JPH04251604A - Skew rolling method of tube - Google Patents

Abstract

PURPOSE:To beforehand prevent the generation of abnormality of peeling, buckling, etc., by restraining bottom flare in the terminal part of tube at the time of skew rolling using a piercer, elongater, etc. CONSTITUTION:The terminal of tubing 4 is detected with a terminal detector 7 which is arranged in front of inclined rolls 1, 1. Based on the detected result with the terminal detector 7, operation command is sent to a machine 5 for adjusting opening degree of roll and machine 6 for adjusting guide position from a control part 9 and the opening degree of roll between the inclined rolls 1, 1 and the position of disk rolls 2, 2 are respectively changed by prescribed amounts by operating them. That is, the range of a prescribed length from the terminal part of the tubing 4 is rolled under the opening degree of roll larger than another part and in a state that intervals, which are increased accompanying to that, between the peripheral surfaces of the inclined rolls 1, 1 and the side faces of the disk rolls 2, 2 are kept in a prescribed dimension. In this way, bottom flare is restrained.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a piercing rolling mill (piercer), a stretching mill (
This invention relates to a method of rolling a pipe material between a pair of inclined rolls and an inner surface regulating device, such as Elongator. [0002] The Mannesmann pipe manufacturing method, which is widely adopted as a method for manufacturing seamless pipes, uses round bar-shaped steel pieces (billets) heated to a predetermined temperature in a heating furnace as a raw material. First, this billet is sent to a piercing rolling mill (Piercer) to be pierced and rolled to obtain a hollow shell tube, and if necessary, this hollow shell tube is fed to an elongation rolling mill (Elongator) for diameter expansion. , the rolled tube is thinned to obtain a rolled tube, and this rolled tube or the hollow tube is sent to various subsequent rolling mills, and after being stretched and rolled to have a desired diameter and wall thickness, it is rolled by a reeler and a sizer. This is a method to obtain product pipes through a refining process that involves polishing, shape correction, and sizing. [0003] The piercer and elongator used for carrying out the Mannesmann pipe manufacturing method as described above are equipped with a pair of inclined rolls and a guide member, each pair of which is disposed opposite to each other with a predetermined pass line in between, and a guide member which is disposed on the pass line. The hole-rolling or elongation rolling using these inner surface regulating devices such as plugs and mandrels is performed on the pipe material (billet in the case of Piaser, hollow tube in the case of Elongator) fed onto the pass line. A predetermined rolling reduction is applied between an inner surface regulating device penetrated into the axial center position and an inclined roll that rolls into contact with the outside of the tube material at this penetration position. FIG. 4 is a cross-sectional view showing the proper rolling state in the piercer. In the figure, 1, 1 is an inclined roll, 2,
2 is a disc roll which is a guide member, and 3 is a plug which is an inner surface regulating member. As shown in the figure, the inclined rolls 1, 1 are arranged on both the left and right sides of the plug 3 with a predetermined distance between them and the outer periphery of the plug 3, and the pipe material 4 to be rolled is centered on the axis of the inclined rolls 1, 1. The inner and outer sides are restrained by the plug 3 inserted into the position and the inclined rolls 1, 1 which roll into contact with the outer periphery, and a predetermined reduction is applied between the two to perform piercing rolling. The rotation of the inclined rolls 1, 1 is made to occur around separate rotation axes that are inclined in opposite directions by approximately the same angle with respect to the pass line of the tube material 4, and the tube material 4 is rotated around the axis in accordance with this rotation. It is rolled while being spirally moved in the longitudinal direction. [0005] The disc rolls 2, 2 are disc-shaped rolls with a large diameter, and are slightly larger than those of the inclined rolls 1, 1 between the upper and lower sides of the plug 3 and the outer periphery of the plug 3. They are spaced apart from each other to rotate around different rotation axes within a plane that includes the axis of the plug 3, that is, the pass line of the tube 4. An arc-shaped hole having a curvature corresponding to the outer diameter of the pipe material 4 is formed on the circumferential surface of the disc rolls 2, 2, and as shown in the figure, it is located at a position where the rolling reduction by the inclined rolls 1, 1 is not applied. The hole shape of the lever is brought into sliding contact with the outside of the tube 4 to suppress the outward bulge of the tube 4 and to correctly guide the tube 4 in the direction of movement. [0006] Problems to be Solved by the Invention [0006] The piercing rolling with the piercer as described above is carried out according to the selected piercing ratio (= length of billet to be obtained/length of hollow tube to be obtained). Rolling is performed by setting rolling conditions such as the distance between the inclined rolls 1 and 1 (roll opening degree) and the distance between the disc rolls 2 and 2 (guide distance), but in recent years, subsequent rolling mills There is a tendency for large drilling ratios to be selected in order to reduce the amount of work required. However, when piercing and rolling is performed at a large piercing ratio, the effect of elongation due to rolling is accumulated on the terminal end side of the pipe material 4, causing a phenomenon in which the vicinity of the terminal end flares, that is, so-called bottom flaring. During rolling, a flare part is caught in the gap between the inclined rolls 1, 1 and the side surfaces of the disc rolls 2, 2, as shown in FIG. The phenomenon of being stripped off (
This has the disadvantage of causing peeling, resulting in a decrease in yield. [0007] When rolling a portion where a bottom flare has occurred, there is also a possibility that a phenomenon (buckling) may occur in which the elongated portion of the flare portion is folded inward during rolling, and if this buckling is mild, As in the case of peeling, this only results in a decrease in yield due to poor shape near the end, but if the peeling is severe, the end of the pipe material 4 may slip out from between the inclined rolls 1, 1 and the plug 3. This causes a phenomenon in which it is difficult to process, so-called tail clogging, and post-processing thereof requires a large amount of time, resulting in a decrease in productivity. These difficulties occur in the same way with Elongator, and are a factor that hinders the implementation of elongation rolling at a large draw ratio (= length of the hollow shell tube to be obtained/length of the rolled tube to be obtained). There is. Incline rolling methods aimed at preventing the occurrence of peeling are disclosed in JP-A-59-35813 and JP-A-6.
This method is proposed in Japanese Patent No. 3-90306. As shown in FIG. 5, these are disc rolls 2, 2 (guide members) facing each other on the downstream side of the rotational direction of the inclined rolls 1, 1.
The focus is on the gap between the corner of the roller and the outer circumferential surface of the inclined rolls 1, 1. That is, the former is a method in which the shape of the inclined rolls 1, 1 is changed so that the biting gap is approximately 0 over the entire length in the rolling direction, and the latter is a method in which the shape is inclined with respect to the pass line. This is a method of reducing this gap as much as possible by installing a guide member (guide shoe or disc roll 2, 2) and aligning the corner part forming the biting gap with the exit surface of the inclined rolls 1, 1. . The former method is an effective method not only for peeling but also for preventing the occurrence of buckling, but it requires tilted rolls 1, 1 of a special shape, and requires additional equipment costs. Reduction of the biting gap by these inclined rolls 1, 1 is possible only when the roll conditions such as the inclination angle are under predetermined conditions, and if the roll conditions are changed, the biting gap increases. However, the problem arises that it becomes impossible to effectively prevent the occurrence of peeling, and conversely, the biting gap is reduced, causing the inclined rolls 1, 1 and disc rolls 2,
2 interferes with each other, making rolling itself difficult. Although the latter method has a certain effect on preventing peeling on the exit side of the inclined rolls 1, 1, on the entry side, the biting gap becomes larger, There is a problem in that the occurrence of peeling is promoted, and furthermore, there is a problem in that there is almost no effect of preventing the buckling, and it is impossible to eliminate the reduction in yield and deterioration in productivity accompanying the occurrence of buckling. The present invention has been made in view of the above circumstances, and it is an object of the present invention to eliminate the bottom flare that occurs at the end of a pipe material during rolling with an inclined rolling mill such as a piercer or an elongator without the need for a specially constructed device. It is an object of the present invention to provide a method for inclined rolling of tubes, which can effectively suppress the occurrence of peeling and buckling caused by bottom flare, and improve yield and productivity. [Means for Solving the Problems] A method for tilt rolling a pipe according to the present invention includes a pair of tilt rolls and a guide member, each pair of which is installed opposite to each other with a pass line in between. Accordingly, the pipe material spirally moves on the pass line,
In a method for inclined rolling of a pipe in which piercing rolling or elongation rolling is carried out between an inner surface regulating device penetrated into the axial center position of the pipe material and the inclined roll, when rolling a predetermined length range from the end of the pipe material, the inclined The distance between the rolls is increased by a predetermined amount, and the position of the guide member is changed so that the distance between the entrance side surface of the tube material in the guide hole type of the guide member and the circumferential surface of the inclined roll becomes a predetermined value. It is characterized by [Operation] In the present invention, the terminal end of the tube being rolled is detected in front of the installation position of the inclined roll using an appropriate detection means, and the roll opening degree is determined based on the point at which this detection is made. At the same time, the distance between the entrance side surface of the tube material and the circumferential surface of the inclined roll in the guide hole shape of the guide member is changed, so that rolling of a predetermined length range from the end of the tube material is performed more than other parts. By carrying out the process under a large roll opening degree and in a state where the distance between the circumferential surface of the inclined roll and the side surface of the guide member, which has increased due to implementation of this roll opening degree, is reduced by changing the position of the guide member, To suppress the occurrence of bottom flare and eliminate the inconvenience caused by it. [Embodiments] The present invention will be explained in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic diagram showing a state in which the method of tilt rolling a pipe according to the present invention (hereinafter referred to as the method of the present invention) is implemented in a piercer, and FIG. 2 is a partially enlarged cross-sectional view taken along line II--II in FIG. 1. The piercer comprises a pair of inclined rolls 1, 1, a pair of disc rolls 2, 2 functioning as guide members, and a plug 3 serving as an inner surface regulating device. Inclined roll 1
, 1 are arranged opposite to each other on both sides of the pass line XX, as shown in FIG. are rotated around separate rotational axes having an inclination angle β of . Note that the illustrated inclined rolls 1, 1 are provided with a gorge portion 1a having a diameter intermediate between the small-diameter inlet end and the large-diameter outlet end, and the gorge portion 1a, the inlet end, and the outlet end are connected to each other. The cone-shaped roll is connected to the side ends by an entrance surface 1b and an exit surface 1c, both of which have slopes.
These may also have other shapes such as a barrel shape. Further, the disc rolls 2, 2 having a large diameter disc shape are inclined in the longitudinal direction of the pass line X--X.
, 1, they are arranged facing each other on both sides of the upper and lower sides with the pass line There is. Furthermore, the plug 3 has a bullet shape as shown, and is fixed to the tip of the mandrel bar 30 so as to be movable forward and backward on the pass line XX. FIG. 3 is an explanatory view showing the progress of piercing and rolling by the piercer configured as described above. The tube material 4 fed along the pass line XX first passes through the inclined rolls 1, 1.
The plug is caught between the entrance surfaces 1b, 1b, and is given a forward force by these rotations to spirally move on the pass line XX and reach the tip of the plug 3 (see FIG. 3(a)). The plug 3 located on the pass line XX has the effect of penetrating the axial center of the tube material 4 so as to be screwed into the tube material 4, and the tube material 4 into which the plug 3 has been inserted is A predetermined reduction is applied between the outer circumferential surface of and the inclined rolls 1, 1 to form a tubular shape (see FIG. 3(b)). The diameter is expanded along the slope of 1c and sent out as a hollow tube 4' (
(See Figure 3(c)). FIG. 2 is a cross-sectional view at a corresponding position of the gorge portions 1a, 1a, and as shown in the figure, the circumferential surfaces of the disc rolls 2, 2 are provided with arc-shaped holes 20, 2 having a predetermined curvature.
0 is formed, and during rolling, these hole types 20,20
The distance between the bottoms of the rollers (guide distance Gg) is set to be slightly larger than the distance between the gorge portions 1a (roll opening degree Rg). And these hole types 20,2
0 slides on the outside of the tube material 4 at a position where it is not rolled down by the inclined rolls 1, 1, suppressing outward bulges, and serves to correctly guide the tube material 4 in the direction of movement. That is, the rolling of the tube material 4 in the gorge portions 1a, 1a is performed while presenting an elliptical shape as shown in FIG. The inclined rolls 1, 1 are provided with a roll opening adjustment device 5 for moving them toward and away from each other to change the roll opening Rg, and the disc rolls 2, 2 are provided with a roll opening adjustment device 5 for changing the roll opening Rg.
A guide position adjuster 6 is attached to change the distance b (see FIG. 2) between the entrance side side surface of the tube material 4 in these hole shapes 20, 20 and the circumferential surface of the inclined rolls 1, 1, and the guide position adjuster 6 is attached thereto. When performing piercing rolling, a roll opening adjustment machine 5 and a guide position adjustment machine 6 are used to obtain a preselected piercing ratio.
This is done with the roll opening degree Rg and guide position properly set. [0020] When performing piercing and rolling using the piercer as described above,
The method of the present invention, which is carried out in order to prevent the occurrence of bottom flare near the terminal end of the pipe material 4, is performed by rolling the inclined roll 1 as shown in FIG.
.
This is carried out by detecting the rolling load during rolling and driving the roll opening degree adjuster 5 and the guide position adjuster 6 by the operation of the control unit 9 which is given these detection results. Note that the termination detector 7 is, for example, one in which a laser beam emitter and a laser beam receiver are disposed opposite to each other with the tube material 4 in between, and detects passage of the termination when the light emitted from the emitter is captured by the receiver. You can use [0021] The control unit 9 has a change amount in which changes in the roll opening degree Rg and the guide interval Gg are set based on rolling information such as the inclination angle β of the inclined rolls 1, 1, the advancing speed of the tube material 4, and the perforation ratio. Based on the amount setter 10, the rolling information, the installation position of the end detector 7, and other information, the time from when the end of the pipe material 4 is detected by the end detector 7 to when control is started is set. The output of the timer setter 11 is also provided. The control section 9 recognizes the start and end of rolling from the output of the load detector 8, starts its operation at the start of rolling, and monitors the output of the end detector 7. When the output of the end detector 7 changes due to detection of the end of the pipe material 4, the roll opening adjustment device 5 and the guide position adjustment device 6 are activated from this point on until the time set in the timer setting device 11 has elapsed. Issue a command. In response to this, the roll opening adjustment device 5 moves the inclined rolls 1, 1 in the direction shown by the white arrow in FIG. The action is to increase the amount by a certain amount. On the other hand, the guide position adjuster 6 operates to change the position of the disc rolls 2, 2 so that the distance b between the circumferential surface of the inclined rolls 1, 1 and the side surface of the disc rolls 2, 2 becomes a predetermined value. to do. Further, the control unit 9 issues a return command to the roll opening adjustment machine 5 and the guide position adjustment machine 6 at the time when the end of rolling is recognized by the output of the load detector 8,
The roll opening degree Rg and the guide position are returned to the state before the change, and the operation is completed. Through the above operations, the pipe material 4 is
From the end of this roll to a predetermined position on the upstream side for a predetermined length, rolling is performed under a preset roll opening Rg and guide position, but in the range from the predetermined position to the end, Rolling is carried out under the roll opening Rg and with the distance b between the inclined rolls 1, 1 and the disc rolls 2, 2 slightly increased. The time set by the timer setter 11 starts from the time when the end of the pipe material 4 is detected at the location where the end detector 7 is installed, until the predetermined position reaches the gorge portions 1a, 1a of the transport rolls 1, 1. This value is determined from the rolling information and the location of the end detector 7 as described above. Further, the change amount of the roll opening degree Rg set in the change amount setting devices 10, 10 is a predetermined value in the increasing direction,
The amount of change in the guide position is the direction in which the side surfaces of the disc rolls 2, 2 approach the circumferential surfaces of the inclined rolls 1, 1, and is approximately equal to the amount of movement of the inclined rolls 1, 1 for changing the roll opening degree Rg. Just set them equal. Finally, the results of tests conducted to demonstrate the effectiveness of the method of the present invention will be shown. This test used a piercer and an elongator to test the method of the present invention and the conventional method in which the roll opening degree Rg and the guide position are not changed near the end of the pipe material 4 under various perforation ratios (stretching ratios). The procedure was carried out to examine the occurrence of peeling and buckling in both cases. Table 1 shows the rolling conditions of the test conducted using a piercer, and Table 2 shows the test results. [0026] In carrying out the method of the present invention, the amount of change in the roll opening degree Rg is increased by 1 mm, and the amount of change in the guide position is The distance b (see FIG. 2) was set to be approximately constant before and after the movement. This is achieved by setting the amount of movement of the disc rolls 2, 2 to 0.5 mm, respectively. The ○ marks in Table 2 indicate cases where stable rolling was possible over the entire length of the tube material 4 and no peeling or buckling was observed in the hollow tube after rolling.
On the other hand, the x marks indicate cases where the occurrence of peeling or buckling was observed, and as is clear from Table 2, when the method of the present invention is implemented, stable piercing rolling is possible even under a high piercing ratio. becomes. [0028] Table 3 shows the rolling conditions of the test conducted using an elongator, and Table 4 shows the test results. [0030] Note that the roll opening Rg and the amount of change in guide position in this test were the same as those in the Piaser test, and as is clear from Table 4,
It has been found that by implementing the method of the present invention, stretch rolling at a high draw ratio can also be performed stably. In this embodiment, disc rolls 2, 2 are used as guide members, but the method of the present invention can also be applied to an inclined rolling mill equipped with other guide members such as guide shoes. , it goes without saying that similar effects can be obtained. As described in detail above, in the method of the present invention, when rolling a predetermined length range from the end of the pipe material, the distance between the pair of inclined rolls is increased by a predetermined amount, and the position of the guide member is The extremely simple procedure of changing the side surface of the roll so that it is close to the peripheral surface of the inclined roll effectively reduces the bottom flare that occurs at the end of the pipe material when the pipe is inclinedly rolled in an inclined rolling mill such as a piercer or elongator. The occurrence of peeling and buckling associated with bottom flaring is prevented, and the inconveniences caused by these phenomena are eliminated.
The present invention has excellent effects, such as being able to contribute to improvement in yield and productivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention in a piercer.

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1;

FIG. 3 is an explanatory diagram of the progress state of piercing and rolling in the piercer.

FIG. 4 is a cross-sectional view showing a normal rolling state in the piercer.

FIG. 5 is a cross-sectional view showing how peeling occurs in the piercer.

[Explanation of symbols]

1 Inclined roll 2 Disc roll 3 Plug 4 Piping material 5 Roll opening adjustment machine 6 Guide position adjustment machine 7 Termination detector 9 Control section

Claims (1)

[Claims] 1. A pair of inclined rolls and a guide member are provided opposite to each other with a pass line in between, and a pipe member that spirally moves on the pass line in accordance with the rotation of the inclined rolls is arranged so that its axis In a method for inclined rolling of a pipe in which piercing rolling or elongation rolling is performed between an inner surface regulating device penetrated into a position and the inclined roll, when rolling a predetermined length range from the end of the pipe material, the distance between the inclined rolls is In addition to increasing the distance by a predetermined amount, the position of the guide member is changed so that the distance between the entrance side surface of the pipe material in the guide hole type of the guide member and the circumferential surface of the inclined roll becomes a predetermined value. Incline rolling method for pipes.