Patent GB-1075279-A (GB)
Title: A grinding machine
Inventor: LOCKWOOD GEORGE HENRY
IPC: B24B5/08
Filed: 1964-10-22
Abstract: 1,075,279. Grinding. HEALD MACHINE CO. Oct. 22, 1964, No. 43136/64. Heading B3D. A machine for grinding a surface of revolution comprises a rotatable workpiece table having a horizontal upper surface, a wheelhead having a spindle adjustable to a vertical position overlying the table, a feedscrew for moving the wheel-head horizontally relative to the table to effect the machining, a stepping motor operatively connected to the feedscrew and rotative in a small movement in response to the receipt of an electrical pulse from a generator, and means selectively adjustable to regulate the transmission of electrical pulses from the generator to the stepping motor. The work-table 21, Fig. 1, is beltdriven from an electric motor and mounted for rotation on a base 11 having a vertical mounting plate 12 for a vertically adjustable horizontal rail 13. A left saddle 14 and right saddle 16 are mounted for horizontal movement on the rail, each saddle carrying a wheelhead 15, 17 on which is mounted a housing 27 for a sleeve 28, the latter being reciprocatable in the housing and supporting a spindle for a grinding-wheel 29. The wheel-heads can be adjusted to vary the angles that the spindles make to the vertical. A further saddle 18 is mounted on the plate 12 and carries a grinding wheel-head having a horizontal axis. The spindles 61, Fig. 3, of the grinding wheels 29 are reciprocated by hydraulic motors 78 and the traverse of the saddles are effected by lead screws 62 which can be rotated continuously by a motor 65 connected by a screw 64 and nut 63 to the lead screw 62 or at a slow speed or stepwise to effect a feed at each end of the stroke of the spindle by a motor 67, the latter being driven by a sequencing and driving circuit 72 which is connected to a pulse generator and increment counter 71 and also drives a further stepping motor 69 operating a dial 46 which indicates the amount of feed of the saddle. The controls for each of the wheel-heads and saddles are carried in a box 26 suspended from the machine. The reciprocation of the grinding wheel spindles 61 is controlled by proximity switches 76 and 77 which feed into a transistorized amplifier in a reversing circuit 79 having a flip-flop relay system, separate timers being provided for controlling adjustable delays at the ends of the stroke of the grinding wheel. The circuit controls the reversing valves 84 for the motors 78, each valve being associated with an adjustable throttle valve 124 for controlling the speed of movement of the spindle. Each saddle can be moved at a rapid speed by the motor 65, at a slow speed by continuous operation of the motor 67, or incrementally by stepwise operation of the latter motor, the number of steps being set by an eight-position switch in a circuit having a counting section, sequencing section, pulse generator and motor driving unit. The counting section has three flip-flops connected to a binary counter which counts the pulses from the generator and stops the cycle when the number of pulses as set by the switch has been reached. The sequence section also has flipflops and a relay system to reverse the direction of the stepping motor 67. The motor driving unit has a pair of control relays which have contacts controlling power relays uesd to switch the polarity of the stepping motor 67 and other contacts for switching the polarity of the dial stepping motor 69. The machine is also equipped with meters 31 for indicating the speed of rotation of the grinding-wheel spindles, a meter indicating the speed of rotation of the work-table, a coolant supply controlled by a button on the box 26, and knobs for the operator to determine the amount of wear of the grinding wheels. An optical position indicator is provided on the saddles for accurately determining their position on the machine. A dresser is mounted on the feeding slides and a control is provided to compensate for dressing. As shown, a double, tapered-roller bearing 23 is mounted on the work-table but the machine, in addition to be able to grind internal surfaces, can also. grind external surfaces, shoulders, lips and faces and can be used for surfacegrinding.