JPS59144582A - Joining method of steel plate and penetrated copper pipe - Google Patents

Abstract

PURPOSE:To improve the joining property on a copper pipe side and to form a good fillet shape in welding of the copper pipe penetrating through a steel plate by a nonconsumable electrode by preheating the part of the copper pipe near the weld zone having good heat conductivity with an arc and welding the weld zone with a filler wire fed to said zone. CONSTITUTION:A nonconsumable electrode 3 is first deviated as shown by a dotted line in the figure in the fillet welding of a copper pipe 2 penetrating through a steel plate 1 and the circumference of the pipe 2 is preheated with arc discharge. The electrode 3 is then set in a prescribed position and while a filler wire 4 is fed, the two members are welded. The build-up surface is then leveled off and the welding is completed. If the pipe 2 having good heat conductivity is preheated in the above-mentioned way, the heat balance thereof with the steel plate is improved and the good build-up weld zone is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of penetrating and joining a copper pipe to a relatively thin steel plate.

[Prior art]

Conventionally, the method of joining a thin steel plate and a penetrating steel pipe is to insert a copper pipe 2 into a steel plate 1 and then perform brazing, as shown in Figure 1. Therefore, additional steps such as pickling were required.

Furthermore, when silver solder is used as the brazing material, there is a drawback that the silver contained in the brazing material is expensive and its price is unstable.

In addition, as shown in Fig. 2, an arc is generated with the tip of the electrode 3 directed from the steel plate 1 at an angle of approximately 45° toward the root inside the corner, and the filler wire 4 is fed into the arc. There is also a method of forming . However, inside the corner between the cap pipe 2 and the steel plate 1, a difference in temperature rise due to arc heat occurs due to the difference in thermal conductivity of the base metal. In other words, the amount of heat given to the copper pipe side is conducted and diffused more quickly than the amount of heat given to the steel plate side. Therefore, there is a problem that the wettability of the copper pipe side becomes poor. Furthermore, if an attempt is made to improve the wettability of the copper pipe side by increasing the amount of heat input, too much heat will be input to the steel plate side, making it impossible to obtain a well-shaped corner.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a joining method that improves the wettability of the copper pipe by balancing the temperature rise at the joint surface of the copper pipe and the steel plate, thereby obtaining a good corner joint.

[Summary of the invention]

In order to improve the bondability of the bonding surfaces, the present invention provides a final step at the beginning of the bonding process in which the bonding surfaces are preheated with arc heat in an inert gas atmosphere to improve the bondability of the bonding surfaces, and then a filler is added. The process of feeding the wire and forming the southern part of the corner continues. Furthermore, in the first stage preheating process, the target position of the electrode is moved to concentrate more arc heat on the copper pipe side and balance the temperature rise of the base material, and in the next process, the electrode position is returned to the original position to the southern part A better joint can be obtained by feeding filler wire.

By separating the preheating process and the filler wire feeding process, an appropriate current value for preheating and an appropriate current value for forming the southern part of the corner are selected.

[Embodiments of the invention]

Next, one embodiment of the present invention will be explained with reference to FIGS. 3 and 4. FIG. 3 shows a through joint in which a copper pipe 2 is passed through a steel plate 1, and the position of the non-consumable electrode 3 is approximately 45 mm from the steel plate 1.
When aiming at the southern route at an angle of ° (solid line), and when moving slightly upward along copper pipe 2 (
(dashed line). Then, in the preheating step mentioned above, the electrode 3 is preheated at a position slightly shifted upward (the position indicated by the broken line) in order to improve the wettability of the bonding surface and to equalize the thermal balance. The filler wire 4 is returned to the position shown by the solid line and is fed to form a good southern corner having joint surfaces on both the pipe side and the steel plate side.

FIG. 4 shows this as an hourly arc current diagram. The predetermined arc current IA is reached in a relatively short time from arc start time io to [1], and after the time required for preheating has passed, the current IA is changed to In if necessary in a short time from time t2 to 13. Then, after a predetermined time 1B has elapsed, the crater treatment starts from time 4, and the final crater current Ic is reached and the bonding is completed. It is preferable to keep the preheating time LA longer than the time required for the electrode 2 to make at least one revolution around the circumference of the pipe, feed the filler wire 4 in the next revolution to form the southern part of the corner, and finally perform crater treatment.

Note that the currents IA and IB are values that depend on the thicknesses of the steel plate 1 and the copper pipe 2, so as shown in FIG. 4, it is not necessary that IA>IBK. , ■ It may be necessary to make A≦II.

〔Effect of the invention〕

As explained above, according to the present invention, the wettability of the copper pipe side can be improved by the preheating process using arc heat in an inert gas atmosphere, so the bondability of the copper pipe side is improved, and the electrode position By changing the temperature during preheating and when feeding the filler, the thermal balance can be improved, resulting in the formation of a beautiful and well-shaped joint.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the joining state of a steel plate and a through-hole copper pipe by conventional brazing, and Figure 2 is a sectional view showing the conventional TIG welding method.
3 is a diagram showing an embodiment of the present invention in which the electrode is moved, and FIG. 4 is a diagram showing an embodiment of the present invention in which the electrode is moved.
FIG. 3 is a diagram showing an example of a flowing time pattern. 1... Temporary extortion, 2... Copper pipe, 3... Electrode, 4
...Filler wire. ■ 1 Figure 4th time M 465

Claims (1)

[Claims] 1. In the welding method of a through joint in which a copper pipe is inserted into a hole provided in a #f4 plate, an arc is caused by a non-consumable electrode in an inert gas atmosphere to A joining method characterized by providing a preheating step of rotating the filler wire at least once or more, followed by a joining step of feeding a filler wire. 2. In the joining method described in claim 1, the preheating step A joining method characterized by changing the aiming position of the electrode in the joining step and the aiming position of the electrode in the subsequent joining step of feeding the filler wire. 3. In the joining method described in claim 1, , a bonding method characterized by completely changing the amount of heat input in the preheating process and the amount of heat input in the subsequent bonding process in which filler wire is fed.