KR101526342B1 - Manufacturing method and manufacturing equipment for small diameter metal tube - Google Patents

Abstract

The use of a large-diameter roll having a diameter clearly larger than the outer diameter of the metal pipe to be manufactured is used to manufacture a small-diameter metal pipe with high precision and high production efficiency. A pair of large-diameter side rolls designed to have an outer diameter (PHI ₁ ) of the metal pipe to be produced and an outer diameter ratio (PHI ₂ / PHI ₁ ) of the outer diameter (PHI ₂ ) of the forming roll of 10 or more, preferably 25 or more, After forming the metal band into a cylindrical shape in a single stand, the edge portions of the metal band are butted and welded together. As the large diameter side roll, a three-roll rolling type or a four-roll rolling type may be used.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a small-diameter metal pipe,

The present invention relates to a method of manufacturing a metal pipe, particularly a small-diameter weld pipe having an outer diameter of less than 20 mm, with high efficiency, and an apparatus therefor.

Generally, a manufacturing method by a roll forming method is employed for manufacturing a welded metal tube. The roll forming method is a method in which a metal band is supplied to a plurality of roll forming stands arranged in a tandem, for example, ten or more stages, and the metal band is continuously formed into a cylindrical shape (for example, Patent Document 1). Thereafter, both side edges (i.e., edge portions) of the cylindrical metal sheet are welded and bonded together to produce a metal tube.

However, in the roll forming method, since the production line is constituted by a plurality of roll forming stands, that is, a multi-stage stand, as described above, when changing the diameter of the metal pipe, Is increased. In addition, there is also a problem that the production efficiency of the welded metal pipe is lowered because the downtime of the production line is prolonged with the roll exchange operation.

In the case of manufacturing a small-diameter metal tube having an outer diameter of 20 mm or less, in the above-described roll forming method, unless rigorous adjustment is carried out in each of the stands, a metal band is likely to be bent, warped, or otherwise formed, There is a problem of remarkably deteriorating.

Therefore, in the case of manufacturing a small-diameter metal pipe having an outer diameter of 20 mm or less, it is preferable to reduce the number of forming stands as much as possible in order to improve the working efficiency and productivity, and more preferably, it is manufactured in a single stand.

As a method of manufacturing a welded metal tube, a die draw forming method is employed in addition to the roll forming method described above. The die draw forming method is a manufacturing method in which a metal band is supplied to a molding die, and then the metal band is taken out from the molding die to continuously form the metal band into a cylindrical shape (see, for example, Patent Document 2). In this manufacturing method, one molding die used for molding the metal band into a cylindrical shape is sufficient. That is, the forming stand is solved in one stage.

However, in the die draw forming method, when metal strips are fed to and withdrawn from the forming dies, significant friction occurs between the forming dies and the metal strip. Therefore, in order to suppress such friction, it has been proposed to apply lubricating oil to the surface of the metal base (refer to Patent Document 2).

However, even if lubricating oil is applied to the metal surface, if a metal band is scratched during the process of manufacturing the metal band, the metal powder dropped from the wound is brought into the molding die while being attached to the metal band, There is a problem that it is accumulated in the molding die. If the metal powder is accumulated in the molding die, if the inside of the molding die is not frequently cleaned, the surface of the metal tube may be scratched. Then, after the production of the metal tube, the surface polishing treatment must be carried out as a treatment of surface wounds. That is, even when the die-draw forming method is used, there arises a problem that the productivity is lowered and the production cost is increased.

However, laser welding is employed as a method of butt welding the edge portion of the metal band formed into a cylindrical shape irrespective of the roll forming method and die draw forming method described above. The laser welding method is preferable from the viewpoint of productivity and workability of the welded metal pipe.

Japanese Patent Application Laid-Open No. 6-134525 Japanese Patent Application Laid-Open No. 8-267150

As described above, the roll forming method has problems not only in that the work load due to the roll changing operation and the dimension adjustment is increased, but also in the case of manufacturing a small-diameter metal pipe, There is a problem that a problem tends to occur when the edge of the metal band is twisted or the like.

Further, in the die draw forming method, a large amount of lubricating oil is used in order to suppress the friction generated between the metal strip and the forming die. Therefore, there is a problem that laser welding can not be performed unless the metal pipe is degreased after being formed into a cylindrical shape.

The present invention has been proposed in order to solve such a problem. That is, only one roll having a diameter that is clearly larger than the outer diameter of the metal pipe to be manufactured, that is, a large-diameter roll of a single stand is used. It is another object of the present invention to provide a method of manufacturing a small-diameter metal pipe in which a metal base is formed into a cylindrical shape with high precision without using lubricating oil, and then the edge portions of the metal bands are welded together.

Method of manufacturing a small-diameter metal pipe of the present invention, to achieve the purpose, the outer guard of the outer diameter (Φ ₁₎ and the diameter (Φ ₂₎ of the roll of the metal tube to be produced (Φ ₂ / Φ ₁₎ has one or more at least 10 pairs Wherein the pair of large-diameter sidewall rolls comprise at least a first large-diameter sidewall roll, a first large-diameter sidewall roll, and a first large-diameter sidewall roll, Wherein the bottom roll has an offset in the inlet side direction of the roll stand relative to a straight line connecting the rotation axis of the first large diameter side roll and the rotation axis of the second large diameter side roll, And a metal band is supplied to the roll stand. After the metal band is formed into a cylindrical shape, an edge portion of the metal band is welded to the roll stand.

It is preferable that the outer diameter ratio? ₂ /? ₁ is 25 or more. In order to improve the abutment shape of the edge portion at the time of welding as described later, it is preferable that the metal band is fed to the edge band roll before the metal band is supplied to the large-diameter side roll, and the edge portion of the metal band is bent in advance .

It is preferable that the large diameter roll stand used in accordance with the practice of the present invention is arranged in a three-roll system composed of two large-diameter side rolls and one bottom roll (see Fig. 8 (A)). 8 (A) is a cross-sectional view showing the structure of a three-roll type large-diameter side roll having a bottom roll as described later. Specifically, the arrangement of the rolls is such that a pair of large-diameter side rolls are arranged in parallel so that the rotation axes thereof are parallel to each other and the outer circumferential surfaces of the large diameter side rolls face each other. The bottom roll is arranged so that the outer circumferential surface of the bottom roll is located in the vicinity of the opposing portion where the outer circumferential surfaces of the two large-diameter side rolls face each other. At the opposing portion, when the metal tube is molded, the edge portions are brought into contact with each other. Further, the rotation axis of the bottom roll is substantially orthogonal to the rotation axis of the two large-diameter side rolls. Further, it is preferable that the bottom roll be disposed offset on the upstream side in the advancing direction of the metal band (that is, on the inlet side of the production line) with reference to a line connecting the rotation shafts of the pair of large-diameter side rolls (See Fig. 10). Fig. 10 is a top view showing a more preferable installation position of the bottom roll used in the triple-roll type large-diameter side roll of the present invention, as described later. Thus, by offsetting the bottom roll on the upstream side in the direction of travel of the metal band, the deformation occurring at the time of forming the metal tube can be further reduced.

In addition, in the above-described three-roll method, a four-roll method in which pin-rolls are further disposed may be employed (see FIG. 11). The pin roll is disposed on the opposed portion so that the outer circumferential surface thereof faces the outer circumferential surface of the bottom roll and the rotational axis thereof is parallel to the rotational axis of the bottom roll. By disposing the fin rolls in this manner, it is possible to maintain the position where the edge of the metal band meets with high accuracy.

The fin roll may be disposed on the squeeze roll just before the edge of the metal band is welded to the squeeze roll. This pin-roll makes it possible to suppress warping of the abutting position of the edge portion of the metal band at the position of the pin-roll (see Fig. 13). The fin roll used at this time preferably has a fin and a concave surface having a radius of curvature larger than that of the metal pipe to be produced. This is because, by using the above-mentioned pin-roll, the pin accurately positions the position of the abutted portion at a desired position for the next welding, and presses the edge portion of the metal band by the concave surface to correct the shape when the edge portion is abutted It is because. As a result, a small-diameter metal pipe with excellent forming accuracy can be obtained.

In the present invention, by using a side roll having an apparently large outer diameter with respect to the outer diameter of a metal pipe to be produced, it is possible to manufacture a small diameter metal pipe having excellent surface properties with high efficiency, It is possible. In addition, by forming the metal band into a cylindrical shape in a single stand, the total number of stands required for manufacturing the metal pipe can be greatly reduced, and the work load for the roll changing operation and the dimensional adjustment by the operator can be reduced. In addition, by appropriately using pin-roll, it is possible to stably manufacture a small-diameter metal pipe.

Fig. 1 (A) is a perspective view showing a schematic structure of a large-diameter side roll used in the present invention and a positional relationship of a welder for weld-joining an abutted portion of an edge. Fig. Fig. 1 (B) is an enlarged view showing a groove portion of the large-diameter side roll.
Fig. 2 is a diagram showing the relationship between the external ratio (PHI ₂ / PHI ₁ ) and equivalent plastic deformation occurring at the edge of the metal band.
3 is a schematic view of a production line used for manufacturing the small-diameter metal tube of the present invention.
4 is a cross-sectional view showing a schematic structure of an edge band roll.
5 is a cross-sectional view showing a schematic structure of a large diameter side roll.
6 is a view showing that the edge portion of the metal band is bent using two large-diameter side rolls.
Fig. 7 is a diagram showing a situation in which a part of the metal band being deformed has a problem between two large-diameter side rolls. Fig.
8A is a cross-sectional view showing the structure of a three-roll type large-diameter side roll in which a bottom roll is arranged, and FIG. 8B is an enlarged view showing a positional relationship between two large-diameter side rolls and a bottom roll.
Fig. 9 is a top view showing a mounting position of the bottom roll used in the triple-roll type large-diameter side roll of the present invention.
10 is a top view showing a more preferable installation position of the bottom roll used in the three-roll anti-roll type large diameter side roll of the present invention.
11 is a cross-sectional view showing the structure of a four-roll type large-diameter side roll in which a first pin roll is disposed in a three-roll type large-diameter side roll of the present invention.
Fig. 12 is a view for explaining the situation of a metal band in a case where pin-rolls are arranged in one stage.
Fig. 13 is a view for explaining a situation of a metal band in a case where pin-rolls are arranged in two stages.
Fig. 14 is a view for explaining the shape of the edge portion at the butted portion of the large-diameter metal tube. Fig.
Fig. 15 is a view for explaining the shape of the edge portion at the butted portion of the small-diameter metal tube. Fig.
16 is a view showing a preferable shape of the second pin-roll disposed immediately before the squeeze roll.

Molding of a metal tube by the roll forming method is generally gently molded by multi-step molding using ten or more roll forming stands arranged in a tandem. Therefore, when changing the diameter of the metal pipe to be manufactured, it is necessary to replace all of the rolls disposed on the forming stand with one corresponding to the outer diameter of the metal pipe to be manufactured. In addition, since the roll exchanging requires a lot of labor and time, the productivity is lowered.

The present invention has thus been found to provide means for gently forming a metal band into a cylindrical shape in a single stand and reducing the deformation of the metal band formed during roll forming. Details thereof will be described below.

The large-diameter side roll used in the present invention will be described with reference to Fig. The large-diameter-side rolls (42, 44) in the present invention (with reference to FIG. 1 (A)), the ratio of the diameter (Φ ₂₎ of the forming roll about the wish to manufacture metal tube outer diameter _{(Φ 1) (Φ 2 /} Φ ₁ ) is significantly increased. The external ratio? ₂ /? ₁ is 10 or more, preferably 25 or more.

The large diameter side rolls 42 and 44 designed to increase the outer diameter ratio? ₂ /? _{1 in} this manner can be regarded as molding dies used in the die draw forming method. That is, in molding the metal base 100 into a cylindrical shape, the present invention can be molded in a single stand instead of a multi-stage stand. However, the present invention does not require the lubricant used in the die draw forming method.

Further, the method for manufacturing a metal pipe according to the present invention is preferable for manufacturing a small-diameter metal pipe having an outer diameter of less than 20 mm. This is because the method of manufacturing a metal pipe according to the present invention is based on the necessity of a large diameter side roll having a considerably large outer diameter ratio according to the outer diameter of a metal pipe to be manufactured. That is, in the case of manufacturing a small-diameter metal pipe having an outer diameter of less than 20 mm, it is possible to use a large-diameter side roll having an actual diameter. In the case of manufacturing a metal pipe having an outer diameter exceeding 20 mm, It is disadvantageous in that it is necessary to prepare rolls, which is not realistic and increases the cost.

Here, a preferable relationship between the outer diameter (PHI ₁ ) of the metal pipe to be produced and the outer diameter ratio (PHI ₂ / PHI ₁ ) of the outer diameter (PHI ₂ ) of the molding roll will be described. The metal band can be gently roll-formed by using a side roll having a large outer ratio (PHI ₂ / PHI ₁ ) which is a ratio of the outer diameter (PHI ₂ ) of the forming roll to the outer diameter (PHI ₁ ) of the produced metal pipe. That is, it is possible to perform molding while reducing deformation caused during molding.

2 shows the relationship between the outer guards (Φ ₂ / Φ ₁₎ and corresponds to plastic deformation occurring in the metal portion one edge (see Fig. 2). By setting the external ratio (PHI ₂ / PHI ₁ ) to 10 or more, it is possible to form the metal band into a cylindrical shape in a state where the deformation occurring 0.25 mm inward from the edge portion of the metal band is further reduced (see FIG. In addition, by setting the outer diameter ratio (PHI ₂ / PHI ₁ ) to 10 or more, it is possible to perform molding in a state in which the cross-sectional shape when the edge portion of the metal band is curved is good and there is no warping. Further, in the side surface of the metal band (see Fig. 2), it becomes constant at a low position when the external ratio (PH ₂ / PHI ₁ ) is about 25.

Therefore, it is more preferable to set the external ratio (PHI ₂ / PHI ₁ ) to 25 or more. The upper limit of the external cost is not particularly specified, but it is practical to set the upper limit to about 80. This is an upper limit that can be considered in consideration of the point that the effect of reducing the deformation occurring at the edge of the metal band is saturated at an outer diameter ratio (? ₂ /? ₁ ) of about 80 and the roll cost.

It is preferable that the metal band 100 is fed to the edge band roll before forming the metal band 100 into a cylindrical shape by using the single large-diameter side rolls 42 and 44. As a result, it is possible to bend the edge portion of the metal band 100 in advance, thereby smoothly curving the edge portion in the large diameter roll.

The manufacturing method of the present invention will be described with reference to Fig. Fig. 3 schematically shows an actual production line used for manufacturing the small-diameter metal tube of the present invention.

The metal band 100 is fed to the edge band roll stand 30 while aligning both edges of the metal band 100 with the guide 20 while being pressed by the plate pressing. The metal band 100 is bent by the edge band rolls 34 and 32 along both ends of the edge band R of the edge band roll and then is wound on the large diameter side rolls 42 and 44 of the large diameter roll stand 40. [ As shown in Fig. Thereafter, the precision of the position of the abutting position of the edge portion of the metal band 100 is increased by the pin roll 80, and the metal band 100 is supplied to the squeeze roll stand 50, Welded. Through these steps, the metal tube 70 is manufactured from the metal base 100. Reference numeral 60 denotes a pulling-out device.

4, the edge band roll stand 30 includes a pair of upper and lower rolls, that is, a first edge band roll 32 having a concave groove with a side end R attached to one edge band roll And a second edge band roll 34 having convex rods to which side edges R are attached to the other edge band rolls.

The metal band 100 is supplied to the edge band roll stand 30 so that both edge portions of the metal band 100 are curved along the side edge R of the edge band roll. Further, the metal band 100 is supplied to the large-diameter side roll stand 40 (see Figs. 1 and 5), and is formed into a cylindrical shape.

The forming of the metal base 100 in the large diameter side rolls 42 and 44 into a cylindrical shape is carried out in such a manner that the metal base 100 after being fed to the edge band roll is paired with a pair of large diameter side rolls 42, (See Fig. 6). Here, a gap (see P in Fig. 7) is formed between one large-diameter side roll (first large-diameter sidewall roll 42) and the other one large-diameter sidewall roll (second large diameter sidewall roll 44) . When the metal base 100 is subjected to the pressure from the large-diameter side rolls 42 and 44, a part of the metal base 100 escapes to the gap P and a problem arises in the shape of the cylinder to be molded (See Fig. 7).

In order to prevent a part of the metal band 100 from escaping, a so-called " receiving part " is formed at the position of the gap P formed between the first large-diameter side roll 42 and the second large- .

The "receiving portion" will be described with reference to FIG. The first large-diameter side roll 42 and the second large-diameter side roll 44 are slit so that a slope of about 30 degrees is formed from the outermost side in the radial direction to the inner side at either one of the both ends in the axial direction. More specifically, as shown in Fig. 8, in order to form a slope of about 30 degrees from the outermost side in the radial direction to the back side of the metal of the first large-diameter sidewall 42 (that is, Side) of the second large-diameter sidewall roll 44 (that is, the lower side of the paper sheet of Fig. 8) is formed to have an inclination of about 30 degrees from the outermost side in the radial direction Sloped to form a slope. Bottom rolls 90 are disposed between two large-diameter side rolls 42, 44 which are inclined as described above (see Fig. 8 (A)). This bottom roll 90 becomes a " receiving portion ". By arranging the bottom roll 90 in the large-diameter side roll stand 40, it is preferable to adopt a three-roll method.

The arrangement of the bottom roll 90 will be described with reference to Figs. 9 and 10. Fig. The center line O 'of the bottom roll 90 is divided into a line O (hereinafter, referred to as "orthogonal line O") which is substantially perpendicular to the rotation axes of the first and second large-diameter side rolls 42, 44, (Refer to Fig. 9), problems may arise when the metal base 100 is formed into a cylindrical shape. This is presumably because, when the orthogonal line O and the center line O 'of the bottom roll 90 are in agreement, the entire circumference of the metal band 100 is restrained in the circumferential direction, resulting in excessive deformation .

In the state where the orthogonal line O of the large-diameter side rolls 42 and 44 and the center line O 'of the bottom roll are aligned, as described above, the metal band 100 is sandwiched between the two large-diameter side rolls 42, There is a possibility that the bottom portion of the metal band 100 slips downward and is bent before being fed to the bottom roll 90 after being supplied to the bottom roll 90. [ Then, the bottom portion of the bent metal band 100 is supported by the bottom roll 90, and then lifted and bent or bent back. As a result, it is presumed that a problem occurs due to excessive deformation of the metal base 100.

Therefore, in the present invention, the bottom roll is disposed on the opposite side of the advancing direction (the advancing direction X of the manufacturing line) of the metal band 100 (that is, On the upstream side of the production line) (see Q in Fig. 10). As a result, the entire circumference of the metal band 100 is not constrained but the length of the run is reduced, and unnecessary deformation due to bending or bending is reduced, so that the amount of deformation can be greatly reduced. This greatly improves the shape and quality of the formed metal base 100.

An edge portion of the metal base 100 formed into a cylindrical shape is abutted and welded, whereby a metal tube is manufactured. As shown in Fig. 3, the metal part 100 formed into a cylindrical shape is held in the squeeze roll stand 50, and the edge part is abutted and welded by the welder 120. As shown in Fig. The welding method preferably employs a laser welding method in view of productivity and workability of the produced welded metal pipe.

The welding method is not limited to the laser welding method, and may be an arc welding method such as a tig welding method, a plasma welding method, or other high frequency welding method.

It is preferable that not only the laser welding but also the welding of the edge portions of the metal band 100 are performed by aligning the abutted portions with a high accuracy and aligning the abutting portions along the progressive direction X of the production line. In order to increase the positioning accuracy of the abutted position, in the present invention, in the large-diameter side roll stand 40, the first pin roll 80 is added to the bottom side roll 90 in addition to the bottom roll 90, (See Fig. 11).

However, even if the pin roll 80 is provided on the metal surface side of the large diameter side rolls 42 and 44 (that is, just above the large diameter side roll on the paper surface of Fig. 11) to roll the metal pipe (see Fig. 11) There is a case where after the forming in the large diameter side rolls 42 and 44, the metal band 100 is twisted in the circumferential direction until it is conveyed to the squeeze roll stand 50, causing a problem in welding See Fig. 12). This is because the deviation of the centering position of the steel strip and the deviation of the roll center such as the large diameter side roll or the squeeze roll when the metal strip 100 as a material is fed into the production line do. However, it is not practical to manually adjust such a shift by the difficulty, leading to an increase in cost.

11, the first pin roll 80 is provided not only on the metal base surface side of the large-diameter side rolls 42 and 44 but also on the metal base 100 The second pin roll 82 is provided on the side opposite to the metal large side with respect to the squeeze roll (that is, on the upper side of the squeeze roll) immediately before being fed to the squeeze roll stand 50.

That is, by using the two pinrols 80 and 82 at the same time, the abutting position of the edge portion can be determined with high precision in two places along the moving direction X of the production line, and thus the state in which the butt portion extends straight is secured . As a result, more stable continuous welding becomes possible.

Further, when the metal band 100 is continuously rolled, the deformation applied to each part of the steel strip is not the same, and is biased by various factors. As a result, the shape of the edge portion of the metal base 100 becomes unstable, and a step is liable to occur at the butted position of the edge portion. Even if the step difference does not occur, for example, as shown in Fig. 15, it is likely that a bad contact of the edge portion occurs, which makes it difficult to perform welding.

This phenomenon occurs remarkably as the diameter of the metal tube to be produced becomes smaller. That is, as shown in Fig. 14, when the diameter of the metal pipe to be manufactured is relatively large (see Fig. 14 (A)), the shape of the butt of the edge portion 110a and the edge portion 110b is I-shaped (Refer to Fig. 14 (B)), it is possible to perform welding with no problem. However, when the diameter of the metal tube to be manufactured becomes small (see Fig. 15 (A)), as shown in Fig. 15 (B), the shape of the abutting position of the edge portion 110c and the edge portion 110d is V- , Which causes welding failure.

Therefore, in the present invention, it is also possible that the second fin roll (the second fin roll) is provided on the side opposite to the metal band 100 side (that is, the upper side of the squeeze roll) with respect to the squeeze roll, just before the steel strip is supplied to the squeeze roll stand 50 82) (see Fig. 16). Specifically, the second pinrol 82 is provided with a pin 82a and a pressing surface 88 having a shape having a radius of curvature larger than that of the metal pipe to be manufactured. By using the second pin roll 82, the pin can accurately position the position of the abutted portion at a desired position for the next welding, and presses the edge portion of the metal base 100 by the concave surface, Can be corrected.

(Example)

Example 1;

An example of manufacturing a metal tube with an outer diameter of Φ6.5 mm (Φ ₁ ) using a ferritic stainless steel plate having a composition of 18 Cr-1Mo-Ti-low carbon low-grade and having a plate thickness of 0.5 mm is described.

The production line described in Fig. 3 was used. As the edge band roll, a roll having a shape shown in Fig. 4 was used. The large diameter side rolls 42 and 44 were of the shape shown in Figs. 5 and 7 (? ₂ = 300 mm, outer diameter ratio? ₂ /? ₁ = 46). The bottom roll has an outer diameter of 62 mm and the offset Q of the large diameter side roll is 0 mm in the upstream direction of the production line and 12 mm, 18 mm and 20 mm. The pinch rolls are arranged such that the first pinrol 80 is disposed on the metal surface side of the large diameter side rolls 42 and 44 (that is, on the upper side of the large diameter side rolls 42 and 44) Is not disposed at the position immediately before the squeeze roll stand 50. [

The material was passed through a plate under the condition that the line speed was 4 m / min, and a metal tube was manufactured by fiber laser welding on a squeeze roll at a power of about 900 W and a beam diameter of 0.6 mm. No lubricant was used. As a result, when the offset Q was 0 mm, scratches were recognized on the outer surface of the obtained metal tube, and roundness was also poor. On the other hand, when the offset is set, a metal tube with good roundness can be manufactured without any damage to the outer surface at any offset amount.

Example 2:

Next, an example of manufacturing a metal pipe having an outer diameter of Φ3.7 mm (Φ ₁ ) using a ferritic stainless steel plate having a composition of 16.5 Cr-Ti-low carbon low-grade nitrogen and having a plate thickness of 0.3 mm is described.

The production line described in Fig. 3 was used. An edge band roll having a diameter of 100 mm was used. The large diameter side rolls 42 and 44 were used when the Φ ₂ was 100 mm and when the 300 mm was used. The external ratio (? ₂ /? ₁ ) is 27 and 81, respectively. The offset Q is set to be 0 mm on the upstream side of the advancing direction of the metal band 100 with reference to the orthogonal line O of the large diameter side rolls 42 and 44 by using a bottom roll having an outer diameter of 62 mm , 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 18 mm and 20 mm. A line speed of 4 m / min, a fiber laser output of about 500 W, and a beam diameter of 0.6 mm. No lubricant was used.

The first pin roll 80 is disposed on the upper side of the large diameter side rolls 42 and 44 and the second pin roll 82 is not disposed on the position immediately before the squeeze roll stand 50. [ As a result, in the case of Fig. 81, when the external ratio (PH ₂ / PHI ₁ ) was 27, when the offset Q was 0 mm, the outer surface of the obtained metal tube was scratched and the roundness was also poor. When the offset (Q) was set, a metal pipe with good roundness was produced without any external damage in any offset amount.

Example 3:

In addition, an example of manufacturing a metal pipe having an outer diameter of? 6.5 mm (? ₁ ) using a ferritic stainless steel plate having a composition of 16.5 Cr-Ti-low carbon low-

The production line, the edge band roll, the large diameter side rolls 42 and 44, and the bottom roll were the same as those used in the first embodiment. That is, the external ratio (? ₂ /? ₁ ) is 46.

In this third embodiment, the offset Q of the bottom roll is set at 0 mm on the upstream side in the advancing direction of the metal band 100 with reference to the orthogonal line O of the large-diameter side rolls 42, , 5 mm, 7 mm, 10 mm, 12 mm, 15 mm, 18 mm and 20 mm. In any case, the pin roll 80 is disposed on the upper side of the large diameter side rolls 42 and 44, and in the third embodiment, just before the squeeze roll stand 50, The fin roll 82 is also provided on the side opposite to the squeeze roll side (i.e., the upper side of the squeeze roll). The pin roll 82 immediately above the squeeze roll stand 50 has two types of curvature radii of 5 mm and 10 mm. As a result, a total of 16 kinds of metal pipes were produced. No lubricant was used.

Then, under the condition that the line speed was 10 m / min, the material was passed through the material strip, and fiber laser welding was performed on a squeeze roll under the condition of an output of about 1500 W and a beam diameter of 0.6 mm.

In each of the above manufacturing conditions, when the offset Q was 0 mm, scratches were recognized on the outer surface of the obtained metal tube, and roundness was also poor. When the offset (Q) was set, a metal pipe with good roundness was produced without any external damage in any offset amount.

Example 4;

Similarly, a metal tube having an outer diameter of? 6.5 mm (? ₁ ) was manufactured from a material obtained by subjecting a ferritic stainless steel plate having a composition of 16.5 Cr-Ti-low carbon low- .

The same manufacturing line, edge band roll, large diameter side roll and bottom roll as those used in Example 1 were used. That is, the external ratio (Φ ₂ / Φ ₁ ) is 46.

In the fourth embodiment, the offset Q of the bottom roll is set to be 3 mm on the upstream side in the advancing direction of the metal band 100 with reference to the orthogonal line O of the large-diameter side rolls 42, , 5 mm, 7 mm, 10 mm, and 15 mm. The pin rolls are provided only on the upper side of the large-diameter side rolls 42, 44 and not on the upper side just before the squeeze roll stand 50.

Fiber laser welding was performed at a line speed of 2 m / min, an output of about 580 W on a squeeze roll, and a beam diameter of 0.6 mm.

As a result, the aluminum-plated stainless steel strip was used as a material band, and a metal tube of good roundness was produced without any scratches on the outer surface in any offset amount under the above manufacturing conditions.

10: Press the plate
20: Guide
30: Edge band roll stand
32: first edge band roll
34: 2nd edge band roll
40: Large diameter side roll stand
42: First large-diameter side roll
42a: groove portion of the first large-diameter side roll
44: second large diameter side roll
44a: groove portion of the second large-diameter side roll
50: Squeeze roll stand
60: extraction device
70: metal tube
70a: Large diameter metal tube
70b: a small-diameter metal pipe
80: First pin roll
82: second pin-roll
82a: pin
88: Pressure face
90: bottom roll
100: metal stand
110a: edge portion
110b: edge portion
110c: edge portion
110d: edge portion
120: welding apparatus
O: orthogonal line
O ': center line of the bottom roll
P: Clearance between two large diameter side rolls
Q: Offset
X: Direction of production line

Claims (16)

The roll stand arranged in the metal tube outer diameter (Φ ₁₎ and the diameter (Φ ₂₎ the outer guard (Φ ₂ / Φ ₁₎ is at least 10 one pairs of the large-diameter-side roll and the bottom roll 3 bangrol method of at least of the rolls to be produced A method of manufacturing a metal pipe,
The pair of large-diameter side rolls comprise at least a first large-diameter side roll and a second large-diameter side roll disposed opposite to the first large-diameter side roll,
The bottom roll is offset in the inlet side direction of the roll stand with reference to a straight line connecting the rotation axis of the first large diameter side roll and the rotation axis of the second large diameter side roll,
Wherein a metal band is supplied to the roll stand, and after the metal band is formed into a cylindrical shape, an edge portion of the metal band is welded. The roll stand arranged in the metal tube outer diameter (Φ ₁₎ and the diameter (Φ ₂₎ the outer guard (Φ ₂ / Φ ₁₎ is at least 10 one pairs of the large-diameter-side roll and the bottom roll 3 bangrol method of at least of the rolls to be produced In the apparatus for manufacturing a metal pipe,
The pair of large-diameter side rolls comprise at least a first large-diameter side roll and a second large-diameter side roll disposed opposite to the first large-diameter side roll,
The bottom roll is offset in the inlet side direction of the roll stand with reference to a straight line connecting the rotation axis of the first large diameter side roll and the rotation axis of the second large diameter side roll,
And a squeeze roll and a welding machine are further provided on the downstream side of the large diameter side roll. delete delete delete delete delete delete delete delete delete delete delete delete delete delete

Images