JPS583722A - Methof and device for manufacturing spiral pipe - Google Patents

Abstract

PURPOSE:To produce a spriral pipe having a desired residual moment in manufacture of the pipe from a steel hoop by making the forming conditions of the hoop to be automatically adjusted in response to the thickness and yield stress change of the hoop. CONSTITUTION:A curvature of a produced pipe is adjusted so as to have a prescribed value by retaining the outer and inner surfaces of a pipe 2 with forming rolls 18, 19, 20 provided on a charging side and a delivery side and internal surface forming stands 12, 13, 14 of a pipe manufacturing device. A steel hoop is continuously charged, while adjusting an outer surface restraining roll 37 and bending moment addition roll 41, and the hoop increases its curvature by being bent between a charging side forming roll 18 and inner surface forming roll 20, and obtains max. curvature at the position of the roll 20. The hoop 1 reduces its curvature gradually between the roll 20 and the delivery side roll 19 through a spring back action, and obtains the final curvature at the position of the roll 19, and is welded at the seam of the bent hoop with a welding torch to be fabricated into a spiral pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for making a spiral pipe, in which a pipe is made by welding edge seams while winding a strip in a spiral shape, and an apparatus therefor.

There are three main methods for manufacturing spiral tubes: an external pressing method, an internal pressing method, and a method without pressing rolls. In the external pressing method, a set of three rows of bending rolls arranged in a pyramid shape compresses and bends the strip, and a large number of fixed external pressing rolls presses down the outer surface of the formed strip in a spiral shape. Seam welding is performed while suppressing springback of the pressed and formed strip. Since the seam is welded while the unwelded formed strip is in contact with the presser roll, the formed strip is not completely unloaded, i.e., the seam remains fixed under internal elastic strain. be done. Therefore, when a slit is made in the longitudinal direction of a tube, a rebound (hereinafter referred to as a residual moment of pressure) occurs that opens the tube. In the internal press method, the strip is pressed down and bent using bending rolls similar to those described above, and the formed strip is slightly expanded using a fixed number of internal press rolls while seam welding is performed. When a slit is made in the longitudinal direction of the tube, a rebound (hereinafter referred to as negative residual moment) is generated that causes the edges of the slit to overlap. For the method without presser roll, the molded base) I/
The strip is formed so that the tube has the nominal outer diameter when fully springbacked, and since the residual moment is 0, springback will not occur even if longitudinal slits are made.

According to the conventional spiral tube manufacturing method,
Since springback does not occur in a method without presser rolls, a fixed amount of springback occurs in a fixed direction regardless of the manufacturer's intention, and there was no idea of intentionally imparting a residual moment. However, as the applications of spiral tubes have expanded, the inventors have realized that ignoring this residual moment can lead to defects in the product and negate its benefits. For example, if a positive residual moment force exists in a spiral line pipe for sour gas, stress corrosion cracking will be promoted, so it is desirable to apply a negative residual moment force. In addition, spiral pipes manufactured using the external pressing method have a large residual stress that causes a positive residual moment, so when used in a pipeline, the pipe expands due to the hydraulic pressure inside the pipe, resulting in a decrease in pipe strength. Roughly speaking, piles with sheet pile claws attached to spiral pipes with negative residual moment or no residual moment at all are
The cross-sectional shape of this pile will be distorted, but if this pile has an appropriate value of positive residual moment, it will be able to maintain its roundness. In this way, it is necessary to freely control the residual moment (internal elastic strain) that causes springback within an appropriate range depending on the application. However, conventional pipe manufacturing methods and devices are designed to simply produce a spiral pipe with a desired diameter, and there is no concept of controlling residual moment. In addition, conventional molding equipment is fixed and cannot freely adjust the amount of molding, so when using the same molding method and equipment, it is necessary to control the amount rather than creating positive and negative residual moments separately. Even that is difficult. Therefore, in order to create positive and negative residual moments, at least two types of equipment, an external pressing type and an internal pressing type, are required. However, installing two types of equipment in a small factory is economically disadvantageous because it lowers the equipment operating rate and increases costs.

An object of the present invention is to provide a pipe manufacturing method and apparatus that can freely adjust and apply a residual moment to a desired direction and value when manufacturing a spiral pipe.

Another object of the present invention is to provide a method and apparatus for manufacturing a spiral tube that can apply positive and negative residual moments to a product tube using one forming device.

Still another object of the present invention is to produce a spiral tube having a desired residual moment by automatically changing the forming conditions of the strip in accordance with changes in strip thickness and yield stress. An object of the present invention is to provide a manufacturing method and an apparatus for the same.

In this invention, in manufacturing a spiral pipe, the maximum curvature to be given to the strip in advance to generate the residual moment is determined based on the strip's plate thickness modulus of elasticity and yield stress, the curvature of the product pipe, and the residual moment to be given to the product pipe. demand.

This curvature is greater than the curvature of the product tube. Three rows of forming rolls arranged in a pyramid shape continuously bend and form the flat strip into a spiral of the maximum curvature by adjusting the mutual position of the forming rolls. Next, the spirally formed filter strip is sprung or expanded to the diameter of the product tube.Then, the seam of the edges of the strip is welded.

In the present invention, the strip is bent to a curvature larger than the curvature of the product pipe and then returned to the curvature of the product pipe, so a single pipe making device can create a residual moment of a desired magnitude and direction in the product pipe. can be given to

Further, in the present invention, while forming the strip into a spiral shape, the ratio of the change in the forming load to the change in the yield stress or the change in the forming amount is detected, and the change in the yield stress or the plate thickness of the strip is tracked. to adjust the position of the forming rolls relative to each other. Therefore, a desired residual moment can be applied to the product tube with high precision.

In the apparatus of the present invention, the bending moment imparting rolls are arranged adjacent to the exit side of the three rows of bending rolls. This roll suppresses springback of the spirally formed strip or expands the spiral to maintain the curvature of the spiral product tube.

In order to adjust the amount of bending of the strip in the bending device and the bending moment imparting roll, it is necessary to know how much a change in the deformation resistance of the strip, such as a steel strip, will affect the tube to be made. 2'7 can be determined by the bending theory described below and by inspection prior to manufacturing. In this inspection, residual moment, deformation resistance, the amount of reduction on the instrument of the bending machine (meter reading), the true amount of reduction, and the relationship between this and curvature are determined. and,
Make it possible to find the results of the test in a graph or table. If the properties of the steel strip to be considered change, a tube with a residual moment at a predetermined value can be produced by adjusting the reduction amount of the bending device based on the above graphs and tables.

The forming process of spiral steel pipes will be studied based on simple bending theory, and the adjustment of product diameter and residual moment based on this will be described below.

First, the ring opening degree, which has a one-to-one correspondence with the residual moment, will be explained.

From the geometric relationship due to the ring opening as shown in Figure 1, ρ1 is the radius of curvature of the product pipe, ρ0 is the ring opening degree,
That is, if it represents the radius of curvature of the pipe after complete springback, θ α = 2ρ. 51nT+2πρ,=(2π−θ)ρ0.

From these two equations, if the ring opening degree γ is defined as r-α/Dp, γ is given by the following equation.

The change in curvature caused by the ring opening will be explained from the relationship between bending moment and curvature. As shown in Figure 2, for example, a material bent to point A with a maximum curvature of 1/ρ1 is welded at the edge to a product with a product curvature of 1/ρ at point B in the middle of springback, and the residual moment MI remains. When a slit is made in the length direction of this product pipe and a ring is opened, the residual moment is released and the curvature of the pipe after the ring is opened is 1/ρ of point C. becomes. The same is true when bending to A' by increasing the maximum curvature and giving a negative residual moment M2, but in this case, in order to make the product curvature from C' to B', it is necessary to It is necessary to provide reverse opening. In this case, when the ring is opened, as can be seen from FIG. 2, the m-rate radius becomes smaller than the radius of curvature of the product, and α in FIG. 1 becomes negative, that is, γ becomes negative.

Since ω is usually a value around 1, an approximate calculation yields: It is expressed as

Also, if the stress-strain relationship of a material is, for example, an elastic perfectly plastic body, then from simple bending theory, E, σa, and 2t represent the Young's modulus, yield point, and plate thickness of the material, respectively.

In normal molding, the third term in parentheses in equation (3) can be ignored, so it becomes seven.

From r2L (4), the Young's modulus of the material is defined as the yield point (E, σ
When the pipe size (2t, ρp) and the maximum bending curvature 1/ρ1 are determined, the ring opening degree γ is determined.

By the way For positive or zero residual moments γ〉0. (ω≦1) ri≧ρ. )ρ.

For negative residual moments, γ〈0. (ω〉1) and ρ,〉ρ
. 〉ρ1.

Also, if the residual stress on the outermost surface of the product pipe is σB,
By calculating the simple bending theory, the ring opening degree can also be given by the following equation. That is, furthermore, the bending moment M per unit length of the pipe at the maximum curvature I/ρ1 and the residual moment M per unit length of the pipe are expressed by the angle.

As is clear from the bending theory described above, the spiral pipe is first bent by a bending device to a radius of curvature ρ1 that is smaller than the intended product pipe radius ρ.

The radius of curvature ρ after complete springback of the strip bent by this bending device, that is, the residual moment becomes O. The value and direction of the residual moment is determined by how much the force, ′-product, is greater, greater, or less than the product dive radius. After being bent to a radius of curvature ρ1, the pipe is pressed outward or inward by a bending moment imparting roll or a press roll that moves in the pipe diameter direction, and welding is performed while the product pipe radius is corrected to ρ.

In this way, it becomes possible to adjust the residual amount of bending moment and also to make it positive and negative. That is, in the case of the external surface pressing method, a negative residual moment, which could not be produced conventionally, is made possible by pressing the strip from the inner surface with excessive bending of the strip and seven bending moment imparting rolls. When trying to give a negative residual moment of M2 shown in the (moment-curvature) curve in Figure 2, the bending device should be adjusted so that a negative moment of M2 is obtained when the curvature of the product pipe is 1/ρ. The amount of bending, for example the amount of reduction, is advanced to point A', and then the product is pushed back to the product pipe diameter with a bending moment imparting roll, that is, the curvature is reduced to point B', and welding is performed and fixed. In this way, if the reduction amount of the bending device is adjusted so that the maximum curvature of the bend given by the bending device is changed between A and A', the range of B to B', that is, MI to M
The residual moment can be adjusted within the range of 2.

On the other hand, if a positive residual moment is to be imparted, this is achieved by pressing the strip radially relative to each other with a fixed outer presser roll, in particular a presser roll immediately after the bending device.

In addition, when using the internal pressing method, the positive residual moment, which could not be generated conventionally, can be moved in the direction of reducing the maximum curvature of the strip, and the strip can be pressed from the outside with a bending moment applying roll. When trying to give a positive residual moment of Ml shown in the (moment-curvature) curve in Figure 2, the curvature of the product pipe is 1
/pp, the reduction amount of the bending device is advanced to point A to obtain a positive moment of Ml, and then the bending moment applying roll is used to press down to the product pipe diameter, that is, the curvature is reduced to point B, and welding is performed. and fix it. On the other hand, if a negative residual moment is to be applied, this is achieved by pressing the strip radially relative to each other with an inner fixed presser roll, in particular a presser roll immediately after the bending device.

In this way, positive and negative residual moments can be freely controlled and produced using one molding method.

The present invention will be explained in detail below based on a specific embodiment of the apparatus shown in the drawings.

FIGS. 3 and 4 are a front view and a side view, respectively, of an external press type pipe manufacturing apparatus to which the present invention is applied. As shown in these drawings, the outer side molding stand 1 is placed on the base II.
2 and an external molding stand 13 are provided.

Further, an inner surface molding stand 14 is suspended from a frame 15 on the base 11 via a pin 16 and a support plate 17. The inner forming stand 14 faces the entry and exit forming stands 12.13.

Forming rolls 18, 19, 20 are rotatably attached to the inlet, outlet and inner forming stands 12, 13, 14, respectively. FIG. 4 shows the arrangement of the entry forming rolls 18. As shown in this figure, a large number of input side forming rolls 18 are arranged along the tube axis direction, and d exit side and inner side forming rolls 19 are inclined at the same angle as the advance angle of the spiral with respect to the tube axis. The arrangement of the rolls 20 is also the same as the arrangement of the entrance forming rolls 18. These forming rolls 18, 19 and 2° are arranged in a pyramid shape when viewed from the front.

As shown in FIG. 4, the entrance molding stand 12 includes a base 21 mounted on the base 1 so as to be movable in the tube axis direction, and a roll support base 22 mounted on the movable base 21 so as to be movable up and down. It consists of The movable table 21 is provided with a serrated smooth surface 23 that is inclined in the tube axis direction. Further, a shaft hole 24 extending in the tube axis direction is provided near the rear end of the moving table 21.
A threaded sleeve 25 is fitted into the rear part of the holder. A threaded rod 26 rotatably supported by a bearing 27 is fitted into the threaded sleeve 25 . A motor 28 with a speed reducer is connected to the threaded rod 26, and the rotation of the threaded rod 26 moves the movable table 21 forward and backward. The roll support stand 22 is the moving stand 21
The roll support base 22 is placed on the movable base 21 so that the groove surfaces 23 and 29 are in contact with each other. The roll support base 22 has a groove 3 near the tip of the smooth surface 29.
1 is provided, and a pin 32 fixed to a frame (not shown) of the base 11 is engaged with this groove 31.

Therefore, when the movable base 21 moves back and forth, the roll support base 2
2 is prevented from moving forward or backward by the pin 32, and moves up and down. Further, the input forming roll 18 is rotatably supported on the upper surface of the roll support base 22 via a block 33.

The exit molding stand 13 also has the same structure as the input molding stand 12 described above. And each forming roll 18.19
The vertical position of is adjusted by moving the moving table back and forth. Even if a vertical molding load acts on the movable table 21 during the molding operation, the movable table 2
1 does not advance or retreat, so the roll support base 22 does not move up or down at all. Therefore, the entry forming roll 18 is held in the set position. The same applies to the other forming rolls 19.

As shown in FIG. 3, a forming case 36 having a C-shaped cross section and extending in the tube axis direction is supported on the base 11 by pillars 35, as shown in FIG. The forming case 36 surrounds the tube 2 so as to cover the area between the position where the forming of the tube 2 begins and the welding position. A large number of outer pressing rolls 37 arranged along the outer peripheral surface of the tube 2 are rotatably attached to the forming case 36 via a support member 38 including a screw mechanism. External pressing roll 37
is moved in and out of the tube 2 in the radial direction by a screw mechanism of the support member 38 to adjust the holding position. In addition, the outer surface presser roll 3
7 contacts the outer peripheral surface of the tube 2 and rotates according to the spiral movement of the tube 2.

A plurality of bending moment imparting rolls 41 arranged along the tube axis direction are attached to the inner surface forming stand 14 . The position of the bending moment applying roll 41 in the inner circumferential direction of the tube is between the exit side forming roll 19 and the outer pressing roll 37, that is, on the exit side, as shown in FIG. It is desirable to be close to. The bending moment imparting roll 41 is attached in the same way as the entry and exit forming rolls. That is,
A moving table 43 having a serrated smooth surface 44 on the stand body 42
is supported. The movable table 43 is moved forward and backward in the tube axis direction by a threaded rod 45 that is rotationally driven by a motor 46 with a reduction gear. The roll support base 48 has a serrated smooth surface 49 and is supported by the stand main body 42 such that the smooth surface 49 contacts the smooth surface 44 of the movable base 43. Q-le support stand 48
As in the case of the input side molding stand 12, the movable table 4 is
It goes up and down by advancing and retreating in step 3.

A welding torch 48 protrudes from the front end (left end in FIG. 4) of the inner surface forming stand 14.

The tip of the welding torch 48 is directed toward the seam 3 on the inner surface of the tube 2. Although not shown in the drawing, the welding torch 48
A torch for welding the seam on the outer surface of the tube 2 is placed near the tube.

A method for manufacturing a spiral pipe having a required residual moment using the pipe manufacturing apparatus configured as described above will be described.

First, each roll is set in a predetermined position. That is,
The forming rolls 18, 19, 20 have an inner forming roll 20 that presses the inner surface of the tube 2, and a maximum curvature of 1 at the position of this roll 20.
/ρ, and the outer surface of the tube 2 is supported by the inlet and outlet forming rolls 18 and 19, and the outlet forming roll 19 is positioned so that the curvature of the product tube is 1/ρ. is adjusted. The outer pressing roll 37 and the bending moment imparting roll 41 are formed by forming rolls 18, 19, and 20, respectively.
The position is adjusted so that it contacts the outer and inner surfaces of the tube 2, which has been formed to have a final curvature of 1/ρ1.

A flat strip is continuously fed horizontally into the tube-making apparatus with the rolls positioned in this way, as shown in FIG. The strip 1 is bent between the entrance forming roll 18 and the inner forming roll 20, and the curvature increases, and the maximum curvature becomes 1/ρ1 at the position of the inner forming roll 20. Between the inner surface forming roll 20 and the exit forming roll 19, the curvature of the strip 1 gradually decreases due to springback, and at the position of the exit forming roll 19, the final curvature becomes 1/ρ.

Then, by the action of the bending moment imparting roll 41 and the pipe diameter maintenance by the outer surface pressing roll 37, which will be described below, the seam 3 of the spirally formed strip is fixed by the welding torch 48 while maintaining the final curvature of 1/ρ. be welded.

In the above-mentioned pipe manufacturing process, when applying a negative residual moment, the bending roll 18 is bent so that the bending curvature reaches the maximum bending curvature at which a predetermined negative residual moment is generated, as shown in FIG.
．． 19 is adjusted, the bending device is tilted, and the product is bent to the curvature shown by the chain line.The pipe is then pushed back from inside by the bending moment imparting roll 41 and corrected as shown by the solid line to obtain the intended product pipe diameter. In other words, as shown in FIG. 2, a product that has been previously formed with a bending device to a bending curvature of 1/ρ1 at point A' is pushed back from the inside with a bending moment imparting roll 41 until it reaches the diameter of the product pipe C'→B' ), and in this state, the joints are welded and a spiral tube is formed. Therefore, a negative residual moment M2 is generated.

On the other hand, when applying a positive residual moment, as shown in Fig. 7, the material is bent to the curvature shown by the chain line using the bending device and pressed by the outer pressing roll 37, and the shape is corrected as shown by the solid line. The product has a diameter of 4 □. In other words, as shown in Fig. 2, if the strip 1 is pressed down at point A using the forming device 5 and spring-backed, the strip 1 will be bent to expand to point C. and add a positive residual moment M. Therefore, if the maximum curvature of bending is set between A-A', the residual moment can be applied by any amount in any direction within the range B-B'. can only be added.

FIG. 8 is a front view showing an embodiment applied to an internal valve system. Components that are the same as those of the apparatus shown in FIGS. 3 and 4 are given the same reference numerals, and descriptions thereof will be omitted. The strip 1 is bent into a spiral tube 2 using a so-called 30-rupender bending device consisting of an outer bending roll 18, 19 and an inner bending roll 2α. A large number of internal valve rolls 52 supported by a stand 54 and a large number of internal valve rolls 52 supported so as to be movable in and out in the pipe radial direction by a pedestal 51 which is a combination of a roll support and a movable table having a sawtooth smooth surface similar to that shown in FIG. The diameter of the pipe is maintained by a moment applying roll 55.The bending moment applying roll 55 is installed so as to be located on the outer surface of the 30-lupender after the outlet outer surface bending roll 19. The pipe 55 is a moving mechanism that utilizes a wedge action similar to that of the external presser □ method.
It is supported by an internal valve roll support stand 57K disposed inside.

With this structure, in order to obtain a positive residual moment, as shown in Figures 2 and 9, after applying pressure at point A with the bending machine to form the shape shown by the chain line, It is pushed inward by the moment imparting roll 55 and welded in the state shown by the solid line. In other words, the curvature of C if springback is pressed down to B to obtain the planned product pipe diameter, and welding is carried out in that state. This results in a positive residual moment of Ml. When adding a negative residual moment,
As shown in FIG. 10, the pipe is bent to a curvature shown by a chain line using a bending device and then widened from the inside by an internal valve roll 52 to correct the curvature shown by a solid line to obtain the intended product pipe diameter. As shown in Fig. 2, the toe 1 is bent to the curvature of point A' by a bending device and then welded while being expanded to point B' by the internal valve roll 52, thereby creating a negative residual moment of M2. Add. By changing the reduction amount in the range of A-7A' in this way, the residual moment changes in the range of B-B'.

FIG. 11 is a front view showing an embodiment applied to a method without a presser roll. Two bending moment imparting rolls 61 and 62 are installed after the bending device so as to be located on the inner and outer surfaces. This internal and external bending moment imparting roll 6
1.62 can be used either one or both at the same time to provide a residual moment. The detailed operation method is the same as the external pressing method and the internal valve method described above, so the explanation will be omitted.

In this manner, according to the present invention, residual moment can be applied in any direction and in any amount. Furthermore, this can be done on the same pipe manufacturing line without requiring replacement of equipment. This not only makes it possible to create spiral tubes with a positive residual moment and spiral tubes with a negative residual moment in one piece of equipment, but also, if desired, from one end to the other from the positive residual moment region. It is also possible to produce a single spiral tube that changes continuously into the negative residual moment region.

Next, the basic concept of residual moment adjustment will be explained.

(1) Setting the initial value of residual moment or ring opening
2t, ρp) and the desired residual moment, that is, the ring opening degree (γ), the maximum curvature 1/ρ□ of bending by the bending device is given by the following equation (2) (from equation 41).

Normally, it is difficult to directly measure ρ□, so for example, the relationship between the curvature of the strip directly under the inner bending roll of the bending device and the roll position of the forming device is determined (8
) By setting the roll position corresponding to ρ1 in the equation, the initial value setting of γ can be achieved. This point will be explained below.

The present inventors conducted a theoretical analysis of the bending of a strip using three forming rolls arranged in a pyramid shape, and found that the ring opening degree γ could be adjusted by changing the positional relationship of these forming rolls. This will be explained in detail with reference to FIG. 12, which shows the positional relationship of the forming rolls. The forming roll is the entrance forming roll 18. It consists of an inner forming roll 20 and an exit forming roll 19. These forming rolls all have the same diameter r, as shown in the figure. is the forming roll equivalent radius, and ro = r + t. (
The plate thickness is 2t. ) The figure is therefore drawn so that each forming roll is tangent to the thickness center line N of the strip being bent. The horizontal distances of the inner forming roll 20 and the exit forming roll 18, 19 are each equal to 9. In addition, a person, exit side forming roll 18
．． 19 is a distance δ9 from the horizontal line H touching the lower end of the inner surface forming roll 20 to the upper end of each roll. It is expressed as δ2. Here, the average reduction amount δm−(δ
, +δ2)/2, the value δm/L2 is determined by the longitudinal elastic modulus E of the material, the yield stress σ, the radius ρ and wall thickness 2t of the tube, and the ring opening degree γ.

Figure 13 shows the above results confirmed by experiment, and r
It is a graph showing the relationship between δm/L2 and δm/L2. In this experiment, the tube radius ρ, = 400 ml + plate thickness 2t = (J + x + forming roll radius r = 40 rttrtr and s)
The test was carried out under the condition that the lip yield stress σa=30 and 9/ma. child.

As is clear from the graph, as δm/L2 increases, the residual moment changes from positive to negative.

By the way, in a bending forming apparatus, the forming roll radius r and the distance between the rolls are generally fixed, so the amount that can be adjusted during the forming operation in terms of the roll position relationship is the above-mentioned average rolling reduction amount δm. δm is the rolling reduction amount δ of the entrance forming roll 18,
and the rolling reduction amount δ2 of the exit side forming roll 19, but the present inventors further fixed δ2 at an appropriate value,
It has been found that the residual moment can be adjusted accurately by adjusting only δ1. Next, this will be explained.

Ideally, as shown in FIG. 12, the contact surface of the exit forming roll 19 should be on the outer periphery of the strip bent at the final radius of curvature ρ. (In the figure, the exit forming roll drawn with an equivalent radius r6 is shown touching the center line N of the strip at point P.) If there is no such contact, for example, the position of the exit forming roll 19 If .delta.2 is too high (.delta.2 is too large), the strip in the vicinity of contacting the forming roll 19 will curve in the opposite direction so that the outer surface of the tube is concave.

For this reason, wasted energy is consumed in forming, and it becomes possible to adjust the residual moment. Conversely, if the position of the exit forming roll 19 is too low (δ2 is too small), the forming roll 19 will move away from the strip, making it impossible to bend and form the strip to the desired curvature.

Appropriate position of the exit forming roll 19, that is, the optimum rolling reduction amount δ
2 can be obtained as follows with reference to FIG. The effective bending length at the center of the strip thickness! , if the bending inclination angle is θ, then from the geometrical relationship l: ρ sin θ
・・・・・・(9) L = l + 7
"esinθ...00)
From equations (91, (10)), L = (1), 10re ) sinθ ・
...(II) Also, the effective reduction amount (height of the contact P position) δ9 is δ1-δ-7'e (1-cosθ) =
It is expressed as pp(1-cosθ)-(12), from which δ, = (ρ, +To) (1-cosθ)...
03) According to (II) and Q31, the rolling reduction amount δ2 of the exit side forming roll 19 may be set in advance to the value given by equation (151).

As mentioned above, there is a certain relationship between δm/L2 and the ring opening degree γ, and therefore the residual moment, so the residual moment can be adjusted by the average reduction amount δm (=(δ1+δ2)/2) of the forming rolls. and furthermore, the formula (I5
) by setting the rolling reduction amount δ2 of the exit side forming roll 19, the residual moment can be adjusted only by the rolling reduction amount δ1 of the entry side forming roll 18.

(2) Response to disturbances (changes in σa and 2t) Adjustment of the residual moment M when disturbances occur due to changes in the yield stress σ of the strip and plate thickness 2t during forming will be explained.

Due to the elastic deformation of the rolling device, housing, etc. of the forming equipment, the apparent rolling amount sm and the true rolling amount δm of the forming rolls do not match, and the relationship between the two is expressed by the following formula (% formula %) where Q is the bending The forming load, K, is the spring constant of the forming stand.

On the other hand, the inventors experimentally found that the forming force Q of the material is σy
I learned that it can be considered as a function of +2t+δm. That is, Q=cp(σ, 2t+δm)・Yu 09 FIG. 14, which will be explained next, qualitatively shows Q−ψ(σY・2t, δIN) by a graph.

Also, since it is approximately δcxl/ρ, it is a function of ρ□. That is, 2m-8=V/(ρ1)・song・(I81Fll; l~0
From the barrel type, 5o-k・ψ(σy+2t+δff1) pass (ρ1)...
...α9 Now, the concept of residual moment adjustment will be explained using an example where σ changes to σ( during molding.

In order to keep the product diameter (2ρp) and residual moment (γ) constant, they must be changed from ρ1 to ρ'1 as σa → σ according to the relationship in equation (8), that is, 0
! 11, from srn to S'. =iψ(σ'Y, 2t+δ'm) + W(Q'
1) All you have to do is change the rolling reduction amount of the forming roll.

FIG. 14 is a graph explaining the above calculation.

Elastic characteristic straight line group sm, s', s'' of the forming device.

is S. Ha? Equation (161) is expressed as a meter. The forming load curve group Q, Q', Q'' expresses 2〇η with the yield stress σa as a parameter.Equation a is the plate thickness 2t.
is also used as a variable, but here the plate thickness is assumed to be constant. The straight line Mp represents the required residual moment. That is, if the required residual moment M is given, Mp
From J=Ql and approximately δCx-1/ρ, for example, the area below the straight line i in FIG. 2 can be approximately represented by the straight line Mp on FIG. 14.

In this FIG. 14, point a is the reduction amount S of the strip with yield stress σ. By forming with
This shows that a tube of

Now, if the yield stress changes to σ4, the forming load changes according to 207), and the load curve becomes Q'. In order to obtain the required residual moment, it is necessary to form with a forming load at the intersection of the straight line Mp and the curve Q'. The apparent reduction amount at this time is the amount S'□ indicated by the straight line S'o passing through this intersection point S.

Even when the plate thickness 2t changes, the required residual moment can be applied to the tube in the same manner as described above.

Next, the yield stress σa of the strip and/or the plate thickness 2
A method for automatically controlling the amount of bending of the strip in order to provide the required residual moment to the tube when t varies will be described.

FIG. 15 schematically shows a molding apparatus including a control device. Before the strip 1 is formed, it is flattened with a roller repeller 65. At this time, the roller leveler 65
There is a functional relationship between the load W applied to the roller 66 and the yield stress σ of the strip. Therefore, this function σ
, = f (W) can be found experimentally, then the load W
By measuring , the yield stress σ7 can be determined. The load W is continuously measured online by a load meter 67 using a load cell or the like. Measured load W
is input to the control computer 68, where the yield stress σ is determined from the function f(W)K. Also, the total thickness is 6
9, the plate thickness 2t is measured and the value is input to the control computer 68.

The control computer 68 has a function Q=' shown in FIG.
f'(σy + 2t +6m) and Q = K
(Sm-δm') is stored. Then, in the same procedure as described above, the yield stress Sm changed by these functions and/or the rolling reduction amount Sm of the forming device according to the plate thickness 2t are calculated in the computer 68.

FIG. 16 is a flowchart showing the calculation process in the control computer 68. The required pipe diameter Dp and residual moment M are preset in the computer 68.

Next, the yield stress σa and plate thickness 2t of the strip are measured, and these values are the initial values σ. , 2 to the computer 68. Based on these initial values, the 14th
The reduction amount Sm is determined by the calculation shown in the figure and is set in the computer 68.

Once the above settings have been completed, start pipe making, and σ1,
Measure 2t. These measured values σYI I2t,
If they are equal to the respective initial values σYOl 2 to K, pipe manufacturing is continued with the above-mentioned reduction amounts S and n, and if they are not equal, the reduction amount mixture is corrected and σyl + 2LH is newly set in the computer 68 as the initial value.

The determined rolling reduction amount 5ffl is input to the rolling down device 73. At this time, the time difference caused by the distance between the forming device and the roller leveler 65 is corrected by detecting the speed V of the strip 1 by a speed meter 72 connected to the pinch roller 71. That is, when the portion of the strip 10 whose load W has been measured by the roller leveler 65 comes to the position of the forming device, the required reduction amount SIn corresponding to this portion is given to the forming device.

The true rolling reduction amount δm of the forming apparatus is detected by a rolling reduction amount detector 73 that detects the position of the roll or the roll axis. The detected rolling reduction amount δm is fed back δ to the computer 68.

FIG. 17 is a schematic diagram of a molding apparatus including a control device using another control method.

In this device, the load Q applied to the forming roll 20 and the true reduction amount δ are determined by a load meter 75 and a reduction amount detector 76.
Detect each m. These detected values Q and δm are input to the control computer 77. The control computer 77 has a function Q−ψ(σy+2t+
δm) and target value ΔQ/Δδm- are input with 1 Mp. As mentioned above, since the line Mp shown in FIG. 14 is a straight line, the apparent rolling reduction amount S is set so that ΔQ/Δδm always becomes a constant value k. By controlling the true rolling reduction amount δm
control. The reduction amount S is input from the computer 77 to the reduction device 78 .

For example, when forming is progressing at point a on the forming load curve Q in Fig. 14, the yield stress σa of the strip is σ
Suppose it changes to ↓. For this reason, the molding load curve changes from Q to Q', and the molding conditions change from point a to C if molding is continued while keeping the rolling reduction amount 5Ifi of the molding roll as it is. At this time, the forming load Q with respect to the change in the true rolling reduction amount δm
The ratio of change in is ΔQ'/Δδ'm, which deviates from the target value k. In other words, the required moment Mp cannot be obtained and M′
, becomes. Therefore, when the reduction amount Sm is changed to S'o by a command from the computer 77, the point C indicating the molding condition moves along the curve Q' and finally reaches the point blc. At this time, the ratio ΔQ/Δδm becomes the target value, and the required residual moment Mp can be applied to the pipe.

FIG. 18 is a flowchart illustrating the calculation process in the control computer 77. Compuyu 1ri77
The required pipe diameter Dp and residual moment Mp are set in advance, and the yield stress σa and plate thickness 2t of the strip, which were measured in advance, are set in advance. Based on these set values, the reduction amount Sm is calculated by the calculation shown in FIG. 14, and this is set in the computer 77.

Once the above settings are completed, pipe production is performed, and the forming load and reduction amount at this time are measured, and these are set as the initial value Q. and δ
Set to 0. Then, pipe manufacturing is continued, and the forming load Q1 and the rolling reduction amount δ1 are measured. Q+””Q.

If so, continue pipe making, and if Q1 to Qo, calculate ΔQ/Δδ. If ΔQ/Δδ-, pipe making is continued, and if ΔQ/Δδ-ki, the reduction amount island is corrected so that ΔQ/Δδ=.

The present invention is not limited to the above embodiments.

For example, although the forming roll is of a split type, that is, it is composed of a large number of rolls, it may be a single forming roll. Further, for adjustment of the position or reduction of the forming roll, a screw-type or hydraulic reduction device may be used instead of the table having a serrated smooth surface.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the ring opening degree, where (a) shows the state before the ring is opened, and (b) shows the state after the ring is opened. FIG. 2 is a diagram showing the relationship between the curvature and bending moment of the pipe during forming and after completion. FIG. 3 shows an embodiment of a pipe manufacturing apparatus in which the present invention is applied to an outer surface pressing method, and is a front view of the forming apparatus. FIG. 4 is a side view of the apparatus shown in FIG. 3. FIG. 5 is a side view showing the structure of a pedestal that supports the bending moment imparting roll. FIGS. 6 and 7 are explanatory diagrams of the bending work in the outer surface pressing method. FIG. 8 shows an embodiment of a pipe manufacturing apparatus in which the present invention is applied to an internal valve system, and is a front view of the forming apparatus. FIGS. 9 and 10 are explanatory diagrams of the bending work in the internal valve method. FIG. 11 is a front view of an apparatus showing an embodiment in which the present invention is applied to a system without a presser roll. FIG. 12 is a drawing showing the mutual positional relationship of the forming rolls. FIG. 13 is a graph showing an example of the relationship between the position (δm/L 2 ) of the forming roll and the residual moment (γ). FIG. 14 is a diagram illustrating a method of adjusting the residual moment by adjusting the position of the forming roll. FIG. 15 is a schematic diagram of a forming apparatus including a device for automatically adjusting the forming amount by detecting changes in the yield stress of the strip. FIG. 16 is a flowchart showing the calculation process in the control computer shown in FIG. 15. FIG. 17 is a schematic diagram of a molding apparatus including a device that automatically adjusts the molding amount by detecting the ratio of the change in molding load to the change in the molding amount. FIG. 18 is a 70-tayat diagram showing the calculation process in the control computer shown in FIG. 17. Patent applicant Representative patent attorney Tomoyuki Yabuki (and 1 other person) No. 611 No. 81! 1 ζwa Fig. 7 @ 1111 Fig. 9 Fig. 10 ill 13 H 2 114 Fig. Q = K (5m - δm ) 6y = f(w)1116
Figure +71 Ryugo Dp, Mp 19 Width 6y, 2tll+l'L and V number 1 (6y0.2shiO) E, bottom + Sm thvig* Pipe making 6Y, 2t >It '1t (6yt, 2tt) YES em= (y. 2t+=2t. O Procedural amendment (voluntary) -t7 J ε Showa Lottery Reigetsu Sukyuichi Director-General of the Patent Agency Shima 1) Haruki Tono1, Indication of the case 1982 Patent Application No. 98358
No. 2, Name of the invention Method for manufacturing spiral tubes and its device 3. Relationship with the case of the person making the amendment Applicant address (residence) 6-3, Otemachi 2F, Chiyoda-ku, Tokyo Name (Name) 665) Nippon Steel Corporation 4,
Agent: 6, amendment: shallow: 3. - To I) (1) The scope of claims on pages 1 to 3 of the specification will be corrected as shown in the attached sheet. (2) Delete the 3rd to 2nd lines from the bottom of page 4 of the same book: ``Spring bank does not occur in a method without a presser roll.'' (3) In the sixth line from the bottom of page 5 of the circular, "this pile" is corrected to "this pipe." (4) "Plate thickness longitudinal elastic modulus" on page 7, line 9 of the same book is corrected to "plate thickness, longitudinal elastic modulus." (5) "Degree of opening" in the last line of page 9 of the same book is corrected to "after opening." (6) Lines 7 and 8 on page 12 of the circular are corrected as follows. "r≧0. (ω≦1) and ρ0≧ρP≧ρ1" (7) Correct equation (5) in the fourth line from the bottom on the same page of the same book as follows. (8) The same book, page 16, lines 1-2, page 23, lines 3, 6
"One example" in lines 1 and 2 on page 1, line 17 on page 39, and line 5 on page 39 are respectively corrected to "one example." (9) "Welding torch 48" on page 4, lines 3, 4, and 5-6 of the same book, and on page 21, lines 14-15,
Corrected to "welding torch" respectively. (10) "Work and" on page 21, line 12 of the same book is corrected to "work or." (11) In the same book, page 4, line 5, "one side" is corrected to "one side." (12) On the same page of the same book, line 122, "same pipe manufacturing" is corrected to "same pipe manufacturing." (13) On the 133rd line of the same page in the same book, ``Hitono'' is corrected to ``One''. (14) On the 16th line of the same page in the same book, ``ichi-end'' is corrected to ``ichi-end.'' (15) "Ippon J" in line 18 of the same page of the same book is corrected to "Ippon". (16) ``Figures 1-3'' on page 4, line 11 of the same book''
Corrected to ``Figure''. (17) Formula (12) in the second line from the bottom on the same page of the same book is corrected as follows. “δ = δ2-γe(1-cosθ)=ρp(1-co
sθ) ・(12)” (18) “Function of ρ1” on page 31, line 14 of the same book is corrected to “δm is a function of ρ1.” (19) Correct "-example" on page 39, line 14 of the same book to "-example." (20) Figures 1(b), 6, 7, 9, 10, and 18 of the attached drawings are corrected as shown in the attached sheet. Claim J: In a forming device equipped with three rows of forming rolls arranged in a pyramid shape along the inner circumferential direction of the pipe, (c) bending and forming the strip into a spiral shape while feeding the IJ tube in its longitudinal direction; , in a method of manufacturing a spiral pipe by continuously welding the helical joint, s) inserting an axial slit in the product pipe based on the thickness and yield stress of the IJ tube and the curvature of the product pipe. Then, the residual moment that causes the ring opening degree to be positive (open in the circumferential direction), negative (closed in the circumferential direction and overlap), or zero (neither open in the circumferential direction nor closed and overlapped) When trying to obtain a product pipe having a shape, the maximum curvature required in the bending process corresponding to the ring opening degree is determined, and the vertical position of the bending roll is determined according to the determined maximum curvature in the bending process. In order to continuously form the strip in a spiral shape by adjusting the . If you want to apply a negative residual moment (the ring opening becomes negative) to the product pipe by tightening the spring until it reaches the curvature, then spring back the above spring back until the curvature of the ring becomes the curvature of the product pipe. 2. A method for manufacturing a spiral tube, the method comprising: welding the helical joint after stretching and expanding the spiral tube. In an apparatus for manufacturing a spiral pipe, a spiral pipe is provided adjacent to the exit side of the forming apparatus in the circumferential direction of the pipe, and has a forming apparatus that performs forming and a welding apparatus that continuously welds the spiral joint. A bending moment imparting roll for supporting the strip surface so that the spiral tube of the strip becomes equal to the diameter of the product tube against spring puncture of the formed strip is provided in a position adjustable in the tube diameter direction. Spiral tube manufacturing equipment.

Claims (1)

[Claims] 1. The strip is bent into a spiral shape while being fed in the longitudinal direction into a forming device equipped with three rows of forming rolls arranged in a pyramid shape along the inner circumferential direction of the pipe; In the method of manufacturing spiral tubes by continuously welding the helical joint, if an axial slit is made in the product tube based on the thickness and yield stress of the strip and the curvature of the product tube. Products with a residual moment in which the ring opening degree is positive (opens in the circumferential direction), negative (closes in the circumferential direction and overlaps), or zero (neither opens in the circumferential direction nor closes and overlaps) When trying to obtain a tube, find the maximum curvature required in the bending process that corresponds to the ring opening degree, and adjust the vertical position of the bending roll according to the determined curvature in the bending process. In order to continuously form the strip in a spiral shape, and to apply a positive residual moment (the ring opening degree is positive) to the product tube following the above-mentioned forming, the curvature of the spiral should be When applying a negative residual moment ('ring opening degree is negative) to the product pipe by springing it back until it reaches the curvature, the above spiral is springbacked until the curvature of the spiral becomes the curvature of the product pipe, and then it is pushed out. A method for manufacturing a spiral pipe q, which includes later welding a spiral joint. 2. A spiral having a forming device for forming a strip into a spiral shape with three rows of forming rolls arranged in a pyramid shape along the inner circumferential direction of the pipe, and a welding device for continuously welding the spiral joints. In the pipe manufacturing apparatus, a strip surface is formed adjacent to the exit side of the forming apparatus in the circumferential direction of the pipe so that the spiral diameter of the strip becomes equal to the diameter of the product pipe against the springback of the spirally formed strip. 1. An apparatus for manufacturing a spiral tube, characterized in that a bending moment imparting roll for supporting the spiral tube is provided whose position can be adjusted in the tube diameter direction.