Heater for a manifold of an injection molding apparatus

Abstract

An injection molding apparatus includes a manifold having a manifold channel for receiving a melt stream of moldable material and delivering the melt stream to a mold cavity through a nozzle channel of a nozzle and a mold gate. A heater is coupled to the manifold. The heater includes a heater plate that is formed by an extrusion process and at least one channel for receiving a heating element.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to an injection molding apparatus and, in particular to a heater for a manifold. BACKGROUND OF THE INVENTION [0002] As is well known in the art, a typical multi-cavity hot runner injection molding system includes a heated manifold for conveying a pressurized melt stream from an inlet to a plurality of outlets. A heated nozzle communicates with each outlet to deliver the melt to a respective mold cavity through a mold gate. Manifolds have various configurations depending on the number and arrangement of the mold cavities. [0003] Different heating arrangements are known for heating manifolds. A common arrangement is an electrical heating element that is received in a groove in a manifold outer surface, as described in U.S. Pat. No. 4,688,622 to Gellert, which issued Aug. 25, 1987. Other arrangements include cartridge heaters that are cast into the manifold as described in U.S. Pat. No. 4,439,915 to Gellert, which is...

AI Technical Summary

Benefits of technology

[0056] The many features and advantages of the invention are apparent from the detailed specification and, thus, it is intended by the appended claims to cover all such features and advantages of the invention that fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Problems solved by technology

Manufacture and assembly of each of these heating arrangements requires machining of the manifold, the heater or both, which can be both costly and time consuming.

However, heater plates are typically made by investment casting methods, which does not accommodate the manufacture of larger plates due to warpage and bending that occurs as the plates get longer.

Further, heater elements of current heater plates are cast within the heater plate and cannot be replaced once they fail, so that the entire heater plate must be replaced upon failure of the heater elements therein.

Alternatively, heater elements that are pressed-in machined grooves on the surface of a manifold may be removed for replacement, although machining such grooves is time consuming and expensive.

In addition, redundancy is provided for by machining a corresponding groove in an opposing surface of the manifold and pressing a secondary heater element into the second groove, adding to the time and cost associated with this production method.

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