In the configuration of the motor bearing system, springs are often used to preload some bearings. Large motors generally use cylindrical springs, and small motors often use wave springs or disc springs.
Wave springs generate spring force by the bending moment of the wave shape, but conventional wave springs generate spring force by the torque of the winding wire. Wave springs occupy only 50% of the axial space and also have a more linear force curve compared to the deflection range.
The role of the wave spring in the motor bearing system is to apply axial and load. The spring force of the spring is equal to the required preload value, that is, the spring force of the wave spring at the test height is within the range of the axial preload value required by the bearing. If it exceeds this range, the wave spring will wear out.
However, if this kind of wear occurs, it is not conducive to the spring and the preload of the bearing. Then, why does such wear occur after the spring is squeezed and deformed?
The possibility of vibration of the bearing connection during operation is high, and the direction of the vibration may have radial and axial components, and the contact friction between the bearing end face and the wave spring occurs. When such wear occurs, if we use our wave spring, not only can preload be applied to the bearing, but also part of the free movement of the bearing can be eliminated, and the noise of the bearing can be reduced. In addition, the wear of the corrugated spring may have severe lace on the outer ring of the bearing.
In the motor, when an axial force is applied to the spring, the wave spring deforms within a reasonable range without compromising the spring’s ability, even if it exceeds the deformation range, the wave spring loses its elastic force. Considering the elasticity of the metal, it will not break, so how does the wave spring fracture encountered in the actual situation form?
Metal fracture is caused by fatigue. The reason is the same as the fatigue of bearings. Shear stress occurs repeatedly, and fatigue often occurs after reaching a certain number of times.
The wave spring is only under the action of shear stress, and fatigue damage is difficult to occur, which must be the result of the reciprocating occurrence of shear stress. The possibility for a motor is that with the motor vibrating, the wave spring is likely to compress, rebound, compress, and rebound, in which case the spring is likely to break.
Corrosion and prevention of wave spring
Corrosion reactions will affect the life of wave springs, causing aging and corrosion. According to the corrosion reaction of the spring, it is divided into chemical corrosion and electrochemical corrosion according to the type of reaction, which are the result of the change of the metal atoms on the surface of the spring, or the result of the gain and loss of electrons to reach the ion state.
- Chemical corrosion
Assuming that the metal on the surface of the spring only reacts chemically with the surrounding medium, the corrosion caused by the spring is called chemical corrosion. For example, the spring is oxidized to form an oxide film in a very dry atmosphere, and the spring chemically changes with the liquid or impurities in the liquid in the non-electrolyte liquid, which is chemical corrosion.
- Electrochemical corrosion
Assuming that the spring is in contact with the electrolyte, the corrosion caused by the microbattery effect is called electrochemical corrosion. For example, if the spring is exposed to acid or salt solution, this solution is an electrolyte. Due to the defects and impurities on the surface of the spring, electrodes with different potential differences will be formed. The spring that is constantly subjected to electrolytic corrosion will undergo different chemical reactions according to the situation. Therefore, in the process of using the spring, please try to prevent the above situation, reduce the corrosion of the spring, and improve the life of the spring.
Ways to Prevent Early Corrosion of Wave Springs
As a method to prevent early corrosion of wave springs, we often use wave springs in our lives, but due to chemical and electrochemical reactions, the contact surface of the springs will corrode to a certain extent, damage the springs, and affect the function of the device.
How to avoid early corrosion of the spring?
Spring anti-corrosion methods include coating, oxidation, and electroplating. These anti-corrosion principles are to form a protective layer on the surface of the spring to isolate the spring from the outside world, thereby achieving the purpose of anti-corrosion.
- Coating: Applying protective coating to the center of the spring surface is one of the main methods of spring anticorrosion. It is mostly used for large and medium-sized springs, especially thermoformed springs and leaf springs. The commonly used coating methods are coating and dip coating. The development of technology will carry out new technologies such as improving working power, coating utilization rate and coating quality, and electrostatic coating.
- Oxidation treatment: The oxidation treatment of the spring is also called blue or blackening. After the oxidation treatment, a protective magnetic iron oxide is produced on the surface of the spring, with a thickness of about 0.6~2um. Due to the thin film, many voids and low protection ability, oxidation treatment can only be used for spring anticorrosion in low corrosive medium. Due to the low cost of oxidation treatment, simple process formula, high productivity, and no influence on spring characteristics, it is widely used in the surface anticorrosion of cold-formed small springs.
- Electroplating: Electroplating is an effective method to obtain a protective layer on the metal surface, and it is also the main method for anti-corrosion treatment of wave springs. It has the characteristics of good adhesion, compact crystallization, small pores, uniform thickness, and excellent physical, chemical, and mechanical properties. Electroplating includes zinc plating, chrome plating, copper plating, tin plating, nickel plating, and the common application is zinc plating. The surface of spring galvanized is generally white or colored. Zinc hardly changes in dry air. In humid air and water containing carbon dioxide, a white zinc oxide film will be formed, which acts as a corrosion inhibitor. Zinc coating is suitable for various atmospheric conditions, but its corrosion resistance is poor in aqueous solutions containing acids, alkalis, and salts, and pure marine atmospheric conditions. Galvanized is characterized by beautiful appearance, low cost, simple process and good effect, and is widely used in the anticorrosion of small springs in the atmosphere.
Zhejiang Lisheng Spring Co., Ltd. is a member enterprise of China Spring Association and a national high-tech enterprise. Since 2012, the company has started to develop wave springs, spiral retaining rings, wave spring washer, overlap wave spring and laminar seal rings. We look forward to establishing a mutually beneficial and win-win cooperation relationship with you.