JPH07102394B2 - Method for manufacturing thin-walled metal tube with excellent cross-sectional shape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a small thin metal tube such that the ratio (t / D) between the plate thickness t and the pipe outer diameter D is mainly 2% or less. The present invention relates to a method for producing a thin-walled metal tube having an excellent cross-sectional shape, which can be continuously produced into a shape having a good roundness.

[Prior Art] In order to manufacture a metal tube, a metal sheet is sequentially bent in the width direction by using a roll forming machine having a forming roll or a cage roll having calibers arranged in a large number of tandems. Then, a manufacturing method has been carried out by a continuous line in which butt portions of both side edges are joined by butt welding while the formed metal plate is held by a seam guide roll and a squeeze roll.

However, if an attempt is made to manufacture a thin-walled metal pipe by such a conventional method, the plate thickness t of the thin metal plate is determined by the pipe outer diameter D.
The radius of curvature of the product (R = D /
Since the thin metal plate cannot undergo sufficient plastic deformation until it is bent to 2), a large spring back is generated during the time when it leaves one roll and is caught by the next roll. There is a problem that it does not bend or edge waves are likely to occur due to large edge stretch.Especially when butt-welding both edges of a thin metal plate, the metal thin plate is not As shown in FIG. 8, there is a drawback in that the butted portion is held in an angled state and cannot be held in a state close to a perfect circle. If butt welding of both side edges of a thin metal plate is performed in such a state, the cross-sectional shape of the welded pipe deteriorates, and since this cross-section defect is local, it must be completely corrected even if it is corrected in a later process. There was a problem that it was difficult.

In addition, as for such a problem, the applicant first made a patent application
No. 224685 (Japanese Patent Laid-Open No. 2-75418), the thin metal plate is bent along the inlet side cylindrical roll, and the pipe is passed through the gear gap between the inlet side cylindrical roll and the outlet side cylindrical roll. Plastic bending with a small-diameter bending roll consisting of a floating roll that is orthogonal to the longitudinal direction with the inside surface as the inside, and then bending back to zero curvature in the longitudinal direction with the roll to perform plastic bending and bending back to the thin metal plate The epoch-making thin wall that is formed by bending the plastic thin plate that has been plastically bent / bent back into a tubular shape by bending it to the product curvature in the widthwise direction using the residual curvature in the widthwise direction caused by the plastic bending / bending back process. The same problem occurs when a thin metal tube is manufactured by the method for manufacturing a metal tube.

[Problems to be Solved by the Invention]

The present invention, when the thin-film metal tube is manufactured by the above-mentioned applicant's epoch-making method for manufacturing a thin-wall metal tube previously disclosed in Japanese Patent Application No. 63-224685 (JP-A-2-75418), A thin metal plate formed into a tubular shape is held in the squeeze roll with its abutting parts at an angle because the cross-sectional shape changes greatly due to the spring back when the abutting parts on both side edges are not welded. A thin metal with an excellent cross-sectional shape is eliminated by eliminating the drawback that a welded tube that cannot be held in a state close to a perfect circle and that has a bad cross-sectional shape in which both side edges of a thin metal plate are butt welded in such a state is produced. An object is to provide a method for manufacturing a pipe.

[Means for Solving the Problems]

As a result of various studies to solve such problems, the present inventors have found that a thin metal plate, which is a material for forming a thin metal tube, has a thin plate pressure and thus has a cross-sectional shape before and after a processing step. Paying attention to the characteristic that they are easily affected by, the cylindrical rollers of the input side and the output side that rotate in the same direction with their axes parallel to each other and provided with a gear between them, and these two rolls. Small diameter bending roll comprising a floating roll having a diameter greater than twice the thickness of the thin metal sheet bent from the gear and arranged in the vicinity of the cylindrical roll parallel to the axis of the cylindrical roll. A plastic group in which a metal thin plate is first passed along a cylindrical roll on the entrance side, then passed through the gear tape, and then bent along a small-diameter bending roll, and then passed through the gear tape. Bend , The plastic bending / bending back is caused by making the curvature in the longitudinal direction of the thin metal plate that has been plastically bent by a small-diameter bending roll orthogonal to the longitudinal direction with the inner surface of the pipe being the inner side. Utilizing the residual curvature in the width direction, the metal thin plate is bent to the product curvature in the width direction and continuously formed into a tubular shape, and then both side edges of the metal thin plate are butted by squeeze rolls and the butted portions are welded together to form a thin metal. When manufacturing a pipe, install a caliber roll or block that holds the cross-sectional shape of the metal sheet in a state close to the design value immediately after the squeeze roll's exit side that abuts both side edges of the metal sheet continuously formed into a tubular shape. Then, it was clarified that the cross-sectional shape of the butt-welded thin-walled metal tubes should be maintained in a perfect circle, and the present invention was completed.

Hereinafter, a method for manufacturing a thin human metal tube having an excellent cross-sectional shape according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side view showing an embodiment in which a thin metal tube is manufactured by the method of the present invention, and FIG. 2 is A-A in FIG.
Line enlarged sectional view, FIG. 3 is an enlarged sectional view taken along line BB in FIG. 1, FIG. 4 is an enlarged sectional view taken along line C-C in FIG. 1, and FIG. 5 is a thin-walled metal pipe according to the method of the present invention. FIG. 6 is a side view showing another embodiment of manufacturing the same, FIG. 6 is DD in FIG.
Line enlarged cross-sectional view, FIG. 7 is a graph showing the ratio of the difference between the maximum outer diameter and the minimum outer diameter of the thin-walled metal pipe manufactured with and without the method of the present invention divided by the average outer diameter. is there.

In the drawings, reference numeral 1 denotes a metal thin plate continuously formed into a tubular shape. As this metal thin plate 1, not only a normal cold rolled metal thin plate but also at least one surface is subjected to polishing treatment such as mirror polishing or hairline polishing. It is possible to use a metal thin plate that has been subjected to surface treatment, or at least one surface of which has been subjected to a surface treatment such as etching, chemical coloring, ceramic coating, plating or painting. In order to continuously form the thin metal plate 1 into a tubular shape, as shown in FIG. 1, after the plastic bending process is performed with a small-diameter bending roll 3 orthogonal to the longitudinal direction with the inner surface of the tube inside, By making the longitudinal curvature zero and utilizing the residual curvature in the width direction caused by the plastic bending and unbending, the product is bent in the width direction to the product curvature and formed into a tubular shape. The roll 6 and its axis are arranged in parallel with the inlet side cylindrical roll 6 and provided with a gap G between the inlet side cylindrical roll 6 and rotate in the same direction as the inlet side cylindrical roll 6. It has a diameter larger than the length obtained by subtracting twice the plate thickness of the thin metal plate 1 which is arranged in parallel to the axis of the cylindrical rolls 6, 7 close to the cylindrical roll 7 on the output side and bent from the gear G. With a small diameter bending roll 3 consisting of a floating roll The thin metal plate 1 is first passed along the cylindrical roll 6 on the entrance side, passed through the gear G, and then bent along the small-diameter bending roll 3 and then passed through the gear G again. This is the configuration. Reference numeral 8 denotes a roll for making the curvature in the longitudinal direction of the metal thin plate 1 which is subjected to the plastic bending process orthogonal to the longitudinal direction with the inside surface of the pipe being the inside by such a plastic bending device, and has a small diameter. The bending roll 3 performs a plastic bending process orthogonal to the longitudinal direction to change the traveling direction of the thin metal plate 1 drawn out through the gear G, and to bend back the thin metal plate 1 so that the longitudinal curvature is zero. Needed to do. Numeral 9 utilizes the residual curvature in the width direction of the metal sheet 1 which is produced by plastic bending / bending back by the plastic bending apparatus composed of the inlet and outlet side cylindrical rolls 6 and 7 and the small diameter floating roll 3 and the roll 8. Then, the seam guide rolls 10 for bending the widthwise direction to the product curvature so as to position the edges of the metal thin plate 1 formed into a tubular shape so as to be positioned immediately below the next welding torch, 10 are the seam guide rolls 9. A squeeze roll that abuts the edges of the metal thin plate 1 formed into a tubular shape, 11 is a welding torch that joins the edges of the metal sheet 1 formed into a tube at the position of the squeeze roll 10, and 12 is a squeeze roll 10. Is a caliber roll or block that keeps the cross-sectional shape of the thin-walled metal pipes butt-welded in a perfect circle immediately after the exit side, and 13 is a thin-walled metal in which the edges of the metal thin plates 1 are joined by a welding torch 11. It is a urethane rubber lining pinch roll to transfer the tube.

[Work]

When the thin metal plate 1 is passed through the apparatus having the structure as described above, the thin metal plate 1 is bent along the cylindrical roll 6 on the inlet side so that it is between the cylindrical roll 6 on the inlet side and the cylindrical roll 7 on the outlet side. Is bent plastically by a small-diameter bending roll 3 consisting of a floating roll which is orthogonal to the longitudinal direction with the surface to be the inside of the pipe passing through the gear G of G and is bent when leaving the cylindrical roll 7 on the exit side. In order to prevent the residual stress from being reduced by bending in the direction opposite to the processed direction, the line connecting the axial center of the inlet side cylindrical roll 6 and the axial center of the outlet side cylindrical roll 7 is The metal thin plate 1 is pulled out toward the exit side of the plastic bending apparatus in a state of being inclined forward by a certain angle larger than 0 ° to change the traveling direction of the metal thin plate 1 and to make the metal thin plate 1 have a longitudinal curvature of zero. Metal that passes through the roll 8 Plastic Bending-unbending is carried out in a plate 1. Thus, the metal thin plate 1 that has been plastically bent and unbent is
The residual curvature in the width direction generated by plastic bending / bending back processing is used to bend the product in the width direction into the product curvature and form a tubular shape.

The metal thin plate 1 formed into a tubular shape in this way has its end edge regulated by the seam guide roll 9,
After passing through 10, the both sides of the tubular thin metal plate 1 are welded to each other with a welding torch 11 and joined, and immediately after the squeeze roll 10 exits, a caliber roll or block 12
The cross-sectional shape of the thin-walled metal pipe butt-welded by is held in a perfect circle and then transferred and discharged by the urethane rubber lining pinch roll 13.

〔Example〕

In the device shown in FIG. ₁ , the distance between the center of rotation of the seam guide roll 9 closest to the squeeze roll 10 and the center of rotation of the squeeze roll 10 is l ₁ , the center of rotation of the caliber roll 12 and the rotation of the squeeze roll 10 are rotated. The distance from the axis center is l ₂ , the distance between the rotation axis center of the seam guide roll 9 closest to the squeeze roll 10 and the rotation axis center of the next seam guide roll 9 is l ₃ , each seam guide roll 9, squeeze roll The roll diameter of 10 and caliber roll 12 is D, and caliber roll
With 12 and without
A thin metal tube was manufactured by performing TIG welding at a current of 80 A while injecting 100% concentration of argon gas from TIG welding torch 11 at 5 m / min. Material at that time, tensile strength of material (T
S), Vickers hardness (Hv), pipe dimensions (wall thickness x diameter), etc. are shown in the table below. As a result, the ratio of the difference between the maximum outer diameter and the minimum outer diameter of the manufactured thin metal tube divided by the average outer diameter is as shown in FIG.
When 12 is used, the roundness of the cross section of the product is remarkably improved, and the improvement of the abutting condition of both side edges of the thin metal plate has made it possible to stabilize even high strength materials without melt-through or bead flicker. It is possible to perform the welding that has been done.

[Effects of the Invention] The method of manufacturing a thin-walled metal tube having an excellent cross-sectional shape according to the present invention described in detail above is disclosed by the present applicant in Japanese Patent Application No. 63-224685 (JP-A-2-75418). Bending the thin metal sheet along the inlet side cylindrical roll, and passing through the gear gap between the inlet side cylindrical roll and the outlet side cylindrical roll, the flow that is orthogonal to the longitudinal direction with the inside surface of the tube inside After performing plastic bending with a small-diameter bending roll consisting of a towing roll, bending is performed with a roll to make the longitudinal curvature zero, and plastic bending / bending back is performed on the metal thin plate, and thus plastic bending / bending back is performed. When manufacturing thin-walled metal pipes by an epoch-making method for manufacturing thin-walled metal pipes, which uses the residual curvature in the widthwise direction caused by plastic bending and unbending to bend the product to the product curvature in the widthwise direction In, the thin metal plate When continuously manufacturing a thin metal tube by forming both sides of the thin metal plate by squeezing rolls and then welding the abutting parts by squeeze roll, butt welding with caliber roll or block immediately after the squeeze roll exit side. The butt joint has an angle when butt-welding both side edges of a thin metal plate that is continuously formed into a tubular shape by a very simple means of keeping the cross-sectional shape of the thin-walled metal pipe formed into a perfect circle. It is possible to manufacture a thin-walled metal tube with an excellent cross-sectional shape by eliminating the disadvantage that the cross-sectional shape of the welded pipe deteriorates because it cannot be held in a state close to a perfect circle. The industrial value of the present invention capable of producing a metal tube is enormous.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment in which a thin metal tube is manufactured by the method of the present invention, and FIG. 2 is A-A in FIG.
Line enlarged sectional view, FIG. 3 is an enlarged sectional view taken along line BB in FIG. 1, FIG. 4 is an enlarged sectional view taken along line C-C in FIG. 1, and FIG. 5 is a thin-walled metal pipe according to the method of the present invention. FIG. 6 is a side view showing another embodiment of the manufacturing method shown in FIG.
Line enlarged cross-sectional view, FIG. 7 is a graph showing the ratio of the difference between the maximum outer diameter and the minimum outer diameter of the thin-walled metal pipes produced by the method of the present invention and without the method, divided by the average outer diameter, 8th
The figure is an enlarged cross-sectional view showing the cross-sectional shape of the material in the squeeze roll in the conventional manufacturing method. In the drawing 1 ... Metal thin plate 3 ... Bending roll with small diameter 6 ... Cylindrical roll on the input side 7 ... Cylindrical roll on the output side G ... Gear up 8 ... Roll 9 ... Seam guide roll 10 ... Squeeze Roll 11 …… Welding torch 12 …… Caliber roll or block 13 …… Urethane rubber lining pinch roll

Claims (1)

[Claims] 1. An inlet-side and outlet-side cylindrical rolls having axes that are parallel to each other and provided with gears between them to rotate in the same direction, and the cylinders adjacent to the two cylindrical rolls. A small group of bending rolls comprising a floating roll having a diameter greater than twice the thickness of the thin metal plate bent parallel to the axis of the profiled roll and bent from the gear. First, after passing through the gear roll through the inlet side cylindrical roll, then bending along a small-diameter bending roll, and then passing through the gear roll, a plastic bending is performed to form the inside of the pipe. By making the curvature in the longitudinal direction of the thin metal plate that has been plastically bent with a small-diameter bending roll orthogonal to the longitudinal direction with the surface inside, the residual curvature in the width direction caused by the plastic bending and bending back is set. Profit Then, the metal thin plate is bent in the width direction to a product curvature and continuously formed into a tubular shape, and then both side edges of the metal thin plate are butted by a squeeze roll and the butted portions are welded to produce a thin metal pipe. A method for producing a thin-walled metal tube having an excellent cross-sectional shape, characterized in that the cross-sectional shape of a thin-walled metal tube butt-welded with a caliber roll or a block immediately after the exit side of the roll is maintained in a perfect circle.