GB655190A - Planetary rolling mill - Google Patents

Abstract

655,190. Rolling. TRIGGS, W. W. (Sendzimir, T.). July 14, 1948, No. 18897. [Classes 83 (ii) and 83 (iv)] Making strip; working at specified temperatures.- Strip is rolled from a flat slab with a single heavy pass reduction in a planetary mill with means for forcing the slab into the mill in opposition to the back pressure produced at the entering side. There may be means such as a two high finishing pass or a coiler on the exit side to apply tension to the issuing strip. The operation develops sufficient heat to maintain fully or even to increase the rolling temperature, e.g. 1550‹ F., so that lower initial temperatures may be used such as from 1200‹ to 1500‹ F., and trouble from scaling avoided, resulting in clean strip that does not need pickling before subsequent cold reduction. For exceptionally clean strip, the whole reducing zone is surrounded by a protective atmosphere. The slab 1, Fig. 1, may be fed by a direct acting hydraulic ram 2 through a guide 4, that prevents upsetting, to a planetary mill comprising sets of reducing rolls 7, 8 that come together in pairs as they roll round driven backing-up rolls 5. The ends of the rolls 7, 8 are mounted in elongated holes in retaining rings geared together through external idlers. A brake 51a at the entry side ensures that the roll necks are at the rear sides of their respective holes before contacting the slabs so that forward movement as required by the elongation of the metal is permitted. The emerging strip 11 is quenched by liquid, gaseous, or mixed spray from nozzles 15, 16 before coiling at 17. In another mill, slabs 51, Fig. 2, with bevelled ends are connected together by electric, gas, or thermo-aluminic welding at 28, may be raised to rolling temperature by electric heating at 102. Heavy feed rollers 24, 26 force the billet into the mill through guides 130, 132 which may also supply heat, as by highfrequency electric heating. The planetary mill 6 is enclosed at 34 for immersion in cooling oil insulated at 36, 35a and the strip may pass direct to finishing rolls 44 with backing rolls 48 solidly supported by a heavy housing 42 and this pass may also be immersed in oil. The winder 17 as well as the rolls 44 may apply tension to the strip. The slabs may be fed by a reciprocating gripper device having steel gripping shoes arranged for water cooling and fitted with slab-engaging pads of heat resisting material. These pads are mounted on the shoes by an intermediate stainless steel bar transversely perforated to retard heat conduction or by a number of transversely arranged stainless steel tubes welded or otherwise tacked together. In a modification, a ceramic intermediate member or one made from stainless steel particles coming from a wet grinding machine is used. The planetary mill may be arranged vertically to facilitate shedding dirt and scale. The backing rolls 5, Fig. 9, are arranged horizontally side by side and are geared together through intermediate shafts 164 by gears 166, 167, Fig. 8. The retaining rings 6d for the planetary rolls 8 are similarly driven by gears 162 and in one construction to secure proper phase adjustment of these rolls the gear 167 is mounted on its shaft by a helical spline 169 and is adjustable laterally at 170. To vary the pass the necks of the backing rolls are supported by eccentric bushes 155 adjustable by racks 160. Instead of employing plain finishing rolls to remove the minute scallops formed by the successive pairs of planetary rolls, the backing rolls may have a series of minute, spaced, longitudinally extending flats to prevent the formation of the scallops. In another mill the planetary rolls are backed up by intermediate rolls having alternately arranged portions of large and small diameter, the small parts acting as bearings in grooves formed in the main backing rolls. The housings support the planetary rolls over their full width by segmental eccentric bushings, separately adjustable and the feed rollers may be similarly adjustably backed up. In a further modification designed to prevent the formation of scallops, the planetary rolls 8b, Fig. 13, are caused to follow a straight path between the positions 501, 502 and are backed up by rings 92 loose on eccentric parts of non-rotating spindles 91 mounted in bearings round the main rolls 60. Arms 94 on the spindles carry rollers 95 that engage a cam track at the operative position, the step 96 causing the spindles to rock to produce the straight path. The spindles are returned to their original position by centrifugal force. By arranging a large bite for the initial pair of rolls to engage the slab and by locally preheating the surface at this point, the surface skin may be separated from the body of the slab and thrown back as a fin, thus eliminating a subsequent scarfing operation. When this is done a clean strip of another metal may be fed into the mill with the main slab to produce compound or cased strip. A wide range of temperature control is obtainable according to the design and operation of the mill, thus with a high mill speed and slow rate of feed the initial temperature may be as high as 1800‹ F. with exit temperature only 800‹ F. Specification 478,360 is referred to.