Patent GB-671290-A (GB)
Title: Surface grinder for mill housings and the like
IPC: B24B7/22
Filed: 1950-09-05
Abstract: 671,290. Grinding. LUKENS STEEL CO. Sept. 5, 1950 [Sept. 16, 1949], No. 21825/50. Class 60. [Also in Group XXIV] A surface grinder assembly for mill housings and like workpieces comprises a frame member, a carriage carrying a grinding wheel and adapted to reciprocate on the frame member, a feed screw journalled in the frame member, a nut on the carriage in threaded engagement with the feed screw whereby the carriage is reciprocated on the frame, a platform on the frame, means mounted on the platform for driving the feed screw, means connected, between the driving means and the feed screw for instantaneously reversing the direction of rotation of the feed screw, and a pair of limit switches on the frame for actuating the reversing means. A mill housing 15 comprises a pair of upright pillar sections 15a, 15b, a base 15c and a connecting arch 15d; the inner opposed faces of pillars 15a, 15b are finished and must be held to close working tolerances. In refacing, the bearing surfaces of pillars 15a, 15b are built up with stainless steel to a point well beyond the finished dimensions. A grinder assembly 16 is then mounted on a pair of vertical ways 18, 19 detachably secured to the housing and another grinder assembly 17 is mounted on a pair of similar vertical ways. The grinder assembly comprises an electric or pneumatic grinder 86, provided with a grinding wheel 88 and carried by a grinder bracket 82 adjustable horizontally in a slide 53 adjustable vertically on a carriage 51 which reciprocates horizontally on a frame 22. The ways 18, 19 are detachably secured to the housing 15 by screws 21, and spacing collars 20. The frame 22 is welded at one end to gib 26 embracing the way 18 and having a retaining plate 27; the other end of frame 22 is slidably guided on way 19 by a gib plate 30 having a T-slot fitting over frame 22, rollers 32 engaging the way 19 and a retaining plate 33. Raising and lowering of the frame 22 on the ways 18, 19 is facilitated by counterweights 44 carried by cables 48 attached to frame 22 and passing over pulleys 50. The frame 22 has on its front face flanges 22a, 22b on which the carriage 51 is reciprocated horizontally by feed screw 23 journalled in end plates 24, 25 of the frame 22, and co-operating with a nut 90 secured to the carriage. The front face of carriage 51 has a T-slot 52 receiving flanges 53a on slide 53 movable vertically relative to the carriage 51 by a screw 54, journalled in the carriage 51, co-operating with half-nut 69 slidably mounted in slide 53 and urged into operative position by spring 76, a handle 70 serving to retract the half-nut to permit complete removal of the slide from the carriage 51 to permit reversal of its position on the carriage. The screw 54 is driven through gearing 57, 58, 66, 64 by slotted or splined shaft 59 journalled in frame 22 and operated by hand crank 63. The bottom of slide 53 has a guideway 80 with a horizontal T-slot receiving the flanges 81 of grinder bracket 82 adjustable by threaded wing nut 83 lockable by spring loaded dog 84. The bracket is made in two parts 82a, 82b secured together by screws 85. An electric or pneumatic grinder 86 clamped in bracket 82 by caps 87 has a grinding wheel 88. The frame 22 is provided at one end with platform 44 on which is mounted electric motor 95 driving through chain 97 a jackshaft 96, one end of which drives pulley 101 and the other end of which drives a reverse gear box 102 causing shaft 103 and pulley 104 thereon to rotate oppositely to shaft 96. A shaft 105, which drives the feed screw 23 through chain 108, extends longitudinally through a pressure-tight cylinder housing 111. A pulley 114 mounted on one end of shaft 105 by bearing 115 is driven through belt 116 by the pulley 101 on the jackshaft 96. A pulley 117 mounted on the other end of shaft 105 by bearing 118 is driven reversely through belt 119 by the pulley 104 on shaft 103. A clutch carrier 120 slidably keyed to shaft 105 has friction face 121 adapted to engage annular face 122 of pulley 114, and is spring-loaded by springs 123 abutting a backing plate 124 keyed to shaft 105. An annular thrust bearing 126 is mounted on shaft 105 between clutch carrier 120 and flanged collar 127 functioning as a piston in one end of housing 111 and carrying packing 128. A second clutch carrier 120' co-operates with the pulley 117. The interior of housing 111 is divided into two separate cylinders 130, 131, fluid connection to cylinder 130 being by passage 132 and conduit 133 and to cylinder 131 by passage 134 and conduit 135. When no pressure exists in either cylinder, the clutch carriers 120, 120<SP>1</SP> assume the neutral position; when pressure is supplied to cylinder 130, clutch carrier 120 is moved to the right so that shaft 105 is rotated forwardly; when pressure is supplied to cylinder 131, clutch carrier 120' is moved to the left so that shaft 105 is rotated reversely. The supply of fluid to the cylinders 130, 131 is controlled by valves 145, 148 actuated by a pivoted lever 140 operated by solenoids 150, 151 selectively energized by closing of limit switches 40, 41 carried by frame 22. When carriage 51 has reached the limit of horizontal travel, either bracket 152 or 153 engages contact arm 42 or 43 to close limit switch 40 or 41. Relays 160, 175 and holding circuits are provided.