Molding tool arrangement and method for producing a foam body with through holes

Abstract

Molding tool assembly (300) comprising: a first tool (320) having at least one projection (324) for creating at least one hole (420) in a foam body (400); a second tool (310) configured to cooperate with the first tool (320) to define at least one foam body cavity (330) for forming the foam body (400), the second tool (310) defining a cavity (314) having a cross-section corresponding to a cross-section of the projection (324); at least one movable piston (200) for burr removal, corresponding to and at least partially disposed within the cavity (314) in the second tool (310), and movable between a released position when the first (320) and second tools (310) are separated and an engaged position when the first (320) and second tools (310) are closed; and an actuator configured to move the movable piston (200) between the engaged position and the released position, wherein in the engaged position, the movable piston (200) contacts the projection (324) to seal the cavity (314), and in the released position, at least a portion of the movable piston (200) extends below a bottom surface of the second tool (310) into the hole (420) of the foam body (400).

Description

TECHNICAL FIELD

[0001] The present application relates to an arrangement of molding tools, in particular a molding tool for molding a foam body with holes and a method for molding a foam body with holes. BACKGROUND

[0002] Vehicle seats are typically formed from molded foam bodies that form the cushions. A plurality of climate or comfort holes may be formed extending through the foam body to achieve the desired airflow for comfort. The climate holes may provide airflow paths through the cushion to heat and / or cool the occupant's surface for climate comfort by extending from the underside of the cushion to the occupant's surface. The comfort holes may also provide seating comfort, in particular for varying the hardness of the foam body. DE 10 2017 108 449 A1 discloses a method for molding a foamed resin molded article, a molding tool, and a foamed resin molded article. DE 10 2013 209 465 A1 discloses a foam part with a foam layer, wherein the foam layer has a plurality of comfort tubes facing the user.DE 198 01 328 A1 discloses a device for producing foamed molded bodies. AT 506 068 B1 relates to a block mold for producing perforated insulation panels. JP 2005 193 483 A relates to a method for producing a foam, and in particular to a method for producing a foam with a vent hole. SUMMARY

[0003] The object underlying the invention is to provide a molding tool assembly for molding a foam body with cavities, whereby thin-film molding due to foam leakage through the cavities is at least reduced. This object is achieved by the features of claims 1, 9, and 14, respectively.

[0004] According to the invention, a molding tool assembly comprises a first tool having at least one projection for creating at least one corresponding hole in a foam body, and a second tool configured to cooperate with the first tool to define at least one foam body cavity for molding the foam body. The second tool defines a cavity having a cross-section corresponding to a cross-section of the projection. The molding tool assembly also comprises at least one movable flash removal piston corresponding to the projection and located at least partially within the cavity in the second tool, and movable between a disengaged position when the first and second tools are separated and an engaged position when the first and second tools are closed.The mold assembly also includes an actuator configured to move the movable piston between the engaged position and the released position. In the engaged position, the movable piston contacts the protrusion to seal the cavity, and in the released position, at least a portion of the movable piston extends beneath a bottom surface of the second mold into the hole of the foam body.

[0005] In one or more embodiments, the actuator may be preloaded in the engaged position so that, in the engaged position, the protrusion may urge the movable piston against the preload. In certain embodiments, the actuating element may be a spring, and the movable piston may be displaced between the engaged position and the released position by compression and decompression of the spring. Furthermore, the spring may be positioned around a shaft body of the movable piston within the cavity to compress and decompress based on movement of the movable piston. In further embodiments, the spring may have a spring rate of at least 5 N / mm. In at least one embodiment, the movable piston may include a rib portion around at least a portion of a circumference of the movable piston.In further embodiments, the rib portion may contact an inner wall of the second tool defining the cavity and remove the foam from the cavity as the movable piston moves between the engaged position and the released position. In at least one embodiment, the actuator may be a hydraulic actuator to push the movable piston into the engaged position after the movable piston has been moved into the engaged position via engagement with the projection.

[0006] According to another aspect, the invention comprises a molding tool assembly comprising a first tool having at least one protrusion for creating a corresponding at least one hole in a foam body, and a second tool configured to cooperate with the first tool to define a foam body cavity for molding the foam body. The second tool defines a cavity having a cross-section corresponding to a cross-section of the protrusion. The molding tool assembly further comprises at least one movable flash removal piston corresponding to the protrusion and located at least partially within the cavity in the second tool.The movable piston is movable between a disengaged position when the first and second tools are separated and an engaged position when the first and second tools are closed, the movable piston being biased toward the disengaged position. In the engaged position, the movable piston contacts the protrusion to seal the protrusion cavity, and in the disengaged position, the bias displaces the movable piston such that at least a portion of the movable piston extends below a bottom surface of the second tool into the hole.

[0007] The first tool comprises a plurality of protrusions, and the second tool comprises a plurality of cavities corresponding to the plurality of protrusions. The mold assembly further comprises a plurality of movable pistons with a respective movable piston for each of the plurality of protrusions. In at least one embodiment, the mold assembly may further comprise an actuator cooperating with the movable piston to bias the movable piston to the released position, wherein the actuator may be a spring having a spring rate of at least 5 N / mm. In certain embodiments, the protrusion has a diameter of 5 to 35 mm. In at least one embodiment, in the engaged position, a bottom of the movable piston may be substantially aligned with the bottom surface.In one or more embodiments, the movable piston may include a rib portion around at least a portion of a circumference of the movable piston, wherein the rib portion contacts an inner wall of the second tool defining the cavity and removes the foam from the cavity as the movable piston moves between the engaged position and the released position.

[0008] In another aspect, the invention comprises a method for forming a foam body with holes. The method comprises providing a first tool having a projection and a second tool having a cavity corresponding to the projection, the first and second tools cooperating to define at least one foam body cavity to form a mold assembly, and positioning at least one movable piston at least partially within the cavity. The method also comprises closing the mold assembly such that the movable piston engages the projection to seal the cavity and forming a foam body, the projection forming a hole. The method further comprises opening the mold assembly such that the movable piston releases the projection and removes the foam from the hole.A cross section of the cavity corresponds to a cross section of the projection.

[0009] Closing the mold assembly forces the movable piston at least partially into the cavity upon engagement with the protrusion. The movable piston is positioned at least partially beneath a bottom surface of the second tool upon opening of the mold. In at least one embodiment, closing and opening may move the movable piston through a height based on an actuator. In some embodiments, the actuator may be biased such that engagement of the movable piston with the protrusion stores energy in the actuator to move the piston through the height upon opening. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic representation of a partial cross-section of a conventional mold assembly; Fig. 2 is a schematic representation of a cross-section of a shaft assembly for a forming tool according to one embodiment; and Fig. 3A-C are schematic representations of a partial cross-section of a mold having a shaft assembly that forms foam with holes, according to one embodiment. DETAILED DESCRIPTION

[0010] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or reduced to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously utilize the present invention.

[0011] Furthermore, unless expressly stated otherwise, all numerical quantities in this specification and in the claims are to be understood as being modified by the word "about" in describing the broader scope of this invention. Practice within the stated numerical limits is generally preferred. Also, unless expressly stated otherwise, the description of a group or class of materials as suitable or preferred for a particular purpose in connection with the invention implies that mixtures of two or more members of the group or class may be equally suitable or preferred.

[0012] When forming holes to promote flow for air conditioning and comfort applications in a molded foam body, the molding tool includes a plurality of protrusions on a first tool that extend toward a second tool such that, when the tool is closed, the foam is molded around these protrusions, which correspond to each of the holes formed in the molded foam body. The holes may extend a height of the molded foam body and be continuous from a bottom to a top of the molded foam body such that the hole is open on both surfaces. The continuous aspect of the holes is particularly helpful for air conditioning holes where airflow through the hole is desired.The opening at the bottom of the molded foam body is formed by the bottom of the protrusion in the first tool, but the opening at the top of the foam body near the second tool may have flashing around the edges at the interface between the molds during production, or may have a thin film covering one end of the through-hole formed by foam leaking into the second tool. When manufacturing the through-holes, these thin layers or films forming over the top of the hole require the foam body to be inspected after molding and trimmed in a post-processing step to remove the material from the top of the hole. In addition, the flash forming at the interface between the upper and first tools can affect the uniformity of the through-hole in the foam body.Therefore, conventional foam molding processes usually require post-processing to remove the burr or thin films formed at the interface between the first and second tools to open the end of each of the holes.

[0013] In Fig. Figure 1 is a schematic cross-sectional view of a conventional mold assembly 100 for molding a foam body with climate / comfort holes. Hereinafter, the climate / comfort holes are generally referred to as holes. The conventional mold assembly 100 includes a first tool 120 and a second tool 110 that cooperate to form a cavity that is filled with foam and forms the foam body. To form the holes in the foam body, the first tool 120 includes a base member 122 and a plurality of projections that extend upward from the first tool 120 toward the second tool 110. Although in Fig. 1, only one protrusion 124 is shown, the first tool 120 may include any number of protrusions in any suitable arrangement as desired for the foam body due to design or comfort considerations, and reference to a single protrusion in the mold is shown as an example of a portion of the mold assembly. The second tool 110 includes a body 112 defining a plurality of cavities 114, each of which corresponds to one of the protrusions 124. Again, Fig. 1 shows a partial view of the mold assembly, and only one cavity 114 is shown, however, the second tool 110 may include any number of cavities based on the protrusions 124. The cavity 114 of the second tool receives the top end of the protrusion 124 so that the foam can flow around the protrusion 124 to form a through hole in the foam body from top to bottom. In a conventional assembly 100, the foam may leak into the cavity 114 and over the top end of the protrusion 124, forming a thin film over the opening of the hole and forming a flash at the interface between the second tool 110 and the first tool 120 at the hole. Therefore, post-molding processing steps are typically required to correct the thin film and flash issues.

[0014] With reference to Fig. 2 shows a schematic representation of a shaft assembly or a movable piston 200 according to one embodiment. The terms “shaft assembly” and “movable piston” may be used interchangeably hereinafter. The movable piston 200 is used with a mold assembly to remove the burr and the thin film layer from the through-hole in the cushion body upon opening of the mold assembly, so that post-processing is not necessarily required. The movable piston 200 is movable between an engaged position and a released position within the mold by an actuator, such as a solenoid valve, a pneumatic actuator, a hydraulic actuator, a spring, etc. The actuator may be automated, due to a preload (i.e., a spring, as in Fig. 2) or other suitable mechanism for moving the movable piston 200 between an engaged position and a released position. The movable piston 200 may be individually coupled to an actuator, or there may be a single external (assembly-associated) actuator for controlling the piston movement within the assembly. Although in Fig. 2 a piston 210 and a spring 250 are shown as contact for the protrusion and the actuator, respectively, any other suitable mechanism (hydraulically controlled ram, magnets, etc.) may be used to move the movable piston between an engaged state (where the protrusion contacts the movable piston to seal the cavity of the first tool against foam leakage via the protrusion) and a disengaged state (where the bottom of the movable piston 200 is positioned vertically below the bottom surface of the body 312 of the second tool 310 so that it removes burr or a thin film formed at the hole opening (as in Fig. 3A-C shown).

[0015] In the Fig. 3A-C, the engaged and disengaged positions of the movable piston 200 are coordinated with the closed and open positions of the mold assembly 300, respectively. The mold assembly 300 is shown with the movable piston 200 and includes a second tool 310 and a first tool 320 that cooperate to form a cavity 330 for the foam filling and the formation of the foam body 400. To form the holes in the foam body 400, the first tool 320 includes a base member 322 and a projection 324 that extends upward from the first tool 320 toward the second tool 310. Although in Fig. 3A-C, only one protrusion 324 is shown, the first tool 320 may include any number of protrusions in any suitable arrangement desired for the foam body 400 due to design or comfort considerations, and reference to a single protrusion is illustrative of a portion of the molding tool assembly 300. Hereinafter, reference to the protrusion 324 is singular and is not intended to be limiting. Furthermore, although not shown in the figures, the protrusion 324 may be located on the second tool and the features may be interchanged between the upper and first tools. The size of the protrusion 324 may be determined based on the desired size of the hole in the foam body 400.In one or more embodiments, the protrusions may have a diameter of about 5 to 35 mm, in other embodiments a diameter of about 7 to 30 mm, and in still other embodiments a diameter of about 10 to 25 mm. Thus, the resulting hole 420 in the foam body 400 may have a diameter of about 5 to 35 mm in certain embodiments, a diameter of about 7 to 30 mm in other embodiments, and a diameter of about 10 to 25 mm in still other embodiments. In one or more embodiments, the protrusions have a uniform size and shape, in other embodiments, each protrusion has a unique size or shape, and in still other embodiments, there are sets of protrusions that correspond to a particular size or shape.Although the protrusions in the figures have a round cross-section, the protrusions may have any cross-sectional shape to provide the air conditioning holes that allow airflow through the body of the foam cushion, such as, but not limited to, circular, square, oval, rectangular, or any other suitable shape based on the design and desired airflow considerations. Accordingly, the movable piston 200, as well as other components of the movable piston 200, may be sized and shaped to match the size and cross-sectional shape of the protrusion.

[0016] The second tool 310 includes a body 312 defining a cavity 314 corresponding to the projections 324. The cavity 314 of the second tool houses the movable piston 200 and, in the engaged position, receives the piston 200 after it has contacted the upper end of the projection 324 and moved vertically upward into the cavity 314, thereby sealing the cavity 314 and forming a flush contact between the projection 324 and the movable piston 200, so that the foam can flow around the projection 324 to form a hole in the foam body 400 from top to bottom. Even if in the Fig. 3A-C, only one cavity 314 is shown, the cavities 314 correspond to the number and / or pattern of the corresponding projection 324. Furthermore, the opening of the cavity 314 in the second tool can be dimensioned according to the cross-sectional shape and size of the movable piston 200 to accommodate the movable piston 200.

[0017] As in Fig. 3A, the projection 324 of the first tool 320 has an upper end for engagement with a piston 210 of the movable piston 200. In the engaged position, as shown in Fig. 3B, the movable piston 200 is contacted by the projection 324 of the first tool 320 and displaced upward into a cavity 314 of the second tool 310. In the disengaged position, as shown in Fig. 3A (before forming the foam body 400) and Fig. 3C (after forming the foam body 400), the movable piston 200 is lowered downward by a distance above the height of the second tool 310 (defined, for example, by the difference between the decompressed spring height H1 and the compressed height H2), with the lower surface of the movable piston 200 extending above a lower surface of the body 312 of the second tool 310 and removing the foam and / or film layer at the top of the hole 420 (i.e., ridge) formed in the foam body 400.

[0018] Referring again to Fig. 3A, the cavity 314 in the second tool 310 includes a lower portion 315 of the cavity 314 sized and shaped to correspond with and receive a piston 210 of the movable piston 200, and an upper portion 316 sized to receive a shaft body 230 of the movable piston 200. As explained below, the piston is sized based on engagement with the projection 324 such that contact between the piston 210 and the projection 324 forms a flush seal to define the hole in the molded foam body 400. The piston 210 is positioned such that a portion is within the cavity 314 in both the engaged and disengaged positions, and a portion extends beyond the bottom surface of the body 312 of the second tool 310 in the disengaged position.

[0019] As in Fig. 2, the movable piston 200 includes the piston 210 and the shaft body 230. The piston 210 is sized such that an engagement surface 212 of the piston 210 is substantially the same size as the upper end of the projection 324 and forms a flush edge when the assembly is in the engaged position (as shown in Fig. 3B) so that the movable piston 200 can eliminate the burr and a thin film by fitting the piston 210 into the opening of the hole 420. The interface between the piston 210 and the projection 324 can be a flat surface or a surface of corresponding shape that mate as male-female parts to seal the tool and prevent foam from leaking over the projection 324. The piston 210 can be made of any suitable material with low adhesion to the foam, thus acting as an anti-stick surface in the mold assembly. The material is also suitable for sealing the piston 210 against a projection 324 when the mold closes, with sufficient mechanical strength to prevent deformation of the piston 210 within the temperature range of the foam. A suitable material for the piston 210 includes, but is not limited to, polytetrafluoroethylene (PTFE).Furthermore, the piston 210, as shown in . Fig. 2 and Fig. 3A-C, has a radius that is larger than the radius of the shaft body 230, so that the piston 210 extends radially further outward than the shaft body 230. The piston 210 forms a barrier to foam flowing into the cavity 314 in the second tool 310 (as shown in Fig. 3A-C).

[0020] With further reference to Fig. 2 and Fig. 3A-C, the shaft body 230 is sized to correspond to the upper portion 316 of the cavity 314, which is sized to prevent the piston 210 from sliding into the upper portion 316 of the cavity and out of the top of the second tool 310. As in the embodiment of Fig. 3A-C, the shaft body 230 may also include an optional stop 232 at an upper end outside the cavity 314. The stop 232 may be connected to the shaft body 230 and contact an outer surface of the body 312 of the second tool 310 when in the disengaged position to limit the vertical movement of the movable piston 200. The stop 232 may be a retaining ring or other suitable feature to limit the lowering of the shaft body 230 into the cavity 314 in the disengaged position, and the position of the stop 232 is not intended to be limiting and is shown as an example of how vertical movement may be limited.

[0021] In one or more embodiments, which in turn relate to Fig. 2, the movable piston 200 includes the piston 210, which includes the connector 220. Although the piston 210 and the shaft body 230 are illustrated as separate features connected by the connector 220, in certain embodiments (not shown), the piston 210 and the shaft body 230 could be formed as a single body that is movable by the actuator. The connector 220 may be any suitable device for connecting the piston 210 to the shaft body 230, such as, but not limited to, a cylinder head screw (as shown in Fig. 2). Although the connector 220 in Fig. 2 as a separate feature, the connector 220 can be integrated into the piston 210 and / or the shaft body 230 or omitted so that the piston 210 and the shaft body 230 are directly attached. As shown in Fig. 2, the upper end of the connector 220 is housed in the shaft body 230, which has a cavity 260 defined by the shaft body 230 for receiving the upper end of the connector 220. The base of the shaft body 230 is connected to the piston 210, so that the connector 220 extends from the piston 210 into the cavity 260 of the shaft body 230. In the Fig. 2, the piston 210 forms a contact surface around the lower portion of the connector 220 for engagement with the projection 324.

[0022] Again referring to Fig. 2, in certain embodiments, the movable piston 200 includes a spring 250 as an actuator for moving the movable piston 200 from the engaged position and the released position. The spring 250 is, as in the embodiment of Fig. 2, is dimensioned to fit around the shaft body 230 and rest on and contact the piston 210 (due to the larger radius of the piston 210). Although the spring 250 in Fig. 2 around the shaft body 230, in other embodiments where the actuator is a spring, the spring may be positioned in any suitable manner so that it compresses and decompresses with the movement of the movable piston 200 during closing and opening of the mold. In certain other embodiments (not shown), the spring may, for example, be disposed above the shaft body 230 in the cavity 314. Each movable piston (corresponding to each projection in the first tool 320) may individually include an actuating spring 250 for moving the movable piston 200.As shown in the figures, the spring 250 is not fixedly connected to the shaft body 230 or the piston 210, but is movably arranged over the shaft assembly so that it can be compressed by the force on the connector 220, resulting in movement of the shaft assembly 200, although one or both ends of the spring 250 may be attached to the movable piston 200 and / or the second tool 310.

[0023] In embodiments where the actuator is a spring 250, the spring 250 may be configured to have a stroke (i.e., a difference in length between the compressed and decompressed states) based on the body 312 and the dimensions of the second tool 310 and the cavity 314 for the movable piston 200. The stroke may be selected based on the height of the second tool 310 and the length of the movable piston 200 such that the spring 250 can move the movable piston 200 to the disengaged position upon opening the tool and compress sufficiently to store enough energy so that the burr can be removed and the cavity 314 can be sealed while the assembly is in the engaged state.In certain embodiments, the stroke of the spring may be about 2 to 10 mm, in other embodiments, the stroke may be about 3 to 8 mm, and in still other embodiments, the stroke may be 4 to 6 mm. In one or more embodiments, the spring force of the spring 250 is sufficient to overcome the frictional forces between the movable piston 200 and the walls of the body 312 defining the cavity 314 to move the movable piston 200 into the hole 420 when the tool is opened and remove burr, yet is resilient enough to allow the piston to compress the spring when the tool is closed by the force of the protrusion. In at least one embodiment, the spring has a force of about 25 to 55 N, in other embodiments, a force of about 30 to 50 N, and in another embodiment, about 35 to 45 N.Furthermore, the spring rate may be any suitable rate for moving the plunger 200 to remove the burr or thin film from the hole, such as, but not limited to, at least about 5 N / mm. In certain embodiments, the spring rate is about 5 N / mm to 50 N / mm, in other embodiments, the spring rate is about 5 N / mm to 35 N / mm, and in yet another embodiment, the spring rate is about 5 N / mm to 25 N / mm.

[0024] With further reference to Fig. 2 and Fig. 3A-C, in one or more embodiments, the piston 210 further includes a rib portion 240 along at least a portion of the outer circumference of the piston 210. In certain embodiments, the rib portion 240 extends along the entire circumference of the piston 210. The rib portion 240 further provides a barrier to foam ingress into the cavity 314 of the second mold 310 when the assembly is closed by contacting the inner wall of the body 312 defining the cavity 314, thereby preventing foam from leaking over the top of the boss and around the piston 210 toward the shaft assembly 230. The rib portion 240 also scrapes the cavity 314 and removes burrs and foam from the edges as the shaft assembly 200 moves between the engaged position and the disengaged position through its contact with the walls of the cavity 314.The rib portion 240 is made of any suitable material, such as, but not limited to, PTFE, polyvinyl fluoride (PVF), or polyoxymethylene (POM), such that the rib portion 240 has sufficient mechanical strength to scrape the foam from the cavity within the operating temperature range of the mold assembly, and has low adhesion to the foam such that it acts as a non-stick surface in the mold assembly when the piston 210 tears away the film formed over the hole in the foam pad, as described in detail below and in the . Fig. 3A-C shown.

[0025] When the mold assembly 300 is closed and in the engaged position, the interface between the second tool 310 and the first tool 320 is sealed via the movable piston 200, which contacts the projection 324 (via the piston 210) to seal the cavity 314, along with the rib portion 240, which provides additional sealing for the cavity 314. Thus, the cavity 314 can be sized and shaped to receive the movable piston 200 by an interference fit with appropriate friction, so that the movable piston 200 is movable by the actuator along a vertical axis of the second tool and can provide sealing (during molding) and flash removal (during disengagement) at the through hole in the foam body 400.The projection 324 engages the piston 210, causing the shaft assembly 200 to move upward into the cavity 314 and compress the spring assembly 250 to have a height H2. Thus, contact between the projection 324 and the piston 210 compresses the spring 250 in the engaged position, sealing the interface between the first and second tools 320, 310 at the contact point between the projection 324 and the piston 210 to prevent foam from leaking beyond the projection 324. In this engaged position, as shown in FIG. Fig. 3B, the piston 210 is displaced upwards into the cavity 314 by the height difference between H1 and H2, by the displacement of the spring 250. Although in Fig. 3B, the piston 210 is substantially aligned with the underside of the body 312 of the second tool 310, in other arrangements (not shown) the engagement position may have the piston 210 either vertically above or vertically below the underside of the body 312 and would still seal the mold assembly via contact with the projection 324.

[0026] During molding of the foam body 400, when the spring 250 is compressed, the bottom of the piston 210 is displaced upward along a vertical axis of the assembly 300 by the height difference between H1 and H2, so that the bottom of the piston 210 may be aligned with the bottom surface of the body 312 of the second tool 310 where the projection 324 contacts the piston 210, or in some embodiments (based on the spring force and the design), the bottom of the piston 210 may still extend beyond the bottom surface of the second tool body 312 due to the displacement caused by the compressed spring and form the seal by direct contact with the projection 324.In this way, the foam body 400 can be molded around the projection 324 and form a hole without leakage through the barrier formed by the movable piston 200 at the opening of the cavity 314 forming a film over the hole.

[0027] As in Fig.As shown in Figure 3C, the mold assembly 300 is opened so that the second die 310 and the first die 320 are separated, and the foam body 400 with the hole 420 is formed. Upon opening the die assembly 300, the spring 250 is pushed back to the height H1 due to the release of the engagement between the shaft assembly 200 and the projection 324. Thus, the movable piston 200 moves back down from the cavity 314, and the piston 210 extends above the surface of the second die body 312, removing the burr at the edges of the opening of the hole 420 or any film that may have formed over the top of the hole 420. As the piston 210 descends, the rib portion 240 also clears the edges of the cavity 314 so that the foam does not migrate into the cavity 314 of the second tool 310.The rib portion 240 can clear the cavity regardless of whether the piston is substantially aligned with the bottom surface of the body 312 in the engaged state, vertically above the bottom surface, or vertically below the bottom surface, based on the movement of the shaft assembly 200 along the vertical axis and the positioning of the rib portion 240. In this way, the foam body 400 with the hole 420 is formed without additional post-processing because the movable piston 200 is able to prevent leakage and a significant flash.

[0028] According to a further embodiment, a method for forming a foam body with through-holes is provided. A first tool and a second tool are provided which cooperate to form the forming tool assembly for forming the foam body. The first tool has at least one projection forming a corresponding hole in the foam body. The projection has a surface with at least one perimeter at an upper end for engaging at least a portion of a shaft assembly. The second tool has a corresponding cavity for each of the projections of the first tool. The cavity has an opening defined in the surface of the second tool. The cavity further includes the movable piston disposed therein.The method also includes closing the mold assembly so that the projection engages the shaft assembly and the cavity is sealed, and forming a foam body with holes formed therein. The shaft assembly includes a piston engaging at least the periphery of the projection to push the shaft assembly so that a spring of the shaft assembly is compressed and the shaft assembly moves upwardly into the cavity. The engagement of at least the periphery and the shaft assembly forms a flush edge to form the hole in the foam body. The method further includes opening the mold assembly to separate the first and second tools so that the spring is decompressed and the shaft assembly moves downwardly into the hole to remove any flash or thin layers formed during the molding step. List of reference symbols: 100, 300 mold arrangement 120, 320 first tool 110, 310 second tool 330 cavity 122, 322 base element 124, 324 lead 122 bodies 114, 314 Cavity of the second tool 200 movable piston 210 pistons 250 spring 12 Body of the second tool 400 foam bodies 420 holes 315 lower section of the cavity 16 upper section of the cavity 230 shaft bodies 212 Intervention area 232 stop 220 connectors 260 Cavity of the shaft body 240 rib section

Claims

[1] Molding tool assembly (300) comprising: a first tool (320) having at least one projection (324) for creating at least one hole (420) in a foam body (400); a second tool (310) configured to cooperate with the first tool (320) to define at least one foam body cavity (330) for forming the foam body (400), the second tool (310) defining a cavity (314) having a cross-section corresponding to a cross-section of the projection (324); at least one movable piston (200) for burr removal, corresponding to and at least partially disposed within the cavity (314) in the second tool (310), and movable between a released position when the first (320) and second tools (310) are separated and an engaged position when the first (320) and second tools (310) are closed; and an actuator configured to move the movable piston (200) between the engaged position and the released position, wherein in the engaged position, the movable piston (200) contacts the projection (324) to seal the cavity (314), and in the released position, at least a portion of the movable piston (200) extends below a bottom surface of the second tool (310) into the hole (420) of the foam body (400). [2] The mold assembly of claim 1, wherein the actuator has a preload in the engaged position such that in the engaged position the projection (324) urges the movable piston (200) against the preload. [3] The mold assembly of claim 2, wherein the actuator is a spring (250) and the movable piston (200) is displaced between the engaged position and the released position based on the compression and decompression of the spring (250). [4] The mold assembly of claim 3, wherein the spring (250) is disposed around a shaft body (230) of the movable piston (200) within the cavity (314) to compress and decompress based on the movement of the movable piston (200). [5] The mold assembly of claim 3, wherein the spring (250) has a spring rate of at least 5 N / mm. [6] The mold assembly of claim 1, wherein the movable piston (200) includes a rib portion (240) around at least a portion of a circumference of the movable piston (200), the rib portion (240) providing a barrier against foam ingress into the cavity (314) of the second mold (310) when the mold assembly (300) is closed. [7] The mold assembly of claim 6, wherein the rib portion (240) contacts an inner wall of the second tool (310) defining the cavity (314) and removes foam from the cavity (314) as the movable piston (200) moves between the engaged position and the released position. [8] The mold assembly of claim 1, wherein the actuator is a hydraulic actuator for pushing the movable piston (200) into the released position. [9] Molding tool assembly (300) comprising: a first tool (320) having at least one projection (324) for creating at least one hole (420) in a foam body (400); a second tool (310) configured to cooperate with the first tool (320) to define at least one foam body cavity (330) for forming the foam body (400), the second tool defining a cavity (314) having a cross-section corresponding to a cross-section of the projection (324); and at least one movable piston (200) for burr removal corresponding to and at least partially disposed within the cavity (314) in the second tool (310) and movable between a released position when the first (320) and second tools (310) are separated and an engaged position when the first (320) and second tools (310) are closed, the movable piston (200) having a bias towards the released position; an actuator configured to move the movable piston (200) from the engaged position and to the released position; wherein in the engaged position, the movable piston (200) contacts the projection (324) to seal the cavity (314), and in the released position, the preload displaces the movable piston (200) such that at least a portion of the movable piston (200) extends below a bottom surface of the second tool (310) into the hole (420), wherein the first tool (320) comprises a plurality of projections (324) and the second tool (310) comprises a plurality of cavities (314) corresponding to the plurality of projections (324), wherein the mold assembly (300) comprises a plurality of movable pistons (200) with a respective movable piston (200) for each of the plurality of projections (324). [10] The mold assembly of claim 9, further comprising an actuator cooperating with the movable piston (200) to bias the movable piston (200) to the released position, the actuator being a spring (250) having a spring constant of at least 5 N / mm. [11] The mold assembly of claim 9, wherein the projection (324) has a diameter of 5 to 35 mm. [12] The mold assembly of claim 9, wherein in the engagement position, a bottom of the movable piston (200) is aligned with the bottom surface. [13] The mold assembly of claim 9, wherein the movable piston (200) includes a rib portion (240) around at least a portion of a circumference of the movable piston (200), the rib portion (240) contacting an inner wall of the second tool (310) defining the cavity (314) and removing foam from the cavity (314) as the movable piston (200) moves between the engaged position and the released position. [14] A method for forming a foam body (400) with holes (420), comprising: Providing a first tool (320) having a projection (324) and a second tool (310) having a cavity (314) corresponding to the projection (324), wherein a cross-section of the cavity (314) corresponds to a cross-section of the projection (324), wherein the first (320) and the second tool (310) cooperate to define at least one foam body cavity (330) to form a mold assembly (300); Positioning at least one movable piston (200) at least partially within the cavity (314); Closing the mold assembly (300) so that the movable piston (200) engages the projection (324) to seal the cavity (314); Forming a foam body (400), wherein the projection (324) forms a hole (420); and Opening the mold assembly (300) so that the movable piston (200) is released, wherein the closing of the mold assembly (300) pushes the movable piston (200) at least partially into the cavity (314) upon engagement with the projection (324), wherein, upon opening of the mold assembly (300), the movable piston (200) is positioned at least partially beneath a bottom surface of the second tool (310) by an actuator.

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