Electrical transmission or interconnection systems – Switching systems – Condition responsive
Patent
1984-06-08
1986-07-08
Tolin, G. P.
Electrical transmission or interconnection systems
Switching systems
Condition responsive
33169C, G01B 702, G01B 712
Patent
active
045995249
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to position-sensing apparatus and to a probe for sensing the position of an object in such apparatus.
It is known in numerically controlled machine tools to provide an automatic tool change mechanism adapted to connect either a tool or a probe to the operating spindle of the machine, the probe being required for the purpose of measuring a workpiece machined by the tool. When a tool is connected to the spindle the latter is then rotated to perform a cutting operation but when a probe is connected to the spindle the latter is held against rotation as is required for a probing operation.
The probe comprises an assembly including means defining an electric circuit, a battery for energising said circuit, and means for changing the state of the circuit responsive to the probe attaining a sensing relationship with the workpiece. It is also known to provide the assembly with a switch for switching the battery on or off, the switch being operated to switch the battery on by engagement of a switch operating member with the spindle when the probe is connected to the spindle, and the battery being automatically switched off when the switch operating member becomes disengaged from the spindle as a result of the probe being removed from the spindle. Thus the probe is armed only when it is connected to the spindle and battery power is saved in this way. However, there is still a waste of power because the probe is not in use all the time it is connected to the spindle. It is an object of this invention to reduce or overcome this difficulty.
SUMMARY The above and other objects are accomplished according to the
invention wherein the battery is switched on by rotation of the spindle, prior to the spindle being held against rotation for the probing operation itself. Such a spindle rotation may also be used to switch the battery off. In this way the time during which the battery is on can be related to the probing operation itself rather than to the time the probe is present on the spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
An example of position-sensing apparatus according to this invention will now be described with reference to the accompanying drawings wherein:
FIG. 1 is an elevational view in partial section and partial block circuit diagram form showing a part of a machine tool embodying the invention.
FIG. 2 is a sectional view through the line II--II in FIG. 1.
FIG.3 is a circuit circuit schematic in partial block circuit diagram form showing an electrical circuit for use in the tool according to the invention.
FIG. 4 is a circuit schematic in partial block circuit diagram form showing an alternative circuit.
FIGS. 5 and 6 are views similar to FIGS. 2 and 4, respectively, showing a modification thereof.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIGS. 1, 2 the machine tool has a tool spindle 10 supported for rotation in a bearing housing 11. The rotation of the spindle is effected by a program 13 connected to a control system 12 for the latter to output a miscellaneous function signal 14 to a motor 15 connected to one end of the spindle 10. The other end of the spindle 10 has removably connected thereto a probe 16 for sensing the position of a workpiece 17 mounted on a table 18 which is movable relative to the spindle by a numerical control signal 19 output by the control system 12. The position of the table 18 is communicated to the system 12 by a feedback signal 20. The probe 16 is connected to and removed from the spindle 10 by an automatic tool changer 21 operated by a miscellaneous function signal 22 from the system 12.
The probe comprises a housing 23 supporting a stylus 24. The position of a surface 25 of the workpiece is sensed by moving the table 18 so that the stylus 24 engages the surface 25. Responsive to such engagement the probe disestablishes a signal 26 which is transmitted from the probe housing 23 to the stationary structure defined by the bearing housing 11 by means of an inductive coupling 27. The signal 26 is connected to the syst
REFERENCES:
patent: 4145816 (1979-03-01), Stobbe et al.
patent: 4178714 (1979-12-01), Tsen et al.
DeBoer T.
Renishaw plc
Tolin G. P.
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