JP3624017B2 - Hot bending method for metal pipe - Google Patents

Description

[0001]
[Industrial application fields]
According to the present invention, a bent metal pipe is made to match or substantially coincide with a desired bending angle on a bending apparatus so that no correction is required after the pipe is taken out from the bending apparatus. The present invention relates to a bending method for a metal pipe.
[0002]
[Prior art]
As a method of bending a metal tube (hereinafter referred to as a tube), as shown in FIG. 1, the tip of the tube 1 to be bent is gripped by a clamp 4A of a pivotable arm 4 with a pivot shaft 3 as a center. After the tube 1 is heated in an annular shape with a heater (for example, a high-frequency inductor) 6, the tube 1 is advanced by the drive device 5, and immediately after the bending moment is applied and deformed, the heating unit is cooled by water cooling 6 </ b> A. There is known a method in which a bend angle is detected by an angle detector 3A attached to the turning shaft 3 and bent continuously until it matches a set angle. In the figure, 2 is a curved pipe portion, 5A is a tail clamp, 5B is a thrust meter, and 7 is a guide roller.
[0003]
By the way, when the above bending is performed with a bending specification as shown by a solid line in FIG. 2, for example, the first straight pipe portion N1, the bending angle θ, the second straight pipe portion N2, and the pipe end length L are the same as the bending specification. Ideally, it can be processed into
[0004]
However, in the above bending process, the actual bending angle θ often does not match the desired set value. Therefore, even if the straight pipe parts N1 and N2 can be processed as specified, the pipe end length is L , And often exceeds the tolerance for the desired value L, and becomes more noticeable as the straight pipe portions N1 and N2 are longer.
[0005]
In general, when performing the above-described bending, it is ideal that the setting value of the bending angle is adjusted to a desired angle.
(1) The pipe has a spring back (hereinafter referred to as SB) phenomenon that is bent into a spring shape upon receiving a bending moment during bending and is restored when the moment is released.
The amount of SB is a function of the pipe shape, material, bending angle, pipe length, and reaction force of each part, and it is not easy to specify.
(2) Even when bending the same pipe, the amount of SB is not constant depending on the processing conditions. That is, when the heating temperature is high or the processing speed is slow, the amount of SB tends to be small and vice versa.
(3) Even if the processing conditions and others are the same, due to differences in the pipe making method, or even if the pipe making method is the same, the SB amount is not constant due to differences in the pipe making manufacturer, etc. In many cases, the deviation between the bending angle of the bent pipe after the bending process exceeds an allowable value. For this reason, in the past, it was normal to bend by correcting the set angle with the correction value calculated from the actual results. However, the correction does not always enter the allowable value, but the bending pipe exceeding the allowable value is not corrected. Had the problem that its bend had to be corrected.
[0006]
Conventionally, when performing the above correction, first, after the bending process is completed, the bending tube is taken out of the processing apparatus, and a desired angle is marked on the surface plate in advance on a separately provided surface plate. Measure the difference between the crease angle and the angle of the bending tube, and if the bending angle of the bending tube is smaller than the crease angle, install a pushing device on the outside of the bending tube and heat the bending part with a heating device. In the same manner, the bending tube is deformed and corrected, and similarly, when the angle of the bending tube is large, a pushing device is provided inside the bending tube, and the bending tube is deformed and corrected outside thereof. Therefore, the conventional correction work requires many devices such as a surface plate, a heating device, a scoring device, and a pushing device in addition to the bending device, and the correction work also requires a great deal of time and cost.
[0007]
[Problems to be solved by the invention]
Therefore, the problem to be solved by the present invention is that a bent metal tube is measured and corrected on a bending device by measuring the difference between the bending angle and a desired bending angle, and the tube is removed from the bending device. It is an object of the present invention to provide a method of bending a metal tube that can be corrected.
[0008]
[Means for Solving the Problems]
The present invention has been made for the purpose of solving the above-mentioned problems, and its structure is an arm that can freely rotate a processing tip side through an appropriate heating device capable of locally heating a metal tube to be bent in an annular shape. While the metal tube is heated by the heating device, the heating unit is relatively moved by an appropriate moving device in the longitudinal direction of the tube , and further, this movement and the rotation of the arm accompanying it are performed. Immediately after applying a bending moment to the metal tube and deforming it, the metal tube hot- bending method for cooling the heating part with an appropriate cooling means indicates that the bending angle has reached a set value and the pivot axis of the arm Once detected by the angle detector attached to and immediately by releasing the tightening by the tail clamp or anti machining side tube by the mobile device while tightening the tail clamp By causing moved opens the energy deflection has occurred in the metal tube in a bending moment applying device constituted by said arm and said mobile device in the counter-processing side of the tube, and bending angle of the set angle and the tube The deviation is detected, and the bending angle is corrected by moving the pipe again to the machining side or the counter machining side to an angle obtained by adding the deviation angle to the set angle.
[0009]
Another configuration of the method of the present invention that can solve the above problem is to clamp the processing tip side to a rotatable arm through an appropriate heating device capable of locally heating a metal tube to be bent in an annular manner, While heating the metal tube by the heating device, the heating unit is moved relatively in the longitudinal direction of the tube by an appropriate moving device, and further, the metal tube is moved by this movement and the rotation of the arm accompanying it. Immediately after deforming by applying a bending moment to the metal tube, in the hot bending method of the metal tube in which the heating part is cooled by an appropriate cooling means, the angle at which the bending angle has reached the set value is attached to the pivot shaft of the arm Once detected by the detector, said stops moving and heating, then the deflection energy occurring in the metal pipe in a bending moment applying device constituted by said arm and said mobile device of the tube Open to the processing side, detect the deviation between the set angle and the bending angle of the pipe, and reheat it to the desired temperature for the desired length including the curved pipe part, and then bring the pipe back to the set angle plus the deviation angle. The bending angle is corrected by moving to the processing side or the counter-processing side.
[0010]
That is, the inventors of the present invention, as a result of diligent research aimed at solving the above-mentioned problems, when the bending angle is excessive or deficient, on the bending apparatus without removing the tube from the bending apparatus. As soon as the bending angle reaches the set value, the bending of the pipe is released to the opposite side, and the deviation between the setting angle and the actual bending angle of the pipe is detected. Is opened to the opposite side, the deviation between the set angle and the bending angle of the pipe is detected, and the tube is reheated to the desired temperature for an arbitrary length including the curved pipe section, and the deviation angle is added to the setting degree. It was learned that the bending can be corrected by moving it to the processing side when the angle is insufficient, and to the non-processing side when it is excessively bent, and the present invention has been completed. .
[0011]
Thus, in the present invention, when the bending angle is smaller than the set angle, the deviation angle is +, when the bending angle is larger than the set angle, the deviation angle is −, and when the deviation angle is +, the pipe is connected to the processing side. If the deviation angle is-, the tube is moved to the counter-processing side. In continuous bending with annular local heating of strips such as pipes, the bending angle is often insufficient due to the characteristics of the SB phenomenon. However, in the above bending, since the bending tends to proceed until the stress due to the bending energy and the plastic stress in the heated portion are balanced, the bending angle may be increased depending on conditions.
[0012]
【Example】
Next, an example of the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a state in which a bending angle is corrected after a tube is bent using an example of a known tube bending apparatus to which the present invention is applied, and FIG. 2 is a view showing a bending mode.
[0013]
In the method of the present invention, the tip of the metal tube 1 to be bent is gripped by the clamp 4A of the arm 4 that can be swiveled around the swivel axis 3, and the tube 1 is heated in an annular shape by the heater 6, while the tube 1 Immediately after 1 is moved forward by the drive unit 5 to impart a bending moment and deformed, the heating part (curved pipe part) 2 is cooled with a cooling jacket 6A by water cooling, and the bending angle θ is detected by the angle mounted on the turning shaft 3. If the bending is continuously detected until it is detected by the device 3A and matches the set angle, the tightening by the clamp 5A on the rear end side of the tube 1 is immediately released, and the bending between the tube 1 and the bending moment applying device is released. And detecting the deviation between the bending angle θ of the pipe 1 and the set angle and moving the pipe to the machining side or the counter machining side by a distance corresponding to the sum of the deviation angle and the deflection angle. The angle θ matches or substantially matches the set angle It is Unisuru of. When the bending angle θ is smaller than the set angle, the bending angle can be corrected by moving the pipe to the processing side, and when the bending angle θ is larger than the setting angle, the pipe is moved to the non-processing side. . Even if the tube 1 is moved to the non-working side until the thrust meter 5B is attached to the driving device 5 and the clamp 5A is tightened, the indicated value of the thrust meter, that is, the residual thrust becomes substantially zero. The same effect can be obtained.
[0014]
Thus, after the bending angle reaches the set angle, a procedure for releasing the bending between the metal tube and the bending moment applying device to the non-working side of the tube includes the following method. That is,
(1) Stop heating, and then immediately release the deflection.
(2) Without stopping the heating, the heating device and the cooling means are relatively moved by an arbitrary distance and then stopped. During this time, the bending is released.
(3) In (2) above, when the heating device and the cooling means are moved relative to each other by an arbitrary distance, the cooling is stopped and only the heating is performed, and during this time, the bending is released. I can do it.
[0015]
Further, after a series of bending processes are completed, the deflection between the tube 1 and the bending moment applying device is released to detect a deviation between the set angle and the bending angle of the tube, and at a desired temperature including the bent tube portion. The tube may be moved again to the processing side or the counter-processing side up to an angle obtained by adding a deviation angle to the set angle.
[0016]
In the above-described embodiment, an example is described in which the pipe 1 is bent while being moved. However, the present invention is not limited to this, and the present invention is also applicable to an apparatus that bends the arm 4 while moving. Is done.
[0017]
【The invention's effect】
The present invention is as described above. A bent metal tube is corrected by measuring the difference between the bending angle and a desired bending angle on the bending apparatus, and after the pipe is taken out of the bending apparatus, the correction is performed. Therefore, it is not necessary to take out the troublesome correction work after taking out the tube from the processing equipment after the bending process is completed. Can be greatly shortened, and the working cost can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing a state in which a bending angle is corrected after a pipe is bent using an example of a known pipe bending apparatus to which the present invention is applied.
FIG. 2 is a diagram showing a bending mode.
[Explanation of symbols]
1 Metal tube to be bent 2 Heating unit 3 Rotating axis
3A Bending angle detector 4 Arm
4A Clamp 5 Drive unit
5A Tail clamp 6 Heater
6A Cooling jacket 7 Guide roller

Claims (2)

The metal tube to be bent is passed through an appropriate heating device that can be heated locally in an annular shape, the processing tip side is clamped to a rotatable arm, and the heating portion of the tube is heated while the metal tube is heated by the heating device. Immediately after the metal tube is bent and deformed by this movement and the accompanying rotation of the arm , the heating unit is appropriately cooled in the longitudinal direction. In the hot bending method of the metal tube cooled by the means, when it is detected by the angle detector attached to the pivot shaft of the arm that the bending angle has reached the set value, the tightening by the tail clamp is immediately released, or, by moving the tube by the mobile device while tightening the tail clamp counter-processing side, bending moment constituted by the said and the arm moving device By opening the bending energy occurs in the metal pipe in the counter-processing side of the tube in the application device, to detect the deviation between the bending angle of the set angle and the tube, the tube again to an angle obtained by adding the deviation angle setting angle A method of hot bending a metal tube, wherein the bending angle is corrected by moving to the processing side or the counter-processing side. The metal tube to be bent is passed through an appropriate heating device that can be heated locally in an annular shape, the processing tip side is clamped to a rotatable arm, and the heating portion of the tube is heated while the metal tube is heated by the heating device. Immediately after the metal tube is bent and deformed by this movement and the accompanying rotation of the arm, the heating unit is appropriately cooled in the longitudinal direction. In the hot bending method of the metal tube cooled by the means, when the angle detector attached to the pivot shaft of the arm detects that the bending angle has reached the set value, the movement and heating are stopped, and then arm and the mobile device and detecting a deviation between the bending angle of the counter-processing side open to the set angle and tube deflection energy tube occurs in the metal tube in a bending moment applying device consists of In addition, it is reheated to a desired temperature for an arbitrary length including the curved pipe part, and the bending angle is corrected by moving the pipe again to the processing side or the counter-processing side to an angle obtained by adding the deviation angle to the set angle. A method of hot bending a metal tube.

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