Plate 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.

1 . A method of manufacturing a heater for a hot runner manifold, the method comprising:
 providing an extruded heater plate body having at least two longitudinally-extending parallel channels therein;   machining a flat contact face of the heater plate body; and   inserting a heating element into each of the channels.   
     
     
         2 . The method of  claim 1 , wherein terminal end portions of each of the heating elements extends out of the respective channel and further including the step of:
 providing at least one end cap for commonly fixing the terminal end portions of the heating elements relative to the heater plate body.   
     
     
         3 . The method of  claim 2 , wherein the terminal end portions of the heating elements are bent and the bends are covered by the end cap. 
     
     
         4 . The method of  claim 1 , further comprising the step of:
 extruding a bar-like blank having the at least two longitudinally-extending parallel channels formed therein; and   cutting the bar-like blank across a width thereof to provide the extruded heater plate body.   
     
     
         5 . The method of  claim 4 , wherein the channels have a key-shaped cross-section. 
     
     
         6 . The method of  claim 4 , wherein the channels are formed within one of a top and bottom surface of the heater plate body. 
     
     
         7 . The method of  claim 4 , wherein the channels are formed within opposing side surfaces of the heater plate body. 
     
     
         8 . The method of  claim 1 , further comprising:
 machining ends of the heater plate body to accommodate installation of the terminal end portions of the heating elements.   
     
     
         9 . The method of  claim 1 , further comprising the steps of:
 machining the channels to have a groove portion and an undercut portion, wherein the undercut portion is wider than the groove portion and sized to be substantially equal to an outer diameter of the heating element to be received therein; and   placing the respective heating element into contact with the undercut portion of the channel.   
     
     
         10 . The method of  claim 9 , wherein inserting the heating element into the channel includes pressing and deforming the heating element into the groove in order to maximize contact between the heating element and the undercut portion 
     
     
         11 . A method of manufacturing a heater for a hot runner manifold, the method comprising:
 extruding a heater plate from a raw form to a final form using a die, the heater plate including a channel;   machining the channel to have a groove portion and an undercut portion, wherein the undercut portion is wider than the groove portion;   cutting the heater plate to a length based on the configuration of the manifold; and   placing a heating element into contact with the undercut portion of the heater plate channel, wherein the heater plate is coupled to the manifold for providing heat thereto.   
     
     
         12 . The method of  claim 11 , further comprising;
 machining a contact surface of the heater plate to maximize contact between the contact surface and a surface of the manifold.   
     
     
         13 . The method of  claim 12 , further comprising:
 machining ends of the heater plate to accommodate installation of heating element terminations.   
     
     
         14 . The method of  claim 13 , further comprising:
 machining relief holes in the heater plate, the relief holes being provided to accommodate connections of other components to the surface of the manifold.   
     
     
         15 . The method of  claim 11 , wherein placing the heating element into the channel includes pressing and deforming the heating element into the groove in order to maximize contact between the heating element and the undercut portion.