DE2330334A1 - ROLLING FRAMEWORK - Google Patents

Description

Int. Cl. ² :

IS) FEDERAL REPUBLIC OF GERMANY GERMAN

PATENT OFFICE

B 21 B 35-02

B 21 B 13-08

Tiro co

Offenlegungsschrift 23 30 334

Union priority:

File number: P 23 30 334.6-14 Registration date: 14th 6.73 Disclosure date: 6th 2.75

Description:

Roll stand

Applicant:

Chernoy Metallurgy Institute, Dnepropetrovsk (Soviet Union)

Representative:
Inventor:

Luyken, R., Dipl.-Phys .; Pat.-Anw., 8000 Munich

Borisenko, Gleb Pavlovich; Zernobrivenko, Jurij Sergeewitsch;
Kuzow, Jurij Georgievitsch; Gorbanew, Arkadij Alexeewitsch;
Kukuschkin, Oleg Nikolaewitsch: Kriwobokow, Wladimir Nikolaewitsch;
Pobegajlo, Grigory Gavrilowitsch; Naschiwanko, Vitaly Dmitrievich;
Dnepropetrovsk (Soviet Union)

A request for examination according to § 28 b PatG has been made

Publications to be considered for the assessment of patentability:

DT-AS 12 18 385

GB 7 14 737

ORIGINAL ii

© 1.75 409886/545

Patent attorneys

ZHl LENTiMu.LUYKEN

80CO Munich 22

Institut cernoj metallurgii P 49 751/2

June 14, 1973 Dnepropetrovsk / USSE BK / Br

ROLLING STAND

The invention relates to rolling

of metals, especially on roll stands in block construction for longitudinal rolling of solid and hollow metal rods.

At present, roll stands with predominantly two and three rolls are used.

In the two-roll stands, the rolls are arranged at an angle of 45 ° to the horizontal plane, and each The pair of rollers in the stands of the rolling mill form an angle of 90 ° with the pair of rollers in an adjacent stand a.

In the three-roll stands, all three rolls are un-

409886/0545

arranged at an angle of 120 ° to each other, and each The stand of the rolling mill is rotated about the rolling axis at an angle of 60 ° with respect to the neighboring stand.

The rolls in the known two-roll stand are s- and an intermediate gear from a motor via a transmission set in rotation. The pair of rollers is over a

System driven by hyperbe gears.

The two-roll stand, mounted on the housing of the main gearbox, has no working stand independent meaning and must be considered together with the construction of the gearbox of the main drive, the is intended for torque transmission simultaneously for a number of frames / i combined to form a block.

The main uses of the device drives precision gears in combination with helical cam rollers makes it possible to use clutches and spindles in the drive excluded and the rolling speed up to " To increase 5O m / sec.

The management of the technological rolling process at high speeds requires an increase in manufacturing accuracy of gear teeth. Therefore, the teeth of the main drive of the scaffolding are after the 11-12. Accuracy class produced what that in ^ aircraft engineering applied manufacturing accuracy.

Raise the positive technological and constructive

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The known two-roll stand has the following disadvantages.

The increase in the rolling speed led to the development of additional measures to improve the dynamic Behavior of the scaffolding, for example for attaching the main gearbox ^ of vibration dampers, what made the construction of the scaffolding even more complicated.

The construction of the gearbox of the main stand drive is extremely complicated, heavy, and required the use of high accuracy classes in production, whereby the manufacturing costs of individual assemblies of the scaffolding increase several times.

A two-roll stand is also known, its rolls through, a controllable electric motor via a common gear, via special gear provided for each scaffold, which are united with the comb roll stands and arranged along the frame of the block consisting of stands as well as drive spindles with Hooke joints are driven.

The main disadvantage of this framework is the complexity of the construction of the main drive. The one in the main scaffold drive existing bulky equipment significantly increases the size of the scaffolding block as well as its weight.

The spindles with Hooke's joints in the main drive

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In addition, as shown by experimental data, they lead to the development of significant vibrations of the whale axes and therefore also of the rollers, which m-ontiert on these axes on the fly are, IL-iorbei reaches the oscillation amplitude of the fold considerable sizes in individual cases, which causes a disruption of the tolerances of the workpieces to be rolled.

The mechanical vibrations of the folds present in the scaffolding of this type do not only have an effect the geometric dimensions of the workpieces to be rolled, but also the durability of the framework bearings, so that this is considerably reduced.

It is the construction of a three-roll stand with only one input shaft and with internal distribution of the rotary movement with the help of bevel gears known, which is mainly used when rolling metal rods made of carbon and low-alloy steels. The minimum The diameter of the rolls in such stands is 25Ο mm, while the maximum speed when rolling from Rods in these scaffolding makes 45 m / sec.

Various arrangements of the bevel gear teeth are used in the frame of this type of construction. Here you can the rollers are arranged on rotating or non-rotating axes.

One of the disadvantages of the known construction of the three-roll stand is the arrangement of the bevel gear tooth

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nations within the framework that require great manufacturing accuracy for high-speed operation. With the internal distribution of the rotary movement, the load-bearing capacity of the bearing unit ori and bevel-Ί gear teeth also decreases in comparison with the two-whale scaffolding, because with the three-roll stands the dimensions of La ^ are reiriieiten and bevel gears through end faces of the same name on the adjacent rollers as well as their intersecting ones Axes are limited.

Also known is the construction of a three-roller

a /
scaffolding with a drive of great power, wit only one

Roller is connected, and with zvjei drag rollers.

This construction eliminates a number of disadvantages of the three-roll stands, but at the same time acquires a number of new ones.

For scaffolding of this type, the Gre'fninkel is compared with the previous stand three times less, which means the possibility of further increasing the rolling speed has a negative impact.

During the break in the rolling mill, the drag rollers slow down their rotational speed, which leads to a mismatch the speed of the rolls in the stand. When rolling is resumed at the moment, in which the bar is captured, additional dynamic loads

In addition, wear and tear increases in this framework

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-β-

of the rollers.

Also known is the construction of a three-roll stand with a high-performance drive, which can only be operated with one UaI-ze is connected, and with a special auxiliary drive for two other rollers that do not have any rigid mechanical connection with the drive roller and with each other. The special auxiliary drive of the two rollers consists of immobile attached to chocks of the stand. Box inside which the wheels of small turbines on the roller axles are mounted. A jet of the liquid leaves a arranged on the body of the box at high speed Nozzle, moves in the direction of the tangent to the wheel r.or Turbine and sets it in rotation _ _ (USA patent

"3,611,777). ~ Γ"

The downside of this scaffolding structure is that in it

Missing elements for synchronizing the rotational speed of the auxiliary rollers to the rotational speed of the driving roller, making the job of the rolling stand and the existing locks of scaffolds ^B of the rolling mill at which work at high speeds significantly complicated.

There are __ "_ constructions of four-roll stands known which are currently used very rarely. to

one/

the disadvantages of such scaffolding are complicated construction and a /
low strength __. to count.

The invention is based on the object of such

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To create a rolling stand in a block construction that allows the following c

The rolling process with GesehwindigkeiWron 80 m / sec and about it, whereby the performance of the rolling mill is significantly increased}

To reduce the dimensions and weight of the equipment of the scaffolding;

Eliminate shock loads and vibrations in the scaffolding;

To simplify the construction of the scaffolding, which leads to a reduction in maintenance costs Equipments leads.

It becomes a frame of a rolling mill in block construction

proposed for orphaning massive and hollow metal rods.

contains /

one stand with chocks in which storage units are mounted, which carry axes with a work roll and at least one drag roll, a drive connected to the work roll for deforming the to be rolled Includes rod and drives for drag rollers. According to the invention, each of the drives for drag rollers is in shape of a contactless overall motor of the front type, which is used for the acceleration and synchronization of the rotational speed the drag rollers are used at the speed of rotation of the work roll, the armature of the Electric motor is mounted on the axis of the drag roller, while the function of the stator is performed by a winding

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is/

built into the chock of the whale scaffolding and i <n one The plane lies parallel to the plane of rotation of this roller, with the stator windings of these drives AC "sources are connected.

It is expedient to use printed windings as stator windings, which makes it possible to change the dimensions to reduce the stator windings considerably, to increase their reliability in operation and their service life to extend.

It is also expedient ^J, the armature of the noncontact electric motor at the end face of the drag roller of the chock facing the end face, on which the stator winding is to install. '

This will allow the dimensions of the parts of the drag roller assembly and consequently the external dimensions as well to reduce the scaffolding and to create a rigid construction of this assembly that easily balances dynamically leaves.

It is also expedient to place the stator winding on the outer side of the chock with respect to the drag roller to assemble and the anchor at the end of the axle of this roller, u.zw · to be attached opposite the stator shaft, which allows ■ ■ the regulation of the gap between the surface of the stator winding and the armature surface

a/
to be carried out faster, as unhindered access to the

ORtGIiUL INSPECTED

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adjustable! healing of the scaffolding is present.

About the accuracy when synchronizing the rotational speeds It is important to increase the speed of the drag rolls with the speed of rotation of the work roll It is advisable to have electrical speed sensors on the drag roller axes to be installed, which in electrical

the / \

Equal circuits are switched on for circulation speeds of the work roll and each drag roll, with the

'* Circuits are electrically connected to the power sources in such a way that in the event of a deviation in the rotational speed of the drag rolls from the rotational speed of the work roll, the alternating current frequency of the Power source ... changed accordingly, what a change

the speed of rotation of the drag roller causes ♦

It. it is also useful to fold hollow as drag rollers to be arranged and to accommodate storage units inside as well as the roller axes ·; not rotating, which considerably simplifies the preparation of the stand and facilitates the dynamic balancing of the roll.

You can also synchronize the speed of the drag rollers with the speed of the To arrange work roll contactless encoder in such a way that part of the encoder on the end face of the hollow roll with not rotating axis and facing the other encoder part, which is located on the face of the built-in

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piece is located.

By means of the invention, a rolling stand has been created which allows the rolling process to be carried out at one speed of 80 m / sec and above to be carried out, as the performance of the rolling mill increases considerably, -External dimensions to determine the size and weight of the devices of the scaffolding. ~; - ">

the shock loads and vibrations in the scaffolding and /

to simplify the construction of the scaffolding, thereby reducing the cost of maintaining its equipment is brought about.

In the following the invention is illustrated by describing Embodiments / 7 and on the basis of the drawing _ explained; show it

1 shows a rolling mill in block construction 2Um rolling of metal rods, in which the rolling stand designed _{according to the invention is used, plan view;}

Pig. 2 the rolling stand designed according to the invention, in which the armature of the contactless electric motor is attached to the end face of the drag roller, that of the end face of the chock on which the stator winding is located, which are bearing units arranged asymmetrically with respect to the roller, the roller axis rotating, view along the roller axis with partial Detail}

3 shows a variant of the assembly A from 409886/0545

-H- j NAC3HQ £ RBQHTJ

Fig. 2, in which the armature of the contactless electric motor is attached to the end face of the hollow drag roller and the bearing unit is installed within the same, with the ■ roller axis not rotating;

Pig. 4 shows an embodiment variant of the assembly A of FIG. 2, in which the stator winding is connected to the Tow roller mounted on the outer side of the chock and the anchor is attached to the end of the axle of this roller, whereby the roller axis rotates.

Comprises D _as in Fig 1 illustrated rolling mill in block construction. A controllable total electric drive 1, a connected thereto by means of a clutch 2 group transmission 3 of the rolling mill, a stator 4 for the group consisting of scaffolding block, are placed on which roll stands 5, Ausgangswellen- 6 of the gearbox and electrical encoder for speeds of the output shafts 6 of the stands 5- The encoders 7 are arranged on end journals, not shown, of the output shafts 6 of the gearbox 3 on the side opposite to the side of the erection of the roll, zframes 5.

The rolling stand 5 according to the invention (FIG. 2) has a stand 8 with chocks 9, IQ and 11 formed as a whole with these, in which a work roll 12 arranged on the drive shaft 13 and two identical drag rolls 14 and 15 are accommodated.

In each of the chocks 9 and 10 of the drag rollers 14 and 15, respectively, removable universal stator blocks 1β are

409886 / 054S

mounted, in which there are stator windings 17 ″, which represent printed windings.

The stator block 16 has an annular cooling chamber 18, which is intended to cool the staton winding 17 during work. The cooling chamber 18 has two openings 19 for the supply and discharge of the cooling liquid, of which an opening in ^ ig. 2 is shown.

The stator block 16 together with the stator winding 17 is built into the body of the chock 10 and, together with the winding 17, is in a plane which is parallel to the plane of rotation of the roller 15.

The drag roller 15 sits on a rotating axle 20, which is stored in storage units 21 and 22, which are arranged asymmetrically with respect to the drag roller, wherein the bearing unit 21 on the part of the stator block 16 compared to the bearing unit 22 to a greater distance in front Roller 15 is removed. Here, the difference in the distances is mainly dependent on the width of the stator block 16 certainly.

On the end face of the drag roller 15, which faces the end face of the chock lO, on which the stator winding 17 is located, an armature mount 23 of the armature is attached. In the anchor socket 23 is an anchor 24 installed. The armature mount 23 is on the body of the roll 15 fastened by several screws 25.

In the body of the chock 10 is a channel 26 for the

40 98 86/054 5

Supply of dehumidified compressed air provided by it into an annular channel 27 which extends from the surface of the axle 20 and the inner surface of the annular bore of the stator block 16 is formed, and then passes into a gap 28 which is formed by the surface of the stator winding 17 and the surface the armature mount 23 is formed, the end face of the stator winding 17 cools.

On the end face of the rotating shaft 20, the roller 29 of an electrical transmitter 30 is placed, which determines the rotational speed the drag roller 15 measures, the encoder in the electrical circuit, not shown, for Synchronization of the rotational speeds of the roll 15 and the work roll 12 is switched on, which of the

Output shaft 6 of the transmission 3 and from which this work roll bearing drive shaft 13 is rotated.

Analogous to the electrical 3 ° encoder for the drag roller 15 is on the second drag roller 14 to measure its rotational speed a similar electrical transmitter 31 is attached, which is also connected to the electrical Circuit for synchronizing the rotational speeds of the rollers 12 and 14 is connected.

The union of the parts of the non-contact electric motor of the face type with the parts of the rolling stand (the stator winding 17 of the motor is combined with the chock 10 and mounted in it, while the armature 24 of the motor united with the drag roller 15 and within the same

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is mounted) allows the dimensions of assembly A of Fig. 2 and accordingly the external dimensions of the framework to decrease.

The combination of the non-contact electric motor of the face type with the parts of the roll stand makes it possible to to create an extremely compact and rigid construction of the roll stand. The dynamic balancing of the Drag roller 15 did not pose any difficulties.

By using φΐΞ stator winding ^ of printed windings 17, which are connected to an AC source (not shown), it becomes possible to reduce the dimensions of the stator block 16, which is located in the chock 10 of the 7 / alzgerüstes 5, which in turn can reduce the external dimensions of the chock and consequently also the external dimensions of the framework. The use of printed instead of the stator windings from Le ± - windings tern executed also allows to simplify the electrical insulation of the winding important to improve the moisture isolation several times, the winding from water intrusion.

as. reliably protect against scale and oil, and to prevent their mechanical damage.

These advantages of the printed stator windings allow a considerable increase in their operational reliability and an extension of their service life.

A variant of the roll stand with the construction

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following / group A, shown in Fig. 3, has design deviations from that in $ ig. 2 shown roll stand.

Instead of the roller I5, a hollow roller 32 is used, while the rotating axle 20 is immovable with the one on it arranged roller 15 rotating together with the axis is replaced by a non-rotating axis 33 is.

The storage units 21 and 22 are replaced by a storage unit 34 mounted inside the hollow roller 32 is. The construction of the armature mount 23, which now also includes the cover, has also been modified. 35 of the storage unit 34 represents which on the end face of the circumferential hollow roller 32 fixed by means of screws 36 is. On the opposite side of the bearing unit 34, there is a second one on the end face of the rotating roller 32 Cover 37 of this storage unit is arranged, which is fastened with the aid of screws 38.

To cool the end face of the stator winding 17, which faces the gap 28, the compressed air is through a channel carried out in the body of the non-rotating shaft 33 39 and channels 4O supplied, which are perpendicular to the channel 39 along the radii of the axis 33.

In the variant of the roll stand described here, the rotational speeds are synchronized of the drag rollers 14 and 15 with the circulation

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digke ± the work roll 12 provided contactless encoder, with part of the encoder on the end face of the hollow roll 32 attached to the non-rotating shaft 33 and the other, on the end face of the chock 11 of this roller attached part of the encoder is facing.

As the part of the contactless encoder arranged on the end face of the hollow roller 32, one of the screws is used 38 used, the head 41 slightly in the gap between

-surface / ". (.in - /

the end of the roller 32 and the chock 11 cantilevered · the other Part 42 of the encoder is attached to the end face of the chock 11 of this roller and is slightly above it Surface before, the head 4I of the screw 38 and the fixed part 42 of the encoder is equidistant from the center of the non-rotating axis 33 of the Roller 32 are located (the constructions of such contactless encoders are known and in detail '_ in the technical Literature described).

The design of the roll stand, in which hollow rolls 32 are housed in their interior as drag rolls

( , are arranged « )

Bearing units 34 and non-rotating axles 33V has in those Cases of advantages when bars are rolled from a metal with a low yield strength and increased rigidity the parts of assembly A of the roll stand is not required. In this case, the preparation of the Stand 8 of the roll stand 5 considerably simplified and the dynamic balancing of the hollow drag rollers 32

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eases.

An execution variant of the roll stand with the construction legend /

Group A, shown in Fig. 4, has ...__. .constructive Deviations from the roll stand shown in FIG. 2 on.

The stator block 16 is on the one in "with respect to the drag roller 15 mounted outer side of the chock 10, while the armature socket 23 at the end 43 of the axis 20 opposite the Statcrwick 17 attached and by means of a screw 44 is attached.

This arrangement of the parts of assembly A allows the gap 28 between the surface of the stator winding and the surface of the anchor quickly thanks to the unimpeded access to the roll stand parts.

In addition, by relocating the armature mount 23 from the roller body to the end 43 of the axis 20 of the Drag roller possible to reduce the width of the rollers 12, 14 and 15 and the! »Storage units 21 and 22 symmetrically in with respect to the roller 15 to be arranged.

This type of roll stand is compact, has increased rigidity and the parts can be divided easily dynamic balancing

The roll stand is "operated" as follows.

At the (not shown) control panel of the in, Fig. 1 shown The machine operator prepares all electrical circuits (not shown) for switching on the rolling mill before, namely the circuit to control the controllable

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Overall drive, the circuit to control the ^ achsel-

_ ._ a /
Power sources with an operating frequency of more than 50 Hz and for synchronizing the rotational speeds of the work roll and drag rolls. Known electrical circuits, which are dealt with in the technical specialist literature and which are suitable for the given operating conditions, can be used here.

The machine operator then switches the system for cooling the stator windings 17 with the aid of the carriages 18 and the system for press air cooling of the end face of the stator winding 17, which is located in the annular gap 28. % r in the presence of the cooling liquid in the cooling chambers 18 and the compressed air in the channel 261 are not shown Control measuring apparatus, which is provided in the rolling mill, switching on the controllable electric motor and the electric Current sources of the stator windings free.

Furthermore, the machine operator of the rolling mill switches on the electric drive 1 and the power sources of the stator windings. The electric drive rotated by means of the clutch 2 rehung the range change gearbox 3 in ^D, which begins again, with the runner of output shafts 6 and drive shafts 13 of the rolling stands 5 to rotate the work rolls 12, wherein the electrical sensor 7, which are for the end journals of the output shafts 6 are located, measure the rotational speeds of the work rolls 12.

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the / electrical signals get into circuits for control

tion of the "Sttc-m-" sources and into the circuits for comparison the rotational speeds of the work roll 12 and each drag roll 14 and 15.

Under the action of the alternating current, a magnetic field formed by the stator winding 17 is created in the gap 28 Rotating field which interacts with the armature 24 arranged in the drag roller 15 and "begins to rotate" this roller.

The work roll 12, if it acts on the alternating current frequency of the "power sources of the stator windings" via the electrical transmitter 7, regulates the frequency _and sets the rotational speed of each ... drag roll 15 and 15 close to the rotational speed of the work roll 12.

To avoid the lagging speed of the

Vc ^ nigeiU Drag rolls 14 and 15 close behind the work roll 12 eliminate the aerodynamic losses caused by the friction of the rollers and 15 against the air,

and/

the one in the storage units 21; 22 resulting friction

occurs / -

losses as well as losses resulting from the interaction

Ve ^ testandy

the drag rollers 14 and 15 with water <^ the caliber is supplied to the cooling of which is

in each roll stand 5 an additional synchronization of the rotational speeds of the drag rollers 14 and 15 with the Circulation speed of the roller 12 is provided.

For this purpose, each drag roller is on the axis

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14 and 15 electrical sensors 30 and 31 attached, which "in the comparison circuits for comparison de! of these rolls at the same speed as the work roll 12 are switched on.

These circuits are in turn with the help of electrical Feedback with the control circuits of the current type /

sources connected, that at an Abiveiehung of the speed of rotation of the drag roll on the rotational speed of the work roll '. . _. the alternating

tents prechendy selstromfrequency of the power source changed, whereby the speed of the drag roller is changed.

At the moment in which on the work roll 12 the predetermined If the rolling speed is set, the synchronization of the speed on the drag rollers ends 14 and 15 at the speed of roller 12 · The rolling mill is prepared for work.

Furthermore, the process of rolling metal bars on the rolling mill runs in the direction of the arrows shown in FIG. _r

The work of the roll stands with the assemblies A, which in ^ ig. 3 and 4 are reproduced, corresponds completely to the description of the work of the roll stand shown in FIG. 2 and set up in the rolling mill shown in FIG. .

An important advantage of the roll stand according to the invention is the considerable increase in whale speed and accordingly also the performance of the rolling mill.

the/

The increase in the rolling speed is supported by 409886/054 5

case of bevel gears in the roll stand construction

■ ψ
achieved. Here "the ^G rei angle remains the same as with the presence of the bevel gear teeth.

Characterized in that in the rolling stand bevel gear for distributing the rotational movement missing from the rolls, it is possible to vary the diameter of the rolls and in the technological point of view appropriate way, the diameter and _ 'the yield coefficients of being rolled ^s tabes in the caliber of the scaffold to regulate.

Contributes to increasing the rolling speed in the stand also with that in the roll stand according to the invention a simple construction of the group transmission 3 with spur gear teeth is used.

The uses of the construction of the roll stand ^ of non-contact complete motors of the front type for accelerating the drag rollers and synchronizing the rotational speeds This roll with the speed of rotation of the work roll also allows the external dimensions of the roll stand as well as to reduce its weight considerably so-

g how to increase the rigidity and strength of the device.

The roll stand structure according to the invention makes it possible to create rolling mill equipment that is highly dynamic Has behavior and allows high speeds (80 m / sec and above) when rolling rods develop small cross-sections.

The proposed according to the invention framework of the _

$ 409886/054

Block-type rolling mill possesses its simplicity

diverse /

and small design highly technological possibilities in comparison with any other TäTalzgerüsten ^B lοckbauart.

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Claims (7)

PASEffSAHSEHÖGEE: June 14, 197 *, BK / Br (1. Roll stand of a rolling mill in block design for rolling of massive and hollow metal structures that make a stand contains /
with chocks in which storage units are assigned which carry axles with a work roll and at least one drag roll, a drive connected to the work roll for deforming the bar to be rolled and drives for drag rolls, characterized in that each of the drives for drag rolls is in ^ orm a contactless overall motor of the front type is designed, which is used to accelerate and synchronize the rotational speed of the drag rollers (l4 and 15) with the rotational speed of the work roll (12), the armature (24) of the electric motor on the axis (20) of the drag roller ( 14 or 15) is mounted, while the function of the stator is performed by a winding (17) which is inserted into the chock (9 or 10} of the roll stand (5). is/ builds and lies in a plane which is parallel to the axis of rotation of this roller (14 or 15) with the stator windings (17) These drives are connected to AC, sources. 2. Roll stand according to claim 1, characterized in that printed as stator windings Windings (17) are used. 409886/0545 3. Roll stand according to claim 1 or 2, characterized characterized in that the armature (24) of the contactless Elek ^ omotors on the end face of the drag roller (14 or 15) facing the face of the chock (9 or 10) on which the stator winding (17) is located "is located, is appropriate. 4. Roll stand according to claim 1 or 2, characterized characterized in that the stator winding (17) on the "with respect to the drag roller (14 or 15) outer Side of the chock (lO. Or 9) mounted and the anchor (24) at the end (43) of the axis (2O) of this roller (14 or is attached opposite the stator winding (17). 5- Roll stand after a! ____! __. of claims 1-4, characterized in that to increase the accuracy in the synchronization of the rotational speeds of the drag rollers (14 or 15) with the rotational speed of the work roller (12) on the axles (20) of the drag rollers (14 or 15) electrical speed sensors (30 or 31) are attached, which in electrical Comparison circuits for comparing the rotational speeds of the work roll (12) and each drag roller (14 or I5) are switched on, the circuits with the Current sources _ are electrically connected in such a way that at one Deviation of the unilateral speed of the drag roll (14 or 15) from the rotational speed of the work roll 40988 67054 5 5 (12) the alternating current frequency of the power source changes accordingly changes, which means a change in the rotational speed ·· *
speed of the drag roller (14 or 15). 6. Roll stand according to claim 1 or 2, characterized in that the drag rollers are hollow Rollers Cj2) with bearing units housed in their inside (54) are arranged while the axes (33) of the folds (32) do not rotate, 7. Roll stand according to claim 5 or 6, characterized in that for synchronizing the Circumferential speeds of the drag rollers (I4 or 15) with the rotational speed of the work roll (12) contactless sensors (4I, 42) are provided, with a part (4I) of the sensor mounted on the end face of the hollow roller (32) with non-rotating axis (33) and the other part (42) the encoder is facing, which is on the front face of the chock (ll). 409886/0545 Blank page