Welding
Repair welding plane
Here refers to the plane repair welding including plane and similar to the plane arc, welding arc heating focus on the workpiece, only when the workpiece melting welding wire can transition to the workpiece to form a qualified welding spot, the actual operation of the tungsten needle from the workpiece distance is less than the tungsten needle from the welding wire distance.
Welding of edges and corners
The edges and corners of the workpiece are easy to produce "edge biting" phenomenon at the beginning and end of welding. The feature of the angular position is that the heat dissipation of the workpiece matrix is smaller, and the emphasis of arc heating is different from that of plane welding. The center of arc heating can be slightly toward the wire at the edges. High temperature wire fluid is used to melt the sharp edges and corners of the workpiece. The two fused together to avoid direct arc burning workpiece "bite edge".
Welding of inner corners
Our internal fillet welding here is the workpiece in both sides of the molding tutor is equal to or less than 90°. Due to the characteristics of the shortest path of arc discharge, the phenomenon that the bottom corner can not be welded by the most conventional welding method is often more prominent, especially when there is a small amount of welding. At this point, the tungsten needle should be ground very sharp (< 20°), no wire. The tungsten needle is close to the base Angle in the direction of the center line of the Angle, and the distance between the tip and the base Angle and both sides is very small. The melted metal on both sides is pulled to the middle position to form a solder joint. If the solder joint cannot be produced in the middle, the tungsten needle can be moved to the position closer to the bottom Angle to try again, or the welding current can be increased to try again until the solder joint is produced in the middle. Next, the center of the tungsten needle can be moved to the center of the solder joint each time, and the position of 1/2 of the edge of the solder joint, repeat welding. The right edge of the base Angle becomes a circular edge. The welding will be easier later. When welding the edges and corners of three sides, it is generally necessary to first fill the welding amount of the inner corner in the outer plane of the welding.
Nitrogen chemical parts welding
Nitrogen chemical parts due to a large number of nitrogen molecules into the surface of the workpiece in the nitriding process, when the high temperature of the welding nitrogen quickly overflow, resulting in a large number of pores in the molten pool, sometimes the molten metal will be sprayed onto the tungsten pole. The welding process is affected. So to get qualified welding surface. The first thing to do is to remove nitrogen. We usually exhaust air by repeated arc melting. It usually takes 5-10 arc burns to exhaust the gas. The solidified surface of the molten pool from a large number of needle-like holes at the beginning to gradually smooth in the middle part (there will always be pinholes in the outer ring), indicating that the gas has been basically drained. If the welding area is large. It is recommended to grind off the nitriding layer before welding. After welding, a seam with many pinholes has been produced at the junction between the solder joint and the nitriding layer. It requires special welding to eliminate it. The specific operation method is: the tungsten needle (required to be sharpened or coated with polymer) is aligned with the part of the gas has been removed. 0.4mm-0.6mm from the crossing line tip height 0.4mm, the welding wire is placed on the outside of the crossing line. The welding temperature of the solder joint is just enough to melt the wire to cover the joint without creating new pinholes in the nitride layer at the edge. If the welding is a small dot like the above operation generally takes 3-4 times to cover the four sides, if the height of the solder joint is greater than 0.5mm during the process, it needs to be ground down about 0.2mm. It is easier to eliminate the needle holes in the joint by welding again. The trouble of welding too high can be avoided by using a thin sheet.
