JPS598452B2 - Roll forming method for cylindrical tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roll-forming method for tubes, and more particularly to a roll-forming method for producing cylindrical tubes from sheet metal.

For example, in manufacturing an electric resistance welded tube, a metal plate is formed into a cylindrical shape using a forming roll, and then the abutting portions in the longitudinal direction of the tube are welded to obtain the tube.

However, as a conventional roll forming method, the methods shown in FIGS. 1 to 3 are widely adopted. That is, in the rough forming process shown in Fig. 1, a metal plate is passed through a hole formed by horizontal upper and lower rolls each having a convex curved surface and a concave curved surface, and the metal plate is formed into a U-shape while being restrained by the upper and lower rolls. do. Next, in the intermediate forming step shown in FIG. 2, the U-shaped metal plate is formed into a circular shape by a pair of vertical rolls having concave curved surfaces designed to come into contact with the entire outer surface of the metal plate. Furthermore, in the final forming process, the third
As shown in the figure, shaping is carried out while applying widthwise compression using a pair of fin rolls designed to contact almost the entire outer surface of the circular blank tube while restraining the ends thereof. However, the conventional roll forming method described above has the following problems.

(1) The range of roll sizes that can be used is extremely narrow, and each roll is required to match the pipe diameter. As a result, a large number of rolls must be prepared, which increases roll cost.

(2) It takes time and effort to change the rolls when changing the pipe diameter, resulting in poor operating efficiency and extremely low productivity.

(3) Since the roll and the metal plate are in full contact with each other throughout the forming process, slipping occurs due to the difference in peripheral speed between the roll and the metal plate, resulting in large energy loss during forming, and scratches, etc. Occurrence can be seen. The present invention improves the above-mentioned problems of the prior art, can handle the manufacture of cylindrical tubes of various sizes with a small number of rolls, greatly reduces the degree of friction between the material to be formed and the rolls, and improves productivity. The purpose of the present invention is to provide a pipe roll forming method that can be dramatically improved. To achieve these objectives, the roll forming method of the present invention involves the following steps when forming a plate-like object to produce a cylindrical tube:
a pair of rolls that are symmetrically displaceable and fixable with respect to an arbitrary diameter in a plane perpendicular to the tube axis direction, and adjacent to each of the pair of rolls, together with the outer periphery of the pair of rolls, A forming pass is provided by providing an auxiliary roll that forms a concave corner with respect to the axis, and the side edge of the plate-like object passing through the pass is restrained by the concave corner, thereby forming the plate-like object. It is characterized by forming a plate-like object into a cylindrical tube while applying bending deformation. The details of the roll forming method of the present invention will be explained below.

When manufacturing a cylindrical tube according to the present invention, a metal plate-like body, such as a metal strip (steel strip), cut plate, etc., is used as the material.
These raw materials are not supplied as they are to the molding pass of the present invention, but are usually supplied to the molding pass of the present invention using a push roll device, which will be described later. That is,
During roll forming, a push roll device is driven to forcibly move the material, and its tip is pushed into a forming path formed by non-driven forming rolls. As the pushing roll device, flat upper and lower rolls as shown in Fig. 5 may be used, or upper and lower rolls having uneven surfaces of a single curvature as shown in Fig. 6 may be used to perform the pushing. Initial molding may also be performed at the same time.

Furthermore, as shown in FIG. 7, pressing and forming may be performed using upper and lower rolls having a flat central portion and curved ends. Which of the push rolls to adopt from these Figures 5 to 7 can be selected appropriately by considering the thickness, width, material, etc. of the material to be formed. It is desirable to use the one shown in FIG. 6 or 7, which has a pressing and forming function. In the present invention, a plate-shaped body charged by such a push roll device is passed through a forming path constituted by unique forming rolls to be formed into a desired cylindrical tube.

A specific example of this forming roll is shown in FIG. FIG. 8a shows a pair of upright truncated conical vertical rolls 5 and the pair of vertical rolls 5.
A specific example of a forming roll constituted by a pair of horizontal auxiliary rolls 6 that are in contact with the upper surfaces of each of the rollers will be shown.

The vertical roll 5 has a rotation axis perpendicular to the tube axis direction, and can be symmetrically displaced with respect to any specific diameter in a plane perpendicular to the tube axis direction, and can be fixed at a predetermined position.
Therefore, the pair of vertical rolls 5 are movable vertically and horizontally in accordance with the pipe diameter, and are always set at optimal positions. Further, in the forming roll used in the present invention, the vertical roll 5 and the auxiliary roll 6 form concave corner portions for restraining both side edges of the plate-like object 1 to be formed. The concave corner portion is formed by the outer peripheral portion of the vertical roll 5 and the partial outer peripheral portion of the auxiliary roll 6, but this concave corner portion is formed by two mutually independent vertical rolls 5 and the auxiliary roll 6. A recess formed by the surface of a plate-shaped object formed by this recess, which causes bending deformation by restraining the side edge of the side end surface of a plate-like object, a part thereof, or a part of the surface in the vicinity thereof. , the concave corner shape refers to the shape of a portion of the roll body that makes this possible. Furthermore, the auxiliary roll 6 is freely displaceable vertically and horizontally, independently of the vertical roll 5, as shown in the figure. In FIG. 8b, a horizontal roll 7 is installed in addition to the vertical roll 5 and the auxiliary roll 6 to horizontally circumscribe the plate-shaped object 1 to be bent. It is possible to avoid buckling due to deformation and improve the stability of the pass line.

As described above, in the present invention, by combining the vertical roll 5 and the auxiliary roll 6, each having an independent rotation axis, a concave corner portion is formed to regulate the side edge of the plate-shaped object 1 to be formed. However, this brings about the following advantages.

That is, even if the vertical roll 5 and the auxiliary roll 6 are formed integrally, a similar concave corner portion can be obtained, but when forming a plate-like object, the edge portion particularly comes into contact with the inclined surface on the side of the auxiliary roll. Local wear in that area becomes noticeable, and if the roll is a one-piece roll, it is necessary to replace the entire roll. However, the split roll type used in the present invention is extremely advantageous in terms of cost because it is only necessary to replace the roll that is more worn.
In addition, if the contact with the edge portion of the plate-like object is not uniform, it is only necessary to change the optimal auxiliary roll with a different inclination angle. Moreover, separating the vertical roll and the auxiliary roll means adjusting the inclination angle and the outer circumferential surface, respectively. By preparing several molds with different shapes, many combination patterns can be created, allowing fine adjustment of molding conditions. Furthermore, in the case of a forming roll type in which a vertical roll and an auxiliary roll are integrally combined, the circumferential speed is different in the sloped part, and there are places where slip occurs between the roll and the plate. Since the forming rolls used each have independent rotation axes, the vertical rolls and auxiliary rolls rotate at optimal circumferential speeds depending on the plate-shaped objects in contact with them, minimizing slips. As a result, inconveniences caused by slips can be reduced as much as possible.

In the forming rolls of the present invention, the gap and height position of the rolls are adjusted as appropriate in accordance with the change in pipe size or the forming stage, and the roll displacement mechanism includes vertical movement and horizontal movement (of a pair of rolls). Any mechanism that enables opening/closing movement) may be used, but
It is desirable to be able to quickly respond to changes in the molded shape and size of plate-like objects, and to be able to securely fix them in any position.

Next, FIG. 4 shows a forming apparatus array for carrying out the roll forming method of the present invention, which is constructed using the above-described forming rolls.

In Fig. 4, numeral 1 is a steel strip having a width necessary for the pipe-making diameter, which is a metal plate material used as the raw material for the cylindrical pipe, and numeral 2 is a finpass roll, which is a finish forming stand, at the tip of the plate material 1. For example, any one of the above-mentioned FIGS. 5, 6, and 7 is used as a single-drive pushing roll for running up to a maximum of 100 degrees.

Reference numeral 3 denotes a forming roll constructed of, for example, four stands, and this forming roll 3 is constructed of an appropriate type selected from those shown in FIG. 8 above.

Reference numeral 4 denotes a fin pass roll for final forming the cylindrical tube formed by the forming roll 3, and has the same roll shape and drive device as conventionally known rolls.

When manufacturing cylindrical pipes according to the present invention, generally after the tip of the material is pushed into the fin pass roll, the pushing roll is allowed to float by leaving a sufficient gap between the upper and lower rolls, and thereafter the material is moved only by the fin pass roll. It is desirable to run the material and finish forming it to prevent asymmetrical forming and twisting of the material.

The positions of the rolls and the state of contact between the plate and the rolls when manufacturing cylindrical pipes of different diameters using the above-described forming path of the present invention are shown in FIGS. 9A to 9E. In the figure, the left half shows the case in which the maximum size of a plate-like object is made into a pipe, and the right half shows the case in which the minimum size of a plate-like object is made into a pipe. This figure shows step by step the process of forming a plate-like object into a cylindrical shape using a forming roll used in the invention. As is clear from the figure, the shape of the forming roll employed in the present invention does not need to be changed depending on the diameter of the pipe, but simply displacing the forming roll according to the size and holding it at a predetermined position and height. This makes it possible to perform rough forming and intermediate forming of different pipe diameters using the same roll. In addition, in the present invention, since the vertical roll and the auxiliary roll are each configured separately, the vertical roll or the auxiliary roll can be independently replaced with a roll having a different shape or inclination angle. It is possible to freely form a concave corner portion with .

It should be noted that the roll forming method of the present invention can of course be applied to the production of electric resistance welded pipes, but it can also be applied not only to cylindrical pipes but also to the former forming part of square pipes, the forming of gutter-like pipes, etc. .

The effects obtained by the roll forming method of the present invention are as follows.

(1) The number of rolls can be significantly reduced compared to conventional molding methods.

(2) Changes in the pipe diameter can be handled by simply moving the forming rolls, and there is no need to replace the rolls as in the past.

Therefore, the operating rate of the molding machine can be significantly improved. (3) Friction between the plate and the roll can be reduced.

(4) Since the roll has a simple shape, it is easy to manufacture.

(5) Since the concave corner portion is formed by two mutually independent rolls, each roll can be easily replaced with another roll, and a concave corner portion of any shape and angle can be obtained. There is also the advantage that only one roll needs to be replaced depending on the degree of wear.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a rough forming roll in a conventional method, Fig. 2 is a sectional view of an intermediate forming roll in a conventional method, Fig. 3 is a sectional view of a final forming roll in a conventional method, and Fig. 4 is a sectional view of a roll for final forming in a conventional method. A side view showing an example of a molding device array for carrying out the process,
5, 6 and 7 are cross-sectional views showing each example of the push roll device, FIGS. 8A and 8B are layout diagrams of forming rolls used in the method of the present invention, and FIGS. , E are schematic diagrams showing the state of contact between the rolls and the plate-shaped body and the position of each roll when manufacturing pipes of different diameters. 1... Plate-shaped body, 2... Push roll, 3
... Forming roll, 4 ... Fin pass roll, 5 ... Vertical roll, 6 ... Auxiliary roll, 7 ... Horizontal roll.

Claims (1)

[Claims] 1. Regarding forming a plate-like object into a cylindrical tube, a pair of rolls that can be symmetrically displaceable and fixed with respect to an arbitrary diameter in a plane perpendicular to the tube axis direction, and a pair of rolls adjacent to each roll of the pair of rolls are provided. Together with the outer periphery of the pair of rolls,
A forming pass is provided by providing an auxiliary roll that forms a concave corner with respect to the axis, and the side edge of the plate-like object passing through the pass is restrained by the concave corner, thereby forming the plate-like object. A roll forming method for a cylindrical tube, characterized by forming a plate-like object into a cylindrical tube while applying bending deformation.