JPH0234685B2 - TGATAKANTSUGITENOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a T-shaped pipe joint (hereinafter referred to as a T-joint) made of a metal tube.

As shown in Fig. 1, a T-joint used at a branch part of piping consists of a main pipe 1 and a branch pipe 2, the boundary between the two is called a crotch 3, and in the case of a welded joint, both ends of the main pipe are 4 and the branch pipe end 5 are beveled for welding connection.

Among the manufacturing methods of T-joints made from metal pipes,
The most common method is burring as shown in FIG. According to this method, first, as shown in Fig. 2a, a tube with the same outer diameter D ₁ and the same wall thickness T 1 as the main pipe ₁ of the product T-joint is slightly finished to the main pipe length L (see Fig. 1). Cut to length L ₀ including the allowance,
The base pipe 7 with the through hole 6 drilled at the planned position for forming the branch pipe is placed into a die 8 having the same inner shape as the outer shape of the product branch pipe and its surrounding main pipe. After setting the holes so that their centers match, open the through hole 6.
A plug 11 is attached to the tip of a drawing rod 10 inserted into the raw tube 7 through the hole. Next, the pull-out rod 10 is pulled down, the through-hole 6 is enlarged by the plug 11, and the second
A branch pipe 2' is formed in the die branch pipe hole 9 as shown in Figure b. This is burring processing.

This processing is done in order to reduce the pulling force and to prevent breakage 12 at the end of the branch pipe as shown in Figure 3.
It is usually done hot and in several parts. In that case, the diameter Dp (see Fig. 2 a) of the plug 11 used each time is increased stepwise, and finally Dp is made larger than the product branch pipe inner diameter d ₂ (see Fig. 1). The value is made smaller by the amount of finishing allowance.

By the way, in the above-mentioned burring process, if the through hole 6 is made circular, the drilling process is easy.
In this way, after the burring process, as shown in FIG. 4, the end of the branch pipe becomes higher in the main pipe axis direction x and lower in the direction y orthogonal thereto. This is because, as is clear from FIG. 1, the difference in height between the end 5 of the product branch pipe and the crotch 3 is the minimum Hx in the x-direction cross section passing through the center of the branch pipe, and the maximum Hy in the y-direction cross section orthogonal thereto. In other words, the y-direction cross-section of the branch pipe requires an extra material wire length corresponding to the height difference ΔH = Hy - Hx compared to the x-direction cross-section, and unless this is taken into account before the burring process, the branch pipe in the y-direction cross-section It is unavoidable that the pipe ends become lower.

When the through hole 6 is made into a round hole, the unevenness of the ends of the branch pipe becomes more significant as ΔH increases, that is, as the ratio D ₂ /D ₁ of the branch pipe diameter to the main pipe diameter approaches 1,
If the irregularities in the ends of the branch pipes are large, the pipe ends must be trimmed using a method such as gas cutting and then beveled, resulting in an increase in man-hours and a decrease in yield due to truncation. In addition, the height of the branch pipe after cutting as shown in Figure 4
If H' does not reach the height Hx of the product branch pipe, the diameter of the through hole 6 has to be reduced, and the hole diameter expansion rate during burring increases. The danger increases.

There are two known methods for eliminating irregularities in the ends of branch pipes during burring.
One of them is to make the through hole 6 long in the main tube axis direction x and short in the direction y perpendicular to the main tube axis direction, as shown in FIG. This is a method of adjusting the distances lx and ly to the hole edge to appropriate values. This method is the most direct and effective method for eliminating uneven pipe ends, but because the machined surface is curved, lx,ly is the ratio of the branch pipe diameter to the main pipe diameter D ₂ /D ₁ and the desired branch pipe height, it is necessary to determine the dimensions by trial and error.
Not only is the shape design complicated, but the through hole 6
The disadvantage is that it is difficult to process.

In order to eliminate these drawbacks, another method is to bulge the part of the main pipe where the branch pipe is to be formed, as shown in Figure 6, before drilling the circular hole to create a crotch line in the y direction. This is a method in which a straight wall portion 30 having a height ΔH from 3' is formed in advance, that is, a height difference ΔH of the crotch portion in the x direction and the y direction is eliminated before the burring process. However, in this method, although the through hole is circular, the elongation in the y direction during the bulging process is large and the straight wall portion 3 in the y direction
However, there is a disadvantage that there is a risk that an overhang fracture 31 as shown in FIG.

In addition, by using a hemispherical plug in the above-mentioned bulging process, a dome-shaped bulge 24 having no straight wall in the y direction is formed as shown in FIG. This can also be said to be effective in eliminating irregularities at the ends of branch pipes. However, in that case,
Unless the peripheral edge of the circular through hole is located on a plane perpendicular to the central axis of the branch pipe, the unevenness of the pipe ends cannot be resolved.
However, in order to obtain such a circular hole, it is necessary to increase the bulge height hx and reduce the diameter of the circular hole.If these conditions are not satisfied, bulge processing is necessary. Occasionally, an overhang break 31' as shown in FIG. 8b occurs, or a tube end break 12 as shown in FIG. 3 occurs during burring.

That is, the circular through hole is as shown in FIG. 11a, which will be described later.
When reaching the area h ^* (the base of the dome-shaped bulge), the periphery is no longer located on one plane, so a circular hole can only be obtained at the top of the bulge.
If the bulge is low, the diameter of the circular hole must be extremely small, in which case the tube end will break during burring. On the other hand, when drilling a large diameter hole in order to prevent the pipe end from breaking during burring, the bulging part must be made high; be. Therefore, in order to obtain a circular through hole that can eliminate the unevenness of the tube ends, it is necessary to increase the bulge height hx and reduce the diameter of the circular through hole.

However, according to the experience of the present inventors, under such conditions, for example, when the ratio β (=D ₂ /D ₁ ) of the branch pipe diameter D ₂ and the main pipe diameter D ₁ is 0.5, bulge may occur. Ratio α of height hx and branch pipe diameter D ₂ = hx / D ₂ is 0.3 or more, through-hole diameter d ₀
The ratio γ (=d ₀ /D ₂ ) between the diameter of the branch pipe and the diameter D ₂ of the branch pipe is 0.3 or less, which is extremely strict, and in reality, there are almost no materials that satisfy this condition. Therefore,
Similar to the method of forming a trapezoidal bulge shown in Fig. 6, the method of drilling a circular hole in a dome-shaped bulge has almost no meaning in reality, and in the end, the method described at the beginning has no meaning. Currently, we have no choice but to rely on elongated holes that are difficult to process.

The present invention has been made in view of the above circumstances, and its purpose is to provide a T-shaped through hole that can be extremely easily machined, thereby easily and reliably eliminating irregularities in the ends of branch pipes. An object of the present invention is to provide a method for manufacturing a pipe joint.

The method for manufacturing a T-type pipe joint of the present invention is a method for manufacturing a T-type pipe joint using a pipe as a raw material, in which a portion of a base pipe that is approximately the same size as the product main pipe portion where a branch pipe is to be formed is expanded toward the outer surface of the pipe. In order to make the tube come out, a substantially hemispherical plug inserted into the raw tube is used to apply pressure in the tube radial direction to form a dome-shaped bulge. A point where the through hole formed after cutting is located on a plane perpendicular to the central axis of the pipe and is cut at the root part where it becomes an elongated hole, and then burring is performed around the through hole to form a branch pipe. It is characterized by

As mentioned above, the elongated hole is effective in eliminating irregularities in the ends of the branch pipe. The present invention provides a through-hole, which has conventionally been considered difficult to fabricate, by an extremely simple method of cutting the dome-shaped bulge on a plane perpendicular to the central axis of the branch pipe.

In the present invention, it is only necessary to form the dome-shaped bulge to such an extent that the dome-shaped bulge can be cut on a plane perpendicular to the central axis of the branch pipe, so there is no need for severe bulge processing that would cause overhang breakage. do not. In addition, since the area where the elongated hole is formed is located at the base of the dome-shaped bulge, the elongated hole is inevitably large, and the tube end does not break during burring. .

Furthermore, the elongated hole obtained by the present invention is not only much easier to process than the hole obtained by conventional processing, but also because the hole portion protrudes from the outer surface of the main tube. It is also advantageous in terms of securing the height of the branch pipe, and since the peripheral edge of the through hole is located on a plane perpendicular to the central axis of the branch pipe, it is possible to eliminate irregularities in the ends of the branch pipe by just cutting. It takes on a suitable shape.

In other words, the elongated hole, which is naturally obtained by cutting the dome-shaped bulge on a plane perpendicular to the central axis of the branch pipe, eliminates irregularities in the end of the branch pipe after burring. It is suitable for eliminating it.

Hereinafter, the method of the present invention will be explained in detail based on specific examples shown in the drawings.

Figure 9 shows the bulging process. The raw tube 7 is substantially the same as that used in the conventional method shown in FIG.
The same outer diameter D ₁ and wall thickness as the main pipe 1 of the product T-joint
T ₁ , and length L ₀ is the length of main tube 1 (see Figure 1)
This is the value obtained by adding some finishing allowance.

According to FIG. 9, first, as shown in a, a beam section 16 to which a substantially hemispherical plug 15 is attached, a fixed column 17 that horizontally supports the beam section 16 in a cantilevered manner, and a fixed column 17 are attached to the upper press ram 18. At the free end side of the beam section 16, there is a gap δ larger than the raw pipe wall thickness _T1 .
A plug pressing tool 20 consisting of a movable column 22 with a built-in hydraulic ram 23 fixed to a mounting plate 19 with Press 18,1
Install it at 8'. Next, the raw pipe 7 is passed through the beam portion 16 of the plug pressing tool 20, and set in the die 8 so that the branch pipe formation planned portion 21 of the raw pipe 7 shown by cross hatching is positioned above the die branch pipe hole 9.

When the setting of the blank tube 7 is completed, in order to fix the blank tube 7 to the plug pressing tool 20, the ram 23 of the movable column 22 is lowered to reduce the distance δ from the beam part 16 to 0.
and then press ram 1 on the press as shown in Figure 9b.
8 is lowered, and the part 21 to be formed into the branch pipe is expanded into the die branch pipe hole 9 using the plug 15 to form a dome-shaped bulging part 24. At this time, the height hx of the dome-shaped bulge 24 is such that the head wall thickness t ₂ of the bulge 24 does not become less than the branch pipe wall thickness T ₂ (see FIG. 1), and the height hx in FIG. It is necessary to keep it within a range where overhang breakage 31' as shown does not occur.

When the swelling process is completed, the upper ram 18 is raised,
After retracting the hydraulic ram 23 of the movable column 22, the bulging semi-finished product 26 is extracted from the beam portion 16, and the dome-shaped bulging portion 24 is cut along a plane perpendicular to the central axis of the branch pipe to form a through hole. Open.

FIG. 10 shows a through hole 6 formed at the center of the tip of a dome-shaped bulge 24 formed using a substantially hemispherical plug 15 so that the outer periphery is located on a plane perpendicular to the central axis of the branch pipe. This is an example of a pierce.
The through hole 6 obtained here is in the main tube axis direction (x direction)
It has an elongated hole shape. In order to obtain such an elongated hole 16, the height h' of the inner peripheral edge 27' (height from the outer surface of the main tube in the cross section in the x direction) is limited.

That is, the planar shape of the through hole 6 provided in the dome-shaped bulge changes depending on the height h' of the inner peripheral edge 27'. As shown in FIG. 11, when the hemispherical plug 15 is bulged, the plug 15
The contact diameter between the inner surface of the bulging portion 24 differs depending on the direction, and the diameter dx of the x-direction cross section and the diameter of the y-direction cross section
The relationship between dy and dx is clear from the fact that the relationship between the x-direction cross-sectional angle θx and the y-direction cross-sectional angle θy between the outer slope of the bulging portion 24 and the inner wall of the die branch pipe hole 9 is θx>θy. becomes ＜dy. Therefore, x
If the height h ^* from the outer surface of the main tube of the contact point Tx with diameter dx in the directional cross section is greater than h', the cut will be made in the area h ^* , and as a result, as shown in Fig. 10. As shown, the planar shape of the through hole 6 is the diameter in the x direction.
The hole has an elongated hole shape in which Dx is larger than the diameter Dy in the y direction.
This shape is suitable for eliminating irregularities in the ends of the branch pipe after burring.

Note that if the dome-shaped bulge is cut at the height of h' when h ^* is smaller than or equal to h', the planar shape of the through hole 6 will be circular. That is,
In this case, the bulge in the area h'', which is the area where the plug 15 is in contact with the dome-shaped bulge in FIG. 11a, is cut. Since the hole 6 is dominated by a hemispherical shape, the hole 6 cut in the area h'' becomes circular. Therefore, the cutting range in the present invention in this case is the area h'' so that the hole 6 does not become circular. ″ is the area of h ^* at the base.

The height of the dome-shaped bulge may be determined depending on the length of the desired branch pipe, but according to the method of the present invention, the height of the dome-shaped bulge may be low or high. becomes anomalous in the region of h ^* .

In the above drilling process, the end surface 28 of the through hole 6
is an end face that coincides with a plane orthogonal to the central axis of the branch pipe, as shown in Fig. 12a, and if its inner peripheral edge 27' is sharp, the pipe end breakage 12 (Fig. 3) occurs during the subsequent burring process. (see FIG. 12b), it is desirable to drill the hole so that the cut end surface 28 is perpendicular to the outer surface of the bulge 24, as shown in FIG. 12b.

Such hole-drilling is performed by using gas cutting, for example, to form a fixed bulge 2 as shown in FIG.
This can be easily done by making the gas torch 29 revolve around the gas torch 4 on the same plane.

Figure 14 shows the details, and the torch 2
The holder 30 that supports 9 has a vertical rotation axis 31
It is slidably supported on a horizontal guide 32 fixed to the. The torch 29 is inclined downward toward the rotating shaft 31.

The bulging semi-finished product 26 is set directly below the rotating shaft 31 so that the bulging part 24 is concentric with the rotating shaft 31, and the gap between the torch 29 and the bulging part 29 is always constant. For example, a worker slides the holder 30 along the guide 32 while moving the rotating shaft 31
When rotated around , the bulge 24 is cut on the same plane. The distance between the torch 29 and the bulge 24 can be controlled visually or by using an appropriate guide jig.

Once the drilling process is complete, the process moves on to burring.
This can be done in exactly the same way as the conventional method shown in FIG.

After the burring process, the semi-finished product is finished by cutting to the product dimensions as necessary, and if it is to be made into a welded pipe joint, bevels are applied to the ends of the branch pipe and both ends of the main pipe. be converted into

It goes without saying that the present invention can be applied whether the bulging process and the burring process are hot working or cold working.

Next, examples of the present invention will be described.

First, the outer diameter D ₁ is 200 mm, the wall thickness T ₁ is 5 mm, and the length L ₀
An aluminum tube with a diameter of 350 mm was set in a die having a semicircular groove with a radius of 100 mm. Next, using a hemispherical plug with a diameter of 140 mm, a dome-shaped bulge having a cross-sectional height hx in the x direction of 40 mm was inflated in the die cutout with a diameter of 150 mm in the cold by the method shown in FIG. Furthermore, after that, the first
The plasma cutting torch shown in Figure 4 is rotated in a horizontal plane, and the diameter Dx in the x direction is 90 mm and the diameter Dx in the y direction is 90 mm at the center of the bulge.
A through hole with a directional diameter Dy of 80 mm and whose peripheral edges were located on the same plane was drilled. Finally, cold burring is performed using the method shown in Figure 2 to reduce the outer diameter D ₂
A branch pipe with a wall thickness of 150 mm and a wall thickness T ₂ of 3.6 mm was formed.

As a result, the height difference in the circumferential direction due to irregularities at the ends of the branch pipes can be suppressed to 5 mm, which makes it possible to perform bevel processing without requiring a process of trimming the ends of the branch pipes, and We were able to finish the pipe height Hx to the required 30mm for the product.

For reference, when the pushing depth of the hemispherical plug was changed in the above bulging process, when the x-direction cross-sectional height hx of the dome-shaped bulge was 50 mm or more, the dome-shaped bulge was shown in Figure 8b. A similar overhang fracture occurred. Therefore, in the above embodiment, there is a margin of 10 mm in height before the overhang fracture occurs. On the other hand, when drilling a circular hole whose periphery is located on the same plane in the dome-shaped bulge (hx = 40 mm), the hole diameter is 60 mm.
mm or less, which caused the tube end to break as shown in FIG. 3 during burring. On the other hand, if burring is to be performed without causing pipe end breakage, the diameter of the through-hole needs to be approximately 80 mm or more, and the dome-shaped bulge becomes hx = 60 mm or more, which falls into the overhang rupture region. Therefore, in the case of forming a branch pipe as described above, circular through holes do not eliminate irregularities in the ends of the branch pipe.

In addition, when we tried to form a branch pipe by directly drilling a circular hole in the same base pipe as the above base pipe and performing the burring process shown in Fig. 2, the height of the branch pipe Hx = 30 mm.
In order to ensure this, the diameter of the hole had to be 50 mm, and one burring process would cause the pipe end to break, so the burring process had to be done in two parts with intermediate annealing. In addition,
The ends of the branch pipes were uneven, and the height difference in the circumferential direction was as much as 35 mm, necessitating a process of trimming and aligning the pipe ends prior to beveling.

As is clear from the above description, the present invention can suppress irregularities in the ends of branch pipes by simple processing and without causing breakage during processing. Therefore, according to the present invention, high quality branch pipes can be manufactured efficiently and economically regardless of the material of the T-joint.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a T-type pipe joint, Fig. 2 is an explanatory diagram of the burring process, Fig. 3 is an explanatory diagram of material breakage in the same process, and Fig. 4 is an explanation of uneven heights at the ends of branch pipes. Figure 5 is an explanatory diagram of a through hole taken as a conventional measure for the same irregularity, Figure 6 is an explanatory diagram of a bulge part taken as a conventional measure for the same irregularity, and Figure 7 is an explanatory diagram of another bulge part taken as a conventional remedy for the same irregularity. , FIG. 8 is an explanatory diagram of material breakage in bulge processing, FIG. 9 is a process explanatory diagram of an example of bulge machining in the method of the present invention, and FIG. 10 is an explanatory diagram of an example of hole drilling in the method of the present invention, 1st
Figure 1 is an explanatory diagram of the state of contact between the plug and material during bulge processing, Figure 12 is an explanatory diagram of the shape of the through-hole end,
3 and 14 are explanatory diagrams of specific examples of drilling in the method of the present invention. In the figure, 1: Main pipe, 2: Branch pipe, 3: Kurotsuchi,
6: Through hole, 7: Base pipe, 8: Die, 9: Die branch pipe hole, 11, 15: Plug, 20: Plug pressing tool, 21: Branch pipe formation planned part, 24: Swelling part, 2
6: Swollen semi-finished product. 27: Outer periphery.

Claims (1)

[Claims] 1. In a method for manufacturing a T-type pipe joint made of pipe, a method is used in which the part of the raw pipe that is approximately the same size as the product's main pipe is inserted into the raw pipe so that the part where the branch pipe is to be formed bulges out to the outer surface of the pipe. After forming a dome-shaped bulge by applying pressure in the pipe radial direction with a hemispherical plug, the dome-shaped bulge is positioned on a plane in which the outer peripheral edge of the cut surface is perpendicular to the central axis of the branch pipe. A method for manufacturing a T-shaped pipe joint, characterized in that the through hole formed after cutting is cut at the root portion where it becomes an elongated hole, and then the periphery of the through hole is subjected to burring processing to form a branch pipe. .