JPH0885146A - Apparatus for molding synthetic resin hollow molded object - Google Patents

Abstract

PURPOSE: To hold both thermoplastic resin sheets between both upper and lower molds without shifting the molds, in a molding method introducing compressed air into the gap between the thermoplastic resin sheets of which the peripheral edge parts are clamped to bring both sheets into close contact with both molds, by providing a plurality of guide pieces to the outer peripheral surface of one of the molds. CONSTITUTION: When a double sheet molding method is executed, at first, the peripheral edge parts of sheets 9, 10 are clamped by upper and lower clampers 1, 1 in such a state that a spacer 11 is interposed between the peripheral edge parts and, next, the sheets 9, 10 are heated and softened by heaters and molds 2, 3 are subsequently allowed to approach the softened sheets 9, 10. In this approach process, the sheets 9, 10 are rubbed and ruptured by the tip parts of guide pieces 6... and the outer peripheral surface of the upper mold 2 is guided to the inner surface on the protruding side of the guide pieces 6... of the lower mold 3. After the molding air nozzle 13 of the mold 2 is allowed to pierce through the sheet 9, compressed air is introduced into a closed space 12 from the air nozzle 13 to bring the sheets 9, 10 into close contact with the cavity inner surfaces 2b, 3b of the molds 2, 3 to obtain a hollow molded object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for hollow synthetic resin moldings.

[0002]

2. Description of the Related Art As a method for producing a synthetic resin hollow molded article, the following molding method, which is so-called double sheet molding method, has been known.

That is, as shown in FIG. 5 (a), two sheets of thermoplastic synthetic resin sheets (51) and (52) are used as molding materials, and their peripheral portions are interposed with a spacer (53) in between. Clamped from above and below with the clampers (54) (54), and in parallel and horizontally at a predetermined interval so that the closed space (55) is left between the sheets (51) (52). To support. Then, heat both seats (51) (52) to the heater (56).
(56) is heated from above and below to be softened, and compressed air is appropriately introduced into the closed space (55) between the seats (51) and (52) from the air nozzle (57) provided in a part of the spacer (53). Is blown in to pretension both sheets (51) (52) in the direction of mutual separation. Then, in this heat-softened state, as shown in FIG. 5B, a pair of upper and lower molding dies (59) (6) are placed inside the clamp positions of the both edges of the sheets (51) (52).
Both dies (59) (60) are brought close to a predetermined closed position so that they can be sandwiched between them, and the sheet clamping surface (59
The sheets (51) and (52) are sandwiched between a) and (60a), and their peripheral portions are joined and integrated. Next, as shown in FIG. 5C, the air nozzle (61) for introducing compressed air provided in one of the molds (59) is advanced so that it penetrates one sheet (51). Then, the sheets are inserted into the closed space (55) between the seats (51) and (52), and compressed air having a predetermined pressure is introduced into the closed space (55) through the nozzle (61). The (52) is brought into close contact with the inner surfaces (59b) (60b) of the cavities of both molds (59) (60). During the introduction of this compressed air, each mold (59) (60)
In some cases, a vacuum suction mechanism (not shown) provided for the sheet is used to draw a vacuum to help close the sheets (51) and (52) in the mold. Then, after cooling while maintaining the internal pressure between both sheets, the compressed air introduction nozzle (61) is retracted and both molds (59) (60) are opened to take out the hollow molded body.

Conventionally, in carrying out the above-described double sheet forming method, the sheets (51) (52) are sandwiched with the molds (59) (60) displaced from each other. When,
Decrease the joint strength between both sheets (51) (52),
In order to prevent such a situation from occurring due to poor bonding, the following structure for preventing misalignment has been adopted.

That is, as shown in FIG. 6, the upper die (5
A table (63) that projects outward from the clamp position is provided on the back surface of 9), and a bed (64) that projects outward from the clamp position also on the back surface of the lower mold (60). ) Is provided, and the table (63) and the bet (64)
The guide columns (65) (66) are provided corresponding to the respective opposing surfaces of the guide columns (65) (66) at positions outside the clamp position, and the positioning protrusions (66) are provided on the tip faces of the upper and lower guide columns (66).
a) is provided, and a positioning recess (65a) is provided on the tip surface of the other guide column (65).
When the seats (51) and (52) sandwich the seats (51) and (52), the positioning projections (65a) and recesses (66a) are fitted to each other, whereby the molds (59) (60) The seats (51) (52) are sandwiched between the two without any misalignment.

[0006]

However, in the mold deviation prevention structure as shown in FIG. 6, the table (63) and the bed (64) are provided on the back side of the molds (59) (60). Since the table (63) and the bed (64) are provided with the guide columns (65) and (66), the guide structure is provided. The weight of the molding equipment has become very large and the size has also become very large, which has also made the equipment very expensive. By the way, in terms of weight, when the weight of the mold (59) (60) itself is 500 kg and the mold size is about 1 m square, the table (63) including the guide columns (65) (66), the bed The weight of (64) reaches 500 to 600 Kg, and if these are combined, the total weight may exceed 1000 Kg, and the mechanical load on the molding apparatus becomes very large. Further, in terms of size, there is also a problem that the size of the hollow molded body that can be molded is limited to a small size, even though the equipment is large.

Further, since the table (63) and the bed (64) have a structure that greatly projects to the side, both molds (59)
Depending on the gripping strength of the seats (51) and (52) by the (60), that is, the mold clamping strength, the table (6
3) or the bed (64) may be deformed flexibly. Therefore, the positioning projections (65a) and recesses (66a)
), But the molds (59) (60) are misaligned, the sheets (51) (52) are pinched and the sheets (51) (52) are not joined properly. However, this is not always a perfect structure as a means for preventing mold deviation.

In view of the above-mentioned conventional problems, the present invention can reliably prevent the mold displacement between the upper and lower molds from occurring and can properly join the sheets, and It is an object of the present invention to provide a molding apparatus for a synthetic resin hollow molded body, which can realize a reduction in weight and cost of the apparatus itself, and can compact a hollow molded body having a large size. To do.

[0009]

In order to achieve the above object, the present invention clamps two thermoplastic synthetic resin sheets at their peripheral edges with spacers in a manner such that a predetermined closed space is left between them. After heating and softening the both sheets, they are sandwiched between a pair of upper and lower molds inside the clamp position on the peripheral edge, and compressed air is introduced into a closed space between the both sheets to move the both upper and lower molds. In a molding apparatus equipped with the upper and lower molds, which is used for carrying out the method for molding a hollow molded body, the guide piece is provided on the outer peripheral surface of at least one of the molds, and the peripheral edge of the mold is sandwiched. In a mode in which a plurality of dies are provided at intervals in the circumferential direction in a mode of projecting from the height position of the attachment surface, the other dies are guided on the outer peripheral surface by the guide piece in the process of relatively approaching the two dies. By making money There is summarized as molding device of the synthetic resin hollow molded body characterized by being adapted to interleave the type displacement without the sheets.

Further, in the above invention, it is preferable that an inner inclined surface of the guide piece on the protruding side is formed with an inclined surface for introduction which is inclined outward in the protruding direction.

[0011]

In the above-mentioned invention, the two sheets are sandwiched by the guide pieces by the guide piece without the molds being displaced.

In addition, the guide piece is provided at a position on the outer peripheral surface of the mold very close to the mold, and the guide piece allows the other mold to be positioned on the outer peripheral surface very close to the mold. In this case, the two molds properly sandwich the sheets with each other without the mold deviation even when the mold clamping strength is large.

Further, since the guide piece provided on the outer peripheral surface of one mold guides the outer peripheral surface of the other mold to prevent the mold deviation, the guide piece is lightweight.
Even if a small size is adopted, the molding apparatus can be made lighter in weight and lower in cost, and can be made compact to form a large hollow molded body.

Further, since the guide pieces are not projected in the entire circumferential direction of the outer peripheral surface of the mold, but are provided so as to project in the circumferential direction at a plurality of intervals, the sheet formed by the guide pieces. The range of biting into the mold is also limited to a small value, so that the resistance when clamping the molds to each other is also restricted to a low level, and there is no possibility of inadequate joining of the sheets due to defective mold clamping.

Further, by forming an introducing inclined surface which is inclined outward in the protruding direction on the inner surface on the protruding side of the guide piece, a slight mold deviation occurs between the molds in a separated state. Even if there is such a problem, when it is inserted, it is automatically corrected to such a state that there is no mold deviation, and the molds are fitted smoothly.

[0016]

Embodiments of the present invention will be described below.

In the forming apparatus for forming a double sheet shown in FIG. 1, (1) and (1) are clampers, and (2) and (3).
Is the upper and lower molds. In addition, (4) and (4) are heaters.

Then, as shown in FIG. 1 and FIG.
On the outer peripheral surface of the lower die (3), guide pieces (6) are projected by a predetermined height above the height of the peripheral clamping surface (3a) of the die (3). In the embodiment, a plurality of bolts (15) and the like are attached at intervals in the circumferential direction, and the upper die (2) has its outer peripheral surface on the guide piece (6).
It is adapted to be fitted into the lower mold (3) while being guided by.

The number of guide pieces (6) and the mounting positions in the circumferential direction depend on the outer peripheral shape of the mold (3) and the like, but at least three guide pieces (6) are displaced in any direction from the upper mold (2). Instead, they are mounted at intervals in the circumferential direction in a mode in which they are fitted to the lower mold (3). Specifically, the mold (3)
When the outer peripheral shape of has a shape having three or more sides, for example, a rectangular shape as shown in FIG.
It is attached to each side. Moreover, like this, 3
In the case of a shape having three or more sides, for example, a square shape as described above, it is preferable to attach the members in a state of being biased to each corner side for the reason of preventing the occurrence of mold clamping failure. desirable.

Each of the guide pieces (6) is made of a metal such as cast iron, aluminum or stainless steel for the reason of strength, and has a thickness in the range of 2 to 12 mm, especially The width is set in the range of 6 to 8 mm, and in the range of, for example, 20 to 100 mm, particularly 40 to 80 mm. Also,
The projecting height of the guide pieces (6) from the clinging surface (3a) is set in the range of, for example, 3 to 40 mm, particularly 8 to 20 mm, in view of the guide function and the like.

An inclining surface (7) for introduction which is inclined outward in the protruding direction is formed on the inner surface of each of the guide pieces (6) ... ) As the upper mold (2) smoothly fits with each guide piece (6)
It is designed to be guided by ...

In carrying out the double sheet forming method with the above-mentioned forming apparatus, first, as shown in FIG. 1, an annular frame-like shape is formed between the peripheral portions of the sheets (9) and (10) as the forming material. With the spacer (11) interposed, the peripheral portion is clamped from above and below by the clampers (1) and (1), and the closed space (21) is left between the sheets (9) and (10). It is supported in a parallel and horizontal manner.

A sheet (9) as a molding material
The material of (10) is not particularly limited as long as it is made of a thermoplastic resin, and any thermoplastic synthetic resin material is selected and used according to the application of the hollow molded body. Specifically, for example, vinyl chloride resin, acrylic resin, polycarbonate resin or the like can be used. The sheet thickness is
Generally, it is, for example, about 1 to 10 mm.

Next, the heaters (4) and (4) heat and soften both sheets (9) and (10) to a predetermined molding temperature.
At this time, at the same time, compressed air is introduced into the closed space (12) between the seats (9) and (10) from the air nozzle (11a) provided in a part of the spacer (11) to prevent free gravity deformation of both seats. And pre-stretch the sheet.

Then, while continuing the pre-tensioning operation, the heaters (4) and (4) were removed, and then, as shown in FIG.
As shown in (b), the upper and lower molds (2) are attached to both sheets (9) and (10) on the inner sides of the clamping positions of the peripheral edges thereof.
(3) is approached.

In this approaching process, first, the guide pieces (6) ... Scrap the sheets (9) and (10) at their leading ends, and then the upper die (2) on the outer peripheral surface of the lower die (3). Each guide piece (6) is guided to the inner surface on the protruding side. By this, if there is a mold deviation, the mold deviation is corrected, and then, as shown in FIGS. 3 (c) and 4 (a), the sheet is attached to the peripheral wall between the molds (2) and (3). The sheets (9) and (10) are sandwiched between the parts (2a) and (3a), and the sheets (9) and (10) are joined and integrated.

After that, as shown in FIG. 4B, the molding air nozzle (13) provided on one mold (2) is driven by a driving means (14) such as a driving cylinder in a conventional manner. This is operated by one of the seats (9)
To penetrate. Subsequently, compressed air is introduced from the air nozzle (13) into the closed space (12) between the sheets (9) and (10) to form the sheets (9) and (10) in the molding die (2) (3). Close the inner surface (2b) (3b) of the cavity. Then, after performing the required cooling while maintaining this internal pressure,
A hollow molded body is obtained by removing the air nozzle (13) and opening the molds (2) and (3) to take out the hollow molded body.

As described above, in the above molding apparatus, the guide pieces (6) ... Guide the molds to guide the sheets (9) and (10) and the molds (2) and (3) are displaced. You can slip in without having to. Moreover, the guide pieces (6) ... Are provided on the outer peripheral surface of the mold (3) very close to the mold (3), and the guide pieces (6) ...
The other mold (2) is guided by the outer peripheral surface of the mold (2) very close to the mold (3). Sheet (9) without any misalignment
(10) It is possible to pinch each other accurately. Therefore,
The sheets (9) and (10) can be reliably joined and integrated in an appropriate joined state, and a hollow molded article of good quality can be molded with high reliability.

Further, the guide pieces (6) provided on the outer peripheral surface of the lower mold (3) are used to guide the outer peripheral surface of the upper mold (2) to prevent the mold deviation between the two molds (2) and (3). Therefore, it is possible to use the above-mentioned lightweight and small-sized guide pieces (6), which can reduce the weight and cost of the molding apparatus and also make the molding apparatus compact. A hollow molded body having a large size can be molded.

Further, the guide pieces (6) are not provided so as to project in the entire circumferential direction of the outer peripheral surface of the mold (3), but are provided so as to project at intervals in the circumferential direction. From the sheet (9) (10) by the guide piece (6) ...
The range of biting into the mold is also limited, so the resistance when clamping the molds (2) and (3) is low, and the occurrence of defective joints between the sheets (9) and (10) due to defective mold clamping is avoided. Therefore, the sheets (9) and (10) can be joined and integrated with good joining strength.

Further, in this embodiment, the guide pieces (6) ... Are separately formed from the mold (3), and the guide pieces (6) are attached to the mold (3) to be integrated. Since the structure is designed as described above, the size of the mold (3) is not increased as compared with the case where such a guide portion is integrally provided with the mold, and Mold material costs can be kept low.

Further, since the guide inclined surfaces (7) which are inclined outward in the protruding direction are formed on the inner surfaces on the protruding side of the guide pieces (6), the molds (2) (3). Even when the molds are slightly separated from each other when they are separated from each other, both molds (2) and (3) can be naturally corrected to such a condition that there is no such mold deviation when they are inserted. Mold (2)
(3) The parts can be fitted smoothly.

In the above embodiment, the guide pieces (6) ... Are attached to the lower mold (3).
A guide piece may be attached to the upper die (2), or a guide piece may be attached to the two dies (2) and (3) so as to be located at different positions in the circumferential direction. May be.

[0034]

As described above, according to the molding apparatus for a synthetic resin hollow molded article of the present invention, the guide pieces serve to guide the two sheets into each other without the two molds being displaced from each other. You can

Moreover, the guide piece is provided at a position on the outer peripheral surface of the mold very close to the mold, and the guide piece allows the other mold to be positioned on the outer peripheral surface very close to the mold. Since it is designed to guide the sheets, the two dies can properly sandwich the sheets without the mold displacement regardless of the clamping strength. Therefore, the sheets can be surely joined and integrated in an appropriate joined state, and a hollow molded article of good quality can be molded with high reliability.

Further, since the guide piece provided on the outer peripheral surface of one mold guides the outer peripheral surface of the other mold to prevent the mold deviation, the guide piece is lightweight and small in size. Can be adopted to reduce the weight and cost of the molding apparatus, and to form a hollow molding having a large size with a compact molding apparatus. Moreover, since the weight of the apparatus can be reduced in this way, the die replacement work can be safely performed.

Further, since the guide pieces are not projected in the entire circumferential direction of the outer peripheral surface of the mold, but are provided so as to be projected at a plurality of intervals in the circumferential direction, the guide pieces are attached to the sheet. The biting range of is also limited,
Therefore, the resistance at the time of clamping the molds is low, the occurrence of the defective bonding of the sheets due to the defective mold clamping can be avoided, and the sheets can be properly bonded and integrated.

Further, by forming an introducing inclined surface which is inclined outward in the protruding direction on the inner surface on the protruding side of the guide piece, a slight mold deviation occurs between the molds in the separated state. Even when there is such a problem, the molds can be naturally corrected in such a state that there is no mold deviation when they are inserted, and the molds can be fitted smoothly.

[Brief description of drawings]

FIG. 1 is a sectional side view of a molding apparatus according to an embodiment.

FIG. 2 is a perspective view of a mold in the molding apparatus.

FIG. 3A to FIG. 3C are cross-sectional views showing a time-series of a sheet picking process in the vicinity of a guide piece.

FIG. 4 (a) is a sectional side view of the device in a state where the seat is sandwiched, and FIG. 4 (b) is a sectional side view of the device during introduction of compressed air.

5A and 5B show a general example of a double sheet forming method. FIG. 5A is a sectional side view showing a heating and softening step, and FIG. 5B is a state in which a sheet is sandwiched by a mold. A sectional side view, FIG. 3C is a sectional side view showing a compressed air introduction state.

FIG. 6 is a sectional side view showing a mold deviation prevention structure in a conventional molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Clamper 2 ... Upper mold 3 ... Lower mold 2a, 3a ... Clamping surface 4 ... Heater 6 ... Guide piece 7 ... Inclined surface 9, 10 ... Sheet 11 ... Spacer 12 ... Closed space 13 ... Nozzle

Claims (2)

[Claims] 1. Two thermoplastic synthetic resin sheets are clamped at their peripheral edges with a spacer in a mode in which a predetermined closed space is left between them to heat and soften the two sheets, and For carrying out a method for forming a hollow molded body, which is sandwiched between a pair of upper and lower molds inside the clamp position, and compressed air is introduced into the closed space between the two sheets to bring the two sheets into close contact with the upper and lower molds. In the molding apparatus provided with the upper and lower molds used, in at least one of the molds, a guide piece is provided on an outer peripheral surface of the mold in a manner that the guide piece protrudes from a height position of a peripheral edge clamping surface of the mold. , A plurality of molds are provided at intervals in the circumferential direction, and the other mold is guided on the outer peripheral surface thereof by the guide piece in the process of relatively approaching the two molds,
An apparatus for molding a hollow hollow synthetic resin body, characterized in that both dies are designed so as to sandwich both sheets without mold deviation. 2. The molding apparatus for a synthetic resin hollow molded article according to claim 1, wherein an inner inclined surface of the guide piece on the protruding side is formed with an inclined surface for introduction which is inclined outward in the protruding direction.