Device in grinding machines

Claim 2

In a grinding machine having a first member comprising a rotatable chuck for carrying a workpiece, a second member comprising a rotatable spindle having thereon a grinding disc, a movable support for one of said members, and a feeding mechanism for moving said support radially and axially of the spindle axis for grinding engagement of the disc with the workpiece, the combination of a first measuring device operative in response to deflection of said spindle caused by the radial forces produced Between the grinding disc and the workpiece, to produce a first signal, a second measuring device disposed to develop a second signal in correspondence to the radial feed position of said support, a control device for said feeding mechanism, operative to stop said feeding mechanism upon completion of a grinding operation, and connected to said measuring devices to compare the signals emitted therefrom, and means for adjusting said control device, so as to add to a predetermined radial feed for said support an additional radial feed, which is substantially as great as the magnitude of deformation of the spindle, before the control device stops the feed movement.

Claim 3

A machine as claimed in claim 1 having a differential pressure box having two pressure chambers therein, and a movable partition separating said chambers, a stationary nozzle positioned to direct pneumatic pressure fluid at said spindle, a pressure fluid conduit connecting said nozzle to said first measuring device to transfer pressure variations occurring in the interspace between said nozzle and said spindle, in response to deflection of said spindle, to one chamber of said differential pressure box, a control member movable in response to radial displacement of said support, a second nozzle positioned to direct pneumatic pressure fluid at said control member, a pressure fluid conduit connecting said second nozzle to the other chamber of said differential pressure box to transfer pressure variations, occurring in the interface between said control member and said second nozzle, to said other chamber, adjustable throttling means in said conduits for calibration of the pressure differential between said chambers, and means connecting said partition to said control device.

Claim 4

A machine as claimed in claim 1, including means operative, upon completed feed movement of said feed mechanism, to cause said support to be retracted for a distance slightly less than said additional radial feed for completion of a fine grinding operation, with pressure on the grinding disc being maintained by the gradually reduced deformation of said spindle.

Claim 5

A machine as claimed in claim 1, wherein said measuring devices comprise a pair of stationary nozzles disposed in spaced, confronting relation to said spindle and a control member, respectively, a differential pressure gauge has opposite sides thereof responsive to pressure variations occurring in the interspaces between one nozzle and said spindle and between the other nozzle and the control member, respectively, in response to the deflection of said spindle and to the radial displacement of said support, respectively, and throttling means is provided for calibrating the pressure differential produced in said gauge.

Claim 6

A machine as claimed in claim 4, wherein said differential pressure gauge is equipped with a movable indicator arm adapted to indicate the prevailing difference in pressure in said gauge, and selectively actuatable coupling members for coupling said indicator arm to said control device.

Claim 7

In a grinding machine having a rotatable chuck for carrying a workpiece, a rotatable spindle having thereon a grinding disc, and a feeding mechanism operable to effect relative movement between said spindle and said chuck radially of said spindle to engage said disc with the workpiece to grind a surface thereon to a predetermined radial depth, the combination comprising a first measuring device operative, when said disc is in grinding engagement with said workpiece, to develop a first signal proportionate to the deflection of said spindle resulting from the forces produced between the grinding disc and the workpiece, a second measuring device responsive to relative radial movement between said spindle and chuck and operative to develop a second signal the magnitude of which is proportionate to said radial movement, control means operative to stop said feeding mechanism when said sEcond signal has reached a predetermined value, and means for adjusting said predetermined value of said second signal prior to a grinding operation, so that said control means will become operative only when the feeding mechanism has effected a radial feed movement determined by the amount of stock which is to be removed from the workpiece, plus an amount approximately proportional to the deflection of said spindle as determined by said first signal.

Claim 8

In a grinding machine having a rotatable chuck for carrying a workpiece, a rotatable spindle having thereon a grinding disc, and a feeding mechanism operable to effect relative movement between said spindle and said chuck radially of said spindle to engage said disc with the workpiece to grind a surface thereon to a predetermined radial depth, the combination comprising a first measuring device operative, when said disc is in grinding engagement with said workpiece, to develop a first signal proportionate to the deflection of said spindle resulting from the forces produced between the grinding disc and the workpiece, a second measuring device responsive to relative radial movement between said spindle and chuck and operative to develop a second signal the magnitude of which is proportionate to said radial movement, control means operative to stop said feeding mechanism when said sEcond signal has reached a predetermined value, and means for adjusting said predetermined value of said second signal prior to a grinding operation, so that said control means will become operative only when the feeding mechanism has effected a radial feed movement determined by the amount of stock which is to be removed from the workpiece, plus an amount approximately proportional to the deflection of said spindle as determined by said first signal.