JPH0617061B2 - Method for manufacturing deformed hollow body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for producing a deformed hollow body such as a curved pipe.

(Prior Art) Conventionally, as a method for manufacturing a deformed hollow body such as a curved pipe, for example, as disclosed in Japanese Patent Publication No. 53-18418,
A pair of split molds are closed with the upper and lower ends of the cavity open, the parison is dropped into the cavity from the upper end opening, the upper and lower ends of the cavity are closed with a shutter, and then pressurized fluid is pressed into the parison. It is known to mold by molding.

However, according to this method, after closing the pair of split molds, the parison is dropped and inserted along the cavity surface from the upper end opening of the cavity, so it is difficult to insert the parison depending on the product shape, and it takes time, Further, since the contact area between the cavity surface and the parison is large and the contact time is long, the temperature of the parison is likely to drop. In particular, in the case of a product having a small radius of curvature of bending, the insertion of the parison may be stagnant at the bending portion and wrinkled, or the progress of the parison may stop and the parison may not be inserted.

As a manufacturing method for solving such a problem, for example,
As disclosed in Japanese Patent Publication No. 58-47337, there has been proposed one in which a parison is inserted downward from the upper end openings of a pair of split cavities, and a parison is inserted through the lower end openings of the cavities by a suction device. There is.

However, in this method, a suction device must be added, which not only increases the cost but also causes a problem that the temperature of the parison is lowered because heat is released to the outside of the mold by suction.

(Problems to be Solved by the Invention) As described above, according to the conventional method, there are problems of difficulty in inserting the parison and temperature decrease of the parison.

The present invention has been made in view of the above-mentioned problems, and it is possible to quickly insert the parison into the cavity while preventing the temperature decrease of the parison, and to enable blow molding without producing flash. It is intended.

[Structure of Invention]

(Means for Solving the Problems) The present invention uses a pair of split molds 1 each of which is composed of a split mold main portion 5 and a split mold upper portion 8 and a split side lower portion 10 on the upper and lower portions of the split mold main portion 5, The parison 13 is placed at the upper end of the cavity 4 of the split mold main portion 5 with at least the split mold main portions 5 of the pair of split molds 1 being close to each other with a gap of about 1 to 1/3 times the parison diameter. After being dropped and inserted from the opening along the inner surface of the cavity 4, the split mold main portion 5, the split mold upper portion 8 and the split mold lower portion 10 are closed, and a pressurized fluid is press-fitted into the parison 13.

(Operation) In the present invention, the split mold main portion 5 of the pair of split molds 1 has a parison diameter of 1
The parison 13 is moved downward from the upper end opening of the cavity 4 along the inner surface of the cavity 4 in this state with a gap l of about 1/3 to 1/3, and the split main part 5, the split upper part 8 and A mold lower part (10) is closed, a pressurized fluid is press-fitted into a parison (13), and blow molding is performed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 is a pair of split molds that compose a mold, and this pair of split molds 1
Is a plurality of guide pins 3 on opposite surfaces of the mold mounting plates 2 on both sides.
, A split mold main portion 5 having a cavity 4 formed on the opposite surface is movably supported by the guide pin 3, and the split mold main portion 5 has a coil-like shape interposed in the guide pin 3. The springs 6 are biased toward each other. Further, a split mold upper portion 8 having a cavity 7 formed on the facing surface and a split mold lower portion 10 having a cavity 9 formed on the facing surface are fixed to the mold mounting plates 2 on both sides of the split mold main portion 5. . Reference numeral 11 denotes a parison extrusion head disposed above the pair of split molds 1, and a blowing nozzle 12 is provided at the center of the lower end of the parison extrusion head 11.

Then, in molding, first, FIG. 1 and FIG.
As shown in the figure, the pair of split molds 1 are brought close to each other, and the split mold main portions 5 are brought close to each other to a position where a predetermined gap 1 is left between their facing surfaces and stopped. In this state, the split mold main portion 5 is pressed by the spring 6 and is in the advanced position, and the split mold upper portion 8 and the split mold lower portion 10 are in positions far away from the mold closed position. Therefore, the upper end opening of the cavity 4 of the split mold main portion 5 is not covered by the split mold upper portion 8.

Next, the parison 13 made of a thermoplastic synthetic resin is discharged from the parison extrusion head 11 and the cavity 4 of the split mold main portion 5 is discharged.
Is dropped and inserted from the upper end opening along the inner surface of the cavity 4, and the end is hung down to a position where the lower part 10 of the split mold can be held. At this time, since the split mold main portion 5 is located at a close position with a gap 1 left and the passage of the parison 13 has some space, it can be quickly inserted even in the case of a product having a relatively small bending radius of curvature. Moreover, even in the place where the parison 13 was in contact with the inner surface of the cavity 4 in a large area in the past,
In some cases, the parison 13 can pass by only making line contact with the parting line of the cavity, and the parison corresponding to the gap l
Of course, since the portion does not contact the cavity 4 surface, as a result, the contact area between the parison 13 and the cavity 4 surface is greatly reduced as a whole, and the temperature decrease of the parison 13 is alleviated.

Then, as shown in FIGS. 2 and 4, when the pair of split molds 1 are closed, the opposing surfaces of the split mold main portion 5 are joined together against the elastic force of the spring 6, and the split molds are joined together. The facing surfaces of the upper part 8 and the split mold lower part 10 are joined together, and the parison 13 is entirely accommodated in the cavities 4, 7, 9 except for the upper and lower cut portions.

Next, blow air as a pressurized fluid into the parison 13 from the blow nozzle 12 to perform blow molding, and after cooling, the mold is opened and the product is taken out. can get.

The pair of split molds 1 of the split mold 1 are placed close to each other to form the parison 13
If the gap 1 when inserting is too large, the parison 13 will deviate from the cavity 4, and if it is too small, the effect will not be obtained. Therefore, for example, 1 to 1/3 times the diameter of the parison 13, for example,
In the case of molding an air-conditioning duct for automobiles, a normal length of about 15 mm is preferable.

〔The invention's effect〕

According to the present invention, the split mold main parts of the pair of split molds are brought close to each other with a gap of about 1 to 1/3 times the parison diameter, and in this state, the parison is opened from the upper end opening of the cavity to the inner surface of the cavity. The main body of the split mold, the upper part of the split mold, and the lower part of the split mold are closed at the same time to pressurize the pressurized fluid into the parison for blow molding. Even in the case of (1), the parison can be quickly inserted into the cavity and blow molded without burrs while the temperature of the parison is prevented from being lowered, and the mold device can be simplified, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a side view of a mold when the parison is suspended, and FIG. 2 is a side view of the mold when the mold is closed.
3 is a perspective view of a part of FIG. 1, and FIG. 4 is a perspective view of FIG. 1 ... Split mold, 4 ... Cavity, 5 ... Split mold main part, 8 ...
… Split mold upper part, 10 …… Split mold lower part, 13 …… Parison, l ……
gap.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Chojiro Sano, No. 1275, 1237, Fuji-shi, Shizuoka Prefecture, Gakunan Organic Co., Ltd. (56) References JP-A-60-96433 (JP, A) JP-A-62-297133 (JP, A)

Claims (1)

[Claims] 1. A pair of split molds comprising a split mold main portion and split mold upper and lower split mold upper and lower split mold main parts, at least split mold main portions of the pair of split molds having a parison diameter. Of 1
After placing the parison down along the inner surface of the cavity from the top opening of the cavity of the split mold main part with a gap of about 1/3 to 1/3 close to each other, The upper part and the lower part of the split mold are closed, and a pressurized fluid is pressed into the parison. A method for producing a deformed hollow body, comprising: