JP3686347B2 - Metal pipe bending method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a method for bending a metal pipe such as an automobile fuel supply pipe.
[0002]
[Prior art]
A metal pipe such as a conventional fuel supply pipe of an automobile is bent using a known pipe bender a as illustrated in FIG. The pipe bender a includes a chuck portion b on which a mandrel shaft c having a mandrel d attached to a tip portion is protruded, a rotatable bending roll e disposed on one side of the mandrel shaft c, and the roll a wrinkle presser jig f disposed close to the concave arc portion that accommodates the metal pipe p of e, and a predetermined angular range centering on the center of the bending roll e while moving forward and backward with respect to the other side portion of the mandrel shaft c. The clamp die g is provided so as to be rotatable inside, and the pressure die i is movable forward and backward in the same direction as the clamp die g.
[0003]
Then, the metal pipe p to be processed is passed through the mandrel shaft c and is gripped by the chuck portion b, and then the clamp die g and the pressure die i are advanced to clamp the pipe p by the bending roll e and the clamp die g. . At this time, the pipe p is also lightly supported by the wrinkle pressing jig f and the pressure die i. Next, the bending pipe e is rotated while the metal pipe p is held, so that the pipe p is bent at a predetermined angle.
[0004]
Japanese Utility Model Publication No. 62-92017 discloses a metal pipe bending mold in which a large number of grooves are provided in a groove of an arc-shaped bending mold at right angles to the longitudinal direction of the groove. Yes. Gavels are formed on the bent inner periphery of the metal pipe processed by this mold. Japanese Laid-Open Patent Publication No. 60-166124 discloses that a pipe is bent using a roll in which a groove extending in the circumferential direction of an arc-shaped molding surface is formed, and an axial direction of the pipe is applied to a bent inner peripheral portion. An apparatus for manufacturing a brazed tube that forms a protruding vein is disclosed.
[0005]
[Problems to be solved by the invention]
When the metal pipe p is a seam-welded stainless steel pipe with a thin plate thickness according to the conventional method for bending a metal pipe as described above, the bending process is performed due to the difference in material between the seam welded part and other parts. Uneven wrinkles are likely to occur at the locations where they are formed. The wrinkles are considerably suppressed by the wrinkle pressing jig f, but the alignment between the jig f and the roll e has to be finely adjusted, and the work is very complicated. Moreover, since the size of wrinkles and the location where wrinkles differ from product to product, it does not look good and it is difficult to obtain a product with stable quality.
[0006]
In the second bending process using the mold disclosed in Japanese Utility Model Publication No. 62-92017, the mold and the movable mold containing the metal pipe are relatively moved without inserting the mandrel into the metal pipe. Since the bending process is performed by pressing, the small wrinkles generated in the inner periphery of the bending have a rough shape, and it can be said that the pipe tends to be flat. In the last manufacturing apparatus of a brazed bend pipe disclosed in Japanese Patent Application Laid-Open No. 60-166124, it is described that a surplus portion generated by compression enters a groove to form a protrusion, but is processed. Depending on the thickness and thickness of the tube, it may be impossible to absorb the surplus portion with only one axial groove. In addition, it is assumed that uneven wrinkles are formed in the formed protrusions themselves.
[0007]
An object of the present invention is to provide a metal pipe bending method capable of stably processing a large number of wrinkles generated in a bending inner peripheral portion of a pipe when being bent into a uniform shape.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a chuck portion in which a mandrel shaft having a mandrel attached to a tip portion is projected, and a rotatable bending device disposed on one side of the mandrel shaft. A clamp means comprising a roll and a clamp die that is advanced and retracted with respect to the other side of the mandrel shaft and is rotatable about a center of the bending roll within a predetermined angle range; and Using a pipe bender composed of a pressure die that can move forward and backward in a direction, a metal pipe passed through the mandrel shaft is gripped by the chuck portion, and the clamp die is advanced to move the pipe to the bending roll. Then, the bending roll is rotated while the metal pipe is clamped. In bending method of the metal pipe subjected to bending of a predetermined angle in the pipe by,
About the bending roll, a corrugated shape having a constant height with a constant angular interval centered on the center of the roll is formed in a concave arc portion formed so as to substantially match the outer diameter shape of the metal pipe, and the metal pipe Provided with a molding part provided so that the developed length of the uneven part formed on the inner peripheral part of the pipe is substantially the same as the length of the virtual center line of the bent part of the pipe A gap between the inner diameter surface of the pipe and the mandrel is provided with a predetermined dimension, and when the bending roll is rotated while the metal pipe is sandwiched, the bent inner periphery of the metal pipe is pressed against the formed part. by, is characterized in the that the plurality of uneven portions of substantially the same shape as the waveform shape of the molded portion is formed bent inner peripheral portion of the pipe.
[00 09 ]
[Action and effect of the invention]
The bending roll has a uniform corrugated shape in the concave arc portion that accommodates the metal pipe, and the unfolded length formed on the bent inner peripheral portion of the metal pipe (that is, forming the bending roll) The forming portion is provided so that the length of the imaginary center line of the portion of the pipe to be bent and the length of the virtual center line of the portion to be bent is substantially the same . Therefore, when the metal pipe is sandwiched between the bending roll and the clamp die and the roll is rotated, the surplus portion that occurs in the bending inner periphery of the pipe due to compressive stress is the corrugated shape of the molded part. It smoothly transitions so as to enter the recess. As a result, uneven portions having substantially the same shape as the corrugated shape of the bending roll are uniformly formed on the inner periphery of the pipe.
[00 10 ]
According to this metal pipe bending method, a portion called a conventional wrinkle that is formed on the inner periphery of the pipe is uniformly shaped as a corrugated uneven portion, and the appearance is also finished with a beautiful appearance, and a stable quality product. Can be obtained. In addition, an expensive wrinkle pressing jig used in the conventional bending method is not required, and a troublesome adjustment work for the jig is not necessary.
[00 11 ]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the method of the present invention will be described below with reference to the drawings. 1 is a front view of a bending roll of a pipe bender to which the method of the present invention is applied, FIG. 2 is a plan view of FIG. 1, FIG. 3 is an explanatory view showing the arrangement of a roll body and a clamp die, and FIG. FIG. 5 is a side view of the roll block, FIG. 6 is a sectional view taken along line AA in FIG. 5, and FIG. 7 is an explanatory view of a metal pipe to be bent.
[00 12 ]
In the pipe bender to which this metal pipe bending method is applied, each mechanism / element other than the bending roll is basically the same as that of the conventional pipe bender described above, so the description is omitted. We will describe in detail the bending role, which is an important component.
In the present invention, no wrinkle pressing jig is used.
[00 13 ]
A bending roll 1 shown in FIG. 1 has a roll body 10, a post 3, a stay 4, and a presser ring 5 that are loosely fitted in this order on a fixed shaft 2 erected on a base (not shown), and a nut 6 on the upper end of the fixed shaft 2. Are integrally provided.
[00 14 ]
As shown in FIG. 4, the roll body 10 has an arc-shaped notch slightly smaller than a semicircular shape (180 °) around the center hole 11 in the body portion 12 provided with the center hole 11 through which the fixed shaft 2 passes. In addition to forming the portion 13, concave arc portions 14, 14 that substantially match the outer diameter shape of the metal pipe p are formed along the tangential direction of the edge of the notch portion 13, respectively.
[00 15 ]
Reference numeral 20 denotes an arc-shaped roll block that is slightly smaller than a semicircular shape that is attached to the roll body 10 by bolts. As shown in FIGS. 5 and 6, the roll block 20 is formed with a concave arc portion 22 that substantially matches the outer diameter of the metal pipe on the peripheral surface 21, and the concave arc portion 22 The forming part 23 having a waveform shape having a constant height at a constant angular interval centered on the center is provided continuously. As shown in FIG. 7, the formed portion 23 has a developed length of the uneven portion r formed on the bending inner peripheral portion q of the metal pipe p, and a virtual portion of the bent portion of the pipe p. It is provided so that the length s of the center line is substantially the same.
[00 16 ]
Next, a method for bending a metal pipe of the present invention using the bending roll 1 will be described.
(1) The metal pipe p to be processed is passed through the mandrel shaft c and is gripped by the chuck portion b, and the clamp die 30 and the pressure die h are advanced to clamp the pipe p between the bending roll 1 and the clamp die 30.
(2) In a state where the metal pipe p is sandwiched between the concave arc portion 14 of the roll body 10 and the concave arc portion 31 of the clamp die 30, the bending roll 1 is rotated clockwise by a predetermined angle by a driving device (not shown). .
(3) Thereby, the bending inner peripheral part q of the pipe p is press-contacted with the shaping | molding part 23 of the roll block 20, and the some uneven | corrugated | grooved part r substantially the same shape as the waveform shape of the shaping | molding part 23 is the bending inner peripheral part q. A uniformly formed pipe is bent.
[00 17 ]
(Experimental example)
The bending method of the metal pipe of the present invention was tested under the following conditions.
Metal pipe: Seam welded stainless steel pipe
(Outer diameter 35mm, plate thickness 0.5mm)
Shape of roll block forming part: corrugated shape with an angle interval of 5 °, height of 3.5 mm
The clearance between the inner diameter surface of the stainless steel pipe and the mandrel: 0.3 mm
[00 18 ]
As a result of the experiment, it was confirmed that an uneven portion r having substantially the same shape as the corrugated shape of the forming portion 23 of the bending roll 1 was uniformly formed on the inner bending portion of the stainless steel pipe, and the appearance was also beautiful. In addition, it was confirmed that when the height of the corrugated shape of the molded part is 2.5 mm, the recessed part becomes large, and when the height is 4.5 mm, the convex part becomes sharp.
[00 19 ]
According to this metal pipe bending method, it is possible to perform a bending process in which a portion called a conventional wrinkle generated in a bending inner peripheral portion of the pipe is uniformly shaped as a corrugated uneven portion, and stable quality is achieved. You can get a product.
[Brief description of the drawings]
1 is a front view of a bending roll of a pipe bender to which the method of the present invention is applied. FIG. 2 is a plan view of FIG. 1. FIG. 3 is an explanatory view showing the arrangement of a roll body and a clamp die. Plan view [Fig. 5] Side view of roll block [Fig. 6] Cross-sectional view taken along line AA in Fig. 5 [Fig. 7] Illustration of metal pipe to be bent [Fig. 8] Outline diagram of conventional pipe bender [ Explanation of symbols]
1 → bending roll 10 → roll body 13 → notch portion 14 → concave arc portion 20 → roll block 22 → concave arc portion 23 → corrugated shaped portion 30 → clamp die p → metal pipe q → bending inner peripheral portion r → Concavity and convexity s → Length of the virtual center line of the bent part of the metal pipe

Claims (1)

A chuck portion having a mandrel shaft with a mandrel attached to the tip, a rotatable bending roll disposed on one side of the mandrel shaft, and the other side of the mandrel shaft is advanced and retracted. And a pipe bender comprising a clamping means including a clamping die that is rotatably provided within a predetermined angle range around the center of the bending roll, and a pressure die that is movable forward and backward in the same direction as the clamping die. Used, the metal pipe passed through the mandrel shaft is gripped by the chuck portion, the clamp die is advanced and the pipe is clamped by the bending roll, and then the metal pipe is clamped By rotating the bending roll at, the pipe is bent at a predetermined angle In bending method of manufacturing a pipe,
The bending roll has a corrugated shape with a constant height at a constant angular interval centered on the center of the roll on a concave arc formed substantially matching the outer diameter shape of the metal pipe, and the metal pipe Provided with a molded part provided so that the developed length of the uneven part formed on the inner peripheral part of the pipe and the length of the imaginary center line of the bent part of the pipe are substantially the same. When the bending roll is rotated while the gap between the inner diameter surface of the pipe made and the mandrel of the pipe bender is set to a predetermined size and the metal pipe is sandwiched, the bent inner circumference of the metal pipe is formed in the formed part. A metal pipe bending method characterized in that a plurality of concave and convex portions having substantially the same shape as the corrugated shape of the forming portion are formed on the inner peripheral bending portion of the pipe by pressing.

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