US3182174A - Processing of metal - Google Patents

Description

y 4, 1965 R. B. SIMS PnbcEssING OF METAL 2 Sheets-Sheet 1 Filed July 16, 1962 INVENTOQ RAYMOND B. SIMS j Q- Wa May 4, 1965 R. B. slMs PROCESSING OF METAL 2 Sheets-Sheet 2 Filed July 16, 1962 IINVENTOQ' RAYMOND B. Sms

Hus ATTORNEY 3,182,174 PROCESSING OF METAL Raymond Bernard Sims, Sheffield, England, assignor to Davy and United Engineering Company Limited, Sheffield, Yorkshire, England Filed July 16, 1962, Ser. No. 210,029 Claims priority, application Great Britain, July 18, 1961, 25,974/61 8 Claims. (Cl. 219-401) This invention relates to the processing of metal and is particularly concerned with rod mills for rolling down billets, particularly of steel, to rod.

At present, a rod mill is supplied with individual billets which may, for example, range from 1%" to 3%" square and approximately 30' in length, from a reheat furnace and therefore operates semi-continuously in that the roll ing of each billet is done in a continuous operation, the metal passing continuously from stand to stand of the mill, but the process is discontinuous from billet to billet. Rod mills usually operate with two or more strands and may have over 25 stands through which the strands pass; the fact that the leading ends of the billets must be entered at high speed in each of the stands gives rise to a serious danger of cobbles occurring, with consequential loss of production time.

The danger of cobbles is reduced by welding billets end to end, before they enter the mill, so that the billets enter as a continuous stream. However, problems arise in the supply of billets to the mill and the control of their temperature and, as a consequence, no mill operating with welded billets has been built.

In accordance with the present invention, there is provided, for a rod mill, apparatus comprising the combination of a welding plant for welding together end to end a succession of billets to form one or more continuous billet streams, one or more post-weld furnaces through which the continuous billet streams pass to the mill and automatic control means for each furnace responsive to the temperature of the stream or streams passing therethrough and operative to compensate approximately for variations in temperature of the individual billets forming the billet stream or streams so that all streams enter the mill with approximately the same uniform temperature. By the use of the post-weld furnace, which is of course additional to the re-heat furnace, the billets enter the mill at approximately the same thermal condition, so as to ensure uniform rolling of the billets in the mill; without the provision of the furnace, there is the danger that certain billets will arrive at the rod mill at different temperatures, due to delays occurring between the time of leaving the re-heat furnace and the time of entering the mill, while the billets are travelling to and from the welding plant.

When Welded billets are employed, the gaps normally continuous mill comprising first and second .re' -heat furnaces, conveyor means whereby billets may be fed to United States Patent the first furnace or to one of the first and second furnaces, a Welding plant for welding together end to end a succession of billets to form one or more continuous billet streams and means associated with the first furnace'for directing billets from that furnace either direct to the mill stands or to the welding plant.

The invention will be more readily understood by way of example from the following description of rod mill plants in accordance therewith, reference being made to the accompanying drawings of which:

FIGURE 1 shows schematically the plant used for the conventional rolling of individual billets;

. FIGURE 2 shows the plant of FIGURE 1 adapted for forming a continuous billet stream, and

FIGURE 3 is a diagrammatic illustration on a furnace and its controls.

Describing first the equipment of FIGURE 1 for supplying billets individually to the mill, an unscrambler 12 loads billets on to a conveyor 13 which feeds the billets into the re-heat furnace 14. The heated billets are pushed out of the furnace 14 by the furnace pusher 15 on to pull out rolls 15a and enter the mill through a switch plate 16. The mill illustrated is intended to operate with four strands and the switch plate 16 directs successive billets into successive holes of the first stand 17 of the mill. Succeeding stands are illustrated at 13, although it will be appreciated that, in all, there may be as many as 25 stands, which for the sake of simplicity are not all illustrated in the drawing.

The furnace 14 is designed to meet the production capacity of the mill, when operating with individual billets. FIGURE 2 shows additional equipment arranged to supply the mill of FIGURE 1 with welded streams of billets. When welded streams of billets are employed, the production capacity of the mill is increased and, therefore, a second re-heat furnace 2% is provided on the side of the unscramblers 12 opposite to the furnace 14. Billets from unscrambler 12 are loaded alternately to the two furnaces 14, 21 by the conveyor 13 and the auxiliary conveyor 21, respectively. Furnace 2!) has its pusher 22 so that billets may be withdrawn from the furnace, while the furnace 14 is supplied with an auxiliary pusher 19 and pullout rolls 19a designed to feed the heated billets on to a further conveyor 23, which conveys them to a crossconveycr 24. The billets from both the furnaces 14, 26 therefore arrive at a single area 25 and are directed by a switch plate 26 successively to four mobile electric welding plants 27. Each Welding plant 27 is of known form and fuses the billets end to end by passing through them a very heavy electric current while the billets are forced together under a pressure of approximately 2 tons per square inch.

The billets emerge from the welding plants 27 as four continuous streams of welded billets and those streams then enter a post-weld furnace 28, which is located in the position of the original pusher 15, which together with pullout rolls 15a is removed when the mill is to be supplied with welded billets. This furnace, which is small in sectional area may also be located below the hearth of furnace 14, in order to simplify the engineering of the layout. As shown in FIGURE 3 the furnace 28 may be divided into individual compartments providing a separate furnace for each individual billet stream. Furnaces 28 are medium frequency induction furnaces, which are each provided with individual control equipment 29 to control the power suppliedto the furnace in response to signals from a pyrometer so located adjacent the stream of welded billet-sentering the furnace. Each pyrometer 36) is connected to its control equipment through an amplifier 31. When the billet streams leave the furnaces 28, which are only 30 to 40 feet long, the billets are all at the same uniform temperature. After leaving the furnaces 28, the billet streams pass either under furnace 14 or through that furnace to the first stand 17 of the rod mill.

It will be seen that the billets emerging from furnace 14 have a longer distance to travel to the area 25, than have the billets from furnace 20. As a consequence, the

billets from furnace Mare at a lower temperature than those from furnace'Zti. If the welded streams were to a pass immediately from the welding plants 27 to the mill,

certain billets will thus be at a lower temperature than the remainder and the rolled product will not be uniform in section. The furnaces 28 are designed to ensure that, regardless of the temperatures of the billets leaving the welding plants 27, the temperature of all billets entering the mill is approximately uniform, and it is for this reason that each furnace 28 is individually controlled by the temperatures of the individual billets entering that furnace.

Two of the billet streams are preferably made up en' tirely of billets arriving from furnace 14, while the other two streams are made up entirely of billets from furnace 20. The billets from furnace 14 being colder at the area 25 than the billets from furnace 2d, the induction furnaces 28 then are required to supply heat to the streams at a reasonably constant rate. In this case only two furnaces 28 are necessary, one for the billets from each furnace. On the other hand, if each stream is made up of billets derived from both the furnaces 14, 20, the furnaces maybe required to supply radically different.

amounts of heat for consecutive billets of the stream.

With the provision of the furnaces 28, the four. billet streams entering the first stand are at approximately the same uniform temperature, with the results that rolling in the mill is uniform for the four strands and adjustment of the stands is facilitated. It will be appreciated that should strand 2 for example be hotter than strand 3 it would be softer and it would be difficult to obtain uniform rolling since the adjustment would have to be made on the screwdown kit on either side of the mill. If either of the central strands was the coldest it would act as-a pivot point to vunbalance the rolling conditions of the two outer strands.

- ing accurately four diameters of the round section rod entering the finishing train may be used with a device measuring the rod speed to obtain an estimate of the weight of rod passing in unit time; a timing mechanism is then operated to control the shears so as to supply to the coilers lengths of rod having weights which are more accurately uniform than the previously described arrangement.

In accordance with the provisions of the patent statutes, 1 have explained the principle and operation of my invention and have illustrated and described'what I considcr to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described. 7 i

I claim:

1. A method of processing billets which comprises the steps of passing billets through one or other of two reheat furnaces, welding the billets together end to end to form continuous billet streams, billets from the same furnace being welded together in the same stream orstreams, passing each stream through an individual furnace and automatically controlling the heat supplied by each furnace to compensate approximately for variations in the temperature of the individual billets forming the billet stream passing therethrough, whereby all the streams emerge from the furnaces at approximately the same uniform temperature. 7 p

2. In an apparatus comprising the combination of a Welding plant for welding togetherend to end a succession of billets to form one or more continuous billet streams,

When the rod leaves the last stand of the rod mill, it e must be sheared at intervals, in order that it may be coiled. The part of the rolled metal corresponding to the welded ends of the individualingots may have to be cut out if, for example the rod is to be drawn into high duty wire and it is therefore desirable that the rod should be sheared at points closely adjacent to the welds to avoid wastage. To bring this about, there is provided a detector located adjacent each of the strands at the entry to the finishing train of the mill. This detector may detect the hot spots in the continuous stand at the weld points i or the radiation emitted by particles for example a ray emitting particles placed at the welding plant 27 in each of the weld junctions in the stream; the detector operates a timer arranged to operate the shears at the end of the finishing train, in order to sever the metal adjacent the welds. It will be appreciated that the welding operations performed on the billets produce local hot spots in the billet streams and that these hot spots are not reat least one post weld furnace, means for passing thecontinuous billet stream or streams from the welding-plant through the. post. weld furnace or furnaces, automatic control for the furnace or furnaces including means for measuring the temperature of billets passing therethrough and controlling the power supplies to the furnace or furnaces to compensate approximately for variations in temperature of the individual billets forming the billet stream or streams so that all streams leaving the furnace or furnaces have approximately the same uniform temperature. 3. In an apparatus according to claim 2 in which the means for measuring the temperature of the individual billets that make up the stream or streams comprises one or more pyrometers located adjacent the path of the billet stream or streams. j V

- 4. In an apparatus according to claim 2. in which the post Weld furnace or furnaces are medium frequency induction furnaces. i

5. In an apparatus according to claim 2a first reheat furnace normally for supplying billets individually, a second reheat furnace and means for supplying billets to the welding plant from'both of said first and second reheat furnaces.

6. In an apparatus comprising first and second reheat furnaces, means for supplying billets to each of the first and second reheat furnaces, a welding plant for welding together end to end a succession of billets to form a plurality of billetstreams, means for directing billets from the first and second reheat furnaces to separate parts of the welding plant, such that'the billets from the first reheat furnace will form a separate billet stream or streams from those from the second reheat furnace, a plurality of post weld furnaces, means for directing the welded stream or streams of billets from the separate parts of the welding plant to different post weld furnaces, control means for controlling the power supplied to each post weld furnace such that the billets streams leaving each post weld furnace are at the same temperature and means for directing the billet streams from. the post weld f-urnaces.

7. In an apparatus according to claim 6 in which each control means includes means for measuring the temperature of the billets passing through the associated post Weld furnace and means responsive to the measured temperature for controlling the power supplied to the furnace to compensate approximately for variations in temperature of the individual billets forming the billet stream or streams so that all streams leaving the furnace have approximately the same uniform temperature.

8. In an apparatus according to claim 6 including instream.

References fitted by the Examiner UNITED STATES PATENTS Cook 219-101 Curley 29-48'7 Coryell 80-69 Hudson 2933.2

Anderson 29-332 Ferm 266-3 Swenson 29-487 RICHARD H. EANES, 311., Primary Examiner.

Claims (1)

1. 6. IN AN APPARATUS COMPRISING FIRST AND SECOND REHEAT FURNACES, MEANS FOR SUPPLYING BILLETS TO EACH OF THE FIRST AND SECOND REHEAT FURNACES, A WELDING PLANT FOR WELDING TOGETHER END TO END SUCCESSION OF BILLETS TO FORM A PLURALITY OF BILLET STREAMS, MEANS FOR DIRECTING BILLETS FROM THE FIRST AND SECOND REHEAT FURNACES TO SEPARATE PARTS OF THE WELDING PLANT, SUCH THAT THE BILLETS FROM THE FIRST REHEAT FURNACE WILL FORM A SEPARATE BILLET STREAM OR STREAMS FROM THOSE FROM THE SECOND REHEAT FURNACE, A PLURALITY OF POST WELD FRUNACES, MEAND FOR DIRECTING THE WELDED STREAM OR STREAMS OF BILLETS FROMTHE SEPARATE PARTS OF THE WELDING PLANT TO DIFFERENT POST WELD FURNACES, CONTROL

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