Patent GB-831269-A (GB)
Title: A method and means for heat treating a toothed convex surface of an article by high frequency induction heating
Inventor: FROST LEONARD FRANK
IPC: H05B6/02
Filed: 1955-04-15
Abstract: 831,269. Induction heating. DELAPENA & SON Ltd. April 13, 1956 [April 15, 1955], No. 10961/55. Class 39(3) Apparatus for heating a toothed convex surface of an article includes a high frequency inductor, an indexing device for imparting a step-by-step rotary movement to the article, and an index correction element for bringing the side surface of a tooth into accurate register with the inductor. Inductor and mounting. An upstanding column 25 is slidably adjustable on horizontal guides 26 by a feed screw 27 and supports an element 29 adjustable vertically by screw means 31. A housing 32 on the element 29 contains an output transformer 33 of a high frequency generator and is pivoted about a bush 34, the housing being secured in any chosen angular position by clamping bolts 35. An inductor 11 projects horizontally towards a shaft 14 for receiving the article, e.g. gear wheel 12, to be treated. Indexing device. A horizontal rod 44 provided with a peg 51 is slidable in guides 45 fixed in a support 46 which may swing horizontally about a pivot 47. A bracket 48 carrying the pivot 47 is itself movable in a horizontal plane, being pivoted at 49 and adjustably secured by a clamping stud and nut 75. Index correction element. A tapered pin 36 is carried on a lever 37 pivoted towards its upper end in a bracket 39, horizontal displacement of the pin 36 relative to the inductor 11 to cope with curved tooth form of helical gear wheels being effected by pivotal adjustment of the bracket 39 on the housing 32. Mounting and clamping means for gearwheel &c. A vertical shaft 14 is rotatable in a boss 15 and may be moved vertically by means of a hydraulic cylinder 16. A spigot 24, interchangeable with .any one of a series of spigots of different diameters, is provided at the top of the shaft 14 to rotatably support the gearwheel 12. A drawbolt 70, extending coaxially within the shaft 14, is operable by a piston to clamp the gearwheel firmly on the spigot 24. Rotational movement of the shaft is necessary when a helical gearwheel is being treated and the combination of such movement with the vertical movement is effected by means 133, described in Specification 831,270. Operation. Assuming the shaft 14 has completed a downward or heating stroke, current to the inductor 11 is automatically discontinued, the shaft moves upwardly to its normal position, and the clamping means is released to allow the gearwheel to be rotated. Electrical and hydraulic means cause the peg 51 of the indexing rod 44 to move into engagement with a tooth space of the gearwheel which is then indexed, the peg then being disengaged from the tooth space and the pin 36 of the index correction element automatically engaging the tooth space through which the inductor is next to pass. Such engagement causes the gearwheel to turn slightly on the spigot 24 until the tooth space is in exact register with the pin 36 and with the inductor. The gearwheel is then clamped in position by operation of the drawbolt 70, both the indexing device and the 'index correction element being disengaged from the gearwheel. Hydraulic fluid is then admitted to the cylinder 16, the shaft 14 and the gearwheel being moved downwardly and current supplied to the inductor. The cycle is repeated for each tooth space. The core of the inductor may be as described in Specifications 714,488, 775,463 or 813,113. The current to the inductor may be varied by means described in Specification 827,958. Provision is made for quenching the heated portion of the gearwheel. Instead of the indexing device engaging the actual gearwheel, the device may be arranged to engage a dummy article attached to the shaft 14. The operating cycle of the apparatus may be effected automatically by a combination of electrical and hydraulic circuits. Pneumatic or electrical means may be substituted for the hydraulic operating means.