JPS5829164B2 - Pipe rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling large diameter seamless metal tubes.

Conventional rolling methods for large-diameter seamless metal pipes (for example, seamless steel pipes) include the pilger mill rolling method and the rotary expander method.

Here, large diameter refers to an outer diameter of 16 inches or more, as is generally used in the steel pipe industry.

In the Pilger mill method, a mandrel is passed through a thick hollow tube, and a special caliber cut double roll rolling mill is used to forge the thickness of the tube between the material and the mandrel while pushing the material back toward the input side with the rolls. This is a rolling method.

In this method, the outside diameter of the tube is considerably reduced by rolling, so the outside diameter of the raw tube is required to be considerably larger than the outside diameter of the finished product.

Therefore, when modifying existing medium-diameter pipe manufacturing equipment to be able to manufacture large-diameter pipes, it is necessary to It is necessary to increase the size across the board, and of course it is also necessary to increase the size beyond Pilger Mill.

At the current technological level, the production output by the pilger mill method is limited to small-scale factories with a monthly production of 10,000 tons or less due to the capacity of the pilger mill, and due to this level of production, production by the pilger mill method is limited to small-scale factories with monthly production of 10,000 tons or less. It is undesirable to install a new cabinet or make a major remodeling of the entire line because it will increase costs.

Furthermore, even if we try to supply cheap and high-quality pipe materials by continuous casting, in the case of steel, there is a limit due to the quality of slabs at the current technological level. It is not possible to obtain.

On the other hand, in the rotary expander method, a medium-walled or thin-walled hollow blank tube is moved between two driven mushroom-shaped rolls and a non-driven conical plug placed between the two. This method involves rolling the wall into a spiral shape to make it thinner and increasing the outer diameter by up to 1.5 times.

With this method, it is possible to roll pipes with an outer diameter of 16// to 24//, for example, so if you have medium diameter pipe manufacturing equipment, you only need to modify or add equipment after the rotary expander. The investment amount is relatively small.

In addition, this method allows mass production compared to the Pilger Mill method, but the roll diameter is larger than 1.5 m, and the roll support must be cantilevered due to the structure of the rolling mill. Therefore, the mill rigidity is low, and if you want to prevent this, you have no choice but to make a huge rolling mill.

On the other hand, this kind of equipment can produce about 30,000 tons per month.

However, if we try to further expand the production scale by using this rotary expander method, the drive source and equipment structure will have to become huge due to the increase in size and speed, or we will have to solve the problem. The flaw is that it has many unresolved problems.

Furthermore, the structure of the rotary expander has a special relationship in that the roll 1 drive shaft is positioned at an angle of approximately 60 degrees to the pass center line, and since it is driven from the exit side of the rolling mill, it occupies equipment. Not only does the area become extremely large, but the temperature drop due to the long transportation distance of the rolled tube to the next process becomes significant, making processing in the next process difficult.

Furthermore, in rotary expanders, the deformation of the tube is not only a simple geometric shape change, but also significant additional shear deformation inside the material, which leads to increased energy consumption, insufficient mill rigidity, and eaves. , and the dimensional accuracy of the pipe deteriorates.

The disadvantages of this conventional method are largely due to the large rolling rolls and the structure of the rolling mill that supports them, as well as the fact that the energy necessary to deform the tube is supplied only by the rolling rolls that circumscribe the tube.

The present invention has investigated these drawbacks of the conventional method in detail and has provided a completely new tube rolling method, which has the following advantages over the conventional method.

(2) Since the pipe is expanded in this process using a material for medium diameter, the process before the punching machine can be performed using equipment 11 for medium diameter.

■Rolling capacity exceeds that of conventional methods.

Encased equipment can be made compact.

■Compared to a rotary expander, the additional shear deformation created inside the material is smaller, reducing the occurrence of eaves and requiring less energy for deformation.

To explain the invention in detail, in FIG. 1, a tube 1 is pushed into a rolling mill by means of a pushing device @2 and is kept pressed during rolling.

As shown in FIGS. 1 and 2, the path of the rolling mill is composed of rolling rollers 3-1, 3-2, guide rollers 4-1, 4-2, and a mandrel 5 placed at the center of the path.

The tip 5' of the mandrel is made smaller than the inside diameter of the tube on the entry side and is accommodated inside the tube as the tube advances.

A mandrel 5 and a rolling roller 3 whose tube walls are rotationally driven
-t, when pushed through the grooves squeezed between 3-2, the tube rotates and is rolled between rolling rollers 3-1, 3-2 and mandrel 5, the wall thickness decreases and the outer diameter increases.

Guide roller 4-1.4-21C keeps the tube within the path and regulates the outer diameter.

The tube 1 and the rolling roller 11 are rotated by the mandrel 5.
, 3-2, button and guide roller 4i, 4-1, 4
-2 is driven to rotate, and during the driven rotation, the rolling roller button and guide roller are tilted in the direction in which frictional force is applied so as to push the tube toward the exit side.

In other words, if the rotation direction of the mandrel is counterclockwise when viewed from the exit side (right side in the figure) as shown in Figure 1, the rotation axes of the rolling roller button and guide roller are tilted to the left, and the mandrel If the direction of rotation is reverse rotation, the rotation axes of the rolling roller and guide roller are also inclined in the opposite direction.

If these inclinations are referred to as roller inclination angles θ, θ is an angle that is parallel to the path center line 6 and intersects with the half interval that includes this.

This angle θ is an element involved in the rotation and advancement of the material to be rolled, but in practice, a value within the range of 4 to 16 degrees can be adopted.

The outer diameter can be easily increased by increasing the distance between the rolling roller and the guide roller and the path center line 6 toward the exit side.

The tube can be deformed more easily if the diameter of the action portion of the twisted roller is increased to correspond to the increase in the outer diameter of the tube.

Therefore, as shown in FIG. 1, it is preferable to arrange the roller center axis so that it is separated from the path center line by ψ, but ψ has no direct relation to the advancement effect of the tube.

Here, the angle ψ is at the position where the tube and roller contact,
The ratio of the true rotation speed of the tube and roller is determined to be constant in the tube axis direction, and takes a value of 00 to 30 degrees.

By tilting the rollers by the angle ψ in this manner, twisting of the tube can be prevented.

The main function of the kite rollers 4-1, 4-2 is to prevent material from flying out from the rolling passes.

That is, rolling rollers 3-1, 3-2 and mandrel 5
As a result, the raw tube is rolled while being rotated and advanced in a spiral manner in the state shown in FIG.

However, the mandrel 5 has a cantilever structure supported at its base end and is easily bent in the vertical direction.

Therefore, if the guide rollers 4-1, 4-2 were not present, the material would break away from being held by the rolling rollers 31.3-2 and fly out of the rolling path.

Among the guide rollers 4-1 and 4-2, the inner surface of the raw tube is separated from the outer circumferential surface of the mandrel at this point, and does not take part in reducing the wall thickness of the tube.

The twisted guide roller can also be replaced with a guide shoe.

As shown in Fig. 3, the diameter of the mandrel 5 increases toward the exit side, and the distance between the mandrel and the rolling roller gradually narrows, and as the tube advances in a spiral, the mandrel and the rolling roller rotate every half turn. Decrease the wall thickness in between and enlarge the outer diameter.

By gradually narrowing the gap between the rolling roller and the mandrel in this way, even if the mandrel diameter expands toward the exit side, the rolled material will move forward in a spiral shape and when it reaches that position, it will not be rolled into a button. A gap is created between the inner diameter of the tube just before rolling and the outer peripheral surface of the mandrel, resulting in more stable rolling.

The advancement of the tube is caused by the pushing force of the pushing device 2 and the rotating drive of the mandrel 5 between the tube 1 and rolling rollers 3-1, 3-2.
This is caused by the frictional force generated between the button and the guide rollers 4-1 and 4-2 due to the rotation of the rollers and the tube, but even if sufficient pushing force cannot be applied by the pushing device 2 near the rear end of the tube. , there exists a condition in which the tube can be advanced only by the frictional force and the rolling can be completed at the final end 1.

By the method described above, the outer diameter of the tube is adjusted to 1.2 to 1.8.
It can be expanded twice as much, making it possible to roll large-diameter pipes even though the manufacturing equipment used before the punching machine was for manufacturing medium-diameter pipes.

For example, the pipe making process includes a heating furnace, a drilling machine, a plug mill, a pipe expanding machine of the present invention, a diameter-sizing machine, a traditional heating furnace, an inclined roll drilling machine, a pipe expanding machine of the present invention, a polishing machine, a diameter-sizing machine, etc. It is.

In an embodiment of the present invention, two rolling driven rollers and two guide driven rollers as shown in FIG. 1, FIG. A good tube with an outer diameter of 180 my++ and a wall thickness of 107 FB was obtained using a roller, a mandrel driven one rotation, and a pushing device.

At this time, the outer diameter of the tube became 1.8 times larger, and the length became 1.1 times larger.

By changing the adjustment of the rolling mill, it is also possible to obtain a good tube with an outer diameter of 150 m+++ and a wall thickness of 10 rML from a raw tube of the same dimensions.In this case, the outer diameter of the tube is 1.5 times larger and the length is It was 1.3 times.

Using a conventional rotary expander, the outer diameter of the tube can be expanded to about 1.5 times.

For example, an outer diameter of 100 rru molded from plasticine.
n, only tubes with an outer diameter of 150TrrrrL1 and a wall thickness of 10 can be obtained from a raw tube with a wall thickness of 25M.

If the tube is expanded further than this, the shear deformation of the material will increase, which will easily cause eaves to form on the tube, impair the smoothness of the surface, and even cause work problems such as poor button engagement and poor bottom slippage. become.

At this time, the rotary expander has rotating shafts 11-1 of rolling rolls 10-1 and 10-2, as shown in FIG.
, 11-2 cross each other at 600 with respect to the path center line 12, and the shape of the roll is mushroom-shaped as shown.

The tube 1 is rolled between the rolls and the plug 14 while advancing in a helical manner, reducing the wall thickness and increasing the outer diameter.

Plug 14 is held in place by mandrel 12 and rotates as the tube rotates.

The rolling roll 10-1°1O-2f1 rotation is driven, and as shown in FIG. 6, its two rotating shafts are one high and the other low with respect to the lotus center line 12.
By doing this, the tube is rotated forward in a spiral manner.

Therefore, within the portion 13 in contact with the tube, the roll surface speed varies greatly in both direction and magnitude depending on the location, complex forces associated with rolling act on the tube, and the deformation and flow of the material become complicated. is twisted, and the inner and outer surface layers undergo relatively large displacements in the circumferential and longitudinal directions.

Since the roll diameter of such rolling equipment is large and the equipment structure is large and complicated, it is not easy to adjust to the optimum conditions for each finished rolling dimension of the pipe, and it is difficult to provide an adjustment section.

Therefore, the method of the present invention is superior to the rotary expander method in the following points.

■Since the additional shear deformation that occurs inside the material is small, the occurrence of eaves is reduced, and the energy required for deformation is also small.

■Rolling equipment can be designed compactly.

■There is less work trouble and the rolling capacity can be increased.

To explain the present invention in more detail, with respect to Particularly, the invention is characterized by the ability to select the shape of the mandrel rolling part that corresponds to the change in diameter of the tube and the wall thickness reduction, and b the ability to select the shape of the rolling roller button and guide roller from a wide range of shapes that are advantageous for deforming the tube. By using a roller bearing in the C roller support part, friction loss of the driven roller bearing part can be reduced;
(d) The pipe diameter can be easily expanded by the pushing force, (e) The hydrostatic pressure component inside the material increases due to the pushing force, and the ratio of tensile stress and shear stress is relatively reduced, preventing the occurrence of eaves, etc. This is the reason why it is superior to the conventional method.

Regarding (2), in the conventional method, as shown in Figures 5 and 6, the rolls are supported on a cantilever, and each roll is tilted at an angle of about 60 degrees with respect to the roll rotation axis Babass line, which is roughly aligned with the path center line. On the other hand, it has a complicated structure with different heights, and the roll diameter is inevitably large.

In particular, driving the two rolling rolls arranged in this way with a large amount of power, and the fact that there is a lot of waste in deforming the squares and tubes, are the causes of the increased size of the apparatus.

On the other hand, the method of the present invention has a pushing device on the entry side, but the pushing stress generated by the device is 0.01 to 1.0 times the yield stress of the rolled material, preferably ff0. 1~0.
Since it is five times as large, it is smaller than the conventional rolling roll drive device.

For example, heated to 1250℃, outer diameter 400rmn, wall thickness 1
00mm low carbon steel with an outer diameter of 600rrrm and a wall thickness of 20m.
m, and the exit material speed at that time was 300rrvry.
's e c, the yield stress of the material is 2 Kq/r
ran2, and the pushing stress is IKri/rrrJn2, the power required for pushing is as small as about 107 KW.

Regarding (2), whereas the conventional method applies forward force to the material only by rolls, in the method of the present invention, the tube is rotated by the rotational force of the mandrel, and the friction force between the surface of the rotating tube and the roller and the pushing force are used. By advancing the tube.

In other words, in the conventional method, when the tube is rolled between the rolls and the plug as described above, the wall thickness of the tube decreases and the outer diameter expands, but especially when the front end is rolled, the outer diameter expands sufficiently. Instead, if a portion occurs where the inner diameter of the tube is not sufficiently large compared to the diameter of the plug, the forward movement of the tube will stop and a □ throttle will occur.

If the tube does not move forward by a certain amount as it rotates, the wall thickness will be insufficient and the outer diameter will not expand sufficiently, and the rotation will stop at the same time that the material cannot move forward, and if the material moves forward. The outer diameter will vary greatly in the length direction.

In the method of the present invention, the tube diameter is easily expanded by the pushing force and the tube is easily advanced.

If the outer diameter is not sufficiently expanded and the inner diameter of the tube is not large enough relative to the diameter of the plug, the contact area between the tube and plug will increase, the frictional force will increase, the tube will rotate easily, and it will not be pushed in. Along with the material feeding by the force, the forward force due to the roller friction force also increases, the volume of the material flowing into the path increases, and the outer diameter easily expands as it is rolled between the roller and the plug.

Furthermore, in the conventional method, there is a lot of waste in deformation, a lot of energy is spent on additional shear deformation, and the rolling speed becomes low.

The present invention has the combined effect of various advantages as described above.
Making the rolling equipment more compact, reducing the power source, and
This made it possible to increase rolling capacity.

As shown in Fig. 1, the method of the present invention consists of a rolling pass made up of a plurality of rolling rollers whose rotating axes are inclined in a specific direction with respect to the pass center line, and a plurality of guide rollers, and a rolling pass is formed near the center of the pass. A mandrel that can be rotated and driven from the exit side is arranged, and a device for pushing the tube into the rolling mill is arranged on the input side, and the tube is rolled by the pushing force of the pushing device and the rotational driving force of the mandrel. This is a tube rolling method in which the tube is rolled in a straight forward motion.

The appropriate number of rolling rollers and guide rollers is 2 as shown in Figure 2 or 3, or 3 as shown in Figure 4, since the structure is simple and the pipe diameter can be expanded easily. However, it is also possible to have four or more each.

The rolling roller rolls the wall thickness of the pipe between it and the mandrel, and its rotation axis is at f relative to the path center line.
By being slanted, it is arranged so that frictional force is generated in the forward direction as it rotates.

The guide roller is arranged so that the distance between the guide roller and the mandrel is larger than the distance between the rolling roller and the mandrel to prevent the tube from jumping out, generate frictional force in the forward direction as it rotates, and cause the tube to move forward. It functions to determine the outer diameter.

This kite roller can be replaced with a plate-shaped flyout prevention guide.

In this case, the frictional force loses its effect of moving the tube forward, but the work is still possible.

By driving the rolling roller 1 as an auxiliary drive, the work when rolling the rear end of the tube, where sufficient pushing force cannot be applied, becomes easier, the rolling speed is increased, and additional shear deformation is further reduced. You can also.

The power for driving the rolling rollers should be smaller than the power for driving the mandrel for one revolution, and should be kept to a minimum in order to avoid increasing the size and complexity of the equipment.

The buttons and guide rollers are not auxiliary rotationally driven like rolling rollers.

Examples of the method of the present invention are as follows.

Number of rolling rollers: 2 Number of guide rollers: 2 Rolling roller inclination angle 6° Guide roller inclination angle 6° Mandrel diameter (maximum part) 150 mm Mandrel rotation speed 30 rPm Shortest distance between rolling roller and mandrel 10rrarL Shortest distance between guide roller and mandrel 20 mm indentation stress
24^l pipe material
Dimensions of plasticine raw tube (mm) Outer diameter 100 x wall thickness 25 x length J500 Dimensions of finished tube (W) outer diameter 180 x wall thickness 10 x length 550 Plasticine is a metal that can be plastically deformed. It is often used in simulation experiments and can sufficiently simulate the deformation of steel during hot rolling.

Next, an example of a rolling mill train to which the tube rolling method of the present invention is applied is as follows: (a) Heating furnace → press roll perforator → elongator → plug □ roll → tube expander of the present invention → diameter-sizing machine (roller) ) Heating furnace → Press roll perforator → Elongator → Plug → Pipe expander of the present invention → Polishing machine → Diameter sizing machine (c) Heating furnace → Inclined roll perforator → Pipe expander of the present invention → Diameter sizing machine) Heating furnace → Inclined roll perforator → Elongator → Pipe expanding machine of the present invention → Sizing machine Among the rows, rolling mill rows (a) and (10) are most preferred.

Further, in the above-mentioned rolling mill row, the tube rolling method of the present invention is all utilized as a tube expanding machine, but it is also possible to perforate the edge material according to the present invention.

Furthermore, the tube rolling method of the present invention is not limited to hot rolling, but can also be applied to cold rolling.

The present invention is applicable not only to the rolling of large-diameter seamless steel pipes, but also to the expansion rolling of tubular objects that can be plastically worked.

The outer diameter of the tube that can be rolled depends on the torsional strength of the mandrel, and for hot rolling steel, an outer diameter of 16" or more is at the industrial level, and for materials with lower deformation resistance, an even smaller diameter is required. The finished products can also be industrialized.

[Brief explanation of drawings]

1 to 3 are detailed explanatory diagrams of the present invention, and FIG. 1 is a
2 is a cross-sectional view of the main part of the tube rolling apparatus, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a sectional view taken along line BB of FIG. 2. FIG. 4 is a sectional view showing another example of the tube rolling apparatus. FIG. 5 explains the rotary expander method, which is a conventional tube rolling method, and is a plan view of the rotary expander. FIG. 6 is a side view illustrating the function of the rolling rolls in the rotary expander method. 1... Pipe, 2... Pushing device, 3-1 to 3-3...
Rolling roller, 4-1 to 4-3...guide roller 5
...Mandrel.

Claims (1)

[Scope of Claims] 1. At least a plurality of pipes whose rotational axial force is inclined in a predetermined direction with respect to the path center line of the pipe, and which are arranged so as to surround the path center line in a plane perpendicular to the path center line. A rolling path is formed by rolling rollers, and a mandrel driven by rotation 1 is placed at or near the center of the rolling path in a plane perpendicular to the rolling direction, and the rotation of the mandrel rotates the tube in a spiral shape. A tube rolling method characterized by rolling from a forward straight line. 2. A rolling pass is constituted by at least a plurality of rolling rollers whose rotational axes are inclined in a predetermined direction with respect to the pass center line of the pipe and are arranged so as to surround the pass line in a plane perpendicular to the pass center line. At the same time, a rotating mandrel is arranged at or near the center of the rolling pass in a plane perpendicular to the rolling direction (the axial direction of the material), and the tube is further pushed into the rolling mill on the entry side of the rolling rolls. A tube rolling method characterized in that a tube pushing device is arranged, and the tube is rolled while being rotated and moved forward in a spiral shape by the rotational driving force of the mandrel and the pushing force of the tube pushing device. 3 At least a plurality of rolling rollers and a plurality of rolling rollers arranged so that their rotational axes are inclined in a predetermined direction with respect to the path center line of the pipe and surround the path center line in a plane perpendicular to the path center line. A rolling pass is configured with a fly-out prevention guide, and a mandrel that is driven one rotation is placed at or near the center of the rolling pass in a plane perpendicular to the rolling direction, and the tube is placed on the rolling roll entry side of the rolling machine. A tube rolling method characterized in that a tube pushing device is disposed to push the tube into the tube, and the tube is rolled in a spiral shape while rotating forward g-v by the driving force of the mandrel per rotation and the pushing force of the tube pushing device. .