Spiral pre-precision-welding weld-in three-wire spearhead

The utility model relates to a spiral pre-precision-welding weld-in three-wire spearhead. At present, double-wire welding is generally adopted in spiral submerged-arc welding, but the double-wire welding is not suitable for producing steel pipes with the minimum diameter of 508mm, and the production efficiency is low. Some three-wire spearheads exist, but the distance or the angle among three wires cannot be adjusted, and the existing three-wire spearheads are small in application range. The spiral pre-precision-welding weld-in three-wire spearhead comprises a spearhead installation support (1), a sliding groove (2) is formed in the spearhead installation support (1), a second spearhead (3) is fixedly installed in the middle of the sliding groove, a first spearhead (4) and a second spearhead (5) are movably connected on two sides of the sliding groove respectively, a regulating screw rod (6) is connected between the first spearhead and the second spearhead, and a regulating screw rod (6) is connected between