GB657129A - Grinding and lapping machines - Google Patents

Abstract

657,129. Grinding. HARTRIDGE, L. Sept. 30, 1948, No. 25547. [Class 60] A machine for grinding a coned point on a lap or the like having a cylindrical body comprises a displacable member for feeding the lap or the like to a grinding wheel and carrying a lap holder in rotarily adjustable manner, said lap holder including a V-guide for engagement with the lap body and a stop plate extending perpendicularly to the lap so as to give end location to the lap while the cone is being ground, means being provided for urging the point of the lap directly on to said stop during grinding and simultaneously rotating it. A machine for grinding a lap 13, to be used for lapping the valve or pintle seats in injection nozzles for compression ignition engines, or for grinding a needle of such nozzle has a bottom slide 1, mounted on a saddle 3 fixed to the bad plate 4; the slide is adjustable forwardly and rearwardly by a feed screw 5, the operating knob 7 of which has graduations 8 cooperating with a zero mark 9 on the slide. The bottom slide 1 carries a top slide 2 adjustable lengthwise by a feed screw. A plate 10, pivotally mounted on the top plate 2a of the slide 2, carries a lap holder 11 and means 12 for rotating the lap 13 in the holder. Plate 10 pivots on a bolt 14 secured to top plate 2#a and is clamped in adjusted position by screw 15, projecting upwards from the top plate 2a through slot 16 in plate 10, and locking nut 17. Finger screws 18, mounted on pillars 19, upstanding from the top plate 2#a bear against opposite sides of the plate 10. The end of the plate remote from the pivot is arcuate and bevelled and has graduations 21 co-operating with an index mark. A dial gauge 23 mounted on the top plate 2a has its feeler 22 in contact with one side of plate 10. The lap holder 11 comprises a block 25, on the upper face of the plate 10, having a V-groove 26 in one. side and laterally slotted at 27 for the reception of a hollow jaw 28 carried by a rod 30 passing through a bearing hole 31 in the block 25 and terminating in a head 32 between which and the block is a loading spring 33. A stop 36 on the block 25 locates the lap axially. The block is removably attached to the plate 10 by bolt 37 and locating pins 38 to enable the complete holder to be exchanged for another adapted to take laps of a different range of sizes and/or type. The means for rotating the lap comprises a shaft 39, supported by a bracket 40 mounted on the plate 10, positioned substantially in alignment with a lap in the holder 11. The outer end of the shaft has a rotating-handle 41 and the inner end is connected by a universal joint 43 to a chuck 42 comprising a sleeve 44 and a shaft 45; a pin 46 passes diametrally through the sleeve and through a lengthwise slot 47 in the shaft, so that the sleeve can slide on the shaft but cannot rotate relatively thereto. A spring 49 surrounding the shaft 45 is positioned between one end of the sleeve 44 and an adjustable collar 48 on the shaft 45. The other end of the sleeve has a cross pin 50 which engages a flat 51 on a shank 52 attached to the carrier of the lap. The spring 49 yielding presses the tip of the lap against the stop 36, the pressure being preset by adjustment of collar 48. A fine-grade grinding wheel 55 is directly driven by an electric motor 56 mounted on a block 57 rigid with the bed 4; the wheel has a guard 58 mounted on the bed. The motor also drives, through a gear box, a chuck 59 to receive the shank 52 when it is desired to lap a valve seat. The block 25 has a holder 60 carrying a diamond 61 for trueing the grinding wheel, the diamond being traversed across the periphery of the wheel for this purpose by means of the feed screw. The machine is made either as a bench fitting, or on legs, or cubicle, and has mounted on the top plate an adjustable electric lamp to illuminate the lap and grinding wheel.