What are the common mechanical failures and solutions for semi-automatic spring brush machines for series excitation motor motors?
First, the brush device failure
1、Brush jumping
Causes: uneven brush spring pressure, uneven brush wear, uneven commutator surface. When the spring pressure is not uniform, it will lead to uneven force on the surface of the commutator, thus generating the phenomenon of jumping; uneven wear of brushes makes the contact state of brushes and commutator unstable; and uneven surface of the commutator will directly cause brushes not to be able to make smooth contact in the operation process.
Solution: First of all, use a manometer to check the spring pressure of brushes to make sure that the difference of spring pressure of each brush is within the permissible range, and the general requirement is that the difference of pressure should not be more than 5% - 10%. For unevenly worn brushes, replace the brushes with new ones and ensure that the contact area between the brushes and the commutator is not less than 75% of the cross-sectional area of the brushes. If the surface of the commutator is uneven, you can use fine sandpaper to sand the surface of the commutator, sanding to ensure that the cylindricity of the commutator and the surface roughness to meet the requirements, the surface roughness is generally controlled in Ra0.8 - Ra1.6μm.
2、Brush stuck in the brush grip
Reason: the gap between the brush and the brush grip is too small, the brush is swollen by moisture, and there are impurities in the brush grip. Too small a gap will make the brush in the brush grip movement is blocked; brush moisture volume becomes large, easy to get stuck in the brush grip; brush grip impurities will increase the friction, hindering the normal sliding of the brush.
Solution: Check the gap between the brush and the brush grip, generally the one-sided gap should be between 0.1 - 0.3mm, if the gap is too small, you can grind the brush grip properly or replace the brush. For the brushes that are damp, dry them in the oven at 100-120℃ for 2-3 hours. Clean up the impurities in the brush grip, you can use clean compressed air to blow away or clean up with a brush.
Second, the transmission mechanism failure
1, belt slippage
Reason: insufficient belt tension, belt wear and tear, oil between the belt and pulley. Belt tension is not enough to provide sufficient friction to transfer power; excessive belt wear will reduce the friction coefficient between the belt and the pulley; oil will reduce the friction between the belt and the pulley, resulting in slippage.
Solution: Adjust the belt tension. For flat belt, it can be adjusted by moving the motor position so that the belt's sag does not exceed 1.5% - 2% of the center distance between the two pulleys under medium load. For V-belts, tension can be measured with a tensiometer, generally according to the belt model and pulley diameter to determine the appropriate tension value. If the belt is badly worn, it should be replaced with a new one, and at the same time make sure that the belt model matches the pulley. Clean up the oil on the surface of the belt and pulley, you can use cleaner to wipe clean.
2、Gear wear or damage
Causes: long-term overload operation, poor lubrication, poor or defective gear material, poor gear meshing. Long-term overload will make the gears under excessive pressure, accelerating wear; insufficient lubrication will increase the friction between the gears, resulting in wear of the tooth surface; gears themselves have problems with the material will affect its wear resistance; poor meshing will make the gears uneven force, localized wear increased.
Solution: Check the motor load, avoid overload operation, and reasonably adjust the working parameters of the motor according to the actual load condition. Ensure good lubrication of gears, regular inspection and add lubricant, for high speed and heavy load gear transmission, can use lubricant containing extreme pressure additives. For worn or damaged gears, to be replaced in a timely manner, replacement should pay attention to the modulus of the gear, the number of teeth, pressure angle and other parameters must be the same as the original gear, and to ensure that the installation accuracy of the gear, such as the tooth side clearance is generally controlled in the 0.08 - 0.3mm between.
Third, the spring mechanism failure
1, spring fracture
Reason: poor quality of spring material, spring long-term fatigue, spring corrosion, more than the elastic limit of the spring. If the spring material itself is not quality, its strength and toughness is difficult to ensure; long time and frequent expansion and contraction will make the spring fatigue cracks, the back lead to fracture; in a corrosive environment, the spring is easy to be corroded and damaged; when the external force exceeds the spring's elasticity limit, it will directly result in spring damage.
Solution: Replace the springs with qualified quality, and choose spring materials with good fatigue resistance and corrosion resistance, such as stainless steel springs. In the design of the spring, according to the actual working conditions to reasonably determine the parameters of the spring, such as the working load, deformation, etc., to avoid long-term fatigue of the spring. For the spring working in a corrosive environment, protective measures can be taken, such as surface galvanizing, painting, etc..
2、Spring elasticity weakening
Reason: elastic fatigue caused by long-term use, high-temperature environmental impact, spring material aging. With the increase of the use of time, the internal organization of the spring structure will change, resulting in a decline in elasticity; in a high-temperature environment, the spring's modulus of elasticity will be reduced, thus making the elasticity weakened; the aging of the spring material will also deteriorate its performance.
Solution: For springs with weakened elasticity, the decision to replace them should be made according to the actual situation. If the elasticity of the spring is weakened to a lesser extent, it can be continued by adjusting the working parameters of the spring, such as appropriately reducing the working load of the spring. When designing, the influence of the working environment temperature on the spring should be taken into account, and suitable spring materials should be selected. For springs working in high-temperature environments, high-temperature-resistant spring materials, such as nickel-based alloy springs, can be used. At the same time, to avoid prolonged exposure of springs in harsh environments to extend their service life.
Fourth, the body and other parts failure
1, motor vibration is too large
Reason: the motor installation foundation is not solid, the motor shaft and the load shaft is not concentric, rotor imbalance, bearing wear. The installation foundation is not solid will make the motor shake during operation; the shaft is not concentric will lead to periodic vibration when the motor is rotating; the rotor is not balanced will make the motor generate centrifugal force when rotating and cause vibration; the bearing is worn out will make the motor's rotating precision decrease and generate vibration.
Solution: Check the motor mounting foundation to ensure that it is firm and reliable. For large motors, damping pads or shock absorbers can be used to reduce vibration. When using couplings or pulleys to connect the motor and the load, the concentricity of the shaft should be adjusted accurately, and the concentricity error is generally no more than 0.05 - 0.1 mm. For rotor imbalance, carry out rotor dynamic balancing calibration, and you can add balancing blocks to both ends of the rotor to correct the amount of imbalance. If the bearings are worn, the bearings should be replaced in a timely manner, after replacement to ensure that the installation accuracy of the bearings, such as the radial clearance of the bearings should meet the specified requirements.
2、Damaged shell
Reason: external impact, long-term exposure to harsh environments leading to corrosion, material aging. External impact may directly cause shell rupture or deformation; in a corrosive environment, shell metal materials will gradually be corroded; with the passage of time, the performance of the shell material will decline, aging phenomenon.
Solution: For the shell damaged by external impact, if the damage is light, it can be repaired, such as the use of metal patching agent for filling and reinforcement. If the damage is serious, the shell should be replaced. For motors working in harsh environments, the shell can be anticorrosive treatment, such as spraying anticorrosive paint, the use of anticorrosive materials wrapped and so on. For the aging shell, according to the degree of aging to decide whether to replace, at the same time, pay attention to check whether the electrical components inside the shell is affected.
※ If the above ways and means still can not solve the equipment failure, please contact Xinhui Electromechanical Equipment Co., Ltd. through the page chat tool to seek help.
