JPS6129810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a forming method for forming a predetermined deformed pipe in a process subsequent to forming a circular pipe in roll forming with a large number of roll stands.

Two examples of forming methods for forming irregularly shaped square pipes are the bending method shown in Fig. 1 and the drawing method in which a round pipe is formed as shown in Fig. 2 and then a square pipe is formed from the circular pipe as shown in Fig. 3. is typical. 1, 2, 3, 5, 8, 9 in Figure 2
and 10 are flowers showing the process of forming a circular pipe.

In the case of the conventional bending method, it is difficult to maintain the length of each side of the square pipe and the bending radius of the corner part evenly even by adjusting the roll stand, and it is difficult to weld the strength of the welded part and the welded part uniformly. Because of these drawbacks, companies generally use a method of forming square pipes rather than round pipes.

Conventionally, when forming a square pipe from a round pipe, the axis of the forming roll, which has a special roll hole mold that matches the prescribed square pipe dimensions as shown in Figure 4, is arranged in a straight line as shown in Figure 5. This is a method of forming irregularly shaped pipes (square pipes) with uniform radius on each side and corner by narrowing the outer circumference of the pipe while passing it through a round pipe, even if the objects are arranged in several stands (2 to 6 stands). . In both the conventional bending method and the drawing method, if the desired product cross-section has a different side length or cross-sectional shape, a dedicated forming roll is required for each.

The present invention has the advantages of the above-mentioned drawing method.
It maintains the ease of adjustment of each side and the ability to mold the corner radius uniformly, and even if the side length or cross-sectional shape is different, it can be easily adjusted by combining rod-shaped rolls with one molding stand device. The purpose is to develop a method for forming irregularly shaped pipes.

The present invention will be explained by examples. FIG. 6 is a perspective view showing a method of forming a deformed pipe using rod-shaped rolls according to the present invention. FIG. 6 shows an embodiment aimed at forming a rectangular shape.

In FIG. 6, reference numeral 11 denotes a pre-formed round pipe.
3, 14, and 15 (which may also be used as a stand), and then sequentially passes through the second stage B and third stage C, where the pitches are even between each roll group. In this case, the rolls at the initial stage of forming are particularly drum-shaped to prevent streak-like depressions from forming in the center of the sides of the product. That is,
When a perfectly circular material to be formed is squared with a cylindrical roll, streak-like dents are likely to occur in the center of the sides due to intense pressure.

The number of stages of all the roll groups for forming, the number of stages of the drum-shaped rolls, and the shape of the drum shape are determined by the range of variation of the ratio of the side length to the thickness of the product. In the case of forming square tubes, in the case of thin-walled tubes with a t/D (thickness/outer diameter) of the material tube of 3% or less, all drum drums are used except for the final finishing stage, which is 2 to 3 stages of cylindrical rolls. It is necessary to have a total of about 6 to 8 stages or more (see Figure 3). In conventional forming methods, the outer diameter of the rolls is large, which naturally results in a large amount of product cross-sectional deformation with each roll pass, or to avoid this, the number of roll stages must be increased.
In other words, compared to the need to increase the size of the equipment, the present invention uses small-diameter rod-shaped rolls, so
It is possible to set a small pitch between roll groups, and the amount of cross-sectional deformation of the product for each pass can be made small, that is, smooth, without increasing the size of the equipment.
It would be best to follow this.

In this way, the irregularly shaped pipe 21 is formed through the stands at each stage in I to I.
It is possible to continuously perform desired molding as desired.

The gist of the present invention is to combine opposing rod-shaped rolls into one stand, and depending on the position of the opposing rod-shaped rolls, the cross section can be square, rectangular, or
It can form polygons. If the purpose is to form a polygonal shape other than a rectangular shape, the number of roll pairs constituting each roll group (stand) may be determined accordingly.

In addition, it is desirable that the pitches between the pairs of rolls constituting a roll group (stand) and the pitches between the roll groups (stands) be as close as possible when considering formability, and the pitches should be placed evenly. This would be advantageous in designing the roll forming line. However, the present invention is not limited thereto. Furthermore, it is also possible to set the opposing rod-shaped rolls to have various irregular cross-sections by giving each one its own movement rather than adjusting each pair one by one. It is also possible to provide a drive device at the end of the rod-shaped roll to feed the molded product. 7th
The figure shows a typical example of a modified cross section that can be molded according to the present invention.

As explained above, the present invention is a method of forming a round pipe into an irregular cross-section by forming a desired irregular cross-section with a combination of opposed rod-shaped rolls, which facilitates adjustment of each side of the drawing method described above. The effect of manufacturing irregularly shaped pipes using a single type of molding device that takes advantage of the advantages of

[Brief explanation of the drawing]

Figure 1: Diagram of a flower formed in cross section of a band plate by the conventional bending method, Figure 2: Diagram of a flower formed into a round pipe by the conventional drawing method, Figure 3: A square shape than the round pipe produced by the conventional drawing method. Fig. 4: Example of forming rolls necessary for the drawing method, Fig. 5: Example of arrangement of forming rolls using the drawing method, Fig. 6: Arrangement of rod-shaped rolls during irregular roll forming according to the present invention , FIG. 7...A cross-sectional shape of a deformed pipe formed according to the present invention.

Claims (1)

[Claims] 1. In a method for forming a special-shaped pipe in which a pipe with a specific cross-sectional shape is manufactured from a raw material pipe with a substantially circular cross-section, a pair of rod-shaped rolls that clamp and compress a material to be formed from the outer diameter side thereof is moved along its axis in the direction of movement of the material to be formed. A method for forming an irregularly shaped pipe, characterized by changing the direction and overlapping each other to form a roll group, providing a plurality of roll groups, and using drum-shaped rolls as the roll group at the initial stage of forming.