Patent GB-1128930-A (GB)
Title: Improvements in and relating to tracer assemblies
IPC: B23Q35/36
Filed: 1965-11-18
Abstract: 1,128,930. Copy-milling. TRUE-TRACE CORP. 18 Nov., 1965 [18 Nov., 1964], No. 49112/65. Heading B3K. A tracer device comprises a body having three bores 51, 52, 53, Fig. 2, which are perpendicular to one another, two of the bores being in a horizontal plane and receiving two control elements acting on two motor members, each control element having a sleeve in which a spool may slide and rotate, a vertical stylus 48 mounted in the third bore by a ball member 125, a bias force means actuated by a reversible fluid-drive motor (188) co-operating with the stylus to bias it towards a template, and a signal tube 168, Fig. 4A, coaxial with the stylus and rotatable by the motor, the upper end of the tube being connected with a compressed air chamber 169 and the lower end having a signal orifice 175 facing a cylindrical surface of the third bore, the angular position of the bias force means and hence its line of action being controlled by selector means sensitive to signals arising as a function of the distance between the signal orifice and the cylindrical surface. A table 37 and a cross-slide 35 are moved by piston motors 38, 36 or by rotary motors and screws, and a knee 34 is moved by a piston motor 32 to provide X, Y and Z axis movements under the control of the valves 51, 52 and 53. The spools 57 of the valves 51 and 52 are each rotationally adjustable by a gear 94, Fig. 6, the supply grooves 60, 70 being notched to provide a flow rate control in addition to the control obtained by axial movement of the spool. The rotational adjustment is achieved by a handle 100, a scale 102, adjustable cams (106, 107), and gearing connected to the gears 94, so that the valves are adjusted simultaneously. The stylus 48 has a spherical projection 125 seated in the valve 53 and a projection 126 yoked to the valves 51, 52. The tracer moves the valve 53 vertically and its angular movement is limited by a ring 133 co-operating with a spherical projection 127. The bias means is mounted on the rotatable ring 138 and carries two arms 136, 137 having rollers 139 urged against the stylus 48 by springs 140. The ring 138 is rotated by a toothed belt (144) driven by a gear 146 from worm gearing 149 and a reversible fluid motor (188). The bias can be rendered inoperative by rotating a ring 150 carrying cam lobes 156 which engage pins 151 or the arms 136 and withdraw the rollers 139 from the stylus so that 3-D copying may take place without the vertical movement of the stylus being locked. The bias rotational drive also rotates the signal tube 168, Fig. 4A, via a shaft 147, belt gearing 162 and a sleeve 167. The tube is supplied with air through the chamber 169 which bleeds through the orifice 175 within the ring 133. The lower end of the tube is rotatably connected to the stylus 48. The direction and rate of rotation of the motor (188) which rotates the bias ring 138 and the signal tube 168 in unison, is determined by a valve 197, Fig. 9, associated with a control chamber 203 connected to the bleed orifice 175. The bias force extends between 30 and 60 degrees to the normal to the surface traced, with a steady position at 45 degrees. Angles below 45 degrees denote an outside corner, Fig. 20 (not shown) and above, an inside corner, Fig. 22 (not shown). Reference has been directed by the Comptroller to Specification 853,797.