JP5834309B2 - Method and apparatus for compressing and bending metal tube - Google Patents

Description

  The present invention relates to a method and an apparatus for compressing and bending a metal tube, and more particularly, to a method and an apparatus for compressing and bending which can suppress metal thinning of the metal tube.

When a metal tube is bent, the thickness on the outer side of the bend decreases, and various methods and apparatuses have been developed to prevent this.
The invention described in Patent Document 1 (Japanese Patent Laid-Open No. 54-8154) describes that the thickness can be reduced to zero by bending while applying a compressive force.

Patent Document 1 shows that there are cases where there are one drive device and two drive devices. For each case, a diagram showing the principle of compression bending is shown in FIG. It is shown in FIG. 6 and FIG.
FIG. 5 is a diagrammatic view when there is one drive device, and FIGS. 6 and 7 are diagrammatic views when there are two drive devices.

  The invention of Patent Document 1 is used as a compression bending method for a metal tube, which has an excellent drive part at one place and two places, and in particular, a compression bender with two drive parts has a wide range of applications and operability. Because it is good, it is most often used. On the other hand, a compression vendor having a single drive unit is mainly used as a single-function compression vendor.

  Incidentally, the basic principle of the compression bender in which the drive device described in Patent Document 1 is provided will be described with reference to FIG.

FIG. 3 is an explanatory diagram of the prior art of a compression bender with a single drive unit, which is a rewrite of FIG. 5 of Patent Document 1 for explanation.
In FIG. 3, a hydraulic cylinder 9 ′ (bending cylinder) is mounted at point D.
The basic principle of a compression bender with one drive is as follows.
That is, the bending moment M is
M = (R−r) P (1)
On the other hand, M is a moment for bending the pipe (1) in the heating section A.
M = SZ (2)
here,
S is the plastic deformation resistance at the heating temperature,
Z is a section modulus of plastic deformation of the tube (1).
From equations (1) and (2)
P = SZ / (R−r) (3)
It becomes.
When r = 0, that is, when the point D moves to the position of the point F (normal bending), the value of P is P ₀ .
P ₀ = SZ / R = M / R (4)
And
Dividing equation (3) by equation (4) gives
P / P ₀ = R / (R−r) = n (5)
It becomes.
Therefore, the value of P increases as the value of n increases, that is, as r approaches R.
The value of n can be increased as necessary, but in order to suppress the thinning rate to 0% by bending with a bending radius of 1.5 Dr (bending radius R is 1.5 times the tube diameter), it is practically It has been found that it should be about 5-6.

The advantage of this system is that the structure is simple because the drive section is only required in one place.
Here, the radius r of the compression wheel for setting the thinning rate to 0 is obtained by assuming that the value of n is 6.
When r is obtained by converting equation (5),
r = (n-1) R / n = 5R / 6
It becomes.
It can be seen that when the radius r of the compression wheel is 5/6 of the bending radius R, n = 6.
Accordingly, the tensile force P ₁ of the hydraulic cylinder 9 'shown in FIG. 3, if the 5/6 of the radius R bending radius r of the compression wheel
P ₁ = nP ₀ = 6P ₀
It becomes.
Of course, this P ₁ is equal to the compressive force P applied to the metal tube.
As described above, this method is a very effective method for preventing the thinning because a large compressive force can be generated by bringing the radius r of the compression wheel close to the bending radius R.
However, as shown in the figure, since the drive device uses one hydraulic cylinder 9 ', the hydraulic cylinder 9', the conductive member 11 and the compression wheel 14 must withstand the compressive force and become extremely large. There are also some drawbacks. The compression bending method in the case of a single drive device is used for bending austenitic stainless steel pipes, and the structure of the device is shown in FIG. 1 of Patent Document 2 (Japanese Patent Publication No. 58-927). Has been.

The basic principle of a compression bender with two drive units will be described with reference to FIG.
FIG. 2 is an explanatory diagram of the prior art of a compression bender with two driving parts, and is rewritten from FIG. 6 and FIG. 7 of Patent Document 1 for explanation.

In FIG. 2, a hydraulic cylinder 9 '(brake cylinder) is mounted at point D, and a hydraulic cylinder 9 (bending cylinder) is mounted at point F.
The relationship between the thinning rate α and the compression force P = P ₁ + P _{2 applied} to the heating part A is well known and has already been theoretically arranged and used on a daily basis, but the desired thinning rate α is set. Since the calculation of the compression force P is performed using complicated numerical calculations and some correction factors, an advanced calculation function is required, and in order to ensure bending accuracy, it is in the micron order (0.001 mm It is necessary to use a hydraulic cylinder or the like having a servo valve having a positioning accuracy of (unit). For this reason, the conventional device has a drawback that the control device and the drive unit are extremely expensive.

As described above, the conventional metal tube bending method is widely used for either one or two drive units, and in particular, a compression bender having two drive units has an applicable range. It is widely used because it is wide and easy to operate. However, there is a problem that unit production is low and the price is high due to its structure and poor operability.
For example, in recent years, there has been an increase in demand for special elbows that suppress the thinning by attaching short pipes to both ends of commercial elbows in order to improve the efficiency of piping work. There was a problem that could not cope with the cost.
There is a method to increase the number of vendors by simply increasing the number of vendors, but the conventional drive unit has the following problems in both the compression bender with one drive unit and the compression bender with two drive units. There is a point.

In the case where the drive device is a single compression bender, as shown in FIG. 12, the tension P is applied to the compression wheel 14 so that the axial compression force applied to the metal tube 1 necessary to obtain a desired thickness reduction rate is P. A compression force P (which is clearly P-P ₁ from the figure) necessary to obtain a desired thickness reduction rate can be applied only by installing a drive device 9 '(bending cylinder) for adding ₁ .
It can be said to be a compression bender suitable for the production of inexpensive special elbows because it is simple and easy to operate because it only requires a single drive. However, since the necessary compression force P is generated by one drive device, there is a disadvantage that the conductive member 11 and the compression wheel 14 connected to the drive device 9 'become extremely large when the large-diameter pipe is bent. Therefore, even if the drive device is a single compression vendor, it becomes quite expensive, and it is economically difficult to respond by increasing the number of vendors for mass production.

In the case where the drive device is a compression bender at two locations As shown in FIG. 13, in order to set the axial compression force applied to the metal tube 1 necessary for obtaining a desired thickness reduction rate to P, the tension P is applied to the pivot shaft 6. drive 9 adding ₁ (bending cylinders), tensioning P ₂ to the compression wheel 14 drive 9 'must be equipped with (brake cylinder), also required the compression to obtain the desired thinning rate A control device with a high-precision calculation function (not shown) having a function of obtaining the force P and the tensions P ₁ and P ₂ using a built-in calculation software and controlling and adjusting based on the calculation result during bending. ), Etc., and expensive equipment was necessary.
For this reason, a compression bender with two drive units is very expensive, and it is extremely difficult to increase the number of vendors for mass production.

  From the above viewpoint, in order to mass-produce special elbows (bending products of metal pipes) with short pipe parts (neck) at both ends at low cost, the structure is simple, the productivity is high, and the price is low. There was an urgent need to develop a bending machine.

JP-A-54-8154 Japanese Patent Publication No.58-927

  The present invention has been made in view of such a situation, and its purpose is to reduce the thickness of a special elbow having necks at both ends and to enable mass production at a low cost, with a simple structure and productivity. It is to provide a bending apparatus and a bending method that are expensive and inexpensive.

As a result of intensive studies on the above problems, the present inventor has obtained the following knowledge.
That is, when bending a metal tube with a thinning rate α, a perpendicular foot drawn from the bending center with respect to the metal tube to be bent is a point A, and the tip of the metal tube is a specific position in front of the point A. In this case, the bending arm that is rotatable around the bending center is clamped so that the effective radius becomes a predetermined bending radius R, and the bending arm has an effective radius that shares the center of rotation with the bending arm. At r, a compression wheel such as a pulley, a chain wheel, or the like having r = R + e larger than the bending radius R by a deviation e calculated by the following equation (1 · 1) is fixed or fitted, and the metal The rear end of the metal pipe is clamped to a tail clamp device on the base located behind the pipe, and a conductive member such as a chain or a steel cable is supported by the compression wheel, and the base on the base. Deviation e away from the center of the metal tube After connecting the slack adjusting device and the bending arm provided in the apparatus, the conductive member is stretched and fixed in a straight line using the slack adjusting device, and then the metal tube is moved using a suitable driving device, Since a force P ₂ is generated in the driving device and bending is started, a reaction force P ₁ is induced in the conductive member, so that the compression force P = P ₁ + P ₂ which is the sum of both is applied to the metal pipe. The power of is given.
Even if the metal tube is bent while being narrowly heated by an appropriate heating device at the point A while the compressive force P is applied, the distance between the base and the bending center is gradually reduced. It has been found that the thickness at the position of the deviation e is kept at the blank thickness because the elongation is suppressed and does not change during bending.

  Incidentally, the looseness adjusting device has a screw jack-like configuration in which a stat bolt having one end of the node 12 connecting the conductive member is passed through a bearing fixed to the looseness adjusting device and tightened with a nut. Of course, the screw jack may be replaced with a hydraulic jack.

  Further, the looseness adjusting device is configured to be movable in the direction perpendicular to the metal tube so that the deviation e can be set appropriately. (Not shown)

  The relationship between the deviation e and the thinning rate can be obtained very easily geometrically by the formula (1 · 1) obtained using FIGS. 8 (a) and 8 (b). It has been found that it is possible to easily perform highly accurate compression bending without the need to determine the compression force P based on advanced calculations and past data.

In addition, the reaction force P ₁ induced by the conductive member is obtained by subtracting the driving force P ₂ from the required compressive force P. Therefore, the stress applied to the conductive member and the compression wheel can be reduced, and the bending apparatus can be downsized. We found that it can be simplified and priced down.

In addition, if a conductive member such as a chain or steel cord is stretched during bending, the reaction force will be reduced and the desired thickness reduction will not be obtained. However, the deviation e is set to be large in consideration of the elongation of the conductive member during bending. I also found out that this could be solved.
The invention of claim 1 of the present invention has been made based on the above knowledge.

As described above, in order to prevent the reduction of the thinning rate due to the elongation of the conductive member, the deviation e may be set in consideration of the elongation of the conductive member, but when the permanent deformation occurs in the conductive member due to repeated use There is a disadvantage that the deviation e cannot be set accurately.
In order to prevent the reduction of the thinning rate due to permanent deformation of the conductive member, a load cell is set on the conductive member, and the tension corresponding to the reaction force generated during bending is applied to the conductive member using a slack adjusting device and stretched. Later, it was found that this could be solved by bending. It has been found that the load cell may be attached to the arm clamp side of the conductive member or in the vicinity of the node on the intermediate clamp side.
The invention of claim 2 has been made based on the above findings.

A metal pipe compression bending apparatus for carrying out the inventions of the first and second aspects has the following configuration.
That is, a heating device that heats a narrow region in the longitudinal direction of the metal tube to be bent, a device that moves the heating device, and the forward point A of the perpendicular line drawn from the bending center with respect to the metal tube. A rotatable bending arm that clamps a specific position of the metal tube, a compression wheel that shares the center of rotation with the bending arm, a base located behind the metal tube, and the metal disposed on the base A tail clamp device for clamping the rear portion of the pipe, a slack adjusting device provided on the base at a position separated from the center of the metal pipe by a deviation e calculated by the following equation (1 · 1), and the slack adjustment A conductive member connected to the bending arm in a state of being supported by the compression wheel starting from a device, and a drive device that varies the distance between the base and the bending center.

  The basic principle of the present invention will be described.

The device of the present invention has a structure in which the drive device is provided at one place and the reaction force generating mechanism is provided at the other place.
FIG. 1 is a diagram for explaining the basic principle of the present invention.
FIG. 1 shows a structure in which the hydraulic cylinder 9 ′ shown in FIG.

As shown in FIG. 1, the case where the hydraulic cylinder 9 ′ is removed and the conductive member 11 is fixed at the point D and bent is described.
As shown in FIG. 1, the conductive member 11 is stretched in a straight line parallel to the metal tube 1 and bent on a compression wheel 14 in which the effective radius r is larger than the bending radius R by a desired deviation e by r = R + e. When processed, a reaction force (braking force) P ₁ is generated in the conductive member 11, and a tensile force (bending thrust) P ₂ is generated in the hydraulic cylinder 9.
The compressive force P applied to the metal tube is
P = P ₁ + P ₂
In this case, the values of P ₁ and P ₂ are obtained.

Comparison of the effects of the conventional invention with one drive device and the present invention having the reaction force generation mechanism with one drive device As is clear from the above examination, the bending thrust in the case of one drive device is an expression ( From 5) P ₁ = nP ₀ = P
On the other hand, the bending thrust P = P ₁ + P ₂ in the case where the driving device of the present invention has a reaction force generation mechanism even at one location, and the reaction force generation mechanism of the reaction force generation mechanism as shown in equations (1 · 3) and (1 · 4). because it is distributed to the tensile force P ₂ of the reaction force P ₁ and the hydraulic cylinder tensile force P ₂ is naturally small.

  As described above, in the present invention, although the drive device is in one place, the compression load is divided into two places, the load applied to the drive device can be greatly reduced, and the conductive member connected to the drive device and the drive device, There is a remarkable effect to reduce the compression wheel. Incidentally, the compression load applied to the driving device can be reduced to 3/8 when n = 6 (realizing a thinning rate of 0) is assumed, compared with the case where the driving device is a single conventional device. Become.

However, FIG. 1 uses a diagram for explaining the basic principle, and the metal tube is also shown by a single line. This is drawn for the sake of convenience, assuming that the bending neutral axis of the metal tube is on the center line of the metal tube. However, when the compression bending is actually performed, the neutral axis of the bending of the metal tube increases as the compressive force increases. Therefore, the bending thrust P ₂ of the present invention calculated using a series of formulas shown in [Equation 2] and [Equation 3] differs from the actual measurement value.
However, the fact that the neutral axis of the bending moves to the back side of the metal tube indicates that the bending R has expanded, and naturally the bending thrust decreases. This further enhances the effectiveness of the present invention.
A series of formulas shown in [Formula 2] and [Formula 3] are reference formulas for explaining the basic principle in an easy-to-understand manner. The bending thrust P of the conventional apparatus having one hydraulic cylinder and the bending thrust of the present invention are shown in FIG. comparisons must be determined using measured values of the bending thrust P _2.

Setting the bending thrust In the conventional method, the bending thrust must be set in advance by calculation or past bending data in accordance with the thinning rate.
Even in the present invention, it seems that the bending thrust must be set in advance according to the formula (1 · 4). However, if the position of the deviation e is set geometrically and bending is performed, a desired thickness reduction rate can be obtained. This is not necessary since the hydraulic cylinder's tensile force P ₂ (bending thrust) is automatically generated as much as necessary.

According to the present invention (Claim 1),
The metal thinning rate can be easily adjusted by simply suppressing the elongation of the metal tube that occurs at the position of deviation e from the center of the metal tube during bending with a conductive member such as a chain or steel cable (simple The thinning rate can be easily adjusted by means).
Compared to a conventional bending device with one driving device, the conductive member, compression wheel, etc. connected to the driving device can be made smaller, so that the device can be reduced in weight.
In addition, there is no need to use a high-precision drive device compared to a conventional bending device with two locations, and it is not necessary to install a control device with a calculation function, so the structure of the device is simplified and reduced in weight. Therefore, it is possible to manufacture a compression bending apparatus that is lightweight, easy to operate and high in productivity at low cost.
Therefore, by using this apparatus, it is possible to mass-produce a bend pipe (metal pipe bent product) like an elbow with a neck at a low cost.
In addition, according to the present invention (Claim 2), it is possible to eliminate the influence of the elongation of the conductive member such as the chain and the steel cord generated during the bending process, so that it is possible to realize the production of the bend pipe having a stable thickness reduction rate. .

Embodiment 1
FIG. 4 is an explanatory view when the invention of claim 1 is carried out using a metal pipe compression bending apparatus that fixes a metal pipe and moves an arm and a heating device to bend the metal pipe. This example is a case of vertical bending.
4A is a diagram for explaining a state immediately before bending, and FIG. 4B is a diagram for explaining a state during bending.

In FIG. 4 (A), the metal tube 1 is clamped to clamps 3 and 7 provided on both ends of the heating unit.
The clamps 3 and 7 are connected to the conductive member 11.
The conductive member 11 means a conductive member of force such as a chain or a steel cable, and this figure is a case of a chain.
The conductive member 11 is connected to the nodes 12 and 13 provided on the clamps 3 and 7, and the conductive member 11 and the nodes 12 and 13 are on an axis larger than the bending radius R of the metal tube 1 by a deviation e on the bending outer side. In the state where the transmission member 11 is supported by the compression wheel 14 concentric with the swivel axis 6 of the bending arm 4 and adjusted by the slack adjustment device 18 so as to be positioned and in a straight line. While driving the hydraulic cylinder 9 disposed on the table 8 and pulling the moving table 15, while heating and cooling the metal tube 1 with the heating device 19, the bending force is applied to the metal tube 1 while moving the heating device 19 relatively. in addition the bending is, the sum of the cylinder tension P ₂ in lot _10, conductive member 11 to the reaction force P ₁ is generated, the heating unit thrust P ₂ in (bend point a) bending and the reaction force P ₁ of the metal pipe 1 A compressive force P is applied.
By applying this compressive force P, the metal tube 1 is suppressed from thinning with high accuracy, and a highly accurate curved tube is formed.

The deviation e can be obtained by the following equation (1 · 1).

  By setting the thinning rate α to a predetermined value in advance, e corresponding to α can be obtained.

The relational expression between the deviation e and the thickness reduction rate α is obtained as follows from FIG.
FIG. 8A is a cross-sectional view of a metal tube when vertical bending is performed, and FIG. 8B is a cross-sectional view of the metal tube, from a bending neutral axis and a center of the metal tube to ensure a desired thickness reduction rate. It is a figure which shows the relationship of deviation e.
EE is a neutral axis position where the wall thickness does not vary. A tensile stress acts on the hatched portion and a compressive stress acts on other portions.

The thickness reduction rate α can be derived from the following equation, where the thickness t _{0 of} the metal tube, the thickness t _t on the T side of the bent tube, and the average radius of the metal tube are ρ.

Example 1
An example of calculating the thinning rate and deviation and an example of actual compression bending will be described.
To set R = 3ρ and α = 0, assuming that the average radius of the metal tube 1 is ρ, the bending radius R is ν times ρ, and the deviation e is χ times ρ, χ = 1−α from equation (1 · 5) (Ν + 1) = 1
e = ρ
What is necessary is just to set e in the position of the average radius (rho) of a metal pipe.

Using the apparatus of FIG. 4, e is set at the position of the average radius ρ of the metal tube, and the STPG 38 of the steel material, the dimensions are the outer diameter 165.2 mm, the wall thickness 9.3 mm, the bending radius R is 234 mm, Variations in the thickness of the back surface of the metal tube when the bending angle was 90 ° and the heating temperature of the bent portion was 950 ° C. were as follows.
The thickness of the metal tube after processing was measured with an ultrasonic wall thickness meter at three positions 10 °, 45 °, and 80 ° from the boundary between the straight tube and the bent tube at the beginning of bending.
The measured values of the wall thickness at the three locations are all within the range of 9.3 mm ± 2%, and this value is the thickness of the metal tube when the hydraulic cylinder is bent with one conventional device. It was within the range of variation.

Results From the above results, it was confirmed that the calculated values were consistent with the actual bending data.
When the bending thrust applied to the hydraulic cylinder was measured, the hydraulic cylinder was reduced to approximately 30% of the conventional device at one location.

Further, by using the apparatus of FIG. 4, e is set at the position of the average radius ρ of the metal tube, the STPG 38 of the steel material, the dimensions are the outer diameter 139.8 mm, the wall thickness 8.1 mm, and the bending radius R is The thickness variation of the back surface of the metal tube when compression bending was performed at 198 mm, a bending angle of 90 °, and a heating temperature of the bending portion of 950 ° C. was as follows.
The measurement of the thickness of the metal tube after processing is the same as in Example 1.
The thickness variation was 8.1 mm ± 2%.
This value was within the range of variation in wall thickness when the hydraulic cylinder was bent with one conventional device.

Results From the above results, it was confirmed that the calculated values were consistent with the actual bending data.
When the bending thrust applied to the hydraulic cylinder was measured, it was in good agreement with the calculated value, and the hydraulic cylinder was reduced to approximately 30% of the conventional device with one location.

Example 2
Another embodiment of compression bending calculated in the same procedure as in Embodiment 1 will be described.
In order to set R = 3ρ and α = 0.05, assuming that the average radius of the metal tube 1 is ρ, the bending radius R is ν times ρ, and the deviation e is χ times ρ, χ = 1 from Equation (1 · 5) −α (ν + 1) = 1−0.05 (3 + 1) = 0.8
e = 0.8ρ
What is necessary is just to set e to the position of 0.8 times the average radius (rho) of a metal pipe.

Using the apparatus of FIG. 4, e is set at a position 0.8 times the average radius ρ of the metal tube, and the steel type STPG38 of the steel material, the outer diameter of the metal tube is 138.9 mm, and the wall thickness is 8.1 mm. The bending radius R was 198 mm, the bending angle was 90 °, the heating condition of the bending portion was 950 ° C., and the variation in the thickness of the back surface of the metal tube was as follows.
The measurement of the thickness of the metal tube after processing is the same as in Example 1.
The variation in wall thickness was 7.7 mm ± 2%.
This value was within the range of variation in wall thickness when the hydraulic cylinder was bent with one conventional device, as in Example 1. When the bending thrust applied to the hydraulic cylinder was measured, it was in good agreement with the calculated value, and the hydraulic cylinder was reduced to approximately 40% of the conventional device with one location.

Results From the above results, it was confirmed that the calculated values were consistent with the actual bending data.

Example 3
Another embodiment of compression bending calculated in the same procedure as in Embodiment 1 will be described.
To set R = 3ρ and α = 0.1, assuming that the average radius of the metal tube 1 is ρ, the bending radius R is ν times ρ, and the deviation e is χ times ρ, χ = 1 from equation (1 · 5) −α (ν + 1) = 1−0.1 (3 + 1) = 0.6
e = 0.6ρ
What is necessary is just to set e to the position of 0.6 times the average radius (rho) of a metal pipe.

Using the apparatus of FIG. 4, e is set at a position 0.6 times the average radius ρ of the metal tube, and the steel grade SGP of the steel material, the outer diameter of the metal tube 114.3 mm, and the wall thickness 4,5 mm The bending radius R was 161 mm, the bending angle was 90 °, the heating condition of the bending portion was 950 ° C., and the variation in the thickness of the back surface of the metal tube was as follows.
The measurement of the thickness of the metal tube after processing is the same as in Example 1.
The variation in thickness was 4.1 mm ± 2%.
This value was within the range of variation in wall thickness when the hydraulic cylinder was bent with one conventional device, as in Example 1. When the bending thrust applied to the hydraulic cylinder was measured, it was in good agreement with the calculated value, and the hydraulic cylinder was reduced to approximately 45% of the conventional device with one location.

result

From the results of Examples 1 to 3, the calculated values and the actual machining data are matched with high accuracy even if the set values of the steel type, thickness, outer diameter, bending radius, and thickness reduction rate of the metal pipe change. I was able to confirm.
Also, the bending thrust applied to the hydraulic cylinder was in good agreement with the calculated value, and it was confirmed that the hydraulic cylinder was reduced from the conventional device at one location.

  As metal materials to be bent in the present invention, round steel pipes, square steel pipes and other pipes, H-shaped steels, I-shaped steels, L-shaped steels, C-shaped steels and other various shapes, various cross-section bars, plates, etc. Arbitrary strips that can be subjected to inter-bending can be targeted.

A flame heating device, a high-frequency induction heating device, or the like can be used as appropriate as a device for rapidly heating the longitudinal narrow region of the metal strip to be bent according to the present invention, but the high-frequency induction heating device is most preferable. .
The use frequency of the high-frequency induction heating device is preferably 1 to 20 KHz. When the metal strip is a steel material, the heating temperature is preferably in the range of 850 to 1100 ° C.

In the present invention, since the conductive member 11 is stretched and fixed in a straight line by the slack adjusting device 18, one hydraulic cylinder which has been conventionally required can be omitted. It can be simplified and the manufacturing cost of the device can be greatly reduced.
Furthermore, since the necessary compression force is shared by the conductive member 11, the tension applied to the conductive member 11 and the thrust of the hydraulic cylinder 9 can be reduced, so that the device can be downsized and the drive device and hydraulic cylinder can be downsized. This also contributes to a reduction in device manufacturing costs. Note bending when the conducting member 11 during processing extending so desired thinning rate by reducing the reaction force P ₁ is can not be obtained, in this case, the deviation e in anticipation of growth of the conducting member 11 in advance bent You can set more.

Table 1 below shows comparison data when the same metal pipe is bent using the conventional invention apparatus requiring two hydraulic cylinders and the present invention apparatus having one hydraulic cylinder.
The material of the metal tube used is steel material STPG38, the dimensions are an outer diameter of 165.2 mm, a wall thickness of 9.3 mm, a bending angle of 90 °, and the heating temperature of the bent portion is 950 ° C. The thinning rate was set to 0%.

  From the results in Table 1, the present invention has the same bending quality (variation in thickness of the thinned portion) compared to the conventional device, and can greatly reduce the manufacturing cost of the device, thereby reducing the bending cost of the product. It was confirmed that it could be greatly reduced.

Embodiment 2
As described above, in order to prevent the reduction of the thinning rate due to the elongation of the conductive member, the deviation e may be set in consideration of the elongation of the conductive member, but when the permanent deformation occurs in the conductive member due to repeated use There is a disadvantage that the deviation e cannot be set accurately.
FIG. 5 is an explanatory diagram when implementing a means (invention of claim 2) for preventing a reduction in thickness reduction due to permanent distortion of a conductive member. This figure shows the case of vertical bending.
5, by setting the load cell 20 to the intermediate clamping side of the conductive member 11, preliminarily measured reaction force P ₁ exerted on conducting member in bend test, at the start, it was measured in the conduction member slack adjuster When starting the bending added the same load and the reaction force P _1, it is possible to suppress the reduction in the thinning rate due to elongation of the conductive member during bending.

Embodiment 3
FIG. 6 is an explanatory diagram when the compression wheel is a wheel.
The diameter of the chain wheel (PCD = Pitch Circle Diameter) is determined by the number of teeth of the chain wheel and cannot be adjusted to an arbitrary value, so wheels are used when fine adjustment of the radius is necessary.

Embodiment 4
FIG. 7 is an explanatory view of another embodiment for carrying out claim 1 of the present invention.
4 and 5, the base 8 and the metal tube 1 are fixed, but in this embodiment, the base 8 moves on the rail 17 and the metal tube 1 moves.
The drawing shows a case of vertical bending. Since the metal tube moves, the heating device 19 does not need to move.

Embodiment 5
FIG. 9 is a cross-sectional view of the metal pipe during bending standby in which the conductive member 11 is set at the position of the deviation e from the center of the metal pipe. However, in order to clarify the relationship between the metal tube 1 and the conductive member 11, the arm clamp 3, the bending arm 4 and the like are removed from the front view of FIG.
(A) is the figure which has arrange | positioned the conduction member 11 and the compression wheel 14 to right and left.
(B) is the figure which has arrange | positioned the conduction member 11 and the compression wheel 14 to the left.
Any one may be selected in consideration of mechanical strength and workability. In particular, in the case of horizontal bending, if the conductive member 11 and the compression wheel 14 are disposed below, the upper part is opened, and the workability becomes more suitable.

Embodiment 6
FIG. 10 is a cross-sectional view of a metal tube and a bending radius when vertical bending is performed with a deviation e to set the desired thickness reduction rate to α in the present invention. However, in order to clarify the relationship between the metal tube 1 and the conductive member 11, the arm clamp 3, the bending arm 4 and the like are removed from the front view of FIG.

Embodiment 7
FIG. 11 is an explanatory diagram showing a relationship with the compression wheel 14 when the conductive member 11 is set at a position of an arbitrary deviation e from the metal tube center.
The case where EE is set to the deviation e ₁ and the case where the deviation ee is set to the deviation e ₂ are illustrated.
The thickness reduction rate is smaller when the deviation e ₂ is set than when the deviation e ₁ is set.
However, parts that are unnecessary for clarifying the relationship between the metal tube 1 and the conductive member 11 are removed from the front view of FIG.

FIG. 1 is a diagram for explaining the basic principle of the present invention. FIG. 2 is an explanatory diagram of the prior art of a compression bender with two drive units. FIG. 3 is an explanatory diagram of the prior art of a compression bender with a single drive unit. Explanatory drawing when implementing invention of Claim 1. FIG. (A) is a figure explaining the state just before bending, (B) is a figure explaining the state in the middle of bending. It is explanatory drawing of Embodiment 2 of this invention. It is explanatory drawing of the structure which used the compression wheel as the wheel. It is another example of a form (metal pipe movement system) of Embodiment 1 of the present invention. (A) is sectional drawing of a metal pipe at the time of performing a vertical bending, (b) is a cross-sectional view of a metal pipe. FIG. 6 is a cross-sectional view of a metal pipe during bending standby in which a conductive member 11 is set at a position of a deviation e from the center of the metal pipe. The figure which shows the cross-sectional view and bending radius of a metal pipe at the time of carrying out the vertical bending with the deviation e in order to make desired thinning rate into (alpha). It is explanatory drawing which shows the relationship with the compression wheel 14 when setting the conduction member 11 to the position of the arbitrary deviation e from the metal pipe center. It is explanatory drawing of the conventional apparatus in case a drive device is one place. It is explanatory drawing of the conventional apparatus in case a drive device is two places.

1 metal tube, 2 bent part of metal tube, 3 arm clamp,
4 bending arm, 5 bracket, 6 pivot axis, 7 tail clamp,
8 base, 9, 9 'bending cylinder, 10, 10' cylinder rod,
11 Conductive members (chains, steel cables, etc.) 12, 13 nodes, 14 compression wheels,
15 headstock, 16 wheels, 17 rails, 18 slack adjuster,
19 heating devices, 20 load cells, 21 heat sources, 22 trolleys,
23 rail, 24 screw A bending point, P axial compression force, reaction force applied to P ₁ transmission member,
P ₂ Bending developed tension (bending cylinder) of the cylinder 9, M bending moment,
θ Bending angle, α Thinning ratio, EE ′ Neutral axis position without wall thickness fluctuation,
NN ′ metal tube center, CC ′ bending inside, TT ′ bending outside, e distance from metal tube center to EE ′, o turning center, ρ average radius of metal tube, r compression wheel radius, theta _e neutral axis angle, R bend radius, base pipe wall thickness of _{t 0} the metal tube, the tension side wall thickness _{t t} metal pipes, compression side wall thickness of _{t c} metal tube

Claims (4)

A method of bending a metal tube at a thinning rate α, wherein a perpendicular leg drawn from the bending center with respect to the metal tube to be bent is a point A, and the tip of the metal tube is forward of the point A At a specific position of the bending arm, it is clamped on a bending arm that is rotatable around the bending center so that the effective radius is a predetermined bending radius R, and the bending arm and the center of rotation are attached to the bending arm. An effective radius sharing r is r, and a compression wheel with r = R + e larger than the bending radius R by a deviation e calculated by the following equation (1 · 1) is fixed or fitted, while the metal The rear end of the metal tube is clamped to a tail clamp device on the base located behind the tube, and the conductive member is supported by the compression wheel, and the center of the metal tube is supported on the base. Looseness adjustment device and bending provided on the outside of the bend by deviation e The conductive member is stretched and fixed in a straight line using the looseness adjusting device, and then the metal tube is moved using an appropriate driving device, and the metal tube is moved to the point. In the vicinity of A, a heating device is used to heat a narrow region in the longitudinal direction of the metal tube, gradually reducing the distance between the base and the bending center, and extending the axis of deviation e from the center of the metal tube. Is suppressed using the conductive member, and a bending process is performed while applying a compressive force P (= P ₁ + P ₂ ) obtained by adding a thrust P _{2 of the} driving device and a reaction force P ₁ generated in the conductive member. A method of compressing and bending a metal tube, characterized in that:
  The load cell is set on the conductive member, and a tension corresponding to a reaction force generated during bending is applied to the conductive member in advance using the slack adjusting device, and then the conductive member is stretched and then bent. 2. A method of compressing and bending a metal tube according to 1. A heating device for heating a narrow region in the longitudinal direction of a metal tube to be bent, a device for moving the heating device, and the metal tube in front of a foot point A of a perpendicular drawn from the bending center with respect to the metal tube A rotating bending arm that clamps a specific position of the metal, a compression wheel that shares the center of rotation with the bending arm, a base that is located behind the metal tube, and a base that is disposed on the base A tail clamp device for clamping the rear portion, a slack adjusting device provided on the base at a position separated from the center of the metal tube by a deviation e calculated by the following equation (1 · 1), and the slack adjusting device. A metal tube compression bending apparatus comprising: a conductive member connected to the bending arm in a state of being supported by the compression wheel at a starting point; and a drive device that varies a distance between the base and the bending center. .



  The metal tube compression bending apparatus according to claim 3, wherein a load cell is attached to the conductive member.