GB509266A - Improvements in or relating to the surface hardening of metal articles such as the teeth of gear wheels, sprocket wheels or other toothed members - Google Patents

Abstract

509,266. Surface-hardening metal articles. SHORTER PROCESS CO., Ltd., and SHORTER, A. E. Jan. 14, 1938, Nos. 1346 and 10786. [Class 72] [Also in Group XI] A method of surface-hardening a profiled surface of an article, such as a gear or sprocketwheel, comprising a plurality of substantially part-circular details whose centres of curvature are all substantially equidistant from a common centre, comprises mounting the article about an axis extending through this common centre, rotating one of the details about the axis through its centre of curvature so as to present successive portions of its surface to the action of a high-temperature heat source, and then rotating the article about the common centre to bring another detail into position for treatment. Where the details depart somewhat from a true circular curvature the heat source may be slightly angularly adjusted during the treatment to maintain the direction of application of the heat normal to the surface, and the distance between the surface and the heat source may be maintained constant by relative movement of the detail and the heat source. In the apparatus shown, the article 13 to be treated, shown as a gear-wheel, is rotatably mounted at 18 on a carriage which is traversed on a diametral slide 10 mounted on a turntable 11 so as to bring the centre of curvature of one of the details or teeth 14 into the axis of rotation 12 of the table. Rotation of the wheel about the axis 18 is prevented by a spring- controlled detent 19 which engages between two of the teeth. A burner 16 and associated quenching jet 17 is then adjusted in relation to the. tooth, and the turntable is rotated either by a hand wheel 25 or by a motor to present. the convex profile of the tooth progressively to the jet and quenching device, after which the detent 19 is released and the wheel turned to bring the adjacent tooth into position. Concave depressions on a wheel periphery may be similarly treated. The motor drive for the turntable operates through a change-speed gear of the friction disc type, controlled by a hand wheel 53, a worm drive and a clutch which may be disengaged by depression of a pedal when the manual drive is to be used. The burner-supporting means comprises a vertical pillar 55 on which is a vertically-adjustable bracket 57 in which a horizontal arm 56 is pivoted so that it may be swung in a horizontal plane. A carriage 60 may be locked in adjusted position along the arm 56 and carries a horizontal bar 64 to which a fine adjustment in an axial direction may be given by a hand wheel 66. The burner 16 is carried by a bracket 62 rotatably mounted on a vertical rod 63 carried by the bar 64, and may be adjusted vertically by a fine-adjustment member 65. In treating details not of truly circular curvature, the direction of application of the heat may be maintained normal to the surface by rotation of the bracket 62 about the rod 63 either manually, or automatically by means of a template arranged above or below the detail and engaged by a roller carried by a member secured to the bracket. Consequential adjustment of the distance between the heating unit and the surface may be effected by the hand wheel 66 or the shaft 15. The burner is fed by flexible conduits 67 carried over a guide pulley 68, and one or more quenching nozzles may be provided alongside it and supplied by a flexible conduit. A trough 21 collects the cooling medium and may discharge to a sump 23, from which the medium may be returned to the quenching nozzles by a pump. A number of heating units may be employed one above the other for surfaces too wide to be treated by a single burner. An electric heater of the induction or resistance type may replace the burner. Mechanism may be provided to stop the motor and cut off the heating medium when a detail has been treated, and to cut off the heating-medium whilst traversing parts of the surface which are not to be hardened. The apparatus may be constructed so that the article being hardened is rotated about a horizontal or inclined axis.