JP6144519B2 - Metal tube twisting method - Google Patents

Description

  The present invention relates to a torsion processing method and apparatus for a metal tube that twists in the outer peripheral direction of a metal tube having a polygonal cross section, and more particularly to a torsion processing method and apparatus for a metal tube suitable for processing a torsional shape with high accuracy and stability. is there.

  2. Description of the Related Art Conventionally, metal pipes having a polygonal cross section and twisted in the pipe outer peripheral direction around the pipe axis direction have been proposed. Such a twisted metal tube is expected to be applied to various applications such as vertical bars and piles of handrails, decorative members, and shock absorbing members.

  In order to actually twist the metal pipe having such a polygonal cross section in the pipe outer peripheral direction, for example, as shown in FIG. 15A, the metal pipe 7 having a quadrangular cross section composed of a plane portion 71 and a corner portion 72 is used. Four rolls 74 are arranged around the center. For example, the roll 74 is disposed at an angle such that the contact surface of the roll 74 and the flat portion 71 can be in surface contact with each other in parallel. Further, the contact position of the flat surface portion 71 with respect to the contact surface of the roll 74 is a portion of the flat surface portion 71 that is extremely close to the corner portion 72.

  A plurality of such roll pairs including four rolls 74 are provided in the tube axis direction. And about a mutual roll pair, the arrangement | positioning angle is shifted and arrange | positioned toward the pipe | tube outer peripheral direction centering | focusing on the pipe-axis direction. And the rotational force for conveying the metal pipe 7 to a pipe-axis direction is provided about at least one of the four rolls 74 in each roll pair, and this is driven. As a result, an external force in the direction of the arrow in the drawing is applied to the metal tube 7 and a clockwise torque is generated, which causes torsional deformation in the tube outer peripheral direction.

  By the way, when attention is paid to one flat surface portion 71a, this flat surface portion 71a can be considered as a model of a beam having one end fixed. The external force P actually applied to the flat surface portion 71a from the outside via the roll 74 is in the same direction as the extending direction of the flat surface portion 71a, as shown in FIG. As a result, when the external force applied to the flat portion 71 exceeds the buckling load (= Pcr), the flat portion 71 is buckled. This buckling load Pcr depends on the material strength and material, the length and thickness of the flat portion 71, and also the curvature at the corner portion 72, but until the flat portion 71 exceeds Pcr and starts buckling. A considerable external force P must be applied.

  And once buckling generate | occur | produces about this plane part 71, the plane part 71 begins to incline with respect to the load direction of the external force P, As a result, as shown in FIG.15 (c), plane part 71 itself has become. Crushing and deepening buckling. Further, as the buckling progresses and the difference in the inclination angle with respect to the load direction of the external force P of the flat surface portion 71 increases, the bending moment based on the external force P applied to the flat surface portion 71 further increases, and as a result, the buckling progresses rapidly. Will be. By repeating this, the flat surface portion 71 is rapidly bent, irregularly twisted and crushed, and eventually remains in the form of damage. In particular, since the metal tube 7 may be twisted and applied as a decorative member, it is necessary to prevent the flat portion 71 from being crushed irregularly by buckling as much as possible.

  As a conventional method for twisting a metal tube, for example, as shown in Patent Document 1, rolls are arranged radially, and a starting material is fed into this to perform twisting.

  However, in the disclosed technique of Patent Document 1, if the torsion angle is excessively increased, the inclination of the external force P of the flat portion 71 with respect to the load direction increases, and buckling occurs. For this reason, it is difficult for the disclosed technique disclosed in Patent Document 1 to perform twisting with a large torsion angle, and in order to twist without causing buckling, it is at best to set the torsion angle to 25 ° at most. there were.

  Moreover, according to the disclosed technique of Patent Document 2, a round pipe is passed in advance in a metal pipe (square pipe), and twisting is performed in this state. During the twisting process, the inner diameter of the square pipe becomes smaller, and when it hits the round pipe inside, no further twisting occurs, and a uniform twisting pitch can be realized. According to this method, it is possible to prevent the above-described buckling of the flat portion 71.

Japanese Patent Laid-Open No. 61-259838 Japanese Patent Laid-Open No. 7-80556

  In general, torsional deformation, when this torsional stress is applied, a starting recess is formed as a starting point of torsional deformation formed in the metal tube, and the torsional deformation gradually progresses from the recess toward the tube axis. To do.

  However, in the technique disclosed in Patent Document 2 described above, since the round pipe is merely loosely fitted and twisted in the square pipe, the above-described starting recesses are irregularly generated. Then, if the position of the starting recess of the torsional deformation formed first is irregular, the torsional deformation starting from this becomes irregular, and the desired uniform torsional shape is obtained. The problem that it is hard to form arises. Further, particularly in recent years, there is a social request to freely control the twist shape (torsion angle and pitch) according to the user's preference. However, in the disclosed technique of Patent Document 2, the request described above meets the request. I couldn't respond.

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to be able to process a uniform torsional shape with high accuracy and stability, and to change the torsional shape of the user. An object of the present invention is to provide a method of twisting a metal tube that can be freely controlled according to preference.

  In order to solve the above-mentioned problems, the present inventor has formed a plurality of recesses formed by plastic deformation of the metal tube inside the tube in the tube circumferential direction, and then inserted the core into the metal tube, with the tube axis direction being the center. As a result, it was found that a uniform torsional shape can be processed accurately and stably by twisting in the tube outer peripheral direction.

A method of twisting a metal tube to which the present invention is applied is a method of forming a plurality of recesses plastically deformed by pressing a metal tube toward the inside of the tube, and forming a core in the metal tube in which the recesses are formed. The metal tube having the core inserted therein is twisted in the tube outer peripheral direction around the tube axis direction, and in the torsion processing , the metal tube having a substantially square shape in cross section composed of a flat portion and a corner portion is formed. A reference roll pair and a twisting roll pair are conveyed in this order, and the right end or the left end of each plane portion is brought into contact with the plane from a substantially vertical direction by the reference roll pair, and the tube axis from the reference roll pair Depending on the desired twist angle with respect to the pitch in the direction, the twisted roll pair provided by rotating from the contact surface of the reference roll pair in the outer circumferential direction of the pipe, Press the left end Characterized by twisting the Te.

In this case, roll pair recess formed on the Symbol metal tube, the reference roll pair, in during the transport in the order of the twisting process roll pairs, tubes each planar portion of the metal pipe by the recess-forming roll pair You may make it form the said recessed part by pressing toward an inner side.

A method of twisting a metal tube to which the present invention is applied is a method of forming a plurality of concave portions plastically deformed by pressing a metal tube through which a core is inserted in advance toward the inside of the tube in the pipe circumferential direction. When the metal pipe is transported in the order of a recess-forming roll pair, a reference roll pair, and a twisting roll pair, the metal is then twisted in the pipe outer peripheral direction around the pipe axis direction. The concave portions are formed by pressing each flat portion of the tube toward the inside of the tube .

  According to the present invention having the above-described configuration, a uniform torsional shape can be processed accurately and stably. Further, according to the present invention having the above-described configuration, the torsional shape can be freely controlled according to the user's preference.

  Further, according to the present invention having the above-described configuration, the twist depth and width can be positioned (centered) by twisting by inserting the core, and stable torsion molding without deviation can be achieved.

It is a top view of the twist processing apparatus to which this invention is applied. It is a front view of the twist processing apparatus to which this invention is applied. In the twist processing apparatus to which this invention is applied, it is a figure which shows the detailed structure from a side surface. It is a front sectional view of a pair of rolls for forming recesses in a twist processing apparatus to which the present invention is applied. It is an enlarged plan view of the metal tube pressed by the pair of recess forming rolls. It is a front sectional view of a reference roll pair in a twist processing apparatus to which the present invention is applied. It is the figure which carried out vector display of the external force loaded with a roll with respect to a metal pipe. It is a figure for demonstrating the roll pair for a twist process. (A) is a figure which shows the state before the rotation adjustment to the pipe | tube outer periphery direction of the twist pair for twist processing, (b) is a figure which shows the roll pair for twist processing in the state in which the rotation adjustment was made. is there. It is FIG. 1 for demonstrating the twisting operation | movement by the twisting apparatus to which this invention is applied. It is sectional drawing for demonstrating the twisting operation | movement by the twisting apparatus to which this invention is applied. It is FIG. 2 for demonstrating the twisting operation | movement by the twisting apparatus to which this invention is applied. It is FIG. 3 for demonstrating the twisting operation | movement by the twisting apparatus to which this invention is applied. It is a figure which shows the example which actually twists about the metal pipe of a cross section substantially circular. It is a figure for demonstrating the problem of a prior art.

  Hereinafter, as an embodiment of the present invention, a metal tube twisting device for twisting a metal tube in the tube outer peripheral direction will be described in detail with reference to the drawings.

  FIG. 1 is a plan view of a twisting apparatus 1 to which the present invention is applied, and FIG. 2 (a) is a front view thereof. The twist processing apparatus 1 includes a drive motor 19, a speed reducer 18 connected to the drive motor 19, and a drive shaft 16 connected to the speed reducer 18. The twist processing apparatus 1 includes the molding machine bed 3, a stand frame 10 erected on the molding machine bed 3, and a roll pair 4 including a plurality of rolls 2 provided on the stand frame 10. I have. As shown in FIG. 1, a plurality of stand frames 10 including these roll pairs 4 are provided at intervals in the direction of the tube axis of the metal tube 5. Further, a core 41 is inserted into the metal tube 5.

  The metal tube 5 processed by the twist processing apparatus 1 is made of, for example, iron or an aluminum alloy, but may be made of any material as long as it is made of metal. Moreover, the metal tube 5 may be comprised by the cross-sectional polygonal shape, for example, is comprised by the cross-sectional regular polygon. In the following example: A description will be given by taking the metal tube 5 having a regular square cross section as an example.

  The metal tube 5 having a square cross section includes a form in which corners 52 are rounded, as shown in FIG. 2B, for example. In such a case, the flat portion 51 formed between the corner portions 52 is not limited to a complete flat surface, and includes one having a certain degree of curvature. In other words, the metal tube 5 is not limited to a polygon having a cross section in a complete geometric sense, but is a substantially regular polygon in which the corner 52 and the plane 51 have a certain degree of curvature. May be.

  Further, the metal tube is not limited to a square shape in cross section, and may have a circular cross section or an irregular cross sectional shape.

  The drive motor 19 rotates the drive shaft 16 based on the supplied power. The power based on the drive shaft 16 that is rotationally driven by the drive motor 19 is transmitted to the stand frame 10 side via the speed reducer 18.

  The roll 2 provided in the stand frame 10 is incorporated by a roll shaft 21 provided in the stand frame 10, and is provided so as to be rotatable around the roll shaft 21. A rotational driving force from the drive shaft 16 is transmitted to any one or more of the roll shafts 21. Then, by rotating the roll shaft 21 to which the rotational driving force is transmitted, the roll 2 can rotate. As a result, the metal pipe 5 to be formed can be sent out from the upstream side to the downstream side in the pipe axis direction while performing desired processing as necessary. When actually forming the metal tube 5, the metal tube 5 is inserted into the central region surrounded by the rolls 2.

  A reduction adjusting bolt 20 is inserted and screwed from the outer peripheral surface of the stand frame 10. The insertion position of the reduction adjusting bolt 20 corresponds to the position where the roll 2 is disposed. The tip of the reduction adjustment bolt 20 can be brought into contact with the roll 2, and by tightening the reduction adjustment bolt 20, the roll 2 can be pushed inward to adjust the position. It is possible to adjust the pressing amount.

  The core 41 is composed of, for example, a metal pipe. The core 41 preferably has a substantially circular outer periphery in cross section, but is not limited thereto, and may have any cross sectional shape. The diameter of the core 41 may be any diameter as long as it can be inserted into the metal tube 5, but preferably has an outer diameter that is loosely fitted to the inner diameter of the metal tube 5. It is configured.

  FIG. 3 is a diagram showing a detailed configuration from the side in the twisting apparatus 1 to which the present invention is applied. In the twisting device 1, a concave forming roll pair 4a, a reference roll pair 4b, and a twisting roll pair 4c for conveying the metal tube 5 are provided in order from the upstream side to the downstream side in the tube axis direction. Further, the above-described core 41 is inserted into the metal tube 5.

  As shown in the front cross-sectional view shown in FIG. 4, the recess forming roll pair 4 a presses the metal tube 5 having a quadrangular cross section from the four directions toward the inside of the tube. FIG. 5 shows an enlarged plan view of the metal tube 5. The respective rolls 2a-1 to 2a-4 in the recess forming roll pair 4a are pressed against the respective flat portions 51 in the metal tube 5 having a quadrangular cross section including the flat portions 51 and the corner portions 52. The rolls 2a-1 to 2a-4 are provided according to the number of surfaces of the flat portion 51. In the metal tube 5 having a quadrangular cross section, the pressing directions are four directions with respect to each surface.

  At this time, it is desirable that the pressing position of each of the rolls 2a-1 to 2a-4 with respect to the plane portion 51 is exactly the center of the cross section of the plane portion 51 as shown in FIG. This is because the torsional external force applied in the subsequent stage is applied more evenly, and a torsional shape with consistency can be obtained. However, it is not indispensable that the pressing position of each of the rolls 2a-1 to 2a-4 is the center of the cross section of the plane portion 51, and it may be any other location.

  The shape of the contact surface of the rolls 2a-1 to 2a-4 with the flat surface 51 may be provided with a curvature as shown in FIG. 4, but is not limited to this and is a flat shape. It may also be a tapered shape.

  Further, in the present invention, through pressing of the rolls 2a-1 to 2a-4 against the flat portion 51, the flat portion 51 is plastically deformed toward the inside of the tube as shown in FIG. Let it form. That is, it is not sufficient to press the flat portion 51 in a mere elastic range, and a pressing amount is required to the extent that plastic deformation occurs and the concave portion 53 is formed. And the location corresponding to the recessed part 53 formed through such plastic deformation has produced work hardening, and has hardened compared with the other location.

  In addition, in the stage where this recessed part 53 was formed, the core 41 and the recessed part 53 may be mutually separated as shown in FIG.5 (b), and may mutually contact. In the following example, a case where the core 41 and the recess 53 are separated will be described as an example.

  In this way, as shown in FIG. 5B, the metal pipe 5 having the recess 53 formed in the flat part 51 is conveyed from the upstream side to the downstream side in the pipe axis direction and reaches the reference roll pair 4b. To do.

  FIG. 6 is a configuration diagram of the reference roll pair 4b. In FIG. 6 which shows this reference | standard roll 4b, about the same component and member as FIG. 2 mentioned above, the description below is abbreviate | omitted by attaching | subjecting the same code | symbol.

  The reference roll 4 b includes a drive motor 19, a speed reducer 18 connected to the drive motor 19, and a drive shaft 16 connected to the speed reducer 18, and a roll to which power from the drive shaft 16 is further transmitted. The shaft 21 and the rolls 2b-1 to 2b-4 in the reference roll pair 4b connected to the roll shaft 21 are provided in the stand frame 10. The stand frame 10 is further provided with a reduction adjusting bolt 20 that can push the roll 2 inward.

  The rotational driving force from the drive motor 19 is transmitted to the rolls 2b-1 and 2b-3 in the reference roll pair 4b, and the rolls 2b-1 and 2b-3 can rotate to transport the metal tube 5. Become. Incidentally, the rotational driving force from the drive motor 19 is sufficient for conveying the metal tube 5 as long as it is provided at least in the recess forming roll pair 4a in FIG. 3 described above. May not be particularly arranged.

  With the rolls 2b-1 to 2b-4 in the reference roll pair 4b, as shown in the front sectional view of FIG. 6, the left end when viewed to the center of the metal tube in each flat portion 51 of the metal tube 5 is the plane. It is made to contact from a substantially vertical direction. It is desirable that the contact position is extremely near the corner 52 at the left end of the flat portion 51. Moreover, the contact position of each roll 2b-1 to 2b-4 to the metal tube 5 may be the right end when viewed from the center of the metal tube of each flat portion 51. Even in such a case, the contact position needs to be the right end of all the plane portions 51, not the right end of one plane portion 51. Each of the rolls 2b-1 to 2b-4 is provided according to the number of surfaces of the flat portion 51.

  FIG. 7 is a vector display of the external force applied to the metal tube 5 by the rolls 2b-1 to 2b-4. As long as the vector direction of the external force loaded on the metal tube 5 by the rolls 2b-1 to 2b-4 can support the flat portions 51, the flat portion before the formation of the concave portion 53 shown by the dotted line is shown. 51 may be inclined.

  The external force applied by the reference roll pair 4b is set to a small external force that is within the elastic deformation range. That is, the reference roll pair 4b may simply have a pressing force that can support the flat portions 51 of the metal tube 5.

  Thus, the metal pipe 5 in which the plane portion 51 is supported by the rolls 2b-1 to 2b-4 is conveyed from the upstream side to the downstream side in the pipe axis direction, and reaches the twisting roll pair 4c. It will be.

  In this twisting roll pair 4c, the rolls 2c-1 to 2c-4 constituting the twisting roll pair 4c are rotated and adjusted in the pipe outer peripheral direction according to the desired twist angle θ as shown in the side view of FIG. 3 and FIG. A turntable 9 provided and a fixing plate 11 for fixing the turntable 9 are provided on a pedestal 17. The turntable 9 has a gear 9a formed on a part of the outer periphery thereof, and a rotation control unit 13 configured to be able to rotate the gear 9a in the outer peripheral direction. Further, a lock mechanism 12 for fixing the rotational position of the rotary disk 9 is provided.

  The fixed plate 11 is erected on the pedestal 17 and is provided with a hole 14 through which the metal tube 5 is inserted. A locking mechanism 12 is attached to the fixed plate 11.

  As shown in FIG. 3, the lock mechanism 12 may be configured in any shape that can grip the rotating disk 9. The gripping of the turntable 9 by the lock mechanism 12 may be realized through tightening of the screws 15.

  The rotation control unit 13 is continuously provided with a concavo-convex portion 13 a that can be fitted to a gear 9 a formed on the outer periphery of the rotating disk 9. By rotating the rotation control unit 13, it is possible to control the turntable 9 to be rotatable in the outer peripheral direction via a gear 9 a fitted to the rotation control unit 13.

  FIG. 9A shows a state before the rotation adjustment of the twisting roll pair 4c in the pipe outer peripheral direction. Incidentally, the configuration of the gear 9a is omitted in FIG. The torsion angle θ is set with reference to the reference line A in the rolls 2c-1 to 2c-4 before the rotation adjustment. The twist angle θ is adjusted based on a desired twist angle with respect to the interval (pitch length) between the reference roll pair 4b and the twisting roll pair 4c. And this is adjusted by rotating the turntable 9 which comprises this twisting roll pair 4c to the pipe | tube outer peripheral direction over twist angle (theta). FIG. 9B shows the twisting roll pair 4c in a state where the rotation is adjusted. It is shown that it is rotated from the reference line A toward the outer periphery of the tube by the twist angle θ.

  Note that the twisting roll pair 4c may be provided not only in one stage but also in a plurality of stages from upstream to downstream in the tube axis direction. In such a case, adjustment is made so that the angle θ from the reference line A increases as it goes downstream so that the shape is finished with the same twist angle.

  Incidentally, it is desirable that the distance between the reference roll pair 4b and the twisting roll pair 4c is as close as possible. This is because the closer these distances are, the smaller the elastic deformation can be achieved, and the twisting can be effectively realized by increasing the amount of plastic deformation.

  The actual processing method by the twist processing apparatus 1 having the above-described configuration will be described.

  First, at time t1 before twisting, as shown in FIG. 10, a core 53 is inserted after a recess 53 as plastic strain is formed in the end 5a of the metal tube 5 in advance. As a result, as shown in FIG. 11, when the cross sections P, Q, and R are sequentially captured from the end portion 5 a of the metal pipe 5 toward the tube axis direction C, any cross section P, Q, R at time t <b> 1. In this case, the recess 53 and the core 41 are slightly separated from each other. In the following description, for the sake of simplicity, it is assumed that the recesses 53 as pre-strains are formed for all of the cross sections P, Q, and R. However, the recesses become closer to the cross section R located further downstream. It is possible that 53 is not formed.

  Next, the metal pipe 5 is conveyed from the upstream side to the downstream side through the twisting device 1 in the pipe axis direction C. As a result, torsional stress is applied to the metal tube 5 in the torque direction T in FIG. 10 by the twisting roll pair 4c. The time at this stage is t2.

  FIG. 12 shows the torsional deformation state of the metal tube 5 at time t2. As a result of the torsional deformation from the end 5a side of the metal tube 5 toward the torque direction T, as shown in FIG. 11, the recess 53 tends to deform further inward at time t2. However, in the process of deforming inward, since the core 41 is disposed in the pipe, the force that the concave portion 53 tries to deform further inward is suppressed. That is, when torsional stress is applied, the recess 53 in the cross section P is deformed inward and comes into contact with the core 41. However, this metal core 41 can resist the force to be deformed to the inside of the recess 53, and the deformation to the inside of the recess 53 itself is suppressed. In the cross section P, the depth of all the recesses 53 is made uniform by the core 41.

  As a result of conveying the metal tube 5 further in the tube axis direction C from the time t2 and applying a torsional stress in the torque direction T by the twisting roll pair 4c, in the cross section P, as described above, Due to the presence of the child 41, the concave portion 53 is restrained from further inward deformation. However, the stress based on the torsional stress described above propagates in the tube axis direction C in which the inward deformation is not constrained. Specifically, the point indicated by the arrow starts from the recess 53 shown in FIG. It will propagate in the direction.

  The cross section Q is in a state where the deformation is not constrained by the core 41 because it has not yet been deformed inward at the time of the initial t1. For this reason, when such stress in the direction of the arrow is applied, the flat portion 51 in the cross section Q is easily deformed inward. Then, as a result of the stress in the arrow direction being applied at the stage of time t2, the plane portion in the cross section Q is deformed inward as shown in FIG. 11, and a new recess 53 is formed. Become. That is, as a result of suppressing the inward deformation due to the presence of the core 41 as in the cross section P, energy based on the torsional stress is spent on plastic deformation of the cross section P shifted in the tube axis direction C side.

  FIG. 13 shows a torsional deformation state of the metal tube 5 at time t3. As a result of torsional deformation from the end 5a side of the metal tube 5 toward the torque direction T, not only the cross section P but also the concave portion 53 of the cross section Q is further deformed inward as shown in FIG. In the process of deforming inward, the recess 53 in the cross section Q is deformed inward and comes into contact with the core 41. In such a case as well, it becomes possible for the core 41 to counteract the force to be deformed inwardly with respect to the concave portion 53 of the cross section Q. It becomes. In the cross section Q, the depth of all the recesses 53 is made uniform by the core 41.

  Incidentally, since the cross section R is not yet deformed inward at the time t2, the deformation is not restrained by the core 41. For this reason, when a torsional stress is applied, the flat portion 51 in the cross section R is in a state where it is easily deformed inward. Then, at the stage of time t3, as a result of applying stress in the direction of the arrow in the drawing, the plane portion in the cross section R is deformed inward as shown in FIG. 11, and a new recess 53 is formed. It will be. That is, as a result of suppressing the inward deformation due to the presence of the core 41 as in the cross section Q, energy based on the torsional stress is expended in plastic deformation of the cross section Q shifted in the tube axis direction C side. As a result, it becomes possible to advance the inward deformation along the direction corresponding to the torsion angle.

  By repeating such an action, the torsional deformation is gradually applied toward the tube axis direction C. This torsional deformation gradually deforms the metal tube 5 inward along the direction corresponding to the torsion angle by the torsion processing, starting from the recess 53 provided in the end portion 5a in the tube axis direction C in advance. . Then, by gradually developing the recess 53 in the tube axis direction C, it is possible to form a single twisted line in which the recess 53 is connected in the direction of the arrow in the figure. If a plurality of the recesses 53 are provided, a plurality of torsion lines starting from these will be formed, and a torsion pattern will be applied to the entire metal tube 5.

  Incidentally, when it is desired to control this twist pattern, it can be realized by adjusting the twist angle θ in the rotary disk 9 constituting the processing roll pair 4c. As a result, the torque in the torque direction T is determined, the torsion angle by twisting is also determined, and the flat portion 51 of the metal tube 5 can be gradually crushed in the direction of the arrow in the drawing to form a recess 53. It becomes. That is, the direction of the torsion line can be freely controlled.

  In addition, the twist pattern may be controlled by controlling the position of the recess 53 formed on the metal tube 5 from the beginning by the recess forming roll pair 4a. Since the twist line is extended from the concave portion 53 which is the starting point, a desired twist pattern can be realized by extending the twist line from the concave portion 53 whose position is controlled.

  In addition, according to the present invention, since the core 41 is inserted into the metal pipe 5 to be processed, the depth of the concave portion 53 can be uniformly controlled by the core 41. As a result, it is possible to apply a generally uniform torsion pattern to the metal tube 5 and to apply the torsional stress at the time of torsion processing in a well-balanced manner, thereby improving workability. .

  Further, the shape of the recess 53 formed by the recess forming roll pair 4a is based on the shape of the contact surface of the rolls 2a-1 to 2a-4 with the flat surface 51, but the torsion actually formed The shape is controlled by the shape of the recess 53. Therefore, conversely, by optimizing the shape of the concave portion 53 in accordance with the target torsional shape, the final torsional shape itself can be controlled. Similarly, the depth and width of the recess 53 can be optimized according to the target twist shape.

  In the above-described embodiment, the case where the metal pipe 5 is a pipe having a substantially square cross section has been described as an example. Alternatively, the cross section may be substantially circular.

  FIG. 14A shows an example of actually twisting the metal tube 5 having a substantially circular cross section. The rolls 2a-1 to 2a-4 in the recess forming roll pair 4a are pressed against the metal tube 5 having a substantially circular cross section. As a result, the core 41 is inserted into the metal tube 5 into which the concave portion 53 as pre-strain is introduced. The subsequent process is the same as that of the above-described metal pipe 5 having a substantially square cross section. As a result, the metal tube 5 having a substantially circular cross section can be similarly twisted.

  Further, the metal pipe 5 is not limited to the case where the concave portion 53 is formed as a pre-strain at the end portion 5a, and may be provided at any location. Even when the concave portion 53 as the pre-strain is formed at the center in the tube axis direction C, the torsion line extends from the pre-strain concave portion 53 as a starting point.

  In the above-described embodiment, the case of twisting in the counterclockwise direction is described as an example. However, the present invention is not limited to this, and the case of twisting in the clockwise direction can be realized based on the same method. . In such a case, the right end of the plane portion 51 is pressed by the reference roll pair 4b, and the left end of the plane portion 51 is pressed by the processing roll pair 4c.

  Moreover, in this invention, it is not essential to use the twist processing apparatus 1 mentioned above. First, a plurality of concave portions 53 plastically deformed by pressing the metal tube 5 toward the inside of the tube by a known means is formed in the tube circumferential direction, and then the core 41 is inserted into the metal tube 5. Next, if the metal tube 5 through which the core 41 is inserted is simply twisted in the tube outer peripheral direction with the tube axis direction C as the center, the same effects as described above are produced. That is, in this invention, it is not limited to processing while conveying the metal tube 5 from the upstream side to the downstream side, and after fixing one end side of the metal tube 5, the other end side of the metal tube 5 is fixed. Even a simple twist can be realized.

  In any of the embodiments, in the present invention, the core 41 may be first inserted into the metal tube 5 and then a plurality of the recesses 53 may be formed in the pipe circumferential direction. Of course, this also provides the same effect as when the core 41 is inserted into the metal tube 5 after the recess 53 is first formed.

DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Roll 3 Forming machine bed 4 Roll pair 5 Metal tube 9 Turntable 10 Stand frame 11 Fixing plate 14 Hole part 16 Drive shaft 17 Base 18 Reduction gear 19 Drive motor 20 Reduction adjustment bolt 21 Roll shaft 41 Core 51 Plane Part 52 Corner part 53 Concave part

Claims (6)

By forming a plurality of concave portions plastically deformed by pressing the metal tube toward the inside of the tube,
Insert the core through the metal tube in which the recess is formed,
The metal pipe through which the core is inserted is twisted in the pipe outer peripheral direction around the pipe axis direction,
In the twisting process, the metal pipe having a substantially square cross section composed of a flat part and a corner part is conveyed in the order of a reference roll pair and a twisting roll pair,
With the reference roll pair, the right end or the left end of each plane portion is brought into contact with the plane from a substantially vertical direction,
According to a desired twist angle with respect to the pitch in the tube axis direction from the reference roll pair, the metal pipe is rotated by the twisting roll pair provided by rotating in the tube outer peripheral direction from the contact surface of the reference roll pair. A twisting method for a metal tube, wherein the twisting process is performed by pressing the right end or the left end of each of the flat portions in the above. Forming a plurality of recesses plastically deformed by pressing a metal tube inserted through the core in advance toward the inside of the tube;
The metal pipe is twisted in the pipe outer peripheral direction around the pipe axis direction ,
When transporting the metal tube in the order of the recess-forming roll pair, the reference roll pair, and the twisting roll pair,
A method of twisting a metal tube, characterized in that the recess is formed by pressing each flat portion of the metal tube toward the inside of the tube by the pair of recess forming rolls . The method for twisting a metal tube according to claim 1 or 2, wherein the metal tube is plastically deformed by pressing any one end portion in the tube axis direction. When transporting the metal tube in the order of the recess-forming roll pair, the reference roll pair, and the twisting roll pair,
Twisting processing method according to claim 1 Symbol placement of the metal tube, characterized in that to form the recess and pressed toward the respective flat portions of the metal tube in the tube side by the recess-forming roll pair. The metal tube twisting method according to any one of claims 1 to 4, wherein the metal tube having any one of a substantially square cross section, a substantially triangular cross section, and a substantially rhombic cross section is twisted. In the twisting process, first, the concave portion formed above is deformed inward,
Next, when the recess is brought into contact with the core, deformation of the recess further inward is suppressed, and the metal is formed along the direction corresponding to the torsion angle by the torsion processing with the recess as a starting point. Deform the tube inward,
Furthermore, the new concave portion formed by deforming inward is brought into contact with the core to suppress the inward deformation of the new concave portion, while inward along the direction corresponding to the torsion angle. The method of twisting a metal tube according to any one of claims 1 to 5, wherein the deformation is repeatedly performed.

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