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Device for ending the feed movement of a grinding wheel

  • US 3,978,624 A
  • Filed: 05/07/1975
  • Issued: 09/07/1976
  • Est. Priority Date: 05/11/1974
  • Status: Expired due to Term
First Claim
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1. In a device for terminating the relative feeding movement between a rotating grinding wheel carried by a rotatable tool spindle and a workpiece, the improvement comprising wherein said rotating grinding wheel has a plurality of electrical conductors insulated with respect to the material of said grinding wheel, the free ends of said conductors terminating at the active surface of said grinding wheel, rotatable voltage transformer means rotating with said tool spindle and generating an impulse characteristic between said free ends of said conductors and said workpiece surface, said voltage transformer means having a primary circuit and a high voltage secondary circuit and a low voltage secondary circuit, one side of both of said high voltage and low voltage secondary circuits being selectively electrically connected to said conductors and the other side thereof to said workpiece, feed drive means for effecting a relative movement between said grinding wheel and said workpiece at least toward each other, said feed drive means having a pair of differing speed characteristics so that said relative movement at one speed is faster than at the other speed, said high voltage circuit being electrically connected to said conductors when said feed drive means effects said fast relative movement between said grinding wheel and said workpiece, threshold switch means responsive to a spark discharge across a predetermined liquid free gap between said grinding wheel and said workpiece when said fast relative movement is occurring between said grinding wheel and said workpiece for (1) simultaneously switching said connection between said high voltage secondary circuit and said conductors to a connection between said low voltage second circuit and said conductors and (2) switching said feed drive means to the slower one of said speeds of relative movement.

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