JPH0999483A - Apparatus for molding synthetic resin hollow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the thickness of a bonded part of the reinforcing part of a hollow molding by implanting an ejection pin in at least one inner surface of molds and bonding both sheets to the inner wall of the other mold by the top part of the ejector pin under pressure at the time of the relative approach of both molds. SOLUTION: An ejector pin 8 is fitted in the implanting hole 9 of a mold 6 in such a state that the body lower part thereof is fundamentally made forcibly or non-forcibly changeable in a height direction and implanted in the mold 6 in such a state that a body upper part is exposed to the surface of the mold 6. Compressed air is introduced into a closed space 3 to closely bond both sheets 1, 2 to upper and lower molds and, at the same time, the ejector pin is made variable in a height state and both sheets 1, 2 are bonded to the inner wall of other mold 5 under pressure by the top part of the ejector pin 8 to be mutually bonded and the end edge parts of both sheets 1, 2 are mutually bonded by the outer peripheral grasping parts 5a, 6a of both molds 5, 6 to obtain a synthetic resin hollow molding having a reinforcing hollow projection.

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 Conventionally, as a method for producing a hollow molded article made of synthetic resin, there is the following method known as a so-called double sheet molding method. That is, in FIG. 4 (a), two thermoplastic synthetic resin sheets (21) and (22) are provided with spacers (24) and (24) at their peripheral portions so as to leave a predetermined closed space (23) between them. The sheets (21) and (22) are heated and softened by the heater (T), and then relatively approached inside the clamped position as shown in FIGS. 4B and 4C. It is sandwiched between a pair of upper and lower molds (25) (26), the air nozzle (27) is inserted into the thermoplastic synthetic resin sheet (21), and compressed air is introduced into the closed space (23) so that both sheets (21 ) (22) is brought into close contact with the upper and lower molds, and at the same time, the top (30) of the protrusion (28) integrally fixedly installed on the mold (26) separates both sheets (21) (22) from the other. The inner walls of the molds are crimped together to bond them together, and the outer peripheral sandwiching parts (25a) (26a) of both molds are used to seal both sheets. By mutually bonding the edge portion (21) (22), as shown in FIG. 2, a method of obtaining a synthetic resin hollow molded body (F) with a reinforcing hollow projections (H).

In this case, the height of the protrusion (28) installed on the mold (26) is the same as the top (30) of the protrusion (28) when the two molds (25) (26) are relatively close to each other. The distance from the inner wall of the other mold (25) facing each other is regulated, and at the same time, the thickness of the joint portion (h) of the two thermoplastic synthetic resin sheets (21) (22) to be pressure-bonded therebetween is regulated. The thickness of the joint portion (h) affects the reinforcing strength of the hollow molding (F) by the reinforcing hollow protrusions (H), and the mold (25) (2)
At the time of manufacturing 6), the height of the protrusion (28) is usually required to have a high accuracy in the range of 0.1 to 1.0 mm.

[0004]

However, according to the conventional molding apparatus using the mold having the above-mentioned protrusion, the height of the protrusion of the mold is often two thermoplastic synthetic resins. It is decided after repeated test molding and mold correction until the optimum height for joining sheets is obtained.
It takes a long time to design and manufacture the mold, and the manufacturing is complicated and the cost is high. In addition, the molding material, thickness,
When the thickness of the joining portion needs to be changed in consideration of molding conditions, joining strength, etc., there is a problem in that the die cannot be adjusted anymore, and the die must be completely modified.

[0005] The present invention solves the above problems,
An object of the present invention is to provide a molding device for a synthetic resin hollow molded body having a mold capable of easily adjusting the thickness of the joint portion in the reinforcing portion of the hollow molded body.

[0006]

To achieve the above object, the present invention clamps two thermoplastic synthetic resin sheets at their peripheral edges with spacers so as to leave a predetermined closed space between them. After heating and softening both sheets,
The upper and lower molds are sandwiched between a pair of upper and lower molds inside the clamp position, and compressed air is introduced into the closed space to bring the two sheets into close contact with the upper and lower molds. In a molding apparatus provided with a mold, at least one of the molds, on its inner surface, a protruding pin for forming a reinforcing hollow protrusion of the molded body is planted in a variable state in the height direction, A gist of a molding device for a synthetic resin hollow molded article is characterized in that, when the two dies are relatively approaching each other, the top portions of the projecting pins press the both sheets against the inner wall of the other die.

Another aspect of the present invention is a molding apparatus for a synthetic resin hollow molded body, wherein the protruding pin is made of a rubber elastic body.

Still another aspect of the present invention is a hollow molding of synthetic resin, wherein the protrusion pin is variably planted in a height direction by a screw provided on a lower portion of the body and a mold. It is a body shaping device.

Further, according to another aspect of the present invention, the projecting pin is elastically variably planted in the height direction by an elastic body disposed between the bottom of the projecting pin and the mold. It is a molding device for a synthetic resin hollow molded body.

Further, according to another aspect of the present invention, the projecting pin is elastically variable in the height direction by a spring-like elastic piece or a rubber-like elastic piece arranged between the bottom portion and the mold. 1 is a molding apparatus for a synthetic resin hollow molded body that is implanted in a state.

In the present invention, the "variable state" means any state in which the height of the protruding pin from the inner wall surface of the mold can be forcibly or non-forcedly changed. Target refers to the case where protruding pins are installed so that the height is fixedly set in advance before thermoforming, and non-forced refers to the joint portion of the thermoplastic synthetic resin sheet in the reinforcing portion of the hollow molding during thermoforming. In this case, the pins are elastically protruded and the pins are installed so that they can exert the sufficient pressure force to form the joints and the elasticity to sufficiently maintain the thickness of the joint.

In the present invention, the term "two thermoplastic synthetic resin sheets" means the substance of the thermoplastic synthetic resin clamped above and below via a spacer so as to leave a closed space in the molding apparatus. It means that it literally consists of two sheet-like thermoplastic synthetic resin sheets, and may also consist of a so-called parison extruded in a tubular shape from an extruder by blow molding or extrusion molding. And in the latter case, the parison is flattened to approximately the height of the spacer in advance and clamped with the spacer inserted and wrapped therein.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a molding apparatus of the present invention will be described with reference to the drawings showing a molding process of a synthetic resin hollow molding using this molding apparatus.

In FIG. 1 (a), two thermoplastic synthetic resin sheets (1) and (2) are provided with spacers (4) at their peripheral portions so as to leave a predetermined closed space (3) between them.
Clamping through (4), above both sheets (1) (2)
Is heated and softened by a heater (T), and then sandwiched between a pair of upper and lower molds (5) and (6) relatively close to each other inside the clamp position as shown in FIGS. 1 (b) and 1 (c). , The air nozzle (7) is inserted into the thermoplastic synthetic resin sheet (1), and compressed air is introduced into the closed space (3) to bring both sheets (1) and (2) into close contact with the upper and lower molds, and at the same time, Both the seats (1), () are variably forced or non-forced in the height direction by the tops (10) of the projecting pins (8) planted in the planting holes (9) of the mold (6). 2)
Is crimped to the inner wall of the other mold (5) to bond them to each other, and the outer peripheral sandwiching portion (5a) of both molds (5) and (6)
By joining the edge portions of both sheets (1) and (2) to each other with (6a), a synthetic resin hollow molded body (F) having hollow reinforcing protrusions (H) as shown in FIG. 2 is obtained. Of.

The material of the mold used in the present invention will now be described. Metals such as aluminum, aluminum-zinc alloy, cast iron, steel, etc., which are commonly used for thermoforming of general thermoplastic synthetic resins. Is applied. The material of the protruding pin implanted in the mold is the same as the material of the mold exemplified above, and a rubber elastic body having high pressure resistance and heat resistance during thermoforming, such as chloroprene rubber. Etc. are further applicable.

Furthermore, the structure of the protruding pin (8) itself is such that the upper part of the body is made of a rubber elastic body and the lower part of the body is combined with another material such as metal, or vice versa. It is also possible.

The protruding pin (8) according to the present invention is basically such that the lower part of the body is forcibly or non-forcedly variable in the height direction, and the projecting pin (8) is provided with a planting hole (9). The upper part of the body is planted in the mold (6) so that the upper part of the body is exposed on the surface of the mold (6).

Further, as a planting structure for making the state variable in the height direction, a screw provided in the lower part of the body of the projecting pin (8) and the planting hole (9) of the die (6) is used. Construction,
Further, a spring-like elastic piece or a rubber-like elastic piece is arranged between the bottom of the projecting pin (8) and the mold (6), and the elastic piece or the rubber-like elastic piece is connected through these elastic pieces. It is possible to adopt a structure in which the bottom of the protruding pin (8) made of a rubber elastic body is adhesively bonded to the planting hole (9). Needless to say, the present invention is not limited to the above-mentioned planting structure as long as the projecting pin (8) is planted in a variable state in the height direction.

An air discharge port (11) for removing air remaining in the planting hole (9) during thermoforming may be provided at the bottom of the planting hole (9) of the mold (6). Good. Further, if necessary, the end of the air outlet (11) may be connected to a suction device to forcibly remove residual air. As described above, by providing the air discharge port (11), it is possible to prevent the finish of the hollow molded body near the projecting pin (8) from being unsatisfactory and improve the finish accuracy.

Here, as compared with the conventional molding apparatus,
Whereas the conventional projection is fixedly installed integrally with the mold, the projecting pin of the present invention is such that, in the upper part of the body, the other metal that faces two thermoplastic synthetic resin sheets as molding materials is opposed. Although the two are similar in that the top part is flat and has a substantially frustoconical shape for the purpose of crimping to the wall surface of the mold, the lower part of the body is planted in the mold in a variable state in the height direction. It is basically different in that it is provided.

As described above, according to the molding apparatus of the present invention, since the mold in which the protruding pins are planted in the height direction in a variable state forcibly or non-compulsively is used, the hollow molding of the synthetic resin can be performed. Prior to or during the thermoforming, the height of the protruding pin can be adjusted very easily, and the thickness of the joint portion (h) of the synthetic resin hollow molded body (F) obtained by the thermoforming is appropriate. Can be regulated.

Next, based on FIGS. 3 (a) to 3 (d),
A specific embodiment of the protruding pin in the mold of the molding apparatus of the present invention will be described below.

Mode 1 As shown in FIG. 3A, a metal protruding pin (8A)
However, in the lower part of the trunk, the planting hole (9
(a) is planted by screwing the screws (12) and (13) together, and in the upper part of the body, two thermoplastic synthetic resin sheets as molding materials are pressed against the wall surfaces of the other opposing mold. Then, the top portion (10a) is made flat and has a substantially frustoconical shape. The height of the projecting pin (8A) is set so as to force it in the screw direction when releasing the mold without thermoforming.
The structure is such that it can be changed by rotating to the left or right and adjusted appropriately. It should be noted that a generally known rotation preventing pin (not shown) is provided on the screw portion so that the height does not change due to careless rotation of the protruding pin (8A) after the height is set.
Can also be attached or a screwing agent can be applied.

Aspect 2 In another aspect, as shown in FIG. 3B, a metal projecting pin (8B) is formed in the die (6) at the lower part of the body, and a planting hole (9b) is formed. ), And the protruding pin (8
The bottom part of B) and the mold (6) are connected via a spring-like elastic piece (B), and in the upper part of the body, the above-mentioned aspect 1 is used.
Similarly, the top portion (10b) is made flat and has a substantially frustoconical shape. The height of the projecting pin (8B) is set such that the two elastic synthetic resin sheets are pressed against the wall surface of the other die facing each other by the top portion (10b) during thermoforming. The structure is such that its height can be non-forcedly changed by the elasticity of B) and the height can be adjusted appropriately.

Aspect 3 As shown in FIG. 3C, a metal protruding pin (8C)
However, in the lower part of the torso, there is a planting hole (9
c) and is coupled between the bottom of the protruding pin (8C) and the mold (6) via a rubber-like elastic piece (G),
In addition, in the upper part of the trunk, the top portion (10c) is flat and has a substantially frustoconical shape, as in the first embodiment. And the height of the protruding pin (8C) is
While the two thermoplastic synthetic resin sheets are pressed against the wall surfaces of the other mold facing each other by the top portion (10c), the elastic force of the rubber-like elastic piece (G) non-forcedly changes the height, The structure can be adjusted appropriately.

Aspect 4 As shown in FIG. 3D, the protruding pin (8D), which is entirely made of a rubber elastic body, is fitted into the planting hole (9d) formed in the mold (6) at the lower part of the body. Protruding pin (8
In the upper part of the body, the top part (10d) has a flat shape and is substantially frustoconical in shape, which is bonded by an adhesive between the bottom part of D) and the mold (6). Form. And, the height of the protruding pin (8D) is the same as that of the two thermoplastic synthetic resin sheets during the thermoforming.
Therefore, while the pressure is applied to the wall surface of the other opposing mold, the height of the protruding pin (8D) made of a rubber elastic body is not forcibly changed by the elasticity of the protruding pin (8D) itself so that the height can be appropriately adjusted.

[0027]

As described above, according to the molding apparatus of the present invention, since the die in which the projecting pins are variably and forcibly implanted in the height direction is used, the synthetic resin hollow molding is performed. Prior to or during the thermoforming of the body, the height of the protruding pin can be adjusted very easily, and the thickness of the joint portion of the hollow molded body can be properly regulated, and the synthetic resin hollow molded body can be formed. As a result, the reinforcing effect can be enhanced. Further, there is an effect that relatively high accuracy is not required at the time of manufacturing the mold, and therefore the cost for manufacturing the mold becomes low.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a process for producing a synthetic resin hollow molded article using a molding apparatus of the present invention, FIG. 1 (a) is a state when a molding material is heated, and FIG. 1 (b) is a molding die. 1 shows a state in which the molding materials are joined and integrated, and FIG. 1C shows a state in which compressed air is introduced to perform molding.

FIG. 2 is a partially cutaway perspective view of a synthetic resin hollow molded body showing a reinforcing structure of a molded body.

3A and 3B show a mode of a projecting pin that is planted in a molding die used in the molding apparatus of the present invention. FIG. 3A is one that is planted with a screw, and FIG. FIG. 3 (c) shows the one that is planted through the elastic piece, FIG. 3 (c) shows the one that is planted through the rubber-like elastic piece, and FIG. 3 (d) shows the one that is itself a rubber elastic body.

FIG. 4 is a cross-sectional view showing a step of producing a synthetic resin hollow molded body using a conventional molding apparatus, FIG. 1 (a) shows a state when a molding material is heated, and FIG. 1 (b) shows a molding die. FIG. 1C shows a state in which molding materials are joined and integrated, and a state in which compressed air is introduced to perform molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermoplastic synthetic resin sheet 2 ... Thermoplastic synthetic resin sheet 5 ... Mold 6 ... Mold 7 ... Air nozzle 8 ... Projecting pin 9 ... Planting hole 10 ... Top 11 ... Air outlet 12 ... Screw 13 ... Screw B ... Spring-like elastic piece G ... Rubber-like elastic piece F ... Synthetic resin hollow molded article H ... Reinforcing hollow protrusion

Claims (6)

[Claims] 1. A thermoplastic resin sheet of two sheets is clamped at its peripheral portions via spacers so as to leave a predetermined closed space between them, and both sheets are heated and softened, and then at the clamp position. It is sandwiched between a pair of upper and lower molds inside, and is used for carrying out a molding method of a hollow molded body in which compressed air is introduced into the closed space to bring both sheets into close contact with the upper and lower molds. In the equipped molding equipment,
In at least one of the molds, a projecting pin for forming a reinforcing hollow protrusion of the molded body is planted on the inner surface of the mold in a variable state in the height direction, and when the two molds relatively approach each other, A molding apparatus for a synthetic resin hollow molded article, wherein the tops of the projecting pins are adapted to press both sheets against the inner wall of the other mold. 2. The molding apparatus for synthetic resin hollow molding according to claim 1, wherein the protruding pin is made of a rubber elastic body. 3. The molding apparatus for a synthetic resin hollow molded article according to claim 1, wherein the protruding pin is variably planted in the height direction by a screw between the lower part of the body and the mold. 4. The molding apparatus for a synthetic resin hollow molded article according to claim 1, wherein the projecting pin is variably planted in the height direction by an elastic piece arranged between the bottom portion and the mold. . 5. The molding apparatus for a synthetic resin hollow molded article according to claim 4, wherein the elastic body is a spring-like elastic piece. 6. The apparatus for molding a synthetic resin hollow molded article according to claim 4, wherein the elastic body is a rubber-like elastic piece.