What should we pay attention to when checking the balance of auto parts?

2020-01-10 09:47:50

The body structure of each car must go through the quality inspection after the production line. Generally, the laser and scanning methods are used to check the stability of each welding point and metal structure. For example, the 360 automatic body measurement technology (auto CMM) we use is to verify the quality of the car body after it is offline.

Of course, in order to verify the safety performance of the body structure, an important part is the front longitudinal impact test. Because in most accidents, the front longitudinal plays a key role in absorbing the collision energy of the whole vehicle. This test requires the vehicle to hit the target at the speed of xxkm / h, and the front longitudinal beam converts the collision energy into internal energy through crushing and bending deformation to ensure the safety of personnel.

For high-speed rotating auto parts such as crankshaft, flywheel, clutch pressure plate, transmission shaft, belt hub, etc., balance test shall be carried out before assembly to check their static balance and dynamic balance. The unbalance of the parts will cause additional load to the parts and the bearings, which will make them vibrate in the work, so as to accelerate the wear and damage of the parts. Therefore, the balance test should be carried out before the final assembly of parts and assemblies to improve the repair quality and extend the service life of the assembly.

The balance of parts and assemblies can be divided into static balance and dynamic balance. The reasons for the imbalance are: the size of the parts is not accurate, the manufacturing quality is not uniform, and the rotating center or axis of the parts is offset due to the errors in the assembly. For example, the static imbalance of the part is caused by the center of gravity of the part leaving the rotating axis of the part. The long part is bent, and the mass distribution along the length is uneven, leading to the start of the imbalance.

Static imbalance. The O-O line is the rotating axis of the disk, the center of gravity of the disk is B, and the distance between the center of gravity and the rotating axis is r. If the disc is supported on the bearing in the way shown in the figure, it can not be stationary at any time (except that the center of gravity can be stationary at the position of B '). Because the action of torque Q · r has the tendency of self rotation at any time, we call this phenomenon static unbalance state.