Heating unit for composite printing of articles

Abstract

The present invention discloses a heating unit (100) for a print head. [Solution] The heating unit includes at least two guide tubes (132, 134), comprising a first guide tube (132) adapted for guiding fiber filaments to an extruder (140) of the heating unit, and a second guide tube (134) adapted for guiding polymer filaments to the extruder. The heating unit also includes a heating element adapted for melting polymer filaments and a horizontal guide channel (125) adapted for guiding the molten polymer from the second guide tube to the extruder. The heating unit further includes a printing nozzle (123) connected to the extruder and adapted for printing composite parts by outputting composite material to the outside of the heating unit.

Description

Technical Field

[0001] The present disclosure relates to the field of additive technologies and can be used in the manufacture of parts and structures made of composite materials reinforced with continuous fibers.

Background Art

[0002] In the relevant art, 3D printing devices that use composite fibers, such as print heads for manufacturing parts or structures made of composite materials, are known.

[0003] For example, there are numerous 3D printer models equipped with specially designed print heads for printing with composite materials. A composite material, or "composite," includes components with different properties and distinct boundaries between the components. The composite material can be strengthened by filling it with particles, short fibers, or long fibers (which can be endless fibers or continuous fibers). Specifically, a composite material containing long fibers or continuous fibers provides a structural material that has the advantage of high rigidity and strength compared to a composite material that does not contain such fibers.

[0004] For the composite printing of articles and the formation of structural polymer composite materials, such fibers are typically introduced into a matrix that is a thermoplastic material in a solid state. The matrix is a material that binds the fibers together or a material filled with short fibers. Typically, the matrix has much lower mechanical properties than the fibers. The composite fibers are supplied to an extruder by a supply device heated to a temperature above the melting temperature of the matrix material of the composite fibers, passed through a printing nozzle, and placed on a printing table, where they are melted, thereby enabling the step-by-step formation of a composite article. Usually, the heating is provided by a heating unit attached to or included in the print head. Here, the extruder is also called an extruder fiber channel.

[0005] For example, international patent application WO2018 / 190750A1 discloses a print head including a printing nozzle that includes, among other things, a mechanism for supplying plastic filaments, more specifically polymer filaments; another mechanism for supplying fibers; a supply tube for polymer filaments; one or more supply tubes for fibers; a heating unit; a plurality of input channels; and an output channel for obtaining a reinforced plastic polymer after the filaments and fibers have passed through the heating unit.

[0006] As is known in the art, Figure 1 shows a hot end unit 1 and a heating block 10. The heating block has input channels, for example, a fiber input section 12 (the supply channel 40 is located inside the heating unit 10) for receiving fiber filaments 13 and guiding the fiber filaments to a corresponding supply channel 40, and a polymer input section 14 for receiving polymer filaments 11 and guiding the polymer filaments to a corresponding fiber supply channel 20. For example, a polymer filament 11, which is a thermoplastic polymer, melts in the high-temperature region of the heating unit 10. The molten thermoplastic polymer is then supplied during the printing process to cover the composite fibers, thereby ensuring connections between different fibers in one layer or different layers of the article or part to be printed. The plastic or polymer is then discharged from the printing nozzle 60 to form the printed article or part. Note that plastic filaments are usually much thicker than composite fibers.

[0007] A known drawback of the device is that the fiber supply channel that guides the fiber to the printing nozzle must adhere to strict dimensional requirements and be long and thin enough to precisely guide the filament, especially the fiber filament, from the input section on the upper side of the print head to the output printing nozzle on the lower side of the heating unit.

[0008] Generally, a print head includes a component called a "hot end." This component is responsible for melting and extruding the filament (e.g., polymer filament in 3D printers). The hot end typically includes a heat block, nozzle, and thermistor, all working together to melt the filament and control the temperature of the molten filament so that it is deposited very precisely at the desired location under the print head, creating a three-dimensional object. A known drawback of known heating units and / or hot ends is that the fiber and polymer filament guided through the heating unit can become viscous and stick and / or adhere to the inner walls of the assembly. This can burn the filament and / or inner walls, building up a further coating layer, such as a residual carbonized coating, which can ultimately seal the supply channel of the heating unit.

[0009] Therefore, despite all the advances made in the field of composite printing, the need for a printhead remains to avoid undesirable clogging caused by the guided fibers.

[0010] Typically, solutions to this problem involve increasing the dimensions of the printhead, or increasing the size of other components attached to the printhead heating unit, or other components that make up part of the printhead heating unit. However, such solutions are not satisfactory for many applications because they make the heating unit too large or bulky. For example, they take up too much space in the printing machine or are incompatible with the latter. Also, the distance between the hot zone in the heating unit and the print nozzle from which the printing material is output may be too large in this case to ensure proper melting of the polymer, thus degrading the quality of the printing process.

[0011] Rather than further reducing the dimensions of the printhead elements, it is more advantageous to provide an alternative solution to prevent fibers and polymer filaments from sticking to or clogging the heating unit by reducing the frictional surface area of ​​the materials within the printhead. Solutions have been sought to prevent plastics, polymers, and other materials from burning and sticking to the walls inside the printhead and heating unit, but these have not been successful in some applications.

[0012] Therefore, in order to manufacture thermoplastic composites while minimizing waste, it is necessary to stabilize the printing process, increase cost efficiency, and keep the printhead compact. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] International Patent Publication WO2018 / 190750A1 [Overview of the Initiative]

[0014] The purpose of this disclosure is to solve these drawbacks, shortcomings, and problems by providing a heating unit for a print head in a first embodiment. The heating unit includes the following components: - at least two guide tubes: each guide tube is fitted to connect to an extruder, with the first of the at least two guide tubes fitted to guide fiber filaments from the first inlet of the first guide tube to the extruder, and the second of the at least two guide tubes fitted to guide polymer filaments from the second inlet of the second guide tube to the extruder; - heating element: the heating element is fitted to melt the polymer filaments guided through the second guide tube to the extruder; - horizontal guide channel connected to the extruder and located below the first and second guide tubes: the horizontal guide channel is fitted to guide the molten polymer from the second guide tube to the extruder; - extruder: the extruder is fitted to form a composite material by covering the fiber filaments guided through the first guide tube to the extruder with the molten polymer filaments; and - printing nozzle: connected to the extruder and fitted to print composite parts by outputting the composite material to the outside of the heating unit.

[0015] In one embodiment, each guide tube is connected to an extruder.

[0016] This significantly reduces the amount of material leakage, clogging, and / or burning used in printheads for printing parts and elements, particularly for composite printing. Specifically, it can prevent leakage, clogging, and / or burning of such materials, especially if the material is a plastic material such as a thermoplastic polymer, which can cause problems when heated in conventionally known printheads. This further aims to completely prevent leakage, clogging, and burning in the printhead heating unit.

[0017] In a preferred embodiment, the fiber filament is selected from carbon fiber filament, glass fiber filament, or Kevlar fiber filament.

[0018] This allows for the manufacture of parts and elements with different properties depending on the type of fiber filament, and enables the creation of reinforced plastics and composite materials during the printing process, resulting in parts with a high strength-to-weight ratio, heat resistance, and chemical resistance.

[0019] Specifically, carbon fiber filaments are strong and rigid filaments that can enhance the structural strength of lightweight yet high-strength printed parts. Glass fiber filaments have properties similar to carbon fiber elements, but the resulting parts tend to be less brittle than those made from carbon fiber filaments. Kevlar fiber filaments offer high strength and heat resistance, and enable the manufacture of parts that can withstand cutting and abrasion. Carbon fiber reinforced plastics can also be used to manufacture lightweight and high-strength parts by combining the strength of carbon fibers with the flexibility of a plastic matrix such as nylon or polyester.

[0020] In a preferred embodiment, the polymer filament is a thermoplastic polymer filament selected from polyether ether ketone, polyether ketone ketone, polyether imide, polysulfone, polyphenyl sulfone, and polyether sulfone.

[0021] This provides a highly efficient and cost-effective heating unit for printheads, enabling the production of materials with far superior advantages than those known. Advantageously, polyether ketone (PEKK) allows for printing of parts at high temperatures and in high-temperature environments without significantly compromising mechanical properties. Furthermore, PEKK has a high strength-to-weight ratio and excellent chemical resistance, making it ideal for harsh environments and applications in the aerospace and automotive industries. Polyetherimide (PEI) offers similar advantages and is particularly suitable for electronic components. Polysulfone (PSU) offers similar advantages to PEKK and PEI, but with even greater clarity and dimensional stability, making it suitable for optical applications. Polyphenylene sulfone (PPSU) is highly reliable for high-performance components in harsh environments due to its excellent dimensional stability, fatigue resistance, and hydrolysis resistance. Polyethersulfone acrylonitrile (PES or PESAN) is ideal for structural and electrical components due to its high rigidity, excellent dimensional stability, and superior flame retardancy.

[0022] In other embodiments, the polymer filament is selected from acrylonitrile butadiene styrene or thermoplastic polyurethane, biodegradable thermoplastic polymers such as polylactic acid, copolyesters such as polyethylene terephthalate glycol, and nylon.

[0023] Acrylonitrile butadiene styrene (ABS) is suitable for a wide range of applications due to its high melting point and excellent strength. Polylactic acid (PLA) is biodegradable and easy to use. Polyethylene terephthalate glycol (PETG) is a versatile plastic that can be used in various applications because it has high strength and durability, and is also resistant to impact, extreme temperatures, and UV rays. Nylon has the advantages of excellent strength, flexibility, and durability, and can also be used in low-temperature printing processes.

[0024] In a preferred embodiment, the heating unit is arranged around a part of the length of a guide tube adapted to guide a polymer filament and further includes a radiator aligned axially with the vertical axis of the guide tube.

[0025] In a preferred embodiment, the heating unit further includes a heat block, each of at least two guide tubes is fixed to the first upper side of the heat block, the heat block further includes an extruder and a printing nozzle, the printing nozzle is arranged on the heat block such that the composite material is output from the heat block outward and from the lower side of the heat block opposite to the upper side of the heat block, and the heat block further includes a heating element.

[0026] In a preferred embodiment, the heating unit further includes a pillar, where the pillar is attached to the heating block and the first guide tube is arranged between the pillar and the second guide tube.

[0027] In one embodiment, the pillar is vertically attached to the heat block.

[0028] In one embodiment, when the pillar is vertically attached to the heat block, the first guide tube, the pillar, and the second guide tube are vertically aligned with each other.

[0029] In another embodiment, the pillar can be positioned along an axis angled with the first guide tube and the second guide tube such that the pillar is horizontally or obliquely attached to the heat block.

[0030] In a preferred embodiment, the heat block includes a first zone called a thermistor zone adapted to house at least one thermal sensor and / or thermistor, where the heat block further includes a second zone called a heater zone adapted to house at least one heating element.

[0031] In a preferred embodiment, the heater zone includes at least one lodge adapted to house heating elements.

[0032] In a preferred embodiment, the horizontal guide channel includes a hollow space formed within the heat block of the heating unit, where the hollow space is located beneath at least two guide tubes and is adapted to accommodate spacers of corresponding size and shape, and the at least two guide tubes are attached to the heat block.

[0033] In a preferred embodiment, the heat block includes an input bushing positioned below a guide tube adapted to guide a fiber filament, the input bushing having an opening of an adjustable diameter to control the flow of the fiber filament.

[0034] In a preferred embodiment, the heating unit further includes a clearance that defines an air gap between the second guide tube and the input bushing.

[0035] In a preferred embodiment, the heating unit further includes a spacer fitted to the inside of a horizontal guide channel, wherein the spacer includes a solid portion and a hollow portion located inside the solid portion, the solid portion being made of a material with high thermal conductivity, and the hollow portion including a tapering notch, the width of which is large enough to guide the molten polymer filament toward the printing nozzle.

[0036] In another embodiment, a print head comprising the following components is proposed: - a main bracket; - two heating units mounted on the main bracket (one of the two heating units being the heating unit described in any one of the claims); - a cutting mechanism mounted on the main support bracket for cutting fiber filaments; - a switching mechanism mounted on the main bracket for controlling the height of one or two of the two heating units.

[0037] In a preferred embodiment, the cutting mechanism includes one or more rotatable cylindrical cutters, each rotatable cylindrical cutter including a radial hole and at least one cylindrical sleeve fixed to the radial hole.

[0038] In a preferred embodiment, the switching mechanism includes a lever configured to control the vertical position of the printing nozzles of one or two heating units. [Brief explanation of the drawing]

[0039] Other features, details, and benefits are shown in the detailed description and drawings below. [Figure 1] This is a cross-sectional view of a heating unit known in the art. [Figure 2] This is a cross-sectional view of the heating unit according to the embodiment. [Figure 3A] This is a schematic diagram of the heating unit according to the embodiment. [Figure 3B] This is a schematic diagram of the heating unit according to the embodiment. [Figure 3C] This is a schematic diagram of the heating unit according to the embodiment. [Figure 4] This is a schematic diagram of a spacer for a heating unit according to an embodiment. [Figure 5] This is a diagram of a print head equipped with one or more heating units according to an embodiment.

[0040] Unless otherwise specified, features common to or similar to multiple figures are given the same reference numeral and refer to the same element or component; therefore, for the sake of brevity, these common features are generally not explained again. [Modes for carrying out the invention]

[0041] The present invention will be further described with reference to the following figures and embodiments. Figure 1 has already been described as an example of a printhead heating unit known in the prior art.

[0042] Referring to Figures 2, 3A, 3B, and 3C, a heating unit for a print head according to this embodiment is shown.

[0043] Specifically, in one embodiment, the heating unit 100 is shown to include a fiber tube input 112 and a polymer tube input 114.

[0044] The heating unit further includes a heat block 150, the elements described above and below being attached to or contained within the heat block 150.

[0045] The fiber tube input section 112 can be connected to a fiber supply mechanism located outside the heat block 150, and the polymer tube input section can also be connected to a polymer supply mechanism located outside the heat block 150. The fiber tube input section 112 functions as an inlet for fiber filaments, i.e., to guide the fiber filaments downward into the fiber guide tube 132, and the polymer tube input section 114 functions as an inlet for polymer filaments, i.e., to guide the polymer filaments into the polymer guide tube 134.

[0046] In one embodiment, a heating element is provided inside the heating unit 100 to heat the inside of the heating unit 100 and some or all of its elements. Examples of heating elements include resistance heating elements, infrared heating elements, cartridge heating elements, positive temperature coefficient elements, mica thermal heating elements, and ceramic heating elements.

[0047] In one embodiment, the bottom of the heating unit 100, or the bottom of the heat block 150 of the heating unit 100, includes a first zone 170 called a thermistor zone, which is adapted to accommodate at least one thermal sensor and / or thermistor.

[0048] In one embodiment, the bottom of the heating unit 100, or the bottom of the heat block 150, includes a second zone 172 called a heater zone, which forms a lodge adapted to house the heating elements. Advantageously, elements 121, 122, and 123, described below, are arranged to reach the same temperature when heated by the heating elements.

[0049] In one embodiment, at least one thermal sensor and / or thermistor is provided inside the heating unit 100 to measure the temperature of the internal components of the heating unit 100.

[0050] Advantageously, the thermistor can be configured to measure the temperature of the polymer guide tube and the temperature at different points in the polymer guide tube.

[0051] In one embodiment, the radiator 116 is provided around the polymer guide tube 134, aligned with the vertical and axial axes of the polymer guide tube along a portion of its length. The radiator 116 may include one or more additional elements selected from heaters, heat dissipation blocks, thermistors, and thermocouples. The radiator may further be mounted on the heat block 150.

[0052] Advantageously, the radiator 116 allows excess heat to dissipate from the heating unit 100, thereby minimizing the temperature of the cold zone located above the heating unit.

[0053] In one embodiment, the radiator 116 may include various dissipation elements, such as heat sinks or any type of passive components that can dissipate heat by conduction. Advantageously, the dissipation elements may also be configured to minimize the temperature of any cold zones located above the heating unit.

[0054] Advantageously, such dissipation elements or passive components are made of a metal such as aluminum and have a large surface area that helps to dissipate heat rapidly. Dissipation elements may include thermoelectric coolers for actively cooling elements within a heating unit or heat block. Dissipation elements may also be thermal paste or thermal grease, which provides material for filling gaps or spaces within the print head, heating unit, or heat block. This further improves the thermal conductivity between the print head and the cooling element, helping to dissipate heat more efficiently.

[0055] Advantageously, polymer and fiber filaments are pushed into the hot end by utilizing their own rigidity. After these filaments are heated within the heating unit 100, they become flexible and loosely rigid, thereby avoiding the need to push the filament over long distances during melting. In other words, the print head with the heating unit described herein includes an effective heat breaker capable of a maximum temperature gradient.

[0056] This allows for a uniform temperature rise along the radiator.

[0057] In one embodiment, the print head includes a single heating unit 100.

[0058] For example, the heating unit 100 may be a cylindrical heater adapted to be inserted into the corresponding hole between the pillar 110 and the fiber guide tube 132.

[0059] In other embodiments, the heating unit 100, or the print head including the heating unit, includes at least another heater element configured to be heated to a temperature exceeding the melting temperature of the fiber filament or polymer filament supplied to the fiber tube input section 112 or the polymer tube input section 114.

[0060] Specifically, the heater element can be heated to a temperature exceeding the melting point of the polymer or thermoplastic filament.

[0061] By using reinforced fibers impregnated with a thermosetting binder and hardened as polymer filaments, the heater element can be heated to a temperature exceeding the glass transition temperature.

[0062] As an option, a feedback control system using a temperature sensor can be used to maintain a constant temperature.

[0063] In one embodiment, the radiator 116, heating element, at least one thermal sensor, and / or thermistor are made of aluminum, copper, aluminum alloy, copper alloy, or any other material having high thermal conductivity (preferably a thermal conductivity of more than 100 W / m·K, more preferably more than 200 W / m·K).

[0064] In one embodiment, a heater element is adapted to melt a polymer filament molten material within a corresponding hot zone of a heating unit 100, and the molten polymer is then mechanically pushed onto or into the fiber filaments coming through the fiber guide tube 132 via a guide channel 125. The molten polymer is preferably in the form of a fluid plastic.

[0065] In a preferred embodiment, the guide channel 125 is horizontal. Preferably, the guide channel 125 extends below the two guide tubes 132, 134 so that the outlet of each guide tube outputs the filament into the guide channel 125 (preferably the guide channel is horizontal and located below the fiber guide tube 132 and the polymer guide tube 134).

[0066] In one embodiment, the guide channel 125 is a notch in the heat block 150. The notch in the guide channel 125 may also be filled with a spacer or any element that partially fills the guide channel 125.

[0067] In one embodiment, fibers covered with molten polymer or plastic are then extracted from the printing nozzle 123 of the heating unit 100 so that the nozzle can construct the printed portion of the composite material.

[0068] In one embodiment, the heating unit 100 includes two input channels, which allow printing using fibers that are not fused to each other and can be combined, for example, by covering one with the other. By covering the fibers with a thermoplastic resin inside the hot end, a solid structure and adhesion between the fibers can be ensured. Examples of fibers include, for example, composite fibers impregnated with a thermosetting binder. Preferred types of fibers used have low porosity and therefore high physical and mechanical properties. Such fibers have the advantage of lower cost because the manufacturing process is much simpler compared to fibers impregnated with thermoplastic polymers.

[0069] Advantageously, this enables the production of fibers that are far simpler and cheaper than those made from thermoplastics, namely, a pre-impregnation process for thermosetting polymers. While the printing processes for thermosetting impregnated fibers and thermoplastic impregnated fibers are roughly equivalent in terms of simplicity, they are more expensive.

[0070] The diameters of the fiber tube input section 112 and the polymer tube input section 114 are adapted to match the dimensions of the corresponding fiber and polymer filaments. In one embodiment, the diameter of the fiber tube 112 is 3 to 10 millimeters, for example, 5 millimeters. In one embodiment, the diameter of the polymer tube input section 114 is 1.5 to 3 millimeters, for example, 1.75 millimeters, corresponding to the diameter of the polymer filament. The diameter of the composite filament usable in this embodiment can be in the range of 0.25 millimeters to 0.8 millimeters.

[0071] Advantageously, the diameters of the through-holes in each tube input section 112 and 114 can be individually adjusted to optimize the printing process.

[0072] In one embodiment, the heating element has a cylindrical shape with a diameter of 5 to 10 millimeters, preferably 6 millimeters, and a length of 20 to 25 millimeters.

[0073] In one embodiment, the guide tube 132 for the fiber filament includes an assembly of a main tube and an end element. Both the tube and the end element are aligned along a common axial channel having a diameter close to the diameter of the fiber filament.

[0074] Here, a channel having a diameter "close" to the diameter of a filament or fiber is defined as a channel having a diameter no more than three times the diameter of the filament or fiber. For example, if the thickness of the fiber is about 0.35 millimeters, the diameter of the channel is about 0.9 millimeters.

[0075] In one embodiment, the mounting of the fiber filament into the guide tube is ensured by the conical shape of the tip element and / or any input portion of the guide tube. This helps maintain straightness and further prevents buckling. It also prevents the fiber filament from coming out of the corresponding inlet of the heating unit each time it is fed or reloaded after any cutting of the fiber filament.

[0076] In one embodiment, below the guide tubes 132 and 134, the bottom of the heating unit 100 includes a heat block 150 that supports multiple elements.

[0077] In one embodiment, the heat block 150 is positioned below the guide tube 132 and includes an input bushing 121 aligned with the guide tube 132. The input bushing 121 is included in the inlet of the extruder 140 and / or can function as the inlet of the extruder 140.

[0078] In one embodiment, the extruder 140 includes at least one of elements 121, 122, and 123. Preferably, the extruder 140 includes an input bushing 121, a washer 122, and a printing nozzle 123.

[0079] In one embodiment, the heat block includes capping elements, such as separate capping components, which are adapted to secure elements 121, 122, and / or 123 together within the heat block 150. This allows for the inclusion of an extruder assembly 140 to which the elements are integrally connected.

[0080] In one embodiment, the input bushing 121 has an adjustable opening. The adjustable opening has the possibility of adjusting its diameter so that the size of its inlet is selected and / or optimized for various parameters of the fiber filament and / or print profile.

[0081] In one embodiment, the heating unit includes an air gap 130, i.e., empty space, between the guide tube 132 and the input bushing 121, which defines the air gap or "cold zone" of the heating unit 100.

[0082] Advantageously, the size of the opening, or the diameter of this opening, can be adjusted to form a small hole, thereby ensuring that, for example, the fibrous filaments inside, such as plastic, do not leak out or flow back up or down.

[0083] In one embodiment, the dimensions of the input bushing are defined based on the fiber diameter. In this embodiment, the diameter of the small hole in the input bushing is greater than the fiber diameter and less than three times the fiber diameter.

[0084] For example, the fiber diameter is 0.35 millimeters, and the hole diameter of the input bushing 121 is 0.6 to 0.8 millimeters.

[0085] In one embodiment, the dimensions of the input bushing are typically 0.6 to 1.2 millimeters, preferably 0.8 to 1.0 millimeters.

[0086] Considering the printing of the part, the fiber filament passing through the guide tube 132 reaches the extruder 140 (also called the extruder fiber channel) through this cold zone. The input bushing 121 is positioned at the level of the inlet of the extruder 140. The input bushing 121 may include or be fitted with a washer 122 (e.g., a copper washer). The fiber filament, covered with molten polymer, is guided to a printing nozzle 123 that outputs the material to be printed, and the printing nozzle 123 is positioned at the bottom of the heat block 150, so that the extruder 140 defines the “hot zone” of the heating unit 100. In one embodiment, the extruder includes a cap, which is configured to surround the extruder. The printing nozzle may also be housed within this cap, and it is preferable that the cap is bolted to the main body structure of the extruder.

[0087] In one embodiment, the printing nozzle has a smooth surface so that the fibers are not damaged when exiting the printing nozzle, regardless of whether the nozzle is inside the cap or not.

[0088] In one embodiment, the height of the hot zone, i.e., the zone between the air gap and the nozzle output, is greater than 20 millimeters. In another preferred embodiment, the height of the hot zone, i.e., the zone between the air gap and the nozzle output, is less than 100 millimeters.

[0089] The diameter of the input channel of the fiber tube input section 112 of the heating unit 100 is smaller than the diameter of the output channel, minimizing the amount of melted filament that passes through the channel that supplies the fiber filament during printing.

[0090] The presence of a 130-degree gap allows for the definition of the air gap that achieves the maximum temperature difference between the cold and hot zones, i.e., the optimal temperature gradient. When heated above the corresponding temperature, the fiber filaments lose their rigidity and become less prone to displacement within the heating unit without bonding, considering the fusion of the fibers with the polymer of the polymer filaments.

[0091] Furthermore, once heated through the hot zone, the fiber filament cannot be pushed beyond a few millimeters, potentially hindering the extrusion and printing process. Therefore, the defined air gap ensures the fiber filament remains cold and rigid when guided until it reaches the hot zone of the heating unit.

[0092] In one embodiment, upon reaching the extruder 140, the extruder functions as a printing nozzle for outputting the material to be printed to the outside of the heating unit 100.

[0093] This is another advantage of the present disclosure, because if the polymer filament is accidentally or excessively extruded within the heating unit, molten plastic may leak out from the sides of the heating unit. Worse still, if the molten plastic reaches the cold zone, it may solidify and block the channels through which the fibers are guided. Advantageously, the present configuration, in combination with the air gap defined by the distance 130 between the cold and hot zones of the heating unit, ensures that the molten plastic cannot reach the cold zone, thus preventing disruption of the printing process or causing printing defects.

[0094] In one embodiment, in addition to the fiber guide tube 132 and the polymer guide tube 134, a pillar 110 is attached to the heat block 150 of the heating unit 100, thus forming three separate components assembled. In this assembly, the fiber guide tube 132 is configured to be positioned between the pillar 110 and the polymer guide tube 134.

[0095] In one embodiment, the heating unit 100 has two inputs 112 and 114 via fiber guide tubes 132 and polymer guide tubes 134, one of which is not connected to, or not adapted to be connected to, a superstructure such as another part of a print head that is adapted to be assembled with (or connected to) the heating unit 100.

[0096] In other words, at least one of these two inputs is isolated from the superstructure by another air gap, or is adapted to be isolated. When the heating unit 100 is assembled or connected with the rest of the print head, these inputs are adapted to be precisely oriented with the filament supply channels of the superstructure.

[0097] Advantageously, the pillar 110 allows for the optimization of the alignment of the heating unit 100 with at least one other part of the print head, particularly the alignment of the fiber guide tube and polymer guide tube when assembling the print head. Furthermore, positioning and assembling the other parts of the print head with the heating unit 110 so that two of their spindles are aligned is simple, fast, and efficient. These spindles are preferably perpendicular.

[0098] In certain embodiments, aligning the pillar and polymer supply tube with the vertical axis of the rest of the printhead is sufficient to ensure optimal positioning, and thus dimensionality, of the air gap located between them.

[0099] In one embodiment, the pillar is made of a material consisting of a titanium alloy or stainless steel.

[0100] Advantageously, pillars containing titanium have low thermal conductivity and high mechanical properties.

[0101] Referring now to Figure 4, a spacer for a heating unit according to the embodiment is shown.

[0102] In one embodiment, the horizontal guide channel 125 defines a hollow or empty space provided within the heat block 150 of the heating unit 100, and as shown in the figure, the hollow or empty space is adapted to accommodate a spacer 122. The thickness of the spacer 122 is preferably slightly greater than the depth of the empty slot to ensure that the spacer 122 is firmly pressed against the top of the bottom of the heat block 150 when assembling the heating unit.

[0103] In one embodiment, specifically, the spacer 122 is positioned at the bottom of the heating unit 100, below the fiber guide tube 132 and the polymer guide tube 134.

[0104] In one embodiment, the spacer 122 includes a solid portion 1222 and a hollow portion 1224. The solid portion 1222 of the spacer 122 is made of a material with high thermal conductivity, such as metal, preferably copper. Advantageously, the use of copper ensures that the supplied polymer or plastic has a uniformly distributed temperature, thus avoiding defects in the resulting composite.

[0105] In one embodiment, the hollow section 1224 includes a slit having a width greater than at least the minimum diameter of the fiber guide tube 132 and the polymer guide tube 134. In a specific embodiment, the hollow section 1224 includes a narrowing notch, which is large enough to guide the material extruded by the extruder 140 to the printing nozzle 123 of the heating unit 100.

[0106] This allows most, if not all, of the material extruded from the extruder 140 to be guided to the printing nozzle 123, and then from the polymer guide tube 134, which is approximately 2 mm in diameter, to the fiber supply zone, which is approximately 1 mm in diameter. The materials used for each of the aforementioned elements are adapted to maintain a uniform temperature not only for themselves but also for all surrounding plastic parts. Furthermore, since all connections between these elements and parts are sealed, the flowing plastic is guided only through the holes in the spacer 122 and / or guide tube, extruder, and printing nozzle.

[0107] In one embodiment, the spacer includes a sheath made of a metal such as copper. This sheath is slightly thicker than the nominal space available for housing the spacer within the heating unit 100.

[0108] In one embodiment, the size of the sheath is approximately 1 millimeter, and the notch is slightly smaller, for example, 0.9 millimeters. When the spacer 122 is placed inside the heating unit, for example, bolted inside the heating unit, the metal part is pressed against the inner wall of the heating unit, providing an optimal seal.

[0109] By further narrowing the guide channels, the plastic can move at high speeds without creating gaps or dead zones in the material flow. This improves the quality of the printing process by preventing the buildup of burnt coatings, thus avoiding clogging of the print head and heating unit. This also prevents plastic and polymer from accumulating on the sides, which would otherwise necessitate print head maintenance after several days of heavy use.

[0110] Referring to Figure 5, a print head according to this embodiment is shown.

[0111] In this embodiment, the print head includes a number of separate heating units, also known as "hot ends."

[0112] Specifically, the print head 200 includes two separate heating units 210 and 220, the first heating unit 210 being a heating unit for heating, guiding and / or supplying a plastic hot end, i.e., a plastic filament, and the second heating unit 220 being a heating unit for heating, guiding and / or supplying a composite hot end, i.e., a composite filament.

[0113] In one embodiment, the print head includes, but is not limited to, a mechanism for supplying plastic filament, a mechanism for supplying reinforcing fibers, another mechanism for cutting reinforcing fibers, one or more supply tubes for any type of filament, and one or more supply tubes for any type of reinforcing fibers.

[0114] In one embodiment, the print head 200 further includes a main bracket 250 that holds all the components and parts.

[0115] In one embodiment, the plastic hot end 210 is retractably fitted by, for example, a switching mechanism 240.

[0116] Advantageously, the switching mechanism 240 includes a horizontal lever adapted to rotate with the nozzle. This horizontal lever is further adapted to move along a diagonal axis located on the main bracket 250. The rotational motion of this lever allows the nozzle to be moved vertically.

[0117] Furthermore, the switching mechanism 240 allows the plastic hot end 210 to be positioned at different heights, including positions higher or lower than the printing nozzles of the composite hot end 220.

[0118] In one embodiment, the plastic hot end 210 is fixed to the main bracket 250 and fitted so as not to move relative to the print head or the main bracket.

[0119] The printhead electrical board is mounted beneath the servo and connects all electrical components to control wires that are connected to the printer's main board.

[0120] In one embodiment, the composite hot end 220 includes a cutting mechanism 230, which is located on the main bracket of the print head 200.

[0121] In one embodiment, the cutting mechanism 230 includes one or more rotatable cylindrical cutters. Preferably, the one or more rotatable cylindrical cutters include a radial hole and at least one cylindrical sleeve fixed to the radial hole.

[0122] These more rotatable cylindrical cutters allow for a high-precision fit due to the cylindrical surface. Advantageously, these rotatable cylindrical cutters can be positioned so that the filament guide through the print head is not obstructed by any elements.

[0123] In one embodiment, the composite hot end 220 further includes a servo motor or machine configured to control and rotate a rotatable cylindrical cutter adapted to cut or break fibers passing through a radial hole.

[0124] The above describes embodiments of the present invention and does not limit the scope of this disclosure. Equivalent structural or process modifications made using the contents of this disclosure and drawings, or applied directly or indirectly to other related technical fields, are also included within the scope of this disclosure and the present invention.

Claims

1. The heating unit is - Each guide tube is fitted to connect to an extruder (140), and of at least two guide tubes, the first guide tube (132) is fitted to guide fiber filaments from the first inlet (112) of the first guide tube to the extruder, and the second guide tube (134) is fitted to guide polymer filaments from the second inlet (114) of the second guide tube to the extruder, at least two guide tubes (132, 134), -A heating element, adapted to melt the polymer filament that is guided to the extruder through a second guide tube (134), - A horizontal guide channel (125) connected to an extruder (140) and located below a first guide tube (132) and a second guide tube (134), which is adapted to guide the molten polymer from the second guide tube to the extruder. - An extruder (140) is adapted to form a composite material by covering fiber filaments guided into the extruder by a first guide tube (132) with molten polymer filaments, and - Includes a printing nozzle (123) connected to an extruder and adapted for printing composite parts by outputting composite material to the outside of a heating unit, Heating units (100; 220) for the print head (200).

2. The heating unit according to claim 1, characterized in that the fiber filament is selected from carbon fiber filament, glass fiber filament, composite fiber filament, optical fiber filament, or Kevlar fiber filament.

3. The heating unit according to claim 1 or 2, characterized in that the polymer filament is selected from thermoplastic polymer filaments such as polyether ether ketone, polyether ketone ketone, polyether imide, polysulfone, polyphenyl sulfone, and polyether sulfone.

4. The heating unit according to any one of the claims, further comprising a radiator (116) positioned around a portion of the length of a guide tube adapted to guide a polymer filament, and aligned axially with the vertical axis of the guide tube.

5. The heating unit according to any one of the claims, further comprising a heat block (150), each of which at least two guide tubes (132, 134) are fixed to the first upper side of the heat block, the heat block further comprising an extruder (140) and a printing nozzle (123), the printing nozzle being positioned in the heat block such that the composite material is output out of the heat block and out from the lower side of the heat block, opposite to the upper side of the heat block, and the heat block further comprising a heating element.

6. Furthermore, including the pillar (110), The pillar is attached to the heating block, The heating unit according to claim 5, wherein the first guide tube (132) is positioned between the pillar (110) and the second guide tube (132).

7. The heating block (150) includes a first zone (170) called a thermistor zone, which is adapted to house at least one thermal sensor and / or thermistor. The heating unit according to claim 5 or 6, wherein the heating block further comprises a second zone (172) called a heater zone, which is adapted to accommodate at least one heating element.

8. The heating unit according to any one of claims 5 to 7, characterized in that the hot zone (172) includes at least one lodge adapted to house a heating element.

9. The horizontal guide channel (125) includes a hollow space formed in the heating block (150) of the heating unit (100). The hollow space is located below at least two guide tubes (132, 134) and is adapted to accommodate spacers (122) of the corresponding size and shape. The heating unit according to any one of claims 5 to 8, characterized in that the at least two guide tubes are attached to the heating block (150).

10. The heating block (150) includes an input bushing (121) positioned below a guide tube (132) which is adapted to guide fiber filaments. The heating unit according to any one of claims 5 to 9, characterized in that the input bushing (121) has an opening having an adjustable diameter for controlling the flow of fiber filaments.

11. The heating unit according to claim 10, further comprising a space (130) that defines an air gap between the second guide tube (132) and the input bushing (121).

12. The system further includes a spacer (122) that is fitted to fit inside the horizontal guide channel (125), The spacer includes a solid portion (1222) and a hollow portion (1224) located inside the solid portion. The solid portion is made of a material having high thermal conductivity. The aforementioned hollow portion is provided with a narrowing notch, The heating unit according to any one of the claims, characterized in that the width of the notch is large enough to guide the molten polymer filament toward the printing nozzle (123).

13. - Main bracket (250), - Two heating units (210, 220) mounted on the main bracket, one of the two heating units being the heating unit described in any one of the claims above. - A cutting mechanism (230) attached to the main bracket for cutting fiber filaments, and A print head (200) including a switching mechanism (240) mounted on the main bracket for controlling the height of one or two heating units.

14. The cutting mechanism (230) comprises one or more rotatable cylindrical cutters, The print head according to claim 13, characterized in that each rotatable cylindrical cutter includes a radial hole and at least one cylindrical sleeve fixed to the radial hole.

15. The print head according to claim 13 or 14, characterized in that the switching mechanism (240) includes a lever configured to control the vertical position of the printing nozzles of one or two heating units.

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