Patent GB-1063375-A (GB)
Title: A presettable control system for a machine tool
IPC: G05B19/10
Filed: 1964-03-17
Abstract: 1,063,375. Machine tools. KEARNEY & TRECKER CORPORATION. March 17, 1964 [Sept. 3, 1963], No. 11313/64. Headings B3B and B3K. A machine tool (e.g. a milling machine) comprises a number of power-driven movable elements 43, 45, 46, Fig. 1 (not shown), actuatable to perform different programmes, presettable programme control means 55, Fig. 2 (not shown), and an auxiliary controller 64 actuatable by the programme control means to produce a sequence of functions different from that established by the programme control means. A programme control panel 36 on a cabinet 35 presents separate manually-operable means for presetting the programme and an associated cabinet 37 provides a source of fluid pressure. The cabinets are connected to the machine tool itself by flexible electrical and hydraulic conduits. The work-table 46 is moved on the saddle 45 which is movable on the knee 43, which is balanced by fluid-pressure. An hydraulic motor (153) is mounted in the knee and is connected to drive the elements through hydraulic clutches, hydraulic brakes and nut- and-screw mechanism. The positions of the elements are gauged by lineal transducers. The single servo drive motor (153) serving precisely to control movement along three axes, co-operates with a single command transformer network. The latter includes transducer primary windings each tapped at inch intervals and having current supplied to each end in controlled proportions to produce a point at which a secondary winding produces a null signal for stopping movement of the associated element. The panel 36, Fig. 2, includes a set 55, of 32 pairs of rotatable switches having indicia viewed through apertures. The switches determine which function(s) will occur during each of 32 phases PH-1 to PH-32. The extents and rates of movement of the members are set-in on the three sections of a sub-panel 56. For instance, if switches PH-3 on the sub-panel 55 are set as shown, the switches P-1 on sub-panel 58 are rendered effective, these switches being set to move a slide at a rate of 5.5 inches/minute'to a position at 6.785 inches from a datum along the Z axis. The same position and feed rate is also selected in respect of the X-axis by switches PH-9. Again, switches PH-18 select the switches P-2 on sub-panel 57 to give a feed rate of 6.6 inches/ minute along the Y-axis. The switches on sub-panel 59 are only for rapid movements, to positions set by the groups P-1, etc. The tool-spindle speeds are set-in on a panel 62, and are obtained from a two-speed hydraulic motor driving through hydraulically-controlled clutches and brakes. A rotary switch is stepped round to select automatically the speed appropriate to each tool, the switch being automatically " homed " when a cycle is complete. The panel 64 enables sub-cycles to be selected, that is, with switches 11A, 11B of phase PH-11 on panel 55 set as shown, a set of switches P-1 is caused to act sequentially before the programme continues with phase PH-12; this sub-cycle P-1 is operative again at phase PH-29. A further panel 66 has two switches for recycling. Thus, by setting the switch RE-1 at " 3 " and the PH-12 switches on the programme panel 55 at S-P7, the programme re-starts at PH-3 and re-cycles to the stage then reached. The second switch RE-2 determines how the programme shall then proceed. The rotatable switches have dials 70, Fig. 3 (not shown), a wiper arm 72, and a knurled setting wheel 71, and are associated with a " function select controller " such as AR, BR comprising banks of relays, a " sub-function controller " and an " action-complete controller ". In some cases, speed changes are effected automatically when a particular operation is selected so that only one programme command is necessary. Prior to a speed change, the spindle rotation is automatically stopped. The supply of mist coolant and coolant is controlled by the programme. A sub-cycle may be repeated to use two tools successively with different feed speeds but with the same positional movements. A frame member 50, Fig. 1, may be replaced by a tool-changer. The tool changer, Fig. 8 (not shown), is generally as described in Specification 1,022,194. It has a tool-changing arm 345, an inclined turret 346 and a collet 358 actuated by springs 361. The arm 351 is rotated by an hydraulic motor 380 controlled by cams 370, 371 and advanced axially by an hydraulic piston 398, which also moves a stop rod 390 mounted in a cylinder 389. The turret is indexed step-by-step by an hydraulic motor stopped and reversed by a dog 430 engaging a switch 431 to cause a dog 420A to abut a positioning lever 424. To provide a datum position for the turret, one tool is elongated to engage a switch arm 439. A tool is retained in the arm 345 by a spring-pressed ball 446, Fig. 9E (not shown). The rotary switches 1A, 1B which are initally set-up manually are rendered operative in turn by relays PH-1 to PH-16 which are energized in succession by a stepping switch (1251A-E- not shown) having five banks, four of the banks being utilized to render effective the re-cycling functions of the switches RE-1 and RE-2. The completion of each function initiates the following function. The machine cycle is initially started by manual depression of a button. A coil is then energized intermittently to advance the stepping switch. The programme may be automatically stopped at any point, being restarted by the manually-actuated button. When a portion of the programme is re-cycled, the re-cycled portion is identical with the previous portion, including the repetition of sub-cycles, except that different tools may then be in use. Tool changes are initiated manually or may be automatic. The tools themselves may also be changed manually and clamped and released automatically. The programme may be pre-set to stop at a particular point for inspection purposes. Prior to the stop, the operator has to depress a button 1630 (not shown) to set the circuit for stopping. Alternatively, the machine may be stopped automatically. If the programme does not require all the switches available, the rotary switches are returned to their initial positions automatically, a time delay allowing the machine to be re-set before being switched off. Modified positional control.-In a modification, relays TH-0 to TH-9, etc., Fig. 29 (not shown) are selected to bring into circuit resistances 1763-1767 and produce voltage command signals in conductors 1780, 1792. One signal passes to a resistance 1760 engaged by a contact 1761 on a nut on the saddle 45, thus enabling its position to be set in conjunction with a discriminator amplifier 1790. At the set position, the " position complete " relay 1PR actuates the programme controller to advance to the next stage.