Mold for molding particle foam

Abstract

A mold (10) for particle foam molding, such as dry molding, comprises: a first mold section (1); a second mould section (2) movable relative to the first mould section between a closed position, in which the first mould section (1) and the second mould section (2) define a cavity (3), a semi-closed position, in which the first mould section (1) and the second mould section (2) define a cavity (3), and an open position, in which the first mould section (1) and the second mould section (2) define a cavity (3); the first mold section (1) and the second mold section (2) are spaced further from each other than in the closed position for filling the cavity (3), and an open position in which the first mold section (1) and the second mold section (2) are spaced from each other by a distance (d) to allow removal of the fused particulate foam product (98) from the cavity; a filling device (4) for feeding foamable particles (99) into the cavity (3) in a semi-closed position; a temperature control system (5) to heat the chamber, where the temperature control system comprises at least one injector (51) configured to inject a controlled amount of a heating fluid, such as steam, into the chamber (3) for fusing the foamable particles; and a cavity seal (6) between the first mold section (1) and the second mold section (2), the cavity seal (6) comprising an inner seal (61) and an outer seal (62) wherein in a closed position, the inner seal (61) and the outer seal (62) cooperate to block the passage of foamable particles and fluid from the cavity (3), and in a semi-closed position, the inner seal (61) and the outer seal (62) cooperate to block the passage of foamable particles and fluid from the cavity (3). The inner seal (61) allows the passage of fluid and blocks the passage of foamable particles from the cavity (3).

Description

Technical Field

[0001] The invention relates to a mould for particle foam moulding, a particle foam machine comprising the mould for particle foam moulding and a method for particle foam moulding. Background Art

[0002] Foam molded articles are usually produced by filling a mold with expandable beads of thermoplastics, such as polymers. After the mold is closed, a relatively large amount of steam is injected, which diffuses between the beads to uniformly heat the outside of the beads, so that the beads are thermoplastically fused to each other.

[0003] DE102019005112A discloses a method for producing a particle foam part from particle foam beads, wherein a mold part defining a cavity can be arranged in a filling position in which the cavity is filled with beads and in a molding position in which the beads are molded. The mold part is pressure-tight and the size of the cavity in the molding position is smaller than in the filling position, so that the beads are compressed in the molding position.

[0004] JPH02245318A discloses a foam molding method and an apparatus including a steam chamber having two halves, in which a mold cavity is formed by a porous wall. The porous wall is provided with steam holes or nozzles, through which steam from the steam chamber can flow into the mold cavity and pass through the beads to heat the beads.

[0005] In an embodiment, the apparatus includes a backing that hermetically joins the two halves of the steam chamber. In this way, the mold cavity can be filled at a pressure equal to or above atmospheric pressure or filled under a vacuum pressure where the mold cavity is at or below atmospheric pressure to improve filling of the mold cavity.

[0006] However, it has been found that filling the mold cavity with expandable beads remains a challenging task, especially when complex and / or thin-walled mold cavities are required. The beads may not spread satisfactorily with the applied pressure, and the filling degree of the mold cavity may not be sufficiently uniform, especially in border areas, thin-walled sections or corners. When an insufficiently uniform filling degree is obtained, the material quality of the final product formed from the fused beads may not be sufficient for practical applications.

[0007] Furthermore, the mold cavity is preheated with steam before filling it, and additional steam is introduced upon closing for the fusion of the beads. Due to the relatively large amount of steam required to heat the beads and the mold cavity, the beads may be relatively wet before, during and during fusion. This can affect the fusion of the beads and may reduce the surface quality of the final product. Furthermore, the product may need to be actively dried in an oven before possible further processing.

[0008] After the mold is opened, the steam from the mold cavity and the steam chamber evaporates and is lost.

[0009] Due to these factors, the environmental impact of the known methods is relatively high. Relatively large amounts of water and energy are required to generate steam and to heat the mould cavity. Drying and further processing of the product further increases the energy consumption.

[0010] Furthermore, heating the steam chamber and the mold cavity may require a relatively long time, resulting in relatively long cycle times for manufacturing the final product and reduced production capacity.

[0011] Additionally, it has been found that known methods for foam moulding do not always produce satisfactory results with innovative materials, particularly in terms of achieving acceptable fill levels, moisture and surface quality of the final product. Applicants propose that there is a need for foam moulding of innovative materials, such as recyclable or biodegradable materials. Summary of the invention

[0012] Purpose of the Invention

[0013] Therefore, the object of the present invention is to provide a mold for particle foam molding that partially overcomes the disadvantages of the prior art or at least provides an alternative mold for particle foam molding, such as a mold with lower environmental impact, suitable for innovative materials and / or providing a fused particle foam product of higher material quality, a drier fused particle foam product and / or a fused particle foam product with improved surface quality.

[0014] Technical Solution

[0015] The invention provides a mould for particle foam moulding according to claim 1. The mould comprises two mould sections, in particular a first mould section and a second mould section which is movable relative to the first mould section. The mould sections can be separated horizontally. The first mould section can form a lower section and the second mould section can form an upper section, or the first mould section can form an upper section and the second mould section can form a lower section. The mould sections can also be separated vertically or in one or more other directions. The first mould section and the second mould section can be adapted to cooperate with each other to form the mould, for example having complementary shapes.

[0016] The mold sections are movable between a closed position in which the first mold section and the second mold section define a cavity, a semi-closed position in which the first mold section and the second mold section are spaced farther apart from each other than in the closed position for filling the cavity, and an open position in which the first mold section and the second mold section are spaced a distance apart from each other to allow removal of the fused particle foam product from the cavity. In the open position, the distance between the mold sections may be greater than in the semi-closed position. The mold may include at least one actuator configured to move the mold sections.

[0017] The closed position may be a fusion position in which the mold segments are arranged to fuse the particles in the cavity. The first mold segment and / or the second mold segment may include a recess, which is enclosed by the second mold segment, the first mold segment, respectively, to define the cavity. The cavity may be partially arranged in the first mold segment and the second mold segment. The cavity is defined by inner walls of the mold segments facing each other in the closed position, such as the inner walls of the recess. The cavity may be completely surrounded by the first mold segment and the second mold segment in the closed position. In the closed position, the cavity may be shaped as a fused particle foam product produced with the mold. However, the cavity may be shaped slightly differently to compensate for the shrinkage and / or expansion of the fused particle foam product. The foamable particles arranged in the cavity in the closed position may form a fused particle foam product.

[0018] The semi-closed position may be a filling position in which the mold segments are configured to allow the cavity to be filled with particles, such as expandable particles. In the semi-closed position, the mold segments may completely surround the filling space. The filling space includes the cavity, but may be larger than the cavity in the closed position. The expandable particles may be filled in the filling space and thereby diffuse through the cavity. In this way, the filling of the cavity may be improved, for example relatively uniform.

[0019] The open position may be a removal position in which the mold segments are configured to allow removal of the foamed particle product from the cavity. The distance between the mold segments in the open position may be at least the width and / or height of the cavity, such that the foamed particle product may be removed when the mold segments are arranged in the open position. Additionally or alternatively, the first mold segment and / or the second mold segment may include detachable sub-segments that are movable relative to each other to allow removal of the foamed particle product from the cavity.

[0020] The mould comprises a filling device for feeding the expandable particles into the cavity in a semi-closed position. The filling device may be configured to feed expandable beads of thermoplastics, such as polymers. The filling device may be fluidly connected to the cavity in the semi-closed position to allow feeding by means of a fluid flow, such as a pneumatic fluid flow, towards the cavity. The filling device may also be fluidly connected to the cavity in a closed position to allow feeding in the closed position.

[0021] The mold includes a temperature control system for heating the cavity. The temperature control system can be configured to heat the inner wall of the first mold section and / or the second mold section. The temperature control system includes at least one injector configured to inject a controlled amount of a heating fluid into the cavity for fusing the foamable particles. The injector can be fluidly connected to the cavity. The injector can be configured to inject the heating fluid having a temperature equal to or higher than a temperature at which the foamable particles become deformable, i.e., moldable.

[0022] The amount of heating fluid is controlled so that the amount can be adjusted. For example, the amount can be controlled to inject enough heating fluid for fusion while keeping the moisture of the final product relatively limited. The injector can be adjustable to control the amount of heating fluid, for example, closable to control the amount of heating fluid.

[0023] The temperature control system may be configured to heat the cavity to at least a temperature at which the expandable particles fuse to form the particle foam, such as to at least the glass transition temperature of the expandable particles.

[0024] The mold may include a controller configured to control the temperature control system, the filling device, and / or the movement of the mold segments between respective positions.

[0025] The injector may be configured to be controlled to maintain the humidity in the cavity below a threshold and / or to prevent moisture from entering the cavity before and / or after fusion, for example during heating and cooling of the mold. In this way, condensation of the heating fluid in the cavity, for example on the inner walls of the mold segments, may be reduced or potentially avoided.

[0026] The mold also includes a cavity seal between the first mold section and the second mold section, the cavity seal including an inner seal and an outer seal. The inner seal can be arranged toward the inner wall of the mold section, and the outer seal can be arranged toward the outer wall of the mold section. The inner seal can be a particle seal configured to seal particles. The outer seal can be a fluid seal configured to seal fluids. The inner seal and the outer seal can be arranged circumferentially around the cavity. The inner seal and the outer seal can be concentric with each other, but can also have different shapes.

[0027] In the closed position, the inner seal and the outer seal cooperate to block particles and fluids from passing through the cavity. Therefore, the passage of particles and fluids can be substantially or completely blocked, so that the fusion of particles in the cavity can be performed under more desired conditions, i.e., less or even no particles and / or fluids flow into or out of the cavity in an uncontrolled manner. In the closed position, the cavity seal can seal the cavity into a fluid and particle seal. In the semi-closed position, the inner seal allows fluid to pass through and blocks particles from passing through the cavity. Therefore, the passage of particles can be substantially or completely blocked in the semi-closed position, and, for example, the cavity seal can seal the cavity into a particle seal.

[0028] In the closed position, the inner seal and the outer seal can be matched to be particle-tight and fluid-tight. The term particle-tight as referred to herein means the sealing of particles in the cavity for particle foam molding, for example, the sealing of expandable beads such as thermoplastics. In an embodiment, the particle-tight can refer to the sealing of solid particles. The particle-tight does not refer to fluid particles and is therefore not sealed to heating fluids.

[0029] The expandable particles may be expandable beads.The expandable particles may be thermoplastic particles, such as thermoplastic polymer particles.

[0030] By having an inner seal and an outer seal, the cavity can be filled in a semi-closed position so that the filling can be performed in a relatively large filling space, so that the uniformity of the filling is potentially improved. Since the outer seal is not fluid-tight in the semi-closed position, the cavity can be vented via the cavity seal for movement toward the closed position. By venting the mold, the pressure accumulated in the cavity due to the movement toward the closed position can be reduced.

[0031] By moving from the semi-closed position to the closed position, the particles in the cavity can be pressed against each other so that the filling uniformity and / or compactness can be improved. This filling method is referred to by the applicant as gap filling.

[0032] Furthermore, due to the cavity seal, the cavity pressure can be controlled to be higher than the ambient pressure and / or the particles can be provided at a flow rate of the material entering the cavity that is higher than the flow rate of the material flowing out of the cavity. In this way, by filling the particles in the cavity with an increased pressure, compression of the particles can be achieved. When the increased pressure in the cavity after filling is subsequently reduced, the particles can return to a less compressed form and press against each other, so that filling uniformity and / or compactness can be improved.

[0033] Similarly, the cavity pressure can be controlled to be lower than ambient pressure. In this way, particles can be drawn into the cavity, which can facilitate distribution of the particles through the cavity. Additionally or alternatively, the pressure in the cavity can be varied between a lower or negative pressure and a higher or overpressure.

[0034] This filling method using negative pressure and / or overpressure is called pressure filling by the applicant.

[0035] The benefit of the mould is that the conditions in the cavity can be controlled relatively accurately. In particular, the flow of fluid into and out of the cavity can be controllable. Compared to the prior art, due to the advantageous combination of double seals and syringes, the pressure and humidity in the cavity can be individually controllable, whereby the cavity can be ventilated via the cavity seal. This enables gap filling and / or pressure filling of the cavity without the need for porous walls with steam holes or nozzles. This has several advantages.

[0036] First, the amount of heating fluid can be adjusted precisely to the amount required for fusing the particles.

[0037] Secondly, the cavity can now reach a specific pressure that is conducive to achieving uniform filling without correspondingly affecting the pressure of the heating fluid.

[0038] Furthermore, when a negative pressure or a pressure below the heating fluid pressure is applied in the cavity, the amount of heating fluid in the cavity can be determined by the syringe so that no heating fluid is drawn into and / or through the cavity by the vacuum pump as in the prior art.

[0039] Thus, a relatively small amount of heating fluid can advantageously be used in the cavity, and the amount of condensate formed in the cavity can be relatively low. Thus, the mould can be particularly suitable for providing a fused particle foam product that is relatively dry during the fusion of the particles. Thus, the fused particle foam product can have a relatively high material quality, an improved surface quality. The fused particle foam product is sufficiently dry that the moulding process is referred to by the applicant as dry moulding. Thus, the present invention allows an improved filling of the cavity, whereby a relatively dry final product can be obtained. In particular, the final product can have a more attractive appearance, be more robust and / or have a better fluid seal than a fused particle foam product produced using moulds of the prior art.

[0040] In addition, when the heating fluid is injected into the cavity with a syringe, the distribution of the heating fluid in the cavity and outside the cavity can be controlled. This makes it possible, for example, to heat the cavity in different ways using the heating fluid in a separate heating-cooling chamber outside the cavity.

[0041] By subsequently injecting and draining the heating fluid into and from the cavity respectively and / or by having a separate heating-cooling chamber, the heating fluid can potentially be reused.Therefore, less fluid, such as steam, needs to be heated resulting in reduced energy consumption.

[0042] Thus, dry molding can be performed where the mold is filled by pressure filling and / or gap filling, such that the mold potentially has a lower environmental impact, can be suitable for innovative materials and / or can provide a fused particle foam product of higher material quality, a drier fused particle foam product and / or a fused particle foam product with improved surface quality.

[0043] In an embodiment, in the semi-closed position, the outer seal blocks the fluid from entering and / or leaving the cavity. In this way, the pressure in the cavity or the cavity pressure can be controlled in the semi-closed position. Therefore, the filling of particles can be performed by filling the particles into the cavity in the semi-closed position while applying a controlled pressure in the cavity, and pressure filling and gap filling can be combined. The mold can be fluid-tight in the semi-closed position.

[0044] In an embodiment, the mold comprises a pressure control system in fluid communication with the cavity for extracting fluid from the cavity, wherein the filling device is configured to feed the foamable particles under a filling pressure, and wherein the pressure control system is configured to influence the pressure in the cavity.

[0045] When feeding the expandable particles, the pressure in the cavity can, for example, be influenced to be above, equal to and / or below the filling pressure.

[0046] Due to the configuration of the inner seal, the flow of fluid through the inner seal may be limited. Therefore, the ventilation of the cavity may be limited by the pressure difference between the cavity pressure and the pressure outside the outer seal, such as ambient pressure. By having a pressure control system, the cavity ventilation can be advantageously increased. This can, for example, enable gap filling in a mold without a nozzle, because the pressure increase in the cavity due to the movement between the semi-closed position and the closed position can be limited by the pressure control system.

[0047] The pressure control system and / or the filling device may be controllable. For example, the filling device may include a particle feedstock containing particles under a filling pressure and a valve, such that when the valve is opened, the particles are filled under the filling pressure.

[0048] In this way, the cavity pressure can be controlled by varying the fill pressure and / or the draw rate of the pressure control system to affect the pressure in the cavity.

[0049] By actively pumping fluid from the cavity, the distribution of particles through the cavity can be improved so that better filling can be achieved.

[0050] Additionally or alternatively, the pressure control system can be configured to apply fluid in the cavity to increase the cavity pressure, such as for gap filling. In this configuration, the pressure control system can be configured to draw fluid from an external source rather than the cavity, and apply the drawn fluid in the cavity.

[0051] In an embodiment, the inner seal and the outer seal are spaced apart from each other and define a conduit, wherein in the semi-closed position the outer seal blocks fluid from entering the cavity, and wherein the pressure control system is fluidly connected to the cavity between the inner seal and the outer seal via the conduit.

[0052] The conduit may be arranged between the first mould section and the second mould section. The conduit may provide a movement space for moving the mould sections between a closed position and a semi-closed position. The conduit may be shaped to accommodate the first mould section and / or the second mould section in its closed position.

[0053] The conduit may extend between an inner end at the inner seal and an outer end at the outer seal. The conduit may fluidly connect the cavity to an external environment so that fluid from the cavity can be discharged from the cavity toward the environment and / or fluidly connect the cavity to a pressure control system so that fluid from the cavity can be extracted using the pressure control system.

[0054] In an embodiment, the pressure control system is separate from the temperature control system and is configured to control the pressure in the cavity independently of the heating fluid pressure in the temperature control system.

[0055] In this way, the heating and ventilation of the chamber can be performed separately, so that the temperature and pressure can be controlled relatively accurately.

[0056] The pressure control system and the temperature control system may be fluidly connected to the chamber via separate connections.

[0057] The inner seal and the outer seal of the lumen seal may extend around the circumference of the lumen such that a conduit extending between the inner seal and the outer seal extends around the circumference of the lumen.

[0058] In an embodiment, a circumferential conduit is formed around the cavity between the inner seal and the outer seal, wherein the pressure control system is fluidly connected to the cavity via the circumferential conduit. In this way, fluid extracted from the cavity can cause a flow towards the circumferential conduit. Particles filled in the cavity by the filling device can be sucked through the cavity by the fluid flow caused by the pressure control system. The pressure control system can be configured to cause a fluid flow towards the inner seal.

[0059] The circumferential conduit may extend substantially along the entire lumen seal.

[0060] By having a fluid flow toward the circumference of the cavity, such as toward the inner seal, particles may be diffused through the cavity, which may advantageously improve filling of border regions near the circumference and / or having relatively complex cavity shapes.

[0061] The pressure control system may be fluidly connected to a conduit extending around the circumference of the lumen.

[0062] In an embodiment, the temperature control system comprises a heating-cooling chamber arranged in the first mold section and / or the second mold section adjacent the cavity, wherein the temperature control system is configured to circulate a heating-cooling fluid through the heating-cooling chamber.

[0063] The temperature control system may include a heat source that can be fluidly connected to the heating-cooling chamber to provide a hot heating-cooling fluid, such as steam, and / or a cold source that can be fluidly connected to the heating-cooling chamber to provide a relatively cold heating-cooling fluid, such as water. In this way, the temperature in the cavity can be controlled by heating and / or cooling the walls of the cavity. The hot heating-cooling fluid can be a heating fluid or another fluid injected with a syringe. The heat source can provide the hot heating-cooling fluid, for example, at a pressure of at least 5 bar, for example 7 bar. The hot heating-cooling fluid can be provided at a temperature of at least the glass transition temperature of the foamable particles, for example at a temperature above 100° C., for example above 150° C., so that they fuse to form a particle foam.

[0064] The heating-cooling chamber may be formed by a double wall surrounding the cavity.

[0065] By having a separate heating-cooling chamber, the cavity can be heated independently of the injection of the heating fluid using the syringe. Thus, the mold can be heated without increasing the humidity in the cavity. Thus, preheating and cooling of the mold can be performed while maintaining a favorable moisture content in the cavity.

[0066] Thus, heating and cooling of the cavity may be performed in other production stages during fusing, for example when moving the mould segments between the closed position and a semi-closed position and / or an open position or during filling of the cavity with a filling device.

[0067] Thus, during the opening-closing movement of the mold halves, the next production cycle can start. This helps to shorten the cycle time.

[0068] In an embodiment, the temperature control system is configured to preheat the chamber prior to introducing the steam using the injector.

[0069] In an embodiment, the temperature control system is configured to cool the cavity during introduction of the heated fluid using the syringe.

[0070] In addition to or as an alternative to the heating-cooling chamber, the temperature control system may include other heating sources for heating the cavity, such as electrical heating, induction or microwave heating, or cooling sources for cooling the cavity, such as a heat pump.

[0071] In an embodiment, the heating-cooling chamber is separated from the pressure control system so that no heating-cooling fluid is drawn by the pressure control system. In this way, the energy consumption of the mold is improved. For example, in the prior art, steam would be consumed through the nozzle.

[0072] In an embodiment, supplying the heating fluid to at least one injector and supplying the heating fluid to the heating-cooling chamber are separate from each other. In this way, the characteristics of the heating fluid injected by the injector can be suitable for fusion, for example, hotter than the heating-cooling fluid in the heating-cooling chamber.

[0073] The heating-cooling chamber may be relatively thin compared to the cavity. For example, the heating-cooling chamber may have a volume that is less than 25%, such as less than 15%, of the cavity. The heating-cooling chamber may be arranged as a chamber having a relatively constant thickness around the cavity.

[0074] The heating-cooling chamber may be provided in the first mould section and the heating-cooling chamber may be provided in the second mould section.Therefore, substantially all walls surrounding the cavity may be heated and / or cooled.

[0075] In an embodiment, the heating-cooling system comprises a return conduit for reusing the heating-cooling fluid. The return conduit may be fluidly connected to the heat source.

[0076] In an embodiment, a wall of the first mould section and / or a wall of the second mould section adjacent to the cavity forms a substantially continuous surface which is interrupted only by the filling device and the at least one syringe.

[0077] Due to the advantageous configuration of the mold with the syringe, the filling device and the cavity seal, further openings in the wall surrounding the cavity, for example openings for ventilating the cavity, can be omitted.

[0078] As a result, particle foam products produced using the mould can have an improved surface quality, for example without irregularities caused by the nozzles.

[0079] In an embodiment, the wall of the first mold section adjacent to the cavity and / or the wall of the second mold section has a thermal conductivity in the range of bronze or aluminum. In this way, energy transfer from the temperature control system to the cavity can be relatively efficient. Bronze is particularly advantageous due to its relatively high thermal conductivity.

[0080] The syringe may include a valve that is movable between an open position and a closed position. The valve may be longitudinally movable, such as a piston. The syringe may be configured to be controlled between an open configuration of the valve, such as an open position, in which the source of heating fluid is fluidically connected to the cavity, and a closed configuration of the valve, such as a closed position, in which the source of heating fluid is not fluidically connected to the cavity. The syringe may be controlled, for example, electronically, hydraulically or pneumatically, such as by moving the piston, such as by applying fluid pressure.

[0081] The injector may be configured to inject the heating fluid at a pressure higher than the pressure in the cavity, for example a pressure of at least 1.5 bar, such as 1.8 bar to 2.1 bar. The temperature of the heating fluid may have at least the glass transition temperature of the foamable particles, such as a temperature of at least 100° C., such as at least 165° C. It has been found that in this way, good particle fusion can be achieved in a practical time. Preferably, the injected heating fluid may have a low steam content. The injected fluid may include saturated steam or superheated steam. In this way, the moisture content in the cavity may be kept relatively low.

[0082] In an embodiment, at least one of the injectors comprises a valve configured to be connected to a steam supply.The piston may be connected to a steam supply separate from the heating-cooling chamber.

[0083] The piston may be configured to inject a predetermined amount of heating fluid into the cavity when activated, such as by timed activation, controlled using a heating fluid flow sensor, etc. The piston may be activated electronically, pneumatically, and / or hydraulically.

[0084] In an embodiment, the outer seal is a telescopic seal. The outer seal may include a telescopically movable seal, such as a piston. The telescopic seal may be configured to extend between mold sections in a closed position, and may also be configured to extend between mold sections in a semi-closed position.

[0085] An advantage of a telescoping seal is that compressive forces, as opposed to shear forces, can be exerted on the mould sections as they move towards each other.

[0086] In an embodiment, the cavity seal comprises a second outer seal. The second outer seal may improve the sealing of the cavity seal. For example, the outer seal may be a shear loaded seal and the second outer seal may be a compression loaded seal. In this way, the sealing of the cavity in the closed position may be improved. The second outer seal may be arranged on respective sides of the first mold section and / or the second mold section facing each other. The second outer seal may be configured to be compressed in the closed position.

[0087] The invention also relates to the use of a mould according to any of the embodiments described herein for dry moulding of an object from expandable particles fed into the mould by a combination of gap filling and back pressure filling.

[0088] The invention also relates to a machine comprising a mould according to any of the embodiments described herein.

[0089] In this way, similar benefits as described herein for the mold may be achieved.

[0090] The present invention also relates to a method for particle foam molding, the method comprising the steps of filling a cavity defined by mold segments with foamable particles; moving the mold segments toward each other from a semi-closed position to a closed position, in which the mold segments are spaced farther apart from each other; heating the cavity and injecting a certain amount of heating fluid, such as steam, into the cavity to fuse the foamable particles, and moving the mold segments away from each other to an open position to allow the fused particle foam product to be removed from the cavity.

[0091] A cavity seal may be arranged between the mold sections. The cavity seal may include an inner seal and an outer seal. In the closed position, the inner seal and the outer seal may cooperate to block the passage of foamable particles and fluid from the cavity, as described herein. In the semi-closed position, the inner seal may allow the passage of fluid, for example, from the cavity, and block the passage of foamable particles, for example, from the cavity.

[0092] The step of filling the cavity can be performed in a semi-closed position. In this way, the cavity can be filled with a gap. In the closed position, particles and fluids can be blocked from passing through the cavity, and in the semi-closed position, fluids are allowed to pass through and particles are blocked from passing through the cavity.

[0093] In an embodiment, filling is performed in a semi-closed position, in which the foamable particles and fluid are blocked from passing through the cavity, and in a semi-closed position, the fluid is allowed to pass through the cavity while the foamable particles are blocked from passing through the cavity. In this way, gap filling and pressure filling can be advantageously combined to fill the cavity with particles.

[0094] In an embodiment, wherein the foamable particles are delivered under a filling pressure, the method comprises the step of extracting fluid from the cavity when filling the cavity to influence the pressure in the cavity, for example to make the pressure in the cavity equal to and / or below the filling pressure.

[0095] In an embodiment, fluid is drawn from the lumen along the circumference of the lumen, such as via a conduit extending between an inner seal and an outer seal of the lumen.

[0096] In an embodiment, the step of heating the cavity is performed at least during the step of moving the mould segments towards each other, for example from a semi-closed position into a closed position. For example, heating may also be performed when the mould segments move from an open position into a semi-closed position.

[0097] In an embodiment, the step of heating the cavity is performed during the step of moving the mould segments towards each other. In particular, the cavity may be heated without injecting a heating fluid. By heating before and / or during the movement of the mould segments, production speeds may be relatively high.

[0098] In an embodiment, the fused particle foam product produced by the method has a substantially continuous surface interrupted only by the markings of the filling device and the at least one injector.

[0099] In an embodiment, a single fused particle foam product is produced using a mold. Because molds can be energy efficient, applicants have discovered that it can be economically feasible to produce a single product using a mold, rather than producing a large number of products per mold as is typically the case.

[0100] The expandable particles may include thermoplastics, for example polymers such as expandable polystyrene, expandable polypropylene, expandable thermoplastic polyurethane, or other materials.

[0101] In an embodiment, the method is performed using a mold according to any of the embodiments described herein, such as according to claims 1 to 13 and / or using a particle foam machine according to any of the embodiments described herein, such as according to claim 14. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Further features of the invention will be explained below with reference to the embodiments shown in the accompanying drawings, in which:

[0103] Figure 1 schematically depicts a side view in cross section of an embodiment of a mold according to the invention, wherein the mold is arranged in an open position;

[0104] Figure 2A Schematically depicts Figure 1 A side view of a cross section of a mold, wherein the mold is arranged in a semi-closed position;

[0105] Figure 2B Schematically depicts Figure 2A A side view of a cross section of a mold of , wherein expandable particles are disposed in the cavity;

[0106] Figure 2C Schematically depicts Figure 2B a side view of a cross-section of a mold, wherein the mold is arranged in a closed position;

[0107] Figure 2D Schematically depicts Figure 2C a side view of a cross-section of a mold wherein steam is injected by a syringe; and

[0108] Figure 2E Schematically depicts Figure 2D A side view of a cross-section of a mold wherein the mold is arranged in an open position to remove a fused particle foam product.

[0109] In all the drawings, the same reference numerals are used to designate corresponding parts or parts having corresponding functions. DETAILED DESCRIPTION

[0110] Figure 1 A mold 10 for particle foam molding is depicted. The mold 10 comprises a first mold section 1 and a second mold section 2 that is movable relative to the first mold section 1. The mold sections 1, 2 are horizontally separated and movable by means of an actuator. The first mold section 1 forms an upper section and the second mold section 2 forms a lower section. The first mold section 1 and the second mold section 2 have complementary shapes and are adapted to cooperate with each other to form the mold 10.

[0111] exist Figure 2C to Figure 2D In the closed position of the mold, the first mold segment 1 and the second mold segment 2 define a cavity 3. The closed position is a fusion position in which the mold segments 1, 2 are arranged for fusing the foamable particles 99 in the cavity 3. The first mold segment 1 includes a recess, which is closed by the second mold segment 2 in the closed position to define the cavity 3. The cavity 3 is defined by the inner walls 31, 32 of the mold segments 1, 2 facing each other in the closed position. The cavity 3 is completely surrounded by the first mold segment 1 and the second mold segment 2 in the closed position. The cavity 3 has a height h. In the closed position, the cavity 3 is shaped into a fused particle foam product 98 produced using the mold. The foamable particles 99 arranged in the cavity 3 in the closed position can form a fused particle foam product 98.

[0112] exist FIG. 2A to FIG. 2B In the semi-closed position of FIG. 1 , the first mold section 1 and the second mold section 2 are spaced further apart from each other than in the closed position for filling the cavity 3. The first mold section 1 and the second mold section 2 are spaced apart from each other by a distance C of 20 mm. The semi-closed position is a filling position in which the mold sections 1 , 2 completely enclose a filling space 3' which includes the cavity 3 but is larger than the cavity 3 in the closed position.

[0113] exist Figure 1In the open position of the mold, the first mold section 1 and the second mold section 2 are spaced apart from each other by a distance d1 that is greater than the distance in the semi-closed position to allow removal of the fused particle foam product 98 from the cavity 3. The open position is a removal position in which the mold sections 1, 2 are configured to allow removal of the foam particle product 98 from the cavity 3. In the open position, the minimum distance d2 between the mold sections 1, 2 is at least the height h of the cavity in the closed position so that the fused particle foam product 98 can be removed from the cavity 3.

[0114] The mold 10 comprises a filling device 4 to feed expandable particles 99, in particular expandable beads of a thermoplastic polymer, into the cavity 3. The filling device 4 is fluidly connected to the cavity 3 via a filling opening 34 in the inner wall 31 of the first mold section. A valve is arranged between the particle feedstock (not shown) and the filling opening 34. The particle feedstock comprises pressurized air at a filling pressure and polymer beads at a filling pressure. The valve opens in a semi-closed position to allow feeding by means of a fluid flow, such as a pneumatic fluid flow, towards the cavity.

[0115] The mold includes a temperature control system 5 for heating the cavity 3. The temperature control system 5 is configured to heat the inner walls 31, 32 of the first mold section 1 and the second mold section 2. The temperature control system 5 includes at least one injector 51, which is configured to inject a controlled amount of heating fluid into the cavity for fusing the foamable particles 99. The injector 51 is fluidly connected to the cavity 3 via the injector opening 33. The injector 51 is configured to inject a heating fluid having a temperature equal to or higher than the temperature at which the foamable particles become deformable, i.e., moldable. The amount of heating fluid is controlled by opening and closing the injector 51 by moving the valve 57, so that the amount of heating fluid, i.e., steam in this embodiment, can be adjusted. The valve is a movable piston 57, which is moved by applying or removing fluid pressure via the control port 56.

[0116] At least one injector 51 comprises a valve 57 configured to be connected to a steam supply via port 55. The steam supply (not shown) is separate from the heating-cooling chamber 52. The piston 57 is configured to inject a predetermined amount of heating fluid into the cavity 3 upon activation by timed activation.

[0117] In this embodiment, valve 57 is able to move longitudinally between an open position and a closed position, in which the steam supply port 55 and chamber 3 are fluidly connected via fluid path F, and in which the piston 57 closes the passage between the steam supply port 55 and the chamber. The piston is biased in the open position by a spring. The piston 57 is held in the closed position by applying fluid pressure via control port 56, so that when the pressure is temporarily removed via control port 56, the piston 57 is pushed to the open position by the spring.

[0118] The mold 10 also includes a cavity seal 6 located between the first mold section 1 and the second mold section 2, and the cavity seal 6 includes an inner seal 61 and an outer seal 62. The inner seal 61 is arranged toward the inner walls 31, 32 of the mold sections 1, 2. The outer seal 62 is arranged toward the outer walls of the mold sections 1, 2. The inner seal 61 is a particle seal configured to seal particles. The outer seal 62 is a fluid seal configured to seal fluids. The inner seal 61 and the outer seal 62 are arranged circumferentially around the cavity.

[0119] In the closed position, the inner seal 61 and the outer seal 62 cooperate to block particles and fluids from passing through the cavity 3. For additional blocking, the cavity seal 6 includes an optional second outer seal 63, which is a compression seal. The outer seal 62 includes an o-ring. The outer seal 62 can also be arranged in the place of the second outer seal 63, and then can additionally or alternatively include a telescopic seal, such as a telescopic film.

[0120] In the closed position, the cavity seal 6 seals the cavity 3 to be impermeable to fluids and particles. In the semi-closed position, the inner seal 61 allows fluid to pass through and blocks particles from passing through the cavity 3 (i.e., from the filling space 3'). In the semi-closed position, the cavity seal 6 seals the cavity 3 (i.e., the filling space 3') to be impermeable to particles. In the semi-closed position, the outer seal 62 blocks fluid from entering and / or leaving the cavity 3 (i.e., the filling space 3'), so that the mold is impermeable to fluids in the semi-closed position.

[0121] The inner seal 61 and the outer seal 62 are spaced apart from each other and delimit a duct 71 , wherein, in the semi-closed position, the outer seal 62 blocks the passage of fluid from the chamber 3 .

[0122] The conduit 71 is arranged between the first mold section 1 and the second mold section 2 and provides space for moving the mold sections 1, 2 between the closed position and the semi-closed position. The conduit is shaped to accommodate the movement of the first mold section 1 and the second mold section 2 toward their closed positions. The conduit 71 extends between an inner end at the inner seal 61 and an outer end at the outer seal 62.

[0123] The mold 10 includes a pressure control system 7 that is fluidly connected to the cavity 3 for extracting fluid from the cavity 3. The filling device 4 is configured to feed the foamable particles 99 at the filling pressure, and the pressure control system 7 is configured to affect the pressure in the cavity 3 to be equal to and / or lower than the filling pressure when the foamable particles 99 are fed. The pressure control system 7 includes a pump (not shown) that is fluidly connected to the mold 10. The pressure control system 7 and the filling device 4 are controllable. The cavity pressure can be controlled by changing the filling pressure and / or the extraction rate of the pressure control system 7 to affect the pressure in the cavity 3. Additionally, the pressure control system 7 is configured to apply fluid in the cavity to increase the cavity pressure, for example for gap filling. The pressure control system 7 is separated from the temperature control system 5 and is configured to control the pressure in the cavity independently of the heating fluid pressure in the temperature control system 5. The pressure control system 7 and the temperature control system 5 are fluidly connected to the cavity 3 via separate connectors 33, 71.

[0124] The conduit 71 fluidly connects the chamber 3 with the pressure control system 7 so that fluid from the chamber can be extracted using the pressure control system. The pressure control system 7 is fluidly connected to the chamber 3 via the conduit 71 between the inner seal 61 and the outer seal 62.

[0125] The inner seal 61 and the outer seal 62 extend around the circumference of the chamber 3, so that the conduit 71 extending between the inner seal 61 and the outer seal 62 extends around the circumference of the chamber 3. The pressure control system 7 is fluidly connected to the chamber along the circumference of the chamber 3, so that extracting fluid from the chamber will cause flow toward the circumference. Therefore, the pressure control system 7 is configured to cause fluid flow toward the inner seal 61.

[0126] The mould 10 comprises a controller configured to control the filling device 4 , the temperature control system 5 , the pressure control system 7 and actuators for controlling the movement of the mould sections 1 , 2 .

[0127] The injector 51 is configured to be controlled to maintain the humidity in the cavity 3 below a threshold value and prevent moisture from entering the cavity 3 before and / or after fusion, such as during heating and cooling of the mold 10 .

[0128] The temperature control system 5 includes two heating-cooling chambers 52, including a heating-cooling chamber 52 arranged in the first mold section 1 and a heating-cooling chamber 52 arranged in the second mold section 2. The heating-cooling chambers 52 are arranged adjacent to the cavity 3, and the temperature control system 5 is configured to circulate a heating-cooling fluid, such as water, through the heating-cooling chambers 52.

[0129] The temperature control system 5 includes a heat source for providing a hot heating-cooling fluid, such as steam, and a cold source for providing a relatively cold heating-cooling fluid, such as water (not shown). The heat source and the cold source may be controllable and fluidly connected to the heating-cooling chamber via inlet and outlet conduits 53, 54 in the mold sections 1, 2.

[0130] For example, the heat source may provide the hot heating-cooling fluid at a pressure of at least 5 bar, such as 7 bar. The hot heating-cooling fluid may be provided at a temperature of at least the glass transition temperature of the expandable particles, such as at a temperature above 100°C, such as 165°C.

[0131] The first mold section comprises two parts 11, 12, and the second mold section comprises two parts 21, 22, between which the heating-cooling chamber 52 is arranged, so that the heating-cooling chamber 52 is formed by a double wall. The heating-cooling chamber 52 is relatively thin compared to the cavity 3, and the heating-cooling chamber 52 each has a volume less than 25%, in particular less than 15% of the cavity. The heating-cooling chamber is arranged as a chamber with a relatively constant thickness around the cavity 3.

[0132] A heating-cooling chamber 52 is provided in the first mould section 1 and a heating-cooling chamber 52 is provided in the second mould section 2. Thus, substantially all walls surrounding the cavity can be heated and / or cooled.

[0133] The outlet port 54 forms a return conduit for reusing the heating-cooling fluid. The return conduit may be fluidly connected to a heat source.

[0134] The heating-cooling chamber 52 is separated from the pressure control system 7 so that no heating-cooling fluid is drawn by the pressure control system 7. The supply of the heating fluid to the at least one injector 51 is performed via the steam injector port 55, and the supply of the heating fluid to the heating-cooling chamber 52 is performed via the conduits 53, 54, so that the supplies are separated from each other. The first conduit 53 serves as an inlet conduit and the second conduit 54 serves as an outlet conduit, and vice versa. The properties of the heating fluid injected by the injector 51 are suitable for fusion, for example, hotter than the heating-cooling fluid in the heating-cooling chamber 52.

[0135] The temperature control system 5 is configured to preheat the chamber 3 before the steam is introduced by the injector 51 , and to cool the chamber 3 during the introduction of the heating fluid by the injector 51 .

[0136] The inner walls 31, 32, i.e. the walls of the first mold section 1 and the second mold section 2 adjacent to the cavity 3, form a substantially continuous surface which is interrupted only by the filling device 7 and the at least one injector 51. The portions 12, 21 of the first mold section 1 and the second mold section 2 adjacent to the cavity forming the inner walls 31, 32 have the thermal conductivity of bronze.

[0137] In use, the mould sections 1, 2 are first positioned in a semi-closed position. Then, the cavity 3 is filled with foamable particles 99, for example expandable thermoplastic polyurethane particles, via the filling device 4 at a filling pressure. At the same time, the cavity 3 can be kept at a predetermined pressure different from the ambient pressure and different from the filling pressure via a pressure control system 7, which is connected along the circumference of the cavity 3 to introduce a fluid flow through the cavity 3, thereby improving the filling of the cavity 3. In addition, during filling, the inner walls 31, 32 of the cavity 3 are already heated via the heating-cooling chamber 52 by pumping a heating fluid from a heat source, without moisture entering the cavity 3. The heating fluid is circulated and reused after being reheated by the heat source. No heating fluid is injected into the cavity 3.

[0138] The mold sections 1, 2 are then moved toward the closed position. In this way, the particles 99 are compressed and gap filling (by moving from the semi-closed position to the closed position after filling the cavity) and pressure filling (by keeping the cavity at a predetermined pressure using the pressure control system 7) are combined. Instead of a combination of filling in the semi-closed position, the cavity 3 can be filled in the closed position.

[0139] Then, a controlled amount of steam is injected into the cavity 3 via the fluid path F by the injector 51 at a pressure higher than the pressure in the cavity, for example at a pressure of 1.8 bar to 2.1 bar and at a temperature higher than the temperature at which the foamable particles become deformable, i.e., moldable. By temporarily removing the continuous fluid pressure at the control port 56, the valve 57 is briefly moved by the controller to the open position to fluidly connect the steam supply port 55 to the cavity 3.

[0140] Water is then pumped through the heating-cooling chamber 52 to cool the inner walls 31 , 32 of the cavity. During cooling, the mould sections 1 , 2 are moved towards an open position for removing the fused particle foam product 99 from the cavity 3.

[0141] As explained above, the inner walls 31, 32 are heated prior to the injection of steam into the cavity 3, resulting in relatively little or no condensation in the cavity during the fusion of the foamable particles 99. In addition, no moisture enters the cavity 3 before and after fusion, such as during the heating and cooling of the mold 10. Thus, the fused particle foam product 99 has a substantially continuous surface that is interrupted only by the markings of the filling device 4 and the at least one injector 51.

Claims

1. A mould (10) for particle foam moulding, such as dry moulding, comprising: - a first mould section (1); - a second mould section (2) which is movable relative to the first mould section between the following positions: a closed position in which the first mold section (1) and the second mold section (2) define a cavity (3); a semi-closed position in which the first mould section (1) and the second mould section (2) are spaced further apart from each other than in the closed position for filling the cavity (3); as well as an open position in which the first mold section (1) and the second mold section (2) are spaced a distance (d) from each other to allow removal of a fused particle foam product (98) from the cavity; - filling means (4) for feeding expandable particles (99) into the cavity (3) in the semi-closed position; - a temperature control system (5) for heating the cavity, wherein the temperature control system comprises at least one injector (51) configured to inject a controlled amount of a heating fluid, such as steam, into the cavity (3) for fusing the foamable particles; and - a cavity seal (6), the cavity seal (6) being located between the first mold section (1) and the second mold section (2), the cavity seal (6) comprising an inner seal (61) and an outer seal (62), wherein, in the closed position, the inner seal (61) and the outer seal (62) cooperate to block the passage of foamable particles and fluid from the cavity (3), and in the semi-closed position, the inner seal (61) allows the passage of fluid and blocks the passage of foamable particles from the cavity (3).

2. The mold according to claim 1, wherein: In the semi-closed position, the outer seal (62) blocks fluid from entering and / or leaving the cavity.

3. The mold according to claim 1 or 2, further comprising a pressure control system (7) in fluid communication with the cavity for extracting fluid from the cavity (3), in, The filling device (4) is configured to feed expandable particles under a filling pressure, and wherein the pressure control system (7) is configured to influence the pressure in the cavity.

4. The mold according to claim 2 and 3, wherein: The inner seal (61) and the outer seal (62) are spaced apart from each other and define a conduit (71), wherein in the semi-closed position, the outer seal blocks fluid from entering the cavity, and wherein the pressure control system (7) is fluidically connected to the cavity between the inner seal and the outer seal via the conduit (71).

5. The mold according to claim 3 or 4, wherein: The pressure control system (7) is separate from the temperature control system (5) and is configured to control the pressure in the chamber independently of the heating fluid pressure in the temperature control system.

6. The mold according to any one of claims 3 to 5, wherein: A circumferential duct (71) is formed around the cavity between the inner seal (61) and the outer seal (62), and wherein the pressure control system (7) is fluidically connected to the cavity (3) via the circumferential duct (71).

7. A mould according to any one of the preceding claims, wherein The temperature control system further comprises a heating-cooling chamber (52) arranged in the first mould section (1) and / or the second mould section (2) adjacent to the cavity, wherein the temperature control system (5) is configured to circulate a heating-cooling fluid through the heating-cooling chamber (52).

8. The mold according to any one of claims 2 to 6 and claim 7, wherein: The heating-cooling chamber (52) is separated from the pressure control system (7) so that no heating-cooling fluid is drawn by the pressure control system.

9. The mold according to claim 7 or 8, wherein: Supplying the heating fluid to the at least one injector (51) and supplying the heating fluid to the heating-cooling chamber (52) are separate from each other, and wherein the heating-cooling chamber (52) comprises a return conduit (54) for reusing the heating-cooling fluid.

10. A mould according to any one of the preceding claims, wherein The wall (31) of the first mould section and / or the wall (32) of the second mould section adjacent to the cavity forms a substantially continuous surface which is interrupted only by the filling device (4) and the at least one injector (51).

11. A mould according to any one of the preceding claims, wherein A wall (31) of the first mold section and / or a wall (32) of the second mold section adjacent to the cavity has a thermal conductivity in the range of bronze or aluminum.

12. A mould according to any one of the preceding claims, wherein The at least one syringe (51) comprises a valve (57) configured to be connected to an external fluid supply.

13. A mould according to any one of the preceding claims, wherein The outer seal (62) is a telescopic seal.

14. Use of a mould (10) according to any one of the preceding claims for dry moulding of an object from expandable particles fed into the mould by a combination of gap filling and back pressure filling.

15. A particle foam machine comprising a mould according to any one of the preceding claims.

16. A method for particle foam molding comprising the steps of: - filling the cavity (3) defined by the mould segments with expandable particles; - moving the mould sections (1, 2) from a semi-closed position towards each other into a closed position; - heating the cavity (3) and injecting a quantity of a heating fluid, such as steam, into the cavity for fusing the expandable particles (99); - moving the mould sections (1, 2) away from each other into an open position for removing the fused particle foam product (98) from the cavity; in, A cavity seal (6) is arranged between the mold sections, and the cavity seal (6) includes an inner seal (61) and an outer seal (62), wherein in the closed position, the inner seal (61) and the outer seal (62) cooperate to block the foamable particles and the fluid from passing through the cavity (3), and in the semi-closed position, the inner seal (61) allows the fluid to pass through and blocks the foamable particles from passing through the cavity.

17. The method according to claim 16, wherein: The expandable particles are fed under a filling pressure, the method further comprising the step of extracting fluid from the cavity (3) to influence the pressure in the cavity when the cavity (3) is filled.

18. The method according to claim 17, wherein: Fluid is extracted from the chamber (3) along the circumference of the chamber (3).

19. The method according to any one of claims 16 to 18, wherein: The step of heating the cavity (3) is performed at least during the step of moving the mould segments from the semi-closed position towards each other into the closed position.

20. The method according to any one of claims 16 to 17, wherein: The fused particle foam product has a substantially continuous surface interrupted only by indicia of the filling device and at least one syringe.

21. A method according to any one of claims 16 to 20, using a mould according to any one of claims 1 to 13 and / or using a particle foam machine according to claim 15.

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