STAND CHANGE CARRIAGE COMPRISING A HYDRAULIC MOTOR

Abstract

The invention relates to a stand change carriage (10) for simultaneously receiving and transporting a plurality of stands of a rolling mill for rolling metal rods, wires or pipes, the stand change carriage (10) comprising a plurality of stand places (16), one of the stands being receivable individually in each of the stand places (16), the stand change carriage (10) comprising a plurality of steerable wheels (20), in order to transport the stands on rails or along a rail-less mill floor, and the stand change carriage comprising at least one hydraulic motor (21) which is operatively connected to at least one of the wheels (20) in order to drive it.

Description

TECHNICAL FIELD

The present invention relates to a stand change carriage for simultaneously receiving and transporting a plurality of stands of a rolling mill for rolling metal rods, wires, or pipes.

BACKGROUND

For rolling metal rods, wires, or pipes, rolling mills are routinely used which comprise a plurality of stands arranged one behind the other in the rolling direction. Said stands in turn contain the actual rollers, which apply the rolling force to the material to be rolled, in order to create metal rods, wires or pipes therefrom.

During operation, the rollers wear, and therefore they have to be refurbished at regular intervals. For this purpose, the stands comprising the rollers to be refurbished have to be removed from the rolling mill and transported to a stand workshop. After the refurbishing of the rollers, the respective stands then have to be transported from the stand workshop again to the rolling mill and inserted into the rolling mill. There is furthermore the requirement to use different stands for different thicknesses of rolled products, the calibers of which stands are already preset to the desired thickness of the respective rolled product.

For exchanging the stands in the rolling mill, stand change carriages are used, in a known manner, which can receive a plurality of stands simultaneously and reliably transport them between the rolling mill and the stand workshop. As described for example DE 10 2014 015 963 A1, in this case a distinction can in principle be made between two different types of stand change systems, in which different stand change carriages are used.

In the first stand change system, which is well known, the stand change carriages do not have their own drive, but rather are moved by means of one or more external control cable systems. For this purpose, control cables and travel sleds fastened thereon are introduced under the mill floor, which forms the substrate on which the wheels of the stand change carriages travel. A change carriage can be attached to a travel sled by means of a coupling rod, and can be moved by the control cable. In this system, the stand change carriages are rail-mounted and it is known in addition to a first stretch of rail extending in parallel with the rolling mill, to provide a second stretch of rail positioned perpendicularly thereto. At switches, which connect the two stretches to one another, the stand change carriage can be switched between the stretches by pivoting the wheels about 90°. Thus, for example, the sequence of the stand change carriages in front of the rolling mill can be changed, if a stand change carriage is temporarily parked on a transverse track. In this system, the choice of which stand change carriage should return to the stand workshop or should be moved to the rolling mill is relatively free.

Since in the case of this type, the stand change carriages do not have any driven axles, the control cable system recessed in the mill floor allows for a lower installation height of the stand change carriages. In particular, the wheels that are pivotable about 90° can also be implemented easily. However, this comes at the cost of an increased space requirement under the mill floor, because a plurality of required components of the control cable system, such as coupling and decoupling stations, cable tensioners, and switch actuators have to be received here. This is disadvantageous in particular when the rolling mill is located in an upper storey of the rolling mill, because the ceiling height in the storey below, in the region of the control cable system, must be significantly reduced, which leads to complexity in terms of structural technology. Furthermore, in this concept, the complexity of the control cable system increases very quickly with the number of stand change carriages to move, and stretches of rail, and is less flexibly adjustable to structural changes in the rolling mill or the stand workshop.

In the second type of stand change system, the stand change carriages have a direct electrical drive of one or more wheels. A stand change system comprising such stand change carriages can in principle be scaled better, because a control cable system in the rolling mill can be omitted. However, electrical supply lines are still connected to these “self-propelling devices” having a cable carrier, in order to ensure necessary control signals and the power supply of the electric motors. Owing to the cable carrier, such stand change carriages are also used only cable-mounted, only one cable carrier, and thus only one carriage having its own drive, being provided per stretch of track. Furthermore, the need for very long lines makes it difficult in practice to have said stand change carriages move directly into a remote stand workshop. Consequently, removed stands must be reloaded by means of a crane, carefully and time-consumingly, from the stand change carriage and onto a different transport means already in the vicinity of the rolling mill, where there is often little space on account of other structures.

Furthermore, in practice only those stand change carriages of the second type are used which can be moved merely in the forwards and backwards direction, but not transversely thereto. Their sequence along the rolling mill therefore cannot be changed and it is not possible to park a stand change carriage of this kind in the second row in front of the rolling mill until it is used. A reason why there are no electrically driven stand change carriages which can change their direction of travel is due to the installation space available. Owing to the dimensions of a sufficiently dimensioned electric motor and its drive unit, a wheel arch of a stand change carriage of the second type requires more space compared with the first type. In order to nonetheless design the stand change carriage to be overall as compact as possible, the wheels are therefore placed in the provided intermediate spaces between the stand places. However, it is no longer possible to position an electric drive having an angular gear in this limited space, which gear is pivotable together with the wheel, in order to thus allow a change in the direction of travel immediately. In other words, the space requirement of the wheel arch of the stand change carriage would be too great. A lateral clearance around the stand change carriage, into which the drive unit consisting of the electric motor and gearbox can extend when the wheel is pivoted, would also have to be provided. Too great a distance between the stand change carriage and rolling mill would, however, be disadvantageous when inserting the stand into the rolling mill. Another reason is the required electrical supply lines. As in a control cable system, upon transfer to another stretch of track the stand change carriage would have to be connected to a different cable carrier, which is associated with additional technical complexity. Furthermore, it would have to be ensured that the cable carriers of the individual stretches of track cannot be damaged upon crossing of stand change carriages.

DESCRIPTION OF THE INVENTION

Against this background, an object of the present invention is that of providing a stand change carriage of the above technical field having a drive concept, which can be used more flexibly than in the prior art. In particular, an object of the invention is that of providing a stand change carriage which can change its direction of travel. In particular, an object of the invention is that of providing a stand change carriage which can be used in as versatile a manner as possible in as many different work plants as possible. In particular, an object of the invention is that of providing a stand change carriage which can be used as autonomously as possible.

This object is achieved by a stand change carriage according to claim 1. Advantageous embodiments of the invention emerge from the dependent claims.

A stand change carriage for simultaneously receiving and transporting a plurality of stands of a rolling mill for rolling metal rods, wires or pipes comprises a plurality of stand places, one of the stands being receivable individually in each of the stand places, and a plurality of steerable wheels for transporting the stands along rails or a rail-less mill floor.

The stand change carriage comprises at least one hydraulic motor, which is operatively connected to at least one of the wheels, in order to drive it.

Hydraulic motors are characterized by their high drive torque. They are thus particularly well suited for moving a heavy stand change carriage. Furthermore, the hydraulic motor offers a more compact design compared with an electric motor having a similar torque. The use of a hydraulic motor thus makes it possible for the size of the wheel arch to be kept comparatively small. If, for example, pivoting of the wheel is made possible by an angular gear mounted on the wheel, the space requirement of the wheel arch does not increase further, despite the additional component, compared with a non-pivotable wheel driven by means of an electric motor.

Furthermore, the small space requirement of the hydraulic motor makes it possible for the installation height of the stand change carriage according to the invention, above the mill floor, to be comparable to the installation height of known stand change carriages which are driven by means of a control cable. The invention thus makes it possible to provide a stand change carriage which is steerable and self-propelled. The stand change carriage is thus not dependent on an external drive, and also not on a rail system, and can thus be used in a more versatile manner than the stand change carriages known from the prior art.

In an advantageous embodiment, the hydraulic motor is a radial piston motor or an axial piston motor. These motor types, and of these two in particular the radial piston motor, have a particularly compact design and allow for a steerable stand change carriage having a particularly low installation height. In particular slow-running radial piston motors have a very compact design and above all have a very small extension in the longitudinal direction. This is preferably less than 0.2 m. In this connection, longitudinal direction means the direction which extends along the axis of rotation of the radial piston motor. If such motors are used, a pivotable drive unit can be implemented by a hydraulic motor and a wheel, which requires a small wheel arch and little clearance around the stand carriage for pivoting.

Preferably, each of the wheels is associated with and operatively connected to its own one of the at least one hydraulic motor. On account of the compact design, it is possible to provide a separate hydraulic motor for each wheel. This in turn multiplies the drive force on the stand change carriage. It is also conceivable to replace a single large motor, which has a comparatively large space requirement and necessitates a minimal installation height of the stand change carriage, by a plurality of smaller hydraulic motors having the same drive force in total, each of said hydraulic motors having a small space requirement. Thus, the minimal installation height can be reduced. Owing to the small size of hydraulic motors, in particular radial piston motors, in this preferred embodiment it is possible to make each of the driven wheels steerable without significant space requirement. However, it can alternatively also be provided that not each of the wheels is provided with its own hydraulic motor.

Preferably, all the wheels are designed to be steerable, in order to perform a change in the direction of travel of at least 30° or more, and more preferably of 90° or more. A stand change carriage comprising such wheels can be moved not only along a forwards and backwards direction, but rather can instantly take a different direction, in particular a direction perpendicular to the original direction of travel. As a result, the stand change carriage can be maneuvered in a particularly simple and space-saving manner, and can also be operated in very tight surroundings. Thus, a plurality of stand change carriages can be positioned in front of a rolling mill, in any desired arrangement, in a very tight space. Alternatively, however, it is also possible for only some of the wheels to be steerable or to be steerable about a smaller steer angle. Thus, an alignment of the stand change carriage based on the rolling mill can be set.

In this case, the contact surfaces of the stand places, on which the stands come to rest after being received in the stand change carriage, are spaced 50 cm or less, preferably 40 cm or less, more preferably 30 cm or less, more preferably 20 cm or less, away from the mill floor. In this way it is possible to ensure, in the case of conventional stands, that the lowest point of the stand is moved just above the mill floor. Alternatively thereto, however, the mill floor can also be provided with depressions, in order to transport the stand at a low height, or the stand can be raised to a higher contact surface by means of a crane or the like, and can be transported at this height.

In a conventional bar rolling mill, the rolling line extends at approximately 0.9 m to 1.1 m above the mill floor, and sometimes even lower. Accordingly, the underside of the stands is routinely located only approximately 0.2 m to 0.3 m above the mill floor. It is therefore desirable for the installation height of the change carriage, in the region of its stand receiving places, to in turn not be higher. Since, according to this preferred feature, the contact surfaces of the stand places on which the stands come to rest after being received in the stand change carriage is spaced 40 cm or less from the mill floor, the stand change carriage can advantageously be used in existing rolling mills without the need for laborious adjustment of the rolling mill or mill floor. In some cases, the lowest point of the stand is a coupling that protrudes downwards. This determines the lowest point. According to the above advantageous feature, the stand change carriage is designed such that said coupling is at only a small safety distance from the ground. However, not all designs of stands have a coupling which protrudes downwards out of the stand, and therefore for these stands a lower contact surface is also possible than is the case for stands having a downwardly protruding coupling of this kind. A low contact surface is advantageous in particular if a control cable-based stand change system is intended to be replaced, and here, on account of the structural situation, the height of the rolling mill above the mill floor is small. Alternatively, the contact surfaces of the stand placed can also be designed to be higher, however.

Preferably, the stand change carriage comprises a steering drive, in order to steer the at least two, preferably all of the, wheels. A stand change carriage of this kind can be operated in a rail-mounted manner or without rails. Thus, in the case of rail-less operation, maneuvering of the stand change carriage and the fixing of its direction of travel is made possible by corresponding positioning of the steering drive. In the case of a rail-mounted stand change carriage, a steering drive is advantageous because then the switches between two stretches of track no longer have to be provided with their own switch actuator in order to bring about steering of the wheels. The wheels of the stand change carriage can, however, also be passively steerable without a steering drive, for example by a rail.

Preferably, the steering drive comprises a chain drive. In this way, a central input for the steering drive can be easily distributed to each steerable wheel of the stand change carriage. Alternatively, however, the steering drive can also be designed differently—in particular, a plurality of drives can be provided, which each steer one wheel.

Further preferably, the steering drive comprises a spindle. This can be incorporated into a chain drive. The spindle makes it possible to ensure that the steering drive is self-locking.

In an advantageous embodiment, the at least one hydraulic motor, together with its associated wheel, is deflectable about a steering axis. The motor and the wheel thus form, as it were, a steerable drive unit. A ring gear is non-rotatably mounted on said drive unit, into which ring gear for example a gear wheel of the steering drive can engage in order to form a gearbox. In this way, the wheel can be steered instantly without significant force application.

Preferably, viewed from above, one of the stand places is arranged between at least two of the wheels, during operation of the stand change carriage. As a result, the installation height of the stand change carriage in the region of the stand place can be kept particularly low, because it is not limited by the space requirement of the wheel arch. It is thus possible to push a stand from a very low stand base of a rolling mill onto the stand place of the stand change carriage, without overcoming a significant height difference.

Preferably, the stand change carriage comprises an energy source, in particular a battery, in order to supply the at least one hydraulic motor with energy. A configuration of this kind renders the stand change carriage independent from an external energy source. Providing supply lines on the stand change carriage, in particular a cable carrier for a cable and the like, can thus be omitted entirely, and the stand change carriage is thereby not limited in its radius of movement. An external energy supply is also possible in principle, however.

Advantageously, the at least one hydraulic motor is part of a closed hydraulic circuit comprising a pump, the hydraulic circuit preferably being designed without a tank. If the hydraulic motor is present in a closed circuit comprising a pump, a pressure can be applied to a hydraulic fluid circulating in the hydraulic circuit, within the closed system, in order to operate the hydraulic motor. It is then for example not necessary to provide a pressure reservoir on the stand change carriage, which has to be constantly charged from outside. Thus, an autonomously functioning stand change carriage can be realized. Omitting a tank allows for a particularly compact design. It may also be advantageous, however, to provide a tank.

Preferably, a battery-operated electric motor is mounted on the stand change carriage, in order to supply the at least one hydraulic motor with hydraulic pressure, and thus drive said motor. This particularly preferred embodiment constitutes a powerful, emission-free, and autonomously functioning variant of a stand change carriage. In this case, the electric motor can be mounted at a point in the stand change carriage which does not impair the installation height of the stand places. The same applies for the battery.

Preferably, the stand change carriage is provided with an inductive charging mechanism. If a rechargeable battery is used as an energy carrier for supplying its electrical components, said battery can thus be charged in a contactless manner. It is for example conceivable to maneuver a stand change carriage, equipped in this way, in a charging zone of the rolling mill or of the stand workshop, in which a mating piece of the inductive charging mechanism is present in or on the ground, when the stand change carriage is to be charged. This charging zone can also be provided directly on the rolling mill, in order to use a point of a particularly high energy requirement and simultaneously relatively long dwell time. As a result, the battery can be of small dimensions.

The stand change carriage preferably comprises a wireless data gearbox device for controlling the stand change carriage. As a result, commands and parameters for its operation can be transmitted to the stand change carriage from an external control system. It is conceivable, for example, for the stand change carriage to move in a remote-controlled manner and as required between different positions in the rolling mill, in the stand workshop, and/or between the rolling mill and the stand workshop. In this case, the control can take place entirely or partially autonomously. It is conceivable, for example, that, in an automated process, a stand change carriage is provided in the stand workshop or the rolling mill when a monitoring system identifies a stand change or finds one to be necessary.

Further preferably, the data gearbox device is configured such that it transmits one or more operating states of the stand change carriage, preferably to a control system and/or to other stand change carriages. Without being limited thereto, the operating states can include the state of charge of a battery, the state of loading with stands, and the position of the stand change carriage. This allows for entirely autonomous operation of the stand change carriage as an “autonomous guided vehicle” or “autonomous mobile robot”. A plurality of stand change carriages can thus exchange their operating states with one another directly and/or indirectly via the control system, in order that said states can also be taken into account during control.

Preferably, the stand change carriage comprises at least four stand places.

Many rolling mills are thus designed such that they comprise four stands arranged one behind the other along the rolling direction. It is therefore particularly advantageous to also provide four stand places for the stand change carriage, in order that, in the case of such stand bases, all the stands can be exchanged simultaneously using the stand change carriage.

Preferably, the stand places are designed for receiving a stand having a hexagonal outside shape, viewed along a rolling direction of the stand. Alternatively, however, the stand places can also be designed for receiving a differently shaped stand, for example a conventional stand having a square outside shape.

In particular in the case of hexagonal stands, but in principle also in the case of square stands, it is the case that couplings of the roller shafts, by means of which the rolling torque is introduced onto the roller shafts, extend obliquely downwards and to the side, from which the stands are exchanged. For this set-up, the above-described stand change carriage can make an additional contribution to the machine safety since it covers these couplings during operation of the rolling mill, if it remains in the stand base during operation of the rolling mill.

Further advantages and developments of the invention emerge from the following description of the figures and all of the claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective side view of a preferred stand change carriage.

FIG. 2 shows the preferred stand change carriage from FIG. 1 from the opposite side.

FIG. 3 shows the preferred stand change carriage from above.

FIG. 4 shows the preferred stand change carriage from below.

FIG. 5 is a side view of the preferred stand change carriage, one stand place being occupied with a stand.

WAYS OF IMPLEMENTING THE INVENTION

FIG. 1 shows a preferred stand change carriage 10 for receiving four stands. For this purpose, the stand change carriage 10 is equipped with four stand places 16 which are all designed to individually receive a stand. The view of FIG. 1 shows the side of the stand change carriage which faces the rolling mill during changing of the stands. Each of the stand places 16 comprises a depression 18 in a main body 11 of the stand change carriage 10, and one slide rail 17 in each case, on either side of the depression 18. On the slide rails 17, the respective stand can be pushed into or lifted onto the stand change carriage 10. The pair of slide rails 17 thus forms the contact surface for a stand housing of a received stand, the depression 18 providing space for parts of the stand protruding from the stand housing, such as a coupling of a roll shaft. Between the stand places 16, the stand change carriage 10 comprises in each case, i.e. in total three, intermediate spaces 28. As will be also described further below, further components, inter alia wheels 20, are arranged in said intermediate spaces 28 on the underside of the stand change carriage 10. On the upper side, the outer intermediate spaces 28 furthermore accommodate, under a cover 27, components of a steering drive, as will be explained in greater detail below.

FIG. 2 shows the stand change carriage 10 from its opposite side. The depressions 18 are closed towards this side, such that the stand change carriage, with the exception of structures on the intermediate spaces 28 and in its rear and front region, has a substantially uniform installation height. In this embodiment, a hydraulic pump 32 is attached at the side, which is driven by an electric motor 33. In principle, the hydraulic pump 32 and/or the electric motor 33 can be accommodated at other points of the stand change carriage 10. The attachment on the side shown is advantageous, however, because these components are not in the way when the rolling mill is approached. The hydraulic pump 32 supplies a hydraulic system of the stand change carriage 10 with a pressurized hydraulic fluid.

Furthermore, a chain drive 22 is provided to the side. The chain drive 22 is part of a steering system which is described in more detail below, and serves to distribute a central input of the steering drive to all the steerable wheels of the stand change carriage.

FIG. 3 shows the stand change carriage 10 from above. In this view, the covers 27 over the two outer intermediate spaces 28 are removed. Thus, the view of a spindle rod 25 is free, which rod is in each case arranged in the intermediate space 28. The spindle rod 25 comprises a spindle 26 in two portions. A sprocket 34 is non-rotatably mounted on the spindle rod 25, to the side of the chain drive 22, into which sprocket the chain drive 22 engages. The spindles 26 in each case mesh with an upper gear wheel 29 which in turn drives a shaft 31 positioned perpendicularly to the drawing plane.

FIG. 4 shows the stand change carriage 10 from below. In this view, the depressions 18 are now raised parts of the main body 11 of the stand change carriage 10. Enough space is present in the intermediate spaces 28 to provide drive units 24 consisting in each case of a wheel 20 and a hydraulic motor 21. The hydraulic motors 21 are incorporated, in a manner conventional in the art, in the hydraulic system of the stand change carriage 10. For the sake of improved clarity, the necessary hydraulic lines are not shown. Overall, the stand change carriage 10 comprises four structurally identical drive units 24, of which in each case two share one of the intermediate spaces 28. In this embodiment, the hydraulic motor 21 of the drive unit 24 is designed as a radial piston motor, the dimensions of which in the longitudinal direction are smaller than 20 cm. The drive unit 24 is therefore very compact overall. Furthermore, a ring gear 23 is mounted on the drive unit 24. Each drive unit 24 can be rotated, together with its ring gear 23, about a steering axis perpendicular to the drawing plane. Owing to the compact design, the drive unit 24 can rotate about the steering axis about 360°, despite the small intermediate space 28, without colliding with the main body 11 of the stand change carriage 10. The direction of travel of each wheel 20 can thus be set as desired, as a result of which the stand change carriage 10 can perform any desired change of direction of travel instantly. In the position shown in FIG. 3, all the wheels 20 face perpendicularly to a longitudinal direction of the stand change carriage, along which the stands are lined up. In the position shown, the stand change carriage can thus be moved towards a rolling mill from the side. A lower gear wheel 30 meshes with the ring gear 23 of each drive unit, such that the respective drive unit 24 is rotated about its steering axis by a rotation of the lower gear wheel 30. Thus, a total of four such lower gear wheels 30 are provided, which are part of the steering drive of the stand change carriage 10. Each lower gear wheel 30 is connected via the shaft 31 to an associated upper gear wheel 29 and thus connected to the chain drive 22. The mechanism is adapted such that, during operation of the chain drive 22, it steers the wheels 20 synchronously in an aligned orientation. Embodiments are also conceivable, however, in which additionally or alternatively in each case only the two wheels 20, which share an intermediate space 28 or which are arranged on one side of the stand change carriage 10, can be steered independently of the other two wheels 20. It is thus for example possible, in an efficient manner, to turn the stand change carriage 10. Preferably, for this purpose, the directions of rotation of the individual hydraulic motors can also be set differently from one another. The chain drive 22 can be driven hydraulically, for which purpose it is incorporated into the hydraulic system, but driving using an electric motor is also possible.

A battery 35 or a battery pack is arranged in the central intermediate space 28, which battery or battery pack supplies power to the electric motor 33 and other electrical components. The stand change carriage 10 shown can thus travel entirely autonomously.

FIG. 5 shows the preferred stand change carriage 10 from the side which faces the rolling mill in the case of a stand change, a stand 13 being received on the left-hand stand place 16 in the viewing direction. It is clear that a coupling 15 of the stand 13 protruding from the stand housing 14 finds space in the depression 18 of the stand place 16. In this view, a mill floor H comprising rails S embedded therein is also sketched, on which rails the wheels 20 of the stand change carriage roll. In this embodiment, the installation height B of the stand places 16, i.e. a distance between the contact surface of the stand places 16 and the mill floor H, is 39 cm.

LIST OF REFERENCE NUMBERS

• • 10 stand change carriage
  • 11 main body
  • 13 stand
  • 14 stand housing
  • 15 coupling
  • 16 stand place
  • 17 slide rails
  • 18 depression
  • 20 wheel
  • 21 hydraulic motor
  • 22 chain drive
  • 23 ring gear
  • 24 drive unit
  • 25 spindle rod
  • 26 spindle
  • 27 cover
  • 28 intermediate space
  • 29 upper gear wheel
  • 30 lower gear wheel
  • 31 shaft
  • 32 hydraulic pump
  • 33 electric motor
  • 34 sprocket
  • 35 battery
  • H mill floor
  • S rails
  • B installation height

Claims

1. A stand change carriage for simultaneously receiving and transporting a plurality of stands of a rolling mill for rolling metal rods, wires, or pipes, the stand change carriage comprising:

a plurality of stand places, wherein one of the stands is receivable individually in each of the stand places;

a plurality of steerable wheels for transporting the stands on rails or along a rail-less mill floor, and

at least one hydraulic motor operatively connected to at least one of the wheels such that the hydraulic motor drives the stand change carriage.

2. The stand change carriage according to claim 1,

wherein the hydraulic motor is a radial piston motor or an axial piston motor.

3. The stand change carriage according to claim 1,

wherein each of the wheels is operatively connected to a respective hydraulic motor of the at least one hydraulic motor.

4. The stand change carriage according to claim 1,

wherein at least two of the wheels are steerable, such that the at least two of the wheels are able to perform a change in direction of travel of at least 30°.

5. The stand change carriage according to claim 1, wherein contact surfaces of the stand places have an installation height of 50 cm or less above the mill floor.

6. The stand change carriage according to claim 1, further comprising:

a steering drive configured to steer at least two wheels,

wherein the steering drive comprises a chain drive.

7. The stand change carriage according to claim 6,

wherein the at least one hydraulic motor and an associated wheel form a drive unit which is pivotable about a steering axis and on which a ring gear is non-rotatably mounted.

8. The stand change carriage according to claim 1,

wherein at least one of the stand places is arranged between at least two of the wheels during operation of the stand change carriage when viewed from above.

9. The stand change carriage according to claim 1, further comprising

an energy source configured to supply the at least one hydraulic motor with energy.

10. The stand change carriage according to claim 1,

wherein the at least one hydraulic motor is part of a closed hydraulic circuit comprising a pump, and

wherein the hydraulic circuit is configured to not include tank.

11. The stand change carriage according to claim 1,

wherein a battery-operated electric motor is mounted on the stand change carriage and is configured to supply the at least one hydraulic motor with hydraulic pressure, such that the hydraulic pressure drive the battery-operated electric motor.

12. The stand change carriage according to claim 1, further comprising an inductive charging mechanism.

13. The stand change carriage according to claim 1, further comprising a wireless data gearbox device for controlling the stand change carriage.

14. The stand change carriage according to claim 1,

wherein the stand change carriage comprises at least four stand places.

15. The stand change carriage according to claim 1,

wherein the stand places are configured to receive a stand having a hexagonal outside shape when viewed along a rolling direction of the stand.

16. The stand change carriage according to claim 1, wherein all of the wheels are steerable, such that all of the wheels are able to perform a change in direction of travel of at least 30°.

17. The stand change carriage according to claim 4, wherein the at least two of the wheels are able to perform a change in direction of travel of at least 90°.

18. The stand change carriage according to claim 1, wherein contact surfaces of the stand places have an installation height of 40 cm or less above the mill floor.

19. The stand change carriage according to claim 6, wherein the steering drive is configured to steer all of the wheels.

20. The stand change carriage according to claim 13, wherein the data gearbox device is configured to transmit operating states of the stand change carriage.