JPH09317085A - Metal pipe having locally irregular shape and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal pipe 1 which can favorably be used as a column material. SOLUTION: At least in one place about longitudinal direction on a body metal pipe 2 of a round shape an irregularly shaped portion 3 is provided in which the outside shape in at least one azimuth in the circumferential direction is turned into a flat form without decreasing the wall thickness. The flattened part 3a of this irregularly shaped portion 3 is to serve as a joint part for joining with another member such as a beam. The irregularly shaped portion 3 may be fabricated through a plastic deformation process including heating, compressing, etc., for the body metal pipe 2, or may be embodied by providing a buildup on the periphery of the metal pipe 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a round metal pipe such as a round steel pipe suitable for use as a structural material, and particularly to a metal having a shape in which a partial region in the longitudinal direction is suitable for joining other members. TECHNICAL FIELD The present invention relates to a pipe and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, round steel pipes have been widely used as structural materials such as pillars of buildings. When using this round steel pipe as a pillar material, various reinforcing members for securing strength are provided at the joint portion of the beam material,
For example, a method of fitting a reinforcing ring to the outer circumference of a round steel pipe and fixing it by welding, a method of welding and fixing a diaphragm inside the round steel pipe, and the like have been performed.

[0003]

However, providing such a reinforcing member on the round steel pipe requires a troublesome work, which causes a cost increase. Further, even at the portion where the reinforcing member is attached, the outer circumference is a cylindrical surface, so when joining the end portions of the beam member, the end portion of the beam member or the flange attached to the end portion of the beam member. Must be machined into an arc shape to match the cylindrical surface of the round steel pipe,
There is a problem that the processing is costly. Furthermore,
When the diaphragm is provided inside the round steel pipe, the diaphragm can be attached only to the pipe end, and therefore, there is a problem that the round steel pipe reinforced by the diaphragm cannot be used as a through column of a building.

[0004]

The present invention has been made to solve the above problems, and reduces the wall thickness of at least one portion in the longitudinal direction of a round main body metal tube such as a round steel tube. It is configured such that a part of the outer surface of which is made flat is provided without using the flat part, and another member such as a beam member is joined using the flat part.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The locally deformed metal pipe according to the present invention is such that at least one position in the longitudinal direction of a round main body metal pipe has at least one outer surface shape in the circumferential direction to reduce the wall thickness. It is characterized in that a deformed portion formed in a flat shape is provided instead.

The deformed portion of the locally deformed metal pipe of this structure is such that the outer surface of at least one position in the circumferential direction has a flat shape without reducing the wall thickness, so that the average wall thickness is It is thicker than the wall thickness of the metal tube and the strength is increased. For this reason, this deformed portion can be used as a joint portion to other members such as beam members without using a reinforcing material, and since the outer surface is flat, other members such as beam members to be joined thereto can be used. The end portion or the flange provided at the end portion can be simply pressed against each other for joining, and the joining work becomes extremely easy. Therefore, the locally deformed metal pipe of the present invention is extremely suitable for applications such as joining other members to the side surface, for example, as a pillar material for a building, and the main body metal pipe can be used as a through pillar extending over a plurality of floors. It is also possible to use the locally deformed metal pipe of the present invention as a through column by providing a deformed portion at a position corresponding to the beam mounting position on each floor.

The material of the main body metal pipe used here is not particularly limited, but a steel pipe having high strength and being easily available is usually used. The deformed portion can be provided in a desired number at a desired position in the longitudinal direction of the main body metal tube. Further, in each deformed portion, the portion in which the outer surface is flat, that is, the flat portion may be only the outer surface at one position in the circumferential direction, but it is also possible to make the outer surface in a plurality of circumferential directions if necessary. It is also possible to form the outer surface into a rectangular tube shape, for example. Forming a flat surface on the outer surface in a plurality of directions in the circumferential direction has the advantage that beam members and the like can be joined in a plurality of directions. The size (width, length) of the flat surface portion formed on the outer surface of the deformed portion may be determined in consideration of the dimensions of other members to be joined to the deformed portion. In a place used for joining beam members of about 300 to 900 mm, the length of the flat surface portion (the length in the longitudinal direction of the main body metal pipe) is set to 320 to 1200.
mm. The thickness of the deformed portion is determined so as not to reduce the wall thickness of the main body metal pipe even when the outer surface is formed into a flat surface, but it should be set thick to ensure the required strength. preferable. For example, the average thickness of the deformed portion is 1.5 with respect to the original thickness of the main body metal tube.
It is preferably about 5.0 times.

The deformed portion can be formed by plastically deforming a part of the main body metal tube. Alternatively, another material may be joined to the main body metal tube to form the main body metal tube. In this case, a tubular member having a hole that fits on the outer surface of the main body metal pipe and having an outer shape that forms a deformed portion may be prepared in advance, and may be fitted on the outer surface of the main body metal pipe. Alternatively, the profiled portion may be formed on the outer circumference of the main body metal tube by overlaying by casting, welding or the like.

The present invention also provides a method for manufacturing the above locally deformed metal tube. That is, the invention of claim 2 of the present invention is a method for producing the above locally deformed metal pipe, wherein at least one azimuth in the circumferential direction of the longitudinal portion of the round main body metal pipe to be deformed, In parallel with the longitudinal direction of the pipe, the planar molding surface of the mold is placed in close contact with or at a distance from the outer peripheral surface of the pipe, and the tubular body in the longitudinal direction where the mold is arranged is heated under red heat. A method for producing a locally deformed metal pipe, wherein a deformed portion having a flat surface portion in at least one azimuth direction in the circumferential direction is formed by applying a compressive force in the longitudinal direction of the pipe to increase the wall thickness. .

According to a third aspect of the present invention, there is provided a method for manufacturing the above locally deformed metal pipe, wherein at least one portion in the circumferential direction of the pipe is provided at a longitudinal portion of the round main body metal pipe to be deformed. At least one azimuth in the circumferential direction is obtained by arranging an outer mold with a flat casting surface in the azimuth direction and casting a molten metal of the same material as the pipe into the gap between the pipe and the solidification. A method for producing a locally deformed metal pipe, characterized in that a deformed portion having a flat surface is formed on the inner surface of the metal pipe.

The present invention will be described in more detail below with reference to the embodiments of the drawings. 1A and 1B show an example of a locally deformed metal pipe of the present invention. FIG. 1A is a schematic sectional view, and FIG. 1B is a schematic sectional view of a deformed portion. The locally deformed metal pipe indicated by reference numeral 1 as a whole is provided with a main body metal pipe 2 made of a steel pipe having a circular cross section, and in a partial region in the longitudinal direction of the main body metal pipe 2,
A deformed portion 3 formed by plastically deforming the main body metal tube 2 is provided. The deformed portion 3 is a flat surface portion 3a in which the shape of the outer surface at the one side in the circumferential direction is formed in a flat shape without reducing the wall thickness. The size of the flat surface portion 3a is set to a size required for joining other members such as beam members. Further, the average thickness of the deformed portion 3 is determined so as to ensure the strength required for joining and using another member to the flat surface portion 3a. Thus, the flat surface portion 3a of the deformed portion 3 can be used as a joint portion to another member such as a beam material without using a reinforcing material, and since the flat surface portion 3a is flat, the beam material to be joined thereto It is possible to press the end portions of other members such as or the like or the flanges provided on them into a flat state and join them by bolting or welding, and it is extremely easy to join other members such as beam members. .

Both ends of the deformed portion 3 may be planes orthogonal to the axis of the main body metal tube 2, but it is preferable to form inclined surfaces 3b having a linear shape or an arc shape as shown in the drawing. By forming such an inclined surface 3b, there is an advantage that a sudden thickness change is eliminated and stress concentration is less likely to occur. Here, the inclination angle of the inclined surface 3b with respect to the axis of the main body metal tube 2 is preferably set to 5 to 45 °, and more preferably 5 to 30 °.

In the above embodiment, the deformed portion 3 is formed with only one flat surface portion 3a, but it is possible to provide a plurality of flat surface portions 3a. FIG. 2 is a schematic sectional view showing an embodiment in that case. The deformed portion 3A formed on the locally deformed metal tube 1A has a cross section of a substantially rectangular tube shape, and includes four plane portions 3a. With this configuration, there is an advantage that beam members or the like can be joined to one deformed portion 3A in four directions. In the embodiment of FIGS. 1 and 2, the deformed portions 3 and 3A formed on the main body metal tube 2 are provided at desired positions in the longitudinal direction of the main body metal tube 2, and the number of them is also set. It is optional.

3A and 3B show another embodiment of the locally deformed metal pipe of the present invention. FIG. 3A is a schematic sectional view, and FIG. 3B is a schematic sectional view of the deformed portion. This locally deformed metal tube 1B
Also has a main body metal tube 2 and a deformed portion 3B. However, the deformed portion 3B is not made by plastically deforming the main body metal tube 2 and another material is joined to the outer surface of the main body metal tube 2. It was formed. The deformed portion 3B may be formed by joining a material made in the shape shown in advance to the outer circumference of the main body metal tube 2 or on the outer surface of the main body metal tube 2 in the same system as the main body metal tube 2. It may be formed of a built-up layer formed by casting a molten metal of the above material and solidifying it. Also in this embodiment, the flat surface portion 3a formed on the deformed portion 3B has the shape shown in FIG.
As shown in FIG.
Needless to say, a plurality of them may be provided as in the above.

Next, a method of manufacturing the locally deformed metal tube 1 shown in FIG. 1 will be described. FIG. 4 is a schematic cross-sectional view showing an example of a thickening processing apparatus for manufacturing the locally deformed metal pipe 1.
Is the main metal tube to be thickened. Reference numeral 12 is a fixing means for fixing and holding one end side of the main body metal tube 2 in a fixed position, and 13 is a compression such as a hydraulic cylinder for pushing the other end side of the main body metal tube 2 in the longitudinal direction to apply a compressive force to the strip 1. A device, 14 is an annular heating device capable of locally heating a small region in the longitudinal direction of the main body metal tube 2 to form a heating part 15 in a red hot state, for example, a high frequency heating coil, 16 is a rear part of the heating device 14. Is a mold placed in. As shown in FIG. 5, the mold 16 has a molding surface having an inner surface shape corresponding to the outer peripheral shape of the cross section of the deformed portion 3 (see FIG. 1). The corresponding flat molding surface 16a is provided. The mold 16 has a flat molding surface 1
6a is arranged parallel to the longitudinal direction of the main body metal tube 2 before the thickness increase processing and at a position a little distance from the outer peripheral surface of the main body metal tube 2. In addition, when the thickness increase amount when forming the deformed portion 3 from the main body metal tube 2 is not so large, the flat forming surface 16a of the mold 16 may be arranged in close contact with the outer peripheral surface of the main body metal tube 2. Good.

The mold 16 has a structure in which a cooling passage 17 for cooling the inside of the mold 16 is provided to cool the mold 16 to prevent abnormal temperature rise of the mold 16 itself and to heat the heated main body metal tube 2. It has a cooling function. Reference numeral 18 is a drive device capable of moving the heating device 14 and the mold 16 with respect to the main body metal tube 2 at a desired speed.

The thickness increasing operation using the thickness increasing apparatus having the above structure is performed as follows. That is, the main body metal tube 2 to be thickened is fixed and held by the fixing means 12, and the opposite end thereof is pressed by the compression device 13 such as a hydraulic cylinder to apply a compressive force to the main body metal tube 2, A small area in the longitudinal direction of the main body metal tube 2 is heated by the heating device 14 to form a heating part 15 in a red heat state that is easily plastically deformed.
The heating device 1 that causes thickening due to compressive force on the
4 is moved along the main body metal tube 2, and at the same time, the heating unit 15
The outer periphery of is heated by the mold 16 so that the inner surface of the mold 16 has a shape determined by the molding surface, and the heating portion 15 is cooled and solidified. Thereby, the desired position in the longitudinal direction of the main body metal tube 2 is increased, and the deformed portion 3 is formed.

In this embodiment, the heating section 15 after the thickness increase
Is cooled and solidified by the mold 16, but if cooling only by the mold 16 causes insufficient cooling, a cooling device such as a type in which a coolant such as cooling water is sprayed is arranged behind the mold 16. You may. Further, although the mold 16 is arranged only on the outer surface side of the main body metal tube 2 in the above embodiment, the mold 1 on the outer surface side is arranged.
There is a case where the deformed portion 3 having a desired shape cannot be formed with only 6 pieces. In that case, the mold may be arranged also on the inner surface side. The heating device 14 may be arranged inside the main body metal tube 2. Further, in the above embodiment,
The mold 16 has a molding surface corresponding to the entire circumference of the deformed portion. However, the mold 16 used here does not necessarily have a molding surface corresponding to the entire circumference of the deformed portion. There is no need to do this, and it is sufficient to use a device having a flat molding surface corresponding to at least the flat surface portion 3a.

Further, in the above embodiment, while heating and thickening a small region in the longitudinal direction of the main body metal pipe, the heating and thickening position is moved to perform thickening processing of a desired length.
When the length of the deformed portion 3 to be formed is short, the portion having the length required for forming the deformed portion of the main body metal tube 2 is heated at once, and a compressive force is applied to the whole to simultaneously increase the thickness. It may be configured to perform. In this case, the mold 16 is naturally
The deformed portion 3 having a length equal to or longer than the entire length is used.

Next, an example of a method of manufacturing the locally deformed metal tube 1B having the structure shown in FIG. 3 will be described. 6 and 7 are schematic cross-sectional views showing an apparatus for forming the deformed portion 3B on the main body metal tube 2 by casting, which are shown in different operating states. The main body metal tube 2 is vertically oriented and held by a supporting device (not shown), and is intermittently moved downward. Reference numeral 21 is an outer mold having a casting surface 22 on the inner circumference corresponding to the outer circumference of the deformed portion 3B formed on the main body metal tube 2. Therefore, the casting surface 22 of the outer mold 21 is the flat surface portion 3 of the deformed portion 3B.
The position corresponding to a is flat. Outer mold 21
Are arranged so that the casting surface 22 surrounds the outer peripheral surface of the vertically oriented main body metal tube 2 and forms an appropriate gap with the main body metal tube 2. The outer mold 21 has a heating mold part 21a located in the upper part and a cooling mold part 21b located in the lower part. A high frequency induction coil 23 for heating is provided in the heating mold 21a. On the other hand, a cooling water channel 24 is provided in the cooling mold 21b.
Cooling water is supplied to the water passage 24 through an adjusting valve, and the cooling effect can be adjusted by adjusting the water supply amount by the adjusting valve. 25
Is a high-frequency induction coil disposed above the outer mold 21, and is for preheating the outer peripheral surface of the main body metal tube 2. These outer mold 21 and high frequency induction coils 23, 2
5 and the like are fixedly arranged at the illustrated positions.

Next, the deformed portion forming operation by the local thickening device having the above construction will be described. First, at the lower end of the region where the deformed portion 3B (see FIG. 3) of the main body metal tube 2 is to be formed,
A receiving plate 30 having a width substantially equal to the thickness of the deformed portion is welded and fixed, and then an antioxidation flux is applied to the portion of the main body metal tube 2 where the deformed portion is to be formed. Then, the main body metal tube 2 is lowered from above to pass through the center of the high frequency induction coil 25 and the outer mold 21, and the outer peripheral surface of the deformed portion, that is, the region where the overlay layer is to be formed is guided from the lower end side by high frequency induction. Preheat to about 600 ° C with the coil 25. Then, as the body metal tube 2 descends, the receiving plate 30 descends, and as shown in FIG. 6, when the body metal tube 2 reaches the substantially lower end position of the heating mold portion 21a, the body metal tube 2 is temporarily descended. After stopping, a separately prepared metal for overlaying, that is, a molten metal 32 of a material of the same system as the main body metal tube is poured into the gap between the outer mold 21 and the main body metal tube 2.

The molten metal 32 poured into the gap between the main body metal tube 2 and the outer mold 21 is induction-heated by the high frequency induction coil 23 to be held in a molten state, and the surface of the main body metal tube 2 is also high frequency induction coil 23. It is heated by and fuses with the molten metal. At the same time, a convection phenomenon occurs in the molten metal 32 to float slag and other impurities in the molten metal on the surface, and when gas is generated, the gas is discharged upward.

After pouring the molten metal, the main body metal tube 2 is slightly lowered, and the operation of pouring the molten metal again is repeated.
That is, the main body metal tube 2 is sequentially lowered, and the molten metal is sequentially poured into the gap between the main body metal tube 2 and the outer mold 21. As the main body metal pipe 2 is lowered by this operation, the lower part of the molten metal 32 moves downward beyond the lower end of the heating mold part 21a and moves to the position of the cooling mold part 21b, as shown in FIG. First, the molten metal 32 is used as the cooling mold 2
It is cooled by 1b and becomes a molten metal 33 in a semi-molten state,
When it further descends, it is sufficiently cooled and solidified, and the built-up layer, that is, the deformed portion 3B, which is well adhered to the outer peripheral surface of the main body metal tube 2.
To form. Here, by appropriately adjusting the descending speed of the main body metal tube 2 and the cooling speed by the cooling mold section 21b, a region of the molten metal 32 in a molten state and a semi-molten state are formed between the outer mold 21 and the main body metal tube 2. It is possible to stably form and hold the region of the molten metal 33 in the state and the solidified region (that is, the overlay layer), and the overlay layer is sequentially formed in this state. The upper end of the region where the deformed portion of the main body metal tube 2 is to be formed is lowered to a little lower than the upper end position of the heating mold part 21a, and after pouring to that region, the main body is not poured. The metal tube 2 is sequentially lowered. As a result, the poured molten metal is cooled and solidified, and the deformed portion 3B is formed in the predetermined region of the main body metal tube 2 by the buildup layer.

As described above, in the method of this embodiment, while pouring molten metal into the gap between the metallic body tube 2 and the outer mold 21, the metallic body tube 2 is lowered and the molten metal is sequentially cooled and solidified to form a buildup layer. Since the deformed portion 3B is formed as it is formed, it is possible to ensure the joining between the main body metal tube 2 and the deformed portion 3B, and to reliably supply the molten metal to the solidified portion, It is possible to efficiently form the deformed portion 3B of good quality with no cavities or accumulation of impurities and no cracks. Further, the deformed portion 3B can be formed in a desired region in the longitudinal direction of the main body metal tube 2. After the deformed portion 3B is formed on the outer peripheral surface of the main body metal tube 2, the metal tube is removed. By the above operation, the locally deformed metal tube 1B shown in FIG. 3 is manufactured. However, in this case, both ends of the deformed portion 3B are end surfaces that are substantially perpendicular to the axis of the main body metal tube 2. If, as shown in Figure 3,
When it is desired to form the inclined surface 3b at the end of the deformed portion 3B, an operation such as fillet welding of the fillet at the end or grinding the inclined surface by a grinder or the like may be performed. Further, on the lower end side, the inclined surface can be formed by adjusting the shape of the receiving plate 30.

In the above embodiment, the high-frequency induction coil 25 for preheating and the outer mold 21 are arranged at fixed positions and the main body metal tube 2 is moved downward, but the present invention is not limited to this structure. , The main body metal tube 2 is held in a fixed position in a vertically oriented state, and the high frequency induction coil 25 and the outer mold 21 are held.
It is also possible to make the main body metal tube 2 move downward relative to the high frequency induction coil 25 and the outer mold 21 by moving the above. Further, in the above embodiment,
When the main body metal pipe 2 is sequentially lowered and the molten metal is sequentially poured, and therefore the main body metal pipe 2 is lowered and the pouring is performed intermittently, when continuous pouring is possible. Alternatively, the main body metal tube 2 may be continuously lowered and poured. Furthermore, in the method described above, the main body metal tube 2 is attached to the outer mold 2
Although this is a method of overlaying while moving relative to No. 1, it is also possible to form a deformed portion having a desired length by pouring once by using a large mold.

The method of manufacturing the deformed portion by heating and thickening the main body metal tube 2 and the method of casting and solidifying the molten metal to form the deformed portion have been described above. The deformed portion often has characteristics such as low elongation and poor impact resistance due to heat history or through a casting process. Therefore, if necessary, it is recommended to heat the deformed portion to 800 to 1000 ° C. and heat it to improve the mechanical properties. As the heating method for heat-treating the deformed portion, a high-frequency induction coil with a length extending over the entire length of the deformed portion is arranged, and the entire deformed portion is heated and heated at the same time. A method of arranging a coil and moving it relative to the deformed portion to heat the entire deformed portion can be mentioned. Further, it is also effective to correct the outer shape of the heated portion with a mold when performing heat treatment.

[0027]

As described above, the locally deformed metal pipe of the present invention has a shape of the outer surface at least one position in the circumferential direction of a partial region in the longitudinal direction of the main body metal pipe having a circular cross section. Since it has a flat-shaped deformed portion without reducing the thickness, it is possible to join another member such as a beam without using a reinforcing material to the flat portion of the deformed portion, and Since the end of the other member to be joined to the flat surface or the flange provided at the end may be simply flat,
It has an effect that the joining work can be performed very easily without requiring troublesome processing.

Further, in the manufacturing method of the present invention, the flat molding surface of the mold is provided in at least one direction in the circumferential direction of the longitudinal portion of the round main body metal tube to be deformed, parallel to the longitudinal direction of the tube. Is placed in close contact with the outer peripheral surface of the tube or at a distance, and the tube body at the longitudinal portion where the mold is arranged is thickened by applying compressive force in the longitudinal direction of the tube under red heat. Is characterized in that a deformed portion having a flat surface portion is formed in at least one azimuth direction in the circumferential direction.
A desired number of deformed portions can be formed at desired positions in the longitudinal direction of the main body metal pipe, and since the deformed portions have an integral structure with the main body metal pipe, they have the effect of high strength. are doing.

Further, in the manufacturing method of the present invention, an outer mold having a flat casting surface in at least one direction in the circumferential direction of the pipe is arranged at the longitudinal portion of the round main body metal pipe to be deformed.
At least 1 in the circumferential direction is obtained by casting a molten metal of the same material as the pipe into the gap between the pipe and the solidification.
Since it is characterized by forming a deformed portion having a plane portion in the azimuth, it is possible to form a desired number of deformed portion at a desired position in the longitudinal direction of the main body metal tube,
Moreover, there is an effect that the joint strength between the deformed portion and the main body metal pipe is large. Further, in this method, since the deformed portion is formed by casting, it is possible to easily obtain the desired shape by changing the casting surface shape of the outer mold to the desired shape, and the wall thickness is also the main body metal. It can be set arbitrarily regardless of the wall thickness of the tube, and has an effect that a deformed portion having a desired shape and size can be formed.

[Brief description of drawings]

1A is a schematic sectional view of a locally deformed metal pipe according to an embodiment of the present invention, and FIG. 1B is a schematic sectional view of a deformed portion of the locally deformed metal pipe.

FIG. 2 is a schematic sectional view of a modified portion of another embodiment of the present invention.

FIG. 3A is a schematic sectional view of a locally deformed metal pipe according to another embodiment of the present invention. FIG. 3B is a schematic sectional view of a deformed portion of the locally deformed metal pipe.

FIG. 4 is a schematic cross-sectional view of a thickening processing apparatus for manufacturing the locally deformed metal pipe shown in FIG.

FIG. 5 is a schematic cross-sectional view showing a state in which a mold is arranged on the outer periphery of a main body metal tube in the apparatus shown in FIG.

FIG. 6 is a schematic cross-sectional view showing an apparatus for manufacturing the locally deformed metal pipe shown in FIG. 3 in an initial state of overlaying.

FIG. 7 is a schematic cross-sectional view showing the apparatus of FIG. 6 in the state of being built up.

[Explanation of symbols]

 1, 1A, 1B Locally deformed metal pipe 2 Main body metal pipe 3, 3A, 3B Deformed portion 3a Flat portion 12 Fixing means 13 Compressor 14 Heating device 15 Heating portion 16 Mold 16a Flat molding surface 18 Driving device 21 Outside Mold 21a Heating mold part 21b Cooling mold part 23, 25 High frequency induction coil 24 Water channel 30 Catch plate 32, 33 Molten metal

Claims (3)

[Claims] 1. A round-shaped main body metal tube is provided with a deformed portion in which at least one position in the longitudinal direction has a shape of an outer surface at least one position in the circumferential direction formed into a flat shape without reducing the wall thickness. A locally deformed metal tube characterized by. 2. The method for producing a locally deformed metal pipe according to claim 1, wherein the longitudinal direction of the pipe is in at least one circumferential direction of the longitudinal portion of the round body metal pipe to be deformed. In parallel with the direction, the flat molding surface of the mold is placed in close contact with or at a distance from the outer peripheral surface of the pipe, and the tubular body of the longitudinal portion where the mold is arranged is placed under the red heat of the pipe. A method for producing a locally deformed metal pipe, characterized in that a deformed portion having a flat surface portion is formed on an outer surface of at least one azimuth in the circumferential direction by increasing the thickness by applying a compressive force in the longitudinal direction. 3. The method for producing a locally deformed metal pipe according to claim 1, wherein at least one orientation in the circumferential direction of the pipe is formed at a longitudinal portion of the round main body metal pipe to be deformed. By arranging an outer mold whose surface is flat and pouring a molten metal of a material of the same system as the pipe into the gap between the pipe body and solidifying it, at least one outer circumferential surface is formed. A method for producing a locally deformed metal tube, comprising forming a deformed portion having a flat surface portion.