초록 ▼

A multi-layer forming nozzle includes a valve member which can open and close a flow passage of molten resin which forms an intermediate layer of a multi-layer molded product by injection molding. The valve member is operated in response to resin pressure differentials at the front and back of the v

A multi-layer forming nozzle includes a valve member which can open and close a flow passage of molten resin which forms an intermediate layer of a multi-layer molded product by injection molding. The valve member is operated in response to resin pressure differentials at the front and back of the valve member to accurately switch from a multi-layer operation to a single layer operation and vice versa. A three-layer nozzle in accordance with the invention has a nozzle body provided interiorly with a first resin path, a second resin path and a third resin path in the form of a concentric circle bending to the same injection opening. The valve member is located either in a mouth portion of the third resin path in the central portion positioned internally of a mouth portion of the second resin path or a mouth portion of the second resin path in the intermediate portion positioned internally of the first resin path. The valve member is moved forward and backward in response to resin pressure differentials to open and close the valve member.

대표청구항 ▼

A multilayer nozzle, comprising: a first core member defining a generally cylindrical first resin path; a second core member encircling said first core member and cooperating with said first core member to define a generally cylindrical second resin path; a nozzle body encircling said second core me

A multilayer nozzle, comprising: a first core member defining a generally cylindrical first resin path; a second core member encircling said first core member and cooperating with said first core member to define a generally cylindrical second resin path; a nozzle body encircling said second core member and cooperating with said second core member to define a generally cylindrical third resin path; said first, second and third resin paths being concentric with one another and directing resin passing through them to a common injection opening; a valve member positioned in said first core member, said valve member being movable between a first position wherein it closes said second resin path and a second position wherein it opens said second resin path, said valve member having an internal opening which communicates with said first resin path and terminates in a first opening which leads to said common injection opening; means on said valve member being responsive to resins injected under respective pressures into said first and second paths respectively to move said valve member between said first and second positions in response to changes in said pressures of said first and second resins in said first and second paths; and said first and second core members, said nozzle body and said valve member cooperating to create a multilayer resin from said first and second resins and a third resin injected under pressure into said third resin path, said multilayer resin having sandwiched between said first and third resins when said valve member is in said second position and said first, second and third resins are injected through said first, second and third resin paths, respectively.