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) The suspension spring with variable spring outer diameter, variable pitch and variable steel wire diameter (three-variable) realizes 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 under 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 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: ①Increase 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 the 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 variable diameter or equal diameter material Minic-Block spring and eccentric spring still has limitations.
(2) Hot forming process of spring
1) Hot forming process speed capability. At present, our country only has CNC 2-axis hot coiling 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 coil 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 coil spring forming process is level