Patent GB-620117-A (GB)
Title: Improvements in or relating to method of and apparatus for heat treatment of metal articles
IPC: H05B6/02
Filed: 1944-04-27
Abstract: 620,117. Heat-treatment. BUDD INDUCTION HEATING, Inc. April 27, 1944, Nos. 7892 and 7893. Convention dates, Feb. 24, 1943 and Aug. 21, 1943. [Class 72] In a method of heating an annular wall of a metallic workpiece having a variable thickness throughout at least portions of its length, an annular heating current is induced in the wall to a substantially uniform depth less than the thickness of the thinnest portion, simultaneously cooling the wall from the opposite surface, at least for a portion of the heating time, at a rate determined by the thickness of the wall such that the tendency of the wall to be heated through at the thinner section is counteracted to a greater extent than at the thicker section and the heating current is discontinued upon the hardening temperature being reached. As shown, applied to the treatment of the inner wall of a socket on a propellor hub, a work holder is mounted on a spider 21 secured at opposite sides to hollow cylinders 22 slidably mounted on guide rods 25 secured to a bracket 26 on a frame 20. Each rod 25 is provided with a piston 27, Fig. 4, which is moved in the cylinder by fluid from passages 31, 32 extending through the rods and connected by ports 28, 29, suitable valve mechanism being provided for delivering and exhausting fluid from the cylinders for raising and lowering the spider 21. A plate 33, supported in the spider 21 has a vertical flange 34 for supporting through bearing 35 a hollow shaft 36 of a rotary supporting member 37 to which is secured a work support comprising a base formed with a plurality of superimposed plates channelled to provide inlet passages for cooling liquid and outlets for heated quenching liquid after use. The support comprises a base 38 secured to the member 37 and an intermediate plate 39 having a hub 41 and an outer rim 42 secured to the plate 38, the upper part of which is channelled to provide radial fluid delivery passages 47 leading to a passage 49, Fig. 8, in the rim 42 and in turn leading to a port 51 in a tubular member 52 projecting through superimposed plates 43, 44 and provided with a port 53 communicating with an outlet passage 54 formed in the plate 43 for the discharge of quenching fluid from the member 52 &c. During the quenching operation, the port 53 is closed by a valve 55 slidably mounted in the lower end of the member 52 and having a head 56 which is subjected to the pressure of fluid entering through a port 57 connecting the passage 47 with the end of the member 52. When the port 53 is closed by the head 56, a port 58 in the part 52 registers with the port 51 thus allowing fluid to flow up through the part 52. The inner end of each channel 47 communicates through a port 61 with the interior of the hollow shaft 36 to which fluid is supplied by a supply pipe 62 connected to a central tube 68. The channels 47 alternate with similar radial channels leading to passages 72, Fig. 5, formed in the rim 42, the ends of the channels opening through ports 74 into an opening 75 which is in the hub of the plate 39, and which communicates with the interior of the tube 68 and is connected to a fluid supply line 76. A work-enclosing hood 77 is mounted on a spider 78 carried on rods 79 which extend through the spider 21 into fluid-containing cylinders 81, Fig. 1, by means of which the hood 81 is raised or lowered. The hood is rotatably supported on the spider 78 by a hanger 84, Fig. 4, mounted in roller bearings 85 through which oil is circulated from a chamber 86 by a pump 88. Like the base 38, the top of the hood 77 is formed by a plurality of channels and rings to form passages for quenching fluid to the outer face of a work piece enclosed in the hood and is formed by a top plate 91 secured to the end of the hanger 84 and having secured round an opening 92 a ring 93 which co-operates with a second ring 94 to form a quenching nozzle 95 to project fluid on to the outer edge or shoulder of a blade socket 96 of a propeller hub 97. The ring 94 also forms with another ring 98 a second quenching nozzle 99 for delivering fluid to an intermediate portion of the outer face of the part 96 and is mounted on and secured to an annular plate 107 bolted to a lower plate 102 whose edge is secured to the periphery of the plate 91. Quenching fluid is conducted to the nozzle 95 from tubes 105 by ports 104 and a passage 103 and when the hood 77 is in position, as shown in Fig. 5. the lower end of each tube. 105 fits over the upper end of the corresponding tube 73. Fluid is also supplied to the nozzle 99 from a passage 106 communicating through ports 107 with an annular passage connected by radial passages 109 to ports 111 communicating with tubes 112 which, as shown, fit over the corresponding tubes 52. A work holder comprises a standard 45 secured to the base 44 and provided with a spindle 114. Fig. 10, eccentrically mounted at one end in a bushing 115 having opposed slots 116 adapted to co-operate with a key 117 so that it can be secured in one of two positions in a collar 118, a work supporting sleeve 119, Fig. 5, in a recess in which an adaptor ring 123 is secured, being held on the spindle 114 by a key 121 and nut 122. The hub 97 is held in position in the sleeve 119 and. ring 123 by a bevelled clamping disc 124 which engages the bevelled edge of the hub bore. This disc is secured to a shaft 125 rotatably mounted on an arm 126 slidably and rotatably supported on a hollow shaft 127 projecting outwardly from a bracket 128, a hand wheel 129 being also mounted on the disc. The edge of the shaft 125 adjacent the disc 124 is recessed to receive the projecting end of the spindle 114, a pin 131 mounted in a recess in the shaft 125 engaging a bayonet slot 132 in the latter, and a detent 133 is provided to hold the shaft in its proper position. The lower end of the arm 126 below the shaft 127 is provided with feet 134 to engage surfaces 135 when the arm is in its operative position. To release a work piece, the wheel 129 is rotated to unlock the pin 131 and bayonet slot connection permitting the arm 126 and the shaft 127 to be moved bodily to the left to withdraw the disc 124 from engagement with the base of the hub 97 and thus removing the feet 134 from engagement with the surfaces 135 so that the arm 126 can be tilted about the shaft 127 to the position shown in dotted lines, Fig. 4, where it can be held by a rod 136 engaging a stop 137. To locate the hub on the spindle 114 and for moving the hub between operations for treating different blade sockets 96, a pin 139 is mounted on a plate 138 secured to the sleeve 119 and engages one of the bolt openings 141 in the hub, the plate being held in position by a pin 142 which engages an opening 143 in the plate 17 and is slidably mounted so that it can be withdrawn by a lever 144 pivoted to the pedestal 45 and connected at its lower end to a spring-controlled shaft 145 slidably mounted in a bearing 146 and extending forwardly of the shaft 127. In operation the work-holder and support together with the hood 77 and quenching nozzles are rotated by a motor 148 and gears 149 mounted on the shaft 36 and the gears also driving a pump 151 circulating lubricant from the reservoir 152 through a tube 153 and passage 154 to the bearing 35 and through a passage 155 to the gearing connecting the motor 148 and gearing 149. The heating of the inner part of the upper blade socket 97 of the hub 96 is effected by a water-cooled conductor 161 provided with a central quenching tube 197 perforated at its lower'end and mounted on a shaft so that-after the desired heating of the socket 97 has been effected the inductor is raised leaving - the tube 197 in position to effect the quenching of the heated part of the hub. Specification 548,970 is referred to.