KR100990731B1 - Manufacturing method for metal bent tube and bending device - Google Patents

Abstract

Provides a technique for bending metal straight pipes at high speed without producing bellows and flattening.

The small section in the tube axis direction of the tube 13 is heated to a temperature easily plastically deformed by the induction coil 35, and the bending arm 17 is moved while moving the region heated by advancing the tube 13 in the tube axis direction. In a method and apparatus for bending and bending a tube by applying a bending moment to the heating region by turning, the induction coil 35 is disposed in the tube, and the bending of the tube 13 during bending is performed. The outer peripheral surface of the bending inner portion and the outer peripheral surfaces of both sides of the bending neutral portion in the region causing the bending deformation are regulated by the restricting surface 42 of the shape correction guide 41 which rotates together with the bending arm 17 to prevent the occurrence of bellows and flattening. In this configuration, it is possible to increase the bending speed.

Regulating surface, shape correction guide, bending arm, induction coil, cooling medium, connecting plate, pressurizing device, mold, high frequency transformer, flat plate, bellows preventing member.

Description

MANUFACTURING METHOD FOR METAL BENT TUBE AND BENDING DEVICE}

1 is a schematic plan view of a bending machine according to one embodiment of the present invention;

FIG. 2 is a schematic sectional view of the bending machine shown in FIG. 1; FIG.

(A), (b), (c), (d) are schematic sectional drawing explaining the bending processing operation by the bending processing apparatus shown in FIG.

(A), (b), (c) is a schematic sectional drawing explaining the bending processing operation by the bending processing apparatus shown in FIG.

FIG. 5 is a schematic cross-sectional view showing an enlarged area causing bending deformation of a tube in the bending processing apparatus of FIG. 1; FIG.

Fig. 6 (a) is a schematic cross-sectional view of a formation correction guide and a pipe at a bending machining position, (b) is a schematic cross-sectional view showing the same portion as (a) apart from the shape correction guide;

7 is a schematic cross-sectional view of a metal curved pipe manufactured by the bending machine of FIG. 1;

(A) is a schematic plan view which shows the modification of the shape correction guide used for the bending machine of FIG. 1, (b) is a schematic sectional view seen from the arrow F-F of (a),

FIG. 9 (a) is a schematic plan view of the bellows preventing member used for the shape correction guide of FIG. 8, (b) is a schematic sectional view seen in the direction of the arrow G-G of (a),                 

(A) is a schematic plan view of the anti-flat plate used for the shape correction guide of FIG. 8, (b) is a schematic sectional view seen from the arrow direction H-H of (a),

11 (a) and 11 (b) are schematic cross-sectional views of the same parts as in Fig. 8 (b), showing a state in which the shape correction guide of Fig. 8 is used under different bending processing conditions, respectively;

12 (a) is a schematic plan view showing still another modification of the shape correction guide used in the bending machine of FIG. 1, (b) is a schematic sectional view seen in the direction of the arrow J-J of (a),

FIG. 13 (a) is a schematic plan view showing a state in which the shape correction guide of FIG. 12 is used under different bending processing conditions, (b) is a schematic sectional view seen in the direction of the arrow K-K in (a),

(A) is a schematic plan view which shows the state which uses the shape correction guide of FIG. 12 by another bending process condition, (b) is a schematic sectional view seen from the direction of the arrow M-M of (a),

15 (a) is a schematic plan view of a bending machine using a modification of the permanent mold, (b) is a schematic sectional view seen in the direction of the PP arrow in (a), and (c) is a mold sphere 81 shown in (b). A schematic cross-sectional view showing a modification of

16 is a schematic cross-sectional view showing another example of the metal curved pipe manufactured in the embodiment of the present invention;

FIG. 17 is a schematic sectional view of a shape correction guide used for producing the metal curved pipe shown in FIG. 16; FIG.

18A, 18B, and 18C are schematic cross-sectional views illustrating a bending processing operation for manufacturing the metal curved pipe shown in FIG. 16;

19 is a schematic cross-sectional view illustrating a bending processing operation for manufacturing the metal curved pipe shown in FIG. 16;

Fig. 20 (a) is a schematic plan view of a conventional bending machine, (b) is a schematic plan view showing a bending machine part of (a) in a state of bending, (c) is a curved pipe manufactured by this bending machine. (B) is a schematic sectional view seen in the direction of the arrow BB of (a),

21 is a schematic cross-sectional view of a bending zone for explaining the problems in conventional bending processing;

(A) is a schematic plan view which shows the other example of the conventional bending machine, (b) is a schematic sectional view seen from the C-C arrow direction of (a),

Fig. 23 (a) is a schematic plan view showing still another example of a conventional bending machine, and (b) is a schematic sectional view seen in the direction of the D-D arrow in (a).

(Explanation of the sign)

13: tube 13A: metal elbow

13a: bend 13b, 13c: tube end

15: machine body 16: spindle

17: bending arm 18: front clamp

20: drive means 23: main bending cylinder

25 Rear Clamp 26: Rear Clamp Support

28: pressurization device 30: connecting plate

31: cylinder for compression 35: induction coil

36: cooling medium 38: high frequency transformer                 

39: motor for transformer movement 40, 40A: permanent tool (molding tool)

41, 41A, 41B, 41C: contour correction guide

42, 42C: Regulatory surface 42a: Bellows regulatory surface

42b: Flat Regulation Page 46: Pipe Regulatory Measures

47: pressure roller 50a, 50b, 50c: tube

51a, 51b, 51c: flattening prevention plate 53a, 53c, 53d: bellows prevention member

58: Bellows-regulated plane 61: Flat regulatory plane

(Technical field to which the invention belongs)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal curved pipe by bending a metal straight pipe, and a bending device for metal pipes used in the practice of the method.

(Prior Art)

(Patent Document 1) JP 58-2726

(Patent Document 2) JP 54-28155

(Patent Document 3) Japanese Unexamined Patent Publication No. 1-18970

(Patent Document 4) Japanese Unexamined Patent Publication No. 61-199521

Background Art Conventionally, a method of bending a metal straight pipe by hot or cold is known as a manufacturing method of a metal curved pipe. As a typical method of hot bending, as shown in Fig. 20 (a), a straight pipe 1 to be bent is passed through an induction coil 2 arranged at a fixed position, and the tip thereof is supported. The front clamp (4) provided on the bending arm (3) which can turn around (O) is gripped, the rear end is gripped by the rear clamp (5), and the middle part is guided by the guide roller (6). Then, the small section in the tube axis direction of the tube 1 is inductively heated to a temperature at which plastic deformation is easy by the induction coil 2 to form a heating section 7, and at the same time the rear clamp 5 ) Is pushed in the tube axis direction by a propulsion device (not shown) to continuously advance the tube 1 in the tube axis direction, and as shown in FIG. 20 (b), a heating part formed by the induction coil 2 The heating arm 7 is provided with the bending arm 3 while moving (7) relative to the tube axis direction. The bending area of the pipe 1 is subjected to a bending operation in which a bending moment generated by turning is applied to bend deformation, and immediately afterwards, a cooling medium 8 such as cooling water is injected from the induction coil 2 to cool and harden. The method of carrying out the process is known, and by this bending process, as shown to FIG. 20 (c), the metal curved pipe provided with the curved pipe part 1a and the pipe end parts 1b and 1c of the both ends of the straight pipe shape ( 1A) is being manufactured.

In this bending processing method, as shown in Fig. 20 (d), the cross section of the curved pipe portion 1a is exaggerated, and a compressive force is applied to the pipe wall on the inner side of the bending (C side) with the bending neutral portion (neutral shaft) NN as the boundary. This action becomes thick, and a tensile force acts on the pipe wall on the bending outside (T side) to make it thin. Therefore, in order to suppress thinning of the outer periphery side wall of the bend, a method of bending is also known while applying a compressive force in the tube axial direction to the tube 1, but in this case, the thickness of the inner side of the bend side wall is further enlarged. During bending, a large compressive force acts on the inner bent inner pipe wall, and when a large thickness is to be increased, deformation of the pipe wall becomes unstable. As shown in Fig. 21, the bent inner pipe wall 1aa is called bellows. Unstable deformation may occur. Therefore, conventionally, measures such as suppressing the bending speed or limiting the bending radius R to a certain degree or the like have been adopted so as to prevent the occurrence of bellows.

In the bending processing method described above, at the start of bending processing, since the driving force applied to the pipe acts as a compressive force on the pipe wall before increasing the thickness of the inside of the bent portion, the compressive stress generated on the pipe wall becomes large, and it is easy to generate bellows. . Therefore, prior to the bending process, hot swaging is performed on the straight pipe portion positioned in front of the curved pipe portion to increase the thickness of the straight pipe portion toward the curved pipe portion, increase the thickness, and then start the bending process by starting the bending process. It is also known to reduce the compressive stress generated in the inner tube wall and prevent the occurrence of bellows (see, for example, Japanese Unexamined Patent Publication No. 58-2726 in Patent Document 1).

In the above bending processing method, the bending outer circumferential side pipe wall and the bending inner side pipe wall are deformed to be close to the bending neutral portion N-N at the time of bending processing, so that the outer diameter of the neutral position is expanded, and the curved pipe portion is flattened. Therefore, in order to prevent this flattening, as shown in Figs. 22A and 22B, the flattening prevention jig (manual) is manually applied to the bent portion 1a after passing the induction coil 2 during bending. A method of preventing flattening by attaching 10) in sequence and regulating the outer diameter on the bent neutral portion NN of the bent portion 1a is known (for example, Japanese Patent Application Laid-Open No. 54-28155 in Patent Literature 2). Reference).

In the conventional hot bending method described above, in most cases, an induction coil 2 for locally heating the tube 1 is disposed outside the tube 1 and heated from the outer surface of the tube. In order to preferentially heat-treat the inner surface of the tube, an induction coil may be disposed in the tube (see Japanese Patent Application Laid-Open No. 1-18970 to Patent Document 3).

As a cold bending method, as shown in FIG. 23, the partial disk-shaped foam guide 11 which rotates the clamp 4 which grasps the front-end | tip of the pipe 1 to bend-processed centering around the support point O is shown. On the outer circumferential surface of the foam guide 11 and on the outer circumferential surface of the foam guide 11, a regulating surface 11a is formed to regulate the outer circumferential surface of the tube 1, and the restricting surface 11a of the foam guide 11 is cold. ), A method of bending and bending is known (see, for example, Japanese Patent Laid-Open No. 61-199521 in Patent Document 4).

However, all of these prior arts have problems. That is, in the hot bending method as shown in Figs. 20 and 22, there is a possibility that the bellows may occur in the inner wall of the bend, and even if the method of preventing the occurrence of the bellows by increasing the thickness of the straight pipe portion prior to the bending, Bellows also occur when the speed is increased, and therefore, the bending speed cannot be increased very much (for example, the limit of 15 mm / sec at the bending radius of 1.5DR), and the cost is reduced by increasing the bending speed. There was a problem that can not. Moreover, in order to prevent flattening of a curved pipe part, the method of attaching a flat prevention jig by hand requires cumbersome work, and the work load becomes large. In addition, even if the above-mentioned problem of bellows can be solved and the bending speed can be increased, in this case, the flattening jig becomes extremely difficult due to the increase in speed, so that the number of attachments or the increase for the attachment work are necessary. In addition, it may become impossible to attach. When the bending speed is increased, even if the flatness ratio increases, the number of use of the anti-flattening jig must be reduced or cannot be used. Therefore, in the obtained curved pipe, the flatness ratio becomes large, and thus the quality decreases. In addition, when a flat pipe portion is flat, the pipe end has a flat (reverse flat) in a direction rotated by 90 degrees, and includes flange attachment and weld response (improved forming response to the pipe end). In many cases, it is necessary to heat-correct the tube end to a round shape, which is unnecessary cost.

Moreover, in order to arrange the induction coil on the outer surface side of the tube during heating during bending, the clamp holding the tube must be disposed at a properly spaced position so as not to interfere with the induction coil. Straight pipe end portions 1b and 1c left on both sides of the curved pipe portion 1a of (1A) become long, and thus do not meet the required standard values. Therefore, conventionally, after completion of the bending process, a part of the straight tube end portions 1b and 1c is cut out to be adjusted to a desired length, which results in an unnecessary cost. In addition, since the pipe ends 1b and 1c have to be cut after bending, it is necessary to carry out improvement work and flange attachment to the pipe ends after bending, and this operation is extremely difficult and the cost is high. In other words, in the improvement processing and the flange attachment to a curved pipe, unlike a straight pipe, it takes a lot of hands for recognition of a pipe end axis line or is unfamiliar with a planting by rotating it, and it is easy to fit a flange and a cost, Increases.

On the other hand, in the cold bending processing method, because of the tensile bending method, it is not possible to suppress the decrease in thickness on the outer peripheral side of the bending. In addition, since the cold working, the allowable elongation on the outer peripheral side of the bend after bending processing is a value obtained by subtracting the elongation due to bending from the allowable elongation of the raw material, and when the elongation by bending is large (when the bending radius is small), The allowable elongation after bending becomes small, and the standard value required for the pipe cannot be satisfied. For this reason, cold bending products of 2DR or less are hard to use for plant piping for general industry. Moreover, because of the cold working, the deformation resistance at the time of processing is extremely large, which requires a large power for bending processing and a mechanical structure with a large rigidity according to the power, thereby increasing the equipment cost. In a thin tube, bellows often occur in the inner wall of the bend, and in order to prevent this, it is necessary to bend the core bar in the tube.

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and can be bent at high speed without generating bellows and / or flatness to a metal straight pipe, and further, a straight pipe portion left on both sides of the curved pipe portion is required for a metal curved pipe. It is an object of the present invention to provide a technique that can be bent in a short state so as to conform to a standard value, thereby greatly reducing the manufacturing cost of a metal curved pipe.

(Means to solve the task)

MEANS TO SOLVE THE PROBLEM In order to avoid the problem in cold bending, in the manufacture of a metal curved pipe by bending, it employ | adopted hot bending and examined to prevent the bellows and flattening which generate | occur | produce at the time of the hot bending. As a result, in the area where the bending deformation of the pipe is caused (called the bending deformation progression part), the outer circumferential surface of the inner side of the tube and the outer circumferential surface of both sides of the bending neutral part are regulated with a suitable tool, thereby preventing bellows and flattening. I found something I could do.

The present invention has been made on the basis of such knowledge, and the invention according to claim 1 of the present invention relates to a metal straight pipe, wherein a small section in the tube axis direction of the pipe is heated to an easily plastic deformation temperature by induction heating, and the heating is performed. The bending part is given by bending moment while giving the bending moment to the heating part while moving the heating part formed in the pipe axial direction relatively, and the bending part is cooled immediately afterward, and the curved pipe part and the straight tube end of the both ends are provided. In a method of manufacturing a metal curved pipe, the induction coil for induction heating is disposed only inside the tube, and the outside of the outer peripheral surface of the bending inner side of the bending deformation progression and the outer peripheral surface of both sides of the bending neutral portion of the outer peripheral surface of the tube are regulated by a molding tool. The bending processing operation is performed, and at the same time as the bending time of the pipe, the bending processing operation is performed before the pipe processing operation. The adjacent straight pipe portion is subjected to an operation of increasing the tube thickness toward the bending point by hot swaging to compress the tube in the tube axis direction to increase the tube thickness, and then to the bending machining operation. It was made up. Thus, by arranging the induction coil only inside the tube, it is possible to arrange the forming tool to the outside of the area heated by the induction coil of the tube without any problem, and the forming tool has outer peripheral surfaces on both sides of the bending neutral portion of the bending deformation progressing portion of the tube. Flattening can be effectively prevented by regulating ,, and bellows generation can be effectively prevented by regulating the outer circumferential surface of the bent inner portion. Moreover, the structure which arrange | positioned the induction coil only in the inside of a pipe | tube advantageously acts also in the prevention of bellows generation (it mentions later). For this reason, it is possible to increase the bending speed and to reduce the cost. Moreover, since it is not necessary to use the flat prevention jig used conventionally, the cumbersome work which manually attached the flat prevention jig is unnecessary, and cost reduction can also be aimed at this point. Moreover, as a result, the flattening of the curved pipe part can be prevented, so that the reverse flat that might have occurred in the pipe end can be prevented, and the correction work of the pipe end is unnecessary. In addition, since the induction coil is disposed in the tube, the clamp for gripping the end of the tube does not interfere with the induction coil, so that the clamp can be positioned near the position where the induction coil is disposed, so that both sides of the bent portion The straight pipe portion left at the bottom can be bent in a state of making the short length required for the finished product. Therefore, after finishing bending, it is not necessary to cut a part of the straight tube end portion and adjust it to a desired length. Before the bending process, a flange may be attached to the end of the tube or an improvement process may be performed. Thus, the manufacturing cost of the metal curved pipe can be further reduced. In addition, in the practice of the present invention, the period between the inner peripheral surface of the bent inner portion of the bending deformation portion of the tube and the outer peripheral surface of both sides of the bent neutral portion with the permanent tool is the period between the start of the bending processing and the end of the bending processing. And since the effect of prevention of bellows can be exhibited to the maximum, it is preferable. However, as long as the effect of the prevention of flattening and the prevention of bellows is within a range that does not decrease so much, a part of the period during bending processing may be left in a state without restriction by a molding tool. Specifically, a period of about 70% or more of the entire bending process period may be regulated by the molding tool.

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According to the invention of claim 4, prior to the bending operation for the pipe, by means of hot swaging to increase the thickness of the pipe by compressing the pipe in the tube axis direction with respect to the straight pipe portions adjacent to each other in front of the bending point of the pipe. The operation is performed to increase the tube thickness toward the bending time point, and then to the bending processing operation after the operation, and the bending process is started after the thickness of the straight pipe portion is increased. A sudden change in thickness does not occur between the increased bent inner side pipe wall and the straight pipe portion, thereby further preventing the occurrence of bellows. Moreover, in the manufactured metal curved pipe, since the thickness of the straight pipe | tube part by the side of a bending time is increasing toward a curved pipe | tube part, a big step | step does not produce between the pipe wall which increased the thickness of the bending inner side of the curved pipe part, and, therefore, stress concentration There is no such thing as this occurrence or giving great resistance to the fluid in the tube.

According to a fifth aspect of the present invention, in the method for producing a metal curved tube according to claim 4, when the bending processing operation is performed on the tube, and the bending end point of the tube is reached, the tube is concentric with respect to the straight tube portions adjacent to each other behind the tube. It is set as the structure which performs the operation which reduces a pipe thickness starting from the said bending end point by hot swaging process which compresses in a direction and increases a pipe thickness. With this configuration, in the manufactured metal curved pipe, since the thickness of the straight pipe portion on the bending end point side decreases from the curved pipe portion, a large step is not generated between the thickened pipe wall of the curved inner portion of the curved pipe portion. There is no such thing as stress concentration or great resistance to the fluid in the tube.

According to a sixth aspect of the present invention, in the method for producing a metal curved tube according to claim 4, a hot swaging process is performed in which the tube end is press-fitted in the tube axis direction to increase the tube thickness with respect to the straight tube portion located behind the bending end point of the tube. It is set as the structure which adjusts the positioning of the pipe end in the manufactured metal curved pipe by adjusting and adjusting the press-in end point position of the pipe end at that time. With this configuration, even if there is an error in the length of the straight pipe provided in the bending process and there is an error in the bending radius formed by the bending process, the positioning of the tube end of the manufactured metal curved pipe can be adjusted to match a predetermined standard value. Therefore, the dimensional accuracy of the product can be improved.

In the manufacturing method of the metal curved pipe | tube of any one of Claims 4-6, at the start of a bending process with respect to the said pipe | tube, the invention of Claim 7 turns a bending arm, and guides an induction coil rather than a predetermined bending process position. The rotational speed of the bending arm and the moving speed of the guide coil are moved relative to the pipe of the heating section with respect to the bending speed of the bending arm at the time of moving from the position spaced on the tip side toward the bending machining position. By setting the ratio of (i.e., the relative movement speed to the tube of the heating part / swing speed of the bending arm) to decrease gradually with the progress of the bending process, the bending process is performed so that the bending radius gradually decreases from the large bending radius, and the induction coil After the bending machining position is reached, the bending radius is uniformly bent while the guide coil is stopped at the bending machining position. will be. According to this configuration, bending processing is started at a large bending radius, and then the bending radius is gradually reduced to a predetermined bending radius, and thereafter, the so-called multistage bending is performed to continue bending processing at the predetermined bending radius. It is possible to prevent the occurrence of bellows, and to obtain a metal curved pipe having a structure in which the transition portion from the straight pipe portion to the curved pipe portion is smoothly curved.

According to the eighth aspect of the present invention, in the method for producing a metal bent tube according to any one of claims 4 to 6, the bending radius is continuously maintained in a bending radius while the induction coil is stopped at a predetermined bending machining position. At the time point near the end, the bending arm is moved in the tubular axis direction from the predetermined bending processing position toward the rear end of the tube while the turning of the bending arm continues, and the turning speed of the bending arm and the moving speed of the guide coil at that time are By setting the ratio of the relative speed of movement of the bend arm to the tube of the heating part (ie, the relative speed of movement of the bent arm / swing speed of the bending arm) to increase gradually with the progress of the bending process, It is set as the structure which performs bending processing so that a radius may gradually increase from a predetermined bending radius. With this configuration, the so-called multi-stage bending can be performed in which bending is performed while gradually increasing the bending radius from a predetermined bending radius at the end of the bending processing, and the transition portion from the bent portion to the straight tube portion is smoothly curved. A metal bend can be obtained.

According to a ninth aspect of the present invention, in the method for producing a metal curved tube according to any one of claims 4 to 6, the bending processing operation is performed in a state in which a compressive force in the tube axis direction is applied to the tube. The thickness reduction of the bent outer side pipe wall of the curved pipe part can be suppressed.

According to a tenth aspect of the present invention, in the method for manufacturing a metal curved pipe according to any one of claims 4 to 6, the pipe is attached to the end of the pipe in the straight pipe step and then provided to the bending processing operation to provide a curved curved pipe with a flange. It was made to get composition. In this way, the flange is attached to the pipe end of the pipe in the straight pipe step, so that the flange can be attached more easily than when the flange is attached to the curved pipe after the bending process, and the flanged metal curved pipe is manufactured in low cost. can do. In addition, if bending is performed while the flange is attached to the end of the pipe, the end of the pipe is kept round by the flange, so that the inverse flattening that occurred at the end of the pipe during conventional bending processing does not occur. This good curve can be manufactured.

In the manufacturing method of the metal curved pipe | tube of any one of Claims 4-6, the said pipe | tube is provided in the said bending processing operation after forming the improvement for welding in a straight pipe | tube step in the pipe end, and improving for welding. It was set as the structure which acquires an attachment curved pipe. Thus, by forming the improvement for welding in a straight pipe | tube step in a pipe end, the improvement formation operation can be simplified compared with the case where the improvement for welding is formed in the pipe end of a curved pipe | tube after a bending process, Metal curved pipes with improved processing at the end of the pipe can be manufactured with low cost.

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The invention of claim 14 also provides a bending work piece for use in the manufacturing method of the metal curved pipe described above, wherein the bending is performed when the metal straight pipe to be bent is advanced in the tube axis direction through a predetermined bending work position. A bending arm capable of turning around a predetermined support point, comprising a pipe restricting means for holding a straight pipe portion behind the machining position in a predetermined running path, a clamp for holding a tip of the pipe, and a inside of the pipe. An induction coil inserted into the induction coil for heating a small section in the tube axis direction located at the bending processing position of the tube, and cooling means for spraying and cooling a cooling medium to the end of the tube in the region heated by the induction coil of the tube; And the bending arm is directly or through the tube, or a combination of both, to exert a bending moment on the tube by pivoting the bending arm. Which is a configuration that a driving means, and the bending operation of, the molding tool for regulating the bending of the bending deformation proceeds portion outer peripheral surface of the tube outer surface and the inner portion neutral bending both side outer peripheral surface portion. With this configuration, the tube can be hot bent, and the bending process can be performed while the bending process controls the outer circumferential surface of the bend inner portion of the tube and the outer circumferential surface of both sides of the bent neutral portion with a molding tool. Bending can be performed at high speed without producing bellows and flatness.

According to a fifteenth aspect of the present invention, there is provided a configuration including a shape correction guide provided to pivot the molding tool integrally with the bending arm, and the shape correction guide is continuous to the bending deformation progression portion of the pipe. It is composed of a bellows regulating surface that regulates the outer circumferential surface of the bent inner portion to prevent the occurrence of bellows, and a flat regulating surface that regulates the outer circumferential surface of both sides of the bending neutral part to prevent flattening of the pipe. . The shape correction guide of this structure can shape-control not only the bending deformation | transformation progression part of a pipe | tube, but also the curved pipe part of completion | finish of bending deformation during bending process, and can prevent the occurrence of bellows and flatness further.

According to a sixteenth aspect of the present invention, in the bending processing apparatus of claim 15, the shape correction guide includes: a main shaft for integrally rotating the shape correction guide; a bellows preventing member including the bellows restricting surface; and the flat regulating surface. It is set as the structure which has a means of attaching one or two flat prevention plates, the said bellows prevention member, and two flat prevention plates in a detachable form to the said main shaft. In this way, by attaching and detaching the bellows preventing member and the flattening plate with respect to the main shaft, an appropriate liner or the flattening plate can be attached at the position according to the bending condition according to the bending conditions such as the outer diameter and the bending radius of the pipe to bend. It becomes possible to respond easily to the change of bending conditions.

According to a seventeenth aspect of the present invention, in the bending processing apparatus of claim 16, the bellows regulating surface of the bellows preventing member is formed of an arc-shaped surface suitable for the outer peripheral surface of the bent inner portion of the bent portion formed by bending processing, The flat regulating surface is composed of a flat surface. If the bellows regulating surface of the bellows preventing member is made into an arc-shaped surface suitable for the outer circumferential surface of the bent inner portion of the bent portion, good bellows preventing effect can be exhibited. In addition, when the flat restricting surface of the flat prevention plate is a flat surface, the structure becomes simple, and the cost of equipment can be reduced.

In the bending processing apparatus of Claim 16 or 17, the invention of Claim 18 is the flat which provided the expansion part also in the bending radius direction so that the said flat prevention plate can be shared by bending processing in a different pipe outer diameter and a different bending radius. It is a structure provided with a regulation surface, and the said bellows prevention member is equipped with the structure corresponding to the bending process in a different tube outer diameter and a different bending radius, respectively, and attaches the thing suitable for bending processing conditions. With this configuration, in changing the bending processing conditions, only the anti-bellow member can be replaced, and the same flat plate can be used, which can further reduce the equipment cost.

According to a nineteenth aspect of the present invention, in the bending machine according to claim 14, the permanent mold is a roll-shaped or die-shaped tool that regulates the outer peripheral surface of the bending inner portion and the outer peripheral surface of both sides of the bending neutral portion in the bending deformation progressing portion of the pipe. It is made up. By setting it as this structure, the permanent mold | tool of a simple structure can be used and it can also reduce installation cost.

The invention according to claim 20 is the bending machine according to any one of claims 15 to 17, wherein the rear end of the pipe, which is restrained by the clamp of the bending arm, is reduced in the tube axis direction and the pipe length to the clamp is reduced. It is set as the structure provided with the pressurization apparatus to pressurize. This configuration makes it possible to apply a compressive force in the tube axial direction to the pipe during bending processing, and various measures such as bending processing while suppressing the thinning of the outer wall of the bending outer side pipe can be made possible.

In the bending machine according to any one of claims 15 to 17, the invention of claim 21 is configured to provide a means for moving the induction coil in the tubular direction in a region before and after the bending machining position. In this way, the bending process can be performed by various methods by setting the configuration in which the guide coil can be moved. For example, when the tube is used in combination with a pressurizing device for compressing the tube in the tube axis direction, the guide coils are heated in the tube axis direction while heating adjacent pipe portions adjacent to each other in front of the bending point of the tube prior to the bending processing operation. By moving toward the bend point at the same time, pressurizing the tube end in the tube axis direction by the pressurizing means, and applying a compressive force in the tube axis direction to the tube, whereby hot swaging can be performed to increase the tube thickness in the straight pipe portion. By appropriately changing the moving speed of the induction coil at the time and / or the indentation speed of the pipe, the pipe thickness can be increased toward the bending point. When the induction coil reaches the bending point, the bending of the induction coil is stopped and the bending processing is started to perform the bending processing method of claim 4, and the bending processing can be further prevented from generating bellows. When the bending process is continued and the end point of the pipe is reached, hot swaging increases the pipe thickness by moving the guide coil in the direction of the tube axis and in the direction away from the curved part, while the press-in of the tube end continues. Machining can be carried out, and by appropriately changing the moving speed of the induction coil and / or the indentation speed of the tube, the tube thickness can be reduced from the bending end point, and the bending processing method of claim 5 is carried out. can do. Furthermore, for the straight pipe portion located behind the end of bending of the pipe, hot swaging is performed to press the pipe end in the tube axis direction with a pressurizing device to increase the thickness of the pipe while heating the pipe with an induction coil. The press-fit end point position of the tube end can be adjusted, and the bending processing method of claim 6 can be implemented. In addition, the induction coil can be moved in the tubular direction in the region before and after the bending machining position, thereby starting the bending process while moving the induction coil from the front of the bending machining position toward the bending machining position. And the bending processing method of continuing the bending processing by stopping the induction coil at that position when the induction coil reaches the bending processing position, and adopting this method, the bending processing method of claim 7 can be employed. Can be carried out. When the bending end is reached, the bending processing method of moving the guide coil backwards from the bending processing position in the state where the bending arm is continued may be employed. The bending processing method of claim 8 may be employed by adopting this method. Can be carried out.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention shown in drawing is described. 1 is a schematic plan view of a metal pipe bending machine according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view thereof. In Fig. 1 and Fig. 2, 13 is a metal tube to be bent, for example, a steel tube, and a bending machine is set at a predetermined position. In this embodiment, as the pipe 13 provided for bending, as shown in FIG.3 (a), the flange 14 can be fixed to the both ends beforehand. 1 and 2, 15 is a machine main body, 16 is a machine main body 15, a main axis freely held about a vertical axis OO, and 17 is rotated integrally with the main axis 16. The attached bending arm 18 is a clamp (hereinafter referred to as a front clamp) that is attached to the bending arm 17 and grips the tip of the tube 1. By this structure, when the tube 13 moves to the tube axial direction as shown by the arrow E, and the bending arm 17 turns with the support line OO as a support point, the bending moment in the tube 13 is carried out. Can be bent and deformed. Here, in the case where the tube is continuously bent and deformed by applying a bending moment to the bend arm 17 while advancing the tube 13, the bending deformation progression portion of the tube passes through the support point O of the bend arm, thereby providing a tube ( When it is located on the straight line OA perpendicular to the axis of 13), since bending can be performed stably and efficiently, the straight line OA is called "bending processing position" in this specification. In addition, in this specification, expressions such as "front end", "back end", "before", and "after" with respect to the pipe 13 shall be based on the moving direction of the pipe indicated by the arrow E. The front clamp 18 gripping the end of the tube 13 may have any structure that can hold the tube 13 directly and / or via the flange 14 at a desired strength. It is preferable that the outer surface of the region adjacent to the flange 14 and the structure capable of gripping the flange can be gripped with a great strength.

20 is a driving means for turning the bending arm 17 for the bending of the tube, the pinion 21 attached to the main shaft 16, the rack 22 arranged to engage the pinion 21, and The main bending cylinder 23 etc. which make the rack 22 reciprocate are provided. 25 is a rear clamp for holding the rear end of the tube 13, 26 is a rear clamp support holding the rear clamp 25, and is movable in the tube axis direction of the tube 13 by a suitable support guide (not shown). Maintained. 28 is a pressurizing device which presses the rear end of the tube 13 in the tube axis direction and approaches the front clamp 18 holding the tube end, and compresses the tube in the tube axis direction. The movable table 29 which is movable in the tubular direction, the connecting plate 30 which connects the movable table 29 to move together with the rack 22, and the rear clamp support 26 are movable tables 29. And a compression cylinder (31) for driving so as to approach and space apart.

35 is an induction coil which is inserted into the tube 13 and inductively heats the small section in the tube axis direction of the tube in a ring shape, and a cooling medium 36 such as cooling water is provided at the end of the tube in the heated region (FIG. 3). Refrigeration means for jetting and cooling. 37 is a relay lead for maintaining the induction coil 35 and supplying power and cooling medium, 38 is a high frequency transformer movable in the tube axis direction while maintaining the relay lead 37, and 39 is a tube shaft for the high frequency transformer 38. It is a motor for transformer movement to reciprocate in the direction. By moving the high frequency transformer 38 to the transformer moving motor 39, the induction coil 35 can be moved in the tube axis direction in the tube 13. Here, the moving range of the induction coil 35 by the transformer moving motor 39 is set to be the desired range before and after the straight line OA (bending processing position). In addition, in this specification, when describing the position of the guide coil 35 in the axial direction, it guides rather than the position (cooling line) in which the cooling medium 36 injected from the guide coil 35 is injected to the pipe | tube 13. It describes on the basis of the position slightly close to the coil 35 (a position where bending deformation and thickness increase deformation are finished by cooling). Thus, for example, as shown in FIG. 5, when the cooling medium 36 from the induction coil 35 is at a position slightly above the bending machining position OA, the induction coil 36 is bent. Write on the location (OA).

40 is a permanent mold | tool which regulates the outer peripheral surface of the bending inner side part and the outer peripheral surface of both sides of a bending neutral part of the area | region located at least in the bending processing position OA of the pipe 13 during a bending process operation. The permanent mold 40 in this embodiment is provided with the shape correction guide 41 attached by the nut 44 so that it may turn integrally with the bending arm 17, The shape correction guide 41 is The cross section is a unitary structure in which a U-shaped restricting surface 42 is formed in an arc shape with the pivot center O as the center. This restricting surface 42 is made into a shape suitable for the bending inner part outer peripheral surface 13aa of the bent deformation | transformation pipe | tube 13, as shown to expand and show in FIG.6 (b), and the bending inner part outer peripheral surface 13aa is made. Flat regulating surfaces 42b and 42b which regulate the bellows regulating surface 42a for preventing the occurrence of bellows and the outer circumferential surfaces 13ab and 13ab on both sides on the bent neutral portion NN of the tube 13 to prevent flatness. In the bending process of the pipe 13, as shown in Fig. 6 (a), the bent and deformed pipe 13 is restrained by the restricting surface 42 to prevent the occurrence and flattening of the bellows. It can prevent. In Fig. 1, the position where the restricting surface 42 is formed and the length in the circumferential direction are at least rotated from the position shown in Fig. 1 (the position for setting the pipe to be bent) to the end of the bending. During the process, the regulating surface 42 is always positioned on the bending machining position OA. Therefore, during the bending process, the regulating surface 42 can always restrict the region at the bending processing position OA of the pipe 13 and the curved pipe portion formed by the bending process.

46 denotes a pipe restricting means for holding a straight pipe portion behind the pipe 13 at a predetermined travel path when the pipe 13 is bent, wherein the pressure roller 47 is provided. Is used.

In FIG. 2, in the installation of the machine main body 15, the axis line of the pipe 13 set in the apparatus is inclined so that the pipe tip side may be 2 to 3 degrees lower. This is to allow the cooling medium injected into the tube to be quickly discharged out of the tube. In addition, instead of making the machine main body 15 incline at the time of installation, you may attach each part which hold | maintains the tube 13 with respect to 15 so that the tube 13 may incline.                     

Next, the method of manufacturing the metal curved pipe 13A shown in FIG. 7 using the bending temporary factory value of the said structure is demonstrated. This metal curved pipe 13A is provided with the curved pipe part 13a of the bending angle (theta), and the straight pipe end parts 13b and 13c of the length (b, c) of the both ends, and each pipe end is flanged. (14) is attached. Further, each of the tube ends 13b and 13c is provided with transition portions 13bd and 13ce whose thickness increases toward the curved portion in the region of lengths d and e adjacent to the curved portion 13a.

In manufacturing the metal curved pipe 13A, first, as shown in FIG. 3 (a), a metal straight pipe 13 is prepared, and the straight pipe is subjected to hot bending and hot swaging to be described later. The metal curved pipe 13A of desired length is adjusted to the length which can be obtained, and the flange 14 is welded and fixed to both ends. Since the welding fixing operation of this flange 14 is performed with respect to a straight pipe, compared with the case of welding-fixing to the curved pipe after bending process like conventionally, it can perform extremely easily and workability. Next, the straight pipe 13 which fixed the flange 14 at both ends is set to the predetermined position of a bending machine, as shown to FIG. 1, FIG. 2, FIG. 3 (b), and the tip is bent arm 17 ), The rear end is gripped by the rear clamp 25, and the guide coil 35 is inserted into the tube 13. Here, the position of the front clamp 18 is the distance (b) from the front end of the straight pipe 13 to the bending machining position OA of the pipe end 13b on the front side of the metal curved pipe 13A shown in FIG. It is set to be equal to the length b. In addition, since the length b normally required for the pipe end 13b of the metal curved pipe 13A is relatively short, the pipe end of the pipe 13 gripped by the front clamp 18 is separated from the bending processing position OA. In order to be spaced apart by (b), it is necessary to arrange the front clamp 18 at a position approaching the bending machining position OA. As shown, since the induction coil 35 is located in the pipe, The induction coil 35 does not interfere with the front clamp 18, and therefore, the front clamp 18 can be disposed without a problem at a desired position.

Next, in Fig. 3 (b), the guide coil 35 is positioned at a position spaced apart by the distance d from the end of the tube rather than the bending machining position OA. Here, the distance d is set equal to the length d of the transition part 13bd formed in the metal curved pipe 13A shown in FIG. From this state, the hot swaging process for the pipe 13 is first started. That is, as shown in FIGS. 3 (b) and 3 (c), heating by the induction coil 35 is performed while the front clamp 18 is held at a constant position without turning the bending arm 17. A small section facing the induction coil 35 of the tube 13 is heated and heated to a temperature easily plastically deformed, for example, an integrating temperature, and is further cooled to a position at the end of the tube rather than the heating region. While injecting (36), the induction coil (35) is moved toward the bending machining position (OA), and at the same time, the rear end of the tube (13) by advancing the rear clamp (25) to the compression cylinder (31) (see Fig. 1). Press in toward the tip. Thereby, the heated area | region of the pipe | tube 13, ie, a heating part, increases thickness, and moves to the tube axial direction of the pipe | tube 13, cooling and hardening | curing immediately after thickness increase, and a hot swaging process is performed continuously. The thickness increase rate of the pipe wall at this time is determined by the ratio of the press-in speed of the rear clamp 25 and the movement speed of the guide coil 35. In this embodiment, the moving speed of the guide coil 35 is made constant and the press-in speed of the rear clamp 25 is gradually increased. Thereby, the thickness increase rate increases with the movement of the guide coil 35, and the transition part 13bd is formed.

When the induction coil 18 reaches the bending processing position OA, the induction coil 35 is stopped and the process shifts to the bending processing operation. That is, heating and cooling medium injection by the induction coil 35 start operation of the main bending cylinder 23 (see Fig. 2) in the state of being connected, and bend arms through the rack 22 and the pinion 21. (17) is rotated and the compression cylinder 31 is operated simultaneously. Thereby, as shown to FIG.3 (d) and FIG.4 (a), the pipe | tube 13 is bent continuously and the curved pipe part 13a is formed. At this time, the operating speed of the compression cylinder 31 can be secured to a desired compression ratio compared to the bending speed (the speed at which the pipe 13 passes through the bending processing position OA) at the rear end of the pipe 13. Set to press in at speed. Thereby, the compression of a desired compression ratio can be added to the pipe 13 of a bending process position during bending processing, and the thickness reduction of the pipe | tube outer side of a bending can be suppressed. Here, in setting the operating speed of the compression cylinder 31, the compression cylinder 31 itself is moving with the rack 22 which turns the bending arm 17, The moving speed v is For bending speed (V),

v = V × Rs / R

(Where Rs is the pitch circle radius of the pinion 21 and R is the bending radius of the pipe)

Since it is a relationship with, it is good to determine this.

In the above bending process, at the start of bending processing, as shown in Fig. 3 (d), the pipe wall is in a state of increasing thickness, and bending processing is started in this state. Therefore, the bending inner pipe wall is formed by bending deformation. Even when the thickness increases, there is no sudden thickness difference between the pipe wall of the straight pipe and the pipe. For this reason, unstable deformation of bellows or the like is unlikely to occur. In addition, the region at the bending machining position OA of the tube 13 is always bent by the restricting surface 42 of the shape correction guide 41 during bending, as shown in FIG. 6 (a). Since the outer circumferential surface of the inner part and the outer circumferential surface of the neutral part NN are regulated, stable bending deformation occurs, and it is possible to prevent the occurrence and flattening of the bellows. Moreover, since the curved pipe part 13a formed by bending deformation is always regulated by the restricting surface 42 of the shape correction guide 41, the bellows generation and flattening can also be prevented from this point. Furthermore, by arranging the induction coil 35 in the tube, an effect that can further prevent the occurrence of bellows is also obtained as compared with the case where the induction coil 35 is disposed outside the tube. This is for the following reason. That is, when the tube 13 is heated by the induction coil 35 arrange | positioned in a tube, as shown to expand in FIG. 5, a tube inner surface side heats mainly, and an outer surface side is heat-transmitted by the heat transfer from an inner surface. Raise the temperature. For this reason, the temperature of the tube inner surface side is higher than that of the tube outer surface side, and the temperature nonuniformity also increases. For example, when the inner side of the tube is heated to 950 ° C., the temperature range on the inner side of the tube is about 950 ± 20 ° C., but about 920 ± 5 ° C. on the outer side of the tube. If the temperature is high and the nonuniformity is large, it is easy to generate bellows, and therefore, bellows are more likely to be generated on the inner side of the tube than on the outer side of the tube. However, the bending radius (R ₂₎ of the pipe inner surface side, is larger than the bending radius (R ₁₎ of the pipe outer surface side, the compression ratio is smaller than the bending according to the outer surface side, because the bellows are difficult to occur. On the other hand, when heating with the induction coil is performed from the outside of the tube as in the prior art, the temperature on the outer side of the tube is high and the temperature nonuniformity increases, so that it is easy to generate bellows. Since it is larger than the side, it becomes easy to generate more bellows. In this way, the occurrence of bellows can be further suppressed by arranging the induction coil in the pipe.

As described above, in this embodiment, the use of the shape correction guide and the heating from the inside of the pipe can be employed to suppress the occurrence of bellows and flattening. For this reason, for example, bending processing of 1.5DR can be performed at 3 to 6 mm / sec at a bending processing speed which is significantly increased compared with the prior art. In addition, since the attachment of the flattening prevention jig by the manual labor performed conventionally is unnecessary, from this point of view, there is no problem in increasing the bending speed.

As shown in Fig. 4A, the bending process advances, and the turning of the bending arm 17 is stopped when the bending arm 17 is turned to a position where the predetermined bending angle θ is reached. Subsequently, as shown in FIG. 4 (b), the induction coil 35 is moved in the tube axis direction and toward the rear end of the tube while the induction coil 35 continues to spray the heating medium and the cooling medium 36. At the same time, the rear end of the tube 13 is press-fitted in the tube axis direction by the compression cylinder 31. As a result, hot swaging is performed on the straight pipe portion following the curved pipe portion 13a. Also at this time, the moving speed of the guide coil 35 and the press-in speed of the pipe end are set to decrease as the thickness increase rate of the pipe wall is separated from the curved pipe portion 13a. Thereby, as shown in FIG.4 (c), the transition part 13be whose thickness was reduced is formed. Moreover, when this pipe end press-fits, the rear end of the pipe 13 gripped by the rear clamp 25 has a predetermined distance c from the bending machining position OA (of the metal curved pipe 13A shown in FIG. 7). It press-fits until it reaches the length c required by the straight pipe | tube end part 13c). Thereby, even if there is a dimension error at the time of manufacture of the straight pipe 13 or the dimension error which arises in bending process, it can absorb it and it can be set as the product of an extremely accurate dimension. By the above, 13A of flanged metal curved pipes of the shape shown in FIG. 7 can be manufactured.

The obtained metal curved tube 13A has almost no bellows and flatness, and is excellent in dimensional accuracy. In addition, since the flange 14 is attached to both ends of the pipe during bending, the flange 14 holds the pipe 13 in a round shape, which suppresses the flatness that may occur in the curved pipe portion 13a. The effect is exhibited, and flattening is suppressed from this point. In addition, there is no large step between the bent inner side pipe wall and the straight pipe portion subsequent to it, and thus there is no stress concentration point, and thus the strength characteristics are excellent, and further, there is no great resistance to the fluid flowing inside. .

Although the said embodiment performs bending process with respect to the straight pipe 13 with a flange, the straight pipe 13 used for a bending process is not limited to this, You may carry out about a thing without a flange. Also in this case, the processing which needs to be performed at the end of the pipe, for example, the improvement processing, is preferably performed in the straight pipe step prior to the bending processing, since the processing is much easier than when performing after the bending processing.

In addition, although the shape correction guide 41 of the integral structure is used in the said embodiment, the shape correction guide is not only an integral structure, but a suitable combination of components so that it can respond easily to a different bending radius or a different pipe diameter is easy. It may be configured. FIG. 8: shows 41 A of shape correction guides concerning one Embodiment in that case. This shape correction guide 41A is usable with respect to the pipe | tube 50a, 50b, 50c of a different outer diameter, and prevents the flatness of several sheets from the bending arm 17 side to the main shaft 16 of the bending arm 17. Stacking the plates 51a, 51b, 51c, the attachment plate 52, the bellows prevention member 53a, the attachment plate 52, the plurality of flat prevention plates 51c, 51b, 51a, and the pressurizing tool 54 It is attached in the form, and secured by tightening with a nut (55). As shown in Fig. 9A, the bellows preventing member 53a has a partial disk shape, and forms a fitting groove 57 for fitting the main shaft 16 in the center region, and has an arc shape. The bellows regulating surface 58 for regulating the bending inner part outer peripheral surface of the curved pipe part of the pipe 50a is formed in the circumferential surface of the tube 50a. This bellows regulating surface 58 is comprised by the arc-shaped surface suitable for the outer peripheral surface of the bending inner side of the curved pipe part, as shown to FIG. 9 (b). If the width and center angle α of the bellows restricting surface 58 are too small, the bellows-preventing effect is insufficient, so that a certain amount or more is required. Handling becomes difficult. Therefore, it is preferable to select this center angle (alpha) about 30-150 degrees. The bellows prevention member 53a shown is used for the large diameter pipe 50a, and is made into the size corresponding to the outer diameter and bending radius of the pipe 50a. Furthermore, the bellows prevention member of the size corresponding to the pipe | tube 50b, 50c of other outer diameter is also prepared, and can be used instead of the bellows prevention member 53a.

As shown in Figs. 10A and 10B, the anti-flat plate 51a is formed of a flat plate having a partial disc shape, and includes a hole 60 for inserting the main shaft 16 in the center thereof. It is. The circular arc-shaped region 61 shown by hatching in FIG. 10A forms a flat regulating surface that regulates the outer circumferential surface on the bending neutral portion N-N of the curved tube portion of the tube 50a. In addition, in this embodiment, although the flat restricting surface 61 is comprised only by the flat surface, you may make it the arc-shaped surface suitable for the outer peripheral surface of the curved pipe part of a pipe as needed. In FIG. 8 (b), the flattening plates 51b and 51c have the same structure as the flattening plate 51a, but the outer diameter is set smaller so as not to interfere with a tube having a larger diameter than the pipe to be used. .

In the case of bending the pipe 50a having a large diameter by using the shape correction guide 41A having the above-described configuration, the respective parts are assembled and used as shown in Fig. 8B. As a result, the curved pipe portion formed in the region line at the bending deformation position of the pipe 50a to be bent is regulated by the bellows restricting surface 58 of the bellows preventing member 53a to prevent the occurrence of bellows. In addition, the outer circumferential surface of the bending neutral portion is regulated by the anti-flat plates 51a and 51a on both sides to prevent flattening. Next, when bending the pipe 50c having the smallest diameter using the shape correction guide 41A, as shown in Fig. 11A, the bellows preventing member 53c for the pipe 50c is shown. ), And only the flat prevention plate 53c is arranged above the pipe 50c. Thereby, bending process can be performed also about the small diameter pipe 50c, restrict | limiting a bending inner side outer peripheral surface and a neutral position outer peripheral surface. Furthermore, in the case of performing a bending process with a small diameter tube 50c but having a large bending radius, as shown in Fig. 11B, the bellows for the tube 50c and having a large bending radius is shown. 53 d of prevention members are attached, and the flat prevention plates 51a and 51a of large diameter are arrange | positioned in the position which contacts the pipe 50c. This makes it possible to perform bending processing while having a large bending radius with respect to the small diameter pipe 50c and regulating the inner peripheral surface of the bent portion and the outer peripheral surface of the neutral position. As mentioned above, since the shape correction guide 41A of this structure can cope with change of bending processing conditions, such as a pipe diameter and a bending radius, by replacing some parts, the shape correction guide 41 of an integrated structure is used. Compared to the above case, the conditions can be easily changed and the equipment cost can be reduced.

12-14 shows the shape correction guide 41B which concerns on other embodiment. This shape correction guide 41B uses the wide flat prevention plates 51 and 51 which can be commonly used for pipe | tubes, such as another pipe diameter and a different bending radius. As the bellows preventing member, when the bending radius is small, as shown in Fig. 12, a cylindrical body 65 having a bellows regulating surface 66 formed on the outer circumference of the cylindrical surface is used. As shown in FIG. 13, even when the arc-shaped member 67 which forms the bellows regulating surface 68 in the outer periphery of an arc-shaped member is used, and a tube diameter is large, as shown in FIG. The arc-shaped member 70 in which the bellows regulating surface 71 is formed on the outer circumference of the arc-shaped member is used. In addition, cylindrical spacers 72, 73, 74 and the like are attached to the main shaft 16 to adjust the positions of the flattening prevention plates 51, 51. Also in the shape correction guide 41B of this structure, it is easy to respond to different bending conditions, such as a different pipe diameter and a different bending radius, by replacing some parts.

In the above embodiment, all of the permanent molds 40 used for the prevention of bellows and flatness are provided with shape correction guides 41, 41A, 41B, etc., which pivot integrally with the bending arm 17. It is not necessary to rotate together with the bending arm 17, but may be configured to be fixed to the bending processing position. Fig. 15 (a) shows the permanent mold 40A fixed and installed at a fixed position. The permanent mold 40A includes a support arm 80 and a die-shaped mold 81 held on the support arm 80 so as to be positioned on the bending processing position OA of the pipe 13. The mold sphere 81 has a restricting surface 82 for restricting the outer circumferential surface of the bend inner portion and the outer circumferential surface of both sides of the bent neutral portion of the tube 13 located at the bending processing position. By using this permanent mold 40A, it is possible to prevent the bellows and prevent the flatness during the bending of the tube, and to allow the bending processing at a high speed.

In addition, as shown in FIG. 15 (b), the mold 13 used for the permanent mold 40A is not limited to the one-piece structure, and the tube 13 is shown in FIG. 15 (c). Has a bellows preventing member 84 having a bellows regulating surface 85 for regulating the outer circumferential surface of the bent inner portion of the tube 13, and a flat regulating surface 87 for regulating the outer circumferential surface of the bent neutral portion of the tube 13, respectively. It can be set as the structure provided with the two flat prevention plates 86 and 86. FIG. With this configuration, it is possible to easily cope with the change in the bending processing conditions by replacing the bellows preventing member 84 or replacing the flattening prevention plate 86, changing the position, and the like. In the permanent mold 40A shown in Fig. 15 (c), instead of the bellows preventing member 84, a roll having a bellows restricting surface formed on the circumferential surface is used, or instead of the flat prevention plate 86. It is also possible to make changes such as using a roll.

In the bending process method of embodiment shown to FIG. 3, FIG. 4, the metal obtained by stopping the induction coil 35 in the bending process position OA during the period which the bending process is given with respect to the pipe | tube 13 is carried out. In the curved pipe portion 13a of the curved pipe 13A (see FIG. 7), a constant bending radius R is applied over the entire angular range. However, the present invention is not limited to this bending processing method, and the area at which the bent portion starts to bend is gradually reduced so that the bending radius becomes from the bending radius larger than the predetermined bending radius R to the predetermined bending radius R, The area of the end of bending is also applicable to a method of bending processing, that is, multi-stage bending, so that the bending radius gradually increases from the predetermined bending radius R. FIG. Hereinafter, embodiment in this case is described. Fig. 16 shows a metal curved tube 13B manufactured by multi-stage bending, which has a curved tube 13Ba (region indicated by an angle θ ₀ ) and a straight tube at both ends thereof. End portions 13Bb and 13Bc (areas indicated by lengths b ₁ and c ₁ ) are provided. The curved pipe portion 13Ba formed here includes a multistage bent portion (area of angles θ ₁ and θ ₂ and an area of angles θ ₄ and θ ₅ ) and a normal bend portion (angle) at both ends thereof. (θ ₃ )). The normal bending portion is a region of a constant bending radius R, and the multistage bending portion on both sides thereof is a region in which the bending radius R _G gradually increases from the predetermined bending radius R as it moves away from the normal bending portion. Moreover, this multi-stage bending part has the angle | corner in which the whole bending part was made into constant bending radius R, ie, the straight tube shape 13b of length (b, c) shown in FIG. The region (area represented by angle (θ ₂ , θ ₄ )) set within the range of the angle (θ) of the curved pipe portion 13a sandwiched by 13c, and the outside thereof (the straight pipe shape shown in FIG. 7). It consists of the area | region (area of angle (theta) ₁ , theta ₅ ) set in the area | region corresponding to the tube end part 13b, 13c of the above, Therefore, the angle (theta) ₀ of the curved part 13Ba is the indicated angle It extends more than (theta).

Next, a method of bending the metal straight pipe to produce the metal curved pipe 13B will be described. In the manufacturing of the metal curved pipe 13B, the bent temporary factory shown in Figs. 1 and 2 may be used as it is. In order to better prevent the occurrence of bellows, the shape correction guide 41C shown in Fig. 17 is used. It is desirable to. The shape correction guide 41C has, on its outer circumferential surface, a restricting surface 42C that regulates the outer peripheral surface of the bent inner portion of the bent portion 13Ba and the outer circumferential surfaces of both sides of the bent neutral portion, and the bottom of the restricting surface 42C. In addition, it consists of a shape suitable for the outer peripheral surface of the bending inner side of the curved part 13Ba in surface perpendicular | vertical to the rotation axis of 41 C of shape correction guides. That is, the regulating surface (42C) portion corresponding to the bottom of the top bend portion is consisting in an arc shape of a predetermined radius (R _1), the part corresponding to the multi-stage bent portions of the two sides is shaped to gradually radius change have.

In the bending process, first, the straight pipe 13 to be bent is set as shown in Fig. 18A, and the guide coil 35 is bent from the end of the pipe while energizing the guide coil 35. It moves to a position OA at a predetermined speed. And, when the guide coil 35 reaches a position spaced apart from the end of the tube by a distance b ₁ (the same distance as the length of the straight tube end 13Bb formed in the metal curved tube 13B), the guide coil 35 The movement of the coil 35 starts bending processing in the continued state. That is, while sending the pipe 13 in the direction of the tube axis, the bending speed of the bending arm 17 is gradually increased while turning to reach a constant turning speed. At the same time, the moving speed of the guide coil 35 gradually decreases in a form that compensates for the increase in the turning speed of the swing arm (so that the relative moving speed with respect to the pipe of the heating part formed in the pipe by the induction coil 35 becomes constant). Let's go. As a result, the pipe 13 is bent. The bending radius at this time is the relative moving speed (= moving speed of the guide coil 35 + moving speed of the turning arm 17) with respect to the turning speed of the bending arm with respect to the pipe of the heating part. Since it is determined by the ratio (i.e., the relative speed of movement of the tube of the heating part / swing speed of the bending arm), as described above, the speed of rotation of the bending arm 17 is gradually increased, and the speed of movement of the guide coil 35 is increased. By gradually lowering the bending radius, the bending radius is considerably larger than the predetermined bending radius R at the start of bending, and gradually decreases as the bending process proceeds. Here, the turning of the bending arm 17 and the movement of the guide coil 35 are as shown in Fig. 18B, when the turning arm 17 turns by the angle θ ₂ . At a constant speed, the guide coil 35 is set to reach the bending machining position OA and stop in synchronization with it. As a result, the bending radius becomes a predetermined bending radius R when the guide coil 35 reaches the bending processing position OA. The multistage bending part (region shown by angle (theta) ₁ , (theta) ₂ of the metal curved pipe | tube 13B of FIG. 16) by the start side of the bending is formed by the above. By forming the multi-stage bend in the bend start area in this manner, the increase in the thickness of the pipe wall in the bent inner portion is avoided, and unstable deformation such as bellows is unlikely to occur. In the bending process, the guide coil 35 is located at a position spaced apart from the bending end position OA rather than the bending end position OA. Therefore, the bending deformation progression portion of the tube is spaced apart from the bending machining position OA. 42C of the shape correction guide 41C exists in the position which opposes the bending deformation progression part, and it restrict | limits the outer peripheral surface of the bending inner part of the bending deformation progression part, and the outer peripheral surfaces of both sides of a bending neutral part. do. For this reason, bellows generation and flatness are prevented. Further, strictly, the bottom surface of the restricting surface 42C of the shape correction guide 41C is bent inward portion of the bending deformation progression portion of the pipe as the bending progress of the multi-stage bending portion (according to the rotation of the shape correction guide 41C). Although it is spaced apart from the outer circumferential surface, the amount thereof is small, so that swelling of the tube wall when bellows occurs can be suppressed, and the bellows prevention effect can be exhibited. In addition, in order to further ensure the prevention of the bellows, the center position of the shape correction guide 41 is moved in accordance with the rotation of the shape correction guide 41C, and the bottom surface of the restricting surface 42C moves the bending deformation progression portion of the pipe. The inner peripheral surface of the bent inner portion may always be precisely regulated.

After the induction coil 35 reaches the bending processing position OA, the bending processing is continued while the induction coil 35 is stopped at that position. As a result, bending processing at a constant radius R is performed. As shown in FIG. 18C, when the bending arm 17 is further turned by the angle θ ₃ , the turning speed of the bending arm 17 is gradually decreased, thereby reducing the induction coil 35. The movement in the tube axial direction toward the rear end of the tube is started, and the movement speed at that time is gradually increased in such a manner as to compensate for the decrease in the turning speed of the bending arm. Thereby, bending processing is performed gradually increasing a bending radius, and the multistage bending part by the bending end side is formed. And, as shown in Fig. 19, the bending arm 17 is the angle (θ _4), the induction coil 35 at the time of turning by the c ₁ (a straight pipe-shaped tube which forms the metallic bent pipe (13B) from the tube rear end The bending process is completed by reaching a position spaced by the end of the end portion 13Bc). As a result, a multi-stage bending portion having a predetermined angle range is formed. Even in this multi-stage bending, since the restricting surface 42C exists in the position facing the bending deformation progression part of the pipe, bellows generation and flatness are prevented. As described above, the metal curved pipe 13A having the shape shown in FIG. 16 can be manufactured.

In addition, in the embodiment shown in FIGS. 16-19, as shown in FIG. 17, the bottom part of the regulation surface 42C formed in 41C of shape correction guides is in the outer peripheral surface of the bending inner side part of the curved pipe part to be formed. Although it was set as the suitable shape, the bottom part shape of the regulation surface 42C does not necessarily need to be made into the shape exactly suited to the bending inner part outer peripheral surface of a curved pipe part, and may shift | deviate a little. For example, the area | region facing a multistage bending part may approximate a straight line shape or a simple circular arc shape, and can reduce the manufacturing cost of 41 C of shape correction guides by this. As the shape correction guide in the case of performing the multi-step bending shown in Figs. 18 and 19, a prefabricated shape correction guide as shown in Figs. 8 to 14 may be used, and in addition to the shape correction guide, As shown in FIG. 15, 40 A of permanent mold | type tools provided separately from the bending arm 17 may be used. In this case, it is preferable that the mold sphere 81 for restricting the bending deformation progressing portion of the pipe is moved in the tube axis direction in conjunction with the movement of the guide coil so that the bending deformation progressing portion can always be regulated. In the above embodiment, when the multi-stage bending is performed, the moving speed of the guide coil 35 is increased or decreased to compensate for the increase or decrease of the swing speed of the swing arm, and is formed in the pipe by the guide coil 35. The relative movement speed with respect to the pipe of a heating part is made constant. This is preferable because the induction coil 35 can obtain the advantage of making the heat amount to be injected into the pipe constant. However, this is not a requirement of performing the multi-stage bending, and therefore, the moving speed and bending of the induction coil 35. The turning speed of the arm 17 can be changed suitably.

According to the method and apparatus of the present invention, it is possible to increase the bending speed while preventing the bellows and / or flattening at the time of bending the metal tube, thereby reducing the manufacturing cost of the metal curved tube. In addition, it is possible to perform bending processing on a pipe that has a flange attached to the pipe end in the straight pipe step, or to perform bending processing on a pipe that has been improved on the pipe end in the straight pipe step. Compared with the case of performing, the cost of flange installation and improved machining can be greatly reduced, and the manufacturing cost of the metal curved pipe can also be greatly reduced from this point. Thus, the present invention has the effect that a high quality metal curved pipe can be produced in a low cost.

Claims (21)

delete delete delete With respect to the metal straight pipe 13, the small section in the tube axis direction of the tube is heated to a temperature easily plastic deformation by induction heating, while the heating portion 7 formed by the heating is moved relative to the tube axis direction. A metal curved tube 13A provided with a bent portion 13a and straight tube ends 13a and 13b at both ends thereof by applying a bending moment to the heating portion to bend deformation and cooling immediately afterwards. ), The induction coil 35 for the induction heating is disposed only on the inner side of the tube, and further, the outer peripheral surface of the bending inner portion and the outer peripheral surface of both sides of the bending neutral portion of the bending deformation progressing portion of the outer peripheral surface of the tube are regulated with a molding tool. While the bending processing operation is performed, the pipe is compressed in the tube axis direction with respect to the straight pipe portions adjacent to each other in front of the bending point of the pipe prior to the bending processing for the pipe. The increased hot sway by the ranging processing is performed an operation for increasing towards the bending point, the wall thickness, method of manufacturing a metallic bent pipe after another, standing, characterized in that in a configuration that transfers to the bending operation in the operation of the thickness. 5. The method according to claim 4, wherein the bending operation is performed on the pipe, and when the end point of bending of the pipe is reached, the pipe is compressed in the tube axis direction with respect to the straight pipe portions adjacent to each other behind the hot portion to increase the thickness of the pipe. A method for producing a metal curved pipe, characterized by performing a step of decreasing the pipe thickness by the swaging process starting from the bending end point. 5. The hot end of the pipe end press-fitted at the end of the tube at the end of the bending end point of the tube is subjected to hot swaging to increase the thickness of the tube. Adjusting the positioning of the end of the pipe in the manufactured metal curved pipe. The bending coil 17 is rotated at the start of bending processing with respect to the said pipe | tube, and the induction coil 35 is located in the tube tip side rather than a predetermined bending processing position in any one of Claims 4-6. The rotational speed of the bending arm 17 and the moving speed of the induction coil are moved from the spaced apart position toward the bending processing position, and the relative moving speed of the heating section relative to the pipe of the heating section with respect to the bending speed of the bending arm 17. By setting the ratio to gradually decrease with the progress of the bending process, the bending process is performed so that the bending radius R gradually decreases from the large bending radius, and after the induction coil reaches the bending processing position, the induction coil is subjected to the bending process. A method for producing a metal curved pipe, characterized in that bending is performed at a constant bending radius in a stationary state. 7. The bending process according to any one of claims 4 to 6, wherein the bending of the induction coil 35 is stopped at a predetermined bending processing position, the bending processing is continued at a constant bending radius, and at the point of closeness at the end of the bending processing, Rotation of the bending arm moves the induction coil in the tube axis direction from the predetermined bending processing position toward the rear end of the tube in a continuous state, and the turning speed of the bending arm and the moving speed of the induction coil at that time are converted to the turning speed of the bending arm. By setting the ratio of the relative moving speed with respect to the tube of the heating section 7 to gradually increase with the progress of the bending process, thereby bending the metal so that the bending radius gradually increases from the predetermined bending radius. Manufacturing method. The method for producing a metal curved pipe according to any one of claims 4 to 6, wherein the bending processing operation is performed in a state in which a compression force in the tube axis direction is applied to the tube. 7. The method for manufacturing a metal curved pipe according to any one of claims 4 to 6, wherein the pipe is attached to the end of the pipe in a straight pipe step and then provided to the bending operation to obtain a curved pipe with a flange. . The metal according to any one of claims 4 to 6, wherein the tube is formed at the end of the tube in a straight pipe step, and then provided to the bending operation to obtain a welded curved tube for welding. Method of manufacturing a curved pipe. delete delete delete When the metal straight pipe to be bent moves forward through the predetermined bending position and advances in the direction of the tube axis, the pipe restricting means for holding the straight portion behind the bending position at the predetermined traveling path, and holding the end of the tube A bending arm capable of turning around a predetermined support point, an induction coil inserted into the tube and inductively heating a small section in the tube axis direction located at the bending machining position of the tube; Cooling means for injecting and cooling a cooling medium into the tube tip side of the region heated by the induction coil of the tube and directing or bending the bending arm to exert a bending moment on the tube by turning the bending arm. The drive means for turning through or through both, and the inner peripheral surface of the bending inner portion of the bending deformation progressing portion in the outer peripheral surface of the pipe during the bending processing operation. A shaping tool for regulating the outer circumferential surface of both sides of the force neutral portion, and having a shaping guide provided so that the shaping tool pivots integrally with the bending arm 17, and the shaping guide is a bending of the tube. The bellows regulating surface 42a which regulates the outer circumferential surface of the bent inner portion for the deformation progressing portion and the continuous bent deformed curved portion that is continuous thereto, and prevents the occurrence of bellows, and the outer circumferential surfaces of both sides of the bent neutral portion NN are regulated. Bending processing apparatus of a metal pipe characterized by having flat control surfaces 42b and 42b which prevent flattening. The bellows prevention member (84) provided with the main shaft (16) which rotates integrally with the said bending arm (17), the said bellows restricting surface (85), and the said flat regulation And a flat plate (86, 86) having a surface, and means for attaching the bellows preventing member and the two flat plate in a detachable form to the main shaft. The bellows regulating surface of the said bellows prevention member is comprised by the arc-shaped surface suitable for the outer peripheral surface of the bending inner side of the curved pipe part formed by bending processing, and the flat regulating surface of the said flat prevention plate is comprised by the flat surface. Bending processing device for metal pipes, characterized in that. 18. The bellows control surface according to claim 16 or 17, wherein the flattening prevention plate is provided with a flat regulating surface provided with an extension part in a bending radius direction so as to be common to bending processing at different tube outer diameters and different bending radii. The prevention member is a bending apparatus for a metal tube, characterized in that a plurality of structures corresponding to bending processing at different pipe outer diameters and different bending radii are prepared and attached to those suitable for bending processing conditions. 16. The bending machine according to claim 15, wherein the forming tool is a roll-shaped or die-shaped tool that regulates an outer circumferential surface of the bent inner portion and an outer circumferential surface of both sides of the bent neutral portion of the bent deformation progressing portion of the tube. 18. The method according to any one of claims 15 to 17, wherein the rear end of the tube (13) whose tip is constrained by the clamp of the bending arm (17) is pressed in the tube axial direction and the tube length to the clamp is reduced. A bending device for metal pipes, characterized by comprising a pressurizing device (28). 18. The bending machine according to any one of claims 15 to 17, comprising means for moving the induction coil (35) in the direction of the tube axis in the region before and after the bending machining position.

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