Adjustable valve pin assembly

Abstract

The valve pin adjustment system is provided for use in valve gated injection molding applications which enables adjustments to the positioning of the valve pin without necessitating removal of the clamping plates and valve assembly components, including valve pins. A piston associated with the valve pin includes a cylindrical body having first and second co-axially aligned internally threaded bores of respective first and second diameters. Preferably, the threads formed in the first and second bores are of the opposite hand. First and second externally-threaded cylindrical valve pin positioning members are respectively received in the first and second bores. Each of the positioning members includes a head portion and a tip portion. The tip of the second positioning member is in contact with the head of the first positioning member to lock the first positioning member in place, and the tip of the first positioning member is in contact with a head portion on the valve pin to locate the valve pin.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of the filing date of provisional application Ser. No. 60 / 480,777, filed on Jun. 23, 2003.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to valve gate systems wherein a reciprocating valve pin opens and closes a melt passageway in injection molding applications. More particularly, this invention relates to valve pin assembly and a method for adjusting valve pin position to ensure proper opening and closing of the melt passageway during injection molding operations.[0003]Valve gated injection molding systems are known in which pistons are actuated pneumatically or hydraulically to reciprocate the valve member. In general, such systems require that the components, in particular the valve pin and its associated piston, be made to very close tolerances to allow for thermal expansion so that, when at operating temperatures, the front end of the valve pin seats precisely in the gate t...

AI Technical Summary

Benefits of technology

"This patent describes a new system for adjusting the position of valve pins in valve gate injection molding applications. The system allows for easy adjustments without the need to remove manifold plates and valve assembly components. The system includes a piston that captures the head of the valve pin and two externally threaded positioning members that are locked in place to secure the valve pin. The system is fully functional and can be easily installed. The piston also acts as a pressure pad and insulator between the top clamp plate and the manifold of the hot runner system. The system also includes features to prevent rotation of the piston and to accommodate the lateral expansion of the manifold. Additionally, the shaft of the valve pin has grooves to collect any melt that may migrate through the manifold. Overall, the system provides a more efficient and flexible way to adjust the position of valve pins in injection molding applications."

Problems solved by technology

If the valve pin does not extend far enough into the gate, it will not seat tightly when in the closed position, leading to a poor gate vestige.

If the valve pin extends too far toward the gate, the tip of the pin will repeatedly impact the gate on closing, thus causing undue wear of both the valve pin and the gate and, potentially, fracture of the mold around the gate.

Typically, final adjustment of the positioning of the valve pin is a complicated and time-consuming procedure.

It is, obviously, an exacting and time consuming process.

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