Patent GB-554489-A (GB)
Title: Improvements in metal cutting or other machine tools
IPC: B23Q17/09
Filed: 1942-07-21
Abstract: 554,489. Lathes &c. WARNER & SWASEY CO. July 21, 1942, No. 10180. Convention date, Sept. 18, 1941. [Class 83 (iii)] A machine tool such as a lathe has a part movable by a driving train which includes associated means for indicating visibly and directly the force applied to said part during the operation of the machine. As applied to the indication of the clamping pressure exerted by the jaws of a collet chuck on a stock bar 39, the collet jaws 37 are closed by axial movement of a tube 40 actuated by fingers 44 which are rocked by the axial movement of a cone member 47. The latter is actuated by a lever 49 pivoted at 50. This lever has a part 51 having a recess 53 coacting with a roller 57 carried on a disc 55 which is lockable in two positions spaced 180 degrees apart by a roller on a lever 69 operated by lever 71. The disc 55 is driven by a worm 61 splined on a shaft 62 moved axially by the lever 69. When the shaft is moved by this lever a friction clutch 73 is engaged, thus connecting the shaft 62 with a driving motor 76. When the clutch 73 is disengaged by reverse movement of lever 69 the brake clutch part 73 engages a brake disc to stop rotation of worm 61. The worm 61 is axially movable and communicates its axial motion to a member 77 which operates lever arms 79 on a rock shaft 80. The resistance to rotation of the worm 59 thus causes the worm 61 to move axially and rock the shaft 80. This operates a camming member 85, Fig. 10, engaging a roller 86 on an arm 87 attached to a fluid filled bellows 88 connected by a line 89 with a cylinder 90 enclosing another bellows device connected to the pointer 95 of a gauge dial 97 which may be viewed through a window 98. The dial is graduated to indicate the pressure with which the work is being gripped in the collet and its indication is produced by the axial movement of the worm 61 produced in transmitting torque to the disc 55 which operates the chuck cone 46. In order to ensure that the indicating-pointer remains in the position to which it is moved throughout the time that the jaws grip the work a slidable wedge member 99 under the action of a spring 100 is caused to move downwardly when the arm 85 is rocked clockwise, Fig. 10, and prevents backward movement of the arm so that pressure on the bellows is maintained. The wedge may be moved upwardly against its spring by lever mechanism operated from a push pin 105. A second wedge 106 prevents forward movement of the arm 85, this wedge being connected to a rock shaft 109 which may be actuated to move the wedge upwards by a push pin 111. The push pins are actuated automatically by a cam disc on the spindle of worm wheel 59. When the handle 71 is operated to release the work the cone 47 is first moved to the dotted position, Fig. 1, and then the cam actuates the pin 105 to raise wedge 99 and permit return movement of the arm 85 thus restoring the indicator to zero and the worm 61 to its original position. After release of the work and during the stock feed the cam rotates further to release pin 105. When the stock has been fed the handle 71 is again actuated to engage clutch 73 to close the chuck and cause cam to actuate push pin 111 to raise the wedge 106 to allow the forward rocking movement of arm 85 and give an indication of the gripping pressure. Finally the pin 111 is released and the wedge 106 moved to a position wherein it prevents further forward movement of arm 85 and ensures the constancy of the reading of the chucking pressure on the indicator. In a modification, Fig. 16, the invention is applied to a machine with a sliding jaw clutch for either internal or external chucking and having a scroll operated by pinions 114 to which a wrench 116 may be applied. This wrench is moved axially by a segment engaging a circular rack 119, the segment being operated from a handle 134 acting through lever mechanism 133, 129, 128. An indicator 132 shows the locked and free positions of the chuck. The wrench is driven by a reversible motor 138 through worm gearing 135, 122, and the worm wheel incorporates a lost-motion connection 121 designed to impart a hammer blow to the chuck to open the same on reversal of the motor. The worm is free to move axially when its rotation is resisted and this axial movement operates a lever 144 pivoted at 145. An eccentric device 146 is arranged to permit rocking of the lever in one direction only according to whether the chuck is used for internal or external gripping. The end of the lever 144 exerts a camming action on a roller 153 carried by a pivoted lever 154 which operates a bellows 157 connected to a second bellows 162, Fig. 25, which operates a dial pointer 166 to indicate the chucking pressure. Another pointer 171 moving over the dial may be set to indicate the required chuck pressure and this setting also positions a micro-switch finger 186 coacting with a wire attached to the bellows 162 so as to switch off the motor 138 when the desired chuck pressure is reached and the indicating pointer coincides with the pointer 171. The motor is controlled by the circuit shown in Fig. 24. A reversing switch 197 adapts the machine for either internal or external chucking and a lever 189 operated by a rocking movement of the handle 134 selectively controls contacts 191, 193 in the circuits of solenoids operating switches 198, 199 for actuating the motor in one direction or other to open or close the chuck. The micro-switch 186 controls a solenoid operating a latch 209 to allow a switch 204 to be spring opened to stop the motor. This stoppage occurs as soon as the pre-set chuck pressure has been reached. In another modification the invention is applied to the measurement and indication of the torque applied in a mechanical feed train operating machine tool slides such as a saddle 217, Fig. 28, and cross slide 218. The motor 220 drives through gearing 223 a worm shaft 224 carrying a worm 229 driving a worm wheel 231 on a shaft geared to the cross-slide feed-screw and a worm 230 driving a worm wheel 232 driving a rack-pinion 249 operating the saddle feed. The worm-wheels are selectively locked to their shafts by clutches 239, Fig. 30, controlled by a handle 243. If either feed train is rendered operative the torque transmitted causes axial movement of the worm shaft 224 to operate a pivoted lever 251 which exerts a camming action on a roller 256 carried by an arm 257 which operates a bellows 259 connected to a second bellows associated with an indicator similar to the indicator 166. The motor control may also be similar to that described above. When the tool is in operation the pressure shown on the indicator should be somewhat less than that of the pre-set hand but if a positive limit stop is encountered the increased torque will cause further movement of the movable hand so that after a short period of dwell for the tool, the motor 220 is de-energized. This stoppage also acts as a safety device to stop the motor if the feed train is overloaded.