(1) the diameter of the spring wire d: the diameter of the copper wire used to make the spring wire;
(2) Spring coil diameter D: the outer diameter of the spring wire;
(3) Spring wire inner diameter D1: the inner diameter of the spring wire;
(4) Spring wire spiral length L: The static length of the spring wire under the action of no external force;
(5) Spring wire working length L0: the dynamic length of the spring wire sitting under the external force;
(6) The length of the spring wire unrolled A: The total length of the straight line required to wind the spring wire;
(7) The tail length of spring wire: two tails are denoted by L1 and L2 respectively;
(8) Spiral direction: There is a left and a right rotation, and the right-hand rotation is commonly used. The drawing does not indicate the general use of right-hand rotation.