◆ Spring wire diameter d: The diameter of the wire used to make the spring.
◆ Outside diameter of spring D: The maximum outside diameter of the spring.
◆ Spring inner diameter D1: the minimum outer diameter of the spring.
◆ Spring middle diameter D2: the average diameter of the spring. Their calculation formula is: D2 = (D + D1) ÷ 2 = D1 + d = D-d
◆ t: Except for the support ring, the axial distance on the middle diameter of the corresponding points of the two adjacent turns of the spring becomes the pitch, which is represented by t.
◆ Effective number of turns n: the number of turns that the spring can maintain at the same pitch.
◆ Number of support turns n2: In order to make the spring receive uniform force during work, ensure the vertical end surface of the axis. When manufacturing, the two ends of the spring are often tightened. The number of tight turns only supports and is called a support ring. Generally there are 1.5T, 2T, 2.5T, and 2T is commonly used.
◆ Total number of turns n1: Sum of effective number of turns and support. That is n1 = n + n2.
◆ Free height H0: The height of the spring without external force.
◆ Spring unfolded length L: the length of steel wire required when winding the spring.
◆ Spiral direction: There are left and right rotations, and right rotation is commonly used. If the drawing does not indicate, right rotation is generally used.
◆ Spring winding ratio; ratio of middle diameter D to wire diameter d.