JP2019030830A - Method for repairing roller of vertical type mill - Google Patents

Abstract

To obtain a method for reliably repairing a roller without breaking a motor and a torque arm of the motor, and by performing connection of the motor or the like more easily and in a shorter period of time.SOLUTION: There is provided a method for repairing a roller of a vertical type mill that includes a table liner which is rotated by a vertical shaft and a roller which comes into contact with a surface of the table liner and can be rotated by transmission of a rotation force of the table liner thereto, and to the one side of which a rotary shaft is connected, and in the mill, an object to be crushed enters between the table liner and the roller, and is crushed. In the method, a rotary shaft of a motor is connected to a surface of the roller on a side on which the rotary shaft is not provided, a motor body displacement regulation member is fixed to a motor body without fixation of the motor body to a component other than the roller, the rotary shaft of the motor is rotated, build-up welding by a metal is performed to a surface of the roller, which faces a surface of the table liner, and the roller surface is repaired.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a repair method by overlay welding of a vertical mill.

The vertical mill is used for the purpose of pulverizing the object to be crushed, such as coal and slag, and the object to be crushed between the table rotated by the vertical axis and the upper surface of the table liner fixed on the table. Is a kind of pulverizing apparatus having a roller for pulverizing the material.
As such a vertical mill is operated, the surface of the table liner and the roller surface in contact with the object to be crushed are worn. When worn, the crushing efficiency is lowered, and in some cases, the table liner and the roller may be damaged.
For this reason, metal is welded to the table liner surface and the roller surface, and repair is performed to recover these surface shapes.
Usually, a motor for rotating the table is connected to the lower side of the table liner. During the repair, the table is rotated while the roller surface is separated from the table liner surface. Overlay welding can be performed on the liner surface.
However, for the operation of the vertical mill, it is not necessary to connect a motor to the rotating shaft of the roller, but it is necessary to rotate only the roller specially when repairing the roller surface.

For this reason, as described in Patent Document 1, for example, a motor is connected to the opposite side of the roller to which the rotary shaft is originally connected, that is, the center side of the table liner, and the motor is fixed by a torque arm. It was necessary to perform repairs.
The connection form of such a motor was the same in the methods described in Patent Documents 2 and 3.
Further, as described in Patent Document 4, a method of directly rotating a rotation shaft originally provided on a roller is also known. However, there is a tendency to increase the size of the device required for rotation, such as the need to transmit driving force to the rotating shaft with a chain or the like.

JP 2005-95842 A JP-A-4-284858 JP-A-11-267536 Japanese Utility Model Publication No. 7-17340

In the above-described background art, when the rotation shaft of the motor can be accurately connected to the rotation shaft of the roller, the rotation shaft of the motor can be smoothly rotated and thus the roller can also be rotated.
At this time, at the time of repairing the roller, when the roller separated from the table liner is rotated by the motor connected to the opposite surface, the roller itself is supported by the bearing. Accurate rotation is possible. When the motor is fixed by the torque arm, the direction of the force applied to the torque arm remains only in the direction opposite to the rotation direction of the rotation shaft of the motor.

However, in many cases, a roller used in a vertical mill has a rotating shaft connected to only one side thereof, and the opposite side has, for example, a smooth surface or a hemispherical surface. May not have been. As a result, there is no rotating shaft on the opposite side, so when installing the motor, the rotating shaft of the motor cannot be accurately connected to the rotating shaft of the roller, and the rotating shaft of the motor does not match the rotating shaft of the roller. There is. As a result, the rotating shaft of the motor is connected at a position eccentric from the rotating shaft of the roller, the rotating shaft of the motor is connected obliquely with respect to the rotating shaft of the roller, and these connection states are It is connected in a composite manner.
In such a connection, the motor body includes the motor body and / or the gear box installed between the motor and the roller, and the rotational movement that is eccentric by the rotation shaft, or the connection point between the motor rotation shaft and the roller is the apex. Rotate in a conical shape or a combination of these rotations.
At that time, if the motor is fixed by the torque arm as in the above background art, the force due to such rotational motion is received, and an unplanned force is applied between the motor, the fixing portion by the torque arm, and the roller, There is a high possibility that the motor, torque arm, etc. will be damaged.

Therefore, conventionally, the rotation shaft of the motor is accurately connected to the rotation shaft of the roller to prevent the rotation force from being applied to the entire motor device including the motor body and the gear box, and to prevent these damages. Was necessary. However, such an accurate connection requires precise adjustment work in a narrow space at the site, and the work takes a long time.
It is an object of the present invention to provide a method for reliably repairing a roller without damaging the motor or the torque arm of the motor, and making the connection of the motor, etc. easier and in a shorter time. .

In order to solve the above problems, the present invention employs the following method.
Supplied with a table liner that rotates by a vertical shaft, and a roller that is rotatable by contact with the table liner and transmitting the rotational force of the table liner, and having a rotating shaft connected on one side A roller repair method for a vertical mill in which an object to be crushed is pulverized by entering between the table liner and the roller,
Connect the rotating shaft of the motor to the surface of the roller where the rotating shaft is not provided,
Without fixing the motor body to a member other than the roller, the motor body displacement regulating member is fixed to the motor body,
A method of repairing the roller surface by rotating the rotating shaft of the motor and performing overlay welding with a metal on the surface of the roller facing the table liner surface.

According to the present invention, when the roller surface of the vertical mill is repaired, the motor fixed to the roller directly or via the gear box is not damaged.
Further, since the member rotated by the motor is a single roller and is a rotation for performing overlay welding on the roller surface, a small rotation speed can be achieved with a small motor. Therefore, the miniaturized motor can be connected to the surface on the center side of the roller vertical mill, that is, in a narrow space. It is necessary to install equipment for overlay welding on the inner surface of the vertical mill. This eliminates the need for work on the rotary shaft provided on the roller toward the outside of the vertical mill, and thus minimizes the work of disassembling the vertical mill apparatus required for repair.

Cross section of vertical mill Vertical perspective view of vertical mill The figure which shows the motor installation situation to a roller The figure which shows the motor installation situation to a roller The figure which shows the motor installation situation to a roller The figure which shows the contact condition of the motor main body displacement control member fixed to the motor, and the structure in a vertical mill (the 1) The figure which shows the contact condition of the motor main body displacement control member fixed to the motor, and the structure in a vertical mill (the 2) The figure which shows the aspect of the motor and related member which were installed in the roller

(Vertical mill)
In the present invention, a vertical mill in which a roller to be repaired is housed and functions as a mill has a structure shown in FIGS. 1 and 2, for example, and has one or more rollers 5. And the rotating shaft 7 is equipped with the structure extended and supported by the outer surface side of the vertical mill.
The vertical mill has a grinding chamber 1 in it. The crushing chamber 1 is provided with a table liner 2 that forms the lower surface of the crushing chamber 1 and is provided with a crushing surface C on the upper surface. The table liner 2 can be rotated by a motor 3 by a vertical shaft 4 during a crushing operation. . The crushing surface C of the table liner 2 has a shape that can be in close contact with the surface of the roller 5.
During normal operation, the surface of the roller 5 is brought into contact with the crushing surface C provided on the upper surface of the table liner 2, and the material to be crushed is dropped and supplied into the gap from the central inlet 6 above the table liner. To do. During operation, the object to be crushed enters between the roller 5 and the table liner 2 so that the object to be crushed is pulverized. At the same time, the rotational force of the table liner 2 is transmitted to the roller 5 through the object to be crushed, and the roller 5 is rotated by the rotating shaft 7.

(roller)
The roller 5 may be installed such that the rotating shaft 7 is horizontal, or may be provided so that the rotating shaft 7 is inclined as shown in FIG. A roller surface is usually covered with a wheel 8 or the like on the side where the rotation shaft of the roller 5 is not provided, that is, on the inner side of the crushing chamber 1. For this reason, it is difficult to visually confirm the rotation center of the roller 5.
The roller 5 is supported so as to be separated from the table liner 2 for repair and inspection.

<Motor mounting to roller>
As shown in FIG. 3, in order to rotate the roller 5 at the time of repair, it is necessary to attach the rotating shaft R of the motor M to the wheel 8 side of the roller 5.
The attachment by attaching the rotating shaft R of the motor M to the roller 5 can employ attachment means that is scheduled to be removed after the repair is completed. Specifically, means such as welding, bolting, and magnets can be employed.
The rotation axis R of the motor M may be attached directly to the roller 5, and one or more gear boxes (not shown) are attached to the rotation axis for the purpose of adjusting the torque. The shaft on the output side of the gear box may be attached to the roller 5.
Since the motor M or the motor M and the gear box are mounted on the roller 5, a minimum installation space is required.

The gear box is equipped with a spiral bevel gear, hypoid gear, etc., and by reducing gear backlash, the rotation output from the gear box can be made smooth, and the output is transmitted directly to the roller 5. It can be installed regardless of the installation angle of the rotating shaft that rotates the roller 5 during operation.
In the present invention, it is possible to rotate the roller 5 by changing the rotational torque transmission method of the roller 5 from the rotating shaft R of the motor M (direct driving by a gear motor) and reducing the size and weight of the driving device. Show. That is, it is possible to adopt a system in which the rotating shaft of the motor M is connected to the rotating shaft of the roller 5 through the gear box.
At that time, a hypoid gear, a bevel gear, or the like is adopted to increase the reduction ratio, and the backlash of the gear is reduced, so that stable driving is possible. Further, since it is direct drive, the torque transmission mechanism can be eliminated and a simple structure can be achieved. As described above, in order to drive the rotation shaft 7 of the roller 5 directly from the rotation shaft R of the motor M, the gear box is also mounted on the roller.

At this time, the motor M only needs to have an output capable of rotating the roller 5 at a low speed (peripheral speed is 300 to 1500 mm / min). If an attempt is made to attach a motor M having an output greater than necessary, the crushing chamber 1 space for the motor M to be enlarged and attached may be insufficient.
As described above, since the motor M has an output capable of rotating the roller 5 at a low speed, the roller 5 is obviously heavier than the motor M. As a result, at the start of rotation of the rotating shaft of the motor M, the rotating motion hardly contributes directly to the rotating motion of the rotating shaft of the roller 5, and the roller does not rotate due to the reaction force, and the motor rotating shaft is centered. In some cases, the motor M main body may rotate.
In particular, the larger the roller 5 is, the more likely the hunting phenomenon occurs. Therefore, in order to prevent the rotation from becoming unstable, a weight can be attached to the roller (not shown).

(Motor body displacement regulating member)
After FIG. 3, one end of the motor main body displacement regulating member 9 is fixed to the main body of the motor M, and the other end of the motor main body displacement regulating member 9 is inserted into, for example, the lower chute portion in the central insertion port 6. Indicates the state. At this time, the other end is only inserted, and is not fixed at the central insertion port 6, and if the motor M rotates, the position of the other end can be moved.
In this way, the other end of the motor body displacement restricting member 9 may be inserted into the central insertion port 6 and in contact with the wall surface. A receiving member capable of setting a range in which the other end of the member 9 can move, for example, an annular member or a U-shaped member is provided, and the other end of the motor main body displacement regulating member 9 is inserted or received in the annular portion or the U-shaped portion. You can also. Further, the other end of the motor body displacement regulating member 9 can be brought into contact with the surface of the table liner 2.
Furthermore, the aspect at the time of attaching the rotating shaft R of the motor M to the roller 5 as mentioned above is also shown. When mounting, the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or the gear box may or may not match.
The coincidence of the rotation axes indicates a state in which the extension line of the rotation axis 7 of the roller 5 and the rotation axis R of the motor M or the rotation axis on the output side of the gear box are completely aligned. FIG. 3 is a diagram in which the motor M is directly connected to the wheel 8 of the roller 5 without using a gear box. The rotating shaft R of the motor M is not directly connected to the rotating shaft 7 of the roller 5 but directly connected to the wheel 8.

<When the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or gear box coincide with each other>
FIG. 3 shows a mode in which the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M and the gear box coincide with each other.
At this time, when the rotation axis R of the motor M is rotated to rotate the roller 5, the motor M may rotate without the roller 5 rotating due to the reaction force. At that time, the position of the other end of the motor main body displacement regulating member 9 moves, that is, moves in a circular arc around the rotation axis R of the motor M. When the movement of drawing an arc is made, the other end contacts any part in the central insertion slot 6 and the position does not move any further. Therefore, since the displacement of the other end is restricted, the rotation of the main body of the motor M is stopped. After the stop, the rotation force of the rotation shaft R of the motor M is not used as a reaction force but is used to rotate the roller 5, so that the roller 5 can be rotated.
At this time, even if the other end of the motor main body displacement regulating member 9 is fixed to the center insertion slot 6 or another member, the position of the motor M does not move and the roller 5 can be rotated.

<When the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or gear box do not coincide with each other>
The rotation axes do not coincide with each other means that the rotation shaft 7 of the roller 5 and the rotation shaft of the motor M or the rotation shaft on the output side of the gear box are not in a straight line.
As one of such states, the rotation axis R of the motor M is displaced in the direction perpendicular to the rotation axis 7 of the roller 5, and the rotation axis 7 of the roller 5 and the rotation axis on the output side of the motor M or the gear box are Are spaced so that they are positioned in parallel. At this time, the rotary shaft 7 and the rotary shaft R are positioned in parallel.
This case is shown in FIG. FIG. 4 shows a case where the rotation axis R of the motor M is parallel to the rotation axis 7 of the roller 5 but the rotation axis R of the motor M is not on the extension line of the rotation shaft 7 of the roller 5. In FIG. 4, the position of the rotation axis R of the motor M is greatly shifted for the sake of explanation. In the actual process, of course, although the rotation axis R of the motor M is intended to coincide with the rotation axis 7 of the roller 5, the inside of the grinding chamber is narrow and it is difficult to grasp the position of the rotation axis 7 on the wheel 8. Therefore, it may not be possible to match.
Immediately after the start of rotation of the rotation shaft R of the motor M, the rotational motion does not become the rotational motion of the roller 5, and the main body of the motor M may rotate due to the reaction force. At this time, the other end of the motor main body displacement regulating member 9 fixed to the motor M main body moves in a circular arc around the rotation axis of the motor M as in the case of FIG.

However, as in the case shown in FIG. 3, after the other end comes into contact with any part in the central insertion port 6 and does not move any further, the rotation axis R of the motor M is reached. Is used to rotate the roller 5, the entire body of the motor M is rotated by the rotating shaft 7. At this time, no force is applied to the other end of the motor body displacement restricting member 9 so as to draw a circular arc around the rotation axis R of the motor M. In this case and in the case shown in FIG. 5 below, the rotational axis R of the motor M may be slightly deviated unless the rotational axis R of the motor M is clearly deviated from the rotational axis 7 of the roller 5. The output is consumed for the rotation of the rotating shaft 7 of the roller 5.
Instead, when the main body of the motor M is rotated by the rotation shaft 7, the movement caused by the rotation shaft R of the motor M being displaced from the rotation shaft 7 and being fixed to the roller 5 is changed to that of the motor main body displacement regulating member 9. Try to end. Unlike the case of FIG. 3, this movement is not a movement that draws an arc, and a movement in which the other end of the motor main body displacement regulating member 9 performs a circular motion is also combined.
Therefore, in such a case, the other end of the motor main body displacement restricting member 9 is not fixed and needs to be positioned in a space that can handle more complicated movements.
If the other end of the motor main body displacement regulating member 9 is fixed to the center insertion slot 6 or another member, the main body of the motor M is also fixed to members other than the roller 5. The position of the motor M is moved by the rotation of the roller 5. As a result, the fixing points of the motor M itself and the motor main body displacement regulating member 9 are damaged.

<When the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or gear box do not coincide with each other>
As an aspect in which the other rotating shafts do not coincide with each other, as shown in FIG. 5, there is a state in which the rotating shaft R on the output side of the motor M or the gear box extends obliquely with respect to the rotating shaft 7 of the roller 5. At this time, the case where the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or the gear box cross each other is included.
Originally, it is desirable to fix the rotation axis R of the motor M or the gear box to the roller 5 so as to completely coincide with the rotation axis 7 of the roller 5. However, in practice, on the surface of the wheel 5 on the side where the motor M is mounted in the roller 5, the rotating shaft 7 of the roller 5 is not exposed, and the mark indicating the position of the rotating shaft of the roller 5 is not provided. There are many. In addition, such a surface is not a flat surface but may be a hemisphere or the like. In such a case, the motor M may be fixed to the roller 5 particularly in the state shown in FIG.
In this case, immediately after the rotation axis R of the motor M starts to rotate, the rotation of the rotation axis R of the motor M receives a reaction force from the roller 5, and the main body of the motor M rotates about the rotation axis R of the motor M. To do. As a result, the other end of the motor body displacement restricting member 9 moves so as to draw an arc centered on the rotation axis R of the motor M. However, the circular arc draws a trajectory inclined with respect to the rotating shaft 7 of the roller 5.

Thereafter, the other end of the motor main body displacement restricting member 9 hits a member, for example, in the central insertion slot 6 or the like, and no further movement is possible. At that time, the rotational force of the rotating shaft R of the motor M is spent on the rotation of the roller 5. As a result, the main body of the motor M is rotated by the rotary shaft 7 and the motor M is tilted and fixed with respect to the rotary shaft 7, so that the motor M main body rotates in a tilted state.
Then, a force for further three-dimensional and complicated movement is applied to the other end of the motor main body displacement regulating member 9. If the other end of the motor main body displacement restricting member 9 is fixed, in other words, if the main body of the motor M is also fixed to a member other than the roller 5, the motor M itself, the motor main body, as in the case shown in FIG. The fixed part of the displacement regulating member 9 will be damaged.

As described above, there are cases where the rotating shaft 7 of the roller 5 and the rotating shaft R on the output side of the motor M or the gear box match or do not match. However, in practice, the case of coincidence and the case of non-coincidence are not found until the rotation shaft R of the motor M is rotated.
Therefore, even if the rotation shaft 7 of the roller 5 coincides with the rotation shaft R on the output side of the motor M or the gear box as a result, the attachment of the motor M to the roller 5 and one end of the motor body displacement regulating member 9 are achieved. It is necessary to fix only to the motor M.

<Relationship between motor M, motor main body displacement regulating member 9 fixed to motor M, and structure in vertical mill>
As described above, according to the present invention, one end of the motor main body displacement regulating member 9 is fixed to the main body of the motor M, and the other end 10 is not fixed to another member or structure.
However, the other end is not completely free to move. As an example, the case where the other end 10 is inserted into the lower end of the central inlet 6 in the vertical mill will be described with reference to the side, front and top views of FIG.
Immediately after the rotation shaft of the motor M starts to rotate, the motor M main body normally rotates around the rotation shaft of the motor M, so that the other end of the motor main body displacement regulating member 9 on the side not fixed to the motor M. 10 also moves. However, since the other end 10 is inserted into the central slot 6, the movable range is restricted to the lower end of the center slot 6. Therefore, when the other end 10 moves and contacts the wall surface at the lower end in the central insertion port 6, it cannot move any further.
As a result, the rotation of the motor M main body is stopped, the rotation of the rotation shaft of the motor M is transmitted to the rotation of the roller 5, and the roller 5 starts to rotate.

  Further, in FIG. 7, when the motor M main body rotates, the other end 10 of the motor main body displacement regulating member 9 comes into contact with the vertical mill wall surface, or a hole or depression provided in the vertical mill wall surface. The other end 10 is restricted so that it cannot move. As a result, as in the case of FIG. 6, the rotation of the motor M main body stops, the rotation of the rotation shaft R of the motor M is transmitted to the rotation of the roller 5, and the roller 5 starts to rotate.

<Overlay welding>
The crushing surfaces of the surfaces of the roller 5 and the table liner 2 are worn by the operation of the vertical mill. For this reason, build-up welding is performed to recover the worn crushing surface, and a new build-up surface is formed. In the overlay welding, welding is performed by bringing a welding jig such as a welding wire close to the surface of the roller 5 or the table liner 2. As a welding jig used for such overlay welding, a known jig can be employed.
In order to perform overlay welding on the surface of the roller 5, the required overlay welding equipment is a known overlay welding equipment. A pipe for supplying the welding wire to be built up is installed from the outside to the inside of the vertical mill, and further, the inner end of the vertical mill inside the pipe is installed near the welding torch. The welding torch is installed as close to the roller surface as can be welded to the roller surface. A well-known welding torch can be used, and a welding wire used for conventional overlay welding can also be used.
In this state, the roller 5 is separated from the grinding surface C of the table liner 2 as necessary, and overlay welding is performed while the roller 5 is rotated by the above means. When the build-up welding jig is moved in the direction of the rotation axis of the roller by an approximate width of the build-up welding every rotation of the roller 5, the weld beads of the build-up welding can be adjacent to each other. As a result, every time the rotation of the roller proceeds, it is built up on the roller surface.
It is preferable that the rotation speed of the roller is 300 to 1500 mm / min. If it is less than 300 mm / min, the efficiency of overlay welding deteriorates, and if it exceeds 1500 mm / min, the welding speed is exceeded, so that sufficient repair becomes difficult.

Although not shown in the figure, the contact thickness of the part in contact with the object to be crushed on the member in the welding jig or vertical mill is non-contact so that it can be measured before, during and after overlay welding, A device for measuring the surface shape by a laser or the like may be provided.
When repairing the roller surface by overlay welding, the surface shape can be changed to an arbitrary shape. The roller surface may have an uneven shape extending in the approximate circumferential direction, and then the surface may be ground to obtain a smoother surface.
Also, in overlay welding, when the welding jig is moved in the axial direction of the roller by the width of the overlay for each rotation of the roller as described above, overlay welding is performed along the roller surface as if it were a single stroke. can do. Further, by reciprocating the welding jig to an arbitrary width in the axial direction of the roller, a wavy pattern such as a so-called chevron pattern is formed on the roller surface, and the object to be crushed between the table liner 2 and the roller 5 It can be made to bite more reliably.

As a driving device including a motor for rotating a roller of about 4 tons (roller diameter: about 1,500 mm) at a speed of about 1,000 mm / min as a peripheral speed for performing good overlay welding, for example, The one of specification is mentioned. This driving device is formed by integrating only the following motor or a gear box.
When the gearbox was used, the gear ratio was as follows, and the torque was increased by lowering the rotational speed. A rotary earth was also used.
Motor: 3 phase x 200V x 50w x 4 pole motor (gear motor)
Gear ratio: 1 / 1,800
Maximum rotation speed at the drive shaft end: 1 rpm (60 Hz), 0.83 rpm (50 Hz)
Maximum torque at the drive shaft end: 32 kg-m (60 Hz), 38 kg-m (50 Hz)
Rotary earth capacity: 1,000 Amp
An example of the mounting state when no gear is used as this driving device (including rotary earth) is as shown in FIG. A specific example of the drive device main body is shown in FIG.
FIG. 8a shows the case where the output side drive shaft (drive side shaft end) and the roller main shaft (rotary shaft) of the gear motor are integrated. In this case, the weight of the driving device is as extremely light as about 12 kg, the mounting is simple, the required space is small, and stable driving is possible. FIG. 8b shows an example in which a pair of gears are used between the gear motor and the roller, and FIG. 8c shows an example in which the torque of the gear motor is transmitted to the roller rotation shaft by a chain (or belt). By using gears, belt chains, etc. for torque transmission, the reduction ratio can be further increased.
This method facilitates roller overlay welding in the mill of a large vertical mill, which has been a difficult task in the past, and roller overlay welding in a mill of a small mill, which has been impossible in the past. Enables simultaneous overlay welding of liner and roller.

DESCRIPTION OF SYMBOLS 1 ... Grinding chamber 2 ... Table liner 3 ... Motor 4 ... Vertical shaft 5 ... Roller 6 ... Center inlet 7 ... Rotating shaft 8 ... Wheel 9 ... Motor body displacement regulating member 10 .. other end 11 .. saddle mill wall 12 .. gear 13 .. chain C... Grinding surface M .. motor R.

Claims (1)

Supplied with a table liner that rotates by a vertical shaft, and a roller that is rotatable by contact with the table liner and transmitting the rotational force of the table liner, and having a rotating shaft connected on one side A roller repair method for a vertical mill in which an object to be crushed is pulverized by entering between the table liner and the roller,
Connect the rotating shaft of the motor to the surface of the roller where the rotating shaft is not provided,
Without fixing the motor body to a member other than the roller, the motor body displacement regulating member is fixed to the motor body,
A method of repairing the roller surface by rotating the rotating shaft of the motor and performing overlay welding with a metal on the surface of the roller facing the table liner surface.