Speed-compensated press load monitoring system

Claim 1

A press load monitoring system for determining the speed-compensated load level of a variable speed press, comprising: strain sensor means for continually determining the strain on the frame of the press as the press is operating; speed sensor means for continually determining the speed of said press as the press is operating; and means responsive to said strain sensor means and said speed sensor means for continually (a) calculating a non-speed-compensated load level of the press from the output of said strain sensor means, (b) modifying the calculated non-speed-compensated load level of the press depending on the output of said speed sensor means so as to derive the speed-compensated load level of the press wherein the speed-variable effects of "ringing" in the press frame have been substantially eliminated, (c) comparing the speed-compensated load level with predetermined set points and (d) automatically shutting down the press if the speed-compensated load level is outside the limits of said predetermined set points.

Claim 3

A method of monitoring the load on a variable speed press so as to compensate for speed-related strains in the frame of the press, comprising the steps of: (1) continually determining the strain on the frame of the press as the press is operating; (2) continually determining the speed of said press as the press is operating; and (3) continually (a) modifying the strain determined for the frame of the press in accordance with the speed of the press so as to remove from said strain the strain component produced by mechanical resonances in the frame of said press and thereby derive the speed-compensated strain on the press, (b) comparing a load level determined by the speed-compensated strain with a predetermined load level, and (c) automatically shutting down the press if the load level represented by the speed-compensated strain is outside the limits of said predetermined load level.

Claim 4

A method of monitoring the load on a variable speed press so as to compensate for speed-related strains in the frame of the press, comprising the steps of: (1) continually determining the strain on the frame of the press as the press is operating; (2) continually determining the speed of said press as the press is operating; and (3) continually (a) modifying the strain determined for the frame of the press in accordance with the speed of the press so as to remove from said strain the strain component produced by mechanical resonances in the frame of said press and thereby derive the speed-compensated strain on the press, (b) comparing a load level determined by the speed-compensated strain with a predetermined load level, and (c) automatically shutting down the press if the load level represented by the speed-compensated strain is outside the limits of said predetermined load level.