GB816950A - Improvements in or relating to feed adjustment means on thread-grinding machines - Google Patents

Abstract

816,950. Screw-thread grinding. LINDNER G.m.b.H., H. March 21, 1958 [April 17, 1957], No. 9211/58. Class 60. A feed adjustment means in a thread grinding machine having automatic adjustment of the grinding wheel 1 to divide the depth of the thread to be ground on a workpiece 2 into a plurality of cutting depths for each grinding operation, has the individual depths of cut selected to be of desired amounts by means of feed stops 9 adjustably mounted on a drum 5, and an actuating member 25 which, in one direction of movement, actuates the feed carriage 3 of the grinding wheel up to a position determined by a selected one of the feed stops and, in the other direction of movement, prior to contracting a fixed stop 28<SP>1</SP>, causes the grinding disc to be withdrawn from the workpiece and the drum to be advanced to render the next feed stop effective. The feed stops 9 comprise screws which are adjustable in blocks 81, 8<SP>4</SP>, in turn, adjustable along longitudinal dovetailed grooves 7 in the drum 5 to positions determined by circumferential grooves 7<SP>1</SP>. The drum is indexable to bring the stops successively into operative position for engagement with a stop 24 on the actuating member 25 by bevel gearing 15, 16 driven from a pawl-andratchet mechanism 14, 18 operated by movement of a plunger 23 when it is engaged by the stop 24 during the movement of the member 25, a disc 11 and resilient index bolts 12 assisting in determining the operative positions of the drum. The member 25 is, at one end, connected by a rack-and-pinion device 27, 27<SP>1</SP> and an electromagnetic clutch 48 to a gear 49 which, in turn, is connected to gears 50, 51 driving the feed spindle 4 of the carriage 3 and, by means of a second electro-magnetic clutch 53, can be connected to a handwheel 55. The opposite end of the member 25 is connected to a piston 26 axially movable in a cylinder 28 by fluid pressure supplied to alternate ends thereof under the control of a reversing valve 30 actuated by a solenoid 32, 33, 34. After the completion of a grinding operation, a switch or relay contact 46 is operated manually, by a stop on the table or by the automatic machine section to energise one side of the solenoid which operates the reversing valve 30 to supply fluid to the lower end of the cylinder 28 and displace the member 25 and hence, withdraw the grinding wheel, which may be single-or multi-ribbed, from the workpiece. During its movement, the member 25 causes the stop 24 to engage the plunger 23 and actuate the pawl-and-ratchet mechanism to rotate the drum 5 and bring the next stop into operative position. The movement of the member 25 is limited by the piston 26 contacting a fixed stop or, as shown, the cylinder and 28<SP>1</SP>, whereupon the pressure in the supply line 35 increases and operates a pressure switch 40 to energise the other side of the solenoid which then actuates the reversing valve to supply fluid to the upper end of the cylinder to effect feed of the grinding wheel into the work to a depth determined by the position of the selected stop 9. The carriage 3 can be manually adjusted by the handwheel 5 by movement of a switch 56 which engages the clutch 53 and disengages the clutch 48. When all the stops are not required, they can be set to idle positions so that, in moving the drum to its initial position, the grinding wheel is prevented from engaging the workpiece. One rotation of the drum may be used to control the depth of grinding of a single workpiece or, if the number of cuts per workpiece is an integral. of the member of stops, a plurality of workpieces.