JPH09267343A - Press molding mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a flash removing process and to reduce costs. SOLUTION: In a press molding mold consisting of a pair of molds 1, 2 for press-molding a thermoplastic material 3, a recession 11 is formed on the inside of at least one mold 2 of a travel part 10' where the molds 1, 2 overlap with a horizontal clearance on the peripheral part during pressing, and an elastic body 12 which is deformed elastically by being pushed to one of the molds 1, 2 when the travel part 10' is formed in the recession 11 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press molding die for press molding a thermoplastic material, particularly a stampable sheet applied to a bumper beam of an automobile.

[0002]

2. Description of the Related Art In recent years, stampable sheets have attracted attention as a lightweight material for automobiles. This is a composite material obtained by mixing glass fiber with resin, and is a thermoplastic material that exhibits fluidity when heated and is press-moldable. It is called a stampable sheet because the state of the semi-finished product before forming is sheet-like.

This stampable sheet (hereinafter referred to as "SP sheet") can be easily formed by a normal press-forming apparatus including a pair of molds. As the molding method, first, a predetermined number of SP sheets corresponding to the product weight are heated to a predetermined temperature (about 190 to 210 ° C) outside the mold, softened to some extent, and then brought to a predetermined temperature (about 50 to 70 ° C). Pour into a heated mold. When this is pressed with a mold, the SP sheet flows in the mold and is spread into the product shape. After this, the SP sheet is cooled and hardened in the mold, the mold is opened and taken out, and the molded product is completed.

[0004]

By the way, this SP sheet contains a large amount of air by heating, and at the same time, gas is generated therein to swell to a thickness of about 3 times. Further, since air is trapped in the mold when the mold is closed, it is necessary to remove these air and gas according to the flow of the SP sheet during press molding. For this reason, it is general to provide a clearance for venting air between the molds.

FIG. 6 shows a conventional molding apparatus in which an upper mold b approaches a fixed lower mold a from above to perform press molding. And this upper mold b
When reaches the bottom dead center, the shape of the SP sheet is finished between the molds a and b. In particular, a travel portion c is provided on the outer periphery where the upper die b and the lower die a overlap each other, and the travel portion c
There is a slight gap e between the outer surface portion d and the outer surface portion d, and this gap e forms an air vent between the molds a and b.

However, according to such a structure, a part of the SP sheet flows out from the gap e, and a burr g is formed on the molded product f as shown in FIG. 7, so that the cutting process is required. there were. In particular, since the travel portion is formed so as to surround the entire circumference of the side surface of the lower mold, there is a gap in the entire circumference, and burr treatment is also required over the entire circumference. For this reason,
It took a lot of time and labor to process the burr, and the cost had to be increased. In addition, glass fibers may be mixed in the burr, and in such a case, it is stuck in the hand and the feeling is bad, and the handling is troublesome.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a press-molding die comprising a pair of dies for press-molding a thermoplastic material, wherein one of the above-mentioned dies and the other of the above-mentioned dies are at the outer peripheral portion during pressing. At least one of the overlapping travel portions with a horizontal gap at the inside of the mold is provided with a recess, and when the travel portion is formed in the recess, the recess is elastically deformed by being pressed by one of the molds. An elastic body is provided for closing the.

In the above structure, when one mold approaches the other mold during press molding, the travel portion presses and deforms the elastic body at the same time when the mold approaches the other mold. Since the elastic body closes the gap, it is possible to prevent burrs from occurring.

[0009]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a press mold according to the present invention.
Particularly, it shows a state in the middle of press molding. The press mold comprises a pair of lower mold 1 and upper mold 2. The lower mold 1 is fixed to a bolster (not shown) and does not move, and the upper mold 2 is fixed to a ram (not shown) so that it can be vertically moved up and down. It has become. The upper die 2 can move closer to and away from the lower die 1, and the SP sheet 3 is formed between the upper die 2 and the lower die 1 by approaching or lowering.

The lower die 1 and the upper die 2 have a punch-die relationship, that is, the lower die 1 is formed with a convex portion 4 protruding upward, and the upper die 2 is formed with a concave portion 5 depressed upward. Are formed. The outer surface of the convex portion 4 and the inner surface of the concave portion 5 serve as a convex molding surface 6 and a concave molding surface 7 that partition the inner surface and the outer surface of the molded product. Further, the lower mold 1 is formed with a horizontal end face forming surface 8 over the entire circumference on the outer peripheral side in the horizontal direction of the convex portion 4, and this serves as a portion for partitioning the end face of the molded product. Further, an outer peripheral side surface 20 extending downward is formed on the outer peripheral side of the end face forming surface 8.

On the other hand, as will be described later in detail, the lower edge 7a of the concave molding surface 7 of the upper mold 2 is formed as shown by the one-dot chain line in FIG.
The above structure is cut out to form a recess 11, and an elastic body 12 is attached to the recess 11. Therefore, the lower end edge portion of the position shown as 7a is
It is adapted to be superposed on the outer peripheral side surface 20 of the lower mold 1 with a slight gap 9 (FIG. 2).

The elastic body 12 is made of an elastic material such as silicon rubber, is formed in a substantially pentagonal shape in cross section and slightly squeezes the lower part, and is detachably attached using, for example, a screw member 13 as shown in FIG. ing. Specifically, screw member 1
3 is inserted into the screw insertion hole 15 of the elastic body 12 after mounting the washer 14 and is tightened in the female screw hole 16 of the upper die 2 to fix the elastic body 12. The elastic body 12 forms one side of the travel portion 10 by the inner side surface 12a.

By the way, as shown in FIG. 1, the lower mold 1 is provided with a horizontal base surface 17 on the outer peripheral side of the outer peripheral side surface 20, and a distance 18 is fixed on the horizontal base surface 17. The distance 18 has a pressing portion 19 that protrudes upward just below the elastic body 12. Then, as will be described later in detail, the pressing portion 19 press-deforms the elastic body 12 in the vicinity of the bottom dead center of the upper die 2.

Next, the operation of this mode will be described.

First, in the state of FIG. 1, a lower mold 1 and an upper mold 2
Are heated to a predetermined temperature, and these lower mold 1 and upper mold 2
The SP sheet 3 heated to a temperature at which it can flow is put between the convex portion 4 and the concave portion 5 of. Then, with the lowering of the upper mold 2, the SP sheet 3 is pressed between the molds 1 and 2 and flows to the outer peripheral side.

Next, as shown in FIG. 2, when the upper die 2 reaches the bottom dead center, the SP sheet 3 reaches the end face forming surface 8 of the lower die 1 and is formed into a downward bent shape. . After that, the molded product obtained by cooling and solidifying the SP sheet 3 is taken out by opening the molds 1 and 2.

Particularly, in the process from the state shown in FIG. 1 to the state shown in FIG. 2, the air (gas) contained in the SP sheet 3 and the molds 1 and 2 flows along with the flow of the SP sheet 3 into SP. The sheet 3 is ejected from the space between the molds 1 and 2 so that the sheet 3 is pushed out. Immediately before the lower end surface 11 of the travel portion 10 reaches the same height as the end surface molding surface 8, the elastic body 12 contacts the pressing portion 19 of the distance 18.

Further lowering of the upper die 2 forms the travel portion 10 by the inner lower edge portion 7a of the upper die, the side surface 12a without the elastic body 12, and the outer peripheral side surface 20 of the lower die 1. That is, the elastic body 12 is pressed from above and is compressed and deformed between the elastic body 12 and the pressing portion 19. Due to this compression, the elastic body 12 expands in the horizontal direction and contacts the outer peripheral side surface 20, whereby the travel portion 10 is formed, and the inner peripheral side surface, that is, the lower end edge portion 7a of the concave molding surface 7 and the outer peripheral side surface 20. The gap 9 between the and will be closed.

As can be seen from FIG. 3, the elastic body 12
Since the fixing position of, that is, the position of the screw insertion hole 15 is offset to the side away from the outer peripheral side surface 20,
Expansion to the side is easy.

When the upper mold 2 is further lowered and the distance between the convex molding surface 6 and the concave molding surface 7 becomes equal to the product thickness t, the lowering of the upper mold 2 is completed, and the upper mold 2 at this time is finished. The position of is the bottom dead center. During this time, the elastic body 12 slides on the outer peripheral side surface 20.

FIG. 4 shows an enlarged view of the state of the main part at the bottom dead center. H represents the horizontal gap of the gap 9, and L represents the distance between the end face molding surface 8 of the lower die 1 and the lower end surface 11 of the upper die 2 and a part of the travel portion 10. As shown in the figure, the connecting portion between the lower end surface 11 and the lower end edge portion 7a of the concave molding surface 7 is a corner portion 21 formed in an appropriate rounded shape, and the elastic body 12 extends along the corner portion 21.
Enter into the gap 9 upward. Thus, the elastic body 12 completely closes the lower part of the gap 9,
As a result, the flow of the SP sheet 3 is regulated, and the occurrence of burrs can be prevented. Further, since the interval H of the gap 9 and the length L of the travel portion 10 are sufficiently small, even if the SP sheet 3 flows into the gap 9 in the upper part of the elastic body 12, the burr length thereof is extremely small and glass fibers are not mixed. Since it is rare, there is no problem with the product. The values of H and L and the elastic body 12
It is also possible to appropriately change the hardness and the like so that the gap 9 is completely filled.

As described above, according to this structure, the burr cutting process can be greatly reduced, the cost can be reduced, and the molded product can be handled very easily.

By the way, if the gap 9 is closed over the entire circumference, the air cannot be evacuated smoothly, the SP sheet 3 does not reach the end (occurrence of "short circuit"), the mold 1, Air and gas become hot inside 2 and SP
Problems such as inducing partial heating deterioration of the sheet 3 (occurrence of "burn") occur.

Therefore, as shown in FIG. 5, in such a form, a seal portion A for closing the gap 9 with the elastic body 12,
The air vent B, which does not do this, is provided at appropriate places according to the shape of the molded product 22. The air bleeding section B is (1) capable of sufficiently performing the SP sheet,
It is decided by experiments, etc. so that they can be arranged according to their position and balance, provided that (2) no "burn" occurs and (3) that all air can be removed. As a result, sufficient air bleeding can be performed and the above problem can be solved, and since only the air bleeding portion B need be deburred, the number of man-hours can be significantly reduced compared to the conventional case. It should be noted that the virtual sheet in the figure indicates the insertion position of the SP sheet 3.

Further, according to such a constitution, the gap distance H can be made larger than that of the conventional one, so that it is not necessary to make the mold material high-grade, and SS41 or FC25 which is a normal mold material.
Etc. can be adopted, and there is an advantage that an increase in mold cost can be prevented.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various other embodiments are possible. For example, the elastic body may be provided in the lower mold. It may be provided on both the upper mold and the lower mold.
Further, the above embodiment is an application example to the SP sheet, but the present invention can be applied to any thermoplastic material such as resin or plastic material.

[0028]

The present invention exhibits the following excellent effects.

(1) The burr cutting process can be greatly reduced, and the cost can be reduced.

(2) Handling of the molded product becomes very easy.

[0031]

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a press molding die according to the present invention, showing a state in the middle of molding.

FIG. 2 is a vertical sectional front view of a press molding die according to the present invention, showing a state at the end of molding.

FIG. 3 is a vertical sectional front view showing a method of attaching an elastic body.

FIG. 4 is an enlarged vertical sectional front view of an essential part at the end of molding.

FIG. 5 is a schematic plan view showing a position of a seal portion provided with an elastic body.

FIG. 6 is a vertical cross-sectional front view showing a conventional press mold.

FIG. 7 is a front view showing a molded product having burrs.

[Explanation of symbols]

 1 Lower mold 2 Upper mold 3 Stampable sheet (thermoplastic material) 9 Gap 10 Travel part 12 Elastic body.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 31:30

Claims (1)

[Claims] 1. A pair of molds for press-molding a thermoplastic material, wherein at least one of the above-mentioned molds and at least one of the above-mentioned molds overlaps each other with a horizontal gap at an outer peripheral portion during pressing. A recess is provided inside the mold of
A press-molding die, wherein an elastic body is provided in the recess when the travel portion is formed and is elastically deformed by being pressed by one of the dies to close the gap.