JP4662321B2 - Blow molding die and blow molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blow molding die for blow-molding a hollow double-walled molded product and a method for blow-molding a hollow double-walled molded product using the die.
[0002]
[Prior art]
Conventionally, plastic hollow bodies such as plastic panels that make up interior walls, partitions, doors, or automobile parts such as headrests, armrests, rear parcel shelves, and cargo floor panels, are blow molded from thermoplastics. Is used. An inner rib for reinforcement is also formed between one resin wall and the other resin wall (see Japanese Patent Publication No. 4-31288).
[0003]
[Problems to be solved by the invention]
As described in Japanese Patent Publication No. 4-31288, in blow molding of a plastic hollow body having an inner rib for reinforcement, a mold is formed by placing a thermoplastic parison between a pair of split molds. Tighten and slide the slide core provided in the other mold so that a part of the other resin wall of the hollow double wall structure protrudes until it comes into contact with one resin wall and welds both resin walls. The resin wall is made integral between one resin wall and the other resin wall by retreating the core to the cavity surface and then welding the side surfaces of the resin walls protruding by the blow pressure by the pressure fluid introduced into the parison. The inner rib which is is formed.
[0004]
However, in the method of forming the inner rib by projecting a part of the parison by the slide core as described above, as shown in FIG. 8, the part of the parison b is projected by the slide core a as shown in FIG. When the slide core a is moved backward, the protruding portion c of the parison b has a mountain shape. Therefore, when the pressure fluid is introduced into the parison b, the protruding base end of the protruding portion c of the parison b is particularly preferred. From the fact that the blow ratio on the side d becomes large, as shown in FIG. 9, it is known from various experiments that the portion on the protruding proximal side d becomes thin and the strength of the inner rib e decreases. .
[0005]
Accordingly, an object of the present invention is to provide a blow molding die that allows a part of a parison to protrude by a slide core and blow molding so that a thin portion does not occur in an inner rib formed inside a molded product by blow pressure. And a method for blow molding a hollow double-walled molded product using the same.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention that achieves the above object is a blow mold for blow molding a molded article having a hollow double wall structure, and molds one half of the blow molded article. It consists of a pair of split molds, one mold having a cavity and the other mold having a cavity for molding the other half of the blow molded product. The other mold has a hollow double wall after clamping It is equipped with a slide core that can be moved forward and backward to weld a portion of the resin wall of the other half of the structure until it comes into contact with the resin wall of the other half and welds both resin walls. A blow molding die comprising vacuum means for adsorbing and holding a portion of a parison projecting a slide core in a cavity.
[0007]
The invention according to claim 2 is a method for blow-molding a hollow double-walled molded article using the blow-molding mold according to claim 1, wherein a parison is disposed between a pair of split molds. The mold is clamped, and then the proximity part of the slide core of the parison is adsorbed and held in the cavity by the vacuum means, then the slide core is advanced, and the part of the parison protrudes until it contacts the opposite part of the parison, and the protrusion The top end face was welded to the opposite part of the parison, and then the slide core was retracted to the cavity surface, and in that state, pressure fluid was introduced into the parison and blow molded, and the part projected by the parison slide core Is an inner rib in which both side surfaces are pressed against each other and welded together.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view showing a blow molding mode using a blow molding die according to the present invention, FIGS. 2 to 6 are main part cross-sectional views of FIG. 1, and FIG. FIG. 3 shows the process of placing the parison, FIG. 3 shows the process of moving the slide core, FIG. 4 shows the process of retracting the slide core, and FIG. 5 shows the process of forming the inner rib by introducing pressure fluid between the parisons. FIG. 6 shows another embodiment of FIG.
[0009]
As shown in FIGS. 1 to 5, the blow molding die according to the present invention comprises a pair of split molds, and one of the molds 1 is formed with a half of a panel (blow molded product, the same applies hereinafter). The other mold 2 has a cavity 4 for molding the other half of the panel. Sheet-like parisons 5 and 5 are arranged between one mold 1 and the other mold 2. On the other mold 2, a slide core 7 for projecting and forming an inner rib 6 on the other resin wall of the panel is provided so as to be able to protrude and retract with respect to the cavity 4.
[0010]
The other mold 2 provided with the slide core 7 is provided with vacuum means 8 and 8 for holding and holding the portion 5a for projecting the slide core 7 of the parison 5 in the cavity 4 with the slide core 7 sandwiched between them. I have. Although not shown, the cavity 4 of the other mold 2 is provided with vacuum means for sucking and holding the parison 5 in addition to the vacuum means 8 and 8. Also, vacuum means 9 for adsorbing and holding the parison 5 in the cavity 3 is also provided at an appropriate interval in one mold 1. 10 and 10 are resin extrusion dies.
[0011]
In order to blow-mold a panel with a pair of split molds configured as described above, as shown in FIG. 1, one mold 1 and the other mold 2 are opened, and a sheet-like parison 5 is interposed between them. 5 is placed and clamped as shown in FIG. When the mold is clamped in this way, the inside of the parisons 5 and 5 is hermetically held by pinch-off portions 11 and 11 formed around the cavities 3 and 4, so that the vacuum means 9 of one mold 1 and the other The vacuum means 8, 8 of the mold 2 and the vacuum means (not shown) are operated to hold the parisons 5, 5 in the cavities 3, 4 by suction.
[0012]
Next, as shown in FIG. 3, the slide core 7 is advanced from the cavity 4, and a part of the part that becomes the other resin wall of the parison 5 is protruded until it comes into contact with the part that becomes the one resin wall of the parison 5, The top end face 13 of the protruding portion 12 is welded to a portion that becomes one resin wall of the parison 5.
[0013]
Subsequently, as shown in FIG. 4, when the slide core 7 is retracted to the same position as the surface of the cavity 4 and pressure fluid is introduced into the parisons 5 and 5 in this state, the parisons 5 and 5 are moved into the cavities 3 and 4. As shown in FIG. 5, the panel 12 is molded by being pressed onto the surface of the panel, and the projecting portions 12 projected by the slide core 7 are pressed against each other to be integrally welded. Inner ribs 6 are formed inside.
[0014]
At the time of molding the inner rib 6 by such blow molding, the vicinity of both sides of the protruding portion 12 by the slide core 7 of the parison 5 is adsorbed and held in the cavity 4 by the vacuum means 8, 8. In the process from the state to the state of FIG. 5, as shown in FIG. 9, the entire parison formed around the protruding portion 12 has a substantially uniform thickness, and in particular, the protruding proximal end e portion may be thin. The inner rib 6 having excellent strength and rigidity is formed.
[0015]
Although the blow molding mode shown in FIG. 6 is another mode of FIG. 5, the thickness of the top end portion 14 of the inner rib 6 is formed so thin as not to impair strength and rigidity. In this way, by forming the top end portion 14 of the inner rib 6 as thin as possible, it is possible to prevent the welding trace of the top end surface 13 from appearing on the surface side of the resin wall or to make it inconspicuous.
[0016]
The constituent material of the panel blow-molded using the mold for blow molding according to the present invention is polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer, vinyl chloride resin, ABS resin (acrylonitrile-styrene-butadiene resin). , Polyamide resins, polystyrene resins, polyester resins, and thermoplastic resins such as engineering plastics such as polycarbonate and modified polyphenylene ether.
[0017]
In addition, in embodiment of this invention, although the blow molding aspect by the sheet-like parisons 5 and 5 was illustrated, of course, the blow molding aspect by a tubular parison is also possible.
[0018]
【The invention's effect】
According to the blow molding die of the present invention and the method for blow molding a hollow double-walled molded product using the same, the adjacent portion of the parison slide core is attracted and held in the cavity by the vacuum means. , The part of the parison protrudes until it touches the opposite part of the parison, and the inner rib that is formed inside the molded product by blowing pressure is introduced into the parison to form the parison. A thin-walled portion does not occur on the base end side, and an inner rib having excellent strength and rigidity can be formed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a blow molding mode using a blow molding die according to the present invention.
FIG. 2 is a cross-sectional view of a main part showing a process of arranging a sheet parison between divided molds.
FIG. 3 is a cross-sectional view of a main part showing a process in which a slide core is advanced from the embodiment of FIG. 2;
4 is a cross-sectional view of a main part showing a step of retracting the slide core from the embodiment of FIG. 3;
5 is a cross-sectional view of an essential part showing a step of forming an inner rib by introducing a pressure fluid between parisons from the embodiment of FIG. 4;
6 is a cross-sectional view of a main part showing another aspect of FIG. 5;
FIG. 7 is a cross-sectional view showing a process in which a part of a parison is protruded by a slide core in a conventional blow molding mode.
8 is a cross-sectional view showing a process in which the slide core is retracted from the embodiment of FIG.
9 is a cross-sectional view showing a process of forming an inner rib by introducing a pressure fluid between parisons from the embodiment of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 One metal mold 2 Other metal mold 3 Cavity 4 Cavity 5 Parison 6 Inner rib 7 Slide core 8 Vacuum means 9 Vacuum means 10 Resin extrusion die 11 Pinch-off part 12 Projection part 13 Top end face 14 Top end part

Claims (2)

A blow molding mold for blow molding a hollow double-walled molded article, wherein one mold having a cavity for molding one half of the blow molded article and the other half of the blow molded article It consists of a pair of split molds of the other mold having a cavity for molding the body, and the other mold has a part of the resin wall of the other half of the hollow double-wall structure after the mold clamping. A vacuum core that has a slide core that can be moved forwards and backwards to protrude until it comes into contact with the resin wall of the body and welds both resin walls. A mold for blow molding, comprising: A method for blow molding a hollow double-walled molded article using the blow molding die according to claim 1, wherein a parison is placed between a pair of split molds and clamped, and then the parison After adsorbing and holding the proximity part of the slide core to the cavity by vacuum means, the slide core is advanced, and the part of the parison protrudes until it comes into contact with the opposite part of the parison, and the protruding top end surface becomes the opposite part of the parison. Next, the slide core is retracted to the cavity surface, pressure fluid is introduced into the parison and blow-molded in that state, and the parts projected by the slide core of the parison are pressed against each other on both sides. A blow molding method characterized in that the inner rib is integrally welded.

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