JPS5857252B2 - Kinzoku Kanno Mageka Kohou Oyobi Dousouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a method for bending metal pipes such as steel pipes.

A widely used method for bending steel pipes is to pass the steel pipe to be bent through a narrow annular heating device, such as a high-frequency inductor, that can heat the pipe at high temperatures, and then cut the tip or an appropriate point in the middle of the pipe. The steel pipe is clamped to an arm which is freely rotatable and has its rotation axis within the plane of the heating device and whose length matches the bending radius of the steel pipe, and propels the steel pipe continuously and straight at a constant speed. There is an extrusion bending method in which the steel pipe is locally heated to a temperature capable of plastic deformation by the heating device and immediately cooled, and the steel pipe is bent by continuously plastically deforming it in the heating region.

Although this method has the advantage of being able to bend steel pipes efficiently, there are many variations in dimensional accuracy after bending due to the bending phenomenon, depending on the bending specifications.
There is a drawback that stable product accuracy cannot be obtained.

Therefore, the above-mentioned bending phenomenon refers to the bending phenomenon that occurs during the bending process.
As the bending angle gradually increases, the bent pipe becomes longer, but at the same time, the stiffness of the core decreases, and it is elastically deformed by the thrust load, which is the force that propels the steel pipe, and the curvature changes, causing the bending radius to change. This phenomenon refers to a phenomenon in which deviation occurs, and this phenomenon begins to occur, albeit slightly, when the bending angle exceeds about 45 degrees, and becomes quite noticeable when the bend angle exceeds 90 degrees.

Generally, in conventional extrusion bending of metal tubes, as shown in Figure 1, as the bending angle changes from θ to θ2 and the degree of bending progresses, the heating point B of the tube and the front end of the tube In other words, the length of the bent pipe section changes in proportion to the bending angle, but as the bent pipe section BL becomes longer, its rigidity decreases,
The thrust load P, which is the force that propels the pipe, is applied to the curved pipe part BL by R2 (
R is the standard bending radius), so the inventors of the present invention investigated the thrust load P and the micro-curved tube at the heating point B in order to find a way to prevent the occurrence of this deflection. As a result of a confirmation test on the correlation between the change in the curvature of the portion BL and the bending phenomenon, it was found that as the bending progresses and bending occurs in the bent pipe portion BL, the curvature at the heating point B changes, and this corresponds to that change. It was learned that a bending radius error occurs and a deviation occurs in the thrust load P.

In other words, as the bending process progresses, a bend occurs in the bent pipe, and the amount of bending increases because the steel pipe is pushed from behind and compressed in the axial direction, and the middle of the bent pipe bulges out. The so-called “
This is because due to phenomena such as "ramming", the amount of advancement of the straight pipe portion is wasted for these phenomena, and the rate of contribution to rotational propulsion of the arm decreases, resulting in a decrease in the amount of rotation of the arm.

Moreover, the amount of rotation of the steel pipe immediately after passing through the heating device is equal to the amount of rotation of the arm, but since the steel pipe is moved forward at a constant speed to keep the amount of heat input constant, the amount of rotation of the steel pipe immediately after passing through the heating device is equal to the amount of rotation of the arm. The bending radius in extrusion bending, which is expressed by the relationship between the amount of advance/the amount of rotation, must be expanded.

On the other hand, the relationship between the above-mentioned bending phenomenon, expansion of bending radius, and thrust load is as follows.

In other words, the propulsion speed for advancing the steel pipe is constant in order to keep the speed at which it passes through the heating device and the heating temperature of the covered pipe constant, so as long as there is no change in the amount of heat input or the dimensions of the steel pipe, etc. If the bending radius increases during bending, the bending moment required for bending will decrease, and the thrust load on the straight pipe portion forming the couple will decrease.

From this, if we detect that a deviation has occurred in the thrust load during bending, it means that we have detected that a deflection phenomenon has occurred in the bent pipe. By adding control so that the aforementioned decrease in the amount of rotation of the bending arm does not substantially occur, it is possible to prevent the occurrence of the bending phenomenon.

The present invention has been made for the purpose of providing a method for bending a metal pipe such as a steel pipe so that the bending phenomenon does not occur in the bent pipe part due to the gauze point as described above. The metal tube to be processed is passed through a heating device that has a narrow width and can heat at high temperatures, such as a high-frequency inductor, and its tip or an appropriate point in the middle is clamped to an arm that is rotatable and conforms to the bending radius. Immediately after being heated by a heating device, the tube is cooled down to a predetermined temperature and then propelled, thereby applying a bending moment to the tube and continuously plastically deforming the tube in the heating region. In this case, a clamp attached to the arm is moved or rotated, or a rotation axis of the arm is moved, and a thrust load that propels the metal tube is detected, and the bending If a deviation occurs in the thrust load as the machining progresses and is detected, the turning speed of the bent pipe can be reduced by forcibly moving or rotating the clamp, or moving the rotation axis of the arm. The present invention is characterized in that it substantially eliminates the deviation of the thrust load by changing the thrust load, thereby making it difficult for errors in the bending radius to occur in the bent portion of the metal tube.

On the other hand, the control principle according to the configuration of the present invention is as follows.

During hot extrusion bending, the heating temperature and advancement speed of the steel pipe are set and the propulsion load when the bending process is started is used as a reference value to detect the deviation value, while the deviation value is detected in proportion to the detected value. , by moving the clamp or arm provided on the arm that grips the steel pipe so as to increase or decrease the actual amount of rotation of the arm, so as to eliminate the above deviation value. It is something.

Next, embodiments of the method of the present invention will be described with reference to the drawings.

The device shown in FIG. 2 is a conventional extrusion bending device, in which 1 is a steel pipe to be bent, 2 is a support stand for supporting the pipe end of the device for continuously and straightly propelling the steel pipe 1, 3, 4 are a pair of guide rolls, and 5 is a heating device consisting of an annular high-frequency inductor that heats the steel pipe 1 from the outside to a high temperature in a narrow width.
Reference numeral 6 indicates a cooling device provided integrally with the heating device 5, 7 indicates a rotatable arm, and 8 indicates a rotation axis of the arm.
is disposed near a plane that includes the rotating shaft 8 and is orthogonal to the straight pipe portion of the steel pipe 1, and 9 is a clamp device installed on the arm 1.

In the conventional device configured as described above, the steel pipe 1 is passed between the guide rolls 3 and 3 and between the guide rolls 4 and 4 into the heating device 5, and the pipe end is supported on the support stand 2 of the propulsion device. On the other hand, depending on the specifications, the tip or intermediate portion of the steel pipe 1 is tightened to the arm 7 by a clamping device 9, and while being propelled continuously and straight at a constant speed by a propulsion device, it is narrowed by a heating device 5. After heating to a temperature that allows plastic deformation, the heating section of the steel pipe 1 is cooled by the cooling device 6, and a bending moment is applied to the steel pipe 1 by the thrust of the propulsion device and the guidance of the arm 7 to the heated region. The steel pipe 1 is bent by continuously plastically deforming it, and the steel pipe can be bent into any radius of curvature with high working efficiency without the need for bending molds or intensive heat work. As mentioned above, in machining with a large bending angle, the dimensional accuracy after the bending process varies due to the bending phenomenon.

There is a drawback that stable product accuracy cannot be obtained.

The device shown in FIGS. 3 to 5 bends a metal tube so that the bending phenomenon does not occur in the bent portion by eliminating the deviation that occurs in the thrust load during bending in the device. The device shown in FIG. 3 has a movable clamp device, and the devices shown in FIGS. 4 and 5 have a movable and rotatable clamp device.

In FIG. 3, reference numeral 10 denotes a support stand that supports the pipe end of a device for propelling the steel pipe 1, and 11 stands between the support stand 10 and the pipe end to support the steel pipe 1 by the propulsion device. 12 is a clamping device; 13 is a hydraulic cylinder for opening and closing the clamping device 12; 14 is an arm γ
15 is a hydraulic servo motor whose output shaft is connected to the screw punch 14 and which is installed on the arm 7. , 16 is a servo valve device, and servo valve 1
6 and the detection device 11 are electrically connected, and the servo motor 15 is driven by the servo valve device 16. When bending the steel pipe 1, a deviation occurs in the thrust load that propels the steel pipe 1, and the detection device detects the deviation. 11, the detection device 11 sends an electric signal to the servo valve device 16, which operates the servo valve device 16 to drive the servo motor 15, rotates the screw 14, and moves the clamp device 12 as shown in the figure. By moving the tube to the left or right, the deviation caused in the thrust load is eliminated, and the bending process is performed so that a bending phenomenon does not occur in the bent portion of the tube.

That is, during the bending process using the apparatus shown in FIG. 3, if it is detected that the bent tube section is bent outward and the thrust load is reduced, the clamp 12 on the arm 7 is moved to the rotating shaft 8 side. Let it happen.

When the clamp 12 moves toward the rotating shaft 8, the arc length of the curved pipe portion at this time is constant, and the arm γ does not freely support the shaft 8, so that the arm 7 moves as shown in FIG. is rotated clockwise, increasing the amount of rotation of arm γ at this point.

Since an increase in the amount of rotation of the arm 7 brings about an increase in the amount of turning of the steel pipe passing through the heating device, this increase in the amount of turning acts on the side that reduces the bending radius due to the relationship between the bending radius and the amount of advancement/the amount of turning. By the above-mentioned movement of the clamp 12, the bending process can be performed without causing bending errors caused by the bending phenomenon in the bending radius.

In addition, in response to an increase in the propulsion load, the clamp 12 is moved to the opposite side to the above, and the bending radius is controlled to be enlarged and corrected.

Next, FIGS. 4 and 5 show examples of the clamp device 12 in the device shown in FIG. A hydraulic cylinder for opening and closing the clamp installed in
20 is a hydraulic cylinder provided on the clamp body 18 for tightening the clamp body, 21 is a vertical shaft provided integrally on the bottom of the clamp body 18, 22 is a guide groove provided on the arm 7, and 23 is slidable in the guide groove 22. 24 is a nut integrally provided at the bottom of the sliding body 23, and 25 is a vertical shaft loose fitting hole recessed in the center of the sliding body 23 and into which a bearing meckle 26 is fitted;
21 is a bolt 2 that fits onto the vertical shaft 21 and is attached to the clamp body 18.
6 is the fixed worm wheel, 29 is the sliding body 2
The drum-shaped worm mounted on the worm wheel 2
It is meshed with 7.

30 is a hydraulic servo motor that rotates the worm 29;
Reference numeral 1 denotes a screw screw installed in the arm γ and screwed onto the nut 24, and 23 is a hydraulic servo motor whose output shaft is connected to the screw punch 31. In connection with the servo valve device 16, the detection device 11 detects a deviation in thrust load during bending of the steel pipe 1 and sends an electric signal to the servo valve device 16.
6 is activated to drive the servo motors individually or simultaneously, and when the servo motor 30 is driven, the worm 29 rotates to rotate the clamping device 11 via the worm wheel 27, and Servo motor 3
2, the screw punch 31 rotates, the sliding body 23 is guided by the nut 24 into the guide groove 22, and the clamping device 17
By moving both to the left or right in the figure, deviations in the thrust load are eliminated, and the bending process is performed to prevent bending.

That is, during bending using the apparatus shown in FIGS. 4 and 5, when it is detected that the bent pipe section is bent outward and the thrust load is reduced, the clamp 18 is adjusted according to the magnitude of the deviation value. It is rotated on the arm 7 in a direction opposite to the direction of rotation of the arm (counterclockwise in FIG. 4).

When the clamp 18 is rotated in the above direction, the chord length of the bent pipe section at this time is constant, and the arm 7 is rotated along its axis 8.
Since the arm 1 is freely supported by the arm 1, the arm 1 is rotated clockwise in FIG. 4, and the amount of rotation of the arm 7 at this point is increased.

The increase in the amount of rotation of the arm 7 is due to the increase in the amount of rotation of the arm 7.
Therefore, from the relationship of bending radius = advance amount / turning amount, the increase in the turning amount acts to reduce the bending radius, and as in the case of the device shown in Fig. 3, the bending Bending can be performed without causing bending errors caused by bending phenomena in the radius.

Contrary to the above example, when an increase in thrust load is detected,
The clamp 18 is controlled to rotate in the opposite direction.

Thus, the movement and rotation of the clamp 18 may be performed in combination according to the direction of the deflection phenomenon and the opposite direction of the thrust load deviation.

In the above embodiment, although not shown, the rotation shaft 8 of the arm 7 is installed on a slidable base, and the drive source for sliding the base is associated with the detection device 11, so that the rotating shaft 8 of the arm 7 is connected to the detection device 11 during the bending process. ,
If a deviation occurs in the thrust load, the drive source may be driven to move the base in the axial direction of the straight pipe portion of the steel pipe 1, and the arm 7 may be forcibly moved.

For example, if it is detected that the thrust load has decreased due to an outward deflection of the bent pipe during bending, the rotation axis 8 of the arm 7 should be moved toward the rear end of the steel pipe 1 (in the opposite direction to the forward direction of the steel pipe). move it to

The above movement of the rotating shaft 8 increases the amount of rotation of the arm 1 at this point, resulting in an increase in the amount of turning of the steel pipe passing through the heating device, so as in the case of the previous embodiment, this amount of turning increases. acts to reduce the bending radius, making it possible to perform control such that bending errors due to bending phenomena do not occur.

EXAMPLE When a gas pipe with a diameter of 60.5 mm was bent at a radius of 570 mm using the conventional method and the method of the present invention in which the thrust load is controlled by moving the clamp, the following results were obtained.

The present invention is as described above, in which a thrust load is detected during extrusion bending of a metal tube, and when a deviation in the thrust load is detected, the clamp provided on the arm is forced to close. By moving, rotating, moving and rotating, or forcibly moving the axis of rotation of the arm, even if the bending process progresses, deviations caused by the deflection phenomenon will not occur in the thrust load. Therefore, according to the present invention, the metal tube to be processed can be bent without causing a bending phenomenon, that is, an error in the bending radius. can get.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the principle of the method of the present invention, Figure 2 is a diagram for explaining the principle of the method of the present invention.
The figure is a plan view of a conventional device, FIG. 3 is a plan view of an apparatus for carrying out the method of the present invention, FIG. 4 is a plan view of a clamp device replacing the clamp device of the above device, and FIG. -A sectional view. 1...Steel pipe, 2...Pipe end support stand, 3
, 4... Guide roll, 5... Heating device, 6... Cooling device, 7... Arm, 8
...Rotation axis, 9...Clamp device,
10... Pipe end support stand, 11... Thrust load detection device, 12... Clamp device, 15...
... Hydraulic motor, 16 ... Servo valve device, 17 ... Clamp device, 22 ...
...Guide groove, 23...Sliding body, 24...
・Natsuto, 27... Wormwheel 29...
...Trumpet-shaped worm, 30 Bomota, 31... Screwdriver. 32... Hydraulic servo

Claims (1)

[Claims] 1. Pass the metal tube to be bent into a heating device that has a narrow width and can heat at high temperatures, such as a high-frequency inductor, and clamp its tip or intermediate point C to an arm that is rotatable and conforms to the bending radius. Immediately after being heated by the heating device, the iron pipe is cooled to a predetermined temperature while being propelled at a constant speed to apply a bending moment to the iron pipe while continuously plastically deforming the iron pipe in the heated region. In the method of When a deviation occurs in the thrust load as the bending process progresses and is detected, the bending pipe is turned by forcibly moving or rotating the clamp, or by moving the rotation axis of the arm. A method for bending a metal tube, characterized in that the speed is changed to substantially eliminate deviations in thrust load, thereby making it difficult for errors in bending radius to occur in the bent portion of the metal tube.