JPH05285507A - Method for rolling tube with inclined roll - Google Patents

Abstract

PURPOSE:To prevent the generation of abnormality in shape by setting the driving speed of mandrel bar higher than the speed of a tube in the axial direction of tube on the outlet side of a device for rolling a material in rolling with inclined rolls. CONSTITUTION:At the same time of starting the advance of the tube in the axial direction of tube, the mandrel bar 7 is advanced in the same direction as the advancing direction of the tube at a prescribed set speed. At this time, the advancing speed of the mandrel bar 7 is set so as to be higher than the advancing speed of the tube 9 on the outlet side of the rolling device 11. Thus, the tube 9 in rolling is forcedly drawn by a frictional force between its inside surface and the outside surface of the mandrel bar 7 to the outlet side of the rolling device with the mandrel bar 7 of which the advancing speed is relatively faster than that of the tube. In such a way, by utilizing a matter that the drawing of the tube 9 in the axial direction of tube is accelerated than that in the peripheral direction in a pass, the generation of projecting parts which are generated on the places where excessive materials are supplied between the rolling rolls 1 in rolling is restrained and the generation of material abnormal in shape can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a pipe, and more particularly to a rolling method for drawing a material by a mandrel bar when rolling the pipe in an inclined roll.

[0002]

2. Description of the Related Art A conventional pipe rolling machine has a structure in which the pressure is narrowed by a plurality of barrel-shaped rolls or a plurality of rolls having semi-circular grooves cut. It was supported by the roll housing via the bearing and roll chock. For this reason, a bending moment acts on the roll to prevent breakage of the roll,
It was necessary to increase the roll diameter in order to increase the rigidity. However, when the roll diameter is increased, the contact area between the roll and the material to be rolled is increased, and the rolling reaction force is increased. Therefore, recent rolling mills have become extremely large. Also, in conventional rolling mills, the rolls drive the ends of the roll shafts, so the structure is extremely complicated especially for inclined roll rolling mills where the roll shaft is inclined, and sufficient strength is required. It is getting huge.

In order to solve such a problem, for the purpose of providing a rolling apparatus for pipes or rods which is small in size, has high mill rigidity, and has a high processing speed, Japanese Patent Publication No. 3-4064.
In Japanese Patent No. 3 publication, the rotating shaft is twisted in the same direction and inclinedly arranged.
As a structure for supporting more than one rolling roll, rolling reaction force via the roll neck portion, as a structure, a rotary housing for supporting the rolling roll body on its cylindrical inner surface, and a fixing for supporting the rotary housing. An inclined roll rolling mill including a housing and a drive device that drives the rotary housing has been proposed.

However, in this inclined roll rolling machine, when the pipe is rolled, the cross-sectional shape of the rolled pipe in the direction perpendicular to the pipe axis direction is not circular but triangular or pentagonal, Since a product having an abnormal shape is generated, there are cases where a rolled product having a predetermined circular cross-sectional shape cannot be obtained. In an inclined roll rolling mill, the material to be rolled is stretched in the pipe axial direction during rolling and also in the pipe circumferential direction. By this stretching in the pipe circumferential direction, as shown in FIG. 3, an excessive material is supplied between the rolling rolls 1 during rolling, so that a convex portion is generated,
Abnormal deformation occurs in the rolled product. Japanese Patent Fair 3-40643
In the gazette, such abnormal deformation is not taken into consideration and there is no improvement measure.

[0005]

In order to solve the above problems, the present invention sets the driving speed of the mandrel bar during rolling higher than the speed of the material in the pipe axis direction on the outlet side of the rolling apparatus to force the material. It is intended to solve the problem by suppressing the stretching of the material in the circumferential direction of the pipe by pulling it out to the outside.

[0006]

The gist of the present invention is to provide a method for rolling a pipe by means of three or more inclined rolling rolls supported in a rotating housing and a mandrel bar driven in the axial direction of the pipe. A method for inclining rolls of a pipe, characterized in that an abnormal shape of a rolled product is prevented by setting the driving speed of the material higher than the speed in the axial direction of the pipe on the exit side of the rolling device and forcibly drawing out the material. It is in.

The present invention will be described in detail below with reference to the drawings. The present invention is intended for the rolling of a pipe by an inclined roll rolling machine, and by setting the driving speed of the mandrel bar higher than the pipe axial direction exit side speed of the material on the rolling machine exit side, an abnormal shape of the rolled tube is obtained. Base on preventing.

FIG. 1 is a side view of a rolling mill when the present invention is applied to tube rolling using an inclined roll having four rolls, and FIG. 2 is a sectional view taken along line AA of FIG. The inclined roll rolling device 11 used in the tube rolling method of the present invention includes three or more (four in the figure) rolling rolls 1 in which the rotating shafts are twisted in the same direction and inclined, and a body portion of the rolling rolls 1. A rotary housing 2 supported by the inner surface of the cylinder, a fixed housing 3 supporting the rotary housing 2, a drive device 4 for driving the rotary housing 2, a mandrel bar 7 inserted in the center of a material to be rolled, The mandrel bar driving device 8 drives the mandrel bar 7 in the tube axis direction.

When the tube to be charged is brought into contact with the rolling roll 1, the rolling force is applied by the rolling roll to the rotational force and the advancing force in the axial direction of the tube. By the time the tube contacts the material, the tube is advanced by feed rolls 10 or other means for transport and guided into a path in rolling mill 11. This pass is shown as an example in the case of four rolling rolls 1 in FIG. 1 and FIG. 2, but is generally 3
It is composed of one or more rolling rolls, becomes narrower toward the exit side, and a predetermined reduction can be applied to the pipe.

In the case of rolling, the mandrel bar driving device 8 advances the mandrel bar 7 in the same direction as the advancing direction of the pipe at the same time when the pipe starts to advance in the axial direction of the pipe. At this time, the advancing speed of the mandrel bar 7 is set to be higher than the advancing speed of the pipe 9 on the exit side of the rolling device 11. In this way, by setting the advancing speed of the mandrel bar 7 to be higher than the advancing speed of the pipe 9 in the axial direction of the rolling device 11 on the exit side, the pipe 9 being rolled is guided by the inner surface of the mandrel bar 7 and the mandrel bar 7. Due to the frictional force with the outer surface of the mandrel bar, the mandrel bar, which has a relatively higher advancing speed than the tube, is forcibly pulled out to the exit side of the rolling device 11.

By forcibly pulling out by the mandrel bar 7 in this way, the pipe 9 is accelerated during the rolling by utilizing the fact that the pipe 9 is stretched in the axial direction of the pipe rather than in the circumferential direction. The generation of convex portions as shown in FIG. 3 caused by the supply of an excessive material between the rolling rolls 1 is suppressed, and the abnormal shape material is prevented from being generated. This set speed varies depending on the size, wall thickness, etc. of the rolled material, and the set speed is changed as appropriate, but it is desirable to be 120% or more of the material advancing speed of the rolling device 11.

[0012]

In the inclined roll rolling method constructed as described above, after setting the drive unit 8 so that the advancing speed of the mandrel bar is higher than the speed of the tube 9, the mandrel bar 7 is advanced while the tube is moved. Rolling is started by advancing the tube 9 and the mandrel bar 7 into a path in the rolling device 11 by advancing the feed roll 10 or other means. The mandrel bar 7 continues to move forward at a predetermined set speed until the rear end of the pipe 9 is completely discharged from the exit side of the rolling device 11, and the pipe 9 is always forced out of the rolling device 11 during rolling. Then, a predetermined rolled product is obtained.

[0013]

EXAMPLE A stainless steel pipe having an outer diameter of 88 mm, a wall thickness of 22 mm and a length of 350 mm was heated to 1280 ° C., and then a mandrel bar 7 having an outer diameter of 43 mm was inserted and rolled.
At this time, a graphite-based hot rolling lubricant was applied to the outer surface of the mandrel bar 7 in advance. Further, at this time, the rolling roll 1 was tilted at an angle of 4 degrees, the minimum path size was 69 mm, and the rotary housing was driven at 60 rpm so as to rotate counterclockwise as viewed from the entrance side.

As a result, the rolled tube was an abnormal shape material having a triangular sectional shape in the direction perpendicular to the tube axis. At this time, the advancing speed of the tube in the tube axial direction was 40 mm / sec, while the set speed for driving the mandrel bar was 40% / sec which was 100% thereof.

Therefore, the inclined roll rolling method of pulling out the material by the mandrel bar according to the present invention is applied, and the set speed for driving the mandrel bar is 120% of the set speed for advancing the tube axial direction of 40 mm / sec. The rolling condition was changed to a certain 48 mm / sec, and the other rolling conditions were the same as those described above. As a result, a rolled product with a predetermined shape with a circular cross section in the direction perpendicular to the pipe axis was obtained. Was given.

[0016]

EFFECTS OF THE INVENTION According to the present invention, three or more rolling rolls in which the rotating shafts are twisted in the same direction and arranged in an inclined manner, a rotating housing for supporting the rolling roll body on its cylindrical inner surface, and the rotating housing are supported. In a pipe rolling apparatus including a fixed housing for driving the rotary housing, a drive device for driving the rotary housing, a mandrel bar, and a mandrel bar drive device for driving the mandrel bar, rolling is performed without generating a rolled product having an abnormal shape. It became possible to do.

[Brief description of drawings]

FIG. 1 is a side view of an inclined roll rolling machine having four rolling rolls to which the present invention is applied.

FIG. 2 is an example of a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory view of a shape of a convex portion generated between rolls during rolling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolling roll 2 Rotating housing 3 Fixed housing 4 Rotating housing drive device 5 Input side stand 6 Output side stand 7 Mandrel bar 8 Mandrel bar drive device 9 Tube 10 Feed roll 11 Rolling device

Claims (1)

[Claims] 1. A method of rolling a pipe by three or more inclined rolling rolls supported in a rotating housing and a mandrel bar driven in the axial direction of the pipe, wherein the mandrel bar is driven at a rolling speed of a material. A tilted roll rolling method for a pipe, characterized in that by setting the speed higher than the speed in the axial direction of the pipe on the exit side of the device, the material is forcibly pulled out to prevent the occurrence of abnormally shaped material.