Patent GB-972117-A (GB)
Title: Grinding machine
IPC: B24B5/42
Filed: 1963-09-30
Abstract: 972,117. Grinding. NORTON CO. Sept. 30, 1963 [Oct. 3, 1962], No. 38332/63. Heading B3D. A crank-shaft grinding machine comprises power-driven rotatable work-supporting means 117, 118, means 21 automatically operable to perform a series of grinding operations on the respective crank pins #1 . . . #6, and angular indexing means automatically operable in the intervals between successive grinding operations by engagement with a crank-pin to position successive crank-pins angularly for the next grinding operation. The machine also includes axial indexing means automatically operable in the intervals between successive grinding operations to position the crank-pins axially for the next grinding operation. The crank-shaft W is supported by a pair of pot chucks 117, 118 on a pair of workheads 115, 116 in the machine which is generally similar to that described in U.S.A. Specification 2,723,503. The workheads are mounted on a table 23 which is movable by a piston-andcylinder device 28 to position successive crank-pins in alignment with a grinding wheel 21 on a slide 19 movable towards and away from the crank-shaft by a piston-and-cylinder device 15. Opposite the grinding wheel a combined end-wire locator, steady rest and gauge assembly 31 is disposed, the assembly which may be similar to that described in U.S.A. Specification 3,076,296 being advanced and retracted by a piston-and-device 57; a further device 56 is operable to rotate the endwise locator which has rollers at its end for engaging opposite faces adjacent the crank-pin. Each pot chuck has a half-bearing 35 which locate the main bearings of the crank-shaft eccentrically with respect to the axis of rotation of the workheads by an amount which ensures that a crank-pin can be disposed coaxial with the axis. The crank-shaft is frictionally gripped in the half-bearings by jaws 37 on bell-cranks 25 actuated by piston- and-cylinder devices 39a, 39b. A further device 39c is operable to reduce the pressure exerted by the jaws so that when the workheads are rotated and a camming element 41 having a roller 46 is raised to an operative position, shown dotted in Fig. 2, by actuation of a cylinder device, the crank-shaft slips angularly relative to the pot chucks until the crank-pin engaging the camming element is coaxial with the axis of rotation of the workheads; adjustable spring-loaded blocks 91 are carried by the jaws for engagement with the crank-shaft. Three camming elements 41 are provided for operating on respective pairs of coaxial crank-pins, each element being actuated by a respective cylinder device 16, 17, 18. The crank-shaft is locked in its newly-adjusted position by a pin 85, Fig. 7, on a piston 82 being engaged with one of a plurality of holes 86, each hole being coaxial with a respective crank-pin, in an end face of a cylinder 83 carried by a pot chuck. The rod 75 of the piston is rigidly connected to a plate 71 from which projects a pin 72 adjustably received by a yoke 64 having a further pin 63 engaging a slot or hole 101 in a flange 102 of the crankshaft. When the pin 85 is retracted from a hole 86, the crank-shaft can be angularly indexed by the camming element 41 to the next position and the pin 85 engaged with the reset hole in the cylinder to lock the crank-shaft against rotation relative to the workheads. Axial indexing is effected by the device 28 under the control of a plunger 87 engaging notches 89 in a plate 88 movable with the table 23. Plungers 111 are disposed within certain notches to prevent angular indexing between successive grinding operations when the next crank-pin to be ground is coaxial with a crank-pin just ground. In operation and with a new crankshaft loaded in the machine with the crankpin #6 adjacent the grinding wheel, actuation of a push-button PB causes a valve U8 to advance the piston of cylinder 57 and the combined end-wise locator, steady rest and gauge assembly 31. When a lever 58 carried by the assembly contacts the crank-pin to be ground, a valve V9 is actuated to direct fluid pressure to cylinder 56 to rotate the end-wise locator and a time delay relay 5TR, after an interval sufficient for end-wise location of the crankshaft and spark-splitting, operates valve V5 to direct fluid to cylinders 39a, 39b and 39c to effect clamping of crank-shaft by the jaws 37, the pressure supplied to the cylinders acting on pressure switches 2PS, 3PS which prevent operation of valve 19, so that piston 82 is not retracted during the grinding cycle, and actuate control relays 10CR, 10ACR and a solenoid S2 simultaneously. Relay 10CR actuate valve V9 to direct fluid to the upper end of cylinder 56 to retract the end-wise locator. Relay 10ACR actuates a solenoid to lift a roller 122 on a lever 123 from a notch 121 in a cam surface concentric with the workhead, the notch serving to position the workheads for loading and unloading of the crank-shaft. Solenoid S2 operates a valve V2 to actuate the feed motor 15 for the grinding wheel slide 19, the motor, in turn, operating limit switches 1LS and 3LS to drive a motor M1 which rotates the pot chucks during the grinding operation. A one-way clutch OC prevents concurrent rotation by a motor M3. The grinding is terminated by automatic control means having a timer and air gauge G1 which de-energize control relays 10CR, 10ACR and solenoid S2. Relay 10CR causes the device 57 to retract the assembly 31, and solenoid S2 operates valve V2 to cause the motor 15 to retract the grinding wheel, which causes limit switch 1LS to stop the workdrive motor M1 and de-energize control relay 1CR. Relay 1CR operates valve V15 and valve V15a blocking exhaust from cylinders 39a, 39b and connecting the large end of cylinder 39c to exhaust, the piston in cylinder 39c then moving against an adjustable stop so that a predetermined quantity of fluid is withdrawn from cylinders 39a, 39b to reduce the pressure acting on the clamping jaws 37. Relay 1CR also actuates valves V13, V14 so that the lowspeed motor M3 is operated to rotate the pot chucks to effect angular indexing. At the same time, a valve 23 is operated to cause the plunger 87 to be withdrawn from notch 89 for an interval controlled by a time delay relay 3TR which then operates valve Vll to urge the plunger against the notch bar. When the plunger is disengaged from the notch, fluid is supplied to the left-hand end of cylinder 28 to traverse the table 23, the cylinder moving and the piston being fixed. Upon engagement of the plunger with the next notch, the traversing of the table is stopped. The disengagement of the plunger 87 from its notch also supplies power to limit switches 15LS, 16LS, 17LS which are actuated by dogs on the table 23. Switch 15LS is actuated when the table starts to move and operates valves V16, V19. Valve V19 causes the piston 82 to withdraw the pin 83 from one of the holes 85, and valve V16 operates cylinder 18 to raise the camming element 41 into the path of crank-pin #2 to position the crank-pin which runs along the arm 42 and roller 46. A timer then causes the piston 82 to be moved to engage the pin 83 with the next hole 85 to angularly position the crank-pin #2 coaxial with the workheads. The timer also causes the camming element 41 to be retracted. When plunger 87 engages the next notch, a limitswitch 10LS actuated on timer 1TR to initiate the next grinding operation. Where adjacent crank-pins, such as #3, #4, are coaxial, the notch associated with one of the crank-pins has a plunger 111 which, when actuated by the plunger 87, operates a timer 2TR to .effect bypassing of the angular indexing operation. After successive grinding operations and the grinding of crank-pin #1, plunger 87 is withdrawn from the last notch and a dog 139 on table 23 trips a valve 65a so that when valve V25 is actuated, the fluid supply moves the table in a reverse direction, plunger 87 being held in its retracted position. A solenoid S1 is also de-energized to lower the follower 122 on to the cam surface so that when the follower engages the notch 121, the pot chucks are correctly positioned for loading and unloading, which may be effected automatically, and motor M3 is stopped. Valve V5 is then actuated to reverse the supply to the cylinders 39a, 39b to move the jaws 37 to the unloading position. The table, meanwhile, continues to move to the right until a dog 138 engages lever 137 to cause valves V65a, V22 to move the table to the left until plunger 87 engages the notch 89 for grinding crank-pin #6 of a new workpiece. U.S.A. Specifications 24,S85 Re issue and 2,813,380 also are referred to.