JPS6018328A - Manufacture of hollow molding article having bent part and device thereof - Google Patents

Abstract

PURPOSE:To obtain a hollow molded article having a bent part whose thickness is uniform, by a method wherein after parison has been supplied within a molding space into predetermined position of the bent part of which a position control component is made to enter, blow molding is performed by making the position control component recede. CONSTITUTION:A shuntable first slide pin 5 is arranged close by a wall surface 2a, whose radius of curvature is small, of a pair of opposed wall surfaces 2a, 2b of a bent part of the inside of a cavity 2 of a molding bottom force 1, parison 3 is extruded within the cavity 2, closing is done by lowering a top force 1' after the parison 3 has been contained between the wall surface 2b and a pin 5 and the pin 5 and a second slide pin 6 fixed to a fixing plate 8 are made to recede. Then after the parison 3 has been positioned on the center of the cavity 2 by moving the parison toward the wall surface 2a, blow molding is done by blowing compressed air within the parison 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow molded article having a curved portion, and more particularly to a method for manufacturing a hollow molded article having a curved portion by blow molding.

Conventionally, as shown in FIG. 1, when a parison 3 is supplied into a cavity 2 having a plurality of curved parts of a mold 1, even if the parison 3 is supplied along the shape of the cavity 2, it will not fit into the cavity curved part. In this case, the parison 3 tends to be biased toward one cavity wall. That is, in the curved portions C+ and C2 of the meandering cavity 2, a pair of curved cavity wall surfaces 2a, 2a- and 2b having different radii of curvature are formed.
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2b- are facing each other, but the housed parison 3 tends to be biased toward the cavity wall surfaces 2a and 28', which have a smaller radius of curvature, probably due to the elasticity and contractility of the parison itself. In this way, if the mold is clamped and blow molding is performed with the parison biased toward one cavity wall at the cavity curved portion, a hollow molded product having an uneven thickness cross section (longitudinal direction) as shown in Fig. 2 is produced. 4 is molded.

That is, in the curved portions C-+ and C-2 of the hollow molded product 4, the wall thicknesses 4b and 4b' on the larger radius of curvature side are thinner, whereas the wall thicknesses 4a and 4 on the smaller radius of curvature side are thinner.
a- tends to be within the thickness. A hollow molded product in which each curved portion is formed with uneven thickness in this manner is inferior in terms of strength.

The invention is based on the above-mentioned points, and aims to provide a method for manufacturing a hollow molded product having a curved portion having a uniform wall thickness even in the curved portion.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, a mold having a unique configuration used in the manufacturing method of the present invention will be explained. As shown in Figure 4, there are two molds: mold (lower mold) 1 and mold (upper mold) 1-.
It consists of two types. At the curved part of the cavity 2 of the lower mold 1, there is a first
A slide bin 5 is provided at a predetermined position. This first slide bin 5 has a tip protruding into the cavity space.
It is configured so that it can be easily evacuated. In the sectional view of FIG. 4, the cross section of the curved part of the cavity 2 is shown.
The right side of the figure shows the cavity wall surface 2b with a larger radius of curvature, and the opposite side shows the cavity wall surface 2a with a smaller radius of curvature. The first slide bin 5 whose tip end protrudes into the cavity 2 described above is disposed close to the cavity wall surface 2a having the smaller radius of curvature. Separately from this, second slide bins 6.6 for interlocking the upper die 1' and the first slide bin 5 are installed from the joint surface of the lower die 1 which joins with the upper die '1-, respectively, at their tips. This second slide bin 6 is arranged so as to protrude by an appropriate length.
．． Like the first slide bin 5, the slide bin 6 is also configured to be able to reciprocate. The ends of these slide bins 5, 6.6, which are housed in the lower die 1, are fixed to a bin fixing plate 8. Springs 7, 7 are attached to the bin fixing plate 8, and the slide bin 5.6.6 is integrally supported via the fixing plate 8 by the elastic force of the springs 7, 7. As a result, when the lower mold 1 and the upper mold 1' are joined during mold clamping, the joint surface of the upper mold 1' and the tip of the second slide bin 6.6 first come into contact with each other, and the upper mold 1- As the lower mold 1 approaches, the second slide bins 6.6 are pressed against the joint surfaces of the upper mold 1' and are slid into the lower mold 1 and stored therein. At this time,
In conjunction with the second slide bin 6.6, the first slide bin 5 protruding into the cavity 2 is also integrally slid and housed inside the lower mold 1. Then, upper mold 1- and lower mold 1
When the slide bin 5. is completely aligned and the mold clamping is completed, the slide bin 5.
6.6 is completely housed inside the lower mold 1, and the upper end surface of the first slide bin 5 constitutes the wall surface of the cavity 2.

The manufacturing method of the present invention using a mold having the above-mentioned unique configuration will be explained. Now, as shown in FIG. 3, there is a mold 1 in which a cavity 2 having, for example, two curved parts is formed. , As mentioned above, the cavity 2 in this mold 1
First slide bins 5, 5 are arranged in the inner curved portion. The first slide bins 5, 5 are disposed close to the wall surface 2a having the smaller radius of curvature of the pair of opposing wall surfaces 2a, 2b of the cavity curved portion. The exact placement positions of the slide bins 5, 5 are determined by the shape of the cavity, the desired wall thickness of the hollow molded product, etc.

In this way, the parison is extruded into the cavity 2 of the mold 1 in which the slide bins 5, 5 are arranged at predetermined positions.
The parison is extruded from the cavity 2, and the parison 3 is housed in the cavity 2 along the shape of the cavity 2. In this case, at the cavity curved portion, the parison 3 is housed between the cavity wall surface 2b having a larger radius of curvature and the first slide bin 5.

After the parison 3 has been completely stored in the mold 1 as described above, the mold is clamped. In this example, as shown in FIG. 4, the upper mold 1- is lowered and joined to the lower mold 1 containing the parison 3 in the cavity 2. At this time, first,
The tip of the second slide bin 6.6 provided on the lower die 1 comes into contact with the alignment surface of the upper die 1-, and as the upper die 1- and the lower die 1 approach, the second slide bin 6.6 moves closer to the lower die. 1 inside spring 7,
At the same time, the M1 slide bin 5 that was regulating the position of the parison 3 also begins to retreat into the lower mold 1. When the upper mold 1' and the lower mold 1 are joined and the mold clamping is completed, the second slide bin 6.6 is completely stored in the lower mold 1, and the first slide bin 5 releases the restriction on the position of the parison 3. do. In this case, the position of the parison 3 was forcibly restricted by the slide bin 5 so that it was positioned one-sidedly toward the cavity wall surface 2b having a larger radius of curvature at the cavity curved portion, so when the slide bin 5 was released, The parison 3 deforms to eliminate the curved portion due to its own elasticity, contractility, etc. That is, the parison 3 begins to move toward the cavity wall surface 2a having a small radius of curvature and is positioned at the center in the width direction of the cavity. In this way, before the pressurized gas is blown into the cavity 2, the parison 3 in the cavity 2 is accommodated in the approximate center of the cavity 2 along the shape thereof. Under these conditions, when pressurized gas is blown into the parison 3, all parts of the parison 3 are expanded approximately evenly, so the wall thickness of the hollow molded product surrounding the completed curved part is Even in curved parts, the thickness is uniform and there is no uneven thickness.
A hollow molded product having a curved part with uniform wall thickness in all parts is molded.

As described in detail above, according to the present invention, it is possible to easily manufacture a hollow molded product having a curved portion with a uniform wall thickness even in the curved portion by blow molding. That is, uneven thickness can be prevented in a hollow molded product having a curved portion by a simple method of providing a slide bin in the cavity to regulate the storage position of the parison. At Nobu, by using such a simple method, the productivity of hollow molded products with curved parts is improved compared to the conventional method of keeping the thickness of the curved part constant using complicated control methods. Cost reduction will be further promoted.

It should be noted that the present invention should not be limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional manufacturing method, Fig. 2 is a sectional view showing a core molded product by the conventional manufacturing method, Fig. 3 is an explanatory diagram explaining one embodiment of the present invention, and Fig. 4 1 is a sectional view showing a mold used in the method of the present invention. (Explanation of symbols) 1: Molding mold (lower mold) 1-: Molding mold (upper mold) 2:
Cavity 3: Parison 5.6: Slide Bin Patent Applicant Elisel Co., Ltd. Figure 1 Figure 2 Figure 3 Ili Fourth Case

Claims (1)

[Claims] 1. In a method for manufacturing a hollow molded product having a curved part, a position regulating member for regulating the position of a parison supplied into a molding space of a mold is bent in the molding space. The N regulating member is advanced into the molding space and the parison is supplied along the parison supply position regulated by the position regulating member, and the mold of the mold is Production of a hollow molded product having a curved part, characterized in that the position restriction member is removed from the molding space to release the position restriction, and pressurized gas is blown into the parison to perform blow molding. Method. 2. In the above item 1, the predetermined position from which the position regulating member advances is set to a position close to the wall surface having a smaller inner support ratio radius of the opposing wall surfaces forming the curved part forming space. A method for manufacturing a hollow molded product having a curved part. 3. In an apparatus for producing a hollow molded product having a curved part equipped with at least one pair of molds that can be freely joined, a parison is provided in a predetermined position of the curved part within the molding space of the mold so as to be freely advanced and retracted. A curved section characterized by having a position w dividing member for regulating the position, and an interlocking means for detecting a joining operation of the mold and retracting the position regulating member from the molding space in response to the joining operation. A manufacturing device for hollow molded products.