GB637882A - Improvements in abrading machines - Google Patents

Abstract

637,882. Grinding lenses. AMERICAN OPTICAL CO. Aug. 7, 1947, No. 21558. Convention date, March 27, 1939. [Class 60] A lens-grinding machine comprises rotary spindles 4, 66, Fig. 1, for mounting the work 54 and a ring-shaped abrading tool 58, means for adjusting the relative angular relation of the tool and work according to the curve to be generated on the work and maintaining the two spindles in corresponding relative positions, and means for moving one spindle towards the other and controlling the extent of material removed from the work. The spindle 66 which, as shown, carries the tool is journalled in a head 2 pivotally mounted on the frame of the machine by a pin 3, Fig. VI, a vernier scale 88 being provided to show the extent of adjustment which is affected by a worm and toothedsector mechanism. The pin 3 is embraced by a split bearing which is clamped by a screw to hold the head in adjusted position. The spindle 4, which carries an adaptor to which the work is secured, has a splined connection with a pulley driven by an electric motor 49 and can be raised or lowered by a rack and pinion connected to a handle 177. A weight attached to the pinion spindle by means of a cord wrapped around a cam-shaped surface holds the spindle in its raised position. The spindle 66 is provided with a pulley, the position of which on the spindle can be adjusted axially by means of a nut to compensate for wear of the tool. This pulley is driven by a belt from a pulley 98 driven by a flexible shaft from the motor 49. The tool is fed with oil through a bore in the spindle 66 and is provided with a vent 216, Fig. XII, to relieve excess pressure. The tool is of bonded abrasive sweated or otherwise secured to a metal hub, and its shape is determined by the proportion of convex to concave surfaces to be ground, thus obviating localized wear. The tool is set to the correct position by aligning it with a mark 218, Fig. I, on the head 2. The means for controlling the removal of material from the work is illustrated in Fig. X, and consists of an axially-displaceable plunger 156 which is raised with the spindle 4 until it is engaged by an adjustable stop 150 whereupon it is depressed to cause a switch 162 to open, breaking the power supply. The stop 150 is provided with a scale to show its axial displacement, and is set to the desired position by means of two pins 138 and 144. These two pins are connected by a cam and link mechanism so that when the pin 138 is placed between the work and tool the pin 144 is placed between the plunger 156 and the stop 150. When the pins are withdrawn, the stop 150 is displaced by the amount it is desired to remove from the work. In order to prevent the machine from being started with the pins in operative position, movement of the pin 144 opens a safety switch. The front of the machine is closed by a sliding door and an indicator is provided to show the relationship between the angular setting of the head and the curve produced on the work.