The longitudinal seam (or seams) are then welded by automatic arc-welding equipment.
Several consecutive forming rolls then shape the strip into a tube with a longitudinal seam on top, as shown schematically in A in the figure.
Experiments are conducted on 12 models made of stainless steel by rolling and longitudinal seam welding.
Micro channel tube is formed with porthole extrusion die, and the longitudinal seam welding problem is the key issue related to both the design of the delicate mandrel in the extrusion die and the pressure bearing capacity of the tube.
In porthole die extrusion process of aluminum alloy profiles, the formation of longitudinal weld seams (L-seams) is inevitable.
Predicting and decreasing the length of transverse weld seam (T-seam), improving the solid-state bonding degree and controlling microstructure of longitudinal weld seam (L-seam) are major concerns.
A weld seam between two bars was formed under hydrostatic pressure in a specially designed die setup to simulate the longitudinal weld seam formation during extrusion through porthole die.
Because of the insufficiency of observation data in the longitudinal direction, moreover, the coal seam belongs to the flat seam, which is stable, therefore, the angle parameters of transverse direction were mainly analyzed.
The mining-induced fractures developed 8.0 30 m above the mined No. 11-2 seam, which was 7.525 times of the seam mining height, the fracture zone was about 65° upward from the seam open-off cut toward the goaf, the height of longitudinal joint growth was 4 20 times of the seam mining height, the height of lateral joint growth is 20 25 times of the seam mining height.
The mining-induced fractures developed 8 30 m above the mined No. 11-2 seam, which was 7.525 times of the seam mining height, the fracture zone was about 65° upward from the seam open-off cut toward the goaf, the height of longitudinal joint growth was 4 20 times of the mining seam height, and the height of lateral joint growth was 20 25 times of the mining seam height.
