JPH09192749A - Break down roll device in tube mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the circularity of a forming material and the thrust to the forming material by making break down upper and lower rolls into the combined rolls of assembling a center roll fitted in a single rotary driving shaft and a pair of split rolls inserting the above between them in the time of producing an electric resistance welded tube. SOLUTION: The composition of an upper roll 1 in a roll device is made in combined rolls assembled with a center roll 2 fitted and attached firmly to a single upper roll rotary driving shaft 7, and a pair of split rolls 3 arranged at the right and left symmetrical positions inserting the above between them. The cross-section profile of the forming working face of this roll is made of a circular-arc with a definite curvature of radius, a right and left symmetrical curve line, or an involute based on a polygon, and a part having a curve face specified to the curve at the position having the uniform gap with the lower roll. Further, the split roll 3 is made freely sliding on the rotary driving shaft 3, and it is driven eccentrically. More, a lower roll 4 is composed of a pair of split rolls 6 arranged on the right and left symmetrically with inserting the intermediate roll 5 between them.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the manufacture of ERW steel pipe,
In particular, the present invention relates to a forming roll device for forming a central portion of a steel strip and an intermediate portion between the central portion and an end portion of the steel strip in a breakdown step in manufacturing a steel pipe by continuous roll forming.

[0002]

2. Description of the Related Art Generally, an electric resistance welded steel pipe is manufactured by performing an initial forming in a breakdown step with an optimum forming roll according to a required diameter and a wall thickness, and then performing a fin pass step and a shape correcting step. In particular, the breakdown step that is initially performed is the most important in the series of steps in the production of ERW steel pipe. This breakdown step is usually a stage of initial forming in a multi-stage mill, in which first bending of the strip steel (usually called edge forming) is performed, and then bending of the central portion of the strip is performed. Forming and bending of the central portion of the steel strip are performed by the upper and lower rolls or a combination of the upper and lower rolls and the side rolls. However, in this method, it is not possible to universally form from large-sized steel pipes to small-sized steel pipes, and the optimum rolls must be recombined for each steel pipe size, so the rolls for each steel pipe size must be combined. There are problems that the set is necessary, the time for roll recombination is necessary, the cost is not paid, and the work is complicated. In addition to these problems, the roundness of the steel pipe is insufficient because the end bending and the semi-circular forming of the steel strip are performed at the initial stage of forming, which is difficult to form. This is because although there are many springbacks after passing the roll due to insufficient bending of the strip edge at the beginning of forming, the number of forming steps is increased from the viewpoint of manufacturing cost and the next strip forming is performed without completely bending the strip edge. Since the central part of the steel strip is formed in the area, this method is to correct the forming defects in the initial and middle stages at a stretch in the fin pass forming process, which is the next process. There is a problem that the roundness cannot be secured.

Therefore, as disclosed in Japanese Patent Publication No. 3-12975-12977 in order to solve the above-mentioned problems, the present applicant forms both ends of a strip steel for a roll used in a breakdown process. A polygon that is preset to include each curved surface of the steel strip end in the roll flower of each steel pipe so that part or all of the cross-sectional curve of the roll surface of the forming roll can be formed into a steel pipe with various planned outer diameters We have developed a dual-purpose forming roll whose cross-sectional shape is based on the expansion curve.

The above-mentioned problems have been solved by the pipe mill having the dual-purpose forming roll developed here. However, in order to use each roll as a common function regardless of the molding stage as described above, the main focus is on making each roll shape a cross-sectional shape of an extension curve based on a polygon. As a result, during the forming from the steel strip to the semi-circular shape in the breakdown process, rolling phenomenon occurs during the forming of stainless steel and hard materials, and precise and efficient forming cannot be performed at each forming stage. There is a problem.

In addition, when forming a large-diameter to small-diameter steel pipe, the caliber design of this combined roll is
It becomes a roll caliber by the curvature extracted from the maximum size and the minimum size of the basic roll flower of the forming target, and the pinch point of the strip steel to be formed by the lower roll and the upper roll is point contact or short line contact at the center through the forming material. Therefore, even if the central portion can be formed, the intermediate portion between the central portion and the end portion already formed at the early stage of breakdown cannot be formed. That is, since the curvature of the lower roll is usually always constant, the central part is thinned locally when a molding load is applied only by the upper roll, which causes a kind of buckling phenomenon and the central part is easily bent and tends to have a vertical oval tendency. Becomes stronger. If the side rolls in the next step are continuously used to reduce the diameter as they are, there is a problem that the formed steel pipe becomes elliptical or bent from the center to cause the product yield to be extremely deteriorated. On the other hand, the occurrence of such a phenomenon was a heavy load in the fin pass molding in the next step.

[0006]

Particularly, in the final forming step of the breakdown step, it is necessary to increase the roundness in order to reduce the load in the fin pass forming of the next step as much as possible. Therefore, in view of the above problems, the present inventor minimizes the load in the fin pass forming which is the next step,
At the same time, satisfying the design of the upper forming roll to avoid the wall thinning action, bending, or elliptical shape in the breakdown process to ensure the roundness of the steel pipe, and at the same time to provide the propulsive force at the time of roll forming, and A structure that can absorb the forming load applied to the forming roll shaft without any problems, and we have developed a dual-purpose roll device for the breakdown path in the pipe mill that combines these in a single stand.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a roll device for a combination of breakdown paths in a completely new pipe mill that solves the above problems and satisfies the needs of the electric resistance welded steel pipe manufacturing industry. The gist of the present invention is as follows. In the roll forming machine in the breakdown process of the roll forming machine having the upper roll and the lower roll,
The upper roll is fitted to a single upper roll rotation drive shaft, and is a composite roll that is a combination of a fixed center roll and a pair of upper split rolls arranged at symmetrical positions with the center roll interposed therebetween. Whether the cross-sectional profile of the forming working surface of the composite roll is a circular arc with a constant curvature, an arbitrary smooth symmetrical curve, or a curvature having an expansion curve based on a polygon, Specify the curve at the position that has a uniform gap with the lower roll, divide this specified curve into multiple pieces, and select a plurality of partial curves that are not adjacent to each other and parallel the partial curve at the closest position. The upper split roll has a curved surface constituted by cross-section curves that are moved to connect and connect the respective end portions, and further, the upper split roll has an arbitrary position on the upper roll rotation drive shaft. Thereby slidable, a roll apparatus breakdown in Paipumiru configured to be supported by the eccentric shaft such that eccentric rotation. Further, in addition to the above configuration, the lower roll is composed of a lower intermediate roll and a pair of lower split rolls which are arranged at symmetrical positions with the lower intermediate roll interposed therebetween.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A breakdown roll device in a pipe mill according to the present invention has a structure in which an upper roll is fitted to a single rotary drive shaft, and the center roll is fixed to the center roll at symmetrical positions. It is a composite roll that combines a pair of upper split rolls arranged,
The center roll rotates synchronously with the lower intermediate roll of the lower roll to form the central portion of the steel strip to be formed, and the upper split roll slides in the left-right direction around the center roll by a separately-described expansion / contraction mechanism to cause a pair of lower splits. It engages with the roll to form the intermediate portion of the steel strip to be formed. Further, since the upper split roll is configured to eccentrically rotate about the rotary drive shaft, the upper split roll is formed in the intermediate portion of the band-formed steel strip in a shape state closest to the single roll at the maximum eccentric portion. It is possible to form the central part of the strip to be formed for small diameter sizes, and as the eccentricity decreases, the upper split roll position becomes farther from the single roll shape, and the intermediate part of the strip to be formed for large diameter sizes can be formed. It will be possible.

The expansion / contraction adjustment of the upper split roll is as follows.
It is similar to the conventional split roll driving method, and is related to a rack provided on the outer circumference of a rotary ring concentrically arranged with the rotary drive shaft by a servomotor different from the motor that drives the rotary drive shaft fixed to the frame. The worm gear is driven to expand and contract. As described above, by using the breakdown roll device according to the present invention, the central portion and the intermediate portion of the steel strip to be formed for small diameter to large diameter can be formed all at once, and extremely efficient work can be performed. At the same time, local thinning action, bending, or elliptical shape, which were problems in the past, are avoided, and the forming load at the time of fin pass forming in the next process can be significantly reduced and the number of fin pass stands can be minimized. be able to. Further, as described above, it is possible to perform semi-circular forming by pinching the central portion of the steel strip to be formed with the center roll, so that even if the diameter ratio to the hard material or the plate thickness becomes large, sufficient breakdown forming can be performed. it can.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front view showing a breakdown combined roll device according to the present invention, and FIG. 2 is a side view of FIG. 1, the structure of which will be described below. In FIG. 1, a breakdown roll device according to the present invention is configured such that an upper roll 1 includes a center roll 2 located at a central portion of the upper roll 1 and a pair of upper splits arranged in symmetrical positions with the center roll 2 interposed therebetween. It is a composite roll formed by combining the roll 3 with the lower roll 4 and the lower intermediate roll 5.
And a forming roll group consisting of lower split rolls 6 which are arranged symmetrically with the lower intermediate roll 5 interposed therebetween. An upper roll rotation drive shaft 7 and a lower roll rotation drive shaft 8 that rotationally drive these forming roll groups are supported by a frame 9 that supports the entire breakdown mill at both ends of these shafts, and the vertical rotation is performed outside the frame 9. A drive motor (not shown) including a reduction gear that rotationally drives the drive shaft is attached. In the above, the center roll 2
The lower intermediate roll 5 and the lower intermediate roll 5 are fitted and fixed to intermediate positions of the upper roll rotary drive shaft 7 and the lower roll rotary drive shaft 8, respectively, and are integrally driven in rotation to pinch and form the strip to be formed from the upper and lower positions. Propulsion is applied and molding proceeds.

On the other hand, the pair of upper split rolls 3 constituting the upper roll 1 and the pair of lower split rolls 6 constituting the lower roll 4 are not driven and are rotated by the forming propulsion force of the steel strip to be formed. While performing the molding operation. In FIG. 1, there are four features of the present invention. They are 1) upper roll configuration, 2) cross-sectional profile of upper roll forming surface, 3) upper roll eccentric mechanism, and 4) lower roll configuration. First, the configuration of the upper roll 1 in the dual-purpose roll device for breakdown of the present invention is such that the center roll 2 fitted and fixed to the single upper roll rotation drive shaft 7 and the left and right symmetrical positions with the center roll 2 sandwiched therebetween. This is a composite roll formed by combining a pair of upper split rolls 3 arranged. Moreover, the cross-sectional profile of the forming operation surface of each of the composite rolls may be an arc having a constant curvature as shown in FIG. 3 (a), or may be a symmetrical symmetrical arbitrary curve, or FIG.
A curved surface having an expansion curve based on a polygon as shown in (b) or a curve at a position having a uniform gap with a lower roll as shown in FIG. Divide the specified curve into a plurality of parts, select a plurality of partial curves that are not adjacent to each other, move the nearest partial curve in parallel, and connect the ends to each other to form a sectional curve. It has a curved surface configured.

In the above-mentioned cross-sectional profile of the composite roll, the arc having a constant curvature is a curved surface represented by a normal concentric circle, and the left-right symmetrical smooth curve is the above-mentioned Japanese Patent Publication No. 3-. It is a curved surface having a cross-sectional shape of an expansion curve based on a polygon preset so as to include each curved surface in the roll flower of each steel pipe disclosed in No. 12975-12977, and further a lower roll and a uniform gap. Specify the curve at the position you have, divide this specified curve into a plurality of parts, select a plurality of partial curves that are not adjacent to each other, move the closest partial curve in parallel, and end each It is a cross-sectional profile designed by the discontinuous curved surface comprised by the cross-section curve which connected and connected each other.

In the above-described composite roll having the above-described structure, the upper split roll 3 has a sleeve 10 fitted on the outer peripheral portion of the upper roll rotation drive shaft 7, and a pair of upper split rolls via a bearing mechanism 11. A rotary bearing 12 is fitted to allow the upper split roll 3 to rotate freely. Further, since these upper split rolls 3 are fitted to the outer peripheral portion of the upper roll rotation drive shaft 7, they can be freely slid in the left-right (width) direction by applying an external force.

What is important here is that the upper roll rotary bearing 12 is a donut-shaped eccentric bearing having an eccentric opening difference. Moreover, these upper split rolls 3 are provided with a pair of expansion / contraction mechanisms 13 in the left-right direction centering on the center roll 2 similar to the expansion / contraction action of a normal split roll. These expansion / contraction mechanisms 13 are fitted to a pair of cylindrical outer rotating cylinders 14, one end of which is fixed to the end portion of the upper roll rotating bearing 12, and the inner peripheral portions of these outer rotating cylinders 14 and have screw-shaped surfaces. A pair of concentric rotary inner cylinders 16 in which the rack 15 is carved are rotatably attached to both ends of the upper roll rotary drive shaft 7 via bearings.

Further, a pinion 17 having a worm gear meshing with the rack 15 is provided on the outer peripheral upper portion of the rotating outer cylinder 14, and a pair of servo motors 18 for rotationally driving the pinion are installed. When the upper split roll 3 is moved in the left-right direction (width direction), the servo motor 18 is rotationally driven, and the driving force is transmitted to the pinion 17, whereby the rotary outer cylinder 14 rotates and the inner rotary cylinder 16 rotates. It is achieved by moving forward and backward around.

Further, the lower split roll 6 of the lower roll 4
The expansion and contraction mechanism 19 provided at both ends of the lower split roll 6 is configured in exactly the same manner as the expansion and contraction mechanism of the upper split roll, and the expansion and contraction of the upper split roll 6 and the expansion and contraction of the lower split roll 6 are synchronized. Done. In this way, by the expansion / contraction mechanism described above, the upper split roll 3
Can move forward and backward around the center roll 2, so that the center roll 2 and the lower intermediate roll 5 form the central portion of the strip to be formed, and the intermediate portion of the strip to be formed is formed. The forming is performed by the upper split roll 3 and the lower split roll 6.

The upper split roll 3 and the lower split roll 6 are used to form the intermediate portion of the steel strip to be formed, because the upper split roll 3 is constructed so as to eccentrically rotate about the rotary drive shaft, so that the maximum eccentricity is the greatest. In a state similar to a single roll, it is possible to form a steel strip intermediate portion for a small diameter size, and as the eccentricity decreases, the position of the upper split roll 3 becomes greater as the position of the upper split roll increases from the single roll. It is possible to form the middle part of steel. With such a configuration, by using the breakdown roll device according to the present invention, it is possible to form the central portion and the intermediate portion of the steel strip to be formed for small diameter to large diameter at one time, which is extremely efficient. Can be performed at the same time, local thinning action, bending, or elliptical shape, which were the conventional problems, can be avoided, and the forming load at the time of fin pass forming in the next process can be greatly reduced and the fin pass stand The number can be kept to a minimum. Further, as described above, it is possible to perform semi-circular forming by pinching the central portion of the band steel to be formed with the center roll, so that even if the diameter of the hard material or the plate thickness increases, the breakdown forming can be sufficiently performed. it can.

[0018]

As described above, in the roll device for breakdown in the pipe mill according to the present invention, conventionally, the propulsive force applied to the strip to be formed depends on the fin path and the sizing. Since the center roll in the breakdown path can sufficiently pinch the steel strip to be formed, the propulsive force can be increased, and the breakdown path can be formed independently from the large diameter steel pipe to the small diameter steel pipe including the intermediate portion forming. Since it can be molded into a large number, the operability is remarkably superior to the conventional method, and the product yield can be further improved.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a breakdown roll device in a pipe mill according to the present invention.

FIG. 2 is a side view of a breakdown roll device in a pipe mill according to the present invention.

FIG. 3 shows various sectional profiles of the split roll working surface in FIG. 1, where (a) is an arc with a constant curvature, and (b) is a curved surface with an arbitrary smooth curved line that is symmetrical. , (C) are views respectively showing a curved surface of an intermittent curve cut out from a circular arc having a constant curvature by a special method.

[Explanation of symbols]

 1 ... Top roll 2 ... Center roll 3 ... Top split roll 4 ... Bottom roll 5 ... Bottom intermediate roll 6 ... Bottom split roll 7 ... Top roll rotation drive shaft 8 ... Bottom roll rotation drive shaft 9 ... Frame 10 ... Sleeve 11 ... Bearing Mechanism 12 ... Rotating bearing 13 ... Upper split roll expansion / contraction mechanism 14 ... Rotation outer cylinder 15 ... Rack 16 ... Rotation inner cylinder 17 ... Pinion 18 ... Servo motor 19 ... Lower split roll expansion / contraction mechanism

Claims (2)

[Claims] 1. In a roll forming machine in a breakdown step of a roll forming machine having an upper roll and a lower roll, a center roll having the structure of the upper roll fitted and fixed to a single upper roll rotation drive shaft, and the center roll. A composite roll that is a combination of a pair of upper split rolls arranged in symmetrical positions across the roll, and the cross-sectional profile of the molding operation surface of the composite roll is an arc of constant curvature, or any symmetrical symmetrical smooth surface. A curve, or a curvature with an expansion curve based on a polygon, or specify a curve at a position with a lower roll and a uniform gap, and divide this specified curve into multiple Then, select a plurality of partial curves that are not adjacent to each other, move the nearest partial curves in parallel, and connect the ends to each other and connect them to each other. The upper split roll is configured to be slidable to an arbitrary position on the upper roll rotation drive shaft, and is supported by an eccentric shaft that rotates eccentrically. A roll device for breakdown in a pipe mill. 2. The lower roll is composed of a lower intermediate roll and a pair of lower split rolls arranged in symmetrical positions with the lower intermediate roll interposed therebetween.
Rolling device for breakdown in the described pipe mill.