JPS59184625A - Manufacture of hollow caselike body - Google Patents

Abstract

PURPOSE:To manufacture a deep hollow caselike body into a hollow part of which a foaming heat insulator is poured, by making blow molding by making use of a plurality of slide cores made of metal molds for molding, which are movable independently each other, jointly with vacuum suction. CONSTITUTION:Blowing air is blown into a parison 2 after the parison 2 has been placed between a male mold 4 and a female mold 5. With expansion of the parison 2 the parison 2 is protruded in the direction of a slide core 4b, the parison 2 is sticked to the slide core 4b and the parison 2 is supported by a slide core 4d by protruding it directly before returning of the parison to an original position. Then the parison 2 which has been expanded so far is made to resemble closely to a final shape of a doorlike body 2' by making vacuum suction through a blow pin 3. Then when high pressure air is blown in the parison again through the blow pin 3 upon completion of positioning of each of the slide cores, the parison 2 is turned into a shape of a completed product by sticking closely to the surfaces of the male mold 4 and the female mold 5. Then a hollow part is filled with a foaming agent and foaming is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a hollow box body by molding the hollow box body by blow molding.

[Background of the invention]

A method of molding a door body of a refrigerator, which is an example of a hollow box body, by a conventional blow molding method will be explained with reference to FIGS. 1 to 5. First, in FIG. 1, the nozzle 2 that has come down from the extrusion die 1 is sealed with the lower end, and is blown by the blow bin 6 to form the male die 4 and the female die 5 of the mold.
This shows the state immediately before being caught between the two. FIG. 2 shows a state in which the parison 2 is damaged because the male die 4 and the female die 5 move and the parison 2 cannot fully extend into the recess 4 of the male die 4 (section 7 in the figure). In this case, it is difficult to form a protrusion with a deep depth relative to the frontage like the door body of a refrigerator, and at best, as shown in Fig.
Aperture ratio of protrusion 2a (depth dimension D/frontage dimension VO)
There was a drawback that only a protrusion with a low height of about 0.05 could be obtained. In addition, FIG. 4 shows an enlarged view of part 7 in FIG. 2 to explain the thinning of the parison 2 in the protrusion 2 (2), and 2h is the male shape of the parison 2. 4. In the state shown in FIG. 4, the parison 2 is under internal pressure (5 to 10 kgf 1crl
), the parison 2 expands at the contact point 2
Since the parison 2 adheres to and is restrained by the surface of the male die 4 at the point A, only the free expansion part 2C deforms, and the thickness of the parison 2 rapidly decreases, resulting in the state shown in FIG. Become.

In other words, the wall thickness ratio ('2/'+) of parison 2 is 0 to 0.
1, and there was the above-mentioned drawback that the protrusion 2a could not be formed, or even if it could be formed, only a low protrusion 2a could be formed.

[Purpose of the invention]

The present invention eliminates the drawbacks of the prior art described above and provides a method for manufacturing a hollow box body having a protrusion with a deep depth relative to the frontage (that is, a large drawing ratio) by blow molding.

[Summary of the invention]

In short, this invention is an attempt to improve the non-uniformity of the wall thickness of a molded product in order to enable the molding of a hollow box body with a large drawing ratio, which serves as a gap in blow molding. In particular, we focused on the fact that the cause of the extreme thinning of the protrusion with a large drawing ratio is the local elongation at the drying point due to adhesion of the parison to the surface of the male mold, and found that the parison contacts the surface of the male mold. Embodiments of the Invention The present invention will be described below with reference to the drawings.

FIG. 6 shows a longitudinal sectional view of an embodiment of a molding die for carrying out the present invention. Hereinafter, parts that are the same as or equivalent to those of the above-mentioned conventional example (FIGS. 1 to 5) are given the same reference numerals. A feature of the male mold 4 and female mold 5 of the molding mold is that the portions forming the door body 2 are of the "insert type", that is, a sliding core, which can slide independently of each other.

First, to explain the structure, the male mold 4f) 4α is a slide core for forming the end face of the door body 2, 4b is a slide core for forming the protrusion 2α of the door body 2, and dc is the slide core for forming the protrusion 2α of the door body 2. Slide core to form the inner surface, also 4d
is a rod-shaped slide core for forming the inside of the door body 2' without the parison 2 contacting the entire surface of the male die 4 together with the slide core 415. In addition, 5α of the female mold 5 is a slide core for forming the outside of the door body 2.

An embodiment of the method for manufacturing a refrigerator door according to the present invention will be described with reference to FIGS. 7 to 10. Figure 7 shows
After the parison 2 is clamped between the male mold 4 and the female mold 5, high pressure air (5 to 10 kgf/r/r) is blown through the blow pin 3 as shown by the arrow in the figure to inflate the parison 2. Indicates a state in which At this time, the slide cores 4σ, 4h, 4c, Ad, and 5α are still drawn into the male mold 4 and the female mold 5.

The parison 2 has a nearly spherical shape. 8th
The figure shows that the parison 2 continues to expand and contacts the slide core 5α on the right side of the figure, and the slide core 4h protrudes toward the high IJ son 2 on the left side, and the parison 2 is attached to its tip. The slide core 4h returns to its original position as shown in the figure, and just before the slide core 4h returns to its original position, the slide core 4d protrudes to support the parison 2 so that the parison 2 does not stick to the surface of the slide core 4c. ing. The above-mentioned action of the slide core 415 on the parison 2 is to make use of the adhesiveness of the parison 2 and to equalize the wall thickness of the parts where the parison 2 contacts each part of the male mold 4. In order to make the parison 2 positively adhere to the cores 4b and 4d, a dwarf (diameter 02-03) is provided on the surface where the slide cores 4h and 4d contact the parison 2, and the parison is inserted through the elbow small hole. A method of vacuum suctioning 2 may also be used.

FIG. 9 shows a state in which the parison 2, which has been expanded so far, is being vacuum-suctioned through the blow pin 3 in the direction of the arrow shown in the figure. Since the part of the parison 2 is adhesively restrained at the contact point, the part that is free to expand and is not restrained deforms in the opposite direction (inward direction). It is possible to closely resemble the finished product, which is the final shape of the body. When the slide cores 4α and 4c are projected to the right in this state, the air in the portions A, B, and C′ shown in the figure escapes through the gaps between the slide cores 4σ and 4c.
4c protrudes from the outer surface of parison 2 without rubbing, and the 1st o
As shown in the figure, after completing the positioning of each slide core, high pressure air (5 to 10 k!
f/cJ), parison 2 becomes fully male type 4.
and comes into close contact with the surface of the female mold 5 to form the shape of the finished product. In addition,
The tip of the rod-shaped slide core 4d is plate-shaped so as not to break through the parison 2. FIG. 11 is a perspective view showing a completed product of the door body 2 which has been added and removed from the above-mentioned complete model, in which 2α indicates the above-mentioned protrusion and 2e indicates the remains of the blowbin 6. Further, FIG. 12 is a sectional view of FIG. 11 above,
2j indicates a filler such as a heat insulating material, and the drawing ratio (=/)/rr'o of the protrusion 2σ obtained by the manufacturing method of the present invention is
It is extremely thick, like 20 to 30. However, the apparent drawing ratio during molding is 1 no/W (<l)/li'o
), which is advantageous. This is because while the above conventional method only expands the parison 2 in one direction, the method of this invention expands each slide core in one direction. It is completely different in that the parison 2 is expanded, contracted, and expanded as it is pushed.

Note that by changing the cross-sectional shape of the extrusion die 1, the thickness of the parison 2 relative to the male mold 4 can be increased.

On the other hand, if the thickness of the parison 2 relative to the #-shape 5 is made thinner, even better results can be obtained.

``Effects of the Invention'' As explained above, according to the present invention, hollow boxes such as refrigerator doors, which have a deep depth (that is, a large aperture ratio of 20 to 60) with respect to one width, can be extremely manufactured. It is easy to manufacture, and if the hollow part of the hollow box is filled with a heat insulating material such as foamed resin, a box with high heat insulation effect can be manufactured in one or two steps, and it can be manufactured using conventional steel plates. Compared to conventional structures in which plastic molded products are assembled by injection molding or profile molding, the product weight can be reduced by approximately 70%, and the product cost can be reduced to approximately i or less. .

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a conventional blow molding device, Fig. 2 is a longitudinal sectional view of a state in which the forming process has progressed from Fig. 1, and Fig. 6 is a completed product obtained by the conventional manufacturing method described above. 4 and 5 are enlarged views of section A in FIG. 2, and FIGS. 6 to 10 are longitudinal sections of the manufacturing equipment in each manufacturing process for carrying out this invention. 11 is a perspective view of a finished product obtained by the manufacturing method of the present invention, and FIG. 12 is a perspective view of a finished product obtained by the manufacturing method of this invention.
A sectional view of FIG. 11 is shown. Explanation of symbols 1...Extrusion die, 2...Parison, 2'...
Door body. 2a... protrusion, 3... blowbin, 4... male fJ
, aa. dir, 4c, ad...slide core, 5.
...Female type, 5α...Slide core. Representative Patent Attorney Akio Takahashi District Figure 4 Figure y Flash Figure 6 Figure 7 Figure 3 District No. ′. /Country 1st Oen 11th Spit 12ml

Claims (1)

[Claims] A hollow box body is formed by forming a hollow molded product by blow molding, and injecting and foaming a foamed heat insulating material into the hollow part of the hollow molded product, and a plurality of slide cores that allow molding molds to move independently of each other. 1. A method for manufacturing a hollow box, characterized in that a protrusion with a deep depth relative to the frontage is provided by using vacuum suction in combination with this.