GB563919A - Improvements in or relating to the flame treatment of the internal surfaces of bores - Google Patents

Abstract

563,919. Heat treating internal surfaces of bores. SHORTER PROCESS CO., Ltd., and SHORTER, A. E. May 13, 1943, No. 7625. [Class 72] In the heat treating of the internal surfaces of bores, heating flames are directed longitudinally into the bore from opposite ends so that the flames meet intermediate the ends, and are mutually deflected laterally to impinge upon the surface to be heated. For bars where the rate of heat conduction from any given circumferentially extending zone is uniform, the flames are arranged to meet at a point or annular zone which is substantially equidistant from the surrounding surface zone to be heated and for bores in which the rate of heat conduction is not uniform in the circumferential direction the flames are arranged so that the distance between the surface and the zone where the flames meet is a minimum in the region of maximum conductivity. Relative rotation between the'bores and the flame about the longitudinal axis of the bore may be effected to effect uniform heating of the surface in the circumferential direction and a relative oscillatory movement axially of the bore between the. latter and the flames to effect uniform heating in the longitudinal direction. For the treatment of ferrous metal articles, the temperature of the surface is raised rapidly at least to the critical point and the surface is then quenched. The work W having a bore, the surface S of which is to be hardened, is mounted in a jig 10 secured to a slide 11 carried by a bed 12 supported in a base-plate 13. The slide 11 is coupled to a spring 14 which when released moves the plate 11 from the position shown in Fig. 1 where the bore is in position between the nozzles N of the burners B to another position abutting against slopes 15 where the bore is between quenching nozzles Q, both the burners and the nozzles Q being mounted on brackets 22. The slide 11 is prevented from moving under the action of the spring by a detent 16, Fig. 2, which is urged into a recess 17 on the underside of the slide 11 by means of a spring 18 and is coupled through a pin 19 to the plunger 20 of a solenoid 21 adapted to be energized periodically by a current under the control of a timing device. In operation, the work W is mounted on the jig with the slide 11 held by the detent 16, as shown in Fig. 1. The burners B are turned on so that the flames issuing from the nozzles N enter the bore and meet centrally so that they are deflected laterally to impinge against the surface S. When the latter has attained the critical temperature, the solenoid 21 is energized to withdraw the detent 16 from the recess'17 and the slide 11 is propelled by the spring 14 until it abuts against the stops 15 in alignment with the quenching nozzles Q from which liquid is ejected centrally into the bore. On completion of the quenching operation, the work W is replaced by the next article to be treated and the slide 11 is retracted by a handle 23 secured to one arm of a bell-crank lever 24, Fig. 3, mounted on a pivot 25 journalled in a bearing 26 carried by a bracket, 27, supported on the base-plate 13. The other arm of the lever 24 is provided with a slot 28 engaged by a pin 29 projecting from the slide 11. The turning on and off the gaseous fuel to the burners and of the quenching medium to the nozzles Q may be effected by solenoid-operated valves which, like the solenoid 21, are controlled by a timing mechanism operated through relays from a master switch. In the treatment of larger bores, the work is mounted on rollers so that it can be rotated and simultaneously it is reciprocated so as to effect a uniform heating in both the circumferential and longitudinal directions. Combined burner-quenching units BQ, Fig. 6, are used, in which a ring of burners N are mounted round the circumference of a circular plate surrounding a plate 66 through openings in which the quenching fluid is delivered from a chamber 70 supplied with fluid through a pipe 71. The nozzles N are connected through passages 67, 68 to a gas inlet 69.