JPH01186221A - Method for bending tube - Google Patents

Abstract

PURPOSE:To smoothly bend a tube to a prescribed shape by moving a movable electrode to the side along a prescribed course to a lengthwise axial line. CONSTITUTION:When a holding electrode 11 and the movable electrode 15 are energized electrically through a control circuit 21 and a transformer 20, the area between both electrodes 11, 15 is subjected to red-heating. At this time, when the rear part of the tube 10 is advanced by advancing a holding means 22, the movable electrode 15 moves along a circular arc revolving round the center 19 of revolution and to a side position to a lengthwise axial line A. As a result, the tube 10 is bent at a red-heated area 29 and a part of the tube 10 in the front direction from this area displaces to the side to the lengthwise axial line A. After and before a bending operation ends, when refrigeration medium of high pressure is sent to a passage 27 of cooling means 26, it is ejected from a nozzle opening 28 to the internal circumferential surface of the tube 10 and the red-heated and bent area 29 is cooled nearly to the room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a method for bending a desired length of a tube.

(Prior art) Hot working is not suitable for completely bending thin-walled pipes made of iron, stainless steel, etc., which are the most widely used industrial materials, so cold working using a so-called signature tube bender is used. Generally adopted.

(Problem to be solved by the invention) However, in cold bending, if the bending radius becomes small, there is a risk of exceeding the limit of plastic workability determined by material purchase, so bending with a small bending radius is performed. This cannot be achieved without obstacles.

However, at present, there is a growing demand for bending processing with a narrow bending radius that exceeds the limit of plastic processing.

Therefore, several bending methods have been proposed to meet this need, but all of them tend to be complicated.

Therefore, the present invention is an extremely easy method for bending thin-walled pipes made of iron, stainless steel, etc., even when the bending radius is small and exceeds the limit of cold plastic forming. Its main purpose is to provide a method for curving a desired length.

(Means for Solving the Problem) □In order to achieve this objective, in the method of bending a desired length of a tube according to the present invention, the tube should be bent in the direction of the longitudinal axis before it is bent. A rear portion of the tube is gripped by a gripper located at the rear of the length. In addition, in front of the means 1, a support electrode is arranged which electrically contacts the outer circumferential surface of the tube and supports the tube VIIJ so that it can be advanced, and in front of the support W and the other, the tube A movable electrode is introduced which is guided to 5 so that it can be moved from this point to a lateral position with respect to the longitudinal axis +1]K while electrically contacting the outer peripheral surface and firmly gripping the tube. Said support!
When an electric current is passed through the tube Wt of the tube between the pole and the movable portion Wt, the tube wall is red-hot by resistive heating in the appropriate area between these two portions. Along with this, the gripper & is advanced, and by or at the same time as this advancement,
When the movable electrode is moved, the part of the tube in front of the red-hot area O is displaced forward with respect to the longitudinal axis.

(Function) According to the above-described method of bending a tube by this eruption ψ, the front part of the tube in front of the red-hot area is displaced laterally with respect to the longitudinal axis, so that the red-hot A bending of the tube occurs in the red-hot zone due to the lateral displacement relative to the rear part of the tube behind the heated zone. Generally, this red-hot area is small and the degree of curvature is also limited, but by advancing the rear portion of the tube as described above and moving the red-hot area rearwardly relative to the tube, By moving the movable electrode away from the longitudinal axis (of course by changing the direction of the movable electrode, if necessary), curvature can be achieved for large lengths of the tube. At this time, in order to obtain the desired curved shape, it is preferable that the width of the red-hot area be short, and therefore it is desirable to immediately cool the red-hot and curved area with an appropriate cooling means. , this cooler & is, for example, mounted inside the tube so that the cooling medium is ejected toward the inner periphery of the tube. The operation of achieving curvature in the red-hot zone while advancing the rear portion of the tube, as described above, can be accomplished either intermittently or continuously.

(Embodiment 1) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The bending process l1i-V for performing the bending process of a tube according to the present invention as shown in Figs. Prior to the bending process, the straight longitudinal axis of the tube contains a straight longitudinal axis.The symbol l) designates a support electrode that is fixedly placed in the area where the bending of the tube is to be achieved; A semi-cylindrical indentation enclosing the right half of 0 (as seen in Figure 9) and a semi-cylindrical depression enclosing the left half of 0. It consists of the left block/JF). Right block 4/3a 7 left block/31) means that Kuhomi lkomi and lkob or any one of them is I in at least a part of it, preferably on its entire surface.
Even if the outer circumferential surface of IFIQ comes into contact with the tfA, the pipe IO will not slide in the hole formed by the holes /Ua and /b, so it will not be supported. For example, they are pressed together by a pneumatic or hydraulic presser so as to be able to respect the direction of the longitudinal axis 1111h with respect to //.

Movable 11 located in front of support electrode 1/! The poles are arranged qualitatively similar to the supporting electrodes &l/, and the supporting electrodes//
O/ J & * / J b −/ J a −/
Kuhomi/4aw/Abs right block/? a, left block/f13f 伽λ,
In this movable electrode /S, the right block /'/& and the left block b can achieve the same mechanical contact with the outer peripheral surface of the support electrode /l, and these pulls / 7a, /7'b firmly grasp the tube IQ'jf, and when the movable W and other parts 15 move, the tube IO held by this 1
The parts are also pressed together by a pressing means 8 similar to the pressing hand Ji/da so as to move following the movement of the other movable part.

This movable electrode 1sld is shown in the sea diagram when it has been rotated by S degrees from the position immediately in front of the supporting electrode /l, for example, as shown in FIG. It is mounted so that it can rotate 90 degrees along an arc K to the position shown in FIG.

Right block/3a and left block is of support #electrode ii
b or either of them is electrically connected to one of both output terminals of the transformer -〇, and is connected to the right block of the movable *hts/? a and left block/'l'b or its chair V
Is electrically connected to the other of the output terminals of the transformer -00? be done.

Both input terminals of the transformer -0 are connected to an alternating current power source (not shown) via a control circuit 2. Transformer-〇 connects these electrodes// through supporting W pole// and movable electric &/S.
The specification is such that a low-voltage, large-current alternating current can be passed through the tube wall of the tube lO between /*/S.

The gripping hand plate disposed on the supporting electrode//Catlk side is stroked substantially in the same manner as the supporting electrode// and the movable electrode No. 5, and the supporting wQ//O/J a,/-
2b */J&, /JbK each corresponds to 4 Kuhomi 2J
a.

, 2Jbx right block-Hiro 11 left block Kohiro at-4
4. In this gripping means-2, the movable 1ir pole 15
Similarly, the right block and the left block 24 (a means gripping the tube/Qf with force and gripping means) -
The pressurizing means 1 and 1 are arranged so that when the tube IQ moves, the part of the tube IQ gripped by the gripping means also moves following the movement of the gripping means.
They are pressed together by pressure means JjK similar to those in 1. However, in this case, electrical contact such as the movable electrode 13 is not essential.

The gripping means 2 are disposed and distributed so that they can be advanced along the longitudinal axis by suitable means not shown.

The cooling pipe roller constituting the cooling means YtS inserted into the cooling pipe 6 extends in the axial direction. It has a number of nozzle openings S extending radially from the front end of the passageway 7 located on the ground. The cooling pipe IQ generally extends so that its nozzle opening S is located slightly in front of the supporting electrode 11, and receives high-pressure cooling from a suitable cooling medium source (not shown). Once introduced, this cooling medium is ejected radially from the nozzle aperture -IS to cool the inner periphery of the tube IQ. In addition, as is clear from the figure mentioned later, the cooling medium has a support t% indicated by the symbol -9.
Without cooling the tube wall of tube IQ in the zone just before //, zone CO? Since the cooling effect is achieved further forward, the cold pipe 6 is placed in the direction of the nozzle hole S.
It is desirable to have a large diameter portion 3Q that contacts or approaches the inner periphery of the pipe IO.

Regarding the pipe bending method using the above-described bending apparatus, the bending apparatus and the pipe IO are suddenly positioned in the position shown in FIG. 7 before the next bending process O. The support type &// surrounds and supports the tube io so that it is in electrical contact with the tube io and can be advanced in the direction of the tube ig (longitudinal axis m) with respect to this support electrode, and the movable i! The pole /S is brought into contact with the movable electrode IS of the bracket by the movement of the movable electrode IS so as to make electrical contact with 0.
As @ minutes follow, tube / 01-1. , Tsukushi and the encirclement grip. Moreover, the gripping means-1 is related to the movement of the gripping means.
Now, move the tube I so that the tube 700 portion to be gripped follows.
Grasp O tightly.

In the state shown in Fig. 1, the control circuit =) and the transformer λot
Through the support electrode ll and the movable electrode/3t - when electrically energized, these picture electrodes ll.

In the area between 13 (area # indicated by ? in Figure 1),
It! A low-voltage, high-power current 'Wl' flows through the tube wall of 10, and the tube of 0 is red-hot by resistance heating. At this point, by advancing the gripping means,
When the 6-way portion is moved forward, the movable electrode 73 is restrained so as to be able to turn around the turning center 19, so that the movable electrode 1S moves along the circular arc This causes a curvature of 0 in the red-hot area with the trowel, and the 0 part in front of this area is moved to the longitudinal axis of the trowel. Displaced laterally against.

If the above-mentioned bending work is completed in a short time, and at the time of completion or before it is completed, cooling means] 40 passages of high-pressure cooling # & body pipe are introduced, and this cooling medium is radiated from the nozzle opening 2S. direction, toward the inner peripheral surface of the tube IQ
% that red-hot and curved area? The food is cooled to near room temperature. This completes the first stage of the work.

Above mentioned nine work sister! In the step 1, the bending operation takes place only in a small area of the tube IO, but this first step is repeated by similar stages Nt-K, so that, for example, the gripping means] are The movable electrode i3 advances from the position shown in Fig. 1 @L to the position shown in Fig. 3, and the movable electrode i3 moves from the position shown in Fig. The conductive force is caused to move laterally with respect to the longitudinal axis along the axis. At this time, even if the movable electrode 15 is far away from the supporting electrode and therefore from the longitudinal axis as shown in FIGS. Located immediately in front of the front surface of the electrode IIO, the front @10 is maintained at a low temperature, so the work of bending the tube/Q tube with red heat is done at the position 30 of the upper diameter of the contaminant. and the position of the front surface of the support electrode (the area indicated by the symbol trowel in Figures 1 to 13). Thus, by stacking the bending operations of small areas at each stage, bending over the pinion length area as shown in Figure #I or Figure 3 is achieved.

In the above-mentioned bending process, the movable electrode 15 moves away from the support electrode l//, so that the current path along the tube lO (other than the red-hot area iron) between the movable electrode 15 and the support electrode // becomes long ( However, power loss occurs due to this current path, which increases in turn.Therefore, it is desirable to control the power in a control circuit corresponding to this.
However, since the current path other than the red-hot area 9 is maintained at a low WAK, its resistance is the same as that of the red-hot area 9. For example, the loss of power is reduced to nearly 70ths of a liter, so the power loss described above is often not a problem in practice. However, of course, better results can be obtained by reducing the power.

Bending by repeating short-time bending operations as described above, that is, bending by pulsed current, is performed when, for example, the bending radius of the center line of 0 is equal to the diameter of 0, or when the bending process of 0 is This should be applied to severe bending conditions, such as when the thickness is thin at the camellia end, and usually continuous bending can be used in which the rear part of the tube IO is continuously advanced while a current is passed continuously. . The details of this continuous bending process are clear from the bending process based on the short-time work described above. However, during continuous bending, there is a risk that the red-hot area iron will move in the forward direction and the relationship between the turning center 19 and the bending center will be damaged. Shift to the next O and Ryoden etc.//,
It is desirable to take countermeasures such as widening the distance between /SCI.

The embodiments described above can be modified to inoculate. For example, moving or displacing the cooler and roller, especially its nozzle opening, 2s position i'' in the direction of the longitudinal axis, cooling means] 6
operating continuously or intermittently, employing other types of cooling means, e.g. red-hot areas, 2? It is also in accordance with the present invention to omit the cooling means when the long-term radiation rIi is performed after the red-hot and bending work steps in the area=9 is kana p.

The movable electrode 15 is configured to move synchronously with the gripping means 2- by the advancement of the gripping hand plate-1, e.g. It may also be actively actuated by a mechanical or electrical transmission mechanism. Moreover, the movable electrode 15 has a turning center l? Instead of being configured to be able to turn around, for example, it may also be configured to be able to move along an appropriate path other than the turning path.

Furthermore, in order to prevent oxidation tubes in the red-hot area hump of the tube lθ, this area f can be covered with a suitable shielding gas. To this end, the red-hot area may be surrounded by a T-shielding casing into which a shielding gas is introduced, or alternatively, the red-hot area may be surrounded by a T-shielding casing into which a shielding gas is introduced.

K shielding gas may be blown into the red-hot area. Red hot area, 2? The entire device is housed in an airtight shielding housing and evacuated to a cPf vacuum, and in some cases, a shielding gas such as an inert gas is introduced into this vacuum atmosphere at low or high pressure. , which is highly desirable in some cases.

(Effect of tensioning) In this invention, since the area to be red-hot and bent can be localized, even if the tube expands and contracts in this area, other parts of the tube will not deform accordingly. Since roundness is not compromised by bending and the movable electrode is guided so that it can move laterally along a predetermined path with respect to the longitudinal axis, the large diameter of the tube allows for bending. Even if the radius is small, bending the specified shape may be difficult.
(It can be achieved.

[Brief explanation of the drawing]

Figures 1, 2, and 3 show the method of this development 9? The equipment for carrying out the bending is in the O state before the bending process, the state after the bending process has been performed by 5 degrees, and the ? Ojl: The bent state,
The drawings are mainly shown in longitudinal cross-sectional views. Xie Zhan Zu,
Figures S and 6 are views showing, primarily in cross section, the support electrode, movable electrode and gripping means used in the apparatus of Figures 1 to 3. In the drawing, IO is the pipe to be bent, ll is the support W
The pole, IS is a movable electrode, and here is a gripping means. Figure 4 for Figure 5 Figure 6 Procedural amendment (method) % formula % 1. Indication of the case 1988 Patent Application No. 9478 2. Name of the invention Method for bending pipes 3. Person making the amendment Case and Relationship Patent applicant address: 4-22-8 Sakurajosui, Setagaya-ku, Tokyo Name: Tsuji Giken Kogyo Co., Ltd. 4, Agent

Claims (1)

[Claims] In order to bend a desired length of the tube, a gripping means is located behind the length to be bent in the direction of the longitudinal axis of the tube prior to bending and grips the rearward portion of the tube. a support electrode that electrically contacts the outer surface of the tube in front of the gripping means and supports the tube so that it can move forward; and a support electrode that electrically contacts the outer circumferential surface of the tube in front of the support electrode. a movable electrode which is guided so as to be movable from this to a position lateral to the longitudinal axis while firmly gripping the tube; Passing a current through the wall
by, or simultaneously with, causing the tube wall to become red-hot by resistive heating in a suitable area between the supporting electrode and the movable electrode and advancing the gripping means in the direction of the longitudinal axis. Bending the tube, by moving a movable part into a position lateral to the longitudinal axis, such that a portion of the tube in front of the red-hot area is displaced laterally to the longitudinal axis. Method.