GB1504310A - Apparatus for measuring the condition of a tool - Google Patents

Abstract

1504310 Testing condition of tools electrically TOKYO SHIBAURA ELECTRIC CO Ltd 31 Dec 1975 [21 Nov 1975] 53283/75 Heading G1N [ Also in Division B3] The condition of a tool is detected by measuring the working resistance of a workpiece to the tool. After a predetermined number of drilling operations of a drill a sample made of the same material as the workpiece is drilled four times and the working resistance measured for each drilling operation by measuring the torque, thrust, cutting temperature or the number of revs to drill a hole in the sample. If two or more of the measurements indicate that the life of the drill is finished a fresh drill is fitted. Torque and thrust transducers Figs. 2, 3. A cylindrical casing 21 houses a diaphragm 23 having a thickened central 23b and peripheral portions 23a the latter being secured to the casing 21. A Piezo-electric member P1 is sandwiched between the portion 23b and spacer 24. Mounted above central projection 23d on steel ball 31 is a sample holder 26 which is supported by criss-cross spring 27 in the casing. Holder 26 also carries two depending portions 26 which with projections 23a of diaphragm 23 sandwich a pair of Piezoelectric elements P2. With the sample 6 held in position on the holder 26 the drill is brought into contact with the sample and a hole drilled at constant speed and rate of feed. An electrical signal indicative of thrust C is obtained from member P1 as holder 26 moves downwards and forces diaphragm 23 against the member P1. An electrical signal indicative of the torque B is obtained from members P2 as the portions 26a are rotated by the torque B into contact with the members P2. Circuitry Fig. 7 (not shown). The working resistance signals are fed via an amplifier and filter to an integrator the output of which is fed to one input of a comparator. If the integrated signal is greater than a reference signal applied to the comparator a pulse is fed to a counter having a capacity of four units and which is pre-set to a count of two. After each measurement the sample is moved and a further hole drilled and the working resist- ance monitored each measurement being counted by a second counter having a capacity of four counts. After four measurements the second counter applies a reset signal to the first counter and if there are two units stored therein then a carry signal is produced to stop the drilling operation and exchange the drill. If no carry signal is produced a command signal for continuing the drilling operation. If the first two measurements produce a pulse at the input of the first counter a carry signal is produced and a clear signal is sent to both counters.