KR101049632B1 - Metal tube manufacturing method with excellent formability - Google Patents

Abstract

The present invention relates to a method for manufacturing a metal tube, a method of manufacturing tubes of various shapes by sequentially cutting the material by blanking and then sequentially processing into a U-shaped O-shape by press molding to avoid the continuous manufacturing method using a conventional multi-stage roll. It relates to a metal tube manufacturing method which can be applied to the excellent moldability.

The present invention comprises the steps of: a) blanking the material in the shape of the development of the tube to be manufactured; b-1) a first press forming step of forming both edges of the blanked material; b-2) a second press-molding step of molding the central portion of the raw material, but forming the elliptical shape having the long radius at the joint side; b-3) a third press molding step of pressing the raw material formed in an elliptical shape with a press mold to mold the remaining part to form a finished product; c) correcting the appearance of the tube by roller clamping; And d) laser welding the joints of the tubes.

Metal tube, formability

Description

High formablity metal tube manufacturing method using U-O forming}

The present invention relates to a method for manufacturing a metal tube, a method of manufacturing tubes of various shapes by sequentially cutting the material by blanking and then sequentially processing into a U-shaped O-shape by press molding to avoid the continuous manufacturing method using a conventional multi-stage roll. It relates to a metal tube manufacturing method which can be applied to the excellent moldability.

The general pipe manufacturing process consists of a continuous operation of forming and welding a tube through a multi-stage forming roll while unwinding the coil.

However, in this conventional method, only the shape of a straight tube having a constant diameter of the tube can be manufactured, so that a conical tube whose cross section is not constant or a heterogeneous diameter tube having different diameters at both ends could not be manufactured.

In addition, this conventional method is to process the shape by using a roller, there is a limit in minimizing the work hardening and had a problem that is difficult to apply to a strong material.

In addition, since the coil material is uncoiled and processed continuously, it can only be manufactured in a form in which the longitudinal direction of the tube and the longitudinal direction of the material coincide, so that the ratio of thickness and diameter to t / D can be manufactured only up to 1/75 level. Could.

The present invention is to provide a method for producing a metal tube excellent in formability and excellent in formability and suitable for manufacturing a vehicle structural tube or hydroforming tube having various forms.

The present invention is to provide a metal tube manufacturing method that can produce a tube using a high-strength material.

The present invention is to provide a method for producing a metal tube with excellent surface quality of the coated material.

The present invention comprises the steps of: a) blanking the material in the shape of the development of the tube to be manufactured; b-1) a first press forming step of forming both edges of the blanked material; b-2) a second press-molding step of molding the central portion of the raw material, but forming the elliptical shape having the long radius at the joint side; b-3) a third press molding step of pressing the raw material formed in an elliptical shape with a press mold to mold the remaining part to form a finished product; c) correcting the appearance of the tube by roller clamping; And d) laser welding the joints of the tubes.

Metal tube manufacturing method excellent in formability according to the present invention by blanking and cutting to a shape corresponding to the shape of the development of the tube to be manufactured, by pressing the molding method to the shape of the tube by minimizing the work hardening of the material The effect is that the molding can be performed in the form.

In addition, the metal tube according to the present invention can minimize the heat affected area around the weld by using laser welding, resulting in the effect that the manufactured metal tube has a formability similar to that of the raw steel sheet.

In addition, the tube manufacturing method according to the present invention can be produced in a form in which the longitudinal direction of the tube and the width direction of the coil material, thereby bringing the effect of improving the formability of the tube.

In addition, the tube manufacturing method according to the present invention brings the effect that can be produced in the form of a tube, such as a conical tube, heterogeneous diameter tube as well as a straight tube.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of a metal tube manufacturing method excellent in formability according to the present invention.

In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description.

In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or convention of a user or an operator.

Therefore, definitions of these terms should be made based on the contents throughout the specification.

1 is a conceptual diagram showing the winding direction of the coil and the direction of the tube to be manufactured.

In the tube manufacturing method according to the present invention, the blanking material is first blanked into a shape corresponding to the shape of the developed view of the tube to be manufactured, and then press-molded to manufacture the tube.

The raw material 10 is wound in the form of a coil, and in view of the characteristics of the manufacturing process, the width direction has better moldability than the moldability in the longitudinal direction.

When the tube is manufactured from the coil of the raw material 10, the length direction of the tube 12 and the length direction of the coil material may be manufactured to coincide, or the length direction of the tube 14 and the width direction of the coil material may be It may also be prepared in a consistent form.

In the case of the conventional multi-stage roll forming, the lengthwise direction of the tube and the length of the coil material were inevitably matched. In this case, the expansion rate was 12.85% when additional molding was performed using the manufactured tube. It was about level.

In the case of using the method according to the present invention, when the length of the tube 12 coincides with the length direction of the material, the expansion ratio is improved to 14.85%, resulting in an excellent formability.

The reason why the tube manufactured by the method according to the present invention is excellent in molding is that it can be processed while freely changing the position of the material by using a press molding method as described below when processing into a tube shape, thereby minimizing work hardening. Therefore, overall moldability is improved.

The best molding is to manufacture so that the longitudinal direction of the tube 14 and the width direction of the coil material coincide, in which case the expansion ratio is 21.18%.

Figure 2 is a perspective view showing the form of the various tubes that can be produced according to the present invention.

As shown, the manufacturing method according to the present invention, the shape of the straight tube 21 on the left side of the figure, the shape of the conical tube 22 (conical tube) in which the diameter is constantly changed, heterogeneous having different diameters on both sides All of the diameter tube 23 (Multi-diameter tube) shape can be manufactured, in addition to the various types of tubes can be produced.

In the case of using the conventional roll forming method, only the shape of a straight pipe could be manufactured, but various types of tubes were manufactured by using the manufacturing method of the present invention, which first blanked the shape of a developed view and then formed into a tube through a press molding process. can do.

Hereinafter will be described in detail with respect to the manufacturing method for each type of tube.

3 is a process flow chart showing a conical tube manufacturing method according to the present invention, Figure 4 is a process flow chart showing a tube manufacturing method having a heterogeneous diameter according to the present invention, Figure 5 is a view showing a cross section of the material for each process step. being.

The conical tube and the tube having a heterogeneous diameter are different from each other, but when manufactured by the manufacturing method according to the present invention go through the same process, a method for producing a conical tube will be described below with reference to FIG. .

As shown, the tube manufacturing method according to the present invention comprises the steps of: a) blanking the material in the shape of the development of the tube to be manufactured; b-1) a first press forming step of forming both edges of the blanked material; b-2) a second press forming step of forming a central portion of the raw material, but forming an elliptical shape having a long radius near the joint portion; b-3) a third press molding step of pressing the raw material formed in an elliptical shape with a press mold to mold the remaining part to form a finished product; c) correcting the appearance of the tube by roller clamping; And d) laser welding the joint of the tube.

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In step a), the blanking is cut into the developed shape of the tube to be manufactured. In the case of a straight tube, the blanked material has a rectangular shape, and the length of one side corresponds to the length of the tube, and the length of the other side is cut to correspond to the circumference of the tube. At this time, when the lengthwise direction of the tube and the width direction of the coil material are cut to match, as described above, the formability of the coil material is excellent.

Referring to Figure 5, step a) because only the blanking operation is performed and the molding is not carried out so that the cross section of the material remains flat.

b-1) In the first press forming step, both edges of the blanked material are formed, and the overall cross-sectional shape has a substantially U-shaped cross section. Referring to FIG. 5, both edges are formed to have a circular curvature to be formed and the center portion is kept flat.

At this time, the molding of both sides is made at once and is made between the first press upper mold 41 and the first press lower mold 42 having a U-shaped cross section as shown.

Next, in the b-2) second press molding step, the center portion of the raw material is molded, but is molded to have a shape of an ellipse with a long diameter near the joint portion.

Referring to FIG. 5, the shape of the cross section may be in the shape of an ellipse having a long radius at the joint side when molded up to step b-2.

The second press molding is performed by the second press upper mold 43 formed to correspond to the inner surface shape of the tube to be molded, and the second press lower mold 44 formed to correspond to the outer surface shape of the tube to be molded.

That is, when the unmolded portion is pressed onto the second press upper mold 43 in a state where it is placed on the second press lower mold 44, the material is molded while being wound around the second press upper mold 43.

b-3) a third press upper mold 45 and a third press lower mold 46 having a molding groove corresponding to the finished product shape in the third press molding step, and undergoing the second press molding step. An oval shaped product is pressurized between the third press upper mold 45 and the third press lower mold 46 to form a circular cross section as shown in FIG.

The reason why the molding is divided into three stages is to minimize the work hardening. First, the edge portion is formed and the central portion is formed to form a long elliptical cross section near the joint, and finally the long length portion. Pressing up and down to form a desired shape.

In step c), the outer shape of the tube is corrected while the joint portion of the tube is further brought into close contact with each other.

In step d), the manufacturing of the tube is completed by connecting the closely joined joints in step c) by laser welding. The use of laser welding is advantageous in terms of formability due to less heat affected zones, and no separate heat treatment is required for the weld.

The tube manufactured by the manufacturing method according to the present invention can be minimized by the laser welding is applied to the affected area around the weld by the laser welding exhibits a formability almost similar to the formability of the raw steel sheet.

On the other hand, the steel pipe manufactured by the conventional continuous tubing method is hardened by heat effects about 30 degrees around the welded portion, the moldability is reduced by more than 10%.

In addition, in the manufacturing method of the present invention, because the laser welding method is used, the bead shape by welding also has the effect of neatly generated without the need for removal work like resistance welding.

After the laser welding step, the method may further include inspecting the weld and finishing the weld surface, and may further include cutting both ends of the tube or cutting the tube if necessary.

According to the present invention, since the material cut by blanking is press-molded into a tube shape, it is possible to manufacture an ultra-thin tube having a low ratio of the thickness of the material to the diameter of the tube. Conventionally, the ratio t / D of the thickness and the diameter could be manufactured up to 1/75 level, but by using the method according to the present invention, an ultra-thin tube having a maximum thickness of 1/250 can be manufactured.

In addition, a method of changing from a U-shaped cross section to an O-shaped cross section in steps so as to minimize work hardening when forming into a tube is used. Therefore, the tube produced according to the method of the present invention brings an effect that is excellent in formability than the tube manufactured by the continuous tubing method using a conventional roll.

In addition, the present invention can form a tube using a high strength dual phase (DP) steel, complex phase (CP) steel, TRIP (TRansformation Induced Plasticity) steel because the shape is formed by a press molding method.

In addition, the present invention may use a GA, GI steel sheet material and in the case of a plated steel sheet provides excellent surface quality by reducing scratches, dents, roll marks and the like.

The present invention can be applied not only to the above steel sheets, but also to aluminum and stainless steel.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. I will understand.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

1 is a conceptual diagram showing the winding direction of the coil and the direction of the tube to be manufactured,

Figure 2 is a perspective view showing the form of various tubes that can be produced according to the present invention,

3 is a process flowchart showing a method of manufacturing a conical tube according to the present invention;

Figure 4 is a process flow chart showing a tube manufacturing method having a heterogeneous diameter according to the present invention,

5 is a view showing a cross section of the material for each process step.

Claims (9)

a) blanking the material in the shape of a developed view of a tube to be manufactured; b-1) a first press molding step of forming both edges of the blanked material; b-2) a second press-molding step of molding the central portion of the raw material, but forming the elliptical shape having the long radius at the joint side; b-3) a third press molding step of pressing the raw material formed in an elliptical shape with a press mold to mold the remaining part to form a finished product; c) correcting the appearance of the tube by roller clamping; And d) laser welding the seam of the tube; Including, The a) step is blanked so that the transverse direction of the coil material and the longitudinal direction of the tube to be manufactured, and the b-1) step by the first press upper mold and the first press lower mold having a U-shaped cross section The step b-2) is performed by the second press upper mold formed to correspond to the inner surface shape of the tube to be molded, and the second press lower mold formed to correspond to the outer surface shape of the tube to be molded, b-3) step is performed by the third press upper mold and the third press lower mold having a forming groove corresponding to the finished product outline, the step c) is a multi-stage roller having a groove shape corresponding to the outer shape of the tube. A metal tube manufacturing method with excellent formability using a V-O forming method, characterized by passing through. delete delete delete delete delete delete The method of claim 1, After step d), Inspecting the welded portion, and finishing the surface of the welded portion, characterized in that the metal tube manufacturing method excellent in formability using the BOO forming method characterized in that it further comprises. The method of claim 1, After step d), A metal tube manufacturing method excellent in formability using a V-O forming method, characterized by further comprising cutting both ends of the tube.

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