Improvements in and relating to automatic positioning apparatus for machine tools

Abstract

Abstract 764,588. Programming for machine-tools; jigs. BRITISH THOMSON-HOUSTON CO., Ltd. July 7, 1954 [July 13, 1953], No. 19360/53. Class 83 (3). [Also in Group XXXVIII] An automatically-operable positioning-apparatus for a machine-tool comprises a reference member 3 in the form of a bar of magnetic material having accurately spaced teeth or non- magnetic inserts to form reference-positions whose spacing is, for example, one inch, which is fixed to the tool-slide 1 which is adjustable by a lead screw 2 driven through a gear-box 11 by a motor M2. A sensing-head 4, containing coils, co-operates with the member 3 to produce an error-signal whenever the sensing-head is in misalignment with an adjacent referenceposition. The sensing-head is movably mounted on the bed of the machine, to which the work is fixed, and is adjustable by a micrometer screw 5 driven through a gear-box 16 by a motor M1. Control handles 10a, 10b set the integral part of the dimension, and handles 6d, 7d, 9d, 10d set the fractional part. Handles 6d &c. control the rotation of synchros 6, 7, 9, respectively, the rotations being added together by differential mechanisms 6b, 7b, 9b and gearing, and controlling synchros S6, S7, S9. The synchros S6, S7, S9 are electrically coupled to synchros S6A, S7A, S9A to produce misalignment signals which are fed to an amplifier A1 to control the motor M1 and displace the sensing head until the misalignment is reduced to zero. Similarly, handles 10a, 10b control the rotation of shaft 8 to control the synchro S8 to produce, through its electrical link with synchro S8A, misalignment signals which are fed through amplifiers A2, A4 to control the motor M2 and effect displacement of the tool slide 1. In order to adjust the tool slide and reference member 3 to a position approximating to the fractional dimension set in by the micrometer screw 5, the rotation of shaft 9 is added through gearing 9c and differential 10 to the movement of shaft 8, and when this position is reached the reduction of the error signal from synchro S8A causes a changeover switch P to operate, whereby the error signal from the sensing head 4 is fed via amplifier A3 and amplifier A4 to control the motor M2. Operation of switch P also effects an increase in the ratio of gearing 11 for the final adjustment, and when the desired position is reached the motor M2 may be disconnected and a mechanical clamping-device 12 operated. The handle 10c is used for setting in a datum dimension and is adjusted prior to the setting of the other handles. The information for positioning the tool-slide or table or controlling the depth of feed may be set in either by hand, punched card, or tape, the mechanism for reading the latter being of contact or photoelectric type.

Inventors

• 👤 Murray Monk
• 👤 Frederick Ambrose Fossey

Bibliographic Details