GB1274503A - Improvements in and relating to machine tools - Google Patents

Abstract

1,274,503. Indicating tool wear. BOEHRINGER G.m.b.H. GEB. 30 Sept., 1969 [17 Oct., 1968], no. 47078/69. Heading B3B. [Also in Division G1] A machine tool, equipped with a plurality of tools which can be moved into operational contact with a workpiece by a tool-changing device, is provided with means for measuring the wear of individual tools by measuring separately for each tool the sum of the periods of operational contact between tool and workpiece and with means for emitting a signal and/or automatically stopping operation of a tool in respect of which the sum of the measured periods has reached a predetermined limit. The tool-changing device may comprise a rotary turret and each tool is associated with an electric counter 10, 110, ... When a particular tool is selected an associated switch 12, 112, ... connects the counter 10, 110, ... to a common line 14, which is connected by a switch 16 to an impulse generator 18 only when the selected tool is operational, e.g. during the forward feed of the tool. Limiting signals representing the maximum time of use without excess wear may be fed to the counter 10, 110 at inputs 20, 120 and when the limits are reached signals from outputs 22, 122 may cause acoustic or optical warnings or initiate control operations to stop the machine or to substitute the tool and the counters may be reset to zero by signals fed to inputs 24, 124. Switch 16 may be replaced by a switch 26 actuated by a relay whose circuit is closed only when the tool contacts a workpiece or alternatively the switch 26 may be actuated by a control member which measures the power for driving the machine or the cutting force of the tool. The counters or the impulse generator may be modified to introduce factors or coefficients to compensate the time measurements for varying operational conditions such as differences of feeding speed or of hardness of the tool. Where a number of tools are used simultaneously, each may be provided with its own impulse generator. The impulse generators may be replaced by electric clocks, whose speeds can be modified in accordance with any compensating factors to be introduced. The degree of wear may be calculated by a computer.