JP3285805B2 - Rolling mill drive device and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus for a rolling mill and a method for controlling the same, and more particularly, to a driving apparatus for a rolling mill using a joint assembly utilizing a tightening torque generated by hydraulic pressure and a method for controlling the same.

[0002]

2. Description of the Related Art In a driving device of a general rolling mill,
The rolling torque of the main motor is transmitted to the rolling roll via each gear of the drive reduction gear and the spindle coupling. Here, the strength of the driving system is generally
Although it is set in consideration of the safety factor with respect to the maximum rolling torque, in the case of a rolling mill, torque fluctuation and excessive load due to plate breakage and the like may occur, and it is necessary to increase the driving system strength. A problem that arises when increasing the drive system strength is the strength of the spindle. Generally, in the case of a spindle, especially a universal joint type spindle coupling, each element of the cross pin portion, for example,
Each strength of cross pin, cap bolt, cap, etc.
It is necessary to increase the strength of the needle bearing.
In order to increase these strengths, it is necessary to increase the swing diameter of the universal joint.

However, in recent years, with the development of rolling mills having small-diameter work rolls such as HC mills and UC mills,
Due to the restriction on the mill side, the swing diameter of the universal joint is restricted. Therefore, in a universal joint spindle of a rolling mill having a small-diameter work roll, the drive system cannot be protected against excessive load by increasing the swing diameter.
An overload prevention device is installed in the drive system.

[0004] In a conventional rolling mill drive device, a mechanism using a shear bolt is known as an overload prevention device for preventing a drive system from being damaged due to overload caused by excessive acceleration / deceleration, plate breakage, or other factors. ing. Sher bolt is a gear coupling that connects the mill drive reduction gear and the main motor,
Alternatively, it is used for a universal joint type or gear coupling type spindle coupling that connects a drive reduction gear and a mill roll.

[0005] The shear bolt has a structure in which the neck portion is the weakest portion in terms of strength, and the breaking set torque value is set by arbitrarily setting the shear strength of the neck portion. The drive system is protected from overload torque by setting the break set torque of the shear bolt to a torque value having an arbitrary safety factor with respect to the weakest part of the drive system.

However, it is necessary to set the fatigue strength of the neck portion of the shear bolt to a value having a safety factor with respect to the nominal stress caused by the normal transmission torque during rolling. A strength higher than the required neck strength determined from the weakest part strength of the system is required. Therefore, the breaking set torque is inevitably high. Considering that the drive system weakest part strength is determined by a value having a safety factor further to the set breaking torque, the drive system has high strength,
That is, the size and weight are increased.

[0007] Also, due to the variation of the breaking strength of the shear bolt due to individual differences, it is necessary to take a set value having a margin with respect to the lowest point of the individual difference range.

[0008] In addition, due to the aging of the shear bolt, etc., not only the pure shear stress but also the bending stress of the neck of the shear bolt is applied, and the fracture is performed with a lower torque than the initially set fracture torque. there's a possibility that.

[0009] Accordingly, it is necessary to unnecessarily expand the limit torque on the strength of the drive system and the set torque at break. This is conversely considered when the strength of the drive system is mainly considered.
Since the fracture setting torque value is used with a lower fracture setting torque value, and the fracture setting torque value approaches the normal transmission torque in rolling, the limitation on the strength at the shear fatigue limit of the shear bolt neck portion increases.

As a method of solving such a problem of the shear bolt, for example, a tightening torque generated by hydraulic pressure described in Japanese Patent Application Laid-Open No. 52-102965 and Japanese Patent Application Laid-Open No. 55-10191 is used. A driving device of a rolling mill using a joint assembly is known.

In the joint assembly, an inner sleeve exists so as to be sandwiched between the coupling and the outer sleeve, and the outer sleeve expands to the inner surface by the oil pressure in the hydraulic chamber. Between them, a surface pressure is generated by the tightening force of the outer sleeve, and torque can be transmitted by a frictional force. When an overload occurs, the coupling and the inner sleeve will slip and break the shear plug if the overload torque is larger than the holding torque due to the surface frictional force due to the static friction coefficient between the coupling and the inner sleeve. To relieve hydraulic pressure.

[0012]

However, in the above-mentioned joint assembly utilizing the tightening torque generated by the hydraulic pressure, the release torque at the time of overload is set by the set value of the set pressure of the hydraulic chamber. However, since the oil is supplied from the oil nipple to the hydraulic chamber, it is difficult to change the oil pressure frequently, and there is a problem that the set value cannot be arbitrarily changed according to various rolling conditions. .

An object of the present invention is to provide an overload torque
An object of the present invention is to provide a rolling mill drive device and a control method thereof that can cancel torque transmission at an arbitrary set torque value.

[0014]

(1) In order to achieve the above object, the present invention provides a drive unit for reducing the input torque from a motor and transmitting the same, and transmitting the output torque of the drive unit to a mill roll. A driving device for a rolling mill, comprising: a spindle; and an overload prevention device, which is disposed between an output shaft of the driving device and the spindle and has a joint assembly using a tightening torque generated by hydraulic pressure. A rotary joint provided on the output shaft, a hydraulic pump for supplying oil to the joint assembly via the rotary joint, a flow path connected to the joint assembly from the hydraulic pump, and a hydraulic pump connected to the joint assembly. A direction control valve for switching a flow path for oil relief, a torque detector for detecting a torque of the output shaft of the spindle or the drive unit, and a preset torque transmission cutoff setting When the detected torque value is greater than the torque value, the flow path of the directional control valve is switched to relieve oil from the joint assembly, and a plurality of torque transmission cutoff setting torque values corresponding to rolling conditions are provided. And control means for selecting these torque transmission cutoff set torque values according to rolling conditions. With this configuration, it is possible to cancel the torque transmission at an arbitrary set torque value with respect to the overload torque.

(2) In the above (1), preferably,
Further, the control means includes a cut-out detecting means for detecting the cut-out of the plate rolled by the mill roll, and switches the flow path of the direction control valve when the cut-out detecting means detects the cut-out. Thus, oil from the joint assembly is relieved. With this configuration, torque transmission can be released even when the plate is cut.

(3) In the above (1), preferably,
The drive unit is configured to transmit torque by pressing the rollers, and when the detection unit detects an overload state, the second control unit reduces the pressing force of the roller to cut off the torque transmission. Means, wherein the set value when the control means relieves oil from the joint assembly is made smaller than the set value when the second control means interrupts torque transmission. . With this configuration, the safety of protection of the drive system at the time of overload can be improved.

(4) In order to achieve the above object, the present invention provides an output shaft of a drive for transmitting input torque from a motor at a reduced speed, and a spindle for transmitting output torque of the drive to a mill roll. A method for controlling a drive device of a rolling mill having an overload prevention device having a joint assembly using a tightening torque generated by hydraulic pressure, the torque of the spindle or the output shaft of the drive device being detected between When the detected torque value is larger than the preset torque transmission cutoff set torque value, the oil from the joint assembly is relieved and a plurality of torque transmission cutoff set torque values corresponding to rolling conditions are provided. ,
These torque transmission cutoff set torque values are selected according to rolling conditions. According to such a method, the torque transmission can be released at an arbitrary set torque value with respect to the overload torque.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A driving device for a rolling mill according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a structural view showing the entire configuration of a rolling mill driving device according to one embodiment of the present invention, and FIG. 2 is an enlarged view of an overload prevention device used in the rolling mill driving device according to one embodiment of the present invention. FIG.

In FIG. 1, a mill roll 1 for rolling a plate
0A is supported by bearings 12A and 14A, and mill roll 10B is supported by bearings 12B and 14B. At the shaft end of the mill roll 10A,
The spindle 20A is connected via a cross pin joint 18A of the coupling 16A. A spindle 20 is connected to the shaft end of the mill roll 10B via a cross pin joint 18B of the coupling 16B.
B is connected.

The spindle 20A is connected to the output gear shaft 3 of the drive reduction gear via a cross pin joint 22A.
2A. The spindle 20B is connected to an output gear shaft 32B of the drive reduction gear via a cross pin joint 22B. Output gear shaft 32A is coupled to output gear shaft 32B, and output gear shaft 32B is coupled to input gear shaft 34. The output gear shafts 32A and 32B and the input gear shaft 34 have bearings 36 and 3 respectively.
6 ′, 37, 37 ′, 38, 38 ′ support the drive shaft casing 30.

The input gear shaft 34 is connected to a mill motor 40 via a gear coupling 42. The driving force of the mill motor 40 is controlled by the input gear shaft 34, the output gear shafts 32A and 32B, the spindles 20A and 20B.
Via B, it is transmitted to the mill rolls 10A and 10B, and the mill rolls 10A and 10B are driven.

Here, as a mechanism for protecting the drive system when an overload torque such as biting between the mill rolls 10A and 10B or torque circulation due to a difference in roll diameters is generated,
The overload prevention devices 100A and 100B
A, 20B and output gear shafts 32A, 32B, respectively. Overload prevention device 100A, 10
The detailed structure of 0B will be described later with reference to FIG.
The structure includes a joint assembly using a tightening torque generated by hydraulic pressure.

Next, the overload prevention devices 100A, 100B
Will be described. The oil set to a higher pressure than the hydraulic pump 50 passes through a pressure reducing valve 52 and is controlled by pressure control cells 56A and 56B by directional control valves 54A and 54B.
Control is performed so that the oil supply oil pressure value detected by B becomes a desired oil pressure (oil pressure at the set release torque). Pressure reducing valve 5
2. Directional control valves 54A, 54B and pressure cell 56
A and 56B are connected by an oil supply pipe 58, respectively. In addition, it is also possible to install a flow control valve having high response characteristics instead of the directional control valves 54A and 54B.

The oil discharged from the direction control valves 54A and 54B is connected to the rotary joints 60A and 60B via an oil supply pipe 58. Since the drive system is a rotating body,
Rotary joint 6 that can supply oil to a shaft having a rotation difference
By providing the gear output shafts 32A, 32B at the center of the mill motor side end of the gear output shafts 32A, 32B,
Oil can be supplied to oil supply holes 62A and 62B provided at the center of 2B. The oil supply holes 62A and 62B are connected to the overload prevention device 100 via oil supply pipes 64A and 64B.
A, 100B and the overload prevention device 100
A, 100B can be supplied with a desired oil pressure.

In this embodiment, as the means for detecting the transmission torque, the spindles 20A and 20B are provided with torque detectors 80A and 80B. The output gear shafts 32A and 32B have a torque detector 82
A, 82B are provided. Torque detector 80A, 8
Reference numerals 0B, 82A, and 82B detect torque values from the torsion stress of the shaft portions of the spindles 20A and 20B or the gear shafts 32A and 32B. Torque detector 80
The torques detected by A, 80B, 82A, and 82B are input to control means 200. Torque detector 80A,
As a method of transmitting the detection signal from 80B, 82A, 82B to control means 200, a non-contact type using an FM transmitter and a contact type using a slip ring are used.

The control means 200 includes a torque detector 80A,
The torque detected by 80B, 82A, 82B is
When the torque becomes larger than the preset torque transmission cutoff set torque, the direction control valves 54A and 54B are controlled to relieve the oil supplied to the overload prevention devices 100A and 100B to the tank 59 side, and the spindle 20A , 20
The power transmission between B and the output gear shafts 32A and 32B is shut off to protect the drive system.

The host computer 300 controls the rolling mill, controls normal rolling and acceleration / deceleration, and sends a rolling condition signal indicating normal rolling and acceleration / deceleration. 200. The control means 200 changes the torque transmission cutoff set torque based on the rolling condition signal input from the host computer 300. For example, during normal rolling, the torque transmission cutoff set torque is set to a torque value obtained by multiplying a required rolling torque by a safety factor. At the time of acceleration / deceleration, the torque transmission cutoff set torque is set to a torque value larger than the set torque value during normal rolling. In this way, by controlling the hydraulic pressure according to various rolling conditions, it is possible to arbitrarily set a desired set breaking torque.

The torque detectors 80A, 80B and
Only one of the torque detectors 82A and 82B may be used. Further, the torque detector may be a method other than the method of detecting the torsion stress of the shaft.

Further, in this embodiment, there is provided a plate breakage detecting means 90 for detecting a plate breakage. As the cutout detecting means 90, for example, a tensiometer is used to detect a cutout when the tension detected by the tensiometer becomes zero, or to detect a cutout based on a signal from the thickness gauge. The cut-out signal detected by the cut-out detecting means 90 is input to the control means 200.

When the plate breakage detecting means 90 detects the plate breakage, the control means 200 controls the direction control valves 54A, 54A.
54B by controlling the overload prevention devices 100A and 100B.
To the spindle 20
A, 20B and the power transmission between the output gear shafts 32A, 32B are shut off to protect the drive system.

The return operation after the torque transmission is released can be easily performed by switching the direction control valves 54A and 54B using the control means 200 and increasing the hydraulic pressure supplied to the overload prevention devices 100A and 100B. Therefore, no human work is required for restoration, and the equipment productivity is improved.

Further, when the transmission torque exceeds the set value of the overload torque, the hydraulic pressure is released until the transmission torque becomes lower than the torque transmission cutoff set torque value. The aging of the friction coefficient of the overload protection device using the joint assembly using the torque is not affected at all, and stable overload transmission release is possible.

With respect to the circulating torque between the upper and lower spindles and the overload torque due to the cobble to one side mill roll, a means for detecting the rotational speed of the upper and lower spindles is provided, and the hydraulic pressure is released from the vertical rotational difference. It can also be controlled.

Next, the structure of the overload prevention device 100 including the joint assembly using the tightening torque generated by the hydraulic pressure according to the present embodiment will be described with reference to FIG. Note that the same reference numerals as those in FIG. 1 indicate the same parts, and the overload protection device 100 is the same as the overload protection device 100 shown in FIG.
A, 100B.

The overload prevention device 100 is provided between the spindle 20 and the output gear shaft 32 connected via the cross pin joint 22, and
When an overload torque is generated at 0, power transmission between the spindle 20 and the output gear shaft 32 is cut off. For this purpose, the overload prevention device 100 has a structure including a joint assembly utilizing a tightening torque generated by hydraulic pressure.

The joint assembly includes a cross pin joint 2
2, an inner sleeve 120 connected to the output gear shaft 32, and an inner sleeve 1.
20 and an outer sleeve 130 fitted with an appropriate interference. There is an appropriate gap between the coupling 110 and the inner sleeve 120. The coupling 110 is supported by the outer sleeve 130 by a bearing 140 and is supported by the inner sleeve 120 by a bearing 145.

Inside the outer sleeve 130, a hydraulic chamber 132 is provided on the circumference. Hydraulic chamber 13
2 is connected to the oil supply pipe 64 by a pipe joint 150,
The fuel supply pipe 64 is connected to a fuel supply hole 62 provided in the output gear shaft 32 by a pipe joint 152. The oil supply hole 62 is connected to the hydraulic pump 50 as described with reference to FIG.

Since the hydraulic chamber 132 is provided at a position where the inner side is thinner than the outer side, when the hydraulic pressure is applied, the outer sleeve 130 expands to the inner side which is weaker in strength. Due to this expansion action, between the coupling 110 and the inner sleeve 120, between the inner sleeve 120 and the outer sleeve 13
A surface pressure corresponding to the oil pressure value is generated on each contact surface between 0 and a frictional force is generated. By this friction force, torque is transmitted between the output gear shaft 32 and the spindle 20.

Here, by appropriately setting the set value of the hydraulic pressure supplied to the hydraulic chamber 132, the coupling 110 and the inner sleeve 120 can be set at a desired set torque.
The contact surface pressure disappears, the gap returns to the initial clearance, and slippage occurs between the coupling 110 and the inner sleeve 120, so that torque transmission is completely interrupted, and protection of the drive system at the set torque value is achieved. It becomes possible.

At this time, the oil groove 1 is
12 is formed, and the lubricating oil sealed therein adheres to the contact surface between the coupling 110 and the inner sleeve 120 together with the release of the hydraulic pressure, thereby preventing seizure due to a rotation difference. Further, the coupling 110 and the inner sleeve 1
Due to the bearings 140 and 145 provided between the outer sleeve 130 and the outer sleeve 130, the contact portion has a structure in which a load surface pressure due to its own weight is not generated.

As described above, according to this embodiment, by changing the hydraulic pressure supplied to the hydraulic chamber, the torque transmission cutoff set torque is arbitrarily set according to the rolling conditions, and the torque transmission is released. It becomes possible. Therefore, the drive system can be extremely stably protected against the overload torque with high accuracy, so that the safety factor of the drive system can be minimized, the swing diameter of the spindle can be minimized, and the mill roll can be minimized. Small diameter,
The drive system can be reduced in weight and size.

Further, it is possible to easily perform a return operation after the torque transmission is released.

Further, there is no influence on the secular change of the friction coefficient of the overload protection device, and the transmission can be stably released at the time of overload.

Next, a driving apparatus for a rolling mill according to another embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 4 is a structural diagram illustrating an overall configuration of a driving device for a rolling mill according to another embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same parts. Further, an overload prevention device 100 having a joint assembly utilizing a tightening torque generated by hydraulic pressure
The configurations of A and 100B are the same as those described in FIG.

In the embodiment shown in FIG. 1, a power transmission mechanism using gears is used as the pinion stand or the pinion stand speed reducer for driving the spindle. On the other hand, in this embodiment, the rollers are mutually connected. A mechanism for pressing is provided to apply a tangential load between the rollers, and a mechanism for transmitting torque from the main driving roller to the driven roller by a frictional force based on the tangential load is used.

The three-roller type drive speed reducer according to the present embodiment has bearings 76, 7 in a drive device casing 70.
It comprises an input drive roller shaft 74 supported by 6 ', 77, 77', 78, 78 ', an upper output drive roller shaft 72A, and a lower output drive roller shaft 72B.

The input drive roller shaft 74, the upper output drive roller shaft 72A, and the lower output drive roller shaft 72B are subjected to bearings 76, 7 by a pressing force F between the input and output rollers.
The contact surface pressure is applied to each roller contact portion by pressing it through a bearing box supporting 6 ′, 77, 77 ′, 78, 78 ′. This is a structure in which torque is transmitted by a tangential force due to circumferential frictional resistance of the contact surface. As the pressing force F increases, the allowable tangential force increases, that is, the allowable transmission torque increases.

The control means 210 controls the pressing force F and controls the torque detectors 80A, 80B, 82A, 82B.
When the torque detected by the above becomes larger than a preset torque transmission cutoff set torque, the pressing force F is controlled to protect the drive system against overload torque.

Further, in this embodiment, in the same manner as described with reference to FIG. 1, an overload prevention device 1 including a joint assembly utilizing a tightening torque generated by hydraulic pressure is provided.
ooA, 100B. Mill roll 10A, 1
When an overload torque exceeding the cutoff set torque is generated at 0B, the control means 200 controls the overload prevention device 100 including the joint assembly using the tightening torque generated by the hydraulic pressure.
To reduce the supply hydraulic pressure to protect the drive train from overload torque.

The roller type driving machine is free from meshing vibration caused by a gear which is one of the causes of chatter marks on the material to be rolled, and is an effective technique in recent fine steel rolling and the like. However, the control for releasing the torque transmission of the roller type driving machine by controlling the pressing force F at the time of overload is as follows.
Since uneven wear of the roller surface is involved, it is necessary to minimize it.

Therefore, in this embodiment, the torque transmission cutoff set value T1 by the overload prevention devices 100A and 100B is changed to the torque transmission cutoff set value T in the roller type driving machine.
2, an overload protection device 100 including a joint assembly using a tightening torque generated by hydraulic pressure is set for the overload torque by setting T1 <T2 low.
A and 100B protect the drive system, so that uneven wear and the like on the roller surface during the torque transmission releasing operation of the roller type driving machine can be minimized.

Further, since the roller type driving device also functions as a safety device when the overload prevention devices 100A and 100B including the joint assembly utilizing the tightening torque generated by the hydraulic pressure are not operated, the driving device protection function is provided. Can be further improved.

In the above description, a three-roller type roller driving device has been described, but the present invention can be similarly applied to a four-roller type roller driving device and a two-roller type driving device. .

As described above, according to the present embodiment, by changing the hydraulic pressure supplied to the hydraulic chamber, the torque transmission cutoff set torque is arbitrarily set according to the rolling conditions, and the torque transmission is released. It becomes possible. Therefore, the drive system can be extremely stably protected against the overload torque with high accuracy, so that the safety factor of the drive system can be minimized, the swing diameter of the spindle can be minimized, and the mill roll can be minimized. Small diameter,
The drive system can be reduced in weight and size.

Further, it is possible to easily perform a return operation after the torque transmission is released.

Further, there is no effect on the secular change of the friction coefficient of the overload protection device, and the transmission can be stably released at the time of overload.

Further, by providing a double overload protection mechanism, the safety of overload protection can be improved.

[0058]

According to the present invention, it is possible to cancel torque transmission at an arbitrary set torque value with respect to overload torque.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing an overall configuration of a driving device for a rolling mill according to an embodiment of the present invention.

FIG. 2 is an enlarged structural view of an overload prevention device used in a driving device of a rolling mill according to an embodiment of the present invention.

FIG. 3 is a structural view showing an overall configuration of a driving device for a rolling mill according to another embodiment of the present invention.

[Explanation of symbols]

10A, 10B: Mill roll 12, 14, 36, 37, 38, 76, 77, 78 ... Bearing 16A, 16B ... Coupling 18A, 18B, 22A, 22B ... Cross pin joint 20A, 20B ... Spindle 30, 70 ... Driving machine Casing 32A, 32B ... output gear shaft 34 ... input gear shaft 40 ... motor 42 ... gear coupling 50 ... hydraulic pump 52 ... pressure reducing valve 54A, 54B ... directional control valve 58 ... oil supply pipe 59 ... tank 60A, 60B ... rotary joint 62 ... oil supply hole 72A ... upper output drive roller shaft 72B ... lower output drive roller shaft 74 ... input drive roller shaft 80A, 80B, 82A, 82B ... torque detector 90 ... plate breakage detecting means 100 ... overload prevention device 110 ... coupling 112 ... oil groove 120 ... inner sleeve 30 ... outer sleeve 132 ... hydraulic chamber 150, 152 ... pipe fittings 200, 210 ... control unit 300 ... host computer

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takayoshi Matsuyama 3-1-1, Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Yoshihiro Maekawa 3-1-1, Sachimachi, Hitachi-City, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (56) References JP-A-11-10214 (JP, A) JP-A-11-10213 (JP, A) JP-A-11-2254 (JP, A) 8-226452 (JP, A) JP-A-11-704 (JP, A) JP-A-7-96306 (JP, A) JP-A-4-3444811 (JP, A) JP-A-55-10191 (JP, A) A) JP-A-7-98020 (JP, A) JP-A-5-39704 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 35/14 B21B 37/00 F15B 20 / 00 F16D 1/00

Claims (4)

(57) [Claims] A drive for transmitting the input torque from the motor at a reduced speed; a spindle for transmitting the output torque of the drive to the mill roll; and a spindle disposed between the output shaft of the drive and the spindle.
A drive device for a rolling mill having an overload prevention device having a joint assembly utilizing a tightening torque generated by hydraulic pressure, a rotary joint provided on an output shaft of the drive machine, and the joint via the rotary joint. A hydraulic pump for supplying oil to the assembly, a flow path connected to the joint assembly from the hydraulic pump, and a directional control valve for switching a flow path for relieving oil from the joint assembly; A torque detector that detects a torque of an output shaft of the driving device; and a torque control device that switches a flow path of the directional control valve when the detected torque value is larger than a preset torque transmission cutoff set torque value, and It has a plurality of torque transmission cutoff setting torque values according to rolling conditions while relieving oil from the assembly. Drive of the rolling mill, wherein a control means for selecting a torque value. 2. The driving device for a rolling mill according to claim 1, further comprising a cut-out detecting means for detecting a cut-out of a plate rolled by said mill roll, wherein said control means includes a cut-off detecting means. A drive device for a rolling mill, wherein when a plate break is detected, the flow path of the directional control valve is switched to relieve oil from the joint assembly. 3. The driving device for a rolling mill according to claim 1, wherein the driving device is configured to transmit torque by pressing the rollers, and when the detecting unit detects an overload state, A second control means for reducing the pressing force of the roller to cut off the torque transmission, wherein the control means sets a value for relieving oil from the joint assembly; A driving device for a rolling mill, wherein the set value is smaller than a set value at the time of shutting off. 4. An output shaft of a drive for transmitting the input torque from the motor at a reduced speed and a spindle for transmitting the output torque of the drive to the mill roll.
In a control method of a driving device of a rolling mill having an overload prevention device having a joint assembly using a tightening torque generated by hydraulic pressure, a torque of the spindle or an output shaft of the driving machine is detected and set in advance. When the detected torque value is larger than the torque transmission cutoff set torque value, the oil from the joint assembly is relieved, and a plurality of torque transmission cutoff set torque values corresponding to the rolling conditions are provided. A method for controlling a driving device for a rolling mill, wherein the torque transmission cutoff setting torque values are selected.