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Talking about the causes and adjustment of vibration during elevator operation

Apr 10, 2019

The elevator home today talks about the causes of vibration during the operation of the elevator and the adjustment method:

       Modern elevators require good ride comfort. However, during the operation of the elevator, vibration phenomenon often occurs. Especially in the process of elevator acceleration and deceleration, about 1/3 to 2/3 of the rated speed range is prone to severe vibration. If the oscillation frequency is close to or even equal to the natural oscillation frequency of the system, it will cause severe mechanical resonance, which will affect the comfort of riding. Therefore, we must analyze the causes of the vibration phenomenon and take effective measures to adjust.

       There are two main reasons for the vibration: mechanical and electrical:

       1. Mechanical reasons and adjustment measures

       (1) The unbalanced mass of the traction machine is the main source of vibration that causes the mechanical resonance of the traction system. For new elevators, this has been considered during design and manufacturing. Generally, this factor does not exist; if this is found at the commissioning site, the quality of the rotating mass must be balanced or replaced. For the use of elevators, when wearing or replacing some parts of the traction machine, it is easy to cause imbalance due to factors such as the quality of the parts and the installation process. For example, an elevator in a hotel was replaced due to the wear of the traction sheave. Due to the unreasonable assembly process, the rotating mass was unbalanced, and severe vibration occurred after the repair.

       (2) The gap between the worm wheel and the worm is not suitable. This type of factor generally occurs when an elevator is used, due to wear.

       (3) The gap between the two sides of the electromagnetic brake is not uniform, resulting in uneven tension during operation. The clearance between the two sides should be adjusted to 0.5 to 0.7 mm.

       (4) If the vibration reduction measures are improper, the rotation of the sheave is not flexible.

       (5) The guide bolts of the guide rails are loose, the bolts of the car body are loose, and the fixing bolts of the traction machine base and the load-bearing beam are loose, which will cause vibration or vibration of the running, and can be tightened to the corresponding parts.

       (6) The rail mounting is not vertical, the gauge is large in the whole length range, and the step of the rail joint is not flat and the step is large. These need to be corrected according to international regulations.

       (7) If the car is tilted or the heavy cargo is placed on the side of the car, causing the car to tilt, it will cause more jitter. It should be adjusted or placed correctly so that it is tilted no more than 3 inches.

       (8) The traction wire rope is not evenly stressed, and it is easy to form abnormal vibration, which will cause the car to shake. It should be adjusted so that the tension difference between the ropes is not more than ±5%.

       (9) The safety clamp wedge and the guide rail have uneven clearance, which causes the grinding rail to be adjusted.

       2. Electrical reasons and adjustment measures

       (1) The interference signal of the speed feedback is one of the important causes of system oscillation and mechanical resonance. Modern elevators generally use photoelectric code discs as speed feedback signals. In addition to paying attention to their own quality, they should also pay attention to their connection with the motor. Usually pay attention to its clean, so as not to block the dust and cause its receiving pulse is not normal. Also pay attention to protect the disc, do not make it twisted or damaged, otherwise it should be replaced.

       (2) The car oscillates at a low speed due to harmonic torque, causing the car to vibrate vertically. This vibration is related to the moment of inertia of the system. In addition, it is related to factors such as whether the regulator parameters match, the symmetry of the three-phase voltage, and the balance procedure of the three-phase current. Therefore, the regulator parameters should be carefully adjusted to adjust the three-phase current symmetry. Also note that the low speed reference cannot be too low.

       (3) A change in the system flywheel moment due to a random change in load.

       (4) The medium speed reference speed falls in the mechanical resonance region, causing a large vibration. The medium speed setpoint should be re-set to leave the resonance zone.

       In short, there are many reasons for the vibration during the operation of the elevator. It may be caused by a certain factor or a combination of various factors. The corresponding measures should be taken in combination with the actual situation.

This article label: talk about the vibration during the elevator operation