Apparatus and method for manufacturing molded foam product

Abstract

To provide an apparatus for manufacturing a foamed molded product capable of achieving a high expansion ratio.SOLUTION: An apparatus for manufacturing a foam molded product includes a fixed mold, a first movable mold, and a second movable mold, the apparatus being configured to manufacture a foam molded product having a bottom surface and a standing wall structure around the bottom surface, the apparatus including a cavity corresponding to the foam molded product including a bottom-surface cavity corresponding to the bottom surface and a standing-wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold when the mold is clamped, the second movable mold being capable of core-backing so as to expand the bottom-surface cavity, and injecting a foaming resin in which a foaming resin and a high-pressure gas are mixed into the cavity, the injection molding machine includes a foam resin injection unit capable of filling the cavity with a foam resin, a core-back drive unit that core-backs the second movable mold and further foams the foam resin filled in the bottom surface cavity to form a foam molded article, and a mold drive unit that performs mold clamping and mold opening of the fixed mold, the first movable mold, and the second movable mold.SELECTED DRAWING: FIG. 1-C

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus for manufacturing a foam-molded product with a high expansion ratio and a method for manufacturing a foam-molded product. [Background technology]

[0002] In recent years, there has been an increasing need for lighter, stronger, and lower cost parts in the fields of home appliances, automotive interiors, etc. Among these, foam molded products are being actively adopted in various fields to meet the demand for lighter weight, higher strength, and lower cost.

[0003] 8 is a cross-sectional view showing a configuration in which double-sided tape 21 is attached to a vehicle body 20 to form an automotive member 10 in accordance with Patent Document 1. According to the configuration described in Patent Document 1, grooves 14 recessed inward from the vehicle body side surface are formed in a position near the end of at least a portion of terminal peripheral region 13 of outer peripheral edge 12 so as to roughly follow outer peripheral edge 12, and a surface 15n of the terminal peripheral region on the vehicle body side outside groove 14 of terminal peripheral region 13 and a surface 15m of the terminal peripheral region on the vehicle body side inside groove 14 of terminal peripheral region 13 are formed to be roughly flush with each other, and terminal 16 of terminal peripheral region 13 is formed in a roughly arc shape from outer surface 17 to outer peripheral edge 12 at the tip of surface 15n on the vehicle body side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-006527 Summary of the Invention [Problem to be solved by the invention]

[0005] In this conventional example, double-sided tape 21 is applied to a vehicle body 20, and an automotive component 10 is formed on top of the tape. However, because groove 14 is formed between surface 15n of the terminal peripheral region and surface 15m of the terminal peripheral region so as to roughly follow outer periphery 12, high expansion ratio molding (2x or more) is not possible, and the presence of groove 14 reduces the thickness and strength.

[0006] The present disclosure is intended to solve the above-mentioned problems, and has an object to provide an apparatus for manufacturing foam-molded products that can achieve a high expansion ratio. [Means for solving the problem]

[0007] The foam-molded product manufacturing apparatus according to the present disclosure is an apparatus for manufacturing foam-molded products that produces foam-molded products having a bottom surface and a standing wall structure surrounding the bottom surface, the apparatus comprising a mold comprising a fixed mold, a first movable mold, and a second movable mold, and when the mold is clamped, a cavity corresponding to the foam-molded product is formed, including a bottom cavity corresponding to the bottom surface between the fixed mold, the first movable mold, and the second movable mold, and a standing wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold, the second movable mold being capable of being cored back to expand the bottom cavity, a foaming resin injection unit that can inject a foaming resin that is a mixture of molding resin and high-pressure gas into the cavity to fill the cavity with the foaming resin, a core-back drive unit that cores back the second movable mold to further foam the foaming resin filled in the bottom cavity to produce the foam-molded product, and a mold drive unit that clamps and opens the fixed mold, the first movable mold, and the second movable mold.

[0008] The method for manufacturing a foam-molded product according to the present disclosure is a method for manufacturing a foam-molded product that produces a foam-molded product having a bottom surface and a standing wall structure surrounding the bottom surface, and includes a mold clamping process in which a fixed mold, a first movable mold, and a second movable mold are clamped together to form a cavity corresponding to the foam-molded product, including a bottom cavity corresponding to the bottom surface between the fixed mold, the first movable mold, and the second movable mold, and a standing wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold; an injection process in which a foaming resin that is a mixture of molding resin and high-pressure gas is injected into the cavity to fill the cavity with the foaming resin; a core-back process in which the second movable mold is cored back to further foam the foaming resin filled in the bottom cavity to produce a foam-molded product; and a mold-opening process in which the fixed mold, the first movable mold, and the second movable mold are opened to remove the foam-molded product.

[0009] The foam-molded product according to the present disclosure has a bottom surface and a standing wall structure surrounding the bottom surface, with the bottom surface and the standing wall structure defining a recess, and the bottom surface has a lower density than the standing wall structure. [Effects of the Invention]

[0010] The manufacturing device for foam-molded products according to the present disclosure can follow the shape of the mold, enabling high expansion ratio molding (2x or more). [Brief explanation of the drawings]

[0011] [Figure 1-A] 3 is a schematic cross-sectional view showing a state in which a fixed mold, a first movable mold, and a second movable mold are clamped together in the method for producing an expansion-molded article according to the first embodiment. FIG. [Figure 1-B] 3 is a schematic cross-sectional view showing a state in which a foaming resin is injected into a cavity after mold clamping in the method for producing a foam-molded product according to the first embodiment. FIG. [Figure 1-C] 4 is a schematic cross-sectional view showing a state in which the second movable die is cored back while maintaining the outer peripheral wall surface around the bottom surface of the molded article in the method for producing an expansion-molded article according to the first embodiment. FIG. [Figure 1-D] 4 is a schematic cross-sectional view showing a state in which the core back of the second movable mold has been completed in the method for producing an expansion-molded product according to the first embodiment. FIG. [Figure 1-E] 1 is a schematic cross-sectional view showing a state in which a mold opening operation is being performed in the method for producing an expansion-molded article according to the first embodiment. FIG. [Figure 1-F] 4 is a schematic cross-sectional view showing the mold closing operation of the fixed mold, the first movable mold, and the second movable mold in the method for producing a foam-molded article according to the first embodiment. FIG. [Figure 2] 3 is a timing chart of the method for producing an expansion-molded product according to the first embodiment. [Figure 3-1] 1 is a schematic cross-sectional view showing a state in which H&C (heat and cool) is arranged in a fixed mold and a first movable mold in the foam-molded product manufacturing apparatus according to the first embodiment. [Figure 3-2]1 is a schematic cross-sectional view showing a state in which H&C (heat and cool) units are arranged in a fixed mold, a first movable mold, and a second movable mold in the foam-molded product manufacturing apparatus according to the first embodiment. [Figure 3-3] FIG. 10 is a schematic cross-sectional view showing a plurality of second movable parts capable of core-back. [Figure 4] 1 is a schematic cross-sectional view showing the vertical wall thickness W and the average thickness t and height H of the bottom surface before the core back in an expansion-molded product. [Figure 5-A] FIG. 10 is a schematic cross-sectional view showing the state of a corner when the corner on the fixed mold (core) side before the core back and the corner on the second movable mold (cavity mold) side are both right angles. [Figure 5-B] FIG. 5B is a schematic cross-sectional view showing the state of the corner portion of FIG. 5A after core back. [Figure 5-C] FIG. 10 is a schematic cross-sectional view showing a state in which an R-shape is provided at a corner portion in front of a core back. [Figure 5-D] FIG. 5B is a schematic cross-sectional view showing the state of the corner portion of FIG. 5C after core back. [Figure 5-E] FIG. 10 is a schematic cross-sectional view showing a state in which a C-surface is provided at a corner portion in front of a core back. [Figure 5-F] FIG. 5B is a schematic cross-sectional view showing the state of the corner portion of FIG. 5E after core back. [Figure 6] 1A and 1B are schematic diagrams showing a cycle of physical foam molding in the first embodiment and an operation of releasing the clamping force before core back. [Figure 7A] 1 is a table showing the time required to release the mold clamping force and the core-back transition time required for a mold opening amount of 2 mm in the method for producing an expansion-molded product according to the first embodiment. [Figure 7B] 4 is a diagram showing the relationship between the core-back transition time, including the time required to release the mold clamping force, and the mold opening amount in the method for manufacturing an expansion-molded article according to the first embodiment. FIG. [Figure 8] FIG. 1 is a cross-sectional view showing a cross-sectional configuration of an automobile member disclosed in Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] The foam-molded product manufacturing apparatus of the first aspect is an apparatus for manufacturing foam-molded products that produces foam-molded products having a bottom surface and a vertical wall structure surrounding the bottom surface, and is a mold comprising a fixed mold, a first movable mold, and a second movable mold. When the mold is clamped, a cavity corresponding to the foam-molded product is formed, including a bottom cavity corresponding to the bottom surface between the fixed mold, the first movable mold, and the second movable mold, and a vertical wall cavity corresponding to the vertical wall structure between the first movable mold and the second movable mold. The second movable mold is a mold that can be cored back to expand the bottom cavity; a foaming resin injection unit that can inject a foaming resin mixed with molding resin and high-pressure gas into the cavity to fill the cavity with the foaming resin; a core-back drive unit that cores back the second movable mold to further foam the foaming resin filled in the bottom cavity to produce the foam-molded product; and a mold drive unit that clamps and opens the fixed mold, the first movable mold, and the second movable mold.

[0013] The second aspect of the manufacturing apparatus for foam-molded products is the same as the first aspect, in that the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold may have a larger radius of curvature on the inner side formed between the fixed mold and the second movable mold than on the outer side formed between the fixed mold and the first movable mold.

[0014] The third aspect of the manufacturing apparatus for foam-molded products is the same as the first aspect, in which the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a chamfered C-surface on the outer surface side formed between the fixed mold and the first movable mold and on the inner surface side formed between the fixed mold and the second movable mold, and the amount of chamfering of the C-surface on the inner surface side may be greater than the amount of chamfering of the C-surface on the outer surface side.

[0015] A fourth aspect of the apparatus for producing a foam-molded product is any one of the first to third aspects, wherein the average wall thickness t of the bottom cavity is 0.5t to 1.5t, where t is the wall thickness W of the upright wall cavity.

[0016] A fifth aspect of the apparatus for producing a foam-molded product is the apparatus of any one of the first to fourth aspects, wherein the second movable mold may have a plurality of second movable molds that are capable of independently core-backing.

[0017] The method for manufacturing a foam-molded product according to the sixth aspect is a method for manufacturing a foam-molded product that produces a foam-molded product having a bottom surface and a standing wall structure surrounding the bottom surface, and includes a mold clamping process in which a fixed mold, a first movable mold, and a second movable mold are clamped together to form a cavity corresponding to the foam-molded product, including a bottom cavity corresponding to the bottom surface between the fixed mold, the first movable mold, and the second movable mold, and a standing wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold; an injection process in which a foaming resin that is a mixture of molding resin and high-pressure gas is injected into the cavity to fill the cavity with the foaming resin; a core-back process in which the second movable mold is cored back to further foam the foaming resin filled in the bottom cavity to produce a foam-molded product; and a mold-opening process in which the fixed mold, the first movable mold, and the second movable mold are opened to remove the foam-molded product.

[0018] The seventh aspect of the method for producing a foam-molded product is the same as the sixth aspect, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold may have a larger radius of curvature on the inner side formed between the fixed mold and the second movable mold than on the outer side formed between the fixed mold and the first movable mold.

[0019] The eighth aspect of the method for producing a foam-molded product is the same as the sixth aspect, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a chamfered C-surface on the outer surface side formed between the fixed mold and the first movable mold and on the inner surface side formed between the fixed mold and the second movable mold, and the amount of chamfering of the C-surface on the inner surface side may be greater than the amount of chamfering of the C-surface on the outer surface side.

[0020] The method for producing an expansion-molded product according to a ninth aspect is any one of the sixth to eighth aspects, wherein the thickness W of the upright wall cavity relative to the average thickness t of the bottom cavity in the mold clamping step before the core-back step may be 0.5t to 1.5t.

[0021] A tenth aspect of the method for producing an expansion-molded article is the method of any one of the sixth to ninth aspects, wherein the second movable mold may have a plurality of second movable molds that are capable of independently core-backing.

[0022] The foam-molded article according to an eleventh aspect has a bottom surface and a standing wall structure surrounding the bottom surface, the bottom surface and the standing wall structure forming a recess, and the bottom surface has a lower density than the standing wall structure.

[0023] A foam-molded article according to a twelfth aspect is the foam-molded article according to the eleventh aspect, wherein the density of the bottom surface may be half or less than that of the standing wall structure.

[0024] Hereinafter, a manufacturing apparatus for a foam-molded product, a manufacturing method thereof, and a foam-molded product according to embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0025] (Embodiment 1) <Foam molding manufacturing equipment> 1A to 1F are schematic cross-sectional views showing the operation of an apparatus 200 for producing foam-molded products. The foam-molded product manufacturing apparatus 200 according to the first embodiment includes a fixed mold 201, a first movable mold 202, a second movable mold 203, an H&C (heat and cool) 204, and a hydraulic cylinder 205. The fixed mold 201, the first movable mold 202, and the second movable mold 203 constitute a mold. A mold driver closes and opens the fixed mold 201, the first movable mold 202, and the second movable mold 203. When the mold is closed, a cavity 220 corresponding to the foam-molded product is formed between the fixed mold 201, the first movable mold 202, and the second movable mold 203. The cavity 220 includes a bottom cavity 216 corresponding to the bottom surface and a standing-wall cavity 218 corresponding to the standing-wall structure. The second movable mold 203 can be cored back to enlarge the bottom cavity 216. The mold also has a foam resin injection unit (not shown) that injects foam resin, which is a mixture of molding resin and high-pressure gas, into the cavity 220. The foam resin injection unit fills the cavity with foam resin. The core-back driving unit cores back the second movable mold 203, further foaming the foam resin filled in the bottom cavity 216 to produce a foam molded product.

[0026] <About the corner C before the core back> Fig. 5-A is a schematic cross-sectional view showing the state of corner C when the corner on the fixed mold (cavity mold) 201 side before core back and the corner on the second movable mold (core mold) 203 side are both right angles. Fig. 5-B is a schematic cross-sectional view showing the state of corner C in Fig. 5-A after core back. As shown in Fig. 5-A, on the interface between the foamed resin 206 and the mold, a core-side skin layer 212 is formed on the side of the second movable mold (core mold) 203, and a cavity-side skin layer 213 is formed on the side of the fixed mold (cavity mold) 201. Due to the core back of the second movable mold 203, the foamed resin in the bottom cavity further foams. In this case, since the foamed resin 206 foams inside the core-side skin layer 212, as shown in Fig. 5-B, when the core backs, the higher the foaming magnification (2 times or more) of the core-side skin layer 212 becomes, the more the skin layer extends and becomes excessive. The inventor has found that when the core-side corner is right-angled before the core back, a groove 214 is formed by the excess part of the core-side skin 212, and foaming does not occur sufficiently, resulting in thin-wall parts and possibly causing a decrease in strength.

[0027] Fig. 5-C is a schematic cross-sectional view showing the state where an R shape is provided at the corner before the core back. Fig. 5-D is a schematic cross-sectional view showing the state of the corner after the core back for the corner in Fig. 5-C. Specifically, in Fig. 5-C, a cavity-side corner R208 and a core-side corner R209 are provided at the corner. Also, the radius of curvature R2 of the core-side corner R209 is made larger than the radius of curvature R1 of the cavity-side corner R208 (R1 < R2). The inventor has found that by making the core-side corner not right-angled but curved, shortening the line length of the core-side skin layer compared to the case of a right angle, and making the radius of curvature larger than that of the cavity-side corner, the above problems can be solved, leading to the present disclosure. As a result, when the foamed resin further foams during the core back, the sag of the core-side skin layer 212 can be absorbed. As a result, after the core back, the corner shape is as shown in Fig. 5-D.

[0028] Fig. 5-E is a schematic cross-sectional view showing the state where a C surface is provided at the corner before the core back. Fig. 5-F is a schematic cross-sectional view showing the state of the corner after the core back for the corner in Fig. 5-E. As shown in Figure 5-E, by making the core-side corner of the corner part a C-face shape instead of a right angle, it is possible to further shorten the line length of the core-side skin layer 212 compared to Figure 5-C. Also, after the core is backed up, slack in the core-side skin layer 212 can be absorbed when the foaming resin is further foamed during core backing. As a result, the corner shape is as shown in Figure 5-F.

[0029] As described above, the bottom cavity formed between the fixed mold 201, the first movable mold 202, and the second movable mold 203 may have a larger radius of curvature on the inner side formed between the fixed mold 201 and the second movable mold 203 than the radius of curvature on the outer side formed between the fixed mold 201 and the first movable mold 202. The inner surface side (core side corner) formed between the fixed mold 201 and the second movable mold 203 and / or the outer surface side (cavity side corner) formed between the fixed mold 201 and the first movable mold 202 are not limited to curved surfaces as shown in Fig. 5-C, but may also be chamfered C-faces as shown in Fig. 5-E. When the outer surface side formed between the fixed mold 201 and the first movable mold 202 and the inner surface side formed between the fixed mold 201 and the second movable mold 203 are each chamfered C-faces, the amount of chamfering of the C-face on the inner surface side may be greater than the amount of chamfering of the C-face on the outer surface side. Furthermore, if the inner surface (core side corner) and outer surface (cavity side corner) have a mixture of curved and C-shaped surfaces, the curved surfaces can also be converted into "C-shaped chamfer amount" and compared using the C-shaped chamfer amount.

[0030] The wall thickness W of the vertical wall cavity 218 may be 0.5t to 1.5t relative to the average wall thickness t of the bottom cavity 216. As shown in Figure 4, it is recommended to set W in the range of 0.5t to 1.5t relative to the average wall thickness t before core back. If W is less than 0.5t, the vertical wall will deform during core back, and if the vertical wall thickness W is more than 1.5t, the vertical wall will be too thick, causing sink marks on the exterior surface. The height H should be set so that H ≥ average wall thickness × expansion ratio or greater.

[0031] <Second moving part> FIG. 3-3 is a schematic cross-sectional view showing a case where a plurality of second movable dies 203 (partial core-backs) capable of performing core-back independently are provided. By core-backing the second movable part 203, the foaming resin filled in the bottom cavity 216 can be further foamed inside the core-side skin layer 212, resulting in high-expansion foaming. In this case, the wall surface of the standing wall around the bottom surface can be maintained. The second movable mold 203 may have a plurality of second movable molds that can be independently cored back. The plurality of second movable parts 203 can be used when it is desired to change the foaming ratio depending on the location.

[0032] <H&C(ヒート&クール)> The H&C 204 indicates a state in which the mold surface temperature has reached the maximum set temperature. The H&C 204 may be located only on the fixed mold 201, as shown in FIG. 1-A. Alternatively, the H&C 204 may be located on both the fixed mold 201 and the first movable mold 202, as shown in FIG. 3-1. Alternatively, the H&C 204 may be located on the fixed mold 201, the first movable mold 202, and the second movable mold 203, as shown in FIG. 3-2. The H&C 204 can be used according to the application. The upper temperature limit (Heat temperature setting) of the H&C 204 can be set to exceed the Tg point (glass transition temperature) of the material physical properties published by the molding resin manufacturer. The lower temperature limit (Cool temperature setting) can be set to the maximum recommended mold temperature published by the molding resin manufacturer. Setting the temperature below the maximum recommended mold temperature lengthens the heat cycle time, reducing mass productivity. Setting the temperature above the maximum recommended mold temperature results in core back without forming a skin layer, making the foam-molded product 207 more susceptible to deformation. At this time, the hydraulic cylinder 205 is kept in the OFF state. By using H&C204, it is possible to control the temperature all the way to the edges, eliminate temperature unevenness, control the internal pressure to increase, and partially core back the foamed resin while keeping the surface skin layer soft, allowing it to conform to the edge shape.

[0033] <Method of manufacturing foam molded products> 1A to 1F are schematic cross-sectional views showing the steps of the method for producing a foam-molded product. Fig. 2 is a timing chart of the operations (operation of the mold 200, injection, core-back), H&C (heat & cool) 204, and hydraulic cylinder 205 of the foam-molded product production apparatus shown in Figs. 1A to 1F. The manufacturing method of the foam-molded product according to the first embodiment is carried out in the following sequence: (1) clamping the mold (FIG. 1-A), (2) injecting the foaming resin (FIG. 1-B), (3) opening the core back of the second movable mold (FIG. 1-C, FIG. 1-D), (4) opening the mold (FIG. 1-E), (5) removing the foam-molded product (FIG. 1-F), and (6) clamping the mold. The foam-molded product 207 is a foam-molded product in which the foamed portion is surrounded by a skin layer.

[0034] (1) Fig. 1-A is a schematic cross-sectional view showing a state in which a fixed mold 201, a first movable mold 202, and a second movable mold 203 are clamped together in the method for producing a foam-molded product according to the first embodiment. The cavity defined between the fixed mold 201, the first movable mold 202, and the second movable mold 203 includes a bottom cavity 216 corresponding to the bottom between the fixed mold 201, the first movable mold 202, and the second movable mold 203, and a standing-wall cavity 218 corresponding to the standing-wall structure between the first movable mold 202 and the second movable mold 203. The thickness W of the standing-wall cavity 218 is preferably set in the range of W = 0.5t to 1.5t, where t is the average wall thickness before core-back, as shown in Fig. 4. If W is less than 0.5t, the standing wall will deform during core-back. If the standing-wall thickness W is more than 1.5t, the standing wall will be too thick, resulting in sink marks on the exterior surface. The height H may be set to be equal to or greater than the average wall thickness x expansion ratio.

[0035] (2) FIG. 1B is a schematic cross-sectional view showing a state in which foaming resin 206 is injected into the cavity after clamping the mold in the method for producing a foam-molded product according to the first embodiment. <Foam resin> The foamed resin 206 is a molding resin mixed with high-pressure gas, and examples of molding resins include polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene (AS), polyamide (PA), polyacetal (POM), polylactic acid (PLA), polybutylene terephthalate (PBT), polyurethane (PU), polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), acrylic (PMMA), polyhydroxyalkanoate (PHA), polyphenylene sulfide (PPS), and nylon (PA6, PA66, etc.). Other examples of high-pressure gases include nitrogen (N2) and carbon dioxide (CO2). CO2 dissolves in large amounts in resin, which reduces viscosity and increases the foaming rate, but it also tends to cause large bubbles in certain areas, making it difficult to achieve a good cross-section. N2 dissolves in smaller amounts in resin, but is less effective at reducing viscosity and is easier to achieve fine foaming throughout the molded product, making nitrogen (N2) the preferred gas.

[0036] At this time, the fixed mold 201, first movable mold 202, and second movable mold 203 are closed, and the H&C 204 controls the temperature up to the mold edge, ensuring no temperature variations. After injection is complete, the H&C 204 starts cooling and continues until mold opening begins. The hydraulic cylinder 205 only needs to be turned on for hydraulic pressure between the completion of mold clamping and before core back.

[0037] (3) Figure 1-C is a schematic cross-sectional view showing the second movable die being cored back while maintaining the outer peripheral wall surface around the bottom of the molded product in the manufacturing method for a foam-molded product according to embodiment 1. After the foam resin 206 is completely filled, a skin layer is formed and the molded product becomes soft. The second movable die 203 is cored back in the direction of the arrow while maintaining the outer peripheral wall surface of the molded product. At this time, the hydraulic cylinder 205 is turned on and turned off after the second movable die 203 is cored back. The H&C 204 continues cooling until mold opening begins. The cooling time is set to 100 seconds or more and 120 seconds or less. Setting the cooling time to 100 seconds or more can suppress deformation of the outer surface, while setting it to 120 seconds or less can prevent one cycle from becoming too long, ensuring mass productivity. The core-back transition time of the second movable die 203 is preferably set to 3 seconds or more and 15 seconds or less. If the time is less than 3 seconds, the skin layer of the foamed resin 206 is stretched suddenly when the second movable mold 203 is cored back, causing cracks (tears) on the cavity side of the corners of the molded product. Also, the skin layer is thin and soft if the time is less than 3 seconds, so the external surface is easily deformed. On the other hand, if the time is more than 15 seconds, the skin layer is formed first, resulting in insufficient foaming and not foaming to the required thickness.

[0038] During core-back transition, after the foaming resin is injected, an operation to release the clamping force occurs before the second movable mold 203 performs core-back, as shown in Figure 6. The operation time differs depending on the molding machine, but it takes a minimum of about 2 seconds. Therefore, it is desirable to set the time required for the operation to release the clamping force to the minimum. Fig. 7A is a table showing the time to release the mold clamping force and the core-back transition time required for a mold opening amount of 2 mm in the manufacturing method for an expansion-molded product according to embodiment 1. Fig. 7B is a diagram showing the relationship between the core-back transition time, including the time to release the mold clamping force, and the mold opening amount in the manufacturing method for an expansion-molded product according to embodiment 1. The vertical axis of Fig. 7B represents the mold opening amount (unit: mm), and the horizontal axis represents time (seconds (s)). For the first 2 seconds, an operation to release the mold clamping force occurs (the mold opening amount remains 0) as shown in Figure 6, and the mold opening amount remains 0 mm. After the operation to release the mold clamping force is completed, the second movable mold 203 cores back, as shown in Figure 7B. The mold opening amount and core back transition time are set taking into account the operation time for releasing the mold clamping force.

[0039] (4) Figure 1-D is a schematic cross-sectional view showing the state in which core-backing of the second movable mold 203 is completed in the manufacturing method of a foam-molded product according to embodiment 1. The fixed mold 201 and the first movable mold 202 are in a closed state. The hydraulic pressure of the hydraulic cylinder 205 is turned off when core-backing is completed, and the H&C 204 is cooling to the set minimum temperature at this time, and continues cooling until mold opening begins.

[0040] (5) Figure 1-E is a schematic cross-sectional view showing the state during mold opening in the manufacturing method for a foam-molded product according to embodiment 1. The hydraulic cylinder 205 is in the OFF state, and the hydraulic pressure is turned ON when mold opening is complete. The foam-molded product 207 is then ejected by the ejector pin and removed from the mold 200. At this point, the H&C 204 starts heating from the start of the mold opening operation, and heats up to the set maximum temperature.

[0041] (6) Figure 1-F is a schematic cross-sectional view showing the operation of closing the mold (closing the mold 200) after removing the foam-molded product 207 from the fixed mold 201, first movable mold 202, and second movable mold 203 in the manufacturing method for a foam-molded product according to embodiment 1. At this point, the H&C 204 continues heating until it reaches the set maximum temperature before the foam resin is injected. At this time, the hydraulic cylinder 205 is in the OFF state and remains OFF until the mold is completely closed. In this way, the highly foam-molded product 207 is molded.

[0042] <Foam molded products> The foam-molded article 207 according to the first embodiment has a bottom surface and a standing wall structure surrounding the bottom surface, and the bottom surface and the standing wall structure define a recess. The bottom surface, which is foamed at a high expansion ratio by core-back of the second movable mold 203, has a lower density than the standing wall structure in which the wall surface is maintained. The density of the bottom surface may be half or less than that of the standing wall structure. [Industrial Applicability]

[0043] The foam-molded article according to the present disclosure contributes to weight reduction through high expansion ratio molding in the exteriors of various household electrical appliances and in the field of automotive installations. [Explanation of symbols]

[0044] 200...Mold 201…Fixed type 202…1st movable type 203…Second movable type 204...H&C (Heat & Cool Device) 205...Hydraulic cylinder 206...Foam resin 207...Foam molded products 208…Cabinet side corner R 209...Core side corner R 210...inside the cavity 212...Core side skin layer 213...Cavity side skin layer 214 Groove 216 bottom cavity 218 Vertical Wall Cavity 220 cavity W: Wall thickness t...Average thickness before core back H...height 10...Automotive parts 11...Foamed resin molded body 111...Foam section 112...Skin section 12...Outer edge 13...Device peripheral area 14...Groove 15m, 15n...surface of the area around the device 16...Terminal 17...Outer surface 20...Body 21...Double-sided tape

Claims

1. An apparatus for manufacturing a foam-molded product that produces a foam-molded product having a bottom surface and a standing wall structure around the bottom surface, a mold including a fixed mold, a first movable mold, and a second movable mold, which when the mold is clamped forms a cavity corresponding to the foam-molded product, including a bottom cavity corresponding to the bottom surface between the fixed mold, the first movable mold, and the second movable mold, and a standing wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold, and the second movable mold is capable of being cored back to expand the bottom cavity; a foam resin injection unit that can inject a foam resin, which is a mixture of molding resin and high-pressure gas, into the cavity to fill the cavity with the foam resin; a core-back driving unit that cores back the second movable mold to further foam the foaming resin filled in the bottom cavity, thereby forming a foam-molded product; a mold driving unit that clamps and opens the fixed mold, the first movable mold, and the second movable mold; An apparatus for manufacturing foam-molded products, comprising:

2. 2. The apparatus for manufacturing foam-molded products according to claim 1, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a larger radius of curvature on the inner side formed between the fixed mold and the second movable mold than on the outer side formed between the fixed mold and the first movable mold.

3. 2. The apparatus for manufacturing foam-molded products according to claim 1, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a chamfered C-surface on the outer surface side formed between the fixed mold and the first movable mold and an inner surface side formed between the fixed mold and the second movable mold, and the amount of chamfering of the C-surface on the inner surface side is greater than the amount of chamfering of the C-surface on the outer surface side.

4. 2. The apparatus for producing a foam-molded product according to claim 1, wherein the thickness W of the upright wall cavity is 0.5t to 1.5t relative to the average thickness t of the bottom cavity.

5. The apparatus for producing a foam-molded product according to claim 1 , wherein the second movable mold has a plurality of second movable molds that can be independently core-backed.

6. A method for manufacturing a foam-molded product, which produces a foam-molded product having a bottom surface and a standing wall structure around the bottom surface, a mold clamping step of clamping a fixed mold, a first movable mold, and a second movable mold together to form a cavity corresponding to the foam-molded product, the cavity including a bottom cavity corresponding to the bottom between the fixed mold, the first movable mold, and the second movable mold, and a standing wall cavity corresponding to the standing wall structure between the first movable mold and the second movable mold; an injection step of injecting a foamed resin, which is a mixture of a molding resin and a high-pressure gas, into the cavity to fill the cavity with the foamed resin; a core-back process in which the second movable mold is core-backed to further foam the foaming resin filled in the bottom cavity to obtain a foam-molded product; a mold opening step of opening the fixed mold, the first movable mold, and the second movable mold to remove the foam-molded article; A method for producing a foam-molded article, comprising:

7. 7. A method for manufacturing a foam-molded product as described in claim 6, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a larger radius of curvature on the inner side formed between the fixed mold and the second movable mold than on the outer side formed between the fixed mold and the first movable mold.

8. 7. The method for manufacturing a foam-molded product according to claim 6, wherein the bottom cavity formed between the fixed mold and the first movable mold and the second movable mold has a chamfered C-surface on the outer surface side formed between the fixed mold and the first movable mold and an inner surface side formed between the fixed mold and the second movable mold, and the amount of chamfering of the C-surface on the inner surface side is greater than the amount of chamfering of the C-surface on the outer surface side.

9. 7. The method for producing a foam-molded product according to claim 6, wherein the thickness W of the upright wall cavity is 0.5t to 1.5t relative to the average thickness t of the bottom cavity in the mold clamping step before the core-back step.

10. The method for producing a foam-molded product according to claim 6 , wherein the second movable mold has a plurality of second movable molds that can be independently core-backed.

11. A foam-molded product having a bottom surface and a standing wall structure around the bottom surface, wherein the bottom surface and the standing wall structure form a recess, The foam-molded product has a bottom surface with a lower density than the upright wall structure.

12. The foam-molded article according to claim 11, wherein the density of the bottom surface is half or less than that of the standing wall structure.

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