JPH0811257B2 - Double pipe bending method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a double pipe used for an automobile exhaust pipe, a heat insulating pipe and the like.

[0002]

2. Description of the Related Art When bending a double pipe , the outer pipe is bent.
In order to prevent the part that contacts the mold from deforming abnormally,
Conventionally, a method of enclosing magnetic particles in a gap between an inner tube and an outer tube, magnetizing the magnetic particles in the vicinity of the bending die to restrain mutual movement of the particles, and pressing the bending die with a pusher to bend the magnetic particles (JP-A-58).
No. -70926, No. 62-234621) are known.

[0003]

According to the above-mentioned prior art, the magnetic fine particles are gathered in a solid state in the vicinity of the bending die , but are easily moved in other portions, so that they are firmly filled, sealed and magnetized. However , the magnetic fine particles in the bending die contact portion and the press metal contact portion to which a pressing force is applied during processing are slightly
And the inner and outer tubes are likely to be abnormally deformed.

[0004]

DISCLOSURE OF THE INVENTION The present invention is an improvement over the above-mentioned prior art to enable bending of a double pipe without abnormal deformation. The means includes a thin inner pipe and an outer pipe. becomes the gap of the double tube the particles of magnetic material filling, in contact with the arcuate surface of the outer periphery of the mold bending the double pipe, while the magnetization of the particles of the magnetic material of the bending tool near an electromagnet, of the bending mold in the double pipe bending processing method of bending presses with gold press double tube on both sides, the magnetic portion receives a pressing force from the portion及<br/> beauty push gold receives a pressing force from the mold bent during bending Together with body particles
It is characterized by being magnetized by an electromagnet .

[0005]

[Function] Since the magnetic fine particles in the gap between the inner and outer tubes are solidified by the high binding force in the magnetized area near the bending die and the pressing metal due to the magnetization , whether the inner or outer tube is the bending die or the pressing die.
Prevents local deformation due to pressing force applied from the
It becomes a thick-walled pipe and undergoes bending, so that the inner and outer pipes do not bend abnormally.

In particular, magnetic fine particles in the vicinity of the bending die are integrated by their own magnetization, and in addition, the magnetized fine particles in the vicinity of the pressing metal on both sides act to prevent movement, thereby preventing abnormal deformation during processing. .

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, the double pipe 1 is a thin-walled inner pipe 2
The outer tube 3 and the outer tube 3, and both tubes 2, 3 are concentrically fixed with a gap 5 having a predetermined size by an inward flange 4 formed at one end of the outer tube 3, and the inside of the gap 5 has, for example, a diameter of 0.1. ~
Magnetic particles 6 such as 0.5 mm of iron powder or iron oxide are filled, and an annular plug 7 is press-fitted into the other end to seal it. As the sealing means , the plugs 7 may be used at both ends without providing the flange 4.

The bending apparatus 10 is a roller type bending die 1.
1. An electromagnet 12 near the bending die 11 and pushers 13 and 14 with an electromagnet.
As shown in FIG. 3, it comprises a pusher 15, a pair of electromagnets 16 and 17 surrounding the pusher 15 and the double tube, and the other pushers 14 with electromagnets have the same structure. The surface in contact with the double pipe 1 in the bending die 11 and the pressing metal 15,
As shown in FIGS. 2 and 3, it has an arcuate surface that matches the outer peripheral surface of the double pipe 1.

The electromagnets 12, 16 and 17 are U-shaped cores 1.
Coils 12b, 16b, 17b on 2a, 16a, 17a
The bent portion of the double tube 1 is sandwiched between the magnetic poles of the electromagnet 12 and the bending die 1 is formed by the magnetic poles of the electromagnets 16 and 17.
Clamp the pressing portion of the double pipe 1 on both sides of the coil 1 and the coils 12b, 1
The magnetic fine particles 6 are magnetized by energizing 6b and 17b. Due to this magnetization, the respective fine particles 6 are coupled to each other, and are brought into an integrated solid state as a whole.

Bending die 11 and pusher 1 of this processing apparatus 10
The double tube 1 is sandwiched between 5, 15 and the electromagnets 12 , 16 , 1
When 7 is excited, the outer tube 3, the layer of magnetic fine particles 6 and the inner tube 2 in the magnetized area are integrated into a thick tube, and when one of the electromagnet-attached pushers 14 is pressed in the direction of arrow F, The pressing force applied to the tube 3 is transmitted to the inner tube 2 through the layer of the fine particles 6 in the solid state in each magnetized area. Therefore, the inner tube 2 is pressed in the same manner as the outer tube 3 and deforms in the same manner, and maintains the substantially same gap 5, so that no abnormal deformation occurs. At this time, the fine particles 6 near the bending die 11 are particularly strong.
Trying to move in the longitudinal direction of the pipe due to the pressing force
However, this movement is strongly magnetized in the vicinity of the pushers 15, 15.
It is resisted by the part and is blocked.

After processing the double tube 1 into a desired curvature,
When the electromagnets 12, 16 and 17 are demagnetized and removed from the apparatus, and the annular plug 7 is removed, the magnetic fine particles 6 are already disengaged due to demagnetization, and because the particle diameter is minute, they easily flow and cause a gap. Despite the narrow width of 5, it can be completely discharged.

[0012]

In the above steps, the magnetic fine particles filled in the gap between the inner and outer tubes are magnetized by the electromagnet and are strongly bonded to each other and the fine particles and the inner and outer tubes are integrated , so that the bending pressure is sufficient. The abnormal deformation does not occur in the double pipe.

[0013] Moreover, since the magnetized portion pressed by embossed as compared with the conventional magnetizing only the curved portion of the double tube, it is possible to prevent abnormal deformation of the pressing part portion of each side not the curved portion only , the magnetization of the particles of the pressing portion in portion of the both side, it is possible to add movement blocking effect on magnetic microparticles are retained in the curved portion. Therefore, the pressure applied to the double pipe becomes the highest, and the curved portion where abnormal deformation is likely to occur,
The effect of being able to bend normally is produced.

[Brief description of drawings]

FIG. 1 is a front view of an apparatus according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

[FIG. 3] Same as above, taken along line III-III

[Explanation of symbols]

1 Double tube 2 Inner tube 3
Outer tube 5 Gap 6 Magnetic fine particles 10
Bending die 13,14 Pusher with electromagnet 15 Pusher 12,16,17 Electromagnet

Claims (1)

[Claims] 1. A magnetic material in the vicinity of a bending die , wherein fine particles of a magnetic material are filled in a gap between a thin inner tube and an outer tube, and the double tube is brought into contact with an arc surface of an outer periphery of the bending die. Of fine particles of electromagnet
In with the magnetization, in the double pipe bending processing method of bending presses with gold press double tube on both sides of the bending mold, or parts and the push gold receives a pressing force from the mold bent during bending
A double tube bending method characterized in that the magnetic fine particles in a portion which receives a pressing force from the magnet are magnetized together by an electromagnet .