JPH0376654B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a blow molding method of thermoplastic resin, in which the molding is performed while performing pressure processing using a mold and a molding core inside.

(Prior art) As a conventional blow molding device, for example,
The one shown in the figure is known.

This conventional blow molding apparatus A is equipped with a deriving device 100 for forming a thermoplastic resin into a cylinder and deriving it, a blowing member 101 provided downward from the deriving device 100, and a mold 102. Ta.

Therefore, when performing molding, the softened resin a is led out downward in a cylindrical shape from the delivery device 100, and then the resin cylinder a1 is closed and clamped from the left and right sides with the mold 102, and the blowing member is Air is blown through the mold 101 to form the mold in close contact with the recess 103 of the mold 102, and then the mold is opened and the molded product a2 is formed.
The molding was completed by pulling out the blowing member 101 from the mold.

In addition, the conventional blow molding apparatus B shown in FIG.
(Refer to Japanese Unexamined Patent Publication No. 57-2727) discloses a drawing device 100 for forming a thermoplastic resin into a cylinder and drawing it out, a pair of left and right molds 104, 105, and a pair of molds 104, 105.
It was equipped with compression parts 106 formed to protrude inward from the mold 105, respectively, and blowing devices 107, 107 provided in the mold 104.

Therefore, when performing molding, the softened resin b is led out downward in a cylindrical shape from the outgoing device 100, and then the resin cylinder b1 is closed from the left and right sides with the molds 104 and 105 and clamped. A part of the resin cylinder b1 is welded at the compression part 106 to form the hinge part 1.
08, and the resin cylinder b1 is blown into the inner surface of the mold by blowing air from the blowing devices 107, 107.
were molded in close contact with each other to form a molded product b2 having a hinge portion 108.

(Problems to be solved by the invention) However, in the case of blow molding apparatus A,
The thickness of the molded product formed is constant everywhere,
For example, if you want to provide a thin hinge part,
The number of molding steps increases, such as by molding the hinge part in advance by injection molding or the like and then blow molding other parts, leading to an increase in mold costs and manufacturing costs.

In order to solve this problem, blow molding equipment B attempted to mold the hinge part only by blow molding, but the product molded by this blow molding equipment B only had parts other than the hinge part. However, this creates a double structure with an air layer in between, resulting in an increased thickness of the molded product, and there are problems in that the material for the double layer is wasted.

(Means for Solving the Problems) Therefore, the present invention was made for the purpose of solving the above-mentioned problems, and in order to achieve this purpose, in the present invention, a resin cylinder is placed inside a mold. When performing blow molding, a molding core supported by a support member is used inside the resin cylinder, and when the mold is clamped, a part of the resin cylinder is pressed by the mold and the molding core, while blow molding is performed. We adopted a configuration that performs the following.

(Function) Therefore, in the blow molding method of the present invention, when performing blow molding, the molding core positioned inside the resin cylinder is brought into contact with the mold via the resin cylinder at the same time as the blow molding. Accordingly, a part of the resin cylinder can be press-molded between the molding core and the mold.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, blow molding for molding a steering column cover for a vehicle will be taken as an example.

First, the structure of the first embodiment shown in FIGS. 1 to 5 will be explained.

Reference numeral 1 denotes a deriving device which transforms the softened thermoplastic resin P into a cylindrical shape and deduces it.

2, 2 are molds which are closed from the left and right to mold resin into the shape of recesses 3, 3, and below each of the molds 2, 2, when facing each other, there is a blowing device (described later). Relief grooves 5, 5 that serve as escape holes 4 are provided.

A blowing device 6 blows air into the resin cylindrical body P1, and is attached to a base 7 provided at the bottom of the deriving device 1, and has a hollow air flow path 8 and a side wall. An air inlet 9 is formed, and the lower end is connected to an air tube 10.
Note that this blowing device 6 also serves as a support device 11 that supports a pressing plate 12 as a molding core, which will be described later.

Reference numeral 12 denotes a holding plate as a molding core, which is supported by the support device 11 and positioned inside the resin cylinder P1 during product molding.The cross section of the end 13 of this holding plate 12 is , has a triangular shape as shown in FIG. They are positioned so that there is a distance t (approximately 0.3 to 0.5 mm) between them.

Next, the operation of the first embodiment will be explained.

First, the resin P softened by heat is drawn out from the drawing device 1, and then, when the resin cylinder P1 is drawn out below the mold 2, the blowing port 9 of the blowing device 6 and the holding plate 12 are drawn out. is the resin cylinder P
1 (FIG. 1).

Thereafter, the molds 2, 2 are closed and clamped from the left and right sides (FIG. 2).

At this time, the end 13 of the pressing plate 12 and the protrusion 14 provided on the inner surface of the mold 2 are opposed to each other, and the distance t between them is about 0.3 to 0.5 mm. For this reason, a portion of the resin cylinder P1 sandwiched between the presser plate 12 and the protrusion 14 is press-molded to a thickness of 0.3~
The thin wall portion 15 is about 0.5 mm.

Next, when air is blown into the resin cylindrical body P1 from the blowing port 9 of the blowing device 6, the resin cylindrical body P1 is expanded and pressed against the inner wall surfaces of the recesses 3, 3 of the molds 2, 2, and then, It hardens as the temperature decreases. At this time, the wall thickness other than the thin portion 15 is approximately 1.5 to 3 mm.

Thereafter, the molds 2 and 2 are opened, first cut along the separation line L1 shown in FIG. Separate line L set to roughly bisect
2 (indicated by the two-dot chain line in Fig. 4), the thin part 15 is removed, the molded product P2 is removed from the blowing device, and the excess material is cut off to form the product P3, and the molding is completed. . In this way, the thin part 1
A product P3 in which 5 is a hinge portion can be manufactured.

Next, a second embodiment shown in FIG. 6 will be described.

This embodiment is based on the holding plate 1 in the first embodiment.
2 and the protrusion 14, a slide pin 18 as a molding core supported by a support device 16 (blow device 17), and a gap t (1.5 to 3 mm) between the slide pin 18 and the slide pin 18 provided on the mold 2. This is an example in which a fitting hole 19 is provided in which the fitting hole 19 is fitted in a protruding state.

Therefore, during molding, the slide pin 18 is inserted into the mold 2.
A part of the resin cylindrical body P1 protrudes into the fitting hole 19 of the mold 2 by sliding it toward , and the outer surface is The inner surface of the fitting hole 19 and the inner surface can be molded into a product with a shape similar to the outer surface of the slide pin 18, and the other parts have the same shape as the first embodiment, but there is no uneven thickness and some parts are protruded. A product with a built-in part can be manufactured by blow molding.

Note that other configurations and operations in the second embodiment are similar to those in the first embodiment, so the same parts are denoted by the same reference numerals and description thereof will be omitted.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in describing the embodiment, a blow molding machine for molding a steering column cover was taken as an example, but as shown in the second embodiment, blow molding equipment for molding not only steering column covers but also other products is used. It may also be a device.

Further, the width of the gap, the wall thickness, etc. used in the examples are not limited to the examples and may be arbitrarily determined.

(Effects of the Invention) As described above, in the blow molding method of the present invention, a molding core is provided which is positioned inside the resin cylinder during molding, and is applied from the inside to the outside mold through the resin cylinder. Because of the configuration in which a part of the resin cylinder is press-molded, conventionally blow molding was used to form a thin wall part to provide a hinge part or to provide a precision internal thread on the inside of the product. It is possible to obtain the effect that a blow molded product having a portion with a changed wall thickness, shape, etc. can be molded by one blow molding without the need for injection molding or the use of extra materials, which was required before the blow molding.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the blow molding device used in the first embodiment of the present invention in a state before mold clamping, and FIG.
3 is a cross-sectional view showing the mold opening state of the device used in the first example, FIG. 4 is a cross-sectional view of FIG. 2, and FIG.
The figure is a detailed view of the main part of Figure 4, and Figure 6 is a detailed view of the main part of Figure 4.
A sectional view showing a blow molding device used in Examples,
FIG. 7 is a sectional view showing a conventional blow molding apparatus A;
FIG. 8 is a sectional view showing a conventional blow molding apparatus B. FIG. 2...Molding die, 11...Support device, 12...Press plate (molding core), 16...Support device, 18...
...Slide pin (molding core), 20...Support device,
22...Cylinder (molding core), A...Blow molding device, B...Blow molding device, P1...Resin cylinder.

Claims (1)

[Claims] 1. When blow molding a resin cylinder in a mold, a molding core supported by a support member is used inside the resin cylinder, and when the mold is clamped, a part of the resin cylinder is blow-molded by the mold and the molding core. A blow molding method in which a part of a molded article has a press processing part, characterized in that blow molding is performed while applying a press process.