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Clamping unit for injection molding machine

  • US 5,052,910 A
  • Filed: 12/13/1989
  • Issued: 10/01/1991
  • Est. Priority Date: 12/31/1988
  • Status: Expired due to Term
First Claim
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1. In a clamping unit for an injection molding machine, said clamping unit comprisesa stationary mold carrier,a movable mold carrier reciprocable relative to said stationary mold carrier to and from a clamping position, andhydraulic actuating means for moving said movable mold carrier to and from said clamping position and for locking said movable mold carrier in said clamping position, said actuating means defining an axis of symmetry and comprisingat least one hydraulic locking cylinder,a locking piston connected to said movable mold carrier and contained in and operable by said at least one hydraulic locking cylinder to lock said movable mold carrier in said clamping position, said locking piston in said at least one hydraulic locking cylinder defining a high-pressure chamber and a low-pressure chamber, said locking piston having at least one valve-controlled overflow passage connecting said high-pressure and low-pressure chambers,at least one hydraulic drive cylinder, operable to move said movable mold carrier to and from said clamping position;

  • said at least one hydraulic drive cylinder being centered on said axis of symmetry and being connected to said movable mold carrier,at least one buffer cylinder, anda buffer piston contained in said at least one buffer cylinder and defining in said at least one buffer cylinder a buffer chamber, said buffer chamber communicating with said low-pressure chamber of said at least one locking cylinder,the improvement whereinsaid at least one buffer cylinder coaxially surrounds said at least one hydraulic drive cylinder,said buffer piston being mounted on said at least one hydraulic drive cylinder,said at least one hydraulic locking cylinder and said locking piston being symmetrically arranged with respect to said axis of symmetry, anda separate shut-off valve being operatively connected with said at least one hydraulic locking cylinder for shutting off said at least one valve-controlled overflow passage in said locking piston.

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