US 4,074,467 AGranted

Grinding machine control

AssigneeCincinnati Milacron-Heald Corporation

InventorEdward George Robillard

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Abstract

A multimodal cycle for a grinding machine is modified as the function of the grinding force and the mode of operation. The grinding force is monitored by measuring the electrical load value upon the grinding wheel motor during operating conditions and biasing this value by a stored value representative of the nongrinding idle load. The idle load bias is updated with each grinding cycle and the grinding force signal is used to control a variety of machine operations. If the grinding force signal exceeds a predetermined threshold during an early portion of the grinding cycle, the wheelhead advancement is terminated; while the same situation in a later portion of the cycle permits continued wheelhead advancement but at a reduced rate. The grinding force signal is also used to count parts and detect part absence. It is further used to regulate rough and finished spark-outs as well as a peak load limit for the grinding cycle. The threshold level for these latter three functions is further modulated in accordance to the size of the grinding wheel.

A grinding machine of the type having a base, a wheelhead carrying an abrasive wheel, a wheel motor for rotating the abrasive wheel, a headstock supported on the base and means for effecting relative movement between the wheelhead and its stock, said effecting means being responsive to a control generating a number of signals to define a grinding cycle having a number of modes including:

(1) a rapid advance mode for positioning the wheelhead and headstock preparatory to grinding and during which no grinding is anticipated, said rapid mode being initiated by a first signal from the control,
(2) a gap eliminator mode for positioning the wheelhead and headstock to initiate the grinding process, said control generating a second signal to terminate the rapid advance mode and begin the gap eliminator mode, and
(3) a grinding mode for performing the grinding operation,
wherein the improvement comprises:
(a) means responsive to the wheel motor for providing a grinding force signal representing the forces of the grinding process, said providing means operating with each grinding cycle to continuously compensate the grinding force signal as a function of the changes in the nongrinding forces on the wheel motor;
(b) means responsive to the first signal and the grinding force signal and connected to the effecting means for producing an interference signal to modify the grinding cycle in response to the grinding force signal exceeding a predetermined magnitude;
(c) means responsive to the second signal and the grinding force signal and connected to the effecting means for producing a gap elimination signal in response to the grinding force signal exceeding the predetermined magnitude, said gap elimination signal operating to terminate the gap eliminator mode and begin the grinding mode;
and
(d) means responsive to the grinding force signal for producing an output signal in response to the grinding force signal exceeding a second predetermined magnitude;
and
(e) means responsive to the output signal for controlling the grinding cycle.

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Abstract

Claims24