US 3625043 A
Description (OCR text may contain errors)
3,625,043 FOR PRODUCING COIL WEIGHTS $83 8 my mm K. J. NEUMANN L CONTINUOUS MULTIPLE CORE ROLLING MILL ROLLED BAR STOCK, ESPECIALLY WIRE OF HEAVY Filed Nov. 13, 1969 United States Patent 3,625,043 CONTINUOUS MULTIPLE CORE ROLLING MILL TRAIN FOR PRODUCING ROLLED BAR STOCK, ESPECIALLY WIRE OF HEAVY COIL WEIGHTS Karl Josef Neumann and Klaus Neumann, St. Ingbert (Saar), Germany, assignors to Moeller & Neumann G.m.b.H., St. Ingebert (Saar), Germany Filed Nov. 13, 1969, Ser. No. 876,272 Claims priority, application Germany, Nov. 14, 1968, P 18 08 822.7 Int. Cl. 1321b 1/18, 27/06, 41/00 US. Cl. 72-202 6 Claims ABSTRACT OF THE DISCLOSURE A multiple core wire train for heavy coil weights with a rapid travel single core roughing group and a multiple core heating trough from which the roughing sections that are rolled down to the usual billet dimensions of an edge length between about 80 to 100 mm. are continuously introduced into the vacated grooves of the first multiple core rolling groups. The pass cross section in the single core roughing group may be theoretically of any size depending on the number of roughing stands so that bars produced in a continuous casting operation having for example an edge length of 180 mm. may be rolled into wire in a single pass.
The invention relates to a continuous multiple core rolling mill train for producing rolled bar stock, particularly wire of heavy coil weights, comprising a furnace, a roughing group, an intermediate group and single core finishing groups. Although the invention has been developed primarily for use with wire trains it may be applied advantageously also for medium and high quality steel trains. For the purpose of this disclosure the following description is directed specifically to the layout of wire trains.
The following are the major influence factors which determine the level of output of a wire train:
(a) number of cores (b) wire end speed (c) pass cross section (d) billet length The number of cores cannot be increased at will due to the limitations inherent in the equipment. With the four core wire rolling train an optimum operation seems to have been reached in view of the influence factor (a).
The wire end speed may be increased, but this is limited by the cropping shears and the coiler apparatus, so that one can state here also that the influence factor Wire end speed of about 50 m./ sec. while using normal shears and coilers represents at the present time an optimum operation, at least when no risks are to be taken with regard to operational safety.
The invention aims at an increase of production in the direction of heavier core weights for which the influence factors pass cross section and billet length prevail. The billet length could be theoretically of any size which may be realized already by welding together various billet lengths. However, this solution is excluded from the scope of this invention because it does not allow an easy multiple core operation. This leaves therefore the possibility of increasing the billet length, but this has an unfavorable 3,625,043 Patented Dec. 7, 1971 influence with respect to the furnace construction. Based on economic considerations the optimum furnace size lies today at a maximum billet length of about 12 m.
In order to increase the coil weight in a wire train on the basis of the above considerations there remains the possibility of increasing the pass cross-section. But particularly on this point the general opinion is that an optimum operation has been reached if one considers that each increase of the pass cross-section means an increase in the number of passes and according to the continuous flow principle a correspondingly decreased input of the billets into the first stand of the roughing group. This causes an unfavorable influence on the heat consumption of the train because the travel time of the billets is increased and thus the temperature difference between the front end and the rear end of the billets becomes greater. It is thus obtained that the deformation resistance across the bar length is unequal and the rolling pressure changes especially in the end stands during the passing of the bars so that the tolerance maintenance of the end product becomes worse. The classical pass cross-section for multiple core wire trains lies therefore today at mm. square. In order to produce from this a coil weight of 1500 kp. the billets would have to have a length of 30 m., which is completely impractical from the standpoint of the furnace builder. The pass cross-section would have to lie at about mm. square which at a wire end speed of 50 m./sec. on the basis of the continuous flow principle would mean an input speed in front of the first stand of the roughing group of 0.075 m./sec. This low input speed is complete- 1y impractical from the standpoint of heat economy. Even in that case the bar length would still have to be about 14.8 m., if one sets out for a coil weight of 1500 kp. a raw weight of the billet of 1550. Also with this billet length the furnace would become fairly Wide and would have to be provided with a complicated suspension ceilmg.
The classical multiple core wire trains operate for reasons of heat economy directly out of the furnace so that with the low input speed of the billets into the first stand of the roughing group the end of the billets is subjected to heat as long as possible. This means a certain disadvantage in that the billets cannot be sprayed down before the rolling process in order to remove scale.
The invention shows the way to provide in a multiple core continuous rolling mill train for the production of wire of heavy coil weights substantially independent of the pass cross-section, which could be presumed to be impossible in view of what has been mentioned before. The solution of the problem which has been presented consists in that one uses instead of a multiple core roughing group a single core rapid travel roughing group preferably with an H-V arrangement of the stands, from which the roughing sections exit freely with an exit speed that is larger relative to the input speed determined by the continuous flow principle and the wire end speed of the multiple core intermediate group by at least a multiple of the core number, wherein a heating device which collects the freely exiting roughing sections and is located between a distributing guide and the intermediate group is pro-' vided, from which the roughing sections may be conducted in each case to vacated grooves of the intermediate group.
The single core operation of the roughing group according to the invention allows first of all a free selection of the pass cross-section relative to a conventional multiple core roughing group particularly when due to the H-V arrangement of the stands no twisting is required. With the increase of the pass cross-section one need merely increase the number of stands in the roughing group. The rapid travel of the single core roughing group which has to supply the grooves with roughing sections provides that due to the relatively high input of the billets into the roughing group one may discard the rolling out of the furnace. The billets may be completely freed of scale by a high pressure spray-down device before being introduced into the roughing group. The high rolling speed of the roughing group reduces not only the influence of the cooling water on the temperature of the roughing section but the single core arrangement of the roughing group presents also the advantage of highest accuracy of the existing cross-sections and permits in comparison with the multiple core roughing down operation lighter stands and smaller driving moments, because the required torques are smaller. The heating device collecting the freely exiting roughing sections in front of the intermediate group now assures that the ends of the roughing section are heated up during the now slow input of the roughing sections into the grooves of the multiple core intermediate group or are either kept warm or heated up further in order to prevent during the further intermediate and finishing rolling the temperature drop to be expected toward the rear end of the bar.
In this respect the heating device corresponds practically to the furnace and the multiple core intermediate group to the roughing group of a classical wire train which is supplied with the usual pass cross-section of 80 mm. square. From this standpoint the invention consists of an arrangement which precedes the furnace and provides a rational reduction of even the highest initial cross-section down to the classical pass cross-section of 80 mm. square wherein this cross-section, in consideration of a coil weight of 1500 kp. to be obtained according to what has been mentioned previously should be 30 m. long. There is no particular problem of building a heating trough of this length especially since it may be shorter than the length of the roughing sections and that it has to take up the roughing sections only up to a front end protruding beyond the furnace length since it is a basic requirement to heat up the rear bar end of the roughing sections upon entering the intermediate group.
It has been stated that the roughing group should operate with an exit speed for the roughing sections which is larger relative to the input speed of the multiple core inter-mediate group determined by the continuous principle and the wire end speed by at least a multiple of the core number. It lies Within the scope of the invention that the roughing group may travel even faster if this is desired from the standpoint of heat economy but in that case stoppages must be allowed in the billet sequence of the roughing sections when the heating device is designed only for receiving a number of roughing sections in adjacent relationship corresponding to the core number of the intermediate group, wherein the distributing guide receiving the heating device directs the roughing sections in adjacent relationship and in the exact direction of the grooves of the intermediate group. It is appropriate to provide a multiple core driving apparatus between the heating device and the intermediate group in order to continuously feed the roughing sections of the intermediate group wherein depending on the size of the grooves the driving apparatus may also be a twisting apparatus with driven rolls. In order to feed the roughing sections to the intermediate group it would also be suflicient to provide the heating device with driven rolls.
The single core rapid travel roughing group may be replaced in the case of a two-core layout of the rolling mill train also by a rapid forging machine since such machines operate on the average with an output speed of 0.3 rn./ sec. which comes to about twice the input speed into the intermediate group, presuming a pass cross-section of 80 mm.
square for the intermediate group and a wire end speed of 50 m./sec. With a rapid forging machine one can go even higher in the pass cross-section and come into the range of the continuous casting cross-sections which must be considerable for unkilled steel and be at least e.g. 180 mm. square.
In the accompanying drawing two examples of a wire mill train according to the invention are schematically illustrated in Which? FIG. 1 is an example of a four-core wire mill train with a single core roughing group and FIG. 2 is a two-core mill train with a rapid forging machine.
The two examples of wire mill trains shown in the drawing have each a heating furnace 10, from which the billets arrive on a rolling track 12, and a high pressure spray-down device 14. In the example of FIG. 1 a five stand single core roughing group 16 with an H-V arrangement of the stands follows the high pressure spraydown device 14. At an interval which corresponds to the free outlet distance of the roughing sections leaving the roughing group 16 is located an eight stand four-core intermediate group 18, behind which the guide of the rolled stock bifurcates and the rolling operation is continued in two-core intermediate groups 20, 21. Subsequently the cores 1, 2, 3 and 4 divide for single core finishing rolling wherein each core finishing line comprises a stand group 22 with two stands, a cropping shears 24, a cooling line 26 and a nine stand wire end block 28. The single core operating stands are set up basically in an H-V arrangement. The wire is distributed over horizontal working Edenborn coiler heads 30 on conveyors 32 for cooling and are subsequently gathered in a conventional manner into coils.
Behind the single core roughing group 16 is located a distributing guide 34, a preferably gas heated heating device 36 and a four-core driving apparatus 38 for feeding the roughing sections, which exit freely in front of the intermediate group 18, into the intermediate group 18. The heating device 36 is made so wide that with a fourcore layout of the mill train up to four roughing sections can be gathered in adjacent relationship in the heating device over the distributing guide 34.
For a coil weight of 1500 kp. the rolling mill train according to FIG. 1 permits a pass cross-section of 150 mm. square for the single core roughing group 16 with a favorable billet length of 8.5 m. The five stand roughing group 16 rolls the pass cross-section down to roughing sections of 30 m. length with a cross-section of mm. square. This is the pass cross-section for the four-core intermediate group 18 whose input speed, in consideration of a wire end speed 50 m./sec., equals 0.157 m./sec. The output speed of the roughing group 16 amounts according to the invention with a four-core wire mill train to at least the quadruple of this input speed of 0.157 m./ sec. of the intermediate group 18 in order to bring during single core operation of the roughing group the amount of rolled stock in the time unit in front of the intermediate group 18 which may handle its four sizes in the time unit. The outlet speed of the roughing group 16 can also be started higher, e.g. with 1.5 m./sec., which is favorable for the heat economy of the train. In that case the roughing group 16 may not be operated without stoppage but a roughing section may be fed into the heating furnace 36 only when a groove of the intermediate group 18 is vacant or is about to be vacated. In FIG. 1 the distributing guide 34 is located e.g. at the lower groove row 4 and guides a roughing section 4' into an outer line of the heating device 36. The groove 4 of the first stand of the intermediate group 18 is about to be vacated so that the front end of the roughing billet 4' may be conducted into the driving apparatus 38 which introduces this core now with the low input speed of. the intermediate group 18 into the vacated fourth groove. The end of the roughing section 4' has mean-while left the roughing group 16.
Since with the pass of the roughing section 4 in the first stand of the intermediate group 18 or in the driving apparatus 38 the end of the 30 m. long roughing billet should be in the heating device 36, the distance between the first stand of the intermediate group 18 and the front end of the heating device 36 is at least 30 m. Since the end of the roughing section 4' has already left the last stand of the roughing group 16 when its front end has been grasped by the driving apparatus 38 it is appropriate to provide between the distributing guide 34 and the heating device 36 still another driving apparatus. Of course the feeding of the roughing sections after leaving the roughing group 16 can be assured also by the rolls of a roll track inside the heating device 36. As may be seen from the roughing sections shown in hatched lines inside the heating device 36 the roughing billet of the core 1 is always completely pulled into the intermediate group 18. It is thus core 1 which is to be supplied next by the roughing group 16 with a roughing section and for this purpose the distributing guide 34 is pivoted into the position 34' shown in hatched lines. The following core to be vacated is core 2 and subsequently core 3 so that the distributing guide 34 is pivoted from the position 34 stepwise as far as the extended position and back again. The furnace supplies billets in the same rhythm as grooves are vacated in the intermediate group 18.
The essence of the wire mill train according to FIG. 1 consits in that in spit of the four-core layout one may roll out of a single furnace with reasonable furnace width heavy coil weights because the problem of the heat consumption or of the low input speed in a continuous rolling process has been eliminated by the combination of a rapid travel single core roughing group with a multiple core heating device in front of the intermediate group 18. This heating device prevents not only the cooling of the rearward bar ends upon entering the intermediate group 18, but it heats up the last few bar ends of the roughing sections further with the aim that ultimately in the wire end blocks 28 the sections enter with a constant momentary temperature into the first stand. This means highest tolerance maintenance of the finished product.
The two-core wire train according to FIG. 2 is based on the same principle as the four-core train according to FIG. 1 with the difference that the roughing group 16 is replaced by a rapid forging machine 40. As pass crosssection may be taken billets of 180 mm. square which corresponds to an acceptable cross-section for continuously cast unkilled steel. For a coil weight of 1500 kp. the billets would be 6 m. long. It is also possible to work here with the rapid forging machine 40 down to roughing sections of 80 mm. square which are introduced over a distributing guide 34 alternately in adjacent relationship into a two-core heating device 42 which is followed in accordance with FIG. 1 by a driving apparatus 38 and an eight-stand intermediate group 44. Behind a further two-core stand group 46 with four stands are located two single core finishing lines each with a two-stand group 48, a cropping shears 50, a cooling device 52 and with a wire end block 54. It is to be understood that within the stand arrangement starting from the intermediate rolling operation there is nothing novel either in the train according to FIG. 1 or in the train according to FIG. 2.
Since in the example according to FIG. 2 the pass cross-section for the intermediate group 44 of 80 mm. square is the same as that in the example according to FIG. 1 the input speed of the intermediate group 44 with an end speed of 50 m./sec. is also the same at 0.157 mm./sec. Since a rapid forging machine operates on the average with 0.3 m./sec. outlet speed which is not quite double the inlet speed of the intermediate group 44 the core number of a rolling mill train according to FIG. 2 with a rapid forging machine is limited to two. More cores would require a multiple number of rapid forging machines.
In utilizing the invention for medium and high quality steel rolling trains it is obvious that the aim of the invention is not the increase of the coil weight but the rolling of particularly long bars which from the standpoint of. the heat economy raises the same problems as the manufacture of wire in heavy coil weights.
Since in the case of a medium or high quality rolling train according to FIGS. 1 or 2 the coiler heads 30 and the cooling conveyor belts 32 are to be replaced by cooling beds, it is indicated to subdivide the bars in front of the one or more cooling beds to reasonable cooling bed lengths, e.g. in that the cropping shears designated by 24 or 50 constitute simultaneously dividing shears. These dividing shears could be mounted also behind the finishing groups 28 and 54.
In applying the invention for medium and high quality rolling trains the invention provides that the cropping and dividing shears are to be mounted in front of the intermediate groups 18 and 44, and one for each core. By means of these shears the roughing sections leaving the heating trough 36 are divided to such bar lengths or pass weights which correspond to the cooling bed length of the predetermined finishing cross-section. Accordingly one obtains, in comparison with carrying out the subdividing for example behind the finishing groups 28 or 54, a series of advantages, namely:
( l) the end rolling speed is no longer limited by problems arising from the shears,
(2) no deformation of the finished bars by flying cut sections, thus an easier further working particularly for iron sections,
(3) better utilization of the cooling bed surfaces since for each finishing dimension that particular roughing length may be sent into the intermediate and finishing rolling operation which corresponds to the full cooling bed length,
(4) the interval between the bears which roll on in the cooling bed range becomes larger than if finishing bars are subdivided whereby the roll-on track of the cooling beds is simplified.
It is to be understood that a multiple core wire train according to the invention may be set up in a known manner with cooling beds as well as with devices for producing coils either for each core or for a single core or for several cores.
What is claimed is:
1. A continuous multiple core rolling mill train for manufacturing rolled bar stock, comprising:
a single core roughing group operatively connected to said furnace;
a multiple core intermediate group spaced from said single core roughing group a distance greater than the maximum legnth of roughing sections leaving said roughing group permitting said roughing sections to exit freely therefrom;
an elongated heating device operatively connected to said single core roughing group for receiving said roughing sections one after the other and means for distributing and feeding said roughing sections to the vacated grooves of said multiple intermediate group; and
single core finishing groups operatively connected to said multiple core intermediate group.
2. A rolling mill as in claim 1, including a switchable distributing guide provided on the entry side heating device.
3. A rolling mill as in claim 2, said heating device being shorter than the length of said roughing sections and provided with means for receiving said roughing sections except for the front end portions thereof which protrude beyond the length of said furnace.
4. A rolling mill train as in claim 2, including a highpressure spray-down device operatively connected between said furnace and said roughing group.
5. A method for continuously rolling bar stock, comprising:
heating billets; rollin-g said billets in a single core roughing group; collecting the roughing sections leaving said roughing group in a heating device preventing loss of temperature in the end portions of said roughing sections;
feeding said roughing sections from said heating device into vacated grooves of a multiple core intermediate group; and
rolling said roughing sections in said intermediate group and in a subsequent single core finishing group.
6. A method as in claim 5, wherein said roughing group is operated at an output speed for the roughing sections leaving said roughing group higher relative to the inlet speed of the subsequent multiple core intermediate group bv at least a multiple of the core number while the inlet References Cited UNITED STATES PATENTS 3,382,697 5/1968 Neumann 72228 664,129 12/ 1900 Cronemeyer 72202 1,029,673 6/ 1912 Daniels 72202 CHARLES W. LANHAM, Primary Examiner E. M. COMBS, Assistant Examiner US. Cl. X.R.