GB2258248A

GB2258248A - Intensive cooling apparatus for rolled stock bar layers

Info

Publication number: GB2258248A
Application number: GB9213859A
Authority: GB
Inventors: Frank Ihme; Gerhard Pechau; Volker Flaxa
Original assignee: Schwermaschinenbau Kombinat Ernst Thalmann VEB; SKET Schwermaschinenbau Magdeburg GmbH
Current assignee: Schwermaschinenbau Kombinat Ernst Thalmann VEB; SKET Schwermaschinenbau Magdeburg GmbH
Priority date: 1991-07-27
Filing date: 1992-06-30
Publication date: 1993-02-03
Anticipated expiration: 2012-06-30
Also published as: IT1260523B; ITMI921367A1; ITMI921367A0; GB2258248B; DE4125248A1; CZ230892A3; GB9213859D0

Description

1 INTENSIVE COOLING APPARATUS FOR-ROLLED STOCK BAR LAYERS The invention

relates to an intensive cooling apparatus for rolled stock downstream of a cooling bed in fine and medium steel 5 rolling mills.

In fine and medium steel rolling mills, finished rolled stock is cut into cooling bed lengths by a cooling bed shears tool and, after being decelerated, is transferred onto the cooling bed. Subsequently to the cooling bed, the rolled stock is frequently straightened, cut into sales lengths. packaged, possibly stacked and bound.

Depending on the rolled stock dimensions, brand of steel and desired properties in the end product, the rolled stock is subjected to controlled cooling technology. Thus it may be cooled either only on the cooling bed or in addition by a water cooling section upstream of the cooling bed. Usually the object of the water cooling section is to produce reductions in temperature from 950' - 10OTC (rolling heat) to 78oO - 85TC or for thermally hardened concrete reinforcing steel, to 500' - 55TC. The necessary temperature for further processing, for the adjustment region, is then attained on the cooling bed. The operation of cutting the steel to sales length has hitherto preferably been effected by cold shears which operate in a start-stop mode. As however they frequently represent a bottleneck, new designs of installations therefore provide a combination of straightening machine and flying cold shears which both operate in a continuous mode as described in Patent Specification DE-A-31 23 127.

However a requirement for proper operation is that on the one hand the rolled stock already comes directly from the cooling bed in such a way that it can be automatically introduced without problems into the multi-line straightening machine, while on the other hand it must be at temperatures of <1OTC, because of the elastoplastic material conditions which occur in the straightening operation.

The object is to achieve those conditions by means of the above-mentioned water cooling sections upstream of the cooling bed and by providing a cooling bed of the optimum configuration, possibly with additional air feed devices, see East German Patent Specification 243 174.

2 However, constricted conditions in respect of space, increasing throughput rates and the general trend to a more compact design configuration means that the cooling bed areas are becoming progressively smaller and the necessary discharge temperatures are only achieved by means of additional devices in the cooling bed.

Previous proposals include the use of forced- circulation air feed installations with fans and using water spray means or water mist cooling means in the cooling bed region. Forced-circulation air feed means admittedly already produce very good effects, but for economic reasons the cooling rates cannot be increased just as desired. Higher cooling rates can be achieved by spraying water or providing a water mist cooling effect. It will be appreciated however that, with such a massive use of water, it is not possible to avoid disadvantageous effects on the cooling bed equipment and a general increase in the level of atmospheric humidity in the hall. In the long term therefore that results in rising maintenance costs, for example due to increased corrosion.

There is also the disadvantage that, due to the predetermined rake or grate spacing, the rolled stock is at large spacings relative to each other and most water is atomised into the hall. With solely additional air feed cooling, it is possible that a large part of the range of rolled material on the delivery roller bed will already be at the straightening temperature while a part is still too hot.

The situation is similar if existing installations are intended to operate at higher through-put rates and thus the cooling bed discharge temperatures become unacceptably high. However, the installation of a complete additional cooling system in the cooling bed region is often not suitable by virtue of the considerable level of expenditure or restricted conditions in regard to installation. 30 Furthermore, in practical operation it has been found that the required straightening action of the cooling beds, in relation to profile members and in particular in relation to asymmetrical profile members, is not always adequate so that major problems may arise for example upon automatic introduction into the straightening machine. According to the invention there is provided intensive cooling apparatus for rolled stock bar layers in fine and medium steel rolling mills, comprising, disposed above and/or below a delivery roller bed -t 3 and downstream of a cooling bed, cooling bars mounting switchable, regulatable and interchangeable water/water-air nozzles and, disposed adjacent thereto and also above and/or below the delivery roller bed, air feed units with air nozzles.

By means of the invention while saving on the amount of equipment, the amount of space required and the operating means in comparison with previously proposed solutions, intensive cooling of bar layers of rolled stock can reliably be obtained in order to ensure admissible temperatures for further processing, with an improved degree of bar straightness.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

Figure 1 is a plan view of intensive cooling apparatus according to the invention; Figure 2 is a side view of the intensive cooling apparatus of Figure 1; Figure 3 shows a view in section through the intensive cooling apparatus of Figure 1 in the region of water nozzles thereof; and Figure 4 shows a view in section through the intensive cooling apparatus of Figure 1 in the region of air feed units thereof.

Referring to the drawings, rolled stock 16, after leaving a final roll stand, passes through cooling bed shears 19 and is divided into cooling bed lengths. On a cooling bed 1, the rolled stock is cooled from rolling temperatures of 90TC to 10OTC to temperatures at which structural transformations are concluded; that is to say, in the case of concretereinforcing and mass-production steel qualities, a temperature of lower than 50TC.

Af ter that temperature is reached the rolled stock is conveyed in a fast transport mode to a delivery roller bed 2. On the delivery roller bed 2, a plurality of bars are brought together spaced by profile rollers or as a compact bar layer on smooth rollers and then transported in the longitudinal direction. In that transportation direction, the cooling bed 1 is followed by intensive cooling. apparatus 5. This is a first possible variant.

In accordance with a second variant, arranged in a feed roller bed upstream of the cooling bed 1 are water cooling pipes 18 which either.cool the rolled stock 16 to temperatures just above AC3 or which are intended to provide for thermal hardening for concre te- reinforcing steels and which cool the rolled stock to about 50TC mean temperature. In the first case each bar cycles over the cooling bed 1 until a 5 temperature of about 50TC is reached. In the case of manufacture of concre te- reinforcing steel, rapid transportation over the cooling bed 1 is possible. As in the first variant, there then follows the layer-wise transportation of the rolled stock to the intensive cooling apparatus 5. Major significance is attributed to temperature measurement. It is required as shown at 2 upstream of the water cooling pipes 18 and at 22 upstream of the cooling bed 1 and upstream and downstream of the intensive cooling apparatus 5 as temperature measurement at 6, 7 for all bars. as the bars are at different temperatures relative to each other and over their length. The bar straightness can be ascertained by means of a straightness measuring device 23 at the end of the cooling bed and in that way 'ski and sabre formation' can be prevented when the bar layer passes through the intensive cooling apparatus 5, by means of controlled cooling.

In the intensive cooling apparatus 5, if necessary the material can also be sprayed with special agents such as corrosion-resistant emulsions. waxes, lacquer, etc, using a coating apparatus 20. The intensive cooling apparatus 5 is integrated into the delivery roller bed 2 and comprises cooling bars 8 and 9 with spray nozzles 10, which are disposed alternately above and below the delivery roller bed 25 2, and, downstream thereof, axial fan units 11, 12 which are also arranged alternately above and below the delivery roller bed 2 and which have guide nozzles 13. The temperature measuring devices 6 and 7 are arranged upstream of the intensive cooling apparatus 5 and upstream of a straightening machine 3. In the region of the intensive cooling apparatus 5, roller bed rollers 14 are in the form of magnetic rollers. Disposed beneath the cooling bars 8 and 9 at the bottom of the delivery roller bed 2 is a water collecting tank 15 while disposed thereabove is a spray protection 17.

The mode of operation of the intensive cooling apparatus is as follows:

The rolled stock 16 is collected after being reduced to 4 c temperatures of below 50TC in the region of the cooling bed 1 and transferred in a layer-wise manner onto the delivery roller bed 2. During the transfer operation the temperature measuring device 6 ascertains the existing rolled stock temperature TA and transmits the 5 signal to a control computer (not shown).

Before the rolled material passes into the straightening machine 3, it is checked by the second temperature measuring device 7 in regard to maintenance of the straightening temperature T R On the basis of the temperature values detected, the control computer either does or does not switch on the intensive cooling apparatus 5. In the intensive cooling apparatus 5 the rolled stock 16 first passes through the region of the cooling bars 8 and 9 with the spray nozzles 10. Depending on the respective cooling technology required. all or only some of the cooling bars 8 and 9 may be in use. If for example only some of the bars of the layer, namely those which were transferred last onto the delivery roller bed 2, are at an excessively high temperature TA, then only the respectively required spray nozzles 10 of the cooling bars 8 and 9 are actuated. In addition, actuation of the spray nozzles 10 is so designed, in conjunction with the temperature range measuring devices 6 and 7, that the rolled stock temperature does not fall substantially (about 20 K) below 1OTC so that the water which still clings to the rolled stock 16 easily vaporises and therefore does not result in the formation of rust or spots or stains. Known water or water- air nozzles are used as the spray nozzles 10.

If the cold shears tool 4 operates in a discontinuous mode, the intensive cooling apparatus 5 is switched on only during roller bed transportation in order to avoid partial temperature differences in the rolled stock.

After the water cooling operation, the rolled stock 16 passes through the operative region of the air feed units 11 with the guide nozzles 13. They additionally serve to blow off the rolled stock 16 any water which is possibly still clinging thereto and which has not evaporated or dripped off. It will be appreciated that it is also possible to add rust-restricting agents to the cooling water such as waxes or emulsions or also oils or lacquers as a coating.

The alternating arrangement of the items of equipment, as shown 6 in the illustrated embodiment, is intended to prevent the occurrence of 'dead zones' around the rolled stock. As operation is Possibly effected using relatively high air or water pressures, it is appropriate for the roller bed rollers 14 to be in the form of magnetic rollers which attract the rolled stock. In order to permit intervention by hand, for example when dealing with scrap, the upper cooling bars 8 and the upper air feed units 11 are designed to be tiltable or pivotable or movable. The water collecting tank 15 serves to return the cooling water to the treatment station (not shown). In order to avoid further adversely affecting the surrounding equipment and to save cooling water, the spray protection 17 is mounted over the region of the cooling bars 8 and 9.

If desired in the intensive cooling apparatus the cooling bars 8 and 9 and the air feed means 11 and 12 can be disposed only from below. Alternatively, in constricted conditions of installation, it is possible to envisage an arrangement provided only above the roller bed.

The water nozzles 10 on the cooling bars 8 may be adjustable in regard to their operative direction (for example by way of ball joints) and their spray angle (interchangeable nozzle heads).

Profile bars, inadmissible deviations from standard of which have been detected on the cooling bed 1 by the straightness measuring device 23 can possibly be improved in regard to their straightness by specifically aimed spraying of each bar in the entire layer.

It is further possible for special means to be sprayed on the rolled stock by means of a coating device 20 arranged. downstream of the cooling bars 8 and 9. That may be for example corrosion- restricting additives, waxes, oils or paints.

7

Claims

1. Intensive cooling apparatus for rolled stock bar layers in fine and medium steel rolling mills, comprising, disposed above and/or below a delivery roller bed and downstream of a cooling bed, cooling bars mounting switchable, regulatable and interchangeable water/water-air nozzles and, disposed adjacent thereto and also above and/or below the delivery roller bed, air feed units with air nozzles.

2. Intensive cooling apparatus according to claim 1, in which the cooling bars mounting the water/water-air nozzles have circuitry links with temperature measuring devices disposed upstream and downstream of the intensive cooling apparatus.

Intensive cooling apparatus according to claim 1, in which spray protection is disposed over the cooling bars and disposed beneath them is a water collecting tank, to provide a sealed enclosure.

4. Intensive cooling apparatus according to claim 1. in which the cooling bars and the air feed units are pivotable.

5. Intensive cooling apparatus according to claim 1, in which the water or water-air nozzles are each separately pivotable.

6. Intensive cooling apparatus according to claim 1, in which the cooling bars and the air feed units are disposed only above or only below or both above and below, in a uniform array.

7. Intensive cooling apparatus for rolled stock bar layers in fine or medium steel rolling mills substantially as hereinbefore described and illustrated with reference to the accompanying drawings.