GB1603427A - Heat shield arrangements - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HEAT SHIELD ARRANGEMENTS (71) We, ENCOMECH ENG ! NEER ! NG SERVICES LIMITE, a British Company of 729 London Road, Hounslow, TW3 1SE, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement :- This invention relates to heat shield arrangements and it is concerned particularly, but not exclusively, with heat shield arrangements for use in metal processing, and to hot-rolling mills employing such arrangements.

Modem engineering techniques are increasingly demanding materials with improved properties, which involve closer control of their manufacture and processing. As a particular example in steel mill processing whether of billets, strip or sections, the metallurgical qualities of finished product are closely related to the accurate control of temperature of the material during the hot rolling process.

A modern hot strip mill producing steel coil can be up to a kilometre in Icneth and typically steel slabs or billets are reduced from 25 cms thickness to 0.2 cms using several roughing mill strands and five or more finishing mill stancls. Durinz the roll- ing process considerable heat losses occur so that the slabs have to be heated initially well in excess of the temperature requirement at the end of the process but a particular problem has been that the heat losses from slabs passing along the mill depcnd upon the time taken. If the slabs are delayed, excessive heat losses occur and the steel strip does not have its required rolling temperatures, so that it may have to be downgraded or even scrapped. In many long modern rqlling mills the delay of one length of strip at the finishing end has an effect on the several lengths of material which are simultaneously at various preceding stages of rolling. Thus with more stringent quality specifications it is becoming more important to reduce the rate of heat loss from the material during transport between stands.

There is an added difficulty in this because during the final reduction stages the back end of the strip takes longer to pass through the finishing mills and so there is a temperature"run-down"along the steel strip due to the cumulative time delay along the length of the strip. The effect of temperature"run-down"is to some extent ameliorated by accelerating the finishing mills during the rolling of each individual slab or strip but nevertheless it remains a problem.

Attempts have been made in the past to reduce the heat loss from the top surface of a hot strip during transport from the roughing mills to the finishing mills. Because radiation is a major source of heat loss at the temperatures involved (around 1060 C) reflectors have been used with somz success to reduce temperature"run-down"from 40 C to around 25 C. However maintenance problems limit the usefulness of reflectors which become inefficient as soon as they become dirty. Such reflectors cannot in any case be fitted under a strip because hot scale and steam would rapidly damage them. In addition, the aluminium reflectors which have been used for their high reflectivity and relatively low cost can reach their melting temperature if their renectivity decreases. As a result rrflectors have been abandoned as a practical means of reducin 7 heat losses from the top surface of a hot strip.

According to the present invention there is provided a heat shield arrangement for material being processed in a hot-rowing mill, the arrangement comprising respective series of heat-insulating panels mounted above and belon a path for the hot material through the mill, the panels each having a heat-insulating core and a cover plate formin or overiying a main face of each panel to the hot matcrial being adapted to form the hot face of the panel and to radiate back heat from the material, and the panels being adapted to be operated with the temperature of the cover plates close to that of the adjacent surfacc of the hot material, and contact elements projecting downwards in the region of the cover plates of the upper group of panels to below the level of the cover plates for protecting the cover plates from engagement with the hot material.

By using such panels in the arrangement, it is possible to rely on rc-radiation of the heat transmitted to it from the adjacent hot surface in order to reduce the cooling of that surface. However, the coverplate is relatively thin and the contact elements held to protect the downwardly facing cover plates if there is any tendency for the hot material to lift or to buckle upwards.

Preferably the upper series of panels are mounted on support means which allow them to be raised to gain access to the conveying path, and a raising mechanism may be provided that can be actuated automatically by sensing means operated by said contact elements to protect the panels by lifting them completely away from the hot material should there be a malfunction that causes the material processed to lift to such a degree that it would otherwise strike the panels.

In a preferred feature, at least some of the panels are displaccable on their support means for varying their heat-silielding effect on the hot material, and there may be provided at least one array of temperature sensors laterally spaced across the material path, and control means actuable by said sensors for said displacement of the panels in order to control the temperature and/or the temperature profile of the material being processed in accordance with predetermined values.

In one form of the invention a hot-rolling mill having a roller table or other roller conveying means provided with a heat shield arrangement according to the invention is provided means for reducing the heat flow from the hot material to the rollers. In particular, the main supporting rollers may be separated from the material by smaller diameter rollers interposed between them and the material, while means may be provided for lifting the material clear of the conveyor rollers when it is to be kept stationary for any period of time.

The invention will be more particularly described by way of example, with reference to the accompainving drawings, some of which appear in our division) patent application No. 8031500 (Serial No. 1603428) relating to another invention illustrated therein. In the drawings : Fig. 1 is a iongitudinal vertical section of a portion of the strip conveying path in a hot strip rolling mill showing upper and lower panels used in a heat shield arrange- ment according to the invention, Fig. 2 is a perspective view of a part of a transfer conveyor of the mill showing only the upper panels in place, Fig. 3 is a raph illustratin ; ; temperature run-down of a slab in a hot strip mill and the influence on this of a heat shield arrangement according to the invention, Fig. 4 is a transverse cross-section of a heat shield arrangement, analogous in many respects to the embodiment of the invention shown in Fig. 2, but incorporating adjust- ment means for the panels, Fig. 5 is a schematic illustration of the control means for the arrangement of Fig. 4, Fig. 6 is a transverse cross-section of a protective device for the arrangement of Figs. 4 and 5, Fig. 7 is a transverse cross-section of a further form of heat shield arrangement according to the invention, Figs. 8 and 9 are schematic illustrations of alternative heat-insulating panels for the arrangement of Fig. 7.

Figs. 10 and 11 illustrate details of a modfied front plate construction for a panel of a heat shield arrangement according to the invention, Fig. 12 is a longitudinal section of a heat shield arrangement illustrating a feature that can be employed in the arrangements of Fig. 2 or Fig. 4, and Figs. 13 and 14 illustrate in mutually transverse sections a modified ro ! ler construction that can also be employed in a hot-rolling mill with the heat shield arrangement of Fig. 2 or Fig. 4.

Referring to Fig. I of the drawings, a hot strip mill delay table is shown with a hot steel slab or strip 1 resting on rollers 2 and with low thermal mass insulation panels disposed above and below the strip.

The upper panel comprises a casing con taining a two- ! ayer core of heat-insulating material consisting of high temperature ceramic fibre board insulation 4 adjoining a bottom cover plate 3 forming the hot face of the panel, the insulation 4 being backed by lower temperature insulating board 5.

The cover plate 3 is formed by a thin sheet of temperature resistant material, e. g. stainless steel, which material can be made either heat reflecting or absorbing. The cover plate rests upon heat-resistant anele-section frame 7 of the casing, which allows free thermal expansion of the plate, and slots 31 in the frame also allow its relative thermal expan- sion. The top of the pancl is sealed by a top plate 10 to which is fixed a mounting lug 11.

In use, as the hot strip I enters under the panel heat radiated from the strip will impinge on the cover plate. Initially the front end of the strip will cool at almost the rate it would achieve in free air while the cover plate is cool. If the plate is thin-for example, less than 1/50th of the thickness of the hot strip 1-then its temperature will quickly rise towards the strip temperature without a significant drop in strip temperature, and as heat loss into the panel is minimised by the thermal insulating core and the panel almost immediately begins to reradiate heat and approach thermal equilibrium with the strip.

The total effective emissivity of the cover plate of the re-radiatina pancl is increased by substantial corrugating or dimpling or like local contouring 6 of its surface, and since the cover plate is preferably very thin such contouring can serve to strenothen the plate and allow local flexing to facilitate relaxation of thermal stresses set up by rapid heating and cooling of the plate.

The total effective emissivity of the cover plate of the re-radiating panel is increased by substantial corrugating or dimpling or like local contouring 6 of its surface, and since the cover plate is preferably very thin such contouring can serve to strengthen the plate and allow local flexing to facilitate relaxation of thermal stresses set up by rapid heating and cooling of the plate.

The cover plate is held from above against the horizontal flan-es of the frame 7 by leaf springs 8 to help provide a seal between the plate and the frame and so minimise the intrusion of dirt and steam into the ceramic fibre core, Vents 9 can also be provided in the side walls of the mounting frame 7 to facilitate the escape of steam if, as during periods of inactivity, water is absorbed by the core and is subsequently vaporised by the heating that occurs when the panel begins to be used again. One-way flap valves 30 on the vents 9 help to prevent the ingress of steam from the surroundings. Tt should be noted that if the cover plate is very thin, extra retaining clips 13 may be required to hold it against the ceramic fibre material of the core.

It will be clear that almost half the heat radiated by the strip is from its lower surface. The problems presented in placing a panel under the strip are greater than for the top panel and in general a modified construction will be required. The lower panel shown in Fig. 1 is supported on the table base plate 15 and can rest thereon either directly or through brackets 16. The cover plate 17 forming the hot face of the lower panel has local contouring like the plate 3 but forms an integral part of an outer casing of welded construction with stainless steel side walls 18 and base 19 as below the strip greater protection is needed against the ingress of foreign matter. The contouring is preferably in the form of a series of par allel corrugations arranged particularly to accommodate thermal expansion of the hot face relative to the remainder of the panel, but because the cover plate is restrained at its edges, the casing is made relatively narrow in the direction of the corrugations, e. g. some half the length transverse thereto. The corrugations also increase the effective emissivity of the hot face, as mcnfioned above, and strengthen the relatively thin material.

The base of the casing has one or more corrugations 20 to allow differential thermal expansion and the panel is filled with a core of highcr and lower temperature insulating ceramic fibre panels 21,22 respective ! y, similar to the upper panel core. Small steam vents 23 are provided in the base of the panel to allow venting of trapped water and these are normally closed by one-way valves 30.

A number of lower panels are disposed side-by-side across the width of the strip and not only reduce the heat loss from the bottom of the strip, but by extending close to the opposed sides of successive rollers of the delay table they also reduce the thermal load on the rollers thereby improving their operating life and redut. n the amount of water cooling required.

The effect of a series of such upper and lower panels as a heat shield in a rolling mill can best be understood by reference to Fig.

3, which shows the temperature or a strip or slab at entry to the roll train of a mill after it has passed along a delay table.

Curve A shows how the temperature of the strip, as sensed at the mill entry, runs down because of the increasing heat losses that have occurred at points progressively further back along the length of the strip due to the increasing delay before entry as dic- tated by the travel speed of the strip in the rolls. The initial temperature of the strip would be, say, 2012 F and while the front end temperature loss nijulit be some 100 F at mill entry (point F), further back along the strip the material arrives at the mill with a progressively lower temperature.

Curve B shows how the heat shield arrange- ment of panels according to the invention gives a similar temperature fall at the front end of the strip, while the panels are still cool, but they almost immediately radiate heat to reduce the temperature fall and very quickly approach the initial temperature of the strip and can reverse the temperature profile for the rear end of the strip, so as to give a more uniform temperature at roll entry.

In a sufficiently long run, the rear end temperature of strip can of course approach the initial strip temperature, but in general the form of the temperature distribution at points along the strip length at their entry to the mill can be controlled by choice of the storage and conductivity characteristics of the hot faces of the panels and the heat insulating cores. It is even possible to incorporate heating means in the panels adjacent their hot faces to give a more uniform cxit temperature, but usually this would only be required for material having a relatively low thermal mass, such as bars and sections.

As already stated, the cover plates can be heat-reflecting but in generaI it will be found convenient to make them black to suit the dirty environmental conditions and in this case they can operate better to improve the temperature distribution in the common condition of a strip with a higher temperature lealing end in the manner shown in Fig. 3, or similarly where there is some time lag in the passage of the trailing end to a roll stand The mounting of the lower panels presents no problems but the top panels require to be mounted so that they can be readily lifted from over the hot strip, e. g. for maintenance or to allow the remova ! of the strip in the event of a long stoppage or to prevent damage to the panel if there is a buckled or bent strip. Fig. 2 illustrates a mounting means suitable for strip mill applications in which upper panels 32 are suspended over the tables in pairs by their top plates 10 and mounting lugs 11 from booms 12, although for narrow mills one panel width will be sufficient to span the roller table whereas on wide mills as many as four panels side-bymay be required. The panels are arranged in a row or rows extending along the stripconveying direction to make up the required heat shield area. It will be understood that the smaller width of the low. r panels clic- tated by thermal expansion considerations in this particular use will result in the use of a larger number of panels than the upper panels to cover the same width.

The booms 12 are mounted as cantilevers from shafts 24 on external floormounted frames at one side of the mill the shafts being supported in rotary bearing blocks 25 to be able to pivot the booms through substantially 90'between the hori zontal position shown and a raised vertical or near vertical position. Columns 26 carrying the bcarings blocks are positioned so as to provide access to the roller drive motors (not shown) of the mill. The panels and booms are countcrbalanced on the shafts by wci. shts 27 and the movement of the panels is obtained by motors 28, e. g. hydraulically operated, which are designed to give positive drive both when raising and lowering the panels.

Operator controls (not shown) are provided for the motors 28 to allow the panels to be raised and lowered for maintenance or access to the nill. To prevent damage to the panels during operation, e. g. if there is a bent or buckled strip in the mill, a skid bumper bar 14 is fitted to certain of the panels or to the boom structure so that the bent strip will contact the bar to push the panels upwards. Preferably, the skid bumper bars are connected to pressure switches 29 which activate the raising movement of the motors 28 in such an eventuality, so that the panels are lifted independently of the force on them.

In Figs. 4 to 6 there is shown a further development of the invention in the example of steel strip rolling mill similar in many respects to that shown in Fig. 2, but in which the heat shield panels can be adjusted in position to achieve a more uniform temperature distribution in the hot material.

Upper panels 40 are mounted on cantilever arms 41 over the conveyor for the steel strip 1, so that as in Fig. 2 the panels are able to cover the entire upper face of the strip. In this embodiment not only are the cantilever arm supports of the panels displaceable to move the panels towards and away from the strip, but the panels themselves are displaceable on the arms to regulate their effect on the strip.

For this purpose the panels may be conveniently arranged in pairs with the central bumper bar 14 independently mounted be tween them. The panels are supported by transverse rails 42 that are secured below the cantiliver arms and are suspended from rollers 42a running on the rails so that they can be displaced laterally towards and away from each other by rams 43, as indicated by the arrows A in Fig. 4. Each rail is pivoted at its inner end 44 and connected by rams 45 to the arm 41, so that by operation of the rams the rails can be tilted about their pivots, and in particular can be so tilted as to raise the laterally outer edges of the panels as shown in outline in Fig. 4. The lower heat shield panels 46 below the strip path are also mounted through rollers 47a on rails 47, which in this instance are fixed, so as to be movable laterally inwards and outwards by rams 48 in the same manner as the upper panels.

The movements of the different rams dur ing the operation of the arrangement to con trol the temperature of a steel strip travelling along the conveyor path is governed by a control unit 60 (Fig. 5) receiving signals from an array of temperature sensors 61 disposed across the width of the strip. It is unnecessary to illustrate the detailed con- struction of the unit 60, since the principes of control equipment design by which these signals are utilise to give the outputs indicated below are well understood and are fully within the knowledge of a person skilled in the art. If the sensors indicate that the temperature at the edges of the strip is too high, the rams 45 between the cantilever arms and the upper rails 42 can be operated to tilt the outer edges of the upper panels upwards, the angle being adjusted to suit the required heat loss rate. If, on the other hand, the temperature at the centre of the strip is too high the panels 40 and/or 46 can be traversed on their rails so as to leave a gap at the centre, both above and below the strip, to allow increase radiation from that region. The extent of the opening movement and the number of panels opened along the length of the conveyor path can both be adjusted to suit the extent of the temperature correction required.

It is also possible to lift the cantilever arms 41, with the panels 40, this serving both as a means of temperature control for the strip and as a means of protection of the panels against damage from a bent or buckled strip. For this purpose, as may be more clearly seen from Fig. 4, each arm 41 is mounted on a fixed frame 50 through a normally horizontally shorter link 51 pivoted at 52 to the lower end of the arm and a longer link 53 pivoted at 54 intermediate the length of the arm and normally lying parallel to the cranked end portion of the arm. The arm 41 is displaced by a ram 55 attached at one end 56 to the frame 50 and its other end 57 being connected to the longer link 53. The mechanism operates, when the ram 55 is extended, to produce a magnifie pivoting movement of the arm 41, as shown in Fig. 4, the stroke of the ram being set so that the panels can be raised to a nearly vertical position, leaving clear access to the roller table.

As already indicated, the ram 55 can be operated by the automatic control means to regulate the temperature of the material.

This can be done when it is required to lower the temperature of the strip as a whole rather than alter the temperature distribution, and normally it will be sufficient for only a small length of the total length of the upper series of heat shielcls to be lifted away for this purpose. The number of panels so raised will determine the cooling effect obtained. The rams 55 may also be automatically operated if a bent or buckled strip is in the mill. The bumper bars 14 provide initial protection in this eventuality, but they also can he provided with pressuresensitive switches so that as the strip bears against them, the rams 55 are actuated and the upper panels are immediately raised clear of the strip. independently of whether they have actually been contacted by the deformed strip.

It will be understood that the control unit may comprise means for readily adjusting the set points or required temperature limits to suit different materials being processed, and there may be a number of arrays of temperature sensors at different stations along the length of the strip conveyor path, either operating upon the same control unit or operating upon separate control units for individual stations of the conveyor path.

The bumper bar 14 may be used in a similar manner to that described with reference to Fig. 2, to raise or actuate raising of the upper panels when there is a risk of damage from buckled or bent stock. Additionally or alternatively, there may be a bent stock detector 62 (Figs. 5 and 6) disposed over the conveyor upstream of the panels to indicate the approach of raised parts of the strip that might damage the panels. The detector support arm 63 may have a simple pivot mounting 64, controlled by a ram 65, to swing the detector clear of the conveyor when required, but it may alternatively have the same form of displacement mechanism as the arms 41 It should be understood, moreover, that such a detector may also be employed in the first-described arrangement in which the panels are fixedly mounted on their supports.

The invention is not restricted to installations in which the heated material is in strip form, and Figs. 7 to 9 illustrate the application of the invention to control the temperature of bar of profiled section stock moving along a conveyor path.

Mounted on a fixed frame 71 are drive rollers 72 for the stock 73, shown here as a square section bar, driven by one or more motors 74. The conveyor path runs perpendicular to the plane of the figure. Mountings 76 pivotable about an axis 77 parallel to the conveyor path carry upwardly projecting side support rollers 78 for the stock and lower heat shield panels 80 of the composite construction already described. Together with upper U-form panels 81 of similar construction these lower panels 80 form a tubular enclosure for the stock. The upper panels 81 are supported on pivot mountings 82 that allow them to be swung upwards to the broken-line position by rams 83, clear of the conveyor and the stock on it. When the upper panels have been swung away in this manner, the side support rollers 78 can be pivoted downwards to give free access to the stock, in particular to allow bent or damaged stock to be removed more easily.

The pivoting of the mountings 76 for the bottom panels allows them to be tilted when the installation is being serviced to shake off any accumulation of mill scale or other foreign matter.

Because the top panel has a cross-sec tional profile that increases its stiffness as compared with the flat panels so far des cribed, it can be made considerably longer : it may have flat faces 84 or axial corruga- tions 85 can be provided to stiffen the inner cover plate, as has already been described.

This inner cover plate is allowed some freedom to expand axially and laterally and is retained in place by lipped edges 86 of the panel casing and heat-resistant ties 87 passing through the inner core of insulating material. A bumper bar 88 projects through the top panels to protect them from being damaged by out-of-shape material. As already described, the bar acts as a contact element and can be provided with impact sensors 89 arranged to trier the operation of the lifting rams 83 for raising the top panels.

The cross-sectional profile of the panels can be varied, for example, to suit a particular cross-section profile material, as is exemplified in Figs. 8 and 9. In Fig. 8, the bottom panel 91 also has a U-form profile increasing its stiffness and the radiussing of the cover plates at the inner corners 92 of the panels can improve the uniformity of the temperature of the stock passing through the arrangement. The corners of rectangular stock or even of the outer eclges of the flanges of the I section shown will normally radiate heat more freely and so cool faster, but the increased insulation of the radiussed corners of the panels has an opposite and therefore compensating effect.

A similar effect can be obtained with the configuration shown in Fig. 9, where both panels 93 have a semi-circular cross-section.

In some circumstances it may be required not only to conserve the heat in the material being processed but also to apply further heating. For example, this mi-hot be necessary if the material is to be held at a constant temperature. It is possible then to provide heating means in or en the insulation panels themselves, as is illustrated in Fivs. 10 and 11. These show a multi-layer cover plate, with a front plate 101 forming the hot face of the panel, a first electrically insulating layer 102, an electrical strip heating element 103 capable of operating at a temperature of 1100 C or more, a second insulating layer 104, and a back plate 105 that like the front plate is suitable for use at hih temperatures.

The layers are secured together by hollow rivets 106 that may also serve to receive suspension ties 107 for the panel, although panels with cover plates of this construction are suitable for mounting both above and below the material being shielded. To maintain the material temperature, the element 103 may be of relatively low power, e. g. up to 5 kwlm2, but higiler powers may be used when required. Tt will be clear without further illustration that the control unit 60 can also fcgulate the operation of the heating elements.

The use of panels with heating elements is shown in the arrangement in Fig. 12, although tubular sheathed elements 103a are illustrated. This example shows a further heat conservation masure, it bc ng assumed in this example that the arrangement is be ing employed with an existing steel mill roller table, which will be equipped with large diameter rollers 110 of high thermal capacity, often water-cooled. The upper and lower thermal insulation panels 111, 112 have the general composite construction already described and both series of panels are arranged in pairs side-by-side, with a central skid bar, 113 and Il4 respectively, between the panels of each pair. The lower panels are also so constructed that there are two or more successive pancls along the distance between adjacent rollers 110, and between these successive panels transversely extending hfting bars 115 are interposed.

These bars, of a high temperature alloy and possibly also provided with heat insulation, can be raised, e. g. by fluid pressure rams 116, to the position shown and so lift the material I from the rollers 110. The mechanism can be used when the operation of the mill requires the material on the roller table to be stopped for any significant length of time. Because of the thermal mass and/or the cooling of the rollers, there would be the risk that cold spots would develop in the material at the regions of contact with the rollers, and that these would affect the uniformity of the final product.

The problem of avoiding undue heat loss to the rollers can alternatively be overcome by modification of the roller table construction in the manner illustrated in Figs. 13 and 14. The main supporting rollers 120 have smaller rollers 121 resting on them, the rollers 121 being of a heat insulating material. Both series of rollers are journalled in a housing assembly 122 and are driven to gether, as by the gearing 123. It may be arranged that the housing assembly can readily be opened to remove the rollers 121 at least, when servicing is needed. Upper heat-insulating panels 124 can be lifted clear in the manner already described when this is to be done.

The main rollers preferably have reduced diameter portions 125 so that the contact area between the rollers 120,121 is confined to the relatively small extent of the larger diameter portions 126, so reducing any heat loss through conduction. If scale drops from ; he matcrial, on the table this measure also helps the scale tc fail clear. It is a further advantage in the use of the smaller diameter high-temperature rollers that the lower heat-insulating panels 127 can be brought closer tonether, so that there is a further reduction of heat loss by radiation.

Claims (19)

1. WHAT WE CLAIM IS :- 1. A heat shield arrangement for material being processed in a hot-rolling mill, the arrangement comprising respective series of heat-insulating panels mounted above and below a path for the hot material through the mill, the panels each having a heat-insu lating core and a cover plate forming or overlying a main face of each panel to the hot material being adapted to form the hot face of the panel and to radiate back heat from the material, and the panels being adapted to be operated with the temperature of the cover plates close to that of the adjacent surface of the hot material, and contact elements projecting downwards in the region of the cover plates of the upper group of panels to below the level of the cover plates for protecting the cover plates from engagement with the hot material.
2. 2. An arrangement according to claim 1 comprising displacement means connected to support means of the upper series of panels for lifting the panels away from the material path.
3. 3. An arrangement according to claim 2 comprising sensing means disposed adjacent the material path and responsive to lifting of the material being processed, for operat ing control means to actuate the operation of said displacement means in dependence upon the response of said sensing means, whereby to protect the panels against dam age by the material.
4. 4. An arrangement according to claim 3 wherein said sensing means comprises ele ments operable by said contact elements for actuating the operation of said displacement means in response to the movement of said contact elements by the material.
5. 5. An arrangement according to any one of claims 1 to 4 comprising adjustment means for displacing at least some of the panels to vary their heat-shielding effect on the hot material.
6. 6. An arrangement according to claim 5 for use with material in strip or billet form wherein a plurality of said panels are dis posed side-by-side across the lateral extent of the arrangement, and means are connected to said panels for displacing the panels to wards and away from each other to vary their heat-insulating effect on a central region of the material.
7. 7. An arrangement according to claim 5 for use with material in strip or billet form wherein a plurality of said panels are disposed side-by-side across the lateral ex tent of the arrangement, and means are con nected to said panels for tilting the panels to displace their laterally outer regions to wards and away from the hot material to vary their heat-insulating effect on the outer lateral margins of the material.
8. 8. An arrangement according to claim 5 wherein said adjustment means comprises means for selectively displacing panels over a portion of the material path towards and away from said path.
9. 9. An arrangement according to claim 6 together with claim 7 wherein a plurality of panels are displaceable both towards and away from each other and by tilting as aforesaid.
10. 10. An arrangement according to claim 9 wherein said plurality of panels are also displaceable transversely towards and away from the material path.
11. 11. An arrangement according to any one of claims 5 to 10 comprising at least one array of temperature sensors laterally spaced across the material path, and control means actuated by said sensors conr. ected to said adjustment means for said displacement of the panels in order to control the temperature and/or the temperature profile of the material being processed in accordance with predetermined values.
12. 12. An arrangement according to any one of claims 1 to 11 wherein the lower series of panels are laterally tiltable for removal of foreign matter.
13. 13. A heat shield arrangement according to any one of claims 1 to 12 wherein means are provided adjacent the lower series of panels for raising the material.
14. 14. An arrangement according to any one of claims I to 5 wherein the panels form a substantially closed tubular conduit for the hot material.
15. 15. An arrangement according to claim 14 comprising guide rollers disposed within the cross-sectional envelope of the panels for the guiding material.
16. 16. A hot-rolling mill comprising a roller table having a series of conveyor rollers along a path for hot material being processed, and a heat shield arrangement according to any one of claims 1 to 13 having its lower series of panels disposed between the rollers of the roller table said rollers comprising upper smaller diameter rollers arranged to have the material resting upon them and lower larger diameter supporting rollers on which said upper rollers rest.
17. 17. A hot-rolling mill according to claim 16, wherein the lower rollers have a plurality of axially spaced larger diameter portions with which the upper rollers are in contact.
18. 18. A heat-shield arrangement for material being processed in a hot-rolling mill, constructed and arranged for use and operation substantially as described herein with reference to any of the illustrated embodi ments.
19. 19. A hot-rolling mill constructed and arranged for use and operation substantially as described herein with reference to any of the illustrated embodiments.