JPH049655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for preventing sagging of a resin sheet, and more particularly, when supplying a heated and softened resin sheet to a mold forming machine that is a vacuum forming machine or a pressure forming machine, The present invention relates to a device for preventing a resin sheet from sagging due to its own weight.

Conventionally, various thin-walled containers have been mass-produced from thermoplastic resin sheets by vacuum forming or pressure forming. When using a thermoplastic resin sheet with relatively low melt strength (tension) such as polypropylene, the resin sheet sags due to its own weight, making it difficult to properly feed the molding machine, resulting in a molded product. There were drawbacks such as uneven wall thickness and wrinkles in the molded product. In addition, not only polypropylene but also resin sheets containing relatively large amounts of inorganic fillers (inorganic filler-containing sheets) generally do not have good moldability, so the molding temperature must be relatively high. However, when such an inorganic filler-containing sheet is heated to an appropriate molding temperature, it suffers from the same drawbacks as polypropylene and the like. Furthermore, molding machines that are integrated with resin sheet extrusion molding machines have recently been attracting attention from the viewpoint of saving energy and improving uniformity of resin sheet temperature by eliminating the need to reheat the resin sheet. also had the same drawbacks as mentioned above.

By the way, as a device to prevent the resin sheet from sagging, there is a device equipped with a circulating resin sheet receiving belt (Japanese Unexamined Patent Publication No. 57-96816), and a continuous line running the bottom surface of the resin sheet just before the molding machine. A sagging prevention device in which a supporting device is arranged in a continuous or intermittent linear manner has already been proposed (Japanese Patent Application Laid-Open No. 57-75818).
The structure is linked to the intermittent running clamp chain of the resin sheet, and the mechanism as a whole is extremely complicated, and furthermore, it is extremely difficult to cool the contact portion with the resin sheet.

An object of the present invention is to provide a resin sheet sagging prevention device that has a simple structure and can be easily configured to cool the contact portion with the resin sheet.

Therefore, the present invention provides a plurality of support wheels that support the lower surface of the heat-softened resin sheet, and these support wheels are arranged at predetermined intervals from each other in the longitudinal direction on a support shaft in a direction perpendicular to the feeding direction of the resin sheet. fitted so as to be rotatable independently, and a plurality of the support shafts are arranged at predetermined intervals along the resin sheet feeding direction, and are not particularly interlocked with the resin sheet feeding mechanism;
Moreover, the above-mentioned object is achieved by configuring the cooling heat medium to flow through each of the support shafts.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a molding apparatus to which an embodiment of the resin sheet sag prevention device according to the present invention is applied. In the figure, a resin sheet 11 is made of a thermoplastic resin such as polypropylene, and if necessary, an inorganic filler or the like is mixed therein. Further, this resin sheet 11 is held between feed rollers 12 and is intermittently fed from the left side to the right side in the figure at a predetermined timing, and is held by gripping means (not shown) on both sides of the resin sheet 11 in the width direction. Appropriate tension is applied to the resin sheet 11 in its width direction by the gripping means, and the resin sheet 11 is transported rightward in the figure.

A droop prevention device 13 according to the present invention is arranged on the side of the feed roller 12 in the transfer direction. This drooping prevention device 13 has a plurality of support wheels 14, and these support wheels 14 are attached to a support shaft 15 fixed in a direction perpendicular to the feeding direction of the resin sheet 11, as shown in FIG. They are attached at predetermined intervals in the longitudinal direction of the support shaft 15. In addition, the support shaft 15
are arranged in plural at predetermined intervals along the feeding direction of the resin sheet 11.

As shown in an enlarged view in FIG. 3, the support ring 14 has a substantially diamond-shaped cross section along the radial direction, and is shaped like a soroban bead. Each of these support wheels 14 is rotatably fitted onto a support shaft 15, and a collar (spacer) 16 of a predetermined size is similarly placed between each of the support wheels 14.
5, and the collar 16 fitted in this manner positions the support ring 14 at intervals along the longitudinal direction of the support shaft 15.

The support shaft 15 has a round tubular shape, and a cooling pipe 18 penetrates inside thereof, and a cooling heat medium 1 such as cooling water is inserted into the cooling pipe 18, which is a heat medium circulation means.
9 is distributed.

Note that resin sheets 11 are disposed in the left and right directions in FIG.
A roller-shaped auxiliary roller 21 that rotatably supports the lower surface side of the roller is provided. In addition, each support shaft 1
The mounting positions of the support wheels 14 in 5 are configured to be at the same position along the width direction of the resin sheet 11.

Heaters 22 are provided on the upper and lower sides of the droop prevention device 13 in FIG. 1, respectively, and the heaters 22 heat the resin sheet 11 to a suitable temperature for molding. Furthermore, a mold forming machine 23 is disposed on the feeding direction side of the droop prevention device 13, which molds the resin sheet 11 heated and softened by the heater 22. The molding machine 23 has a female mold 24 and a plug 25 that extend toward each other so as to be able to clamp the resin sheet 11 from the upper and lower surfaces, and further includes a clamp plate 26 that clamps the heat-softened resin sheet 11 to the end surface of the female mold 24. have. With such a molding machine 23, a molded portion 11A having the same shape as the cavity portion 24A is continuously molded on the resin sheet 11. Note that, as shown in FIG. 2, the contact portion between the resin sheet 11 and the support ring 14 is located at a position approximately in the middle between the molded portions 11A, and the molded portions 11A are punched out from each other. It is designed to become the punching residue when separated.

According to this embodiment, it is possible to prevent the resin sheet 11 heated and softened by the heater 22 from sagging, and furthermore, since the support wheel 14 is not interlocked with the feeding mechanism for the resin sheet 11, the structure is simplified. It is extremely simple. Furthermore, since the support wheels 14 are rotatable independently of each other, the sheet 11 is not meandered or wrinkled. In addition, since the support shaft 15 does not have a rotating structure, there is no need to use a rotating joint when circulating the cooling heat medium 19 through the cooling pipe 18 provided in the support shaft 15, and from this point of view, the structure is simple. It can be made into something.

In addition, a cooling heat medium 19 is circulated inside the support shaft 15 via a cooling pipe 18, and thereby,
Overheating by the heater 22 of the droop prevention device 13 can be prevented, and the support ring 14 will not be heated by the resin sheet 11, so that adhesion of the resin sheet 11 can be prevented.

In addition, in implementation, the support wheel 14 does not necessarily have to be in the shape of an abacus bead, but if it is in the shape of an abacus bead, the attachment state of the support wheel 14 to the support shaft 15 can be kept stable (no wobbling), and The contact area between the support ring 14 and the resin sheet 11 can be minimized. Further, as the heat medium flow means, instead of the cooling pipe 18, a hole in the support shaft 15 may be used to directly flow the cooling heat medium 19 into the hole. Furthermore, instead of using the collar 16, the support wheel 14 may be positioned by, for example, providing a shallow groove along the circumferential direction on the outer periphery of the support shaft 15, and installing the support wheel 14 in this groove. .

Furthermore, the resin sheet 11 may be supplied from a raw sheet, or
The resin sheet 11 extruded from the sheet extrusion molding machine may be directly supplied to the molding machine 23. In such a case, the heater 22 may not be particularly required.

As described above, according to the present invention, the structure is simple,
It is possible to provide a resin sheet sagging prevention device that can be easily configured to cool the contact portion with the resin sheet.

[Brief explanation of drawings]

FIG. 1 is a front view showing a schematic configuration of a molding apparatus for resin containers to which an embodiment of the resin sheet sagging prevention device according to the present invention is applied, FIG. 2 is a plan view of the embodiment, and FIG. The figure is an enlarged sectional view of the main part of the embodiment. 11...Resin sheet, 13...Dragging prevention device,
14... Support wheel, 15... Support shaft, 16... Collar, 18
...Cooling pipe, 19...Heat medium for cooling, 22...Heating machine, 23...Mold forming machine, 11A...Molding section.

Claims (1)

[Claims] 1. A sagging prevention device for a resin sheet that is heated and softened and supplied to a molding machine, and is provided with a plurality of support wheels that support the lower surface of the resin sheet, and these support wheels are used to prevent the resin sheet from being fed. The support shafts are rotatably mounted independently of each other at predetermined intervals in the longitudinal direction of the support shafts fixed in a direction perpendicular to the direction, and the support shafts are mounted at predetermined intervals along the feeding direction of the resin sheet. A sagging prevention device for a resin sheet, characterized in that a plurality of resin sheets are arranged and a heat medium circulation means is provided in the support shaft.