JPS63127B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Field of Application> The present invention is directed to a spiral tube that can apply any residual moment in the positive and negative regions when manufacturing a tube while winding a strip in a spiral shape. Regarding pipe manufacturing equipment.

<Prior art> A conventionally known spiral pipe manufacturing device is shown in Fig. 1a, which schematically shows its structure.
As shown in b and c, first and second bending rolls 3 and 4 are adjacent to each other along the tube circumferential direction,
A bending device is provided between these bending rolls 3 and 4, which has a third bending roll 5 that sandwiches the strip 1 and faces the bending rolls 3 and 4. The helical joint of the spirally wound strip 1 is welded by a welding device (not shown).

In general, the diameter of a spiral pipe is kept constant without any step at the helical joint of the strip, but if the thickness or material of the strip is uneven, a step may occur at the helical joint. Therefore, the pipe diameter tends to increase or decrease easily. In particular, in the case shown in Fig. 1c, even if there is a slight change in the strip thickness or material, the pipe diameter will be distorted accordingly, and not only will the dimensional stability be extremely poor, but it may also become impossible to make pipes. Situations like this also occur.

Therefore, in the case shown in Fig. 1a (for example, see pages 25 to 32 of "Nippon Kokan Giho" No. 73), the strip 1 bent to a larger pipe diameter is always bent to a predetermined pipe diameter using the outer surface presser roll 6. It is compressed to prevent the pipe diameter from fluctuating.
In the method shown in (for example, see pages 25 to 32 of "Nippon Kokan Giho" No. 73), the strip 1, which is always bent to a smaller pipe diameter, is pressed and expanded to the specified pipe diameter with the inner pressing roll 6'. This is to prevent fluctuations in the pipe diameter.

A cut 1 is made along the longitudinal direction of the spiral tube 2 as shown in FIG. 2a obtained in this way.
7 and cut the spiral tube 2, the first
The spiral tube 2 obtained by the pipe-making apparatus shown in FIG. 2A changes to the state shown in FIG. 2B due to spring back.

Here, when the ring opening degree is defined as γ≡α/Dp, γ is expressed as γ=ρ _p /ρ _p sinρ _p /ρ _p π=sinωπ/ω. However, ρ _p represents the radius of curvature of the spiral tube 2, ρ _p represents the radius of curvature after cutting, and ω≡
ρ _p /ρ _p , α=2ρ _p sinθ/2, 2πρ _p = (2π−θ)ρ
It is _p .

On the other hand, as shown in FIG. 3, which shows the relationship between the bending moment and the curvature when the spiral tube 2 is cut (ring opening), for example, A with the maximum curvature 1/ρ _i
The strip 1 bent to a point is welded at the edge with a product curvature 1/ρ _p at point B in the middle of springback to become a spiral tube 2, and the residual moment Mp
remains. When the ring is opened by making a cut 17 along the longitudinal direction of the spiral tube 2, the residual moment Mp is released and the curvature after the ring is opened is C.
It becomes 1/ρ _p of the point. The same is true when bending to A' with the maximum curvature further increased and giving a negative residual moment Mp', but in this case, in order to make the product curvature from C' to B', It is necessary to apply a reverse bend from the inside after bending using the apparatus shown in Figure b. In this case, when the ring is opened, the radius of curvature becomes smaller than the radius of curvature of the product, as shown in FIG. 3, and α shown in FIG. 2b is negative, that is, γ is negative.

From experiments and theoretical considerations, once the Young's modulus, yield point, and plate thickness of the strip 1, the radius of curvature ρ _p of the spiral tube 2, and the maximum bending curvature 1/ρ _i are determined, the ring opening degree γ can be derived. . Incidentally, in the region of ω≦1 where there is a positive residual moment, γ≧0, ρ _p ≧ρ _p ≧
ρ _i and in the region of ω≧1 where the residual is negative, γ≦0 and ρ _p ≧ρ _p ≧ρ _i .

<Problems to be Solved by the Invention> When the above-mentioned spiral tube is used as a pipeline for fluids such as gas, water, oil, etc., when the pressure of these fluids is high, the inner circumferential surface of the tube tends to expand. Because of this force, there is a risk that the strength of the spiral tube 2 made with the apparatus shown in FIG. 1a and originally having a positive residual moment may be reduced. For this purpose, a spiral tube 2 with a negative residual moment made with the device shown in FIG. 1b is used,
The fluid pressure and negative residual moment are balanced.

Therefore, the spiral tube 2 having a negative residual moment cannot be manufactured using the apparatus shown in FIG.
In order to meet such requirements, a spiral tube with a residual moment as close to zero as possible is used as a substitute, but it is still essentially impossible to meet this requirement. Furthermore, as the residual moment approaches zero, the contact between the outer pressing roll 6 and the strip 1 becomes unstable, and it becomes difficult to maintain the pipe diameter constant.

In addition, when using spiral pipes as steel pipe piles,
In the spiral pipe 2 with a negative residual moment made with the device shown in Fig. 1b, the roundness decreases due to heat shrinkage due to welding of the sheet piles, and the spacing between the sheet piles narrows, causing construction troubles. There is a possibility that it will be invited. For this reason, a spiral tube 2 having an appropriate positive residual moment made with the apparatus shown in FIG. 1a is used to balance the shrinkage stress during welding with the positive residual moment.

Therefore, the apparatus shown in FIG. 1b cannot produce a spiral tube 2 having a positive residual moment.
In order to meet this requirement, a spiral tube with a residual moment as close to 0 as possible is used instead, but it remains essentially impossible to meet this requirement. Moreover, as the residual moment approaches zero, the contact between the inner pressing roll 6' and the strip 1 becomes unstable, and it becomes difficult to maintain the pipe diameter constant.

In this way, conventional pipe manufacturing equipment can only make spiral pipes that have residual moments in either the positive or negative range, so users can create spiral pipes that require the opposite characteristics, such as pipelines and steel pipe piles. In order to manufacture different parts so as to satisfy the requirements, it is necessary to prepare two pieces of equipment as shown in FIG.

Moreover, it is fundamentally difficult to manufacture a spiral tube with a stable diameter and high precision in which the residual moment is close to zero.

Based on this knowledge, the present invention allows the residual moment to be set arbitrarily, whether positive or negative, with a single pipe manufacturing equipment by simply modifying the conventional equipment, and also eliminates the need for residual moment along the longitudinal direction of the pipe. It is an object of the present invention to provide a pipe manufacturing device which can gradually change the pipe diameter from positive to negative depending on the situation and can maintain the pipe diameter with high accuracy even when the residual moment is set to be near zero.

<Means for Solving the Problems> The configuration of the first spiral pipe manufacturing device of the present invention includes first and second bending rolls adjacent to each other along the circumferential direction of the pipe, and a third bending roll facing the bending roll with the strip sandwiched between the rolls; and a spiral joining of the strip that is fed into a bending device having at least three of these bending rolls and wound into a spiral shape. A device for manufacturing a spiral pipe, comprising a welding device for welding the parts, and a presser roll provided on the inside or outside of the spirally wound strip and abutting on the inner peripheral surface or the outer peripheral surface of the strip. A bending moment imparting roll is provided adjacent to the bending device on the downstream side of the bending device in the sheet passing direction of the strip, and is positioned on the opposite side of the presser roll with the strip between the strips, The present invention is characterized in that the bending moment imparting roll is movable in the radial direction of the spiral tube in order to press the strip so that the strip has a preset diameter.

Further, the configuration of the spiral pipe manufacturing device according to the second aspect of the present invention includes first and second bending rolls adjacent to each other along the circumferential direction of the pipe, and a strip sandwiched between the bending rolls. a third bending roll facing the bending roll; and a welding device for welding the helical joint of the strip that is fed into a bending device having at least three bending rolls and wound into a spiral shape. In a spiral tube manufacturing device equipped with
A pair of bending moment imparting rolls are provided adjacent to the bending device on the downstream side of the bending device in the strip passing direction and located inside and outside of the spiral tube, and the spiral tube is set in advance. The spiral tube is characterized in that the pair of bending moment imparting rolls are respectively movable in the radial direction of the spiral tube in order to press the strip so that the strip has the same diameter.

<Function> The strip is bent by a bending device to a radius of curvature that is equal to or smaller than the radius of the intended product tube. Here, the sign and magnitude of the residual moment are determined by how much smaller or larger the radius of curvature of the strip bent by the bending device after spring back is than the radius of the product tube.

Thereafter, the position of the strip is regulated by a pair of bending moment imparting rolls that are opposed to each other and are movable in the radial direction, or by a presser roll and a bending moment imparting roll that are opposed to each other while sandwiching the strip. The helical joints are successively welded by the welding device while being held or corrected.

<Example> As shown in FIG. 4, which shows the schematic structure of an example of applying the present invention to a pipe manufacturing apparatus equipped with an external pressure roll, and FIG. 5, which shows the side structure of a part of the same, two The strip 1 is bent into a spiral tube 2 by a bending device (three roll bender) comprising outer bending rolls 3, 4 and one inner bending roll 5. When forming this strip 1 into a spiral shape, a roller-type forming case 9 is used, which is movably supported by a screw 8 and equipped with a large number of external pressing rolls 6 that move according to the diameter of the product tube, and a bending moment. (Residual moment) is performed using the imparting roll 7. This bending moment imparting roll 7 is installed so as to be located on the inner surface side of the spiral tube 2 after the outer surface bending roll 4 on the exit side of the bending device. The roll 7 is attached to the same stand 10 as the internal bending roll 5, and is moved in the radial direction of the spiral tube 2 by a combination of a wedge-shaped roll support 11 having a serrated smooth surface and a wedge-shaped slider 12. It is set up so that it can be moved. That is, the roll support 11, which is housed in a guide 18 that is integrated with the stand 10 so as to be movable only in the radial direction (vertical direction in FIG. It is pushed out due to the wedge action between it and the mover 12, which is moved in the longitudinal direction (in the left-right direction in FIG. 5). Therefore, the strip 1 will not be pushed in by the reaction force from the strip 1 during the molding operation. In this case, it is of course possible to move the mover 12 using a screw.

With this structure, when applying a negative residual moment, as shown in Figure 6, which shows the working principle, the inner surface is bent to the maximum bending curvature that produces a predetermined negative residual moment. The reduction of the rolls 5 is adjusted, and the product is bent to the curvature shown by the broken line using the bending device, and then pushed back from the inside by the bending moment imparting rolls 7 to correct the shape as shown by the solid line to form the spiral pipe 2 with the planned pipe diameter. . In other words, in order to make the spiral tube 2 having a negative residual moment Mp' shown _in FIG ^. Strip 1 is bent to point A' based on the relationship γ/π+γ. If the material deformation resistance corresponding to t/ρ _i is σ _i and σ ^* is 1.15 times that value, then ρ _p /ρ Based on the relationship: _i =π/π+γ+3/2·σ ^* ·ρ _p /E·t, the strip 1 is given a bend with a curvature of 1/ρ _i as shown in FIG. Note that these formulas can be directly applied to the case of giving a positive residual moment, which will be described later. If this is spring-backed, the tube will have a curvature 1/ρ _p ' shown in Figure 3, and the tube will have a larger curvature (smaller diameter) than the curvature 1/ρ _p of the tube 2 to be made into a product. . Therefore, in this embodiment, the strip 1 is bent by the bending moment imparting roll 7 to point B' where the curvature is equal to the curvature 1/ρ _p of the product pipe.
is pressed and expanded by a bending moment imparting roll 7. By performing welding in this state to form the spiral tube 2 having a predetermined curvature 1/ρ _p , this spiral tube 2 will have a negative residual moment Mp'.

In addition, when applying a positive residual moment, as shown in Fig. 7, which shows the working principle, the product is bent to the curvature shown by the broken line using the bending device and pressed by the outer pressing roll 6 to form the shape shown by the solid line. Correct the required diameter to obtain the planned product pipe diameter. In other words, as shown in Figure 3
When trying to obtain a spiral tube 2 having a positive residual moment Mp, the bending moment imparting roll 7 is not necessary, and in this case, the bending moment imparting roll 7 is not required. Give the strip a bend with a curvature of 1/ρ _i corresponding to point A shown. If this is spring-backed by the outer pressing roll 6 and welded with a planned pipe diameter having a curvature of 1/ρ _p corresponding to point B to form a spiral pipe 2, this spiral pipe 2 will be as shown in Fig. 3. It has a positive residual moment Mp.

In this way, if the reduction amount of the bending device is adjusted so that the maximum curvature of the bending given by the bending device changes between point A and point A', the bending amount can be adjusted from point B to
It is possible to arbitrarily set the residual moment within the range of point B', that is, the range from point Mp to point Mp'.
If it is necessary to set the residual moment close to 0, the outer surface pressing roll 6 and the bending moment imparting roll 7 are brought into contact with the strip 1 at the same time to prevent variations in the pipe diameter due to unevenness in the material of the strip 1 or the plate thickness. It is desirable to suppress it.

Next, as shown in FIG. 8, which schematically shows the structure of an embodiment in which the present invention is applied to a pipe manufacturing apparatus equipped with an inner pressing roll, the structure is composed of outer bending rolls 3 and 4 and an inner bending roll 5. The strip 1 is bent into a spiral tube 2 by a bending device. When forming this strip 1 into a spiral shape, a large number of inner presser rolls 6' are movably supported by a pedestal 15 which is a combination of a roll support having a serrated smooth surface and a slider. This is performed using the roll support stand 16 and the bending moment applying roll 7. The bending moment imparting roll 7 is installed so as to be located on the outer surface side of the spiral tube 2 after the outer surface bending roll 4 on the exit side of the bending device. The roll 7 is a moving mechanism that utilizes a wedge action similar to that of the external pressing type.

With this structure, when applying a positive residual moment, as shown in Figures 9 and 3, which show the working principle, a bending device is used to apply pressure at point A to create the shape indicated by the broken line. After that, it is pushed inward by the bending moment imparting roll 7 and welded in the state shown by the solid line. That is, if spring-backed, the curvature at point C will be 1/ρ _p , and it will be pushed back to point B to obtain the intended product pipe diameter, and welded in that state.
This results in a positive residual moment Mp.

In addition, when applying a negative residual moment, as shown in Figure 10, which shows the working principle, a piece is bent to the curvature shown by the broken line using a bending machine in the same way as the conventional one shown in Figure 1b. Without using the bending moment imparting roll 7, it is pressed and expanded from the inside with the inner pressing roll 6', and the curvature is corrected to the solid line to obtain the intended product pipe diameter. In other words, as shown in Fig. 3, the product is bent to the curvature at point A' using a bending device, then spring-backed to point B' using the inner pressing roll 6', and then reversely bent and expanded. Welding is performed as it is, and a negative residual moment Mp′ is applied.

In this way, by changing the reduction amount in the range from point A to point A', the residual moment can be changed from point B to
It can be changed within the range of point B′. If it is necessary to set the residual moment close to 0, the inner pressing roll 6' and the bending moment imparting roll 7 are brought into contact with the strip 1 at the same time, as in the case described above, and the material and plate of the strip 1 are It is desirable to suppress variations in pipe diameter due to uneven thickness.

Specific experimental results based on these Examples will be described below.

Steel type SS41 (yield stress = 30Kg/mm ² ) Product pipe dimensions Outer diameter 800mm, wall thickness 9.0mm Bending rolls: Rolling up (lower) control with 3 rolls Initial bending can be made to various levels based on the above specifications FIG. 11 shows the results of manufacturing a spiral tube. In this experimental example, the magnitude of the residual moment is expressed by the ring opening degree γ, and the relationship between the ring opening degree γ and the residual moment is shown in FIG. The average push-up amount Sm is determined by the position S 1 of the contact point between the outer bending rolls 3 and 4 and the strip 1, with the tangent to the spiral tube 2 at the contact point between the inner bending roll 5 and the strip ₁ as a reference.
This is the average value of _S2 .

Next, as shown in FIG. 13, which shows the schematic structure of another embodiment in which the present invention is applied to a pipe making apparatus as shown in FIG. Sandwich the spiral tube 2
A pair of bending moment imparting rolls 7 are installed oppositely on the inside and outside of the. The residual moment is controlled by operating the pair of bending moment imparting rolls 7 in the radial direction of the spiral tube 2, but since the operating method is essentially the same as in the two embodiments described above, the explanation thereof will be omitted. Omitted. In addition, since it is necessary to maintain a constant pipe diameter, it is desirable to always have a pair of bending moment imparting rolls 7 in contact with the inside and outside of the strip 1.

By the way, it is natural that the bending moment imparting roll 7 in the three embodiments described above is set at the rear of the bending device, but usually it is located approximately at the exit side of the strip 1 from the bending device with the spiral tube 2 as a reference. By keeping it within the 90 degree range, it becomes possible to stably control the residual moment. Furthermore, in order to control the bending device and the bending moment imparting rolls 7, it is necessary to know how much influence a change in the deformation resistance of the strip 1 has on the spiral tube 2. This can be determined by the bending theory of plate materials and by inspection prior to manufacturing the spiral tube 2. From this inspection, it is possible to determine the relationship between residual moment, deformation resistance, the amount of reduction on the instrument of the bending machine, the amount of actual reduction, and the curvature, and to find the results in a graph or table. From these experiments, it has been found that when the physical properties change, it is possible to create a spiral tube 2 with the residual moment at the expected value by adjusting the reduction amount of the bending device based on the above graphs and tables. Can be done.

<Effects of the Invention> According to the spiral pipe manufacturing apparatus of the present invention, a bending moment imparting roll is provided which sandwiches the strip and faces the presser roll, or a pair of bending moment imparting rolls is provided which sandwich the strip. Spiral pipes for pipelines and steel pipe piles, each with good characteristics, can be manufactured using a single pipe manufacturing facility. Therefore, it is also possible to manufacture a long tube in which the residual moment gradually changes from positive to negative from one end to the other. In addition, by simultaneously pressing the inside and outside of the strip with these rolls, it is possible to maintain a constant tube diameter even if there are variations in the inner thickness of the strip or unevenness in the material, and the residual moment is close to 0. It is also possible to stably manufacture spiral tubes with high dimensional accuracy.

[Brief explanation of the drawing]

Figure 1a is a conceptual diagram of a conventional external press type spiral pipe manufacturing apparatus, Figure 1b is a conceptual diagram of a conventional internal presser type spiral pipe manufacturing apparatus, and Figure 1c is a conventional presser. A conceptual diagram of a spiral pipe manufacturing device without rolls. Figure 2 a and b are geometric diagrams of the spiral pipe before and after cutting to explain the ring opening degree. Figure 3 shows the spiral pipe before and after cutting. Graph showing the relationship between curvature and bending moment, 4th
The figure is a conceptual diagram showing the external appearance of an embodiment in which the present invention is applied to an external press type pipe manufacturing device, FIG. 5 is a mechanical conceptual diagram showing the drive mechanism of the bending moment imparting roll, and FIGS. 6 and 7. 8 is a conceptual diagram showing the external appearance of an embodiment in which the present invention is applied to an internal pressing type pipe manufacturing device, and FIGS. Fig. 11 is a graph showing an example of experimental results according to the present invention, Fig. 12 is a graph showing the relationship between ring opening degree and residual moment, and Fig. 13 is a graph showing the method of applying residual moment. FIG. 2 is a conceptual diagram showing the appearance of an embodiment in which the invention is applied to a pipe manufacturing device without a presser roll. Also, in the figures, 1 is a strip, 2 is a spiral tube, 3 and 4 are external bending rolls, 5 is an internal bending roll, 6 is an external press roll, 6' is an internal press roll, and 7 is a bending moment. It is a grant role.

Claims (1)

[Claims] 1. First and second bending rolls adjacent to each other along the pipe circumferential direction, and a third bending roll facing the bending roll with a strip sandwiched between these bending rolls. a welding device for welding the helical joint of the strip that is fed into a bending device having at least three bending rolls and wound into a spiral shape; In a spiral tube manufacturing apparatus, the spiral pipe forming apparatus is provided with a presser roll that is provided and comes into contact with the inner circumferential surface or the outer circumferential surface of the strip. In addition, a bending moment applying roll is provided sandwiching the strip and positioned on the opposite side of the presser roll, and the bending moment applying roll is used to press the strip so that the spiral pipe has a preset pipe diameter. A device for making a spiral tube, characterized in that the spiral tube can be displaced in the radial direction. 2. First and second bending rolls adjacent to each other along the pipe circumferential direction, a third bending roll facing the bending roll with a strip sandwiched between these bending rolls, and at least three of these bending rolls. A welding device for welding the helical joint of the strip that is fed into a bending device having bending rolls and wound into a spiral shape, wherein the welding device welds the helical joint of the strip, which A pair of bending moment imparting rolls are provided adjacent to this bending device on the downstream side in the sheet passing direction and located inside and outside of the spiral tube, and the strip is bent so that the spiral tube has a preset diameter. A device for making a spiral pipe, characterized in that the pair of bending moment imparting rolls are respectively movable in the radial direction of the spiral pipe in order to press the spiral pipe.