Patent GB-712580-A (GB)
Title: Apparatus for automatically charging and discharging rotary hearth furnaces
IPC: C21D9/00
Filed: 1952-09-30
Abstract: 712,580. Rotary hearth furnaces ; charging and discharging. TALLEY, R. E. Sept. 30, 1952, No. 24451/52. Class 51 (2). [Also in Group XXXVII] In a rotary hearth furnace, intended particularly for heating steel billets prior to piercing and rolling into seamless tubing, wherein billets of different sizes are handled together, movements of the hearth, a charging machine and a discharging machine are co-ordinated by an adjustable sequence controller and an electric timer, so that the hearth moves forward in steps of one size for loading and steps of a different size for unloading, while the charger functions in proper sequence with the loading movement of the hearth and the discharger in proper sequence with the unloading movement. The rotary hearth is mounted on idler rollers 12 and is driven by a motor S through gearing coupled to diametrically opposed bevel pinions 10 engaging a bevel gear It attached to the underside of the hearth, side idler rollers 15 being provided engaging a track 17 on the inner circumference of the hearth. The lower part of the furnace walls are formed of wedgeshaped tiles 23 supported on wedge-shaped castings 24, both of which can be removed while the furnace is working and dependent flanges 21 engage waterfilled troughs formed on the peripheries of the hearth. The clearance gaps 22 between the side walls and the hearth may be adjusted by screw jacks 25 built into the foot supports of the buckstays. The charging machine, Fig. 5, comprises a wheel mounted carriage 26 running on radially disposed rails 27 and driven by a motor 28 through rack and pinion gearing 30, 31, and a manipulating arm 32 formed with clamping jaws 32a, 32b and slung from the carriage 26 in vertically movable manner by an arrangement of bell cranks 33 and slidable collars 34 actuated by a hydraulic cylinder 39 through a connecting rod 37. The clamping jaw 32a is fixed and the hydraulically operated jaw 32b is slidably mounted on the arm 32, adjustment of the jaw opening to suit varying lengths of billets being obtained by means of a motor driven screw 43 rotatably mounted on the arm 32. The discharging machine, Fig. 7, is identical with the charging machine, its carriage 49 running on radially disposed rails 50. Spacing of the ingots on the hearth is controlled by the manually adjustable sequence controller 4, Fig. 6, which co-operates with an electric time clock and associated control circuits (see Group XXXVII) to automatically control the rate of discharge of the billets and the correct sequence of the various movements performed in the operation of the furnace. The adjustable sequence controller 4, shown in detail in Fig. 2, comprises cam cylinders 73 and 74 with their respective spring-loaded pawls 75 and 76 adjustably mounted in a steel housing 72 on shafts 87 and 89, the cylinder 73 controlling the hearth spacing of billets being charged and cylinder 74 controlling the hearth position for discharging. Each cam cylinder comprises notched cam discs at 73a, 73b &c. and 74a, 74b &c. the notches being spaced to provide a suitable range of hearth spacings. The cam cylinder 73 is driven through gearing and a flexible coupling 83 from the slow speed shaft of a speed reducer 9 incorporated in the hearth drive, and the engagement of identical gear wheels on the cylinders 73 and 74 cause them to rotate in opposite directions at equal speeds. Normally closed switches, Fig. 4 (not shown), mounted on the housing 72 are in operative engagement with levers secured to the pawl shafts 87 and 89, said switches being opened to stop the hearth rotation when one or both pawls fall into their respective notches. Each hearth station may be a charging station, a discharging station, or both depending on the spacing of the billets, and re-starting of the hearth is initiated automatically by the aforementioned electrical control means by movement of the charging machine in the first instance and by movement of the discharging machine in the two latter instances.