Oil fume machines, electric fans, exhaust fans, Bathroom Heaters and even air conditioners are fan-type household electrical appliances, which rely on the high-speed rotation of the impeller to drive the rapid air flow in order to achieve the purpose of work.
Careful attention has been paid to the dynamic balance of the impeller of the oil smoke suction machine. When disassembling and measuring the structure of various oil smoke suction machines, special attention has been paid to the structural characteristics of the impeller of the oil smoke suction machine. When investigating the production plants of oil smoke suction machines in Zhejiang, Jiangsu and Guangdong, we intentionally and specially understand the control degree of each manufacturer to the dynamic balance of the impeller. It is therefore observed that some manufacturers are actually dealing with the dynamic balance of the double-sided balancer impeller by means of the dynamic balance of the single-sided balancer impeller.
In fact, this problem is very easy to find: if the impeller is confirmed to be a double-sided dynamic balancer, at least two balancing plates should be observed on the impeller; If the impeller belongs to double-sided dynamic balancing machine and only one balancing plate is observed, it can be considered that the dynamic balancing treatment to the impeller is improper.
According to the ratio of diameter of fan impeller to disc width of impeller, i.e. the ratio of length to diameter, the impeller can be divided into one-sided dynamic balancer impeller and two-sided dynamic balancer impeller.
When the diameter of the impeller is 7-10 times larger than the width of the impeller (i.e. the projected thickness on the side of the impeller), i.e. the length-diameter ratio is greater than l/10-1/7, it belongs to the impeller of one-sided dynamic balancing machine. Electric fans, exhaust fans, etc. are of this type. In this case, if the impeller is found to have dynamic imbalance, the centroid of the impeller deviating from the centroid can be restored to the centroid position and the impeller can be balanced by installing a correcting mass of the same torque on any part of the impeller centroid diameter (see Figure 1).
For impellers with L/D ratio less than 1/10~1/7, the above method is not applicable. Impellers with L/D ratio less than 1/10~1/7 belong to the impeller of double-sided balancer. On the impeller of double-sided balancing machine, when the impeller is in the state of no power drive, if two equal masses are allocated at both ends of the axes and the axes are symmetrical, then the centroid of the impeller does not show the problem of deviating from the rotating axis of the impeller, and the impeller is actually in a state of "static balance"; However, once the impeller enters the high-speed rotating state, the centrifugal forces produced by the two mass will form a force couple, and the inertial and rotating shafts of the impeller will no longer coincide, resulting in strong vibration of the bearing of the impeller; Or the mass of the two pieces is not symmetrical, and the inertia shaft and the rotating shaft are inclined, so the centroid of the impeller deviates from the axis, and the vibration of the impeller increases significantly when it rotates. This is the most common dynamic imbalance in the double-sided dynamic balancer impeller. To eliminate this dynamic imbalance of the impeller, corrective mass must be installed on at least two planes (see Figure 2).
In addition, the impeller of fan-type household electrical products is generally a kind of "cantilever" rotor structure, that is, the impeller is only supported at one end of the connection between the impeller and the main shaft of the motor, and the impeller is in a suspended state. It can be regarded as a "cantilever beam" structure in structural mechanics, which can not be ignored when analyzing the dynamic balance of oil fume (see Figure 2).
After knowing the classification mode of dynamic balance type of impeller, it can be judged that the impeller of oil fume machine belongs to the impeller of cantilever double-sided dynamic balance machine. During the series of process of design, manufacture, installation, application and maintenance of the oil fume machine, it is very critical to clearly recognize the type characteristics of the impeller dynamic balance of the oil fume machine.
According to the data collected at present, it is considered that most of the impellers selected in the current production of cigarette fume machines belong to the impellers of cantilever double-sided dynamic balancer.
From the view of all kinds of oil fume machine impellers disassembled and measured by technicians, the diameter of oil fume machine impellers at this stage is usually about 200 mm (190 mm for smaller diameter and 220 mm for larger diameter). According to the division method of "one-sided balancer" impeller and "two-sided balancer" impeller, if the diameter of impeller is 210 mm, The width of impeller (as centrifugal impeller is widely used in oil smoke suction machine at present, its width state is very obvious from the side) should be between 21 and 30 mm; That is to say, when the width of impeller is not more than 30mm, the impeller with 210mm diameter can be centroid balanced by one-sided balancing method to ensure that the impeller does not vibrate abnormally at high speed due to the dynamic balance state of impeller.
Careful attention has been paid to the dynamic balance of the impeller of the oil smoke suction machine. When disassembling and measuring the structure of various oil smoke suction machines, special attention has been paid to the structural characteristics of the impeller of the oil smoke suction machine. When investigating the production plants of oil smoke suction machines in Zhejiang, Jiangsu and Guangdong, we intentionally and specially understand the control degree of each manufacturer to the dynamic balance of the impeller. It is therefore observed that some manufacturers are actually dealing with the dynamic balance of the double-sided balancer impeller by means of the dynamic balance of the single-sided balancer impeller.
In fact, this problem is very easy to find: if the impeller is confirmed to be a double-sided dynamic balancer, at least two balancing plates should be observed on the impeller; If the impeller belongs to double-sided dynamic balancing machine and only one balancing plate is observed, it can be considered that the dynamic balancing treatment to the impeller is improper.
According to the ratio of diameter of fan impeller to disc width of impeller, i.e. the ratio of length to diameter, the impeller can be divided into one-sided dynamic balancer impeller and two-sided dynamic balancer impeller.
When the diameter of the impeller is 7-10 times larger than the width of the impeller (i.e. the projected thickness on the side of the impeller), i.e. the length-diameter ratio is greater than l/10-1/7, it belongs to the impeller of one-sided dynamic balancing machine. Electric fans, exhaust fans, etc. are of this type. In this case, if the impeller is found to have dynamic imbalance, the centroid of the impeller deviating from the centroid can be restored to the centroid position and the impeller can be balanced by installing a correcting mass of the same torque on any part of the impeller centroid diameter (see Figure 1).
For impellers with L/D ratio less than 1/10~1/7, the above method is not applicable. Impellers with L/D ratio less than 1/10~1/7 belong to the impeller of double-sided balancer. On the impeller of double-sided balancing machine, when the impeller is in the state of no power drive, if two equal masses are allocated at both ends of the axes and the axes are symmetrical, then the centroid of the impeller does not show the problem of deviating from the rotating axis of the impeller, and the impeller is actually in a state of "static balance"; However, once the impeller enters the high-speed rotating state, the centrifugal forces produced by the two mass will form a force couple, and the inertial and rotating shafts of the impeller will no longer coincide, resulting in strong vibration of the bearing of the impeller; Or the mass of the two pieces is not symmetrical, and the inertia shaft and the rotating shaft are inclined, so the centroid of the impeller deviates from the axis, and the vibration of the impeller increases significantly when it rotates. This is the most common dynamic imbalance in the double-sided dynamic balancer impeller. To eliminate this dynamic imbalance of the impeller, corrective mass must be installed on at least two planes (see Figure 2).
In addition, the impeller of fan-type household electrical products is generally a kind of "cantilever" rotor structure, that is, the impeller is only supported at one end of the connection between the impeller and the main shaft of the motor, and the impeller is in a suspended state. It can be regarded as a "cantilever beam" structure in structural mechanics, which can not be ignored when analyzing the dynamic balance of oil fume (see Figure 2).
After knowing the classification mode of dynamic balance type of impeller, it can be judged that the impeller of oil fume machine belongs to the impeller of cantilever double-sided dynamic balance machine. During the series of process of design, manufacture, installation, application and maintenance of the oil fume machine, it is very critical to clearly recognize the type characteristics of the impeller dynamic balance of the oil fume machine.
According to the data collected at present, it is considered that most of the impellers selected in the current production of cigarette fume machines belong to the impellers of cantilever double-sided dynamic balancer.
From the view of all kinds of oil fume machine impellers disassembled and measured by technicians, the diameter of oil fume machine impellers at this stage is usually about 200 mm (190 mm for smaller diameter and 220 mm for larger diameter). According to the division method of "one-sided balancer" impeller and "two-sided balancer" impeller, if the diameter of impeller is 210 mm, The width of impeller (as centrifugal impeller is widely used in oil smoke suction machine at present, its width state is very obvious from the side) should be between 21 and 30 mm; That is to say, when the width of impeller is not more than 30mm, the impeller with 210mm diameter can be centroid balanced by one-sided balancing method to ensure that the impeller does not vibrate abnormally at high speed due to the dynamic balance state of impeller.
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