Mold clamping equilization system
AssigneeHusky Injection Molding Systems Ltd.
InventorsJohn DiSimone, Paul Brown, Robert D. Schad
Life of this patent
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Abstract
Injection molding machines for making plastic articles having a stack mold arrangement frequently suffer from the problem of unbalanced forces. Various novel techniques for counteracting and/or avoiding the production of these forces are disclosed. These techniques include the use of latches to lock an injection nozzle to a sprue bar, the use of shutters to lock the sprue bar to a stationary platen, the use of a force compensator in a moving stack mold half, and the use of an injection nozzle axially offset from the sprue bar.
Claims18
An improved injection molding apparatus which comprises:
- a stack mold arrangement including a stationary mold member fixed to a stationary platen, a movable central mold member, and a movable outer mold member, said stationary and movable mold members forming at least two molds;
- means for injecting plastic material into said at least two molds;
- said injecting means including an injection nozzle communicating with a source of plastic material and sprue bar means engaging said nozzle for distributing plastic into said at least two molds;
- means for creating a clamping force on both sides of said mold arrangement so as to keep said molds closed during molding;
- and
- means for maintaining said sprue bar means in contact with said injection nozzle and for containing separation forces which occur at the connection between said sprue bar means and said injection nozzle so as to maintain balanced clamping forces on both sides of said stack mold arrangement.
An injection molding apparatus which comprises:
- a stack mold arrangement including a stationary mold member fixed to a stationary platen, a movable central mold member, and a movable outer mold member, said stationary and movable mold members forming at least two molds;
- means for injecting plastic material into said at least two molds;
- said injecting means including an injection nozzle communicating with a source of plastic material and sprue means engaging said nozzle for distributing plastic into said at least two molds;
- means for creating a clamping force on both sides of said mold arrangement so as to keep said molds closed during molding;
- means for maintaining said sprue means in contact with said injection nozzle and for maintaining balanced clamping forces on both sides of said stack mold arrangement;
- said maintaining means being formed by a force compensator consisting of a fixed block mounted to a first mold half attached to one of said movable mold members, a mounting block attached to a second mold half attached to the other of said movable mold members, an adjustable post threaded into said mounting block and a compression spring between said adjustable post and said first block,
- whereby said spring is adjustable so as to develop a force which exactly balances the reaction to any separating force transmitted along said sprue means.
An injection molding apparatus which comprises:
- a stack mold arrangement including a stationary mold member fixed to a stationary platen, a movable central mold member, and a movable outer mold member, said stationary and movable mold members forming at least two molds;
- means for injecting plastic material into said at least two molds;
- said injecting means including an injection nozzle communicating with a source of plastic material and sprue bar means engaging said nozzle for distributing plastic into said at least two molds;
- means for creating a clamping force on both sides of said mold arrangement so as to keep said molds closed during molding;
- means for maintaining said sprue bar means in contact with said injection nozzle and for maintaining balanced clamping forces on both sides of said stack mold arrangement;
- and
- said maintaining means comprising means for preventing axial forces being transmitted from said injection nozzle to said sprue bar means.
Dependencies are inferred from the claim text.