Patent GB-514300-A (GB)
Title: Method of and apparatus for cutting
IPC: B24B27/06
Filed: 1938-03-31
Abstract: 514,300. Severing by abrading; sawing. JACKSON, L. MELLERSH-. (American Chain & Cable Co., Inc.). March 31, 1938, No. 9898. [Classes 60 and 145 (ii)] In cutting by feeding a rotating cutting disc through the work the disc is given a bodily oscillatory movement across the work at right angles to the direction of feed, thus reducing the arc of contact between the disc and the work and so reducing the resistance and the power required. In the machine shown, for cutting bars by this method, a cutting disc 25, preferably of abrasive material, is carried on a spindle in the end of an arm 18 pivoted at 16 to another arm 15 which is in turn pivoted at 14 to the machine base; the pivot 14 is placed directly beneath the work-holding devices, so that movement of the arm 15 about this pivot produces substantially horizontal movement of the disc 25 across the work. The disc 25 is rotated by belt gearing, enclosed in a cover 38, from the shaft 34 of an electric motor 29 which has its base pivoted at 27 to an extension 20 of the arm 18 and adjustably secured at 33 to another extension 32 of the arm 18, so that the tension of the belt can be adjusted. The arm 18 is rocked about its pivot 16 by the piston-rod 43 of a hydraulic cylinder 40 pivoted to the arm 15. The arm 15 is supported by a counterbalance spring 107, and may be oscillated about its pivot 14 by a link 74 connected to an adjustable crank-pin 72 on a gearwheel 69 driven by a second electric motor, which also drives a rotary pump 65 to supply hydraulic pressure for the cylinder 40 and a cylinder 57 actuating the work clamps. The work 53 is held on a V-block 39 by two rods 47 having downwardly pointing ends engaging the work close to the sides of the disc 25; the rods 47 are adjustably attached to the piston-rod of the cylinder 57. The cylinders 40, 57 are controlled by a rotary valve 115 having four positions; in the first or normal position the arm 18 and the clamps 47 are raised, in the second the arm 18 is raised while the clamps are free, pressure fluid being cut off from both ends of the cylinder 57; in the third the clamps are lowered to hold the work, the arms 18 remaining raised; and in the fourth position the arm 18 is lowered to carry the cutting disc 25 through the work, the clamps remaining in the holding position. The pressure of the fluid supplied to the cylinders 40, 57 is regulated by relief valves; pressure gauges may be provided. The speed at which the arm 18 can descend is limited by an adjustable outlet valve on the outer end of the cylinder 40 to a value slightly in excess of that at which the disc 25 can cut through the work, so that the disc is not suddenly brought against the work and the disc cannot descend outside the sides of the work or into the hollow of a tube being cut. The valve 115 is actuated by a shaft 135, spring-biassed to the normal position, having a handle 170 with a notched hub 176 engaged by a detent 168 on a spring-biassed spindle 162 to hold the valve in its various positions; a spring-release member 174 is operable to force the detent 168 out of engagement with the hub 176 when required. In order to reduce the time between successive cutting operations, the movement of the arm 18 may be automatically reversed as soon as the cutting disc 25 has passed through the work by a rod 188, adjustably fixed to the arm 18, engaging a sliding rod 164 to press down an arm 163 on the spindle 162, thus releasing the detent 168 to allow the valve 115 to be moved back by its spring from the fourth to the third position; the arm 18 also carries an adjustable stop member 186 which engages a lug 185 on the arm 15 to stop the upward movement of the disc 25 when it is just clear of the work. The clamps are held just clear of the work, instead of being fully raised, by bringing the valve 115 from the first to the second position at the appropriate time. The cutting disc is enclosed in a housing 13 formed with an arcuate slot for the passage of the cutting disc spindle, closed by a cover carried on the arm 18, a large inspection opening on the opposite side with a hinged door 94, and an opening for the work 53 closed by a screen 99 which fits in guides in the housing and has an opening slightly larger than the work and a rubber member fitting closely round the work; interchangeable screens 99 are used according to the size of the work. The housing contains a chamber 77 for cooling liquid, formed with a slot in which the disc 25 works; the liquid falls from the disc and work through a screen into a reservoir in the lower part of the machine, whence it is returned to the chamber 77 by a motor-driven pump. The work may be positioned in the machine by a stop screw 200 carried on an arm on a bar 197 which is slidably adjustable in a member 196 on a shaft 193 operable by a lever 195 to swing the stop away from the work. The cutting disc 25, Fig. 18, is formed with a series of holes as shown, so arranged that as the disc wears there is always a notch at one point of its periphery to clear dirt and pick up cooling liquid.