Patent GB-847444-A (GB)
Title: "work handling and indexing mechanism for machine tools"
IPC: B24B5/35
Filed: 1959-01-15
Abstract: 847,444. Grinding. CINCINNATI MILLING MACHINE CO. Jan. 15, 1959 [March 6, 1958], No. 1498/59. Class 60. A workpiece handling and indexing mechanism, for use in a machine tool having at least two work stations for successive machining operations on two surfaces of a workpiece spaced a predetermined angle apart, has two workpiece holders for moving the workpiece into and out of said work stations respectively, a transfer station above said work stations, means to move said work holders in straight, spaced paths between said work stations and said transfer station, a member at said transfer station adopted to receive a workpiece and swing the workpiece between a first position aligned with the path of one of said workpiece holders to a second position aligned with the path of other of said workpiece holders and thereby index the workpiece through said predetermined angle, means at the first position to transfer a workpiece from one workpiece holder to said member, and means at the second position to transfer a workpiece from said member to the other workpiece holder. A centreless grinder has a wheelhead 23 sup. porting a spindle 24 carrying grinding wheels 25, 26, 27, 28. A lower slide 35 mounted on the base 21 carries a blade holder 36 and work handling mechanism 60. An upper slide 37 mounted on the lower slide 35 supports a regulating wheel housing 38 supporting a spindle 39 carrying regulating wheels 40, 41, 42, 43 aligned with the grinding wheels. Movement of the lower slide 35 relative to the base 21 and of the upper slide 37 relative to the lower slide 35 is provided by the unit 50. When the slide 37 is in retracted position it operates limit switch LS 15 mounted on the base 21. Trueing devices 30, 45 for the grinding and regulating wheels are provided. The workpieces W are cross-shaped joints with two pairs 55, 55 and 56, 56 of opposed trunnions, the pairs lying on perpendicular axes. The grinding wheels 27, 28 and regulating wheels 42, 43 constitute a work station S1 for simultaneously grinding the trunnions 55, 55 and grinding wheels 25, 26 and regulating wheels 40, 41 constitute a second work station 32 for simultaneously grinding the trunnions 56, 56. The blade holder receives a blade 57 having two pairs 58, 58 and 59, 59 of upstanding arms which support workpieces at stations S1, S2. The work handling mechanism 60 comprises a housing 61 mounted on the slide 35 and carrying a casing 62. A carriage 67 vertically slidable in the casing 62 has two depending fingers 68, 69 with notches 70, 71 and a central depending part 72 with opposed notches 73, 74 defining fingers 75, 76. Each notch has a shallow V-shaped base to cradle the trunnion of a workpiece. Fingers 68, 76 constitute work holder H1 corresponding to work station S1 and fingers 69, 75 constitute work holder H2 corresponding to work station S2. Guides 80 depend from the casing 62 inregistration with the fingers of the workholders to retain the trunnions thereon as the carriage 67 ascends. Guides 81 depend from the casing 62 in registration with these trunnions not supported by the fingers to check rotation of the workpiece and to guide it into the casing in proper orientation as the carriage ascends. The carriage 67 is moved vertically by a cylinder CF controlled by a valve VF operated by solenoids 265, 266. When either solenoid is energised to move the spool of the valve, the spool is retained in the position to which it has been moved, despite de-energization of the solenoid, by a spring- urged detent 290 engaging a collar 264 on the spool. A bracket 122 is connected to the carriage 67 by means extending through openings 120, 121 in the casing 62. When the carriage 67 is in its upper position a screw 309 (not shown), on the bracket 122 operates a limit switch LS5 on the top of casing 62. When the carriage 67 is in its lower position a bolt 308 on the bracket 122 operates a limit switch LS13 on housing 61. The carriage 67 has an intermediate position determined by the engagement of a stop block 122c on the bracket 122 with a stop 240 when the latter has been moved into the path of the bracket. The stop 240 is moved by a cylinder CE controlled by a valve VE operated, against a spring, by a solenoid 150e. The upper end of cylinder CF for vertical movement of carriage 67 is connected to the valve VF through a deceleration valve 280 operated, against a spring, by a cam 122b on the bracket 122 so as to slow down the carriage 67 before it is arrested by the stop 240. When the stop 240 is retracted by cylinder CE to permit movement of the carriage 67 to its upper position lines 254, 255 are connected so that the valve 280 is ineffective. A limit switch LS10 on the top of cylinder CE is operated by a cam 122a on the bracket 122. At a transfer T the casing 62 has secured thereto casings 90, 93. The casing 93 carries a loading shoot 94. The casing 90 carries an ejection shoot 92 and houses a transfer plate 91. The plate 91. is triangular and is secured on shaft 100 journalled in casings 62, 90. A rectangular recess cut in one corner of'plate 91 receives blocks 95, 96 so as to form a pocket 110 to receive a workpiece. The block 96 has spring-loaded plungers 91d serving to hold a workpiece on the pocket. Holes 115 in the plate 91 register with the trunnion-receiving portions of the pocket. The plate 91 has an opening 111 extending therethrough which is shaped to correspond with the shape of a workpiece. The plate 91 swings, about the axis of shaft 100, between a lower position in which one side of the plate engages a stop screw 112<SP>1</SP> and on upper position in which another side of the plate engages a stop screw 113<SP>1</SP>, the stop screws being threadedly received in the casing 90. To effect swinging a pinion 104 on the shaft 100 meshes with a rack 105 carried by a rod 112 connected at its upper end to a dashpot CG. The rod 112 has spaced collars 113, 114. As the carriage 67 approaches its upper position bracket 122 engages collar 113 to swing plate 91 into its upper position; as the carriage approaches its lower position, bracket 122 engages collar 114 to swing plate 91 into its lower position if it has not already dropped under the action of gravity. A cylinder CA on axis A (the pivoted axis of plate 91) operates plunger 158 to push an unground workpiece from the loading shoot 94 into workpiece holder H1. The cylinder CA is controlled by a valve VA operated, against a spring, by a solenoid 150a. An escapement mechanism for release of workpieces one at a time to the bottom of loading shoot 94 comprises rods 162, 163 slidable in the shoot and having slots 162a, 163a engaging pins 160b, 160b on an arm 160 pivoted about pin 161. A roller 160a on arm 160 is received between collars 157a, 157b on the piston rod 157 of cylinder CA. Arm 160 has fingers 185, 186 operating a limit switch LS9. Limit switches LS6, LS7 mounted on brackets 320 secured to the casing 62 are operated, through pivoted arms 307, 306 G workpieces in the shoot. A cylinder CB on axis B (containing the centre of pocket 110 when plate 91 is in its lower position) operates plunger 195 to push a workpiece from the workholder H1 into the pocket 110 of plate 91. Cylinder CB is controlled by a valve VB operated, against a spring, by a solenoid 150b. Spaced collars 210, 211 on the piston rod 194 of the cylinder CB actuate limit switch LS 12. A cylinder CC operates arm 132 having four pins 134 spaced about axis C (containing the centre of pocket 110 when plate 91 is in its upper position) and projecting through openings in casing 90 and openings 115 in plate 91 to push a workpiece from the pocket 110 into the workpiece holder H2. Cylinder CC is controlled by a valve VC operated, against a spring, by a solenoid 150c. A rod 212 connected to the arm 132 has a slot 213 receiving the arm of limit switch LS8. A cylinder CD on axis D (containing the centre of opening 111 when plate 91 is in its lower position) operates plunger 217 to push a workpiece from the workpiece holder H2 through the opening 111 in plate 91 into the ejection shoot 92. Cylinder CD is controlled by a valve VD operated, against a spring, by a solenoid 150d. The piston rod 216 of the cylinder CD has a yoke 234 co-operating with spaced collars 231, 232 on a rod 280 having a slot 233 engaging the arm of limit swtch LS11. Cycle. The varions movements take place automatically under control of the limit switches. Assuming that the carriage 67 is in its upper position, the holders H1, H2 being empty and the pocket 110 of the plate 91, which is then in its upper position, containing a workpiece which has been ground at station S1. Cylinder CA pushes an unground workpiece from the loading shoot 94 into holder H1, cylinder CC pushes the workpiece from pocket 110 into holder H2, and stop 240 is retracted by cylinder CE. Cylinder CF moves the carriage 67 down into its lower position wherein holders H1, H2 are in association with stations S1, S2. The regulating wheel housing 38 is advanced by the unit 50 whereby grinding is effected. After an interval determined by timer 319 (not shown), unit 50 retracts regulating wheel housing 38 to discontinue grinding. Stop 240 is advanced by cylinder CE. Cylinder CF moves carriage 67 up to its intermediate position. Cylinder CB pushes the workpiece ground at station S1 from holder H1 into pocket 110 in plate 91 which is in its lower position and cylinder CD pushes the workpiece from holder H2 through the opening 111 in plate 91 into the ejection shoot 92. Cylinder CE retracts stop 240 and carriage 67 is moved by cylinder CF to its upper position, during which movement plate 91 is swung into its upper position.