Experimental study on vibration suppression of gear shaft misalignment with ISFD

Misalignment faults in gear systems lead to violent vibration and noise, shortening the life of equipment. The aim of this work is the demonstration of vibration suppression of parallel-misaligned gear shafts using an integral squeeze film damper(ISFD). Using a first grade spur gear in engineering for reference, an open first-grade spur gear system is built and the vibration characteristics of the gear system with rigid supports and ISFD elastic damping supports are studied under different degrees of misalignment. The experimental results show that ISFD supports have excellent damping and vibration attenuation characteristics, which have improved control of the gear system vibration in horizontal, vertical and axial directions under different degrees of misalignment. This work shows that an ISFD structure can effectively suppress vibration of characteristic frequency components and resonance modulation frequency components. The test results provide evidence for the application of ISFD in vibration control of gear shaft misalignment faults in engineering.

Study on Coaxiality Measurement System of Compound Gear Shaft Based on Non⁃contact Optic

Aiming at the shortcomings of traditional contact measurement methods such as low measurement efficiency,high cost and low accuracy,a non-contact optical measurement method based on the laser displacement sensor is proposed.According to the relevant regulations of the coaxiality error evaluation standard and the structural characteristics of the compound gear shaft,we have designed and built a set of supporting software system as well as a hardware test platform.In this paper,the distance difference threshold and scale threshold methods are used to eliminate outlier data.The least squares circle is selected to calculate the center of the circle and the minimum containment cylinder axis method is used as the reference axis of the composite gear shaft.Compensated by the standard step shaft calibration,the coaxiality error of the composite gear shaft can be measured to be within 0.01 mm in less than two minutes.The range value of the multi-section measurement test is 0.065 mm.The average coaxiality error is∅0.476 mm.

Fretting instability characteristics for gear shaft shoulder

In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by adopting the method of combining kinematics and tribology, and the numerical analysis was applied to the fretting instability mechanism of gear shaft shoulder by introducing the friction instability damping ratio. The numerical results show that the main factors causing the unstable and vibrating gear shaft shoulder are the large tightening torque and too large static friction coefficient. The reasonable values of the static friction coefficient, the amount of interference and tightening torque can effectively mitigate the fretting instability phenomenon of gear shaft shoulder. The experimental results verify that damping plays a significant role in eliminating the vibration of gear shaft control system.

CALCULATIONS OF THE INNER DISTURBANCE FREQUENCIES INSIDE THE EPICYCLIC GEARING

The forms of the vibration disturbances inside the epicyclic gear train are analyzed. Thefrequency equations for the inner disturbances of the epicyclic gearing with one or two degrees offreedom have been built. The latter of them is a 3-dimension problem and the range of the disturbance frequencies covers a series of planes inside the 3-dimension coordinates. As a result, thechances to lead to the system resonance are developed. The calculating results indicate that in thedesign process of the shaft system, the chances of resonance can be reduced by tunning the dynamicparameters and the structure of the system.

Developments of crawler steering gearbox for combine harvester straight forward and steering in situ

Soil compaction and accumulation are caused by crawler steering.Soil characteristics would affect the ability of crawler straight forward and steering in situ.This paper studied the principle of straight forward steering and steering in situ mode of traditional unilateral brake steering gearbox of a crawler combine harvester.Then a positive and negative steering gearbox model was developed and processed.The performance of positive and negative steering gearbox was analyzed by performing two steering modes on soil compaction effect.Results showed that the positive and negative steering gearboxes can achieve three operating modes,such as straight forward,unilateral brake steering,and positive and negative steering in situ.The positive and negative steering in situ was smooth and without soil accumulation phenomenon.When the crawlers center distance,crawler grounding length,crawler width were 1150 mm,1620 mm and 450 mm respectively,the rolling area and the scratch free area of positive and negative steering gearbox were 5.37 m2 and 0.36 m2 respectively.However,the rolling area and the scratch free area produced by unilateral brake steering gearbox were 13.92 m2 and 1.88 m2 respectively,which was 8.55 m2 larger than that of positive and negative steering gearbox.The crawler with positive and negative steering gearbox has minor damage to paddy soil.This research can provide a theoretical basis for the smooth steering in situ and structural optimization of the crawler steering gearbox.