CN104384192A - Tube drawing machine and seamless tube rolling method - Google Patents

Abstract

The invention provides a pipe drawing machine and a seamless pipe rolling method, which are used for rolling a capillary pipe into a blank pipe. The pipe drawing machine includes: a bed (5), arranged on a rolling line; a plurality of rollers Dies are arranged side by side in the bed (5); the necking machine (4) is located at the entrance of the bed (5); the material receiving front (3) is located at the upstream of the necking machine (4), and bears the The foreground supporting surface of the capillary; the drawing tube background (6), located at the outlet of the bed, and the drawing tube background (6) supports the mandrel and the capillary; the rack and pinion transmission system (7), located at the drawing tube The downstream of the backstage (6); the mandrel is connected to the rack and pinion drive system (7), and the mandrel can be placed on the receiving front (3), necking machine (4) and bed (5), roller Carry out reciprocating linear movement between mold (30) and drawing tube background (6). The seamless pipe rolling method uses the above-mentioned pipe drawing machine. The bed coefficient of the present invention is smaller and there is no pressure bar stability problem.

Description

Pipe drawing machine and seamless pipe rolling method

technical field

The invention relates to the field of metallurgy, in particular to a three-roll mill for rolling seamless steel pipes, in particular to a pipe drawing machine and a seamless pipe rolling method.

Background technique

At present, seamless steel pipe rolling can be divided into active rolling and passive rolling according to the transmission type. The active rolling unit includes MPM, PQF and other two-roll or three-roll multi-stand continuous longitudinal rolling and ASSEL three-roll single-stand skew rolling. , Accu Roll two-roller single-stand cross-rolling and other units; passive rolling is mainly CPE method (Cross-roll Piercing and Elongating), which is a method of cross-rolling perforated cross-rolled capillary pipes and then jacking them to obtain waste pipes after shrinking. A rolling process method for producing finished steel pipes by tension reduction. The key of this method is the top system, the motor drives the rack through the reducer, drives the push rod to push the mandrel, and tops the barren tube.

One of the main pressure processing and deformation equipment corresponding to the above-mentioned CPE is the pipe jacking machine. Due to the stability of the pressure rod, the mandrel aspect ratio (the ratio of length to diameter) of this model is often limited, and the aspect ratio of the matching push rod It is also limited and affects the bed coefficient to a certain extent.

Due to the limitation of the maximum jacking force, the number of biting racks (roll dies) cannot be too many at the same time, and the rolling roll dies are arranged at a relatively large interval. Considering the stability of the pressure bar, the interval cannot be too large, but the rolling pass ( The total number of online roller molds) must ensure the process requirements, and the bed is often lengthened, resulting in longer mandrels or push rods, and corresponding increases in pipe jacking racks, which makes equipment and tool manufacturing and production of spare parts uneconomical.

To sum up, the following problems exist in the prior art: in the current rolling of seamless steel pipes, there is a problem of poor force stability of mandrel or push rod, which affects the length-to-diameter ratio of the mandrel.

Contents of the invention

The invention provides a pipe drawing machine and a seamless pipe rolling method to solve the problem that the mandrel rod or push rod has poor force stability and affects the mandrel length-to-diameter ratio in the seamless steel pipe rolling.

For this reason, the present invention proposes a kind of pipe drawing machine, is used for rolling capillary pipe into waste pipe, and described pipe drawing machine comprises:

The bed, arranged on the rolling line, acts as a base to support each roll mold;

Multiple roller molds are arranged side by side in the bed;

Necking machine, located at the entrance of the bed;

The material receiving front is located upstream of the necking machine, receiving the capillary to be rolled;

The tube-drawing background is located at the exit of the bed, and the tube-drawing background supports the mandrel and the capillary;

The rack and pinion transmission system is located downstream of the backstage of the pulling tube;

The mandrel is connected to the rack and pinion transmission system, and the mandrel can move reciprocally and linearly between the material receiving front, the necking machine and the bed, the roller mold, and the drawing tube background, and,

When the mandrel is inserted into the capillary and put in place, the rack and pinion drive system pulls the mandrel, so that the mandrel pulls the capillary to move along the same rolling direction, and the capillary is drawn into shape and rolled. Become a waste management.

Further, the tube drawing machine further includes: a positioning baffle arranged upstream of the material receiving front.

Further, the tube drawing machine further includes: a lifting roller table arranged upstream of the positioning baffle, and the positioning baffle is connected between the lifting roller table and the material receiving front desk.

Further, the rack and pinion transmission system includes: a transmission motor, a gear connected to the transmission motor, and a rack meshed with the gear, wherein the rack is connected to the mandrel.

Further, the mandrel includes: a head, a rod body and a tail connected in sequence, and the rod body of the mandrel includes two sections, which are thick sections and thin sections connected to each other respectively, and the thick section is the working section of the mandrel, The length of the thin section is greater than the length of the bed, and the shaft shoulders of the thick section and the thin section are the necking positions of the mandrel. The head of the mandrel is located at the end of the thick section and is tapered. The clamping head, and the clamping head is connected with the thin section.

Further, the rack includes: a rack body engaged with a gear, and a rack head connected to the rack body, and the rack head is connected to the mandrel, wherein the rack The head is located under the rack main body, along the length direction of the rack, the top of the rack main body has engaging teeth, and the bottom surface of the rack head is straight.

Further, the pull tube backstage has a V-shaped roller table, and on a section perpendicular to the length direction of the rack, the bottom surface of the rack head is V-shaped.

Further, each roll mold includes three rolls, and the three rolls are driven to rotate around their respective rotation axes, and the included angle between the rotation axes of the three rolls is 60°, and the rolls in the adjacent roll molds are 60°. ° Phase angles are staggered to achieve 60° dislocation rolling in the circumferential direction of the capillary.

Further, each roll mold includes three rolls, and the three rolls are driven to rotate around their respective rotation axes, the angle between the rotation axes of the three rolls is 60°, and the adjacent roll molds adopt a 45° phase angle misalignment Arrangement to realize alternate rolling of 45° and 30° in the circumferential direction of the capillary.

The present invention also proposes a seamless pipe rolling method, the seamless pipe rolling method comprising:

Step A: the mandrel advances and puts the rod in place in the capillary;

Step B: Then, pull the mandrel back through the rack and pinion transmission system, so that the mandrel pulls the capillary and enters each roll mold along the same rolling direction, and the rolls in each roll mold are driven to rotate, and the The capillary is drawn into shape and rolled into a waste tube.

Further, the seamless pipe rolling method further includes step C: the bare pipe with the rod is removed from the background of the pipe drawing, and the process of loose rod and pipe removal is carried out, and step C occurs after step B.

In the present invention, after the mandrel is inserted into the capillary in place, the rack and pinion transmission system pulls the mandrel, so that the mandrel pulls the capillary to move along the same rolling direction, and the capillary is drawn into shape. Rolled into barren tube. In the present invention, the method of "pull" instead of "push" is used to produce rolled tubes, which avoids the problem of the stability of the pressure rods of production tools such as mandrels. At the same time, the number of racks (roller molds) to bite into is greatly increased, the roller molds are arranged in close contact, the bed is made shorter and more economical, the bed coefficient is smaller, and the maximum extension coefficient of the pipe drawing machine can be larger than that of the pipe jacking machine. It is a large extension pipe rolling mill.

Because the diameter of the mandrel can be made smaller, it is possible to produce a blank pipe with a smaller diameter than the existing jacking pipe, because there is no need to reserve a track space for the rack at the bottom of the bed like the jacking pipe (the rack does not need to wear bed), so the bed is lower and the frame is more rigid after being connected to the foundation. Because of the change from "push" to "pull", the buckling tool for ensuring the stability of the push rod and mandrel can also be omitted, which greatly saves the production time for changing product specifications.

Under the condition of the same specification, the present invention can provide greater rolling force than the pipe jacking machine, and at the same time, the number of biting racks is larger, providing greater elongation, and there is no stability problem of the pressing bar.

Description of drawings

Fig. 1 is a schematic diagram of the working principle of the present invention;

Fig. 2 is the structural representation of rolling line of the present invention;

Fig. 3 is the schematic diagram of the connection mode of rack and mandrel of the present invention;

Fig. 4 is the schematic diagram of the opening mode of the rack and mandrel of the present invention;

Fig. 5 is a schematic structural view of the receiving front desk of the present invention;

Fig. 6 is the structural representation of roller mold and bed of the present invention;

Fig. 7 is a schematic diagram of a hexagonal roll die of the present invention;

Fig. 8 is the octagonal roll die schematic diagram of the present invention;

Fig. 9 is a schematic structural view of the first rack according to the embodiment of the present invention;

Fig. 10 is a schematic structural diagram of a second rack according to an embodiment of the present invention;

Fig. 11 is a schematic structural diagram of a third rack according to an embodiment of the present invention;

Fig. 12 is a sectional view of the rack head of the present invention.

Explanation of reference numbers:

1 Lifting roller table 2 Positioning baffle 3 Material receiving front 4 Shrinking machine 5 Bed 6 Pulling tube backstage 7 Rack and pinion transmission system 8 Rack and rack track 9 Mandrel 10 Pressure wheel rocker 11 Lock lever 12 Disc spring (overlap spring ) 13 Rack 14 Guide plate 16 Long pipe buckle 17 Middle pipe buckle 18 Short pipe buckle 20 Roller mold 21 Middle ring 22 Left ring 23 Right ring 24 Roller mold 25 Positive ring 26 Side ring 27 Press block 29 Side tooth plate 30 Roll mold 31 roll 32 roll 33 roll 131 rack main body 133 rack head 50 rolling direction 60 capillary 65 V type roller table

Detailed ways

In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention will now be described with reference to the accompanying drawings.

As shown in Figure 1, the roll stand (roll die) of the present invention adopts idle roll rolling (that is, passive rolling), and the mandrel pulls the capillary to move together along the rolling direction 50, and the mandrel 9 and the capillary 60 pass through each Roller die 30 is rolled into required waste pipes. The mandrel head adopts a chamfered design, which is convenient for threading the rod, and the tail of the mandrel has a clamping end, which is used for locking and fixing the mandrel.

As shown in Figure 2, the present invention proposes a pipe drawing machine, which is used to roll capillary pipes into waste pipes, and the pipe drawing machine includes:

The bed 5 (or called the base) is arranged on the rolling line;

A plurality of roll molds 30 (three-roll rolling mill), arranged side by side in the bed 5;

The necking machine 4 is located at the entrance of the bed 5 and closes the head of the capillary. As a better option, the necking machine 4 closes the capillary 60 online, and its center is in line with the center of the capillary, on the same rolling line , using the capillary rolling line to shorten the interval between capillary perforation and pipe rolling, reduce heat dissipation, and facilitate the smooth progress of pipe drawing;

The material receiving front 3 is located upstream of the necking machine 4, and accepts the capillary to be rolled to ensure that the rolling line is centered. Enter the receiving front 3, the height of the receiving front 3 can be adjusted, so that the capillary to be rolled can ensure the centering of the rolling line;

The tube-drawing background 6 is located at the exit of the bed. The tube-drawing background 6 supports the mandrel 9 and the capillary 60. The tube-drawing background 6 transports the mandrel before rolling, and transports the waste tube after rolling. The hot mandrel is loaded, and the blank pipe rolled with the mandrel is discharged; the roller table 6 in the pipe drawing background can be lifted and lowered to accept mandrels of different diameters and blank pipes of different diameters. This is called a small lift. This action It is realized by the unified adjustment of the screw elevator (it can also be realized by other mechanisms); when the rack 13 comes over, it needs to avoid and realize a large lifting, and this action is realized by a separate hydraulic cylinder;

The rack and pinion transmission system 7 is located downstream of the pipe-drawing background 6 as a power source for rolling;

The mandrel 9 is connected to the rack and pinion transmission system 7, and the mandrel can move linearly back and forth between the material receiving front 3, the necking machine 4 and the bed 5, the roller mold 30, and the tube drawing background 6 , as shown in Figure 1, when the mandrel is put in place through the capillary, the rack and pinion drive system 7 pulls the mandrel, so that the mandrel pulls the capillary to move along the same rolling direction, and the The capillary is drawn into shape and rolled into a waste tube.

Wherein, in the present application, the rack clamps the mandrel and feeds it, passes through the bed 5, and wears the rod toward the capillary. The strength and so on are the same. In this application, the positioning baffle 2 stops the end of the capillary, and there are three buckle tiles (long pipe buckle 16, middle pipe buckle 17 and short pipe buckle 18) on the receiving front to fix the capillary, and then realize Threading the rod into place under the capillary static state, this threading method is the same as the pre-threading process in which the mandrel penetrates the capillary into place under the capillary static state before the pipe jacking.

Further, as shown in FIG. 2 , the tube drawing machine further includes: a positioning baffle 2 arranged upstream of the material receiving front 3 . The positioning baffle plate 2 is positioned to stop different capillary lengths, and the capillary is pushed to the shrinkage position by controlling the stroke of the hydraulic cylinder to fix the baffle and be close to the capillary.

Further, as shown in FIG. 2 , the pipe drawing machine also includes: a lifting roller table 1 arranged upstream of the positioning baffle 2, and the positioning baffle 2 is connected between the lifting roller table 1 and the receiving Between the front desk 3. The height of the lifting roller table 1 is adjusted in real time to accept mandrels of different diameters, so that the center of the mandrel and the center of the capillary are aligned with the center of the roller mold.

Further, the rack and pinion transmission system 7 includes: a transmission motor, a gear connected to the transmission motor, and a rack meshed with the gear, wherein the rack is connected to the mandrel. The rack and pinion transmission system 7 is used as the power source of rolling, the motor drives the reducer, and drives the rack and pinion to realize the feeding and retracting of the mandrel, thereby drawing the waste tube.

Further, the mandrel includes: a head, a rod body and a tail connected in sequence, and the rod body of the mandrel includes two sections, which are thick sections and thin sections connected to each other respectively, and the thick section is the working section of the mandrel, The length of the thin section is greater than the length of the bed, and the shaft shoulders of the thick section and the thin section are the necking positions of the mandrel. The tail part is the clamping head coupled with the rack, and the clamping head is connected with the thin section.

The rack track 8 is located at the rearmost end of the rolling line or downstream of the transmission system 7, and accepts the running rack, or stops to overhaul the rack.

As shown in Figure 2, the rolling process of the present invention is: the capillary coming from the perforation falls on the material receiving front 3, the positioning baffle 2 positions the capillary, and the roller table of the lifting roller table 1 and the drawing pipe background 6 is adjusted to the mandrel. At this time, the main drive motor in the transmission system 7 drives the gear, so that the rack on the rack track 8 clamps the mandrel and feeds it, passes through the bed 5, and puts the rod on the capillary. After it is in place, the necking machine 4 The head of the capillary tube is closed, and the roller table of the tube pulling background 6 is adjusted to the position of the waste tube, and the rack and pinion pull the mandrel back to draw the waste tube. Immediately afterwards, the barren tube with rod is removed from the backstage of the tube, and the next process of loose rod and tube removal is carried out.

As shown in Figure 9, the rack 13 adopts straight teeth that are easy to process, and its head is connected to the mandrel 9, and the double tooth surface of the rack 13 is processed. Open the tooth surface of the rack.

Further, as shown in FIG. 10 , the rack 13 includes: a rack body 131 engaged with a gear, and a rack head 133 connected to the rack body, and the rack head 133 is connected to the rack body. Mandrel 9 is connected, wherein, the rack head 133 is located under the rack body 131, as shown in Figure 10, along the length direction of the rack, the top of the rack body 131 has a The bottom of the rack main body 131 also has meshing teeth meshing with the gear, and the bottom surface of the rack head 133 is straight. In this way, the rack 13 can be lifted up into a horizontal "L" shape, and the head of the rack connected to the mandrel 9 can be properly optimized, so that the backstage roller table of the pipe drawing only needs to accept the mandrel or empty pipe during the rolling process. , without avoiding the tooth surface of the rack in turn.

Furthermore, as shown in FIG. 11 , along the length direction of the rack, the top of the rack body 131 has meshing teeth that mesh with the gear, and the bottom of the rack body 131 does not have meshing teeth that mesh with the gear, that is, the rack 13 Single tooth surface processing, the bottom of the rack body 131 is straight, and the bottom of the rack head 133 is straight. This preferred solution can be used when the drawing force of the pipe drawing machine is not so high. The single tooth surface of the rack 13 is processed to reduce the manufacturing cost.

Further, as shown in FIG. 12 , the pipe-drawing backstage 6 has a V-shaped roller table 65 , and the bottom surface of the head of the rack is V-shaped on a section perpendicular to the length direction of the rack. Optimize the shape of the rack head, according to the height of the roller table when the mandrel is in position, and make the corresponding rack head according to the roller surface of the V-shaped roller table in the backstage of the tube, so that the roller table can meet the mandrel conveying, and will not interfere with the gear The bars touch each other, which has the effect of streamlining auxiliary actions.

Further, as shown in Figures 6 to 8, each roll mold is a three-roll mill, and each roll mold includes three rolls, and the three rolls are driven to rotate around their respective rotation axes, and each roll mold 30 is arranged side by side on the In the bed, each roll mold includes three rolls, namely roll 31, roll 32, and roll 33. The three rolls are driven to rotate around their respective rotation axes A1, A2, and A3, and the included angle between the three axes is 60°. °, the rolls in adjacent roll molds are arranged in a staggered phase angle of 60°.

Side tooth plates 29 are arranged on both sides of the bed frame, and after the roller mold 30 is packed into the bed, it is fixed with a briquetting block 27. As shown in Fig. 6, the circular formwork 30, due to the staggered arrangement of adjacent roller molds, is placed around the rolling line by 180°, which brings inconvenience to the workshop for hoisting. This problem can be better avoided when adopting the hexagonal roll die 24 as shown in Figure 7 . The positive suspension ring 25 and the side suspension ring 26 are housed on the hexagonal roller mold 24. If a roll mold adopts the positive hanging ring 25 to face upward, then the adjacent roll mold adopts the side hanging ring 26 to face upward, so that the central planes of each roll of the adjacent roll mold realize a 60° dislocation arrangement. The above two forms of roll dies are equivalent to "six-sided" force-rolled blank pipes (that is, six-direction force-rolled pipes), and the advantage is to effectively suppress and eliminate the ear on the surface of the waste pipe produced by the roll gap between the rolls.

And then, as shown in Fig. 8, when adopting eight sides (eight sides) roll mold 20, adjacent roll mold adopts 45 ° dislocation arrangement, can obtain the blank tube equivalent to "nine directions" force rolling (rolling in nine directions) ). Bafang roller mold 20 is equipped with middle suspension ring 21, left suspension ring 22, and right suspension ring 23. If one roll mold adopts middle suspension ring 21 to face upward, then the front adjacent roller mold adopts left suspension ring 22 to face upward, and the rear adjacent roller mold adopts right suspension ring 23 facing upward, so as to realize the alternate arrangement of 45° and 30° in the circumferential direction. The frame outline of the Bafang roller mold 20 adopts Bafang, thereby realizing a 45° dislocation arrangement. In this way, the force in the circumferential direction of capillary rolling is reasonable, and the rolling is more uniform. Among them, the superimposed effect of the three adjacent roller molds being misplaced by 45° in turn is "nine squares".

Bafang roll mold 20 and hexagonal (hexagonal) roll mold 24 use the same rolls. Bafang roll mold 20 and hexagon roll mold 24 have the same shape except for the outer contour of the formwork and the number of suspension rings (3 and 2 respectively). Other than that, there is no other difference.

As shown in Figures 3 and 4, the rack and the mandrel adopt an automatic locking and opening connection mode. During the operation of the rack 13, the stacked spring 12 (disc spring) pushes the lock lever 11, and the mandrel 9 The clamping tail end is tightly locked and fixed on the rack 13. When the rack 13 is at the start or end position of the mandrel 9, the rack enters the guide plate 14, the pressure wheel rocker 10 is pressed, and the lock lever 11 is pushed to compress the folded spring 12. At this time, the rack 13 is opened, and the mandrel 9 It can be separated from it and loaded and unloaded, that is, single rod is loaded at the beginning of rolling, and rod tube is unloaded at the end of rolling (mandrel strip with blank tube after rolling). The loading and unloading stations are respectively located on both sides of the tube drawing background. During the rolling operation of the rack 13, the overlapping spring 12 pushes the lock lever 11 to lock the mandrel 9 on the rack 13. At this time, the rocker handle 10 of the pressure roller rises until it returns to the lower position of the guide plate 14 at the initial position. suppress.

As shown in Figure 5, the capillary from the perforation is placed on the material receiving front 3 within the pipe end line A4 and the pipe end line A5, and the long pipe buckle 16, the middle pipe buckle 17 and the short pipe buckle are arranged at equal intervals on the material receiving front 3. Pipe buckle tiles 18, these are the only buckle tiles of the pipe drawing unit, the purpose is to buckle the capillary and facilitate threading of the rod. The capillary can be long or short, and the action of buckling the tile can be selectively controlled according to its length. When the capillary incoming material is a long capillary, the long tube buckle 16, the middle tube buckle 17, and the short tube buckle 18 are buckled at the same time, the positioning baffle 2 is in place, and the capillary tail is attached to the capillary when threading the rod. stop. After the rod threading is completed, the necking machine 4 closes the head end of the capillary; when the incoming capillary is a medium-length capillary, the long tube buckle 16 is opened, the middle tube buckle 17 and the short tube buckle 18 are buckled at the same time, and the positioning stop The plate 2 stops in place, and the necking machine 4 closes; when the capillary incoming material is a short capillary, the long pipe buckle 16 and the middle pipe buckle 17 are opened, the short pipe buckle 18 is buckled, and the positioning baffle 2 is in place to stop, Shrinking machine 4 closes. The positioning baffle 2 of the tube drawing machine is used to position and stop different capillary lengths. The long-stroke hydraulic cylinder is controlled by the overflow valve to push the capillary to the shrinking position and the swing-type fixed baffle is close to the capillary. On the receiving front 3 The fastening tile buckles the capillary, and then the fixed baffle at the necking is opened, waiting for the rod to be worn. The necking machine is fixed, and the necking position of the mandrel is calculated and positioned by the encoder.

The present invention has significant differences in its transmission arrangement, force bearing mode and tool design, and belongs to the new method of CPE. The motor drives the rack through the reducer, and pulls the mandrel to make the waste tube. Under the condition of the same specification, the present invention can provide greater rolling force than the pipe jacking machine, and at the same time, the number of biting stands is more, and greater elongation is provided. The present invention can provide a more efficient and economical production method of seamless steel pipes rolled with greater elongation, and the roll dies are arranged close to each other. At the same time, the modulus of the biting rolls is greatly increased, the bed coefficient is smaller, and the diameter of the mandrel is smaller. The diameter of the blank pipe can be produced smaller, and there is no problem with the stability of the pressure bar, which greatly saves the replacement time of tile buckle tools and product specifications.

The above descriptions are only illustrative specific implementations of the present invention, and are not intended to limit the scope of the present invention. Because the various components of the present invention can be combined with each other under the condition of no conflict, any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall belong to the protection of the present invention. range.

Claims (11)

1. a bench, for hollow billet is rolled into hollow forging, is characterized in that, described bench comprises:

Lathe bed (5), is arranged on roll line;

Multiple roller die, is disposed in parallel in lathe bed (5);

Necking machine (4), is positioned at the entrance of described lathe bed (5);

Material feeding foreground (3), is positioned at the upstream of necking machine (4), bears hollow billet to be rolled;

Trombone slide backstage (6), is positioned at the outlet of described lathe bed, and described trombone slide backstage (6) supports plug and hollow billet;

Rack pinion system (7), is positioned at the downstream of described trombone slide backstage (6);

Plug, connect described rack pinion system (7), and described plug can at material feeding foreground (3), necking machine (4) and lathe bed (5), carry out reciprocating linear between roller die (30) and trombone slide backstage (6) and move, and

When plug is worn after hollow billet puts in place, described rack pinion system (7) pulls plug, makes described plug pull described hollow billet to move along same rolling direction, draws shaping, be rolled into hollow forging by described hollow billet.

2. bench as claimed in claim 1, it is characterized in that, described bench also comprises: the positioning baffle (2) being arranged on described material feeding foreground (3) upstream.

3. bench as claimed in claim 2, it is characterized in that, described bench also comprises: the rise and fall roller (1) being arranged on described positioning baffle (2) upstream, described positioning baffle (2) is connected between described rise and fall roller (1) and described material feeding foreground (3).

4. bench as claimed in claim 1, it is characterized in that, described rack pinion system (7) comprising: driving motor, the gear be connected with described driving motor, with the tooth bar of described gears meshing, wherein, described tooth bar is connected with described plug.

5. bench as claimed in claim 4, it is characterized in that, described plug comprises: the head connected successively, excellent body and afterbody, the excellent body of described plug comprises two sections, interconnective thick section and thin segment respectively, thick section is plug active section, the length of thin segment is greater than lathe bed length, thick section and thin segment shaft shoulder place are the reducing position of plug, it is tapered that the head of plug (9) is positioned at thick section termination, the afterbody of described plug (9) is the clamping head connected with tooth bar, and described clamping head is connected with described thin segment.

6. bench as claimed in claim 4, it is characterized in that, described tooth bar comprises: with the tooth bar main body of gears meshing and the tooth bar head that is connected with described tooth bar main body, described tooth bar head is connected with described plug, wherein, described tooth bar head is positioned under described tooth bar main body, along the length direction of tooth bar, the top of described tooth bar main body has tooth engaged, and the bottom surface of described tooth bar head is straight.

7. bench as claimed in claim 4, it is characterized in that, described trombone slide backstage has V-type roller-way, and on the section of vertical tooth rack length direction, the bottom surface of described tooth bar head is V-type.

8. bench as claimed in claim 1, it is characterized in that, each roller die comprises three rolls, three rolls are respectively around the respective driven rotation of rotation axis, angle between the rotation of three rolls is 60 °, roll in adjacent roller die is 60 ° of phase angle interlaced arrangement, realizes hollow billet circumferentially 60 ° of dislocation rollings.

9. bench as claimed in claim 1, it is characterized in that, each roller die comprises three rolls, three rolls are respectively around the respective driven rotation of rotation axis, angle between the rotation of three rolls is 60 °, adjacent roller die adopts 45 ° of phase angle dislocation to arrange, realizes hollow billet circumferentially 45 ° and the 30 ° dislocation rollings replaced.

10. a seamless pipe milling method, is characterized in that, described seamless pipe milling method comprises:

Steps A: plug advances and wears rod and puts in place in hollow billet;

Step B: then, pull plug rollback by rack pinion system (7), make described plug pull described hollow billet to enter in each roller die along same rolling direction, the driven rotation of the roll in each roller die, described hollow billet is drawn shaping, is rolled into hollow forging.

11. seamless pipe milling methods as claimed in claim 10, it is characterized in that, described seamless pipe milling method also comprises step C: trombone slide backstage transferred to by described waste pipe racks rod, and carry out the de-plumber's sequence of pine rod, step C occurs after stepb.