Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to heat or cool
Reexamination Certificate
1999-04-05
2001-05-22
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to heat or cool
C425S562000, C425S564000
Reexamination Certificate
active
06234783
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an injection molding nozzle to be used for injection molding of resin or molten metal.
2. Related Background Art
Known nozzles, nozzle main bodies and valve pins to be used for injection molding are typically made of metal such as tool steel and hence cannot be used with glass fiber, carbon fiber, resin containing a filler material and molten metal.
Known injection molding nozzles made of metal are accompanied by the following problems.
(1) The metal has a low hardness and is chemically unstable so that the gas or the fluid forced to penetrate into the gap between the injection molding nozzle and the valve pin by the temperature and the pressure of the material to be injected can seize the valve pin.
(2) The pliability of the metal can give rise to a collapse on the part of the valve pin and a certain degree of deviation in the coaxiality between the valve pin and the gate.
(3) The metal shows a large coefficient of thermal expansion to make it difficult to maintain a high degree of machining accuracy during the manufacturing process.
(4) The large coefficient of thermal expansion and the easy cuttability of the metal make it difficult to enhance the surface smoothness and the surface planeness.
SUMMARY OF THE INVENTION
In view of the above identified problems of known metal-made injection molding nozzles, it is therefore an object of the present invention to provide an improved injection molding nozzle that shows a high hardness and is chemically stable so that the inner surface thereof is not corroded nor the gas or the fluid forced to penetrate into the gap between the injection molding nozzle and the valve pin seize the valve pin regardless of the temperature and the pressure of the material to be injected.
Another object of the present invention is to provide an injection molding nozzle, wherein the valve pin is not pliable and does not give rise to a collapse on the part of the valve pin.
Still another object of the present invention is to provide an injection molding nozzle, whose material shows a small coefficient of thermal expansion to make it easy to maintain a high degree of machining accuracy during the manufacturing process.
A further object of the present invention is to provide an injection molding nozzle, wherein the large coefficient of thermal expansion and the high machinability of the material of the nozzle enhance the surface smoothness and the surface planeness.
According to the invention, the above objects are achieved by providing an injection molding nozzle to be used for resin and molten metal, said nozzle is made of a ceramic material and at least part of the outer periphery is covered with metal.
Preferably, the valve pin to be combined with said nozzle is at least partly made of a ceramic material. Preferably, said nozzle is heated by electromagnetic induction. Preferably, the valve pin sliding hole and the injection path of said nozzle communicate with each other.
REFERENCES:
patent: 4492556 (1985-01-01), Crandell
patent: 5096646 (1992-03-01), Shigemoto et al.
patent: 61-272119 (1986-12-01), None
Julius Grant, Hackh's Chemical Dictionary, p. 611, 1969.*
61-272119, Moulding Device for plasticised materials, Dec. 2, 1986, Abstract.
Iida Hiroyuki
Shibata Itsuo
Toki Hitoshi
Wada Shigeo
Heitbrink Tim
Jacobson Price Holman & Stern PLLC
Ju-Oh Inc.
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