JPH0149564B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention generally relates to pipes with a diameter of 30 m that are often used as supply paths for oil and air in automobiles and other various machines, equipment, devices, etc. The present invention relates to a method for bending a metal tube having a relatively small diameter and a thin wall, with a wall thickness of about 2 m/m or less, and to an improvement of a mold roll for the bending process.

[Prior Art] Conventionally, this type of metal tube bending method and its bending die roll have been made using a disc body having a mounting hole 12 in the shaft core or a partially cut-out roll, as illustrated in FIG. A processing roll 10 is used in which a fitting groove 13 having a substantially semicircular cross section is provided along the circumferential surface of a disc body 11. As shown in FIG. 3, the bending method is shown in FIG. Insert. In addition, a wiper 15 [in cooperation with the core metal 14] is located on the inner peripheral surface in front of the bending part.
When the metal pipe P' is held down by the holding tool 19 and the metal pipe P' is held down by the clamp body 16, the metal pipe is The bending process was performed by holding P' and moving the handle 17 in the direction of the arrow, and simultaneously rotating the disc body 11 as a mold roll.

[Problems to be Solved by the Invention] Generally, when bending the metal tube, as the ratio of the wall thickness to the outer diameter of the metal tube decreases,
Furthermore, as the ratio of the bending radius to the outer diameter becomes smaller, as shown in FIG.
Extreme strain deformation caused by local buckling due to pressure 2
yields 0. If such distortion and deformation 20 occurs, the flow path at the bent portion will be narrowed and the flow of fluid will be obstructed, so it is desirable to prevent the occurrence of distortion and deformation as much as possible to obtain a smooth inner peripheral wall. By the way.

However, when using the conventional bending die roll, it is extremely difficult to prevent the distortion and deformation 20 from occurring. For this reason, in connection with the use of mold rolls for bending, a conventional bending method as shown in FIG. 3 had to be used. Therefore, when the conventional bending die roll is used, the core metal 14 and the wiper 15 are required, which not only complicates the entire device, but also makes the core metal 14 different from the metal tube P' each time it is processed. The wiper must be inserted into the interior, and the wiper setting work is also troublesome, resulting in a significant reduction in productivity.

The present invention was made in view of the current state of this type of metal tube bending method as described above, and its purpose is to eliminate the bending process that occurs on the circumferential surface of a metal tube without using a core metal or a wiper. To provide a method for smoothly bending a metal tube by releasing strain deformation portions without causing large local buckling, and to provide a bending die roll used for the bending.

[Means for Solving the Problems] In order to achieve the above object, the method of bending a metal tube of the present invention includes forming a metal tube into a substantially disk shape, and having a fitting groove having a substantially semicircular cross section on the circumferential surface. A bending mold roll is formed, and a plurality of deformation absorbing recesses are formed at short intervals from each other over at least a predetermined area on the bottom surface of the fitting groove, and a mounting hole is formed at the axis position. The metal tube is fixed to the frame through the mounting hole, the circumferential surface of the bent part of the metal tube is brought into contact with the fitting groove, and the metal tube is pressed from the outside along the fitting groove. The metal tube is bent by allowing the strain-deformed portion that occurs on the peripheral surface of the metal tube to escape into the deformation absorbing recess.

Further, the bending mold roll of the present invention is formed into a substantially disk shape, and a fitting groove having a substantially semicircular cross section is formed on the circumferential surface, and a fitting groove having a substantially semicircular cross section is formed on the bottom surface of the fitting groove over at least a predetermined area. A plurality of deformation absorbing recesses are formed at short intervals from each other, and a mounting hole is formed at the axial position.

[Function] According to the present invention, the circumferential surface of the metal tube is brought into contact with the fitting groove on the circumferential surface of the disc-shaped bending mold roll, and the metal tube is pressed from the outside along the fitting groove. A bending process is performed on the metal tube by.

The distortion and deformation of the circumferential surface of the metal tube caused by this pressing is successively released into the deformation absorbing recess formed at the bottom of the fitting groove of the bending mold roll.
The metal tube can be bent smoothly while preventing the occurrence of large strain deformation caused by local buckling.

This bending process does not require the use of a core metal or a wiper as in the past, and is easily performed.

[Example] Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1A is a front view of a bending die roll 10a according to the present invention, and FIG. A of
- It is a sectional view taken along the A line, and the axial center of the disk body 1 is attached to the stand (not shown) by bolts or the like.
A mounting hole 2 for fixing is provided. Further, a fitting groove 3 having a semicircular cross section is formed along the circumferential wall surface of the disc body 1, and near the bottom of the entire circumference of the fitting groove or a part of the circumference, there is a A plurality of shallow deformation absorbing recesses 4 are provided in a continuous wave-like manner, or are provided in a spaced manner with a slight interval between them. It is desirable that the deformation absorbing recess 4 is provided in a partially spherical shape such as a semi-spherical or semi-circular sphere. By using the bending die roll 10a composed of the disk body 1,
For example, bending can be performed without requiring the core bar and wiper used in the conventional bending method shown in FIG.

That is, the bent portion of the metal tube P is set in contact with the fitting groove 3 on the circumferential surface of the bending mold roll 10a, and the metal tube P is inserted from the outside along the circumference of the fitting groove 3. The metal tube P is pressed in the bending direction, and the strain deformation on the inner circumferential wall of the bent portion due to the press is sequentially released into the deformation absorbing recess 4 to perform the bending process. Only a low bulge 5 within the range is formed, and the occurrence of extreme strain deformation caused by local buckling is prevented, so the metal tube P is not damaged by bending or can be bent in a state where it is extremely prone to breakage. never be done. Further, the flow path at the bent portion of the metal tube P does not become narrow and the flow is not obstructed. At the same time, it is possible to eliminate the need for a core metal and a wiper during bending.

[Effects of the Invention] As explained above, according to the present invention, the plurality of deformation absorbing recesses 4 provided in the fitting groove 3 portion formed on the circumferential surface of the bending mold roll improve the stability during bending. Since the strain deformation caused by the pressing on the inner circumferential wall of the bent portion of the metal tube P in is effectively released into the recessed portion, extreme strain deformation caused by local buckling can be prevented.

Therefore, the strength of the metal tube after bending does not decrease and the metal tube does not become easily damaged. In addition, there is no need to worry about narrowing the flow path at the bending part and obstructing the flow, and there is no need for a core metal or wiper during bending, so the outward bulge 5 can be made within the allowable range without interfering with the flow. Thus, an inner circumferential wall of the bent portion can be formed. Furthermore, since no core metal or wiper is required, productivity can be improved by eliminating the work of inserting a core metal into the metal tube P and setting the wiper.

[Brief explanation of drawings]

FIG. 1A is a front view of a bending die roll related to a method for bending a small-diameter thin-walled metal tube according to an embodiment of the present invention, and FIG. 1B is an A of FIG. 1A. 2 is a front view of the conventional bending die roll shown above; FIG. 3 is an explanatory diagram of the conventional bending method using the die roll shown in FIG. 2; The figure is a partially cutaway plan view of the bending portion using the mold roll of the present invention shown in FIG. 1, and FIG. 5 is a partially cutaway plan view of the bending portion using the conventional mold roll shown in FIG. . 1...Disk body, 2...Mounting hole, 3...Guiding groove, 4...Recess.

Claims (1)

[Scope of Claims] 1. A fitting groove formed in a substantially disk shape and having a substantially semicircular cross section is formed on the circumferential surface, and a plurality of deformations are formed on the bottom surface of the fitting groove over at least a predetermined area. A bending die roll in which absorbing recesses are formed at short intervals and a mounting hole is formed at the axis position.
The metal tube is fixed to the frame using the mounting hole, the circumferential surface of the bent part of the metal tube is brought into contact with the fitting groove, and the metal tube is pressed from the outside along the fitting groove. A method for bending a metal tube, characterized in that the metal tube is bent while allowing a strain-deformed portion generated on the circumferential surface of the tube to escape into the deformation absorbing recess. 2. A fitting groove formed in a substantially disk shape and having a substantially semicircular cross section is formed on the circumferential surface, and a plurality of deformation absorbing grooves are formed at short intervals on the bottom surface of the fitting groove over at least a predetermined area. A mold roll for bending, characterized in that it is formed of a molded roll and has a mounting hole formed at the axial center position.