JPH0441021A - Device for manufacturing welded pipe - Google Patents

Abstract

PURPOSE:To make enough the edge forming for the range from the thick wall material to the thin wall material by providing the mechanism for adjusting the interval of the roll stands and the mechanism for adjusting the interval of the upper and lower rolls and the inclining angle of the lower side roll. CONSTITUTION:The interval of the upper and lower rolls is adjusted by adjusting the roll reduction of the upper side roll (1-3), and also the inclinating angle beta is adjusted by sliding the bearings (1-8) of the lower roll (1-4) along the circular arc surface (1-7) for the metallic sheet of the different thickness. Because the edge bend forming is enough executed by adjusting the inclinating angle beta to be larger about the inclinating angle beta on the thin wall material, so the rigidity of the edge part is increased, and the prevention of the edge buckling is largely effected. Especially, on the case of the thin wall material, the effect for preventing the edge from elongating is more effectively displayed on the cage roll because the edge bend forming is enough executed on the former stage of the forming roll group.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a welded pipe manufacturing apparatus incorporating a group of forming rolls for continuously forming a metal strip into a cylindrical shape.

Conventional technology For example, welded pipes such as electric resistance welded pipes are produced by first gradually forming a flat metal strip into an arc shape in a roll forming step, and after forming the arc-shaped metal band into a tube shape in a final step, a pressure welding step is performed. It is manufactured by melt-welding the butt edges together.

In this step of roll forming into a tubular shape, so-called roll bending is performed, and the first step is generally called breakdown, which is forming into an arc shape, and then that arc is shaped into an even smaller radius. Formed into a tubular shape,
The final stage is called the fin bath, in which a tubular butt edge is formed.

In roll forming of such welded pipes, in order to obtain the desired product shape, pre-bending performed on both ends of the metal strip in the width direction is extremely important. If it is not present, it will cause a decrease in the shape quality of the welded part or a decrease in material yield.

By the way, when manufacturing thin-walled and thick-walled welded pipes, metal strips from thin to thick-walled materials are usually formed using the same roll, so there is a problem in that it is not possible to bend the edges of thin-walled materials. .

Figures 5 (A) and (B) are state diagrams during thin-walled material molding, respectively;
It is a state diagram during thick-walled material molding, (10) is the upper roll, (
11) shows the lower roll, and (12) shows the metal band.

In other words, in the case of thick materials, as shown in Figure (B), it is possible to bend the edge of the metal f (12) caught between the upper roll (10) and lower roll (11). ,
If the material is thin, the edges cannot be bent as shown in Figure (A). Rather, the edges of thin materials tend to stretch a little compared to the center of the metal band, and these stretched edges bend and become wavy, resulting in poor welding.

For example, if the ratio t/D of the wall thickness t to the outer diameter is less than 1.5%, undulations will occur at the side edges of the metal band during forming.

This phenomenon is usually called edge buckling.

In addition, as a bending method for edges,
Even with the method called the W-bending method disclosed in Publication No. 4, thin to thick materials are formed using a fixed lower roll, so it is not possible to sufficiently pre-bend the edges of thin materials. Can not.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 64-44217, there is a welded pipe manufacturing apparatus in which the lower roll of a horizontal roll is divided into two parts, and the angle of inclination in the advancing direction of the metal band can be adjusted.

On the other hand, in the breakdown roll group used in the existing manufacturing equipment for welded pipes with medium diameter or larger (outer diameter 10 inches or more), the outer diameter That is, the lower roll is commonly used even if the metal strip width is different.

However, such a device is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 64-4421.
When a pipe manufacturing apparatus such as that disclosed in Publication No. 7 is applied, a plurality of rolls are required in order to correspond to the outer diameter size of the final product, and the cost of the rolls becomes extremely high.

In addition, as shown in FIG. 6, a fixed lower roll (101)
A special edge forming stand with an upper roll (102) whose distance from the lower roll can be adjusted is combined with stand No. 001 in the normal breakdown roll stand group.
, and two stands to perform pre-bending forming.

However, in this method as well, since the roll axis of the lower roll is fixed at both the angle of inclination and the angle of intersection, the edge formation becomes insufficient in the case of thin-walled materials. As a result, the bending rigidity of the edge portion in the rolling direction is weakened, and the edge portion of the breakdown steel sheet advances in a wavy manner between the roll stands, causing edge elongation and edge buckling before and after the fin bath.

Furthermore, since the edge forming stand is installed behind the No. 1 breakdown stand, the material with no bent edges is fed to the No. 11 breakdown stand. Therefore, edge elongation occurs at the NO31 breakdown stand, and edge buckling occurs before and after the fin bath.

Problems to be Solved by the Invention As mentioned above, in a method for manufacturing a welded pipe in which the lower roll of the horizontal roll of the breakdown is divided into two and the angle of inclination in the direction of movement of the metal band can be adjusted, the above-mentioned t. /D
Edge buckling occurs in thin materials with a hardness of 1.5% or less.

Furthermore, even with an edge forming stand, edge forming of thin-walled materials is insufficient, leading to edge buckling, making it difficult to form thin-walled tubes.

In the roll forming of welded pipes, this invention sufficiently bends both edges of a metal strip, prevents edge buckling even in thin wall materials, and sufficiently bends edges from thin to thick materials with one set of rolls. It is an object of the present invention to provide a welded pipe manufacturing apparatus equipped with a roll preforming mechanism that can perform the following steps.

Means for Solving the Problems The present invention provides a welded pipe comprising a group of forming rolls for continuously forming a metal strip into a cylindrical shape, and a welding means for joining both edges of the metal strip formed into a cylindrical shape. A manufacturing device,
Consisting of a pair of left and right roll stands, and a pair of upper and lower edge forming rolls that are cantilever-supported by the roll stands and whose roll axes interval can be adjusted, the roll axis of at least the lower forming roll of the edge forming rolls is An edge preforming device that is supported so as to intersect with a direction perpendicular to the direction of travel of the metal strip at an appropriate angle of inclination in the plane of travel of the metal strip, and whose angle of inclination is adjustable, is installed at the front stage of the group of forming rolls. The gist of the present invention is a welded pipe manufacturing apparatus characterized in that it is provided with a welded pipe manufacturing apparatus.

Function In this invention, the distance between the left and right roll stands of the edge preforming device is determined according to the outer diameter size (width of the metal strip) so that the portion corresponding to the edge portion of the metal strip comes into contact with the roll. Adjust and set the distance between the pair of stands and the distance between the upper and lower rolls.

The distance between the upper and lower pair of forming rolls of the left and right pair of roll stands is preferably the same as the thickness of the metal band.

Further, it is preferable that the inclination angle of the lower roll is large for thin-walled materials, and is larger for thick-walled materials.

As described above, the edge preforming device of the present invention can adjust the interval between the pair of left and right roll stands, so even if the width of the metal strip is different, it is possible to bend the edge without changing the rolls.

Further, by adjusting the rolling position of the upper roll and the inclination angle of the lower roll, it is possible to form metal strips with different thicknesses into a predetermined shape up to the ends thereof. In other words, in the case of thick-walled materials, the edge portions are reliably kept in the specified position without reducing the wall thickness of the edge portions and causing roofing, and in the case of thin-walled materials, without creating unbent portions. It becomes possible to bend it into a shape.

Therefore, even in a thin material, the edges can be sufficiently bent, thereby increasing the rigidity of the edge portion and preventing edge pack rings.

As described above, according to the edge preforming device of the present invention, the distance between the left and right roll stands is adjusted when the outer diameter sizes are different, and the distance between the upper and lower rolls and the inclination of the lower roll are adjusted when the wall thicknesses are different. By adjusting the angle, edge forming can be performed without changing rolls. Furthermore, in the present invention, since the edge preforming device is installed before the forming roll group, it is extremely effective in preventing edge buckling when forming thin materials.

Embodiment FIG. 1 is a schematic plan view showing an apparatus according to an embodiment of the present invention, FIG. 2 is a schematic front view showing an edge preforming device in the same device, and FIG. 3 is a lower side forming of the same edge preforming device. It is a schematic plan view which shows the inclination angle adjustment mechanism of a roll.

In FIG. 1, (1) shows an edge preforming device, (2) a normal breakdown stand, (3) a cage roll stand consisting of a large number of small roll groups, and (4) a fin pass stand.

The edge preforming device (1) consists of a pair of left and right roll stands (1-1), a spacing adjustment shaft (1-2), an upper forming roll (1-3), and a lower forming roll (1-4). The pair of left and right roll stands (1-1) are screwed together with the spacing adjustment shaft (1-2) via a nut member (1-5) provided at the bottom of the roll stands (1-1). 1-2
) is a mechanism that allows them to move toward and away from each other by rotating them.

The upper forming roll (1-3) is connected to the bearing box (1-6)
The box is supported in a cantilever manner, and can be adjusted by a reduction adjustment mechanism built into the box.

The lower forming roll (1-4) has a bearing (1-4) that slides on the same arcuate surface (1-7) formed on the roll stand.
-8), and is variably mounted so as to cross the direction perpendicular to the direction of movement of the metal band at an inclination angle β in the plane of movement of the metal band.

Of course, the mechanism for adjusting the inclination angle β of the lower forming roll (1-4) is not limited to the one illustrated here; for example, a method of rotating the roll stand itself around a vertical axis may also be used. can.

In the edge preforming device having the above structure, when the outer diameter size is different, that is, when the width of the metal strip is different, the spacing adjustment shaft (1-2) is rotated to adjust the width of the left and right roll stands (1-1). Adjust spacing.

Moreover, the distance between the upper roll (1-3) and the lower roll (1-4>) is adjusted by the amount of rolling of the upper roll <1-3>.

Preferably, the spacing is the same as the thickness of the metal strip.

In addition, for metal strips with different wall thicknesses, the upper roll (1
-3) Adjust the distance between the upper and lower rolls by adjusting the reduction, and adjust the inclination angle β by sliding the bearing (1-8) of the lower roll (1-4) along the arc surface (1-7). do. Especially for thin materials with t/D of 1.0 to 1.5%, by adjusting the inclination angle β to a large value, the edges can be bent sufficiently. Increases rigidity and is highly effective in preventing edge buckling. Particularly in the case of thin-walled materials, the edges are sufficiently bent and formed before the forming roll group, so that the effect of suppressing edge elongation with cage rolls is more effectively exhibited.

Note that, as shown in FIG. 4, the same effect can be obtained when a pair of left and right roll stands (1-1) are installed so as to have an inclination α in a plane perpendicular to the direction in which the metal strip travels. Furthermore, in this case, if we try to form the edge so that the bending angle with respect to the center of the metal band is the same as when it does not have the inclination α, the difference in outer diameter in the axial direction is small, in other words, Since it is possible to use rolls with a small difference in outer circumferential speed, it is possible to effectively suppress seizure defects that occur at the edge portions due to slippage.

Example 1 Outer diameter 50.8 mm (common), wall thickness 1.0 mm (t/
D=2.0%), 0.8mm (t/D=1.6%)
, 0.7 mm (t/D = 1.4%), the edge preforming device of the present invention shown in FIGS.
2) when installed in the front stage of breakdown stand (2) (example of the present invention), and installed in the rear stage of breakdown stand (2) (comparative example).
Table 1 shows the results of performing roll forming in three cases (conventional example without edge preforming device) and examining the presence or absence of edge buckling at that time.

As is clear from Table 1, in the case of the conventional example (without edge preforming device), edge cracking occurs in all cases, and when the edge preforming device is installed at the rear of the breakdown stand, the wall thickness While edge buckling occurred with 0.0 and 7 aon, in the present invention, edge buckling occurred with a wall thickness of 1.0 nm.
On, 0.8 mm, and 0.7 mm, there was no buckling at all.

Table 1 ○: No edge buckling ×: Edge buckling present As described in detail in the invention, the apparatus of this invention has a roll stand interval adjustment mechanism, an interval between upper and lower rolls, and an inclination angle of the lower roll. Thanks to the edge preforming device equipped with an adjustment mechanism, it is possible to bend the edge without changing rolls even when the width of the metal strip is different, and it is also possible to form edges from thick to thin materials. and
It is particularly effective in preventing edge pack rings during thin-walled molding, and is highly effective in manufacturing welded pipes.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an embodiment of the present invention, FIG. 2 is a schematic front view showing an edge preforming device in the same device, and FIG. 3 is an inclination angle of the lower roll of the edge preforming device. FIG. 4 is a schematic plan view showing the adjustment mechanism, FIG. 4 is a schematic front view showing another embodiment of the edge preforming device, and FIG. A
) is a state diagram when forming a thin-walled material, (B) is a state diagram when forming a thick-walled material, and FIG. 6 is a schematic front view showing an example of a conventional edge forming stand. 1... Edge preforming device 1-2... Spacing adjustment shaft 1-4... Lower roll 1-1... Roll stand 1-3... Upper roll 2... Breakdown stand 3... Cage Roll stand 4/Finpass stand

Claims (1)

[Claims] In a welded pipe manufacturing apparatus, which is equipped with a group of forming rolls that continuously form a metal strip into a cylindrical shape, and a welding means for joining both edges of the cylindrical metal strip, a pair of left and right roll stands; , consisting of a pair of upper and lower edge forming rolls that are cantilever-supported by the roll stand and whose roll axes interval is adjustable, and of the edge forming rolls, at least the lower forming roll has a roll axis in the plane of movement of the metal strip. An edge preforming device that is supported so as to intersect with a direction perpendicular to the traveling direction of the metal band at an appropriate angle of inclination and whose inclination angle is adjustable is provided at the front stage of the group of forming rolls. Equipment for manufacturing welded pipes.