GB589928A - Improvements in or relating to rotary cutters - Google Patents

Abstract

589,928. Securing milling-cutters &c. on shafts. DEFIANCE MACHINE WORKS, Inc. March 8, 1945, No. 5740. Convention date, Oct 18, 1944. [Class 80 (ii)] [Also in Group XXII] Relates to cutters and boring heads having a shank for connection to the machine spindle and consists in mounting the cutter body for limited rotation on the shank with interposed resilient means for suppressing rotational vibration. Cutters 7, Fig. 3, are secured by screws to a circular body 6 flexibly mounted with limited rotation on a stub-shaft 11 provided with a tapershank 10 for attachment to the spindle of the machine. Radial arms 9, Fig. 2, transmit the drive to hydraulic buffers 8 secured to the body 6 wherein pistons 21, Fig. 4, are disposed either side of the arms 9 in cylinders with springs 24 and 25 placed between the pistons and the arms, and the pistons and the end-covers respectively, the arms projecting into the cylinders through slots permitting limited relative movement. The enclosed spaces housing springs 25 are connected by a channel 27 and the whole filled with a hydraulic fluid, an adjustable screw 28 regulating the flow of fluid displaced by movement of the pistons. The springs transmit the drive through to the body 6 whilst torsional vibrations set up by the cutters engaging the work are minimised by the hydraulic buffers. In a modification the springs 24 are dispensed with and projections on the back of the pistons abut the arms 9, the channel 27 being enlarged at one end to accommodate a check-valve, a secondary adjustable port connecting the channel 27 with the rear of the check-valve. This arrangement provides extra facilities for damping vibration. A further modification employs pistons with split skirts urged open by internal springs to damp out vibration by frictional contact between the pistons and cylinder walls, thus obviating the hydraulic system. In the Specification as open to inspection under Sect 91, two alternative methods of providing resilient driving and damping means to replace the radial arms and buffer system are also described. In one method, the stub-shaft and body each have a sleeve concentrically mounted with a rubber-like ring bonded to both sleeves. In the second method, the back face of the body is provided with a friction ring against which a brake-shoe splined to the stubshaft is pressed by a series of springs, a torsion spring between the body and the shaft securing the resilient drive. The subject-matter does not appear in the Specification as accepted.