Patent GB-256582-A (GB)
IPC: B24B49/18
Filed: 1926-06-24
Abstract: 256,582. Heald Machine Co., (Assignees of Guild, TV. J.). Aug. 7, 1925, [Convention date]. Round holes, enlarging and trueing; trueing rotating tools.-In a machine for grinding internal surfaces and other work, the cross feeding mechanism is arranged so that when the work reaches a predetermined size the stroke of the reciprocating grinding-wheel carriage is amplified to carry the wheel past a trueing-device, the normal stroke then being resumed until, when the work is to size, the stroke is again amplified to carry the wheel clear of the work to allow of removal &c. The machine comprises a reciprocating carriage 1 carrying a grinding-wheel head 2, the work 6 being rotatably carried by a head 3. The slide 1 is reciprocated by hydraulic or other means, and reversal at the ends of its strokes is effected by dogs 7, 8 carried by blocks 80. 79 on the slide, the dogs operating a reversing lever 9. The wheel head 2 consists of a cross slide 11 movable on a bracket 13 carried on the slide 1, the slide 11 being moved to feed the wheel into the work by a screw 14. The screw may be rotated by hand through reduction gearing 24 - - 27, the gears 24, 25 of which are carried by a pin 23 mounted in a drive ring 22 to which a hand wheel 28 may be coupled by a screw 31. Mounted on the ring 22 is a dial ring 32 having connected thereto a ratchet ring 34 operated by a pawl 38, which is carried by a lever 37 pivoted at 36 on the bracket 13 and operated at each reciprocation by a cam 40, the step-by-step rotation of the ring 32 being communicated to the ring 22 by a ratchet drive 42, 43, which allows of the ring 32 being turned anti-clockwise by hand. The ring 34 carries a cam 44, which, in the clockwise or wheel-feeding direction of rotation, engages successively two adjustable screws 45, 49 carried by levers 46, 50, the lever 46 when rocked closing contact 47, 48 and thus closing the circuit of a magnet 65, through a switch 62, the normal position of which is shown in Fig. 10. The armature of this magnet when attracted lifts a lever 70 into the path of a latch 84 pivoted to a block 81, thereby permitting the block 79 carrying the dog 8, when it contacts with the lever 9, to move relatively to the slide 1 until it contacts with the block 81, when the lever 9 is thrown over. The slide thus makes an extended stroke to the right and returns, and during these strokes the wheel is trued by a diamond 53 which is moved into the path of the wheel by movement of a valve 77 by an arm 76 of the lever 70. On the outward stroke of the slide the switch 62 is thrown over by an arm 94 pivoted at 85 to the block 81, which prevents a repetition of the amplified stroke. The normal stroke of the slide is then resumed until the cam 44 causes the lever 50 to close contacts 51, 52, whereby the circuit of a magnet 97 is closed, thus lifting a lever the arm 103 of which lifts the pivoted dog 8 and allows the slide to make an extended movement to the right, withdrawing the wheel from the finished work. In order to set the cross feed mechanism to operate as described above, a workpiece is made to exact size by manual operation of the machine, the ring 32 being set manually to operate the lever 50 with the final setting of the feed by hand; this position is indicated by a pointer and graduations on the ring 32. The parts are then set to give the wheel dressing operation at the desired point, and this is accomplished by rotating the handwheel 28 anticlockwise the required amount, the screw 31 being tightened and the rotation communicated to the ring 32 and cam 44 by ratchet teeth 112 on the ring and a pawl 113 in the handwheel, this action also retracting the slide 11 the required amount; the diamond is then adjusted just to make contact with the grinding-whoel. In order to compensate for the wear and dressing of the wheel during grinding of each piece of work, the cam 44 must be set back during manual retraction of the slide 11 after a piece of work has been ground. This is accomplished by means of an adjustable screw 116, Fig. 2, carried by a block 115 on the handwheel 28, one end of the screw being adapted to contact with a lug 119 on the ring 22 and the block being adapted to contact with a lug 118 on the ring 22. Thus when the wheel 28 is turned anticlockwise, the wheel and ring 32 with cam 44 move until the block contacts with the lug 118, when the ring is driven and the slide 11 retracted; before commencement of the next operation the wheel 28 is turned freely clockwise, the ratchet 112 allowing of this, until the screw 116 contacts with the lug 119. In a modified form of cross feed mechanism, Fig. 7, an annular member 121 is provided having a hub 122 carrying the stud 23 for the reducing gear, and secured to the member 121 is a ratchet wheel 123 which co-operates with the pawl 38. The cam 44 is carried by a ring 124 rotatably mounted on the member 121, the ring having on its opposite sides teeth 125, 126 which co-operate respectively with pawls 127, 128 carried by the member 121 and a ring 129. The ring 129 is mounted on the member 121 and is frictionally constrained by pads or shoes acting on its periphery, wear of the wheel being allowed for by lost motion between screws in the ring 129 and a post carried by the ring 121. Specification 257,670 is referred to.