Development status of spring technology-Development of spring design
- TAG :
Among the electromechanical products, there are three main types of springs with the largest amount:
1) Motor vehicle springs based on automobiles;
2) Electronic product springs based on household appliances;
3) The springs of optical devices based on video cameras, copiers and cameras.
Motor vehicle springs are mainly developed in the direction of high strength to reduce the quality; electronic product springs are mainly developed in the direction of miniaturization; and the springs of optical devices are mainly developed in the direction of both high strength and miniaturization. Corresponding spring design methods, materials and processing technologies have been developed.
Development of spring design
At present, the widely used spring stress and deformation calculation formulas are derived from the mechanics of materials. Without certain practical experience, it is difficult to design and manufacture high-precision projectiles. As the design stress increases, many previous experiences are no longer applicable. For example, after the design stress of the projectile is increased, the helix angle is increased, which will transfer the fatigue source of the spring from the inner side of the coil to the outer side. To this end, sophisticated analytical techniques must be used, and the currently widely used method is the finite element method (FEM).
The characteristics of vehicle suspension projectiles are that in addition to sufficient fatigue life, their permanent deformation should be small, that is, the anti-loose performance should be within the specified range, otherwise the center of gravity of the vehicle body will shift. At the same time, the impact of environmental corrosion on its fatigue life should be considered. As the maintenance period of vehicles increases, more stringent requirements are put forward for permanent deformation and fatigue life. For this reason, high-precision design methods must be adopted. The finite element method can predict in detail the impact of projectile stress on fatigue life and permanent deformation, and can accurately reflect the relationship between material and spring fatigue life and permanent deformation.
In recent years, the finite element method design method of spring has entered the practical stage, and many reports of practical value have appeared, such as the influence of helix angle on spring stress; the relationship between stress and fatigue life calculated by finite element method.
Comparing the calculation with the current design method and the finite element method to analyze the stress. For the springs of the same structure, under the same load, it can be seen from the figure that the stress of the wind and grass with few effective loops or large helix angle, the results obtained by the two methods are quite different. This is because as the helix angle increases and the load is eccentric, the outer diameter or lateral deformation of the spring is greater, and the stress is also greater. The current design calculation method can not accurately reflect it, but the finite element method can reflect it more accurately.
In addition, an optimized design was introduced in the design of the spring. The structure of the spring is relatively simple, the function is simple, and the parameters that affect the structure and performance are saved. Therefore, those who do not think about it use the analytical method very early. The skin solution method can be used to find the optimal design plan.
With the development of computing technology, the use of computers to optimize the design of non-linear programming has achieved results.
Reliability design is a series of analysis and design techniques adopted in order to ensure the reliability of the designed product. Its task is to make the designed product reach the specified reliability target on the basis of predicting and preventing the possible failure of the product. value. It is a supplement and improvement to the traditional design method. Spring design has made some progress in the use of reliability technology, but further improvement requires the development and accumulation of data.
With the development of spring application technology, many new problems that need to be paid attention to and solved have also been raised for designers. For example, the influence of material, strong pressure and shot peening treatment on fatigue performance and loose performance is difficult to calculate accurately during design; it depends on experimental data to determine; another example is the number of turns calculated according to the current design formula, the stiffness of the made spring is higher than the design The stiffness value is small, and the effective number of turns needs to be reduced to meet the design requirements.