JPH0655428B2 - Method for molding thermoplastic resin sheet material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a method for molding a thermoplastic resin sheet material.

"Prior Art" Hot drawing of a thermoplastic resin sheet material is performed through a hot drawing step, a cooling and solidifying step, an outer shape drawing step, and the like.

In the hot drawing process, a hot drawing mold 1'having a heater 7 on an upper mold 2'and a heater 13 on a lower mold 3'as shown in FIG. 7 is used. In the hot drawing step, the thermoplastic resin sheet material cut into the blanks 14 'for one product in the previous step is heated by the hot drawing die 1'and the three-dimensional shape part 25 and the three-dimensional shape to be the product are formed. A flange portion 18 'around the portion 25 is molded.

The blank 14 'after hot drawing is cooled and solidified in the subsequent cooling and solidifying step, and then the outer peripheral unnecessary portion is removed in the external shape removing step to obtain a product.

By the way, the thermoplastic resin sheet material has a characteristic called shape memory (hereinafter referred to as shape memory characteristic), and has the property of returning to the shape before being deformed during plastic deformation. This shape memory characteristic is remarkable at the time of cooling and solidifying after the hot drawing process, and the blank 14 'formed into a predetermined shape as shown in FIG. 8 (a) by hot drawing.
Is removed from the drawing die 1'out of the die and cooled and solidified in the cooling and solidifying step, a shape deformation such as springback occurs based on the shape memory characteristic, and a strain A as shown in FIG.
B was generated, and the quality and commercial value were sometimes impaired.

For this reason, conventionally, the blank 14 'is left in the drawing die 1'after the hot drawing process is finished, and the blank 14' is held under pressure for a long time and cooled and solidified by slow cooling to prevent the occurrence of distortion. It was

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, the time required for the cooling and solidifying step is long, and the hot drawing which is cooled together with the blank 14 ′ is required for the next hot drawing. There is a problem that productivity is low because the mold needs to be reheated and hot drawing cannot be performed continuously.

The present invention has been made in view of the above problems, and prevents deformation based on shape memory characteristics in the cooling and solidifying step after hot draw forming, thereby forming a thermoplastic resin sheet material with improved productivity. The challenge is to provide.

"Means for Solving the Problems" In order to solve the above problems, according to the present invention, a one-piece thermoplastic resin sheet material is a hot drawing die provided with a bead forming portion, and a three-dimensional portion to be a product, The three-dimensional shape portion is molded into a flange portion having a bead that surrounds it endlessly to improve shape retention, and in the cooling and solidifying step after the hot drawing die is removed from the die, deformation based on shape memory characteristics is performed. A method for molding a thermoplastic resin sheet material is provided, which is characterized in that the flange portion is removed in the step of removing the outer shape after cooling and solidification.

[Operation] According to the method of the present invention having the above-described configuration, the endless bead is formed on the thermoplastic resin sheet material in the three-dimensional portion to be the product and the flange portion of the three-dimensional portion in the thermoplastic resin sheet material. By forming the beads, the shape retention of the thermoplastic resin sheet material is enhanced, and the deformation due to the shape memory characteristic in the cooling and solidifying step performed by separating from the hot drawing die to the outside of the die is prevented. Then, after cooling and solidification, unnecessary flange portions are removed in the external shape removing step.

[Examples] Examples of the present invention will be described with reference to the drawings.

First, FIGS. 1 to 3 show a hot drawing die used in the hot drawing step. FIG. 1 is a sectional view of the hot drawing die, FIG. 2 is a bottom view of the upper die as seen from below, and FIG. 3 is a plan view of the lower die as seen from above. The hot drawing die 1 is composed of an upper die 2 and a lower die 3.

The upper die 2 includes a punch 4, a stripper plate 5, a punch holder 6 and the like. The punch 4 has a built-in heater 7 and is fixed to the punch holder 6. The stripper plate 5 is formed thinner than the punch 4, and has a hole 8 through which the punch 4 is inserted. The stripper plate 5 is movably supported by the punch holder 6 between an upper end position where its upper surface abuts the lower surface of the punch holder 6 and a lower end position where its lower surface is substantially flush with the lower surface of the punch 4, and is not shown in the figure. The spring member constantly biases the lower end position. The stripper plate 5 is provided with an endless protrusion 9. A shank 10 is projectingly provided on the upper surface of the punch holder 6.

The lower die 3 is composed of a die plate 11, a bolster 12 and the like.
The die plate 11 has a built-in heater 13 and a bolster 12
Is stuck to. Molding in which the blank 4 made of the punch 4 and the thermoplastic resin sheet material enters the upper surface of the die plate 11 and has a depth dimension equal to the difference between the plate thickness of the punch 4 and the plate thickness of the stripper plate 5 during hot drawing. The hole 15 is recessed. An endless groove 16 surrounded by the molding hole 15 is provided in the die plate 11 so as to correspond to the protrusion 9 of the stripper plate 5. The groove 16 and the protrusion 9 form an endless bead forming portion 17, and the bead forming portion 17 forms an endless bead 19 on the flange portion 18 of the blank 14 at the time of hot drawing. Also, the positioning pins 24 are provided on the die plate 11.
Are provided at two locations.

In the subsequent cooling and solidifying step, the blank 14 that has undergone the hot drawing step is released from the hot drawing die 1 to the outside of the mold as shown in FIG. 5, and is solidified in the natural cooling step in the atmosphere. At this time, since the blank 14 has a shape in which the endless bead 19 surrounding the three-dimensional shape portion 25 is formed on the flange portion 18 to improve the shape retention, the blank 14 is deformed based on the shape memory characteristic and the three-dimensional shape portion 25 is deformed. No springback etc. will occur.

Then, in the outer shape removing step, the endless bead 19 is formed.
The flange portion 18 including is removed.

"Operation" As an operation of the above configuration, a procedure for actually molding a thermoplastic resin sheet material into an instrument panel of an automobile will be described with reference to the process diagram shown in Fig. 6 and Figs. 4 (a) to (i). .

A thermoplastic resin sheet material having a plate thickness of 0.5 mm, for example, is cut into a material 20 of 450 mm × 450 mm in the material cutting step 101 (see FIG. 4 (a)). In this embodiment, 9 pieces of instrument plates are formed from one piece of material 20. Next, in the printing step 102, black, white, red, etc. are printed on the front and back surfaces (see FIG. 4 (b)). A protective sheet 21 is attached to the printed front and back surfaces in a subsequent protective sheet attaching step 103 in order to prevent scratches in a later step (see FIG. 4 (c)). Next, in order to facilitate the processing of reference holes, which will be described later, in the short length cutting step 104, the material 20 is cut into three lengths of the instrument plate, that is, short length material 22 of 150 mm × 450 mm (see FIG. 4 (d)). Then, the reference hole 23 is formed in the reference hole forming step 105 (see FIG. 4E). The reference holes 23 are provided to prevent misalignment in printing in a hot drawing step 107 and an outer shape / punching step 109, which will be described later. There are 6 holes. Next, in the blank cutting step 106, the short material 22 is used for one instrument plate, that is, 15 pieces.
The blank 14 of 0 mm × 150 mm is cut (see FIG. 4 (f)).

In the subsequent hot drawing step 107, the blank 14 is drawn into the three-dimensional shape portion 25 and the flange portion 18 by using the hot drawing die 1 shown in FIG. Hot drawing step 107
In the upper mold 2, the punch 4 and the stripper plate 5 are heated by the heater 7 in the upper mold 2, and in the lower mold 3, the die plate 11 is heated by the heater 13. The blank 14 is
It is placed on the die plate 11 of the lower mold 3. At this time, by inserting the reference hole 23 into the positioning pin 24 of the die plate 11, the die plate 11 is placed at a predetermined position so that there is no misalignment between printing and thermal drawing. And if you lower the upper mold 2,
First, the stripper plate 5 at the lower end is a blank 1
4, the blank 14 is sandwiched between the stripper plate 5 and the outer peripheral portion 26 of the die plate 11 to preheat the peripheral edge portion of the flange portion 18. At this time, the bead forming portion 17 causes the endless bead 1 on the flange portion 18.
9 is formed. Next, the upper mold 2 is further lowered, and the punch 4 and the molding hole 15 of the die plate 11 form a predetermined three-dimensional shaped portion 25.

Next, the upper die 2 is lifted to separate the blank 14 from the hot drawing die 1 to the outside of the die, and the blank 1 is subjected to the cooling and solidifying step 108.
Cool and solidify 4 in air. At this time, the deformation or the like based on the shape memory characteristic is prevented by the shape retention increased by forming the endless bead 19 surrounding the three-dimensional shape portion 25 on the flange portion 18. (Refer to FIG. 4 (g) and FIG. 5 showing the VV line cross section).

Next, in a contour / hole punching step 109, which is a contour cutting step, a hole 27 having a predetermined shape is formed and trimming of the contour is performed. At this time, the outer peripheral unnecessary portion including the endless bead 19 is removed from the flange portion 18 (see FIG. 4 (h)). Then, in the protective sheet peeling step 110, the front and back protective sheets 21 are peeled off (see FIG. 4 (i)), and all steps are completed.

In this embodiment, the holes 27 are formed in the outer shape / drilling step 109. However, if the holes are not required in the product, only the outer shape is trimmed.

In this embodiment, the material is 0.5 mm and the thickness is 150 mm.
Although a thermoplastic resin sheet having a size of 150 mm was used, the present invention is not limited to this, and the plate thickness and the shape and dimensions are appropriately selected according to the product.

"Effects of the Invention" The present invention has the above-mentioned configuration, and a single thermoplastic resin sheet material is attached to a flange portion of the thermoplastic resin sheet material by a hot drawing type bead forming portion in a hot drawing step. By forming a bead that surrounds the three-dimensional part to be a product in an endless manner to improve shape retention, it is possible to prevent deformation based on shape memory characteristics in the cooling and solidifying step after the hot drawing die is removed from the die. A cooling and solidifying step of performing pressurization and gradual cooling using a hot drawing die becomes unnecessary, and solidification is possible by natural cooling in the atmosphere. Therefore, it is possible to perform hot drawing by continuously using the hot drawing die in a heated state, and there is an excellent effect that productivity can be remarkably improved.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a sectional view showing a hot drawing die, FIG. 2 is a bottom view showing an upper die of the hot drawing die, and FIG. A plan view showing the lower die of the hot drawing die, FIGS. 4 (a) to 4 (i) are explanatory views showing the shape of the thermoplastic resin sheet material in each step, and FIG. 5 is FIG. 4 (g). V
-V line sectional view, FIG. 6 is a process drawing of the molding process of the thermoplastic resin sheet material, FIGS. 7 and 8 show a conventional example, FIG. 7 is a cross-sectional view of a hot drawing die, 8A is a cross-sectional view showing the thermoplastic resin sheet material immediately after hot drawing, and FIG. 8B is a cross-sectional view showing the thermoplastic resin sheet material in which strain has occurred. 1 ... Hot drawing type, 14 ... Blank (thermoplastic resin sheet material), 17 ... Bead forming part, 18 ... Flange part, 19 ... Endless bead, 25 ... Three-dimensional shape part, 107 ... ... hot drawing step, 108 ... cooling and solidifying step, 109 ... external shape and punching step.

Claims (1)

[Claims] 1. A one-piece thermoplastic resin sheet material is formed by a hot drawing die provided with a bead forming portion, and a three-dimensionally shaped portion to be a product, and a flange portion having a bead that surrounds the three-dimensionally shaped portion endlessly. In the cooling and solidifying process after the hot drawing die is removed from the die,
A method for forming a thermoplastic resin sheet material, which comprises preventing deformation based on shape memory characteristics, and removing the flange portion in an outline drawing step after cooling and solidification.