1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the joint between the welds will be poor, resulting in unfused or cracked.

2. If the gap is too small, the proximity effect will increase, and the welding heat will be too large, causing the weld to burn; or the weld will form deep pits after extrusion and rolling, which will affect the surface quality of the weld.

After heating the two edges of the tube blank to the welding temperature, under the squeeze of the squeeze roller, the formed metal grains penetrate and crystallize with each other, and finally form a strong weld. If the squeezing force of the spiral steel pipe is too small, the number of common crystals formed is small, the strength of the weld metal decreases, and cracks will occur after the force is applied; if the squeezing force is too large, the molten metal will be pushed out of the weld. Not only reduces the strength of the weld, but also generates a lot of internal and external burrs, and even causes defects such as welding overlap.