Gears are often located in key parts of mechanical equipment, so the wear and failure of gears will bring great losses to the equipment. Gear failures are often caused by gear tooth failure. 4 种情况及解决措施。 This article shares four cases of gearbox transmission failure and their solutions.
、减速机和齿轮的介绍 1.Introduction of reducer and gear
减速机的类型 1.1 Type of reducer
The reducer includes a worm gear reducer, a harmonic reducer, and a planetary reducer. Among them, the worm gear reducer has the function of reverse self-locking, and the deceleration is relatively large. The input shaft and the output shaft are not on the same axis and are not on the same plane. This type of reducer has poor transmission efficiency and high accuracy.
Harmonic reducer mainly uses the controllable elastic deformation of flexible elements to transmit power. Its accuracy is high, but the life of the flexible wheel is short, the ability to withstand impact force is poor, and the transmission rate is not high.
The planetary reducer has a compact structure, a small backlash, high accuracy, a long service life, and a large rated output torque, but the cost of this reducer is too high.
齿轮的相关知识 1.2 Related knowledge of gears
The accuracy of gears generally considers economic factors, but the accuracy level of gears has a great impact on the generation of noise and backlash, and the noise produced by high-precision gears is smaller.
For the gear width, increasing the gear width can reduce the unit load under constant torque. When the torque is constant, the small gear is more noisy than the large gear. Increasing the gear width can also increase the bearing capacity of the gear.
A small pitch can ensure that as many gear teeth as possible contact at the same time, which can reduce transmission noise and improve transmission accuracy. A smaller pressure angle can reduce gear operation noise and increase accuracy.
When designing and manufacturing gears, attention should be paid to gear errors, including pitch error and tooth direction error. The elimination of these errors can improve the accuracy of the gear and ensure the efficiency of the reducer.
When the assembly is not concentric, the shafting will be unbalanced. If the high-precision gears are unbalanced, the accuracy of the gearing will be greatly affected. It can also damage the effectiveness of the reducer.
Tooth surface hardness is also an important factor affecting the effectiveness of the reducer gear operation. Low tooth surface hardness will cause the gear operation of the reducer to fail.
、减速机齿轮失效的形式及解决措施 2. Forms and solutions of gear reducer failure
齿轮断齿造成失效 2.1 Gear failure due to broken teeth
The failure of gear teeth is the most serious situation in the entire mechanical engineering, mainly including overload fracture, random fracture of fatigue fracture, etc. For overload fracture, refers to the tooth fracture that occurs when the gear is severely overloaded one or more times. In this case, the fracture of the gear is generally located at the root of the gear, and the fracture is generally straight and rough.
Fatigue fracture refers to the fact that the gear root causes fatigue cracks and fractures in the long-term high-cycle state. The fracture can be divided into the fatigue fracture surface and the final fracture surface. No plastic deformation is seen in the fatigue fracture area. The end of the gear. Random breakage usually also occurs at the root of the gear, but special cases also occur in other parts.
There are many measures to prevent gear breakage. You can increase the fillet radius of the tooth root, eliminate machining tool marks on this part in order to reduce the stress concentration of the tooth root, and increase the stiffness of the shaft and support to reduce local impact. The degree of force can also be used to perform cold work such as shot blasting and rolling to improve the tooth surface.
齿面磨损无法传动 2.2 tooth surface wear can not be transmitted
During the gear transmission of the reducer, the wear on the tooth surface is unavoidable. The tooth surface wear also includes adhesive wear, abrasive wear, abrasion, corrosion wear, and burns. For adhesive wear, it mainly refers to lubrication. If the lubricating oil layer is complete and the thickness is relatively thick, the contact between metals will be reduced, and no wear will occur.
If the oil film temperature and pressure are the same, then the higher the viscosity of the oil, the less the wear. Under low speed, heavy load, extreme temperature, etc., the oil film may be damaged. In this case, the wear occurs in the large area except the pitch circle. Partial gear tooth surface. This wear can be improved by increasing the hardness of the tooth surface, reducing the roughness of the tooth surface, and increasing the viscosity of the oil.
Abrasive wear and abrasion mainly refers to the presence of impurities in the lubricant or the occurrence of abrasive debris during contact between metals during operation, which causes the gears of the reducer to wear and make the transmission work ineffective.
If the gear is centered well and the abrasion is not caused by the micro-convex encouraged on the pool surface, then the wear of the entire gear will extend to most areas. Corrosive wear refers to the chemical reaction of some substances in the lubricant with the metal on the tooth surface, causing metal corrosion.
齿面点蚀与齿面胶合 2.3 Tooth surface pitting and tooth surface bonding
During the transmission of gears, the contact stress at various points on the contact surface exhibits cyclic fluctuations. After a period of time, cracks will occur due to the fatigue of the metal on the contact surface, and the expansion of the cracks will cause the metal to peel and form pitting. This can be prevented by increasing the hardness of the tooth surface and reducing the surface roughness.
Under the condition of high speed, large load or lubrication failure, the gear will cause local high temperature on the tooth surface, and the contact surface will be glued. This situation is called glue. In order to prevent glue, the hardness and smoothness of the tooth surface should be improved. Different types of gears are used for different types of gears. Correct selection of lubricant is an important measure to reduce gear failure.
齿面塑性变形引起的失效 2.4 Failure caused by plastic deformation of tooth surface
Plastic deformation mainly includes ripples and ridge-like extensions caused by crushing and hammering deformation. Mainly because the gear material is soft, causing metal flow along the friction direction. Temperature and humidity changes in the gear working environment will also cause tooth surface Plastic deformation. Lubricating oil with higher viscosity can be used to prevent plastic deformation and increase the hardness of the tooth surface.
Only by finding the real cause of the failure of the gear transmission of the reducer can we solve the corresponding problems, ensure the effectiveness of the mechanical operation process, improve the operation efficiency, and promote the work.