JP2790887B2 - Manufacturing method of metal welded pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a metal plate continuously into a tubular shape and welding the butted two side edges of the metal plate to mainly obtain a thickness t and an outer diameter D. When manufacturing a metal welded pipe having a ratio t / D of 3 to 20%, a flat metal plate is formed into a tubular shape by passing a flat metal plate through a through hole formed in a die. The present invention relates to a method for manufacturing a metal welded pipe.

[Conventional technology]

In order to manufacture a metal tube by bending a metal plate to a product curvature in the width direction thereof to form a tube, conventionally, a forming roll or a cage having a large number of calipers arranged in tandem as shown in a perspective view in FIG. Using a roll forming machine equipped with a roll 10, the metal plate 1 is sequentially bent in the width direction to be formed into a tube, and the metal plate 1 formed into a tube is subjected to a seam guide roll.
11 and the metal plate 1 held by the squeeze roll 5
The roll forming method of manufacturing by a continuous line in which butted portions 1b of both side edges 1a are joined by butt welding has been generally practiced.

However, in such a conventional method, for example, when manufacturing a metal welded pipe having a ratio t / D of the thickness t to the outer diameter D of 3 to 20%, the outer diameter of the metal pipe to be manufactured is changed. The forming roll or cage roll 10,
Furthermore, since the roll set such as the seam guide roll 11 and the squeeze roll 5 must be replaced with each roll set having desired dimensions corresponding to the outer diameter of the metal pipe to be manufactured,
Since there are at least 20 or more sets of rolls for one type of outer diameter, a large amount of labor and a long time are required to replace the rolls, which reduces the production efficiency of the equipment. There is a disadvantage that it is not economical since each roll set having a desired size corresponding to the diameter must be prepared.

Furthermore, when manufacturing a thin metal tube having an outer diameter of 10 mm or less, extremely high accuracy is required in the installation position of each roll set, the interval between the rolls facing each roll, the dimensions of the rolls in each roll set, and the like. For example, in each set of opposing rolls, it is necessary to set the positions of the opposing rolls at the same time as the front and rear and up and down with respect to the passing direction of the metal plate 1 at the same time. It is easy to install with the eccentric position slightly deviated from the position, especially when the outer diameter of the metal tube to be manufactured is small and the thickness of the metal plate 1 is very thin, the opposing roll is installed with the eccentricity slightly. Then, a step is formed at the butting portion 1b of both side edges 1a of the metal plate 1 formed into a tubular shape by the roll, and the butting portion 1b having the step is welded. The cross-sectional shape of the formed metal tube does not form a perfect circle, resulting in a defect on the product.

[Problems to be solved by the invention]

The present invention can easily and inexpensively cope with a change in the outer diameter of a metal pipe to be manufactured having a ratio t / D of the wall thickness t to the outer diameter D of 3 to 20% by solving the above-mentioned disadvantages of the prior art. It is an object of the present invention to provide a method for manufacturing a metal tube which can be manufactured particularly easily and inexpensively and inexpensively with a thin metal tube having an outer diameter of 10 mm or less.

[Means for solving the problem]

The present inventors have conducted various studies to solve this problem, and as a result, have found that a die having a through-hole having a circular cross section having a tapered portion whose diameter decreases from the entry side to the exit side is formed. The metal plate is formed into a tubular shape in which both side edges are abutted at once by penetrating a metal plate into the through hole of the metal welded tube to be manufactured. Ratio of wall thickness t to outer diameter D
When t / D is 3 to 20%, the metal plate to be penetrated into the through hole of the die is 1.01 of the thickness center line length of the metal welded pipe.
If a metal plate with a width of ~ 1.35 times is used, a flat metal plate can be formed into a tubular shape with its side edges abutted at once without using a large number of rolls to gradually form the tube. The present invention was completed by investigating that it is possible to manufacture a metal welded pipe having a good cross-sectional shape by welding butted portions of both side edges of the metal plate.

Hereinafter, a method for manufacturing a metal welded pipe according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory side view showing a state in which a metal welded pipe is manufactured by the method of the present invention, FIG. 2 is an explanatory front view showing an example of the die shown in FIG. 1, and FIG. A in Figure 2
FIG. 4 is a sectional view taken along the line A, FIG. 4 is a view showing another embodiment of manufacturing the metal welded pipe by the method of the present invention, FIG. 5 is a sectional view taken along the line BB in FIG. 4, and FIG. (A), (b) and (c) show various cross-sectional shapes of the metal plate immediately after passing through the through hole of the die, and FIG. 7 shows a method of manufacturing a stainless steel welded pipe having a diameter of 10 mm by the present invention. FIG. 4 is a diagram showing the relationship between the material width and the thickness / diameter at that time.

In order to carry out the method of the present invention, first, a circular section having a tapered portion whose diameter decreases in the direction of travel of the metal plate 1 for manufacturing a metal welded pipe, that is, from the entry side to the exit side. Dice 2 with through holes 3
Prepare That is, the flat metal plate 1 is penetrated into the through hole 3 from the entrance side having a larger diameter to the exit side having a smaller diameter than the entrance side through a tapered portion from the entrance side, so that both side edges thereof are formed at once. A die 2 for forming a tube in a state where 1a is abutted is prepared. The metal plate 1 to be formed into a tubular shape is not limited to a normal cold-rolled metal plate, but also a metal plate having at least one surface subjected to polishing such as mirror polishing or hairline polishing, or at least one surface having been subjected to etching or chemical coloring. A metal plate that has been subjected to surface treatment such as processing, ceramic coating, plating, and painting can be used.

As shown in FIG. 1, such a metal plate 1 is passed through a through-hole 3 having a circular cross section having a tapered portion whose diameter decreases as going from the entry side to the exit side of the die 2.
It is formed into a tubular shape with its side edges 1a abutting at once. At this time, although the thickness differs depending on the outer diameter and the material of the metal welded pipe to be manufactured, when the thickness of the metal plate 1 is 3 to 20% of the outer diameter of the metal welded pipe to be manufactured, the material width is reduced. Is too narrow, the internal pressure due to the circumferential compression force is insufficient,
Since the material is not sufficiently filled therein, the deformation near the side edges 1a is insufficient as shown in FIG. Since the metal plate 1 formed as described above may cause a phenomenon such as meandering and twisting, the metal plate 1 preferably has a plate width of 1.01 times or more the length of the center line of the thickness of the metal welded pipe to be manufactured. When the width of the metal plate 1 is large with respect to the thickness center line of the metal tube to be manufactured, the metal plate 1 abuts the both side edges 1a in the middle of the tapered portion when being drawn into the die 2. While being formed into a tubular shape, it is subjected to a compressive stress in the circumferential direction by the taper of the die 2 and a tensile stress in the longitudinal direction, and contracts in the circumferential direction to expand in the longitudinal direction. If the width is too wide, the compressive stress in the circumferential direction is too large and buckling may occur near both side edges 1a of the metal plate 1 as shown in FIG. It is desirable to use a metal plate 1 having a plate width of 1.35 times or less the length of the thick center line. Here, the thickness center line of the metal weld pipe is a circumferential line passing through the center of the thickness of the metal weld pipe, and the length is the length of the thickness center line = (outside diameter of product−thickness). X Pi =
It is expressed by (minimum inside diameter of die through hole-wall thickness) x pi. The occurrence of such a phenomenon is shown in FIG. 7 by using a stainless steel die of various thicknesses made of carbon tool steel SKD-11 and having pierced holes with an inlet diameter of 35 mm, an outlet diameter of 10 mm, and a taper angle of 22 °. As shown in the figure, the result of TIG welding the butt portion of both side edges of the stainless steel band in a state where the band (SUS304) is formed into a tubular shape by penetrating the through hole using a solid lubricant and then held in a tubular shape by a squeeze roll. If the thickness of the metal plate 1 is less than 3% of the outer diameter of the metal welded pipe to be manufactured, the thickness of the metal plate 1 is too small, and the side edges 1a of the metal plate 1 are staggered due to the circumferential compressive force. When the thickness of the metal plate 1 exceeds 20% of the outer diameter of the metal welded pipe to be manufactured, the thickness of the metal plate 1 increases. Too large a pulling force causes the metal plate 1 to break at the die exit side or cause the metal plate 1 to break. Both side edges
It has been confirmed that the vicinity of 1a does not bend sufficiently and a phenomenon that it cannot be formed into a perfect circular shape occurs. As described above, when the sheet width is in the range of 1.01 to 1.35 times the length of the center line of the thickness of the metal welded pipe, a metal welded pipe having a good shape can be manufactured, but the occurrence of surface flaws is completely prevented. In this case, it is preferable that the plate width is in the range of 1.01 to 1.20 times the length of the center line of the thickness of the metal welded pipe.

When such a metal plate 1 is passed through the through hole 3 of the die 2, the metal plate 1, which has been subjected to plastic bending with a small-diameter bending roll 8 perpendicular to the longitudinal direction with the inner surface of the pipe as the inner side, When the metal plate 1 is flat on a flat surface when the metal plate 1 is projected onto a plane by utilizing the residual curvature in the width direction caused by plastic bending / bending back by setting the curvature in the direction to zero. It is desirable to penetrate the through-hole 3 of the die 2 in a state where it is bent in the width direction so as to be smaller than the width, so that it can be reliably formed into a tubular shape. For example, as shown in FIG. 4, the entrance-side cylindrical roll 9 and the axis thereof are arranged with a gap provided between the entrance-side cylindrical roll 9 and the entrance-side cylindrical roll 9 in parallel with the entrance-side cylindrical roll 9. A cylindrical roll 9 on the output side, which rotates in the same direction as the cylindrical roll 9 on the side, and a small-diameter bending roll 8 which is disposed in close proximity to these cylindrical rolls 9, 9 and parallel to the axis of the cylindrical roll 9; Roll group consisting of
First, the metal plate 1 is moved along the cylindrical roll 9 on the entry side, then passed through the gap, then bent along the small-diameter bending roll 8, and then again passed through the gap to make the longitudinal curvature zero. Utilizing the residual curvature in the width direction generated by the plastic bending / unbending, the metal plate 1 was bent in the width direction so that the plate width when projected onto a plane was smaller than the width when the metal plate 1 was flat. In this state, it is made to penetrate through the through hole 3 of the die 2.

In this way, the diameter of the entry side of the through hole 3 of the die 2 through which the metal plate 1 penetrates is preferably made larger than the width of the metal plate 1, but inside the tube as shown in FIG. Small-diameter bending roll 8 perpendicular to the longitudinal direction with the surface inside
When the metal plate 1 that has been subjected to the plastic bending process is penetrated by
As shown in the figure, the metal plate 1 is already bent at the entry side of the through hole 3 and the plate width when projected on a plane is smaller than the actual plate width. 3
It is sufficient that the metal plate 1 has a diameter larger than the plate width when the metal plate 1 on the entry side is projected onto a plane. 1 and 3
As shown in the drawing, the same diameter section 3a having the same diameter is provided in the through hole 3 of the die 2 from the middle of the entry side and the exit side to the exit side, and both sides of the metal plate 1 in the same diameter section 3a. edge
It is preferable to perform plastic bending on the tube by maintaining the state where the tube 1a is formed in abutted shape.

In this way, the flat metal plate 1 is formed into a tubular shape with its both side edges 1a abutted at once, and the butted portion 1b of the both side edges 1a is welded. As shown in FIG. 1, an arc welding torch is formed by joining a butt portion 1b in which both side edges 1a are butted while a tubular metal plate 1 is held in a tubular shape by a squeeze roll 5 through a through hole 3 of a die 2. 4 or penetrates from the outer peripheral edge of the die 2 toward the same diameter section 3a of the die 2 corresponding to the butted portion 1b of the tubular metal plate 1 as shown in FIG. A through hole 7 for welding is formed, and a laser is radiated from a laser irradiator 6 for laser welding to a butt portion 1b on both side edges 1a of the metal plate 1 through the through hole 7 for laser welding. Can also As a means for welding, the metal plate 1 formed into a tubular shape by penetrating the through hole 3 of the above-mentioned die 2 is held in a tubular shape by a squeeze roll 5, butted portions 1 b of both side edges 1 a of the metal plate 1. It is needless to say that laser welding may be adopted as a means for welding the steel.

(Operation)

As described above, the method for manufacturing a metal welded pipe according to the present invention includes:
Since the metal plate 1 is made to pass through a die 2 having a circular through-hole 3 having a tapered portion whose diameter decreases as going from the entrance side to the exit side.
The metal plate 1 is bent along the tapered portion of the through hole 3 and is stretched in the longitudinal direction in the process of penetrating the metal plate 1, so that the flat metal plate 1 only needs to be passed through the through hole 3 of the die 2. It can be formed into a tube having the same outer diameter as the diameter of the through hole on the outlet side at a stroke.

When the metal plate 1 is passed through the through hole 3 of the die 2, the metal plate 1 is subjected to plastic bending with a small-diameter bending roll 8 perpendicular to the longitudinal direction with the surface inside the pipe as the inside, and then the metal plate 1 This plastic bending
The die 2 is bent in the width direction so that the width of the metal plate 1 projected on a plane is smaller than the width of the flat metal plate 1 due to the residual curvature in the width direction caused by the bending back. If the metal plate 1 is formed into a tubular shape along the tapered portion of the through hole 3, the stress acting on the die 2 can be reduced by penetrating the through hole 3.

Further, the same diameter section 3a having the same diameter is provided between the entrance and the exit side of the through hole 3 of the die 2 and the exit side, and both side edges 1a of the metal plate 1 are formed in the same diameter section 3a. The through-hole 3 is maintained by maintaining the
, The spring back generated in the tubular metal plate 1 can be reduced. A welding through-hole 7 is formed to penetrate from the outer peripheral edge of the die 2 toward the same diameter section 3a of the die 2, corresponding to the butted portion 1b of the metal plate 1 formed in a tubular shape. When the butt portion 1b of the metal plate 1 is laser-welded by irradiating a laser beam through the through-hole, the welded tubular metal plate 1 is maintained in a circular cross section having the outer diameter of the metal tube to be manufactured up to the exit side. Spring back after passing through the through hole 3 is reliably suppressed.

As described above, according to the method of the present invention, the metal plate 1 is penetrated through the through hole 3 having a circular cross section of the die 2, so that the metal plate 1 can be accurately butted on both side edges 1 a without generating a step. It is possible to manufacture a metal welded pipe having a simple cross-sectional shape.

〔Example〕

Example 1 A die made of carbon tool steel SK5 has an inlet diameter of 35 mm and an outlet diameter of 10
mm, a through hole with a taper angle of 22 °, plate thickness 1 mm, plate width 31 m
m austenitic stainless steel strip (SUS30
4) After passing through the through hole to form a tube, the butt portion of both side edges of the stainless steel strip is TIG-welded while being held in a tubular shape by a squeeze roll. As a result, the cross-sectional shape is almost a perfect circle. A stainless steel welded pipe with a thickness of 1 mm and an outer diameter of 10 mm could be manufactured.

Example 2 A diameter of 4.0 mm and a diameter of the outgoing side of a die made of carbon tool steel SK5
A through hole with a diameter of 1.0 mm and a taper angle of 30 ° was drilled, and a through hole for welding with a diameter of 0.5 mm was drilled in the same diameter section with a length of 3.0 mm as shown in FIG. A flat austenitic stainless steel strip (SUS304) with a width of 3.3 mm is penetrated into the through hole to form a tube, and then the laser irradiator uses the welding through hole to butt the butt on both sides of the stainless steel strip.
As a result of irradiating a G (yttrium aluminum garnet) laser and performing welding, a stainless steel welded pipe with a perfect circular cross section and a good weld condition of 0.1 mm in thickness and 1.0 mm in outer diameter can be manufactured. Was.

Example 3 A die made of carbon tool steel SK5 has an inlet diameter of 35 mm and an outlet diameter of 10
mm, a through hole with a taper angle of 22 °, plate thickness 1 mm, plate width 31 m
m austenitic stainless steel strip (SUS30
4) Perform a plastic bending process with a small-diameter bending roll with a radius of 7 mm perpendicular to the longitudinal direction with the inside surface of the pipe as the inside, and then reduce the longitudinal curvature to zero, thereby performing plastic bending and unbending. Utilizing the resulting residual curvature in the width direction, the steel sheet is formed into a tubular shape by penetrating through the through-hole in a state of being bent to some extent in the width direction, and then butted against both side edges of the stainless steel strip while being held in a tubular shape by a squeeze roll. As a result of TIG welding of the part, the cross-sectional shape is almost a perfect circle, the thickness is 1 mm, the outer diameter
A 10mm stainless steel welded pipe could be manufactured.

〔The invention's effect〕

As described in detail above, when a metal welded pipe is manufactured by the method for manufacturing a metal welded pipe according to the present invention, the through hole formed in the die has a through-hole of 1.01 to 1.35 times the length of the center line of the thickness of the metal welded pipe. A simple method of penetrating a flat metal plate having a width of 3 mm does not cause a phenomenon that meandering or twisting occurs in the manufactured metal welded pipe, and the metal edges of the metal plate overlap with both side edges. The flat metal plate can be formed into a tube having a good cross-sectional shape at once without causing wrinkles due to buckling near both side edges of the plate.
It is only necessary to prepare one die corresponding to the outer diameter of the metal welded pipe to be manufactured, in which the ratio t / D of the outer diameter D to the outer diameter D is 3 to 20%, so the outer diameter of the metal pipe to be manufactured is changed. In this case, the dies can be changed easily in a short time, and it is economical.

Furthermore, since the metal plate that has passed through the through-hole of the die is formed in a tubular shape with its both side edges firmly abutting, it is possible to easily carry out high-mix low-volume production and supply high-quality products. be able to.

When the same diameter section is provided in the through hole of the die, the spring back generated in the metal plate after penetrating the through hole is suppressed, and when the welding through hole is formed in the same diameter section, the same diameter is provided. Since the butt portion of the metal plate can be welded in the diameter section, a good quality product can be supplied.

Laser welding of the butted portion can form a good weld by adjusting the laser output suitable for the material and width of the metal plate, etc., so even a thin metal welded pipe of several mm or less can be formed. It can be easily manufactured.

The metal welding method according to the present invention having various advantages as described above makes it possible to produce a metal welded pipe at a low cost and easily, and even to manufacture a metal pipe having a very small diameter. It is very big.

[Brief description of the drawings]

FIG. 1 is an explanatory side view showing a state in which a metal welded pipe is manufactured by the method of the present invention, FIG. 2 is an explanatory front view showing an example of the die shown in FIG. 1, and FIG. A- in FIG.
FIG. 4 is a sectional view taken along line A, FIG. 4 is a view showing another embodiment of manufacturing a metal welded pipe by the method of the present invention, FIG. 5 is a sectional view taken along line BB in FIG. 4, FIG. B), b) and c)
FIG. 7 shows various cross-sectional shapes of a metal plate immediately after passing through a through hole of a die. FIG. 7 shows the relationship between the material steel and the thickness / diameter when a stainless steel welded pipe having a diameter of 10 mm is manufactured by the method of the present invention. FIG. 8 is a perspective view showing a state in which a metal welded pipe is manufactured by a conventional method. In the drawings: 1 ... metal plate 1a ... side edge 1b ... butted portion 2 ... die 3 ... through hole 3a ... same diameter section 4 ... arc welding torch 5 ... squeeze roll 6 ... laser irradiation machine 7: Through-hole for welding 8: Bending roll of small diameter 9: Cylindrical roll 10: Forming roll or cage roll 11: Gemm guide roll

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akinobu Takezoe 1 Tsurucho, Amagasaki-shi, Hyogo Nisshin Steel Co., Ltd. Inside the Processing Technology Center (56) References JP-A-60-44126 (JP, A) JP-A-55 -22442 (JP, A) Jiko 40-4042 (JP, Y1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21C 37/08 B21D 5/06-5/12

Claims (5)

(57) [Claims] 1. A metal plate (1) is provided on a die (2) having a through-hole (3) having a circular cross section and having a tapered portion that decreases in diameter from the entry side to the exit side. Is formed into a tubular shape in which both side edges (1a) are abutted at once at a time, and this abutting portion (1b)
When a metal welded pipe is manufactured by welding a metal to a pipe, when the ratio t / D between the thickness t and the outer diameter D of the metal welded pipe to be manufactured is 3 to 20%, the through hole ( 3) As the metal plate (1) to penetrate, the length of the thickness center line of the metal welded pipe is 1.01 to
A method for producing a metal welded pipe, comprising using a metal plate (1) having a plate width 1.35 times as large as that of a metal tube. 2. The same diameter section (3a) having the same diameter is provided in the through hole (3) of the die (2) between the middle of the entrance side and the exit side to the exit side. 2. The method for manufacturing a metal welded pipe according to claim 1, wherein the state in which the side edges (1a) of the metal plate (1) are formed into a tubular shape in abutting manner in (3a) is maintained. 3. Both side edges (1) of a tubular metal plate (1).
The method for manufacturing a metal welded pipe according to claim 1 or 2, wherein the butted portion (1b) of a) is laser-welded. 4. A welding penetrating from the outer peripheral edge of the die (2) to the same diameter section (3a) of the die (2) corresponding to the butted portion (1b) of the metal plate (1) formed in a tubular shape. The method for producing a metal welded pipe according to claim 3, wherein a through hole (7) for drilling is formed, and the butted portion (1b) is laser-welded by irradiating a laser from the through hole (7) for welding. 5. A metal plate (1) which has been subjected to plastic bending with a small-diameter bending roll (8) perpendicular to the longitudinal direction with the inside surface of the tube as the inside, by reducing the curvature in the longitudinal direction to zero. Thus, the width of the metal plate (1) when projected onto a plane using the residual curvature in the width direction caused by the plastic bending / unbending becomes smaller than the width when the metal plate (1) is flat. The method for producing a metal welded pipe according to any one of claims 1 to 4, wherein the metal pipe is penetrated through the through hole (3) of the die (2) in a state of being bent in the width direction.