Patent GB-842606-A (GB)
Title: Improvements in or relating to grinding machines
IPC: B24B47/26
Filed: 1957-02-07
Abstract: 842,606. Grinding. NEWALL ENGINEERING CO. Ltd., and HOARE, S. W. Feb. 7, 1957 [Feb. 7, 1956], No. 3847/56. Class 60. A grinding machine of the type in which the workpiece 16, Figs. 1 and 2, is mounted on a longitudinallytraversing table 13 and the grinding wheel 15 is carried by a wheelhead 14 slidable to and from the workpiece, has a stop member 22 carried by the wheel-head, and a cooperaging stop member 17 provided on the machine bed, one of the stop members being movable to bring a plurality of differently-dimensioned abutments 24, Fig. 3, in succession into the path of the other stop member to adjust the stopping position of the wheel-head on its approach to the workpiece and hence the size to which the workpiece is ground. The wheel-head is reciprocated to and from the workpiece by a quick-advance hydraulic cylinder- and-piston device 20, the cylinder of which has a spigot 19 formed at its rearward end to locate a circular stop-plate'17 bearing the abutments 24 ; these abutments are grouped circularly around the stop plate, diametrically-opposed pairs being of the same axial depth. A rod 21, which passes slidably through the spigot, is attached, at one end, to the piston of the device 20, and at the other end, to the stop member 22 formed with two diametrically-disposed projections 23 which engage a pair of diametricallydisposed abutments 24 to determine the final forward stop-position of the wheel head. A gear 26, which is attached to the stop-plate 17, is rotated during the return stroke of the wheel-head to bring successive abutments 24 into the path of the projections 23 by a pivotally-mounted piston- and-cylinder device 34. The piston is formed with a rack which engages and rotates the gear 26 on its forward stroke when the device is swung into the engaged position. The swinging movement and effective action of the device 34 may be manually operated by a lever at the front of the machine, indicator lights and an interlock ensuring that the stop-plate is returned to its correct starting position for each workpiece. The initial movement of the wheel head is at a fast rate and shortly before the final forward stop-position is reached, a slow feed of pre-set fixed length is operated to grind the workpiece to the finished size. Shortly before the finished size is reached, a lever operated by the wheel-head causes a micro-switch to actuate a time-delayed hydraulic relay. The time delay permits the wheel-head to reach its forward position before the relay actuates a solenoid-operated valve 42, Fig. 8, to supply fluid pressure to one end of a piston-andcylinder device 52 which traverses the table 13 on slideways 12, and operates a solenoidoperated valve 45 to supply fluid pressure to a valve 44 which withdraws a plunger 37 from a slot in a control bar 35 secured to the table 13. When the first section of the workpiece has been ground, a cam 56 on the control bar 35 operates a micro-switch 55 which causes the wheel-head to be withdrawn from the workpiece and the device 34 to bring the pair of abutments 24 into the path of the projections 23. At the same time, a cam 59 co-operates with a lever 58 to actuate a valve to increase the table traverse speed, which is then reduced as the lever rides off the cam and the next section of the workpiece is approached. The table traverse speed is further reduced by the plunger 37, which is urged by a spring 49, engaging a recess 53 to move a spool 43 in the valve 44 and operate a valve 54 to increase the back pressure in the fluid supply bin 51. When the plunger engages the slot 48, the spool 43 operates a valve 50 which closes the fluid supply bin and stops the table for the next section of the workpiece to be ground. The wheel-head is then moved towards the workpiece, by the plunger 37 actuating a micro-switch 60 at the end of the slot 48. At the completion of grinding the final section of the workpiece, a two-step cam 61 actuates the micro-switch 55 to return the wheel-head and a micro-switch 62 which reverses the valve 42 to supply fluid to the opposite end of the device 52 and return the table 13 to the starting position where the plunger engages a slot 38, and a cam 63 operates a micro-switch 64 to stop the machine ; the slot 38 is less in depth than the slots 48 to ensure that the relay 60 is not operated to feed the wheel-head into the workpiece. A fresh workpiece may be inserted in the machine either manually or by automatic hopper feed. Withdrawal of the plunger 37 is effected by a lever 47 which operates the solenoid 46, valve 45 and valve 44. A manualcontrol member 65, Fig. 1, actuates a microswitch to connect the wheel-head to a feedwheel for manual control of the wheel-head. If desired, the adjustable stop device for the wheel-head can be used without the automatic table traverse, but in conjunction with a rotary turret at the front of the machine with different stops or dogs being used to bring each section of the work-piece in turn into alignment with the wheel-head. The hydraulic fluid may be maintained at a constant temperature by means such as described in Specification 790,430. A wheel trueing unit may be mounted on the wheel-head.