JP3362357B2 - Welded joints and welding methods - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded joint and a welding method, and more particularly to a welded joint and a welding method capable of making a bead width inside a pipe uniform and narrow. INDUSTRIAL APPLICABILITY The present invention is suitably applied to semiconductor manufacturing equipment, gas supply piping systems, ultrapure water supply systems, and the like.

[0002]

2. Description of the Related Art The degree of integration of semiconductor devices is increasing more and more, and at the same time, the performance of characteristics is being improved. Along with this, semiconductor manufacturing equipment, highly purified manufacturing atmosphere, and
Further purification of gas, ultrapure water, etc. has been attempted.

Conventionally, a gas supply pipe system used in a semiconductor manufacturing process is formed by welding various pipes, joints, valves and the like. As a welding method, for example, in the case of stainless steel pipes, the pipe ends of two pipes are butted against each other, and tungsten inert gas welding, arc gas welding,
A welding method such as electron beam welding is used.

However, in the case of welding by such a method, there is a problem that the bead width becomes nonuniform and widens, resulting in contamination of process gas and the like. That is, although metal fumes are generated during welding, widening the bead width means that metal fumes that evaporate and fly increase. The metal fumes are cooled and reattached in the vicinity of the welded portion, and are peeled off when a corrosive gas or the like is flown, which contaminates the gas and the process atmosphere and deteriorates the characteristics of the semiconductor device to be manufactured. Further, since the bead portion has a rough surface and gas is easily adsorbed, the adsorbed gas is gradually desorbed to contaminate the process atmosphere. Furthermore, chromium beads are deposited in the bead portion, which causes intergranular corrosion depending on the gas used.

For the above-mentioned reasons, in the semiconductor manufacturing-related apparatus, it is desired to make the bead width of the welded portion as narrow as possible.

[0006]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a welded joint and a welding method capable of performing welding with a narrow bead width.

[0007]

The welded joint of the present invention has a tube diameter of 3/8 inch or 1 having a tubular end for welding.
In a / 4 inch stainless steel welded joint, a groove is provided on the inner wall side of the tubular end, and the groove is 60 to 60 mm from the central axis.
Having a depth of 0.15 to 0.2 from the tubular end.
It is characterized by being 5 mm.

The groove has an angle of 60 to 75 ° from the central axis and a depth from the tubular end of 0.15 to 0.25.
It is preferably mm.

The welding method of the present invention is a welding method for a stainless steel welded joint having a tubular portion with a pipe diameter of ⅜ ″ or ¼ ″, and the inner wall side of the pipe ends of the two welded joints. After forming the groove in the
Having an angle of 75 ° C. and a depth from the tubular end of 0.15 to
0.25 mm, and the welded joint is welded along the outer circumference.

The groove has an angle of 60 to 75 ° from the central axis and a depth from the tubular end of 0.15 to 0.25.
It is preferably mm.

[0011]

In the process of the present inventor's study of narrowing the bead width, in the case of the conventional I-groove, it is caused by the accuracy of butting of the welded members, the variation in the composition of the welded joint, the tolerance between the welded joints, etc. It was found that a uniform bead width could not be obtained with good reproducibility. That is, even if welding was performed under the same conditions, a defective fusion portion appeared or conversely a wide bead appeared in each welding and also in one welding. Therefore, if the amount of heat input is increased in order to eliminate the defective melting portion, the bead width becomes very wide.

The present invention has been completed on the basis of such knowledge, and when welding and connecting a welded joint having a tubular end such as a pipe, it is opened on the inner wall side of the pipe end to be a welded portion. By providing a tip and welding from the outside, it is possible to make the bead width inside the pipe uniform and extremely narrow, and obtain it with good reproducibility.

In the present invention, the groove angle is preferably 60 to 75 ° from the center line of the tube, and more preferably 65 to 70 °. Within this range, the bead width becomes more uniform and narrow. The depth of the groove from the tip depends on the pipe diameter and thickness of the pipe, but for commercially available 3/8 inch pipe and 1/4 inch pipe, it is 0.15-0.25 mm, 1/2 inch pipe. Is preferably 0.2 to 0.3 mm.

As the welded joint of the present invention, the welded portion has a tubular shape, and various kinds of pipes, valves, various joints and the like can be mentioned. Particularly, it is preferably applied to a pipe having a diameter of 1/4 inch or 3/8 inch.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Welded joints having a 1/4 inch diameter pipe (S
US316L VCR) and 1/4 inch diameter SUS316
A groove was cut on the pipe end of the L pipe with a precision lathe as shown in FIG. 1 (a).

Subsequently, an automatic welding machine (SPB manufactured by Astro Arc Co., Ltd.) using the conventional tungsten inert gas welding method is used.
100) two butt welds of two weld joints.
Zero sets were performed (FIG. 1 (b)).

For comparison, 20 sets of butt welding were similarly performed on the conventional welded joint having the I-groove (FIG. 1 (c)).

After welding, the welded portion was cut into a plane including the central axis, and the internal bead portion was observed.

The conventional joint is, as shown in FIG. 2 (b),
Those with insufficient welding and, conversely, those with a wide bead width and non-uniformity were about 40% and 60%, respectively, and stable beads could not be obtained.

On the other hand, in the case of this embodiment, as shown in FIG. 2A, the bead width is 0.
A bead having a uniform and narrow width was obtained by entering the range of 4 to 0.5 mm. Moreover, the strength was equal to or higher than that of the wide bead with the I groove.

Next, Tables 1 and 2 show the results of welding in the same manner while changing the groove angle (α) and depth (d) and variously.

[0023]

[Table 1]

[0024]

[Table 2] As shown in Table 1, the groove angle is preferably 60 to 70 °, and more preferably 65 to 70 °.
Within this range, defects due to insufficient welding are eliminated, and narrow beads can be obtained. Further, when the groove angle is 80 °, the flat portion at the pipe end disappears, but the welding strength tended to be lower than that of 60 ° to 75 °.

Further, as shown in Table 2, by setting the groove depth to be 0.15 to 0.25, a narrow bead with no insufficient welding was obtained.

[0026]

According to the present invention, welding of narrow beads can be performed with good reproducibility, and the present invention is suitably applied to welding of equipment such as semiconductor manufacturing equipment that requires a highly clean atmosphere.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a groove shape of a welded portion and a welding method of the present invention.

FIG. 2 is a conceptual diagram showing a state of a bead portion after welding.

[Explanation of symbols]

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasumitsu Mizuguchi 75-1 Shingo, Higashimatsuyama-shi, Saitama Osaka Oxygen Industrial Co., Ltd. (72) Inventor Takeshi Tanaka 75-1 Shingo, Higashimatsuyama-shi, Saitama Osaka Oxygen Co., Ltd. In the Development Center (72) Inventor Junyuki Murakawa 2-16-13 Yushima, Bunkyo-ku, Tokyo Saito Building Co., Ltd. UMC Ltd. (56) References: Kaihei 5-49188 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 33/00

Claims (2)

(57) [Claims] 1. A pipe diameter having a tubular end for welding is 3
/ 8 inch or 1/4 inch stainless steel welded joint
In, the groove is provided on the inner wall side of the tubular end, and the groove is
It has a temperature of 60 to 75 ° C. from the central axis and a depth from the tubular end.
Welded joint characterized by having 0.15 to 0.25 mm
hand. 2. The diameter of the pipe having a tubular portion is 3/8 inch or
Welding method for 1/4 inch stainless steel welded joint
To form a groove on the inner wall side of the pipe ends of the two welded joints.
After that, the groove has an angle of 60 to 75 ° C from the central axis.
And the depth from the tubular end is 0.15-0.25 mm.
And weld the welded joint along the butt circumference.
Welding method characterized by.