JPS5992108A - Reduced thickness rolling method by reduced thickness rolling device for pipe end in installation for producing seamless steel pipe - Google Patents

Abstract

PURPOSE:To make the wall thickness of a finish pipe obtd. in reduction uniform by providing the clearance as much as the predicted amt. of the expansion in the outside diameter at the end of a hollow blank pipe with reduced thickness rolling of said pipe is offset between the inside diameter of the hollow blank material prior to the reduced thickness rolling and the outside diameter of a mandrel and suppressing the expansion in the outside diameter with the reduced thickness rolling. CONSTITUTION:The rear end of a hollow blank pipe 6 is fed 39 into the working center of a reduced thickness rolling device 12 for pipe end. A mandrel 13 and rolling rolls 14 are set respectively in rolling down positions. Driving devices 21, 28 for revolution and rotation are respectively operated to bring the rolls 14 into contact with the outside peripheral part at the end of the pipe 6 in the state of revolution and rotation. The amt. of expansion in the outside diameter at the end of the pipe 6 with the reduced thickness rolling by the mandrel 13 and the rolls 14 is predicted during this time, and a clearance as much as the predicted amt. of expansion is offset is provided between the inside diameter of the blank pipe 6 prior to the reduced thickness rolling and the outside diameter of the mandrel 13. The pipe 6 subjected to the rolling is thus negated of the amt. of expansion with the thickness reduction and the part which is not rolled by the rolls 14 is made approximately equal in the outside diameter to the part rolled by said rolls.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thinning rolling method using a tube end thinning rolling device in seamless steel pipe manufacturing equipment.

The manufacturing process for seamless steel pipes consists of a perforation process in which holes are made in the raw round steel piece, and a stretching process in which the perforated hollow tube is stretched with reduced thickness.
8, and finish rolling to narrow the elongated hollow shell tube to a predetermined outer diameter (3-[degrees of "-").

That is, in a typical manufacturing process for seamless steel pipe using a Mann 12-rel mill, for example, as shown in FIG. After that, the piercer mill 3 is used as a piercing rolling mill.
Perforated by f+, studied.

Next, with the mandrel bar 4 inserted, 9■6
+I+= by mandrel mill 5 as a stretching machine
Extension can be added to extension I. The hollow J-tube 6 which has been stretched to twice or four times the length by the mandrel mill 5 is heated in a reheating furnace 7 if necessary, and then reduced by a stretch reducer 8 as a finishing mill. The finished tube 9 is then rolled.

By the way, in the above-mentioned trench reso user 8, the hollow blank tube 6 into which no mandrel bar is inserted is reduced and rolled by a large number of rows of roll stands each having an oval hole shape.
A finished tube 9 with a predetermined outer diameter and wall thickness can be formed. Here, the diameter of each roll hole shape in the continuous roll stand rows of the trench reducer 8 is set so that the later the stage, the smaller the diameter, and the roll hole shape of the final roll stand is set to a predetermined outer diameter of the finished tube 9. This allows the outer surface of the finished tube 9 to be finished molded. Here, the wall thickness of the hollow tube 6 formed in the stretch reducer 8 becomes thicker as its outer diameter is narrowed down to a smaller diameter by the roll hole type of each roll stand, and it also increases in thickness as it passes through the oval hole type. This causes the tube to be deformed non-uniformly in various parts in the circumferential direction, resulting in non-uniform wall thickness, resulting in the inconvenience that a finished tube 9 of good quality cannot be obtained.

To solve the above-mentioned disadvantages (in the conventional seamless steel pipe manufacturing process, the stretch reducer 8
When rolling out the material, while applying a tensile force in the axial direction of the hollow shell 6 between each roll stand, the unevenness in wall thickness in the cross section of the hollow shell 6 is reduced, and at the same time, the tension is applied by the roll rotation speed of each roll stand. This makes it possible to control the thickness increase or decrease the thickness to obtain a finished pipe 9 with a predetermined wall thickness.

However, even with the above-mentioned conventional seamless steel pipe manufacturing method, there is a gap between the roll stands at both ends of the hollow tube 6 between the point where it passes through one roll and is bitten into the next roll. Sufficient tensile force cannot be applied. In other words, it is impossible to remove the uneven thickness of both ends of the hollow wood pipe 60 due to increased thickness, and the finished pipe is 90 pieces! 1
It becomes necessary to cut off the thickened part that occurs in part 14. ``Title''
- The amount of the thickened portion at both ends of the trench tube 9 to be cut off depends on the outer diameter reduction ratio in the trench reducer 8 or the degree of control of the roll rotation speed in each roll stand. The ratio of the length with both ends cut off to the total length reaches about 5% on average.

Therefore, in order to ensure that the wall thickness of the finished pipe obtained by the above-mentioned edge rolling is uniform in the entire longitudinal direction, the present applicant has proposed
According to the 4+1 document and the drawings, [the core metal inserted into the inner periphery of the end of the hollow shell tube that has been punched and rolled, and the core metal that revolves around the outer periphery of the end of the hollow shell into which the core metal is inserted] and a rolling roll that rotates and comes into contact with the hollow shell and rolls down the end of the hollow shell; We have already proposed a thinning rolling method using a tube end thinning rolling device in a seamless steel pipe production facility that enables the thickness to be thinned in advance.

However, in the case of the thinning rolling method using the tube end thinning rolling apparatus already proposed above.

As shown in FIGS. 2 and 3, it is possible to roll the hollow shell 6 toward the outer end with thinning of the core metal 13 and the rolling rolls 11. , 3rd
As shown in the figure, the outer diameter of the hollow shell 6 increases toward the outer end, and the outer diameter reduction ratio in the subsequent trench reso user 8 becomes a dog, and as a result, the outer diameter increases at the end of the hollow shell 6. A thinning phenomenon occurs, and the effect of tube end thinning rolling is impaired.

The present invention provides a seamless steel pipe that suppresses the expansion of the outer diameter due to thinning rolling at the end of the hollow mother pipe and reliably makes the wall thickness of the finished pipe obtained by reduction rolling uniform in its entire longitudinal direction. The object of the present invention is to provide a thinning rolling method using a tube end thinning rolling device in a manufacturing facility.

In order to achieve the second object, the present invention provides a core metal inserted into the inner periphery of the end of a hollow raw tube that has been perforated and drawn and rolled, and a hollow raw tube into which the core metal is inserted. A rolling rJ-rule that revolves and rotates in contact with the outer periphery of the end and rolls down the end of the hollow shell, and the end of the hollow shell is rolled by the reduction rolling that follows the elongation rolling. A thinning rolling method using a thinning tube end thinning rolling device in a seamless steel pipe manufacturing equipment that enables the wall thickness of the thickened portion to be thinned in advance, the method comprising: reducing the outer diameter of the end due to the above thinning rolling. The amount of pipe expansion is predicted, and the thickness reduction rolling is performed by providing a clearance between the inner diameter of the hollow shell tube before thinning rolling and the outer diameter of the core metal to offset the predicted amount of pipe expansion.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 4 is a 1111 side view, partially cut away, showing an example of a tube end thinning rolling apparatus used for carrying out the present invention, and FIG. 5 is a front view of FIG. 4.

The tube end thinning rolling apparatus 12 shown in FIGS. 4 and 5 includes a mandrel mill 5 and a reheating furnace 7. Placed between a
The end portion of the hollow tube 6 which has been elongated and rolled by the mandrel mill 5 has a thickness reduction pressure of +14 rUJ. That is, the V-end thinning rolling device 12 is.

Hollow wood pipe 50) Q: Core metal 13 inserted into the inner circumference of the M section
and three rolling rolls 14 that contact the outer circumferential portion of the hollow shell 6 into which the core metal 13 is inserted in a state of revolution and rotation, and that enable the hollow shell 6 to be rolled down toward the center. Therefore, the ends of the hollow tube 6 are adapted to be rolled so that the outer ends thereof in the J-direction of the axis become thinner. , each rolling I''-rule 14 has a support shaft 14 on a chock portion 158 of each rolling device 15.
It is supported to rotate on its own axis via A, and is moved forward and backward toward the center of the core metal 13 by a lowering mechanism of the downstream device 15, which will be described later. The lowering device 15 is mounted on the pedestal 16.
At one end portion 1B8 of the revolving housing 18, which is rotatably supported coaxially with respect to the core metal 13 via the support 17, there are arranged at three equally spaced positions in the circumferential direction around the core metal 13. This allows each rolling roll 14 to come into contact with the outer periphery of the end of the hollow tube 6 into which the cored metal 13 is inserted, in a state of revolution and rotation. Furthermore, pressure 9JjHo-ru 1
4 is the center of rotation of the core metal 13 and the hollow tube 6.
It is set in a direction different from the line bIIqIl, and when the rolling roll 14 revolves around the outer periphery of the hollow shell 6, rotates, and comes into contact with it, a relative spiral motion is created between the hollow shell 6 and the rolling roll 14. It is possible for this to occur. A gear 19 is attached to the outer periphery of the end of the revolving housing 18 opposite 1N+1 from the lowering device 15.
It is designed to be rotationally driven by.

A shaft of a gear 22 supported on the inner circumference τ111 of the revolving housing 18 is connected to a 1 m1 portion of the support 11i11114A of the rolling roll 14 via a universal joint 23.

The gears 22 are arranged at three equal intervals on the inner periphery of the revolving nozzle 18 in correspondence with the rolling rolls 14, and each gear 22 is connected to the core metal 13.
It is possible to mesh with a ring-shaped gear 24 arranged at the same +lqh angle as the revolving nozzle 18 around the periphery. The gear 24 is integrally provided on the outer periphery of a cylindrical sleeve 25, and the sleeve 25 is coaxial with the core metal 13 and is arranged relative to the core metal 13 in the axial and rotational directions via a bearing 26 on the outside thereof. movably supported. One end of the sleeve 25 projects outward from the end of the revolution housing 18 on the gear 19 side, and a ring-shaped gear 27 is attached to the periphery of this projection row. A gear 29 attached to the output shaft of a rotation drive device 28 is meshed with the gear 27, whereby the sleeve 25 is rotationally driven around the core metal 13, and is rotated through the gears 24, 22 and the universal joint 23. Each rolling roll 14 is driven to rotate.

1) The No. 11 pressure F device 15 rotates the No. 110 rolling roll 1 by the rotation of the pinion 31 screwed into the fE lower screw 30.
4 can move forward and backward in the rolling direction. This Binion 31
meshes with a rack 32 inserted into one end 18A of the revolving housing 18 from the axial direction, and is rotationally driven by movement of the rack 32 in the axial direction. Three racks 32 are arranged corresponding to the rolling wheels 14, and one end in the axial direction of the racks 32 is connected to the 1111 surface of the ring 33. The inner surface of the outer end of the ring 33 is inserted between a pair of I+-ra 36 rotatably attached to the ram 35 of the hydraulic device 34, and thereby the ring 33
3 can be driven in the axial direction even though it does not rotate together with the revolving housing 18.

In Fig. 1, 37 is a wheel that allows movement of the frame 16, 38 is a vinyl roll that allows the hollow tube 6 to be inserted, and 39 is a feeder that allows the hollow tube 6 to move forward and backward in the axial direction. The roller 40 is a hydraulic device that allows the core metal 13 to move forward and backward in its axial direction.

Next, an embodiment of the thinning rolling method according to the present invention in which the pipe end thinning rolling device 12 is operated once a month will be described.

First, as explained in FIG.
The pipe is carried into the processing center of the tube end thinning rolling device 12 for the rear end. Here, the wheels 37 of the pedestal 16 are kept stationary,
The core bar 13 and the rolling rolls 14 are each held at a retracted position in the axial direction with respect to the hollow tube 6, and the radial position (rolling position) of each rolling roll 14 is held at the retracted position. When it is confirmed, for example, by the detection signal from the infrared detection z:(, that the rear end of the hollow tube 6 has been inserted into the processing position of the tube end thinning rolling device 12, the core metal 13 and the rolling roll 14 are each advanced in the axial direction by a set distance, and then the downstream position Kv of the rolling roll 14 is determined.

When the core bar 13 is advanced and inserted into the hollow tube 6, the hollow tube 6 is fixedly held by the pinch lever 38.

At the same time as the setting of the rolling position of the rolling rolls 14 is completed as described above, the pinch rolls 38 release the hollow tube 6, and the revolution drive device 21 and the rotation drive device 2
8 is activated, and the rolling rolls 14 are brought into contact with the outer circumference of the end portion of the hollow tube 6 in a state in which it revolves and rotates on its own axis. Here, since the rolling shafts of the rolling rolls 140 are arranged in different directions with respect to the shafts of the hollow shell 6 and the core metal 13, the rolling rolls 14 and the hollow shell 6 are relatively spiral. Interlock. On the other hand, since the pedestal 16 is held stationary,
Based on the above-mentioned spiral movement, the hollow tube 6 moves in its axial direction, and gradually changes its rolling position by the rolling rolls 14 to its outer end 1.
Displace it to +111.

Therefore, when the revolution speed and the autorotation speed of the roll rolls 14 are arbitrarily set, the roll rolls 14 apply rotational torque to the hollow shell 6.

The hollow blank tube 6 moves in the axial direction while swinging around its own axis, and twisting deformation occurs at the end of the hollow blank tube 6.

Therefore, in this actual hflj example, H-rolling roll 1
The revolution rotation speed and the autorotation rotation speed of the rolling rolls 14 are mutually adjusted so that the rolls 4 do not apply rotational torque to the ends of the hollow shell 6, and the rolling rolls 14 are rotated in the axial direction without rotating the hollow shell 6. It is designed for mobile use.

As the hollow tube 6 moves in the axial direction without rotating as shown in the figure, the rolling rolls 14 move.

The preset thickness reduction rate, that is, the increase in thickness added to the end of the hollow shell 6 by the subsequent reduction rolling, is offset.
The end portion of the hollow tube 6 is thinned at a thinning rate that is determined to be suitable for filtration. The thinning operation by the rolling roll 14 is performed by driving the ring 33 via the roller 36 by the hydraulic device 34,
By rotating the binion 31 through the rack 32 thereby.

This is done by rolling down the rolling rolls 14. Here, the core metal 13 is projected by the hydraulic device 40 so as not to move relative to the hollow tube 5.

Thereby, while the rolling rolls 14 are rolling the hollow shell 6 to reduce its thickness, the core metal 13 is maintained in the inserted state with respect to the hollow shell 6.

Therefore, in this embodiment, the amount of expansion of the outer diameter of the end of the hollow shell 6 due to the thinning operation by the core bar 13 and the rolling roll 14 and the thinning rolling is prefilled, and the A clearance should be provided between the inner diameter of the hollow tube 6 and the outer diameter of the core metal 13 to offset the predicted tube expansion M.
, the hollow wood pipe 60 is thinned, and the core metal 13 having an outer diameter smaller than the inner diameter before rolling is used. teeth,
As shown in FIG. 6, the amount of tube expansion due to thinning is canceled out, and the outer diameters of the unrolled part and the rolled part by the rolling rolls 14 are approximately the same, and the thinner wall is rolled towards the outer end in the axial direction. will be administered. As shown in FIG. 6, the inner diameter of the rolled part by the rolling rolls 14 is smaller than the inner diameter of the non-rolled part, creating a step.
Since the tube is rolled while applying a tensile force through the reduction rolling, the above-mentioned step does not remain in the finished tube.

When the thinning rolling of the rear end of the hollow shell 6 is completed in this way, the rolling position of the rolling roll 14 is opened, and the core metal 1 is opened.
3 is retracted by the hydraulic device 40 and pulled out from the hollow shell 6. The inner tube 6, which has undergone the thinning 1'E rolling of the retreated portion, is then carried into the processing center of the tube end thinning rolling machine for the front end, and the front end is reduced in the same way as the rear end. The flesh is rolled.

Figure 7 shows %'W:IA thickness reduction1. tt, 6T and a diagram showing the relationship between outer diameter expansion amount ΔD. In other words, Fig. 7 shows a hollow tube with an outer diameter of 890 mm, a wall thickness of 645 mm, and a length of 2,500 mm, which is thinned by cylindrical rolling rolls at a rolling temperature of 950°C and a roll inclination angle of 6 degrees. Thickness T of the unrolled part by rolling rolls when applied. and wall thickness T1 of the rolled part
The relationship between the difference between the thickness reduction amount ΔT and the difference between the outer diameter Do of the non-rolled part and the outer diameter D1 of the rolled part by the rolling rolls, that is the pipe expansion amount ΔD, is expressed as , is expressed by the exponential function of the following (υ equation).

△D=8.69△T1.99...
(1) The general relationship between the amount of wall thinning ΔT and the amount of pipe expansion ΔD is expressed by the exponential function of the following equation (2).

ΔD=K・ΔTn・・・・・・
- (2) In the above formula (2), the coefficient KI n is the tube outer diameter and wall thickness.

It is determined in advance based on the roll inclination angle, rolling degree, rolling speed, tube material, roll shape, etc. Therefore, the relationship between the amount of thinning △T and the tube expansion 1Nkm D is determined in advance according to the rolling conditions.
It becomes possible to predict one pipe expansion due to thinning rolling and set the clearance to be provided between the inner diameter of the hollow shell and the outer diameter of the core metal.

Hereinafter, a specific implementation result will be described in the case where the end portion of a hollow wood pipe with an outer diameter of 88.9-=- and a wall thickness of 645- is subjected to a thickness reduction of 1.2-.

According to the above equation (1), when determining the outer diameter expansion amount ΔD for the wall thickness reduction amount ΔT=1.2−, ΔD=12.5=−.

Therefore, the clearance that should be provided between the inner diameter of the hollow shell pipe before rolling and the outer diameter of the core metal is equivalent to the above-mentioned pipe expansion amount D σ)
It may be set to 12.5-'-. Therefore, the outer diameter of the core metal 13 to be used is 63.5 mm. This core metal 13
When thinning was carried out using the same method, it was possible to make the outer diameters of the unrolled part and the rolled part of the hollow shell 6 substantially equal to f+1.

When the hollow blank tube 6 subjected to thinning rolling in this manner is rolled into a finished tube with an outer diameter of 50.8-'-1 and a wall thickness of 6.45 =- and a width of 22 in the trench reso user 8. Table 1 was obtained as a result of comparing the crop lengths of the leading and trailing ends with those of the conventional method.

Table 1 According to this Table IK, it is observed that by implementing the present invention, the crop truncation length can be significantly reduced and the yield can be improved by 1.1-1.

In the above embodiment, the hollow shell 6 is released by the vinyl rolls 38 during thinning rolling by the rolling rolls 14. However, in the piping end thinning rolling device 12, the middle piping blank tube 6 is fixed by the pinch rolls 38 during the thinning rolling by the rolling rolls 14.

The pedestal 16 may be movable 11t.

- In addition, the above-mentioned embodiment has the present invention in a tube end thinning rolling device 12 that uses rolling rolls 14 that are arranged in opposite directions with respect to the hollow tube 6 and that move relatively in the axial direction of the hollow tube 6. We have explained the case where it is applied. However, the present invention provides a V-end thinning rolling device in which the rolling rolls are not disposed in opposite directions with respect to the hollow shell tube, and is provided with other means for moving the rolling rolls and the hollow shell tube relative to each other in the axial direction, or .

For use in pipe end thinning rolling equipment, etc., which uses rolling rolls having a roll width equal to or greater than the length of the end of the hollow shell to be thinned, and where there is no peace of mind in moving the rolling roll and the hollow shell relative to each other in the axial direction. is also an applicable σj function.

“In addition, the present invention is not only applicable to the manufacturing process of seamless steel pipes based on the mandrel mill method, but also applicable to the manufacturing process of seamless steel pipes using other rolling methods such as the plug mill method.” ] It is Noh.

As described above, the present invention relates to a core metal inserted into the inner periphery of the yfM section of a hollow wood pipe that has been perforated and stretched and rolled.

a rolling roll that revolves and rotates in contact with the outer periphery of the end of the hollow shell into which the core metal is charged, and that rolls down the end of the hollow shell, and the rolling roll is provided after the elongation and rolling. A wall thinning rolling method using a tube end thinning rolling device in a seamless steel pipe manufacturing facility that enables the thickness increase added to the end portion of the hollow mother pipe by rolling to be thinned in advance, the method comprising: The amount of expansion of the outer diameter of the end due to this is predicted, and a clearance is provided between the inner diameter of the hollow blank tube before thinning rolling and the outer diameter of the core metal to offset the predicted amount of expansion, and the thinning rolling is performed. Therefore, it is possible to suppress the expansion of the outer diameter due to thinning rolling at the end of the hollow mother pipe, and to ensure that the wall thickness of the finished pipe obtained by reduction rolling is uniform in its entire longitudinal direction.

[Brief explanation of drawings]

Figure 1 is a process diagram showing the manufacturing process of general seamless steel pipes.
FIG. 2 is a front view showing the state of thinning of a hollow shell tube by the tube end thinning rolling apparatus already proposed by the present applicant, FIG. 3 is a sectional view taken along line Ill-II in FIG. 2, FIG. 4 is a partially cutaway side view showing an example of a tube end thinning rolling device used in the implementation of the present invention, FIG. 5 is a front view of FIG. 4, and FIG. FIG. 7, which is a central longitudinal sectional view of the steel pipe obtained by wall rolling, is a diagram showing the relationship between the amount of tube end wall thinning and the amount of outer diameter expansion. 3°°Hearther Mill, 5°” Mandrel Mill, 6.
・・Hollow tube, 8・・Stretch reso user, 11゛°
Pipe end thinning rolling device, 13゛・core metal, 14... rolling roll, 21... revolution drive device, 28... 1] diversion drive device. Agent Patent Attorney Osamu Shiokawa

Claims (1)

[Claims] (1) A core metal is inserted into the inner periphery of the end of the hollow shell tube that has been drilled and stretched, and the core metal is inserted into the outer periphery of the hollow shell tube that revolves and rotates on its axis. a rolling roll that is in contact with and rolls down the end of the hollow shell,
In a seamless steel pipe manufacturing facility, the wall thickness other than the wall thickness added to the end portion of the hollow mother pipe can be reduced in advance by the reduction rolling that follows the elongation rolling. A wall rolling method in which an expansion (1 t) of the outer diameter of the end that is capable of the wall thinning rolling is predicted, and the predicted tube expansion amount is offset between the inner diameter of the hollow blank tube before thinning rolling and the outer diameter of the core bar. A thinning rolling method using a tube end thinning rolling device in a seamless steel pipe production facility, which performs thinning rolling with a clearance just enough to do so.