Patent GB-641395-A (GB)
Title: Improved die polishing or lapping machine
IPC: B24B5/48
Filed: 1948-04-16
Abstract: 641,395. Lapping or polishing dies. KNELLER (INSTRUMENTS & TOOLS), Ltd., and HARDY, N. S. April 16, 1948, No. 10595. [Class 60] A die polishing machine of the type comprising spaced wire holders 7, 8, Fig. 1, for holding taut wires between them, rotary work heads 2a, 2b for the reception of the dies, and means for effecting relative reciprocation between the wire holders and the work heads, has automatic means gradually to shift the rubbing zone along the wire first in one direction and then in the reverse direction. The ends of the wires are held by clamping plates 4a, 5a and 4b, 5b ; scales also being provided to facilitate positioning of the ends of the wires. The holders 7, 8 are attached to a reciprocable member 3 connected by a screw 41 with an arm 40 reciprocated by a crank 46, Fig. 3, and a crosshead 44. The crankshaft 48 is driven through gearing 33 and a pulley 32 from a motor 13. The screw 41 carries a ratchet wheel 49 with square teeth which are partly covered by a bluff 58, Fig. 6, provided with a slot to allow engagement of the ratchet wheel by one of two pawls 52, 53. These pawls are pivoted on a pendulous member 51 which has a projection to co-operate with a spring-pressed detent (not shown) so that it can be held in an inclined position to one side or the other of the vertical in order to render one pawl or the other inoperative. The member 51 also has a pin 62 which lies between two vertical pins 60, 61 on the bluff so that the recess in the latter is always brought beneath the operative pawl by the movement of the member 5. Each time the member 3 reaches the top of its stroke, the ratchet wheel 49 has a tooth engaged by the end of the pawl which is in the operative position. The end of the pawl then swings through an arcuate path about the pivot so that the ratchet wheel is rotated, angular displacement of the member 51 being prevented by the detent. The rotations of the ratchet wheel 49 cause the screw 41 to turn in its nut 42 which is secured to the member 3 until the latter has reached one of its extreme positions in which further rotation of the screw is prevented by one of two pairs of co-operating stops 65, 68 and 66, 69, Fig. 3. With either pair of these stops in engagement, the ratchet wheel cannot rotate and the resulting pressure on the operative pawl angularly displaces the member 51 against the detent to bring the other pawl into operative position so that the direction of the screw 41 is reversed. The dies are mounted in chucks 10a, Fig. 4, which are rotatably mounted in a casing 11a and driven by bolts 12a, 14 from the motor 13. The casing 11d is adjustably connected by a screw 25a with a spindle 19a clamped in a bracket 16a which is adjustable in horizontal guides 17a on the frame of the machine The axis of the die may thus be set at an angle to the wire. When it is necessary to polish a radius at one end of the dieaperture, the die is rocked into and out of the vertical. To accomplish this, a crank 26a on the spindle 19a is adjustably connected to a link 27a which is in turn adjustably connected to a lever 28a pivoted at 29a and provided at one end with a follower which is held in contact with a cam 31 by a spring 34. This mechanism is duplicated for the other die holder which is actuated from a lever 28b having a follower also held in contact with the cam 31 by the spring 34 at a diametrically opposite point to the follower on the lever 28a.