CN109396192B - Centering machine - Google Patents

Abstract

The application provides a centering machine, which comprises: a plurality of press rolls, which are arranged around a rolling center line; the driven gears are arranged on the outer sides of the pressing rollers in a surrounding mode; the driven gears correspond to the press rollers, and each driven gear is connected with the corresponding press roller; each of the driven gears has a first rotation axis; a drive gear; the driving gear is arranged on one side of the rolling center line; each driven gear is meshed with the driving gear, and the driving gear is used for driving each driven gear to rotate around the first rotation axis so that a plurality of compression rollers can be opened and closed; the driving mechanism is connected with the driving gear and is used for driving the driving gear to rotate. The embodiment of the application provides a centering machine capable of ensuring accurate synchronization of the opening degree of each compression roller.

Description

Centering machine

technical field

The invention relates to the technical field of steel pipe rolling and piercing, in particular to a centering machine.

Background technique

The centering machine is used to stabilize the ejector rod to ensure the smooth progress of the piercing.

Both Figure 1 and Figure 2 show a centering machine in the prior art. The existing centering machine mainly includes a frame 50 and a link mechanism arranged on the frame 50 . This link mechanism comprises crank 52, pressure roller 54, upper swing arm 56, side swing arm 58, lower swing arm 60, side tie rod 62, lower pull rod 64, upper pull rod 66 (or opening and closing hydraulic cylinder), adjustment hydraulic cylinder 68. The pressure roller 54 is installed on the swing arm; the crank 52 swings around the crank hinge point H1; the upper swing arm 56 and the side swing arm 58 swing around the upper hinge point H2; the lower swing arm 60 swings around the lower hinge point H3 swings. The adjusting hydraulic cylinder 68 is used to synchronously drive the upper swing arm 56 , the side swing arm 58 , and the lower swing arm 60 , so as to adjust the opening degree of the pressure roller 54 .

Since crank 52, upper swing arm 56, side swing arm 58 and lower swing arm 60 can not be a fixed value under the drive of adjusting hydraulic cylinder 68, the speed and displacement that swing around the hinge point, so crank 52, upper swing arm 56, The speed and displacement of the side swing arm 58 and the bottom swing arm 60 vary unevenly, thus causing the speed of each pressing roller 54 to be different during the opening process, that is, the opening degrees of each pressing roller 54 are different. Fig. 1 shows the assembly drawing of the centering machine with the smallest opening of the pressure rollers in the prior art, wherein the angular distances between the pressure rollers 54 are 122.45°, 117.53° and 120.018° respectively. Fig. 2 shows the assembly diagram of the maximum opening of the pressure rollers of the centering machine in the prior art, wherein the angular distances between the pressure rollers 54 are respectively 117.9°, 122.08° and 120.021°, it can be seen that there are two pressure rollers Roller 54 has obvious increase and decrease change. In this way, the centers of the pressing rollers 54 are not on the circumference centered on the rolling centerline, that is, when the openings of the pressing rollers 54 are different, the positions of the center of the formed circles are also different. However, the center line of rolling, that is, the center line of perforation remains unchanged, so the circles where each pressure roller 54 is positioned are eccentric to the circle of the outer diameter section of the steel pipe 14 . This eccentricity will increase the radial force of the steel pipe 14, causing the steel pipe 14 to become arc-shaped. And the steel pipe 14 constantly collides with the pressing roller 54 in the process of spiral advancement, which causes a lot of noise on site and affects the service life of the centering machine.

Contents of the invention

In view of this, the embodiments of the present application provide a centering machine that can ensure precise synchronization of the opening degrees of each pressure roller.

The above object of the present invention can be achieved by the following technical solutions: a centering machine, comprising: a plurality of pressing rollers arranged around the rolling center line; a plurality of driven gears, a plurality of said driven rollers The driven gears are arranged outside the plurality of pressure rollers; and the plurality of driven gears correspond to the plurality of pressure rollers, and each driven gear is connected to the corresponding pressure rollers; each Each of the driven gears has a first rotation axis; a driving gear; the driving gear is arranged on one side of the rolling center line; each of the driven gears is meshed with the driving gear, and the driving gear It is used to drive each driven gear to rotate around the first axis of rotation, so that a plurality of the pressure rollers can be opened and engaged; a driving mechanism, the driving mechanism is connected with the driving gear, the The driving mechanism is used to drive the driving gear to rotate.

As a preferred implementation manner, the extension direction of the first rotation axis of each driven gear is parallel to the extension direction of the rolling centerline.

As a preferred embodiment, the pressure rollers include a first pressure roller, a second pressure roller and a third pressure roller uniformly arranged along the rolling centerline, and the first pressure roller is connected with the driving gear Facing each other, the second pressure roller and the third pressure roller are located on the side of the first pressure roller facing away from the driving gear, and the second pressure roller is located above the first pressure roller, The third pressing roller is located below the first pressing roller.

As a preferred embodiment, the driven gear includes a first driven gear connected to the first pressure roller, a second driven gear connected to the second pressure roller, and a second driven gear connected to the first pressure roller. The third driven gear connected with the three pressure rollers; the first driven gear and the second driven gear are both meshed with the upper teeth of the driving gear, and the third driven gear is engaged with the upper teeth of the driving gear. The lower teeth of the driving gear are meshed, and the first driven gear is opposite to the second driven gear.

As a preferred embodiment, an intermediate wheel is arranged between the second driven gear and the driving gear, and the teeth on both sides of the intermediate wheel are respectively connected to the driving gear and the second driven gear. The gears mesh.

As a preferred embodiment, each of the driven gears is provided with a through hole, and each of the through holes is pierced with a first rotating shaft, and the extension direction of each of the first rotating shafts is the same as that of the corresponding The extension direction of the first rotation axis of the driven gear is consistent; each of the first rotation shafts is provided with a connecting rod, and each of the pressure rollers is connected with the connecting rod.

As a preferred implementation manner, each of the first rotating shafts is fixedly connected to the corresponding driven gear through a key.

As a preferred embodiment, it includes: a frame; the frame includes a vertically arranged first side plate and a second side plate, the first side plate is provided with a first opening, and the first side plate A second opening is arranged on the two side plates, the first opening is opposite to the second opening, one end of the first rotating shaft is passed through the first opening, and the first rotating shaft The other end is passed through the second opening.

As a preferred embodiment, one end of each connecting rod is connected to the first rotating shaft, the other end of each connecting rod is connected to the pressure roller, and each connecting rod same length.

As a preferred embodiment, the pitch circle diameter and modulus of each driven gear are the same.

As a preferred embodiment, the radius of the pitch circle of each driven gear is 275 mm, the pitch circle diameter of the intermediate wheel is 150 mm, and the first rotation axis of each driven gear is Located on a circle with a diameter of 580 mm.

As a preferred implementation manner, the driven gear is a sector gear, and the driving gear is a sector gear.

As a preferred embodiment, the driving mechanism includes a hydraulic cylinder and a plunger pierced in the hydraulic cylinder, the plunger is connected with the driving gear, and the plunger can Under the pressure of the fluid inside, it reciprocates along the direction perpendicular to the rolling centerline.

As a preferred implementation manner, the driving gear has a second rotation axis, and the extension direction of the second rotation axis is parallel to the extension direction of the rolling centerline.

As a preferred implementation manner, the tooth width of the driving gear is greater than the tooth width of the first driven gear; and the tooth width of the driving gear is greater than the tooth width of the intermediate gear.

The beneficial effects of the centering machine provided by the present application are: the centering machine according to the embodiment of the present application sets the driving gear, the driven gear, and the driving mechanism so that the opening of the pressure roller is realized by the rotation of the driving gear and the driven gear. Since the angular velocity of the driving gear and the driven gear can be kept constant during the rotation process, it can ensure that the speed of each pressure roller is the same during the opening process, thereby ensuring the precise synchronization of the opening degrees of each pressure roller. Therefore, the embodiment of the present application provides a centering machine capable of ensuring accurate synchronization of the opening degrees of each pressure roller.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

Fig. 1 is the minimum mechanical assembly diagram of the opening of the centering machine in the prior art;

Fig. 2 is the mechanical assembly diagram of the maximum opening of the centering machine in the prior art;

Fig. 3 is the schematic diagram of the mechanism of centering machine in the prior art;

Fig. 4 is the schematic diagram of the centering machine provided by one embodiment of the present application;

Fig. 5 is a simplified diagram of a centering machine provided by an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Please refer to Figure 4 and Figure 5. The centering machine provided in one embodiment of the present application may include: a plurality of pressing rollers 23 arranged around the rolling center line; a plurality of driven gears 25, a plurality of said driven gears 25 surrounds the outside of a plurality of said pressure rollers 23; Connected; each said driven gear 25 has a first rotation axis 31; driving gear 29; said driving gear 29 is arranged on one side of said rolling center line; each said driven gear 25 and said The driving gear 29 is meshed, and the driving gear 29 is used to drive each of the driven gears 25 to rotate around the first rotation axis, so that a plurality of the pressing rollers 23 can be opened and engaged; the driving mechanism 53, The driving mechanism 53 is connected with the driving gear 29 , and the driving mechanism 53 is used to drive the driving gear 29 to rotate.

During use, the driving gear 29 is driven to rotate by the driving mechanism 53 . In this way, the driving gear 29 can drive each driven gear 25 to rotate around its respective first axis of rotation. Further, each pressure roller 23 is driven to rotate around the first rotation axis of the corresponding driven gear 25 , so that the multiple pressure rollers 23 are opened and engaged.

It can be seen from the above technical solutions that the centering machine according to the embodiment of the present application sets the driving gear 29, the driven gear 25, and the driving mechanism 53 so that the opening of the pressure roller 23 is realized by the rotation of the driving gear 29 and the driven gear 25. . Since the angular velocity of the driving gear 29 and the driven gear 25 can remain constant during rotation, it can be ensured that the speeds of each pressure roller 23 are the same during the opening process, thereby ensuring that the opening degrees of each pressure roller 23 are precisely synchronized. Further, as shown in Figure 3, the crank, pressure roller 23, upper swing arm, side swing arm, lower swing arm, side pull rod, lower pull rod, and upper pull rod on the centering machine in the prior art intersect with each other. The centering machine in the prior art has to be designed as a double-layer structure in the frame 47, so that the minimum design width of the centering machine in the prior art is limited. However, in this embodiment, through the gear transmission of the driving gear 29 and the driven gear 25, the width of the centering machine described in this embodiment can be reduced.

As shown in FIG. 4 , in this embodiment, a plurality of pressing rollers 23 are arranged around the center line of rolling. Specifically, the pressing roll 23 includes the first pressing roll 11, the second pressing roll 13 and the third pressing roll 15 arranged uniformly along the rolling center line, the first pressing roll 11 faces the driving gear 29, and the second pressing roll 11 faces the driving gear 29. The roller 13 and the third pressing roller 15 are located on the side of the first pressing roller 11 facing away from the driving gear 29, and the second pressing roller 13 is located above the first pressing roller 11, and the third pressing roller 15 is located below the first pressing roller 11 . That is, there are three pressing rollers 23, and the three pressing rollers 23 are evenly arranged around the rolling centerline. And the central angle corresponding to two adjacent pressure rollers 23 is 120 degrees. Since the centerline of the steel pipe 12 is located on the rolling centerline, the three pressure rollers 23 can be evenly arranged around the steel pipe 12 , and the three pressure rollers 23 can exert a uniform force on the steel pipe 12 . Further, each pressing roller 23 presses against the periphery of the mandrel before piercing, that is, the plurality of pressing rollers 23 are in an entwined state. When piercing, the ejector pin is fixed. The steel billet moves toward the push rod, and the plug at the front end of the push rod penetrates into the center of the steel billet to form a steel pipe 12 . Since the ejector rod is relatively thin, the outer diameter becomes thicker after the steel pipe 12 is put on, so in the process of piercing, each pressure roller 23 will move in a direction away from the steel pipe 12, that is, each pressure roller 23 changes from the engaged state to Open state. Of course, the number of the pressing rollers 23 is not limited thereto, and may be other numbers, such as 4, which is not specified in this application.

As shown in FIG. 4 , in this embodiment, a plurality of driven gears 25 are arranged around the outer sides of a plurality of pressure rollers 23 . That is, a plurality of driven gears 25 are arranged around the rolling center line, and the plurality of driven gears 25 are located outside the plurality of pressure rollers 23 . Further, the driven gear 25 corresponds to a plurality of pressure rollers 23 , each driven gear 25 is connected to the corresponding pressure roller 23 , and each driven gear 25 has a first rotation axis 31 . Further, the extension direction of the first rotation axis of each driven gear 25 is parallel to the extension direction of the rolling center line. Specifically, the number of driven gears 25 is equal to the number of pressure rollers 23 . For example, the number of pressing rollers 23 is three, and the number of driven gears 25 is three. Each driven gear 25 is connected to the corresponding pressure roller 23, and the connection method may be welding, integral molding, etc., which is not specified in this application. Thereby each pressure roller 23 can be driven by the corresponding driven gear 25 to rotate around the first rotation axis 31 of the corresponding driven gear 25, so as to realize the movement of the pressure roller 23 away from the direction of the steel pipe 12 and towards the direction of the steel pipe 12, and also That is, each pressing roller 23 can be changed between an engaged state and an open state. In order to ensure that each driven gear 25 has the same speed and angular displacement driven by the driving gear 29 , the pitch circle diameter and module of each driven gear 25 are the same.

As shown in Figure 4, in one embodiment, the driven gear 25 includes a first driven gear 17 connected to the first pressure roller 11, a second driven gear 19 connected to the second pressure roller 13, and a The third driven gear 21 that the 3rd pressure roller 15 is connected; The first driven gear 17 and the second driven gear 19 are all meshed with the upper gear teeth of the driving gear 29, and the third driven gear 21 and the driving gear 29 The lower gear teeth are engaged, and the first driven gear 17 is opposite to the second driven gear 19 .

As shown in FIG. 4 , in one embodiment, each driven gear 25 is provided with a through hole, and a first rotating shaft 35 is pierced in each through hole, and the extension direction of each first rotating shaft 35 is consistent with the corresponding The extension directions of the first rotation axes 31 of the driven gears 25 are consistent; each first rotating shaft 35 is provided with a connecting rod 39 , and each pressing roller 23 is connected with the connecting rod 39 . Specifically, one end of each connecting rod 39 is connected to the first rotating shaft 35 , and the other end of each connecting rod 39 is connected to the pressure roller 23 . The connection method may be welding, integral molding, etc., which is not specified in this application. In order to ensure that each pressure roller 23 has the same speed and angular displacement driven by the corresponding driven gear 25, each connecting rod 39 has the same length. Further, each first rotating shaft 35 is fixedly connected with the corresponding driven gear 25 through a key. Therefore, when the driven gear 25 rotates, it can drive the first rotating shaft 35 to rotate, and then the first rotating shaft 35 can drive the connecting rod 39 to rotate.

As shown in FIG. 4 , in one embodiment, the frame 47 includes vertically arranged first side panels 41 and second side panels 43 and a horizontally arranged bottom panel 45 . The bottom plate 45 is located between the first side plate 41 and the second side plate 43 and connected with the first side plate 41 and the second side plate 43 . The frame 47 is a cuboid structure as a whole. Of course, the shape of the frame 47 is not limited thereto, and may be other shapes, which are not specified in this application. Further, a first opening is provided on the first side plate 41 of the frame 47 , a second opening is provided on the second side plate 43 of the frame 47 , and the first opening and the second opening are oppositely disposed. One end of the first rotating shaft 35 passes through the first opening, and the other end of the first rotating shaft 35 passes through the second opening. Therefore, when the driven gear 25 rotates, it can drive the first rotating shaft 35 to rotate relative to the frame 47 .

As shown in Figure 5, in order to ensure that the center of the circle enclosed by each pressure roller 23 is at the same position at any opening degree, the radius of the pitch circle of each driven gear 25 is 275 mm, and the center of the circle of the intermediate wheel 27 The diameter of the pitch circle is 150 mm, the first rotation axis 31 of each driven gear 25 is located on a circle with a diameter of 580 mm, and the length of each connecting rod 39 is 255 mm.

As shown in FIG. 4 , in this embodiment, the driving gear 29 is provided on one side of the rolling center line. The driving gear 29 has a second rotation axis 33 so that the driving gear 29 can rotate around the second rotation axis 33 . Further, the driving gear 29 is provided with a through hole, and the second shaft 37 is pierced in the through hole. The extension direction of the second rotating shaft 37 is consistent with the extension direction of the second rotation axis 33 . Further, the extension direction of the second rotation axis is parallel to the extension direction of the rolling centerline. Further, the first side plate 41 of the frame 47 is provided with a third opening, and the second side plate 43 of the frame 47 is provided with a fourth opening, and the third opening is opposite to the fourth opening. One end of the second rotating shaft 37 passes through the third opening, and the other end of the second rotating shaft 37 passes through the fourth opening. Each driven gear 25 meshes with a driving gear 29, and the driving gear 29 is used to drive each driven gear 25 to rotate around the first axis of rotation, so that the plurality of pressing rollers 23 can be opened and engaged. Specifically, the first axis of rotation of the first driven gear 17 and the first axis of rotation of the second driven gear 19 are located above the rolling center line, and the first axis of rotation 31 of the third driven gear 21 is located above the rolling centerline. below the centerline. That is, both the first rotating shaft 35 of the first driven gear 17 and the first rotating shaft 35 of the second driven gear 19 are located above the center line of rolling. And the first driven gear 17 is opposite to the second driven gear 19 . Further, both the first driven gear 17 and the second driven gear 19 mesh with the upper teeth of the driving gear 29 , and the third driven gear 21 meshes with the lower teeth of the driving gear 29 . Therefore, when the driving gear 29 rotates clockwise, the driving gear 29 can drive the first driven gear 17 and the third driven gear 21 to rotate clockwise. In order to make the rotation direction of the second driven gear 19 opposite to the rotation direction of the first driven gear 17, that is, to make the rotation direction of the first pressure roller 11 and the second pressure roller 13 opposite, thereby realizing the first pressure roller 11 and the second pressure roller 13. The second pressure roller 13 rotates away from the rolling center line or rotates towards the rolling center line at the same time. An intermediate wheel 27 is arranged between the second driven gear 19 and the driving gear 29, and the teeth on both sides of the intermediate wheel 27 are respectively connected to the driving wheel. The gear 29 meshes with the second driven gear 19 . Thus when the driving gear 29 rotates in the clockwise direction, the first pressure roller 11 rotates in the clockwise direction around the first rotation axis of the first driven gear 17, and the third pressure roller 15 rotates around the first rotation axis of the third driven gear 21. The rotation axis rotates in the clockwise direction, and the second pressure roller 13 rotates in the counterclockwise direction around the first rotation axis of the second driven gear 19, so that the first pressure roller 11, the second pressure roller 13 and the third pressure roller 15 all Rotating away from the rolling center, that is, the first pressing roller 11 , the second pressing roller 13 and the third pressing roller 15 are in an open state. When the driving gear 29 rotates counterclockwise, the first pressure roller 11 rotates counterclockwise around the first rotation axis of the first driven gear 17, and the third pressure roller 15 rotates around the first rotation axis of the third driven gear 21. The axis rotates in the counterclockwise direction, and the second pressure roller 13 rotates in the clockwise direction around the first rotation axis of the second driven gear 19, so that the first pressure roller 11, the second pressure roller 13 and the third pressure roller 15 all face The rolling center rotates, that is, the first pressing roller 11 , the second pressing roller 13 and the third pressing roller 15 are in an engaged state. Thereby, a plurality of pressure rollers 23 can be opened and entwined. Further, in order not to interfere between the first driven gear 17 and the intermediate wheel 27 and the second driven gear 19, the tooth width of the driving gear 29 is greater than the tooth width of the first driven gear 17; The tooth width is greater than that of the intermediate wheel 27 .

As shown in FIG. 4 , further, the driven gear 25 is a sector gear, and the driving gear 29 is a sector gear.

As shown in FIG. 4 , in this embodiment, the driving mechanism 53 is used to drive the driving gear 29 to rotate around the second rotation axis 33 . The driving mechanism 53 is connected with the driving gear 29 . Specifically, the driving mechanism 53 includes a hydraulic cylinder 49 and a plunger 51 passing through the hydraulic cylinder 49 , and the plunger 51 is connected with the driving gear 29 . The connection method may be screw connection, bolt connection, integral molding, welding, etc., which is not specified in this application. The plunger 51 can reciprocate under the pressure of the fluid in the hydraulic cylinder 49 in a direction perpendicular to the rolling centerline. When the plunger 51 is extended under the pressure of the fluid, the driving gear 29 can rotate counterclockwise around the second rotation axis 33 . When the plunger 51 is retracted under the pressure of the fluid, the drive gear 29 can rotate clockwise about the second axis of rotation 33 .

The above are only a few embodiments of the present invention, and those skilled in the art can make various changes or modifications to the embodiments of the present invention according to the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims (9)

1. A centering machine, comprising:

a plurality of press rolls, which are arranged around a rolling center line;

the driven gears are arranged on the outer sides of the pressing rollers in a surrounding mode; the driven gears correspond to the press rollers, and each driven gear is connected with the corresponding press roller; each of the driven gears has a first rotation axis;

a drive gear; the driving gear is arranged on one side of the rolling center line; each driven gear is meshed with the driving gear, and the driving gear is used for driving each driven gear to rotate around the first rotation axis so that a plurality of compression rollers can be opened and closed;

the driving mechanism is connected with the driving gear and is used for driving the driving gear to rotate;

the extending direction of the first rotation axis of each driven gear is parallel to the extending direction of the rolling center line;

the pressing rollers comprise a first pressing roller, a second pressing roller and a third pressing roller which are uniformly distributed along the rolling center line, the first pressing roller faces the driving gear, the second pressing roller and the third pressing roller are positioned on one side of the first pressing roller, which is opposite to the driving gear, the second pressing roller is positioned above the first pressing roller, and the third pressing roller is positioned below the first pressing roller;

the driven gear comprises a first driven gear connected with the first press roller, a second driven gear connected with the second press roller and a third driven gear connected with the third press roller; the first driven gear and the second driven gear are meshed with the upper gear teeth of the driving gear, the third driven gear is meshed with the lower gear teeth of the driving gear, and the first driven gear and the second driven gear are oppositely arranged;

a idler wheel is arranged between the second driven gear and the driving gear, and gear teeth on two sides of the idler wheel are respectively meshed with the driving gear and the second driven gear;

each driven gear is provided with a through hole, each through hole is internally provided with a first rotating shaft in a penetrating way, and the extending direction of each first rotating shaft is consistent with the extending direction of the corresponding first rotation axis of the driven gear; a connecting rod is arranged on each first rotating shaft, and each pressing roller is connected with the connecting rod;

the driven gear is a sector gear, and the driving gear is a sector gear.

2. The centering machine of claim 1, wherein: each first rotating shaft is fixedly connected with the corresponding driven gear through a key.

3. The centering machine of claim 1, characterized in that it comprises: a frame; the frame includes the first curb plate and the second curb plate of vertical setting, be provided with first trompil on the first curb plate, be provided with the second trompil on the second curb plate, first trompil with the second trompil is just right mutually, the one end of first pivot wears to locate in the first trompil, the other end of first pivot wears to locate in the second trompil.

4. The centering machine of claim 1, wherein: one end of each connecting rod is connected with the first rotating shaft, the other end of each connecting rod is connected with the compression roller, and the length of each connecting rod is the same.

5. The centering machine of claim 1, wherein: the pitch diameter and the modulus of each driven gear are the same.

6. The centering machine of claim 1, wherein: the pitch circle radius of each driven gear is 275 mm, the pitch circle diameter of the intermediate wheel is 150 mm, and the first rotation axis of each driven gear is located on a circumference with a diameter of 580 mm.

7. The centering machine of claim 1, wherein: the driving mechanism comprises a hydraulic cylinder and a plunger penetrating through the hydraulic cylinder, the plunger is connected with the driving gear, and the plunger can reciprocate along the direction perpendicular to the rolling center line under the pressure of fluid in the hydraulic cylinder.

8. The centering machine of claim 1, wherein: the driving gear is provided with a second rotation axis, and the extending direction of the second rotation axis is parallel to the extending direction of the rolling center line.

9. The centering machine of claim 1, wherein: the tooth width of the driving gear is larger than that of the first driven gear; and the tooth width of the driving gear is larger than that of the intermediate wheel.