Rp Topla Limited

Minoru Ojiro

Tomoyoshi Sakamoto

Hiroki Katagiri

Takashi Hirose

Yasuhiko Hata

Yaushiko Hata

Hiroyuki Minezaki

A hollow body molding device having molten resin injected into a main cavity, fluid is pressure-injected through a pressure port after the injection of molten resin, a floating core moves to the outlet side, the molten resin is extruded from the outlet simultaneously with the movement of the floating core, and a hollow molded body is molded, the hollow body molding device having a floating core storage portion connected to the main cavity and stores the floating core moved by the pressurized fluid, an auxiliary cavity stores molten resin discharged from the main cavity and the floating core storage portion, communication passages and which communicate the floating core storage portion and the auxiliary cavity with each other; and an opening and closing means that opens and closes the communication passages by sliding movement. In the hollow body molding device, each inlet cross-sectional area B of the communication passages is specified.

Hollow body molding device

The present invention includes injecting a molten resin into a main cavity, which has on its one end a pressure port provided with a floating core and on its other end a first outlet, and a branch cavity, which communicates with the main cavity and has on its end a second outlet allowed to open and close, injecting a pressurized fluid through the pressure port after the injection of the molten resin, and moving the floating core to the first outlet side, and, at the same time, extruding the molten resin from the first outlet to form a main pipe hollow, and opening the second outlet after the main pipe hollow reaches a portion at which the branch cavity communicates with the main cavity, and extruding the molten resin by the pressurized fluid from the second outlet to form the branch pipe hollow.

Method of manufacturing pipe with branch

A hollow body formed of a thermoplastic resin and having uniform inner diameter and thickness and an excellent inner surface smoothness, and, in particular, a pipe-shaped hollow body having a bent portion is manufactured by injection molding. A method of manufacturing a hollow body includes injecting a molten resininto a mold cavityof a mold, the mold cavityhaving on its one end a pressure portprovided with a floating coreand on its other end an outlet, pressure-injecting a pressurized fluid through the pressure portafter the injection of the molten resin, and moving the floating coretoward the outlet, and, at the same time, extruding the molten resinfrom the outlet In the method, the floating coreis constituted of a columnar portion and a top portion, which is continuously connected to one surface of the columnar portion and has a shape that a cross-sectional area perpendicular to a central axis of the columnar portion gradually decreases from one surface side of the columnar portion. When a diameter of the columnar portion is represented by A, the height of the columnar portion is 0.1 A to 1 A, and the height of the top portion is 0.3 A to 1.6 A.

Method of manufacturing hollow body

In a resin heat exchanger unit, a resin pipe having straight portions and curved portions and a plurality of resin fins are integrally molded and there can be realized high reliability, high heat exchange efficiency, and a simple manufacturing process. The resin heat exchanger unit includes a resin pipe (), which has straight portions () and curved portions () provided alternatively and continuously, and a plurality of resin fins () connected to the pipe (), the pipe () and the fins () being integrally injection-molded.

Growing community of inventors

Ota, Japan

Minoru Ojiro