JPH10180313A - Skew rolling method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To roll a hard-to-work tube stock such as Ni-base alloy without generating plastic deformation on a mandrel. SOLUTION: This rolling method is composed so that the tube stock H is drawn while imparting tensile force to the tube stock H from the front in the advancing direction of the tube stock H, the tube stock H is elongated between plural inclined rolls 21 which are arranged around the pass line X and the mandrel 11 which is inserted into the tube stock H and a rolled tube M is manufactured. In such a case, the tube stock H is elongated while advancing the mandrel 11 in the advancing direction of the tube stock H.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly applicable to Ni-based alloys and high N
The present invention relates to an inclined rolling method and an apparatus for producing a thin rolled tube by elongating and rolling a material tube of a difficult-to-process material such as an i-alloy steel tube.

[0002]

2. Description of the Related Art As a method for producing a seamless pipe by extending a raw pipe, there is an inclined rolling method as shown in FIG. FIG. 5 is an enlarged view of a portion in a state where elongation rolling is being performed, and FIG. 5A is a diagram showing a state in which rolling is being performed by a tilt rolling device as viewed from the front side of the outlet side of the tube. FIG. 2B is a cross-sectional view taken along the line BB of FIG. 2A, and FIG. 2C is a view taken along the arrow C of FIG. 2B.

[0003] Three inclined rolls 21 around the pass line X
a, 21b, and 21c are rotatably provided in a drive unit (not shown) at 120 ° intervals. The drive shaft of each inclined roll 21 (general name of the inclined rolls 21a, 21b, 21c)
As shown in FIGS. 3B and 3C, the path line X is inclined with an intersection angle α and an inclination angle β.

[0004] The material tube H into which the mandrel 110 is inserted and rotating passes between the inclined roll 21 and the mandrel 110 while passing between the inclined roll 21 and the mandrel 110.
Between the rolled tube M
become. At this time, the end of the rolling tube M in the traveling direction is pulled in the feed direction by a pulling device (not shown) as shown by a white arrow, and gives a predetermined tension or a propulsion speed to the rolling tube M. In addition, the rotation of the inclined roll 21 and the inclined angle β rotate the raw material tube H and apply a propulsive force in the feed direction.

[0005] The inclined roll 21 is composed of two truncated cones, and the half cone angle of the first truncated cone portion is equal to the intersection angle α.
The half cone angle of the second truncated cone provided continuously with the first truncated cone portion is formed smaller than the intersection angle α. When the material tube H is inclinedly rolled, first, the material tube H is rolled by a rolling surface S1 which is relatively inclined with respect to the pass line X,
Next, rolling is performed on a rolling surface S2 that is relatively small and inclined with respect to the pass line X.

[0006] The mandrel 110 is shown in FIG.
As shown in (C), when the material tube H is inclinedly rolled by the inclined rolls 21 to produce the thin-walled rolled tube M, it has a role of defining the shape of the hollow portion of the produced rolled tube M. The mandrel 110 is connected to the tip of the mandrel shaft 120.

When the material tube H is subjected to tilt rolling, the mandrel 110 inserted into the material tube H during rolling is seized with the inner surface of the tube. Further, the mandrel 110 may reach a high temperature range and cause plastic deformation. In the drawing process of the steel pipe, oxide scale is grown on the surface of the mandrel 110 by a specific heat treatment, and seizure and temperature rise are avoided by using the heat insulating effect and the lubricating effect of the scale and the oxide scale generated on the inner surface of the steel pipe. ing.

[0008]

However, when manufacturing seamless pipes such as Ni-base alloys, high-Ni alloys, or Co-base alloys used for a chemical plant or a steam generator of a nuclear reactor, such difficult processing is required. A material having high deformation resistance and low deformability has a high heating temperature of 1050 to 1200 ° C., which is equal to or higher than that of a steel pipe.

In general, the Ni-base alloy tube is cold-rolled from the extruded tube by Pilger rolling at a low forming speed. When hot rolling such small-diameter pipes, the mandrel to be inserted into the pipes is inevitably small, cannot take a water-cooled structure, has a small heat capacity, and has a high deformation resistance of the Ni-based alloy. The temperature may rise and plastic deformation may occur. At this time, heat transfer to the mandrel is intense due to the processing temperature and heat generated during processing. In addition, the Ni alloy has excellent oxidation resistance, and the oxide scale is thin and dense, so adiabatic lubrication like a steel pipe is used. No effect can be expected.

For this reason, a glass lubricant was applied to the inner surface of the pipe as a high-temperature lubricant, but the problem that plastic deformation occurred in the mandrel and hindered rolling could not be solved. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inclined rolling method and apparatus capable of rolling a hard-to-work material tube such as a Ni-based alloy without causing plastic deformation of a mandrel. I do.

[0011]

According to the present invention, in order to achieve the above object, the inclined rolling method according to the present invention comprises the steps of: In the inclined rolling method of producing a rolled tube by stretching and rolling the material tube between a plurality of inclined rolls arranged around the pass line and a mandrel inserted into the material tube,
The material pipe is stretched and rolled while the mandrel is advanced in the traveling direction of the material pipe.

Further, the tilt rolling device of the present invention comprises a tension means for pulling the material pipe while applying a tensile force to the material pipe from the front in the traveling direction of the material pipe, and a plurality of inclined means arranged around the pass line. A roll, and a mandrel holding device that holds the mandrel inserted into the material pipe, and gradually feeds the mandrel in the traveling direction of the material pipe during rolling, between the inclined roll and the progressively mandrel. And elongating and rolling the raw material tube to produce a rolled tube.

As a result of repeated investigations on the cause of the plastic deformation of the above-mentioned mandrel, the present inventors found that the same portion of the mandrel, when viewed in the axial direction, was in high-temperature contact locally during rolling and was in contact with the inner surface of the pipe. It has been found that friction and heat of deformation of the tube are caused by local heating of the mandrel. Therefore, by gradually moving the mandrel forward in the direction of travel of the tube during rolling, the mandrel is relatively moved with respect to the inclined roll, and the same part of the mandrel is not subjected to a load from the start to the end of rolling without being continuously loaded. / It has been found that by dispersing the stress load, the temperature rise of the mandrel can be suppressed to prevent plastic deformation, and the present invention has been achieved.

In this case, the shape of the mandrel preferably has a long columnar portion to be unwound during elongation rolling in order to distribute load. In addition, it is preferable that the mandrel shaft connected to the mandrel is rotatably held, the relative speed of the inner surface of the tube in the rotation direction is reduced, and the frictional heat generation is suppressed.

Further, by setting the forward speed of the mandrel to 1% or more of the exit speed of the rolling tube, it is possible to avoid concentration of a heat load and effectively prevent plastic deformation. In addition to such a method, when rolling a material tube made of a material having high deformation resistance at a high temperature such as a Ni-based alloy, it is preferable to use a mandrel made of a heat-resistant alloy.

That is, in the stretching process of the pipe by inclined rolling, the deformed area immediately below the inclined roll is surrounded by the non-deformed area not in contact with the roll, so that the compressive stress generated in the three directions on the mandrel is caused by the deformation resistance of the workpiece. Much higher than that. The Ni-based alloy tube is heated at a heating temperature of 1050 to 12
Heated to 00 ° C, even in this temperature range 5-10kg
It has a deformation resistance of f / mm ² . Due to the constraint of the non-deformation region, the surface pressure actually generated on the mandrel surface is about 2.0 times the deformation resistance, and a normal Fe-based mandrel causes plastic deformation.

By the method of dispersing the thermal / stress load by advancing the mandrel, the temperature of the mandrel can be suppressed to about 1000 ° C. immediately after the completion of molding, so that the yield strength at 1000 ° C. is 25 kgf.
If the mandrel is made of a Ni-based alloy or a Co-based alloy having an N / mm ² or more, N
The i-base alloy pipe can be stretched.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 is a schematic view for explaining the inclined rolling method of the present invention, showing a state during rolling, and FIG.
FIGS. 3A and 3B are schematic diagrams illustrating the inclined rolling method of FIG. 1, wherein FIG. 3A shows a state at the start of rolling and FIG. Hereinafter, the same components as those of the related art in FIG. 5 are denoted by the same reference numerals.

In this inclined rolling method, the mandrel to be inserted into the material pipe and its holding device are different from the conventional one, but the other inclined rolls, the pulling device for the rolling pipe, etc. may have the same configuration as the conventional one, and the inclined roll shown in FIG. The principle of rolling itself does not change. FIG. 1 shows a mandrel 11 used for inclined rolling according to the present invention, a feed holding device 10 thereof, and one inclined roll 21 out of three. The mandrel 11 is connected to one end of a mandrel shaft 12, and the other end of the mandrel shaft 12 is rotatably held by a shaft holding device 13.

The mandrel 11 is different from the conventional one in that the mandrel shaft is unwound during the rolling operation, and the mandrel shaft is moved from the shell-shaped tip to gradually move the portion of the inclined roll 21 to which the thermal / stress load is applied to the rearward portion. 12 has a long cylindrical portion 11a reaching the rear end. The length 1 of the cylindrical portion 11a is determined by the speed and time at which the mandrel 11 is fed forward during rolling, and is not particularly limited, but may be, for example, about 150 to 500 mm.

The material of the mandrel 11 is a normal F
Although e-base may be used, deformation resistance at high temperature such as Ni-base alloy is high.
When rolling a material tube of a different material,
And the proof stress at 1000 ° C is 25 kgf / mm^TwoLess than
Above, especially 25-35kgf / mm ^TwoNi-based alloy or C
It is preferable to use an o-based alloy. Specifics of Ni-based alloy
As a typical composition, for example, C: 0.1 to 0.
2%, Cr: 8.0 to 11.0%, Co: 8.0 to 1
7.0%, Ti:. 0-5.0%, Al: 4.0-6.
0%, Zr: 0.03 to 0.09%, B: 0.01 to
0.02%, in addition to this, Mo: 2.0 to 4.0%,
W: 8.0-14.0%, V: 0.5-1.5%, H
f: 1.0 to 3.0%, Nb or Ta: 1.0 to 2.0
% Or more, and the balance is Ni
And alloys consisting of unavoidable impurities.
You. The surface of the mandrel always has a relative speed with the inner surface of the pipe
It is in contact and needs hot wear resistance. Also,
The mandrel is machined to attach it to the shaft.
It must be a material that can be processed. Ni-based alloy or
By configuring the mandrel 11 with a Co alloy,
High temperature strength, abrasion resistance, oxidation resistance, machine required for drel
It can satisfy demands such as machine workability.

The shaft holding device 13 is capable of moving forward and backward along the pass line X, and is stopped by the stopper 14. The stopper 14 is advanced at a predetermined speed by the control motor 15 during rolling, and at the same time, a force is drawn into the mandrel 12 toward the outlet in the axial direction by the friction of the inner surface of the pipe. The shaft holding device 13 also advances with the advance.

The shaft holding device 13 waits at the position where the raw material tube H exits from the heating furnace and is set in the rolling device before it is set in the rolling device, and the forming roll is lowered by, for example, an elevating cylinder to start forming. At this point, the mandrel is rapidly advanced by an air cylinder (not shown) and inserted into the inside from the end of the material pipe H to the rolling position by the inclined roll 21. During rolling, the shaft holding device 13 is pressed against the stopper 14, and the holding device 13 is also moved forward by moving the stopper 14 at a predetermined speed by the control motor 15, whereby the mandrel 12 is moved toward the outlet in a predetermined direction. It is designed to move forward at the speed of

Then, as shown in FIG. 2A, the leading end of the blank tube H is gripped by a gripper 31 of a tensioning device (not shown) before the start of forming, and the blank tube H is gripped by the gripper 31 during the rolling operation. While pulling along the forward direction at a predetermined tension or a predetermined pulling speed. The gripper 31 is rotatably attached to an axial tension applying device, and rotates together with the rolling tube M during rolling.

The material tube H is installed, and the mandrel 11 is inserted into the material tube H at a position where the tip of the cylindrical portion of the mandrel 11 faces the inclined roll 21, and the tip of the material tube H is gripped by the gripper 31. While applying a pulling force, the inclined roll 21 is arranged at the forming position while being rotationally driven.
As shown in (a), rolling of the raw material tube H is started. The raw material tube H is stretched between the inclined roll 21 and the mandrel 11 while passing between the inclined roll 21 and the mandrel 11 while being advanced mainly by the pulling force of the pulling device. It is reduced and becomes a rolled tube M.

In the present invention, during this rolling operation, the mandrel 11 is gradually advanced by the mandrel feed holding device 10 in the traveling direction of the material pipe H. In order to obtain an appropriate value of the forward speed of the mandrel 11, a mandrel made of IN100 was used.
Outer diameter 34 mm, inner diameter 28
mm rolled tube, the mandrel advance speed is Vm,
When the exit speed of the rolling tube is Vl, Vl is 40 mm.
/ S, Vm was changed, the temperature of the mandrel at the end of rolling was measured, and the presence or absence of plastic deformation of the mandrel was visually observed.

The composition of the Ni-based alloy is Co: 2.5%
Hereinafter, Cr: 20.0 to 22.5%, Mo: 12.5 to
14.5%, W: 2.5 to 3.5%, Fe: 2.0 to
6.0%, Si: 0.08% or less, Mn: 0.50% or less, C: 0.015% or less, the balance being a Ni-based alloy composed of Ni and unavoidable impurities. Hastelloy C-22.

In FIG. 3, the horizontal axis represents the mandrel advancing rate (Vm /
Vl x 100%), and the vertical axis shows the temperature of the mandrel at the end of rolling. According to FIG. 3, when the mandrel advancing rate is 1% or more, the temperature at the end of rolling of the mandrel becomes 1000 ° C. or less, and it is recognized that plastic deformation of the mandrel does not occur. The upper limit of the forward speed of the mandrel is determined in consideration of the manufacturing technology and is not particularly limited, but is generally about 20%. The exit speed of the rolling tube is generally about 20 to 100 mm / sec.

By continuing such a rolling operation, FIG.
The rolling operation is completed when rolling is performed to a portion near the end of the material tube H as shown in FIG. At this time, the inclined roll 21
It is preferable that the position of the cylindrical portion 11a of the mandrel subjected to the stress due to the above is a portion close to the rear end of the cylindrical portion 11a, thereby effectively utilizing the cylindrical portion 11a of the mandrel. Can be effectively suppressed.

According to the inclined rolling method of the above aspect, since the material tube is stretched and rolled while the mandrel is advanced in the traveling direction of the material tube, the thermal / stress load applied to the mandrel from the inclined roll via the material tube is reduced. Disperse the thermal / stress load over almost all of the mandrel cylinder, because the receiving part moves from the leading end to the rear end of the cylindrical part of the mandrel during rolling and is not concentrated in one place. As a result, the temperature rise of the mandrel can be reduced, and plastic deformation can be effectively prevented.

Further, since the mandrel shaft to which the mandrel is connected is freely rotatably held, the mandrel rotates together with the material pipe, thereby reducing the relative speed of the inner surface of the pipe in the rotating direction, thereby suppressing frictional heat generation. Therefore, plastic deformation can be suppressed by suppressing the temperature rise of the mandrel.

Further, if the material of the mandrel is made of a Ni-based alloy or a Co-based alloy having a high deformation resistance at a high temperature, the mandrel can be moved forward and free during the stretching process,
Since the plastic deformation of the mandrel can be more effectively prevented, stretching of a Ni-based alloy tube or the like having a high deformation resistance at a high temperature can be performed without causing the plastic deformation of the mandrel.

Next, a description will be given, with reference to FIG. 4, of a tilt rolling apparatus for performing the above-described tilt rolling method. FIG. 4 is a schematic configuration diagram illustrating one embodiment of a device configuration of the inclined rolling device of the present invention. The inclined rolling device 1 includes a mandrel feed holding device 10, a forming roll unit 20, and a pulling device 30 from the left side in the drawing. A mandrel feed holding device 10 that holds the mandrel shaft 12 and is disposed so as to be able to advance and retreat in the pass line direction;
A stopper 14 for stopping the advance of the mandrel holding device 13 by an air cylinder (not shown) and a control motor 15 for moving the stopper 14 at a predetermined speed are provided. Mandrel inserted into material tube H (see Fig. 1)
Is connected and fixed to the tip of the mandrel shaft 12, and the mandrel shaft 12 is rotatably held by a mandrel holding device 13.

The mandrel holding device 13 stands by at a position where the material tube H is removed from the heating furnace and is placed on the material tube carry-in bed 16 at the retraction stop position. Is started, the mandrel 11 is rapidly advanced by the air cylinder so as to insert the mandrel 11 into the material pipe H. And
The mandrel holding device 13 holds the mandrel 11 during rolling.
The stopper 14 is pressed against the stopper 14 by the retraction force in the direction of the outlet generated by the mandrel holding device 1 by moving the stopper 14 forward at a predetermined speed by the control motor.
3 is advanced at a predetermined speed, and the mandrel 11 is advanced gradually. The mandrel 11 is preferably made of a Ni-based alloy or a Co-based alloy.

As shown in FIG. 5, the forming roll section 20 includes three forming rolls 21 around a pass line X.
a, 21b and 21c are provided rotatably at 120 ° intervals. As shown in FIGS. 5B and 5C, the drive shaft of each forming roll 21 is inclined at an intersection angle α and an inclination angle β with respect to the pass line X. The rolling tube M is rotationally driven by the rotation of the forming roll 21 and the inclination angle β, and at the same time, a propulsive force is given in the feeding direction.

The forming roll crossing angle α is fixed in a direction converging toward the material advancing direction, for example, 30 to 45 °, preferably about 45 °, and the inclination angle β is, for example, about 0 ° to about 2 °.
It is freely variable in the range of 5 °. Note that all three forming rolls 21 have the same intersection angle α and inclination angle β.

The forming roll 21 includes a roll driving motor 22
Is attached to the tip of the drive shaft by a taper shank. By fixing with a taper shank,
Each forming roll 21 can be easily attached and detached and can receive a large load. A not-shown tilt angle providing motor as a tilt angle adjusting means is connected to the casing of the roll drive motor, and by adjusting the drive of the tilt angle providing motor,
By rotating the forming roll 21 together with the roll drive motor 22 around the pressing cylinder 23, the inclination angle β given to the forming roll 21 is adjusted.

The forming roll 21 is, as shown in FIG.
The first truncated cone portion has a conical half angle equal to the intersection angle α, and the second truncated cone portion provided continuously with the first truncated cone portion has a conical half angle. It is formed smaller than α. When the material pipe H is inclinedly rolled, first, the material pipe H is rolled by a rolling surface S1 which is relatively inclined with respect to the pass line X, and then is rolled by a rolling surface S2 which is inclined relatively small with respect to the pass line 19. .

The pulling device 30 is provided so as to be able to move forward and backward with respect to the forming roll section 20 on the pass line X.
Gripper 3 that grips the tip of the material and rotates with the material tube H
1, a tension rod 32 holding the gripper 31,
And a tensile force source (not shown). During the rolling operation, the material tube 10 is pulled at a predetermined tension or a predetermined pulling speed along the feed direction while being gripped by the gripper 23.

When the material tube H is rolled by such an apparatus configuration, the material tube H taken out of the heating furnace is placed on the material tube carry-in bed 16 and the mandrel holding device 13 at the retracted position is advanced. Then, the mandrel 11 is inserted from the rear end of the material tube H, and the front end of the material tube H is gripped by the gripper 31. Then, in a state where the raw material tube H is pulled along the pass line X at a predetermined pulling speed by the pulling device 30, inclined rolling is started at a portion in contact with the rotating forming roll 21. When the material pipe H is inclinedly rolled, first, the material pipe H is rolled at a relatively large reduction ratio by the rolling surface S1 which is relatively inclined with respect to the pass line H, and then is inclined relatively small with respect to the pass line X. Rolling is performed at a relatively small area reduction rate by the rolling surface S2. During this rolling, the mandrel holding device 13 advances at a predetermined speed together with the stopper 14 advanced by the control motor 15, and sends the mandrel 11 forward.

The inclined rolling device can prevent the plastic deformation of the mandrel and produce a seamless tube made of a material having a high deformation resistance at a high temperature, such as a Ni-based alloy.

[0042]

According to the inclined rolling method of the present invention, a seamless pipe can be manufactured while preventing plastic deformation of the mandrel. Further, the inclined rolling device of the present invention can carry out such an inclined rolling method.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an outline of a tilt rolling method of the present invention.

FIGS. 2A and 2B are schematic diagrams illustrating the outline of the inclined rolling method of the present invention, in which FIG. 2A shows a state at the start of forming and FIG. 2B shows a state at the end of forming.

FIG. 3 is a graph plotting the mandrel advancing rate versus the temperature at the end of rolling of the mandrel.

FIG. 4 is a schematic configuration diagram showing an outline of a tilt rolling device of the present invention.

FIG. 5A is a view of the state during rolling by the inclined rolling device as viewed from the front side of the outlet side of the pipe, and FIG. 5B is a view taken along line BB of FIG.
FIG. 7C is a cross-sectional view along the line, and FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Incline rolling device, 10 ... Mandrel feed holding device, 1
DESCRIPTION OF SYMBOLS 1 ... Mandrel, 12 ... Mandrel shaft, 13 ... Mandrel holding device, 14 ... Stopper, 15 ... Control motor, 20 ... Forming roll part, 21 ... Inclined roll, 30 ... Tensioning device, 31 ... Gripper, H ... Material pipe, M ... rolled tubes,
X: Pass line

Claims (7)

[Claims] 1. A method according to claim 1, wherein the material pipe is pulled while applying a tensile force to the material pipe from the front in the traveling direction of the material pipe, and a plurality of inclined rolls arranged around a pass line and a mandrel inserted into the material pipe. A method for producing a rolled tube by elongating and rolling the material tube, wherein the mandrel is elongated in the traveling direction of the material tube while elongating the material tube. 2. The tilt rolling method according to claim 1, wherein said mandrel has a long cylindrical portion to be unwound during elongation rolling. 3. The method of claim 1, wherein the mandrel shaft holding the mandrel is rotatably held. 4. When the mandrel advance speed is Vm and the exit speed of the rolling tube is Vl, the mandrel advance rate (Vm
/ Vl × 100) is 1% or more. 5. The inclined rolling method according to claim 1, wherein the mandrel is made of a Ni-based alloy or a Co-based alloy having a proof stress at 1000 ° C. of 25 kgf / mm ² or more. 6. A pulling means for pulling the raw material tube while applying a tensile force to the raw material tube from the front in the traveling direction of the raw material tube, a plurality of inclined rolls arranged around a pass line, and inserted into the raw material tube. And a mandrel holding device for gradually feeding the mandrel in the traveling direction of the material tube during rolling, and stretching and rolling the material tube between the inclined roll and the mandrel that is gradually advanced. And a rolling tube. 7. The inclined rolling device according to claim 6, wherein a mandrel shaft connected to the mandrel is rotatably held by the mandrel holding device.