Speed control device

Claim 2

In a grinding machine having a grinding wheel, an advancing mechanism for said grinding wheel, said advancing mechanism having at least two speeds of operation, a hydrostatic spindle for supporting a workpiece, and support fluid in said hydrostatic spindle, the improvement comprising detector means responsive to pressure variations in said support fluid, and speed control means responsive to the output of said detector means to change the speed of operation of said advancing mechanism.

Claim 3

The grinding machine of claim 1 wherein said advancing mechanism has an approach speed and a working speed, said detector means produces said output when the pressure in said support fluid changes as said grinding wheel contacts said workpiece at said approach speed, and said speed control means changes the speed of said advancing mechanism from said approach speed to said working speed.

Claim 4

The grinding machine of claim 1 wherein said detector means includes a differential manometer, two chambers in said hydrostatic spindle for containing support fluid, and connecting means interconnecting said two chambers and respective input sides of said differential manometer.

Claim 5

The grinding machine of claim 3 wherein said two chambers in said hydrostatic spindle are diametrically opposed across said spindle and in a line joining the axes of said grinding wheel and said hydrostatic spindle.

Claim 6

The grinding machine of claim 3 wherein said differential manometer has an electrical output.

Claim 7

The grinding machine of claim 3 wherein said differential manometer has a pneumatic output.

Claim 8

The grinding machine of claim 3 wherein said differential manometer has an hydraulic output.

Claim 9

The grinding machine of claim 1 wherein said speed control means responsive to the output of said detector means includes trigger means, said trigger means initiating said change in speed of said advancing mechanism in response to a threshold output from said detector means.

Claim 10

The grinding machine of claim 8 wherein said trigger means is adjustable to vary the threshold output from said detector means required to fire said trigger means.

Claim 11

In a grinding machine having a grinding wheel, an advancing mechanism for said grinding wheel, said advancing mechanism having at least two speeds of operation, a hydrostatic spindle for supporting a workpiece, and support fluid for said hydrostatic spindle, the improvement comprising: detector means responsive to pressure variations in said support fluid, said detector means including a differential manometer having an electrical output, first amplifier means for amplifying the output of said differential manometer, electrical trigger means responsive to a threshold output of said first amplifier means, second amplifier means for amplifying the output of said trigger means, and means responsive to the output of said second amplifier means for changing the speed of said advancing mechanism whereby a change in pressure in said support fluid when said grinding wheel contacts said workpiece causes a change in speed of said advancing mechanism.

Claim 12

In a grinding machine having a grinding wheel, an advancing mechanism for said grinding wheel, said advancing mechanism having at least two speeds of operation, a hydrostatic spindle for supporting a workpiece, and support fluid for said hydrostatic spindle, the improvement comprising: detector means responsive to pressure variations in said support fluid, said detector means including a differential manometer having an electrical output, first amplifier means for amplifying the output of said differential manometer, electrical trigger means responsive to a threshold output of said first amplifier means, second amplifier means for amplifying the output of said trigger means, and means responsive to the output of said second amplifier means for changing the speed of said advancing mechanism whereby a change in pressure in said support fluid when said grinding wheel contacts said workpiece causes a change in speed of said advancing mechanism.