JPS59150731A - Hollow double-wall box and method and apparatus for forming the same - Google Patents

Abstract

PURPOSE:To form a hollow double-wall box particularly having a large depth relative to a width by a method wherein a mold is divided into a plurality of pieces movable independently of one another so as to possibly avoid an extruded cylindrical parison from contacting with the mold wall. CONSTITUTION:A cylindrical parison 2 extruded from an extruding die 1 is held between an outer frame 4d of a male mold 4 and an outer frame 5b of a female mold 5 to be enclosed in a space defined by the male and female molds. While high pressure air is blown in through a blow pin 3 to expand the parison 2, a slide core 4a is first moved to approach and contact with the parison 2 and then moved reversely with a slide core 4c being projected toward a slide core 5a, causing the parison 2 to be pushed toward the slide core 5a. In this state, the slide core 4b is projected and high pressure air is blown in, so that the parison 2 comes into close contact with the mold wall, thus making it possible to manufacture a hollow double-wall box.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] This invention relates to a double-wall box with a deep middle wall obtained by resin blow molding, a method for molding the same, and a molding tc apparatus. It is something.

[Prior art]

As shown in Fig. 1, a mold for resin blow molding for obtaining a conventional double-wall box has a semi-molten resin (hereinafter referred to as parison) extruded from an extrusion die 1, hanging down, and sealed at the lower end. A male mold 4 and a female mold were formed into a box shape by grip-probing 2 with a probe 3. It had a structure in which it was sandwiched by J5. Therefore, when the molds 4 and 5 are moved closer to each other and the parison 2 is inserted, the parison 2 comes into contact with the mold wall and sticks at that part, so that the parison 2 is no longer deformed by the mold wall. This is done only in the part that is not in contact with the (hereinafter referred to as the free expansion part), so in the end,
As a result of local elongation, the parison 2 becomes thinner and cannot withstand internal pressure, often resulting in local breakage as shown in FIG. For this reason, in the conventional technique, the aperture ratio of the box shape (
The ratio of the depth dimension to the frontage W was at most about ■. Note that FIG. 2 shows a plane view taken along line A-Am in FIG. 1 above.

Next, let's talk about corner B, which has a large local elongation! 5i! For clarity, an enlarged view of the corner portion 3 in FIG. 3 is shown in FIG. i@4. 2a shows the contact part of the parison 2 with the mold wall, and in this state, the parison 2 is under internal pressure (5 to 1 owf).
/cnf) and expands, only the free expansion fR12b is expanded and deformed, resulting in the state shown in FIG. That is, parison 2 according to the conventional method
The wall thickness ratio (tt/, t+) is 0.1 to 0.3, which is an extremely small value, and therefore, local rupture may occur as described above, or even if it does not rupture, the strength of the body is weak. It had the disadvantage of forming corners.

[Purpose of the invention]

The purpose of this invention is to eliminate the above-mentioned drawbacks of the prior art,
The purpose of the present invention is to provide a hollow double-walled box body obtained by resin blow molding, which is particularly deep in relation to its frontage, and a method and apparatus for molding the same.

[Summary of the invention]

In short, in order to achieve the above object, this invention focuses on the fact that the cause of the extremely thinning of the parison at the corners of the trap and mold is due to local elongation of the parison due to its adhesion to the mold wall. In order to prevent the above-mentioned local elongation, efforts were made to reduce the contact area between the parison and the mold wall as much as possible. That is, extruded from an extrusion die.

In order to finally form the cylindrical parison into an asymmetrical box, the mold is divided into a plurality of pieces that each move independently to prevent the parison from touching the mold wall as much as possible. It is divided and molded.

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings.

Note that the same reference numerals are given to the same or equivalent parts as in the conventional example. 6 to 10 are longitudinal cross-sectional views showing the structure of the resin blow molding apparatus of the present invention and the process of forming a box by the molding apparatus. The feature of this molding device is that the box-like molding part of the mold is a sliding core that moves nine times independently of each other.

4a in the male mold 4 is a slide core for molding the end face of the box (see Figure 10 below), and 4b in the slide core 4a is for molding the inside of the box (m in Figure 10 below). 4c in the slide core 4b.
This is a slide core for molding the inside qm of the box body without the parison 2 contacting the entire surface of the mold wall together with the slide core 4a, and is made into a rod shape for this purpose. Further, 5a of the female mold 5 indicates a slide core for molding the outer surface of the box (n) in FIG. 10, which will be described later.

First, the operation of forming a box by the above-mentioned forming apparatus will be sequentially explained. Figure 7 shows the outer frame 4d of the male mold 4 and the female Oyohi mold 5.
After sandwiching the parinon 2 with the outer frame 5b of the
The parison 2 is being expanded by blowing high pressure air (5 to 10 kp f/cm) through the pin 3. At this time, the slide cores 4a, 4b, 4C and 5 are still inflated.
a is drawn into the mold, and parison 2
Because they are placed equidistantly between each other, parison 2 has a nearly spherical shape. FIG. 8 shows a state in which the parison 2 continues to expand freely and finally contacts the slide core 5a, and the slide core 4a moves in the direction of contacting the parison 2 earlier, and its tip Although this is a diagram showing a state in which the parison 2 is moved in the opposite direction and returned to its original position after being made to adhere, in reality, before the slide core 4a returns to the above 11, as shown in FIG. ,
Slide core 4C protrudes in the direction of slide core 5a. The operation of the slide core 4a is performed by utilizing the adhesion between the parison 2 and the slide core 4a.
This is to equalize the wall thickness of the contacting part of the outer frame 4d of the male die 4 (k in FIG. 10 described below) K.
A small hole with a diameter of 02 to Q and 3 rrm is provided in the part that comes into contact with the material, and Makabe blowing is performed through the small hole. Figure 9 shows
While pushing the parison 2 in the direction of the slide core 5a by the protrusion of the slide core 4C, the blow pin 3
This shows a state in which the inside of the parison 2, which has been inflated by the high-pressure sudden air passing through it, is being suctioned through the blow pin 5. In the above manner, the parison 2 is adhesively restrained at the contact points with the slide cores 4a, 4C, and 5a, so the parts C and D shown in the figure freely expand inward of the parison 2, and the parison 2 is pushed against the mold wall. This means that by simply applying adhesive to a portion of the box, it was possible to make it closely resemble the final shape of the box. Next, if the slide core 4b is made to protrude in this state, it will protrude to the outside of the parison 2 without sticking due to the effect of the tapered portion around the slide core 4b, and
High pressure air (5 to 10kpf/
cm''), the air between the C and D parts of the parison 2 and the male mold 4 and female mold 5 will blow into the respective outer frames of the male mold 4 and female mold 5, the slide core and each Parison 2 passes through the tiny gap between the slide cores.
is in close contact with the mold wall, and the molding is completed as shown in FIG. Note that the tip of the rod-shaped slide core has a sufficient contact area so as not to break through the Barin/2.

Configure it as follows. .

FIG. 11 shows a box 6 formed by the above molding method using the above molding apparatus, where W, D and H are the outer width and depth of the box 6, respectively.

Represents rows and heights. Note that 6a is the front wall of the box 6 formed by solidifying the parison 2.

6 shows a light item such as a heat insulating material filled into the box body 6 through the hole left by the blow pin 3, and shows an embodiment for using the double-walled middle wall box body as a heat insulating housing. It is.

In the above explanation, the shape of the parison 2 was a cylindrical shape with uniform wall thickness as shown in FIG. It is effective to make the wall thickness of the side that is relatively less deformed thinner and the wall thickness of the side that contacts the male mold 4 thicker.

In addition, as a filling rod into the box 6, two liquids that cause a hardening reaction are mixed on the inner wall of the box 6 and then injected through the hole left by the blow pin 3 to form closed cells and form foam insulation. Material (
For example, it is extremely easy to construct a foam-side uniform heat insulating material).

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to create a light and inexpensive double-walled box with a large bending ratio.

It has the effect of being easily moldable.

[Brief explanation of drawings]

Figure 1 is a longitudinal sectional view of a conventional resin blow molding device,
The figure is a sectional view taken along the line A-A in FIG. Enlarged view of parts, Figures 6 to 1
Figure 0 is a longitudinal sectional view of a molding apparatus showing the configuration and resin blow molding process of an embodiment of the present invention, and Figure 11 is the top dd.
It is a partial cross-sectional perspective view of the box obtained by the method of (1). Explanation of symbols 1...Extrusion die 2...Parison 3...
Blow pin 4...male type 5...female type
6...Patent attorney Akio Takahashi, Patent attorney, Akio Takahashi No. 1, No. 3, No. 4-0 Hard 2 10th Grudge 11th Round 1 Continued from page 1 0 Inventor Yoshio Asahino 800 Oaza Tomita, Ohira-cho, Shimoga-gun, Tochigi Prefecture Hitachi, Ltd. Tochigi Factory -159=

Claims (1)

[Claims] (1) After the cylindrical parison extruded from an extrusion die is confined between the male and female molds, the independent pieces constituting the male and female molds are movable. This is a double-walled box with a large drawing ratio by applying the sudden pressure inside the parison, then depressurizing it, and then pressurizing it again. (22) A patent claim characterized in that, in the double-walled inner box, two or more types of materials that cause a curing reaction are injected into the entire inside of the box to generate closed cells to form a foamed heat insulating material. (3) In resin blow molding, after the cylindrical parison extruded from the extrusion die is confined between the limiting walls in the male mold and the female mold, It is characterized by molding a box body with two internal walls and a wide drawing ratio by pressurizing or depressurizing the sudden pressure inside the parison while moving the independent pieces constituting the male type and female type. A method for forming a double-walled inner box body. (4) In fallen fat blow molding, the male mold of the mold is
Molding of a medium-sized two-wall box body, characterized in that pieces for forming the end face and inner wall of the box body, and pieces for positioning the parison are each independently provided so as to be spaced apart from each other. Device.