JPS5830592A - Bending structure of pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bending structure for pipes, and in particular to a bending structure that is effective when bending a thin metal round pipe to a small radius of curvature.

Conventionally, pipes used in automobile seat frames and the like are made by bending thin-walled metal round pipes into a small radius of curvature. In general, the minimum bending curvature of a pipe is carbon steel pipe for mechanical structures (STKMllA), and in the case of 180 degree bending (folding), the inner radius is four times the pipe outer diameter (0) (4D), and this value is It is said that if it is less than this, wrinkles will occur on the inner wall, and the cross section of the core will become flattened when the pipe 1 is bent, as shown in FIGS. 1(A) and 1(B), resulting in a decrease in strength.

An object of the present invention is to provide a bending structure for a pipe that has a bending curvature smaller than the above-mentioned minimum bending curvature, does not generate wrinkles on the inner wall, and has high strength.

In order to achieve the above object, the present invention provides a pipe in which a pipe is clamped to the die surface of a bending die by a clamping means installed in a pipe bending die device, and is bent by a press die that is movable toward and away from the bending die. , a groove is provided at the bottom of the bending mold surface almost over the entire bending area toward the bending center, and during bending, at least the bending area range is bent R.
A bending die and a press die are set so that the diameter of the pipe is compressed toward the two cores, and the excess wall of the pipe is made to protrude into the groove of the bending die. The pipe diameter corresponding to the bending radius is slightly flattened toward the core, and protrusions and striations are integrally formed from the inner wall of the pipe corresponding to the bending point toward the bending core over almost the entire bending point ξ This provides a bending structure for pipes.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

FIG. 2 (5) 0 shows a pipe 2 according to the present invention, which is a thin-walled metal round shape with a small curvature R (1.7D in relation to the diameter of the pipe) and 90 degrees. It is bent into a shape. At the bending point 3 (range 41 to 12) of the pipe 2, as shown in FIG. is made slightly shorter than the major axis r2 in the lateral direction. The diameter 2r2 in the lateral direction is approximately the same as the diameter of the straight portion 4 of the pipe 2. Further, on the inner wall 2a of the pipe corresponding to the bending point 3 of the pipe 2, a circular arc-shaped protrusion 5 protruding toward the bending radius 0 is formed over the entire area of the bending point 3.

The length S from the tip of the protrusion 5 to the opposing outer wall 2C is approximately the same as the diameter of the pipe. (SAD) At the bending point 3 of the pipe 2, since the protrusion 5 is formed, wrinkles are not generated on the inner wall 2a, and the strength is increased by the protrusion 5, so that the minimum bending curvature is lower than the conventional minimum bending curvature. (R
=:=4[)) It can be bent with a bending curvature that is even smaller than that of 4 [)].

FIG. 3 and subsequent figures show a bending device for the pipe 2, in which 6 is a frame of a bending machine, 7 is a bending die protruding from the frame 6,
8 is a clamping means protruding from the frame 6 facing above the bending mold 7; 9 is a cylinder pivotally connected to the frame 6;
0 is a press die mounting plate which is pivotally connected to the downward rod 9a of the cylinder 9 and the clamp means 8, and 11 is a press die which is pivotally connected to the press die mounting plate 10. The bending die 7 has a U-shaped groove 7b formed at the bottom of the bending die surface 7a substantially over the entire bending area toward one bending radius. In addition, the bending mold surface 7
a and the die surface 11a of the die 11 are set to a radius slightly smaller than the pipe radius of the pipe 2 so that the diameter of the pipe 2 is compressed toward the core during bending. There is.

When bending the pipe 2 using the above device, the upper outer circumferential surface of the pipe 2 is held by the clamping means 8, and the lower outer circumferential surface of the pipe 2 is fitted into the bending mold 7. In this state, pipe 2
The straight section of is fixed by clamping means 8 and bending die 7.

Then, actuate the cylinder 9 to lower the rod 9a and lower the rod 9a.
The press mold mounting plate 10 is rotated in the direction of the arrow in the figure using the clamp pivot point as a fulcrum. With this rotation, the press die 11 moves close to the bending die surface 7a of the bending die 7, and the pipe 2 is fitted between the die surface 11a of the press die 11 and the bending die surface 7a. The pipe 2 is bent along surfaces 11a and 7a. By this bending process, as shown in FIG. 3, the mold surface 11a
, 7a is made slightly smaller than the radius of pipe 2, the bending point 3 of pipe 2 is slightly flattened so that the pipe diameter is compressed toward the bending R core,
The extra wall of the inner wall escapes from the groove 7bl of the bending mold surface 7a and protrudes.

A protrusion 5 is integrally formed with the inner wall 2a of the pipe 2.

As is clear from the above description, according to the pipe bending structure according to the present invention, a relief groove is provided in the mold (bending mold) inside the pipe of the pipe bending device, and excess metal is collected in the groove during bending. By doing this, it is possible to prevent wrinkles from forming on the inner wall of the pipe at the bending point, and on the contrary, form protrusions that act as reinforcement.Thus, it is possible to make a thin-walled metal round pipe with a bending radius smaller than the minimum bending curvature of a typical pipe. It has the advantage that it can be bent with a certain curvature, and even when bent with a small curvature, the strength does not decrease, and on the contrary, the bent part can be strengthened.

[Brief explanation of drawings]

The first part is a side view showing the bending structure of a conventional pipe;
) is an XX-line cross-sectional view of the first rotation, and FIG. 2 (-) is a side view showing the bending structure of the pipe according to the present invention, and FIG. 2(B)
Figure 3 is a front view of the pipe bending device, Figure 4 is a side view of Figure 3, and Figure 5 is a cross-sectional view taken along the line Y-Y in the second round. FIG. 2... Pipe, 3... Bending point, 5... Projection, 7... Bending die, 7a... Mold surface, 7b... Groove, 8... Clamping means, 9...・Cylinder, 11
...Press mold, 11a--Mold surface.

Claims (1)

[Claims] (1) In a pipe that is clamped along the mold surface of a bending die by a clamping means and is bent by a pressing die that can be moved toward and away from the bending die. A groove is provided at the bottom of the bending die surface over the entire bending area toward the bending core, and when bending the bending die and press die, the diameter of the pipe is compressed when bending the bending area of the pipe toward the R core. The bending point of the pipe is set to be slightly flattened toward the bending core, and a protrusion that is integrally formed from the inner wall of the pipe at the bending point toward the bending core is placed at the bending point. A pipe bending structure characterized by being formed over the entire area.