Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Shaping against interior of a forming surface by rotation of...
Patent
1996-12-12
1999-09-07
Dye, Rena L.
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Shaping against interior of a forming surface by rotation of...
264512, 264319, 425577, 425579, 425585, 428 357, 428 364, 428 369, 428 3691, B29C 4322, B29D 2300
Patent
active
059483431
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to hollow shaped molded articles such as pipes, their molding process and their molding device.
BACKGROUND OF THE INVENTION
As a conventional process and device for monolithic molding of a synthetic resin pipe, it is known to use a mold which comprises a metal floating core having a diameter corresponding to an inner diameter of the pipe and an injection port for injecting a compressed fluid, both provided at one end of a main cavity, and a sub-cavity provided at the other end of the main cavity through a communication port; the main cavity is filled with a molten resin, the compressed fluid is introduced under pressure through the injection port, the floating core is moved toward the communication port to form a hollow part in the resin filled within the cavity, and an excess part of the resin is discharged into the sub-cavity through the communication port, thereby monolithically molding a hollow pipe (Japanese Patent Laid-Open Publication No. Hei 4-208425).
The above-described conventional process and device are primarily for injection molding and are particularly characterized by forming the hollow part by effecting the injection of the compressed fluid and the movement of the floating core, and have an advantage of producing a pipe which has a smooth surface condition and high dimensional precision. And, they can also mold a reinforced resin containing reinforced fiber such as glass fiber, carbon fiber or metal fiber. Besides, they have an advantage of producing a curved pipe in addition to a straight pipe when bending is within a range that the floating core can be moved.
And, in the above conventional process and device, the communication port has a diameter smaller than the floating core, and the floating core stays within the main cavity. Thus, since the metallic floating core is designed to stay within the main cavity, it is advantageous that the resin extruded into the sub-cavity can be pulverized after completing the molding process and can immediately be used again as the molding material.
However, the above conventional process and device had the following disadvantages.
(1) Since the floating core remains within the main cavity, a molded article has at least one end of its formed hollow part closed by this floating core. Although this hollow shaped molding process and its molding device are particularly suitable to produce a pipe, the produced pipe has its one end closed by the floating core.
(2) The above closed part is cut off after molding. But, it is a troublesome work, and the metallic floating core remains in the cut-off piece. Therefore, the floating core must be removed before reusing the cut-off piece as the molding material.
(3) The resin discharged into the sub-cavity is removed as a block- or rod-shaped mass and cannot be pulverized easily, detrimental to reuse. Particularly, when a hollow shaped molded article is made of a reinforced resin containing reinforced fiber, the reinforced resin in the sub-cavity has a high strength, so that a large crusher is required to break it, and its blades are easily worn. Thus, the reinforced resin cannot be reused readily. Besides, reuse is also hindered because when the reinforced resin is crushed, its reinforced fiber is cut into pieces, lowering the mechanical properties of the reinforced resin.
(4) When the hollow shaped molded article is made of a reinforced resin, the inner surface of the hollow shaped molded article with which the moving floating core is in direct contact loses its smoothness easily because the reinforced resin contains a filler reinforcing material or reinforcing fiber. Therefore, when the hollow shaped molded article is used as a pipe, for example, there is a disadvantage that a significant property of the pipe, i.e., a flow resistance, is increased, resulting in extremely limiting its application range.
(5) To move the floating core, the compressed fluid at a substantially high pressure is injected in a stroke. Therefore, the floating core is instantaneously moved towa
REFERENCES:
patent: 5324558 (1994-06-01), Muto et al.
patent: 5330807 (1994-07-01), Williams
patent: 5397636 (1995-03-01), Miyao et al.
patent: 5474823 (1995-12-01), Kamiyama et al.
patent: 5629062 (1997-05-01), Ejiri et al.
patent: 5763035 (1998-06-01), Andre De La Porte et al.
International Search Report for International Application No. PCT/JP96/00417 dated May 28, 1996.
Hidetoshi Akutu
Hiroki Katagiri
Isao Iida
Masaki Ono
Minoru Oziro
Dye Rena L.
RP Topla Limited
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