GB303196A - Improvements in or relating to the method of hardening metal surfaces - Google Patents

Abstract

303,196. Shorter, A. E., Boucher, C. L., and Patent Gear Hardening Co., Ltd. Sept. 29, 1927. Hardening.-In a method and apparatus for hardening the surfaces of the teeth of spur wheels in which the teeth are at angle to the longitudinal axis of the wheel, the teeth of bevel and worm wheels, helices, cams, shafts, and articles of cylindrical, angular, or irregular cross-section, the surfaces are heated locally to the required temperature for hardening and then quenched immediately, relative movement being effected mechanically between the heating and quenching devices and the article to maintain the surface of the latter parallel to, and at a uniform distance from, the heating &c. devices, and a cooling medium being applied to prevent distortion. In the form of apparatus shown in Fig. 1, which may also be used for the hardening of plain spur wheels, a tank 1 in which the spur wheel A to be treated is mounted is filled with water, the level of which is adjusted by means of an adjustable weir 2. The wheel A is supported on a screwed shaft 18 by conical plates 21 slidably mounted thereon, the shaft 18 being supported on open-topped bearings 17<a> on trunnions 17 which are supported in bearings on yokes 15 carried by shafts 14 adjustably mounted on standards 9 secured to a base 10 mounted on a turn-table 11 in the tank 1. By this means the gear wheel can be mounted at any angle so that the tooth to be treated may be mounted at any angle so that it is parallel to the path of the blowpipe. The blowpipe 7 and the quenching pipes 8 are adjustably mounted on a pivot 33 carried by a bracket 34 integral with or secured to a slide 23 which is vertically adjustable on the front end of a slide 25 adjustably mounted on a slide 28. The slide 28 is reciprocated parallel to the surface of the tooth to be treated by a screw-threaded shaft 40 mounted in a frame 41 and driven from the shaft 43 of a motor 42 by a worm 44 engaging a worm wheel 45 on a shaft 46 longitudinally slidable in bearings in a housing 47. Secured on the shaft 46 is a large friction disc 48, which is held in contact by a spring 49 with a small disc slidable on, but rotatably secured to, a shaft 51 mounted in bearings on the slide 28. To the lower end of the shaft 51 is secured a worm 52 which engages a worm wheel 53A on the shaft 40. The slide 28 is coupled to the shaft 40 by a nut 53 which forms part of a lever 54 pivoted at 55 to a slide 28, and which is normally held out of engagement therewith by a spring 56. The nut 53 is moved into contact with the rod 40 by a handle 57 secured to the lever 54 and may be locked in position by an arm 58 provided with a slot 59 having an enlarged portion to receive the enlarged end 61 of a rod 62 slidable in slots in the sides of the slide 28. The rod 62 is held in position by a spring 63 interposed between the wall of the slide 28 and a collar 64. To limit the movement of the slide 28 an abutment screw 65 is adjustably mounted on the frame 41 in alignment with the rod 62. When the slide 28 reaches the end of its movement and the nut 53 is disengaged from the screw 40, the slide may be returned to its initial position by a handle 68 or automatically by a weight 69 connected to the slide 28 by a chain 70 passing over a pulley 71. Means may also be provided for automatically cutting off the supply of gas to the blowpipe 7. The next tooth is then brought into position for treatment by a pawl 92 on the end of a rod 93 connected by a screw 94 to a block 95 pivoted at 96 in the forked end of a lever 97 slidable on, but rotatable with, a spindle 98 mounted in bearings on the tank 1 and connected to a slotted lever 99 to which is adjustably secured the end of a rod 101. The other end of the rod is engaged by a cam which is mounted on a rod secured to the slide 28. When the wheel has been moved to the required distance a spring 109 mounted between a bearing 108 and a collar 110 on the rod 101 returns the feeding mechanism to its original position. Supplementary quenching nozzles may be provided to direct streams of water across the other teeth to localise the heat of the blowpipe 7. For the treatment of wheels with herringbone teeth one of the yokes 15 is raised and the other lowered and the turntable 11 turned until one part of the tooth is parallel to the path of travel of the blowpipe 7. After treating the faces of one half of the teeth, the opposite yokes 15 are raised and lowered and the hardening completed. When treating the teeth of worm wheels, the blowpipe 7 &c. are mounted so that they follow the curve of the teeth. When treating the teeth of worms, the latter are mounted on a shaft so that during the treatment they are rotated continuously. When treating cams, the blowpipe &c. are fixed in position and the cam is rotated, the portion undergoing treatment being maintained at or adjacent to the level of the water in the tank 1. For hardening articles of cylindrical, angular, or irregular cross-section, the blowpipe and quenching pipes are of annular shape so that the whole of the part of the surface under treatment is heated and quenched. Specification 227,296 is referred to.