JP4837308B2 - Pipe bending method and apparatus - Google Patents

Description

The present invention relates to a pipe bending method and apparatus .

(1) Rotating pull bending machine Pipe parts that have been subjected to small R bending (normally R / D <2, R: neutral axis bending radius, D: pipe outer diameter) are used in automobiles or air conditioners. ing. As a bending method for bending a pipe into a predetermined shape, a rotary drawing bending apparatus as shown in FIGS. 3 and 4 is widely used.

  The rotary pull bending apparatus has a rotatable bending die 1 in which a groove for bending guidance is formed, a clamp 2 for fixing a part of the pipe p to the bending die 1, and a bending outer peripheral surface of the pipe p. A holding die (pressure die) 3, a wrinkle restraint (wiper) 4 that holds the inner circumferential surface of the pipe p, a mandrel 5 that is held inside the pipe p, and a pipe p from the rear end of the pipe p Has a tube booster 6 for urging the shaft in the axial direction (moving direction of the inlet pipe). The pressing die 3 is supported by a holder 7 so as to be movable in the axial direction of the pipe p, and the holder 7 can be adjusted in the radial position of the bending die 1 by a position adjusting screw 7a. Although the holder 7 is moved by the position adjusting screw 7a and the pressing position of the pressing die 3 is adjusted, there is a guide mechanism for guiding the moving direction of the holder 7, although not shown in FIGS.

Since the rotary drawing and bending machine basically does not perform drawing at the bending portion, the pressing method of the pressing mold, the pressing means, and the installation position have the following characteristics.
(A) About the pressing method of the pressing die (pressure die) in the rotary drawing process: The rotary drawing machine processes the pipe by clamping the tip of the pipe to the bending die and rotating the bending die (= bending die). It is characterized by winding and bending while pulling. At this time, by restraining the bending outer side of the pipe with a pressing die moving in the longitudinal direction, the bending reaction force generated on the opposite side of the portion wound around the bending die is received and the pipe is prevented from being squeezed. Therefore, it is basic to fix the pressure die pressing position at the pipe setting position.

When the pipe is thin, the cross-sectional shape is flattened by bending. Therefore, flattening of the cross-section during bending is suppressed by inserting a mandrel on the inner surface of the pipe.
(B) About the pressing die pressurizing means and its installation position in the rotary pulling bending process: In order to efficiently receive the bending reaction force generated on the opposite side of the portion wound around the bending die by the above-mentioned concept (a), The installation position of the holder for fixing the mold and the position adjusting screw at the center thereof is set to a position closer to the entry side than the position where the bending mold and the pipe are in contact with each other. In a normal rotary bending machine, this installation position is generally set to a position closer to the entry side by about the maximum outer diameter Dmax × (1.5 to 2) of the pipe from the position where the bending mold and the pipe are in contact. is there.

When the pressing die pressurizing means is installed at such a position, it can be used for a bending process that does not cause the pipe to be deformed as in (a) above.
(2) Thinning of bending outer side and generation of wrinkle on inner side of bending and its suppression method in rotary drawing bending process In this pipe bending method, as shown in FIG. On the other hand, the outer side of the bend is stretched due to the long trajectory length and is thinner than the original thickness t, and the inner side of the bend is shortened due to the short trajectory length and becomes thicker than the original thickness t. For this reason, it becomes easy to generate | occur | produce a crack in a bending outer side and buckling in a bending inner side. In addition, ovalization (flattening) occurs as shown in FIG.

When a relatively thin tube material is bent by the rotary drawing method, wrinkles on the inner side of the bend become noticeable along with the thinning on the outer side of the bend.
Conventionally, to prevent wrinkles (buckling) on the inner side of the bend and to prevent the pipe p from becoming oval, as shown in FIGS. 3 and 4, a mandrel 5 is provided on the inner surface side of the pipe p, and the bending die 1 on the outer surface side of the pipe p and Bending (buckling) has been prevented by bending with the pipe p held between the wrinkle restraint 4 and the mandrel 5 on the inner surface of the pipe p. In addition to the thinning due to the tensile deformation of bending, the outer side had the disadvantage that the thinning of the outer side of the bending was promoted and the cracks were more easily broken.

  In Patent Document 1, as a method for suppressing such problems of cracks and wrinkles (buckling) in bending, a bending speed detector of the bending die 1 and a pushing speed detector of the tube booster 6 are attached to the rotary pull bending apparatus. It has been proposed to employ a synchronous control that makes the bending speed pattern and the pressing speed pattern similar by controlling acceleration / deceleration of the bending speed or the pressing speed based on signals from these detectors.

Further, in Patent Document 2, the thrust from the rear end of the tube booster 6 is overloaded from the pulling load of the bending die 1, the pushing speed of the tube booster 6 is overspeeded from the bending velocity of the bending die 1, and the pushing die is further pushed. It has been proposed that the moving speed of 3 is higher than the bending speed of the bending die 1.
Patent Document 3 proposes a means for applying a compressive force in the pipe axis direction by moving the pressing die in the pipe axis direction without slipping with the pipe in order to suppress wrinkles inside the bend and thinning outside the bend. Has been.
Japanese Patent No. 2544001 Japanese Patent Publication No. 2-15291 Japanese Patent Laid-Open No. 3-81019

  However, even if the techniques described in the above-mentioned patent documents 1 to 3 are used, the inner surface of the pipe is deformed as described above by a mandrel for preventing flattening of the pipe and suppressing wrinkles (buckling) inside the bend. However, thinning pipes (especially the ratio t / D of thickness t to outer diameter D is reduced by removing the mandrel and wrinkle suppression to prevent thinning due to ironing deformation. 0.03 or less), even when bending to a relatively large bending radius such that the ratio R / D of the bending radius R to the outer diameter is about 3 or more, the inside of the bend (the inner side of the bend) ) Has the disadvantage of causing wrinkles.

The present invention has been made in order to solve the problems associated with the above-described prior art, and its purpose is to suppress thinning of the outer side of the bend in bending with a relatively large bending radius, to suppress mandrel and wrinkles, etc. It is an object of the present invention to provide a pipe bending method and apparatus having a simple apparatus configuration that does not generate wrinkles (buckling) inside the bending without using the above tool.

  As a result of intensive research on bending of pipes, the present inventors have conducted bending and drawing (diameter reduction) in a bent portion of the pipe (that is, a portion that is intended to follow the bending die). At the same time, we found that wrinkle generation inside the bend can be suppressed by applying axial (tube axis direction) tension to the pipe at the bent part entry side, and further applying pipe axis tension to the bent part entry side of the pipe. In order to achieve this, the present inventors have found that it is better to move the pressing die at a lower speed than the pipe.

That is, the present invention is as follows.
[Claim 1 ]
Bending radius to outer diameter ratio R / of a pipe having a wall thickness t of 2.3 mm or less and a wall thickness to outer diameter ratio t / D of 0.03 or less formed on a rotatable main body and a peripheral surface of the main body. D: a bending die having a cross-section arc- shaped groove portion having the same groove radius as the pipe radius corresponding to the bending shape of 2.4 to 5.2, a clamp for holding one end of the pipe, and the groove portion of the bending die It said pipe having a groove of the same groove radius of circular arc cross sectional shape as the pipe radius that can be clamped, and stamping die movable in the axial direction of the pipe to be該挟lifting, toward the pusher type in the bending tool between the As a pressurizing means for pressurizing without applying an excessive bending moment, a straight line passing through the point where the pipe abuts on the bending mold and the rotation center of the main body portion is zero or more on the inlet side of the pipe and the inlet side The point where a straight line shifted by a distance equal to or less than the outer diameter of the pipe intersects the push die Means for pressurizing, a holder for transmitting the pressing force of the means to the pressing mold, a holder guide mechanism for keeping the direction of the pressing force constant, and a driving means for driving the movement of the pressing mold. And using a pipe bending apparatus in which the total sum of the lengths of the groove portions combining the bending mold and the pressing mold is shorter than the circumferential length of the pipe,
No mandrel is disposed on the inner surface of the pipe and no wrinkle suppression is disposed on the outer surface of the pipe entry side on the bending portion entry side, and drawing and tube axial tension are simultaneously applied to the bending portion to bend outside. In order to simultaneously prevent the thinning of the wire and the wrinkle inside the bend and the ovalization of the cross section of the pipe, the pipe is sandwiched between the grooves of the bending die and the pressing die, and the bending portion is squeezed by the pressing means. processed speed ratio defined by the following following formula (1) the push-type pipe axis direction in the driving means is driven so that 0.60 to 0.95 while the following formula the drawing at the same time (2) defined in the bent portion perimeter aperture ratio characteristics and to Rupa type bending method that performs rotation bending while facilities to be less than 8.0% 0.5% or more.
Speed ratio = Pushing-type tube axis moving speed / Pipe centerline moving speed (1)
Bending part circumference drawing ratio = (Round pipe circumference-Pipe circumference after bending) / Round pipe circumference x 100 (%) (2)
Here, the elementary pipe refers to a pipe before bending.
[Claim 2 ]
Furthermore, the pipe bending machining method according to claim 1 using a control means for controlling said pressurizing means in accordance with the bent shape of the pipe.
[Claim 3 ]
The pipe bending method according to claim 2 , wherein a rotation angle of the bending die is detected using a rotation angle detection means, and the pressurizing means is controlled by the control means based on the detected rotation angle.
[Claim 4 ]
The pipe bending method according to claim 3, wherein the driving unit is controlled based on the detected rotation angle.
[Claim 5 ]
It is an apparatus used for implementation of the pipe bending method in any one of Claims 1-4 ,
Bending radius to outer diameter ratio R / of a pipe having a wall thickness t of 2.3 mm or less and a wall thickness to outer diameter ratio t / D of 0.03 or less formed on a rotatable main body and a peripheral surface of the main body. D: a bending die having a cross-section arc- shaped groove portion having the same groove radius as the pipe radius corresponding to the bending shape of 2.4 to 5.2, a clamp for holding one end of the pipe, and the groove portion of the bending die It said pipe having a groove of the same groove radius of circular arc cross sectional shape as the pipe radius that can be clamped, and stamping die movable in the axial direction of the pipe to be該挟lifting, toward the pusher type in the bending tool between the As a pressurizing means for pressurizing without applying an excessive bending moment, a straight line passing through the point where the pipe abuts on the bending mold and the rotation center of the main body portion is zero or more on the inlet side of the pipe and the inlet side The point where a straight line shifted by a distance equal to or less than the outer diameter of the pipe intersects the push die Means for pressurizing, a holder for transmitting the pressing force of the means to the pressing mold, a holder guide mechanism for keeping the direction of the pressing force constant, and a driving means for driving the movement of the pressing mold. In addition, the pipe bending apparatus is characterized in that the total sum of the lengths of the groove portions combining the bending die and the pressing die is shorter than the circumferential length of the pipe.
[Claim 6 ]
The pipe bending apparatus according to claim 5 , further comprising a control unit that controls the pressurizing unit in accordance with a bending shape of the pipe.
[Claim 7 ]
The rotation means according to claim 6 , further comprising a rotation angle detection means for detecting a rotation angle of the bending mold, wherein the control means controls the pressurizing means based on the rotation angle detected by the rotation angle detection means. Pipe bending machine.
[Claim 8 ]
Furthermore, the pipe bending apparatus in any one of Claims 5-7 which has a control means which controls the said drive means according to the bending shape of a pipe.
[Claim 9 ]
The pipe bending apparatus according to claim 8 , wherein the control means for controlling the drive means controls the drive means based on the rotation angle detected by the rotation angle detection means.
[Claim 10 ]
The pipe bending apparatus according to any one of claims 5 to 9 , further comprising a pressing position changing unit that changes a setting position of at least one of the pressing unit, the holder, and the holder guide mechanism.

  According to the device of the present invention, with a simple device configuration, while simultaneously applying a circumferential compressive force of drawing processing and a pipe axis direction tension by controlling the feed amount or feed speed of the pressing die to the bending portion of the pipe, According to the method of the present invention in which bending can be performed while drawing a pipe, and bending is performed simultaneously with drawing while applying a tensile force in the tube axis direction using the apparatus of the present invention, a thin pipe is bent relatively large. When bending to a radius, wrinkles can be effectively prevented from occurring inside the bend.

  Also, the pressurizing load form of the pressurizing means is shifted by a distance of 0 or more to the inlet side of the pipe and less than or equal to the outer diameter of the inlet pipe on the straight line passing the point where the pipe contacts the bending mold and the rotation center of the main body. By adopting a configuration in which the point where the straight line intersects the pressing die is pressed in the linear direction, an extra bending moment does not act on the guide structure of the holder that transmits the pressing force to the pressing die, causing the device to be deformed or damaged. It is possible to load a large applied pressure without any trouble.

  Further, by using this apparatus, it is possible to reduce the cost of the apparatus and the mold, and at the same time, shorten the cycle time of the bending process.

1 and 2 are a schematic view showing an example of a pipe bending apparatus of the present invention and a schematic IV-IV cross-sectional view thereof. Hereinafter, embodiments of the present invention will be described with reference to these drawings.
The illustrated example shows a bending die 1 having a body portion rotatable around a rotation center o and a groove 1U portion having a shape corresponding to the bending shape of the pipe p formed on the peripheral surface of the body portion, and a pipe p. The pipe p can be sandwiched between the clamp 2 that holds one end of the groove, the groove 1U of the bending die 1 and the groove 3U of the self (pushing die 3), and is movable in the axial direction of the sandwiched pipe p It has a pressing die 3.

  Further, as a pressurizing means 8 for pressurizing the pressing die 3 toward the bending die 1, a straight line L0 passing through the point where the pipe p abuts on the bending die 1 and the rotation center o of the main body portion is set to 0 on the inlet side of the pipe p. The point where the straight line L1 shifted in parallel by the distance δ equal to or less than the pipe outer diameter D on the entry side intersects the pressing die 1 is pressed in the direction of the straight line L1 {ie, the straight line L0 (or the straight line L1) and the pressing die 1 Pressurizing the intersection point in the direction of the straight line L0 (or straight line L1)}, a pressurizing actuator 8, and preferably further a holder 7 for transmitting the pressurizing force of the pressurizing actuator 8 to the pressing die 1 and the direction of the pressurizing force. And a holder guide mechanism (not shown) for keeping it constant. The point where the pipe comes into contact with the bending die refers to the point where the pipe comes into contact with the bending die under the condition that the amount of drawing is zero.

Moreover, it has the control means 11 which controls the pressurization means 8 according to the bending shape of the pipe p, and the press die drive actuator 12 as a drive means which drives the movement of the push die 3.
Note that 9 is a hydraulic control device that controls the pressure applied by the pressurizing actuator 8, 13 is a hydraulic control device that controls the tensile force of the push-type drive actuator, and 10 is a rotation angle detection means that detects the rotation angle of the bending die 1. , 11 are control devices for instructing the hydraulic control devices 9, 13 based on the detected angle information of the rotation angle detecting means 10, respectively.

  When the pipe p is attached to the pipe bending apparatus and bending is performed, the sum of the arc lengths of the grooves 1U and 3U of the bending die 1 and the pressing die 3 (peripheral length as a hole mold) is shorter than the peripheral length of the pipe p, In addition, by making the pressure of the pressurizing means 8 more than the force required for the drawing deformation of the pipe p and applying a pipe axial tension to the pipe p on the bending side, the pipe p is simultaneously given drawing and bending, And the wrinkle which generate | occur | produces inside a bending can be suppressed effectively.

The force required to throttle the pipe p varies greatly depending on the outer diameter D, the thickness t, the strength, and the degree of the amount of drawing of the pipe p, but a large pressing force of several tons to several tens of tons is required.
When such a large pressure is applied, from a straight line L0 passing through the point where the pipe p abuts on the bending die 1 and the rotation center o of the bending die main body as in a normal rotary bending machine (FIG. 3). When the holder 7 arranged at a largely separated position is pressurized, the product of the applied pressure acting on the separated position and the distance to the separated position around the point where the pipe abuts the bending mold on the pipe p. A large bending moment proportional to When the applied pressure is increased, the holder for transmitting the applied pressure is inclined by a gap (gap) from the guide, and in addition to the drawing and bending deformation at the bent part, the pipe p on the bent part entrance side is bent by the applied pressure. A moment may be applied to cause the pipe to bend on the entry side of the bent portion, or the guide mechanism or the mechanism that holds the wrinkle suppression may be deformed.

  When a pressurizing means is arranged at the position of the straight line L0 and the pressing die 3 is pressed in the direction of the straight line L0, the bending moment due to the applied pressure acting on the pipe p on the bending portion entry side is not generated, and the pressing force is not applied. The pressure applied by the pressure means 8 is used for drawing and bending the pipe p. On the other hand, a bending moment for bending the pipe is simultaneously generated by the rotation of the bending die 1 in addition to the restriction by the bending force of the bending die 1 and the pressing die 3. On the bending portion entry side, the pressing die 3 receives a reaction force of this bending moment, so that the bending process is performed simultaneously with the drawing process. In order to keep the pipe on the entry side of the bending portion horizontal as shown in FIG. 1 and to perform molding at a predetermined bending angle, the holder 7 receives the rotational force due to the bending moment received by the pressing die 3. Guide means (not shown) such as a T-groove type guide attached to the bending machine main body, for example, which guides the head so as to be able to advance and retreat only in the pressurizing direction is provided.

  When drawing and bending the pipe p at the same time, the guide means transmits the applied pressure to the pipe, so that it is necessary to receive the pressure without changing the pressurizing direction even when the rotational force is applied. is there. For this reason, the pressurizing means 8 has a straight line L0 passing through the point where the pipe p abuts against the bending die 1 and the rotation center o of the main body part at 0 or more on the entry side of the pipe p and less than or equal to the pipe outer diameter D on the entry side. The point where the straight line L1 shifted in parallel by the distance δ (provided that the straight line L0 coincides with the straight line L0 when δ = 0) intersects the pressing die 3 is pressed in the direction of the straight line L1. As a result, the guide means is not deformed or damaged, or the processing machine main body (non-moving part of the processing apparatus, for example, the guide mechanism of the holder 7) is not deformed or damaged. Drawing and bending of the pipe p can be performed at the same time while reducing the effect of unnecessary bending moment on the pipe.

It should be noted that the distance δ is determined from the viewpoint of avoiding deformation when subjected to a force accompanying bending processing including drawing of the pipe and the assembly accuracy due to long-term use since the guide mechanism is fixed to the processing machine body. From the viewpoint of suppressing deterioration, it is preferable to set the pipe outer diameter to ½ (that is, D / 2) or less.
However, if the sum of the perimeters of the hole molds formed by the arc lengths of the grooves 1U and 3U is equal to or longer than the perimeter of the pipe p, the flanges of the bending mold 1 and the pressing mold 3 come into contact (between the flanges). Since the drawing force hardly acts on the pipe p and the pipe p cannot be greatly drawn, the sum of the arc lengths of the grooves 1U and 3U of the bending die 1 and the pressing die 3 is the pipe circumference. It is preferable that the length is shorter than the length.

  When the pipe p is compressed in the circumferential direction at the bending portion and drawn, the neutral axis of the bending deformation moves to the outside of the bend rather than the geometric axis, so that the thinning of the outside of the bend is reduced and the bending is simultaneously performed. The part extends in the axial direction while increasing the wall thickness. This elongation in the axial direction supplements the trajectory length on the outer side of the bend, and can further suppress the thinning on the outer side of the bend. However, since the mandrel is not arranged on the inner surface side of the pipe p, the ironing deformation by the mandrel does not occur, and the reduction of the thickness due to the ironing deformation is not promoted. That is, bending with less thinning is possible.

  On the other hand, as described above with respect to the conventional rotary pull bending apparatus, the bending outer side of the pipe p becomes elliptical (flattened) during the bending process. This is a phenomenon that occurs in order to relieve the tensile deformation outside the bending of the pipe p, and occurs when the outside of the pipe p is separated from the hole shape of the pressing die 3. However, when the drawing portion is sufficiently drawn at the bending portion as in the present invention, the pipe p fills the hole molds (grooves 1U, 3U) of the bending die 1 and the pressing die 3, and the deformation of drawing and bending occurs. Since it progresses, the cross-sectional shape is less likely to be ovalized (flattened). On the contrary, the sum of the perimeters of the bending die 1 and the pressing die 3 is longer than the perimeter of the pipe p, and when the drawing process is not performed, the pipe p is difficult to fill into the perforation, so that it is ovalized (flattened). It is easy to produce.

On the inner side of the bend, if the sum of the peripheries of the bending die 1 and the pressing die 3 is shorter than the perimeter of the pipe p and the drawing process is sufficiently performed in the bending portion, the pipe p is Since the hole molds of the bending mold 1 and the pressing mold 3 are filled, the thickness increase is increased, and the generation of wrinkles due to buckling deformation is also reduced.
Further, in conjunction with the simultaneous processing of drawing and bending as described above, the moving speed of the pressing mold 3 is controlled to be lower than the moving speed of the pipe p by the pressing mold driving actuator 12, thereby bending the pipe p bending portion ( That is, by applying a pipe axial tension to a portion that is to follow the bending mold, a thin pipe (particularly, a ratio t / D of the thickness t to the outer diameter D is 0.03 or less) is bent to a radius R. Even when bending to a relatively large bending radius such that the ratio R / D of the outer diameter and the outer diameter is about 3 or more, wrinkles on the inner side of the bend (bending inner peripheral side) are generated without using wrinkle suppression. Can be suppressed.

As described above, according to the method of the present invention, when a thin pipe is bent to a relatively large bending radius, it is possible to effectively prevent wrinkles from occurring inside the bend. At this time, the moving speed of the pressing die is loaded so that the speed ratio defined by the following equation (1) is 0.95 or less, and the drawing process is performed by the bending portion circumference defined by the following equation (2). It is preferable to apply the squeezing ratio to 0.5% or more.
Speed ratio = Pushing die tube axis moving speed / Pipe centerline moving speed (1)
Bending part circumference drawing ratio = (Round pipe circumference-Pipe circumference after bending) / Round pipe circumference x 100 (%) (2)
Here, the elementary pipe refers to a pipe before bending. FIG. 7 is a diagram for explaining the definition of the speed ratio.

However, if the speed ratio is too small, the thickness decrease on the outside of the bend will increase and cracking will easily occur, and there is a risk of wrinkles due to slippage between the pressing die and the pipe. It is preferable to do this. A more preferable speed ratio is 0.70 to 0.90.
In addition, when trying to obtain a large bending portion perimeter drawing ratio exceeding 8.0%, not only will the scale of the device increase due to excessive pressure, but the outer diameter of the pipe after bending will become too small. Since it is not realistic, it is preferable that the bending portion circumferential length drawing ratio is 8.0% or less. In the method of the present invention, the core is arranged using the one provided in the bending apparatus of the present invention with a mandrel arrangement means for arranging a mandrel inside the portion of the pipe sandwiched between the bending die and the pressing die. Bending may be performed without gold.

  As described above, the example of the device of the present invention shown in FIGS. 1 and 2 has the rotation angle detection means 10 for detecting the rotation angle of the bending die 1 supported rotatably around the point o. ing. On the other hand, a hydraulic pressure control device 9 is connected to the pressurizing means 8, and the hydraulic pressure control device 9 and the rotation angle detecting means 10 are connected to a control means 11 for controlling the movement of the apparatus, and the control means 11 is rotated. Upon receiving a signal from the angle detection means 10, a pressure instruction signal can be issued to the hydraulic control device 9 to control the pressure of the pressurizing actuator 8.

The control means 11 is also connected to drive means (push-type drive actuator) 12 for driving the push die via the hydraulic control device 13, and receives a signal from the angle detection device 10 to receive the hydraulic control device 13. An instruction signal for the tube axis direction tension can be issued to control the tension of the push-type drive actuator 12.
In advance, position information of a part with a large throttle amount or a part with a small throttle amount in the longitudinal direction of the pipe p is input to the control means 11 in association with the position information of the rotation angle of the bending die 1 and the necessary pressure is applied at that time. If the information is input, when the signal from the rotation angle detection means 10 reaches the set angle during the bending process, the control means 11 issues an instruction signal to the hydraulic control device 9 so as to become the set pressure, and the pressurizing means 8 As a result, bending members having different drawing amounts in the longitudinal direction of the pipe p can be manufactured.

  In addition, when the pressing mold moving speed is controlled at a constant speed, the general operation setting can be performed only by the hydraulic control device 13 and the driving means 12, but a plurality of bendings having different pipe bending radii are continuously performed. In some cases, it is necessary to optimally control the tube axial tension according to the bending radius. In this case, similarly to the control system of the pressurizing means, the position information of the part having a large or small bending radius in the longitudinal direction of the pipe p is previously controlled in correspondence with the position information of the rotation angle of the bending die 1. If the information of the push-type driving means corresponding to the tube axial tension required at that time is inputted to the means 11 and the signal from the rotation angle detecting means 10 becomes a set angle during bending, the control is performed. The means 11 issues an instruction signal to the hydraulic control device 13 so as to obtain the optimum tension, and controls the tension load in the tube axis direction. As a result, a bending member of a thin pipe having a different bending radius in the longitudinal direction of the pipe p can be manufactured.

In order to control the pressing tool movement speed with higher accuracy, a pressing tool movement amount detector is provided, and the detected value of the pressing tool movement amount is input to the control means 11 to calculate the pressing tool movement speed, and the calculation result May be used to control the push-type drive actuator 12.
In a typical rotary drawing and bending machine, bending is performed by exchanging the bending die 1 and the pressing die 3 so that the pipe outer diameter can cope with a change in a certain range (for example, outer diameter 48.6 to 89.1 mm). In response to changes in the outer diameter of the pipe to be processed, it is necessary to replace the mandrel for changes in the pipe wall thickness. In the apparatus of the present invention, the bending die 1, the push die 3 and the wrinkle restraint 4 are exchanged in response to a change in the pipe outer diameter, and the form adapted for changing the pressurizing position in accordance with the pipe outer diameter change. It is preferable that pressure position changing means for changing the setting positions of the pressure means 8, the holder 7, and the holder guide mechanism is provided so that bending at an appropriate pressure position can be advantageously performed. Further, the holder for holding the rotating shaft of the bending die 1 and the pressing die 3 and the holder guide mechanism are attached to the base of the bending machine main body so as to obtain a predetermined rigidity, but the outer diameter D and the wall thickness of the pipe p. When t is large or the amount of restriction is large, a large pressing force is applied. Therefore, when the rotating shaft of the bending die 1 is bent or the rigidity of the main body to be attached is insufficient, the base of the main body bends. In some cases, a predetermined aperture amount cannot be given. In such a case, bending of the rotating shaft of the bending die 1, bending of the main body base, etc. are performed by attaching and integrating the structural parts that connect the rotating shaft upper part of the bending die 1 and the parts to which the pressing means is attached. The deformation may be prevented.

  The present invention can also be applied to a rotational bending process in which the pipe is not squeezed by fixing the pressing position of the pressing die to the position when the pipe is set.

  Conventional device (conventional rotary bending device (FIG. 3); device B), device of the present invention (straight line L1 within the range of δ = 0 or more and D or less as shown in FIG. 1 (provided that the straight line L1 coincides with δ = 0)) The pressurizing means is disposed on the apparatus A} and the comparison apparatus (the pressurizing means is disposed on the straight line L1 within the range of δ> D in FIG. 1; apparatus C), and the following bending is performed. Table 1 shows the results of visual evaluation of the appearance (processing conditions) of the sample. The speed ratio in Table 1 is a value calculated from the measurement result.

Material: Carbon steel ERW steel pipe STKM20A, STKM15A, STKM17A
Outer diameter D × wall thickness t (mm): φ63.5 × t1.6, φ89.1 × t2.0, φ114.3 × t2.3 (t / D = 2.5, 2.2, 2.0 %)
Bending radius R (mm): 150, 300, 600 (R / D = 2.4, 3.3, 5.2), bending angle: 90 °
As is apparent from Table 1, in the present invention example in which the machining conditions belong to the method of the present invention, it could be machined without causing wrinkles (buckling).

It is the schematic which shows one example of the pipe bending apparatus of this invention. FIG. 4 is a schematic sectional view taken along the line IV-IV in FIG. 2. It is the schematic which shows an example of the conventional rotation pull bending apparatus. FIG. 5 is a schematic VV sectional view of FIG. 3. It is explanatory drawing which shows the thinning of the bending outer side of the pipe in a prior art. It is explanatory drawing which shows the ovalization of the pipe in a prior art. It is a definition explanatory drawing of a speed ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bending type | mold 1U, 3U groove | channel 2 Clamp 3 Push type | mold 4 Wrinkle control 5 Mandrel 6 Pipe booster 7 Holder 7a Position adjustment screw 8 Actuator for pressurization (pressurization means)
9, 13 Hydraulic control device 10 Rotation angle detection means 11 Control means 12 Push-type drive actuator (drive means)
p Pipe D Pipe pipe outer diameter t Pipe thickness R Bending radius o Bending mold rotation center L0 The point where the pipe abuts the bending mold and the straight line passing through the rotation center of the bending mold body L1 Straight line L0 enters the pipe A straight line translated by a distance δ equal to or smaller than the pipe outer diameter D on the inlet side

Claims (10)

Bending radius to outer diameter ratio R / of a pipe having a wall thickness t of 2.3 mm or less and a wall thickness to outer diameter ratio t / D of 0.03 or less formed on a rotatable main body and a peripheral surface of the main body. D: a bending die having a cross-section arc- shaped groove portion having the same groove radius as the pipe radius corresponding to the bending shape of 2.4 to 5.2, a clamp for holding one end of the pipe, and the groove portion of the bending die It said pipe having a groove of the same groove radius of circular arc cross sectional shape as the pipe radius that can be clamped, and stamping die movable in the axial direction of the pipe to be該挟lifting, toward the pusher type in the bending tool between the As a pressurizing means for pressurizing without applying an excessive bending moment, a straight line passing through the point where the pipe abuts on the bending mold and the rotation center of the main body portion is zero or more on the inlet side of the pipe and the inlet side The point where a straight line shifted by a distance equal to or less than the outer diameter of the pipe intersects the push die Means for pressurizing, a holder for transmitting the pressing force of the means to the pressing mold, a holder guide mechanism for keeping the direction of the pressing force constant, and a driving means for driving the movement of the pressing mold. And using a pipe bending apparatus in which the total sum of the lengths of the groove portions combining the bending mold and the pressing mold is shorter than the circumferential length of the pipe,
No mandrel is disposed on the inner surface of the pipe and no wrinkle suppression is disposed on the outer surface of the pipe entry side on the bending portion entry side, and drawing and tube axial tension are simultaneously applied to the bending portion to bend outside. In order to simultaneously prevent the thinning of the wire and the wrinkle inside the bend and the ovalization of the cross section of the pipe, the pipe is sandwiched between the grooves of the bending die and the pressing die, and the bending portion is squeezed by the pressing means. processed speed ratio defined by the following following formula (1) the push-type pipe axis direction in the driving means is driven so that 0.60 to 0.95 while the following formula the drawing at the same time (2) defined in the bent portion perimeter aperture ratio characteristics and to Rupa type bending method that performs rotation bending while facilities to be less than 8.0% 0.5% or more.
Speed ratio = Pushing-type tube axis moving speed / Pipe centerline moving speed (1)
Bending part circumference drawing ratio = (Round pipe circumference-Pipe circumference after bending) / Round pipe circumference x 100 (%) (2)
Here, the elementary pipe refers to a pipe before bending. Furthermore, the pipe bending machining method according to claim 1 using a control means for controlling said pressurizing means in accordance with the bent shape of the pipe. The pipe bending method according to claim 2 , wherein a rotation angle of the bending die is detected using a rotation angle detection means, and the pressurizing means is controlled by the control means based on the detected rotation angle. The pipe bending method according to claim 3, wherein the driving unit is controlled based on the detected rotation angle. It is an apparatus used for implementation of the pipe bending method in any one of Claims 1-4 ,
Bending radius to outer diameter ratio R / of a pipe having a wall thickness t of 2.3 mm or less and a wall thickness to outer diameter ratio t / D of 0.03 or less formed on a rotatable main body and a peripheral surface of the main body. D: a bending die having a cross-section arc- shaped groove portion having the same groove radius as the pipe radius corresponding to the bending shape of 2.4 to 5.2, a clamp for holding one end of the pipe, and the groove portion of the bending die It said pipe having a groove of the same groove radius of circular arc cross sectional shape as the pipe radius that can be clamped, and stamping die movable in the axial direction of the pipe to be該挟lifting, toward the pusher type in the bending tool between the As a pressurizing means for pressurizing without applying an excessive bending moment, a straight line passing through the point where the pipe abuts on the bending mold and the rotation center of the main body portion is zero or more on the inlet side of the pipe and the inlet side The point where a straight line shifted by a distance equal to or less than the outer diameter of the pipe intersects the push die Means for pressurizing, a holder for transmitting the pressing force of the means to the pressing mold, a holder guide mechanism for keeping the direction of the pressing force constant, and a driving means for driving the movement of the pressing mold. In addition, the pipe bending apparatus is characterized in that the total sum of the lengths of the groove portions combining the bending die and the pressing die is shorter than the circumferential length of the pipe. The pipe bending apparatus according to claim 5 , further comprising a control unit that controls the pressurizing unit in accordance with a bending shape of the pipe. The rotation means according to claim 6 , further comprising a rotation angle detection means for detecting a rotation angle of the bending mold, wherein the control means controls the pressurizing means based on the rotation angle detected by the rotation angle detection means. Pipe bending machine. Furthermore, the pipe bending apparatus in any one of Claims 5-7 which has a control means which controls the said drive means according to the bending shape of a pipe. The pipe bending apparatus according to claim 8 , wherein the control means for controlling the drive means controls the drive means based on the rotation angle detected by the rotation angle detection means. The pipe bending apparatus according to any one of claims 5 to 9 , further comprising a pressing position changing unit that changes a setting position of at least one of the pressing unit, the holder, and the holder guide mechanism.

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