At present, the processing equipment and production lines of mechanical springs are developing in depth and breadth towards numerical control (NC) and computer control (CNC). However, with the changes in spring materials and geometric shapes, the processing technology has also developed.

1) Variable spring outer diameter, variable pitch and variable wire diameter (three-variable) suspension springs have achieved mold-free processing. Since the development of the three-variable spring, conical steel bars have been used for winding on CNC lathes, but the yield and price are not ideal. Now it is changed to a spring coiling machine under heating state, controlling the roller speed and pulling force to obtain the required cone shape, and quenching with the residual heat of processing.

2) The hollow stable spring rod is formed by rolling and welding low-carbon boron steel plates.

3) The torsion bar is made of high-purity 45 steel, which is subjected to high-frequency quenching to obtain high surface hardness and large residual compressive stress, thereby improving fatigue life and anti-relaxation ability.

4) Leaf springs widely used in electronic products are basically formed by stamping and automatic bending. At present, the main focus is on the development of composite material joining technology.

(1) Cold forming process of spring

1) One-time automation capability of cold forming process. Cold forming machines have now developed to 12 claws. Steel wires in the range of (0.3-14) mm can basically be formed in one go in an 8-claw forming machine. The current development direction of forming process equipment: ① Improve the forming speed. The main development trend is to improve the forming speed of the equipment, that is, production efficiency; ② Improve the durability of the equipment by improving the precision of equipment parts and strengthening the heat treatment effect; ③ Add length sensors and laser rangefinders to provide CNC forming machines with automatic closed-loop control of the manufacturing process.

2) Cold forming process range capability. Currently, the maximum specification of large diameter spring coiling machines can reach 20mm, =2000MPa, and winding ratio 5. The cold forming process of variable or equal diameter Minic-Block springs and eccentric springs still has limitations.

(2) Hot forming process of spring

1) Hot forming process speed capability. At present, my country only has CNC 2-axis hot coiling machines for forming (9~25) mm specifications, with a maximum speed of 17 pieces per minute. Compared with developed countries, there is a big gap.

2) Large spring hot forming process control capability. Since there is only a CNC 2-axis hot coiling machine, the shape control has less effect in three directions and the accuracy is poor; and there is no automatic bar rotation control and adjustment mechanism, so the hot coil spring forming process level and capability are low. Therefore, the spring accuracy level and surface oxidation and decarburization level are also low.