EP1169149B1 - Method for roll forming steel pipes, and equipment for same - Google Patents
Method for roll forming steel pipes, and equipment for same Download PDFInfo
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- EP1169149B1 EP1169149B1 EP99917140A EP99917140A EP1169149B1 EP 1169149 B1 EP1169149 B1 EP 1169149B1 EP 99917140 A EP99917140 A EP 99917140A EP 99917140 A EP99917140 A EP 99917140A EP 1169149 B1 EP1169149 B1 EP 1169149B1
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- forming
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- the present invention relates to a roll forming method for welded steel pipes; with said method the common-utilization of rolls can be realized regardless of the wide variation in dimensions of materials to be formed.
- the present invention more specially, relates directly to a novel roll forming method for welded steel pipes by setting the pinch-point (which is a specified location for holding the material to be formed with upper and lower rolls) at the boundary area between the target forming zone and formed or un-formed zone along the width direction of the material, and by making said target forming zone in contact with the pre-determined caliber of the upper roll which is placed on the bend-inner side but not making the bend-outer side of the target forming zone in contact with the lower roll to perform the bend forming process, so that the bend-formability can be remarkably improved, roll-flaws or roll-scratches can be avoided, and accordingly the common-utilization of rolls can be realized at the break-down forming portion for the edge-bend method.
- a required cross sectional profile will be made by bending the band steel subsequently in the material's width direction using forming rolls.
- the material to be formed (which is the band steel plate) is, in advance, formed into a semi-circular shape.
- the thus pre-formed material is then processed through the cluster forming and the fin-pass portion, where the material is formed into an open-shape circular cross-sectional profile.
- the material to be formed is divided into several portions along the width direction and is formed portion by portion to approach the final circular shape.
- the bend-inner side is referred to the position above the steel plate; while the bend-outer side is referred to the position below the steel plate.
- the circular-bend method the curvature of the total width of the material is increased stepwise.
- one pair of upper and lower contour rolls is normally used in the conventional breakdown forming stand, as seen in Figure 2A.
- the pair of rolls is consisted of a lower roll 2 with concave roll surface(caliber) and an upper roll 3 with convex caliber.
- the target forming zone of the material 1 to be formed (in other words, both sides of bend-inner and bend-outer sides of the material) is pressed in the pre-set roll gap.
- the reference diameter of the roll which is a diameter corresponding to the roll surface portion having an equivalent rotational speed to moving speed of the material in the longitudinal direction
- the surface of the final roll-formed product will suffer from the surface scratches and flaws.
- the band steel plate is apt to twist in the forming process.
- both lower and upper rolls are used to form a desired roll gap, there is no flexibility to accommodate to the steel pipe forming with various sizes. For example, when either outer diameter or the wall thickness of the product changes, with the edge-bend method, all forming rolls are required to be exchanged. On the other hand, by the circular-bend method, if the outer diameter of the products remains the same value, rolls can be common-employed in forming pipes with various wall thicknesses (if they are within a certain limit) by adjusting the roll-gaps.
- the circular-bend method is considered to be more practical than the edge-bend method.
- the roll-gaps will become to be uneven and constraint on the material is not sufficient, so that the expected formability can not be achieved. In other words, such common-utilizing of rolls might sacrifice the resultant formability.
- the common-utilization of rolls has been proposed by arranging a plurality of small-size rolls (cage rolls) instead of the conventional type of cluster rolls.
- the common-utilization of rolls is not realized.
- the forming load at the cluster forming portion but also a part of the forming load which is originally carried out at the breakdown forming portion are shifted to the cage-forming portion, so that the number of breakdown forming stands can be reduced.
- the forming function of the cage rolls is extremely limited. Namely, since the contact area between the cage rolls and the material to be formed is very small, each cross-sectional portion of the material is formed under the non-uniform bending moment. The formability of such free-bending method depends strongly upon the size and material properties of the products. Accordingly, it is extremely difficult to obtain the desired curvature distribution as has been designed.
- the upper and lower rolls are applied to the strip at a forming region where the strip is roll formed by the upper and lower rolls such that the strip is wound around the roll surface of the upper and the lower rolls; therefore the strip is constrained by both the lower roll on the bend outer side and the upper roll on the bend inner side. Furthermore, this document does not disclose a pinch point.
- the common-utilisation of rolls can be realised not only at the cluster forming portion but also at the breakdown forming portion by using a special roll whose calibre is an involute (which changes its radius curvature either continuously or step-wisely) and employing a position-controlling mechanism for transferring and rotating such rolls.
- the roll arrangement as seen in Figure 2B is normally used for the so-called No. 1 breakdown stand.
- suitable involute curves are provided to the upper roll 3 (convex roll) and the lower roll 2 (concave roll) respectively, corresponding to the limits of inner and outer diameters of all products in concern.
- the roll gaps formed with these rolls are normally not uniform, the upper and lower roll positions are determined in order to form the favourable roll-gaps at the edge portion of the material 1, corresponding to the size of the product to be formed.
- the circular-bend type forming method is basically used to the stands except the No. 1 breakdown stand. As a result, most of the forming work is still carried out as the cluster forming portion.
- US 4,770,019 discloses a method, and apparatus for applying the method, for (1) forming a pipe from a strip having a bent-inner side and a bent-outer side and a target forming zone, the roll forming taking place between at least one pair of an upper roll and a lower roll, the method comprising the steps of applying an upper roll to the bent-inner side of the strip and applying the lower roll to the bent-outer of the strip; (2) winding the target zone of the strip around a roll surface of the upper roll on the bent-inner side, being constrained from the bent-outer side by the lower roll.
- the disclosed method and device are directed to forming pipes having large or small diameters using a single set of forming rolls.
- This document further discloses a roll forming equipment comprising one piece or separate type of lower roll, and a pair of upper rolls, whereby the axial direction of the rotating axes of upper the rolls can be changed in order to support the material to be formed.
- an object of the present invention to provide a novel roll forming method and equipment for same, with which, basically without deteriorating any advantages of the common-utilisation of rolls in the FF forming method which uses the circular-bend method, the fact - that the forming work of the FF forming method is mainly located at the cluster forming portion showing the poor formability - can be modified, the formability can be enhanced at the breakdown forming portion, and the overall formability can be remarkably improved.
- the present inventors have proposed a novel forming method (Japan Patent Laid-Open Publication No. 2000-084619, PCT/JP98/04962) published on 29.02.2000 and EP-A-0988905 published on 29.03.2000 in which the edge-bend method is introduced to the FF forming method and a plurality of edge-bending stands is used at the breakdown forming portion in order to enhance the forming function and approximately half zone of the plate's width is formed portion by portion from its edge sides.
- the overall formability and stability of the mill system are improved.
- the bending method as seen in Figure 2B of the FF forming method is conventionally used only for forming the material's edge portions and it is difficult to set the suitable roll-gaps for the case when the target forming zone is relatively wide.
- this forming method has a technical concept such that although the target forming zone is not expected to be in contact with both concave and convex rolls since the involute calibers are used, the appropriate roll surface portions of convex and concave rolls are selected in order to bend the material in the roll gap into a shape similar to that of roll gap as possible.
- the present inventors have conducted experiments and analyses to investigate the relationships between roll arrangement/orientation and forming functions in order to enhance the forming function at the breakdown forming portion while using effectively all advantages of FF, FF/X forming methods which make it possible to common-utilize the rolls at the pipe mill system.
- the present inventors have come to a conclusion that, in order to bend the material into a desired shape, it is not essentially necessary to employ a pair of concave and convex contour rolls.
- the present inventors have found that, by winding a portion of the cross-section of the material to be formed (which is hereafter referred merely as to a target forming zone) around either an entire or a portion of the surface of the convex roll having a roll caliber with a certain curvature distribution, the almost same curvature distribution can be printed onto the target forming zone of the material without constraining the opposing surface by using the concave roll as been practiced conventionally.
- this new bending method is named as 'embrace-bending'.
- the same forming can be achieved by employing the roll arrangement as seen in Figure 3 instead of providing a pair of convex and concave rolls as seen in Figure 2A.
- the control of the curvature distribution is mainly conducted by the upper convex roll 12.
- the principle function of these rolls is to provide a supporting force in order to wind the target forming zone around the convex roll surface 12, so that the embrace-bending can be performed.
- the target forming zone of the material can be controlled and supported in such a way that it can be in contact with the convex roll caliber portion whose curvature distribution is expected to be printed.
- the pinch-point serving a minimum distance between the convex and concave rolls is set at a certain location to control the position of material along the width direction.
- the target forming zone of the material is wound around a caliber portion of the convex roll at the bend-inner side to print the expected curvature distribution to the target forming zone without constraining it from the bend-outer side.
- the minimum distance between the convex and concave rolls at the pinch-point should be set to be equal to the wall thickness in order to obtain sufficient amount of pressure or frictional force. Both surfaces of the material are simultaneously constrained only at the pinch-point.
- Such a pinch-point is designed and set at the boundary area between the target forming zone and other portions of the material; which is, in turn, the portion being formed previously including the bending non-sensitive zone of the material's edge portion or un-formed portion of the material.
- the driving force when the driving force is not required, it is not essential to constrain the inner and outer surfaces of the material simultaneously at the pinch-point. Instead, it is simply required to set the position for the concave roll in order to wind the target forming zone around the convex roll surface.
- the first aspect of the invention is a roll-forming method for forming a pipe from a strip having a bend-inner side and a bend-outer side and a target forming zone, the roll-forming taking place between at least one pair of an upper roll and a lower roll, the method comprising the steps of: forming a pinch point by applying an upper roll to the bend-inner side of the strip and applying the lower roll to the bend-outer side of the strip; setting the pinch point at a boundary between the target-forming zone and an adjacent portion of the strip; and winding the target zone of the strip around a roll surface of the upper roll on the bend-inner side without being constrained from the bend-outer side by the lower roll.
- the zone along the width direction of the material to be formed at a certain stand is set as the target forming zone
- the pinch-point is set at the boundary between the target forming zone and other portions of the material in order to print the desired curvature distribution by winding the target forming zone around the surface of the convex roll mounted at the bend-inner side
- the lower roll calibre is sent in such a way that this roll will not contact the target forming zone from the bend-outer side as the conventional method does. Consequently, it is not necessary to provide the conventional type of roll calibre since the concave roll is not directly related to control the curvature distribution of the target forming zone.
- the target forming zone of the material is basically constrained by only the convex roll, severe deformation hardly takes place. Moreover, occurrence of the excess deformation strain is controlled to the utmost, resulting in that steel pipes with excellent secondary-formability can be produced. This is the first advantage of the present novel roll-forming method.
- the roll diameter at the pinch-point can be considered as the reference roll diameter. Since the position of the pinch-point is very clearly identified and does not vary, it is very easy to synchronize the driving speeds among each stand. This is the second advantage of the present novel roll-forming method.
- a second aspect of the invention is a roll forming equipment for the performance of a roll forming method for forming a pipe from a strip having a bend-inner side and a bend-outer side and a target forming zone
- the roll forming equipment comprising: (a) one piece or separate type of lower roll; (b) at least one pair of upper rolls in the material's width direction; and (c) a pair of side rolls being provided in the horizontal way at the edge portion of the material, whereby the axial direction of the rotating axes of upper and lower rolls can be changed independently in order to support the material being formed, in use of the equipment the roll forming taking place between the at least one pair of upper rolls and the lower roll, the side rolls being in contact with the previously-formed zones of the material from the bend-outer side to prevent bending-back phenomena
- the equipment being prepared for being used in a method comprising the steps of: i) forming a pinch point (pp) by applying the upper roll to the bend-inner side of the strip;
- the target-forming zone is that part of the strip being roll formed in the above method of the present invention which is one step in the forming of a pipe. It is not the whole width of the strip being formed in the overall pipe forming process.
- the embrace-bending method is basically applicable to all types of forming mills and forming methods and it is possible to rationalize the existing forming processes.
- the excellent function which can not be realized with the conventional forming methods can be recognized.
- the present novel bending method is indispensable in order to establish the advanced common-utilization technology of rolls based on the edge-bend forming method having a strong forming function such as the aforementioned FF/X forming method.
- the roll arrangements at the breakdown forming stand of Figure 2B is modified in order to perform the "embrace-bending" method of the present invention.
- the pinch-point, pp is provided at a place apart from the plate edge with a certain distance.
- the area from the pinch-point, pp, to the plate edge is called as the bending non-sensitive portion 1a since the sufficient bending moment is not normally obtained.
- the range of the bending non-sensitive portion 1a depends upon the product's dimensions and material type, it can be defined as to be almost same as the plate thickness.
- the bending non-sensitive portion 1a being located on the outer side of the pinch-point, pp, is supported by the lower roll 20, and the target forming zone 1b located on its inner side is wound around the upper roll surface 21 in order to be bent.
- the pinch-point, pp is set between the bending non-sensitive portion 1a and the target forming zone 1b.
- the contacting surface of the lower roll 20 has a flat surface in order to avoid constraining the target forming zone from the bend-outer side.
- the involute caliber may also be provided to the lower roll 20, so that the material edge portion can be supported by the roll surface portion having the curvature close to that of the product
- the embrace-bending does not essentially require to provide the central roll 22 and to form the W-shape cross-section of the material, it possesses a beneficial effect to widen the range of the target forming zone.
- the shape of the central roll 22 and its position can be set in such a manner that, for forming all different sizes of products, the expected target forming zone should be certainly wound around the upper roll 21.
- the roll arrangement seen in Figure 4A is very effective to bend the edge portion, and is also applicable to bend other portions of material. However, when the range of the common-utilization of rolls is wide, while providing the pre-determined curvature distribution to the target forming zone, it is also necessary to support the previously-formed zone to prevent the bending-back phenomena.
- the roll arrangement as seen in Figure 5A is extremely effective to form target forming zones except the formed edge portion.
- the central roll 30 is provided as similarly as the case in Figure 4A, it is used not only to improve the embrace-bending efficiency, but also to form the pinch-points, pp, by combining with a pair of upper rolls 31,32 to generate the driving force.
- side rolls 33,34 are provided.
- the side rolls 33,34 are in contact with the above mentioned previously-formed zone in order to prevent the bending-back phenomenon.
- the target forming zone 1c located at the outer side of the pinch-point pp is wound around the upper rolls 31,32 efficiently.
- the involute caliber to these rolls 31,32 and rotate and/or parallel-move these rolls 31,32 along the width direction of the material to select the caliber portion to contact the target forming zone of the material.
- the central rolls can be made for the central rolls. It is preferable to employ the separate-type rolls such as two-part-type or three-part-type rolls, which is better than to have a single roll as seen in the figure. It will become more easy to make the target forming zone of the material attach to a certain portion of the caliber of the upper roll by appropriately selecting the position of central roll in width or vertical direction.
- the separate-type rolls such as two-part-type or three-part-type rolls, which is better than to have a single roll as seen in the figure. It will become more easy to make the target forming zone of the material attach to a certain portion of the caliber of the upper roll by appropriately selecting the position of central roll in width or vertical direction.
- edge stretch which is the main cause of the edge wave, is apt to take place at these stands.
- Roll wear and edge wave mentioned above may occur even when using the embrace-bending method of the present invention.
- the present inventors have discovered that, small-size auxiliary rolls being in contact to the edge of the material can be mounted at vicinity of the upper and/or lower stream of the breakdown forming stands, so that some of the forming load will be allotted to the auxiliary roll, resulting in that the forming load and surface pressure which are acting on the lower roll will be reduced.
- the edge portion of the material 1 will be gradually rising while approaching to the center of the upper roll 40 or lower roll 41 at the breakdown forming stand. At an early stage of the contacting process, only the sharp outer edge corner of the material will be in contact to the lower roll surface 40.
- a pair of small-size non-driven type second auxiliary rolls 53,54 is mounted at a vicinity of the upper and lower stream close to the lower rolls 50,51 to attach to the outer edge corner of the material 1, so that the edge portion of the material 1 can be supported.
- the contact with the auxiliary rolls 53,54 dulls the outer edge corner of the material and reduces the possibility of occurrence of the abnormally high surface pressure. Furthermore, by mounting the second auxiliary rolls 53,54, some of the forming load will be allotted to the auxiliary rolls 53,54 and the forming load and surface pressure acting on the lower rolls 50,51 can be reduced.
- auxiliary roll 53 When the auxiliary roll 53 is provided at only the upper stream, it is preferable to constrain firmly the material along the longitudinal direction by mounting the auxiliary roll 55 at the lower stream side of the forming stand since the steel band will rotate along the longitudinal direction around the upper roll 52 as a supporting point and the effect of the auxiliary roll 53 will be reduced if there is no auxiliary roll mounted at the lower stream side of the forming stand.
- the wear problem of the auxiliary roll can not be avoided.
- the auxiliary roll according to the present invention is a small-size non-driven type, roll per se as well as its supporting mechanism can be very simple compared with the forming rolls, so that the equipment and maintenance cost will be low and exchanging operation for polishing these roll surfaces will also be easier and simpler.
- the essential function of the second auxiliary roll is to support the edge of the material and it only contacts the edge corner of the material, formability and product quality will not adversely been affected even if they are worn. For such a case, it is not required to exchange and polish these auxiliary rolls.
- auxiliary roll not only controls the wear phenomenon of the forming roll, but also exhibits a great effect to prevent the so-called edge wave of the material caused by the excessive edge stretch during the forming process.
- edge stretch is the most remarkable at the breakdown forming area.
- edge portion when the material 1 is entering the roll gap, the edge portion winds around the surface of lower roll 40 and rises. Since, during this short period of time, the S-shaped spatial locus 42 created by the edge portion is much longer than nearly-liner loci created by other portions, a large amount of edge stretch will take place. Moreover, due to such an edge stretch, downward-warp will occur on the longitudinal direction of the material after the material passes through the roll gap, causing the same rising problem at the subsequent stand.
- the auxiliary roll since the auxiliary roll does not contribute directly to the forming of the products, it is not required to design the roll caliber with respect to the products' dimension as done for the forming rolls.
- the flat rolls can be used if the edge corner of the material can be supported at the desired position.
- the auxiliary roll requires only a simple supporting device being mounted before and after the forming stand, so that the exclusive stand just for the auxiliary roll is not needed.
- the shorter the distance (pitch) from the supporting point of the material's edge corner to center of the lower roll the larger various effects obtained from the auxiliary rolls, the shorter distance (pitch) can be obtained if the auxiliary roll is placed at the same stand as the lower roll.
- the short pitch as seen in Figure 7B, it is extremely effective to decline the axis of the auxiliary roll toward the center of the lower roll along the longitudinal direction.
- a rotation-type pair of left and right upper rolls which is changeable to the contacting direction against the material and a pair of left and right lower roll together with the central roll having a narrow width are mounted.
- the pinch-point is set at the boundary area between the target forming zone along the material's width direction which is ready to form at the BD1 stand and the bending non-sensitive material's edge portion.
- Such a pinch-point possesses the same mechanism and function as described in Figure 4A to perform a certain edge-bending operation.
- the roll stand BD2 seen in Figure 8B consists of a rotation-type pair of left and right upper rolls, a wide lower central roll, and a pair of horizontal rolls to support the edge potion of the material which was previously formed at the BD1 roll stand. Between the upper roll and shoulder portion of the central roll, the pinch-point is provided at the boundary area between the target forming zone which is planned to be formed at the stand BD2 and the un-formed zone of the material's central portion, to exhibit the same mechanism and function as described in Figure 4B to perform the bending operation.
- the roll stand BD3 has the same mechanism and function as the previous roll stand BD2 does, and is used to bend a target forming zone which is closer to the center of the material.
- the portion of material at the outer side of the target forming zone, which has already been formed at previous roll stands BD1 and BD2 is supported by the horizontal roll with an involute caliber, so that the bending-back of the formed portion at the outer side of the target forming zone is prevented.
- the edge-bend forming method without exchanging rolls can be realized at the breakdown forming portion, so that formability is extremely improved and the common-utilization of rolls in a range of about three-fold in terms of diameter ratio can be achieved.
- the pipe mill as seen in Figure 7 A, comprises of roll stands BD1, BD2, BD3 at the breakdown forming portion, roll stand RB of the reverse forming portion, cluster roll stands C1,C2,C3, and roll stands FP1,FP2 in the fin-pass forming portion.
- a rotation-type pair of left and right upper rolls which are changeable in the contacting direction with the material, a narrow central roll, and a pair of left and right lower rolls with involute calibers are mounted.
- the pinch-point is provided at the boundary area between the target forming zone which is ready to be formed at the roll stand BD1 and the bending non-sensitive zone of the material's edge portion.
- Such a pinch-point possesses the same mechanism and function as described in the Figure 4A to perform the edge-bending operation.
- the target forming zone is not in contact with the roll caliber of the lower roll except its boundary at the pinch-point (not seen in Figure).
- a rotation-type left and right pair of upper rolls and a pair of left and right lower Tolls are provided.
- the pinch-point is provided at the boundary area between the target forming zone which is ready to be formed at the roll stand BD2 and the previously-formed zone formed at the roll stand BD1.
- Such a pinch-point exhibits same mechanism and function as described in Figure 4B.
- the target forming zone is not in contact with the roll caliber of the lower roll except its boundary at the pinch-point.
- the material's edge portion which was previously formed at the roll stand BD1 is in contact and supported with the involute caliber of the lower roll to maintain the expected formability.
- the roll stand BD3 as seen in Figure 6C, possesses the same mechanism and function as previous roll stand BD2 does. At this stand, a target forming zone which is closer to the central of the material is bent. The material's edge portion which was already formed by previous roll stands BD1 and BD2 is supported along the involute caliber of the lower roll, so that the bending-back of the formed portion is avoided.
- the edge-bend method without exchanging rolls can be realized at the breakdown forming portion, so that formability is extremely improved and the common-use of rolls in a range of about 2.5-fold in terms of diameter ratio can be achieved.
- the auxiliary rolls are provided with an attachable manner before and after the breakdown forming portion.
- the edge stretch of the steel plate was measured at each stand at the breakdown forming portion.
- Table 1 shows the results for three cases; namely they include (1) without any auxiliary roll, (2) auxiliary rolls before and after the roll stand BD1, and (3) auxiliary rolls before and after roll stands BD1 and BD2.
- Table 2 shows the results of effects of the auxiliary roll on the thrust and forming load at the roll stand BD2. From results presented in Table 2, it is obvious that the thrust on the BD2 roll stand and forming load acting on the lower roll are clearly different between the case when the auxiliary roll is not provided before and after the roll stand BD1 and the case when the auxiliary roll is provided before and after the roll stand BD1.
- the pinch-point formed by the upper and lower rolls is set at the boundary area between the target forming zone along the material's width direction and previously-formed zone or un-formed zone.
- the target forming zone is wound around a certain caliber of the upper roll being positioned at the bend-inner side, and bend-formed in such a manner that the lower roll is in almost no-contact condition with the target forming zone.
- the concave roll does not contribute directly to control the curvature distribution of the target forming zone.
- the target forming zone is basically constrained only by the convex roll, so that the excess deformation hardly takes place and the occurrence of the superfluous deformation strain can be prevented.
- the maximum surface pressure is generated on the pinch-point. Since the roll diameter corresponding to this pinch-point is used as a roll reference diameter and the position of the pinch-point is clearly identified and not changed, the driving force among each roll stand can be synchronized easy.
- the contacting condition between the material and rolls is stable regardless of variations in wall thickness of the material, so that the twist phenomena is not induced.
- the roll forming method of the present invention since it is not necessary that both concave and convex rolls are rolls with exclusive roll caliber corresponding to the product to be formed, the common-utilization rolls is easy to realize. Also, the forming function and operativity of mill can be greatly improved by introducing it to the breakdown forming portion.
- the auxiliary roll at the area in vicinity of upper stream and lower stream of the lower roll of the breakdown forming stand to support the edge of the material to the pre-set height, the forming load and surface pressure acting on the lower roll can be reduced. As a result, the local wear on the roll can be reduced. Also forming defects such as the edge wave caused by the localized stretching of the edge portion can be eliminated.
Description
with said method the common-utilization of rolls can be realized regardless of the wide variation in dimensions of materials to be formed. The present invention, more specially, relates directly to a novel roll forming method for welded steel pipes by setting the pinch-point (which is a specified location for holding the material to be formed with upper and lower rolls) at the boundary area between the target forming zone and formed or un-formed zone along the width direction of the material, and by making said target forming zone in contact with the pre-determined caliber of the upper roll which is placed on the bend-inner side but not making the bend-outer side of the target forming zone in contact with the lower roll to perform the bend forming process, so that the bend-formability can be remarkably improved, roll-flaws or roll-scratches can be avoided, and accordingly the common-utilization of rolls can be realized at the break-down forming portion for the edge-bend method.
without auxiliary roll | auxiliary roll before & after BD1 | auxiliary roll before & after BD1,2 | |
BD1 stand | 2.25% | 1.1% | 1.1% |
BD2 stand | 1.8% | 0.48% | 0.25% |
BD3 stand | 0.5% | 0.48% | 0.48% |
when the auxiliary roll is not provided before and after BD1 stand | when the auxiliary roll is provided before and after BD1 stand | ||
forming load acting on the lower roll of BD2 stand | thrust at BD2 stand | forming load acting on the lower roll of BD2 stand | thrust at BD2 stand |
6530kg | -10kg | 2750kg | 180kg |
Claims (10)
- A roll-forming method for forming a pipe from a strip (1) having a bend-inner side and a bend-outer side and a target forming zone (1b, 1c), the roll-fonning taking place between at least one pair of an upper roll and a lower roll, the method comprising the steps of:i) forming a pinch point (pp) by applying an upper roll (12, 21, 31, 32, 41, 52) to the bend-inner side of the strip (1) and applying the lower roll (10, 11, 20, 30, 50, 51) to the bend-outer side of the strip (1);ii) setting the pinch point (pp) at a boundary between the target-forming zone and an adjacent portion (1a, 1d) of the strip (1); andiii) winding the target zone (1b, 1c) of the strip (1) around a roll surface of the upper roll (12, 21, 31, 32, 52) on the bend-inner side without being constrained from the bend-outer side by the lower roll (10, 11, 20, 30, 50, 51).
- The roll forming method as cited in claim 1, wherein side rolls (33, 34) are in contact with the previously-formed zones of the material from the bend-outer side to prevent bending-back phenomena.
- The roll forming method cited in claim 1 or claim 2, wherein the central portion of the material along its width direction is pushed from the bend-outside through the contacting roll to form a W shape of cross-section.
- The roll forming method cited in any one of claims 1 to 3, wherein a roll calibre is shaped with a plurality of arcs.
- The roll forming method cited in claim 4 wherein an involute is employed as the roll calibre.
- A roll forming method of welded steel pipe wherein the forming method cited in any one of the preceding claims is employed in the breakdown forming portion.
- The roll forming method cited in any one of claims 1 to 6, wherein an auxiliary roll (53,54) is mounted which is in contact with the edge of the material and at a vicinity of the upper roll (12, 21, 31, 32, 52) and lower roll (10, 11, 20, 30, 50, 51) in forming stands, and the auxiliary roll (53, 54) is used to support the height of the edge of the material to a certain height previously arranged during the roll forming.
- The roll-forming method of claim 2 comprising the use of roll forming equipment which comprises one-piece or separate-type of lower roll (30), a pair of upper rolls (31, 32) in the material's width direction, and a pair of side rolls (33, 34) being provided in the horizontal way at the edge portion of the material.
- The roll-forming method of claim 2 comprising the use of roll forming equipment which comprises one-piece or separate-type of lower roll (30), a pair of upper rolls (31, 32) in the material's width direction, and a plurality of rolls being arranged in the longitudinal direction to contact the edge portion of the material from the outer side.
- Roll forming equipment for the performance of a roll forming method for forming a pipe from a strip (1) having a bend-inner side and a bend-outer side and a target forming zone (1b, 1c), the roll forming equipment comprising:(a) one piece or separate type of lower roll (30);(b) at least one pair of upper rolls (31, 32) in the material's width direction; and(c) a pair of side rolls (33, 34) being provided in the horizontal way at the edge portion of the material, whereby the axial direction of the rotating axes of upper (31, 32) and lower rolls (30) can be changed independently in order to support the material being formed,i) forming a pinch point (pp) by applying the upper roll (31, 32) to the bend-inner side of the strip (1);ii) setting the pinch point (pp) at a boundary between the target-forming zone (1b, 1c) and an adjacent portion (1a, 1d) of the strip (1); andiii) winding the target-forming zone (1b, 1c) of the strip (1) around a roll surface of the upper roll (31, 32) on the bend-inner side without being constrained from the bend-outer side by the lower roll (30).
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP09757599A JP4906986B2 (en) | 1999-04-05 | 1999-04-05 | Roll forming method |
JP11097577A JP2000288634A (en) | 1999-04-05 | 1999-04-05 | Roll forming method and roll forming stand |
JP9757599 | 1999-04-05 | ||
JP9757799 | 1999-04-05 | ||
PCT/JP1999/002186 WO2000059653A1 (en) | 1999-04-05 | 1999-04-23 | Method for roll forming steel pipes, and equipment for same |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1169149A1 EP1169149A1 (en) | 2002-01-09 |
EP1169149B1 true EP1169149B1 (en) | 2005-07-27 |
Family
ID=26438740
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99917140A Expired - Lifetime EP1169149B1 (en) | 1999-04-05 | 1999-04-23 | Method for roll forming steel pipes, and equipment for same |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1169149B1 (en) |
AT (1) | ATE300366T1 (en) |
CA (1) | CA2270097C (en) |
DE (1) | DE69926406T2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5470841B2 (en) | 2008-12-26 | 2014-04-16 | 新日鐵住金株式会社 | Roll bending apparatus for steel plate for cylinder pipe and roll bending method for steel plate for cylinder pipe using the same |
DE102020215091A1 (en) | 2020-12-01 | 2022-06-02 | Sms Group Gmbh | Process for preforming sheet metal and computer program and device for carrying out the process |
-
1999
- 1999-04-23 AT AT99917140T patent/ATE300366T1/en active
- 1999-04-23 EP EP99917140A patent/EP1169149B1/en not_active Expired - Lifetime
- 1999-04-23 DE DE69926406T patent/DE69926406T2/en not_active Expired - Lifetime
- 1999-04-23 CA CA 2270097 patent/CA2270097C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
DE69926406T2 (en) | 2006-05-24 |
EP1169149A1 (en) | 2002-01-09 |
ATE300366T1 (en) | 2005-08-15 |
CA2270097C (en) | 2006-01-24 |
CA2270097A1 (en) | 2000-10-05 |
DE69926406D1 (en) | 2005-09-01 |
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