JPS6317529B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a cold roll forming method with a large number of roll stands to produce C-shaped steel, channel steel, guardrails, automobile bumpers, and other shapes with open edges, and in particular with long rises. This paper relates to roll forming methods of different sizes.

When a metal strip is cold roll-formed into a desired shape with an irregular cross-section through a number of roll stands, it is necessary to use a straightening machine etc. to form a molded product that is straight in the longitudinal direction, or to form a molded product that is constant in the longitudinal direction. When molding a molded product having a C-shaped cross section with a curvature of , and the edges having different rising lengths, a flat roll is usually used for the bottom part of the shaped product.

Fig. 1 shows the above-mentioned sections having different cross-sections with rising edges, but when this section is formed using the flower shown in Fig. 2, the bottom part of the section corresponding to A in No. 1 is flat. The rising part B is formed by the upper and lower rolls having an angle of β, and the rising part C is formed by the horizontal part of the roll.
It was formed using upper and lower rolls with an angle of . Then, No. 2 and No. 3 were molded, and No. 4 was used to complete the desired molded product shown in FIG. 1. This shows one molding form; in reality, many stands are used.
Even when forming channel steel, 10 to 12 stages of stands are usually required. With this type of forming method, from the strip
Since the strip passes through the stands continuously from No. 1 to No. 1 and from No. 1 to No. 2, twisting occurs in the vertical direction of the strip plate between the stands where it is formed. We considered adjusting the rising angles α and β for each pass to create a strain that was as balanced as possible, but due to the relationship with the thickness and height of the shape, it was difficult to adjust the rising angles α and β for each pass. I couldn't solve the problem.

The present invention has been made to solve these drawbacks, and in the process of forming a profile having edges with different rise heights on both sides of the cross section, the shape of the roll forming the center area is formed into an uneven roll shape. It has been found that a normal desired cross section without twisting can be obtained, and the present invention is to provide a cold roll forming method having an irregularly shaped open cross section.

The cause of twisting in molded materials is not fully understood. However, when a strip-shaped body is subjected to elongation deformation in the length direction on both sides of its width direction, this strip-shaped body generates a propeller-like twist in either the left or right direction.
In channel steel, similar torsion occurs when the edges of each planar portion are stretched in the length direction relative to the center of the width. It is known that when cold roll forming channel steel or the like, the tip of the rising portion is particularly large, and the corner portion between the web and the flange is elongated and deformed in the length direction during bending. Therefore, it can be seen that twisting can be prevented by reducing the elongation in the longitudinal direction, particularly at the tip of the rising portion. The elongation of the tip of the rising portion in the longitudinal direction increases with the bending angle of the corner portion per stage of forming rolls, the length of the rising portion, and therefore the amount of displacement on the flower. Generally, the bending angle of the corner part per stage of forming rolls is set to be large during the early to middle stages of forming, and is selected to be small in the late stages of forming due to friction between the material to be formed and the forming rolls. Therefore, the elongation at the tip of the rising portion is particularly large from the early to middle stages of corner forming.

The present invention will be explained using figures. FIG. 3 shows an embodiment of the shape forming method of the present invention.
This is a flower diagram for forming a profile having the same shape as shown in FIG. In other words, A' is the part that will become the bottom part of the profile, and B' and C' are the rising edge parts on both sides, respectively. The corner portions are bent using a concave roll and an upper roll.

Although FIG. 3 merely shows an embodiment of the present invention, and the finished product is completed in steps No. 1 to No. 4, in actual implementation, for example, the cross-sectional bottom width
50m/m rising, 15m/m on one side, 50m/m on the other side
When a channel steel with a thickness of 1.6 m/m was formed using the forming method of the present invention, a 7-stage cold roll stand was required. There was no twisting and dimensional accuracy was good.

As an embodiment of the present invention, the case where the open portion of the rising edge of the cross section is molded upward is illustrated, but
It is sufficient that the roll shape is such that the bottom part, which is the central part with respect to the open part of the strip shape material during molding, is always convex even when it is turned downward or sideways.

FIG. 4 is a flower diagram showing another embodiment of the present invention. To form shape No. 7 of the product cross section
Molding is performed through the cross-sectional deformation steps No. 1 to No. 6, and the method of the present invention is applied to No. 1 and No. 2 parts.

As explained above, by using the forming method of the present invention in roll forming a section having an open cross section such as a section steel, longitudinal twisting can be prevented even when the forming material has different heights of rising edges on the side. The effect of being able to mold shapes with accurate dimensions without causing any problems is remarkable.

[Brief explanation of the drawing]

Figure 1 is a cross section of channel steel, Figure 2 is a flower diagram of a conventional cold roll forming method, Figure 3 is a flower diagram showing an embodiment of the present invention, and Figure 4 is an applied flower diagram of the present invention. It is.

Claims (1)

[Claims] 1. A metal strip plate having a cross-sectional shape in which the central portion A in the width direction is flat or nearly flat, and has rising portions B and C having different lengths in the same direction on both sides, and is straight in the longitudinal direction. In the cold roll forming method, the corner formed by the central portion A and both rising portions B and C is bent into a curved state in which the central portion A is convex in the rising direction, and the material to be formed is A cold roll forming method for a shaped material, characterized in that the rolling is carried out perpendicularly to a plane containing both axes of a pair of forming rolls to prevent twisting of the cross section of the product.