Patent GB-512225-A (GB)
Title: Improvements in and relating to grinding or abrading machines
IPC: B24B19/02
Filed: 1938-07-06
Abstract: 512,225. Grinding screw-threads. HORSTMANN, S. A., and HORSTMAN, Ltd. July 6, 1938, No. 669/39. Divided out of 500,726. [Class 60] In a screw-thread grinding machine the slide for the work-supporting parts or for the grinding- wheel head is in the form of a circular section bar which extends into a hydraulic cylinder to serve as a piston for causing or controlling the movements of the slide under the action of pressure fluid admitted to the cylinder. The machine comprises a base 100 on which is mounted a bed 101, rubber or resilient pads being, if required, inserted between the parts. The base carries an electric motor 102 driving a fluid pump 103 from which oil is led through a control valve to a fluid motor 105 serving to rotate the work and the lead screw. The head and tail stock carrying the work are mounted on the circular section bar 106, which is supported on the bed and, at the right-hand end, enters a cylinder 107. The left-hand end of the bar is bored out for connection to the lead screw 110, which is supported and driven as described in Specification 500,726. The lead screw is biassed, and backlash taken.up, by the fluid in the cylinder 107, supplied through a port 157; leakage of oil serves to lubricate the bar 106. The head stock 117 is clamped to the bar 106 and has a lug 119 engaging a bearing plate 12,1 resting on the bed 101, the lug having therein an adjusting screw 122a. The grinding- wheel 202 is mounted in a bracket 198 secured to a slide bar 189, of circular section, extending across the bed 101 and acted upon by pressure fluid in cylinders 190, 192 at the rear and front ends respectively, so that the bar may be moved to cause the wheel to approach, or recede from the work to an extent limited by screws 195, 194. The bracket 198 is provided with a bearing 199 receiving an extension 200 of the housing 201 for the wheel 202, the spindle 203 of which runs in bearings 204 in a sleeve 205 clamped in a tube 305 secured to the housing, the spindle being belt driven from an electric motor 264, which is mounted at its ends on rubber bushes in brackets 207 on the tube 305, a torque reaction rod 208 being provided. The housing 201 may be adjusted in the bearing 199, to suit the helix angle of the thread being ground, by a pin 217, engaging a slot 218 in a scale plate 219 on the tube 305 and carried by an arm on a shaft rotated through worm-gearing by a manually operable shaft. Reversing-mechanism for controlling movement of the wheel 202 comprises a hand lever 221 pivoted at 222 on the bed and engaging the plunger 224 of a reversing-valve 223 controlling admission of fluid to and exhaust from the cylinders 190, 192; or automatic reversal may be effected by dogs 237 mounted on a slide bar 235 and engaged by a member 236 on plate 121. The bar 235 engages, by means of a slot 501, a pin 500 on the lever 221, and positive movements of the valve are ensured by a spring snap device 502-507. For relieving taps, the headstock 117 is turned slightly with the bar 106 by means of pins in a ring secured to the shaft 131, the pins engaging an arm pivoted on the headstock and carrying an adjustable screw engaging the plate 121; alternatively, a cam plate may be driven by the work-rotating means to operate the screw to allow the grinding-wheel to advance. Tapered work may be ground by slight rotation of the tailstock on the bar 106. When a tap or other fluted work is to be ground means as described in Specification 500,726 may be employed; automatic feed of the grinding-wheel also may be provided, and cooling fluid may be supplied by a pump. Specification 492,591 also is referred to.