KR101798213B1 - Jig for bending and enlarging diameter and Method of bending and enlarging diameter using the same - Google Patents

Abstract

The bending diffusing jig according to the present invention comprises:
A plurality of mandrels 110 rotatably connected in series and a punch 120 connected to the mandrel 110 so as to be pivotable forwardly of the mandrel 110 to function as an expanding function.
Also, according to the bending expansion method using the jig for bending expansion according to the present invention,
A first shaping step of expanding a front portion of the straight pipe 400 and a second shaping step of forming the bent pipe 500 by bending the pipe 400 having been subjected to the first shaping step upwardly, And a secondary molding step of inserting the bending diffusing jig 100 into the front part and drawing the bending diffusing jig 100 out.
Therefore, according to the present invention, when bending and expanding the pipe 400, when the upper and lower molds 310 and 320 are closed, the bending expanding jig 100 is pushed into the pipe 400 It is possible to mold the curved tube 500 that conforms to the forming portions 315 and 325 of the upper mold 310 and the lower mold 320. [

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a bending expanding method using a bending expansion jig and a bending expansion jig,

The present invention relates to a bending expansion method using a bending expanding jig and a bending expanding jig, and more particularly, to a bending expansion method capable of shortening a process, And a bending expanding method using a bending expanding jig and a bending expanding jig.

Hereinafter, a bending expansion method according to the background art will be described with reference to the accompanying drawings.

Fig. 1 is a perspective view showing a rear portion of a bending pipe manufactured by the bending expansion method according to the background art, Fig. 2 is a perspective view showing a front portion of a bending pipe manufactured by the bending expansion method according to the background art, FIG. 4 is a process diagram showing a process of expanding a pipe after the pipe is bent by the bending expansion method according to the background art, and FIG. 5 FIG. 6 is a bend tube manufactured by the bending expansion method according to the background art, in which (a) and (b) show different bending angles, Will be described together with an example showing a state in which the rear end of the flange does not coincide with the flange.

Generally, a bending pipe (bending pipe) 10 as shown in Figs. 1 to 3 is formed in an exhaust pipe of a vehicle, so that it can be installed in a vehicle without interference. That is, the curved pipe 10 is used to connect two pipes that are inclined at different angles.

Since the curved tube 10 is formed in such a manner that the front end portion 15 is expanded as compared with the rear end portion 17 in the bent state, the other pipe can be received and connected to the front end portion 15. As shown in FIG. 6, the flange 20 is attached to the rear end portion 17 so that the flange 20 can be coupled to the other pipe having the flange.

A method of manufacturing the curved tube 10 will be described with reference to FIGS. 4 and 5. FIG.

First, a linear pipe 5 is disposed between the upper mold 30 and the lower mold 40, in which the molding portions 33 and 43 are formed so as to conform to the bend 10. The upper mold 30 and the lower mold 40 are coupled to each other to bend the pipe 5 to form the bending tube 10.

After the bending step, the mandrel 50 is inserted into the front portion of the bend 10 in a state where the upper mold 30 and the lower mold 40 are engaged, so that the front portion is first expanded. At this time, since the rear part of the forming parts 33 and 43 is also expanded, the rear part of the pipe 5 is expanded when the mandrel 50 is inserted. After the rear portion is thus expanded, the mandrel 50 is retracted, and a primary expansion step is performed.

After the first expansion step, the upper mold 30 and the lower mold 40 are separated to separate the expanded bending tube 10, and then the hammer is inserted into the front portion of the bending tube 10, .

After the secondary expansion step, the hammer is again inserted into the front portion of the bending tube 10 and is re-charged so that a third expansion step is performed.

After the third expansion step, as shown in Fig. 5, a finishing step is performed in which the front portion and the rear portion of the bending tube 10 are cut so as to be perpendicular to the center line c, and then subjected to a chamfering process.

According to the background art, there are the following problems.

First, as shown in FIG. 4, when the mandrel 50 is inserted to the front of the bending tube 10 and the front portion is expanded in a state where the pipe 5 is upwardly bent to form the bending tube 10, A step H is formed between the front portion and the rear portion of the bending tube 10 as shown in Figs. 1 to 3 and the rear portion of the step 11 is provided with a plurality of A wrinkle 13 is generated. At this time, the step 11 and the corrugation 13 are formed on the upper portion and the left and right sides of the bending tube 10 and are not formed on the lower portion because the bending portion 10 is bent upward and the lower portion is pulled, The molding portion 43 of the mold 40 is brought into close contact with the molding portion 43 of the mold. The upper portion of the curved tube 10 is curled so that a portion of the upper mold 30 that is not in close contact with the forming portion 33 is formed and this phenomenon is caused by the space H formed between the step 11 and the corrugation 13, Are formed on the upper and left and right sides of the bending tube (10). Since the enlarged portion F formed in front of the curved tube 10 can not be machined at one time, the step 11 is protruded to a higher height through the second expansion step and the third expansion step do. When the curved pipe 10 is connected to the exhaust pipe, the inner side surface is bent due to the step 11 and the corrugation 13, and such a curvature is generated when the exhaust gas, noise, Thereby causing a problem that smooth discharge is difficult. Accordingly, there is a problem that the vibration and noise of the vehicle are increased, the exhaust gas flows back into the engine in a state where the exhaust gas is filled in the exhaust pipe, and the inside of the engine is contaminated with soot.

The bending angle a and the shape (diameter and shape) of the bending tube are deformed at the time of the second bending step and the third bending step, There was a problem. Therefore, in the finishing step, as shown in Fig. 5 (a). the cutting jig is fabricated on the basis of the center line c of the bending line 10 shown in Fig. 5 (a), so that the bending angle of the bending line 10 shown in Fig. 5 (b) When the front portion and the rear portion are cut, they are cut in a state inclined to the center line c shown in Fig. 5 (b). Therefore, as shown in FIG. 6, a phenomenon that does not conform to the flange 20 occurs. In addition, since it is impossible to produce a product having an exact shape and size according to a design dimension, there is a problem that compatibility is lacking. In other words, when the other pipe is received inside the front end portion 15, the size of the expanded portion F is smaller or larger than that of the other pipe, which is not consistent.

Thirdly, since the work process is complicated as compared with the present invention, there is a problem that productivity is low due to difficulty in quick work.

(Document 1) Korean Patent Registration No. 10-1087517 (November 22, 2011) (Document 2) Korean Patent Publication No. 10-2015-0011836 (February 02, 2015) (Document 3) Korean Patent Registration No. 10-1471123 (December 03, 2014)

The bending expansion method using the jig for bending expansion and the jig for bending expansion according to the present invention will be described as follows.

First, a step is protruded between the front part and the rear part of the bending tube at the time of expansion after bending the pipe, and wrinkles are generated at the rear part of the step. Therefore, the curvature is formed on the inner surface of the bend due to the step and wrinkle, and such bending has a problem that it is difficult to smoothly discharge the exhaust gas or the noise or vibration of the vehicle due to interference. Therefore, noise and vibration of the vehicle are increased, and the exhaust gas is flowed back to the engine, thereby deteriorating the performance of the engine.

Secondly, the bending angle and the shape (diameter and shape) of the bending tube are deformed at this time when the bending section is formed in front of the bending tube through the second bending step and the third bending step. Therefore, a phenomenon that does not conform to the flange occurs as shown in Fig. In addition, since it is impossible to produce a product having an exact shape and size according to a design dimension, there is a problem that compatibility is lacking. That is, there is a problem in that when the other pipe is received inside the front end portion, the size of the expanded portion is smaller or larger than that of the other pipe.

Thirdly, since the work process is complicated as compared with the present invention, there is a problem that productivity is low due to difficulty in quick work.

The bending diffusing jig according to the present invention comprises:

A plurality of mandrels rotatably connected in series and punches pivotally connected to the forefront of the mandrel so as to function as an expanding function.

In addition, the mandrel is a spherical shape passing through the inside of the bending tube, and the punch is formed so as to be wider than the mandrel and to conform to the extension of the bending tube.

In addition, the mandrel and the punches are connected in series by a chain.

The bending expansion method using the bending expansion jig according to the present invention uses the bending expansion jig,

A first molding step of expanding a front part of a straight pipe, a second molding step of forming a bending pipe by bending the pipe through the first molding step, inserting the bent bending jig into a front part of the bending pipe, .

Further, in the primary molding step,

The upper part and the lower part are connected to each other after the piping is disposed between the upper and lower molds with the molding part extending forward, and the front part of the piping is expanded by inserting the punches in front of the piping.

Further, in the secondary molding step,

The pipe having undergone the primary molding step is disposed between an upper mold and a lower mold having a molding part formed to conform to a bending tube so that the upper mold and the lower mold are coupled to each other so that the pipe is formed into a bending tube, And a secondary molding step of inserting the jig and drawing it out.

The bending expansion method using the bending expansion jig and the bending expansion jig according to the present invention has the following effects.

First, according to the present invention, since the upper and lower molds are closed when the pipe is bent and then expanded, the bending expanding jig is pushed into the inside of the pipe and then drawn out. can do. That is, a plurality of mandrels disposed at the rear of the jig for bending expansion are pushed outward while being pushed outwardly while moving along the inside of the bending tube while being pivoted, and the punch is inserted into the inside of the bending tube to form the extended portion. There is an effect that wrinkles are not generated, and it is smoothly manufactured with a designed size. In addition, when the bobbin thus manufactured is mounted on an exhaust pipe of a vehicle, exhaust gas, noise and vibration can be discharged quickly without interference, so that noise and vibration of the vehicle can be reduced and the exhaust gas flows back to the engine, It is possible to prevent the phenomenon of deteriorating the performance.

Secondly, in the case of the finishing step, since the bends are manufactured in the same shape and dimensions, if a jig is cut so as to be perpendicular to the center line of any one bend, all the bends produced are perpendicular to the center line by the jig Can be cut. Therefore, it is possible to form a curved tube which is brought into close contact with the flange as shown in FIG. 13, and when the other pipe is received inside the front end portion, there is an effect that it can be tightly coupled.

Thirdly, since the present invention is made up of the primary molding step, the secondary molding step, and the finishing step, the productivity can be improved by reducing the number of steps compared to the background art.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing a rear portion of a bending pipe manufactured by a bending expansion method according to the background art; Fig.
2 is a perspective view showing a front portion of a bending pipe manufactured by the bending expansion method according to the background art;
Fig. 3 is a cross-sectional view showing a bending pipe manufactured by the bending expansion method according to the background art, cut along the longitudinal direction. Fig.
4 is a process diagram showing a process in which a pipe is expanded after the pipe is bent by the bending expansion method according to the background art.
Fig. 5 is a view showing a bending angle bending method according to the background art, in which (a) and (b) show different bending angles.
6 is a view showing a state where a rear end of a bending tube is not fitted with a flange, which is a bending tube manufactured by the bending expansion method according to the background art.
7 is a sectional view showing a jig for bending distri- bution according to the present invention.
8 is a process diagram showing a primary molding step in a bending expansion method using a jig for bending expansion according to the present invention.
9 is a process diagram showing a secondary molding step in a bending expansion method using a jig for bending expansion according to the present invention.
10 is a process diagram showing a third molding step in a bending expansion method using a jig for bending distri- bution according to the present invention.
11 is a perspective view showing a rear portion of a bending tube manufactured by a bending expansion method using a jig for bending expansion according to the present invention.
12 is a perspective view showing a front portion of a bending tube manufactured by the bending expansion method using the jig for bending expansion according to the present invention.
13 is a sectional view showing a state in which a rear end of a bending tube manufactured by a bending expansion method using a jig for bending distri- bution according to the present invention conforms to a flange.

(Jig for bending expansion)

In order to solve the above-described problems, the construction of the jig 100 for bending expansion of the present invention will be described.

FIG. 7 is a cross-sectional view of the jig for bending expansion according to the present invention.

Bending accuracy tolerance jig 100 according to the present invention, as shown in Figs. 11 and 12, as for forming a bent pipe 500 is bent concavely upward, the width in the front part than the rear portion of the bent pipe 500, And the inner side surface and the outer side surface of the curved tube 500 can be smoothly formed into a round shape.

To this end, the present invention is configured as follows.

A plurality of mandrels 110 connected in series are constituted, and a punch 120 is formed which is connected to the front side of the mandrel 110 disposed at the forefront (the expanded portion side of the bend) to function as an expanding function. At this time, the mandrel 110 and the punch 120 are rotatably connected to each other so as to pass through the inside of the curved pipe 500.

The mandrel 110 is formed in a spherical shape passing through the inside of the curved tube 500 so as to be in contact with the inner surface of the curved tube 500 and to expand the corrugation or the step. And is formed so as to coincide with the extension 510 of the curved tube 500 as shown in FIG.

The outer surface of the punch 120 and the mandrel 110 may be connected to the chain 130 so as to be freely rotatable between the mandrel 110 and the punch 120 as shown in FIG. For example, through holes 113 and 123 are formed in the direction in which the mandrel 110 and the punch 120 are arranged, and the chain 130 passes through the through holes 113 and 123. One end of the chain 130 passing through the rearmost mandrel 110 is connected with a latching portion 115 which is hooked on the through hole 113. The other end of the chain 130 passing through the front side of the punch 120 The engagement portion 125 engaged with the through-hole 113 is connected. The engaging portions 115 and 125 may be, for example, pins or plates that can be engaged with the through-holes 113 and 123, respectively.

(Bending Expansion Method Using Jig for Bending Distortion)

A bending expansion method using the bending expanding jig 100 according to the above construction will be described as follows.

FIG. 8 is a process diagram showing a first molding step in a bending expanding method using a bending expanding jig according to the present invention, and FIG. 9 is a view showing a second molding step in a bending expanding method using a jig for bending expansion according to the present invention. FIG. 10 is a process diagram showing a third molding step in the bending expanding method using the jig for bending expansion according to the present invention, and FIG. 11 is a view showing the manufacturing process by the bending expansion method using the jig for bending expansion according to the present invention. FIG. 12 is a perspective view showing a front portion of a bending pipe manufactured by the bending expanding method using the bending expanding jig according to the present invention, and FIG. 13 is a perspective view showing the bending expanding jig according to the present invention. Sectional view showing the state that the rear end of the bending pipe manufactured by the bending expansion method conforms to the flange.

11 and 12, the bending expansion method using the jig for bending expansion according to the present invention is for molding a bend 500 which is concavely bent upward, wherein the bend 500 has a front portion And an inner side surface and an outer side surface of the curved tube 500 can be smoothly formed into a round shape.

To this end, the bending expansion method is performed as follows in the present invention.

A first molding step of expanding the front part of the straight pipe 400 is performed and the pipe 400 having been subjected to the first molding step is concavely bent upward to be formed into a curved pipe 500 and then the curved pipe 500 The bending expanding jig 100 according to the present invention is inserted into the front part of the bending expanding jig 100 and then taken out. Then, a finishing step is performed in which the front portion and the rear portion of the bending tube 10 are cut so as to be perpendicular to the center line (c), then ground and then subjected to a chamfering process.

8, after the piping 400 is disposed between the upper mold 210 and the lower mold 220, the width of the front portion of the molding portions 213 and 223 is extended, The lower part 210 and the lower part 220 are coupled to each other and the front part of the pipe 400 is expanded by inserting the punch 230 in front of the pipe 400. The forward and backward movement of the punch 230 may be performed by a hydraulic cylinder.

The forming portions 213 and 223 are formed in the shape of a groove corresponding to the pipe 400 and open at the upper surface of the upper mold 210 and the upper surface of the lower mold 220, 225 are formed. At this time, in the forming portions 213 and 223, the width of the groove is set to a size capable of pressing the pipe 400. Therefore, the outer diameter is pressed by about 1 to 3 mm.

8, the piping 400 is disposed between the upper mold 210 and the lower mold 220, and then the upper mold 210 and the lower mold 220 are coupled to each other. The punch 230 having a width wider than the inner diameter of the pipe 400 is inserted at the front of the pipe 400 at a price. At this time, since the pipe 400 is pushed by the upper mold 210 and the lower mold 220, there is no phenomenon that the pipe 400 is pushed backward. Thus, it is possible to form the pipe 400 having the rear portion extended.

9, the pipe 400 having undergone the primary molding step is inserted into the upper mold 310 and the lower mold 320 in which the molding portions 315 and 325 are formed to conform to the curved pipe 500, Respectively. The upper mold 310 and the lower mold 320 are coupled to each other so that the pipe 400 becomes the bending tube 500 and the bending diffusing jig 100 is inserted in front of the bending tube 500 Out. At this time, lubricating oil is applied to the inner surface of the bending tube 500, so that it is possible to easily insert and pull out the bending diffusing jig 100.

That is, the upper mold 310 has a groove-shaped molding portion 315 opened to the front and rear, and an inner upper surface 317 is formed to be convex downward. The lower mold 320 has a molding portion 325 formed on the upper surface thereof and conforming to the molding portion 315, and an inner bottom surface 327 is recessed downward. The front portions of the forming portions 315 and 325 are extended to fit the extending portion 510 disposed in front of the curved tube 500.

Therefore, since the pipe 400 extending forward is disposed between the upper mold 310 and the lower mold 320 and the upper mold 310 and the lower mold 320 are coupled to each other, the pipe 400 is connected to the molding portions 315 and 325 And the bending tube 500 is formed.

When the bending expanding jig 100 is pushed toward the front of the pipe 400, as shown in FIG. 10, the mandrels 110 are pivoted upward and the inner surface of the pipe 400 is pushed outward to be evenly spread do. The punch 230 expands the front portion of the curved tube 500 to allow the extension 510 to be formed. Thereafter, the center of the mandrel 110 disposed at the foremost rear is passed through the bend 500. Thereafter, when the bending expanding jig 100 is pulled forward, the mandrels 110 are compressed again inside the bending tube 500 and are uniformly deformed, thereby preventing a wrinkle or a step from being formed. And, there is an advantage that it can be molded according to the exact shape and dimensions as designed. At this time, the bending expanding jig 100 can be advanced or retracted using a hydraulic cylinder.

Thus, when the upper mold 310 and the lower mold 320 are separated from each other, the curved tube 500 is formed. Since the length is longer, the length is adjusted in the next finishing step.

In the case of the finishing step, since the curved tubes 500 are manufactured in the same shape and dimensions, if a jig is cut so as to be perpendicular to the center line c of one of the curved tubes 500, 500 may be cut at right angles to the center line (c) by the jig. Accordingly, a curved line 500 that is in close contact with the flange 600 can be formed as shown in FIG.

According to the present invention, when bending the pipe 400 and then expanding it, the bending expanding jig 100 is pushed into the inside of the pipe 400 with the upper and lower molds 310 and 320 closed, It is possible to mold the curved tube 500 that conforms to the forming portions 315 and 325 of the upper die 310 and the lower die 320. [ That is, a plurality of mandrels 110 disposed at the rear of the bending expanding jig 100 are pushed outwardly while moving along the inside of the curved pipe 500 while rotating, and the punch 120 is passed through the bending pipe 500, So that the enlarged portion 510 is formed. That is, bending and expanding operations of the pipe 400 can be performed at the same time. Therefore, there is an advantage that the curved tube 500 can be manufactured smoothly with a designed size without causing a step or wrinkle.

Accordingly, when the bent pipe 500 thus manufactured is mounted on an exhaust pipe of a vehicle, the exhaust gas, the noise and the vibration can be quickly discharged without interfering with each other. Therefore, noise and vibration of the vehicle can be reduced, So that the performance of the engine can be prevented from deteriorating.

In addition, since a plurality of the curved pipes 500 can be manufactured according to the design dimensions, there is an advantage that the flange 600 can be easily fitted to the prescribed flange 600, and the advantage that the flange 600 can be tightly coupled when the other pipe is received inside the front end have.

In addition, since the present invention is performed as a primary molding step, a secondary molding step, and a finishing step, there is an advantage that productivity can be improved by reducing the number of steps compared with the background art.

(Example 1)

1. Primary molding step;

A pipe 400 having an inner diameter of 50 mm, an outer diameter of 54 mm and a length of 150 mm and a material of which is SUS 429 is compressed by the upper and lower molds 210 and 220 and the punch 230 is inserted forward of the pipe 400, A pipe 400 having an inner diameter of 50 mm, an outer diameter of 54 mm, and a length of 150 mm was provided. At this time, the punch was compressed by a force of 200 kg for 10 seconds by using a hydraulic cylinder, and withdrawn.

The thus-formed pipe 400 was made to have an elliptical shape having a width of 60 mm and a height of 55 mm, a thickness of 1 mm, and a length of 50 mm. In addition, the front portion of the expanded portion was made to have an inner diameter of 48 mm, a thickness of 1 mm, and a length of 100 mm.

2. Secondary molding step;

The pipe 400 is pressed in a state of being accommodated in the forming parts 315 and 325 of the upper mold 310 and the lower mold 320 so that the bending angle a is bent to be 60 degrees to mold the curved pipe 500 . At this time, the bending expanding jig 100 was pushed in under a force of 350 kg for 10 seconds using a hydraulic cylinder, and then taken out. The bending diffusing jig 100 is made of a heat-treated steel SM45C having a diameter of 49 mm with a mandrel 110 having two spherical mandrels 110 connected thereto. The punch 230 was made of heat treated steel SM45C having a width of 61 mm, a height of 56 mm, and a length of 50 mm and having an elliptical cross section. The chain 130 also uses heat treated steel SM25C.

The enlarged portion 510 has an inner side width of 61 mm, a height of 56 mm, a thickness of 0.5 mm and a length of 50 mm. The front portion of the extension 510 has a curved surface 500 having an inner diameter of 49 mm and a thickness of 0.5 mm. .

3. Finishing steps

After cutting a point 5 mm from both ends of the bending part 500, the bending part 500 was ground by performing a chamfering operation.

(Comparative Example 1)

1. Bending step

A pipe having an inner diameter of 50 mm, an outer diameter of 54 mm, a length of 150 mm and a material of SUS 429 was pressed by upper and lower molds to be a curved pipe. The bending angle at this time was set to be 60 degrees.

2. Primary expansion step

After the bending step, the front portion of the pipe was expanded using a mandrel. At this time, a mandrel having a width of 57 mm, a height of 55 mm and a length of 50 mm was used. The mandrel having an elliptical cross section was used. Thus, a curved tube with an elliptical expanding portion could be obtained.

3. Secondary expansion step

After the primary expansion step, a hammer having a cross section of an oval shape and having a width of 59 mm and a height of 55.5 mm was pushed into the expansion part.

4. Phase 3 expansion

After the secondary expansion step, a hammer having a cross section of an oval shape and having a width of 61 mm and a height of 56 mm was pushed into the extension section. Thus, the expanded portion had a left-right width of 61 mm, an inner height of 56 mm, and a thickness of 0.1 mm, and a rear portion of the expanded portion was a curved tube having an inner diameter of 48 mm and a thickness of 1 mm.

5. Finishing steps

After cutting a point 5 mm from both end portions of the bending tube, the bending work was performed after grinding, thereby completing the manufacture of the bending tube.

(Experimental Example 1)

The appearance and the dimensions and shape of Example 1 and Comparative Example 1 were inspected using measurement equipment.

In Example 1, the inner side and the outer side were smoothly formed into a round shape, and the same product as the actual size was obtained. However, in Comparative Example 1, a step and a wrinkle were formed in the bend, and the inner diameter, the outer diameter and the bending angle were different from the actual dimensions.

(Experimental Example 2)

A pipe having a length of 1,500 mm was connected to both side ends of the bending pipe 500 according to Example 1 and Comparative Example 1. Each pipe was shaped so as to conform to both ends of the bending tube. The flange 600 is welded to the rear end portion 530 and is then bolted to the other pipe provided with the flange. Then, 20,000 cc of dry ice was supplied from one pipe to the other pipe.

Further, the time when the vibrations were transmitted to the opposite end was measured by hitting the end of the pipe supplied with the dry ice with a hammer every 3 seconds.

Then, noise of 50 dB was generated at the end of the pipe supplying the dry ice, and noise transmitted to the end of the opposite side was measured. At this time, a sound insulation plate having a width of 3,000 mm is closed around the curved pipe 500, so that noise transmitted through the ambient air can be blocked as much as possible.

Example 1
Comparative Example 1
The amount of dry ice that has passed through the pipe for 10 minutes

18,000cc
13,000cc
Amount of dry ice remaining in the tube for 10 minutes

25cc
540cc
Time the vibration is transmitted

0.23 sec
1.53 sec
Amount of noise transmitted over 10 minutes

47dB
38dB

As a result of the experiment, it is possible to rapidly discharge the dry ice since the curved line 500 according to the first embodiment does not have steps and wrinkles, and the extension 510 of the curved line 500 can accurately It can be confirmed that the amount of dry ice that is leaked as compared with Comparative Example 1 can be reduced. In addition, it was confirmed that Embodiment 1 can quickly transmit vibration and noise. Therefore, it was found that the present invention can realize the above effect.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not for purposes of limiting the technical idea of the present invention, but are intended to be illustrative, and therefore, the scope of the technical idea of the present invention is not limited by these embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: Jig 110 for bending expansion: Mandrel
113: through hole 115:
120: Punch 123: Through hole
125: engaging portion 130: chain
210: image forming part 213: forming part
215: extension part 220: bottom part
223: forming part 225:
230: punch 310: upper mold
315: forming part 317: inner upper surface
320: Lower mold 325: Molding section
327: inner side 500: bend
510: extension part 520: front end part
530: rear end

Claims (6)

delete delete delete A plurality of mandrels 110 rotatably connected in series,
And a punch (120) connected to the mandrel (110) so as to be pivotable forwardly of the one disposed at the foremost position and performing an expanding function,
The mandrel 110 is formed in a spherical shape passing through the inside of the curved pipe 500 and the punch 120 is formed to have a width larger than that of the mandrel 110, Lt; / RTI >
The mandrel 110 and the punch 120 are bending expanding methods using a bending expanding jig 100 connected in series by a chain 130 ,
A primary molding step of expanding a front portion of the linear pipe 400,
The pipe 400 having been subjected to the primary molding step is concavely bent upward to be formed into a curved pipe 500 and then inserted into the front portion of the bending pipe 500 for drawing out the bending expanding jig 100 Comprising a car forming step ,
Wherein the primary forming step comprises:
The upper mold 210 and the lower mold 220 are coupled to each other after the piping 400 is disposed between the upper mold 210 and the lower mold 220 where the molding portions 213 and 223 extend forward, 400, the punch 230 is inserted to extend the front portion of the pipe 400,
Wherein the secondary molding step comprises:
The piping 400 having been subjected to the primary molding step is disposed between the upper mold 310 and the lower mold 320 having the molding portions 315 and 325 formed to conform to the curved tube 500, The lower mold 320 is coupled to the pipe 400 so that the pipe 400 becomes the bending tube 500 and the bending diffusing jig 100 is inserted in front of the bending tube 500 and then drawn out, Wherein the bending expanding jig is a bending expanding jig. delete delete

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