Patent GB-944460-A (GB)
Title: Control apparatus for automatically positioning the table of a machine tool
IPC: B23Q16/00
Filed: 1962-04-02
Abstract: 944,460. Machine tool details. CENTRE CIRCUITS Inc. April 2, 1962 [April 24, 1961], No. 12577/62. Headings B3B and B3C. A control device for a machine tool table &c. comprises drive means for moving the table in one direction, and stop means actuated by a part connected to the table to discontinue the drive and halt the member when it reaches a predetermined position along the direction of movement, in which the stop means comprises a series of spaced elements carried by the member, a selected one of which is engaged by means which acts to discontinue the drive, the means being adjustable over a limited distance in the direction of movement. In a boring machine 30, Fig. 1, the position of table 32 along axis Y<SP>1</SP>, Y is controlled by a device 42<SP>2</SP> (not shown), the position of saddle 36 along axis X<SP>1</SP>, X by a device 42<SP>1</SP>, and the position of support 34 along axis Z<SP>1</SP>, Z by a device 42<SP>3</SP> (not shown), devices 42<SP>1</SP>-42<SP>3</SP> being of similar type. Device 42<SP>1</SP>, Fig. 2, comprises a large movement positioner 44, and a small movement positioner 46, and the positioners control the drive for the saddle 36 which includes a lead screw 52, Fig. 3, driven by a main electric motor 54 and a stepping motor 56, a brake 58 and a gear-box being also provided. The drive 50<SP>2</SP> for table 32 is controlled by device 42<SP>2</SP>. Positioner 44 comprises a channel 64, Figs. 4, 5, 7, 8, 9, carrying a segmentally jointed cam track 66, and adjustable eccentric pins 68 accurately spaced apart at centimetre centres; the channel moving with the saddle. A pivotable latch 70 and a cam follower 72 are connected to the small movement positioner 46 by a plate 94 and they are movable in the direction of movement of the saddle by an amount S, i.e. within the limit of two pin centres. A number of code bars 86, Fig. 5, are provided to convert binary code information supplied by, e.g. a punched tape, to linear measurements and control the positions of spring-urged latches 84, which govern the positions of the pivoting sections of cam path 66. Positioner 46 has a set of positioning bars 96, 98, 100, 102 and 104, slidable in the directtion of saddle movement and latch 70 is carried by bar 96, Each bar has a single row of pins 110 on one side and a double row 108 on the opposite side and pivoted pins 168, Fig. 13, are introduced between the pins on adjacent bars to position the latter, code bars 166 actuated by cylinders 112 being positioned to place the required pin 168 between pins 108, 110. Pawl 70 is supported by a cam-shaft 138, Figs. 7-9, the latter controlling a bell-crank 142<SP>1</SP> for operating a stopping switch SW4 and cooperating with followers 146, 148 of slowdown switch SW2 and reversing switch SW7. Pawl 70 is fixed to shaft 138 and is pivoted by a pneumatic cylinder 152 and follower 72 is actuated by cam path 66 to allow a switch 74 to control the saddle drive. A double-acting pneumatic cylinder 182, Fig. 11, advances bar 96 with respect to fixed bar 104 and due to the engagement of pins 168, bars 98, 100 and 102 are also advanced, thus moving bar 96 the aggregate of the movements of all of the bars. A single-acting pneumatic cylinder 178 moves a lever 180, Fig. 11, causing pins 168 to be freed by angles 174 from code bars 166, Fig. 13, and the bars are then re-positioned.