JP6839786B2 - Square tube forming method and equipment - Google Patents

Description

The present invention relates to a square tube forming method and apparatus for forming a metal round tube into a square tube, and more particularly to a forming roll type square tube forming method and apparatus using a multi-stage forming roll stand. In addition, in this specification, a square tube means a metal square tube.

As a square tube forming device for forming a round tube having a circular cross section into a square tube having a rectangular cross section, there is a configuration using a forming roll stand row in which a plurality of forming roll stands are arranged in the forming direction, and the most common one is , There is a configuration using a four-sided forming roll stand that restrains the outer circumference of the same cross section of a round tube from four sides perpendicular and horizontal. On the other hand, there is also a square tube forming device that does not use this four-way forming roll stand, and one of them is a patented one that uses a forming roll stand row in which horizontal roll stands and vertical roll stands are alternately arranged along the forming direction. It is presented in Document 1 and Patent Document 2.

In these square tube forming devices, caliber rolls are used for both horizontal rolls and vertical rolls. The caliber roll is a molded roll whose outer peripheral surface is deeply arcuate from both end sides in the rotation axis direction toward the center, and the arcuate dent is a roll caliber.

All of the square tube forming devices are basically designed so that the roll caliber at each stand gradually becomes shallower from the upstream side to the downstream side in the material traveling direction, and more specifically, the curvature of the roll caliber becomes shallower. , Gradually decrease from a value close to the curvature of the round tube, which is a raw tube, and finally become 0, which is the same as the straight part sandwiched between the corners of the square tube, which is the product. It is designed.

In the square tube forming apparatus shown in Patent Document 1, horizontal roll stands and vertical roll stands are alternately arranged in close proximity to each other in order to suppress springback of the pipe material between adjacent rolls and improve formability. And they are trying to utilize the molding power of each other.

In the square tube forming apparatus shown in Patent Document 2, improvements have been made to the roll caliber of each forming roll. In the conventional four-sided molding roll stand, since four corners are to be molded at one time, excessive strain is generated in the corners, and the part that should be a flat straight part sandwiched between the two corners is wavy. Deformation is likely to occur, which was remarkable in the case of relatively thin-walled pipes. In the square tube molding apparatus shown in Patent Document 2, molding (straightening) of the shoulder portion (both ends of the straight portion sandwiched between the two corner portions) adjacent to the corner portion of the product square tube is performed as another portion. In order to precede the molding of the molding roll, the roll caliber of the molding roll is divided into a corner part, a shoulder part, and a straight part other than the shoulder part in the circumferential direction, and different curvatures are given to each part. As a result, a high-quality square tube having excellent moldability can be obtained.

In any square tube forming apparatus, the roll caliber is designed so that the bottom of the caliber of the forming roll makes limited contact with the central portion of the straight portion of the product, which is within a certain range. For example, it is possible to mold pipe materials of different sizes in the same stand row, but the range of combined use is limited, and the development of a square tube forming apparatus having a wider roll-combinable use is awaited.

Further, recently, it has been requested that the curvature of the cross section R of the corner portion is accurate as specified, that is, there is no thickening or thinning, including the structural steel pipe, which is presented in Patent Document 1. In order to suppress springback and improve formability, the square pipe forming device employs a small-diameter forming roll for the purpose of narrowing the space between adjacent horizontal rolls and vertical rolls, which makes it more intrusive. In reality, springback cannot be suppressed due to an increase in resistance, and it is difficult to meet the above demand. On the other hand, in the square tube forming apparatus presented in Patent Document 2, relatively high dimensional accuracy is ensured by the combination of multiple curvatures in the roll caliber described above, but on the other hand, the caliber roll is more exclusive. , It is inevitable that the roll compatibility will be sacrificed.

Further, in recent years, round steel pipe manufacturing factories have put into practical use a pipe making line that can be used for both rolls and can be formed within a range of several times the diameter ratio. By incorporating a square tube forming apparatus into this pipe forming line, it is required that round tubes and square tubes having various diameters can be freely manufactured in the same forming line according to demand. In this case, remolding from a round pipe to a square pipe with a large amount of deformation in the cross section has a large penetration resistance, and it is important to secure a stable thrust and suppress the total length of the stand row.

However, in the square tube forming apparatus of Patent Documents 1 and 2, when the space between the adjacent roll stands is narrowed, the amount of springback of the pipe material between the adjacent roll stands is large, and the pipe material passes through the stand row. The resistance becomes very high. Therefore, a four-way roll stand with a large thrust, which is a combination of a horizontal roll and a vertical roll, is required to propel the pipe material. In fact, in the square tube forming apparatus presented in Patent Document 2, four-way roll stands are arranged at the most upstream and the most downstream of the forming line, and even in the square tube forming apparatus presented in Patent Document 1, in reality. For example, it is necessary to arrange four-way roll stands in multiple stages for driving for pushing the raw pipe, and it is inevitable that the total length of the stand rows on the molding line will increase.

Japanese Unexamined Patent Publication No. 2000-301233 Japanese Unexamined Patent Publication No. 2006-150377

In view of these circumstances, the present invention makes it possible to combine a wide roll that can be incorporated into a modern pipe manufacturing line and suppress the total length of the roll stand row, and further, it is difficult for the product corners to be thickened or thinned, and the formability is high. It is an object of the present invention to provide an excellent square tube forming method and a square tube forming apparatus.

In order to achieve the above object, the present inventors have flat roll stands in which rod-shaped flat rolls having no roll caliber are combined, particularly horizontal flat roll stands and vertical flat roll stands are alternately arranged along the pipe material forming direction. We focused on the arranged flat roll stand rows. Unlike the caliber roll, the flat roll does not have an arcuate dent on the outer peripheral surface, so the minimum outer diameter and the maximum outer diameter are substantially equal, and the distance between the roll stands can be reduced compared to the case of the caliber roll stand. it can. As a result, the total length of the roll stand row is suppressed, and the roll compatibility is significantly improved as compared with the caliber roll stand row.

Then, as a result of repeating the analysis of the flat roll stand row from various viewpoints, the most important formability as a square tube forming apparatus was found as follows.

First, compared to the case of the caliber roll stand row, the horizontal roll stand and the vertical roll stand are arranged alternately, so that the bending molding is basically performed by the two-way roll, and the drawing molding is performed by the four-way roll. It is possible to prevent the occurrence of distortion at the corners. Moreover, since the forming roll in each roll stand is a flat roll in which the maximum diameter is suppressed, it is a fact that the space between the roll stands can be narrowed, but the space between the roll stands can be tentatively reduced. Even so, it is not possible to suppress the springback of the pipe material between the adjacent roll stands.

Secondly, it is the distribution ratio of the reduction amount in the roll stand row to each stand, that is, the reduction amount distribution, that greatly affects the moldability when forming a round tube into a square tube, rather than the caliber shape in the caliber roll. Is. In particular, the operation of applying an extremely large reduction amount with some molded roll stands in the roll stand row, and the reduction amount distribution with such a large change, the dimensions (outer diameter, wall thickness) and material of the round tube, and the corners. It is effective to change the size of the pipe greatly according to the size of the pipe.

Thirdly, the flat roll stand is very effective for performing such an operation. This is because, in the case of a caliber roll having a roll caliber, the outer diameters of both ends are larger than the caliber bottom portion that abuts on the pipe material, and the change in roll interval and reduction amount is restricted by the maximum diameter portion. On the other hand, in the case of a flat roll having substantially no roll caliber, the range of change in the roll interval is large and the reduction amount can be adjusted in a wide range, which is particularly effective for forming a square tube.

Fourth, when a large reduction amount is applied by the flat roll stand, the springback also becomes large, and the passage resistance of the pipe material increases accordingly, so that it becomes difficult for the pipe material to pass through the roll stand row, and Patent Document 2 Even if a four-way roll stand is added as described in, it cannot be supported. In order to solve this, it is necessary to rotationally drive the flat roll with as many roll stands as possible in the total length of the flat roll stand row to give a strong propulsive force to the pipe material passing through the flat roll stand row over the entire length. Specifically, the flat roll is rotationally driven in all stages of at least one of the adjacent horizontal roll stand and vertical roll stand.

The square tube forming method and apparatus of the present invention have been developed based on such findings, and the square tube forming method is based on a multi-stage roll stand arranged along the element tube forming direction. It is a square tube forming method in which a round tube of various diameters is passed through and formed into a square tube of various dimensions which is a product.
The first flat roll stand and the second flat roll stand whose reduction directions are orthogonal to each other are arranged alternately along the pipe material forming direction, and a flat roll stand row in which the reduction amount in each roll stand can be set independently is used.
The flat roll stand is based on the molding reduction amount distribution from the first stage stand to the final stage stand, which is selected in advance according to the outer diameter, wall thickness and material of the raw tube to be used, and the dimensions of the planned product square tube. Individually distribute a unique reduction amount to each roll stand in the row,
In addition, the two-way rolls in at least one of the first flat roll stand and the second flat roll stand, which are adjacent to each other, are rotationally driven to apply propulsive force to the raw tube to be molded, and the roll stands are used. By bending and molding with the two-way roll, the raw tube to be molded is formed into a product square tube having a planned size.

Further, the square tube forming apparatus of the present invention is a square tube forming apparatus for carrying out the square tube forming method of the present invention.
It is a square tube molding device that passes round tubes of various diameters, which are raw tubes to be molded, through a multi-stage roll stand arranged along the raw tube forming direction to form square tubes of various dimensions, which are products.
The first flat roll stand and the second flat roll stand whose reduction directions are orthogonal to each other are provided with a row of flat roll stands in which the first flat roll stand and the second flat roll stand are alternately arranged along the molding direction.
Each roll stand in the flat roll stand row has a roll interval adjusting means that can independently set the reduction amount, and each stage is in at least one of the adjacent first flat roll stand and the second flat roll stand. It has a roll driving means for rotationally driving the two-way roll.
In the description of the present invention described below, the roll stand row is a flat roll stand row, and the molding material is a raw tube to be molded.

In the square tube forming method and apparatus of the present invention, as long as the adjacent first flat roll stand and the second flat roll stand are orthogonal to each other in the reduction direction, the angle with respect to the vertical line and the horizontal line in the individual reduction directions does not matter. From a practical point of view, it is better to use one as a horizontal roll stand and the other as a vertical roll stand. Regarding the roll drive in each roll stand, both the adjacent first flat roll stand and the second flat roll stand, that is, all the rolls may be driven. By driving both the horizontal roll and the vertical roll, it is possible to form square tubes with different rectangular ratios. Further, although it is possible to drive both rolls only in some stands, it is rational and desirable to drive only one in all stands from the viewpoint of rationalization of the device structure and reduction of the device manufacturing cost.

The flat roll in each roll stand is basically one in which the outer diameter is constant in the total length in the rotation axis direction, but in some roll stands, particularly in one or a plurality of continuous roll stands in a part of the roll stand row. It is within the scope of the present invention to provide both rolls in each roll stand, whether driven or non-driven, with shallow arcuate recesses having a curvature larger than the outer surface R of the roll contact surface of the pipe material passing through the roll stand. By forming this arcuate recess on the outer peripheral surface of the drive roll in a section that requires a large propulsive force for the pipe material, for example, in the upstream portion of the roll stand row, a large propulsive force can be obtained, and the non-drive roll can be combined. By forming a similar arc-shaped recess on the outer peripheral surface, smooth propulsion and molding of the pipe material becomes possible.

As for the roll interval adjusting mechanism in the roll stand row, it is preferable to share the interval adjusting motor in the roll stand row. Specifically, a plurality of sets of first flat rolls are made so that one set of interval adjusting motors for one set of adjacent first flat roll stands and second flat roll stands can be moved along the roll stand row. It is better to share it between the stand and the second flat roll stand. As a result, the device structure is simplified, the weight of the device is reduced, and the manufacturing cost of the device is reduced.

Although the inventions described in Patent Documents 1 and 2 alternately arrange horizontal roll stands and vertical roll stands, the basic principle is to form a square tube by a row of caliber roll stands, that is, in each stand. This is a technology in which the curvature of the roll caliber is gradually reduced, and the circular tube, which is a raw tube, is gradually rolled into a square tube, which is a product.

In square tube molding using a row of caliber roll stands, the total molding amount is distributed almost evenly to all stages according to the number of stands used, and based on this, the caliber curvature at each stand is designed and the caliber curvature at each stand is designed. As for the reduction amount at each stand, the total reduction amount is evenly distributed to each stand in a form corresponding to the Caliber curvature distribution.

The square tube forming method and apparatus of the present invention uses a roll caliber using a plurality of stages of roll stand rows in which a first flat roll stand and a second flat roll stand whose reduction directions are orthogonal to each other are alternately arranged along the forming direction. Since the restrictions on the molding dimensions are removed, the roll-combined use is very high. In addition to reducing the overall length of the flat roll stand row by reducing the distance between adjacent flat roll stands, the sizing stand (4-way roll stand) for securing thrust, which was indispensable in the past, is no longer required, making it easier to modernize. Can be incorporated into the pipe manufacturing line. Therefore, it is possible to form a square tube of various dimensions from a round tube having various diameters, more specifically, various dimensions (outer diameter, wall thickness) and material.

That is, the flat roll has extremely high roll compatibility, the reduction amount of each stand in the stand row can be set independently, the reduction amount can be freely distributed, and the roll stand is suppressed by suppressing the total length of the roll stand row. Since it is possible to increase the number of stages of the roll stand, the amount of molding per roll stand is small even when the amount of reduction is large, and the amount of wrapping around the roll is reduced, so that the penetration resistance is reduced. Unlike, it is bent by a two-way roll, and at least one of the adjacent first flat roll stand and second flat roll stand is driven, and stable propulsion is performed on the pipe material passing through the stand row. By being able to apply force, high pipe making efficiency can be stably secured even if there is no sizing stand (4-way roll stand) for securing thrust, and despite the suppression of the total length of the flat roll stand row, and the product. Excellent moldability is ensured because it is difficult for the corners to be thickened or thinned.

Therefore, the square tube forming method and apparatus of the present invention can economically produce a high quality square tube.

It is a perspective view of the square tube molding apparatus which shows one Embodiment of this invention. It is a perspective view from another angle of the same angle tube forming apparatus, and the roll drive mechanism is omitted. It is a perspective view of the horizontal roll stand in the same square tube forming apparatus. It is a perspective view of the vertical roll stand in the same square tube forming apparatus. It is a perspective view which shows one Example of the square tube forming method of this invention, and shows the square tube forming process in the same Example continuously, as a whole. In the same embodiment, it is explanatory drawing which shows the square tube forming process from the material round tube to the product square tube step by step by the cross-sectional shape of the tube in each stand. A perspective view showing another embodiment of the square tube forming method of the present invention shows the square tube forming process in the same embodiment continuously and as a whole. In the same embodiment, it is explanatory drawing which shows the square tube forming process from the material round tube to the product square tube step by step by the cross-sectional shape of the tube in each stand.

An embodiment of the present invention will be described below.

The square tube forming apparatus of the present embodiment is an apparatus in which a round tube as a molding material is passed through a plurality of forming roll stands in order to continuously form a square tube, and is arranged in a round tube manufacturing line. By molding a part of the manufactured round tube into a square tube, both the round tube and the square tube can be manufactured.

As shown in FIGS. 1 and 2, this square tube forming apparatus includes a square tubular roll stand row 10 that is long in the tube material forming direction. The square tubular roll stand row 10 comprises a square frame-shaped horizontal roll stand 20A having a thin thickness in the pipe material forming direction and a square frame-shaped vertical roll stand 20B having a thin thickness in the pipe material forming direction on the stand base 30. The structure is such that they are arranged alternately along the pipe material forming direction. The round tube, which is a molding material, passes through the roll stand row 10 from the front side to the back side in FIG. That is, the front side of FIG. 1 is the upstream side of the roll stand row 10, and the front side is the downstream side of the roll stand row 10.

As shown in FIG. 3, the horizontal roll stand 20A is formed between the upper and lower fixed horizontal bases 22A and 22A and the upper and lower fixed horizontal bases 22A and 22A connected by a total of four vertical rods 21A, two on each side. It is provided with vertical horizontal movable bases 23A and 23A supported by left and right vertical rods 21A so as to be movable in the vertical direction, and upper and lower horizontal rolls 24A and 24A attached to opposite surfaces of the movable bases 23A and 23A, respectively. ing.

Each of the upper and lower horizontal rolls 24A is a flat roll having a substantially constant outer diameter over the entire length in the central axis direction, and the horizontal support shafts supporting the horizontal roll 24A are brackets with built-in bearings on both sides of the horizontal roll 24A. It is rotatably supported by 25A and 25A, and one end of the support shaft protrudes to one side of the roll stand row 10 as an input shaft 24A', and roll drive as a roll driving means arranged on the other side. By being connected to the mechanism 40, it is rotationally driven (see FIG. 1).

The upper and lower sets of horizontal rolls 24A and 24A are a mechanical upper jack 26A attached downward to the upper surface of the central portion of the upper fixed horizontal base 22A and upward to the lower surface of the central portion of the lower fixed horizontal base 22A. The roll spacing is adjusted by the attached mechanical lower jack 26A.

That is, the downward upper jack 26A has a tip portion that penetrates the upper fixed horizontal base 22A and is coupled to the upper surface of the upper movable base 23A, and is arranged on one side of the roll stand row 10 for horizontal rolls. It is driven by the spacing adjustment motor 50A (see FIGS. 1 and 2) via the horizontal input shaft 27A. The upper end of the upward lower jack 26A penetrates the lower fixed horizontal base 22A and is coupled to the lower surface of the lower movable base 23A, and the horizontal roll interval adjusting motor 50A (see FIGS. 1 and 2). ) Was attached to the gearbox 28A attached to the upper surface of the other side of the upper fixed horizontal base 22A, the vertical power transmission shaft 29A, and the lower surface of the other side of the lower fixed horizontal base 22A. By being transmitted to the lower jack 26A via the gear box 28A, it is driven synchronously with the upper jack 26A.

By such symmetrical synchronous drive of the upper and lower jacks 26A and 26A, the upper and lower movable bases 23A and 23A are symmetrically driven up and down, and the roll interval of the upper and lower horizontal rolls 24A and 24A is adjusted. That is, the distance between the upper and lower horizontal rolls 24A and 24A is adjusted by the upper and lower jacks 26A and 26A, the horizontal roll spacing adjustment motor 50A, the input shaft 27A as the power transmission mechanism, the upper and lower gearboxes 28A and 28A, and the power transmission shaft 29A. The mechanism is configured.

As shown in FIG. 4, the vertical roll stand 20B includes a pair of left and right fixed vertical bases 21B and 21B, two upper and lower horizontal rods 22B and 22B connecting the left and right fixed vertical bases 21B and 21B, and left and right fixed vertical bases. The left and right movable bases 23B and 23B, which are movably supported in the horizontal direction by the two upper and lower horizontal rods 22B and 22B between the bases 21B and 21B, and the left and right movable bases 23B and 23B, respectively, are rotatably supported. It is equipped with left and right vertical rolls 24B and 24B.

The left and right fixed vertical bases 21B and 21B are symmetrically erected on both ends of the horizontal fixed base 22A (see FIG. 3) below the horizontal roll stand 20A described above. That is, the horizontal fixed base 22A on the lower side of the horizontal roll stand 20A described above extends to the downstream side of the roll stand row 10, and the vertical fixed bases 21B and 21B are mounted on the extending portion. As a result, the adjacent pair of horizontal roll stands 20A and vertical roll stands 20B form a horizontal / vertical stand pair 20 integrated by a common horizontal fixed base 22A.

Each of the left and right movable bases 23B has an upper and lower slider slidably supported by the upper and lower horizontal rods 22B and 22B, and a roll support frame 25B attached between the upper and lower sides. The roll support frame 25B, which also serves as a connecting member for the upper and lower sliders, has a structure in which the upper and lower horizontal members and the outer vertical member are combined and opened inward, and the left and right vertical rolls 24B and 24B are provided between the upper and lower horizontal members. Is rotatably supported. The roll intervals of the left and right vertical rolls 24B and 24B are adjusted by the left and right jacks 26B and 26B attached to the outer side surfaces of the left and right vertical fixed bases 22B and 22B so as to face the inside.

That is, the tip of the jack 26B on one side penetrates the fixed vertical base 22B on one side and is connected to the outer surface of the outer vertical member of the movable base 23B on the one side, and the roll stand row 10 It is driven via the vertical input shaft 27B by a vertical roll spacing adjustment motor 50B (see FIGS. 1 and 2) arranged on one side. Further, the jack 26B on the other side has a tip portion that penetrates the fixed vertical base 22B on the other side and is coupled to the outer surface of the outer vertical member of the movable base 24B on the other side, and is used for the vertical roll. The driving force of the spacing adjustment motor 50B (see FIGS. 1 and 2) is a gearbox 28B mounted on one side of the stand base 30, a horizontal power transmission shaft 29B, and the other side of the stand base 30. By being transmitted to the jack 26B on the other side via the gear box 28B mounted on the top, the jack 26B on the other side is driven symmetrically and synchronously.

By symmetrically and synchronously driving the left and right jacks 26B and 26B, the left and right movable bases 23B and 23B move symmetrically horizontally, and the distance between the left and right vertical rolls 24B and 24B is adjusted. That is, the left and right jacks 26B and 26B, the vertical roll spacing adjustment motor 50B, the input shaft 27B as the power transmission mechanism, the left and right gearboxes 28B and 28B, and the power transmission shaft 29B are spaced apart from the left and right vertical rolls 24B and 24B. It constitutes an adjustment mechanism.

Then, one set of the horizontal roll stand 20A and the vertical roll stand 20B having such a structure is regarded as a horizontal / vertical stand pair 20, and a plurality of sets thereof are arranged on the stand base 30 along the pipe material forming direction to form the angle. The roll stand rows 10 in the tube forming apparatus are configured. More specifically, the roll stand row 10 is composed of 11 sets of stands vs. 20 (a total of 23 roll stands including the horizontal roll stand 20A in the final stage).

In the square tube forming apparatus, as described above, the intervals between the horizontal rolls 24A and 24A in the horizontal roll stand 20A are adjusted by the horizontal roll interval adjusting motor 50A, and the intervals between the vertical rolls 24B and 24B in the vertical roll stand 20B are vertical. It is adjusted by the roll interval adjustment motor 50B. Only one set of the horizontal roll spacing adjustment motor 50A and the vertical roll spacing adjusting motor 50B is provided here corresponding to one horizontal / vertical stand pair 20, and the one set of horizontal roll spacing adjusting motor 50A and the vertical roll spacing adjusting motor 50B By moving the vertical roll spacing adjustment motor 50B along the roll stand row 10 (here, self-propelled), the spacing between the horizontal rolls 24A and 24A and the spacing between the vertical rolls 24B and 24B in 12 sets of horizontal and vertical stands vs. 20 Is adjusted sequentially.

That is, as shown in FIGS. 1 and 2, particularly FIG. 2, a support 51 is provided over the entire length of the roll stand row 10 on one side of the roll stand row 10, particularly on the uppermost portion thereof. The support base 51 is horizontally supported by a stay 52 or the like extending from the uppermost portion of the stand assembly 20 to one side. A set of the horizontal roll spacing adjustment motor 50A and the vertical roll spacing adjusting motor 50B are connected to each other, and in that state, can move on the support base 51 along the roll stand row 10. Then, one set of the horizontal roll interval adjusting motor 50A and the vertical roll interval adjusting motor 50B stop at positions corresponding to each of the 12 sets of horizontal and vertical stands vs. 20, and at each stop position, the horizontal roll stand 20A is inside. By being connected to the horizontal input shaft 27A and the vertical input shaft 27A in the vertical roll stand 20B, respectively, the intervals between the horizontal rolls 24A and 24A in the horizontal roll stand 20A and the vertical roll 24B in the vertical roll stand 20B are provided. , 24B are adjusted respectively.

Then, by performing this operation for each of all the horizontal and vertical stands to 20, the intervals of the horizontal rolls 24A and 24A and the intervals of the vertical rolls 24B and 24B are unique in each of all the horizontal and vertical stands to 20. It will be adjusted. Reference numeral 53 denotes a flexible cable for supplying power to the mobile horizontal roll interval adjusting motor 50A and the vertical roll interval adjusting motor 50B.

In the square tube forming apparatus, as described above, the horizontal rolls 24A and 24A in the horizontal roll stand 20A are rotationally driven by the roll drive mechanism 40 arranged on one side of the roll stand row 10. The roll drive mechanism 40 here is divided into three drive units 41. Each drive unit 41 rotates the upper and lower horizontal rolls 24A and 24A in the four horizontal roll stands 20A by being connected to the four horizontal roll stands 20A in the four adjacent stands vs. 20 in the roll stand row 10. Drive.

That is, the roll drive mechanism 40 has a drive motor 42 for driving each drive unit 41, and has four horizontal roll stands 43 and 43 corresponding to the four horizontal roll stands 20A. By connecting the upper and lower horizontal rolls 24A and 24A in 20A with the input shafts 24A'and 24A', the four horizontal roll stands 20A are combined to rotate the upper and lower horizontal rolls 24A and 24A in each horizontal roll stand 20A. Drive.

In the square tube forming apparatus of the present embodiment, a part of the roll stands in the roll stand row 10, here a part on the upstream side, more specifically, two sets of horizontal and vertical stands vs. 20 from the most upstream. That is, in each of the two horizontal roll stands 20A and the vertical roll stands 20B, the horizontal rolls 24A and 24A in each horizontal roll stand 20A and the vertical rolls 24B and 24B in each vertical roll stand 20B pass between the rolls. An extremely shallow arcuate recess having a curvature larger than the outer surface R of the pipe material to be formed is formed.

Next, a method of forming a round tube into a square tube using the square tube forming apparatus of the present embodiment will be described as a square tube forming method of the present embodiment.

Multiple sets (12 sets in this case) of horizontal and vertical stands vs. 20 (12 sets in this case) in the roll stand row 10 according to the dimensions (outer diameter, wall thickness) and material of the round tube that is the molding material, and the dimensions of the square tube that is the product. That is, in the combination of the horizontal roll stand 20A and the vertical roll stand 20B), the distance between the upper and lower horizontal rolls 24A and 24A in the horizontal roll stand 20A and the distance between the left and right vertical rolls 24B and 24B in the vertical roll stand 20B are set, for example, the roll stand. Adjust every 20 stands from the upstream side to the downstream side of the row 10. As described above, this adjustment is performed by the combination of the movable horizontal roll interval adjusting motor 50A and the vertical roll interval adjusting motor 50B.

After adjusting the intervals between the horizontal rolls 24A and 24A in the horizontal roll stands 20A and adjusting the intervals between the vertical rolls 24B and 24B in the vertical roll stands 20B in all the stands to 20, the roll drive mechanism 40 causes all the stands to 20 to adjust the intervals. Only the horizontal rolls 24A and 24A in the horizontal roll stand 20A are rotationally driven.

In this state, a round tube, which is a molding material, is passed through the roll stand row 10. The tube material is formed from a round tube to a square tube by sequentially passing through a pair of stands 20 (that is, a combination of a horizontal roll stand 20A and a vertical roll stand 20B) in the roll stand row 10.

Here, the roll stand row 10 has a configuration in which the horizontal roll stands 20A and the vertical roll stands 20B are alternately arranged, and the horizontal rolls 24A and 24A in the horizontal roll stand 20A and the vertical rolls 24B in the vertical roll stand 20B, Both 24B are flat rolls having a substantially constant outer diameter over the entire length in the central axis direction. For these reasons, not only the distance between adjacent stands is reduced, but also it is easy to avoid roll interference between adjacent stands, so that the roll spacing is independent in each stand and in a wide range. It is adjustable. Further, even if the distance between adjacent stands is narrowed, a flat roll having a relatively large diameter can be used, so that the wrapping of the pipe material around the roll and the increase in intrusion resistance due to this can be avoided.

Therefore, depending on the outer diameter, material, wall thickness, etc. of the molding material, the reduction amount at a specific position of the roll stand row 10, for example, a part of the stands on the upstream side is increased, and the reduction amount is gradually decreased for the others. It is possible to set a formability-oriented reduction amount distribution in consideration of the changing springback amount.

In addition, in the roll stand row 10, the pipe material intrusion resistance is essentially suppressed to be small, and in all the horizontal roll stands 20A, the horizontal rolls 24A and 24A are rotationally driven to pass through the roll stand row 10. Since the propulsive force is applied to the entire length, the amount of reduction at a specific position of the roll stand row 10 is increased, and as a result, the springback is increased so that the pipe material smoothly passes through the roll stand row 10.

In particular, in the square tube forming apparatus of the present embodiment, each horizontal roll stand is used in a part of the stands on the upstream side (here, two sets of horizontal and vertical stands are paired with 20, but more than that) in which the amount of reduction is increased. Ultra-shallow arcuate recesses having a curvature larger than the roll contact surface surface R of the pipe material passing between the rolls are formed on the outer peripheral surfaces of the horizontal rolls 24A and 24A in 20A and the vertical rolls 24B and 24B in each vertical roll stand 20B. Therefore, a particularly large propulsive force is added to the pipe material passing through each stand.

Further, the arc-shaped recesses are provided on the horizontal rolls 24A and 24A in the horizontal roll stand 20A and the vertical rolls 24B and 24B in the vertical roll stand 20B on the upstream side of the roll stand row 10, so that the pipe material is provided in the roll stand row. The pulling force into the 10 is strengthened, and the pipe material can pass smoothly.

Then, in addition to the smooth passage of the pipe material, the pipe material passing through the roll stand row 10 is bent and molded from two directions by the flat horizontal rolls 24A and 24A and the flat vertical rolls 24B and 24B to form corners. Therefore, the moldability is improved and a high-quality square tube is manufactured. Specifically, a square tube having a predetermined cross-sectional curvature without thinning at the corners is manufactured. The fact that wall thinning does not occur at the corners means that it is not necessary to assume that wall thinning will occur in the size of the molded raw tube, and the effect of reducing the diameter of the mother tube or the wall thickness of the round tube and square tube that can be manufactured can be made the same. It works.

In addition to this, in the square tube forming apparatus of the present embodiment, the horizontal roll stands 20A and the vertical roll stands 20B are alternately arranged to suppress roll interference between adjacent stands, and the horizontal roll stands 20A. Since only the horizontal rolls 24A and 24A in the above are rotationally driven and the vertical rolls 24B and 24B in the vertical roll stand 20B are free rollers, member interference between adjacent stands is further suppressed. As a result, the total length of the roll stand row 10 is suppressed to be short, and it is easy to secure the equipment arrangement space in the pipe manufacturing factory. In addition, the weight of the device is reduced, and the manufacturing cost can be reduced.

In addition, the roll spacing adjustment in the horizontal roll stand 20A and the roll spacing adjustment in the vertical roll stand 20B can be performed horizontally and vertically by a combination of a mobile set of horizontal roll spacing adjusting motors 50A and vertical roll spacing adjusting motors 50B. Perform every 20 stands vs. 20. That is, the horizontal roll interval adjusting motor 50A and the vertical roll interval adjusting motor 50B are also used between the plurality of horizontal and vertical stands vs. 20. Therefore, the structure of the square tube forming apparatus is simplified, and as a result, the weight of the apparatus is reduced and the apparatus manufacturing cost is further reduced.

Finally, as an example of the present invention, the analysis model results of the two square tube molding examples will be specifically described with reference to FIGS. 5 to 8. The analysis software used to obtain the analysis results is a three-dimensional elasto-plastic deformation finite analysis software having sufficient accuracy to reproduce the actual molding developed by the present inventors. The drawings are schematic based on the results output from the software.

In the square tube forming examples 1 and 2, the same flat roll stand row is used, and in the square tube forming row 1, the square tube forming process in the flat roll stand row is shown continuously and as a whole in FIG. FIG. 6 shows the change in the cross-sectional shape of the pipe from the round pipe, which is the molding material, to the square pipe of the product, step by step for each stand. Similarly, in the square tube forming row 2, the square tube forming process in the flat roll stand row is shown continuously and as a whole in FIG. 7, the cross-sectional shape of the tube from the round tube which is the molding material to the square tube of the product. FIG. 8 shows the change of the above stepwise for each stand. Since the outer diameters of the rolls are displayed in the same ratio in FIGS. 5 and 7, it is easy to compare the size of the outer diameter of the raw pipe.

The flat roll stand rows used in the square tube forming examples 1 and 2 have a configuration similar to that of the square tube forming apparatus shown in FIGS. 1 to 4, and the vertical roll stand and the horizontal roll stand are paired with the vertical roll and the horizontal roll. A total of 12 sets of 24 rolls arranged alternately in a roll stand row. The roll diameter of each roll stand is 150 mm, and the total length of the roll stand row is 4660 mm. The reduction amount can be set individually for each of the 24 roll stands, but the 12 sets of roll stands with one pair of vertical and horizontal are divided into three groups with four sets as one group. A unique reduction amount was set for each group.

In the first group located at the most upstream portion, in order to secure propulsive force, each roll is provided with a shallow arcuate recess having a curvature larger than the outer surface R of the roll contact surface of the pipe material passing through each roll stand. There is.

Then, in the square tube forming example 1 shown in FIGS. 5 and 6, a relatively small-diameter material round tube made of ordinary steel (Ys = 360 MPa) having an outer diameter of 44.45 mm and a thickness of 3.6 mm is formed on one side. Shows the case of molding into a product square tube having a square cross section of 38 mm and a thickness of 3.6 mm. The reduction amount distribution adopted for this ordinary steel raw pipe was set to a ratio of 9: 3: 1 in the order of the first group, the second group, and the third group.

That is, the reduction amount required for the total molding of the cross-sectional shape from the material round tube to the product square tube is 13, and the first group performs molding with a reduction amount of 9/13 (about 69.3%), and the second group. In the case, molding was performed with a reduction amount of 3/13 (about 23%), and in the third group, molding was performed with a reduction amount of 1/13 (about 7.7%). To perform molding from a round tube to a square cross section, the same reduction amount is set for one pair of vertical rolls and horizontal rolls, and as a result of flattening of the sides, four squared moldings of a square cross section are performed.

As a result, the last stand RB8 of the first group finished molding about 69% of the total molding amount, the last stand RB16 of the second group finished molding about 92%, and the last stand of the third group. RB24 will finish 100% molding both vertically and horizontally.

Further, in the square tube forming example 2 shown in FIGS. 7 and 8, a relatively large diameter material round tube having an outer diameter of 119.67 mm and a thickness of 7 mm made of the same ordinary steel (Ys = 360 MPa) is 50 mm in length. , The case of molding into a flat rectangular product square tube with a width of 150 mm and a thickness of 7 mm has been shown, and the reduction amount distribution is again in the order of the first group, the second group, and the third group at 9: 3: The ratio is 1. In order to form a round tube into a rectangular cross section, the corner positions can be set by selecting the reduction amount so that the vertical side is large and the horizontal side is small for one pair of vertical rolls and horizontal rolls. As a result of the flattening of the sides, four squared moldings with a rectangular cross section are performed.

As a result, the last stand RB8 of the first group finished molding about 69% of the total molding amount, the last stand RB16 of the second group finished molding about 92%, and the last stand of the third group. RB24 will finish 100% molding both vertically and horizontally.

The reason for distributing the reduction amount in this way is clearly shown in FIG. 8, but the first group on the upstream side promotes flattening of the sides at once to perform square forming, and the second in the middle stream part. This is because the group will continue to perform cornering molding to promote gentle flattening of the sides, and the third group on the downstream side will adopt a molding process to obtain the planned dimensions. In the case of two square tube moldings, the reduction amount distribution is adopted in consideration of the planned product dimensions. It is a feature of the present invention that a molding process according to such product specifications can be flexibly adopted. In addition, the roll combined range in the analysis model is up to 3 times or less in outer diameter ratio and 3 times or less in aspect ratio, and it was confirmed from this analysis result that the result of manufacturing the actual machine and actually operating it is also the same.

The grouping of roll stands in the flat roll stand row is divided into 3 groups with 1 pair x 4 pairs (8 units) as 1 group, but 4 groups with 1 pair x 3 pairs (6 units) as 1 group, 1 6 groups with 2 pairs x 2 pairs (4 units) as 1 group may be used, and 12 groups with 1 pair x 1 pair (2 units) as 1 group may be used. In addition, a wide range of square tube molding can be performed by selecting various grouping methods along with the reduction amount distribution depending on the difference in the product square tube size).

10 Roll stand row 20 Horizontal vertical stand vs. 20A Horizontal roll stand (first flat roll stand)
21A Vertical rod 22A Fixed horizontal base 23A Movable base 24A Horizontal roll 25A Bracket 26A Jack 27A Input shaft 28A Gearbox 29A Power transmission shaft 20B Vertical roll stand (second flat roll stand)
21B Fixed vertical base 22B Horizontal rod 23B Movable base 24B Vertical roll 25B Roll support frame 26B Jack 27B Input shaft 28B Gearbox 29B Power transmission shaft 30 Stand base 40 Roll drive mechanism (roll drive means)
41 Drive unit 42 Drive motor 50A Horizontal roll spacing adjustment motor 50B Vertical roll spacing adjustment motor 51 Support stand 52 Stay 53 Cable

Claims (3)

A square tube molding method in which round tubes of various diameters, which are raw tubes to be molded, are passed through a multi-stage roll stand arranged along the raw tube forming direction to form square tubes of various dimensions, which are products.
The first flat roll stand and the second flat roll stand whose reduction directions are orthogonal to each other are arranged alternately along the pipe material forming direction, and a flat roll stand row in which the reduction amount in each roll stand can be set independently is used.
According to the molding reduction amount distribution from the first stage stand to the final stage stand, which is selected in advance according to the outer diameter, wall thickness and material of the raw tube to be used, and the size of the planned product square tube, the flat roll stand row A unique reduction amount is individually distributed to each roll stand,
In addition, the two-way rolls in at least one of the first flat roll stand and the second flat roll stand, which are adjacent to each other, are rotationally driven to apply propulsive force to the raw tube to be molded, and the roll stands are used. A square tube forming method for forming the raw tube to be formed into a product square tube having a predetermined size by bending molding with the two-way roll. In the square tube forming method according to claim 1, in one or more roll stands in a part of the flat roll stand row, an arcuate recess having a curvature larger than the roll contact surface R of the pipe material passing through the roll stand is formed into a flat roll. A square tube forming method for forming and applying a propulsive force to the pipe material. In the square tube forming method according to claim 1, a set of interval adjusting motors for an adjacent set of a first flat roll stand and a second flat roll stand can be moved along a row of flat roll stands. A method for forming a square tube, which is arranged in a row and shared between a plurality of sets of the first flat roll stand and the second flat roll stand in a row of flat roll stands.

Images