JP2806515B2 - Molding equipment for synthetic resin hollow moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a method of manufacturing a hollow molded article made of synthetic resin, the following molding method called a double sheet molding method has been conventionally known.

That is, as shown in FIG. 5 (a), two thermoplastic synthetic resin sheets (51) and (52) are used as molding materials, and the peripheral portions thereof are interposed via a spacer (53). And clamp them from above and below with clampers (54) and (54), and place both sheets (51) and (52) in parallel and horizontal at a predetermined interval so as to leave a closed space (55) between them. To support. And both sheets (51) (52) are heated (56)
Heat is applied from above and below in (56) to soften, and compressed air is introduced into the closed space (55) between the sheets (51) and (52) from the air nozzle (57) provided in a part of the spacer (53) as appropriate. Is blown to pretension both sheets (51) and (52) in the direction away from each other. Then, in this heat-softened state, as shown in FIG. 5 (b), the two sheets (51) and (52) are placed in a pair of upper and lower molding dies (59) (6) inside the peripheral clamp position.
0), the two dies (59) and (60) are brought close to a predetermined closed position so as to be sandwiched between them, and the sheet clamping surfaces (59
a) and (60a) are sandwiched between the sheets (51) and (52), and their peripheral edges are joined and integrated. Next, as shown in FIG. 5 (c), the compressed air introduction air nozzle (61) provided on one mold (59) is advanced to operate and penetrate the one sheet (51). Then, the compressed air is inserted into the closed space (55) between the sheets (51) and (52), and compressed air of a predetermined pressure is introduced into the closed space (55) through the nozzle (61) to make the sheets (51). (52) is brought into close contact with the inner surfaces (59b) and (60b) of the cavities of both molds (59) and (60). During the introduction of this compressed air, each mold (59) (60)
In some cases, vacuum evacuation is performed by a vacuum suction mechanism (not shown) provided in the apparatus to assist the sheets (51) and (52) in the mold. Then, after cooling while maintaining the internal pressure between the two sheets, the compressed air introduction nozzle (61) is retracted to open both molds (59) and (60), and the hollow molded body is taken out.

Conventionally, in carrying out the above-described double sheet forming method, the sheets (51) and (52) are sandwiched in a state where the two dies (59) and (60) are misaligned. When,
Reduce the bonding strength between both sheets (51) (52),
In order to prevent such a situation from occurring due to poor bonding, the following misalignment preventing structure has been adopted.

That is, as shown in FIG.
A table (63) is provided on the back of (9) so as to extend outward from the clamp position, and a bed (64) is also provided on the back of the lower mold (60) so as to extend outward from the clamp position. ), The table (63) and the bet (64)
Guide pillars (65) and (66) are provided correspondingly to the opposing surfaces of the pair at positions outside the clamp position, and the positioning protrusions (66) are provided on the distal end surfaces of the upper and lower guide pillars (66).
a) is provided, and a positioning recess (65a) is provided on the distal end surface of the other guide post (65), and a mold (59) is provided.
When the sheets (60) sandwich the sheets (51) and (52), the positioning projections (65a) and the recesses (66a) are fitted with each other, thereby forming the molds (59) and (60). The sheets (51) and (52) sandwich the sheets without misalignment.

[0006]

However, in the above-described structure for preventing the displacement of the mold shown in FIG. 6, the table (63) and the bed (64) are provided on the rear side of the molds (59) and (60). And the table (63) and the bed (64) are provided with guide columns (65) and (66). The molding equipment has become very heavy and its size has also become very large, which has also made the cost of the equipment very high. Incidentally, in terms of weight, in the case where the weight of the molds (59) and (60) themselves is 500 kg and the mold size is about 1 m square, the table (63) including the guide rods (65) and (66), the bed The weight of (64) was 500-600 kg, and when these were combined, the total weight could exceed 1000 kg, and the mechanical load on the molding apparatus was very large. In addition, in terms of size, there is a problem that the size of a moldable hollow molded body is limited to a small size even though the equipment becomes large.

In addition, since the table (63) and the bed (64) have a structure protruding largely to the side, the two dies (59)
Depending on the pinching strength of the sheets (51) and (52) by the (60), that is, the mold clamping strength, the table (6
3) and the bed (64) may be deformed flexibly. Therefore, the positioning convex part (65a) and the concave part (66a) may be deformed.
), The molds (59) and (60) are misaligned with each other, and the sheets (51) and (52) are sandwiched between the molds (59) and (60). This is not necessarily a perfect structure as a means for preventing mold displacement.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention can prevent the occurrence of misalignment between upper and lower molds with high reliability, and can properly join sheets. 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 the weight and cost of the apparatus itself, and can form a compact and large-sized hollow molded body. I do.

[0009]

In order to achieve the above object, the present invention provides a method for clamping two thermoplastic synthetic resin sheets at a peripheral edge thereof through a spacer so as to leave a predetermined closed space therebetween. After heating and softening the two sheets, the sheet is sandwiched between a pair of upper and lower molds inside the clamp position on the periphery, and compressed air is introduced into a closed space between the two sheets to bring both sheets into close contact with the upper and lower molds. used in the practice of the method of molding a hollow molded article which, in the molding device provided with the upper and lower molds, at least one of the two mold located inside of the clamping position, on its outer peripheral surface, the guide piece, In a mode in which the mold protrudes from the height position of the peripheral edge clamping surface, a plurality of the two sheets are provided at intervals in the circumferential direction, and the two pieces are guided by the guide pieces in a process in which the two molds relatively approach each other.
The gist of the present invention is to provide a molding apparatus for forming a synthetic resin hollow molded body, characterized in that the two molds are sandwiched between the two molds without slippage by guiding the outer peripheral surface of the other mold by slicing through. .

[0010] In the above invention, it is preferable that an inclined surface for introduction inclined outward in the protruding direction is formed on the inner surface of the projecting side of the guide piece.

[0011]

In the above-mentioned invention, the two sheets are sandwiched between the two molds by the mold guiding action of the guide pieces without the molds being displaced.

Further, the guide piece is provided at a position which is very close to the mold, that is, the outer peripheral surface of the mold, and the other piece is positioned by the guide piece at a position which is very close to the mold, which is the outer peripheral surface thereof. In this case, the two molds can properly sandwich the sheets without misalignment even when the mold clamping strength is large.

Further, since the guide piece provided on the outer peripheral surface of one of the molds guides the outer peripheral surface of the other mold to prevent misalignment, the guide piece is lightweight,
It is possible to adopt a small-sized one, and the molding apparatus is reduced in weight and cost, and the hollow molded body is compact and large in size.

Further, the guide piece is not protruded in the entire circumferential direction of the outer peripheral surface of the mold, but is provided so as to protrude at intervals in the circumferential direction. The engagement range of the sheets is also limited to a small value, so that the resistance at the time of fastening between the dies is also limited to a low value, and the joining failure of the sheets due to insufficient fastening of the molds does not occur.

[0015] In addition, since an introduction inclined surface inclined outward in the protruding direction is formed on the inner surface of the protruding side of the guide piece, a slight mold displacement occurs when the dies are separated from each other. Even when there is a gap between the molds, the molds are naturally corrected to a state without such misalignment at the time of clamping, and the molds are smoothly fitted.

[0016]

Next, an embodiment of the present invention will be described.

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

Then, as shown in FIGS. 1 and 2,
In the lower mold (3), on the outer peripheral surface, guide pieces (6)... Project a predetermined height above the height position of the peripheral clamping surface (3a) of the mold (3). In this embodiment, a plurality of bolts (15) or 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).
While being guided by the lower mold (3).

The number of the guide pieces (6) and the mounting position in the circumferential direction depend on the outer shape of the mold (3), but at least three, and the upper mold (2) is misaligned in any direction. Instead, they are attached at intervals in the circumferential direction in a mode in which they are fitted to the lower mold (3). Specifically, mold (3)
In the case where the outer peripheral shape is 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 two or more sides, for example, a square shape as described above, it is preferable to mount it in a state where it is biased to each corner side for reasons such as preventing mold clamping failure from occurring. desirable.

These guide pieces (6) are made of a metal such as cast iron, aluminum, stainless steel or the like for strength reasons or the like. The width is set in the range of 6 to 8 mm, and the width is set in the range of, for example, 20 to 100 mm, particularly 40 to 80 mm. Also,
The protruding height of the guide pieces (6)... From the holding surface (3a) is set in a range of, for example, 3 to 40 mm, particularly 8 to 20 mm from the viewpoint of the guide function.

The guide pieces (6) are formed with an introduction inclined surface (7) which is inclined outward in the projecting direction on the inner surface of the projecting side of each of the guide pieces (6). The upper mold (2) smoothly moves each guide piece (6) in the process of fitting
... to be guided to.

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 edges of the sheets (9) and (10) as the forming material. With the spacer (11) interposed, the peripheral portion is clamped from above and below with clampers (1) and (1), and a closed space (21) is left between the sheets (9) and (10). It is supported in a parallel and horizontal manner in an aspect.

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

Next, both sheets (9) and (10) are heated and softened to a predetermined molding temperature by heaters (4) and (4).
At this time, compressed air is simultaneously introduced into the closed space (12) between the two sheets (9) and (10) from the air nozzle (11a) provided in a part of the spacer (11) to prevent free gravity deformation of both sheets. At the same time, the sheet is pretensioned.

After removing the heaters (4) and (4) while continuing this pre-stretching operation, FIG.
As shown in (b), the upper and lower dies (2) are placed on both sheets (9) and (10) inside the clamp position on the periphery thereof.
Approach (3).

In the approaching process, first, each guide piece (6)... Smashes the sheets (9) and (10) at its leading end, and thereafter, the upper mold (2) moves on its outer peripheral surface to the lower mold (3). Each guide piece (6) is guided by the inner surface on the protruding side. As a result, if there is a misalignment, the misalignment is corrected. Thereafter, as shown in FIGS. 3 (c) and 4 (a), the sheet is clamped on the peripheral wall between the molds (2) and (3). The sheets (9) and (10) are sandwiched between the portions (2a) and (3a), and the sheets (9) and (10) are joined and integrated.

Thereafter, as shown in FIG. 4 (b), the molding air nozzle (13) provided on one of the molds (2) is connected to a driving means (14) such as a driving cylinder, as shown in FIG. To move it into one of the seats (9).
Through. Subsequently, compressed air is introduced from the air nozzle (13) into the closed space (12) between the sheets (9) and (10), and the sheets (9) and (10) are formed into molding dies (2) and (3). Close to the inner surfaces (2b) and (3b) of the cavity. Then, after performing the required cooling while maintaining this internal pressure,
The 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 two sheets (9) and (10) are displaced by the two molds (2) and (3) by the mold guiding action by the guide pieces (6). It can be sandwiched without doing. Moreover, the guide pieces (6) are provided at a position very close to the mold (3), that is, the outer peripheral surface of the mold (3).
Guides the other mold (2) at a position very close to the mold (3), that is, the outer peripheral surface thereof, so that both molds (2) and (3) have a mold clamping strength. Regardless of the type, the sheet without displacement (9)
(10) It is possible to pinch each other with high accuracy. Therefore,
The sheets (9) and (10) can be reliably joined and integrated in an appropriate joining state, and a high quality hollow molded article can be molded with high reliability.

The guide pieces (6) provided on the outer peripheral surface of the lower die (3) guide the outer peripheral surface of the upper die (2) to prevent the two die (2) and (3) from being misaligned. Therefore, as the guide pieces (6), the light and small-sized guide pieces as described above can be employed, and the molding apparatus can be reduced in weight and cost, and a compact molding apparatus can be used. A hollow molded article having a large size can be formed.

Further, the guide pieces (6)... Do not protrude over the entire outer circumferential surface of the mold (3) in the circumferential direction, but are provided so as to protrude at intervals in the circumferential direction. From the guide pieces (6) ... sheets (9) (10)
The range of engagement of the sheets (9) and (10) with the sheet (9) and (10) is prevented from being poor due to a poor resistance when the molds (2) and (3) are fastened. The sheets (9) and (10) can be integrally joined with good joining strength.

In this embodiment, the guide pieces (6) are formed separately from the mold (3) in the first place, and the guide pieces (6) are attached to the mold (3) to be integrated. As a result, the size of the mold (3) can be reduced without increasing the size of the mold (3) as compared with a case where such a guide portion is provided integrally with the mold. Mold material costs can be kept low.

Further, since the introduction inclined surface (7) inclined outward in the projecting direction is formed on the inner surface of the projecting side of the guide pieces (6), the molds (2) and (3). Even when the molds are slightly misaligned in a separated state, the two molds (2) and (3) can be naturally corrected in a state where there is no such misalignment when sandwiching. Mold (2)
(3) The two can be fitted smoothly.

In the above embodiment, the lower die (3) is provided with the guide pieces (6)...
A guide piece may be attached to the upper mold (2), or a guide piece may be attached to each of the two dies (2) and (3) such that their positions are different in the circumferential direction. May be.

[0034]

As described above, the apparatus for molding a synthetic resin hollow molded article of the present invention sandwiches both sheets by the mold guiding action of the guide pieces without the two molds being displaced. Can be.

Further, the guide piece is provided at a position which is very close to the mold, that is, the outer peripheral surface of the mold, and the other piece is positioned by the guide piece at a position which is very close to the mold, which is the outer peripheral surface thereof. Therefore, the two dies can properly sandwich the sheets without deviation, regardless of the clamping strength. Therefore, the sheets can be reliably joined and integrated in an appropriate joining state, and a hollow molded body having good quality can be molded with high reliability.

Further, since the guide piece provided on the outer peripheral surface of one die is guided by the outer peripheral surface of the other die to prevent the mold from being displaced, the guide piece is of a light weight and small size. Therefore, the molding apparatus can be reduced in weight and cost, and a large-sized hollow molded article can be molded by using a compact molding apparatus. In addition, since the weight of the apparatus can be reduced in this manner, the mold changing operation can be performed safely.

Further, the guide pieces are not provided so as to protrude in the entire circumferential direction of the outer peripheral surface of the mold, but are provided so as to protrude at intervals in the circumferential direction. The biting range of the
For this reason, the resistance at the time of clamping between the dies is low, and it is possible to avoid the occurrence of the joining failure between the sheets due to the improper clamping, and to properly join and integrate the sheets.

In addition, since the introduction inclined surface which is inclined outward in the projecting direction is formed on the inner surface of the projecting side of the guide piece, the molds slightly shift when the molds are separated from each other. Even in such a case, the molds can be naturally corrected to have no such misalignment at the time of sandwiching, and the molds can be fitted smoothly.

[Brief description of the 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.

FIGS. 3A to 3C are cross-sectional views showing a process of sandwiching a sheet near a guide piece with time.

FIG. 4A is a cross-sectional side view of the apparatus in a sheet sandwiching state, and FIG. 4B is a cross-sectional side view of the apparatus during compressed air introduction.

FIGS. 5A and 5B show a general example of a double sheet forming method, wherein FIG. 5A is a cross-sectional side view showing a heat softening step, and FIG. 5B is a state in which the sheet is sandwiched by a mold. FIG. 3C is a cross-sectional side view showing a state in which compressed air is introduced.

FIG. 6 is a cross-sectional side view showing a mold displacement 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-91739 (JP, A) JP-A-6-114919 (JP, A) JP-A-3-335956 (JP, A) JP-A-3-3-35956 27922 (JP, A) JP-A-6-170936 (JP, A) JP-A-60-52056 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 49 / 42,49 / 48-49/56 B29C 33/42 B29L 22:00

Claims (2)

(57) [Claims] 1. A peripheral portion of two thermoplastic synthetic resin sheets is clamped via a spacer in such a manner as to leave a predetermined closed space therebetween, and the two sheets are heated and softened. It is used to carry out a molding method of a hollow molded body that is sandwiched between a pair of upper and lower molds inside the clamp position, and compressed air is introduced into a closed space between the two sheets to bring both sheets into close contact with the upper and lower molds. in the molding apparatus provided with the upper and lower molds, at least one of the two mold located inside of the clamping position, on its outer peripheral surface, the guide piece, the height position of the peripheral clamping surface of the mold In a mode in which a plurality of dies are provided at intervals in the circumferential direction, the two pieces are slid and broken by the guide pieces while the two dies are relatively approaching each other.
A molding apparatus for a synthetic resin hollow molded body, characterized in that both molds sandwich the two sheets without misalignment by guiding the outer peripheral surface of one of the molds. 2. The molding apparatus for a synthetic resin hollow molded article according to claim 1, wherein an inclined surface for introduction inclined outward in a projecting direction is formed on an inner surface of the projecting side of the guide piece.