GB536261A - Improvements in or relating to method of and apparatus for abrading - Google Patents

Abstract

536,261. Abrading-machines. MICROMATIC HONE CORPORATION. Nov. 7, 1939, No. 29570. Convention date, Nov. 18, 1938. [Class 60] Round holes enlarging and trueing.-A machine having a hone 11 or other abrading element is arranged to apply a light pressure between the hone and work at first, to prevent rapid wear of the stones, and then increase this pressure. If desired the pressure may be reduced again towards the end of the operation to produce a smoother finish. A hone or a number of hones 11 is carried by a head 12 by which the hones are introduced into the work. Each hone can be expanded by cones operated by a piston in the head 12, the operating fluid being controlled by a reversing valve 14 operated by a solenoid 15 and time switch 66 or a revolution counter &c. The fluid is supplied by a pump 17 and its pressure is regulated by an adjustable relief valve 21 to produce the desired maximum pressure by the hone. Any desired lower starting and finishing pressures are obtained by other relief valves 23, 27 which are connected to the pipe 18 at and for the times desired by valves 26, 29, solenoids, and time switches 67, 68 &c. In a modification the valve 14 is supplied with fluid under a gradually increasing and then a gradually decreasing pressure by a relief valve 33, Fig. 8, connected to a piston 79 with a passage 81 connecting its two faces. The chamber A, below this piston, is connected by a passage 78 to the fluid supplied by the pump to the valve 14 and that B, above it, is a two-way valve 75, Fig. 6, which connects it alternately to two bleed valves 84, 85 which are adjusted to give a greater and smaller flow respectively than the passage 81. The chamber 34 is connected to the fluid supply pipe 18 and, by a pipe 74, to the valve 14 and the chamber C to exhaust. When the cycle of operations is commenced the valve 85 is in use and the pressure on the valve 33 is at first equal to that of the spring 32 less that due to the fluid pressure on the lower face of the piston 79 which is the same as that in the pipe 18. Owing to the flow through 85 being less than that through 81 pressure on the upper face of the piston 79 increases and thus the pressure in the supply pipe 18 also increases to a maximum determined by the main relief valve 21. When the valve 75 is reversed by a time switch &c., the pressure on the upper face of the piston and in the pipe 18 falls gradually. Finally the time switch 66 opens the circuit to the valve 14 to retract the abrading elements.