Improvement of the connecting plate structure of t

  • Detail

Improvement of the connecting plate structure of crankshaft dynamic balance test

crankshaft is one of the important parts of engine. The unbalance of crankshaft makes the engine produce periodic vibration when it works, which leads to the reduction of working accuracy and reliability of the engine, fatigue damage of parts and boring noise. In addition, crankshaft imbalance also has a direct adverse effect on bearing life and mechanical efficiency. Therefore, the crankshaft dynamic balance test has become an important inspection process

the crankshaft dynamic balance test is carried out on the dynamic balance testing machine. According to the principle of dynamic balance, the rotating parts with large axial size must be added with an appropriate mass in any two rotating planes to make the rotating parts reach balance. Therefore, first make the crankshaft run on the dynamic balance testing machine, then find out the size and phase of the mass diameter product required to be balanced in two selected planes, and then carry out counterweight or weight removal, so as to make the crankshaft achieve dynamic balance

Figure 1 is the structural diagram of the original dynamic balancing device. The power box 1 drives the crankshaft 5 through the universal coupling 2 and the adapter 3 (the crankshaft is supported by two groups of rollers 6), so as to measure the magnitude and phase of the imbalance. The connection between the connecting plate and the crankshaft adopts the way of jacking screw tightening. In the long-term production practice, we found the following problems:

· jacking with jackscrews is easy to scratch and damage the machined surface of the crankshaft

· when the crankshaft starts running and braking, it sometimes rotates relative to the connecting disc, so it is not easy to find the phase of the imbalance, resulting in the inability of counterweight

· the jackscrew tightening method is adopted, and the working section threads of the jackscrew and the adapter are easy to be damaged

1. Power box 2 Universal coupling 3 Connecting plate 4 Jackscrew 5 Crankshaft 6 Roller

Figure 1 structural diagram of the original dynamic balancing device

based on the above shortcomings, but the author has improved the structure of the docking plate in the detection of loading soft copper or annealed copper rod

Figure 2 shows the improved disc connecting device. Mill two straight grooves in the direction of mutual symmetry of the connecting plate 1, and place the semicircular key 2 and counterweight 3 with equal mass in these two grooves respectively to ensure the balance of the whole connecting plate during operation. The woodruff key 2 and the counterweight 3 are fixed on the adapter 1 with two extension springs 4. When in use, guide the woodruff key 2 into the keyway at the small end of the crankshaft to drive the crankshaft to run for dynamic balance test

1. Connect plate 2 Woodruff key 3 Counterweight 4 Tension spring

Figure 2. The improved disc receiving device

uses this improved structure and has the following advantages

· there is no need to use a wrench, and the operation is convenient to ensure the quality of raw materials

· when the crankshaft starts running and braking, the relative position of the connecting plate and the crankshaft will not change, so it will be easy to find out the phase of the imbalance

· adopt the half round key transmission mode, which will not cause damage to the crankshaft and can be used for a long time

when using the above connection structure, pay attention to the following questions

· the fit gap between the working surface of the woodruff key and the keyway should not be too large (about 0.05mm, only replace the sensor), otherwise it will affect the use of the adapter. We should carefully understand the service life of the following standards

· the improved adapter is suitable for crankshafts with closed keyway, especially for crankshafts with semicircular keyway. However, if the keyway at the small end of the crankshaft is unblocked, it should be used with caution. (end)

Copyright © 2011 JIN SHI