JP3394422B2 - Pipe expansion method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diameter expansion method comprising a method of forming a branch pipe by a burring process in the middle of a pipe and a method of forming one end of the pipe into a pipe expansion part having a larger diameter by pipe expansion. The present invention also relates to a diameter expanding device for carrying out the diameter expanding method, and particularly to a diameter expanding device suitable for surely forming a branch pipe or a pipe expanding portion having high circularity.

[0002]

2. Description of the Related Art As an example of a product subjected to burring processing, a gas insulated switchgear, which is one of substation facilities, is a pressure vessel whose inside is completely sealed, and a branch portion branched from a base material pipe. Each has a connected structure,
A burring process is performed to form a branch portion necessary for connecting the base material pipes.

Further, as an example of a product subjected to pipe expansion processing, in the case of a pipe gas insulated transmission line used for power transmission in a substation or the like, a structure in which the pipes are fitted to each other over a long distance and the like is connected. The joints required to connect the pipes are made by expanding one end of the pipes.

Here, a burring method and a pipe expanding method in the prior art are shown in FIGS.

First, a conventional burring method is shown in FIGS. 5 (a), 5 (b) and 5 (c).
That is, in the burring method shown in FIG. 5A (hereinafter referred to as the first conventional technique), the forming die 41 is inserted into the base material pipe 1 having a pre-drilled hole and is connected to the forming die 41. The shaft 42 is moved in the direction of the arrow to move the forming die 41 to the base material pipe 2
The branch pipe 2 is formed in the base material pipe 1 by drawing it from the inside to the outside. The first conventional technique is Japanese Patent Laid-Open No. Sho 54-54.
-137472 publication is mentioned.

In the burring method shown in FIG. 5 (b) (hereinafter referred to as the second conventional technique), a plurality of expandable and contractible molding pins 44 constituting the molding head 43 are preliminarily drilled. The base material pipe 1 is inserted from the center of the prepared hole into the inside, the molding pin 44 is projected so as to have the branch pipe inner diameter determined there, the molding head 43 is rotated around the axis as shown by the arrow in the figure, and the base material is The branch pipe 2 is formed by drawing the pipe 1 from the inside to the outside. Japanese Patent Application Laid-Open No. 57-115921 can be cited as the second conventional technique.

Further, in the burring method shown in FIG. 5 (c) (hereinafter, referred to as a third conventional technique), a roller 45 is inserted into a prepared hole provided in the base material pipe 1, and the roller 45 is inserted around the prepared hole. The along roller 45 revolves around the sun while rotating as shown by the arrow, and the roller 45 gradually expands the inner surface of the prepared hole to form the branch pipe 2. As the third conventional technique, Japanese Patent Laid-Open No. 8-
There is a 117877 publication.

On the other hand, a conventional pipe expanding method is as shown in FIGS. That is, in the pipe expanding method shown in FIG. 6 (hereinafter referred to as the fourth conventional technique), a plurality of divided pipe expanding pieces 51 are inserted into the pipe 6 and the pipe expanding pieces 5 are inserted.
A pipe expanding portion is formed in the pipe 6 by radially moving each one to push and expand the pipe 6.

Further, in the tube expanding method shown in FIG. 7 (hereinafter referred to as the fifth conventional technique), the revolvable roller 53 is connected to the pipe 6.
The pipe 6 is inserted into the pipe 6, and the inner surface of the pipe 6 is revolved along the circumference as shown by the arrow, and the pipe 53 is gradually expanded by the rotation of the roller 53 to form the pipe expansion portion 7 in the pipe 6.

[0010]

By the way, the prior art described above does not consider the following points. That is, in the first and second prior arts shown in FIGS. 5A and 5B, the contact resistance between the molding die 41 and the molding pin 28 and the inner surface of the branch pipe 2 causes scratches on the inner surface of the branch pipe. In addition, since work cracking is likely to occur due to stress concentration, a lubricant has been applied to alleviate the contact resistance. However, although there is no problem when the material of the base material pipe 1 for burring is a hard material, when it is a soft material such as an aluminum alloy material, even if a lubricant is applied to the inner surface of the branch pipe. There is a problem that it is impossible to prevent the occurrence of scratches.

Furthermore, the branch pipe inner diameter φd is the base material pipe inner diameter φD.
On the other hand, if an attempt is made to form a size of d / D = 1.0, in the first conventional technique, the forming die 41 cannot be inserted into the base material pipe 1, so that a branch pipe must be formed. I can't. Further, in the second conventional technique, the stress concentration cannot be suppressed only by applying the lubricant, and the branch pipe is cracked. Therefore, the first and second conventional techniques have a problem that the processing content is limited.

In the third prior art, since the roller 45 which rotates can reduce the contact resistance with the inner surface of the branch pipe, the occurrence of scratches can be prevented without applying a lubricant, and the burring of the soft material can be prevented. Processing is also possible, and the above d
It is also possible to perform processing that has a relationship of /D=1.0.

However, in the third conventional technique, as shown in FIG. 5 (c) in the process of forming the branch pipe 2,
Since the roller 45 rotates along the circumference of the prepared hole and gradually expands in the direction 46 of high rigidity with respect to the base material pipe 1, the root portion of the branch pipe 2 is buckled 47. there were.

On the other hand, in the fourth prior art shown in FIG. 6, when the pipe 6 is expanded, a gap 52 is formed between the divided expansion pieces 51, so that the pipe 6 has a polygonal shape. Will be formed. For this reason, when the expanded pipes are fitted to each other and joined by welding or the like, a gap is generated in the fitted parts, and there is a problem that the weldability deteriorates.

Further, in the fifth conventional technique shown in FIG. 7,
The roller 53 is drawn while expanding it along the inner surface of the pipe 6, but in the shape of the end of the pipe 6 after the drawing, a deformation 54 along the shape of the roller 53 occurs, and the roller 53 is processed into a desired shape. There was a problem I couldn't do.

Since the above-mentioned various problems occur, the first to fifth conventional techniques cause deformation during processing, and even if a branch pipe or an expanded pipe portion is formed, the deformation occurs. There was also a problem that the roundness accuracy was poor and the reliability of product quality was poor.

In view of the above problems of the prior art, the object of the present invention is to prevent the occurrence of scratches on the branch pipe during burring, and to prevent cracks due to stress concentration by making the plate thickness uniform. It is another object of the present invention to provide a method for expanding the diameter of a pipe, and another object of the present invention is to provide a method for expanding the diameter of a pipe which can prevent the expansion portion from being deformed during the pipe expanding process to have a desired shape.

Another object of the present invention is to provide a diameter expanding device capable of accurately carrying out the above method.

[0019]

According to the present invention, in a method of forming a branch pipe on a surface of a base material pipe by burring, a) a base hole preliminarily provided in the base material pipe is rotatable about an axis. A pin for burring which is formed so as to be rotatable and swingable at an arbitrary diameter, and b) is then in contact with the arc side in the minor axis direction of the prepared hole, While swinging outwardly on the arc side, the arc side in the minor axis direction is expanded and expanded, respectively, and c) the pin is brought into contact with the arc side in the major axis direction in the prepared hole. Side outwardly pushing and expanding the circular arc side in the major axis direction, and then d) swinging the pin while pressing the pin in the prepared hole to the circular arc side in the major axis direction. With this, gradually pull it out of the base material pipe,
The part of the branch pipe is formed by erecting the expanded arc side of the longitudinal axis in the prepared hole on the surface of the base metal pipe, and e) thereafter, the pin is expanded in the prepared hole. While swinging while pressing against the circular arc side in the axial direction, it is gradually pulled out to the outside of the base metal pipe, and the expanded short side circular arc side of the prepared hole is raised on the surface of the base metal pipe to remove the remainder of the branch pipe. It is characterized by forming.

Further, according to the present invention, in the pipe expanding method of forming a pipe expanding portion having a diameter larger than the pipe diameter on the outer peripheral portion of the pipe by a pipe expanding process, a) is preliminarily rotatable in the pipe about an axis and a fulcrum portion. Insert a pin for pipe expansion that is rotatable around the center and is rotatable with an arbitrary diameter,
b) Next, by rotating the pin, the tip end of the pin is brought into contact with and pressed against the peripheral wall of the pipe, and in that state, the pin revolves around the pipe axis and moves along the pipe axis, and By gradually increasing the revolution radius of the, the peripheral wall of the pipe is bulged to form the expanded portion of the desired diameter,
c) When the tip of the expanded portion is formed to the tip side of the pipe, the revolution and the movement are performed while the tip of the pin is pressed against the peripheral wall of the pipe, and the pin is in an angular direction coinciding with the axial center of the pipe. It is characterized in that the tip of the expanded pipe portion is formed straight along the axial center of the pipe by gradually returning the pin to a revolving radius and gradually increasing the revolution radius of the pin.

Further, according to the present invention, a lift table that can be raised and lowered, a rotary shaft that is rotatably attached to the lift table about an axis, a pin for burring processing and a pipe expanding process, and the pin is rotated about the axis. A slide base attached to the rotary shaft and provided between the slide base and the rotary shaft while being freely rotatable and rotatable about a fulcrum of the pin, and the slide base being orthogonal to the rotary shaft. A feed mechanism that moves in the direction and adjusts the distance between the central axis of the rotary shaft and the fulcrum of the pin, and a control means that controls each of the lifting platform, the rotary shaft, the pin, and the feed mechanism via a drive source. It is characterized by having.

[0022]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 show an embodiment of a diameter expanding device for carrying out the method of the present invention. That is, in this diameter expanding device, the rotating shaft 12 is attached to the lift table 11 that can be lifted and lowered. The rotary shaft 12 is rotatably supported in the lift 11 via a bearing 13, and is rotated by a motor (not shown). As shown in FIG. 2, the elevating table 11 is connected to an elevating mechanism 14 controlled by the controller 15 and moves up and down according to the amount of movement of the elevating mechanism 14. The elevating mechanism 14 is composed of a cylinder or the like.

On the other hand, a pin 1 for forming a branch pipe by burring or for forming an expanded portion by expansion.
6 is supported by the slide base 17. A shaft holder 18 is fixed to the bottom surface of the slide base 17 so as to face each other, and a pin 16 is rotatably provided around a shaft at a midpoint of a shaft 19 mounted between the shaft holders 18 via a bearing 20 made of a roller bearing. It is supported. Therefore, an insertion hole for the pin 16 is formed at a midway position of the shaft 19 in a direction orthogonal to the axial direction of the shaft 19, and the pin 16 is attached to the bearing 20 fitted in the insertion hole. It is designed to rotate freely around.

A mounting bracket 21 for a motor is fixed to one end of the slide base 17, a motor 22 is installed on the bracket 21, and an output shaft of the motor 22 is connected to the shaft 19 via a coupling 23. It is connected. Then, when the shaft 19 is rotated by the drive of the motor 22, the pin 16 and the shaft 19 are rotated.
As shown by the alternate long and short dash line in FIG. 2, the fulcrum portion 24 intersecting with the axis of is pivoted clockwise and counterclockwise. That is, the pin 16 is the slide base 1.
7 is attached so as to be rotatable about an axis and rotatable about a fulcrum portion 24.

A feed mechanism for moving the slide base 17 is provided between the slide base 17 and the rotary shaft 12. In the feed mechanism, a base 25 is fixed to the tip of the rotary shaft 12, and a motor 27 for a feed screw is installed on the base 25 via a mounting bracket 26. A feed screw 29 is connected to the output shaft of the motor 27 via a coupling 28. The lead screw 29 is the base 2
By the bearing unit 30 provided at the bottom of 5,
It is rotatably supported in a direction orthogonal to the axis of the rotating shaft 12, and is arranged so that its axis intersects with the axis of the rotating shaft 12. ? Further, a nut portion 31 is provided at an intermediate position of the feed screw 29 so as to be screwed with the feed screw 29, and the nut portion 31 is fixed on the slide base 17.
The pin 16 supported by the slide base 17, the feed screw 29 of the feed mechanism, and the rotary shaft 12 are on the same straight line in FIG.

When the feed screw 29 is rotated by the drive of the motor 27, the nut portion 31 moves left and right together with the slide base 17 as shown in FIG. The distance between the parts 24 can be adjusted arbitrarily.

Therefore, when the distance between the axis of the rotary shaft 12 and the fulcrum 24 of the pin 16 is adjusted by driving the feed screw 29, when the rotary shaft 12 is driven, the center of the rotary shaft 12 will be centered. The pin 16 revolves around a desired diameter.

At this time, the feed screw 2 is attached to the bottom of the base 25.
The guide rails 32 hang down so as to be arranged on both sides of the slide guide 9, and slide guides 33 that slide with the guide rails 32.
Is fixed on the slide base 17, and when the slide base 17 is moved by driving the feed screw 29, the slide base 17 is moved stably.

Further, the control unit 15 includes not only the lifting mechanism but also the motor 22 for rotating the pin 16 and the feed screw 2.
The motor 27 that drives 9 and the motor (not shown) that drives the rotary shaft 12 are controlled in accordance with the burring process and the pipe expanding process, respectively.

Next, an embodiment of the method of the present invention will be described with reference to the description of the operation of the diameter expanding device of the embodiment. First, the pipe used in the gas insulated switchgear is the base material pipe 1, and the base material pipe 1
The burring process for forming the branch pipe 2 will be described below. When the burring process is performed, the prepared hole 3 is formed in the base material pipe 1 in advance as shown in FIG. This pilot hole 3
Has an elliptical shape such that the periphery of the prepared hole is located on the same plane when opened in the base material pipe 1, its center position coincides with the axial center of the base material pipe 1, and the ellipse major axis is Along with the axis of the base material pipe 1, the base material pipe 1 is arranged so that the ellipse minor axis extends along the radial direction.
Are arranged orthogonally to the axis center of.

While the base material pipe 1 is set at a predetermined position, the feed screw 29 is driven to set a predetermined distance between the shaft center of the rotary shaft 12 and the fulcrum 24 of the pin 16 in the diameter expanding device. 2 and the pin 16 is in a vertical position with a solid line position as shown in FIG. 2 (see FIG. 1).

At this time, the elevating table 11 is lowered and the pin 1
6 is inserted as it is into the base material pipe 1 so as to coincide with the center of the prepared hole 3 of the base material pipe 1, and then the pin 16 is moved to contact the arc side in the minor axis direction of the elliptical prepared hole 3. Then, while pushing the arc side outward in this state, the pin 16 is swung by driving the rotary shaft 12 so as to repeat forward rotation and reverse rotation within a desired angle range, as shown in FIG. As described above, the arc-shaped side of the elliptical pilot hole 3 in the minor axis direction is pushed and expanded as shown by the hatched portion 4 to perform the primary processing. At this time, if it is pushed and spread along the peripheral wall of the pilot hole 3 at one time, the thickness of the material forming the periphery of the pilot hole 3 may be uneven, but the pin 16 is only on the arc side in the minor axis direction of the pilot hole. By oscillating while pressing and spreading, the material can be brought close to the thin portion. The portion of the base material pipe where the thickness around the pilot hole 3 is thin is based on data generated from the experience of burring up to now, and particularly in the elliptical pilot hole 3, the arc side in the minor axis direction. And the arc side in the major axis direction.

Further, the pin 16 surely makes the arc side closer to the oblique line portion 4
The control unit 15 drives the feed screw 29 by the motor 27 to form the shape as shown in FIG.
By controlling so that the distance from the axis center of the and gradually increases, and also controlling the swing radius to gradually decrease, it is expanded like the shaded portion 4.

When the expansion of the shaded portion 4 is completed, the opposite side is similarly processed, and the other side is expanded like the shaded portion 4 to complete the primary processing. At the end of the primary processing, the prepared hole 3 becomes as shown in FIG. 3B, and the expanded portions 4a and 4b are formed.

After forming the portions 4a and 4b which are expanded to the arc side in the minor axis direction of the prepared hole 3 in this way, this time, as shown by the shaded portions 5 and 5 in FIG. Secondary processing is performed by sequentially pushing and expanding the remaining portion of the hole 3 in the arcuate direction in the major axis direction in the same manner. Also in this case, the pin 16 swings while expanding the arcuate side of the prepared hole 3 in the major axis direction, whereby the material can be brought close to the thinned portion. That is, in the material forming the periphery of the pilot hole 3 in the burring process, the boundary portion between the arc side in the minor axis direction and the arc side in the major axis direction of the pilot hole 3 is likely to be thin, and therefore the material is brought close to that portion. To make the thickness uniform.

After that, the shaft 22 is driven by the motor 22, and the pin 16 is rotated to a specific angular position as shown in FIG. 3 (c). Thereafter, the pin 16 is pressed against the arcuate side 5 of the pilot hole 3 which is expanded in the major axis direction while keeping the specific angular position, and at the same time, the rotary shaft 12 is driven to revolve and swing within a predetermined angular range. While moving, the elevating mechanism 14 gradually elevates the elevating base 11 and pulls it out from the base material pipe 1, and raises the expanded arc side 5 in the longitudinal direction of the prepared hole, whereby a part 2 of the branch pipe 2 is formed.
a is formed. Further, the arc side 5 on the opposite side is similarly raised to form a part 2a of the branch pipe. In this case, at the time when the branch pipe parts 2a, 2a are formed by raising each arc side in the longitudinal direction of the prepared hole, both
The space between a and 2a is set to a size corresponding to the diameter of the branch pipe 2.

Then, this time, the shaft 19 is driven by the motor 22 to return the pin 16 to its original position and hang it down as shown in FIG. 3 (d).
As shown in (f), the pin 16 is pressed against the expanded arc side in the minor axis direction of the pilot hole 3 and the swing range is gradually increased so that the arc side of the minor hole 3 in the minor axis direction is also increased. In the same manner, it is started up to form the remaining portion 2b of the branch pipe 2, and the final processing is performed. That is, the feed screw 29 is controlled so that the distance between the shaft center of the rotary shaft 12 and the shaft center of the pin 16 is gradually increased, and the portions 4a and 4b that are expanded in the minor axis direction of the prepared hole 3 are expanded.
However, the remaining portions 2b and 2b of the branch pipe 2 are gradually formed by sequentially rising as shown in FIGS. 3D, 3E, and 3F, and thus the forming process of the branch pipe 2 is completed. In the final processing, the part of the prepared hole 3 expanded in the short axis direction of the prepared hole 3 is started up. At this time, if it is actually started up within a wider angle range than the expanded part. When the branch pipe 2 is formed, the continuous portion between the rising portion in the short axis direction and the rising portion in the long axis direction can be smoothed.

As described above, according to the method of the present invention, the pin 16 is pressed and swung against the prepared hole 3 having an elliptical shape, as shown in FIG.
As shown in (a), the arc side in the minor axis direction is pushed and expanded like the shaded portions 4 and 4 to form the pushed portions 4a and 4b on the arc side, and at the same time, the material is moved to both sides of the arc side, , 16 are operated in the same manner to push the arc side in the major axis direction as shown by the shaded portions 5 and 5 in the same manner as shown in FIG. 3B to form the pushed portion on the arc side and at the same time Since the material is also drawn to both sides of the side, the material can be made to come to the part where the wall thickness becomes thin as a result. After that, as shown in FIG. The parts 1a and 2a of the branch pipe 2 are formed by rising from the pipe 1, respectively, and the arc side expanded in the minor axis direction is further formed from the base material pipe 1 to form the remaining parts 2b and 2b of the branch pipe 2. Thereby, the branch pipe 2 is formed in the base material pipe 1.

Therefore, in the method of the present invention, the material for forming the pilot hole 3 is formed by independently expanding the arc side in the minor axis direction and the arc side in the major axis direction with respect to the periphery of the pilot hole 3. Since the branch pipe 2 is formed by adjusting the wall thickness uniformly, and then independently raising the arc side in the major axis direction and the arc side in the minor axis direction, the circumference of the prepared hole can be pushed or spread all at once. Alternatively, the problems of the first to third conventional techniques forming the branch pipe can be solved by continuously expanding. That is, it is possible not only to prevent stress concentration from occurring locally in the branch pipe 2 as in the first and second conventional techniques, but also to roll the rollers 4 along the inner surface of the prepared hole.
Unlike the third prior art in which the branch pipe is expanded by 5, it is possible to prevent the root portion of the branch pipe 2 from buckling and deforming 47, and it is possible to surely form the branch pipe with a good roundness.

Moreover, since the pin 16 is rotatably mounted, it is possible to reduce the contact frictional resistance with the peripheral wall of the prepared hole 3 during processing, and the base material pipe 1 is a soft material such as an aluminum alloy. However, there is no risk of scratches.

Further, since the pin 16 has a shape smaller than that of the pilot hole 3 and the branch pipe 2 is formed by swinging the pin 16 in the pilot hole 3 or the like, an inner diameter equal to the inner diameter D of the base metal pipe is formed. It can be easily formed even with the branch pipe 2 having.

Next, the pipe expanding process for forming the pipe expanding portion 7 at one end of the pipe 6 will be described with reference to FIG. In this case, the axis of the rotary shaft 12 and the axis of the pin 16 are aligned,
In that state, the pins 16 are inserted into the pipe 6 by the descending operation of the elevating table 11. Next, the pin 16 is rotated by driving the motor 22 so that the pin 16 comes into contact with the peripheral wall of the pipe 6, and the feed screw 29 is driven by the motor 27 so that the fulcrum portion 24 of the pin 16 has a predetermined distance from the rotary shaft 12. So that In this case, the distance between the pin fulcrum portion 24 and the rotary shaft 12 is determined by the size of the diameter of the pipe 6 and the size of the rotation angle of the pin 16.

After that, the rotary shaft 12 is driven, and FIG.
As shown in, the pin 16 rotates so as to push the peripheral wall of the pipe 6 toward the outside a and gradually rises as shown by the arrow b. At that time, by gradually increasing the radius of rotation of the pin 16, As shown in FIG. 3B, a gradually expanded bulging portion 7a is formed along the axial direction on the outer circumference of the pipe 6. That is, the pin 16 makes an orbit around the axial center of the pipe 6 and a movement along the axial direction of the pipe 6 while the tip end portion presses the peripheral wall of the pipe 6, and the orbital radius gradually increases. By making it larger,
The peripheral wall of the pipe 6 is formed with an inclined expanded portion 7a that gradually bulges outward from the diameter of the pipe.

Then, when the size of the inclined expanded portion 7a reaches a desired radial dimension, the dimension is maintained so as to be maintained.
Pushing force of pin 16 against peripheral wall of pipe 6 and pin 1
By gradually raising the elevating table 11 with the same rotating force of 6, the straight pipe expanding portion 7b connected to the inclined pipe expanding portion 7a is formed.

Furthermore, the tip of the straight expanded portion 7b is the pipe 6
4C, when the pin 16 is lifted so as to be pulled out from the pipe 6 as the lifting table 11 moves up and down, the pin 16 is moved along the axis of the pipe 6 as shown in FIG. 4C. While gradually returning to the position of (1) and gradually increasing the rotation diameter of the pin 16 while returning to the position, the tip of the straight expanded portion 7b is formed straight. That is, pin 16
Performs revolving around the pipe axis and movement along the pipe axial direction with its tip pressed against the pipe peripheral wall, while gradually returning to the angular direction that coincides with the pipe axial center and revolving. By gradually increasing the radius, the tip of the straight pipe expanding portion 7b is formed straight along the axial center of the pipe 6.

Thus, by gradually returning the pin 16 to the position parallel to the axis of the pipe 6 and increasing the revolution radius, the tip of the straight expanded portion 7b is formed straight along the axis of the pipe 6. Therefore, it is possible to prevent the deformation 54 along the shape of the roller 53 from occurring as in the fifth conventional technique, and it is possible to obtain a pipe expanding portion having a desired shape.

Further, while the pin 16 is pressed outward against the peripheral wall of the pipe 6, the pin 16 is gradually raised while being rotated in the pipe 6, thereby forming the inclined expanded portion 7a and the straight expanded portion 7b. In addition, it is possible to form the expanded portion having a high roundness, and the polygonal shape is not formed unlike the fourth prior art.

As a result, in the present invention, the branch pipe 2 can be formed without stress concentration at the local portion of the branch pipe 2 during burring and without causing the root portion of the branch pipe 2 to buckle and deform. Therefore, at the time of pipe expansion processing, the straight pipe expansion part 7
Since the expanded portion can be formed without deforming the end of b and forming a polygonal shape, product quality can be improved.

As described above, since the diameter expanding device of the embodiment has the lifting table 11, the rotary shaft 12, the slide base 17, the processing pin 16, and the control section 15, the burring method and The pipe expanding method can be performed accurately.

[0050]

As described above, according to claim 1 of the present invention, the arc side in the minor axis direction is expanded and expanded by pushing and swinging the pin against the prepared hole of the base material pipe. The material is moved to both sides, and then the pin is similarly pushed to expand the arc side in the axial direction, and the material is moved to both sides of the arc side. As a result, the material is moved to the portion where the wall thickness becomes thin around the prepared hole. After that, the arc side expanded in the long axis direction is raised from the base metal pipe to form part of the branch pipe, and the arc side expanded in the short axis direction is raised from the base metal pipe. Since it is configured to form the remaining portion of the branch pipe, it is possible not only to prevent stress concentration in the local portion of the branch pipe, it is possible to prevent the root portion of the branch pipe from buckling deformation, It is possible to reliably form a branch pipe with good roundness, and It is possible to achieve the above.

According to the second aspect, when the tip of the pipe expanding portion is formed up to the tip side of the pipe, by gradually returning the pin to a position parallel to the axis of the pipe and increasing the revolution radius, Since the tip of the pipe expanding portion can be formed straight, it is possible to obtain a pipe expanding portion having a desired shape with high roundness without deformation, and it is possible to improve product quality.

According to a third aspect of the present invention, an elevating table which can be raised and lowered, a rotary shaft which is attached to the elevating table so as to be rotatable around an axis, a pin for burring processing and a pipe expanding process, and the pin are attached to the shaft. It is rotatable around and rotatably supported around a fulcrum of the pin, and is provided between the slide base attached to the rotary shaft and the slide base and the rotary shaft to rotate the slide base. A feed mechanism that moves in the direction orthogonal to the axis and adjusts the distance between the central axis of the rotary shaft and the fulcrum of the pin, and each of the lifting platform, the rotary shaft, the pin, and the feed mechanism are controlled via drive sources. Since the control means is provided, the diameter expansion method according to claims 1 and 2 can be carried out accurately.

[Brief description of drawings]

FIG. 1 is a front view for explaining an essential part showing an embodiment of a diameter expanding device for carrying out the method of the present invention.

FIG. 2 is a side view for explaining the same as the whole.

FIG. 3 is an explanatory view of a burring process showing an embodiment of the method of the present invention in the order of steps.

FIG. 4 is an explanatory view of pipe expanding processing showing another embodiment of the method of the present invention in the order of steps.

FIG. 5 is an explanatory diagram showing first to third conventional techniques.

FIG. 6 is an explanatory diagram showing a fourth conventional technique.

FIG. 7 is an explanatory diagram showing a fifth conventional technique.

[Explanation of Codes] 1 ... Base material pipe, 2 ... Branch pipe, 2a ... Part of branch pipe, 2b ...
Remainder of branch pipe, 3 ... Elliptical pilot hole, 6 ... Pipe, 7 ...
Expanding part, 7a ... Inclined expanding part, 7b ... Straight expanding part, 11 ...
Elevating table, 12 ... Rotating shaft, 14 ... Elevating mechanism, 15 ... Control part, 16 ... Pins for burring process and pipe expanding process, 24
... fulcrum part of pin 16, 17 ... slide base, 19 ... shaft, 22 ... motor, 27 ... motor, 29 ... feed screw.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoo Oga 1-1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Kokubun Plant, Hitachi Ltd. (72) Inventor Yasuhiro Nonaka 1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture No. 1 Incorporated company Hitachi Ltd. in Kokubun factory (72) Inventor Satoru Shirata 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Incorporated company Hitachi Ltd. in Kokubun factory (72) Incorporator Naohiro Tsukao Aiase, Hitachi City, Ibaraki Prefecture 2-9-1, Machi, Hitachi Equipment Engineering Co., Ltd. (72) Inventor Keiichi Nakamura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Production Technology Laboratory (72) Inventor Toshiya Teramae Yokohama, Kanagawa City, Totsuka-ku, Yoshida-cho, 292, Hitachi, Ltd., Production Engineering Laboratory (56) References Japanese Patent Laid-Open No. 7-204752 (JP, A) JP 8-117877 (JP, A) JP 9-70625 (JP, A) JP 7-39946 (JP, A) JP 8-267130 (JP, A) (58) Survey Fields (Int.Cl. ⁷ , DB name) B21D 51/16 B21D 19/04 B21D 19/08 B21D 39/10

Claims (3)

(57) [Claims] 1. A method for forming a branch pipe on the surface of a base material pipe by burring, comprising: a) being rotatable and rotatable around an axis in an elliptical pilot hole previously provided in the base material pipe. And a pin for burring that is swingably formed with an arbitrary diameter is inserted. B) Next, with the pin in contact with the arc side in the minor axis direction of the prepared hole, the outside of the arc side While swinging while pressing in one direction, the arc side in the minor axis direction is pushed and expanded respectively, and c) Further, with the pin in contact with the arc side in the major axis direction in the prepared hole, outwardly of the arc side. After swinging while pressing to expand the arc side in the long axis direction respectively, d) rock the pin while pressing it against the expanded arc side in the long axis direction in the prepared hole and at the same time as outside the preform pipe Gradually pulling out to the above-mentioned widened axial direction in the prepared hole The arc side of is raised above the surface of the base material pipe to form a part of the branch pipe, and e) After that, the pin is shaken while being pressed against the arc side in the minor axis direction expanded in the prepared hole. The pipe is characterized in that it is moved and gradually pulled out of the base metal pipe, and the arc side in the prepared hole in the direction of the short axis which is expanded is raised above the surface of the base metal pipe to form the remainder of the branch pipe. Diameter method. 2. A method for forming a pipe expanding portion having a diameter larger than the pipe diameter by pipe expanding processing on the outer peripheral portion of the pipe, comprising: a) being rotatable in the pipe in advance about an axis and rotating around a fulcrum. Insert a pipe expanding pin that is rotatably and freely rotatable with any diameter. B) Then, by rotating the pin, the tip of the pin is brought into contact with and pressed against the peripheral wall of the pipe, and in that state the pin is pushed. While revolving around the pipe axis and moving along the pipe axial direction, and gradually increasing the revolution radius of the pin, the peripheral wall of the pipe is bulged to form an expanded portion of a desired diameter, c). At the time when the tip of the expanded portion is formed to the tip side of the pipe, the revolution and the movement are performed while the pin tip is pressed against the pipe peripheral wall, and the pin is gradually moved in an angular direction that coincides with the axial center of the pipe. While returning A method for expanding the diameter of a pipe, characterized in that the tip of the expansion portion is formed straight along the axis of the pipe by gradually increasing the revolution radius of the pin. 3. An elevating table that can be raised and lowered, a rotary shaft that is rotatably attached to the elevating table about an axis, a pin for burring processing and a pipe expanding process, and the pin is rotatable about the axis. Also, while rotatably supporting the fulcrum of the pin as a center, a slide base attached to the rotating shaft,
A feed mechanism that is provided between the slide base and the rotary shaft, moves the slide base in a direction orthogonal to the rotary shaft, and adjusts the distance between the central axis of the rotary shaft and the fulcrum of the pin.
A pipe diameter-expanding device, comprising: a lift, a rotary shaft, a pin, and a control means for controlling each of the feed mechanisms via a drive source.