JP2743226B2 - Manufacturing method of metal curved tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal pipe having a straight pipe section which has been subjected to the same heat treatment as the bent section at both ends of the bent section by bending the metal pipe while being heat-treated. And a manufacturing method.

[0002]

2. Description of the Related Art Heretofore, a method of manufacturing a metal bent pipe in which a metal pipe is bent while being heat-treated and a straight pipe portion before and after the bent portion as well as the bent portion is continuously heat-treated is disclosed in the application of the present applicant. There is one described in JP-A-60-44054. According to this method, a heat treatment apparatus is arranged outside a metal pipe and moves at a constant speed relative to the pipe through a straight pipe section, a bent section, and a straight pipe section. The heat treatment can be uniformly applied to the entire bent pipe with a pipe.

Further, as a method of bending a thick-walled metal tube while heat-treating it, there is a method described in Japanese Patent Application Laid-Open No. 51-84766 filed by the present applicant. In this method, a heating device is fixed inside and outside of a metal tube, and heating and quenching are performed simultaneously from the inner and outer surfaces of the tube while moving the metal tube. 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 moved backward, and the tube is released from the clamp holding the tube. There is a case where a considerable amount of bending energy is 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 jumps out,
There is a problem in that the heat treatment temperature changes due to the roll, making uniform processing difficult.

In addition, the former method and the latter method are combined,
When performing heat treatment while bending a large diameter thick metal tube,
A heating device is arranged inside and outside the pipe, and heat treatment is performed continuously from the straight pipe part to the bent part and further to the straight pipe part.At the time of heat treatment of the straight pipe part, the pipe is released from the clamp, and the heat treatment of the bent pipe part is performed. At the time of bending, it is necessary to perform an operation of holding the tube by the clamp. However, if these series of operations are performed at a relative speed between the tube and the heating device, and the inner and outer surface heating devices are not precisely synchronized, the heating temperature and the cooling temperature on the inner and outer surfaces change, and uniform processing cannot be performed. However, it has been found that this is extremely difficult.

[0006]

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

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a structure in which a metal pipe to be bent is locally formed by an annular heating device having a cooling device. Heating and cooling immediately after the heating, and by moving the heating portion relatively in the longitudinal direction of the tube, applying bending moment to the tube, deforming and bending the tube, the both ends of the curved tube portion are bent. In the method of manufacturing a metal pipe having a straight pipe portion having 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 portion on the front end side of the pipe, and the bending process is performed. At the end of the process, the pipe is stopped, and heat treatment is performed on the straight pipe on the rear end side of the pipe while moving the heating device backward.After all the heat treatment and bending processes are completed, the pipe is removed from the clamp holding the pipe. Release tube from clamp during release process The bending energy between the pipe and the device for applying the bending moment is removed immediately before the pipe is bent. The devices are placed inside and outside the tubes so that they are driven synchronously.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan sectional view showing a state in which a front end straight pipe portion of a metal pipe to be bent is subjected to a heat treatment, FIG. 2 is a plan sectional view showing a state in which bending is started, and FIG. FIG. 4 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 in which the pipe is released from the clamp, and a rear straight section is heat-treated, and FIG. FIG. 2 is a plan view of an example of a device suitable for performing the above.

In the drawing, reference numeral 1 denotes a tube to be entirely heat-treated while being bent, and 2 denotes a bending arm which turns around a turning center 3. A clamp 4 for gripping the tip of the tube 1 is provided at the tip side. It is provided. Reference numeral 5 denotes a support for supporting the rear end of the pipe 1, and reference numerals 6 and 7 denote heating devices for heat-treating the inside and outside of the pipe 1, both of which are provided 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). I have.

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

FIG. 2 shows a state in which bending of the pipe 1 in which the front end straight pipe portion has been heat-treated as described above is started. Then, the pipe 1 is stopped while taking the heat, and the heating devices 6 and 7 are moved backward at the set speed. During this time, the front end of the tube 1 is gripped by the clamp 4, and after completion of the gripping, the tube 1 is advanced at the set speed while maintaining the relative speed between the tube 1 and the heating devices 6 and 7 again. , 7 are stopped at a position that is aligned with the turning center 3, that is, at a bending position, and the bending process is started.

FIG. 3 shows a state in which the pipe 1 is bent from the above state by a conventional method. When the pipe 1 reaches the vicinity of the end of the bending, the pipe 1 and the heating devices 6 and 7 are stopped while maintaining a relative speed.
Or it is a heating device 6, 7 is cause backward at a set speed, stop and the rear end support base 5 at the same time by reverse only slightly [Delta] x ₁ tube 1, thereby Dakkyo the flexures energy generated during machining, or rear end support base 5 remains stopped, Bed - to advance the arm 8 only slightly [Delta] x _2, to Dakkyo the flexures energy generated during machining, the tube 1 pops out when releasing the clamp 4 To prevent

When the clamp 4 is released after the bending process is completed, as shown in FIG.
Stops the heating devices 6 and 7 while maintaining the relative speed,
Is advanced at a set speed, and the straight pipe portion at the rear end of the pipe 1 is heat-treated, whereby a metal bent pipe having the whole heat-treated uniformly is manufactured.

In the above series of steps, the heating devices 6
In order to perform not only accurate synchronization but also accurate overall processing, control may be performed as shown in FIG. That is, in FIG. 5, reference numeral 9 denotes a propulsion device for applying a thrust to the tube 1, and a chain wheel SW having one end fixed to the rear end support 5 of the tube 1 by attaching a chain wheel SW to an output shaft of a driving unit 91. The thrust is applied to the tube 1 by winding it by the chain wheel SW, and the moving distance sensor 10 of the tube 1 is mounted on the rear end support base 5. And Thus, the moving speed of the tube 1, the sensor 10 has detected the control - are input to La 12, is sent from there to the speed control unit 92, Sa - Vomo - operates the driving unit 91 by data DM _9, The tube 1 is always moved at a set speed. Servo motors DM ₆ and DM ₇ are used for driving the heating devices 6 and 7, respectively, and pulse generators PG ₆ and PG ₇ and tacho generators TG ₆ and T 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. Numeral 11 denotes a load transducer (load cell) attached to the chain C, which removes bending energy between the pipe 1 and a device for applying bending moment.
This is for detecting the load applied to the chain C and transmitting it to the controller 12 when the removal is completed. 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 controllers, TG ₉ is a tacho generator attached to the servo motor 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 bent pipe in which the bent pipe section and the straight pipe sections before and after the pipe section are uniformly heat-treated, and the bending energy generated in the pipe 1 by the bending process is removed. Therefore, even if the springback caused by the bending of the pipe 1 works, this can be eliminated,
Therefore, there is no problem when the clamp 4 is released.

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

[0017]

Since the present invention is as described above, it is possible to uniformly heat-treat a metal pipe from a straight pipe at the front end to a straight pipe at the rear end through a curved pipe, and thus high strength and high toughness. In particular, if the heating device is arranged inside and outside the tube, it is suitable for manufacturing a large-diameter thick-walled metal curved tube.

[Brief description of the drawings]

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

FIG. 2 is a plan sectional view showing a state in which bending processing is started.

FIG. 3 is a cross-sectional plan view showing a state in which bending energy has been released immediately after a bending process has been completed and a pipe has been released from a clamp.

FIG. 4 is a plan sectional view showing a state in which a tube is released from a clamp and a rear straight tube portion is subjected to a heat treatment.

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]

 DESCRIPTION OF SYMBOLS 1 Metal pipe to be heat-processed and bent 2 Bending arm 3 Center of rotation of bending arm 4 Clamp 5 Rear end support 6 Inner tube heating device 7 Outer tube heating device 8 Beam 9 Pipe propulsion device 10 Tube Moving speed measuring sensor 11 Load transducer 12 Controller PE Bending angle detector

Claims (2)

(57) [Claims] 1. A metal pipe to be bent is locally heated by an annular heating device equipped with a cooling device and cooled immediately after heating, and the heating portion is relatively moved in the longitudinal direction of the tube. A method for producing a metal pipe having an appropriate length of straight pipe section at both ends of a curved pipe section and subjected to the same heat treatment by means of a device for imparting bending moment to the pipe and deforming and bending the pipe. At the end of the bending process, the pipe is stopped at the end of the bending process, and the heating device is moved backward to the rear end side straight tube portion of the pipe while the bending process is performed continuously to the heat treatment of the front end side straight pipe portion of the pipe. Apparatus for applying pipe and bending moment immediately after releasing the pipe from the clamp in the step of releasing the pipe from the clamp holding the pipe after the heat treatment and all the steps of the heat treatment and bending are completed. Characterized by removing the bending energy between Of manufacturing curved metal pipes. 2. An inner surface heating device for heating an inner surface of a metal pipe to be bent, and an outer surface heating device for heating an outer surface of the metal tube on the outside, respectively, and these are driven by individual driving devices. The metal pipe and the heating device are relatively moved from the front straight pipe portion of the metal pipe through the bent portion to the rear straight pipe portion, and the inner and outer heating devices are driven in synchronization with each other, and the entire process is performed. 2. The method according to claim 1, wherein the heat treatment and the bending are successively performed.