Actively cooled consolidator for continuous ultrasonic welding of thermoplastic composites

Abstract

The invention provides a consolidator system (1000) for consolidating a weld seam (1) in a welded material (10), wherein the consolidator system (1000) comprises a consolidator unit (200) and a fluid control system (400), wherein: (A) the consolidator unit (200) comprises a consolidator bottom section (210) and a cooling compartment (220); (B) the consolidator bottom section (210) is configured for physically contacting the weld seam (1), wherein the consolidator bottom section (210) comprises a thermally conductive material; (C) the cooling compartment (220) comprises a fluid inlet (221), a cooling chamber (222), and a fluid outlet (223), wherein the cooling chamber (222) comprises a thermally conductive material; (D) in a first configuration of the consolidator system (1000): (i) the consolidator bottom section (210) is configured in thermal contact with the cooling compartment (220); (ii) the fluid inlet (221), the cooling chamber (222), and the fluid outlet (223) are fluidically coupled; and (iii) the fluid control system (400) is fluidically coupled to the cooling compartment (220) and is configured to flow a cooling fluid (40) through the cooling compartment (220), wherein the consolidator system (1000) is configured to maintain a temperature of the consolidator bottom section (210) at below a temperature T1, wherein T1 is selected from the range of ≤ 100 °C.20

Description

[0001] Actively cooled consolidator for continuous ultrasonic welding of thermoplastic composites

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a consolidator system. The invention further relates to an ultrasonic welding apparatus. Further, the invention relates to a method for ultrasonic welding of a material.

[0004] BACKGROUND OF THE INVENTION

[0005] Cooling systems for a welding apparatus are known in the art. For instance, WO2020239341A1 describes a system and a method for welding two thermoplastic workpieces. The system has an ultrasonic tool, a support and a cooling unit. The ultrasonic tool is designed to generate mechanical vibrations. The system is designed to clamp together the workpieces in the receiving region by means of the ultrasonic tool and the support if at least one fastening portion of the workpieces opposite one another is arranged in the receiving region. The ultrasonic tool is designed to introduce the mechanical vibrations into the fastening portion of the workpieces in order to weld the workpieces in a joining zone. The cooling unit is designed to cool, with cooling fluid, at least a part of the fastening portion of the workpieces and / or a cooling portion of the workpieces directly adjacent to the fastening portion.

[0006] US2023059804A1 describes a system for consolidating materials, comprising a sonotrode configured to direct ultrasonic energy into materials to be consolidated, wherein the materials to be consolidated have both a glass transition temperature and a melting temperature; a non-rigid consolidating material in proximity to the sonotrode, wherein the non-rigid consolidating material and sonotrode define a region therebetween for receiving the materials to be consolidated, and wherein the non-rigid consolidating material has a glass transition temperature that is higher than the glass transition temperature of the materials to be consolidated and a melting temperature that is higher than the melting temperature of the materials to be consolidated.

[0007] US3022814A describes a method of bonding two thermoplastic bodies to one another that comprises: placing the bodies in contact with one another sonically, vibrating contacting portions of the bodies to generate heat therein until the contacting surfaces of the bodies become soft and tacky and fuse to one another, and simultaneously cooling the outer surface of at least one body to induce a flow of heat away from the fused surfaces of the bodies, then terminating the vibration, and completing the cooling of the bond under compression. US2023226775A1 describes a sonotrode for welding a material, the sonotrode comprising a welding section configured for contacting the material, wherein the welding section defines a rounded shape in a cross-section parallel to a longitudinal axis of the sonotrode, wherein the rounded shape approximates a circular sector, wherein the circular sector has a central angle acselected from the range of 25°-300°, and wherein the circular sector has a central radius rcselected from the range of 5-30 mm, and wherein the sonotrode has a width W perpendicular to the longitudinal axis, wherein W is selected from the range of 10- 100 mm.

[0008] SUMMARY OF THE INVENTION

[0009] In order to manufacture (large) multipart structures, it may be needed to join multiple parts together. For example, thermoplastic composites - which may be increasingly used in the aerospace industry - may be joined by applying heat and pressure at the location where the parts are to be joined.

[0010] One of the techniques which may be used for joining parts together is continuous ultrasonic welding. This process may consist of a heating phase (or “vibration phase”) and a cooling phase. In the heating phase of continuous ultrasonic welding, a sonotrode may exert high frequency low amplitude vibrations transversely to a welding interface while applying a (constant) static pressure and moving the sonotrode along a to-be-welded seam / area (herein also: “along a welding line” or “weld line”). The vibrations may introduce surface and viscoelastic friction at the weld interface, which may heat up the welding interface, and may thereby join the two parts together by promoting interm olecular diffusion across the welding interface. During the cooling phase the just heated-up material may (be allowed to) cool down, optionally under the application of pressure.

[0011] However, the sonotrode may provide high interface temperatures and a large heat-affected zone, which may be detrimental for weld quality of the weld seam and may degrade the adherends themselves, especially when the temperature of the adherends and welding interface is not reduced sufficiently (quickly) in the cooling phase to reach a sufficient solidified state of the adherends and welding interface. A sufficient solidified state may typically be reached below the melting temperature or the crystallization temperature or the glass transition temperature of the thermoplastic material. Further, the sonotrode may also heat up sections of the adherends close to the welding interface, and / or may add to the through-the- thickness heating and heat affected zone, which may be detrimental to the adherends. The welded material may retain the increased temperature (at the interface and / or through the thickness) for some time after the sonotrode has moved on along the weld seam. Such retained heat may result in a substantial level of material distortion. For example, the heating may result in local thickness variations, porosity, and squeeze out of thermoplastic material and fibers. This retained heat may even accumulate within the to-be-welded adherends, thereby further reducing weld quality.

[0012] One solution may be to actively cool the welded material. Prior art may describe methods of cooling, wherein a cooling fluid is sprayed on the welded material after the sonotrode has moved a suitable distance away. However, spraying the welded material with a cooling fluid may cause local swelling of the welded material by absorption of the cooling fluid, which may further increase the porosity in the weld seam. Further, with a sprayed cooling fluid, additional processing steps are needed to wipe away and / or evaporate the cooling fluid, thereby reducing productivity. Additionally, such a method of spraying a cooling fluid may require a constant supply of fresh cooling fluid, and may increase the production of waste (in the form of spent cooling fluid) during the production process.

[0013] Another solution may be to apply pressure on the weld seam after welding, wherein the pressure may be maintained until the weld seam has cooled down (to a predetermined temperature). Applying pressure until the material has cooled down sufficiently may consolidate the weld seam, thereby reducing porosity, reducing de-consolidation, and increasing the strength of the weld seam. The pressure may be applied with a consolidator. A consolidator may be a (block of) thermally conductive material, which is aligned with and pressed onto the weld seam behind the sonotrode with a consolidation force, and which may absorb the heat from the weld seam. However, prior art consolidators may heat up (rapidly) during continuous ultrasonic welding, thereby reducing the amount of heat that can be absorbed by the consolidator from the weld seam. Hence, for welding longer seams, such a consolidator may no longer (be able to) cool down the weld seam enough to provide a high-quality weld seam. Additionally, a consolidator may typically be rigid, and may therefore apply uneven pressure or damage the material when the material comprises thickness variations, reducing the quality of the weld seam.

[0014] Hence, it is an aspect of the invention to provide an alternative consolidator system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0015] According to a first aspect, the invention provides a consolidator system for consolidating a weld seam in a welded material. The consolidator system may comprise a consolidator unit and a fluid control system. In embodiments, the consolidator unit may comprise a consolidator bottom section and a cooling compartment. The consolidator bottom section may especially be configured for physically contacting the weld seam (at a bottom section first side). Further, the consolidator bottom section may comprise a thermally conductive material. In embodiments, the cooling compartment may comprise a fluid inlet, a cooling chamber, and a fluid outlet. In (such) embodiments, (at least) the cooling chamber may comprise a thermally conductive material. Further, in a first configuration of the consolidator system, the consolidator bottom section may be configured in thermal contact with the cooling compartment. Additionally or alternatively, in the first configuration of the consolidator system, the fluid inlet, the cooling chamber, and the fluid outlet may be fluidically coupled. Further, in the first configuration of the consolidator system, the fluid control system may be fluidically coupled to the cooling compartment, and may be configured to flow a cooling fluid through the cooling compartment (especially through the cooling chamber via the fluid inlet and the fluid outlet). As such, in the first configuration of the consolidator system, the consolidator system may be configured to maintain a temperature of the consolidator bottom section (especially of the bottom section first side) at below a temperature Ti. In embodiments, Ti may be selected from the range of < 100 °C.

[0016] Hence, in specific embodiments, the invention may provide a consolidator system for consolidating a weld seam in a welded material, wherein the consolidator system comprises a consolidator unit and a fluid control system, wherein: (A) the consolidator unit comprises a consolidator bottom section and a cooling compartment; (B) the consolidator bottom section is configured for physically contacting the weld seam, wherein the consolidator bottom section comprises a thermally conductive material; (C) the cooling compartment comprises a fluid inlet, a cooling chamber, and a fluid outlet, wherein the cooling chamber comprises a thermally conductive material; and (D) in a first configuration of the consolidator system: (i) the consolidator bottom section is configured in thermal contact with the cooling compartment; (ii) the fluid inlet, the cooling chamber, and the fluid outlet are fluidically coupled; and (iii) the fluid control system is fluidically coupled to the cooling compartment and is configured to flow a cooling fluid through the cooling compartment, wherein the consolidator system is configured to maintain a temperature of the consolidator bottom section at below a temperature Ti, wherein Ti is selected from the range of < 100 °C.

[0017] Such a consolidator system may - in the first configuration - be actively cooled with a cooling fluid. Hence, such a consolidator system may be especially suitable for continuous ultrasonic welding of longer weld seams, where the temperature of the consolidator unit may be maintained at or below a temperature at which a good-quality weld seam is obtained, facilitating the production of a weld seam having a consistent quality, even after longer welding times. Further, the cooling fluid in such a consolidator system may be recycled, thereby providing a circular and sustainable process. Additionally, with such a consolidator system, the cooling fluid may not be in (direct) contact with the welded material, thereby avoiding swelling in the welded material.

[0018] The consolidator system may especially be used to consolidate a weld seam. Herein, the term “consolidate a weld seam”, and similar terms, especially relates to a process wherein pressure is applied onto a weld seam while simultaneously cooling down the weld seam (by absorbing heat from the weld seam), to provide a compressed weld seam having low porosity, wherein after the consolidation process the material(s) comprised in the weld seam may have hardened into a single (semi-)solid material or composite. Hence, the weld seam may be provided between two pieces of the same material, or between two different materials.

[0019] In embodiments, the material may be any to-be-welded material. In embodiments, the (welded) material may comprise one or more of metals, thermoplastic composites, thermoset composites, and elastomers. Especially, in embodiments, the material may comprise a polymer composite material. In specific embodiments, the material may comprise a thermoplastic, especially a (fiber-reinforced) thermoplastic composite. In further embodiments, the material may comprise a thermoplastic composite, such as a thermoplastic composite laminate. In particular, the material may comprise a thermoset (composite) with a thermoplastic coupling layer co-cured on the surface adherend, i.e., a thermoset (composite) that may be welded through a thermoplastic coupling layer. Hence, the material may comprise a thermoset composite with a co-cured layer of thermoplastic material, known as a coupling layer, on at least one side of the composite. The material may also be referred to herein as an “adherend”. The term “material” may herein also refer to a plurality of (different) materials. In further embodiments, the material may comprise an aerospace material or an automotive material, especially an aerospace material, or especially an automotive material. Hence, in specific embodiments, the material may comprise a thermoplastic composite or a thermoset composite with a co-cured layer of thermoplastic material on at least one side of the composite. A thermoplastic composite may provide the benefit that - upon application of ultrasonic vibrations during the ultrasonic welding - the temperature in two pieces of the thermoplastic composite may be increased to above a glass transition temperature and / or melting temperature, causing the (viscous and / or melted) thermoplastic composite of both pieces to locally flow together into a single thermoplastic composite (in the weld seam), such that the weld seam may have (essentially) the same properties as the remainder of the material after consolidation.

[0020] As described above, the consolidator system may comprise a consolidator unit and a fluid control system. In embodiments, the consolidator unit may be provided separately from the fluid control system (and may be coupled to any fluid control system known in the art). Hence, in specific embodiments, the invention may provide a consolidator unit for consolidating a weld seam in a welded material, wherein the consolidator unit comprises a consolidator bottom section and a cooling compartment, wherein: (A) the consolidator bottom section is configured for physically contacting the weld seam, wherein the consolidator bottom section comprises a thermally conductive material; (B) the cooling compartment comprises a fluid inlet, a cooling chamber, and a fluid outlet, wherein the cooling chamber comprises a thermally conductive material; and (C) in a first configuration of the consolidator unit: (i) the consolidator bottom section is configured in thermal contact with the cooling compartment; (ii) the fluid inlet, the cooling chamber, and the fluid outlet are fluidically coupled; and (iii) the cooling compartment is configured to receive a (flowing) cooling fluid, wherein the consolidator unit is configured to maintain a temperature of the consolidator bottom section at below a temperature Ti, wherein Ti is selected from the range of < 100 °C.

[0021] The consolidator unit may have (largest) (orthogonal) dimensions length Lc, width Wc, and height He. Hence, the (largest) length Lc may be configured perpendicular to both the (largest) width Wc and (largest) height He, wherein the width Wc may further be configured perpendicular to the height He. In embodiments, the (largest) length Lc of the consolidator unit may be larger than the (largest) width Wc of the consolidator unit, Lc > Wc. Further, in embodiments, the (largest) length Lc of the consolidator unit may be larger than the (largest) height He of the consolidator unit, Lc > He. Hence, in embodiments, the consolidator unit may be elongated. Especially, in embodiments, the consolidator unit may have an axis of elongation AL, wherein the consolidator unit may be elongated along the axis of elongation AL. During operation of the consolidator unit (in a continuous ultrasonic welding process), the axis of elongation AL may especially be configured (roughly) parallel to the weld seam and / or (roughly) parallel to a welding direction. Hence, the consolidator unit may have the (largest) consolidator length Lc along the weld seam. Additionally, in embodiments, during operation of the consolidator unit, the consolidator unit may have the (largest) width Wc in a direction perpendicular to the weld seam and parallel to a surface of the material (especially of the weld seam). Further, in embodiments, during operation of the consolidator unit, the consolidator unit may have the (largest) height He in a direction parallel to a (surface) normal of the material, especially of the weld seam.

[0022] In embodiments, the (largest) consolidator length Lc may be selected from the range of > 3 cm, such as from the range of > 4.5 cm, especially from the range of > 6 cm, like from the range of > 8 cm. Additionally or alternatively, the (largest) consolidator length Lc may be selected from the range of < 20 cm, such as from the range of < 17.5 cm, especially from the range of < 15 cm, like from the range of < 10 cm.

[0023] Further, in embodiments, the (largest) consolidator width Wc may be selected from the range of > 1.0 cm, such as from the range of > 2 cm, especially from the range of > 3 cm, like from the range of > 4 cm. Additionally or alternatively, the (largest) consolidator width Wc may be selected from the range of < 17.5 cm, such as from the range of < 15 cm, especially from the range of < 10 cm, like from the range of < 8 cm. Further, in embodiments, the (largest) consolidator width Wc may be selected from the range of Wc < Lc, such as from the range of Wc < 0.9*Lc, especially from the range of Wc < 0.8*Lc, like from the range of Wc < 0.7*Lc. Additionally or alternatively, the (largest) consolidator width Wc may be selected from the range of Wc > 0.1 *Lc, such as from the range of Wc > 0.2*Lc, especially from the range of Wc > 0.3*Lc, like from the range of Wc > 0.4*Lc.

[0024] In embodiments, the (largest) consolidator height He may be selected from the range of > 1 cm, such as from the range of > 1.5 cm, especially from the range of > 2 cm, like from the range of > 2.5 cm. Additionally or alternatively, the (largest) consolidator height He may be selected from the range of < 15 cm, such as from the range of < 10 cm, especially from the range of < 8 cm, like from the range of < 6 cm. Further, in embodiments, the (largest) consolidator height He may be selected from the range of He < 0.8*Lc, such as from the range of He < 0.7*Lc, especially from the range of He < 0.6*Lc, like from the range of He < 0.5*Lc. Additionally or alternatively, the (largest) consolidator height He may be selected from the range of He > 0.1 *Lc, such as from the range of He > 0.2*Lc, especially from the range of He > 0.25*Lc, like from the range of He > 0.3*Lc.

[0025] In embodiments, the consolidator unit may comprise a consolidator bottom section. The consolidator bottom section may comprise, especially consist of, a thermally conductive material. The thermally conductive material may especially have a thermal conductivity of > 20 W / (m*K), such as > 30 W / (m*K), especially > 50 W / (m*K), like > 75 W / (m*K). Further, the thermally conductive material may have a thermal conductivity of > 100 W / (m*K), such as > 150 W / (m*K), especially > 200 W / (m*K), like > 250 W / (m*K). In embodiments, the thermally conductive material may comprise (an alloy of) one or more of copper, aluminum, silver, gold, silicon carbide, aluminum nitride, aluminum oxide, boron nitride, aluminum silicon carbide, beryllium oxide, a silicon carbide composite, aluminum silicon carbide, magnesium, a copper tungsten alloy, a copper molybdenum carbide, carbon, diamond, (other) ceramics, and graphite. Especially, in embodiments, the thermally conductive material (of the consolidator bottom section) may comprise one or more of gold, silver, copper, aluminum, and alloys thereof. In embodiments, the thermally conductive material (of the consolidator bottom section) may at least comprise copper. In specific embodiments, the thermally conductive material may comprise one or more of gold, silver, copper, aluminum, and alloys thereof, wherein the thermally conductive material may have a thermal conductivity selected from the range of > 75 W / (m*K). Such a thermally conductive material may be capable of (quickly) absorbing heat from the weld seam, and conducting this heat away from the weld seam. Further, a thermally conductive material comprising one or more of gold, silver, copper, aluminum, and alloys thereof may have a relatively high hardness, improving the resistance of the consolidator bottom section to wear and facilitating the addition of threaded holes to the consolidator bottom section. The addition of threaded holes may provide the benefit that the consolidator unit may be provided as a modular system, wherein the consolidator bottom section and / or the cooling compartment may be easily exchanged depending on the material to be welded (see below), and wherein the modular consolidator unit may be relatively easily assembled into e.g. the first configuration via one or more bolts and / or screws (see also below).

[0026] In embodiments, the consolidator bottom section may comprise a bottom section first side and a bottom section second side, wherein the bottom section second side may be configured opposite the bottom section first side. The bottom section first side may, during operation of the consolidator unit and / or system (in a continuous ultrasonic welding process), especially be configured in physical contact with the weld seam. That is, during operation, the consolidator system, especially the consolidator unit, may be configured to exert pressure on the weld seam (to consolidate the weld seam) via the bottom section first side. Further, in embodiments, the consolidator unit may be configured to absorb heat from the weld seam via the bottom section first side. Hence, in embodiments, the bottom section first side may be configured in thermal contact with the weld seam. An element may be considered in “thermal contact” with another element if it can exchange energy through the process of heat. Hence, the elements may be thermally coupled. In embodiments, thermal contact can be achieved by physical contact. Further, in embodiments, thermal contact may be achieved via a thermally conductive material. In embodiments, the bottom section first side may be planar (or “flat”). Such a planar bottom section first side may be beneficial for welding of flat materials. In embodiments wherein the bottom section first side is planar, the edges of the bottom section first side may be (slightly) rounded. Rounded edges may prevent the bottom section first side from damaging the material. Alternatively, in embodiments, the bottom section first side may be curved. Especially, the bottom section first side may have a curvature in a plane perpendicular to the axis of elongation AL (of the consolidator unit). In embodiments, the curvature of the bottom section first side may have a radius of curvature Rc. The radius of curvature Rc may be determined by (virtually) extrapolating the curvature of the bottom section first side into an imaginary circle, and then calculating the radius of the imaginary circle. Hence, the radius of curvature Rc may be the radius of a circle having the same (local) curvature as the bottom section first side. In embodiments, the radius of curvature Rc may be selected from the range of > 30 cm, such as from the range of > 40 cm, especially from the range of > 50 cm, like from the range of > 75 cm, though smaller values are herein not excluded. Further, in embodiments, the radius of curvature Rc may be selected from the range of > 100 cm, such as from the range of > 150 cm, especially from the range of > 175 cm, like from the range of > 200 cm. Additionally or alternatively, in embodiments, the radius of curvature Rc may be selected from the range of < 700 cm, such as from the range of < 600 cm, especially from the range of < 500 cm. Further, in embodiments, the radius of curvature Rc may be selected from the range of < 350 cm, such as from the range of < 300 cm, especially from the range of < 250 cm. Hence, in specific embodiments, the consolidator unit may have an axis of elongation AL, wherein the bottom section first side may have a curvature in a plane perpendicular to the axis of elongation AL, wherein the curvature may have a radius of curvature Rc selected from the range of > 100 cm. A bottom section first side having a curvature may facilitate the (continuous) ultrasonic welding of curved materials. For instance, the material may be used to create a (partially) rounded object, wherein the to-be-welded material may be placed in a curved mold or frame, such that upon welding, the material may adhere to the shape of the curved mold or frame to provide the (partially) rounded object. In such embodiments, a consolidator unit having a curved bottom section first side, wherein the radius of curvature Rc may correspond to a radius of curvature of the curved mold or frame, may facilitate good physical contact between the bottom section first side and the (to-be-welded) material.

[0027] Additionally or alternatively, in embodiments, the bottom section first side may be curved in a plane parallel to the axis of elongation AL (of the consolidator unit). Hence, in embodiments, the bottom section first side may have a second curvature in a plane parallel to the axis of elongation AL. In embodiments, the second curvature of the bottom section first side may have a second radius of curvature Rc2 selected from the range of > 30 cm, such as from the range of > 40 cm, especially from the range of > 50 cm, like from the range of > 75 cm, though smaller values are herein not excluded. Further, in embodiments, the second radius of curvature Rc2 may be selected from the range of > 100 cm, such as from the range of > 150 cm, especially from the range of > 175 cm, like from the range of > 200 cm. Additionally or alternatively, in embodiments, the second radius of curvature Rc2 may be selected from the range of < 700 cm, such as from the range of < 600 cm, especially from the range of < 500 cm. Further, in embodiments, the radius of curvature Rc may be selected from the range of < 350 cm, such as from the range of < 300 cm, especially from the range of < 250 cm. Hence, in embodiments, the bottom section first side may have one or more of a (first) curvature in a plane perpendicular to the axis of elongation AL having a radius of curvature Rc, and a second curvature in a plane parallel to the axis of elongation AL having a second radius of curvature RC2. That is, the bottom section first side may be curved in one or two (perpendicular) directions. Alternatively, the bottom section first side may be flat (or “planar”).

[0028] In embodiments, during operation of the consolidator system, the consolidator bottom section (especially the bottom section first side) may be configured in physical (and thermal) contact with the material, especially with the weld seam, over a first contact area CAi. In embodiments, the first contact area CAi may be equal to a surface area of the bottom section first side, though this need not be the case.

[0029] Further, in embodiments, the consolidator bottom section may be configured to be in thermal contact with the cooling compartment at a bottom section second side. In embodiments, the bottom section second side may have a second surface area SA2. In embodiments, the consolidator bottom section may have a rectangular shape, such that CAi = SA2. Alternatively, the consolidator bottom section may have tapered shape, such as an (acute or right) trapezoid shape. In such embodiments, one of the first contact area CAi and the second surface area SA2 may be larger than the other of the first contact area CAi and the second surface area SA2. Hence, in embodiments, CA1 / SA2 > 1, such as CA1 / SA2 > 1.1, especially CA1 / SA2 > 1.25, like CA1 / SA2 > 1.5. Additionally or alternatively, in embodiments, CA1 / SA2

[0030] < 4, such as CA1 / SA2 < 3, especially CA1 / SA2 < 2.5, like CA1 / SA2 < 2. Further, in embodiments, CA1 / SA2 < 1, such as CA1 / SA2 < 0.9, especially CA1 / SA2 < 0.75, like CA1 / SA2

[0031] < 0.5. Additionally or alternatively, in embodiments, CA1 / SA2 > 0.1, such as CA1 / SA2 > 0.2, especially CA1 / SA2 > 0.3, like CA1 / SA2 > 0.4. Hence, in specific embodiments, the consolidator bottom section may be configured to be in thermal contact with the cooling compartment at a bottom section second side, wherein during operation of the consolidator system the consolidator bottom section may be configured in physical contact with the weld seam over a first contact area CAi, wherein the bottom section second side may have a second surface area SA2, and wherein CA1 / SA2 < 1. Such a configuration of the consolidator bottom section may facilitate that the contact area CAi with the weld seam may be smaller than an area of the bottom section second side, thereby reducing friction with the (material in the) weld seam while maintaining or increasing a surface area for thermal conduction of the heat from the weld seam to the cooling compartment.

[0032] In embodiments, the bottom section first side may be configured to be in physical contact with the material, especially the weld seam, over a first contact length Lciconfigured parallel to the consolidator length Lc (and the weld seam). In embodiments, the first contact length Lcimay be selected from the range of > 1.0 cm, such as from the range of > 2 cm, especially from the range of > 3 cm, like from the range of > 4 cm. Additionally or alternatively, the first contact length Lcimay be selected from the range of < 17.5 cm, such as from the range of < 15 cm, especially from the range of < 10 cm, like from the range of < 8 cm. Further, in embodiments, the bottom section first side may be configured in physical contact with the material, especially the weld seam, over a first contact width Wciconfigured parallel to the consolidator width Wc (and perpendicular to the weld seam). In embodiments, the first contact width Wcimay be selected from the range of > 0.5 cm, such as from the range of > 1 cm, especially from the range of > 2 cm, like from the range of > 3 cm. Additionally or alternatively, the first contact width Wcimay be selected from the range of < 10 cm, such as from the range of < 8 cm, especially from the range of < 6 cm, like from the range of < 5 cm. In embodiments, the first contact length Lciand first contact width Wcimay together determine the first contact area CAi, wherein CAi = Lci*Wci.

[0033] In embodiments, the consolidator unit may be a monolithic consolidator unit, i.e., in embodiments the consolidator unit may be formed from a single (thermally conductive) component comprising (both) the consolidator bottom section and the cooling compartment. Alternatively, the consolidator unit may be formed from multiple components which may be joined together (in the first configuration) to form the consolidator unit. Hence, in embodiments, the consolidator bottom section may be a first component of the consolidator unit, and the cooling compartment may be a second component of the consolidator unit. In (such) embodiments, the consolidator bottom section may be attached to the cooling compartment to form the consolidator unit in the first configuration, and may be removed from the cooling compartment for e.g. storage and / or cleaning of the consolidator unit. In embodiments, attaching the consolidator bottom section to the cooling compartment may be facilitated by one or more fixating elements, configured to attach (or “fixate”) the consolidator bottom section to the cooling compartment. Hence, in embodiments, the consolidator system, especially the consolidator unit, may comprise one or more fixating elements. The fixating elements may be selected from the group comprising screws, bolts, clamps, glue, (doublesided) tape, and straps. Further, in embodiments, one or more of the consolidator bottom section and the cooling compartment may comprise fixating element receivers, configured to receive and / or guide the fixating elements to facilitate fixating the consolidator bottom section to the cooling compartment. In specific embodiments, the fixating elements may comprise bolts, and the fixating element receivers may comprise threaded holes, wherein the threaded holes may be configured in the consolidator bottom section and the cooling compartment.

[0034] In embodiments, the consolidator bottom section may thus be attached to and removed from the cooling compartment with the one or more fixating elements. Hence, the consolidator bottom section may be configured removably attachable to the cooling compartment. Especially, the consolidator bottom section may be removed from the cooling compartment, wherein the consolidator bottom section may afterwards be (re-)attached to the cooling compartment (to form e.g. the consolidator unit in the first configuration). Hence, in specific embodiments, the consolidator bottom section may be configured removably attachable to the cooling compartment. A consolidator bottom section that is removably attachable to the cooling compartment may facilitate that the consolidator bottom section may easily be exchanged for a different size and / or type of consolidator bottom section. Hence, the same consolidator system and / or consolidator unit may be used for ultrasonic welding of a wide range of materials and / or shaped parts, wherein only the consolidator bottom section may need to be exchanged to accommodate a different material and / or part. Such a consolidator system and / or unit may therefore be more versatile and economical, as no separate systems are needed for each part and / or material.

[0035] Turning to the cooling compartment, the cooling compartment may comprise a cooling compartment first side and a cooling compartment second side, wherein the cooling compartment second side may especially be configured opposite the cooling compartment first side. In embodiments, the cooling compartment may be configured in thermal (and physical) contact with the consolidator bottom section at the cooling compartment second side. Further, in embodiments, the cooling compartment second side may have a first surface area SAi. In embodiments, the cooling compartment second side may have the same shape and size as the bottom section second side, such that SAi = SA2. In further embodiments, SAi and SA2 may differ less than 20% (relative to the largest of SAi and SA2), such as less than 10%, especially less than 5%. Yet, in embodiments, the cooling compartment second side may be larger than the bottom section second side. Hence, in embodiments, SAi > SA2, such as SAi > I. SA2, especially SAi > 1.25*SA2, like SAi > 1.5*SA2. Additionally or alternatively, in embodiments, SAi < 5*SA2, such as SAi < 4*SA2, especially SAi < 3*SA2, like SAi < 2.5*SA2. In embodiments wherein SAi > SA2, SAi (and / or the surface area of the cooling compartment first side) may especially be determined by SAi = Lc*Wc. Yet, in (other) embodiments, the bottom section second side may be larger than the cooling compartment second side. Especially, in embodiments, SA2 > SAi, such as SA2 > l.l*SAi, especially SA2 > 1.25*SAi, like SA2 > 1.5*SAi. Additionally or alternatively, in embodiments, SA2 < 5*SAi, such as SA2 < 4*SAi, especially SA2 < 3*SAi, like SA2 < 2.5*SAi. In such embodiments, the bottom section second side may be determined by SA2 = Lc*Wc.

[0036] In embodiments, the cooling compartment may comprise a fluid inlet, a cooling chamber, and a fluid outlet. The fluid inlet and fluid outlet may (each) comprise an opening in the cooling compartment first side configured extending towards (and intersecting) the cooling chamber. Hence, in embodiments, the fluid inlet and the fluid outlet may comprise openings. In specific embodiments, the fluid inlet and / or the fluid outlet may be an opening. Alternatively, the fluid inlet and / or the fluid outlet may (further) comprise an adapter element. The adapter element may be configured to provide a watertight seal with the opening of the fluid inlet and / or fluid outlet at an adapter element first end, and to provide a connection point for a fluid carrier system (e.g. tubing) at an adapter element second end. Hence, the adapter element may be configured to facilitate attaching a fluid carrier system (such as e.g. tubing) to the opening of the fluid inlet and / or fluid outlet. Suitable adapter elements are known to the person skilled in the art, and will not be described in detail here.

[0037] The fluid inlet and fluid outlet may (in the first configuration) especially be configured fluidically coupled to the cooling chamber. Herein, the term “fluidically coupled”, and similar terms, may relate to an arrangement of items or features along or through which a fluid flow path may be defined. Hence, a fluid, such as the cooling fluid, may flow from the fluid inlet, through the cooling chamber, to the fluid outlet (in the first configuration of the consolidator unit). In embodiments, the cooling chamber may (thus) be (at least partially) hollow. In embodiments, the “hollow (center)” of the cooling chamber may be defined by one or more cooling chamber walls. Especially, in embodiments, the cooling chamber may comprise a “hollow center” configured surrounded by (at least four, especially at least six) cooling chamber walls, wherein at least one of the cooling chamber walls may comprise the openings of the fluid inlet and / or fluid outlet. Alternatively, the cooling chamber may comprise a thermally conductive material comprising a depression (or “basin”), wherein in the first configuration the thermally conductive material comprising the basin may be configured at least partially covered by (another part of) the cooling compartment, wherein the basin is configured fluidically coupled to the fluid inlet and fluid outlet in the first configuration. Hence, in embodiments, the cooling chamber (such as the one or more cooling chamber walls) may comprise a thermally conductive material. This may be the same (type of) thermally conductive material as comprised by the consolidator bottom section, yet this need not be the case. In embodiments, the cooling chamber may comprise a thermally conductive material, wherein the thermally conductive material may comprise (an alloy of) one or more of copper, aluminum, silver, gold, silicon carbide, aluminum nitride, aluminum oxide, boron nitride, aluminum silicon carbide, beryllium oxide, a silicon carbide composite, aluminum silicon carbide, magnesium, a copper tungsten alloy, a copper molybdenum carbide, carbon, diamond, (other) ceramics, and graphite. In specific embodiments, the cooling chamber may comprise a thermally conductive material, wherein the thermally conductive material may comprise one or more of gold, silver, copper, aluminum, and alloys thereof.

[0038] In embodiments, the cooling chamber may further comprise one or more cooling protrusions. In embodiments, the one or more cooling protrusions may especially comprise (such as consist of) the thermally conductive material. The one or more cooling protrusions may be configured on an interior of at least one of the one or more cooling chamber walls and / or in the basin. Further, the one or more cooling protrusions may be configured perpendicular to the cooling compartment second side, i.e., the one or more cooling protrusions may be configured extending into the “hollow (center)” and / or basin of the cooling chamber (in the first configuration of the consolidator unit). In embodiments, the one or more cooling protrusions may comprise ridges, such as especially ridges running along a flow path of the cooling fluid. In specific embodiments, the ridges may span the (hollow part of) the cooling chamber (in the first configuration), wherein the ridges may form a plurality of cooling channels in the cooling chamber. Additionally or alternatively, in embodiments, the cooling protrusions may comprise needles (or “pins” or “spikes” or “fins”). In embodiments, the needles may span the height of the “hollow (center)” and / or basin of the cooling chamber. Further, in embodiments, the “hollow (center)” and / or basin of the cooling chamber may have an internal cooling chamber height Hccperpendicular to the cooling compartment second side in the first configuration, wherein the one or more cooling protrusions may have a cooling protrusion height Hcpperpendicular to the cooling compartment second side, and wherein Hcc > Hcp. In embodiments, during operation of the consolidator system and / or consolidator unit, the one or more cooling protrusions may be configured in thermal contact with the cooling fluid. That is, during operation of the consolidator system and / or consolidator unit, the cooling fluid may flow past the one or more cooling protrusions (and towards the fluid outlet). Hence, in specific embodiments, the cooling chamber may comprise one or more cooling protrusions, wherein in the first configuration of the consolidator system the one or more cooling protrusions may be configured in thermal contact with the cooling fluid. Such cooling protrusions may provide the benefit that the (thermal) contact area between (the thermally conductive material of) the cooling chamber and the cooling fluid may be increased. Hence, such cooling protrusions may allow more heat to be transferred (from the consolidator bottom section) to the cooling fluid in the same amount of time, thereby improving the (cooling) performance of the consolidator unit.

[0039] In embodiments, during operation of the consolidator system and / or consolidator unit, the consolidator unit may be configured to absorb heat from the weld seam, and to transfer at least part of that heat to the cooling fluid (flowing through the cooling compartment), thereby reducing the temperature at the surface of and / or within the weld seam. Hence, in embodiments, the consolidator system, especially the consolidator unit, may be configured to reduce at least a surface temperature of the weld seam. Here, the surface temperature refers to the temperature measured by placing e.g. a thermocouple onto the surface of a material, and / or the temperature measured using a (hand-held) infrared thermometer / pyrometer or infrared camera pointed towards the surface to be measured. In embodiments, the consolidator unit may (during operation) be configured to reduce the surface temperature of the weld seam by at least 5 °C, such as by at least 10 °C, especially by at least 15 °C, like by at least 20 °C. Further, in embodiments, the consolidator unit may (during operation) be configured to reduce the surface temperature of the weld seam by at least 30 °C, such as by at least 40 °C, especially by at least 50 °C, like by at least 75 °C. Additionally or alternatively, in embodiments, the consolidator unit may (during operation) be configured to reduce the surface temperature of the weld seam by at most 300 °C, such as by at most 200 °C, especially by at most 150 °C, like by at most 100 °C. The reduction in surface temperature may depend on the operational parameters used. For instance, at slower (ultrasonic) welding speeds, the surface temperature reduction which may be obtained with the consolidator unit may be higher than at faster welding speeds. Similarly, the surface temperature reduction may depend on the material that is welded, as the thermal conductivity of material may differ. In one example, a weld seam of 485 mm may be provided in a material via ultrasonic welding with a rounded sonotrode (see below) having a welding section with a width of 16 mm and a radius of curvature Rc,sof 17.5 mm in a plane parallel to the weld seam. The sonotrode may apply (ultrasonic) vibrations having a frequency of 20 kHz and a peak-to-peak vibrational amplitude of 80 pm to the material to provide the weld seam, wherein the sonotrode may weld the material at a speed of 6 mm / s and with a welding force of 1000 N. Further, a consolidator unit may be placed behind the sonotrode at a shortest (edge-to-edge) distance di (see below) between the sonotrode and the consolidator unit of 2 mm, wherein the consolidator unit may apply a consolidation force of 1024 N, and wherein the consolidator unit may be in contact with the material over a width Wciof 1.6 cm and a length Lciof 4 cm. In such embodiments, an average reduction in surface temperature of the weld seam over the weld seam length of 485 mm may be > 60 °C. Hence, in specific embodiments, during operation the consolidator unit may be configured to reduce a surface temperature of the weld seam by at least 20 °C. Such a temperature reduction may facilitate reducing the temperature of the (surface of the) weld seam to below e.g. a melting temperature and / or crystallization temperature and / or glass transition temperature with the consolidator unit (while maintaining a pressure on the material), thereby providing a solid(ified) weld seam having low porosity and flow.

[0040] In embodiments, during operation of the consolidator system, the consolidator unit may further be configured to reduce an average temperature of the weld seam. Herein, the average temperature of the weld seam may especially refer to the average temperature of the weld seam over a thickness of the weld seam (and in a direction perpendicular to the bottom section second side). In embodiments, the consolidator unit may (during operation) be configured to reduce the average temperature of the weld seam by at least 3 °C, such as by at least 5 °C, especially by at least 10 °C, like by at least 15 °C. Further, in embodiments, the consolidator unit may (during operation) be configured to reduce the average temperature of the weld seam by at least 20 °C, such as by at least 35 °C, especially by at least 50 °C, like by at least 60 °C. Hence, in embodiments, during operation the consolidator system, especially the consolidator unit, may be configured to (also) reduce a core temperature of the weld seam (as well as a surface temperature).

[0041] In embodiments, the cooling compartment may be formed from a single component. For instance, in embodiments, the cooling compartment may be formed from a single block of thermally conductive material, wherein the cooling chamber, fluid inlet, fluid outlet, and optionally the one or more cooling protrusions may be formed in the block of thermally conductive material. Alternatively, the cooling compartment may comprise multiple parts which may be (removably) attached in the first configuration of the consolidator system. Especially, the cooling compartment may comprise a cooling compartment top part and a cooling compartment bottom part. The cooling compartment top part and the cooling compartment bottom part may be configured removably attachable. Especially, the cooling compartment top part and the cooling compartment bottom part may be configured attached in the first configuration of the consolidator system, especially of the consolidator unit. In embodiments, the cooling compartment top part and the cooling compartment bottom part may be attached (in the first configuration) with the one or more fixating elements, wherein the cooling compartment top part and the cooling compartment bottom part may comprise fixating element receivers configured to receive the fixating elements.

[0042] In embodiments, the cooling compartment bottom part may comprise (at least part of) the cooling chamber. Especially, in embodiments, the cooling compartment bottom part may (at least) comprise the “hollow (center)” and / or basin of the cooling chamber. Further, in embodiments, the cooling compartment bottom part may comprise at least part of the cooling chamber walls. Additionally, in embodiments, the cooling compartment bottom part may comprise at least part of the one or more cooling protrusions. In specific embodiments, the cooling compartment bottom part may form a single component with the consolidator bottom section, i.e., in embodiments the consolidator bottom section and cooling compartment bottom part may not be removably attached. Alternatively, in embodiments, the consolidator bottom section may be configured removably attachable to the cooling compartment bottom part, wherein the cooling compartment bottom part may further be configured removably attachable to the cooling compartment top part. In embodiments, the cooling compartment top part may comprise the fluid inlet and fluid outlet, such as especially the openings of the fluid inlet and fluid outlet. Hence, in embodiments, the cooling fluid may (during operation of the consolidator system) flow from the cooling compartment top part to the cooling compartment bottom part. As such, the cooling compartment top part and cooling compartment bottom part may be configured to form a watertight seal (around the edges of the cooling compartment) in the first configuration. Such a watertight seal may be provided by a sealing unit. Hence, in embodiments, the cooling compartment may further comprise a sealing unit. The sealing unit may especially be configured between the cooling compartment top part and the cooling compartment bottom part in the first configuration (of the consolidator system and / or unit). Further, the sealing unit may be configured to provide a watertight seal between the cooling compartment top part and the cooling compartment bottom part. In embodiments, the sealing unit may comprise one or more of an O-ring, a gasket, and a waterproof tape. Additionally or alternatively, the sealing unit may comprise a sealing unit material selected from the group comprising silicones, cork, natural rubber, artificial rubbers (e.g. neoprene, EPDM, nitrile, etc.), (fluorinated) polymers (e.g. polytetrafluoroethylene (PTFE)), metals, and composites thereof. Hence, in specific embodiments, the cooling compartment may comprise a cooling compartment top part and a cooling compartment bottom part, wherein the cooling compartment top part and the cooling compartment bottom part may be configured removably attachable, wherein the cooling compartment bottom part may comprise (or “define”) the cooling chamber, wherein the cooling compartment top part may comprise the fluid inlet and fluid outlet, and wherein the cooling compartment may further comprise a sealing unit, wherein in the first configuration the sealing unit may be configured between the cooling compartment top part and the cooling compartment bottom part. A cooling compartment comprising a cooling compartment top part and a cooling compartment bottom part being removably attachable may provide the benefit that a user may relatively easily access the cooling chamber for e.g. cleaning purposes. Further, such a configuration of the cooling compartment may facilitate the use of different fluid control systems (having e.g. different size tubing), as the cooling compartment top part comprising the fluid inlet and fluid outlet may easily be replaced with a cooling compartment top part having larger or smaller openings and / or adapter elements for the fluid inlet and fluid outlet. Hence, the consolidator unit may be modular system which may be adapted to the specific fluid control system used and the (shape and / or type of) material to be welded.

[0043] In embodiments, in the first configuration, the consolidator unit may be fluidically coupled to a fluid control system. In particular, in embodiments, the consolidator system may comprise or be functionally coupled to a fluid control system, especially comprise the fluid control system, or especially be functionally coupled to the fluid control system. The fluid control system may be configured to flow a cooling fluid through the cooling compartment. Especially, the fluid control system may be configured to flow a cooling fluid through the cooling chamber via the fluid inlet and the fluid outlet. In embodiments, the cooling fluid may be selected from the group comprising hydrogen gas, helium (gas), (ambient) air, liquid nitrogen, (demineralized) water, (poly)ethylene glycol (solutions), diethylene glycol (solutions), propylene glycol (solutions), polyalkylene glycols, mineral oils, silicone oils, freons, hydrofluorocarbons (HFCs), and hydrocarbons (e.g. propane and / or isobutane). Especially, the cooling fluid may be a liquid, such as selected from the group comprising liquid nitrogen, (demineralized) water, (poly)ethylene glycol (solutions), diethylene glycol (solutions), propylene glycol (solutions), polyalkylene glycols, mineral oils, silicone oils, freons, hydrofluorocarbons (HFCs), and hydrocarbons (e.g. propane and / or isobutane). In specific embodiments, the cooling fluid may comprise (demineralized) water. (Demineralized) water may be relatively easy to remove in case of spillage (compared to e.g. mineral oils), and may be relatively safe for workers (compared to e.g. HFCs). Further, (demineralized) water may be widely available and relatively easy to recycle and / or dispose of (as no waste treatment may be required). In embodiments, the cooling fluid, such as especially the (demineralized) water, may further comprise one or more additives, e.g. to prevent corrosion and / or algae growth in the cooling fluid.

[0044] The cooling fluid may be configured to absorb heat from the thermally conductive material of the consolidator unit, thereby reducing the temperature of the consolidator unit, especially of the consolidator bottom section. Especially, by flowing the cooling fluid through the cooling compartment, the consolidator system (especially the fluid control system) may be configured to maintain a(n average) temperature of the consolidator bottom section (especially of the bottom section first side) at below a temperature Ti. Hence, the consolidator system may be configured such that during operation, the (average) temperature of the consolidator bottom section (especially of the bottom section first side) may be at most Ti. In embodiments, the consolidator system may further be configured to maintain the temperature of the consolidator bottom section (especially of the bottom section first side) at the temperature Ti (during the continuous ultrasonic welding process). In embodiments, Ti may be selected from the range of < 200 °C, such as from the range of < 150 °C, especially from the range of < 125 °C, like from the range of < 100 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of < 85 °C, such as from the range of < 75 °C, especially from the range of < 50 °C, like from the range of < 40 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of > 0 °C, such as from the range of > 5 °C, especially from the range of > 10 °C, like from the range of > 15 °C. Additionally or alternatively, in embodiments, the material may have a glass transition temperature Tg, a crystallization temperature Tc, and / or a melting temperature Tm, wherein Ti may be selected to be equal to or smaller than one or more of the glass transition temperature Tg, the crystallization temperature Tc, and the melting temperature Tm. Hence, in embodiments, Ti < Tg, such as wherein Tg- Ti > 10 °C, especially Tg- Ti > 20 °C, like Tg- Ti > 30 °C. Additionally or alternatively, in embodiments, Ti < Tc, such as wherein Tc- Ti > 10 °C, especially Tc- Ti > 20 °C, like Tc- Ti > 30 °C. Additionally or alternatively, in embodiments, Ti < Tm, such as wherein Tm- Ti > 10 °C, especially Tm- Ti > 20 °C, like Tm- Ti > 30 °C.

[0045] In embodiments, during operation of the consolidator system, the cooling fluid may absorb heat from the consolidator bottom section (via the cooling chamber). Consequently, the temperature of the cooling fluid may be increased upon flowing from the fluid inlet to the fluid outlet. Especially, the cooling fluid provided to the fluid inlet may have a first temperature Tin, and the cooling fluid received from the fluid outlet may have a second temperature Tout In embodiments, during operation of the consolidator system, Tout > Tin. Especially, in embodiments, Tout- Tin > 0.1 °C, such as Tout - Tin > 0.5 °C, especially Tout- Tin > 1 °C, like Tout - Tin > 2.5 °C. Further, in embodiments, Tout - Tin > 5 °C, such as Tout - Tin > 10 °C, especially Tout - Tin > 15 °C, like Tout - Tin > 20 °C. Additionally or alternatively, in embodiments, Tout- Tin < 100 °C, such as Tout - Tin < 80 °C, especially Tout- Tin < 60 °C, like Tout - Tin < 50 °C. Hence, in specific embodiments, the cooling fluid provided to the fluid inlet may have a first temperature Tin, and the cooling fluid received from the fluid outlet may have a second temperature Tout, wherein during operation of the consolidator system Tout > Tin. Such a temperature difference between cooling fluid entering the cooling compartment and cooling fluid exiting the cooling compartment may (essentially) prevent that the cooling fluid (e.g. water) undergoes a phase change and / or expand significantly in the cooling compartment. As such, the safety of the consolidator system may be improved, as the build-up of pressure in the cooling compartment may be prevented, and fume release may be reduced, especially prevented.

[0046] In embodiments, the fluid control system may be configured to reduce a temperature of the cooling fluid received from the fluid outlet. Hence, in embodiments, the fluid control system may comprise a fluid cooling unit. The fluid cooling unit may especially be configured fluidically coupled (via a fluid carrier system) to the fluid inlet and the fluid outlet in the first configuration of the consolidator system. Especially, in embodiments, the fluid control system, especially the fluid cooling unit, may comprise a cooling unit inlet and a cooling unit outlet, wherein the cooling unit inlet may be fluidically coupled to the fluid outlet of the consolidator unit, and wherein the cooling unit outlet may be fluidically coupled to the fluid inlet of the consolidator unit. Further, during operation of the consolidator system, the fluid cooling unit may in embodiments be configured to: (i) receive a heated cooling fluid from the fluid outlet, (ii) reduce a temperature of the (heated) cooling fluid received from the fluid outlet to provide a cooled cooling fluid, and (iii) provide the cooled cooling fluid to the fluid inlet. In embodiments, the fluid cooling unit may comprise one or more of a (liquid-liquid and / or liquid / gas) heat-exchanger, a vortex tube, fans, and an evaporation tower. Further, in embodiments, the fluid cooling unit may be configured to reduce the temperature of the (heated) cooling fluid received from the fluid outlet by at least 0.1°C, like by at least 0.5 °C, such as by at least 1 °C, especially by at least 2.5 °C, like by at least 5 °C. Further yet, in embodiments, the fluid cooling unit may be configured to reduce the temperature of the (heated) cooling fluid received from the fluid outlet by at least 10 °C, such as by at least 15 °C, especially by at least 20 °C, like by at least 25 °C. Additionally or alternatively, in embodiments, the fluid cooling unit may be configured to control the first temperature Tin of the cooling fluid provided to the fluid inlet. Especially, in embodiments, the fluid cooling unit may be configured to maintain the first temperature Tin at a temperature of < 50 °C, such as at a temperature of < 40 °C, especially at a temperature of < 30 °C, like at a temperature of < 25 °C. In embodiments, the fluid control system, especially the fluid cooling unit, may further comprise one or more pumps, configured to flow and / or pump the cooling fluid through the cooling compartment (and the fluid cooling unit).

[0047] Hence, in specific embodiments, the fluid control system may comprise a fluid cooling unit, wherein in the first configuration the fluid cooling unit may be configured fluidically coupled to the fluid inlet and the fluid outlet, wherein the fluid cooling unit may be configured to receive a heated cooling fluid from the fluid outlet, wherein the fluid cooling unit may be configured to reduce a temperature of the cooling fluid received from the fluid outlet to provide a cooled cooling fluid, and wherein the fluid cooling unit may be configured to provide the cooled cooling fluid to the fluid inlet. Such a fluid control system may facilitate recycling the cooling fluid in the consolidator system. Further, such a fluid control system may improve the cooling capabilities of the consolidator unit by providing a cooled cooling fluid having a higher capacity for heat absorption to the fluid inlet.

[0048] In embodiments, the difference between Tin and Tout may be related to a flow rate of the cooling fluid through the cooling chamber, wherein a higher flow rate may facilitate a smaller difference between Tin and Tout. Hence, in embodiments, the fluid control system, especially the fluid cooling unit, may further be configured to control a flow rate of the cooling fluid through the cooling compartment. In embodiments, the flow rate may be selected from the range of > 2 ml / s, such as from the rate of > 5 ml / s, especially from the range of > 10 ml / s. Additionally or alternatively, the flow rate may be selected from the range of < 400 ml / s, such as from the range of < 200 ml / s, especially from the range of < 150 ml / s, like from the range of < 100 ml / s.

[0049] In embodiments, the fluid control system may comprise a fluid carrier system. The fluid carrier system may be configured to transfer the cooling fluid between the fluid cooling unit and the (fluid inlet and / or fluid outlet of the) consolidator unit. Hence, in embodiments, the fluid carrier system may be configured fluidically and mechanically coupled to the fluid cooling unit and the fluid inlet and fluid outlet of the consolidator unit. In embodiments, the fluid carrier system may especially comprise tubing, comprising a tubing material selected from the group comprising silicones, metals, polymeric materials (e.g. polyurethane, nylon, polyethylene, PVC, etc.), (synthetic) rubbers, fluorinated polymeric materials (e.g. PTFE), fiberglass, and composites thereof. Further, as indicated above, the cooling fluid may in embodiments especially comprise (demineralized) water. Hence, in embodiments, the tubing may be watertight tubing. Further, in embodiments, the fluid control system, the fluid inlet, the cooling chamber, and the fluid outlet may form a watertight fluidic pathway in the first configuration, wherein the fluid control system may be configured to move the cooling fluid along the fluidic pathway during operation of the consolidator system. In specific embodiments, the fluid control system, the fluid inlet, the cooling chamber, and the fluid outlet may form a closed loop, wherein the cooling fluid may be recycled within the closed loop. Alternatively, the fluid control system may be configured to receive cooling fluid from an (external) reservoir (such as e.g. a lake, a stream, or a (rain)water basin, a bucket, the ambient air, a gas cylinder), wherein the fluid control system may further be configured to provide the cooling fluid received from the fluid outlet to the (external) reservoir (or another reservoir) (optionally via the fluid cooling unit). In such embodiment, the fluid control system may further comprise one or more of sedimentation tanks and filters, configured to purify the cooling fluid. Yet, in embodiments, the fluid control system, fluid inlet, cooling chamber, and fluid outlet may especially form a closed loop.

[0050] In embodiments, at least part of the fluid control system may be configured remote from the consolidator unit. Especially, in embodiments, the fluid cooling unit may be configured remote from the consolidator unit. Herein, the term “configured remote”, and similar terms, indicates that two elements are spatially separated by at least 20 cm, such as by at least 50 cm. The fluid cooling unit may thus be configured at a distance from the consolidator unit (during operation of the consolidator system). Especially, the fluid cooling unit may be configured at an (average) distance of > 20 cm, such as > 50 cm, especially > 70 cm, like > 100 cm, from the consolidator unit (during operation of the consolidator system). Hence, in specific embodiments, one or more may apply of: (i) at least part of the fluid control system may be configured remote from the consolidator unit, wherein the cooling fluid may comprise water; and (ii) in the first configuration: (a) the fluid control system, the fluid inlet, the cooling chamber, and the fluid outlet may form a watertight fluidic pathway, and (b) the fluid control system may be configured to move the cooling fluid along the fluidic pathway. Configuring at least part of the fluid control system (such as especially the fluid cooling unit) remote from the consolidator unit may provide the benefit that cooling fluid may not spill over the material (to be welded) upon leakage of the fluid cooling unit. Further, configuring at least part of the fluid control system (such as especially the fluid cooling unit) remote from the consolidator unit may provide the benefit that the heated cooling fluid from the fluid outlet may already be partially cooled down while travelling from the fluid outlet to the fluid cooling unit (via the fluid carrier system), thereby reducing the energy required to reduce the temperature of the cooling fluid in the fluid cooling unit. Additionally, configuring the fluid cooling unit remote may provide the benefit that the fluid cooling unit may not obstruct a sonotrode and / or the consolidator unit during ultrasonic welding.

[0051] In embodiments, the consolidator unit may be configured to be (mechanically and / or) functionally coupled to an ultrasonic welding apparatus. Especially, in embodiments, the consolidator unit may be functionally coupled to an ultrasonic welding apparatus through a connector. Hence, in embodiments, the consolidator system may comprise a connector. The connector may be configured at the cooling compartment first side. Further, in embodiments, the connector may comprise one or more of a universal joint, a hinge, a rod, a ball joint, and a constant-velocity (CV) joint, such as especially a universal joint. In embodiments, the connector may be configured to allow a rotation of the consolidator unit (with respect to the material and / or the weld seam). Especially, the connector may be configured to allow a first rotation of the consolidator unit about a first axis Ai. The first axis Ai may be configured intersecting the connector. That is, the consolidator unit may be configured to rotate about (the joint comprised by) the connector. Further, in embodiments, the first axis Ai may be configured parallel to the bottom section first side (and / or to the bottom section second side). Additionally, during operation of the consolidator system, the first axis Ai may be configured parallel to the weld seam. In embodiments, the first rotation may have a (maximum) first rotation angle ai, wherein the (maximum) first rotation angle on may be the maximum angle about the first axis Ai over which the consolidator unit may be rotated (i.e., the consolidator unit may be configured to be rotated to any angle selected from the range of < on). In embodiments, the first rotation angle on may be selected from the range of > 1°, such as from the range of > 5°, especially from the range of > 10°, like from the range of > 15°, such as from the range of > 20°. Additionally or alternatively, in embodiments, the first rotation angle on may be selected from the range of < 80°, such as from the range of < 60°, especially from the range of < 40°, like from the range of < 30°. In embodiments, the consolidator unit may, from a resting position (configured parallel to the material and / or weld seam), be configured to rotate to an equal degree in both the clockwise and anti -clockwise direction about the first axis Ai. Hence, in embodiments, from a resting position, the consolidator unit may be configured to rotate over ai / 2 degrees in the clockwise direction about the first axis Ai, and over ai / 2 degrees in the anticlockwise direction. Yet, in (other) embodiments, the consolidator unit may be configured to rotate more in one of the clockwise and anti -clockwise direction than in the other of the clockwise anti-clockwise direction. Alternatively, in embodiments, the connector may be a rigid connector (e.g. a rod), wherein the first rotation angle on may be selected from the range of < 1°, such as from the range of < 0.5°, especially from the range of < 0.2°, including (essentially) 0°.

[0052] In embodiments, the connector may further be configured to allow a second rotation of the consolidator unit about a second axis A2. The second axis A2 may be configured intersecting the connector. Further, the second axis A2 may especially be configured parallel to the bottom section first side (and / or to the bottom section second side), and perpendicular to the first axis Ai. In embodiments, the second rotation may have a (maximum) second rotation angle 012, wherein the (maximum) second rotation angle 012 may be the maximum angle about the second axis A2 over which the consolidator system may be rotated (i.e., the consolidator unit may be configured to be rotated to any angle selected from the range of < 012). In embodiments, the second rotation angle 012 may be selected from the range of > 1°, such as from the range of > 5°, especially from the range of > 10°, like from the range of > 15°, such as from the range of > 20°. Additionally or alternatively, in embodiments, the second rotation angle 012 may be selected from the range of < 80°, such as from the range of < 60°, especially from the range of < 40°, like from the range of < 20°. In embodiments, the consolidator unit may, from a resting position (configured parallel to the material and / or weld seam), be configured to rotate to an equal degree in both the clockwise and anti -clockwise direction about the second axis A2. Alternatively, in embodiments, the consolidator unit may be configured to rotate more in one of the clockwise and anti -clockwise direction than in the other of the clockwise anti-clockwise direction. Alternatively, in embodiments, the connector may be a rigid connector (e.g. a rod), wherein the second rotation angle 012 may be selected from the range of < 1°, such as from the range of < 0.5°, especially from the range of < 0.2°, including (essentially) 0°. Yet, especially, the connector may allow a second rotation of the consolidator unit about a second axis A2. Hence, in specific embodiments, the consolidator bottom section may have a bottom section first side for contacting the weld seam, and the consolidator system may comprise a connector, wherein the connector may be configured to allow (i) a first rotation of the consolidator unit about a first axis Ai configured parallel to the bottom section first side, and (ii) a second rotation of the consolidator unit about a second axis A2 configured parallel to the bottom section first side and perpendicular to the first axis AL Such a connector may facilitate that, upon minor differences in thickness of the material, the consolidator unit may rotate to maintain an even pressure on the material, thereby providing a weld seam having a consistent quality, and preventing damage to the material.

[0053] In embodiments, the connector may be configured to prevent a rotation about a third axis A3 configured perpendicular to the first axis Ai and the second axis A2 (and intersecting the connector and the consolidator bottom section). That is, in embodiments, during use of the consolidator system, the connector may be configured to prevent a rotation of the consolidator unit in a plane of the material. Such a configuration may facilitate that the consolidator unit may remain aligned with the weld seam during operation of the consolidator system, such that the length Lc of the consolidator unit may be oriented parallel to the weld seam.

[0054] In embodiments, the connector may further be configured to transfer a consolidation pressure from a pressure-exerting means to the consolidator unit. Additionally or alternatively, the weld seam may be pressed against the consolidator unit (with the consolidation pressure) by a pressure-exerting means, wherein the connector may be configured to maintain a position of the consolidator unit. Hence, the connector may be configured to facilitate applying pressure on the weld seam with the consolidator unit (see also below).

[0055] As indicated above, the consolidator system, especially the consolidator unit, may be applied in an ultrasonic welding apparatus. Hence, according to a further aspect, the invention provides an ultrasonic welding apparatus for welding a material. The ultrasonic welding apparatus may especially comprise a consolidator system and a sonotrode. In embodiments, the consolidator system comprised by the ultrasonic welding apparatus may especially be the consolidator system as defined herein. In embodiments, the consolidator system (of the ultrasonic welding apparatus) may comprise a consolidator unit and a fluid control system (such as the consolidator unit and fluid control system as defined herein). The consolidator unit may especially comprise a consolidator bottom section and a cooling compartment. In embodiments, the consolidator bottom section may be configured for physically contacting a weld seam in the material (at a bottom section first side). Further, the consolidator bottom section may comprise a thermally conductive material. In embodiments, the cooling compartment may comprise a fluid inlet, a cooling chamber, and a fluid outlet. Additionally, the cooling compartment may comprise a thermally conductive material. In embodiments, the sonotrode may comprise a welding section configured for contacting the material. Further, the sonotrode may be configured to (locally) weld the material to provide the weld seam. In embodiments, in a first configuration of the ultrasonic welding apparatus, the consolidator unit may be configured at a shortest distance di from the sonotrode, wherein di may be selected from the range of < 150 mm. Further, in the first configuration of the ultrasonic welding apparatus, the consolidator bottom section may be configured in thermal contact with the cooling compartment. Further yet, in the first configuration of the ultrasonic welding apparatus, the fluid inlet, the cooling chamber, and the fluid outlet may be fluidically coupled. Additionally or alternatively, in the first configuration of the ultrasonic welding apparatus, the fluid control system may be fluidically coupled to the cooling compartment and may be configured to flow a cooling fluid through the cooling compartment (especially through the cooling chamber via the fluid inlet and the fluid outlet). In embodiments, the consolidator system may be configured to maintain a temperature of the consolidator bottom section (especially of the bottom section first side) at below a temperature Ti. In (such) embodiments, Ti may be selected from the range of < 100 °C. Further, in embodiments, the ultrasonic welding apparatus may be configured to apply pressure on the weld seam with the consolidator unit.

[0056] Hence, in specific embodiments, the invention provides an ultrasonic welding apparatus for welding a material, comprising a consolidator system and a sonotrode, wherein: (A) the consolidator system comprises a consolidator unit and a fluid control system, wherein the consolidator unit comprises a consolidator bottom section and a cooling compartment; (B) the consolidator bottom section is configured for physically contacting a weld seam in the material, wherein the consolidator bottom section comprises a thermally conductive material; (C) the cooling compartment comprises a fluid inlet, a cooling chamber, and a fluid outlet, wherein the cooling compartment comprises a thermally conductive material; (D) the sonotrode comprises a welding section configured for contacting the material, wherein the sonotrode is configured to weld the material to provide the weld seam; and (E) in a first configuration of the ultrasonic welding apparatus: (i) the consolidator unit is configured at a shortest distance (di) from the sonotrode selected from the range of < 150 mm; (ii) the consolidator bottom section is configured in thermal contact with the cooling compartment; (iii) the fluid inlet, the cooling chamber, and the fluid outlet are fluidically coupled; (iv) the fluid control system is fluidically coupled to the cooling compartment and is configured to flow a cooling fluid through the cooling compartment, wherein the consolidator system is configured to maintain a temperature of the consolidator bottom section at below a temperature Ti, wherein Ti is selected from the range of < 100 °C; and (v) the ultrasonic welding apparatus is configured to apply pressure on the weld seam with the consolidator unit. Such an ultrasonic welding apparatus may be especially suitable for continuous ultrasonic welding, and may facilitate active cooling of the weld seam under pressure. As such, such an ultrasonic welding apparatus may provide a weld seam having a consistent quality, even after longer welding times. Further, such an ultrasonic welding apparatus may facilitate placing the consolidator unit in close proximity to the sonotrode, thereby providing the benefit that the weld seam may be consolidated by the consolidator unit relatively quickly after welding of the weld seam.

[0057] As indicated above, the consolidator system comprised by the ultrasonic welding apparatus may especially be the consolidator system of the invention. Hence, embodiments relating to the consolidator system as defined above may also apply to the consolidator system of the ultrasonic welding apparatus as defined herein.

[0058] In embodiments, the consolidator system may be configured to maintain a temperature of the consolidator bottom section (especially of the bottom section first side) at below a temperature Ti. In embodiments, Ti may be selected from the range of < 200 °C, such as from the range of < 150 °C, especially from the range of < 125 °C, like from the range of < 100 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of < 85 °C, such as from the range of < 75 °C, especially from the range of < 50 °C, like from the range of < 40 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of > 0 °C, such as from the range of > 5 °C, especially from the range of > 10 °C, like from the range of > 15 °C.

[0059] In embodiments, in the first configuration, the consolidator unit may be configured at a shortest (edge-to-edge) distance di from the sonotrode. Herein, the shortest distance di may especially be the distance from a closest edge of the consolidator unit to a closest edge of the sonotrode. Further, in embodiments, di may be selected from the range of < 200 mm, such as from the range of < 175 mm, especially from the range of < 150 mm, like from the range of < 100 mm. Further, in embodiments, di may be selected from the range of < 75 mm, such as from the range of < 50 mm, especially from the range of < 25 mm, like from the range of < 10 mm. Further yet, in embodiments, di may be selected from the range of < 7.5 mm, such as from the range of < 5 mm, especially from the range of < 2.5 mm, like from the range of < 1 mm, including (essentially) 0 mm. Additionally or alternatively, in embodiments, di may be selected from the range of > 0.5 mm, such as from the range of > 1 mm, especially from the range of > 2 mm, like from the range of > 10 mm.

[0060] In embodiments, the consolidator unit and sonotrode may be configured aligned (or “centered”). This is, in embodiments, the weld seam may have a center axis configured parallel to a welding direction, wherein a center of the consolidator unit and a center of the sonotrode may both be located on the center axis of the weld seam. Hence, looking (straight) down the weld seam, the center of the consolidator unit and the sonotrode may overlap. Alternatively, the consolidator unit and sonotrode may be configured misaligned (or “staggered”). In such embodiments, the center of the sonotrode may be located on the center axis of the weld seam, and the center of the consolidator unit may be configured at a distance d2 from the center axis of the weld seam. Hence, the center of the consolidator unit may be configured at a distance d2 from the center of the sonotrode (in a direction perpendicular to the welding direction). In embodiments, the distance d2 may be selected from the range of < 20 mm, such as from the range of < 15 mm, especially from the range of < 10 mm, like from the range of < 5 mm. Additionally or alternatively, the distance d2 may be selected from the range of > 0.1 mm, such as from the range of > 0.5 mm, especially from the range of > 1 mm, like from the range of > 2 mm. Hence, in embodiments, the consolidator unit may have an offset with respect to the sonotrode.

[0061] In embodiments, the ultrasonic welding apparatus may be configured to apply pressure on the weld seam with the consolidator unit. Further, in embodiments, the ultrasonic welding apparatus may comprise a support platform configured to support the material (during welding). The support platform and / or the consolidator unit (via the connector) may be configured functionally coupled to a pressure-exerting means, such as e.g. a pneumatic cylinder. In embodiments, the pressure-exerting means may be configured to apply pressure on the weld seam by pressing one of the support platform and the consolidator unit against the other of the support platform and the consolidator unit. Alternatively, the pressure-exerting means may be functionally coupled to a (moving) anvil, wherein the pressure-exerting means may be configured to press the anvil to the consolidator unit. Hence, the weld seam may be compressed (and / or consolidated) between the consolidator unit and the support platform. In embodiments, the ultrasonic welding apparatus may be configured to consolidate the weld seam (by applying a pressure on the weld seam with the consolidator unit) with a consolidation pressure selected from the range of > 0.2 MPa, such as from the range of > 0.4 MPa, especially from the range of > 0.7 MPa, like from the range of > 1.0 MPa, such as from the range of > 1.3 MPa. Additionally or alternatively, in embodiments, the ultrasonic welding apparatus may be configured to consolidate the weld seam with a consolidation pressure selected from the range of < 5.0 MPa, such as from the range of < 4.0 MPa, especially from the range of < 3.0 MPa, like from the range of < 2.0 MPa.

[0062] Turning to the sonotrode, the sonotrode may be any sonotrode known in the art. Yet, in embodiments, the sonotrode may have an elongated shape. Especially, the sonotrode may be elongated along a longitudinal axis ALS, wherein the longitudinal axis ALSmay intersect the welding section. In embodiments, during use of the sonotrode, the longitudinal axis ALSmay be configured (roughly) perpendicular to the weld seam (and / or the material). Further, in embodiments, the welding section may have a width W perpendicular to the longitudinal axis ALS. The width W of the welding section may especially determine a maximum width of the weld seam, wherein the width of the weld seam may be selected from the range of < W. Hence, during use of the sonotrode, the sonotrode may have the width W in a direction perpendicular to the welding direction and / or the weld seam. Further, in embodiments, the welding section of the sonotrode may have a curvature in a plane parallel to the width W and the longitudinal axis ALS. The curvature (of the welding section) may especially have a radius of curvature Rc,s, wherein the radius of curvature Rc,smay be selected from the range of > 30 cm, such as from the range of > 40 cm, especially from the range of > 50 cm, like from the range of > 75 cm, though smaller values are herein not excluded. Further, in embodiments, the radius of curvature Rc,sof the welding section may be selected from the range of > 100 cm, such as from the range of > 150 cm, especially from the range of > 175 cm, like from the range of > 200 cm. Additionally or alternatively, in embodiments, the radius of curvature Rc,sof the welding section may be selected from the range of < 700 cm, such as from the range of < 600 cm, especially from the range of < 500 cm, like from the range of < 350 cm. Hence, in specific embodiments, the sonotrode may have a longitudinal axis ALS, wherein the welding section may have a width W determining a width of the weld seam, wherein the welding section may have a curvature in a plane parallel to the width W and the longitudinal axis ALS, wherein the curvature may have a radius of curvature Rc,sselected from the range of > 100 cm. A sonotrode having a welding section with a curvature in a plane parallel to the width W may facilitate the (continuous) ultrasonic welding of materials having a curvature (in a direction perpendicular to the welding section).

[0063] In embodiments, the sonotrode may further have a curvature in a plane perpendicular to the width W, and parallel to the longitudinal axis ALS. Especially, in embodiments, the welding section (of the sonotrode) may define a rounded shape in a crosssection parallel to a longitudinal axis ALSof the sonotrode (and perpendicular to the width W). The rounded shape may especially approximate a circular sector. The term “cylindrical sector” may herein refer to the result of two straight cuts through the central axis of a cylinder along the height of the cylinder, i.e., the section of a cylinder defined by two planes parallel to the central axis of the cylinder. The cylindrical sector may further be defined by a circular sector, particularly by a central radius rcand central angle of the circular sector (see below). For example, if the two planes parallel to the central axis of the cylinder are parallel, the cylindrical sector is a semi-cylinder, i.e., a cylindrical sector defined by a circular sector having a central angle of 180°. Hence, in specific embodiments, the welding section may have a shape approximating a semi-cylindrical shape.

[0064] The term “approximate” and its conjugations herein, such as in “to approximate a shape”, refers to being nearly identical to, especially identical to, the following term, for example nearly identical to a circular sector or a semi-cylindrical shape. For example, a welding section may define a circular sector but for a defect. Similarly, for example, the rounded shape defined by the welding section may not be perfectly round but slightly ellipsoidal. In particular, an object approximating a first shape may herein refer to: a first shape realization encompassing the object, wherein the first shape realization is defined as the smallest encompassing shape of the (2D or 3D, respectively) object wherein the first shape realization has the shape of the first shape, wherein a ratio of the area (volume) of the first shape realization to the area (volume) of the object is < 1.2, especially < 1.1, such as < 1.05, especially < 1.02. For instance, a welding section may approximate a semi-cylindrical shape, wherein the first shape realization may be defined as the smallest encompassing semi-cylindrical shape of the welding section, wherein a ratio of the volume of the first shape realization to the volume of the welding section is < 1.2, especially, especially < 1.1, such as < 1.05, especially < 1.02, including (essentially) 1. Further, if the dimensions of the first shape are defined, the term approximate may refer to the object and the first shape being superimposable (in 2D or 3D, respectively) such that an intersection between the object and the first shape covers at least n% of the object and at least n% of the shape, wherein n is at least 90%, such as at least 95%, especially at least 98%, such as at least 99%, including 100%.

[0065] In embodiments, the circular sector may (thus) have a central angle acof > 10°, such as > 25°, especially > 45°, such as > 90°, especially > 135°, such as > 150°, especially > 175°. In further embodiments, the circular sector may have a central angle acof > 30°, such as > 35°, especially > 40°, such as > 60°. Additionally or alternatively, in embodiments, the circular sector may have a central angle acof < 330°, such as < 300°, especially < 270°, such as < 235°, especially < 210°, such as < 190°. In further embodiments, the circular sector may have a central angle acof < 160°, such as < 120°, especially < 100°, such as < 90°. Hence, the central angle acmay, for example, be selected from the range of 25°-300°, such as from the range of 100°-300°, especially from the range of 135°-210°, or especially from the range of 25°-100°, such as from the range of 25°-40°, or such as from the range of 40°-100°. Further, in embodiments, the circular sector may have a central radius rcselected from the range of 2.5-50 mm, such as from the range of 5-30 mm, especially from the range of 6-20 mm, like from the range of 7-10 mm.

[0066] Further, as indicated above, the sonotrode may have a width W perpendicular to the longitudinal axis ALS. In embodiments, the width W may be selected from the range of 5- 200 mm, such as from the range of 10-100 mm, especially from the range of 15-80 mm, like from the range of 20-60 mm. Hence, in specific embodiments, the welding section may define a rounded shape in a cross-section parallel to a longitudinal axis ALSof the sonotrode, wherein the rounded shape may approximate a circular sector, wherein the circular sector may have a central angle acselected from the range of 25°-300°, wherein the circular sector may have a central radius rcselected from the range of 5-30 mm, and wherein the sonotrode may have a width W perpendicular to the longitudinal axis ALS, wherein the width W may be selected from the range of 10 - 100 mm. Such a sonotrode may provide a rounded contact surface. Thereby, the sonotrode may provide the benefit that heat generation may be more locally focused to the welding interface (or: “weld interface”), which may result both in lower power requirements, a lower interface temperature, and / or less heating of surrounding areas, especially “through- the-thickness” heating, and may thereby improve welding quality. Further, such a sonotrode may especially facilitate the ultrasonic welding of curved materials.

[0067] In embodiments, as indicated above the consolidator bottom section may have a (planar) bottom section first side for contacting the weld seam. Further, in embodiments, the consolidator system (of the ultrasonic welding apparatus) may comprise a connector. In (such) embodiments, the consolidator unit may especially be configured connected to the (remainder of the) ultrasonic welding apparatus through the connector. In embodiments, the connector of the ultrasonic welding apparatus may be the same as the connector of the consolidator system as defined herein. Hence, embodiments described for the connector of the consolidator system as defined herein may also apply to the connector of the consolidator system of the ultrasonic welding apparatus as defined herein. Hence, in embodiments, the connector may be configured to allow a first rotation of the consolidator unit about a first axis Ai (intersecting the connector and) configured parallel to the bottom section first side (and to a surface of the material). Additionally or alternatively, the connector may be configured to allow a second rotation of the consolidator unit about a second axis A2 configured parallel to the bottom section first side and perpendicular to the first axis AL Hence, in specific embodiments, the consolidator bottom section may have a bottom section first side for contacting the weld seam, and the consolidator system may comprise a connector, wherein the consolidator unit may be configured connected to the ultrasonic welding apparatus through the connector, wherein the connector may be configured to allow one or more of (i) a first rotation of the consolidator unit about a first axis Ai configured parallel to the bottom section first side, and (ii) a second rotation of the consolidator unit about a second axis A2 configured parallel to the bottom section first side and perpendicular to the first axis AL An ultrasonic welding apparatus comprising such a connector may facilitate that, upon minor differences in thickness of the material, the consolidator unit may rotate to maintain an even pressure on the material, thereby providing a weld seam having a consistent quality, and preventing damage to the material.

[0068] In embodiments, the ultrasonic welding apparatus may further comprise a compaction element. The compaction element may be configured to align (and / or smoothen) the parts of the material (i.e., the adherends) prior to ultrasonic welding by the sonotrode. Hence, the compaction element may be configured to be in physical contact with the material. Further, in embodiments, the compaction element may be configured on an opposite side of the sonotrode to the consolidator unit. That is, along a welding direction, the compaction element may be located in front of the sonotrode (and the consolidator unit). The compaction element may be configured to apply a compaction pressure on the material. The compaction pressure may be selected from the range of > 0.1 MPa, such as from the range of > 0.2 MPa, especially from the range of > 0.5 MPa, like from the range of > 0.7 MPa, such as from the range of > 1 MPa. Additionally or alternatively, in embodiments, the compaction pressure may be selected from the range of < 25 MPa, such as from the range of < 20 MPa, especially from the range of < 15 MPa, like from the range of < 10 MPa. In specific embodiments, the compaction pressure may be lower than the consolidation pressure.

[0069] In embodiments, the compaction element may comprise a compaction block, wherein the compaction block may be configured to (physically) contact the material at a planar bottom side of the compaction block. Hence, in embodiments, the compaction block may be configured to slide over the material (while applying the compaction pressure). Alternatively, the compaction element may comprise a compaction wheel, wherein the compaction wheel may be configured to roll over the material (while applying the compaction pressure). Further, in embodiments, the compaction element may comprise a plurality, such as > 2, especially > 3, like > 4, compaction blocks and / or compaction wheels. A plurality of compaction blocks and / or compaction wheels may facilitate applying a more even compaction pressure on materials having a more complex shape (e.g. curved materials).

[0070] The compaction element, especially the compaction block and / or compaction wheel, may comprise a compaction element material. The compaction element material may be selected from the group comprising metals, glass, ceramics, stone, and polymeric materials. In embodiments, the compaction element material may especially have a higher melting point and / or a higher glass transition temperature than the material (to be welded). Such a compaction element material may provide the benefit that the compaction element is stable at the thermal conditions it may be exposed to, i.e., it may (essentially) not melt nor soften due to heat absorbed from the material.

[0071] In embodiments, the ultrasonic welding apparatus may further comprise one or more gas nozzles. Alternatively, the ultrasonic welding apparatus may be functionally coupled with one or more gas nozzles. The one or more gas nozzles may be configured to provide (such as especially emit) a (pressurized) gas. Hence, in embodiments, the one or more gas nozzles may be configured fluidically coupled (e.g. via tubing) with one or more of a gas reservoir and a (gas) pump (such as especially a compressor). In embodiments, the gas (provided by the one or more gas nozzles) may be any gas known in the art. Especially, the gas may comprise, such as be, (ambient) air. Additionally or alternatively, the gas may comprise one or more of carbon dioxide, nitrogen, and argon. The gas may (especially in the case of ambient air) be a dehumidified gas. Especially, the gas may have a relative humidity of < 20%, such as < 15%, especially < 10%, like < 5%, including (essentially) 0%. In embodiments, the gas may be a pressurized gas. That is, the one or more gas nozzles may be configured to provide pressurized gas, wherein the gas may be especially be pressurized upstream of the one or more gas nozzles. Especially, the gas (provided by the one or more gas nozzles) may have a pressure of > 1 bar, such as > 3 bar, especially > 5 bar, like > 7 bar. Additionally or alternatively, the gas (provided by the one or more gas nozzles) may have a pressure of < 30 bar, such as < 20 bar, especially < 15 bar, like < 10 bar. Further, the gas may have a temperature selected from the range of > - 70 °C, such as from the range of > -50 °C, especially from the range of > -20 °C. Further yet, the gas may have a temperature selected from the range of > 0 °C, such as from the range of > 5 °C, especially from the range of > 10 °C. Additionally or alternatively, the gas may have a temperature selected from the range of < 35 °C, such as from the range of < 25 °C, especially from the range of < 20 °C. Further, the gas may have a temperature selected from the range of 10-35 °C, such as from the range of 15-30 °C, especially from the range of 20-25 °C (i.e., the gas may be around room temperature).

[0072] In embodiments, the weld seam may be provided at an interface between two pieces of (the same or different) material(s), see also below. Hence, in embodiments, a first piece of material may be at least partially overlapped with a second piece of material, wherein the weld seam may be provided at the overlap. Especially, a bottom face op the upper piece of material may be ultrasonically welded to a top face of the bottom piece of material. In embodiments, the one or more gas nozzles may be configured to provide the (pressurized) gas to (a top of) the weld seam (i.e., at the region of overlap between the two pieces of material, especially at a top face of the upper piece). Additionally or alternatively, the two pieces of material may each have a side face at the overlap, wherein the one or more gas nozzles may be configured to provide the (pressurized) gas to the side face of one or more of the upper piece of material and the bottom piece of material, such as especially to the side face of the upper piece of material. In embodiments, the one or more gas nozzles may be configured to provide the (pressurized) gas to at least part of the weld seam located (directly) under the sonotrode (i.e., to the part of the weld seam currently being welded). Additionally or alternatively, along the welding direction, the one or more gas nozzles may be configured to provide the (pressurized) gas to at least part of the weld seam located between the sonotrode and the consolidator unit. Additionally or alternatively, along the welding direction, the one or more gas nozzles may be configured to provide the (pressurized) gas to at least part of the weld seam located behind the consolidator unit (i.e., to the welded and consolidated weld seam). Yet, especially, the one or more gas nozzles may be configured to provide the (pressurized) gas to one or more of (i) at least part of the weld seam located (directly) under the sonotrode, and (ii) at least part of the weld seam located between the sonotrode and the consolidator unit. Especially, the one or more gas nozzles may be configured to reduce a temperature of (or in) the weld seam, such as especially a temperature of a side face of the welded material (by flowing the gas along the weld seam).

[0073] In embodiments, the one or more gas nozzles may be configured mounted on the ultrasonic welding apparatus, especially in (close) proximity to the sonotrode, wherein the one or more gas nozzles may move (together) with the sonotrode. Alternatively, the one or more gas nozzles may not be mechanically coupled with (the rest of) the ultrasonic welding apparatus, wherein the ultrasonic welding may be configured to: (i) move the one or more gas nozzles independently from but in synchronization with the sonotrode, or (ii) maintain a position of the sonotrode and the one or more gas nozzles, and move the to-be-welded material along the welding direction. In embodiments, during operation of the one or more gas nozzles, each of the one or more gas nozzles may be configured to provide the (pressurized) gas to (or along a length of) at least 1 cm, such as at least 1.5 cm, especially at least 2 cm, of the weld seam (at any point in time, and along the welding direction). That is, during ultrasonic welding, each of the one or more gas nozzles may flow the gas over a (static) spot on the weld seam having a length of > 1 cm, such as > 1.5 cm, especially > 2 cm, along the welding direction. In embodiments, the gas flow from the one or more gas nozzles may have a maximum flow speed, wherein the length of the (static) spot may be determined by the distance between opposite points along the weld seam at which the gas has a flow speed of half the maximum flow speed. Further, in embodiments, each of the one or more gas nozzles may be configured to flow the gas over a (static) spot on the weld seam having a length of < 10 cm, such as < 7.5 cm, especially < 5 cm, along the welding direction. That is, each of the one or more gas nozzles may be configured to flow the gas over a (static) spot on the weld seam having a length of 1-10 cm, such as 1.5-7.5 cm, especially 2-5 cm, along the welding direction. Hence, in specific embodiments, the ultrasonic welding apparatus may comprise one or more gas nozzles, wherein the one or more gas nozzles may be configured to provide a flow of gas to at least part of the weld seam. Especially, the at least part of the weld seam may(, as seen along the welding direction,) be selected from the group of: (i) at least part of the weld seam located (directly) under the sonotrode, and (ii) at least part of the weld seam located between the sonotrode and the consolidator unit. Such one or more gas nozzles may especially be configured to cool a side face of (at least one of) the pieces of welded material, thereby preventing overheating, degradation, and / or burning of said side face.

[0074] The consolidator system and / or the ultrasonic welding apparatus as defined herein may especially be used for the continuous ultrasonic welding of a material. Hence, in a yet further aspect, the invention provides a method for ultrasonic welding of a material using a consolidator unit. The consolidator unit of the method may especially be the consolidator unit (of the consolidator system) as defined herein. Hence, embodiments relating to the consolidator unit as defined herein may also apply to the consolidator unit of the method as defined herein. Hence, the consolidator unit (of the method) may comprise a consolidator bottom section and a cooling compartment. The consolidator bottom section may especially be configured in thermal contact with the cooling compartment. In (such) embodiments, the method may comprise providing ultrasonic vibrations to the material with a sonotrode to provide a weld seam. Herein, the sonotrode of the method may in principle be any sonotrode known in the art that is suitable for ultrasonic welding, but may especially be the sonotrode as defined herein. Further, the method may comprise bringing the consolidator bottom section in physical and thermal contact with the weld seam. Additionally, the method may comprise flowing a cooling fluid through the cooling compartment to maintain a temperature of the bottom section (especially of the bottom section first side) at below a temperature Ti. In embodiments, Ti may be selected from the range of < 200 °C, such as from the range of < 150 °C, especially from the range of < 125 °C, like from the range of < 100 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of < 85 °C, such as from the range of < 75 °C, especially from the range of < 50 °C, like from the range of < 40 °C. Additionally or alternatively, in embodiments, Ti may be selected from the range of > 0 °C, such as from the range of > 5 °C, especially from the range of > 10 °C, like from the range of > 15 °C. Yet, especially, Ti may be selected from the range of < 100 °C. Hence, in specific embodiments, the invention may provide a method for ultrasonic welding of a material using a consolidator unit, wherein the consolidator unit comprises a consolidator bottom section and a cooling compartment, wherein the consolidator bottom section is configured in thermal contact with the cooling compartment, wherein the method comprises: (A) providing ultrasonic vibrations to the material with a sonotrode to provide a weld seam; (B) bringing the consolidator bottom section in physical and thermal contact with the weld seam; and (C) flowing a cooling fluid through the cooling compartment to maintain a temperature of the bottom section at below a temperature Ti, wherein Ti is selected from the range of < 100 °C. Such a method may facilitate continuous ultrasonic welding of a material, wherein a weld seam having a consistent quality is provided. Especially, such a method may facilitate actively cooling the consolidator unit during ultrasonic welding, providing the benefit that the weld seam may be substantially cooled down upon consolidation with the (passing) consolidator unit, thereby reducing, especially preventing, (i) pore formation in the weld seam, (ii) de-consolidation after passing of the consolidator, and (iii) resin and fiber squeeze out from the adherends.

[0075] In embodiments, the method may especially be suitable for continuous ultrasonic welding of a material. In embodiments, the material (to be welded) may be any to be welded material. In embodiments, the (to-be-welded and / or welded) material may comprise one or more of metals, thermoplastic composites, thermoset composites, and elastomers. Especially, in embodiments, the material may comprise a polymer composite material. In specific embodiments, the material may comprise a thermoplastic, especially a (fiber- reinforced) thermoplastic composite. In further embodiments, the material may comprise a thermoplastic composite, such as a thermoplastic composite laminate. Examples of suitable thermoplastics (for the thermoplastic composites) may e.g. comprise low-melt polyaryletherketone (LMPAEK), polyetheretherketon (PEEK), polyphenylene sulfide (PPS), polyamide (PA) (e.g. polyamide 6 (PA6) and / or polyamide 12 (PA12)), polyetherimide (PEI), polyetherketoneketone (PEKK), and poly(methyl methacrylate) (PMMA). Examples of suitable thermoplastic composites may for instance be F / LMPAEK, F / PEEK, F / PPS, F / PA6, CF / PA12, F / PEI, CF / PEKK, and F / PMMA, wherein F may comprise one or more of carbon fiber (CF) and glass fiber (GF). In particular, the material may comprise a thermoset (composite) with a thermoplastic coupling layer co-cured on the surface adherend, i.e., a thermoset (composite) that may be welded through a thermoplastic coupling layer. Hence, the material may comprise a thermoset composite with a co-cured layer of thermoplastic material on at least one side of the composite. The material may also be referred to herein as an “adherend”. The term “material” may herein also refer to a plurality of (different) materials. In further embodiments, the material may comprise an aerospace material or an automotive material, especially an aerospace material, or especially an automotive material. Hence, in specific embodiments, the material may comprise a thermoplastic composite or a thermoset composite with a co-cured layer of thermoplastic material on at least one side of the composite.

[0076] In embodiments, the weld seam may be provided at an interface between two pieces of (the same or different) material(s). Hence, in embodiments, a first piece of material may be at least partially overlapped with a second piece of material, wherein the weld seam may be provided at the overlap. In embodiments, the method may comprise providing an energy director between (the overlapping section of) the first piece of material and the second piece of material. The energy director may be configured to absorb the ultrasonic vibrations of the sonotrode and concentrate the energy of the ultrasonic vibrations (at the overlap), wherein the energy director (and the first and second pieces of material) may be at least partially melted at the overlap, thereby facilitating a melting together of the first piece and second piece of material to provide the weld seam. Alternatively, the first piece and second piece of material may be welded together without the use of an energy director. In such embodiments, one or both of the first piece and second piece of material may have a roughened surface, wherein the roughened surface may facilitate concentrating the energy from the ultrasonic vibrations to facilitate the welding of the first piece to the second piece. Hence, in embodiments, the method may comprise providing a (piece of) material having a roughened surface.

[0077] In embodiments, the (piece of) material having a roughened surface may be provided by pressing of a material precursor with a (removable) roughness-inducing layer. Especially, in embodiments, the material precursor may be at least partially covered with the roughness-inducing layer, wherein the stack of material precursor and roughness-inducing layer may be pressed together with a pressure of > 5 bar, such as a pressure of > 10 bar, especially a pressure of > 15 bar, at a pressing temperature Tp, and wherein after pressing the roughness-inducing layer may be removed from the material precursor to provide the material having a roughened surface. In embodiments, the pressing temperature Tpmay be selected from the range of > 50 °C, such as from the range of > 100 °C, especially from the range of > 200 °C, like from the range of > 350 °C. Further, in embodiments, the roughness-inducing layer may have a(n average) roughness selected from the range of > 10 pm, such as from the range of > 20 pm, especially from the range of > 30 pm. Additionally or alternatively, in embodiments, the roughness-inducing layer may have a(n average) roughness selected from the range of < 60 pm, such as from the range of < 50 pm, especially from the range of < 40 pm. The (average) surface roughness may e.g. be determined using microscopy imaging (of a cross-section of the roughened material) and / or laser scanning microscopy. In embodiments, one side of the material may comprise the roughened surface. Alternatively, both sides of the material may comprise the roughened surface. Especially, in embodiments, the first piece of material may be at least partially overlapped with the second piece of material for ultrasonic welding, wherein the roughened surface(s) may be configured at the interface between the first piece and second piece of material. As indicated above, one or both of the first piece and second piece of material may comprise the roughened surface.

[0078] In embodiments, the material precursor may comprise a layer of resin, wherein the layer of resin is configured facing the roughness-inducing layer in the stack. The layer of resin may have a thickness selected from the range of 20-400 pm, such as from the range of 35-350 pm, especially from the range of 50-250 pm, like from the range of 50-200 pm. The roughened surface may in embodiments especially be formed in the layer of resin. This may provide the benefit that the (roughened) layer of resin may melt during the ultrasonic welding process, wherein the layer of resin may promote the diffusion of material from the first piece of material to the second piece of material and vice versa, thereby providing a stronger weld seam. Further, the roughened surface may provide the benefit that no energy director is needed to facilitate the welding process, thereby reducing the final thickness of the weld seam and the number of components needed to provide the weld seam, thus providing a simplified welding process. Additionally, with a material comprising a roughened surface, no energy director is needed to facilitate the welding process, thereby reducing the weight of the final welded material. Hence, a material comprising a roughened surface may be especially suitable for applications in e.g. the automotive industry, wherein a lower final weight of the car may reduce fuel consumption and tire degradation.

[0079] In embodiments, the method may comprise providing ultrasonic vibrations to the material, wherein the ultrasonic vibrations may have a welding frequency. In embodiments, the welding frequency may be selected from the range of > 12 kHz, such as from the range of > 13 kHz, especially from the range of > 14 kHz, like from the range of > 15 kHz, such as from the range of > 17 kHz. Additionally or alternatively, in embodiments, the welding frequency may be selected from the range of < 50 kHz, such as from the range of < 45 kHz, especially from the range of < 40 kHz, like from the range of < 35 kHz, such as from the range of < 25 kHz.

[0080] In embodiments, the method may comprise bringing the consolidator bottom section (especially the bottom section first side) in physical and thermal contact with the weld seam. Further, the method may comprise providing a consolidation pressure on the weld seam with the consolidator unit (via the bottom section first side), wherein the consolidation pressure may be selected from the range of > 0.2 MPa, such as from the range of > 0.4 MPa, especially from the range of > 0.7 MPa, like from the range of > 1.0 MPa, such as from the range of > 1.3 MPa. Additionally or alternatively, in embodiments, the consolidation pressure may be selected from the range of < 5.0 MPa, such as from the range of < 4.0 MPa, especially from the range of < 3.0 MPa, like from the range of < 2.0 MPa.

[0081] In embodiments, the method may further comprise functionally coupling the consolidator unit to an ultrasonic welding apparatus with a connector. The connector of the method may especially be the connector as defined herein (for the consolidator system). Hence, in embodiments, the connector (of the method) may be configured to allow a rotation of the consolidator unit about a first axis Ai configured parallel to the bottom section first side. Further, the method may comprise rotating the consolidator unit about a first axis Ai (and optionally about a second axis A2). Hence, in specific embodiments, the bottom section may have a bottom section first side for contacting the weld seam, wherein the method may comprise functionally coupling the consolidator unit to an ultrasonic welding apparatus with a connector, wherein the connector may be configured to allow a rotation of the consolidator unit about a first axis Ai configured parallel to the bottom section first side.

[0082] In embodiments, the method may further comprise flowing a cooling fluid through the cooling compartment to maintain a temperature of the bottom section at below the temperature Ti. In embodiments, the method may further comprise absorbing heat from the bottom section (via the cooling compartment) with the cooling fluid. Hence, in embodiments, the temperature of the cooling fluid may increase while flowing through the cooling compartment. Especially, in embodiments, cooling fluid provided to the fluid inlet may have a first temperature Tin, and cooling fluid received from the fluid outlet may have a second temperature Tout, wherein Tout > Tin. In embodiments, the method may comprise reducing the temperature of the cooling fluid in the fluid cooling unit (of the fluid control system). Especially, the method may comprise reducing the temperature of the cooling fluid by at least 0.1°C, like by at least 0.5 °C, such as by at least 1 °C, especially by at least 2.5 °C, like by at least 5 °C. Further, in embodiments, the method may comprise reducing the temperature of the cooling fluid by at least 10 °C, such as by at least 15 °C, especially by at least 20 °C, like by at least 25 °C. In embodiments, the method may especially comprise controlling the temperature Tin of the cooling fluid provided to the fluid inlet. Especially, in embodiments, the method may comprise maintaining the temperature Tin at a temperature of < 50 °C, such as < 40 °C, especially < 30 °C, like < 25 °C.

[0083] Hence, in specific embodiments, the cooling fluid provided to the fluid inlet may have a first temperature Tin, and cooling fluid received from the fluid outlet may have a second temperature Tout, wherein the method comprises reducing the temperature of the cooling fluid, especially in the fluid cooling unit. Reducing the temperature of the cooling fluid in the cooling unit may increase the heat-absorbing capacity of the cooling fluid, thereby increasing the efficiency with which the consolidator unit may be cooled.

[0084] In embodiments, the difference between Tin and Tout may be related to a flow rate of the cooling fluid through the cooling chamber, wherein a higher flow rate may result in a smaller difference between Tin and Tout Hence, in embodiments, the method may further comprise controlling a flow rate of the cooling fluid through the cooling compartment. In embodiments, the flow rate may be selected from the range of > 2 ml / s, such as from the rate of > 5 ml / s, especially from the range of > 10 ml / s. Additionally or alternatively, the flow rate may be selected from the range of < 400 ml / s, such as from the range of < 200 ml / s, especially from the range of < 150 ml / s, like from the range of < 100 ml / s.

[0085] In embodiments, the method may further comprise reducing a surface temperature of the weld seam, especially by absorbing heat from the (surface of the) weld seam with the consolidator unit. In embodiments, the method may comprise reducing a surface temperature of the weld seam by at least 5 °C, such as by at least 10 °C, especially by at least 15 °C, like by at least 20 °C. Further, in embodiments, the method may comprise reducing a surface temperature of the weld seam by at least 30 °C, such as by at least 40 °C, especially by at least 50 °C, like by at least 75 °C. Additionally or alternatively, in embodiments, the method may comprise reducing a surface temperature of the weld seam by at most 300 °C, such as by at most 200 °C, especially by at most 150 °C, like by at most 100 °C. Hence, in specific embodiments, the method may comprise reducing a surface temperature of the weld seam by at least 20 °C. Such a reduction in surface temperature may facilitate that the welding interface may solidify sufficiently, thereby preventing the formation of pores in the weld seam.

[0086] In embodiments, the method may comprise continuously welding the material along a welding path (to provide the weld seam). In embodiments, along the welding path, the consolidator unit may be configured behind the sonotrode. Especially, along the welding path, the consolidator unit may have a shortest distance di to the sonotrode. In embodiments, the shortest distance di may be selected from the range of < 200 mm, such as from the range of < 175 mm, especially from the range of < 150 mm, like from the range of < 100 mm. Further, in embodiments, di may be selected from the range of < 75 mm, such as from the range of < 50 mm, especially from the range of < 25 mm, like from the range of < 10 mm. Further yet, in embodiments, di may be selected from the range of < 7.5 mm, such as from the range of < 5 mm, especially from the range of < 2.5 mm, like from the range of < 1 mm, including (essentially) 0 mm. Additionally or alternatively, in embodiments, di may be selected from the range of > 0.5 mm, such as from the range of > 1 mm, especially from the range of > 2 mm. Hence, in specific embodiments, the method may comprise continuously welding the material along a welding path, wherein along the welding path the consolidator unit may be configured behind the sonotrode at a shortest distance di selected from the range of < 150 mm. Such a shortest distance di may facilitate that the weld seam may be consolidated by the consolidator unit relatively quickly after welding of the weld seam, thereby preventing the formation of pores in the weld seam.

[0087] In embodiments, the method may comprise bringing the consolidator bottom section in physical and thermal contact with the weld seam, wherein a center of (the width Wc of) the consolidator unit is configured centered on the weld seam. In such embodiments, the consolidator unit may further be aligned (along the weld seam) with a center of the sonotrode. Alternatively, the method may comprise bringing the consolidator bottom section in physical and thermal contact with the weld seam, wherein a center of (the width Wc of) the consolidator unit is configured at a distance d2 from a center axis of the weld seam. That is, in embodiments, the consolidator unit may be configured misaligned (or “staggered”) with respect to the weld seam. Further, in such embodiments, the consolidator unit may be configured misaligned (or “staggered”) with respect to the (center of the) sonotrode, especially by the distance d2. Hence, in embodiments, the method may comprise bringing the consolidator bottom section in physical and thermal contact with the weld seam, wherein the center of the consolidator unit may be offset from (the center of) the sonotrode by a distance d2 (in a direction perpendicular to the welding path). In embodiments, the distance d2 may be selected from the range of < 20 mm, such as from the range of < 15 mm, especially from the range of < 10 mm, like from the range of < 5 mm. Additionally or alternatively, the distance d2 may be selected from the range of > 0.1 mm, such as from the range of > 0.5 mm, especially from the range of > 1 mm, like from the range of > 2 mm. Hence, in embodiments, the method may comprise placing the consolidator unit at an offset with respect to the sonotrode. Further, in embodiments, the method may comprise flowing a gas over at least part of the weld seam (using one or more gas nozzles). Especially, the method may comprise providing a flow of gas to one or more of: (i) at least part of the weld seam located (directly) under the sonotrode, and (ii) at least part of the weld seam located between the sonotrode and the consolidator unit. Additionally or alternatively, the method may comprise providing a flow of (pressurized) gas to at least part of the weld seam located under (and / or behind) the consolidator unit. As indicated above, the gas may comprise, such as be, one or more of (ambient) air, carbon dioxide, nitrogen, and argon, such as especially (ambient) air. The gas may have a relative humidity of < 20%, such as < 15%, especially < 10%, like < 5%, including (essentially) 0%. Further, the gas may be a pressurized gas, such as having a pressure selected from the range of 1-30 bar, like from the range of 3-20 bar, especially from the range of 5-15 bar, like from the range of 5-10 bar. Additionally or alternatively, the gas may have a temperature selected from the range of 10-35 °C, such as from the range of 15-30 °C, especially from the range of 20-25 °C. Hence, in specific embodiments, the method may comprise providing a flow of gas to at least part of the weld seam. Especially, the at least part of the weld seam may(, as seen along the welding direction,) be selected from the group of: (i) at least part of the weld seam located (directly) under the sonotrode, and (ii) at least part of the weld seam located between the sonotrode and the consolidator unit.

[0088] BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: Fig. l depicts an embodiment of the consolidator system; Fig. 2 schematically depicts an embodiment of the consolidator unit; Fig. 3 schematically depicts an embodiment of the ultrasonic welding apparatus; and Fig. 4 schematically depicts an embodiment of an operational mode of the consolidator system. The schematic drawings are not necessarily on scale.

[0090] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0091] Fig. 1 schematically depicts an embodiment of the consolidator system 1000. Especially, Fig. 1 depicts an embodiment of the consolidator system 1000 in the first configuration. The consolidator system 1000 may be used for consolidating a weld seam 1 in a welded material 10. The material 10 may comprise a first adherend 11 (or “top adherend”), a second adherend 12 (or: “bottom adherend”), and an energy director 16. In embodiments, the first adherend 11 may at least partially overlap the second adherend 12, wherein the energy director 16 may be configured between the first adherend 11 and the second adherend 12, and wherein the weld seam 1 may especially be formed at the part of the material 10 where the first adherend 11 and second adherend 12 overlap. Alternatively, the material 10 may not comprise an energy director 16, and one or more of the first adherend 11 and second adherend 12 may comprise a roughened surface, wherein the roughened surface may be configured facing the overlap of the first adherend 11 and second adherend 12, and wherein the weld seam 1 may especially be formed at the part of the material 10 where the first adherend 11 and second adherend 12 overlap (especially at the roughened surface). Hence, in embodiments, during operation, the first adherend 11 and the second adherend 12 may be welded to one another to provide the weld seam 1 in the material 10. The material 10 may in embodiments especially comprise a thermoplastic composite.

[0092] Returning to the consolidator system 1000, the consolidator system 1000 may comprise a consolidator unit 200. Further, the consolidator system 1000 may comprise or be functionally coupled to a fluid control system 400. The consolidator unit 200 may comprise a consolidator bottom section 210 and a cooling compartment 220. The consolidator bottom section 210 may especially be configured for physically contacting the weld seam 1 (at a bottom section first side 211). Further, in embodiments, the consolidator bottom section 210 may comprise a thermally conductive material. Additionally, the cooling compartment 220 may comprise a fluid inlet 221, a cooling chamber 222, and a fluid outlet 223. In embodiments, during operation of the consolidator system 1000, the fluid inlet 221 may be configured facing the consolidated weld seam 1, and the fluid outlet 223 may be configured facing the to-be- consolidated weld seam 1. Hence, during operation of the consolidator system 1000, the fluid outlet 223 may be configured in front of the fluid inlet 221 along the welding path. Yet, in alternative embodiments, during operation of the consolidator system 1000, the fluid inlet 221 may be configured in front of the fluid outlet 223 along the welding path (see Fig. 3A). In (other) embodiments, the fluid inlet 221 and fluid outlet 223 may be configured side-by-side along the welding path. Further, in embodiments, the cooling chamber 222 may comprise a thermally conductive material.

[0093] As indicated, Fig. 1 schematically depicts an embodiment of the consolidator system 1000 in the first configuration. In the first configuration, the consolidator bottom section 210 may especially be configured in thermal contact with the cooling compartment 220. Further, in the first configuration, the fluid inlet 221, the cooling chamber 222, and the fluid outlet 223 may be fluidically coupled. Additionally, in the first configuration, the fluid control system 400 may be fluidically coupled to the cooling compartment 220, and may be configured to flow a cooling fluid 40 through the cooling compartment 220 (especially through the cooling chamber 222 via the fluid inlet 221 and the fluid outlet 223). In embodiments, in the first configuration (and during operation of the consolidator system 1000), the consolidator system 1000 may be configured to maintain a temperature of the consolidator bottom section 210 (especially of the bottom section first side 211) at below a temperature Ti. The temperature Ti may especially be selected from the range of < 100 °C.

[0094] The fluid control system 400 may comprise a fluid cooling unit 410. In the first configuration, the fluid cooling unit 410 may be configured fluidically coupled to the fluid inlet 221 and the fluid outlet 223. Especially, in embodiments, the fluid control system 400, especially the fluid cooling unit 410, may comprise a cooling unit inlet 411 and a cooling unit outlet 412, wherein the cooling unit inlet 411 may be fluidically coupled to the fluid outlet 223 of the consolidator unit 200, and wherein the cooling unit outlet 412 may be fluidically coupled to the fluid inlet 221 of the consolidator unit 200. The fluid cooling unit 410 may especially be fluidically coupled to (the fluid inlet 221 and fluid outlet 223 of) the consolidator unit 200 via a fluid carrier system 420. The fluid carrier system 420 may in embodiments (as depicted in Fig. 1) comprise tubing. Further, the fluid cooling unit 410 may be configured to: (a) receive a heated cooling fluid 40 from the fluid outlet 223, (b) reduce a temperature of the cooling fluid 40 received from the fluid outlet 223 to provide a cooled cooling fluid 40, and (c) provide the cooled cooling fluid 40 to the fluid inlet 221. The heated cooling fluid 40 may be indicated by reference 41, and the cooled cooling fluid may be indicated by reference 42. In embodiments, the cooling fluid 40 provided to the fluid inlet 221 (i.e., the cooled cooling fluid 42) may have a first temperature Tin, and the cooling fluid 40 received from the fluid outlet 223 (i.e., the heated cooling fluid 41) may have a second temperature Tout. In embodiments, during operation of the consolidator system, Tout > Tin.

[0095] In embodiments, at least part of the fluid control system 400, such as at least the fluid cooling unit 410, may be configured remote from the consolidator unit 200. Further, in (such) embodiments, the cooling fluid 40 may comprise (demineralized) water. Additionally or alternatively, in the first configuration the fluid control system 400, the fluid inlet 221, the cooling chamber 222, and the fluid outlet 223 may form a watertight fluidic pathway (especially a closed loop). Further, in the first configuration, the fluid control system 400 may be configured to move the cooling fluid 40 along the fluidic pathway.

[0096] The consolidator bottom section 210 may be configured removably attachable to the cooling compartment 220. That is, the consolidator bottom section 210 may be configured to be removed from the cooling compartment 220, wherein the consolidator bottom section 210 may further be configured to be re-attached to the cooling compartment 220 (e.g. when configuring the consolidator unit 200 in the first configuration). The reversible attachment of the consolidator bottom section 210 to the cooling compartment 220 may be facilitated by one or more fixating elements 250. In the embodiment depicted in Fig. 1 (and Fig. 2A), the one or more fixating elements 250 may especially comprise bolts. Further, the consolidator bottom section 210 and cooling compartment 220 may (each) comprise one or more fixating element receivers, configured to receive the one or more fixating elements 250 to facilitate fixating the consolidator bottom section 210 to the cooling compartment 220. In the embodiment depicted in Fig. 1 (and Fig. 2A), the one or more fixating elements receivers may especially comprise threaded holes. Further, the consolidator unit 200 may comprise a connector 50, configured to facilitate functionally coupling the consolidator unit 200 to an ultrasonic welding apparatus 3000 (see below).

[0097] Fig. 2A schematically depicts an exploded view of an embodiment of the consolidator unit 200. As depicted in Fig. 2A, the consolidator bottom section 210 may have a (planar) bottom section first side 211 for contacting the weld seam 1. Further, Fig. 2A depicts a more detailed view of an embodiment of the connector 50. The connector 50 may in embodiments comprise, such as be, a universal joint. Further (and as such), the connector 50 may be configured to allow a rotation of the consolidator unit 200. Especially, the connector 50 may be configured to allow a first rotation of the consolidator unit 200 about a first axis Ai, wherein the first axis Ai may be configured parallel to the bottom section first side 211 (and the weld seam 1). Additionally (or alternatively), the connector 50 may be configured to allow a second rotation of the consolidator unit 200 about a second axis A2 configured parallel to the bottom section first side 211 and perpendicular to the first axis AL The first axis Ai and the second axis A2 may intersect the connector 50, such that the consolidator unit 200 may be configured to rotate about the connector 50. Further, the first axis Ai and the second axis A2 may be configured parallel to the material 10 (during operation of the consolidator system 1000). Hence, the consolidator unit 200 may be configured to rotate out of a plane configured parallel to the material 10. Further, in embodiments, the consolidator system 1000, especially the connector 50, may be configured to prevent a rotation of the consolidator unit 200 within the plane configured parallel to the material 10. That is, the consolidator system 1000, especially the connector 50, may be configured to prevent a rotation of the consolidator unit 200 about a third axis A3 configured intersecting the connector 50 and the consolidator bottom section 210 (and configured perpendicular to the first axis Ai and the second axis A2). The consolidator unit 200 may have dimensions length Lc, width Wc, and height He (see also Fig. 2B). The length Lc of the consolidator unit 200 may be larger than the width Wc and the height He of the consolidator unit 200, i.e., Lc > Wc and Lc > He. Hence, in embodiments, the consolidator unit 200 may have an axis of elongation AL, wherein the consolidator unit 200 may be elongated along the axis of elongation AL. During operation of the consolidator unit 200, the axis of elongation AL may especially be configured (roughly) parallel to the weld seam 1 and / or (roughly) parallel to a welding direction. In embodiments, the consolidator unit 200 may have a rectangular shape, wherein the length Lc and width Wc of the consolidator unit 200 may be (essentially) constant along the height He of the consolidator unit 200. Yet, alternatively, in embodiments the consolidator bottom section 210 may be beveled and / or comprise a slanted side. In such embodiments, the length Lc and width Wc may vary along the height He of the consolidator unit 200. Further, in such embodiments, the bottom section first side 211 may have a smaller surface area than a bottom section second side 212, wherein the consolidator bottom section 210 may be configured to be in thermal contact with the cooling compartment 220 at the bottom section second side 212. Especially, during operation of the consolidator system 1000, the consolidator bottom section 210 may be configured in physical contact with the weld seam 1 over a first contact area CAi, and the bottom section second side 212 may have a second surface area SA2, wherein CA1 / SA2 < 1.

[0098] Turning to the cooling compartment 220, the cooling compartment 220 may comprise a cooling compartment top part 227 and a cooling compartment bottom part 228. The cooling compartment top part 227 and cooling compartment bottom part 228 may be configured removably attachable (via the one or more fixating elements 250). In the embodiment depicted in Fig. 2A, the consolidator system 1000 may comprise eight fixating elements 250 (of which five are fully visible), wherein the four outer fixating elements 250 (closest to the corners of the consolidator unit 200) may be configured to fixate the consolidator bottom section 210 to the cooling compartment 220 (and the cooling compartment top part 227 to the cooling compartment bottom part 228), and wherein the four inner fixating elements 250 (closest to the center of the consolidator unit 200) may be configured to fixate the cooling compartment top part 227 to the cooling compartment bottom part 228 (and may not be configured to fixate the consolidator bottom section 210 to the cooling compartment 220). In embodiments, the cooling compartment bottom part 228 may comprise the cooling chamber 222. Further, the cooling compartment top part 227 may comprise the fluid inlet 221 and fluid outlet 223. The cooling compartment 220 may further comprise a sealing unit 230. In the first configuration, the sealing unit 230 may especially be configured between the cooling compartment top part 227 and the cooling compartment bottom part 228. The sealing unit 230 may be configured to provide a watertight seal between the cooling compartment top part 227 and cooling compartment bottom part 228 in the first configuration. Hence, the sealing unit 230 may comprise one or more of an O-ring, a gasket, and a waterproof tape. In the embodiment depicted in Fig. 2A, the sealing unit 230 comprises a gasket.

[0099] Zooming in, the cooling chamber 222 may comprise one or more cooling protrusions 225. In the embodiment depicted in Fig. 2A, the one or more cooling protrusions 225 comprise ridges, though this need not be the case (see also above). In embodiments, in the first configuration (especially during operation) of the consolidator system 1000, the one or more cooling protrusions 225 may be configured in thermal contact with the cooling fluid 40. Especially, during operation of the consolidator system 1000, the cooling fluid 40 may flow past the one or more cooling protrusions 225.

[0100] Fig. 2B schematically depicts a front view of the consolidator unit 200. As depicted, the bottom section first side 211 may have a curvature in a plane perpendicular to the axis of elongation AL (and / or first axis Ai) of the consolidator unit 200. The curvature of the bottom section first side 211 may have a radius of curvature Rc. The radius of curvature Rc may especially be the radius of a (virtual) circle having the same (local) curvature as the bottom section first side (211). In Fig. 2B, (a part of) the radius of curvature Rc is schematically represented by the dashed line. In embodiments, the curvature of the bottom section first side 211 may have a radius of curvature Rc selected from the range of > 100 cm. The bottom section first side 211 may further (or alternatively) have a second curvature in a plane parallel to the axis of elongation AL. Such embodiments are not depicted here.

[0101] Fig. 3A schematically depicts an embodiment of the ultrasonic welding apparatus 3000 for welding a material 10. The ultrasonic welding apparatus 3000 may comprise a consolidator system 1000 (especially the consolidator system 1000 as defined herein) and a sonotrode 100. The consolidator system 1000 may comprise a consolidator unit 200 and a fluid control system 400. Further, the consolidator unit 200 may comprise a consolidator bottom section 210 and a cooling compartment 220. The consolidator bottom section 210 may especially be configured for physically contacting a weld seam 1 in the material 10 (at a bottom section first side 211). Further, the consolidator bottom section 210 may comprise a thermally conductive material. Additionally or alternatively, the cooling compartment 220 may comprise a fluid inlet 221, a cooling chamber 222, and a fluid outlet 223. Further, the cooling compartment 220 may comprise a thermally conductive material. The sonotrode 100 may comprise a welding section 110 configured for contacting the material 10. Further, the sonotrode 100 may be configured to (locally) weld the material 10 to provide the weld seam 1.

[0102] Fig. 3A schematically depicts a first configuration of an embodiment of the ultrasonic welding apparatus 3000. In the first configuration, the consolidator unit 200 may especially be configured at a shortest distance di from the sonotrode 100. In embodiments, the shortest distance di may be selected from the range of < 150 mm. Further, in the first configuration, the consolidator bottom section 210 may be configured in thermal contact with the cooling compartment 220. Further yet, in the first configuration, the fluid inlet 221, the cooling chamber 222, and the fluid outlet 223 may be fluidically coupled. Additionally, in the first configuration, the fluid control system 400 may be fluidically coupled to the cooling compartment 220, and may be configured to flow a cooling fluid 40 through the cooling compartment 220 (especially through the cooling chamber 222 via the fluid inlet 221 and the fluid outlet 223). In the first configuration of the ultrasonic welding apparatus 3000, the consolidator system 1000 may be configured to maintain a temperature of the consolidator bottom section 210 (especially of the bottom section first side 211) at below a temperature Ti. In embodiments, the temperature Ti may be selected from the range of < 100 °C. Further yet, in the first configuration and during operation of the ultrasonic welding apparatus 3000, the ultrasonic welding apparatus 3000 may be configured to apply pressure on the weld seam 1 with the consolidator unit 200 (and / or with a support platform configured to support the material 10).

[0103] In particular, in the depicted embodiment, the sonotrode 100 may, during operation, move towards the right, followed by the consolidator unit 200 at the (shortest) distance di. Hence, the part left of the hyphened line has been exposed to the sonotrode 100, whereas the part right of the hyphened line has not yet. Hence, the welding line may have a first thickness ti right of the hyphened line, and a second thickness t2 left of the hyphened line, wherein t2 < ti. For visualization purposes, the welding line left of the hyphened line has been depicted thinner; it will be clear to the person skilled in the art, however, that the thickness of the first adherend 11 and of the second adherend 12 in principle does not change due to the sonotrode 100 (application).

[0104] The consolidator system 1000 may comprise a connector 50, such as especially the connector 50 as defined above. The consolidator unit 200 may be configured connected to the (remainder of the) ultrasonic welding apparatus 3000 through the connector 50. Further, the connector 50 may be configured to allow one or more of (i) a first rotation of the consolidator unit 200 about the first axis Ai (configured intersecting the connector 50 and) configured parallel to the bottom section first side 211 (and to a surface of the material 10), and (ii) a second rotation of the consolidator unit 200 about the second axis A2 (configured intersecting the connector 50 and) configured parallel to the bottom section first side 211 and perpendicular to the first axis AL

[0105] Fig. 3B schematically depicts an embodiment of the sonotrode 100. The sonotrode 100 may have a longitudinal axis ALS. Further, the welding section 110 of the sonotrode 100 may have a width W determining a width of the weld seam 1. Additionally, in embodiments the welding section 110 may have a curvature in a plane parallel to the width W and the longitudinal axis ALS. The curvature of the welding section 110 may especially have a radius of curvature Rc,sselected from the range of > 100 cm.

[0106] The welding section 110 may further (or alternatively) define a rounded shape 111 in a cross-section parallel to the longitudinal axis ALSof the sonotrode 100. The rounded shape 111 may approximate a circular sector 20. In embodiments, the circular sector 20 may have a central angle acselected from the range of 25°-300°. In the depicted embodiment, the central angle acmay be about 180°. In further embodiments, the circular sector 20 may have a central radius rcselected from the range of 5-30 mm, especially from the range of 7-18 mm. In embodiments, The sonotrode 100 may have the width W perpendicular to the longitudinal axis ALS (and to the cross-section), wherein W may especially be selected from the range of 10 - 100 mm, especially from the range of 20 - 60 mm.

[0107] In the depicted embodiment, the welding section 110 (further) has a welding shape approximating a semi-cylindrical shape. In particular, the semi-cylindrical shape may have a cylinder height hcperpendicular to a longitudinal dimension of the sonotrode, especially wherein the cylinder height hcmay be selected from the range of 10 - 100 mm. In particular, the cylinder height hcmay be identical to the width W of the sonotrode. Further, the semi- cylindrical shape may have a cylinder radius selected from the range of 5-30 mm. In particular, the cylinder radius may be identical to the central radius rc.

[0108] Fig. 3B further schematically depicts an embodiment wherein the sonotrode is an unslotted sonotrode 101. In embodiments, the sonotrode 100 may comprise a sonotrode material 105 selected from the group comprising stainless steel, titanium, and aluminum. In particular, in the depicted embodiment, the sonotrode 100, especially the welding section 110, may define the circular sector 20. Further, in the depicted embodiments, the welding section 110 defines an outline, wherein at least part of the outline may have a radius of curvature selected from the range of 5-30 mm. The outline may especially coincide with a circular arc defined by the circular sector 20. In the depicted embodiment, the sonotrode 100 may have a thickness T perpendicular to the longitudinal axis ALSand the width W, wherein the thickness T may vary along the longitudinal axis ALSand / or the width W, especially along the longitudinal axis ALS. In particular, the thickness T may, in the depicted embodiment, have a constant value along approximately 40% of the sonotrode 100 along the longitudinal axis ALS. In embodiments, the constant value for this thickness T may be equal to twice the radius rcof the circular sector 20. In further embodiments, the thickness T may have a constant value along at least 10% of the sonotrode 100 along the longitudinal axis ALS, such as along at least 20%, especially along at least 30%, such as along at least 40%, especially along at least 50%.

[0109] In particular, in embodiments the sonotrode 100 may comprise a first part 121, a second part 122, and the welding section 110. The length L may be defined by the first part 121, the second part 122, and the welding section 110. Yet further, the second part 122 may be configured between the first part 121 and the welding section 110. In embodiments, the first part 121, the second part 122, and the welding section 110 may be a single body, especially of metal or metal alloy. The second part 122 may have a second part thickness T and a second part width Wl. Further, the welding section 110 may taper from the second part 122 to a welding section top 115. Hence, there may be an essentially stepless change from second part 122 to welding section 110 to the welding section top 115. Hence, the largest width of the welding section 110 and the largest thickness of the welding section may in embodiments be identical to the thickness T and the width Wl of the second part 122. Especially, the second part thickness T and the second part width Wl may be constant over at least 40% of the length L of the sonotrode 100, such as over at least 50%. In embodiments, the second part 122 may have the (largest) thickness T and width Wl close to the first part 121. Alternatively, the second part 122 may have the (largest) thickness T and width Wl close to the welding section 110. Further, in specific embodiments W1=W. Further, in embodiments, rc<W<4* rc, such as 1.5*rc<W<4* rc. The first part 121 may have a width larger than the second part width Wl. Further, the first part

[0110] 121 may have a thickness larger than the second part 122. Especially, this width and thickness may be gradually achieved. In other words, the first part 121 may taper to its maximum width and thickness. In this way, there may be an essentially stepless change from the second part

[0111] 122 to the maximum width and thickness parts of the first part 121.

[0112] Fig. 4A schematically depicts experimental data obtained using an embodiment of the consolidator system 1000. Further, Fig. 4A schematically depicts an embodiment of a method for ultrasonic welding of a material 10 using a consolidator unit 200. As indicated, the consolidator unit 200 may comprise a consolidator bottom section 210 and a cooling compartment 220, wherein the consolidator bottom section 210 may be configured in thermal contact with the cooling compartment 220. The method may comprise providing ultrasonic vibrations to the material 10 with a sonotrode 100 to provide a weld seam 1. Further, the method may comprise bringing the consolidator bottom section 210 in physical and thermal contact with the weld seam 1. Additionally, the method may comprise flowing a cooling fluid 40 through the cooling compartment 220 to maintain a temperature of the bottom section 210 (especially of the bottom section first side 211) at below a temperature Ti. In embodiments, Ti may be selected from the range of < 100 °C. In embodiments, the method may especially comprise continuously welding the material 10 along a welding path, wherein along the welding path the consolidator unit 200 may be configured behind the sonotrode 100 at a shortest distance di selected from the range of < 150 mm.

[0113] Fig. 4A especially schematically depicts the temperature of the consolidator bottom section 210 (near the bottom section first side 211) during continuous ultrasonic welding of a material 10. The horizontal axis depicts the welding time t in seconds, and the vertical axis depicts the temperature T in degrees Celsius. The (thicker) vertical line at 80 s indicates the moment when the sonotrode was switched off. A weld seam 1 of 485 mm was produced in a material (10) with a length of 500 mm, with an average welding speed of 485 / 80 = 6.0 mm / s. A (rounded) sonotrode 100 was used to provide the weld seam 1, wherein the sonotrode 100 had a welding section 110 with a width of 16 mm and a radius of curvature Rc,sof 17.5 mm. The sonotrode 100 was configured to apply (ultrasonic) vibrations having a frequency of 20 kHz and a peak-to-peak vibrational amplitude of 80 with a welding force of 1000 N. For comparison, the temperature of the cooling compartment 220 first side is also depicted. Additionally, the temperature of a consolidator bottom section of a (conventional) consolidator system not comprising a cooling compartment and a fluid control system is depicted, here indicated by reference 5000. The consolidator units of the consolidator systems 1000,5000 were placed behind the sonotrode 100 at a shortest (edge-to-edge) distance di of 2 mm, wherein the consolidator units of the consolidator systems 1000,5000 applied a consolidation force of 1024 N to the weld seam 1, and wherein the consolidator units of the consolidator systems 1000,5000 were in contact with the material 10 over a width Wciof 1.6 cm and a length Lciof 4 cm.

[0114] As can be seen from Fig. 4A, the temperature of the consolidator bottom section of the (conventional) consolidator system 5000 increases (rapidly) with longer welding times, and reaches a temperature T of > 180 °C after 80 seconds of welding. Conversely, the temperature of the consolidator bottom section 210 of the consolidator system 1000 of the present invention only increases by about 10-15 °C during the same period of ultrasonic welding, and reaches a temperature T of < 50 °C after 80 seconds of welding. Further, the temperature of the consolidator bottom section 210 of the consolidator system 1000 remained (relatively) constant over the welding time t. A lower temperature of the consolidator bottom section 210 may facilitate absorbing more heat from the weld seam 1, thereby reducing the (surface) temperature of the weld seam 1 and facilitating a phase transfer from liquid(-like) to solid(-like) of the material 10 in the weld seam 1, preventing pore formation and deconsolidation in the weld seam 1.

[0115] Fig. 4B schematically depicts the effect of a cooler consolidator bottom section 210 on the surface temperature T of the weld seam 1 during an ultrasonic welding process using similar parameters to the process described above for Fig. 4A (i.e., same welding speed, distance, etc.). Similar to Fig. 4A, the surface temperature of a weld seam 1 consolidated using the (conventional) consolidator system 5000 increases with increasing welding times, reaching the upper detection limit of the temperature sensor (160 °C) after ~70 s (indicated by the flat plateau). Meanwhile, the surface temperature of a weld seam 1 consolidated using the consolidator system 1000 of the present invention remains relatively stable at a temperature of < 80 °C. The peaks observed at around 5s for both the (conventional) consolidator system 5000 and the consolidator system 1000, and the peak observed at around 77s for the consolidator system 1000 are related to measurement artifacts and edge effects at the beginning and end, and may not accurately reflect the surface temperature of the weld seam 1.

[0116] Hence, as illustrated by Fig. 4B, the consolidator unit (200) is configured to reduce a surface temperature of the weld seam 1 by at least 20 °C during operation of the consolidator system 1000. Further, the method (of the invention) may comprise reducing a surface temperature of the weld seam 1 by at least 20 °C.

[0117] The term “plurality” refers to two or more. Furthermore, the terms “a plurality of’ and “a number of’ may be used interchangeably. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. Moreover, the terms ’’about” and “approximately” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90% - 110%, such as 95%-105%, especially 99%-l 01% of the values(s) it refers to.

[0118] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of' but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

[0119] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0120] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0121] The term “further embodiment” and similar terms may refer to an embodiment comprising the features of the previously discussed embodiment, but may also refer to an alternative embodiment. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0122] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, “include”, “including”, “contain”, “containing” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0123] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0124] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0125] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. Moreover, if a method or an embodiment of the method is described being executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suitable for or configured for (executing) the method or the embodiment of the method, respectively. The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A consolidator system (1000) for consolidating a weld seam (1) in a welded material (10), wherein the consolidator system (1000) comprises a consolidator unit (200) and a fluid control system (400), wherein: the consolidator unit (200) comprises a consolidator bottom section (210) and a cooling compartment (220); the consolidator bottom section (210) is configured for physically contacting the weld seam (1), wherein the consolidator bottom section (210) comprises a thermally conductive material; the cooling compartment (220) comprises a fluid inlet (221), a cooling chamber(222), and a fluid outlet (223), wherein the cooling chamber (222) comprises a thermally conductive material; and in a first configuration of the consolidator system (1000): the consolidator bottom section (210) is configured in thermal contact with the cooling compartment (220); the fluid inlet (221), the cooling chamber (222), and the fluid outlet (223) are fluidically coupled; and the fluid control system (400) is fluidically coupled to the cooling compartment (220) and is configured to flow a cooling fluid (40) through the cooling compartment (220), wherein the consolidator system (1000) is configured to maintain a temperature of the consolidator bottom section (210) at below a temperature Ti, wherein Ti is selected from the range of < 100 °C.

2. The consolidator system (1000) according to claim 1, wherein the fluid control system (400) comprises a fluid cooling unit (410), wherein in the first configuration the fluid cooling unit (410) is configured fluidically coupled to the fluid inlet (221) and the fluid outlet(223), wherein the fluid cooling unit (410) is configured to receive a heated cooling fluid (40) from the fluid outlet (223), wherein the fluid cooling unit (410) is configured to reduce a temperature of the cooling fluid (40) received from the fluid outlet (223) to provide a cooled cooling fluid (40), and wherein the fluid cooling unit (410) is configured to provide the cooled cooling fluid (40) to the fluid inlet (221).

3. The consolidator system (1000) according to any one or the preceding claims, wherein one or more applies of: at least part of the fluid control system (400) is configured remote from the consolidator unit (200), wherein the cooling fluid (40) comprises water; and in the first configuration: (a) the fluid control system (400), the fluid inlet (221), the cooling chamber (222), and the fluid outlet (223) form a watertight fluidic pathway, and (b) the fluid control system (400) is configured to move the cooling fluid (40) along the fluidic pathway.

4. The consolidator system (1000) according to any one of the preceding claims, wherein the consolidator bottom section (210) has a bottom section first side (211) for contacting the weld seam (1), and wherein the consolidator system (1000) comprises a connector (50), wherein the connector (50) is configured to allow (i) a first rotation of the consolidator unit (200) about a first axis (Ai) configured parallel to the bottom section first side (211), and (ii) a second rotation of the consolidator unit (200) about a second axis (A2) configured parallel to the bottom section first side (211) and perpendicular to the first axis (Ai).

5. The consolidator system (1000) according to any one of the preceding claims, wherein during operation the consolidator unit (200) is configured to reduce a surface temperature of the weld seam (1) by at least 20 °C.

6. The consolidator system (1000) according to any one of the preceding claims, wherein the thermally conductive material comprises one or more of gold, silver, copper, aluminum, and alloys thereof, wherein the thermally conductive material has a thermal conductivity selected from the range of > 75 W / (m*K).

7. The consolidator system (1000) according to any one of the preceding claims, wherein the cooling chamber (222) comprises one or more cooling protrusions (225), wherein in the first configuration of the consolidator system (1000) the one or more cooling protrusions (225) are configured in thermal contact with the cooling fluid (40).

8. The consolidator system (1000) according to any one of the preceding claims, wherein the consolidator bottom section (210) is configured removably attachable to the cooling compartment (220).

9. The consolidator system (1000) according to any one of the preceding claims, wherein the consolidator bottom section (210) is configured to be in thermal contact with the cooling compartment (220) at a bottom section second side (212), wherein during operation of the consolidator system (1000) the consolidator bottom section (210) is configured in physical contact with the weld seam (1) over a first contact area CAi, wherein the bottom section second side (212) has a second surface area SA2, and wherein CA1 / SA2 < 1.

10. The consolidator system (1000) according to any one of the preceding claims, wherein the cooling compartment (220) comprises a cooling compartment top part (227) and a cooling compartment bottom part (228), wherein the cooling compartment top part (227) and the cooling compartment bottom part (228) are configured removably attachable, wherein the cooling compartment bottom part (228) comprises the cooling chamber (222), wherein the cooling compartment top part (227) comprises the fluid inlet (221) and fluid outlet (223), and wherein the cooling compartment (220) further comprises a sealing unit (230), wherein in the first configuration the sealing unit (230) is configured between the cooling compartment top part (227) and the cooling compartment bottom part (228).

11. An ultrasonic welding apparatus (3000) for welding a material (10), comprising a consolidator system (1000) and a sonotrode (100), wherein: the consolidator system (1000) comprises a consolidator unit (200) and a fluid control system (400), wherein the consolidator unit (200) comprises a consolidator bottom section (210) and a cooling compartment (220); the consolidator bottom section (210) is configured for physically contacting a weld seam (1) in the material (10), wherein the consolidator bottom section (210) comprises a thermally conductive material; the cooling compartment (220) comprises a fluid inlet (221), a cooling chamber (222), and a fluid outlet (223), wherein the cooling compartment (220) comprises a thermally conductive material; the sonotrode (100) comprises a welding section (110) configured for contacting the material (10), wherein the sonotrode (100) is configured to weld the material (10) to provide the weld seam (1); and in a first configuration of the ultrasonic welding apparatus (3000):the consolidator unit (200) is configured at a shortest distance (di) from the sonotrode (100) selected from the range of < 150 mm; the consolidator bottom section (210) is configured in thermal contact with the cooling compartment (220); the fluid inlet (221), the cooling chamber (222), and the fluid outlet (223) are fluidically coupled; the fluid control system (400) is fluidically coupled to the cooling compartment (220) and is configured to flow a cooling fluid (40) through the cooling compartment (220), wherein the consolidator system (1000) is configured to maintain a temperature of the consolidator bottom section (210) at below a temperature Ti, wherein Ti is selected from the range of < 100 °C; and the ultrasonic welding apparatus (3000) is configured to apply pressure on the weld seam (1) with the consolidator unit (200).

12. The ultrasonic welding apparatus (3000) according to claim 11, wherein the welding section (110) defines a rounded shape (111) in a cross-section parallel to a longitudinal axis (ALS) of the sonotrode (100), wherein the rounded shape (111) approximates a circular sector (20), wherein the circular sector (20) has a central angle (ac) selected from the range of 25°-300°, wherein the circular sector (20) has a central radius (rc) selected from the range of 5- 30 mm, and wherein the sonotrode (100) has a width W perpendicular to the longitudinal axis (ALS), wherein the width W is selected from the range of 10 - 100 mm.

13. The ultrasonic welding apparatus (3000) according to any one of claims 11-12, wherein the consolidator bottom section (210) has a bottom section first side (211) for contacting the weld seam (1), wherein the consolidator system (1000) comprises a connector (50), wherein the consolidator unit (200) is configured connected to the ultrasonic welding apparatus (3000) through the connector (50), wherein the connector (50) is configured to allow one or more of (i) a first rotation of the consolidator unit (200) about a first axis (Ai) configured parallel to the bottom section first side (211), and (ii) a second rotation of the consolidator unit (200) about a second axis (A2) configured parallel to the bottom section first side (211) and perpendicular to the first axis (Ai).

14. A method for ultrasonic welding of a material (10) using a consolidator unit (200), wherein the consolidator unit (200) comprises a consolidator bottom section (210) anda cooling compartment (220), wherein the consolidator bottom section (210) is configured in thermal contact with the cooling compartment (220), wherein the method comprises: providing ultrasonic vibrations to the material (10) with a sonotrode (100) to provide a weld seam (1); bringing the consolidator bottom section (210) in physical and thermal contact with the weld seam (1); and flowing a cooling fluid (40) through the cooling compartment (220) to maintain a temperature of the bottom section (210) at below a temperature Ti, wherein Ti is selected from the range of < 100 °C.

15. The method according to claim 14, wherein the method comprises reducing a surface temperature of the weld seam (1) by at least 20 °C.

16. The method according to any one of claims 14-15, wherein the method comprises continuously welding the material (10) along a welding path, wherein along the welding path the consolidator unit (200) is configured behind the sonotrode (100) at a shortest distance (di) selected from the range of < 150 mm.

17. The method according to any one of claims 14-16, wherein the material (10) comprises a thermoplastic composite or a thermoset composite with a co-cured layer of thermoplastic material on at least one side of the composite.