JPH0361022A - Manufacture of sheet molded product - Google Patents

Abstract

PURPOSE:To easily mold a plurality of molded products simultaneously, by a method wherein molding is performed by laminating and arranging a plurality of sheet materials, whose molding shrinkage factors are different from one another, in the order that the more the sheet material goes inward from the outside, the smaller the mold shrinkage factor becomes in a recessed state part. CONSTITUTION:Along with simultaneous extrusion of two kinds of sheet materials whose molding shrinkage factors are different from each other through two units of extruding machines 11a, 11b, they are conveyed to a molding device 13 and arranged on its bottom force 14 while laminating the sheet materials 12a, 12b by inserting a mold release film 32 between them. In this instance, the sheet materials 12a, 12b whose molding shrinkage factors are high and low respectively are arranged on the lower and upper parts. A top force 15 of a molding device 13 is lowered, suction is performed with a vacuum pump not illustrated herein through a suction hole 17 of the bottom force 14 while performing mold clamping and the sheet materials 12a, 12b are sucked to a recessed mold surface 16 of the bottom force 14 under this state. Then those materials are pressed with the mold surface 16 and a protrusion 18 through lowering of the top force 15 and molded products 1a, 1b having a recessed state part 2 are molded by running two sheet materials 12a, 12b along the mold surface 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a sheet molded product, in which a plurality of sheet molded products are simultaneously molded.

(Prior art) Figure 3 shows a synthetic resin molded product 1. This refers to a fender protector that covers the outside of a car's tires.
This molded product 1. The main body part 3 has a substantially semicircular shape and has a concave part 2 inside, and flange parts 4.5 are integrally provided at both ends thereof. When molding such a molded product 1, conventionally,
A manufacturing method as shown in FIG. 4 is used.

In FIG. 4, 11 is an extruder that molds and extrudes a synthetic resin sheet material 12 from raw materials.

A molding device 13 has a lower mold 14 and a movable upper mold 15. The lower mold 14 has a concave mold surface 16 and a suction hole 17 opened in the mold surface 16. Above mold surface 1
A convex portion 18 corresponding to 6 is formed.

A trimming device 19 has a lower mold 20 and a movable upper mold 21. The lower mold 20 has a concave mold surface 22, and the upper mold 21 has a convex mold surface 22 corresponding to the mold surface 22. Part 23
A cutter 26 consisting of a blade receiving groove 24 and a blade 25 facing thereto is provided at the front and rear of the opposing surfaces of the lower die 20 and the upper die 21.

Then, the sheet material 12 of the work sheet extruded from the extruder 11
is conveyed to the molding device 13 and placed on the lower mold 14, and while the upper mold 15 is lowered and closed, the sheet material 12 is sucked from the suction hole 17 of the lower mold 14 by a vacuum pump (not shown).
is attracted to the concave mold surface 16 of the lower mold 14, and the upper mold 1
5 is pressed by the mold surface 16 and the convex portion 18,
A molded product 1 having a concave portion 2 is molded by aligning the sheet material 12 along a mold surface 16.

Next, the upper mold 15 is raised and removed from the mold, and the molded product 1 taken out from the mold is conveyed to the trimming device 19 and the lower mold 20 is removed.
the upper die 21 is lowered to form the concave portion 2 of the molded product 1.
While being held between the mold surface 22 and the convex portion 23, the front and rear flanges 4 and 5 are cut to a predetermined length by the cutter 26, unnecessary parts are removed, and the upper mold 21 is lifted to take out the molded product 1. .

(Problems to be Solved by the Invention) According to the above method, since the sheet materials are sequentially fed one by one to the molding device and molded, only one molded product can be molded in one process.

In this case, if multiple molding devices and trimming devices are used, multiple molds can be molded at the same time in one step, but this increases the size of the device and increases the cost.
There is a problem in that it is difficult to respond to small-volume production of other products or to changes in shape.

The present invention is intended to solve the above-mentioned problems, and aims to make it possible to easily mold a plurality of molded products at the same time.

[Structure of the invention]

(Means for Solving the Problems) The method for manufacturing a sheet molded product of the present invention involves manufacturing a sheet molded product in which a molded product having a concave portion is formed by aligning a synthetic resin sheet material along the mold surface of a molding device. In the method,
A plurality of sheet materials having different molding shrinkage rates are laminated and molded in the order of decreasing molding shrinkage rates from the outside to the inside in the recessed portion.

(Function) In the present invention, when molding a molded product having a concave portion,
A sheet material with a high molding shrinkage rate is placed on the outside of the concave part.
On the inside thereof, sheet materials having a small molding shrinkage rate are sequentially stacked and molded, and the recessed portions are molded into different sizes, and then made into substantially the same size by molding shrinkage.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

This example also shows the case where the fender protector shown in FIG. 3 is manufactured as the synthetic resin molded product 1, and is basically equipped with the apparatus shown in FIG. 4, so that Portions corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

That is, the apparatus shown in FIG. 1 also includes an extruder 11 and a molding device 13.
, has a trimming device 19, but the extruder II
, two extruders 11a and Ilb are arranged above and below, and a release film supply device 31 is disposed between these two extruders 11a and Ilb, and each extruder 11a.

A release film 32 is supplied between the sheet materials 12a and 12b from 11b. Further, in the trimming device 19, a cutter 26 is provided only at the rear portion. Further, the sheet materials 12a and 12b extruded from the respective extruders 11a and llb have different molding shrinkage rates, and in the illustrated example, the lower sheet material 12a has a higher molding shrinkage rate than the upper sheet material 12b, and There is.

Then, two types of sheet materials 12a and 12b having different molding shrinkage rates are simultaneously extruded from the two extruders 11a and Ilb, and a release film supply device 31 (supplied by Jli) is placed between the sheet materials 12a and 12b. While interposing and laminating the mold release film 32, this is conveyed to the molding device 13 and placed on the lower mold 14 thereof.

At this time, the sheet material 12a having a larger molding shrinkage rate is placed below, and the sheet material 12b having a smaller molding shrinkage rate is placed above. In this state, the upper mold 15 of the molding device 13 is lowered and closed, and the sheet materials 12a and 12b are drawn into the concave mold surface of the lower mold 14 by suction from the suction hole 17 of the lower mold 14 by a vacuum pump (not shown). At the same time as adsorbing to the upper mold 15
Press by the mold surface 16 and the convex part 18 by descending, and 2
The sheet materials 12a and 12b are placed along the mold surface 16 to form molded products 1a and Ib having concave portions 2. As a result, the molded product 1a made of the sheet material 12a with a larger mold shrinkage rate is located on the outside of the concave mold surface 16, and the molded product 1b made of the sheet material 12b with a smaller mold shrinkage ratio is located inside thereof. .

Next, the upper mold 15 is raised to open the mold, and the molded products 1a and lb taken out from it are transported to the trimming device 19 and set on the lower mold 20, and the upper mold 21 is lowered to open the molded products 1a and Ib. While holding the concave portion 2 between the mold surface 22 and the convex portion 23, the rear flange portion 5 is cut to a predetermined length using the cutter 26, unnecessary portions are removed, and the upper mold 21 is lifted to form the molded product 1a. , take out Ib.

Then, the two laminated molded products 1a and Ib are peeled off from the release film 32 and separated. Then, two molded products I molded into different sizes in the concave portion 2
a and lb shrink at different molding shrinkage rates, and finally have approximately the same dimensions that are close to each other.

Next, an example of molding shrinkage of molded products 1a and lb will be shown.

Figure 2 shows the case where it is applied to a polyethylene resin fender protector with a thickness t of 1.2 mm.
A) shows the state of molded products 1a and Ib immediately after molding, and Fig. 2 (
B) shows the separated state before shrinkage, and the dimensions are as shown in Table 1 below.

(See next page) Table ■ These molded products Ia and Ib shrink as shown in Figure 2 (C), but in this case, the radius of molded product 1a after shrinkage is , the radius of the molded product 1b after shrinkage is as follows, and other dimensions show similar shrinkage, resulting in dimensions as shown in the following table.

Table 2 In this way, molded products 1a, 1. The radius of the concave portion 2 of b is approximately the same size. Note that the dimensions of the flange portion may be adjusted by cutting the longer end after shrinkage.

Note that Table 2 shows the dimensions of the molded product after 24 hours.

That is, the difference between Table 1 and Table 2 corresponds to molding shrinkage, and the slight shrinkage that occurs after 24 hours is distinguished from molding shrinkage and is called post-shrinkage.

As described above, the molded product la has the concave portion 2.

1b, a plurality of sheet materials 11a and 12b are stacked in order from the outside to the inside of the concave portion 2 in order from the highest molding shrinkage rate to the lowest, thereby forming a plurality of sheet materials with similar dimensions in one molding process. Molded product la.

1b can be obtained.

In the above example, the case where two molded products are obtained simultaneously by laminating two sheet materials was explained, but depending on the thickness and material of the sheet materials, three or more sheets may be laminated and molded to obtain three or more molded products. Molded products can also be obtained at the same time. In addition, in the case of a combination of sheet materials to be laminated that allows delamination, for example, ABS resin and polypropylene resin, or polyethylene resins that are not very high temperature, it is recommended to polymerize directly without using a release film. You can.

In addition, as a forming device, a device that combines vacuum forming and press forming and performs them simultaneously is shown, but in addition to vacuum press forming, press forming, vacuum forming,
This can be done using an appropriate forming method such as pressure forming.

0 [Effects of the Invention] According to the present invention, when molding a molded product having a concave portion, a plurality of sheet materials are stacked and arranged in order from the outside of the concave portion to the inside of the concave portion in order of molding shrinkage percentage from large to small. By molding, it is possible to easily obtain a molded product with concave shapes having approximately the same dimensions in one molding.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing an example of the method of the present invention, Fig. 2 is an explanatory diagram showing the state of molding shrinkage of a molded product, Fig. 3 is a perspective view of the molded product, and Fig. 4 is a process diagram showing a conventional method. FIG. 1a, 1b...molded product, 12a, 12b...sheet material,
13... Molding device.

Claims (1)

[Claims] (1) In a method for manufacturing a sheet molded product, in which a molded product having a concave portion is formed by aligning a synthetic resin sheet material along a mold surface of a molding device, a plurality of sheet materials having different molding shrinkage rates are placed in the concave portion. A method for manufacturing a sheet molded product, characterized in that the sheets are laminated and molded in order of decreasing molding shrinkage from the outside to the inside.