GB2048737A

GB2048737A - Improvements in Rolling Units

Info

Publication number: GB2048737A
Application number: GB7941348A
Authority: GB
Original assignee: Friedrich Kocks GmbH and Co
Current assignee: Friedrich Kocks GmbH and Co
Priority date: 1979-05-19
Filing date: 1979-11-30
Publication date: 1980-12-17
Also published as: AT373170B; GB2048737B; ATA576179A; ES484451A1; BE878609A; JPS55165202A; FR2457134A1; DE2920398A1

Abstract

A row of rolling stands of a rolling unit (1) for hot rolling metal wire or bars, is divided into two or more component units (10) by a cooling path (14) to prevent the work-material becoming over heated. The individual stands are driven from a common drive motor (2) via intermediate transmissions (5), distributor transmissions (7, 8) and main drive transmissions (12) so that no loop is formed in the work-material between stands or even between the component units (10). <IMAGE>

Description

SPECIFICATION Improvements in Rolling Units The invention relates to a rolling unit for the hot-rolling of wire or bars, particularly for the finishing rolling of not-easily deformable materials in which a number of rolling stands are arranged in tandem and are driven by a common drive.

Various constructions of rolling units of this type are known, in which two, three and, in exceptional cases, even a larger number of rolls form a respective one of the sizing passes. A wide variety of materials are also hot-rolled by means of rolling units of this kind.

When rolling not-easily deformable materials, such as high-alloyed steel, alloys which contain only a low percentage of iron, and various nonferrous metals, rolling speeds are achieved which, at the most, are approximately 30 metres per second and, not infrequently, are less than this. In contrast to this, rolling speeds of more than twice this speed are obtained during hot-rolling of common steels. The reason for this does not reside in a limited efficiency of the rolling units and in their drives, but resides in the fact that, during deformation in the rolling units at higher rolling speeds, the temperature of the not-easily deformable materials rises far in excess of the admissible rolling temperature. This applied particularly when the individual rolling passes are formed by only two rolls. The higher the rolling speed, the greater is the rise in temperature.In the known rolling units, one is forced to reduce the rolling speed in dependence upon the nature of the work-material in order to prevent the workmaterial from being damaged by overheating.

However, this is tantamount to a lower output of the rolling mill.

The above-mentioned disadvantages of known rolling units are particularly evident in the case of rolling units for finishing rolling, since, it is in these units, that the rolling speed reaches its maximum. Basically, however, a rise in the temperature of the work-material also occurs in the roughing and intermediate units, so that the invention described hereinafter is basically usable also in the case of roughing and intermediate units even though it is normally intended only for finishing units.

An object of the invention is to provide a rolling unit for the hot-rolling of wire or bars, by means of which even not-easily deformed materials can be processed at a significantly higher rolling speed without damaging the work-material.

A rolling unit in accordance with the invention, comprises a number of rolling stands arranged in tandem and driven by a common drive, an intermediate gap being provided between two adjoining rolling stands, at least at one location within the rolling unit, and a cooling path for the work-material arranged in said gap.

Consequently, the work-material, which has been heated to a temperature in excess of its original rolling temperature when passing through the first rolling stands, is cooled in the interposed cooling path, so that it enters the following rolling stands with approximately the original rolling temperature. This is repeated when the rolling unit has a plurality of cooling paths. By appropriate design and regulation of the cooling path or paths, the temperature of the workmaterial can be kept within the admissible range, even when the work-material is heated to a higher temperature in the region of the sizing passes as a result of higher rolling speeds.

Therefore, significantly higher rolling speeds can be achieved in the case of not-easily deformed materials, thus considerably improving the efficiency of the entire rolling line. Furthermore, a larger cross-sectional reduction per sizing pass is obtainable with the rolling unit in accordance with the invention, since the interposed cooling paths compensate for the greater rise in the temperature of the work-material which is caused in the sizing passes by the reduction in the cross section of the work-material.

However, the sub-division of a rolling unit into two or more component units with interposed cooling paths must not be confused with the arrangement of two separate rolling stands having a cooling path disposed therebetween.

Namely, an essential feature of the invention is also that the two or more component units or their rolling stands are driven by a common drive, and, consequently, all the component units have only one common group drive. This has the substantial advantage that it is possible to dispense with work-material loops and their regulating means between the component units, without any appreciable change occurring in the prescribed tension compression ratios between the component units.

In a preferred embodiment of the invention, the number of rolling stands upstream of each cooling path is equal to the number of rolling stands downstream thereof. This results in identical structural members in the individual component units, whereby manufacture is considerably simplified and rendered less expensive. However, in special cases, this embodiment will be modified when this appears to be advantageous with respect to the design of the sizing passes or the nature of the work-material.

Furthermore, it is advisable to choose the transmission ratios from rolling stand to rolling stand so as to be equal in the main drive transmission mechanisms of the individual component units. This simplifies and reduces the costs of the assembly and manufacture of the drive transmission mechanisms and the stockkeeping of spare parts.

Furthermore, it it advisable to choose the input speed into the main drive mechanism of a respective component unit disposed downstream so as to be equal to the product of the input speed into the main drive mechanism of the respective component unit disposed upstream, and the total elongation of thesaid component unit. As a result of this, the main drive mechanisms of the component units can be of identical construction, which substantially simplifies manufacture and the stockkeeping of spare parts.

The invention is further described by way of example, with reference to the drawings; in which: Figure 1 is a diagrammatic plan of a rolling unit having two component units each having the same number of stands; Figure 2 is a similar plan of a rolling unit having two component units each having a different number of stands; Figure 3 is a diagrammatic plan of a rolling unit having three component units each having the same number of stands; and Figure 4 shows the rolling unit of Figure 1, together with an appended temperature graph.

Referring to Figure 1, a rolling unit generally designated 1 is driven by a common drive motor 2. The motor 2 has two drive shafts 3 and 4 which drive intermediate transmissions 5 and 6.

Distributor transmissions 7 and 8 are connected to the outputs of the intermediate transmissions 5 and 6 and drive the drive shafts 9 which are distributed around the rolling axis 13 of the rolling units 1. Only one drive shaft 9 in each of the component units 10 can be seen in Figure 1, because the view is taken in plan, the main drive transmission mechanisms 12 disposed above the roller stands 11 being omitted in order to show the roller stands 11, and the main drive transmission mechanisms 12 disposed below the roller stands 11 being concealed in the plan view.

However, the lateral main drive mechanism 12 of each component unit 10 can be seen. The main drive transmission mechanisms 12 include the transmission stages which produce the differing drive speeds for the successive stands 11 so that no loop is formed between the stands or even between the component units 10. The rolling axis 13 is shown by a dash-dot line.

A cooling path 14 is located between the component units 10 and is operated preferably by means of a fluid cooling agent. The cooling bed can be of known construction and is regulable with respect to its cooling action.

Referring to Figure 2, the drive for the rolling unit 1 also comprises a common drive motor 2, but has only a single common intermediate transmission 1 5. The embodiment of Figure 2 otherwise differs from that of Figure 1 only by virtue of the fact that the component unit disposed downstream, that is to say, the right hand component unit 10 in Figure 2, has two rolling stands 11 more than the component unit 10 which is disposed upstream and has only four rolling stands 11.

In the embodiment of Figure 3, the rolling unit 1 has a total of three component units 10 between which are disposed two cooling paths 14. However, here also, each component unit 10 is driven by a single common drive motor 2, a total of three intermediate transmissions 11 being used. Correspondingly, three distributor transmissions 1 7 are provided which transmit the torque to the main drive transmission mechanisms 12.

In the embodiment of Figure 3, the input speed into the main drive mechanism 12 of the central component unit 10 is double the input speed of the main drive mechanism 12 of the component unit 10 disposed at the entry end of the extreme left in Figure 3, although it is only half the input speed into the main drive mechanism 12 of the component unit disposed on the extreme right, on the assumption that the total elongation of each component unit is equal to 100%. The same also applied to the embodiments of Figures 1 and 2.

Referring to Figure 4 the temperature change during the running-through of the work-material is shown in a graph illustrated below an embodiment in accordance with Figure 1. The curves shown in the graph are only given by way of example and it will be appreciated that they are dependent upon the nature of the work-material.

The work-material enters the first rolling stand 11 of the first component block 10 at, for example, a temperature of approximately 870 degrees Celsius, and leaves the first component block 10 at a temperature of approximately 950 degrees.

After being cooled to a barely perceptible extent upstream of the cooling path 14, it enters the latter and is cooled therein to approximately 870 degrees before it enters the first rolling stand 11 of the second component unit 10. This data relates to a calculated average temperature shown by the central curve portion 1 8. The curve 19 located thereabove gives the core temperature which prevails in the centre of the cross section of the work-material, whereas the very much lower surface temperature of the work-material is shown by the curve portion 20. As in the first component unit 10, the temperature rises when the work-material enters the second component unit 10, although it does not exceed 950 degrees and thus remains within the admissible range.

Claims

1. A rolling unit for the hot-rolling of wire or bars, comprising a number of rolling stands arranged in tandem and driven by a common drive, an intermediate gap being provided between two adjoining rolling stands, at least at one location within the rolling unit, and a cooling path for the work-material arranged in said gap.

2. A rolling unit as claimed in claim 1, in which the number of rolling stands upstream of the or each cooling path is equal to the number of rolling stands downstream thereof.

3. A rolling unit as claimed in claim 1 or 2, in which the individual component units separated from one another by said gap are each provided with respective main drive transmission mechanism and in which the drive mechanism transmission ratios from rolling stand to rolling stand in each component unit are equal.

4. A rolling unit as claimed in claim 1, 2 or 3 in which the input speed into the main drive transmission mechanism of a respective downstream component unit is chosen to be equal to the product of the input speed into the main drive mechanism of the respective upstream component unit and the total elongation of the said upstream component unit.

5. A rolling unit for the hot-rolling of wire or bars constructed and adapted to operate substantially as herein described with reference to and as illustrated in the drawings.