JPH0156870B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses lead and titanium using a lead brazing rod.
This relates to a welding method using TIG welding. Recently, titanium and lead have been used as corrosion-resistant metals in containers, pipes, structures, etc. of corrosion-resistant chemical equipment, and even in insoluble anodes for electroplating, and welding of the two may be required. Taking insoluble anodes as an example, in electroplating such as zinc plating, tin plating, nickel plating, and lead plating,
It is well known that attempts have been made to use insoluble anodes for plating on one or both sides of steel strips and the like. Several proposals have been made regarding the material and structure of the insoluble anode in order to withstand the harsh corrosive environment and prevent leakage current, one of which seems promising is a composite material of lead and titanium. . FIG. 1 shows a part of an electrogalvanizing bath, into which a steel strip 1 is passed along a U-shaped path. The steel strip is energized to the (-) pole and an insoluble anode 3 is placed on each side of the strip for double-sided plating on its entry and exit sides into the bath. The insoluble anode 3 includes an iron plate 8 and a lead plate 5 that enclose a copper material 4 as a current-carrying material inside.
It consists of a titanium material 6 placed on the side opposite to the side facing the strip. The titanium material 6 has the property of being passivated in the liquid and blocking the flow of current, thereby effectively preventing leakage current from the back and side surfaces of the insoluble anode opposite to the strip. In making the insoluble electrode, the titanium material and the lead plate are welded together at their joints, as shown in FIG. 2, in order to provide a robust integral structure. Furthermore, since lead plates inevitably suffer melt damage, it is necessary to build up the melted parts every few months, and lead-titanium build-up welding is also required at that time. In the past, it was considered difficult to weld lead and titanium, and it was even said that perfect joining was impossible.
However, the present inventor has discovered that it is possible to weld lead and titanium extremely easily by performing downward TIG welding using a low rod under appropriate welding conditions selected according to the plate thickness. I found out. It is extremely unexpected that lead-titanium welding, which has been considered difficult or impossible in the past, can be achieved using such a simple welding method, and contributes to simplification and cost reduction in the production of insoluble anodes. According to the invention, welding current of 13 to 85 A, 9 to
Using a welding voltage of 12V and a welding speed of 70 to 300 mm/min, welding conditions that fall within the range shown in Figure 4 according to the plate thickness were selected, and the lead plate and titanium plate were held in a downward position using a lead brazing rod. A method for welding a lead plate and a titanium plate using TIG welding is provided.
The selection conditions largely depend on the thickness of the lead plate and titanium plate; the thicker the plate, the greater the welding heat input (voltage x current/speed) needs to be. As a result of extensive testing, it has been found that the welding conditions shown in the following table are more preferable depending on the lead and titanium plate thickness.

[Table] Low stick welding is performed by heating the titanium-lead joint with the welding electrode facing downward, as shown in Figure 3. After-shielding and back-shielding are preferred. The low bar is shown as 7. Suitable overlay welding is possible under the welding heat input shown in FIG. 4 in the range of welding current of 13 to 85 A, welding voltage of 9 to 12 V, and welding speed of 70 to 300 mm/min. In FIG. 4, in the range below the lower limit curve of the welding heat input range, workability is poor, the bead appearance is poor, and good joining cannot be achieved. In the range above the upper limit curve, lead undercut (a dent occurs in the part above the joint of the lead plate), lead shoulder burn-through (melt to the corner of the lead plate), or titanium undercut (the titanium plate melts). Defects such as dents (indentations near the joints) are more likely to occur. If the welding current is too small, the welding speed is slow, the bead appearance is poor, and penetration is likely to be poor. On the other hand, if the welding current is too large, the welding speed becomes too fast, making it difficult to control the electrode movement speed, and the titanium plate Melt-through and other defects are more likely to occur, and oxidation becomes more intense. Although the present invention is described as a lead plate, it is equally possible to implement lead alloys containing 2% or less Ag, lead alloys containing 7% or less Sb, and lead alloys containing 7% or less Sn.
These are included. Furthermore, although a lead plate is used, a plate with some unevenness also falls within the scope of the present invention. According to the present invention, welding can be performed with a small welding heat input, and mechanical or chemical deterioration of the titanium material due to overheating can be minimized. Furthermore, heat treatment under an inert gas atmosphere before and after welding is not required. Example 1 Low stick welding of Pb-Ti plates was carried out using a high performance DC argon arc welding machine having the following ratings. Rated input 11kVA, 8.2kW Rated input voltage 200V Rated input current 55A Rated frequency 50/60Hz Number of phases Single phase Rated usage rate 25% Industrial pure argon gas was used as the shielding gas. The polarity of the current in DC TIG welding was set as (-) for the electrode rod and (+) for the base metal. The welding position was as shown in Figure 3a. The plates used were of various thicknesses as shown in the table below. The test results are shown in the table below. Workability was good and joints with good bead appearance were produced. As the brazing rod, a lead brazing rod made by cutting a 3 mm lead plate into a width of about 3 mm was used. The results are shown in the table. The bead appearance was extremely good.

【table】 [Brief explanation of drawings]

Figure 1 shows a part of electroplating equipment that uses an insoluble anode, Figure 2 shows a cross-sectional view of the insoluble anode along the line X-X in Figure 1, and Figure 3 uses a lead brazing rod. FIG. 4 is a graph showing the appropriate range of heat input to titanium thickness according to lead plate thickness. 1: Strip, 3: Insoluble anode, 4: Current-carrying material, 5: Lead plate, 6: Titanium, 7: Lead brazing rod, 8:
Iron plate.

Claims (1)

[Claims] 1 Welding current of 13~85A, welding voltage of 9~12V,
From the welding speed of 70 to 300 mm/min, select welding conditions that fall within the range shown in Figure 4 according to the plate thickness, and use a lead brazing rod to hold the lead plate and titanium plate in a downward position.
A low rod welding method for lead plates and titanium plates, characterized by TIG welding.