JP2005231224A - Twin composite molding apparatus for thermoplastic resin molding and twin composite molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding apparatus which can produce a molding at low costs by efficiently controlling an air bank trace formed on the surface of a resin molding having an internal hollow part. <P>SOLUTION: In a twin composite molding apparatus for a thermoplastic resin molding, heater parts 2 and 2' for heating/softening resin sheets 1 and 1', molds 3 and 3', and sheet holding mechanism parts 5 and 5' for holding the resin sheets 1 and 1' are provided, and a compressed air needle 4 for injecting compressed air between the resin sheets 1 and 1' is arranged in one of the molds 3 and 3'. The heater parts 2 and 2', the molds 3 and 3', and the sheet holding mechanism parts 5 and 5' are housed in an airtight container 8. The sheet holding mechanism parts 5 and 5' hold the resin sheets 1 and 1' and form an airtight space 6. Pressure variable adjustment mechanisms are arranged in the airtight container 8 and the airtight space 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a twin composite molding apparatus and a twin composite molding method for a thermoplastic resin molded body, and in particular, efficiently controls softening sag during resin sheet heat softening and improves the adhesion between the molded body surface and the upper and lower mold cavity gaps. The present invention relates to a twin composite molding apparatus for a thermoplastic resin molded body capable of efficiently controlling the occurrence of air accumulation generated on the surface of the molded body and preventing contact and fusion in the upper and lower heater sections.

  When the resin material is applied to automobile parts, the resin parts are required to be lightweight, high in rigidity, and high in strength. As means for solving this problem, development of resin parts having hollow portions inside has been carried out. By providing the hollow portion inside the resin part, the rigidity and strength of the part can be improved while reducing the weight of the part. Conventionally, as a method for producing a resin molded body having a hollow portion, two resin sheets that face each other and are arranged in parallel in a mold are fixed in the periphery, and the resin sheet is preheated using a heat generator. After that, a compressed air molding method in which air is blown between a pair of resin sheets to inflate the inside and press-bond to the mold, or a suction port that can be evacuated is arranged on the inner wall surface of the mold cavity, and the resin sheet and the mold heated in advance A vacuum forming method in which the inner wall surface of a mold cavity is formed while being vacuumed, and a manufacturing method by a vacuum / pressure forming method that combines a pressure forming method and a vacuum forming method are known. Here, the vacuum / compression molding method, that is, the twin composite molding method (TCF method) is a method in which two thermoplastic resin sheets are heated and melted and compressed air is injected between the two resin sheets. This is a method of forming a part by shaping a resin sheet by sucking air from the pores provided in and closing the mold.

  For example, in a double sheet molding method, a synthetic resin hollow molded body having high reproducibility of the shape of a molded body, high strength of a joint, and capable of obtaining a large, wide area, flat plate shaped hollow molded body. As a molding method, at least one of the sheet holders is slid and a vacuum / pneumatic molding apparatus using a structure having a driving means for reducing the interval between the resin sheets (see Patent Document 1) or heat-softened into a molded product. 2. Description of the Related Art A vacuum forming apparatus (see Patent Document 2) that bonds a thermoplastic synthetic resin sheet to a molded product by vacuum heating is known.

JP 2003-276075 A JP 2002-67137 A

  However, in the conventional molding method, two resin sheets facing each other in advance are heated in advance, and then the mold cavity is evacuated while being narrowed by the upper and lower molds, and two heat-softened resin sheets are obtained. In the case of molding a single body or a plurality of hollow portions each having an opening for injecting compressed air on the front surface and / or the back surface, the molds are molded in two resin sheets. Depending on the evacuation speed in the cavity, the surface roughness of the mold cavity, or the cavity shape of the mold, an air pool (including fine irregularities on the resin sheet surface) is generated between the heat-softened resin sheets and molding is performed. There is a problem that the yield of goods cannot be raised. Further, in the insert molding method in which the hollow molded body is molded and decorated on the surface side of the molded product, the decorative sheet integrated with the molded product or the insert product and the heat-softened resin sheet, or gold There is a problem that an air pool or void occurs between the mold and the decorative sheet, and a good molded product cannot be obtained.

  In order to increase the evacuation speed when molding two resin sheets, the diameter or number of evacuation holes in the mold cavity is increased, or the surface roughness of the mold cavity is increased. There is a way to do it. Furthermore, a method for reducing the degree of freedom of the cavity shape of the mold, or a vacuum / pneumatic molding apparatus using a structure having a driving means for reducing the interval between the resin sheets by sliding at least one of the sheet holders (See Patent Document 1), there is a method of increasing the shaping speed of the heat-softened resin sheet into the mold cavity.

  However, with these methods, many traces of vacuum holes remain in the molded product, the surface roughness of the mold cavity is transferred to the surface of the molded product, and the appearance quality of the molded product is impaired. However, the degree of freedom in shape design is reduced because the degree is lowered. In addition, in molding when there is a decorative sheet or insert product, if the shaping speed of the heat-softened resin sheet in the mold cavity is increased, the yield of molded products without air accumulation cannot be improved. It was.

  In insert molding, the decorative sheet or insert product is laid out by removing it from the position of the vacuum drawing hole in the mold cavity, or the decorative sheet or insert product is laid out at the same position as the vacuum drawing hole in the mold cavity. There is a method of preventing air accumulation generated between the decorative sheet or insert product and the heat-softened resin sheet or between the mold and the decorative sheet by processing and laying out. Further, there is a method in which a thermoplastic synthetic resin sheet softened by heating in a subsequent process is vacuum-bonded to a molded product (see Patent Document 2).

  However, in these methods, there is a problem in that there is a limitation on a portion to be decorated, and a hole processing trace remains at the position of the vacuum drawing hole, thereby deteriorating the appearance quality of the molded product. In addition, there is a problem that the product cost becomes high in the decoration method by the post-process.

  This invention is made | formed in view of such a situation, and the molded object surface and decoration of the resin molding which has a hollow part inside, or the molding by which decoration or insert was given to this resin molding Improve the adhesion of the surface or the gap between the decorative sheet or insert part and the thermoplastic resin sheet, and air pocket marks generated on the surface, or the gap between the decorative sheet or insert product and the thermoplastic resin sheet An object of the present invention is to provide a molding apparatus and a method for molding a thermoplastic resin molded body that can efficiently control the occurrence of air accumulation and can produce a decorative molded product at low cost.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the upper and lower heater parts, the upper and lower molds, and the sheet holding mechanism part of the twin composite molding apparatus are stored in an airtight container, and further, the sheet holding mechanism part. Has found that the above-mentioned problems can be solved by fixing a pair of upper and lower resin sheets to form an airtight space, and a mechanism for positively controlling the pressure of the airtight container and the airtight space. It came to be completed.

That is, the twin composite molding apparatus of the thermoplastic resin molding of the present invention according to claim 1 includes a pair of upper and lower heater portions for heating and softening a pair of upper and lower resin sheets made of thermoplastic resin, and a heat-softened resin. The pair of upper and lower molds for forming the sheet by narrowing the sheet, and a sheet holding mechanism portion for holding the resin sheet, and the pair of resin sheets heated and softened to one of the upper and lower pair of molds A twin composite molding apparatus for a thermoplastic resin molded body in which a compressed air needle for injecting compressed air is disposed,
The pair of upper and lower heater sections, the pair of upper and lower molds, and the sheet holding mechanism section are stored in an airtight container, and the sheet holding mechanism section holds the pair of upper and lower resin sheets to form an airtight space. And the airtight container and the airtight space are provided with a pressure variable adjusting mechanism.

  Next, the molding apparatus according to claim 2 further includes a circuit for equalizing the pressure in the hermetic container and the hermetic space.

  Next, the molding apparatus according to claim 3 further detects the softening droop of the resin sheet during heating of the pair of upper and lower resin sheets by an external signal, and can adjust the pressure in the hermetic container. An adjustment mechanism is provided, and the pressure in the hermetic container is controlled by the softening droop adjustment mechanism.

  Next, the molding apparatus according to claim 4 is characterized in that the external signal is detected by an optical signal or image processing.

  Next, the molding apparatus according to claim 5 further includes a mechanism capable of evacuation in the cavities of the pair of upper and lower molds.

  Moreover, the twin composite molding method of the thermoplastic resin molded body of the present invention described in claim 6 uses the twin composite molding device according to any one of claims 1 to 5, and the airtight container and the The airtight space is evacuated or isobaric evacuated, and then the pair of upper and lower resin sheets are heated and softened, and then the heat and softened resin sheet is narrowed by the pair of upper and lower molds, and then the airtight container is filled. After adjusting the pressure, the compressed air needle is inserted between the pair of resin sheets to inject compressed air, and the resin sheet is shaped into a mold.

  Next, the molding method according to claim 7 is characterized in that the pressure in the airtight container and the airtight space is made equal by evacuation of the airtight container and the airtight space.

  Next, in the molding method according to claim 8, after the resin sheet is heat-softened, the pressure of the airtight space is adjusted to preheat the heat-softened resin sheet, and then the resin sheet is formed with the mold. It is characterized by narrow pressure.

  Next, the molding method according to claim 9 is a process in which the heat-softened resin sheet is shaped into a mold or, after shaping, the inside of the mold cavity is evacuated to heat-soften the resin sheet. Is sucked into the mold.

  Next, the molding method according to claim 10 is characterized in that a decorative sheet is arranged on at least one of the pair of upper and lower forming molds to perform decorative molding.

  According to the present invention, the upper and lower heater parts, the upper and lower molds, and the sheet holding mechanism part of the twin composite molding apparatus are stored in an airtight container, and the pair of upper and lower resin sheets are fixed by the sheet holding mechanism part to form an airtight space. By forming and forming a mechanism that positively controls the pressure of the hermetic container and the hermetic space, the shape of the surface of the hollow molded body having a hollow portion and the decorative hollow molded body is improved, and the hollow It eliminates voids in the molded body, air accumulation marks between the surface of the hollow molded body and the mold, and air accumulation marks in the gap between the decorative sheet and the resin sheet, improving appearance quality and reducing molding costs. A twin composite molding apparatus for a thermoplastic resin molded body and a twin composite molding method for a thermoplastic resin molded body using the apparatus can be provided.

  Hereinafter, the twin composite molding apparatus and molding method for a thermoplastic resin molding of the present invention will be described in more detail. Such a twin composite molding apparatus for a thermoplastic resin molded body includes a pair of upper and lower heater parts for heating and softening a pair of upper and lower resin sheets made of a thermoplastic resin, and forming the heat softened resin sheet by narrowing the pressure. A pneumatic needle comprising a pair of upper and lower molds and a sheet holding mechanism for holding the resin sheet, and for injecting compressed air between the pair of resin sheets heated and softened to one of the pair of upper and lower molds Is a twin composite molding apparatus for a thermoplastic resin molded body, wherein the pair of upper and lower heater parts, the pair of upper and lower molding dies, and the sheet holding mechanism part are stored in an airtight container, and The sheet holding mechanism portion holds the pair of upper and lower resin sheets to form an airtight space, and the airtight container and the airtight space are provided with a pressure variable adjustment mechanism. That.

  In other words, the twin composite molding apparatus according to the present invention includes a sheet holding mechanism portion that holds a peripheral portion of a pair of upper and lower resin sheets facing each other to form an airtight space, and an upper portion that is positioned above the sheet holding mechanism portion. All of the heater part and the lower heater part positioned below, the upper mold located above the upper heater part, and the lower mold located below the lower heater part are stored in an airtight container, A pneumatic needle for injecting pressurized air into the hermetic space is disposed in one of the upper mold and the lower mold, and includes a pressure adjusting mechanism for adjusting the pressure in the hermetic container and the pressure in the hermetic space. Here, the twin composite molding apparatus of the present invention preferably includes a pressure adjusting mechanism capable of making the pressure in the airtight container and the pressure in the airtight space equal.

  The twin composite molding apparatus of the present invention further detects softening sag during heating of the upper and lower resin sheets from an external signal, and a softening sag adjustment mechanism capable of adjusting pressure in the hermetic container, A mechanism for controlling the pressure is preferably provided. Here, it is more preferable to detect the external signal by an optical signal or image processing.

  The twin composite molding apparatus of the present invention preferably further comprises a mechanism capable of evacuation in the cavity of the upper and lower molding dies.

  Here, the twin composite molding apparatus and molding method for a thermoplastic resin molded body of the present invention will be described in more detail with reference to FIGS. 1 shows a resin sheet setting process, FIG. 2 shows an airtight container and an isobaric circuit of an airtight space, FIG. 3 shows a resin sheet heating start process, and FIG. 4 shows a resin sheet pretension process. FIG. 5 shows the process of narrow-pressure molding of the resin sheet, FIG. 6 shows the process of taking out the hollow molded body, FIG. 7 shows the molded body after trimming, and FIG. 8 shows the setting process of the resin sheet and the decorative sheet. FIG. 9 shows the narrow pressure forming process of the resin sheet and the decorative sheet, and FIG. 10 shows the decorative hollow molded body after trimming.

  In FIG. 1, the molding apparatus includes an upper heater portion 2 that heat-softens the upper resin sheet 1, a lower heater portion 2 ′ that heat-softens the lower resin sheet 1 ′, an upper molding die 3, and a lower molding die 3 ′. The upper mold 3 is provided with a pneumatic needle 4 capable of injecting pressurized air between the heat-softened resin sheets 1 and 1 ′. The illustrated example shows a case where the evacuation holes are not formed in the cavities of the upper mold 3 and the lower mold 3 '. Moreover, in FIG. 1, although the pneumatic needle 4 is installed in the upper shaping | molding die 3, the aspect which installed the pneumatic needle 4 in the lower shaping | molding die 3 'is also one embodiment of this invention.

  Next, the upper resin sheet 1 and the lower resin sheet 1 ′ are all placed so that the space between the upper resin sheet 1 and the lower resin sheet 1 ′ becomes an airtight space 6 by the sheet holding mechanism portions (holders) 5 and 5 ′. The circumference is clamped, and at least one of the sheet holding mechanism portions (holders) 5 and 5 ′ is connected to a vacuum pump capable of introducing the medium into the airtight space 6 between the upper resin sheet 1 and the lower resin sheet 1 ′. In addition, a pressure holding valve 7 is installed, and the upper heater portion 2 and the lower heater portion 2 ′, the upper molding die 3 and the lower molding die 3 ′, and the upper resin sheet 1 and the lower resin sheet 1 ′ are clamped. The entire mechanism parts (holders) 5 and 5 ′ are accommodated in an airtight container 8, and a pressure adjustment valve 7 ′ connected to a pressure reducing pump capable of adjusting an internal pressure is installed in the tight container 8. Therefore, the pressure of the airtight space 6 between the upper resin sheet 1 and the lower resin sheet 1 ′ and the pressure of the airtight container 8 are controlled to be equal by adjusting the pressure regulating valves 7 and 7 ′ connected to the decompression pump. Accordingly, the dripping phenomenon due to heat softening of the upper resin sheet 1 and the lower resin sheet 1 ′, or the contact between the upper resin sheet 1 and the lower resin sheet 1 ′ due to the pressure difference between the resin sheet holding mechanism portions 5 and 5 ′ is controlled. It is possible.

  Further, the apparatus shown in FIG. 2 can be used as a circuit for equalizing the pressure in the airtight container 8 and the airtight space 6. This apparatus uses a line connected to the pressure reducing pump as one place of the pressure regulating valve 7 ′, and evacuates the line of the pressure regulating valve 7 and the line of the pressure regulating valve 7 ′ in parallel through the pressure regulating valve 7 ″. Therefore, the pressure in the airtight container 8 and the airtight space 6 can be adjusted to be equal.

  Furthermore, between the lower resin sheet 1 ′ and the lower heater portion 2 ′, the positions where the sensors 9 and 9 ′ that detect the softening droop that occurs when the resin sheet is softened by heating are not in contact with the lower heater portion 2 ′. Is installed. Therefore, control can be performed so that the process can proceed to the next process before the lower resin sheet 1 'and the lower heater portion 2' are brought into contact with each other. Representative sensors 9 and 9 'include a transmission type, a reflection type, or a retro-reflection type of a photoelectric sensor using infrared light, laser light, etc., which can be detected and controlled by image processing using a camera or the like. Good.

  In addition, as a method for heating the resin sheets 1 and 1 'to the softening temperature or higher, a heating method using a far-infrared heater having a maximum energy wavelength in the vicinity of 4 μm, a short wavelength or medium wavelength heater having a maximum energy wavelength in the vicinity of 1 μm to 3 μm. And an indirect heating method. In general, a heating method using a far infrared heater in which the output wavelength of the heater and the absorption wavelength of the resin substantially coincide is preferable.

  FIG. 3 shows a state where heating of the upper resin sheet 1 and the lower resin sheet 1 ′ is started by the upper heater part 2 and the lower heater part 2 ′. At this time, the pressure regulating valves 7 and 7 'connected to the decompression pump are opened and are at the same pressure as the atmospheric pressure. At this time, heating may be started by the upper heater unit 2 and the lower heater unit 2 ′ in advance while adjusting the pressure adjusting valves 7 and 7 ′ so that the hermetic container 8 and the hermetic space 6 become equal in pressure with a decompression pump. Is possible. Preferably, heating is performed at atmospheric pressure. Note that the gastight container 8 and the airtight space 6 can be filled with a general gas in advance. Typical examples of such gas include air, nitrogen, carbon dioxide gas and the like. Nitrogen gas is preferred.

  In FIG. 4, the pressure regulating valves 7 and 7 ′ are adjusted so that the upper resin sheet 1 and the lower resin sheet 1 ′ reach the heat softening temperature condition and the hermetic container 8 and the hermetic space 6 become equal pressure by the decompression pump. Then, after the pressure reduction is completed, the upper resin sheet 1 and the lower resin sheet 1 ′ are pretensioned while adjusting the pressure adjusting valve 7 to release the pressure of the airtight space 6 to the atmosphere. In this step, the pressure reduction after reaching the heat softening temperature condition may be controlled by controlling the upper resin sheet 1 and the lower resin sheet 1 ′ to a pressure capable of forming the upper mold 3 and the lower mold 3 ′. Preferably, the pressure is controlled to 400 hPa or less. In addition, it is possible to use general gas for decompression in the airtight space 6. Typical examples of such gas include air (atmosphere), nitrogen, and carbon dioxide. Nitrogen gas is preferred.

  In FIG. 5, after the upper resin sheet 1 and the lower resin sheet 1 ′ reach the heat softening temperature condition and are pre-tensioned, the upper heater portion 2 and the lower heater portion 2 ′ recede and heat soften the upper resin sheet 1. The upper resin sheet 1 'and the lower resin sheet 1' are pressed into the upper and lower mold cavities by pressing the lower resin sheet 1 'with the upper mold 3 and the lower mold 3'. Further, the pressure adjusting valves 7 and 7 ′ are adjusted to the atmospheric pressure, and the pressure needle 4 formed in the cavity from the upper part of the upper mold 3 which is narrowed while releasing the pressure of the airtight container 8 to the atmosphere is the upper resin sheet 1. The compressed air is injected into the hollow portion 10. Typical examples of such gas include air (atmosphere), nitrogen, and carbon dioxide. Nitrogen gas is preferred.

  In FIG. 6, after the molding is completed, the upper mold 3 and the lower mold 3 ′ are opened, the pneumatic needle 4 is retracted, and the hollow molded body 11 is formed and taken out in the sheet holding mechanism portions 5 and 5 ′. The state is shown.

  Here, as the structure of the mold, it is preferable to process a vacuum suction port on the cavity surface where the front surface and the back surface of the hollow molded body 11 shown in FIG. 6 are formed. Since the shape of the suction port is transferred to the surface of the hollow molded body 11, a desired number may be processed at a location corresponding to the corner portion or the concave portion of the hollow molded body 11, and the hole diameter is preferably 1 mm or less. . Examples of the mold material include ferrous, non-ferrous metals, ceramics, and thermosetting resin materials.

  FIG. 7 shows a state where the hollow molded body 11 having the hollow portion 10 is trimmed.

  As described above, according to the twin composite molding apparatus of the present invention for molding a hollow molded body from a pair of resin sheets, the softening sagging during the heat softening of the resin sheet is efficiently controlled, and the surface of the molded body and the upper and lower mold cavities are controlled. It is possible to improve the adhesion of the gaps, efficiently control the occurrence of air accumulation on the surface of the molded body, and prevent contact and fusion in the upper and lower heater sections.

  When a decorative sheet or insert product is installed in the mold, an example of a molding method using the decorative sheet 12 is added to the inside of the lower mold 3 ′ in the molding apparatus as shown in FIG. The decorative molded body 13 shown in FIG. 10 can be obtained by arranging the decorative sheet 12 and carrying out the molding of FIG.

  Also in the above decorative molding, according to the twin composite molding apparatus of the present invention that molds a decorative hollow molded body from a pair of resin sheets as shown in FIGS. Efficiently controls and improves the adhesion of the gap between the molded body surface and the upper and lower mold cavities and the decorative surface, and the adhesion of the gap between the decorative sheet and the thermoplastic resin sheet, and occurs on the decorative molded product surface. It is possible to efficiently control the occurrence of air accumulation marks and air accumulation in the gap between the decorative sheet and the thermoplastic resin sheet, and to prevent contact and fusion in the upper and lower heater portions.

  In the aspect in which the decorative sheet or the insert product which is one of the embodiments of the present invention described above is installed in the molding die, including the case where the place where the decorative sheet and the insert product are installed is inverted upside down. As the mold structure, it is preferable to process a suction port that can be evacuated on the cavity surface where the front and back surfaces of the hollow molded body 11 shown in FIG. 6 are formed. Since the shape of this suction port is transferred to the surface of the hollow molded body 11, a desired number of suction ports are provided at locations corresponding to the corners or recesses of the hollow molded body 11 and further at locations for holding decorative sheets or inserts. The hole diameter is preferably 1 mm or less.

  Here, the resin sheet material that can be molded with the above-described mold will be described. As a raw material resin for forming such a molded body, that is, a resin of a resin sheet, any thermoplastic resin that softens when heated can be applied. For example, polyolefin resins such as polyethylene and polypropylene, polystyrene, polycarbonate, acrylonitrile / styrene / butadiene Examples of the present invention include block copolymers, general thermoplastic resins such as nylon, ethylene / propylene block copolymers, thermoplastic elastomers such as styrene / butadiene block copolymers, and polymer alloys thereof. The resin for the resin sheet includes all of them.

  Further, in such a resin sheet, a nanocomposite in which various fillers such as talc and glass fiber, or a fine particle material on the order of several tens of nm much smaller than the wavelength of visible light (380 to 770 nm) is blended. It may be a material. Incidentally, clay, talc, silica, etc. are mentioned as a fine particle material. Various commonly used additives such as pigments, lubricants, antistatic agents and antioxidants may be blended.

  Next, in the decorative sheet, it is possible to arrange a material having good adhesion to the thermoplastic resin or a material having an adhesive function on the adhesive surface. When using a coating film as a decorating sheet, as an example of the coating film, there may be mentioned one configured by laminating a coating film having an acrylic resin composition as a clear layer and a resin base material. Since the acrylic resin composition is transparent, it can be used, for example, as a clear coating film for automobile outer panels.

  Moreover, it is preferable that the said coating film consists of the said clear layer, a colored layer, and a backing material layer, and is integrally molded. Further, the coating film may be produced by laminating the clear layer, the acrylic colored layer, and the backing material in this order, and may be manufactured by melt multilayer extrusion film molding or heat lamination molding, or the clear layer, colored film, and backing material. They may be laminated in order and formed into a film by thermal lamination molding.

  On the other hand, the material having good adhesiveness may be appropriately selected and used from the well-known thermosetting resin-based or thermoplastic resin-based decorative sheet, and has an adhesive function. The material may be appropriately selected from known adhesives.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in full detail, this invention is not limited by this.

1) Mold Die As shown in FIG. 1, the mold structure is composed of a pair of an upper mold 3 and a lower mold 3 ′. The mold material is made of aluminum (ZAS), no vacuum suction hole is provided in the cavity, the cavity size for forming the hollow molded body is 150 × 150 × 105 mm, and the space height of the hollow part of the hollow molded body Was about 100 mm.

2) Molding of hollow molded body As shown in FIG. 1, the upper heater part 2 and the lower heater part 2 ′ for heating and softening the upper resin sheet 1 and the lower resin sheet 1 ′, and the upper mold 3 and the lower mold 3 ′ In addition, the upper mold 3 is provided with a compressed air needle 4 capable of injecting compressed air between the heat-softened resin sheets 1 and 1 ′. Note that far-infrared heaters were used for the upper heater portion 2 and the lower heater portion 2 ′.

  Next, the upper resin sheet 1 and the lower resin sheet 1 ′ are all placed so that the space between the upper resin sheet 1 and the lower resin sheet 1 ′ becomes an airtight space 6 by the sheet holding mechanism portions (holders) 5 and 5 ′. The circumference is clamped, and at least one of the sheet holding mechanism portions (holders) 5 and 5 ′ is connected to a vacuum pump capable of introducing the medium into the airtight space 6 between the upper resin sheet 1 and the lower resin sheet 1 ′. In addition, a pressure holding valve 7 is installed, and the upper heater portion 2 and the lower heater portion 2 ′, the upper molding die 3 and the lower molding die 3 ′, and the upper resin sheet 1 and the lower resin sheet 1 ′ are clamped. The entire mechanism parts (holders) 5 and 5 ′ are accommodated in an airtight container 8, and a pressure adjustment valve 7 ′ connected to a pressure reducing pump capable of adjusting an internal pressure is installed in the tight container 8. Therefore, by adjusting the pressure of the airtight space 6 between the upper resin sheet 1 and the lower resin sheet 1 ′ and the pressure of the airtight container 8 to the equal pressure by adjusting the pressure adjusting valves 7 and 7 ′ connected to the pressure reducing pump, It is possible to control the dripping phenomenon due to heat softening of the resin sheet 1 and the lower resin sheet 1 ′, or the contact between the upper resin sheet 1 and the lower resin sheet 1 ′ due to the pressure difference between the resin sheet holding mechanism portions 5 and 5 ′.

  Further, between the lower resin sheet 1 ′ and the lower heater portion 2 ′, sensors 9 and 9 ′ for detecting softening sag generated when the resin sheet is heated and softened are installed at positions where they do not contact the lower heater portion 2 ′. Has been. Therefore, control can be performed so that the process can proceed to the next process before the lower resin sheet 1 'and the lower heater portion 2' are brought into contact with each other. The pressure regulating valves 7 and 7 'connected to the decompression pump are opened and are at the same pressure as the atmospheric pressure.

  Next, as shown in FIG. 3, heating of the upper resin sheet 1 and the lower resin sheet 1 'was started by the upper heater part 2 and the lower heater part 2'. The upper heater portion 2 and the lower heater portion 2 ′ were heated and held at 800 ° C. as a temperature for rapidly heating the upper resin sheet 1 and the lower resin sheet 1 ′.

  Next, after the heating of the upper resin sheet 1 and the lower resin sheet 1 ′ is completed, the pressure of the airtight space 6 and the airtight container 8 is adjusted to be equal to or less than 400 hPa by the pressure adjusting valves 7 and 7 ′ connected to the pressure reducing pump. Then, as shown in FIG. 4, the upper resin sheet 1 and the lower resin sheet 1 ′ were pretensioned while adjusting the pressure adjusting valve 7 to release the pressure in the airtight space 6 to the atmosphere.

  Next, as shown in FIG. 5, the upper heater part 2 and the lower heater part 2 ′ are retracted, and the heat-softened upper resin sheet 1 and lower resin sheet 1 ′ are narrowed by the upper mold 3 and the lower mold 3 ′. Further, while the pressure regulating valves 7 and 7 ′ are opened, the compressed air needle 4 formed in the cavity is inserted into the upper resin sheet 1 from the upper part of the narrowed upper mold 3, and 0. A pressurized air of 5 MPa was injected, and after completion of cooling, a decorated hollow molded body 13 of FIG. 10 was obtained.

  As the upper and lower resin sheet materials, polycarbonate resin sheet [Iupilon sheet NF-2000 (manufactured by Mitsubishi Engineering Plastics)] plate thickness 3 mm and acrylic resin sheet [Acrylite L (manufactured by Mitsubishi Rayon)] plate thickness 3 mm are used for decoration. As the sheet, an AVLOY dry paint film (Mitsubishi Chemical MKV) in which a clear layer, an acrylic colored layer, and a backing material are laminated in this order as a coating film using an acrylic resin composition was used.

(Examples 1-8)
As shown in FIGS. 1 to 10, the upper and lower heater parts, the upper and lower molds, and the sheet holding mechanism part of the twin composite molding apparatus are stored in an airtight container, and the decorative sheet is not interposed in the lower mold. In each case, after the temperature at the center of the plane of the upper resin sheet reaches the set value, the pressure of the airtight space and the airtight container is adjusted to be equal to each other, and after pretensioning, the upper resin sheet softened by heating and the lower The resin sheet was narrowly pressed by the upper mold and the lower mold to obtain the hollow molded body shown in FIGS. Table 1 shows the evaluation results of the formability of the hollow molded body, the voids of the hollow molded body, the air pocket marks between the surface of the hollow molded body and the mold, and the air pocket marks in the gap between the decorative sheet and the resin sheet.

(Comparative Examples 1-4)
Using the same resin sheet molding apparatus as the embodiment shown in FIGS. 1 to 10, an upper and lower molding die in which a vacuum drawing hole capable of being evacuated is processed is used, and this vacuum drawing hole becomes a molded product of the cavity. For each of the cases where the corner portion is arranged at φ1 mm and the interval is 30 mm, and the decorative sheet is not interposed in the lower mold and the case where it is interposed, the planar center temperature of the upper resin sheet reaches the set value, and then the airtight space is formed. After adjusting the pressure of the airtight container while keeping the atmospheric pressure open and pre-tensioning, the upper and lower resin sheets softened by heating are narrowed by the upper mold and the lower mold, and the vacuum is provided in the cavity when the pressure is narrow After molding while sucking from the pull hole, the hollow molded body of FIGS. 7 and 10 was obtained. Table 2 shows the evaluation results of the formability of the hollow molded body, voids of the hollow molded body, air accumulation marks between the surface of the hollow molded body and the mold, and air retention marks in the gap between the decorative sheet and the hollow molded body. .

3) Performance evaluation Tables 1 and 2 show the evaluation results of the hollow molded body obtained in each example. Each performance was measured and evaluated by the following methods.

<Shaping property of hollow molded body>
The appearance of the flat portion and the R portion of the hollow molded body was visually observed. When the shape of the mold cavity was correctly reflected in the appearance of the hollow molded body, the symbol was marked as “good”, and when it was not reflected, it was marked as “x”.

<Void of hollow molded body>
Voids (bubbles) generated on the front surface or the back surface of the hollow molded body were visually observed. When there was no void, the symbol was marked as “good”, and when a void was generated, it was marked as “x”.

<Air trap marks between the surface of the hollow molded body and the mold>
Air trap marks generated between the molds on the front or back surface of the hollow molded body were visually observed. When there was no air stagnation mark, the symbol was marked as “good”, and when the air stagnation mark was generated, it was displayed as “x”.

<Air trap marks in the gap between the decorative sheet and the resin sheet>
The air accumulation trace which generate | occur | produced in the clearance gap between the decorating sheet and hollow molded object in the decorating surface of a hollow molded object was observed visually. When there was no air stagnation mark, the symbol was marked as “good”, and when the air stagnation mark was generated, it was displayed as “x”.

<Comprehensive judgment>
When all of the evaluation results of the formability of the hollow molded body, the void of the hollow molded body, the air accumulation trace between the surface of the hollow molded body and the mold, and the air accumulation trace in the gap between the decorative sheet and the resin sheet are good The symbol is indicated by ◯, and when any of them is defective, it is indicated by ×.

  As is apparent from Tables 1 and 2, the hollow molded body and the decorative hollow molded body molded using the thermoplastic resin molded apparatus that is a preferred embodiment of the present invention have a formability of the hollow molded body. Good, no voids in the hollow molded body, no air accumulation trace between the surface of the hollow molded body and the mold, no air accumulation trace in the gap between the decorative sheet and the resin sheet, the appearance quality is excellent, and the molding method jumps It can be seen that there is an improvement.

  The preferred embodiments and examples of the present invention have been described in detail above. However, the present invention is not limited to these, and various modifications are possible within the scope of the present invention. For example, in the present specification, “upper” and “lower” are equivalent to each other, and both are replaced with each other.

  Further, the above molding method is used as an automobile part, and a resin glass part such as a window shield, a side glass, a bag door glass, and a sunroof, or an automobile resin outer plate such as a roof panel, and further, an automobile back door and a side door It can also be applied to molding and the like.

The setting process of a resin sheet is shown. Fig. 2 shows an isobaric circuit of an airtight container and an airtight space. The heating start process of a resin sheet is shown. The pre-tension process of a resin sheet is shown. The narrow pressure molding process of a resin sheet is shown. The hollow molded object taking-out process is shown. The molded product after trimming is shown. The setting process of a resin sheet and a decoration sheet is shown. The narrow pressure forming process of a resin sheet and a decorative sheet is shown. The decorated hollow molded body after trimming is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper resin sheet 1 'Lower resin sheet 2 Upper heater part 2' Lower heater part 3 Upper molding die 3 'Lower molding die 4 Pneumatic needle 5, 5' Seat holding mechanism part 6 Airtight space 7, 7 ', 7 "Pressure adjustment Valve 8 Airtight container 9, 9 'Sensor 10 Hollow portion 11 Hollow molded body 12 Decorated sheet 13 Decorated hollow molded body

Claims (10)

A pair of upper and lower heater portions for heating and softening a pair of upper and lower resin sheets made of a thermoplastic resin, a pair of upper and lower molds for narrowing and shaping the heat-softened resin sheet, and holding the resin sheet And a twin composite of a thermoplastic resin molded body in which a compressed air needle for injecting compressed air between the pair of heat-softened resin sheets is disposed on one of the upper and lower pair of molds. A molding device,
The pair of upper and lower heater sections, the pair of upper and lower molds, and the sheet holding mechanism section are stored in an airtight container, and the sheet holding mechanism section holds the pair of upper and lower resin sheets to form an airtight space. A twin-composite molding apparatus for a thermoplastic resin molded body, wherein the hermetic container and the hermetic space are provided with a pressure-variable adjusting mechanism.   The twin composite molding apparatus for a thermoplastic resin molded body according to claim 1, further comprising a circuit for equalizing the pressure in the hermetic container and the hermetic space.   Furthermore, the softening sag of the resin sheet at the time of heating the pair of upper and lower resin sheets is detected by an external signal, and includes a softening sag adjusting mechanism capable of adjusting the pressure in the hermetic container, and by the softening sag adjusting mechanism, The twin composite molding apparatus for thermoplastic resin molding according to claim 1 or 2, wherein the pressure in the hermetic container is controlled.   4. The twin composite molding apparatus for a thermoplastic resin molding according to claim 3, wherein the external signal is detected by an optical signal or image processing.   The twin composite molding apparatus for a thermoplastic resin molded body according to claim 1, further comprising a vacuum capable mechanism in the cavities of the pair of upper and lower molding dies.   Using the twin composite molding apparatus according to any one of claims 1 to 5, the airtight container and the airtight space are evacuated or isobaric evacuated, and then the pair of upper and lower resin sheets are After heat-softening, the heat-softened resin sheet is narrowed by the pair of upper and lower molds, and after adjusting the pressure in the airtight container, the pressure needle is inserted between the pair of resin sheets to inject pressure air And a method for twin composite molding of a thermoplastic resin molding, wherein the resin sheet is shaped into a molding die.   7. The twin composite molding method for a thermoplastic resin molded body according to claim 6, wherein the pressure in the airtight container and the airtight space is made equal by evacuation of the airtight container and the airtight space.   8. The resin sheet is narrowed with the mold after the resin sheet is heat-softened, the pressure in the airtight space is adjusted to preheat the heat-softened resin sheet. The twin composite molding method of the thermoplastic resin molding as described.   A process of shaping the heat-softened resin sheet into the mold or after shaping, the cavity of the mold is evacuated, and the heat-softened resin sheet is sucked into the mold A twin composite molding method for a thermoplastic resin molded article according to any one of claims 6 to 8.   The twin composite molding method for a thermoplastic resin molded body according to any one of claims 6 to 9, wherein a decorative sheet is arranged on at least one of the pair of upper and lower molds.

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