JPH05169144A - Manufacturing method of metal curved pipe - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] Metal pipes are bent while heat-treating, and metal bending pipes with straight pipe parts that have undergone the same heat treatment as the bending parts at both ends of the bending parts are made to continue the process. To provide a manufacturing method. A metal pipe 1 is locally heated by an annular heating device 7 equipped with a cooling device and is cooled immediately after heating, and the heating portion is moved by a propulsion device 9 in the longitudinal direction of the pipe while bending moment. A metal pipe having straight pipe portions of appropriate length at both ends of the curved pipe portion and subjected to the same heat treatment as a whole is manufactured by an apparatus for adding and processing. In this method, bending is continuously performed on the heat treatment of the straight pipe part on the front end side of the pipe, and the pipe is stopped at the end of the bending process, and the straight pipe part on the rear end side of the pipe is heat treated while moving the heating device backward. After completing all the steps of heat treatment and bending, just before releasing the tube from the clamp 4, the bending energy between the tube and the device for applying the bending moment is released. In the case of processing large-diameter thick-walled pipes, a heating device is arranged inside and outside the pipes to drive them synchronously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal curved pipe which is bent while heat-treating a metal pipe and has straight pipe portions at both ends of the bent portion which have been subjected to the same heat treatment as the bent portion. Manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing a metal curved pipe, in which a metal pipe is bent while being heat-treated, and a straight pipe portion before and after the bent portion is continuously heat-treated, the present applicant has filed. There is one described in JP-A-60-44054. In this method, a heat treatment device is arranged outside a metal pipe, and the heat treatment device is arranged to move at a constant speed relative to the pipe through a straight pipe portion, a bent portion, and a straight pipe portion at all times. The whole bent pipe with a pipe part can be uniformly heat-treated.

Further, as a method of bending mainly a thick metal tube while heat-treating, there is one described in Japanese Patent Application Laid-Open No. 51-84766 filed by the present applicant. This method is a method in which a heating device is fixed inside and outside the metal tube, and heating and quenching are simultaneously performed while moving the metal tube from the inner and outer surfaces of the tube to perform bending processing. It can be heat-treated simultaneously with bending.

However, in the former method, the metal tube is stopped near the end of the bending process, the heat treatment is performed while the heat treatment device is moving backward, and the pipe is released from the clamp holding the pipe. A large amount of bending energy may be stored in the tube, and when this bending energy is stored, when the tube is released from the clamp, it becomes a springback and the tube pops out,
There is a problem in that there is a case where the rolling causes the heat treatment temperature to change, which makes uniform processing difficult.

In addition, combining the former method and the latter method,
When heat-processing while bending a large-diameter thick-walled metal pipe,
A heating device is placed inside and outside the pipe to heat-treat continuously from the straight pipe portion to the bent portion and then to the straight pipe portion.When heat treating the straight pipe portion, the pipe is released from the clamp and heat treatment of the curved pipe portion is performed. During the bending process, the operation of holding the pipe by the clamp must be performed. However, unless the inner and outer surface heating devices are accurately synchronized while the pipe and the heating device are operated at a relative speed for these series of operations, the heating temperature and the cooling temperature on the inner and outer surfaces change, and uniform processing cannot be performed. , It turned out to be extremely difficult to do so.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, the present invention has a straight pipe portion in which a metal pipe is bent while being heat-treated and both ends of the bent portion are subjected to the same heat treatment as the bent portion. It is an object of the present invention to provide a method for manufacturing a metal curved tube which can manufacture a metal curved tube having the above-mentioned process with continuous strokes.

[0007]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and its structure is such that a metal pipe to be bent is locally heated by an annular heating device having a cooling device. Both ends of the curved pipe portion are heated by heating and cooling immediately after heating, and a device for bending and deforming the pipe by giving a bending moment to the pipe while moving the heating part relatively in the longitudinal direction of the pipe. In a method for manufacturing a metal pipe having a straight pipe part of an appropriate length and subjected to the same heat treatment as a whole, the bending process is performed continuously with the heat treatment of the straight pipe part on the front end side of the pipe, and the bending process is performed. At the end of step, the tube is stopped, and while the heating device is moving backward, heat treatment is applied to the straight pipe part on the rear end side of the tube, and after all the steps of heat treatment and bending are completed, the tube that holds the tube Release the tube from the clamp during the release process Immediately before starting, the bending energy between the pipe and the device for applying the bending moment is eliminated, and in the case of manufacturing a large-diameter thick-walled metal curved pipe, heating is performed. The devices are placed inside and outside the tubes so that they can be driven in synchronism.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 is a plan sectional view showing a state in which a straight pipe portion of a front end of a metal pipe to be bent is being heat treated, FIG. 2 is a plan sectional view showing a state in which the bending process is started, and FIG. 5 is a plan sectional view showing a state in which the bending energy is released immediately before releasing the pipe, FIG. 4 is a plan sectional view showing a state where the pipe is released from the clamp and the straight pipe portion at the rear end thereof is heat treated, and FIG. 5 is a method of the present invention. FIG. 3 is a plan view of an example of an apparatus suitable for carrying out the method.

In the figure, reference numeral 1 denotes a tube whose whole is to be heat-treated while being bent, and 2 is a bending arm which swivels around a swivel center 3, and a clamp 4 for gripping the tip of the tube 1 is provided on the tip side. It is provided. Reference numeral 5 is a tube rear end support for supporting the rear end of the pipe 1, and 6 and 7 are heating devices for heat-treating the inside and outside of the pipe 1, both of which are equipped with an annular cooling device (not shown). 1 is heat-treated by cooling immediately after heating. Reference numeral 8 denotes a boom connected to the turning center 3 of the bending arm 2. By driving the boom 8, the turning center 3 can be moved back and forth (right and left in the figure). There is.

In FIG. 1, as described above, the heating devices 6 and 7 are arranged on the side of the bending arm 2 from the turning center 3 of the bending arm 2 in a state where the straight pipe portion at the front end of the pipe 1 is heat-treated. At the same time, the clamp 4 is released so as not to hinder the passage of the tube 1, and the tube 1 is heated from the inside by the heating devices 6 and 7,
While performing the operation of cooling immediately after heating, the tube rear end support 5 is advanced to heat-treat the front straight tube portion of the tube 1.

FIG. 2 shows a state in which bending of the pipe 1 having the front end straight pipe portion heat-treated as described above is started, and when the heat treatment of the straight pipe portion is approached, the pipe 1 and the heating devices 6 and 7 are moved at a relative speed. , The tube 1 is stopped, and the heating devices 6 and 7 are moved backward at the set speed. During this time, the clamp 4 grips the front end portion of the tube 1, and after the gripping is completed, the tube 1 is advanced at the set speed while the tube 1 and the heating devices 6 and 7 are kept at the relative speed, and as shown in the drawing, the heating device 6 , 7 are stopped at a position which is in line with the turning center 3, that is, a bending position, and the bending process is started.

In FIG. 3, the pipe 1 is bent from the above state by a conventional method, and when the bending is near the end, the pipe 1 and the heating devices 6 and 7 are stopped while keeping the relative speed.
The heating devices 6 and 7 are moved backward at a set speed. At the same time as the tube 1 is stopped, the rear end support base 5 is moved backward slightly by Δx ₁ to remove the bending energy generated during the bending process. Alternatively, with the rear end support 5 still stopped, the boom 8 is slightly advanced by Δx ₂ to remove the bending energy generated during bending, and the pipe 1 pops out when the clamp 4 is released. Prevent.

After the bending process is completed and the clamp 4 is released, as shown in FIG. 4, the tube 1 and the heating devices 6 and 7 are connected.
Takes the relative speed and stops the heating devices 6 and 7,
Is advanced at a set speed, and the straight pipe portion at the rear end of the pipe 1 is heat-treated to produce a metal curved pipe that is uniformly heat-treated as a whole.

In the above series of steps, the heating device 6,
In order not only to synchronize 7 accurately, but also to perform the entire machining accurately, control may be performed as shown in FIG. That is, in FIG. 5, reference numeral 9 is a propulsion device for applying a thrust to the pipe 1, and a chain wheel SW is attached to an output shaft of a drive portion 91 of the propulsion device, and a chain C having one end fixed to the rear end support 5 of the pipe 1 is attached. A thrust force is applied to the tube 1 by winding the chain wheel SW, and a moving distance sensor 10 for the tube 1 is attached to a rear end support 5. Then, the moving speed of the tube 1 detected by the sensor 10 is input to the controller 12 and is sent to the speed control unit 92 from there, and the driving unit 91 is operated by the servo motor DM ₉ and The tube 1 is always moved at a set speed. Further, the servomotors DM ₆ and DM ₇ are used to drive the heating devices 6 and 7, respectively, and the pulse generators PG ₆ and PG ₇ and the tacogenerators TG ₆ and T ₇ are used.
Combining G _7, control based on the sensor 10 for measuring the movement distance of the tube 1 - the La 12 is to synchronize the internal and external heating device 6, 7 in the series of operations. Reference numeral 11 is a load converter (load cell) attached to the chain C, which is used to remove the bending energy between the pipe 1 and the device for applying the bending moment.
The load on the chain C is detected, and when the removal is completed, the load is transmitted to the controller 12. In the figure, 20 is a guide roller for guiding the pipe 1, 61 and 71 are high-frequency transformers, 62 and 72 are speed control units, TG ₉ is a tachogenerator attached to a servomotor DM ₉ , PE. Is a bending angle detector attached to the turning center 3 of the bending arm 2.

By doing so, the pipe 1 becomes a metal curved pipe in which the curved pipe portion and the straight pipe portions before and after the curved pipe portion are uniformly heat-treated, and the bending energy generated in the pipe 1 by the bending process is eliminated. Therefore, even if the springback due to bending of the pipe 1 works, it can be eliminated.
Therefore, there is no problem when releasing the clamp 4.

In the above embodiment, the pipe 1 to be bent and heat-treated is heated from the inside and outside. However, this is applied to the thick and large diameter pipe 1, and the pipe 1 is relatively large. When the tube 1 is thin and has a small diameter, the tube 1 may be heated only from the outside.

[0017]

Since the present invention is as described above, the metal pipe can be uniformly heat-treated from the straight pipe portion at the front end to the straight pipe portion at the rear end through the curved pipe portion, so that high strength and high toughness can be obtained. It is suitable for manufacturing a large-diameter, thick-walled metal curved tube if the metal curved tube having the above can be manufactured, and particularly if the heating device is arranged inside and outside the tube.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing a state in which a front straight pipe portion of a metal pipe to be bent is heat-treated.

FIG. 2 is a plan sectional view showing a state where a bending process is started.

FIG. 3 is a plan cross-sectional view showing a state in which bending energy is released and bending energy is released immediately before releasing the tube from the clamp.

FIG. 4 is a plan sectional view showing a state in which the pipe is released from the clamp and the rear end straight pipe portion is heat-treated.

FIG. 5 is a plan view of an example of an apparatus suitable for carrying out the method of the present invention.

[Explanation of symbols]

 1 Metal tube to be heat treated and bent 2 Bending arm 3 Center of swiveling of bending arm 4 Clamp 5 Rear end support 6 Tube inner heating device 7 Tube outer heating device 8 Boom 9 Tube propulsion device 10 Tube Moving speed measuring sensor 11 Load converter 12 Controller PE Bending angle detector

Claims (2)

[Claims] 1. A metal pipe to be bent is locally heated by an annular heating device equipped with a cooling device and is cooled immediately after heating, while the heating part is relatively moved in the longitudinal direction of the pipe. A method for producing a metal pipe having straight pipe portions of appropriate lengths at both ends of the curved pipe portion and subjected to the same heat treatment as a whole by an apparatus for bending the pipe by applying a bending moment to the pipe In the above, the bending process is performed continuously with the heat treatment of the straight pipe part on the front end side of the pipe, the pipe is stopped at the end of the bending process, and the straight pipe part on the rear end side of the pipe is moved backward while moving the heating device backward. A device for applying a pipe and bending moment immediately after releasing the pipe from the clamp in the process of releasing the pipe from the clamp holding the pipe after the heat treatment and all the processes of heat treatment and bending are completed. It is characterized by releasing the bending energy between Method for manufacturing curved metal tube. 2. An inner surface heating device for heating the inner surface of the metal pipe to be bent and an outer surface heating device for heating the outer surface of the metal pipe are respectively arranged so as to be driven by individual driving devices. The metal pipe and the heating device are relatively moved from the front end straight pipe part of the metal pipe to the rear end straight pipe part through the bending portion, and the inner and outer surface heating devices are driven in synchronization, and the entire process is performed. The method for producing a bent metal tube according to claim 1, wherein the heat treatment and the bending are sequentially performed.