JPS6178510A - Manufacture of branch pipe - Google Patents

Abstract

PURPOSE:To obtain a branch pipe, having a branched part uniform in the wall thickness in its peripheral direction and free from a welding line, by forming a high-frequency heating coil, to be arranged in the vicinity of a primary hole bored in a base pipe, into a saddle shape whose coil width is changed along the peripheral direction. CONSTITUTION:A high-frequency heating coil 5 is disposed at the peripheral part of a primary hole bored in a base pipe 1, to heat a burr-forming part by supplying a high-frequency current. The coil width of coil 5 is changed along the peripheral direction so that the coil width B1 on a plane 12, containing the axial center of pipe 1 and that 4a of a burring punch 4, is larger than the coil width B2 on a plane 13 passing through the axial center 4a and intersecting orthogonally with the plane 12. When the forming part is heated, the punch 4 is extracted from the hole to form a branched part 2A. At that time, a plastic deformation at stress-concentrating points 2a, 2c is restrained, and a branch pipe 10A uniform in the wall thickness at each part 2a-2d along the peripheral direction of part 2A, is obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing a branch pipe, and in particular, the present invention relates to a method for manufacturing a branch pipe, and in particular, the plate thickness of the branch pipe portion is substantially uniform along the circumferential direction, and the thickness of the branch pipe is substantially uniform along the circumferential direction, and the thickness of the branch pipe is substantially uniform along the circumferential direction, and there is no weld line. The present invention relates to a method for manufacturing a branch pipe, which is intended for manufacturing a branch pipe having a branch pipe portion without the need for a branch pipe.

[Background of the invention]

Conventionally, as a method for manufacturing a branch pipe having a branch pipe section,
For example, as shown in Japanese Patent Application Laid-Open No. 58-53330, branch pipes are formed by press working from plate materials, but
In branch pipes manufactured using this method, the plate thickness of the branch pipe parts is not uniform along the circumferential direction, and there are weld lines that are unstable in metallographic structure, so the reliability of the product strength is not guaranteed. There were some problems that needed further improvement.

[Purpose of the invention]

The present invention solves the above-mentioned problems of the prior art and manufactures a branch pipe having a branch pipe portion in which the plate thickness of the branch pipe portion is substantially uniform along the circumferential direction and there is no weld line. The object of the present invention is to provide a method for manufacturing a branch pipe that can be used to produce a branch pipe.

[Summary of the invention]

The structure of the method for manufacturing a branch pipe according to the first invention is such that a pilot hole is bored at a predetermined position, and a high-frequency heating coil is arranged near the peripheral edge of the pilot hole. A method for manufacturing a branch pipe in which a branch pipe is formed by heating to a processing temperature with a heating coil, pulling out a burring punch inserted into the main pipe from the prepared hole and performing burring processing, in which a high-frequency heating coil is used. The width of the coil on a plane including the axis of the main pipe and the axis of the burring punch is larger than the width of the coil #A on the plane passing through the axis of the burring punch and perpendicular to the plane. This is a saddle-shaped high-frequency heating coil in which the coil width changes along the circumferential direction.

Further, the configuration of the method for manufacturing a branch pipe according to the second invention is such that a pilot hole is bored at a predetermined position, and a high-frequency heating coil is arranged near the peripheral edge of the pilot hole. In the method for manufacturing a branch pipe, the branch pipe portion is formed by heating the main pipe to a processing temperature by the high-frequency heating coil, and pulling out a burring punch inserted into the main pipe from the prepared hole to perform burring processing, the method comprising: high-frequency heating. The coil is placed on a plane that is perpendicular to the plane that passes through the axis of the burring punch such that the coil gap between the prepared hole edge on a plane that includes the axis of the main pipe and the axis of the burring punch is The saddle-shaped high-frequency heating coil is formed so that the coil gap can be changed along the circumferential direction so that the coil gap between the coil gap and the prepared hole edge becomes larger.

More specifically, the high-frequency heating coil used in the process of high-frequency heating the periphery of the pilot hole of a main pipe with a pilot hole bored at a predetermined position is a ring-shaped saddle-shaped high-frequency heating coil. Along the circumferential direction of the heating coil, a change in the cross-sectional area or a change in the coil gap between the main pipe and the high-frequency heating coil is formed. By varying the deformation resistance in the circumferential direction of the hole, it is possible to control the plate thickness strain at the branch pipe section. Basic matters related to the invention will be explained using drawings.

FIG. 5 is a perspective view showing a branch pipe having a branch pipe section manufactured using a conventional method for manufacturing a branch pipe, and FIG. 6 is a charcoal t
4 Processing temperature showing the relationship between processing temperature and deformation resistance of steel pipes -
The deformation resistance diagram, Figure 7, shows the shape of the saddle-shaped high-frequency heating coil.
Coil width-heating @ straight line diagram showing an example of the relationship between coil width and heating temperature, No. 0. 8 is a coil gambu heating temperature diagram showing an example of the relationship between the coil gap and the heating temperature of a saddle-shaped high-frequency power heating coil.

Branch pipe section 2 manufactured by a conventional branch pipe manufacturing method
As shown in FIG.
The thickness of the plate is not uniform in the circumferential direction, and strain is concentrated near points 2a and 2C on the cross section including the axis of the main pipe 1 and the axis of the branch pipe part 2, resulting in sexual deformation. There is a tendency to become larger,
The plate thickness at points 2a and 2C is thinner, and 2b in the direction perpendicular to this
, 2d.

The plate thickness at the point has become thicker. Furthermore, there was a weld line 11 that was unstable in terms of metallographic structure.

Therefore, in the present invention, the periphery of the pilot hole of the main pipe in which the pilot hole has been bored is heated with a saddle-shaped high-frequency heating coil, the burring punch is pulled out from the pilot hole, and the branch pipe portion is formed by burring. In addition to eliminating rainbow weld lines, the deformation at points 2a and 2a, where fertile deformation is large, is suppressed (the means for suppressing this will be described later), and the deformation at points 2b and 2a, where greasy deformation is small, is suppressed. In particular, the plate thickness of the branch pipe portion is formed to be approximately uniform along the circumferential direction.

Incidentally, the deformation resistance of a carbon steel pipe, which is an example of the material of the main pipe 1, depends on the processing temperature, as shown in FIG. That is, when the processing temperature is low, the deformation resistance is large, whereas when the processing temperature is high, the deformation resistance is small and the amount of plastic deformation is large. Therefore, when forming the branch pipe portion, the processing temperature near the points 2a and 2C where strain is concentrated is set to 2b.
, by making it lower than point 2a, the amount of plastic deformation at points t, 2a, and zC can be suppressed, and the amount of deformation at points 2b and 2a can be increased, and the plate thickness of the branch pipe section can be reduced in the circumferential direction. I tried to make it almost uniform along the line.

As a means of changing the processing temperature along the circumferential direction of the branch pipe portion by lowering the processing temperature of points 2a and 2C, the processing temperature of points 2a and 2C, and the processing temperature of points 2b and 2d, the inventors have developed Two means were generated.

■ The coil @ of the saddle-shaped high-frequency heating coil is changed along the circumferential direction.

An example of the relationship between the coil width and the heating temperature is shown in Figure 7. As the coil width becomes wider (that is, the cross-sectional area becomes larger), the density of the high-frequency current becomes smaller and the heating temperature becomes lower. Therefore, the shape of the saddle-shaped high-frequency heating coil is made such that the coil width is widened in the portion corresponding to the 20 points 2a (i.e., on the plane including the axial center of the main tube 1 and the axial center of the burring punch), and 2b, In order to narrow the coil @ in a portion corresponding to point 2a (i.e., on a plane passing through the axis of the burring punch and perpendicular to the plane),
The coil width is changed along the circumferential direction.

■ The coil gap between the saddle-shaped high-frequency heating coil and the pilot hole edge is varied along the circumferential direction.

An example of the relationship between the coil gap and the heating temperature is as shown in FIG. 8. As the coil gap becomes thicker, the heating efficiency deteriorates and the heating temperature decreases. Therefore, the shape of the saddle-shaped high-frequency heating coil is such that the coil gap between the coil gap and the prepared hole edge is large in the portion corresponding to the points 2a and 2C, and the coil gap is large in the portion corresponding to the points 2a and 2C.

The branch pipe according to the first invention is shown in FIG. 1 so that the coil gap can be changed along the circumferential direction so that the coil gap between the prepared hole edge and the portion corresponding to point 2a becomes smaller. Manufacturing method O Example 1 - A front cross-sectional view showing the branch pipe manufacturing apparatus used, FIG. 2 is a plan view of the branch pipe manufacturing apparatus according to FIG. 1, and FIG. 3 is the −■
FIG. 4 is a perspective view showing a branch pipe manufactured by the branch pipe manufacturing apparatus according to FIG. 1.

1 is a main pipe with a pilot hole drilled, 3 is a fixing clamp for fixing both ends of this main pipe 1, 4 is a burring notch in the shape of a truncated cone for burring, and 4a is this burring notch. 4 is an axis, 6 is a rod to be fixed to the burring punch 4, 5 is a high frequency current generated by a high frequency source 8, and is used to flow through a water cooling cable 9;
This is a saddle-shaped high-frequency heating coil for high-frequency heating the peripheral edge of the pilot hole of the base 1f1, that is, the burring forming part. The coil 'A B 1 on the plane 12 including the
(through a) The coil width B on the plane 13 orthogonal to the plane 12 also increases: the coil width changes along the circumferential direction.

The operation of manufacturing a branch pipe from the main pipe 1 using the branch pipe manufacturing apparatus configured in this manner will be described.

First, we drilled the pilot hole! After both ends of W1 are fixed using fixing clamps 3, a burring punch 4 is inserted into the main pipe 1, and the punch is fixed to the rod 6. A saddle-shaped high-frequency heating coil/v5 is set near the circumference R of the pilot hole.

Here, when this branch pipe manufacturing apparatus is turned on, a high frequency current flows through the saddle-shaped high frequency heating coil 5, and the burring forming part is high frequency heated. When the core portion is heated to a predetermined temperature, a machining force 7 is applied to the rod 6 while maintaining this machining temperature, and the burring punch 4 is pulled out from the prepared hole while the branch pipe portion 2 People are molded. In this case, at points 2a and 2C where strain is concentrated, the coil width B
By increasing 1 (〉Carp 4!), the processing temperature is kept low, so plastic deformation in the vicinity of which the deformation resistance is strong is suppressed.The burring punch 4 is completely removed from the prepared hole. When it is pulled out, the manufacturing equipment is turned off.

When the processed product is taken out after it has cooled down, as shown in FIG.
, a branch pipe 10A having substantially uniform plate thickness at the Zd portion is obtained.

Next, a specific example will be described.

Outer diameter of main pipe 1: 50ELOwφ, plate thickness: 9.5 mm
, a branch pipe part 2 with an inner diameter of 320 mgφ is attached to a carbon steel pipe with a length of 4 m.
Explain the case of molding a person.

The processing temperature-deformation resistance diagram of this carbon steel pipe is shown in FIG. 6 above.

The saddle-shaped high-frequency heating coil 5 has an inner diameter of approximately 380 mm,
Coil width Bl = 40112Il, B2 = 18mm. Therefore, as can be seen from FIG. 7, the processing temperature is about 700C near points 2a and 2C, while it is about 900C near points 2b and 2a, which are perpendicular to these points (coil gap low). When there is a temperature difference of 200 C in this way, as is clear from FIG. 6, the ratio of deformation resistance is about twice.

The frequency of high-frequency heating was constant at 2-5KH2.

The burring punch 4 has an outer diameter of 320Wφ and a half apex angle of 3.
It has a 0° truncated cone shape, and the processing force 7 is approximately 28 tf.
And so.

When the above-mentioned conditions were set and the carbon steel pipe was subjected to burring using the branch pipe manufacturing apparatus shown in FIG.
Molding of A could be carried out.

According to the embodiment described above, there are the following effects.

(1) Since the plate thickness of the two branch pipe members can be formed to be substantially uniform along the circumferential direction, the reliability in terms of strength of the ten branch pipe members is improved.

(2) Integral molding is possible through ffi processing, eliminating weld lines, improving metallographic reliability. (3) A branch pipe of 10A can be formed in one process, reducing processing man-hours. .

In this embodiment, the case where a carbon steel pipe is used as the material of the main pipe 1 has been described, but the present invention is not limited to carbon steel pipes, but can also be applied to all metal pipes such as stainless steel pipes and alloy steel pipes. This can be applied when manufacturing branch pipes using this method.

Next, an embodiment of the method for manufacturing a branch pipe according to the second invention will be described.In the embodiment according to the first invention, 2a.

As a means of lowering the processing temperature at the 20 points i2b and the processing temperature at point 2d and changing the processing temperature along the circumferential direction of the branch pipe section, the coil width of the saddle-shaped high-frequency heating coil 5 is changed in the circumferential direction. However, as mentioned above, it is also possible to change the coil gap between the saddle-shaped high-frequency heating filter and the prepared hole edge along the circumferential direction as another means. .

Therefore, in this embodiment, the high-frequency heating coil (see FIG. 2) is connected to a coil gap gI between the axial center of the main pipe 1 and the prepared hole edge on the plane 12 including the axial center 4a of the burring punch 4. However, the plane 1 is passed through the axis 4a of the burring punch.
2 and the pilot hole edge on the plane 13 orthogonal to the coil gap g! It is also shaped so that it can be made thicker.

To explain with a specific example, in the same manner as in the above specific example, the outer diameter is 5.
08. When forming two branch pipes with an inner diameter of 320 wφ on a carbon steel pipe related to the main tube with a plate thickness of 9.5 m and a length of 4 m, the inner diameter is approximately 380 flφ and the coil gap g
+=lo■+g2=A saddle-shaped high-frequency heating coil that can be set to 6 cods (the coil width is constant at 40 cods) is used.

The processing temperature at this time is 2a, as shown in Figure 8.
, around 2C point is about 700C, 2b, around 26 point is about 90C
0C), there is a temperature difference of 1i200C between the two, and the ratio of deformation resistance is approximately doubled as in the previous embodiment. The carbon steel pipe was burred using a high-frequency heating frequency of 2.5 KHz, a burring punch 4 having a truncated conical shape with an outer diameter of 1320 m and a half-vertex angle of 30°, and applying a processing force 7 of approximately 28 tf. However, similarly to the embodiment described above, a branch pipe in which the thickness of the two branch pipe parts in the circumferential direction was substantially uniform could be formed.

〔Effect of the invention〕

As explained in detail above, according to the present invention, it is possible to manufacture a branch pipe having a branch pipe portion in which the plate thickness of the branch pipe portion is substantially uniform along the circumferential direction, and there is no weld line. A method for manufacturing a branch pipe can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view showing a branch pipe manufacturing apparatus used for carrying out the method for manufacturing a branch pipe according to the first invention, and FIG. 2 is a plan view of the branch pipe manufacturing apparatus according to FIG. Fig. 3 is a sectional view taken along the line ■-■ in Fig. 1, Fig. 4 is a perspective view showing a branch pipe manufactured by the branch pipe manufacturing apparatus according to Fig. 1, and Fig. 5 is a FIG. 6 is a perspective view showing a branch pipe having a branch pipe portion manufactured by a conventional branch pipe manufacturing method.
The processing temperature-deformation resistance diagram showing the relationship between the processing temperature and deformation resistance of carbon steel pipes, and the WJ7 diagram, are the coil width-heating diagrams showing an example of the relationship between the coil width and heating temperature of a saddle-shaped high-frequency heating coil. The temperature diagram, FIG. 8, has a saddle shape. DESCRIPTION OF SYMBOLS 1... Main pipe, 2A... Branch pipe part, 4... Burring punch, 4a... Axis center of burring punch, 5...
Saddle-shaped high-frequency heating coil, 10 people...branch pipe, 12...
...A plane containing the axis of the main pipe and the axis of the burring punch, 13...A plane passing through the axis of the burring punch and perpendicular to the drying surface 12, B+, B snow...Coil width, gl,
gl...Coil gap. Gi 1st $2 Mouth/,? 3 eyes 4 eyes 5 mouth 2b I $ 4 eye power a work ≦iaL

Claims (1)

[Claims] 1. A pilot hole is drilled at a predetermined position, and a high-frequency heating coil is arranged near the peripheral edge of the pilot hole. In the method of manufacturing a branch pipe, the high-frequency heating coil is placed at the center of the storage axis, and the branch pipe is formed by heating, pulling out a burring punch inserted into the main pipe from the prepared hole, and performing burring. along the circumferential direction so that the coil width on a plane including the axis of the burring punch and the axis of the burring punch is larger than the coil width on a plane passing through the axis of the burring punch and orthogonal to the plane. A method for manufacturing a branch pipe, characterized by using a saddle-shaped high-frequency heating coil with varying coil width. 2. A prepared hole is drilled at a predetermined position, and a high-frequency heating coil is arranged near the peripheral edge of the prepared hole. In a method for manufacturing a branch pipe in which a branch pipe section is formed by pulling out a burring punch inserted into the pilot hole from the prepared hole and performing burring processing, a high-frequency heating coil is placed between the axis of storage and the axis of the burring punch. The coil gap between the prepared hole edge and the prepared hole edge on a plane including A method for manufacturing a branch pipe, characterized in that a saddle-shaped high-frequency heating coil is formed so that the coil gap can be changed along the circumferential direction.