GB747357A - Improvements in or relating to a threading unit for use with a workpiece holder - Google Patents

Abstract

747,357. Screwing. SHEFFIELD CORPORATION. Nov. 9, 1953 [Nov. 18, 1952], No. 30932/53. Class 83 (3). A machine for screwing or tapping comprises means 21 on a spindle 16 for detachably connecting a threading tool 15, drive means 35 on means 42 which supports the spindle for sliding movement and rotates it always in the same direction, a lead unit including a screw 18 fixed to the spindle, means 106 for disengaging the lead unit, and a return mechanism 61, 62 for rapidly returning the spindle after a threading operation. A key 43 in the spindle 16 conveys the rotary motion from the sleeve 42 and permits the sliding movement. The worm-wheel 35 is rotated by a motor 2A through a belt 26 and change gearing 30 ... 32. The spindle is rapidly returned after threading by a motor 1A driving through a chain 56, a planetary gear clutch 65, 66, 67, 70, the pinion 61 and the rack 62 on the spindle. With a brake 72 engaged, the gear 65 rotates the wheel 67 to return the spindle. With a brake 74 engaged, the wheels 65, 66, 70 rotate idly and the spindle is held fast, thus allowing the unit to be mounted vertically. In operation, motor switches are pressed to start the motors 1A, 2A and a cycle-start-switch is pressed to energize a solenoid to move the yoke 106. The yoke 106 carries with it a sleeve 102 having a cam surface to close nut-segments 19 on to the lead screw 18. A solenoid is also actuated to release the brake 74. The spindle advances together with the die head 15 which is opened and closed by abutments on a rod 112. An adjustable abutment 90 carried along with the spindle actuates a switch 109 at the forward limit of movement to move the yoke 106 and release the nut segments. Movement of the yoke 106 also actuates a switch 120 to operate the brake 72, causing the spindle to be returned. At the rear limit a further adjustable abutment 91 actuates a switch 110 which de-energizes a solenoid to allow the brake 74 to be applied by spring means, thus holding the spindle against axial movement. This brake is also applied automatically in the event of power failure, or by pressure on a stop-button which cuts off all current. Lubricating machines.-A cam-driven pump 29 in a sump in a casing 13 supplies oil to a bearing 51, to the spindle and, if desired, to the lead unit. The spindle 16 is helically grooved externally and the sleeve 42 internally, for lubrication.