The forming angle refers to the acute angle formed by the intersection of the horizontal projection of the steel pipe centerline and the steel strip centerline, commonly denoted as α. The forming angle is the most critical parameter in the forming process of spiral submerged arc welded (SSAW) pipes. It not only indicates the angle at which the steel pipe centerline should be inclined relative to the steel strip centerline, but also determines the position of the machine set on the rolling line, which is crucial for the rational matching of the steel pipe diameter and the steel strip width. A spiral formation can only be achieved when the forming angle is less than 90°. The spiral formation is the result of the functional relationship between B, D, and α:
D = B / (π * cosα)
Where:
D: Steel pipe diameter
B: Steel strip width
α: Forming angle
What is the formula for calculating the forming angle?
The formulas for calculating the forming angles between the front bridge and each roll (#1, #2, #3) are not explicitly given in the question, but they typically involve geometric relationships and the dimensions of the steel strip and pipe. However, here's a general approach that can be used to derive such formulas, based on the principles of spiral pipe formation:
Assuming a simplified model, the relationships between the front bridge and the rolls might be approximated by considering the geometry of the spiral formation and the path of the steel strip as it wraps around the forming rolls. These calculations would typically involve trigonometric functions and geometric constraints specific to the machine configuration.
Since the exact formulas depend on the specific design of the pipe mill and the configuration of the rolls, here are placeholders for the formulas that would typically need to be determined by the machine manufacturer or designer:
Front bridge to #1 roll forming angle = (Function of B, t, D, and machine geometry)
Front bridge to #2 roll forming angle = (Function of B, t, D, and machine geometry)
Front bridge to #3 roll forming angle = (Function of B, t, D, and machine geometry)
Where:
B = Steel strip width, mm
t = Nominal wall thickness of the steel pipe, mm
D = Nominal outer diameter of the steel pipe, mm
Note: The actual formulas would need to be derived based on the detailed design of the pipe mill and the spiral forming process. These formulas are not universally applicable and would vary from one machine to another.
