At present, the processing equipment and production lines of mechanical springs are developing towards the depth and breadth of numerical control (NC) and computer control (CNC). However, with changes in spring materials and geometric new shapes, processing techniques have also developed.
1) Suspension springs with variable spring outer diameter, variable pitch and variable wire diameter (three-variable) realize moldless plastic processing. Since the development of three-variable springs, tapered steel bars have been used for winding processing on CNC lathes, but the yield and price are not ideal. Now it is changed to use the spring coiling machine in the heating state to control the roll speed and drawing force to obtain the required cone shape, and use the processing waste heat for quenching.
2) The hollow stabilized spring rod is rolled and welded with low carbon boron steel plate.
3) The torsion bar is made of high-purity 45 steel. After high-frequency quenching, the surface has high hardness and large residual compressive stress, thereby improving fatigue life and anti-relaxation ability.
4) The leaf springs widely used in electronic products are basically formed by stamping and automatic bending. At present, it is mainly to develop the joining technology of composite materials.
(1) Cold forming process of spring
1) One-time automation capability of cold forming process. The cold forming machine has now developed to 12 jaws. The steel wire in the range of (0.3-14)mm can basically be formed at one time by the 8-jaw forming machine. The current development direction of forming process equipment: ①Improve the forming speed, the main development trend is to increase the forming speed of the equipment, that is, the production efficiency; ②Improve the durability of the equipment by improving the precision of equipment parts and strengthening the heat treatment effect; ③Increase the length sensor and Laser rangefinder, automatic closed-loop control manufacturing process for CNC forming machine.
2) Cold forming process range capability. At present, the maximum specification of large wire diameter spring coiling machine can reach 20mm, =2000MPa, and the winding ratio is 5. The cold forming process of reduced 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 coil spring machine for forming on (9~25) mm specifications, with a maximum speed of 17 pieces per minute. Compared with developed countries, the gap is large.
2) Large spring hot forming process control ability. Because there is only a CNC2-axis hot-coiling spring machine, the shape control is less effective in three directions, and the accuracy is poor; and there is no automatic bar rotation control and adjustment mechanism, so the hot-coiled spring forming process level and ability are low. Therefore, the precision level of the spring and the level of surface oxidation and decarburization are also low.