Mold device for sandwich molded body and mold method for sandwich molded body

Abstract

To provide a sandwich molded article mold assembly that molds a sandwich molded article molded in high accuracy and having ensured heat resistance, and a method for molding the sandwich molded article using the sandwich molded article mold assembly.SOLUTION: A sandwich molded article mold assembly for injection molding a sandwich molded article formed using different materials for a core layer located in a middle and skin layers sandwiching the core layer from front and back sides, comprises: a cavity in which the sandwich molded article is formed; a primary gate for feeding a skin material being a constituent of the skin layers from both ends of the cavity; a secondary gate for feeding a core material being a constituent of the core layer from both ends of the cavity; and a plurality of spillover parts for discharging the skin material and the core material during the injection molding. Each of the spillover parts is arranged in the vicinity of a corner that forms an edge of the sandwich molded article, and the vicinity of a weld portion to which the skin material and the core material fed from both ends join in the cavity.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a mold apparatus for forming a sandwich molded body, for example, a sandwich molded body for forming an outer panel of an automobile, and a method for molding a sandwich molded body using the mold apparatus for forming a sandwich molded body. [Background technology]

[0002] In recent years, from the viewpoint of weight reduction, plastic exterior panels have been used instead of conventional metal exterior panels as automobile exterior panels such as bumpers and fenders. As a component for forming such a plastic exterior panel, a sandwich molded body is known in which a middle core layer and skin layers sandwiching the core layer from the front and back are made of different materials (see, for example, Patent Document 1). In the above-mentioned sandwich molded body, there is known an example in which a polypropylene resin having excellent appearance is used for the skin layer, and a composite material of polypropylene having excellent mechanical properties with glass fiber or carbon fiber is used for the core layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-353749 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when complex shapes such as sliding doors are sandwich molded, various problems arise. For example, when the above-mentioned sandwich molded body is injection molded, the skin material forming the skin layer may accumulate in the four corners and center of the sliding door, forming a skin material pool 104, as shown in Fig. 7. In this case, problems such as warping of the panel constituting the sliding door, deterioration of molding dimensional accuracy, and deformation of the panel during in-line painting due to insufficient filling of the core material and inability to ensure heat resistance may occur.

[0005] In addition, core material overflow 106 may occur, forming a core material in the weld portion. In this case, problems such as the surface roughness becoming rough and the quality of the outer panel deteriorating due to the fibers protruding from the outer panel may occur.

[0006] An object of the present invention is to provide a mold apparatus for a sandwich molded body, which molds a sandwich molded body that is precisely molded and has ensured heat resistance, and a method for molding a sandwich molded body using the mold apparatus for a sandwich molded body. [Means for solving the problem]

[0007] The mold device for a sandwich molded body of the present invention is From the core layer in the middle and the front and back The above A mold device for a sandwich molded product for injection molding a sandwich molded product having a core layer and skin layers sandwiched therebetween using different materials, comprising: A cavity in which the sandwich molded body is formed; a primary gate for supplying a skin material constituting the skin layer from both ends of the cavity; a secondary gate for supplying a core material constituting the core layer from both ends of the cavity; The fluid supplied to the cavity The skin material and the core material The sandwich molded body Discharged during injection molding Be Multiple spillover areas and Equipped with The spillover portions are located near corners that form edges of the sandwich molded body, and In the cavity, the skin material is supplied from both ends. and The core material is characterized in being disposed in the vicinity of a weld portion where the two flows join together.

[0008] In this way, by arranging the spillover portion near the corner portion of the sandwich molded body, it is possible to prevent the formation of skin material accumulation at the corner portion. This makes it possible to prevent the panel from warping, which deteriorates the molding dimensional accuracy, or from being deformed due to insufficient filling of the core material, which makes it difficult to ensure heat resistance. In addition, by arranging the spillover portion near the weld portion, it becomes difficult for the core material to overflow, so that it is possible to prevent deterioration of the quality of the panel, such as fibers protruding from the panel and causing surface roughness. Therefore, it is possible to mold a sandwich molded body that is precisely molded and has ensured heat resistance.

[0009] In addition, the mold device for a sandwich molded body of the present invention is The spillover section is characterized by having an opening and closing pin that adjusts the time when the skin material and the core material are discharged from each spillover section.

[0010] In this way, by adjusting the time when the resin material is discharged, the timing of the resin material being discharged from areas such as corners and welds can be changed, making it possible to achieve a good balance between excess and deficiency of resin material in each area.

[0011] In addition, the mold device for a sandwich molded body of the present invention is an opening / closing control unit that opens and closes the opening / closing pin, The opening / closing control section is characterized in that it is any one of a hydraulic cylinder, an air cylinder, and an electric control section. In this way, by making it possible to apply a plurality of types of devices to the opening / closing control section, the present invention can be applied to various types of molds.

[0012] In addition, the mold device for a sandwich molded body of the present invention is The sandwich molded article after demolding is a panel used as an outer panel of an automobile. That is, the mold apparatus for producing a sandwich molded body of the present invention is officially used for molding outer panels of automobiles.

[0013] Further, the sandwich molding method of the present invention includes the steps of: A method for molding a sandwich molded body using the above-mentioned mold device for a sandwich molded body, a first step of discharging the skin material to the spillover portion by opening and closing the opening and closing pin in the vicinity of the corner portion; a second step of discharging the core material into the spillover portion by opening and closing the opening and closing pin in the vicinity of the weld portion after the first step is completed; The present invention is characterized by comprising: By following this procedure, the resin material can be discharged in a well-balanced manner, and a sandwich molded body can be formed with high precision.

[0014] Further, the sandwich molding method of the present invention includes the steps of: The second step includes an interruption step of temporarily interrupting the discharge of the core material. This allows for greater precision in molding the sandwich molded body at the weld portion. Effect of the Invention

[0015] According to the present invention, it is possible to provide a mold device for a sandwich molded body, which molds a sandwich molded body that is precisely molded and has ensured heat resistance, and a method for molding a sandwich molded body using the mold device for a sandwich molded body. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of a mold device for a sandwich molded body according to an embodiment, viewed from above. FIG. [Diagram 2] 1 is a schematic diagram of a mold device for a sandwich molded body according to an embodiment, viewed from the side. FIG. [Diagram 3] 11 is a table showing the injection time of the resin material and the opening time of the spillover portion according to the embodiment. [Figure 4] 11A to 11C are diagrams showing a process in which a resin material is filled into a cavity of a mold in the embodiment. [Diagram 5] 11A to 11C are diagrams showing a process in which a resin material is filled into a cavity of a mold in the embodiment. [Figure 6] 11A and 11B are diagrams showing how a skin material is stretched by a core material moving through a cavity of a mold according to an embodiment. [Figure 7] FIG. 1 is a diagram showing a process for injection molding a sandwich molded body according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram of a mold device for a sandwich molded body (hereinafter, abbreviated as a mold device) according to the embodiment, viewed from above, and Fig. 2 is a schematic diagram of the same viewed from the side.

[0018] As shown in Figures 1 and 2, the mold device 2 is an apparatus used for molding a sandwich molded body 30 in which different materials are used for a core layer located in the middle and skin layers sandwiching the core layer from the front and back, and is equipped with a flat rectangular mold 4, a first resin unit (not shown) that supplies the skin material, which is the first resin material that constitutes the skin layer, to the mold 4, a second resin unit (not shown) that supplies the core material, which is the second resin material that constitutes the core layer, to the mold 4, a first nozzle 8 which is a flow path for the skin material, a second nozzle 10 which is a flow path for the core material, a hydraulic cylinder 12, and an opening and closing pin 14 connected to the hydraulic cylinder 12.

[0019] At the tip of the first nozzle 8, primary gates 8a and 8b are provided as supply ports for the skin material, and at the tip of the second nozzle 10, secondary gates 10a and 10b are provided as supply ports for the core material. (In the following description, the direction connecting the primary gates 8a and 8b is referred to as the vertical direction, and the direction perpendicular to this is referred to as the horizontal direction.)

[0020] The mold 4 is formed with a cavity 20 in which the sandwich molded body 30 is formed, a film gate 22 which is an inlet for introducing resin material into the cavity 20, and a spillover portion 24 for discharging the resin material from the cavity 20 during injection molding.

[0021] Here, the cavity 20 is supplied at both ends with skin material by primary gates 8a, 8b and with core material by secondary gates 10a, 10b. In addition, spillover portion 24 includes seven portions: spillover portions 24a, 24b, 24c, 24d, 24e, 24f, and 24g.

[0022] Here, spillover portions 24a, 24b, 24e, and 24f are arranged in the mold 4 near the corner portion 30a that forms the edge of the sandwich molded body 30 (lateral outside of the cavity portion 20 and both vertical end sides of the cavity portion 20), spillover portion 24g is arranged near the window corner portion 30b that forms the edge of the window portion of the sandwich molded body 30 (inside the window portion), and spillover portions 24c and 24d are arranged in the cavity portion 20 near the weld portion 30c where the skin material and core material supplied from both ends join together (lateral outside of the cavity portion 20 and vertical center side of the cavity portion 20).

[0023] Each spillover section 24 is opened and closed by pins 14a, 14b, 14c, 14d, 14e, 14f, and 14g via hydraulic cylinder 12, which is an opening and closing control section. The timing of opening and closing of each pin 14 can be adjusted when the skin material and the core material are discharged.

[0024] The mold 4 includes an upper mold 4a that is vertically movable and a lower mold 4b that is fixed. Next, a method for forming the sandwich molded body 30 using the mold device 2 will be described with reference to the table shown in FIG. 3, taking as an example a case of manufacturing a panel constituting a sliding door among the outer panels of an automobile. First, the movable upper mold 4a is moved downward to close the mold 4. Next, the primary gate 8b of the mold 4 is opened by a gate opening / closing unit (not shown), and the skin material that will be the surface layer of the sandwich molded body 30 is injected into the first nozzle 8 by the first resin unit, and the skin material 32 is supplied to the portion that constitutes the lower part of the sandwich molded body 30, as shown in FIG. 4. Here, as shown in FIG. 3, the time when the skin material 32 is first injected is set as a first reference time, and the skin material 32 continues to be injected for 6 seconds from the first reference time.

[0025] Next, 4.5 seconds after the first reference time, the primary gate 8a of the mold 4 is opened by the gate opening / closing unit, and the skin material 32 is injected from the primary gate 8a for 2 seconds, and the skin material 32 is also supplied to the portion that constitutes the upper part of the sandwich molded body 30 (see Figure 4).

[0026] Then, when six seconds have elapsed from the first reference time, the injection of the skin material 32 by the first resin unit is stopped, and both primary gates 8a, 8b are closed by the gate opening / closing portion. Next, when the secondary gate 10b of the mold 4 is opened by the gate opening / closing unit, the second resin unit injects the core material 34 that will be the intermediate layer of the sandwich molded body 30 into the second nozzle 10, and as shown in Fig. 5, the core material 34 is supplied to the portion that constitutes the lower part of the sandwich molded body 30. Note that the time when the core material 34 is first injected is set as the second reference time, and the core material 34 continues to be injected for 5.5 seconds from the second reference time (until 11.5 seconds from the first reference time).

[0027] Here, by injecting the core material 34 into the hollow portion 20, the skin material 32 is stretched as the core material 34 advances, as shown in Fig. 6. This allows the skin material 32 to spread throughout the entire hollow portion 20.

[0028] At the same time, the hydraulic cylinder 12 operates the opening and closing pins 14a, 14b, 14e, and 14f to open the spillover portions 24a, 24b, 24e, and 24f, and the skin material 32 accumulated in the corner portion 30a is discharged into the spillover portions 24a, 24b, 24e, and 24f. To This makes it possible to prevent the formation of skin material pools (see FIG. 7) at the corner portions 30a of the sandwich molded body 30.

[0029] During this time, one second after the second reference time (seven seconds after the first reference time), the hydraulic cylinder 12 further operates the opening / closing pin 14g to open the spillover portion 24g, and the skin material 32 accumulated in the window corner portion 30b is poured into the spillover portion 24g. To This prevents accumulation of skin material at the window corners 30b.

[0030] Then, 1.5 seconds after the second reference time (7.5 seconds after the first reference time), the opening / closing pins 14a, 14b, 14e, and 14f are operated by the hydraulic cylinder 12, and the spillover portions 24a, 24b, 24e, and 24f are closed.

[0031] Next, 2 seconds after the second reference time (8 seconds after the first reference time), when the skin material 32 accumulated in the corner portion 30a of the sandwich molded body 30 is completely discharged, the opening and closing pins 14c, 14d are operated by the hydraulic cylinder 12 to open the spillover portions 24c, 24d, and the skin material 32 accumulated in the weld portion 30c of the sandwich molded body 30 is discharged into the spillover portions 24c, 24d. To It is then discharged (step 2).

[0032] Furthermore, 2.5 seconds after the second reference time (8.5 seconds after the first reference time), the secondary gate 10a of the mold 4 is opened by the gate opening / closing part. As a result, the core material 34 is also supplied to the portion constituting the upper part of the sandwich molded body 30, as shown in FIG.

[0033] Immediately thereafter, 2.8 seconds after the second reference time (8.8 seconds after the first reference time), the opening / closing pin 14g is operated by the hydraulic cylinder 12 to close the spillover portion 24g, completing the discharge of the skin material 32 accumulated in the window corner portion 30b, and 3.3 seconds after the second reference time (9.3 seconds after the first reference time), the spillover portions 24c, 24d are temporarily closed via the opening / closing pins 14c, 14d (interruption process).

[0034] Then, 4.5 seconds after the second reference time (10.5 seconds after the first reference time), the spillover portions 24c, 24d are opened again by the opening / closing pins 14c, 14d, and the excess core material 34 in the weld portion 30c where the core material 34 injected from the secondary gates 10a, 10b joins is discharged (second process). This makes it difficult for the core material to overflow from the weld portion 30c (see FIG. 7).

[0035] 5.5 seconds after the second reference time (11.5 seconds after the first reference time), the injection of the core material 34 by the second resin unit is stopped, and the secondary gates 10a and 10b are both closed by the gate opening / closing parts. At the same time, the hydraulic cylinder 12 operates the opening / closing pins 14c and 14d to close the spillover parts 24c and 24d again.

[0036] Next, pressure is applied to maintain the shape of the sandwich molded body 30, and after the sandwich molded body 30 has cooled and hardened, the upper mold 4a is moved upward to open the mold 4, and the panel is released.

[0037] In addition, since the tip of the opening / closing pin 14 is sharp, the resin material remaining in the spillover portion 24 and the sandwich molded body 30 are separated by closing the opening / closing pin 14. Therefore, the separation of the resin material remaining in the spillover portion 24 and the sandwich molded body 30 at the time of demolding is smoothly performed.

[0038] According to the invention of this embodiment, by arranging the spillover parts 24a, 24b, 24e, 24f, and 24g in the vicinity of the corner part 30a and the window corner part 30b of the sandwich molded body 30, it is possible to prevent the formation of skin material pools in the corner part 30a and the window corner part 30b. This makes it possible to prevent the panel completed from the sandwich molded body 30 from warping, which deteriorates the molding dimensional accuracy, and the panel from being deformed due to insufficient filling of the core material 34 not being able to ensure heat resistance. In addition, by arranging the spillover parts 24c and 24d in the vicinity of the weld part 30c, it becomes difficult for the core material to overflow, and this prevents deterioration of the quality of the panel, such as fibers protruding from the panel and causing the surface roughness to become rough.

[0039] This allows the panel to be molded with high precision, and ensures the heat resistance of the panel. In addition, by temporarily suspending the opening of the spillover portions 24c, 24d, the molding accuracy of the sandwich molded body 30 at the weld portion 30c can be further improved.

[0040] In the above embodiment, the opening / closing control unit is the hydraulic cylinder 12, but instead of the hydraulic cylinder 12, an air cylinder or an electric control unit may be used as the opening / closing control unit.

[0041] In addition, in the above-described embodiment, the table shown in FIG. 3 is only an example, and the injection time of the resin material and the opening time of the spillover portion 24 do not have to be strictly these times, and various modifications are possible without departing from the scope of the present invention.

[0042] In addition, in the above embodiment, it is mentioned that the skin material and the core material are supplied from both ends of the cavity 20, but the both ends mentioned here do not necessarily mean the upper center and the lower center as shown in Fig. 1. For example, the primary gates 8a, 8b and the secondary gates 10a, 10b for supplying the skin material and the core material may be provided near any of the spillover portions 24, and the skin material and the core material may be supplied from different directions, such as in both directions.

[0043] In the above-described embodiment, the skin material includes a propylene-based resin. Examples of the propylene-based resin include a propylene homopolymer and a copolymer of propylene and at least one selected from ethylene and an α-olefin having 4 or more carbon atoms. The copolymer may be a propylene-based random copolymer or a propylene-based block copolymer.

[0044] Examples of α-olefins having 4 or more carbon atoms include 1-butene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, and ethyl-1-pentene. Examples of α-olefins having 4 to 20 carbon atoms include 1-butene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl-1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. Among these, 1-butene, 1-pentene, 1-hexene, and 1-octene are preferred.

[0045] The propylene-based resin is preferably a propylene homopolymer or a propylene block copolymer, which is also called impact polypropylene and is usually a mixture of a polypropylene homopolymer and a propylene-ethylene copolymer.

[0046] The propylene-based resin may contain a propylene-based resin modified with an unsaturated carboxylic acid or a derivative thereof, such as maleic anhydride, fumaric acid, or (meth)acrylic acid. In such modified propylene-based resin, the content of the unsaturated carboxylic acid or a derivative thereof is preferably 0.01 to 10% by mass.

[0047] The core material contains a fiber-reinforced propylene-based resin, which imparts excellent heat resistance and mechanical strength to the molded article of the present embodiment. The propylene-based resin in the fiber-reinforced propylene-based resin may be the propylene-based resin described in the description of the skin material. However, the propylene-based resin contained in the fiber-reinforced propylene-based resin and the propylene-based resin contained in the skin material may be the same resin or different resins. In addition, a part or all of the propylene-based resin may be recycled material.

[0048] Examples of the fibers in the fiber-reinforced propylene-based resin include glass fibers, carbon fibers, metal fibers such as aluminum fibers, aluminum alloy fibers, copper fibers, brass fibers, steel fibers, stainless steel fibers, and titanium fibers, natural fibers such as cotton fibers, silk fibers, wood fibers, and cellulose fibers, ceramic fibers such as silicon carbide fibers, silicon nitride fibers, alumina fibers, and zirconia fibers, and synthetic fibers made of synthetic resins such as fully aromatic polyamide (aramid), fully aromatic polyester, fully aromatic polyesteramide, fully aromatic polyether, fully aromatic polycarbonate, fully aromatic polyazomethine, polyphenylene sulfide, polyparaphenylene benzobisoxazole, poly(para-phenylene benzobisthiazole), polybenzimidazole, polyether ether ketone, polyamide imide, polyimide, polytetrafluoroethylene, polyvinyl alcohol, polyolefin, polyarylate, and fluorine-based polymers. Examples of the glass fibers include filament-like fibers obtained by melt spinning glass such as E glass, C glass, S glass, and alkali-resistant glass. Among the fibers, glass fibers and carbon fibers are preferred from the viewpoints of rigidity, heat resistance, and the like.

[0049] If necessary, the fibers may be subjected to a surface treatment such as a coupling agent treatment, a surfactant treatment, an ultraviolet ray irradiation treatment, an electron beam irradiation treatment, a plasma irradiation treatment, etc. Examples of the coupling agent include amino group-containing alkoxysilanes such as γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane, and hydrolysates thereof.

[0050] The fibers may be short or long, but long fibers are preferred because the physical properties of the resulting molded product are excellent, and short fibers are preferred from the viewpoint of flowability during molding. A mixture of short and long fibers may also be used. The short fibers may be chopped fiber (cut fiber) short fibers or pulp-like short fibers having fibrils. [Explanation of symbols]

[0051] 2. Mold equipment 4. Mold 4a Upper mold 4b Lower mold 8 Nozzles 8a Primary Gate 8b Primary Gate 10 Nozzles 10a Secondary Gate 10b Secondary Gate 12 Hydraulic cylinder 14(14a, 14b, 14c, 14d, 14e, 14f, 14g) Opening pin 20 Cavity 22 Film Gate 24(24a, 24b, 24c, 24d, 24e, 24f, 24g) Spillover section 30 Sandwich molding 30a Corner section 30b Window corner 30c Weld 32 Skin material 34 Core material 104 Skin material pool 106 Core material overflow

Claims

1. A mold device for a sandwich molded body for injection molding a sandwich molded body having a core layer located in the middle and skin layers sandwiching the core layer from the front and back, the core layer being made of different materials, A cavity in which the sandwich molded body is formed; a primary gate for supplying a skin material constituting the skin layer from both ends of the cavity; a secondary gate for supplying a core material constituting the core layer from both ends of the cavity; a plurality of spillover portions through which the skin material supplied to the cavity is discharged during injection molding of the sandwich molded body; Equipped with A mold device for sandwich molded bodies, characterized in that the spillover portions are located near corner portions that form the edges of the sandwich molded body, and near a weld portion in the hollow portion where the skin material and the core material supplied from both ends join together.

2. A mold apparatus for a sandwich molded body as described in claim 1, characterized in that the spillover portion is further arranged in the vicinity of a window corner portion that forms the edge of the window portion of the sandwich molded body.

3. A mold apparatus for a sandwich molded body as described in claim 1 or 2, characterized in that the core material supplied to the hollow portion is also discharged into the spillover portion located in the vicinity of the weld portion during injection molding of the sandwich molded body.

4. 4. A mold device for producing a sandwich molded body according to claim 3, further comprising an opening / closing pin for adjusting the time of discharge of the skin material and the core material in each of the spillover portions.

5. an opening / closing control unit that opens and closes the opening / closing pin, 5. The mold apparatus for producing a sandwich molded body according to claim 4, wherein the opening / closing control section is any one of a hydraulic cylinder, an air cylinder, and an electric control section.

6. 6. The mold apparatus for a sandwich molded body according to claim 4, wherein the sandwich molded body after demolding is a panel used as an outer panel of an automobile.

7. A method for molding a sandwich molded body using the mold device for a sandwich molded body according to any one of claims 4 to 6, a first step of discharging the skin material to the spillover portion by opening and closing the opening and closing pin in the vicinity of the corner portion; a second step of discharging the core material into the spillover portion by opening and closing the opening and closing pin in the vicinity of the weld portion after the first step is completed. A method for molding a sandwich molded body, comprising:

8. 8. The method for molding a sandwich molded body according to claim 7, wherein the second step includes an interruption step of temporarily interrupting the discharge of the core material.

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