JP2018140546A - Molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method capable of molding a high quality composite molded article without causing a thin wall or pinhole in a resin sheet at a periphery of a deep drawing shape.SOLUTION: A core material is sandwiched between a pair of resin sheets, each resin sheet is vacuum-sucked from a cavity surface to be in close contact with a mold, and then the mold is clamped and molded. At least one of the resin sheets is stretched by pressing the core material, and then the resin sheet is brought into close contact with the mold by vacuum suction. The core material is composed of a core material main body formed of a material hard to be welded to the resin sheet and an insertion material formed of a material that is easily welded to the resin sheet and inserted into a hole formed in the core material main body. The core material is pressed against the resin sheet in a state where the insert material is retreated from a contact face with the resin sheet, and the resin sheet is brought into close contact with the mold by vacuum suction, and then the insert material is pushed into contact with the resin sheet.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a molding method for molding a composite molded article composed of a resin sheet and a core material.

  For example, when forming a single-walled resin molded product, prepare a raw sheet made of thermoplastic resin in advance, reheat it until it is in a molten state, and then apply vacuum to the mold cavity by vacuum suction or air pressure Molding and pressure forming are performed. Vacuum forming and compressed air forming have features such as being suitable for high-mix low-volume production. For example, two resin sheets are extruded, and these are brought into close contact with a pair of molds by vacuum suction, and then clamped. Integrated molding technology has also been developed.

  In addition, a molding method in which a core material is inserted between resin sheets for molding has also been proposed. For example, Patent Document 1 discloses a method for manufacturing a resin panel in which a foam and a reinforcing material are provided. In the method for manufacturing a resin panel disclosed in Patent Document 1, a parison or a resin sheet in a molten state is disposed between divided molds, and the parison or the resin sheet is press-molded into a cavity of the mold by vacuum or compressed air, which is a core material. The foam is placed in the cavity and clamped, and the inner surface of the molten parison or resin sheet and the outer surface of the foam are welded.

JP 2006-334801 A

  By the way, in these vacuum forming and pressure forming, it is necessary to securely adhere the heat-melted resin sheet to the cavity surface of the mold. If the adhesion of the resin sheet to the mold cavity is poor, the surface shape of the mold cannot be transferred sufficiently, and a resin molded product of a predetermined quality cannot be obtained.

  On the other hand, with the diversification of resin molded products, the shapes of the molded products are also various, and in some cases, vacuum suction of the resin sheet is difficult. For example, in a molded product, if the resin sheet has a deep drawing shape, it is necessary to greatly stretch the resin sheet, and if you try to shape the deep drawing shape by closely contacting the mold by vacuum suction, Thin walls and pinholes are likely to occur around

  The present invention has been proposed in view of such a conventional situation, the resin sheet can be stretched smoothly, and there is no occurrence of thin wall or pinhole in the resin sheet around the deep drawing shape, An object of the present invention is to provide a molding method capable of molding a high-quality composite molded product.

  In order to achieve the above-described object, the molding method of the present invention includes a method in which a core material is sandwiched between a pair of resin sheets and each resin sheet is brought into close contact with the mold by vacuum suction from the cavity surface. Is a molding method in which the mold is clamped to mold, and at least one resin sheet is stretched by pressing against a core material, and is then brought into close contact with the mold by vacuum suction.

  If the resin sheet is vacuum-sucked with a mold, the molten resin sheet is partially attached to the mold surface, causing unevenness in stretching, leading to thinning and pinholes. In contrast, when the resin sheet is stretched by pressing the core material, the portion of the core material in contact with the melted resin sheet is melted, and this serves as a lubricant, thereby being smoothly stretched. Then, if it shape | molds by vacuum suction of a metal mold | die, a resin sheet will be shape | molded by the deep drawing shape, without generating thin wall and a pinhole.

  According to the present invention, the resin sheet can be smoothly stretched, and a high-quality composite molded product can be formed without generating a thin wall or pinhole in the resin sheet around the deep-drawn shape.

It is a schematic sectional drawing which shows the shaping | molding method to which this invention is applied in order of a process, and is a figure which shows the insertion process of a core material. It is a schematic sectional drawing which shows the extending process of the resin sheet by a core material. It is a schematic sectional drawing which shows the shaping | molding process of the resin sheet by vacuum suction. It is a schematic sectional drawing which shows the pushing process of an insertion material. It is a schematic sectional drawing which shows a mold clamping process. It is a schematic perspective view of a core material. It is a schematic sectional drawing of a core material. It is a schematic sectional drawing which expands and shows the insertion hole vicinity of a core material. It is a schematic sectional drawing which shows a mode that a resin sheet is shaped only by the vacuum suction of a metal mold | die.

  Hereinafter, embodiments of a molding method to which the present invention is applied will be described in detail with reference to the drawings.

  A molded product manufactured by the molding method of the present embodiment has a skin material in which a thermoplastic resin sheet (molten resin sheet) is molded, and a core material is joined and integrated therein.

  FIG. 1 to FIG. 5 show the molding method of this embodiment in the order of steps. First, in molding, as shown in FIG. 1, a pair of molten thermoplastic resin sheets (molten resin sheets) 1, 2 is supplied between the pair of molds 3, 4, and the core material 5 is inserted between the thermoplastic resin sheets 1, 2 using, for example, a robot hand.

  The thermoplastic resin used for the thermoplastic resin sheets 1 and 2 is not particularly limited and may be any one as long as it can be molded. For example, a polyethylene resin or a polypropylene resin may be used. Engineering plastics such as ethylene-vinyl acetate copolymer, vinyl chloride resin, ABS resin (acrylonitrile-styrene-butadiene resin), polyamide resin, polystyrene resin, polyester resin, polycarbonate resin, modified polyphenylene ether Etc. are suitable, and fillers such as glass fiber, carbon fiber, calcium carbonate, talc, mica, etc. can be added as necessary.

  Any resin material can be used as the core material 5, and for example, a foam can be used. The foam is obtained by foam-molding various resin materials, and examples of the resin material include polyethylene resins and polypropylene resins. As the polyethylene resin, low density polyethylene (LDPE), high density polyethylene (HDPE), linear short chain branched polyethylene (LLDPE), etc. can be used. Copolymerization of ethylene and other copolymerizable monomers It may be a coalescence. Examples of the polypropylene resin include a propylene homopolymer, a random or block copolymer of propylene and another α-olefin (such as ethylene, butene, pentene, hexene, octene, and methylpentene). In any case, it is preferable to contain polyethylene or polypropylene having a long-chain branched structure. Alternatively, it is also possible to use a foam of polyacrylonitrile / styrene copolymer (so-called heat pole).

  Here, the resin material used for the core material 5 is preferably one that is difficult to weld to the thermoplastic resin sheets 1 and 2. If the core material 5 is easily welded to the thermoplastic resin sheets 1 and 2, the thermoplastic resin sheets 1 and 2 are welded to the core material 5, and smooth stretching may be difficult.

  Since the crystalline thermoplastic resin, the amorphous thermoplastic resin and the thermosetting resin have poor compatibility with each other, for example, the thermoplastic resin sheets 1 and 2 made of a crystalline thermoplastic resin are amorphous thermoplastic resins. The core material 5 made of a thermosetting resin is hardly thermally welded. The thermoplastic resin sheets 1 and 2 made of an amorphous thermoplastic resin are hardly thermally welded to the core material 5 made of a crystalline thermoplastic resin or a thermosetting resin. In addition, as a crystalline thermoplastic resin, polyolefin resin (for example, polypropylene, polyethylene) etc. can be illustrated. Examples of the amorphous thermoplastic resin include a styrene resin (for example, polystyrene) and a modified polyphenylene ether resin. Examples of the thermosetting resin include phenolic resins.

  However, if the entire core material 5 is formed of a material that is difficult to weld to the thermoplastic resin sheets 1 and 2, the adhesion between the thermoplastic resin sheets 1 and 2, which are the skin materials, and the core material 5 becomes insufficient after molding, and composite molding The quality of the product may be reduced.

  Therefore, in the present embodiment, most of the core material 5 is formed of a material that is difficult to weld to the thermoplastic resin sheets 1 and 2, and an insert material that is easily welded to the thermoplastic resin sheets 1 and 2 is formed in the core material 5. By embedding, both formability and adhesiveness are achieved.

  6 to 8 show an example of the core material 5 used in the molding method of the present embodiment. In this example, the core material 5 is comprised from the core material main body 51 and the insertion material 52 inserted in it.

  The core material main body 51 is the main body of the core material 5, and the outer shape thereof is substantially the same as the shape of the core material 5. In the present embodiment, the protruding portion 5 </ b> A is formed on the core material 5 corresponding to the deep drawing shape, but the protruding portion 5 </ b> A is formed by providing a protruding portion on the core material main body 51.

  The core material body 51 is preferably formed of a material that is difficult to weld to the thermoplastic resin sheets 1 and 2, whereby the thermoplastic resin sheets 1 and 2 can be smoothly stretched. When the core material body 51 is formed of a material that is easily welded to the thermoplastic resin sheets 1 and 2, when the core material body 51 comes into contact with the thermoplastic resin sheets 1 and 2, the thermoplastic resin sheets 1 and 2 are It sticks to the core material main body 51, and smooth stretching is difficult. If the core material body 51 is formed of a material that is difficult to weld to the thermoplastic resin sheets 1 and 2, the thermoplastic resin sheets 1 and 2 do not stick to the core material body 51, and the thermoplastic resin sheet 1. , 2 are stretched so as to slide along the surface of the core body 51.

  On the other hand, the insert material 52 is provided for joining and integrating the core material 5 and the thermoplastic resin sheets 1 and 2, and is therefore formed of a material that is easily welded to the thermoplastic resin sheets 1 and 2. Yes. Further, the insertion material 52 is inserted into an insertion hole 53 provided in the core material main body 51 and integrated with the core material main body 51. The insertion material 52 can freely advance and retreat in the insertion hole 53, as shown in FIG. As shown, the core material body 51 can be retracted from the contact surface with the thermoplastic resin sheets 1 and 2.

  Note that an annular rib 54 may be provided in the opening of the insertion hole 53 of the core material main body 51 on the contact surface side with the thermoplastic resin sheets 1 and 2 as shown in FIG. By providing the rib 54, the contact between the thermoplastic resin sheets 1 and 2 and the insertion material 52 can be surely prevented, and the thermoplastic resin sheets 1 and 2 can be smoothly stretched. The rib 54 melts and disappears quickly by contacting the molten thermoplastic resin sheets 1 and 2 and does not affect the molded product.

  As described above, when molding a composite molded product, first, as shown in FIG. 1, molten thermoplastic resin sheets (molten resin sheets) 1 and 2 are supplied between a pair of molds 3 and 4. The core material 5 is inserted between the thermoplastic resin sheets 1 and 2 using, for example, a robot hand or the like. At this time, the insertion material 52 is retracted from the contact surface of the core material body 51 with the thermoplastic resin sheet 1. Keep it.

  In this state, as shown in FIG. 2, the core material 51 is pressed against the thermoplastic resin sheet 1 on the side where the protruding portions 5A are formed, and the thermoplastic resin sheet 1 is stretched so as to follow the shape of the core material 5 (expanded). To do). At this time, the thermoplastic resin sheet 1 comes into contact with the core material body 51, but the core material body 51 is formed of a material that is difficult to weld to the thermoplastic resin sheet 1, so it does not weld to each other, The thermoplastic resin sheet 1 is stretched along the surface of the core material body 51. In particular, when the temperature of the thermoplastic resin sheet 1 is higher than the melting point of the core material 5 when the thermoplastic resin sheet 1 comes into contact with the core material 5 (for example, polypropylene is selected as the thermoplastic resin sheet and expanded polystyrene is selected as the core material). In the case), when the core material 5 is pressed, the core material main body 51 in a portion in contact with the molten thermoplastic resin sheet 1 is melted, and this serves as a lubricant, so that the core material body 51 is stretched more smoothly.

  After the thermoplastic resin sheet 1 is stretched to some extent by the core material 5 or while the thermoplastic resin sheet 1 is stretched by the core material 5, the thermoplastic resin sheet 1 stretched by the core material 5 is molded as shown in FIG. The thermoplastic resin sheet 1 is molded along the cavity shape of the mold 3 by vacuum suction. By this vacuum forming, the cavity shape of the mold 3 is reliably transferred to the thermoplastic resin sheet 1.

  Similarly, the thermoplastic resin sheet 2 on the opposite side is also molded into the cavity shape of the mold 4 by vacuum suction. Since the thermoplastic resin sheet 2 on the opposite side does not have a deep-drawing shape, no thin wall or pinhole is generated even by molding only by vacuum suction.

  After the thermoplastic resin sheets 1 and 2 are formed into the cavities of the molds 3 and 4 by vacuum suction, the insertion material 52 of the core material 5 is pushed in as shown in FIG. It contacts with the plastic resin sheet 1. By inserting the insertion material 52 into the insertion hole 53, both end surfaces thereof are flush with the core material main body 51 and constitute a part of the joining surface with the thermoplastic resin sheets 1 and 2.

  Finally, as shown in FIG. 5, the molds 3 and 4 are clamped to integrate the thermoplastic resin sheets 1 and 2 and the core material 5 into a composite molded product. The molded composite molded product is completed by opening and removing the molds 3 and 4 and performing trimming or the like.

  The resulting composite molded article is of high quality without the occurrence of thin portions or pinholes in the thermoplastic resin sheets 1 and 2 as the skin material.

  For example, as shown in FIG. 9, when the thermoplastic resin sheet 1 is formed into a deep drawn shape by vacuum suction without being stretched by the core material 5, the stretched state of the thermoplastic resin sheet 1 in the deep drawn shape portion can be uneven, and the thin portion And pinholes are likely to occur. On the other hand, in the molding method of this embodiment, since the thermoplastic resin sheet 1 is stretched with the core material 5 in advance and then vacuum-sucked, the thermoplastic resin sheet 1 is evenly stretched to form a thin portion or a pinhole. Will not occur.

  Further, in the molding method of the present embodiment, the core material 5 and the thermoplastic resin sheets 1 and 1 are embedded in the core material 5 because the insert material 52 formed of a material that is easily welded to the core material 5 is embedded. 2 is also maintained, and a high-quality composite molded product can be obtained in this respect as well.

  As described above, according to the molding method of the present invention, even if the molded product has a deep-drawn shape, there is no occurrence of thin wall or pinhole in the thermoplastic resin sheet around the deep-drawn shape, It is possible to mold a high-quality composite molded article with a good bonding state between the thermoplastic resin sort and the core material.

  As mentioned above, although embodiment which applied this invention has been described, it cannot be overemphasized that this invention is not what is limited to the above-mentioned embodiment, In the range which does not deviate from the summary of this invention, a various change can be added. Is possible.

1, 2 Thermoplastic resin sheet 3, 4 Mold 5 Core material 51 Core material body 52 Insert material 53 Insert hole 54 Rib

Claims (4)

A molding method in which a core material is sandwiched between a pair of resin sheets and each resin sheet is closely attached to the mold by vacuum suction from the cavity surface, and then the mold is clamped and molded,
A molding method characterized in that at least one resin sheet is stretched by pressing a core material, and is then brought into close contact with a mold by vacuum suction.   The molding method according to claim 1, wherein the at least one resin sheet after molding has a deep drawing shape.   The core material includes a core material body formed of a material that is difficult to weld to the resin sheet, and an insert material that is formed of a material that is easily welded to the resin sheet and is inserted into a hole formed in the core material body. The molding method according to claim 1, wherein the molding method is configured.   The core material is pressed against the resin sheet with the insert material retracted from the contact surface with the resin sheet, the resin sheet is brought into close contact with the mold by vacuum suction, and then the insert material is pressed into contact with the resin sheet. The molding method according to claim 3, wherein:

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