JP4906986B2 - Roll forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a roll forming method such as a welded steel pipe that realizes sharing of a forming roll regardless of a wide change in the dimensions of the forming material, for example, a position where the forming material is sandwiched by upper and lower rolls (pinch point) Is set only at the boundary between the target forming region in the material width direction and the pre-formed region or the un-formed region, and the target forming region is aligned with the predetermined caliber of the upper roll inside the bend, and the outer side of the target forming region is bent. By forming the bottom roll so that it hardly touches it, the bend formability is remarkably improved and the occurrence of roll wrinkles, roll marks and buckling is prevented, and edge-bend breakage is achieved. The present invention relates to a roll forming method for a new welded steel pipe or the like that realizes the use of a roll in a down forming portion.
[0002]
[Prior art]
In the roll forming of a welded steel pipe, a necessary cross-sectional shape is created by sequentially bending in the width direction of a strip-shaped base plate using a forming roll. In the breakdown forming portion, which is the initial stage of forming, the base plate is formed into a substantially semicircular cross-sectional shape. Thereafter, the base plate cross-section becomes an open circle through cluster molding and fin pass molding.
[0003]
In the breakdown forming part, mainly two types of forming methods as shown in the roll flour of FIG. 1 are used. In the edge bend method, the base plate is divided into several regions from the end toward the center (broken line circle, the upper side of the base plate is the inside of the bend, and the lower side of the base plate is the outer side of the bend). The method is taken. On the other hand, in the circular-bend method, a method of gradually increasing the curvature of the entire width of the base plate is adopted.
[0004]
Regardless of which molding method is adopted, in a conventional breakdown molding stand, usually a pair of upper and lower hole rolls shown in FIG.2A are arranged, for example, the lower roll has a concave portion and the upper roll becomes a convex portion, This is a molding method in which all of the width direction of the base plate, that is, both the inner side and the outer side of the base plate are sandwiched by the set roll gap and deformed.
[0005]
In such a conventional forming method, it is generally necessary to set a uniform roll gap equal to the plate thickness in order to give a target curvature to the base plate. However, in actual production, this molding method has the following problems.
[0006]
The plate thickness of the base plate always varies, and the plate thickness fluctuates unevenly during the molding process, so even if a uniform roll gap equal to the plate thickness is set, the roll surface and the plate surface are in close contact. Rather than being in a discontinuous contact state, the contact area and contact strength also change over time, and it is impossible to predict this change.
[0007]
As a result, first, it becomes difficult to set the reference diameter of the roll (the rotation diameter of the roll surface portion having a rotational peripheral speed equal to the moving speed of the base plate), and it is also difficult to synchronize the roll rotation speed at each stand. . Therefore, useless driving force and energy are often used, and wrinkles are easily formed on the product surface. Furthermore, the forming load and driving force in the width direction of the material become asymmetric, and phenomena such as meandering and rolling of the material are likely to occur.
[0008]
Since both the upper and lower rolls are perforated rolls, there is little flexibility in forming steel pipes of different sizes. For example, in the case of the edge bend method, when either the product outer diameter or the wall thickness changes, all the forming rolls must be replaced. In the case of the circular bend method, when the product diameter is the same, the roll can be used by adjusting the roll gap with respect to a change in the wall thickness within a certain range.
[0009]
Therefore, this molding method seems to be more practical than the edge bend method. However, when a relatively thin base plate is formed, the roll gap becomes non-uniform and the restraint on the base plate is insufficient, so the required formability is often not obtained. In other words, the combination of such rolls sacrifices moldability.
[0010]
However, in order to solve the problems of operability and productivity associated with the roll replacement work, in recent years, technical development for the combined use of rolls has been actively performed. A typical example is a cage forming mill.
[0011]
In this type of mill, a large number of small rolls (cage rolls) are arranged in place of the conventional cluster rolls, so that the rolls can be combined. However, in the breakdown forming part, as in the conventional mill, no roll-sharing is performed. In order to reduce the number of replacement rolls as much as possible, not only the cluster molding part but also part of the molding load that was previously shared by the breakdown molding part is transferred to the cage molding part, reducing the number of breakdown molding stands. Yes.
[0012]
However, the cage roll forming function is extremely limited. That is, since the contact area between the cage roll and the base plate is very small, each portion of the cross section of the base plate is formed with a non-uniform bending moment. The formability of such a free-bend bending method varies greatly depending on the product size and material, and it is extremely difficult to control the curvature as designed.
[0013]
In particular, the bending phenomenon frequently occurs in the central portion of the width where the bending moment is the largest. Even when the inner roll (convex roll) is used, the bending moment cannot be made uniform because the base plate does not normally follow the inner roll surface. On the other hand, bending tends to occur at the contact portion between the base plate and the inner roll.
[0014]
In such a molding method having a weak molding function, if an excessive molding load is shared, the molding function and stability of the entire mill are inevitably adversely affected. At present, many problems already appear in this type of combined mill.
[0015]
[Problems to be solved by the invention]
In order to eliminate such weak points of the cage type mill, various improvements have been made in the roll forming method (hereinafter referred to as FF forming method) disclosed in JP-A-3-12977 and JP-A-3-12976. is there. In the FF forming method, special rolls whose roll surface shape (roll caliber) has a continuous or stepwise change in curvature, and position adjustments to move and rotate these rolls. By using the mechanism, not only the cluster forming part but also the breakdown forming part can be used as a roll.
[0016]
In particular, a roll arrangement as shown in FIG. 2B is used in a so-called No. 1 breakdown stand that bends the base plate ridge where the forming is most difficult. In the roll arrangement of the FF forming method, appropriate extension curve calibers are provided on the upper roll (convex roll) and the lower roll (concave roll) according to the range of the inner diameter and outer diameter of all products.
[0017]
The roll gap formed from these rolls is usually not uniform, but the upper and lower roll positions are set so that a roll gap preferable for bending the end of the base plate is formed according to a specific product size. By using this forming method, the edge bending without exchanging rolls was possible for the first time, and the forming function of the entire mill was improved.
[0018]
However, even in this FF molding method, the other stands of the breakdown molding part basically adopts a circular bend type molding method, and also uses a roll, making it difficult to obtain the required moldability. As a result, the center of gravity of the molding load is still not in the breakdown molding part but in the cluster molding part having a weak molding function.
[0019]
This invention improves the fact that the center of the molding load of the FF molding method lies in the cluster molding part with a weak molding function without impairing the advantage of the roll combination in the FF molding method that basically adopts the bending method of the circular bend. The purpose of the present invention is to provide a novel roll forming method that enhances the forming function at the breakdown forming portion and greatly improves the overall formability of the base plate.
[0020]
[Means for Solving the Problems]
In order to further enhance the molding function by introducing an edge bend method into this FF molding method, the inventors have arranged a plurality of the above-mentioned edge bending stands in the breakdown molding part, and end the region about half the plate width. Proposing a molding method that bends sequentially from the part (Japanese Patent Application No. 10- 214320 PCT / JP98 / 04962).
[0021]
The above-described new molding method (hereinafter referred to as FF / X molding method) has greatly improved the moldability and stability of the entire mill. However, the bending method of FIG. 2B of the FF forming method is originally used for forming only the end portion of the base plate, and when the target forming region is wider, it is difficult to set an appropriate roll gap.
[0022]
Even in this FF, FF / X forming method, the basic idea of roll forming is the conventional forming idea of forming a base plate portion, which is a target forming region, from the inner and outer surfaces simultaneously using an uneven roll. . In addition, in this molding method, since the stretched curve caliber is used for both concavo-convex roll calibers, the entire area of the base plate does not come into contact with all of the concavo-convex rolls. The technical idea is to select an extension curve so that it can be molded.
[0023]
The inventors have improved the molding function in the breakdown molding part and improved the end of the base plate while effectively utilizing the advantages of the above-mentioned FF and FF / X molding methods that can be used as a roll in a pipe mill. As a result of many experiments and analyzes on the relationship between roll arrangement and forming function for the purpose of greatly improving formability, it is not always necessary to use a pair of concave and convex hole-type rolls simultaneously to bend the base plate. I got the knowledge.
[0024]
That is, the inventors set a part of the region in the width direction of the base plate to be formed (hereinafter referred to as a target forming region), the surface of the convex roll having a roll caliber having a certain curvature distribution or a part of the surface. In this way, even if a concave roll is not used to constrain the surface of the opposite side of the base plate as in the prior art, it is possible to “transfer” to the base plate area having the same curvature distribution as the convex roll surface portion. It has been found that roll forming is possible by following the surface of the convex roll without being restricted by the conventional concave roll.
[0025]
For example, the same molding object can be achieved by using the roll arrangement of FIG. 3 instead of the pair of concave and convex hole roll arrangements shown in FIG. 2A described above. In this case, the molding curvature is controlled mainly by the upper convex roll. The lower left and right pair of concave rolls have only a small part of the roll caliber compared to the conventional concave roll of FIG. 2A, but the role of the right and left rolls is to align the target forming area with the convex roll surface. Therefore, the support force by the concave and convex rolls is given only to the appropriate base plate part to create a system that can perform the bending along the above-mentioned, that is, the target molding area of the base plate is applied to the roll caliber part to be transferred of the convex roll. It is to control and support to touch.
[0026]
What is important in the bending along this invention is A pair of Pinch point that is the minimum roll gap position between rolls (pinch-point), that is, the pinch point where the material to be formed is sandwiched between a pair of rolls To set the required position to control the position in the plate width direction of the base plate, without constraining the entire target forming area of the base plate from outside the bending, For example This is to transfer and roll-form this along the surface of the roll caliber portion to be transferred of the upper convex roll inside the bend.
[0027]
If it is necessary to generate a driving force, the minimum roll gap between the convex roll and the concave roll is set to be equal to the plate thickness in order to obtain sufficient pressure and consequently frictional force, and this minimum roll gap is. Constrain both surfaces of the base plate at the same time only at the pinch point.
[0028]
Such a pinch point is usually set at the boundary between a preset target forming area and another base plate area, i.e., a pre-formed area (including a bending insensitive part at the material edge) or an unformed area at the time of designing. In operation, a pinch point for generating a driving force may be set at a boundary portion in the vicinity of this boundary.
[0029]
On the other hand, when it is not necessary to generate a driving force in a mill having a multi-stage roll stand, it is not always necessary to provide a pinch point. What is necessary is just to set the position of a concave roll so that the set target shaping | molding area | region may be followed along the convex roll surface part firmly.
[0030]
In short, in this new bending method, the area in the width direction of the material to be molded on the required roll stand is set as the target forming area, and this target forming area is scheduled to be transferred to the upper convex roll inside the bend. In order to transfer the curvature along the surface of the roll caliber part, a pinch point is set at the boundary between the target forming area and the other base plate area, and a concave roll that forms a convex roll and a pinch point is a conventional roll. In other words, the roll caliber is set so as not to make positive contact with the target forming region, in other words, so as not to restrain the target forming region from the concave roll side as much as possible except in the vicinity of the pinch point. Accordingly, since the concave roll does not directly participate in the control of the curvature of the target forming region, it is not necessary to provide a conventional roll caliber.
[0031]
In the new roll forming method according to the present invention, since the target forming region of the material is basically restricted only by the convex roll, it is difficult for excessive deformation to occur, the generation of excessive deformation strain is suppressed as much as possible, and secondary processing is performed. There exists an advantage which can manufacture the steel pipe excellent in property.
[0032]
When the roll is driven, the maximum surface pressure is generated at the pinch point, and the roll diameter at the pinch point may be set as the roll reference diameter. Since the position of the pinch point is very clear and does not vary, it is a great advantage that it is relatively easy to synchronize the driving force at each stand.
[0033]
Furthermore, even if the surface pressure at the pinch point fluctuates within a certain range due to variations in the plate thickness, the contact state between the base plate and the roll hardly changes, so the symmetry of the left and right forces is greatly disrupted, causing meandering and rolling. There is little induction.
[0034]
Therefore, the formability and workability of the mill can be greatly improved by introducing the concept of along-bending according to the present invention into the conventional breakdown forming portion. Moreover, in the molding method of this invention, since both the convex roll and the concave roll do not need to be perforated rolls, there is an advantage that the roll can be easily combined.
[0035]
That is, according to the present invention, in the roll forming method of a welded steel pipe, the entire target forming region in the material width direction to be formed is mainly aligned with the roll surface inside the bend without actively restraining from the outside of the bend. Furthermore, the position of the pinch point that sandwiches the material to be molded between at least a pair of upper and lower rolls is the target forming region in the material width direction to be formed with the forming roll and the pre-formed region (material edge). Roll forming that mainly forms along the roll surface inside the bend without constraining the whole of the target forming area from the outside of the bend. Is the method.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, the bending method for forming along the roll surface mainly inside the bending can be applied to all types of forming mills and forming methods, and the existing forming process can be streamlined. However, when used as part of a roll-combining technology, it is possible to make better use of superior functions that cannot be obtained with existing molding methods.
[0037]
In particular, this new bending method seems indispensable for the establishment of an advanced combined technology based on the edge bend forming method having a strong forming function such as the FF / X forming method described above. Here, as a specific application, a roll arrangement example and a roll forming method that can implement the concept of “along bending” named by the inventors and can also be used as a roll will be described.
[0038]
FIG. 4 shows the roll arrangement in the breakdown forming portion of FIG. 2B so that the forming method by “along bending” according to the present invention can be carried out. First, as shown in FIG. 4A, the pinch point is installed at a distance from the plate edge. The end portion of the base plate from the pinch point to the plate edge is called a bending insensitive portion because usually a sufficient bending moment cannot be obtained.
[0039]
The range of the bend insensitive part varies depending on the product dimensions and material, but here it is defined as approximately the plate thickness. The base plate of this part outside the pinch point is supported by the lower roll, and the target forming area inside it is By pressing the inner side of the target molding area with the center roll, that is, pressing the anti-pinch point side from the outside, Mold along the upper roll surface.
[0040]
Therefore, a pinch point is set between the bending insensitive portion in the width direction of the material and the target forming region, and here the lower roll has a flat contact surface so as not to be actively restrained from the outside of the bending. It is as.
[0041]
In order to cope with forming with different caliber sizes, it is natural to adjust the position of the upper and lower rolls, but the degree of forming is mainly determined by the roll caliber of the upper roll, so select the upper roll surface part with an appropriate curvature distribution. It is necessary to hit the target molding area.
[0042]
In particular, when the range of product outer diameters is wide, as with the conventional FF forming method, the upper roll is provided with an extended curve caliber, and in addition to translation, the roll contacts so that an appropriate caliber part can be selected. In order to change the surface (rotation), it is preferable to use a mechanism for supporting the direction of the support axis of the roll in a variable manner.
[0043]
For the lower roll, basically, it is not necessary to provide the extended curve caliber as described above. If the roll flower is appropriately designed, it is possible to cope with the molding of each size using a straight caliber as shown in FIG. 4A.
[0044]
However, if roll marks, wrinkles, etc. are predicted to occur due to the material and t / D (product thickness product outer diameter), the roll surface has a curvature close to the product size by providing an extension curve caliber on the lower roll. It is also possible to support the end of the base plate using a portion.
[0045]
On the other hand, the installation of the central roll and the formation of the W-shaped base plate cross section are not essential conditions for bending along the side, but have the effect of expanding the width of the target forming region. The shape of the center roll and the relative position to the upper and lower rolls may be set so that the planned target forming area is surely aligned with the upper roll in the formation of all products.
[0046]
The roll arrangement of FIG. 4A is very effective for edge bending, but can also be applied to bending of a base plate region other than the forming of the end portion. However, when the combined range of the roll is wide, it is necessary to give the curvature set in the target forming region and at the same time to protect the end portions of the base plate on the outside and the cross-sectional shapes of other pre-formed regions. Otherwise, a large amount of bending back will occur in the pre-formed region, and the planned cross-sectional shape may not be obtained.
[0047]
Therefore, the roll arrangement as shown in FIG. 5A is extremely effective for bending the base plate region other than the molding of the end portion. In this roll arrangement, a central roll is provided as in FIG. 4A, but this central roll not only enhances the bending effect but also forms a pinch point with each pair of upper rolls. It also has a role to generate driving force.
[0048]
Moreover, in the roll arrangement | positioning shown to FIG. 5A and FIG. 4B, unlike the roll arrangement | positioning of FIG. 4A, the side roll is provided. This side roll Outside the target molding area, that is, on the anti-pinch point side In the pre-formed area From outside the bend By making contact, the bending back of this region is suppressed, and at the same time, the bending moment due to the forming force from the side roll is utilized to form the target forming region outside the pinch point along the upper roll.
[0049]
On the other hand, as shown in FIG. 4B, because the bending moment acting on the pre-formed region is small, that is, the point of action of the side roll forming force is in this region, and the bending moment arm is short, so this region is greatly deformed. I will not let you.
[0050]
In addition, even if a small roll is used instead of the illustrated side roll, it is possible to prevent the phenomenon that the pre-formed region droops when viewed in the longitudinal direction of the material, and a plurality of small rolls are arranged in the longitudinal direction of the material. Thus, various contact directions can be set.
[0051]
Even in the above roll arrangement, the curvature of the target forming region is mainly controlled by the upper roll, so the roll curve caliber is used for this roll, and the roll is further rotated (rotated) or translated in the material width direction. It is preferable to select a caliber portion having a necessary curvature distribution and apply it to the target forming region of the material.
[0052]
As with the lower roll in FIG. 3, the side roll needs to be translated at least in order to cope with the molding of various product dimensions. In order to suppress the occurrence of roll wrinkles and roll marks as much as possible, it is desirable to provide an appropriate extension curve caliber. Therefore, the roll arrangement in FIG. 5A shows an arrangement in the case of a material for forming a relatively large diameter tube, and the roll arrangement in FIG. 5B shows an arrangement in the case of a material for forming a small diameter tube.
[0053]
The same applies to the Caliber in the center roll. In addition to the single roll shown in the figure, it is also preferable to adopt a two-part or three-part split type roll, corresponding to the molding of various product dimensions, the material width direction and the vertical height etc. By selecting appropriately, for example, by bending in a W shape as seen in a cross section in the width direction of the material, the target forming region of the material can be further abutted against a predetermined caliber portion of the upper roll.
[0054]
【Example】
Example 1
FIG. 6 shows an example in which the roll forming method and the apparatus according to the present invention are applied to No. 1 to No. 3 of the roll arrangement in the breakdown forming portion in the pipe mill by the FF / X forming method previously proposed by the inventors. A description will be given based on FIG. As shown in FIG. 7A, the pipe mill has a roll stand BD1, BD2, BD3 in the breakdown forming part, a roll stand RB in the reverse bend forming part, cluster rolls C1 to C6 in the cluster forming part, and a roll stand FP1 in the fin pass forming part. , FP2 is arranged.
[0055]
In the roll stand BD1 of the breakdown forming part, as shown in FIG. 6A, a pair of low tension left and right upper rolls whose direction of contact with the material is variable, and a narrow central roll and a pair of left and right are arranged on the lower side. A lower roll is arranged, and a pinch point is set between the upper roll and the lower roll at the boundary between the target forming area in the material width direction to be formed with the BD1 and the bending insensitive portion of the material edge. Thus, it has the same mechanism and function as those described in detail with reference to FIG. 4A and can perform predetermined edge bending.
[0056]
The roll stand BD2 shown in FIG.6B is composed of a pair of left and right upper rolls of a low tension type and a lower wide central roll, and a horizontal roll for abutting and supporting the end of the material formed by the previous BD1, Between the upper roll and the shoulder of the center roll, a pinch point is set at the boundary between the target forming area in the material width direction to be formed with the BD2 and the unformed area in the middle of the material. It has the same mechanism and function as those described in detail above, and can perform predetermined edge bending.
[0057]
The roll stand BD3 shown in FIG. 6C has the same mechanism and function as the previous BD2, and further performs molding on the center side of the material. The material end formed by the previous BD1 and BD2 is a horizontal roll. Is supported along the extension curve provided in the roll caliber, and the formed arc portion is prevented from spreading, and a roll flower with a predetermined edge bend shown in FIG. 1A is formed.
[0058]
Next, since the central part of the material is pushed up from below and is somewhat bent into a W shape, it is returned to the original by the roll stand RB shown in FIG. 7B, so the cluster forming part shown in FIG. 7C Can be easily and reliably implemented in the cluster roll C1. Further, the cross section is formed into a substantially cylindrical shape at the fin path forming portions of FP1 and FP2.
[0059]
By using the pipe mill shown in FIG. 7A according to the present invention, it is possible to realize edge bend molding in the breakdown molded part, and the moldability is remarkably improved, and it is possible to use the roll in the range of about three times the outer diameter ratio. became.
[0060]
Example 2
An example in which the roll forming method and the apparatus according to the present invention are applied to No. 1 to No. 3 of the roll arrangement in the breakdown forming portion in a conventional FF forming mill will be described with reference to FIGS. . As shown in FIG. 9A, the pipe mill has a roll stand BD1, BD2, BD3 in the breakdown forming part, a roll stand RB in the reverse bend forming part, cluster rolls C1, C2, C3 in the cluster forming part, and a roll in the fin pass forming part. Stands FP1 and FP2 are arranged.
[0061]
In the roll stand BD1 of the breakdown forming part, as shown in FIG. 8A, a pair of low tension left and right upper rolls with variable contact direction to the material, and a narrow center roll and roll caliber on the lower side A pair of left and right lower rolls provided with an extension curve are arranged, and between the upper roll and the lower roll, a target forming region in the material width direction to be formed with the BD1, and a bending insensitive portion of the material edge A pinch point is set at the boundary, and has the same mechanism and function as those described in detail in FIG. 4A, and can perform predetermined edge bending. Although not shown in detail in the drawing, the material does not contact the roll caliber of the lower roll from the pinch point in the width direction of the material plate to the center side.
[0062]
The roll stand BD2 shown in FIG. 8B includes a pair of left and right upper rolls, an upper roll, and a pair of left and right lower rolls, each of which is provided between an upper roll and a lower roll each having a roll curve. A pinch point is set at the boundary between the target forming area in the width direction of the material planned to be formed by the BD2 and the pre-formed area in the middle of the material, and the same mechanism and function as described in detail in FIG. And can perform a predetermined edge bend. Again, on the center side from the pinch point in the width direction of the material plate, the material is not in contact with the roll caliber of the lower roll, and conversely, the end of the material molded with the previous BD1 is the extension curve of the lower roll. It is supported by the roll caliber and retains formability.
[0063]
The roll stand BD3 shown in FIG. 8C has the same mechanism and function as the previous BD2, and further performs molding on the center side of the material. The end of the material formed by the previous BD1 and BD2 is the lower roll. Is supported along the extension curve provided in the roll caliber, and the formed arc portion is prevented from spreading, and a roll flower with a predetermined edge bend shown in FIG. 1A is formed. It is also effective to bring an auxiliary roll into contact with the edge.
[0064]
Next, since the center part of the material is pushed up from the bottom and is somewhat bent into a W shape, it is restored by the roll stand RB shown in FIG. 9B, so the cluster forming part shown in FIG. 9C Can be easily and reliably implemented in the cluster roll C1. Further, the cross section is formed into a substantially cylindrical shape at the fin path forming portions of FP1 and FP2.
[0065]
By using the pipe mill shown in FIG. 9A according to the present invention, it is possible to realize edge bend molding in the breakdown molding part, and the moldability is remarkably improved, and the roll can be used in the range of about 2.5 times the outer diameter ratio. became.
[0066]
【Effect of the invention】
This invention sets a pinch point of a material to be formed by upper and lower rolls at a boundary between a target forming region in a material width direction and a pre-formed region or an un-formed region, and sets the target forming region to a predetermined upper roll inside the bend. Along with the caliber, especially by forming the lower roll so that it hardly touches the bending outside of the target forming area, the bend formability is remarkably improved, and roll wrinkles, roll marks and buckling occur. It is possible to prevent.
[0067]
In the roll forming method according to the present invention, the concave roll is not directly involved in the control of the curvature of the target forming region, and the target forming region is basically only constrained from the convex roll, so that excessive deformation is difficult to occur and deformation strain is not generated. Generation can be suppressed as much as possible.
[0068]
Also, when driving the roll, the maximum surface pressure is generated at the pinch point, and the roll diameter of this pinch point is used as the roll reference diameter, so the position of the pinch point is clear and does not fluctuate, and the driving force at each stand Can be tuned.
[0069]
Furthermore, in the roll forming method of the present invention, since the contact state between the base plate and the roll hardly changes even when the thickness of the material is varied, meandering or rolling is not induced.
[0070]
In the roll forming method of the present invention, both the convex roll and the concave roll do not need to be perforated rolls, so that the roll can be easily used as a roll, and the formability and workability are greatly improved by introducing the roll into the breakdown forming portion. it can.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram showing a roll flower in a breakdown forming part, where A is an edge bend method and B is a circular bend method.
FIG. 2 is an explanatory view showing a roll arrangement of a conventional breakdown forming stand, wherein A is an example of a pair of upper and lower hole-type rolls, and B is a roll of FF forming method.
FIG. 3 is an explanatory view showing a roll arrangement for showing a concept of “along bending” according to the present invention.
FIGS. 4A and 4B are explanatory views of roll arrangement showing an example in which “along bending” according to the present invention is applied to a breakdown forming stand.
FIGS. 5A and 5B are explanatory diagrams of a roll forming apparatus in which “along bending” according to the present invention is applied to a roll forming method for a welded steel pipe, where A is a large diameter pipe and B is a small diameter pipe.
FIGS. 6A and 6B are explanatory views showing the roll arrangement of the roll stand of the breakdown forming portion of the embodiment to which the roll forming method and apparatus according to the present invention are applied.
7A is an explanatory perspective view showing a roll arrangement of a pipe mill to which the roll forming method and apparatus according to the present invention are applied, FIG. 7B is an explanatory view showing a roll arrangement of a reverse bend forming portion, and C is a cluster forming. It is explanatory drawing which shows the roll arrangement | positioning of a part.
FIGS. 8A and 8B are explanatory views showing the roll arrangement of the roll stand of the breakdown forming portion of another embodiment to which the roll forming method and apparatus according to the present invention are applied.
9A is a perspective explanatory view showing the roll arrangement of another pipe mill to which the roll forming method and apparatus according to the present invention are applied, FIG. 9B is an explanatory view showing the roll arrangement of the reverse bend forming section, and C is It is explanatory drawing which shows the roll arrangement | positioning of a cluster formation part.

Claims (7)

In roll forming method for molding giving sequential required curvature to these areas toward the both ends of the material to be formed to the central portion in the width direction and set a plurality of target forming zone, the roll pair on the material widthwise side The pinch points on both sides that sandwich the material to be formed between the pair of rolls and the lower roll are the target forming region that is a partial region in the material width direction that is to be formed by the forming roll, and the material edge that is outside the target forming region in the material width direction bending set the boundary portion between the ready-made type region including the insensitive portion, said without the outer bend the whole of the target forming zone to restrain roll, unformed region material width in the anti-pinch point side of the target forming zone of A roll forming method in which the target forming region is pressed along the upper roll surface on the inner side of the bending by pressing from the outer side of the bending with the central roll below the center of the direction . In roll forming method for molding giving sequential required curvature to these areas toward the both ends of the material to be formed to the central portion in the width direction and set a plurality of target forming zone, the roll pair on the material widthwise side a target formation zone pinch points on both sides sandwiching the material to be formed, which is a material width direction a part area to be molded in the molding roll and the material widthwise center lower side middle rolls, material width direction of the target forming zone Set at the boundary with the unmolded area on the inside and bend the preformed area on the side opposite to the pinch point of the target molded area with the side roll without constraining the entire target molded area with the roll from the outside. A roll forming method in which the target forming region is pressed along the upper roll surface on the inner side of the bending by pressing from the outside. The roll forming method according to claim 1 or 2, wherein an auxiliary roll is brought into contact with the pre-formed region of the material to be formed from the outside of the bending. The roll forming method according to claim 1 or 2, wherein the roll caliber of the roll has a shape in which a plurality of arcs are combined. The roll forming method according to claim 4, wherein an extended curve caliber is used for the roll. A roll forming method using the forming method according to claim 1 or 2 for forming a breakdown forming part of a roll forming method of a welded steel pipe. The roll forming method according to claim 1 or 2, wherein a flat roll is used as the lower roll.

Images