Patent GB-1340658-A (GB)
Title: Arrangement for controlling the motion of a tool-support in a machine tool
Inventor: RYAN MERLE E
IPC: B24B49/18
Filed: 1972-06-19
Abstract: 1340658 Trueing grinding wheels BENDIX CORP 19 June 1972 [6 July 1971] 28624/72 Heading B3D An arrangement for controlling in a machine tool the motion of a tool support 18 which moves cyclically to perform a two-stage forward motion including a traverse motion and an infeed motion, and to be subsequently returned to a reset position, comprises a positioning plate 26 mounted on a fixed part of the machine tool for sliding movement relative thereto in the direction of the tool support motion, the tool support having means drivingly engaging the plate during the forward motion, and a positioning element 36 in the form of a pin which terminates the infeed and initiates the return motion, slidably extends through the plate and has a head 80 resiliently biased against the plate, locating means 46 for fixing the pin during cycling motion of the tool support to prevent concomitant movement of the pin and plate but allowing the pin to move in response to termination of the forward motion, whereby the plate is repositioned at each cycle to increase the traverse motion while the infeed motion remains constant. As described, the arrangement is applied to the control of a crush dressing mechanism and consists of a position referencing assembly 12 secured to the machine base, a control switch assembly 16 and a control assembly 20 both fixed to the wheelhead 18. The assembly 12 has a bore slidably receiving a rod 22 to which is secured the positioning plate 26, the rod being engaged by an adjustable friction member 32. The pin 36 is also slidable in the housing and in the plate 26, and a spring 40 urges the pin so that a shoulder abuts the plate. The pin is releasably lockable in the housing by a clamping pin actuated by an air cylinder 46. The switch assembly 16 consists of a cam 50 which is rocked when the wheelhead moves to a position in which the cam engages a surface 66 on the plate 26, the cam having adjustable screws 54, 56 which co-operate with valves 58, 60 one of which controls the flow of fluid to the actuator so that the infeed rate is reduced to a slower precrush traverse and the other of which reduces the rate further to the crush infeed rate. As the wheelhead advances sufficient lost motion exists in the switches for the contact assembly to advance to the assembly 12 until a contact 68 on the rod 22 is engaged by an adjustable contact 70 and a circuit is made which causes the grinding wheel to be slowly rotated as it is advanced onto the crush rolls. Further advance of the wheelhead moves the rod 22 and plate 26 relative to housing 24. The pin 36 remains stationary, being' held by air cylinder 46 and the spring 40 being compressed, until a micrometer screw contact 82 engages contact 80 on the pin to complete a circuit to discontinue the infeed, the grinding wheel being rotated slowly to finish trueing. After a time interval, during which the air cylinder is actuated to release pin 36 so that it is again urged by spring 40 until the shoulder abuts the plate 26, air cylinder 46 clamps pin 36 so that when the grinding wheel is restricted. the plate 26 remains in the position it occupied at the end of trueing and the grinding wheel is rapidly advanced to that position during the next trueing cycle.