It means that after the narrow area of the tube blank is heated to a high temperature of 1250~1300℃, the two edges of the tube blank are squeezed together by the large squeezing force transmitted by the squeeze roller to form a common crystallization to realize welding and solid phase welding. The characteristic is that although the edge of the tube blank has reached the welding temperature, the heating area of the edge of the tube blank in the opening corner area is very narrow and still maintains its original shape. During the welding process, only a small amount of metal is extruded to form a tiny Internal and external burrs, the sparks splashing are small, and the burr height is generally not higher than 30mm.
Solid solution welding
The performance reflected on the edge of the tube blank is that the edge of the tube blank is heated to 1300~1400 ℃, and the physical shape of the tube blank in the open corner area is no longer angular, especially near the vertices of the corners, and the contours of the two edges have been blurred. At the same time, the heated area is much wider than that of the solid phase. Welding can be completed with only a large extrusion force. In this process, part of the molten metal is squeezed to form larger internal and external burrs, accompanied by more Big sparks flew everywhere.
When the edge of the tube billet is heated to above 1400°C, the heating range of the edge becomes sharply widened, some of the metal is in a molten state, and the physical shape loses regularity. The molten metal on both sides of the opening angle has "flowed" together to form a liquid bridge. The current is highly concentrated at the lintel, causing the molten metal at the lintel to partially vaporize. In this state, the two edges of the tube blank can be welded with a small extrusion force. At the same time, a large amount of molten metal is easy to be welded. Extrusion produces a large number of internal and external burrs, accompanied by strong sparks.
In the actual production process, these three welding forms are often intertwined. However, the solid-melt welding form is more favored by operators and used more frequently. The application risks of both solid-phase welding and fusion welding are very high. Under the influence of many objective factors, the actual welding temperature is difficult to be strictly constant: in the solid phase welding state, the temperature is slightly lower, the welding will be incomplete, and a cold weld will be formed, while in the molten welding state, if the temperature is higher , It will form overburning defects. On the other hand, when the welding temperature is high or low, the above problems will not occur, and it is easy to meet the process needs. Especially if the customer requires a straight tube with a small internal burr, it is better to choose a solid For phase welding, if pipes with small internal burrs are required, solid-fusion welding should be selected; of course, if high-strength thick-walled pipes are to be welded, then fusion welding is a better choice.