Method and apparatus for controlling a vent gap with active material elements

Abstract

Method and apparatus for controlling a vent gap in a mold for an injection molding machine are provided, and include an active material insert configured to be regulate the degree of opening of the vent gap. The active material insert is configured to be actuated in response to signals from a controller, so as to selectively block the opening of the vent gap during the molding process. Wiring structure is coupled to the active material insert, and is configured to carry the actuation signals. Melt flow sensors may also be provided to aid in regulating the vent gap, and may be connected to the controller in order to provide real-time closed loop control over the operation of the vent gap. Preferably, the methods and apparatus are used as part of a system for controlling the flow of melt within a mold cavity.

1 . A method of regulating a vent gap in an injection mold, comprising the steps of: 
 actuating said piezoceramic actuator to adjust a width of said vent gap, to restrict the flow of melt through said vent gap.    
     
     
         2 . The method of  claim 1 , wherein the width of said vent gap is adjusted based upon one or more factors selected from the group consisting of melt temperature, melt composition, and melt pressure.  
     
     
         3 . A method of controlling a fluid flow path through a mold cavity, comprising the steps of: 
 injecting melt into said mold cavity;    sensing melt fronts as said melt flows throughout the mold cavity and transmitting signals corresponding to said melt fronts from said sensors to said controller; and    transmitting signals from said controller to actuate said active material actuators, wherein said active material actuators are actuated to control said vents and control melt flow through said mold cavity.