Patent GB-659939-A (GB)
Title: Improvements in profile grinding or polishing machines
IPC: B24B17/08
Filed: 1949-04-12
Abstract: 659,939. Grinding and polishing. RANSOMES, SIMS & JEFFERIES, Ltd., DYER, F. T., and REVETT, R. H. April 12, 1949, No. 9-901. [Class 60] A machine for grinding or polishing mould boards 35 of plough bodies and other articles of varying contour comprises a power - driven grinding wheel 1 which is so mounted that it can rise and fall during operation on the article being ground or polished, a work table 34 supporting the article, and means for reciprocating the work table relatively to the grinding wheel, feeding it in directions inclined to the directions of reciprocation, and imparting rising and falling movements to it during the grinding operation so as to effect mutual rising and falling movements of the article and grinding wheel with the latter normal to the surface being ground. The spindle 2, Figs. 1 and 3, of the grinding wheel 1 is rotatable in a housing 3 pivoted at 4 on the upper end of a slide E which is adjustable vertically on a column 8 under the control of hand-operated worm, screw and nut mechanism 9, 13, 14. The spindle 2 is driven from a motor 19 on the housing 3 through belts 17 and pulleys; the motor is counterbalanced by weights 21, 22 on a rod 23, the weight 22 being slidable along the rod by means of a screw-threaded shaft 22<SP>1</SP> in order to vary the downward pressure of the wheel 1. The wheel 1 is lifted from the work by supplying pressure fluid to an hydraulic cylinder 26 which is pivoted to the machine base 65 and has its piston rod 31 connected to the housing 3; the wheel is lowered on to the work by connecting the cylinder 26 to exhaust, and a second similarly-disposed hydraulic cylinder then acts as a dash-pot to cushion the oscillations of the wheel. The work table 34 is pivoted at 36 on brackets 37 carried by a traversing table 38 which reciprocates on slides 39 and rollers 40 on a feed carriage 41 movable in a direction normal to the path of the table 38 on slides 66 on the base 65. In order that the grinding wheel may be maintained normal to the varying contour of the article 35 the table 34 is arranged to be tilted during traverse by means of two hydraulic cylinders 47 pivoted on the brackets 37. Spring-urged piston rods 51 in the cylinders are each pivoted at 53 to a lever 55 carried by a rotatably-mounted shaft 59 and also to links 54 which are pivotally connected to a lever 57 fixed on the relevant pivot 36. The shaft 59 carries a follower roll 61 co-operating with an inclined cam plate 63 on a fixed base 64. The cam plate 63 determines the degree of tilt of the table under the action of the cylinders 47. The reciprocation of the table 38 is effected by a double-acting hydraulic cylinder 42, Fig. 1, which is clamped to the feed carriage 41 and has its piston rod 44 connected to the table. The feed carriage 41 is advanced and retracted by a feed screw 67, Fig. 3, mounted in the machine base 65 and engagaing a nut on the carriage. The feed screw 67 may be operated manually by a wheel 69 or automatically through gearing 70, 71, an intermediate shaft 72, and further gearing from a motordriven gear box 80, Figs. 1 and 3. According to which of two clutches in the gear; box is made effective by manually operating a push rod 103 to the right or left, the feed carriage may be advanced at slow feed rate or withdrawn at quick return speed; in the neutral position of the rod 103, the gear box is ineffective and the carriage can then be fed by the hand wheel 69. During a grinding operation the table 38 is constantly reciprocated and the feed carriage 41 is fed forward so that successive and adjacent bands on the article are ground by the action of the grinding wheel. The hydraulic cylinders 26, 42, 47 are included in a circuit as shown in Fig. 24 including a fluid-distributing pump 187, a rotary plug valve 109 which can be set so as to connect the cylinder 26 either to pressure fluid and thereby raise the grinding wheel or to exhaust whereby the grinding wheel descends to operative position, and a rotary plug valve 123 controlling the supply of ressure fluid to the cylinder 42 through an automatic reversing valve 148 for reciprocating the table 38. The reversing valve 148 is in the form of a rotary plug valve controlling the supply of pressure fluid from the valve 123 to opposite ends of the cylinder 42 and also the exhaust from the latter to a throttle valve which may be adjusted by hand to control the speed of reciprocation of the table. The valve 148 is rocked between its two positions for reciprocating the table by lever mechanism actuated by two solenoids which are energized alternately by the closure of switches 208, 209, Fig. 3, on the cam table 64 by stops 213, 214 on the traversing table 38. The circuit to the tilting cylinders 47 includes a pressure-reducing valve 194, Fig. 24, and an automatic relief valve 177 which permits the supply of pressure fluid to the cylinders for the upward tilting of the work table 34 and its exhaust therefrom to provide for the downward tilt. The valves 109, 123 are operable by handles 111. 124, Fig. 19, and inter-engaging cams 132, 133 fixed on the shafts of the valves ensure that, when the valve 109 is operated tc lower the grinding wheel, the valve 123 is opened to cause reciprocation of the table 28, and, when the valve 123 is operated to stop the reciprocation of the table, valve 109 is opened to elevate the grinding wheel. The hydraulic circuit also includes a relief valve 192 and a cooling coil 195 on the exhaust pipe 157. When the feed carriage 41 has completed its full predetermined feed movement, a tappet 143, Fig. 19, on the carriage engages an adjustable stop 342 on' a push-rod 134 which is mounted slidably adjacent the valves 109, 123 in a position normally determined by springs 138 and has a tooth 139 for alternate engagement with two spaced teeth on a rocker 142<SP>1</SP> on the shaft of the valve 123. The rod 134 then moves with the carriage until a collar 142 on the rod engages with a collar 146 on the clutch rod 103 and causes the latter to halt the drive of the feed carriage 41; at the same time, the tooth 139 moves the valve 123 to stop the reciprocation of the table 38 and the valve 109 to lift the grinding wheel from the work. By suitable operation of the push rod 103 the carriage 41 is then returned by the quick-return drive until the tappet 143 strikes an adjustable stop 346 on the rod 103 and thereby operates the latter to stop the drive. The valves 109, 123 are similarly operated to raise the grinding wheel and stop the table 3 should the latter make a stroke of undue length and the switch 208 or 209 fail to be operated by the corresponding stop 213 or 214. In this case, a switch 252 mounted between the switches 208, 209 is then closed by the corresponding stop so as to energize a solenoid 254, Fig. 19, which acts through a chain 144 upon the rod 134; this movement of the rod also moves the clutch rod 103 to neutral position and stops the drive to the feed carriage. In addition, the closure of the switch 252 is caused to break the circuit to the motor 19 driving the grinding wheel. The mould board 35 is mounted on the work table 34 on the rabbeted parts of end brackets 263, 264, Fig. 32, and a central bracket 265, being secured in position by a clamping member 268 on a chain 269 which passes under a sprocket 270 and is connected to the piston rod of a compressed air or hydraulic motor 270'. If the mould boards have a concave form the grinding wheel may have a convex grinding surface.