JPH1158504A - Manufacture of synthetic resin hollow structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a synthetic resin hollow structure, which is simpler than its conventional method by contriving the improvement of workability and the elimination of processes, and at the same time, manufacture the synthetic resin hollow structure having no through mark of a compressed air introducing nozzle. SOLUTION: By piercing a compressed air introducing nozzle 9 equipped with the product forming cavity 11 of upper and lower molds B1 and B2 or a sub-chamber forming part provided adjacent to the cavity in a sheet 2 so as to introduce compressed air between sheets 1 and 2 under the condition that the two thermoplastic synthetic resin sheets 1 and 2, between which a separator 3 is inserted to be pinched, are pinched between the upper and the lower molds B1 and B2, the sheets are brought into close contact with the inner surface of the cavity 11 and, in addition, the sheet piercing with the nozzle 9 is carried out under the condition that the sheets are attracted under vacuum to the mold B2 having the nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a synthetic resin hollow structure, and more particularly, to a method of arranging two thermoplastic synthetic resin sheets opposed to each other, sandwiching them between upper and lower molds, and compressing the sheets. The present invention relates to a method of forming a hollow structure by expanding a sheet by introducing air, bringing the sheet into close contact with an inner surface of a cavity, and shaping the sheet along the inner surface of the cavity.

[0002]

2. Description of the Related Art Conventionally, as a method for producing such a synthetic resin hollow structure, a method called clamshell molding, double sheet molding, sheet blow molding or the like is known. In this method, the upper and lower two thermoplastic synthetic resin sheets are clamped via a spacer at a peripheral portion in a manner to leave a predetermined closed space therebetween, and the two sheets are heated and softened. , Sandwiched between a pair of upper and lower molds inside the clamp position, the sheets are joined and integrated at their peripheral edges, and compressed air is introduced into a closed space between the two sheets to put both sheets on the upper and lower mold inner surfaces. In order to introduce the compressed air into the closed space, the compressed air introducing nozzle provided in one mold is usually penetrated through the sheet and inserted into the closed space between the two sheets. By doing that.

[0003] When the compressed air introduction nozzle is made to penetrate the sheet, the metal is provided with the nozzle so that the nozzle can be surely penetrated and inserted into the closed space between the two sheets. A method has been proposed in which the sheet is vacuum-sucked on the mold side, and in this vacuum-sucked state, the nozzle is penetrated through the sheet. (Japanese Unexamined Patent Publication No. 8-80562
No.)

[0004]

However, in the above-mentioned conventional method, the two upper and lower thermoplastic synthetic resin sheets are overlapped with each other with a peripheral portion interposed by a spacer in such a manner that a predetermined closed space is left therebetween. This clamping work is troublesome and troublesome.

Further, when both sheets are heated and softened, the softened sheets inevitably become slack, and especially when the height of the closed space between the two sheets is small, the two sheets come into contact with each other and are fused. In order to prevent this, an air nozzle is provided in a part of the spacer, and when the sheet is heated and softened, compressed air is introduced from the air nozzle into a closed space between the two sheets, thereby preserving the sheet. It is necessary to take measures such as tensioning. Moreover, in order to introduce the compressed air into the closed space to pre-stretch the sheet, the contact portion between the sheet and the spacer must be airtight, so that the structure becomes complicated and precision is required.

[0006] In addition, when the sheet is vacuum-sucked to the mold side where the nozzle is provided, and the nozzle is penetrated through the sheet in this vacuum-sucked state, if the closed space is tightly closed, the nozzle is originally required. The sheet on the side that must be shaped by being in close contact with the mold on the opposite side to the mold on which the nozzle is provided is also sucked by the mold side on which the nozzle is provided, so the nozzle is placed between the sheets. Not only is it difficult to insert into the closed space, but also because it is preformed into a shape opposite to the original shaping shape, there is a problem that the shape does not come out cleanly. Therefore, when vacuum suction is performed, compressed air is introduced from the air nozzle into the closed space, and the sheet on the side that must be shaped in close contact with the mold opposite to the mold on which the nozzle is originally provided is not sucked. Thus, a step of increasing the internal pressure of the closed space is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional circumstances, and has as its object the purpose of which is to simplify a clamping operation and to provide a pretension for preventing fusion of sheets during heating and softening of the sheets. When vacuum suctioning the sheet to the mold side where the nozzle is provided to penetrate the nozzle into the sheet, it is also necessary to introduce compressed air into the closed space between the sheets and apply pressure inside Another object of the present invention is to provide a method for manufacturing a synthetic resin hollow structure which is simpler than a conventional method.

[0008]

In order to achieve the above object, a method for manufacturing a synthetic resin hollow structure according to the present invention comprises the steps of: A sandwich-like molding material in which a sheet-like separator that is a material that does not fuse to both of these sheets and that has air permeability and good resin permeability only under pressure is sandwiched between synthetic resin sheets. After heating the molding material to soften the two sheets, between the pair of upper and lower molds, approach one of the molds, and vacuum-suction one sheet into the one mold. In this suction state, the compressed air introduction nozzle provided in the one mold is penetrated through one of the sucked sheets, the leading end is inserted between the two sheets, and the mold is clamped to close both sheets. Between the molds and pressurize. Compressed air is introduced between the two sheets through a compressed air introduction nozzle to form the two sheets in close contact with the inner surfaces of the upper and lower dies. The resin is permeated into the separator, and the two sheets are fused and joined to the same body by the resin permeated into the separator.

According to a second aspect of the present invention, the separator has air permeability in all directions, and the mold provided with the compressed air introduction nozzle is adjacent to the product molding cavity. A sub-molding portion, a groove communicating the sub-molding portion and the cavity is provided, and in the sub-chamber molding portion, the compressed air introduction nozzle is penetrated through a sheet, and a tip thereof is inserted between the two sheets. It is characterized by doing.

[0010]

According to the first aspect of the present invention, there is provided:
In the invention of the above, between the upper and lower two synthetic resin sheets,
Since a separator made of a material that is not fused is inserted between these two sheets, the lower sheet sags with the softening of the sheet when the sheet is heated and softened, whereas the upper sheet is supported by the separator and sags. There is no spontaneous space between sheets. Therefore, unlike the conventional method, it is not necessary to clamp the two sheets by overlapping them with a spacer interposed therebetween at a predetermined closed space between the two sheets. Therefore, in the method of the present invention, the operation of the clamp is simplified as compared with the conventional method, and the workability is improved.

Further, the separator has good resin permeability only under a pressurized pressure, and the resin hardly penetrates in a normal state. Therefore, two sheets softened by heating come into contact with each other via the separator. Also, there is no possibility that the sheets are fused together. Therefore, in the method of the present invention, unlike the conventional method, when the sheet is heated and softened, it is not necessary to take measures such as introducing compressed air between the sheets and pre-stretching so that the sheets do not contact each other. , Thereby simplifying the process.

In addition, since compressed air is not introduced between the sheets and pretension is performed as described above, a special structure, tool, or part for maintaining the airtightness between the sheets at the peripheral portion is not provided. There is no need to simply hold the sheet around the periphery with a clamp. And, in this way, the method of simply holding the peripheral portion of the sheet with a clamp is combined with the fact that the separator has air permeability, and in order to allow the nozzle for introducing compressed air to penetrate the sheet, the nozzle must be When vacuum-sucking the sheet to the mold side provided, air can be introduced into the space between the sheets via the separator. Therefore, without introducing air between the sheets by artificial means, without increasing the internal pressure between the sheets,
Even the sheet on the side that must be shaped by closely contacting the mold opposite to the mold where the nozzle is originally provided,
The space between the sheets can be reliably held without being sucked by the mold having the nozzle.
Therefore, according to the present invention, the pressurized air introducing nozzle can be reliably and accurately inserted between the sheets. In addition, the vacuum suction prevents the sheet on one side from being preformed into an inverted shape from the original shape before shaping by the introduction of compressed air, which is also effective for clean shape shaping. .

According to the second aspect of the present invention, a groove is provided in a part of the sheet holding portion of the mold so as to connect the sub-chamber forming portion and the product forming cavity. Even after the mold is clamped, the mold clamping pressure does not act on the molding material in the groove portion, and the resin does not penetrate into the separator in this portion. Therefore, the compressed air introduced into the sub-chamber from the sub-chamber formed adjacent to the molding part of the hollow structure does not penetrate the resin between the upper and lower sheets in the molding part of the hollow structure. It is introduced through the fiber voids of the part of the separator, whereby the sheet is shaped and the hollow structure is formed. Therefore, the hollow structure manufactured by the method of the present invention has no trace of the compressed air introduction nozzle.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 to 7, reference numeral A denotes a molding material, and B1 and B2 denote a pair of upper and lower dies for molding the molding material A into a hollow structure C having a desired shape. The molding material A is composed of two synthetic resin sheets 1 and 2 that can be heat-fused to each other as a base material, and a separator 3 sandwiched between the two sheets 1 and 2. .

The two sheets 1 and 2 are not particularly limited as long as they are two synthetic resin sheets which can be heat-sealed to each other, and are optional depending on the use of the hollow structure C. Materials are selected and used, but generally, ABS, AE
S, PS, PP, etc. formed into a sheet by extrusion, or PP with glass fiber formed by papermaking
Sheets are used. These sheets 1 and 2 will become clear in the following description, but they need to be non-breathable in order to shape them. On the other hand, since the glass fiber-containing PP sheet often has air permeability and cannot be sufficiently shaped as it is, it is used by laminating an air-impermeable film or the like.

The sheets 1 and 2 may be made of the same material in combination, or of course, may be made of different materials as long as they can be thermally fused to each other. The combination can be selected according to the application. In addition, it is optional that both sheets 1 and 2 have the same thickness depending on the shape and application of the hollow structure C, or that one is thicker than the other, but both have a thickness of several millimeters. It is desirable to do. Further, it is of course arbitrary to change the colors of the two sheets 1 and 2 according to the use of the hollow structure C.

On the other hand, when the above-mentioned two sheets 1 and 2 are heated and softened during the formation of the hollow structure C, the separator 3 is formed on the two sheets 1 and 2 so as not to be fused. The separator 3 is used to maintain the separated state.
No heat-fusing property for 2, having air permeability,
At least under normal pressure, it is difficult for the resin to penetrate, but it is necessary that the resin easily penetrates by applying pressure, and it is more preferable that the resin be flexible or easily loosen or be separated. The separator 3 is made of, for example, a nonwoven fabric such as a polyester material, glass or P
A woven fabric such as an ET triaxial fabric, a spun bond, or the like is used, but the material and configuration thereof are not particularly limited as long as the material is a thin sheet satisfying the above requirements.

The separator 3 is composed of two upper and lower sheets 1,
The two sheets 2 and 1 are fixed in advance to one or both of the surfaces facing each other, or are simply interposed between the two sheets 1 and 2 without being fixed to the sheets 1 and 2.
Which method is to be selected is optional, but when another component or member is inserted into the hollow portion 4 of the hollow structure C to be manufactured, or when the hollow portion 4 is to be used as a gas or liquid passage. In this case, it is more convenient to fix the separator 3 to the sheet 1 or 2 in advance, because later processing becomes easier. The method of fixing the separator 3 to the sheets 1 and 2 is not particularly limited, but if the separators 3 are laminated at the time of extrusion molding of the sheets 1 and 2, the fixing can be easily and reliably performed.

The molding material A has a peripheral portion formed by a clamper 5.
, And are arranged between the upper and lower molds B1 and B2, and are heated from both upper and lower surfaces to a predetermined molding temperature by the heater 6 to soften the sheets 1 and 2. At this time, when the separator 3 is fixed to one sheet (for example, 1), it is preferable that the sheet 1 on which the separator 3 is fixed is heated upward. For heating the molding material A, it is optional to take any heating method of non-contact heater heating and contact heater heating.

The two sheets 1 and 2 accompanying the softening by heating described above.
Although the resin melts, the molten resin cannot penetrate into the separator 3 as it is, and therefore the molten resin of the sheets 1 and 2 is not hindered by the separator 3 and mixed and integrated. Fusion of 1 and 2 is prevented,
Both sheets 1 and 2 maintain a separated state.

However, when a woven fabric is used as the separator 3, if the weave is too large, the molten resin of the sheets 1 and 2 penetrates into the weave when the sheets 1 and 2 are softened by heating, and the sheets 1 and 2 are separated from each other. Because of the fusion, the size of the weave is
It is necessary that the size be such that the molten resin cannot penetrate into the texture unless pressed in a molding step described below. For example, 3
In the case of framed fabric, if the thickness of the braided fabric is 0.15 mm and the length of one side of the weave is 5 mm, or if the thickness is 0.3 mm and the length of one side of the weave is 10 mm, heat the fabric. Two sheets 1 during softening
2 can be used without fusing, but if the thickness is 0.3 mm and the length of one side of the weave is 20 mm, the two sheets 1 and 2 are fused during heat softening and cannot be used. Therefore, when the separator 3 is a woven fabric, it is preferable that the thickness is 0.3 mm and the length of one side of the weave is about 10 mm.

By the above heating, the sheets 1 and 2 are softened,
Accordingly, the central portion of the lower sheet 2 hangs down due to its own weight, but the upper sheet 1 is held in a substantially horizontal state while being supported from below by the separator 3. A space 7 is formed between the two sheets 1 and 2 without a spacer intervening.

After the sheets 1 and 2 have softened to the extent necessary for molding, the heater 6 is then moved and removed, the lower mold B2 is raised to approach the molding material A, and the lower sheet 2 Contact in close contact. The lower mold B2 is provided with a compressed air introduction nozzle 9 communicating with a compressed air supply source 8. The nozzle 9 is moved forward and backward by a suitable driving means (not shown) such as a driving cylinder. The mold B2 is activated and projects from the inner surface of the cavity 10 of the mold B2 in the forward state.

The upper and lower dies B1, B2 are provided with vacuum suction means. That is, the upper and lower molds B1 and B2 have a plurality of vacuum suction holes opened on the inner surfaces of the cavities 10 and 11, respectively.
12 and 13 are formed, and vacuum suction is performed by a vacuum pump 14. The vacuum suction means includes a valve 1
The upper and lower dies B1 and B2 can be operated independently by the operations of 5, 16 and the like. Then, in a state where the lower mold B2 is in close contact with the molding material A in which the sheets 1 and 2 have softened, the vacuum suction means of the lower mold B2 is operated, and the lower sheet B2 is operated. Apply suction force to 2.
This vacuum suction is most preferably performed so that the lower sheet 2 is in close contact with the inner surface of the cavity 10 of the lower mold B2. It may be performed so as to be drawn close to the inner surface of the cavity 10 of the mold B2.

When a suction force acts on the lower sheet 2 by the vacuum suction, air is sucked from the outside through the separator 3 into the space 7 between the sheets 1 and 2 due to the air permeability of the separator 3. The pressure in the space 7 does not drop, and the upper sheet 1 is not sucked by the lower mold B2. And this lower mold B2
In the vacuum suction state, the compressed air introduction nozzle 9 is moved forward to penetrate the lower sheet 2, and the tip is inserted into the space 7 formed between the upper and lower sheets 1 and 2. At this time, the lower sheet 2 is connected to the lower mold B2 as described above.
, And the nozzle 9 is urged against the advancing force of the nozzle 9 in the opposite direction and is tensed, so that the nozzle 9 can be reliably and smoothly penetrated through the lower sheet 2. .

Subsequently, the upper mold B1 is lowered, the molds B1 and B2 are clamped while applying a predetermined molding pressure, and the molding material A is clamped at the sheet clamping portions 17 and 18 around the periphery thereof. The compressed air is injected into the space 7 between the upper and lower sheets 1 and 2 of the molding material A from the compressed air introducing nozzle 9 at the same time. During the introduction of the compressed air between the upper and lower sheets 1 and 2, the vacuum suction of the lower mold B2 is continued, and the operation of the vacuum suction means on the upper mold B1 side is also started. Perform suction.

Thus, between the sheet sandwiching portions 17 and 18 of the dies B 1 and B 2, the molding resin causes the molten resin of the two sheets 1 and 2 to move from the fiber gap of the separator 3 into the separator 3 due to the mold clamping pressure. , And are fused to the same body to form a joint 19, and compressed air into which the two sheets 1 and 2 are injected in the cavity portions 10 and 11 surrounded by the sheet holding portions 17 and 18. As a result, the hollow portion 4 is formed in such a manner as to be in close contact with the inner surfaces of the cavities 10 and 11 and along the inner surfaces of the cavities 10 and 11.

When the separator 3 is not fixed to the upper sheet 1 at the time of shaping by the introduction of compressed air, as shown in the drawing, portions other than the portions sandwiched between the sheet sandwiching portions 17 and 18 of the dies B1 and B2 are used. Since the separator 3 and the sheets 1 and 2 are separated from each other, there is no possibility that the presence of the separator 3 may hinder the shaping of the sheet, and the separator 3 is temporarily fixed to the upper sheet 1 by means such as lining. Even in this case, when it is flexible or extensible, it is appropriately deformed or spread, and when it is easily loosened or divided, it is loosened or divided to form the sheets 1 and 2. There is no inhibition.

Although it is not always necessary to suction the upper mold B1 by vacuum at the time of shaping by introducing compressed air, by performing this, the air pocket in the cavity 11 is eliminated, and the sheet 1 is removed from the cavity 11 The hollow structure C, which is a molded product, can be securely adhered to the inner surface.
In addition, it is possible to provide a more precise shape and improve the cooling efficiency of the product.

Next, after performing the required cooling while maintaining this internal pressure, the opening valve 20 connected to the compressed air introduction nozzle is opened to release the pressure in the hollow portion 4, and the inside of the hollow portion 4 is set to the atmospheric pressure. Equivalent. At this time, the pressure inside the hollow portion 4 may become negative pressure due to a sudden pressure reduction, and the molded product C may be deformed. Therefore, it is desirable to continue the vacuum suction of the molds B1 and B2. . After the internal pressure of the hollow portion 4 is released, the nozzle 9 for introducing compressed air is moved backward and the dies B1, B2
Is opened to take out the formed hollow structure A and perform necessary trimming. At the time of opening the mold, it is desirable that only the vacuum suction of the upper mold B1 be stopped and the vacuum suction of the lower mold B2 be continued. Thereby, the molded article hollow structure C
Is securely left on the lower mold B2 side and is not attached to the upper mold B1 and is not lifted, so that deformation at the time of mold opening can be prevented. Thus, the hollow structure C having a required shape is obtained.

Next, another embodiment of the present invention (referred to as a second embodiment) will be described with reference to FIGS. This second embodiment is different from the above-described embodiment (referred to as the first embodiment) in that the compressed air introduction nozzle 9 is inserted through the sheet 2 in a portion to be the hollow portion 4 of the structure C. By doing so, the compressed air is directly introduced into the portion, whereas the upper and lower two sheets 1,
2 using the air permeability of the separator 3 sandwiched between
The compressed air is indirectly introduced from the side through the separator 3 into the hollow portion 4
Specifically, a hollow sub-chamber 21 is formed adjacent to the side of the part to be the product structure C, and the compressed air introduction nozzle 9 is connected to the sheet 2 at the formation part 22 of the sub-chamber 21. The compressed air introduced between the upper and lower sheets 1 and 2 is inserted between the upper and lower sheets 1 and 2 so that the compressed air introduced between the upper and lower sheets 1 and 2 becomes the hollow part 4 of the hollow structure C via the separator 3. In between the upper and lower sheets 1 and 2.

That is, in this embodiment, the sheet clamping portion 18 provided around the product molding cavity 10 in the lower mold B2 is formed slightly wider than that of the lower mold B2 in the first embodiment. Then, a sub-chamber forming portion is provided on the upper surface of the sheet holding portion 18.
The sub-chamber forming section 22 and the product forming cavity 10 are connected to each other by providing a groove 23 on the upper surface of the sheet holding section 18.

The nozzle 9 for introducing compressed air is provided with a cavity for molding a product as in the first embodiment.
Instead of being provided in the sub-chamber 10, the sub-chamber forming section 22 is provided. Further, similarly to the product molding cavity 10, a plurality of vacuum suction holes 12 'opened on the inner surface thereof are formed in the sub-chamber molding portion 22 as well. The vacuum pump 14 that communicates with the vacuum suction hole 12 ′ can share the vacuum pump that communicates with the vacuum suction hole 12 of the product forming cavity 10. The shape of the sub-chamber forming portion 22 is arbitrary, and the size may be overwhelmingly smaller than the molded product forming cavity 10 of the lower mold B2.

Thus, in the second embodiment, molding is performed using the above-described dies B1 and B2 in substantially the same procedure as in the first embodiment. The procedure will be described below, but in order to avoid repetition of the description and simplify the description, the manufacturing process is shown in the drawings, and the same reference numerals are given to the same elements as those in the first embodiment. However, detailed description is omitted.
First, a molding material A constituted by sandwiching a separator 3 between two sheets 1 and 2 made of a thermoplastic synthetic resin is heated to soften the upper and lower sheets 1 and 2 (FIG. 9). The material A and the lower mold B2 are brought close to each other, and in a state where both are brought into close contact with each other, the vacuum suction means of the lower mold B2 is operated to apply a suction force to the lower sheet 2 of the molding material A. (Fig. 10).

Then, in the vacuum suction state of the lower mold B2, the compressed air introduction nozzle 9 is operated forward to project from the bottom surface of the sub-chamber forming portion 22. As a result, the nozzle 9 penetrates the lower sheet 2 that is in close contact with the bottom surface of the sub-chamber forming section 22, and its tip is inserted between the upper and lower sheets 1 and 2 (FIG. 11).

Subsequently, the upper and lower molds B1, B2 are clamped while applying a predetermined molding pressure, and the molding material A is sandwiched between the sheet clamping portions 17, 18 inside the clamp position on the periphery thereof. At the same time, compressed air is injected between the upper and lower sheets 1 and 2 of the molding material A in the sub-chamber molding section 22 from the compressed air introducing nozzle 9. Due to the introduction of the compressed air, first, the upper and lower sheets 1 and 2 expand in the sub-chamber molding portion 22, and are formed in close contact with the inner surface of the sub-chamber molding portion 22 and along the inner surface. The chamber 21 is formed.

At this time, by closing the molds B1 and B2,
In the molding material A, the molten resin of the upper and lower sheets 1 and 2 is pressed between the sheet sandwiching portions 17 and 18 by the mold clamping pressure.
The fibers 19 penetrate into the separator 3 from the fiber gap and are fused to the same body to form a joint 19, but a part of the sheet sandwiching parts 17, 18 has a sub-chamber forming part 22 and a product forming cavity 10 Is formed, the mold clamping pressure does not act on the molding material A in this groove 23, and the separator 3
Does not penetrate the resin. Therefore, the compressed air introduced between the sheets 1 and 2 in the sub chamber forming section 22
After the sheets 1 and 2 are expanded in the above, the resin flows between the upper and lower sheets 1 and 2 in the product forming cavity 10 through the fibers of the separator 3 where the resin has not penetrated. The two sheets 1 and 2 are expanded, brought into close contact with the inner surfaces of the cavities 10 and 11, and shaped into a shape along the inner surfaces to form the hollow portion 4 of the hollow structure C (FIG. 12).

Thereafter, after the required cooling is performed while maintaining the internal pressure, the nozzle 9 for introducing the compressed air is moved backward and the dies B1 and B2 are opened (FIG. 13) to take out the molded product C '. The sub-chamber 22 is cut off from the molded product C 'by performing appropriate trimming to obtain the hollow structure C (FIG. 15). Although the synthetic resin hollow structure C obtained by adopting this embodiment has a portion 24 where the upper and lower sheets 1 and 2 are not joined to a part of the joining portion 19, a nozzle for introducing compressed air into the product is provided. No trace of 9 can be made. Therefore, the use of the product is not limited, and versatility can be obtained as a method for manufacturing a synthetic resin hollow structure.

In this embodiment, the compressed air introduction nozzle 9 is advanced by a suitable driving means such as a cylinder, and protrudes from the inner surface of the sub-chamber forming portion 22.
It is not always necessary to make the sheet 2 penetrate,
It is also possible to provide in advance the mold B2 integrally with the mold B2 in a state of protruding from the bottom of the sub-chamber forming section 22 in advance. When the compressed air introduction nozzle 9 is provided integrally with the mold B2 in a state of being protruded in advance, a hole that the nozzle 9 penetrates through the sheet 2 and opens in the sheet 9 by suction of the sheet 2 to the inner surface of the mold B2 generally has a hole. Although it is considered that the size of the nozzle becomes larger than the diameter of the nozzle, there is a possibility that the introduced compressed air may leak from the hole. However, in this embodiment, since the sub-chamber forming portion 22 in which the nozzle 9 is provided is small, the hole edge of the hole is It adheres strongly to the inner surface of the molded part 22, and air does not leak from this hole.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a method for manufacturing a synthetic resin hollow structure of the present invention, and is a cross-sectional view of equipment for carrying out the method of the present invention.

FIG. 2 is a cross-sectional view showing a heat-softened state of a molding material.

FIG. 3 is a sectional view showing a vacuum suction state.

FIG. 4 is a cross-sectional view showing a state in which the compressed air introduction nozzle is stabbed by clamping the mold.

FIG. 5 is a cross-sectional view showing a state in which compressed air is introduced for shaping.

FIG. 6 is a cross-sectional view showing a state in which the mold is opened after completion of molding.

FIG. 7 is a sectional view showing a state where a product is obtained by trimming.

FIG. 8 shows a second embodiment of the method for producing a synthetic resin hollow structure of the present invention, and is a cross-sectional view of equipment for carrying out the method of the present invention.

FIG. 9 is a sectional view showing a heat-softened state of a molding material.

FIG. 10 is a sectional view showing a vacuum suction state.

FIG. 11 is a cross-sectional view showing a state in which the compressed air introduction nozzle has been inserted by clamping the mold.

FIG. 12 is a cross-sectional view showing a state in which compressed air is introduced to shape the shape.

FIG. 13A is an enlarged sectional view showing a main part when compressed air is introduced, and FIG. 13B is a sectional view taken along line (b)-(b) of FIG.

FIG. 14 is a sectional view showing a state in which the mold is opened after the completion of molding.

FIG. 15 is a cross-sectional view showing a state in which a sub-chamber portion is cut off by trimming to obtain a product.

FIG. 16 is a perspective view showing a main part of the manufactured synthetic resin hollow structure.

[Explanation of symbols]

 A: Molding material B1: Mold (upper) B2: Mold (lower) C: Hollow structure 1: Synthetic resin sheet (upper) 2: Synthetic resin sheet (lower) 3: Separator 4: Hollow structure Hollow part 7: Space between sheets 9: Nozzle for introducing compressed air 10: Cavity 11: Cavity 17: Sheet holding part 18: Sheet holding part 19: Joint of hollow structure 21: Sub chamber 22: Sub chamber Chamber formation part 23: groove

Claims (2)

[Claims] 1. A material which is not fused to both upper and lower synthetic resin sheets which can be thermally fused to each other, and which has air permeability and good resin permeability only under pressure. To form a sandwich-shaped molding material by sandwiching a sheet-shaped separator having, and heating the molding material to soften both sheets, between a pair of upper and lower molds,
By approaching one of the molds, one of the sheets is vacuum-sucked to the one of the molds, and in this suction state, the compressed air introduction nozzle provided in the one of the molds penetrates through the one of the sucked sheets. And insert the tip between both sheets,
Clamp the mold, sandwich both sheets between the molds and press,
Thereafter, compressed air is introduced between the two sheets through the compressed air introduction nozzle to form the two sheets in close contact with the inner surfaces of the upper and lower molds, while the pressurization is applied to portions other than the hollow portion. A method for producing a synthetic resin hollow structure, characterized in that the molten resin of both sheets is permeated into a separator by the above method, and both sheets are fused and joined to the same body by the resin permeated into the separator. 2. The method according to claim 1, wherein the separator has air permeability in all directions, and the mold provided with the compressed air introduction nozzle has a sub-molding portion adjacent to a product molding cavity; With a groove to communicate with the cavity,
2. The method for manufacturing a synthetic resin hollow structure according to claim 1, wherein in the sub-chamber forming section, the compressed air introducing nozzle is penetrated through a sheet, and a tip of the nozzle is inserted between the sheets.