JP2003220643A - Apparatus and method for molding hollow body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mold a hollow-body molded article of which the joining strength between paired thermoplastic resin sheets is high and wherein no insert exists. <P>SOLUTION: In a hollow body molding apparatus 10, the paired thermoplastic resin sheets 20 disposed across a space to form a closed space 31 in between are molded into a hollow molded body. On the occasion when the paired resin sheets softened by heating are contact-bonded under pressure by pressing molds 40, pressing is conducted in the initial stage thereof not by the pressing surfaces of the mold, but by push guides 45 provided on the pressing surfaces, in this hollow body molding apparatus. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow body molding apparatus and a hollow body molding method, and more particularly, to a hollow body in which a pair of thermoplastic resin sheets are arranged so as to form a closed space. TECHNICAL FIELD The present invention relates to a hollow body molding device and a hollow body molding method for molding.

[0002]

2. Description of the Related Art Automobile parts made of resin materials are required to be lightweight and have high rigidity and high strength. In order to meet this demand, resin parts having a hollow part have been developed. This is because when the hollow portion is provided in the resin component, the resin component can be made lighter and the rigidity and strength of the resin component can be improved. Conventionally, there are the following four methods for producing a hollow body using a thermoplastic resin.

First, in the first compressed air forming method, two pairs of thermoplastic resin sheets are made to face each other so that a predetermined closed space is formed between the resin sheets. Then, the peripheral portions of both resin sheets are fixed. Then, these resin sheets are heated and softened by a heater, and the inside of the fixed peripheral edge portion is sandwiched by a pair of upper and lower molds. Next, a compressed air pipe is inserted into the resin sheet, compressed air is injected into the closed space, and the resin sheet which has been softened by heating is expanded in the mold cavity and brought into close contact with the inner wall of the mold.

In the second vacuum forming method, a suction port for vacuuming is arranged on the inner wall surface of the mold cavity instead of inflating the resin sheet by using a pressure forming device as in the pressure forming method. This is a method in which the air in the mold cavity is evacuated from the suction port to bring the heat-softened resin sheet into close contact with the inner wall surface of the mold cavity.

The third vacuum pressure forming method is a method in which the above-mentioned pressure forming method and vacuum forming method are used in combination, and the resin sheet is inflated in the mold cavity and at the same time air in the mold cavity is blown. This is a method of drawing a vacuum and bringing the heat-softened resin sheet into close contact with the inner wall surface of the mold cavity.

The fourth blow molding method is a generally used method, in which a heated cylindrical high-viscosity resin material is lowered from above and sandwiched by a mold to produce a hollow body. Is the method.

[0007]

However, in the above-mentioned conventional hollow body molding method, one set of two thermoplastic resin sheets is heated in advance and the inside of the peripheral edge portion of the two thermoplastic resin sheets is set. Since it was sandwiched between molds, if the parts are large and the area and dimensions are large,
Since the thermoplastic resin sheet softened by heating easily hangs down by its own weight, in order to prevent fusion of both resin sheets, the closed space of the thermoplastic resin sheets must be widened. As a result, the pressurization time from the contact of the mold to the inside of the peripheral edge of the two resin sheets to the completion of the pressing of the mold becomes longer as the closed space is expanded,
The temperature lowering from the heat softening temperature of the resin sheet is likely to proceed, and there is a possibility that the joint strength between the two resin sheets may be insufficient in joint strength.

As one method for solving this problem, when the pressing is completed, the heating softening temperature of the thermoplastic resin sheets is increased so that the two thermoplastic resin sheets are bonded with a desired bonding strength. There is a way. However, when the heating and softening temperature is increased, voids are easily generated in the thermoplastic resin sheet, or due to decomposed gas of the thermoplastic resin sheet, many pinhole-shaped spots are formed on the mold pressure surface. Occurs, which causes a new problem that the appearance of the hollow body molded article is significantly impaired.

Further, in the case of blow molding, since it is necessary to use a high-viscosity resin material, when a general-purpose resin material is used, the resin material extends due to its own weight to form a thin portion,
There is a problem that this reduces the dimensional accuracy and strength of the parts.

The present invention has been made in order to solve the above-mentioned conventional problems, and forms a hollow body molded product having a high bonding strength between a pair of thermoplastic resin sheets and no insert. An object of the present invention is to provide a hollow body molding apparatus and a hollow body molding method that can be performed.

[0011]

[Means for Solving the Problems] In order to solve the above problems,
In order to achieve the object, the hollow body molding apparatus according to the invention according to claim 1 is a hollow body for molding a pair of thermoplastic resin sheets with a space therebetween so as to form a closed space. In the body forming apparatus, an expandable and contractible pressure adjusting means is provided on the press surface of the mold for press-bonding the pair of resin sheets, and the resin sheet is not the press surface at the initial stage of pressurizing the resin sheet. It is characterized in that the pressure is adjusted by the pressure adjusting means.

A hollow body molding apparatus according to a second aspect of the present invention is a hollow body molding apparatus for molding a pair of thermoplastic resin sheets into a hollow molded body, wherein each of the pair of resin sheets is separated by a space. A holder that is fixed to form a closed space between the pair of resin sheets, a mold that press-bonds the heat-softened pair of resin sheets, and the pair of resin sheets are formed in the mold. Shaping means for shaping into the shape of a cavity, and a pressing surface for pressing the pair of resin sheets in the final stage of pressurization is formed in the mold, and the pressing surface is It is characterized in that the resin sheet is provided with a protruding pressure adjusting means for expanding and contracting according to a pressing force for pressurizing the resin sheet in an initial stage of pressurization.

A hollow body molding apparatus according to a third aspect of the present invention is the hollow body molding apparatus according to the first or second aspect, wherein the pressure adjusting means is a part of a pressing surface of the mold or It is characterized by being provided all around.

According to a fourth aspect of the present invention, there is provided the hollow body molding apparatus according to the first or second aspect, wherein the pressure adjusting means is provided with a heater. Characterize.

According to a fifth aspect of the present invention, there is provided a hollow body molding apparatus according to the first or second aspect, wherein the pressure adjusting means has a heat insulator incorporated therein. Characterize.

According to a sixth aspect of the present invention, there is provided a hollow body forming apparatus according to the second aspect, wherein the shaping means is a member for performing vacuum forming, pressure forming or vacuum pressure forming. It is characterized by including.

According to a seventh aspect of the present invention, there is provided a hollow body forming method in which a pair of thermoplastic resin sheets are arranged with a space therebetween so as to form a closed space and a hollow body is formed. In the initial stage of pressurizing the pair of resin sheets, the resin sheets are pressed by the pressure adjusting means provided on the press surfaces, not on the press surface of the mold for press-bonding the resin sheets. It is characterized by being done.

A hollow body molding method according to an eighth aspect of the present invention is the hollow body molding method of molding a pair of thermoplastic resin sheets into a hollow molded body, wherein each of the pair of resin sheets is separated by a space. The step of fixing to a holder and forming a closed space between the pair of resin sheets, the step of pressure-bonding the pair of resin sheets that have been heat-softened by pressure with a mold, and the pair of resin sheets A shaping step of shaping the shape of the cavity formed in the mold, wherein in the pressure-bonding step, the resin sheet is pressure-bonded in the initial stage of pressing the pair of resin sheets. The resin sheet is pressed not by the pressing surface of the mold but by the pressure adjusting means provided on the pressing surface. At the final stage of the pressing, the resin sheet is pressed by the pressing surface of the mold. Characterized in that the.

A hollow body molding method according to a ninth aspect of the present invention is the hollow body molding method according to the eighth aspect, wherein in the pressure-bonding step, the pressure adjusting means is equal to or higher than the softening temperature of the resin sheet. It is characterized by being heated to.

A hollow body molding method according to a tenth aspect of the present invention is the hollow body molding method according to the eighth aspect.
The shaping step is performed by a vacuum forming method, a pressure forming method, or a vacuum pressure forming method.

The hollow body molding method according to claim 11 is the hollow body molding method according to claim 7 or 8, wherein the resin sheet is an organic filler, an inorganic filler or a fiber reinforced material. Is a resin sheet containing

[0022]

As described above, according to the hollow body molding apparatus and the hollow body forming method of the present invention, at the initial stage of pressurizing the pair of resin sheets, the metal for press-pressing the resin sheets is pressed. Since the resin sheet is pressed by the pressure adjusting means provided on the pressing surface instead of the pressing surface of the mold, the temperature decrease of the resin sheet at the portion pressed by the mold is delayed, The interval between the resin sheets can be easily narrowed while maintaining the stretchability of the peripheral edge of the resin sheet. For this reason, even if the distance between the pair of resin sheets is set to be wide to use a large or vast thermoplastic resin sheet, it is possible to delay the temperature decrease of the resin sheet at the portion pressed by the mold. Therefore, the joint strength between the two resin sheets is not insufficient, and it is possible to form a hollow molded body having a hollow portion inside while improving the shapeability. Furthermore, since there is no insert inside the hollow body, it is possible to obtain a transparent molded body that looks good. Therefore, it is possible to mold a hollow molded body having a high bonding strength between the pair of thermoplastic resin sheets and having no insert.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a hollow body molding apparatus and a hollow body molding method according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a hollow body molding apparatus 10 according to the present invention.
2 is a sectional view showing the holder 3 of the hollow body molding device 10.
It is sectional drawing which shows 0 with the heating apparatus 60 which heat-softens a pair of thermoplastic resin sheet 20.

The hollow body molding apparatus 10 according to the present invention is used to mold a pair of thermoplastic resin sheets 20 into a hollow molded body 22 (see FIG. 6B) having a hollow portion 21 inside. To be As shown in FIG. 1, a hollow body molding device 1
Reference numeral 0 denotes a holder 30 that fixes each of the pair of resin sheets 20 with a space therebetween to form a closed space 31 between the pair of resin sheets 20, and a press for press-bonding the pair of heat-softened resin sheets 20 under pressure. The mold 40 and the cavity 41 formed in the press mold 40 by the pair of resin sheets 20.
And a shaping means 50 for shaping the shape. Further, as shown in FIG. 2, the hollow body molding device 10 includes a heating device 60 that heats and softens the pair of resin sheets 20 fixed to the holder 30.

As the material of the resin sheet 20, any thermoplastic resin that softens when heated can be applied. For example, polyolefin resin such as polyethylene or polypropylene, polystyrene, polycarbonate, acrylonitrile / styrene / butadiene block copolymer, nylon, etc. Examples of the thermoplastic resin include thermoplastic elastomers such as ethylene / propylene block copolymers and styrene / butadiene block copolymers, and polymer alloys thereof. The term "thermoplastic resin" in the present specification is a concept including all of these.

The resin sheet 20 may be a mixture of an organic filler, an inorganic filler or a fiber reinforcing material. Specifically, in the above-mentioned thermoplastic resin, various fillers such as talc and glass fiber, or several tens of nanometers, which is much smaller than the wavelength of visible light (380 to 770 nm).
It may be a nanocomposite material containing a fine-grained material of the order of m. Examples of the fine particle material include clay, talc, silica and the like. Further, it may be a thermoplastic resin in which various commonly used additives such as pigments, lubricants, antistatic agents and antioxidants are blended.

As shown in FIGS. 1 and 2, the holder 30 has a space between two thermoplastic resin sheets 20 so that the resin sheets 20 are closed spaces 31. It has a structure for fixing the peripheral portion of 20.
That is, the holder 30 includes the pair of thermoplastic resin sheets 2
The support portion 32 supports the respective peripheral portions of 0 and the pressing plate 33 (corresponding to the pressing portion) that presses the peripheral portions of the resin sheet 20 against the supporting portion 32.

The supporting portion 32 has a box shape with a rectangular cross section, and openings 32a are formed in each of the upper and lower walls.
A flange 32b for holding the resin sheet 20 is formed on the inner peripheral edge of the opening 32a. When each opening 32a is closed by the resin sheet 20, the inside of the support portion 32 is in a sealed state, and the closed space 31 is formed between the pair of resin sheets 20. The distance between the upper and lower walls, that is, the distance between the opposing thermoplastic resin sheets 20 is set by the heating device 60.
Even if the resin sheet 20 droops when 0 is softened by heating, the dimensions are set so that the pair of resin sheets 20 will not come into contact with each other or be fused.

As the material of the supporting portion 32, the resin sheet 2 is used.
The material is not particularly limited as long as it can withstand the stress generated during the thermal deformation of the resin sheet 20 in the process of heating 0. For example, iron-based, non-ferrous metal or ceramic-based, and thermosetting resin materials can be used. Preferred are iron-based and non-ferrous metal materials that are inexpensive and easy to process.

The pressing plates 33 are provided on the upper side and the lower side of the supporting portion 32 along the inner peripheral edge of the opening 32a. The pressing plate 33 has the support portion 32.
The resin sheet 20 is provided so as to be movable toward and away from the resin sheet 20.
The respective peripheral portions of are pressed against the support portion 32. Thereby, each of the pair of resin sheets 20 is fixed to the holder 30 with a space therebetween.

As a method of fixing the pressing plate 33 to the supporting portion 32, the pressing plate 33 and the supporting portion 32 are used.
A guide hole is machined along one side of the resin sheet 20 along the periphery of the resin sheet 20, and a needle-like protrusion that fits into the guide hole is provided on the other side, and the needle-like protrusion is fitted into the guide hole. A guide pin fastening method that narrows the pressure can be given. The fixing of the resin sheet 20 by this guide pin fastening method is common, but in addition, press fastening method by hydraulic pressure or air pressure, bolt fastening method, plate narrowing by which a plate holding the holding plate 33 is pressed by using a hinge. A pressure fastening method can be mentioned.

As shown in FIG. 1, the press die 40 has an upper die 42 and a lower die 43 which can move relatively toward and away from the upper die 42. Upper and lower molds 42, 4
3 is provided at a position sandwiching the inside of the fixed peripheral edge of the resin sheet 20. On the press surfaces of the upper mold 42 and the lower mold 43 that sandwich the resin sheet 20, the heat-softened resin sheet 20 is placed in the upper and lower molds 4 at the initial stage of pressurization.
A push guide (pressure adjusting means) 45 is provided so as to be able to move forward and backward so as to be sandwiched without directly contacting the press surfaces of Nos. 2 and 43. The push guide 45 prevents the temperature of the resin sheet 20 heated to a temperature equal to or higher than the heating softening temperature from decreasing due to the contact of the press die 40 lower than the temperature. Therefore, the resin sheet 20 near the portion pressed by the press die 40 by the push guide 45.
The temperature drop of is delayed.

The tip end portion of the push guide 45 has an extendable structure in which the protruding length thereof changes depending on the applied pressure. The push guide 45 can be provided on a part of the pressing surfaces of the upper and lower molds 42 and 43, or on the entire circumference. The push guide 45 may have a structure having a heat insulating function, but it is preferable that the push guide 45 has a function of heating the resin sheet 20 to a temperature higher than the softening temperature.

The pair of resin sheets 20 softened by heating are
By moving the upper and lower molds 42 and 43, the inside of the peripheral edge portion is sandwiched by the push guide 45 and pressure-bonded.
A cavity 41 having an inner surface shape that matches the outer shape of the hollow molded body 22 is formed on the inner surfaces of the upper and lower molds 42 and 43.

The die material of the press die 40 is an iron-based material,
Examples include non-ferrous metal or ceramic materials and thermosetting resin materials.

FIG. 3 is a sectional view of the spring type push guide, and FIG. 4 is a sectional view of the pneumatic or hydraulic type push guide. As shown in FIG. 3, the push guide 4
Reference numeral 5 includes a socket holder 71 and a socket 72. The socket holder 71 is firmly fixed by being inserted into the mounting holes provided in the upper mold 42 and the lower mold 43 from the pressing surface side thereof. The socket holder 71 includes a socket 7 that can be moved back and forth along its inner peripheral surface.
A pressing spring 73 for pressing the 2 toward the outside with a desired pressure is built in. The pressing spring 73 is supported by a spring base 74 inside the socket holder 71. A resin sheet compression portion 75 is provided at the tip of the socket 72. Therefore, the resin sheet compression portion 75 can be housed in the socket holder 71 (see FIG. 3B) or can protrude from the socket holder 71 (see FIG. 3A).

A heater (not shown) is built in the resin sheet compressing section 75 to heat the temperature of the resin sheet compressing section 75 to a temperature not lower than the heat softening temperature of the resin sheet 20.
In the case where the heater is not built in, it is desirable that the resin sheet compression section 75 has a heat insulating property. in this case,
As the structural material of the resin sheet compression portion 75, for example, a material having a low thermal conductivity such as a ceramic material, a thermosetting resin material, or a laminate material having a metal material on the surface and a resin material disposed inside may be used. desirable. The tip diameter of the resin sheet compression portion 75 may be any diameter, but it is preferable to select a diameter that does not form a pressure-bonded mark on the resin sheet 20.

The push guide shown in FIG. 4 does not press the resin sheet compression portion 75 with the pressing spring 73 unlike the push guide shown in FIG. 3, but presses the resin sheet compression portion 75 with air pressure or hydraulic pressure. It is a thing. The function of the push guide shown in FIG. 4 is the same as that of the push guide of FIG. In the case of the push guide shown in FIG. 4, airtightness is maintained between the socket holder 71 and the socket 72 in order to press the resin sheet compression portion 75 with air pressure or hydraulic pressure. Therefore, the socket holder 71 and the socket 72 form a pneumatic or hydraulic cylinder 76. The socket holder 71 is provided with a medium supply / exhaust port 77 for supplying air or oil into the cylinder 76 or for discharging the supplied air or oil.

In the push guide shown in FIGS. 3 and 4, until the upper die 42 and the lower die 43 sandwich the resin sheet 20, as shown in FIG. 3 (A) or FIG. 4 (A), the resin sheet is compressed. Although the portion 75 projects from the socket holder 71, when the resin sheet 20 starts to be sandwiched, the resin sheet compression portion 75 is gradually housed in the socket holder 71, and when the resin sheet 20 is completely sandwiched, as shown in FIG.
As shown in FIG. 4B or FIG. 4B, the resin sheet compression portion 75 is completely stored in the socket holder 71.

Examples of the molding method capable of shaping the molded body include a vacuum molding method, a pressure molding method, and a vacuum pressure molding method.

An apparatus for performing the vacuum forming method generally comprises a mold having a cavity capable of forming a molded body, and this mold is provided with a suction port for performing vacuuming. The mold has a structure that presses the resin sheet so that the space between the cavity and the resin sheet becomes a closed space. When performing the vacuum forming method, first, the thermoplastic resin sheet is preheated to a temperature equal to or higher than the heat distortion temperature by a heating device. This heated resin sheet is narrowed by a mold to form a closed space between the cavity and the resin sheet. Then, while the resin sheet is at or above the thermal deformation temperature, a negative pressure is applied to the inside of the cavity through the suction port to shape the resin sheet into a predetermined shape.

The compressed air molding method is a molding method using a method substantially opposite to the above-mentioned vacuum molding method, and compressed air is supplied from the outside to the closed space formed between the thermoplastic resin sheets,
In this method, a thermoplastic resin sheet heated to a temperature not lower than the heat distortion temperature is brought into close contact with the inner surface of the cavity to be shaped into a predetermined shape.

The vacuum pressure forming method is a forming method having both a vacuum forming method and a pressure forming method.

In the illustrated embodiment, the vacuum pressure forming method is adopted among these forming methods. The shaping means 5
Reference numeral 0 denotes a member for performing vacuum pressure forming, that is, a suction port 51 for performing vacuuming, and a pair of resin sheets 20.
And a gas feed pipe 52 for feeding a pressurized gas into the closed space 31 therebetween.

As shown in FIG. 1, the suction port 51 is formed on the surface of the cavity 41 of the upper and lower dies 42 and 43. Since the shape of the suction port 51 is transferred to the surface of the hollow molded body 22, it is preferable to form the suction port 51 at a position corresponding to the corner of the hollow molded body 22. The number of suction ports 51 is not particularly limited, and an appropriate number can be formed. The hole diameter of the suction port 51 is preferably 1 mm or less.

The gas inlet pipe 52 is provided so as to penetrate the support portion 32, as shown in FIGS. The gas inlet pipe 52 is arranged at a desired position which is a horizontal position on the surface on which the upper mold 42 and the lower mold 43 are pressed.
The tip of the gas inlet pipe 52 extends to a position communicating with the closed space 31 when the die is pressed.

A valve 53 for controlling the supply or stop of the supply of the pressurized gas is provided on the way of the gas inlet pipe 52. The valve 53 is normally closed and is opened to deliver pressurized gas at the same time the mold press is started or at the same time the mold press is completed. Further, the gas inlet pipe 52 is provided with an on / off mechanism (not shown) for making the space between the resin sheets 20 the closed space 31 or the open space. In this on / off mechanism, the space between the resin sheets 20 is set to the closed space 31 or the pressurized state until the pressurizing and pressing of the pair of resin sheets 20 is completed by the press die 40 and the feeding of the pressurized gas is completed. On the other hand, a mechanism for releasing the pressure in the hollow portion 21 to the atmosphere immediately before taking out the hollow molded body 22 is preferable. The injection time, injection pressure, injection start time, etc. of the pressurized gas are controlled.

As the material of the gas inlet pipe 52, iron-based, non-ferrous metal or ceramic-based, resin-based material or the like can be used.

As the gas to be used, a general gas is used, and typical examples of such gas include air, nitrogen, carbon dioxide gas and the like. Nitrogen gas is preferable. Further, the lower limit value of the pressurized gas to be used may be a high pressure gas of 1 MPa or more or a low pressure gas of less than 1 MPa, although it depends on each molding condition and resin type. Preferably, a low pressure gas of less than 1 MPa is convenient for handling.

At the time of vacuum pressure forming, the valve 5 is pressed immediately after the pressing of the resin sheet 20 by the upper and lower molds 42 and 43 is completed.
3 is opened, and the pressurized gas is supplied to the closed space 31 between the resin sheets 20 through the gas inlet pipe 52. At the same time, the resin sheet 20 is vacuumed from the suction port 51.
The shaping on the inner wall surface of the cavity 41 is promoted.

The heating device 60 can employ various methods as long as it can heat the thermoplastic resin sheet 20 to a softening temperature or higher. For example, a hot air heating method, a heating method with a far infrared heater having a maximum energy wavelength of about 4 μm, and an indirect heating method with a short wavelength or medium wavelength heater having a maximum energy wavelength of about 1 μm to 3 μm can be mentioned. A heating method using a far infrared heater in which the output wavelength of the heater and the absorption wavelength of the resin are substantially the same is common.

Next, using the above-described hollow body molding device 10, the pair of thermoplastic resin sheets 20 are joined to the hollow molding body 22.
The procedure for molding into the following will be described.

FIG. 5 (A) is a sectional view showing a state in the middle of the pressure-bonding step, and FIG. 5 (B) shows that the pressure-bonding step is completed.
6 is a sectional view showing a state where the shaping process is completed.
(A) is a sectional view showing a state in the middle of the trimming process,
FIG. 6B is a cross-sectional view showing the manufactured hollow molded body 22.

First, as shown in FIG. 2, the pressing plate 33 presses the peripheral portions of the pair of thermoplastic resin sheets 20 against the supporting portion 32. Thereby, the pair of thermoplastic resin sheets 20 are fixed to the holder 30 with a space therebetween, and the closed space 3 is provided between the resin sheets 20.
1 is formed (step of forming the closed space 31).

Next, the holder 30 is heated by the heating device 60.
Heating the pair of thermoplastic resin sheets 20 fixed to
The resin sheet 20 is softened (heat softening step).

When the resin sheet 20 reaches the heat-softening temperature or is held at the heat-softening temperature for several minutes, pressing by the upper and lower dies 42 and 43 is started to heat the resin sheet 20 as shown in FIG. 5 (A). The pair of softened resin sheets 20 are pressure-bonded by the upper and lower molds 42 and 43 (pressure-bonding step).

In the process of pressing the upper mold 42 and the lower mold 43 to the horizontal position where the gas inlet pipe 52 is arranged, the closed space 31 surrounded by the support portion 32 and the pair of resin sheets 20 is compressed. Since the space volume of the closed space 31 is reduced by this compression, each resin sheet 20
Is predicted.

In this pressure-bonding step, the push guide 45 projects from the pressing surfaces of the upper and lower molds 42 and 43 until the upper mold 42 and the lower mold 43 sandwich the resin sheet 20, as shown in FIG. Therefore, the upper and lower molds 42, 43
When the pressing by is started, first push guide 4
5 contacts the resin sheet 20. Then, as the pressing progresses, the push guide 45 is housed in the mold. Then, as shown in FIG. 5A, when the resin sheet 20 is completely pressure-bonded by the upper and lower molds 42 and 43, the push guide 45 is completely housed in the mold and the resin sheet 2
0 is mainly pressed and pressed by the pressing surfaces of the upper and lower dies 42 and 43.

Further, the resin sheet compression portion 75 corresponding to the tip end portion of the push guide 45 is heated to a temperature higher than the heat softening temperature of the resin sheet 20 by the heater provided therein. Therefore, the stretched portion (the portion stretched by the push guide 45) of the resin sheet 20 is pressed without falling below the heat softening temperature. Further, the resin sheet compression unit 75 does not need to have a built-in heater, but in that case, since it is made of a material having a heat insulating property, there is a decrease in temperature from the heat softening temperature when the resin sheet 20 is pressed. Be delayed. Therefore, from the start to the completion of the pressure bonding step, the resin sheet 20
The stretchability of the extended portion is maintained, and the space between the resin sheets 20 is easily narrowed. As a result, there is no fear that the joint strength between the two resin sheets 20 is insufficient.

Next, as shown in FIG. 5B, when the pressing by the upper and lower molds 42 and 43 is completed, the pair of heat-softened resin sheets 20 is vacuum-pressure formed by the shaping means 50 to form the cavity 41. The shape is shaped into (shape forming step). Specifically, the valve 53 is opened immediately after the pressing by the upper and lower dies 42 and 43 is completed, and the pressurized gas is supplied to the closed space 31 between the resin sheets 20 via the gas inlet pipe 52.
Supply to. At the same time, the suction port 51 is evacuated to accelerate the shaping of the resin sheet 20 onto the inner wall surface of the cavity 41.

After the cooling of the molded body is completed, the valve 53 is closed and the supply of the pressurized gas from the gas inlet pipe 52 is stopped. The on / off mechanism releases the pressure in the hollow portion 21 to the atmosphere. Then, as shown in FIG. 6 (A), the gas inlet pipe 52 is pulled out from the molded body, and the upper and lower dies 42 and 43 are opened to perform trimming (trimming step).

Through the above series of steps, as shown in FIG. 6B, a hollow molded body 22 having a hollow portion 21 inside is obtained.

As described above, according to the hollow-body molding apparatus 10 and the hollow-body molding method of this embodiment, when the pair of resin sheets 20 softened by heating are pressure-bonded by the press die 40, first, Since the push guide 45 that is heated or has a heat insulating function contacts the resin sheet 20 that is heated to the softening temperature or higher, the temperature of the resin sheet 20 near the portion pressed by the press die 40 decreases. Is delayed, the stretchability of the peripheral portion of the resin sheet 20 is maintained, and the space between the resin sheets 20 can be easily narrowed. Therefore, even when the gap between the pair of resin sheets 20 is set to be wide in order to use the large or vast thermoplastic resin sheet 20, the resin sheet 20 in the vicinity of the portion pressed by the press die 40 is used. Since it is possible to delay the temperature decrease of No. 2, there is no lack of joint strength at the joint portion where both resin sheets 20 are pressure-bonded, and it is possible to mold the hollow molded body 22 having the hollow portion 21 inside while improving shapeability. Becomes In addition, since the heating of the resin sheet 20 in the vicinity of the portion pressed by the press die 40 is performed to delay the temperature decrease, the time required for molding does not become long.

Furthermore, since there is no insert inside the hollow molded body 22, a transparent molded body having a good appearance can be obtained.

Therefore, it is possible to mold or manufacture a resin molded product which has a high bonding strength between the pair of thermoplastic resin sheets 20 and does not have an insert, and which is lightweight and exhibits high rigidity and high strength in a short manufacturing process. It will be possible.

In the above-described embodiment, the shaping means 50 includes the members 51 and 52 for performing vacuum pressure forming, but the present invention is not limited to this case. For example, as the shaping means 50, only a member for performing vacuum forming, that is, a suction port 51 for performing vacuuming may be provided in the mold 40, and the formed body may be formed by a vacuum forming method. Further, as the shaping means 50, only a member for performing pressure molding, that is, only a gas feed pipe 52 for feeding pressurized gas into the closed space 31 between the pair of resin sheets 20 is provided, and molding is performed by the pressure molding method. The body may be shaped.

[0068]

EXAMPLES Examples 1 to 7 of the present invention in which the hollow molded body 22 is molded with the press die 40 provided with the push guide 45 and the hollow molded body 22 with the press die 40 without the push guide 45 will be described below. The molded comparative examples 1-5 are demonstrated based on an experimental result.

(1) Thermoplastic resin sheet 20 As the thermoplastic resin sheet 20, 330 mm × 330 m
Two acrylic sheets of m × thickness 1 to 5 mm (manufactured by Mitsubishi Rayon, acrylic light L (colorless and transparent)) were prepared.

(2) Press mold 40 An aluminum mold having the structure shown in FIG. 1 was prepared.
The press die 40 was provided with a suction port 51 capable of vacuuming. The number of hollow portions 21 formed is one. The die pressing surface was 200 mm × 200 mm. The inner volume of each cavity 41 of the upper and lower molds 42 and 43 is 150 mm in length × 150 m in width.
A box structure having m × depth of 100 mm, a draft in the depth direction of 5 ° and a corner radius of 5 °. A mold was used that can be pressure-bonded on the entire circumference and up to 25 mm from the periphery of the mold pressing surface.

(3) Push Guide 45 Inside the resin sheet compression portion 75 of the push guide 45, a ceramic heater having a brass outer periphery was incorporated. Socket 7
2 was made of a ceramic material. Push guide 45
Used the spring type push guide shown in FIG.

(4) Holder 30 The support portion 32 was provided with a gas inlet pipe 52 made of SUS304 and having an outer diameter of 6 mm. The gas inlet pipe 52 was arranged at a position that protrudes from the wall surface of the end portion of the cavity 41 and is horizontal to the surface on which the upper and lower molds 42 and 43 are pressed during pressing the mold. The gas feed pipe 52 was provided with a valve 53 for feeding the pressurized nitrogen gas simultaneously with the die press. The size of the inside of the peripheral edge of the thermoplastic resin sheet 20 fixed by the pressing plate 37 is 300 mm × 3.
It is 00 mm. The spacing between the resin sheets 20 supported by the support 32 is 30 mm to 100 mm.

(5) Molding Step Two thermoplastic resin sheets 20 are fixed to the supporting portion 32 by the pressing plate 37, and after the resin sheet 20 is completely softened by heating, the heating softening temperature is 160 ° C. to 200 ° C. The mold pressing time was set to 60 seconds, and the vacuum pressure pneumatic timing was set to immediately after the press completion, and vacuum pressure pneumatic molding was performed. The temperature of the press die 40 was 85 ° C. ± 5 ° C. for both the upper and lower dies 42 and 43. The temperature of the resin sheet compression portion 75 of the push guide 45 is set to 130 ° C.
It was ± 5 ° C. Nitrogen gas having a pressure of 0.5 MPa was used as the pressurized gas.

(6) Molding Conditions and Evaluation Results Molding conditions and evaluation results are shown in Tables 1 and 2 below. As the molding conditions, the thickness of the thermoplastic resin sheet 20 (the thickness of the acrylic sheet), the distance between the upper and lower walls of the supporting portion 32 (the distance between the holders), that is, the distance between the opposing resin sheets 20 and the heat softening temperature were changed.

The plate thickness of the acrylic sheet is 1 mm to 5 mm. The holder interval is 30 mm to 100 mm. The heat softening temperature is 160 ° C to 200 ° C. Example 1
7, the press die 4 equipped with the push guide 45
The hollow molded body 22 was molded with 0. On the other hand, in Comparative Examples 1 to 5, the hollow molded body 22 was molded by the press mold 40 without the push guide 45.

In the evaluation items in the table below, the formability indicates the degree of transferability of deep drawing and corner radius. The case where the deep drawing is good and the transferability at the corner radius = 5 degrees is good is shown by “◯”, and the case where they are bad is shown by “x”. Further, the pressure-bonding property refers to the degree to which the contact interface of the thermoplastic resin sheet does not separate. When there is no air accumulation in the pressure-bonded part and the thermoplastic resin sheet contact interface does not peel off, it is indicated as "○" as a good case,
The case where it was defective is indicated by "x". The comprehensive evaluation is an evaluation in which the shapeability and the pressure-bonding property are comprehensively judged. The case where both the shapeability and the pressure-bonding property are good is shown by “◯”, and when either is bad, it is shown by “x”.

First, examples will be described. In the embodiment described below, the press die 40 provided with the push guide 45 is used. The results of each example are shown in Table 1.

[0078]

[Table 1]

<Examples 1 and 2> In these examples, an acrylic sheet having a plate thickness of 1.0 mm was used. The distance between the holders when the acrylic sheet is fixed to the support 32 is 30 mm
(Example 1) or 100 mm (Example 2). In each of the examples, the heat softening temperature of the acrylic sheet is 16
It was set to 0 ° C.

Under the above-mentioned molding conditions, a hollow molded body was molded using the above-mentioned press die 40. As shown in Table 1, in both Examples 1 and 2, the shapeability, The result that the crimpability and the comprehensive evaluation were good was obtained. <Examples 3 and 4> In these examples, the plate thickness is 3.0 mm.
The acrylic sheet of was used. Holder spacing is 30 mm
(Example 3) or 50 mm (Example 4). The heat-softening temperature of the acrylic sheet was 160 ° C. (Example 3) or 180 ° C. (Example 4).

Under the above-mentioned molding conditions, a hollow molded body was molded using the above-mentioned press die 40. As shown in Table 1, in both Examples 3 and 4, the shapeability, The result that the crimpability and the comprehensive evaluation were good was obtained. <Examples 5 to 7> In these examples, the plate thickness is 5.0 mm.
The acrylic sheet of was used. Holder spacing is 50 mm
(Example 5) or 100 mm (Examples 6 and 7). The heat softening temperature of the acrylic sheet was 180 ° C. (Examples 5 and 6) or 200 ° C. (Example 7).

Under the above-mentioned molding conditions, a hollow molded body was molded using the above-mentioned press die 40. As shown in Table 1, all of Examples 5 to 7 were shaped. The result was that the evaluation was good, and the overall evaluation was good.

Next, a comparative example will be described. In the following comparative example, a normal press die 40 without the push guide 45 was used. The press die 40 can press the entire circumference of the portion up to 25 mm inside the peripheral edge of the press surface. The results of each comparative example are shown in Table 2.

[0084]

[Table 2]

<Comparative Example 1> In this comparative example, a hollow molded body was molded using the above-mentioned press die 40 under the same molding conditions as in Example 1 above. As a result, as shown in Table 2, the shapeability was good “○”, but the air pressure was generated in a part of the pressure-bonded area, so that the pressure-bondability was poor “x”. It was For this reason, the comprehensive evaluation was also "bad". <Comparative Example 2> In this Comparative Example, a hollow molded body was molded using the above-mentioned press mold 40 under the same molding conditions as in Example 3 above. As a result, as shown in Table 2,
The shapeability was good “◯”, but the air pressure was generated in a part of the pressure-bonded area, so the pressure-bondability was poor “x”. For this reason, the comprehensive evaluation was also "bad". <Comparative Example 3> In this Comparative Example, a hollow molded body was molded using the above-described press die 40 under the same molding conditions as in Example 5 described above. As a result, as shown in Table 2,
The shapeability was good “◯”, but the air pressure was generated in a part of the pressure-bonded area, so the pressure-bondability was poor “x”. For this reason, the comprehensive evaluation was also "bad". <Comparative Example 4> In this Comparative Example, a hollow molded body was molded using the above-described press die 40 under the same molding conditions as in Example 6 above. As a result, as shown in Table 2,
Both the shapeability and the pressure-bonding property were “poor”. For this reason, the comprehensive evaluation was also "bad". This result is obtained because the entire surface of the press die 40 is not pressure-bonded and the pressure-air pressure loss occurs. <Comparative Example 5> In this Comparative Example, a hollow molded body was molded using the above-mentioned press mold 40 under the same molding conditions as in Example 7 described above. As a result, as shown in Table 2,
The shapeability was good “◯”, but the air pressure was generated in a part of the pressure-bonded area, so the pressure-bondability was poor “x”. For this reason, the comprehensive evaluation was also "bad". <Discussion> From the results of Examples 1 to 7 and Comparative Example, it is understood that the use of the hollow molded body molding apparatus 10 and the molding method of the present invention greatly improves the pressure bonding property. The result is that the push guide 45 (130
However, the temperature is considerably lower than the heating softening temperature (160 ° C. to 200 ° C. in the experiment), which is the pressing surface of the press die 40 (85 ° C. ± in the experiment).
It is considered that this is because (5 ° C.) is not brought into direct contact with the resin sheet 20.

Therefore, according to the hollow molded body molding apparatus 10 and the molding method of the present invention, even in a large-sized or vast sheet-shaped thermoplastic resin sheet 20, the thermoplastic resin sheet 20 is heated or softened or molded. , The holder space is separated to the necessary range that does not cause contact and fusion due to sagging, and from that state it is possible to mold a hollow molded body with a hollow part inside, there is no insert inside, and the strength of the joint part It can be seen that the production of excellent resin molded products that are high, lightweight, and that exhibit high rigidity and high strength is dramatically improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a hollow body molding device according to the present invention.

FIG. 2 is a cross-sectional view showing a holder of a hollow body molding device together with a heating device for heating and softening a pair of thermoplastic resin sheets.

FIG. 3 is a sectional view of a spring type push guide.

FIG. 4 is a sectional view of a pneumatic or hydraulic push guide.

5A is a cross-sectional view showing a state in the middle of a pressure-bonding step, and FIG. 5B is a cross-section showing a state where the pressure-bonding step is completed and the shaping step is completed. It is a figure.

FIG. 6 (A) is a sectional view showing a state in the middle of a trimming process, and FIG. 6 (B) is a sectional view showing a manufactured hollow molded body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Hollow body molding apparatus 20 ... Thermoplastic resin sheet 21 ... Hollow part 22 ... Hollow molded body 30 ... Holder 31 ... Closed space 32 ... Supporting part 33 ... Pressing plate 40 ... Press mold (mold) 41 ... Cavity 42, 43 ... Upper / lower mold 45 ... Push guide 50 ... Shaping means 51 ... Suction port (shaping means (member for vacuum forming or vacuum pressure forming)) 52 ... Gas inlet pipe (shaping means (pressure forming or vacuum forming) Member for performing pressure molding)) 60 ... Heating device 71 ... Socket holder 72 ... Socket 73 ... Pressing spring 74 ... Spring base 75 ... Resin sheet compression section 76 ... Cylinder 77 ... Medium supply / discharge port

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinkichi Torii             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Katsuhiko Suzuki             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F-term (reference) 4F202 AG07 CA17 CA27 CA30 CB01                       CK17 CK42 CK52 CL09 CL42                       CN18                 4F208 AC03 AG07 AR02 MA01 MA02                       MA03 MB01 MC01 MH06 MJ21                       MJ30 MK08 MK15 MK20

Claims (11)

[Claims] 1. A hollow body molding device for molding a pair of thermoplastic resin sheets with a space therebetween so as to form a closed space and molding into a hollow molded body. The mold pressing surface is provided with expandable and contractible pressure adjusting means, and the resin sheet is pressed by the pressure adjusting means instead of the pressing surface in the initial stage of pressurizing the resin sheet. Hollow body forming device. 2. A hollow body molding device for molding a pair of thermoplastic resin sheets into a hollow molded body, wherein each of the pair of resin sheets is fixed with a space therebetween and a closed space is provided between the pair of resin sheets. A holder for forming a mold, a mold for press-bonding the pair of resin sheets that have been heated and softened, and a shaping unit for shaping the pair of resin sheets into the shape of the cavity formed in the mold, In the mold, a press surface for press-bonding the pair of resin sheets in the final stage of pressurization is formed, and in the press surface, the resin sheet is pressed in the initial stage of pressurization. 1. A hollow body molding device, characterized in that a pressure adjusting means capable of expanding and contracting according to the applied pressure is provided so as to project. 3. The hollow body molding apparatus according to claim 1, wherein the pressure adjusting means is provided on a part or the entire circumference of the pressing surface of the mold. 4. The hollow body molding apparatus according to claim 1, wherein the pressure adjusting means is provided with a heater. 5. The hollow body molding apparatus according to claim 1, wherein a heat insulator is built in the pressure adjusting means. 6. The hollow body molding apparatus according to claim 2, wherein the shaping means includes a member for performing vacuum forming, pressure forming, or vacuum pressure forming. 7. A hollow body molding method for molding a pair of thermoplastic resin sheets with a space therebetween so as to form a closed space and molding into a hollow molded body, wherein an initial stage of pressurization of the pair of resin sheets. In the hollow body molding, the resin sheet is pressed by the pressure adjusting means provided on the pressing surface, not the pressing surface of the mold for press-bonding the resin sheet. Method. 8. A hollow body molding method for molding a pair of thermoplastic resin sheets into a hollow molded body, wherein each of the pair of resin sheets is fixed to a holder with a space provided between the pair of resin sheets. A step of forming a closed space, a step of pressure-bonding the pair of resin sheets that have been heat-softened by pressure with a mold, and a step of shaping the pair of resin sheets into the shape of the cavity formed in the mold. In the initial stage of pressurization of the pair of resin sheets, in the pressure-bonding step, not the press surface of the mold for press-bonding the resin sheet, but the press surface is provided. A hollow body molding method, characterized in that the resin sheet is pressed by the pressure adjusting means provided, and in the final stage of the pressing, the resin sheet is pressed by the pressing surface of the mold. 9. The hollow body molding method according to claim 8, wherein, in the pressure-bonding step, the pressure adjusting means is heated to a temperature equal to or higher than the softening temperature of the resin sheet. 10. The hollow body molding method according to claim 8, wherein the shaping step is performed by a vacuum forming method, a pressure forming method, or a vacuum pressure forming method. 11. The hollow body molding method according to claim 7, wherein the resin sheet is a resin sheet containing an organic filler, an inorganic filler, or a fiber reinforcing material.