JPS6334009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for manufacturing plastic tanks.

Conventionally, a method for manufacturing plastic fuel tanks by blow molding was disclosed in Japanese Patent Application Laid-open No. 1986-
As disclosed in No. 15861, while the molds 1 and 2 are brought together as shown in Fig. 1a, the protruding strips 3 and the concave strips 4 are engaged as shown in Fig. 1b, and as shown in Fig. 1c. A method has been proposed in which the pinch-off blades 5 and 6 are also moved to cut off the mating portion 8 of the plastic layer 7 to make the inner and outer appearance flat, and then blow molding is performed.

However, in the conventional method described above, since blow molding is performed after cutting with the pinch-off blades 5 and 6, the finish is often not clean and flat.
Furthermore, because of the flat finish, especially in multilayer blow tanks, there was a problem in that the strength of the mating parts was significantly insufficient at low temperatures.

The present invention was made in view of the above-mentioned conventional problems, and consists of extruding a plastic layer into a split mold,
After aligning the split molds, a plastic layer is blow-molded onto the inner surface of the mold to form a hollow body, and a slide core provided in a recess formed in the mold matching area is moved to move the plastic layer in the recess into the hollow body. This is a manufacturing method for a plastic tank in which the plastic tank is extruded and then cut with a pinch-off blade at the tip of the slide core to form a flat, inwardly extruded thick part with a clean appearance at the joint part to improve strength. This is a new offer.

Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

As shown in FIG. 2a, upper and lower split molds 10,
11 is provided, and a recess 12 is formed in the mold matching portion of the molds 10 and 11.

Slide cores 13 and 14 are provided to be slidable up and down in the recess 12, and the slide cores 13,
Pinch-off blades 13a and 14a are formed at the tip portion of 14.

Therefore, in order to manufacture the plastic tank 15 using the molds 10, 11 and slide cores 13, 14 as described above, first, the plastic layer 16 is extruded into the molds 10, 11, and then the plastic layer 16 is extruded into the molds 10, 11. 11
After collecting a portion of the plastic layer 16 in the recess 12, the plastic layer 16 is placed in the mold 10,
A hollow body 15' is formed by blow molding on the inner surface of 11.

Then, as shown in FIG. 2b, the slide cores 13 and 14 are slid together with the molds 10 and 11 in a double action operation to push out a part of the plastic layer 16 accumulated in the recess 12 into the hollow body 15'. .

At this time, the plastic layer 16 is attached to the molds 10 and 1.
Since the plastic layer 16 is in contact with the plastic layer 16 and its temperature is significantly lowered, the viscosity of the plastic layer 16 becomes high, and the plastic layer 16 becomes inwardly built up.

Thereafter, when the pinch-off blades 13a and 14a of the slide cores 13 and 14 are brought together, the joint portion 16a of the plastic layer 16 is cut off, and the tank 15 is cut off.
is completed.

As shown in Fig. 2c, this tank 15 has a clean and flat appearance because the mating part 16a is cut off after blow molding, and since the thick part 15a serves as the mating part of the tank 15, its strength is significantly increased. improves.

Furthermore, since the thick part 15a is formed inside the tank 15, if it is formed outside the tank 15, stress will concentrate on this convex part and cause damage in the event of a collision. There is no fear.

In addition, in the molding of a multilayer blow tank, depending on the slide timing of the slide cores 13 and 14, the nylon layer may be cut at the joint portion 16a, but this will have almost no effect on the permeation of the filled fuel (gasoline). was confirmed through experiments.

As described above, the present invention involves blow molding a plastic layer to form a hollow body after fitting the split molds together, and then extruding the plastic layer in the recess of the mold into the hollow body using a slide core, and then forming the combined part. This is a method of manufacturing plastic tanks by cutting away the waste.

Therefore, since the mating part is cut off after blow molding, it is possible to finish the tank with a clean and flat appearance, and since an inner thick part is formed at the mating part of the tank, the strength is significantly improved.

[Brief explanation of drawings]

1a to 1c are sectional views showing the process of a conventional tank manufacturing method, and FIGS. 2a to 2c are sectional views showing the process of the tank manufacturing method according to the present invention. 10, 11...divided mold, 12... recess, 13, 1
4... Slide core, 13a, 14a... Pinch-off blade, 15... Tank, 15a... Thick part, 15'...
Hollow body, 16... plastic layer, 16a... mating part.

Claims (1)

[Claims] 1. Extrude the plastic layer into the split molds, match the split molds, blow mold the plastic layer onto the inner surface of the mold to form a hollow body, and insert the slide core provided in the recess formed in the mold matching part. moving the plastic layer within the recess into the hollow body;
A method of manufacturing a plastic tank in which the pinch-off blades at the tip of the slide core are then aligned and cut to form a thick part that has a flat appearance and is extruded inward as the joint part.