JPS6120722A - Mold for blow molding - Google Patents

Abstract

PURPOSE:To prevent the inside of pressed bodies from getting thinner by providing a weir that can move to the inner part of a mold in the squeezing parts of partitioned molds. CONSTITUTION:When the molds 11, 12 are closed, the parison 6 is crushed gradually by the squeezing parts A, A. Further, just before the molds 11, 12 are closed, the cam surface 15a of the slide cam 15 abuts upon the drive cam surface 18a of the drive cam 18. Hereby, while the slide cam 15 compresses the elastic body 16, it moves toward the lower part in the cam-containing chamber 14. At this time, since the weir 17 being installed so that the squeezing part A is crossed with the movement of said cam 15 moves downward, the lower side of the parison 6 put between both compressed parts A, A is forced down to supply a sufficient quantity of resin to the place relevant to the inside of the compressed parts 7a in a molded piece. After blow molding, said compressed parts 7a take a sufficient thickness of resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to improvements in blow molding molds used, for example, in blow molding.

(Prior Art) Conventionally, blow molding molds have had structures as shown in FIGS. 1 and 2, for example.

That is, this blow molding mold 1 is used for blow molding a fuel tank for an automobile, and has a hollow part 4 that forms a molded product formed by two halves of the mold 2 and 3, and a hollow part 4 in which air is blown. It forms a mouth 5.

When performing blow molding, a pipe-shaped parison 6 (softening tube) injected from an extrusion device (not shown) is sandwiched between the molds 2 and 3, and compressed air is introduced from the opening 6a formed by the blow port 5. By blowing, the parison 6 is expanded into the shape of the hollow portion 4 to form a hollow fuel tank.

In the fuel tank 7 immediately after being molded in this way, as shown in FIG. 3, the parison exposed outside the mold remains as a burr 6b, and as shown in FIG. Finishing is done by cutting out.

However, in the crimped part 7a where the burr 6b is removed after being crimped by the two dies 2 and 3, the parison 6 may escape out of the mold when the dies 2 and 3 press, or the parison 6 may be temporarily compressed during the molding process. As the sandwiched parison 6 is expanded into the shape of the hollow part 4 by compressed air, the inner wall is pulled and dented, resulting in a decrease in wall thickness and strength, as shown in Figure 5. was there.

Therefore, as shown in FIGS. 6 and 7, one mold 2
Alternatively, step portions are formed in the clamping parts 2a and 3a of both molds 2 and 3 so that the distance between both molds 2.3 becomes smaller toward the inside of the mold. parison 6
Some models were designed to prevent the meat from escaping out of the mold, but this did not prevent the meat from being pulled due to the expansion caused by blowing after crimping, and the inner surface of the crimped portion 7a ended up being dented. became.

(Purpose of the Invention) This invention was made by focusing on the above-mentioned conventional problems, and it is possible to improve the pressure by providing a weir movable inward of the mold at the clamping part of the divided mold. A blow molding tool that can prevent the parison from escaping out of the mold during clamping, and can also prevent the inner surface of the crimped part from becoming thin by pushing the parison toward the inside of the mold. The purpose is to provide a model.

(Structure of the Invention) The structure of the blow molding mold according to the present invention is that in a blow molding Venus consisting of a plurality of split molds that sandwich an injected parison, one mold has a weir that crosses the pressed part of the parison. A slide cam to which a mold is attached is provided, the slide cam is biased so that the base can move toward the outside of the mold, and a slide cam is attached to the other mold so that the base moves toward the inside of the mold during mold matching. It is characterized by the provision of a drive cam surface that pushes the cam.

(Example) The present invention will be explained below based on the drawings.

FIGS. 8 to 12 are diagrams illustrating an embodiment of the present invention.

That is, as shown in FIG. 8, this blow molding die 10 forms a hollow part 13 that forms the shape of a molded product using two divided molds 11.12.
2 are provided with arcuate cutouts 11a and 12a that form air inlets when the molds are matched.

In addition, at both upper ends of the dividing surface of one mold 11,
As shown in FIG. 9, cam storage chambers 14.14 are formed which are open on the dividing surface side, and each of the cam storage chambers 14.
．． 14, a slide cam 15 having an upward cam surface 15a is inserted so as to be vertically movable and with the cam surface 15a side protruding. A long weir 17 is constructed so as to cross the pinched portion A. and again,
An elastic body 16 is provided below each of the cam storage chambers 14.14, and each of the elastic bodies 16 allows each slide cam 15 to be
, 15 are urged upward so that the base 17 is directed out of the mold.

Further, on the dividing surface of the other mold 12, there is provided a drive cam 1 that faces each of the slide cams is and is during mold matching.
8.18, each of the drive cams 18 having a downward drive cam surface 18& that contacts the cam surface 15a and pushes the slide cam 15 downward.

Note that a protrusion 11b is formed on the upper edge of the hollow part 13 in one mold 11 to further reduce the gap between the other mold 12 and to press a part of the pipe-shaped parison 6. A pinched portion A is also formed between both drive cams 18 in the mold 12.

Next, the operation of the blow molding die 10 configured as described above will be explained.

First, when the molds 11 and 12 are brought closer to the parison 6 (softening tube) injected between the molds 11.12 separated from each other, the parison 6 is
The pinched parts A and the part corresponding to A are gradually crushed. (The state shown in FIG. 9) Furthermore, just before both molds 11 and 12 close, the cam surface 15a of the slide cam 15 and the drive cam surface 18a of the drive cam 18 come into contact with each other, causing the first
As shown in figure O, the slide cam 15 is connected to the elastic body 16
While compressing the cam, it moves downward in the cam storage chamber 14 (into the mold). At this time, as shown in FIG. 11, as the slide cam 15 moves, the weir 17, which is constructed across the pinched part A, moves downward, so that the lowering of the base 17 causes both pressures to rise. The lower side of the parison 6 sandwiched between the sandwiched parts A and A is forcibly pushed down, and the pushed down part is connected to the protrusion 11b and the other mold 1.
2 into the hollow part 13.

Therefore, the crimped part 7a in the molded product (see Fig. 4)
A sufficient amount of meat will be supplied to the part corresponding to the inner surface side, and after blow molding with compressed air,
As shown in FIG. 2, no dents are formed on the inner surface of the crimp portion 7a, and the thickness is equal to or greater than that of the other portions.

Furthermore, when both molds 11 and 12 are separated after completion of molding, the slide cam 15 and weir 17 return to their original positions due to the repulsive force of the compressed elastic body 16.

Note that the downward movement distance of the weir 17 can be changed depending on the size and combination of the slide cam 15 and the drive cam 18, so for example, by increasing the amount by which the parison 6 is pushed in, the inner surface of the crimp portion 7a can be brought into a protruding state (the third position). 12), the strength can be further improved.

In addition, in the above embodiment, the weir 17 was provided at the upper part of the dividing surface of the star 11 and 12, but this position is not limited, and it may be installed at another part that pinches the parison 6. Of course there are times when it happens.

Furthermore, in the above embodiment, the drive cam 18 having the drive cam surface 18a was provided on the other mold 12, but the other mold 12 and the drive cam 18 may be integrated, and the other mold 12 may be provided with a drive cam surface 18a for pushing the slide cam 15.

Furthermore, in the above embodiment, the cam storage chamber 1 is provided in one mold 11.
4.14 is formed to form a slide cam 15 and an elastic body 16.
However, it is not necessary to form a cam storage chamber in one of the molds 11. For example, as shown in FIG. A cam unit 12 including a drive cam 18 and a drive cam 18 protruding from the side surface of the other mold 12 may be provided.

(Effects of the Invention) As explained above, according to the blow molding mold of the present invention, in a blow molding mold consisting of a plurality of split molds that sandwich the injected parison, one mold has a
A slide cam is provided with a weir that crosses the clamped portion of the parison, and the slide cam is biased so that the base can move toward the outside of the mold, and the base is pressed against the other mold during mold matching. Since the structure includes a drive cam surface that pushes the slide cam so that the base faces into the mold, the weir prevents the parison from escaping outside the mold when it is pressed between the divided molds. Moreover, since the parison is forcibly pushed into the mold by the moving base, for example, if the flesh is pulled by the expansion caused by blowing after crimping, the amount of flesh on the inner surface of the crimped part will be insufficient and a dent will occur. This can be prevented, and by making the wall thickness sufficient, it has the effect of resolving the lack of strength in the molded product.

[Brief explanation of the drawing]

Figures 1 and 2 are a side cross-sectional view explaining the state before the parison is sandwiched in blow molding using a conventional blow molding die, and a side cross-sectional view after molding, and Figure 3 is the molding with burrs attached. Figure 4 is a perspective view of the molded product with the burrs removed, Figure 5 is a sectional view taken along the line B-B of the crimping part in Figure 4, Figures 6 and 7 are the metal parts. FIG. 8 is a cross-sectional view illustrating an example of the shape of the clamped portion in the mold, FIG. 8 is a perspective view illustrating the blow molding mold according to an embodiment of the present invention in an open state, and FIG. 9 is a diagram showing two molds brought close together. FIG. 1O is a cross-sectional view explaining the state of the slide cam and drive cam of the mold in the closed state, and FIG. 11 is the mold in the closed state. FIG. 12 is a cross-sectional view explaining the crimped part of the molded product after blow molding, FIG.
The figure is a perspective view illustrating a state in which a cam unit is attached to a mold. 6... Parison, 10... Blow molding mold, 11... One mold, 12... Other mold, 15... Slide cam, 16... Elastic body, 17... Weir, 18a...Drive cam surface, 1ri...Cam unit, A...Pressed part. Patent applicant: Nissan Motor Co., Ltd. Patent attorney Yutaka Oshio Figure 2 Figure 3 Figure 4 Figure 51! I 6th Figure 7 Figure 9 Figure 10 Figure 11 Figure 1

Claims (1)

[Claims] (1) In a blow molding mold consisting of a plurality of split molds that sandwich the injected parison, one mold is provided with a slide cam attached to a weir that crosses the clamped portion of the parison, and the weir is The slide cam is urged so that it can move toward the outside of the mold, and the other mold is provided with a drive cam surface that pushes the slide cam so that the weir moves toward the inside of the mold during mold matching. Characteristic blow molding mold.