JPS6147230A - Blow molding method - Google Patents

Abstract

PURPOSE:To enable to manufacture an open-sided product or a product with intricate form by a method wherein parison is pinched between a gas blow-off member and a plurality of molds by shifting the molds and compressed gas is blown off from the blow-off holes of the gas blow-off member. CONSTITUTION:Firstly, parison 13 is extruded from an extruder 14 in between a gas blow-off member 12 and at least either one of molds 11a and 11b under the state that the gas blow-off member 12 is installed in the interior of a plurality of the molds 11a and 11b. Secondly, the molds 11a and 11b are shifted so as to close the molds. Thirdly, compressed air is blown off from a large number of blow-off holes bored on the blow-off member 12 under the state that the parison 13 is pinched between the blow-off member 12 and the molds 11a and 11b so as to press the parison against the molds along the form of a cavity in order to mold the parison into the predetermined form. Finally, an open-sided molded part is manufactured by opening the molds after the cooling of the parsion is competed and, after that, taking the molded part out of the molds.

Description

[Detailed description of the invention] purpose of invention (Industrial application field) This invention relates to a blow molding method.

(Prior art) When manufacturing a molded article by blow molding, a thermoplastic material heated and melted in an extruder 1 is extruded as a cylindrical parison 2, as shown in FIG. 4(a). Mold 3a
, 3b, the compressed gas injected from the nozzle 4 causes the molds 3a,
It expands within 3b to produce a hollow molded product 5. In this way, the conventional blow molding method can only mold a hollow molded product 5, so when manufacturing a product 6 with one side open, it is necessary to divide the hollow product molded by blow molding. (See Figure 5), there is a problem that not only is it time-consuming to divide, but also that a large amount of resin unnecessary for the product 6 is required during molding, resulting in a poor yield. Further, when manufacturing a product 6 having a flange portion 6a as shown in FIG. 6, secondary processing is required, which again poses the problem of labor and material yield of the secondary processing.

(Problems to be Solved by the Invention) This invention can mold a product with one side open, which could not be achieved with conventional blow molding methods, and
The present invention provides a new blow molding method that can produce products with complex shapes as well as injection molded products.

Structure of the Invention (Means for Solving the Problems) As a means for solving the above-mentioned problems, in the present invention, a plurality of molds contain compressed gas that is held between the molds during mold clamping. A gas blowing member having a blowing outlet of A method in which the parison is moved and held between a gas blowing member and a mold, and the parison is pressed against the cavity surface of the mold by blowing out compressed gas from the blowing port of the gas blowing member. It was adopted.

(Operation) In the present invention, a parison is extruded from an extruder between the gas blowing member and at least one of the molds with the gas blowing member disposed inside a plurality of molds. Then, a plurality of molds are moved and clamped, and compressed gas is blown out from a number of outlets formed in the gas blowing member with the parison being held between the gas blowing member and the molds. The parison is pressed against the mold along the shape of the cavity of the mold by the action of compressed gas, and is molded into a predetermined shape. Next, after cooling of the parison is completed, the mold is opened and the molded product is taken out from inside the mold, thereby producing a molded product with one side open.

(Example) An example embodying the present invention will be described below with reference to Fig. 1.2. A pair of left and right molds 11a formed symmetrically,
At the center of 11b, there is an air chamber 12a having almost the same height and width as the molds 11a and 11b, a plurality of air outlets 12b formed on both sides of the air chamber 12a, and a connecting pipe 12c connected to a compressed air source (not shown). A gas blowing member 12 consisting of the following is provided. An extruder 1114 is disposed above the gas blowing member 12 to heat and melt the raw resin and extrude it as two sheet-shaped parisons 13.

Now, when forming a molded product using this apparatus, as shown in FIG. After extruding until the lower end of the left and right molds 11a and 11b reach the lower ends of the left and right molds 11a and 11b,
b to the gas blowing member 12 side, and the parison 13 is held between the gas blowing member 12 and both the left and right molds 11a and 11b. After the parison 13 is clamped, compressed air is blown out from each outlet 12b of the gas blowing member 12, and the parison 13 is
is pressed into both the left and right molds and molded into a shape that follows the mold cavity. After the compressed air is introduced into the air seedling 12a, it is blown out from each outlet 12b.
Air with almost the same pressure is blown out from 2b and the parison 13
All parts are pressed uniformly. Further, since the cavity of the mold is divided by the gas blowing member 12, by opening the mold 118.11b after cooling is completed and taking out the molded product 15, it is possible to simultaneously obtain two products with one side open.

Note that the present invention is not limited to the above-mentioned embodiments. For example, as shown in FIG.
It can also be applied to a cylindrical parison 13 in the same way as a normal bouquet o-i type. Also, mold 1
1a and 11b do not necessarily have to be formed symmetrically, and may be formed asymmetrically. Further, according to the blow molding method of the present invention, it is possible to manufacture products with complex shapes similar to injection molded products, but the injection pressure is usually as high as 800 to 2000 ko/cd, The mold also needs to be pressure resistant, which increases the cost, but when implementing the blow molding method of this invention, the pressure of compressed air is 3 to 10 kg/cnr, which is the same as in the normal blow molding method, so the mold Since pressure resistance is not required so much, it is possible to reduce mold cost and energy.

Effects of the Invention As detailed above, according to the present invention, it is possible to mold a product that is not hollow and has one side open, and even though it is blow molded, it can be molded with a complex shape similar to injection molded products. This has the excellent effect of reducing mold costs and energy consumption.

[Brief explanation of the drawing]

Figures 1 (a) to (C) are cutaway front views showing the sequence of the blow molding method embodying this invention, and Figure 2 is Figure 1 (a).
), FIG. 3 is a perspective view showing another parison, FIGS. 4(a) to <C> are sectional views showing the order of the conventional blow molding method, and FIG. 5 is blow molding. FIG. 6 is a cross-sectional view showing a divided state of the product, and is a cross-sectional view of a product that requires secondary processing in the conventional method. Molds 11a, 11b, gas blowing member 12, air outlet 12a
1 outlet 12b1 parison 13, extrusion hoe 14, molded product 1
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Claims (1)

[Claims] 1. A gas blow-off member having a blow-off port for compressed gas that is clamped by the molds when the molds are clamped is disposed inside the plurality of molds, and the gas blow-off member and the molds are connected to each other. After disposing the parison extruded by an extruder between the molds on at least one side of the mold, the plurality of molds are moved to sandwich the parison between the gas blowing member and the mold, and the gas is A blow molding method characterized by pressing and molding a parison against a cavity surface of a mold by blowing out compressed gas from an outlet of a blowing member. 2. The blow molding method according to claim 1, wherein the plurality of molds are asymmetrically formed. 3. The blow molding method according to claim 1, wherein the plurality of molds are formed symmetrically. 4. According to any one of claims 1 to 3, the parison is extruded in the form of two sheets, and is formed by being sandwiched between a pair of molds and a gas blowing member. Blow molding method as described.