JPS6225452B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves passing a metal strip (material to be formed) through a number of roll stands arranged in tandem in the longitudinal direction, and bending and forming it in the width direction. This invention relates to improvements in forming rolls for cylindrical bodies in cold roll forming methods.

[Conventional technology]

Forming methods such as edge forming, center forming, and circular forming have been conventionally adopted as methods for forming circular tubular bodies from metal strips by cold roll forming, but none of these methods It is difficult to bend and form both edges of the material to be formed to the ends.

For this reason, as shown in FIG. 4, with the center part in the width direction of the material to be formed A1 or A2 bent in the opposite direction to the bending direction of the intended circular tubular body, the intended circular tubular body is bent at both edges. By bending and forming in the same direction as the bending direction of the body, that is, by pinching both edges in a state close to perpendicular to the rolling direction of the forming roll,
A forming method is known that alleviates the difficulty of bending both edges by imparting an effective bending action to the portion (hereinafter, this forming method will be referred to as the W-bend method).

On the other hand, multiple types of wall thicknesses are often required for a circular tubular body with the same outer diameter, so it would be ideal if the same pair of forming rolls could be used to form materials with a wide range of wall thicknesses, that is, various plate thicknesses. This is convenient in terms of reducing roll costs.

In the W-bending method, the material to be formed is pressed and bent from both the front and back sides as described above, so the roll gap between the two rolls used for clamping must be made to match the thickness of the sheet correctly, or to prevent the occurrence of edge waves. In order to prevent this, it is desirable to make the edges of the material to be formed slightly loose. Therefore, it is not possible to process materials having a wide range of thickness with the same forming roll hole die.

In the W-bending method, there is a proposal in Japanese Utility Model Publication No. 1984-44884 for the purpose of responding to changes in the thickness of the material to be formed.

As shown in Fig. 5, this proposal is based on a forming roll (hereinafter referred to as an upper roll, which presses the edge of the material to be formed from the inner surface of the target cylindrical body, and a lower roll relative to this upper roll). ) is divided in the axial direction into roll pieces 4, 4,
The circumferential curved surface of each roll piece 4, 4 is a circular arc surface having two radii of curvature R1 and R2 that have their center on the center line Ei perpendicular to the axis of the roll piece and touch each other on the center line Ei. The roll pieces 4, 4 can be reversed at their respective positions, and the curved surface of the lower roll 1 has a small radius of curvature R2 for a thick plate, and the curved surface of a large radius of curvature R1 for a thin plate. - It faces the concave curved surface (radius of curvature R3) on the outside of line A, and the material to be formed is clamped and pressed at this portion to bend and form it.

[Problem that the invention seeks to solve]

The above-mentioned proposal has the drawback that a sufficiently high-precision forming result cannot be obtained in bending a thick plate. That is, as the thickness of the material to be formed increases, it becomes difficult to bend and form the material, so in order to bend and form the material, it is necessary to apply pressure over a wide width dimension.

On the other hand, when molding a cylindrical body with the same outer diameter, the material to be molded is a thicker plate A2, which is narrower than a thinner A1, as shown in Figure 4, so the edge surface is a thin plate. It is closer to the center than .

However, in the above proposal, since the part where the material to be formed is clamped on a curved surface with a constant radius of curvature is the part outside the line E-I in Fig. 5, the width of the part to be clamped correctly is insufficient for thick plates. , bending with sufficiently high precision is difficult.

However, although it is not disclosed in the above publication, the inside of the line E-I of the lower roll 1 may be an arcuate curved surface having its center on the line E-I and having a radius of curvature R4 of R3+(R1-R2). Accordingly, it is possible to increase the width of the clamping pressure portion of the material to be formed. However, in this case, since the increased width of the clamping pressure part is different from the desired edge bending radius, this part needs to be further bent on the next stage roll stand, etc. The amount of molding per stage of stands will be reduced.

Therefore, when bending thick plates, which are difficult to bend, the above proposal does not apply to conventional edge forming, in which the central part in the width direction of the material to be formed is kept flat and held under narrow pressure, and both edges are It can be said that this forming method is not much different from the forming method in which the bending range is sequentially moved from the center to the center side.

The present invention is capable of responding to changes in the thickness of the material to be formed, and is particularly capable of ensuring the effective edge bending width of the thick plate.
It is an object of the present invention to provide a forming roll suitable for forming by a bending method.

[Means for solving problems]

To put it simply, the present invention is such that the proposed line E is not perpendicular to the axial center of the forming roll, but is made at an angle to the line perpendicular to the axial center.

In other words, the rolls that clamp both edges of the material to be formed from the inner surface of the target cylindrical body are divided in the axial direction, and can be reversed left and right at each position, and the cross-sectional shape of the outer peripheral work surface is is two lines on a straight line that is at an angle to a line perpendicular to the axis of the roll.
It is characterized by having two circular arcs that are centered on a point and touch each other on the line, and the side of the small radius of curvature is the side in the rolling direction of the straight line.

〔Example〕

The present invention will be described below based on the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of the cylindrical cold-forming roll of the present invention, and FIGS. 2 and 3 are cross-sectional views of essential parts of the roller in the state of forming a thick plate and a thin plate, respectively.

In Fig. 1, the upper roll is divided in the axial direction into divided roll pieces 4, 4, which can be turned left and right at respective positions on the roll axis (not shown), and the outer peripheral working surface is perpendicular to the roll axis. Radius of curvature R1 and R2 that touch on the straight line 12 with two points 10 and 11 as centers on the straight line 12 having an angle α to the line
It forms a circular arc surface with a small radius of curvature R
The 2nd side is the rolling direction side of the straight line 12.

In addition, in this example, the center 1 of each arc
The distance L from 0, 11 to the end face in the roll axis direction is made equal, so that when the split roll piece 4 is reversed, the axial position of the center of the circular arc surface that is the outside of the split roll piece 4 does not change. ing.

The roll hole shape of the lower roll 1 consists of a convex arc surface with a radius of curvature R5 at the center and a concave arc surface with a radius of curvature R3 on the outside that is in contact with this arc surface, and the center of the radius of curvature R3 is the radius of curvature R3. The position is the same as the center of R2 in the roll axis direction.

FIG. 2 shows a state in which a thick plate is bent and formed. As can be seen from this figure, the angle α is the angle at which the clamping pressure width increases in the present invention.

Furthermore, as can be seen from this figure, the roll of the present invention is suitable for forming thick plates that are difficult to bend, which is important as a roll that can be used for various plate thicknesses. , and can be disposed on both sides of the roll, including the part perpendicular to the rolling direction of the roll.

Next, Figure 3 shows the case of thin plate forming.
The upper roll 4 is horizontally reversed with respect to the state shown in FIG.

In this figure, a straight line 12 is inclined in the opposite direction to that in FIG. 2, and the material to be formed A1 is bent at a constant radius of curvature at a portion outside the straight line 12. Therefore, in the case of a thin plate that is easy to bend in the present invention, the clamping pressure range is narrower than in the above proposal. The narrow clamping pressure range is not a problem for thin plates, and the narrow clamping pressure range has the effect of reducing edge elongation.

Note that in this embodiment, the position of the center of the arcuate surface used in the roll axis direction remains unchanged even when the left and right sides are reversed, and there is no need to adjust this position.

〔Effect of the invention〕

As described above, the present invention has the advantage that, in addition to originally being difficult to bend and form rolls for various thicknesses,
This is an improvement over the conventional forming method, in which bending was more difficult due to the reduced clamping pressure width, and greatly improved the forming performance of thick plates without impairing the forming performance of thin plates.

In the above explanation, we have described the case of W-bending forming different thicknesses of cylindrical bodies with the same outer diameter, but the effect of the present invention, that is, the effect of increasing the clamping pressure range for thick plates, is This also occurs when molding a cylindrical body, so the present invention is not limited to cases where the outer diameter is the same.

In addition, in the present invention, the radius of curvature R1 and R
The outer portions of each of the two circular arcs may be provided with linear or circular arc-shaped portions with other radii of curvature.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the forming roll of the present invention, Figs. 2 and 3 are sectional views of main parts showing the forming state of thick plates and thin plates, and Fig. 4 is a sectional view of the conventional W-bending method and FIG. 5 is a cross-sectional view illustrating how the width dimension of a material to be formed changes when the sheet thickness changes. FIG. 5 is a cross-sectional view of a conventional sheet thickness roll. 1: Lower roll, 4, 4: Roll piece of upper roll,
A1, A2: Material to be formed, R1: Large radius of curvature, R
2: Small radius of curvature.

Claims (1)

[Claims] 1. A large number of roll stands in which metal strips are arranged in tandem are passed through in the longitudinal direction, and the strips are clamped from the front and back surfaces so that both edges in the width direction are bent in the same direction as the bending direction of the cylindrical body. In the cold forming roll of the cylindrical body used when bending the inner portions of the both edges in the direction opposite to the bending direction of the cylindrical body, the both edges of the material to be formed are The rolls that apply pressure from the inner surface of the tubular body are divided in the axial direction and can be turned left and right at each position, and the cross-sectional shape of the outer peripheral working surface is set at an angle with respect to a line perpendicular to the axis of the rolls. 1. A cold-forming roll for a cylindrical body, characterized in that it has two arcs that are centered on two points on a straight line, touch each other on the line, and have a small radius of curvature side as the rolling direction side of the straight line.