DE1934302A1 - Method and device for hot rolling metal slabs - Google Patents

Description

Method and device for hot rolling metal slabs

The invention relates to a method for the continuous or semi-continuous hot rolling of metal slabs to metal strip with a high specific coil weight, for example 3o - 4o kg / mm strip width, in which the rolling stock is heated, descaled, is pre-rolled and is reduced in thickness during finish rolling under tension in the longitudinal direction, as well a rolling mill with rolling stands arranged one behind the other in a line, which are in stand groups each with a roughing and finishing train and, if necessary, an intermediate road are divided up to carry out the method.

In the hot strip mills, in which strips made of steel or non-ferrous metals are rolled, the roll stands, which are designed as continuous stands, are in a line one behind the other and partly arranged in groups of scaffolds. Sometimes individual roll stands are also designed as so-called reversing stands or reversing stands. In these well-known Rolling / recognizing is used in the as Vorstraßen ζ ο Lehne th the first 4 to 6 stands, if possible, so that the Rolled stock is not stressed by longitudinal forces, is

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avoid constrictions in the bandwidth. To achieve this, the first 4 to 6 stands, in which the rolling stock of e.g. 25o mm is reduced to approx. 50 mm thickness, in such a Set up a distance that the tape can run freely between them, so that the roughing train especially when the tape to be rolled into a bundle with a high specific weight becomes very long.

After the pre-rolled strip has left the roughing train, a further free run-out is no longer possible because of the great length of the rolling stock, so that the last 5 to 7 stands of the rolling train have to be pulled together to form the so-called finishing train. In the stands of the finishing train, the m depending on the bandwidth to be generated in spaces between 2 and 5 are positioned alternate _r m is rolled the strip simultaneously. As in the roughing train, it is not possible to roll without drafts in the finishing train. The belt tension between the scaffolding is kept as small as possible, for example with the help of loop regulators.

As a result of the length of the roughing train, in which the strip is only limited Speed can be transported, is a proportionate for the passage of the strip through the roughing train takes a long time, with the tape being impermissibly strong

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cools down. The cooling is because of the increasing distance of the frameworks from one another, the stronger the larger the specific Bundle weights are. To reduce the length of the roughing train and thus the cooling times is to increase the coil weights the last 2 to 3 stands of the roughing mill have already been proposed to form a group. Is particularly strong the cooling of the strip, in particular the rear end of the strip, on the roller table between the last stand of the roughing train and the finishing train, because the strip that is already relatively »thin here can only enter the finishing train very slowly. To the To reduce heat losses, it has already been proposed to increase the thickness of the sliver, i.e. the length of the sliver to shorten, and to roll this pre-strip in a finishing train with an increased number of stands. The increase in the thickness of the sliver However, there are limits when rolling in the finishing train, because the width deviations at the beginning of the strip and Strip ends that are rolled / rolled in the finishing mill without the tension of the loop regulator are not permitted with thicker pre-strips grow up.

The invention is based on the object of a method for Yfarni rolling of metal slabs and a method for carrying this out Process suitable rolling mill to create, by means of which increased specific coil weights by increasing the incoming

009885/0153

Vorländer manufactured, the length of the operating system of a hot strip rolling mill considerably shortened, the drive power to be installed and the heat losses of the strip to be rolled can be reduced. Another job is to get one Specify method for hot rolling metal slabs, by means of whose uniform width can be achieved over the entire length of the belt.

According to the invention, this object is achieved in that the thickness of the metal slab is increased during preliminary rolling or intermediate rolling is reduced under compressive stress in the longitudinal direction, advantageously the size of the longitudinal compressive force by changing the volume of the rolling stock passed through the roll gap per unit of time is set. In an expedient manner, this change can brought about by changing the roll speed or the roll gap. In order to avoid any tensile stress in the rolling stock, this is advantageously the case with preliminary or intermediate rolling from one roll stand to the following roll stand per unit of time The current volume of the rolling stock is kept somewhat larger than that which runs per unit of time and the rolling speed in the trailing one Roll stand increased or, in the leading roll stand, decreased until the volume of the rolling stock runs off is equal to that of the incoming volume per unit of time. Instead of increasing or decreasing the rolling speed a corresponding change in the roll gap can also be made with advantage »

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The one provided for carrying out the rolling process according to the invention Rolling mill is characterized in that between the Roll stands of the roughing train hold-down devices and between the work rolls of the rolling stands of the roughing train and / or the Roll stands of the intermediate train and / or the roll stands of the Pertigstrasse above and below the rolling stock passing through Tape guides are arranged. Compartment of a preferred embodiment of the rolling mill according to the invention are rolling tables below the rolling stock, and a rotating one between the rolling tables Support roller and above the rolling stock a liftable and lowerable role running on the rolling stock is provided, which on attached to a roller holder running in guides and in its height position by means of an adjustable adjusting cylinder is adjustable, wherein the upper edge of the support rollers is arranged above the upper edge of the work rolls. In further Formation of the new rolling mill, a stop is arranged on the roller holder, by means of which the control lever of a To operate the potentiometer and the speed of the drive motor of the work rolls can be regulated. In an expedient manner it is furthermore between the work rolls of the rolling stands of the roughing train and / or the rolling stands of the intermediate train below the rolling stock a roller table with rotatable rollers and above the rolling stock on each roll stand one rotatable around a pivot point

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Roller holder arranged with rollers, which by means of a hydraulic cylinder is adjustable against the rolling stock, wherein with advantage by means of the hydraulic cylinder or the roller holder via a contact manometer or a limit switch Work rolls can be switched off in emergencies and the speed of the work rolls by means of one coupled to the roll holder Potentiometer is adjustable.

The advantages of the rolling process or rolling mill according to the invention According to the invention, a continuous roughing train can initially be seen in the fact that it is considerably shortened can be. In addition, there is a lower temperature drop in the rolling stock, which allows on the one hand the temperature of the Slab heating furnaces, which are connected upstream of the roller train, to lower about 1oo C and in this operating area fuel and to save repair costs and, on the other hand, to increase the specific coil weights, which leads to advantages in terms of acquisition and operating costs in the area of the hot strip mill and in the downstream processing plants the width deviations of the bands are due to the interaction of longitudinal pressure and longitudinal tension in the individual scaffolding groups is reduced. The result is one over the entire length of the tape Uniformly wide strip is produced because the widths caused by unavoidable strip tension in the finishing train

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constrictions over the largest part of the length of the tape by additional Spreading the bands in a scaffolding group in which with Compressive forces rolled in the longitudinal direction of the strip are compensated.

The method of hot rolling according to the invention is shown in FIG schematic drawing explained in more detail using hot rolling mills designed according to the invention. Show it?

Embodiments of rolling mills in

schematic structure,

a top view of a roughing train,

a top view of a roughing train after

Pig. "4 belonging finishing mill,

a top view of a further roughing train,

a top view of the roughing train after

Fig. 6 belonging intermediate and finishing train,

8 shows a longitudinal section through two stands of the roughing and intermediate train according to FIGS. 4 and 6 or 7 _f

9 shows a longitudinal section of two stands of the finishing train and

Fig. 10-14 Diagrams of the balance of forces in the rolling stock during rolling.

Fig. 1 - 3 Fig. 4th Fig. 5 Fig. 6th Fig. 7th

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Pig. 1 shows the schematic structure of a fully continuous Hot strip rolling mill, which consists of the heating furnace group 1, a roughing train 2, a finishing train 3 and a coiler group 4. The roughing train 2 is a scale washer 6, the finishing train 3 is preceded by a cropping shear 5 and a scale washer 6. the Individual machine groups of the rolling train are connected to one another by the roller tables 7.

As can be seen from Fig. 4, the roll stands 1o1 to 1o5 the roughing train 2 by a synchronous motor 8 and two DC motors 91, 92 driven. By changing the speed of the DC motor 91, the roller speeds are changed the roll stands 1o1, 1o2 brought about, while by changing the speed of the motor 92 the roll speeds of the Scaffolding 1o4 and 1o5 can be changed. However, everyone can do it too The stands of the roughing train 2 are individually driven by adjustable motors.

The stands 1o1, 1o2, 1o3 of roughing train 2 are the vertical stands 111, 112, 113 upstream. Between the Gerüoten 1o1, 1o2 and 1o2, 1o3 are hold-down devices 12, between the Frameworks 1o3, 1o4 and 1o4, 1o5 are arranged tape guides 13, the structure and puncture of which is explained below. The finishing mill 3 (Fig. 1), the details of which are shown in Fig. 5.

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represents is "eats in" a known manner; the scaffolding 14 are individually driven by the controllable DC motors 141 via the gears .142 and pinion rollers 143. Between Scaffolding, loop lifters 15 are provided.

A slab is produced in the fully continuous hot strip mill in Pig. 1 with the roughing train to Pig. 4 and Pertigstrasse after Pig. 5 rolled into strip in the following way:

The hot-rolled slab is fed into one of the furnaces of the heating furnace group 1 is transferred to the roller table 7 and runs on it to the roughing train 2. Before entering the roughing train 2, the slab is freed from furnace scale when passing the scale washer 6. the Slab is now in the roughing train 2 simultaneously in the horizontal frames 1o1 to 1o3 in thickness without longitudinal tensile stress reduced in width in the rolling stock and in the vertical upsetting stands 111, 112, 113. The hold-down devices 12 between the rolling stands 1o1, 1o2 and 1o2, 1o3 control together with rolling pressure cells, not shown, in the vertical upsetting frame 111, 112, 113 the speed of the motor 91 and thus the longitudinal forces in the rolled material. In the frameworks 1o4, 1o5 v / ird with Longitudinal compressive forces in the rolling stock worked to increase the bandwidth. The magnitude of the longitudinal compressive forces is beneficial through Change of the roller speed with the Gerüofcen 1o4, 1o5 over the

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The speed of the motor 93 is set. The engine speed and / or the roll gap is set in an expedient manner in such a way that the width in the middle of the strip is opposite to the ends of the strip differs in that the different constriction between belt ends and the middle of the strip, which is later created by the different pulling of the loop lifters 15 in the finishing train 13, straight is compensated.

The pre-strip running out of the roughing train 2 runs over the roller table 7 to the cropping shear 5, where it is scooped and treads, after the secondary igniter has been removed in the scale washer 6, into the rolling stands of the finishing train 3, where the strip is reduced to the finished strip thickness in a known manner.

If strips of different widths are to be produced from a slab width in a wide range, a grouping of the roll stands according to FIG. 2 is expediently used. This roller train, which also works as a fully continuous train, consists of the heating furnace group 1, the roughing train 16, the intermediate train 17 »the finishing train 3 and the reel group 4. The individual machine groups are connected to one another by roller tables 7. The roughing train 16, the intermediate train 17 and the finishing train 3 are each preceded by a scale washer 6. Between the Z _w Ischenstrasse 17 and the scale washer 6 is disposed a crop shear. 5 In front of the horizontal stands 1o1 to 1o5 the

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In the roughing train 16, the vertical upsetting stands 113 to 115 and also the hold-down devices 12 are installed. Between the stands 171, 172 (Fig. 7) are tape guides 13 and 13 between the scaffolding 173 and the cropping shears 5 is the same as each A loop lifter 15 is arranged between the stands 14 of the finishing train 3.

The roll stands 1o1 to 1o5 of the roughing train 16 (FIG. 6) are driven by a direct current motor 91 and a three-phase motor 19 and a common transmission 2o. The roll stands 171 to 173 of the intermediate line 17 (Fig. 7) are driven by the DC motor 91 also via a common, e.g. hydraulic Gearbox 2o or driven by three individual DC motors, not shown. The roll stands 14 of the finishing train 3 are driven according to the embodiment of FIG. A slab is produced in the fully continuous hot rolling mill 2 with the roughing train according to FIG. 6 and the intermediate train and finishing train according to FIG. 7 in the following Way rolled into strip:

In the roughing train 16, the slab is, for example, 300 mm thick continuously reduced to 8o mm and in width e.g. from 1o5o mm to 97o mm by 80 mm, including the speeds of the motors 91,

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19 sp are set in the manner explained below that the Y / rolls of the roll stands 1o1 to 1o5 act with a slight slow ck on the rolling stock and so certainly none Width constriction occurs in the middle of the pre-strip. Behind the last stand 1o5 of roughing train 16, from which the pre-strip at a speed of approx. 1.5 in / sec. exits, runs it freely on the roller conveyor 7, on which it goes to the scale washer is transported and enters the intermediate road 17. In the Scaffolding 171 to 173 of the intermediate train 17, the pre-strip is reduced under longitudinal pressure in the thickness of 8o ram to 15 mm. As a result of the compressive stresses exerted on the rolling stock by the rolls of stands 171 to 173 of roughing train 17 in the longitudinal direction the tape is spread more in the middle of the tape than at the beginning or end of the tape. To prevent this from happening in the Between belt 17 under longitudinal compressive stresses belt moves up or down, it is expediently between the frameworks 171 to 173 supported by belt guides 13.

When the strip emerges from the last stand 173 of the intermediate line 17, it is scooped with the help of the cropping shears 5, freed from the secondary igniter in the scale washer 6 and then finished in the stands 14 of the finishing train 3 in a known manner rolled, with the additional produced in the intermediate train 17

Spreading in the mb to compensate for those by that. The sling lifter 15 in the finishing train 3 is used to constrict the belt.

The method for rolling hot strip can also be carried out with advantage in a semicontinuous rolling mill according to FIG. The rolling mill according to Fig. 3 consists of the heating furnace group 1, one Reversing stand 21 and the intermediate and finishing train 17 and 3 designed according to FIG. 7. Ground in the reversing stand 21 E.g. the slabs are rolled down in five passes with a thickness of 300 mm. Since the pre-strip is removed from the roll stand 21 after each rolling table can run out freely, an uneven spreading of the rolling stock occurs not on.

The semi-continuous roller train operating according to FIG. 3 offers in terms of space requirements, small width deviations and large specific coil weights have the same advantages as the fully continuous roller train according to Fig. 2. The heat loss in the roughing train, however, is larger in the semi-continuous rolling train according to FIG. 3 than in the fully continuous rolling road according to Figs. 1 and 2, so that the pusher furnace at semi-continuous Roads according to Fig. 3 have to work with higher temperatures. When converting existing semi-continuous hot strip mills the arrangement according to FIG. 3 offers, however, quite considerably « Advantages because the existing reversing stand 21 can then continue to be used.

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Around the rolling stock without longitudinal tension and only with compressive tension is to be rolled in the longitudinal direction in stands 1o1 to 1o3 of roughing train 2 and in stands 1q1 to 1o5 of roughing train 16 A hold-down device 12 according to FIG. 8 is advantageously provided between each of these stands. Below the Rolled stock 8o1 at the exit or entrance between the scaffolded e.g. 1o1 and 1o2 the rolling tables 8o2, 8o3 and between the rolling tables a rotating support roller 8o4 is arranged, the upper edge of which lies above the work rolls 8o5 of the roll stands 1o1, 1o2. Above of the rolling stock 8o1, the hold-down device 12 is provided, which consists of the adjustable adjusting cylinder 121 and the There is guides 122 for the roller holder 123 in which the pressure roller 124 is rotatably mounted. On the roll holder 123 a stop 126 is arranged, by means of which the control lever 127 of a potentiometer 128 can be actuated. The introduction is movably attached to the frame 1o2.

The hold-down device 12 shown in Fig. 8 operates as follows:

The front end of the rolling stock 8o1 emerging from the roll stand 1o1 runs at the speed of the work rolls 8o5 of the frame 1o1 over the roller table 8o2 and the support roller 8o4 until it hits the infeed beam 125. From the introduction. bar 125 is the tip of the rolling stock 8o1 around the support roller

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bent down and runs between the work rolls 8o5 des Roll stand 1o2 a. The speed of the work rolls 8o5 in the stand 1o2 is set so that the through the stand 1o2 the strip volume running off per unit of time is somewhat smaller than the strip volume flowing in from the framework 1o1 per unit of time. In this way, the rolling stock 8o1 lifts the roller 124 together with the roller aging 123 against the pressure of the adjusting cylinder away. The roller aging 123 presses with the stop 126 the control lever 127 of the potentiometer 128 up, which via suitable switching devices lowers the speed of the drive motor of the work rolls 8o5 of the stand 1o1 for as long or the roll gap ' is reduced until the volume of the band running towards this structure equal to the QiBandvolume running through the roll stand 1o2 is.

Both that between the roll stands 1o1, 1Ό2 as well as that in the Rolling stock located in the roll gaps represents the time of the rolling process, while it is lifted from the support roller 8o4 under compressive force in the longitudinal direction, which is caused by the pressure in the adjusting cylinder 121 is determined. By changing this pressure, the compressive force in the rolling stock can be varied if necessary. She must however, it should always be set so low or high that the tape does not buckle upwards in front of or behind the roller.

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So that the rolling stock 8o1 or strip under compressive stress cannot buckle up or down between the roll stands 1o3 to 1o5 (FIG. 4-) or 171 to 173 (FIG. 7), it is guided up and down by a strip guide 13 , as shown in Fig. 9, supported. The strip guide, generally designated 13, is provided between the schematically illustrated roll stands 1o3, 1o4. It consists of a roller table 131 with the rotatable rollers 132, which is fastened between the roll stands 1o3, 1o4 below the rolling stock 8o1 in the roll stands. Above the rolling stock 8o1 are the two roller holders 133 with the rollers 134 ' ^{which can be} rotated about the pivot points 135 and are pressed against the rolling stock 8o1 passing through with the aid of the cylinders 136. The hydraulic pressure in the cylinders 136 is advantageously set so high that the roll holders 133 are not raised when the degree of compression of the rolling stock 801 is provided. If, in the event of malfunctions in the roller train, belt loops are formed upwards, which lift the roller holders 133, which causes a pressure increase in the cylinder 136, the roller train is switched off via contact pressure gauges or limit switches (not shown). In an expedient manner, the roller holders 133 can also be coupled with potentiometers, via which the motor speeds of the work rolls of the rolling stands 1o3, 1o4 can be influenced.

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Viewed from the distribution of forces in the rolling stock, the one according to the invention runs Rolling process as follows:

The beginnings and ends of the tape are in both scaffolding groups, i.e. », rolled in the roughing train 2 or in the roughing and intermediate train 16, 17 as well as in the finishing train 3, without forces in the rolling direction. The rolling force 'P generated during the deformation im Roll gap when the friction between rolls and is neglected Rolled in this, as in Pig. 1o shown in the direction of Rolled stock thickness is the compressive stress A. The compressive stress A causes tensile stress through its transverse components in the longitudinal direction of the rolling stock B and the tensile stress C in the transverse direction of the rolling stock. The deformation of the rolled stock in the direction of its thickness, The length and width are in these belt areas, as apart from the V / alzkraft P no other external forces act on the rolling stock, only determined by the magnitude of the stresses A, B and C,

In the first stand group, i.e. in roughing train 2 or in roughing and intermediate train 16, 17, the strip is started as soon as it is in zv / ei or more stands are rolled at the same time by setting suitable speed differences between the individual stands the upsetting force denoted by D in FIG. 11, which in the rolling stock in the longitudinal direction corresponds to the compressive stresses E with their Transverse components F, G generated *

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The tensions from the forces P, D (Fig. 1o and 11) are superimposed after Pig. 12. The transverse component F (open arrow) acts counteracts the voltage A (closed arrow) and amplifies the Rolling force. The transverse component G (double open arrow) is effective in the same direction as the transverse component C (three times more open Arrow) and increases the spread. The beginning and the end of the tape are therefore narrower than the middle of the strip after leaving the first stand group.

In the second stand group, i.e. in finishing mill 3 » rolled in a known manner with looper 15. As soon as that Belt has run into two or more stands, the loop lifters 15 are positioned against the belt from below and

testify in this a tensile force, denoted by H in Fig. 13 is the tensile stress in the longitudinal direction of the belt! I with the transverse components K, 1 in the directions of strip thickness and strip width evokes.

The stresses from the forces P, H (Fig. 1o, 13) are superimposed according to Fig. 14. The transverse component K (open arrow) acts in the same direction as the tension A (closed arrow) Thus the longitudinal force I supports the rolling force P. The transverse component L (double open arrow) affects the cross component C. (triple open arrow) and reduces the spread;

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In the second stand group, the beginning and end of the strip are therefore wider than the middle of the strip. The uneven widths in roughing train 2 and ^: in finishing train 3 or in roughing and intermediate train 16, 17 and in finishing train 3 are thus compensated for.

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Claims (11)

Hoesch Aktiengesellschaft ^, 46 Dortmund ^ Eberhardstrasse 12 claims 1. Process for the continuous or semi-continuous hot rolling of metal slabs to metal strip with a high specific coil weight, in particular with 3o - 40 kg / mm strip width, in which the rolling stock is heated, descaled, pre-rolled and, during finish rolling, under tensile stress in the longitudinal direction in the thickness is reduced, characterized in that the metal slab is reduced in the pre-rolling or intermediate rolling in thickness under compressive stress in the longitudinal direction. 2. The method according to claim 1, characterized in that the when pre-rolling or intermediate rolling from a roll stand into the following roll stand per unit of time increasing volume of the rolling stock is somewhat larger than that which is running per unit of time Volume and the rolling speed in the following roll stand increased for as long or in the leading roll stand for so long is decreased until the outflowing volume of the rolling stock is equal to the inflowing volume per unit of time. 0 * 0 9 8 8 57 oil B "9" 3. The method according to claims 1 and 2, characterized in that the size of the longitudinal compressive force by changing the pro Unit of time passed through the roll gap volume of the material to be rolled the roller speed is set. 4. The method according to claims 1 Ms 3, characterized in that the change in the per unit time passed through the roll gap Volume of the rolling stock is brought about by changing the roll speed or the roll gap. 5. Rolling mill with rolling stands arranged one behind the other in a line, those in scaffolding groups with one pre-production and one finishing train each and, if necessary, an intermediate road are divided for carrying out the method according to claims 1 to 4, characterized in that between the roll stands (1o1 to 1o5) of the roughing train (2, 16) hold-down devices (12) and between the work rolls of the roll stands (1o1 to 1o5) of the roughing train (2, 16) and / or the roll stands (171 to 173) the intermediate train (17) and / or the rolling stands (14) of the finishing train (3) above and below the rolling stock (8o1) continuous tape guides (13) are arranged. - ν - «U 6. Rolling mill according to claim 5, characterized in that below the rolling stock (8o1) rolling tables (8o2, 8o3), a rotating support roller (8o4) between the rolling stock and above the rolling stock (8o1) a lifting on the rolling stock (8o1) and lowerable rollers (124) are provided, which are arranged on a roller holder (123) running in guides (122) and whose height can be adjusted by means of an adjustable adjusting cylinder (121). 7 * rolling mill according to claims 5 and 6, characterized in that that the upper edge of the support rollers (8o4) is arranged above the upper edge of the work rolls (8o5). 8. Rolling mill according to claims 5 to 7, characterized in that that on the roller holder (123) a stop (126) is arranged, by means of which the control lever (127) one Operate the potentiometer (128) and set the speed of the drive motors the work rolls (8o5) is adjustable. 9. Rolling mill according to claim 5 »characterized in that between the work rolls (8o5) of the roll stands (1o3 to 1o5) of the roughing train (2) and / or the roll stands (171 to 173) of the intermediate street (17) below the rolling stock (8oi) a roller table (131) with rotatable rollers (132) and above the rolling stock (80I) on each roll stand one around a pivot point (135) rotatable roller holder (133) with rollers (i34) is arranged, which by means of a hydraulic cylinder (136) against the rolling stock (80I) can be adjusted. 10. Rolling mill according to claims 5 to 9 »characterized in that that by means of the hydraulic cylinder (136) or the roller holder (133) via a contact manoraeter or a limit switch the work rolls can be switched off. 11. Rolling mill according to claims 5, 9 and 1o, characterized in that that the speed of the work rolls (8o5) by means of a potentiometer coupled to the roll holder (133) is adjustable. 009 885/0 15