GB436721A - Improvements in or relating to means for controlling the operation of various machine tools, mainly grinding machines and lathes, according to the size of the work - Google Patents

Abstract

436,721. Gauging-devices. DRUMMOND, A., Ryde's Hill, Guildford, Surrey. April 11, 1934, Nos. 10985 and 13445. [Class 60] [See also Group XXII] In an apparatus for controlling the operation of a machine tool such as a grinding machine by stopping or reducing the feed when the work A attains a predetermined size, the reduction of the work diameter causes two jaw members E, E<1> to be moved apart until, at the required point, a roller F passes between the jaws and causes the stoppage or variation of the feed. The work is engaged by a hardened point B carried in a block D which supports the movable jaw E and is pivoted to a slide H by means of a flexible strip J. The fixed jaw E<1> is secured to the slide H. A spring G tends to keep the point B against the work and when the latter reaches a predetermined size the roller F falls between the jaws onto a block L and causes the engagement of contacts L<2> L3 to complete an electric circuit and effect the required control such as the removal of the wheel from the work or other operation including withdrawal of the slide H clear of the work. During the withdrawal movement, which is effected by a fluid pressure cylinder M, an arm F<5> on a pin carrying a lever F<3> engages a fixed abutment F<8> to cause the lever to lift the roller F through the laws. The lever is held in this position by a latch f<6> engaging the projection f<3>, the latch being disengaged by a hand lever when required. For adjusting the apparatus to a new size of work, a ball N4 is placed between abutments on the slide H and pivoting block D respectively and is of such size that the roller F will pass between the jaws. An accurate test piece is then placed in the machine and the cylinder M and slide H shifted by means of a micrometer device N<1> until the point B engages the test piece. A work blank is then put in the machine and the ball N' removed and the grinding operation continued until the roller falls through the jaws and stops the operation. The work is then gauged and if still oversize the micrometer N<1> is readjusted, the roller raised, and the work continued until the roller again falls. This is continued until the work is the exact size required, after which succeeding pieces may be ground to size automatically without further re-setting. In a modification, Figs. 4 and 5, the point B on the block D is held against the underside of the work by a spring G and the abutments N' N3 are in direct engagement, the latter being adjustable and being swung aside when not required. In this form the member L carrying the contact L<2> is pivoted at L<7> and the lever F<3> is raised manually to reset the roller. Instead of being slidable, the member H is pivoted to the base K by a spring strip P<2> and is set for different sizes of work by means of a screw R engaging an eccentric roller R<2> mounted on a casing P secured to the member H. The screw R gives a coarse adjustment while the roller R<2> which has an eccentricity of about À002" may be rotated to give a fine adjustment. In another modification, two diamond or hardened points engaging opposite sides of the work may each be connected to a pivotally mounted jaw between which the roller passes. The device may also be employed for reducing the speed of the grinding-wheel before the finished size is reached or the roller may first pass through one pair of jaws to reduce the speed and later through a second pair of jaws to stop the operation. In another modification two rollers may co-operate each with a separate pair of jaws. The controlling means may be actuated mechanically or hydraulically instead of electrically and the roller may operate an indicator in addition to or instead of the other automatic action.