GB847719A - Improvements in lapping machines - Google Patents

Abstract

847,719. Lapping valve seats. DEWRANCE & CO. Ltd. May 21, 1959 [May 21, 1958], No. 16289/58. Class 60. In a portable machine for lapping a flat valve seating, for example the seating of a safety valve or stop valve, a support member carrying a rotary member provided with driving means is adapted to be secured to the valve. body at an opening thereof opposite the seating with the axis of rotation of the rotary member normal to the plane of the seating. a fluid pressure device having cylinder and piston elements is adapted to urge a lapping tool mounted on one of the elements against the seating and the other of the said elements is mounted eccentrically on a spindle itself eccentrically rotatably mounted on and extending parallel to the axis of rotation of the rotary member and provided with means whereby the spindle may be secured to the rotary member at selected angular positions to give different eccentric movement to the lapping tool The flat angular valve seat 3 is lapped by a circular disc 6 having on its lower face grooves to retain lapping paste. A screw 44 passing through a central aperture in the disc engages a threaded hole in a rod 41. The contacting surfaces of the rod 41 and disc 6 are part spherical. The aperture in the disc is of greater diameter than the screw and the disc is not clamped tightly by the head of the screw. The rod 41 has screwthreaded engagements with a boss 39 on a piston 36 working in a cylinder 30. The cylinder is secured to the lower end of a spindle 28 and is eccentric thereto. The spindle 28 is mounted eccentrically in a sleeve 20. After a nut 32 has been loosened, the spindle 28 can be rotatably adjusted in the sleeve 20 so as to alter the eccentricity of the cylinder 30 relative to.the sleeve 20. A pointer 33 secured to the spindle 28 co-operates with a scale on a top cap 23 of the sleeve 20. The sleeve 20 is rotatably mounted by bushes 12, 16 in a tubular member 9 secured to a plate 8 and in register with a central aperture therein. The plate has slots 10 to receive bolts 11 by which it is secured to the valve body - 1. A worm wheel 25 keyed to the sleeve 20 meshes with a worm 61 rotatably mounted in a casing 62 attached to the tubular member 9, the worm having at one end a rectangular slot 63 to receive a driving key held in the chuck of a hand-operated electric or pneumatic drill. Compressed air from a bottle 60 passes through a valve 59, flexible pipe 58 and banjo coupling 49 to a bore 28<SP>1</SP> in the spindle 28 and thence to the space in the cylinder 30 above the piston 36. Pressure can be relieved, after closing the valve 59, by operating a valve 67.