JPS5837131B2 - Netsukaso Seijyuushishi Toyori Seikeihin Oseizosuru Hohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a molded article from a thermoplastic resin sheet.

More specifically, a uniaxially or biaxially stretched thermoplastic resin sheet is used as a material, and this is heated using an indirect heating method,
When manufacturing a molded product by a vacuum forming method or a pressure forming method, the molded product is prevented from being deformed by the shrinkage force generated when the stretched sheet material is heated.
This invention relates to an improved method for improving the quality of molded products and improving productivity.

Methods for producing molded products using uniaxially or biaxially stretched thermoplastic resin sheets include vacuum forming methods and pressure forming methods.

The heating methods used to manufacture molded products using these sheets include a direct heating method in which the sheet material is heated by contacting it with a preheated metal plate, and a direct heating method in which the sheet material is heated without contacting the heating plate. There is an indirect heating method that heats in hot air.

A direct heating method is mainly used to form stretched sheet materials.

This is because the stretched sheet material shrinks and deforms when heated, so the heated portion must be fixed, but this fixing is easy with a direct heating method.

However, when using the direct heating method, there are disadvantages in that it tends to be subject to limitations on the thickness of the sheet material, the width of the sheet material, and the number of molded products that can be molded in one shot. Consideration is being given to a molding method using the indirect heating method, which has fewer such limitations. is being carried out.

Currently known indirect heating molding methods include a method of simultaneously punching out a pre-shaped article from a sheet material, as described in Japanese Patent Publication No. 42-6185.

According to this forming method, the sheet material shrinks due to its shrinkage force,
The sheet material deforms until the next shot, and in order to avoid the effects of this shrinkage, it is necessary to feed extra sheet material, resulting in a decrease in yield.

In view of this situation, the present inventor has completed the present invention as a result of intensive study on a method for manufacturing a precept-shaped article that eliminates the above-mentioned drawbacks.

The purpose of the present invention is to use a uniaxially or biaxially stretched thermoplastic resin sheet as a material and heat it using an indirect heating method, thereby minimizing the influence of the shrinkage force of the sheet material on the molded product and improving quality. The object of the present invention is to provide a scale and a method for manufacturing molded products that improves productivity.

The gist of the present invention to achieve the above object is to heat a uniaxially or biaxially stretched thermoplastic resin sheet using an indirect heating method and produce a molded product by a vacuum forming method, a pressure forming method, etc. A deformation-preventing rib molding mold is installed on the side where the sheet material to be heated and molded is supplied.
In addition, the sheet material exit side is formed using a mold provided with a cutting blade having a width equal to or slightly smaller than the width of the deformation-preventing rib molding mold, perpendicular to the sheet material transport direction. A method of manufacturing a molded article from a thermoplastic resin sheet is provided.

The method of the present invention will be explained in detail below.

The method of the present invention is applied to a uniaxially or biaxially stretched thermoplastic resin sheet.

The method is applied when these stretched sheets are heated and molded using an indirect method.

Typical thermoplastic resins include styrene resins, vinyl chloride resins, and olefin resins, and polycarbonate, polyamide, and other thermoplastic resins that can be formed into sheets by stretching are also used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

FIG. 1 is a longitudinal sectional front view of an example of the apparatus used in carrying out the method of the present invention in a state in which a molded article is manufactured, and FIG. 2 is a molding section of the apparatus shown in FIG. 1. 3 is a perspective view of an example of a product obtained by the method of the present invention, FIG. 4 is a plan view of an example of a product obtained by the method of the present invention, and FIG. 5 is a front view of a product obtained by the conventional method. A plan view of each of the obtained products is shown.

In the figure, reference numeral 1 denotes a biaxially stretched thermoplastic resin sheet to be molded, which is transported in the direction of the arrow at predetermined time intervals by a transport device (not shown).

Reference numeral 2 denotes a heating furnace for the sheet 1, which heats the sheet 1 to a temperature at which it can be molded in the next mold.

The length of the heating furnace 2 is usually 3 to 5 shots (in the illustrated example, the length 32 in FIG. 3 corresponds to one shot).

) minutes is sufficient and is heated to the desired temperature in the final zone of the furnace.

The heated sheet is transferred to a molding part with both ends in the width direction being removed, and is subjected to molding.

3 is a mold support stand, 4 is a hydraulic cylinder, 5 is a toggle mechanism, 6 is a heating furnace support stand, 7 is a formwork, 8 is a face plate, 9 is a compressed air supply pipe, 1o is a ventilation hole, 11 is for molding The mold 12 is a ventilation hole provided in the mold 11.

13 is a lower mold for forming deformation prevention ribs, 14 is 13
16 and 17 are cooling water holes provided in each of the rib molding molds.

After the heated sheet is transferred to the castle-shaped mold part (
(See FIG. 1), the mold support 3 is pushed upward by the hydraulic cylinder 4 and the toggle mechanism 5, the sheet 1 is sandwiched between the mold 7 and the face plate 8, and the mold is clamped so that the compressed air does not leak.

Simultaneously with the completion of mold clamping, compressed air is supplied to the compressed air supply pipe 9 and applied to the sheet surface through the compressed air supply pipe 10, thereby pressing the heated sheet against the molding die 11.

The air trapped in the mold 11 is discharged out of the mold through the ventilation hole 12 (see FIG. 2).

The above example is an example in which a molded article is manufactured by the pressure forming method. However, if the vent hole 12 of the mold 11 for molding the mold 11 is connected to a vacuum mechanism, the molded article can also be manufactured by the vacuum forming method.

In addition, a molded product can be manufactured by combining the pressure forming method and the vacuum forming method. When manufacturing a molded product using the above-mentioned forming process, the sheet 1 is formed by a set of deformation-preventing rib molding molds. 13.
14 and which can form the deformation prevention ribs 18 is used.

In FIG. 1, the lower mold 13 is made into a female mold and fixed to the formwork 7,
An example in which the upper mold 14 is operated by the hydraulic cylinder 15 has been shown.

Of course, the combination may be reversed.

Further, the mechanism for operating the mold 14 is not limited to a hydraulic mechanism, and other mechanisms may be employed.

The shape of the deformation prevention rib 18 is preferably such that the vertical cross-sectional shape taken in the direction of the arrow in FIG. 1 is V-shaped, U-shaped, or W-shaped.

The width (meaning the direction perpendicular to the direction of the arrow in FIG. 1) does not need to cover the entire width of the sheet 1, and can be changed depending on the shape of the product to be manufactured.

If it is made too small, it will not be able to sufficiently absorb the deformation caused by subsequent heat shrinkage, which is undesirable.The width should be the same as or slightly larger than the molded width of sheet 1 (in the direction perpendicular to the arrow direction in Figure 1). good.

The deformation prevention ribs 18 are preferably formed at the same time as the container body.

In other words, the hydraulic mechanism 1 at the same time as the start of mold clamping or after the end of mold clamping.
5 to press the upper mold 14 against the lower mold 13, the deformation prevention rib 18 can be formed.

While the container body is being formed, the sheet is not transported, and the sheet being heated in the heating furnace is heated highest in the portion closest to the mold and tends to shrink.

However, during molding (the deformation prevention rib molding mold quickly molds the deformation prevention ribs and molds the container, the mold 13
, 14 in a pressed state, it is possible to prevent the deformation of the sheet from reaching the mold.

When the molding is completed and the mold is opened, the mold 14 is returned to its original position, and a sheet for the next molding is transferred into the molding chamber 7, so that the next molding can be performed.

While the sheet for the next shot is transferred after the mold is opened and the mold is clamped, the sheet 1 shrinks, but deformation prevention ribs 18 are formed, and this part is still fully compressed. Since this portion is not curved, this portion can be deformed over a range from a concave shape to a flat shape, and this deformation can absorb the shrinkage of the sheet 1 and minimize the effect on the molded product 19.

In order to eliminate deformation of the upper sheet during transport, a cutting blade 2 is provided on the side opposite to where the deformation-preventing rib molding mold of the molding mold 11 is provided, that is, on the exit side of the sheet material.
The cutting blade 20 using a mold provided with 0 is a fixed mold 2.
It is preferable to fix it to 1.

The fixing plate 21 is placed inside the formwork 7 as shown in FIGS. 1 and 2, the tip of the fixing frame 21 is kept at the same height as the formwork 7, and the tip of the cutting blade 20 is heated. The cutting blade 2o is made high by the amount corresponding to the thickness of the sheet.
The width (in the direction perpendicular to the direction of the arrow in FIG. 1) is preferably equal to or slightly smaller than the width of the deformation prevention rib forming mold.

As shown in FIG. 2, this cutting blade 20 cuts into the sheet 1 during mold clamping.

When the sheet 1 shrinks when the mold is opened and the sheet is transferred for the next molding, the deformation prevention rib 18 is deformed over a range from a concave shape to a flat shape, as described above, but at the same time, the notch is The molded part 19 opens to absorb the deformation as indicated by 29 in FIGS. 3 and 4.
can almost eliminate the impact on

22 is a mounting plate for the hydraulic cylinder 15, 23 is an upper surface fixing plate, 24 is a heat insulating plate, and 25 is a hot plate.

The hot plate 25 has the role of keeping the heated sheet warm so that it does not cool down immediately during molding, and is preferably a temperature-adjustable mechanism.

Also, it is possible to have a structure in which the heated sheet does not come into direct contact with the face plate 8, but if this is done, the heating plate 25
, it is not necessary to provide the heat insulating plate 24.

26 is a formwork guide shaft, 27 is a lower fixing part, and 28 is a nut.

29, the part where the notch was made is due to heat shrinkage of the sheet [
Shows open state.

A perspective view of a molded product obtained by the method of the present invention is shown in Fig. 3, for example.

Reference numeral 30 indicates marks left by holding both ends of the formed sheet, and reference numeral 31 indicates marks left by pressing the heated sheet against the tip of the formwork 7.

32 indicates the area molded by the mold shown in FIGS. 1 and 2.

It goes without saying that these shaped products are cut into desired sizes from sheets and punched out by a punch in a cutting and punching process section (not shown).

FIG. 4 is a bacilli diagram of a molded article obtained by the method of the present invention.

Each line of the molded product (the top and bottom surfaces appear as a line Cζ).

), from the side closest to the heating furnace to the side farthest (a, b, c in the direction of ζ)
...If you add h, neither part a near ζ nor h on the opposite side of the heating furnace (f4) will undergo any deformation.

FIG. 5 is a cross-sectional view of the product obtained by the conventional method.

This case indicates that severe deformation occurs in the molded product near the heating furnace.

Conventionally, a thermoplastic resin sheet that has been uniaxially or biaxially stretched is heated using an indirect heating method, and a molded product is manufactured using a pressure molding method, a vacuum forming method, etc. The stretched sheet shrinks when heated. However, when the method of the present invention is followed, such defects can be eliminated and good products can be manufactured efficiently, and the industrial value is extremely high. It is.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of an example of the apparatus used in carrying out the method of the present invention in a state in which a molded article is manufactured, and Fig. 2 is a longitudinal sectional front view of the apparatus shown in Fig. 1. FIG. 3 is a plan view of an example of a product obtained by the method of the present invention; FIG. 4 is a plan view of an example of a product obtained by the method of the present invention; FIG. is a plan view of a product manufactured by the conventional method. In the figure, 1 is a sheet, 2 is a heating furnace, 7 is a formwork, 8 is a metal plate, 9 is a compressed air supply pipe, 10.12 is a ventilation hole, 11 is a molding mold, and 13 is a lower part for forming ribs to prevent deformation. , mold, 14
18 is a deformation prevention rib forming mold, 18 is a deformation prevention rib,
19 is a molded product, and 2o is a cutting blade.

Claims (1)

[Claims] 1. When a uniaxially or biaxially stretched thermoplastic resin sheet is heated using an indirect heating method and a molded product is manufactured by a vacuum forming method, a pressure forming method, etc., the heated sheet material to be formed is supplied. A deformation-preventing rib forming mold is provided on the sheet material exit side, and a cutting blade having a width equal to or slightly smaller than the width of the deformation-preventing rib forming mold is provided on the sheet material exit side, perpendicular to the sheet material transport direction. A method for manufacturing a molded product from a thermoplastic resin sheet, characterized by molding using a mold provided with.