Patent GB-722022-A (GB)
Title: Improvements in machine tools
IPC: B24B47/06
Filed: 1951-10-23
Abstract: 722,022. Grinding. JONES & SHIPMAN, Ltd., A. A., and HOULDSWORTH, J. Oct. 21, 1952 [Oct. 23, 1951]. No.24725/51. Class 60. [Also in Group XXIX]. The reciprocating work and tool carriers 1, 2 Fig. 1, of a hydraulically operated machine tool, e.g. a cylindrical grinding machine, move successively in a continuous cycle; the movements may be at right angles to one another so as to perform the machining operation shown in Fig. 2, or the movements may be at some other predetermined angle. The slide I is moved by a piston 3 in a cylinder 36, under the control of a reversing valve 9 which is operated by a relay valve 6. A throttle valve 10 in the exhaust line of valve 9 controls the speed of slide 1. An adjustable screw 4 associated with the slide 1 co-operates with a pivoted lever 5 connected with the relay valve 6. The slide 2 is moved by a piston 19 in a cylinder 51, under the control of a reversing valve 20 which is operated by a relay valve 18. A throttle valve 26 in the exhaust' line of valve 20 controls the speed of slide 2. An adjustable screw. 16 carried by the slide 2 co-operates with a bell crank lever 17 and a further lever 52 connected to relay valve 18. An initiator motor is connected in parallel with the motor 3, 36 and comprises a piston 21 having an annular groove 40 engaged by an adjustably loaded ball 22. The piston 21 has secured thereto a pivotable arm 41 having at its outer end a catch nose or claw 23 co-operating with an abutment element 24 connected to relay valve 18. When piston 21 moves to the left the relay valve 18 is moved to operate valve 20, and during this travel an inclined edge 48 on the catch arm 41 rides up a fixed stop 25 thus disengaging the catch arm from abutment 24; during return movement of the catch nose the face 49 of the claw rides over a chamfered surface 50 of the abutment 24 thus allowing restoration of the catch 49 to the abutment side of element 24. An initiator motor 11 connected in parallel with the motor 19, 51 similarly operates the relay valve 6.  With the parts in the position shown, the piston 3 moves from left to right. When the piston 3 reaches its right hand position, the pressure difference on the ends of initiator motor 21 increases sufficiently to overcome the loading of ball 22. The piston 21 is thus shifted to the left and the catch 23 shifts the relay valve 18 to the left until the claw 23 is disengaged by peg 25. The lever 52 moves clockwise, and the reversing valve 20 shifts to the left. The piston 19 moves upwards. Consequent upon the shifting of the reversing valve 20, pressure passes to the right hand end of the initiator motor 11 and shifts the piston 11 into the left hand position where it is retained by engagement of the ball in the groove. When the piston 19 reaches its topmost position, screw 16 contacts lever 17, operating lever 52 and shifting relay valve 18 to the right, the catch nose 23 being still out of engagement. The reversing valve 20 shifts to the right, and piston 19 moves downwards. When piston 19 reaches its lowermost position, piston 11 shifts to the right, thus shifting relay valve 6 to the right and consequently shifting reversing valve 9 to the left. The piston 3 moves to the left, and the piston 21 of the initiator motor moves to the right. When the piston 3 reaches its left hand position, screw 4 contacts lever 5 to shift relay valve 6 to the left consequently shifting reversing valve 9 to the right. This completes the cycle of operations which has followed the pattern indicated in Fig. 2, in which the horizontal arrows represent movement of the work 27 with the tool 28 stationary, while the vertical arrows represent travel of the tool 28 with the work stationary. In a modification, Fig. 3, the relay valve for the reversing valve 9 comprises valve heads 72, 73 on the piston of the initiator 21. The piston 21 has two annular grooves 40, 69 engageable by the loaded ball 22. A cam 62 on the piston 21 moves in a slot 74 in the cylinder and co-operates with a roller 63 on one arm of a pivoted bell crank 64 the other arm of which carries a pivoted pawl 50 loaded by a spring 75 and co-operating with stop 25 and abutment 24. Opposite slot 74 in the initiator cylinder is an aperture 76 for the passage of the nose of a detent bell crank lever 60 pivoted at 77 on the cylinder and having at its opposite spring-loaded end a pointed nose 47 coacting with the nose of a pawl piece 13. The latter has a cam formation 78 co-operating with a peg 15; the piece 13 is pivoted on a lug 79 secured to the piston of initiator 11 and is spring urged. When the piston 3 reaches the right hand end of its cylinder, the pressure rise shifts initiator piston 21 towards the right, the ball 22 leaving the groove 69. When the piston 21 has moved halfway to the right, roller 63 rides up the cam piece 62 on the piston and detent lever 60 drops into slot 61 on the piston thus retaining the piston in halfway position; the conduits leading to reversing valve 9 are closed, no effect being produced on valve 9, so that piston 3 remains held in its right hand position. The movement of roller 63 actuates bell crank 64 carrying pawl arm 50 which moves to the right so that a bevelled shoulder 80 thereon takes with it the relay valve 18 by means of the detent 24. At the end of the stroke of arm 64, pawl arm 59 is sufficiently depressed by pin 25 for shoulder 80 on arm 50 to drop out of contact with the detent 24. Movement of the relay valve 18 to the right causes shift of the reversing valve 20 to the right; piston 19 moves upwardly, and initiator piston 11 is shifted to the right, taking with it the pawl piece 13 which overrides and engages the detent nose 47. Reversal of the piston 19 at the end of its upward movement is effected by the screw 16. When the piston 19 reaches the lower end of its travel, the build up in pressure shifts piston 11 to the left, taking with it the pawl piece 13 engaging the nose 47. This disengages the detent 60 from the slot 61 and allows the initiator piston 21 to complete its stroke to the right, whereupon the reversing valve 9 shifts to the left, and consequently the piston 3 moves to the left. The roller 63 moves down the face of the cam 62 causing the arm 64 to move to the left; the initiator piston is now set for repeating its action in a reverse direction which occurs when the piston 3 reaches the left hand end of its cylinder. The above cycle of operations produces the pattern shown in Fig. 4, the tool 58 machining the work 57 through two right angles. Specification 360,635, [Group XXIX], is referred to.