GB1039149A - Programme control for machine tools - Google Patents

Abstract

1,039,149. Machine tool details. BULLARD CO. March 15, 1965 [March 25, 1964; May 11, 1964 (2); July 1, 1964; July 20, 1964; Nov. 23, 1964], No. 10959/65. Headings B3B, B3C and B3T. [Also in Divisions B4, F2 and G3] A programme control for machine tools 73, 74, 75 comprises a tool slide 17 slidable horizontally on runners 18 of a saddle 15 which saddle is slidable vertically on runners 16. The saddle 15 is moved by a piston-cylinder device 20, 19 under the control of a valve 24 while the slide 17 is moved by a piston-cylinder device 51, 50 under the control of a valve 55. The valves 23, 55 are actuated by templates 42, 67 which are mounted on a common shaft 68. Each template comprises a pair of discs, such as 76, 77 which co-operate with stylii 45, 46 mounted on a plate 43 pivoted to the valve body 24. An arm 40 carried by the plate engages the piston valve 31 of valve 24. The disc 76 engages the stylus 46 when the valve 31 is to be moved downwards from a centre or null position while the disc 77 engages the stylus 45 when the valve 31 is to be moved upwards. When one disc engages its associated stylus the other is free from its associated stylus and vice versa. The contours of the discs are shaped to correspond with the required programme with respect to the direction of movement and the rate of movement. The discs 81, 82 act on valve 55 in a similar manner. When the valve 24 moves the saddle 15, a rack 30 moves with it and acts through pinions 29, 27 and rack 26 to move the valve body 24 hence the lever 43 relative to the template 42 until the valve is recentred. The feedback for the valve 55 is provided in a similar manner through a rack 61, pinions 60, 58 and rack 57. The shape of the discs with the lettering A-S show the contours for carrying out the inner and outer facings of an element 13 in Fig. 1 (not shown). In a modification, a relay valve is arranged between the valves 24, 55 and the piston-cylinder devices and in a further modification, the pistoncylinder devices are replaced by rotary motors. The Specification also describes an arrangement of using similarly contoured discs of different sizes. The valves 24, 55 may be replaced by valves controlling the supply and exhaust of fluid to the larger area sides of the pistons while the smaller area sides are continuously supplied with fluid under pressure. In a further modification, the template is sensed by a balanced inductance arrangement having an E-shaped armature which is displaced by a follower cooperating with the mechanical feedback. In an alternative follow-up arrangement the hydraulic servo system is replaced by D.C. motors controlled through amplidynes. For hydraulic motors, the electrical signal acts on solenoid pilot valves. A further form of the invention provides a similar hydraulic control as above with the movement of the slide being provided by differential opposed pistons carried by the slide and working in cylinder in the saddle. To prevent the saddle falling when the machine is at rest, a spring-loaded piston brake acts on the saddle, the brake being released by hydraulic pressure when the system is started. The Specification also describes the construction of a pilot spool valve (see Division F2). A tool holder, Fig. 33, comprises a tool 550 fixed to a part 531 which frictionally engages a member 510 mounted on a support 512. The part 510 has rectangular recesses 513, 514 for slippers 518, 521 which have limited vertical and horizontal movement in the recesses respectively. Members 524, 525 with integral eccentric pins 526, 527 are received in bores of the slippers. The 531 has a rectangular bore 535 whose sides are engaged by a pivot pin 528. Rotation of the pin 526 .by a spanner moves the part 531 vertically relative to the part 510 while rotation of the pin 527 causes the part 531 to pivot about the pin 528. Indicators 553, 556 show the relative position of the parts.