The content of this paper is about the case analysis of the right-angle gear box fault analysis and diagnosis strategy. It is a very practical experience summary. I hope it will be helpful to your work and learning.
The right-angle gear box is an industrial component, which can transmit power through the transmission gear system. At the same time, as a mechanical part of transmission gear, the gear box is also widely used in chemical industry. From the application of gearbox, this paper expounds in detail the common fault manifestation and diagnosis measures of gearbox.
I. Use of Right-angle Gear Box
The main uses of gearbox are as follows: First, it can change the transmission speed through the gear set, which is often called "variable speed right angle gearbox" in industry. Secondly, the right-angle gear box can change the rotational moment, that is to say, under the same power, the higher the speed of the gear, the smaller the moment of the right-angle gear shaft, the larger the reverse; thirdly, the right-angle gear box is used for power distribution, in industry, the staff can use an engine, through the right-angle gear shaft. The main axle of the gearbox pulls several slave axles, and then only one engine will pull several loads. Fourthly, the right-angle gearbox has clutch function, and the brake clutch is the clutch function of the gearbox. People can freely separate the two meshing gears, and then separate the load from the engine. Fifthly, to change the direction of transmission, it is advisable to use two sector-shaped gears to transmit the force in the vertical direction to the other side of the rotating shaft in an orderly manner.
2. Typical Failure Performance of Right-angle Gear Box
Through the analysis of the practical application of right angle gear box, it is not difficult to determine its fault. The whole right-angle gear box system includes bearings, gears, transmission shafts and box structure, etc. As a kind of commonly used mechanical power system, it is very prone to failure of mechanical parts, especially the three parts of bearings, gears and transmission shafts, while continuing to move. The other failure probability is obviously higher than it. They are low.
When a gear performs its task, it lacks the ability to work because of various complex factors. The value of function parameters exceeds the allowable maximum critical value, which results in a typical gear box failure. Its manifestations are also varied, which can be divided into two main categories: the first is that gears are gradually generated in the cumulative rotation, because the external surface of the gearbox bears relatively large loads in the process, the clearance of meshing gears will appear in the relative rolling force and sliding force, and the friction force when sliding. Contrary to the direction of both ends of the pole, over time, long-term mechanical operation will cause gear gluing, cracks, and increase wear and tear, and gear fracture will become inevitable. Another kind of failure is due to the staff not familiar with the safe operation process or violating the operation specifications and requirements, negligence in the installation of gears, or buried hidden dangers for the failure in the initial manufacturing. This kind of failure is often due to the internal hole and the outer circle of the gear are not on the same center, and the gear interacts with each other. There are errors and asymmetric distribution of axes in the timely shape.
In addition, in every part of the right-angle gear box, the shaft is also a part that will easily flash out. When there is a relatively large load impact shaft, the shaft will quickly deform, which directly induces the failure of the gear box. When the fault diagnosis of gearbox is carried out, the effects of shafts with different deformations on the fault of right-angle gearbox are different. Of course, there will be different fault manifestations, so the distortion of shafts can be divided into severe and mild. Shaft unbalance will cause faults, the reasons are as follows: working under heavy load environment, long-term deformation is inevitable; the shaft itself exposes a series of defects in many processes such as production, manufacturing and processing, resulting in serious unbalance of newly cast shafts.
3. Strategies for Fault Diagnosis of Right-angle Gearbox
The right-angle gear box is a unified mechanical body coexisting with gears and bearings. Its various faults caused by processing defects or pressure are worthy of attention. Generally speaking, the following methods are usually adopted:
1. Cepstrum Analysis Method
Cepstrum analysis, also known as quadratic spectrum analysis, is a new technology in modern signal processing science. When multi-group modulation side frequency is difficult to identify in the spectrum of mechanical signal, cepstrum can decompose and identify the fault frequency, analyze and diagnose the causes of the fault.
For the vibration spectrum of right-angle gearbox with several pairs of gears meshing each other, because each pair of gears will appear side-band when meshing, when individual side-band interlacing concentrated distribution, it is far from enough to identify and analyze only by frequency refinement, because cepstrum will transform the harmonic in power spectrum into cepstrum. The position of a single line in the figure implies that the corresponding harmonic frequencies in the power spectrum are separated by time periods.
Another notable advantage of cepstrum is that it is insensitive to the signal transmission path of the sensor or the azimuth of the measuring point, and insensitive to the correlation between the frequency regulation and the magnitude, which in turn helps to monitor the magnitude of the fault signal without measuring the specific magnitude of a measuring point.
2. Side band analysis method
Generally speaking, the sideband is analyzed from two aspects: one is to compare the range of the amplitude of the sideband in each measurement process; the other is to check the specific frequency relationship by means of the symmetry of the frequency of the sideband, which is definitely the same group of sidebands. If so, the frequency of the modulated signal can be obtained along the way. Number and meshing frequency of gearbox.
It should be pointed out that individual faults, such as gear shedding, cracks on the root and individual broken teeth, will have obvious transient modulation. There will also be a series of sidebands in the direction of meshing and on both sides. Their main characteristics are that the order is dense and the spectrum lines are scattered. The shape of side frequencies varies due to the overlapping of higher-order converters. If obvious local faults occur, the components of harmonics and the frequency of their rotation can also be increased.
The side-band components here contain abundant information resources of right-angle gearbox fault. To obtain this information, sufficient frequency resolution is needed in spectrum analysis, which promotes accurate measurement of the distance between side-bands.
3. The Method of Power Spectrum Analysis
Power spectrum is the statistical average concept of stochastic process, and the power spectrum of stationary stochastic process is a deterministic function. This method can determine the frequency composition of vibration signal and the distribution of vibration energy on each frequency of right-angle gearbox. Because the power spectrum and the amplitude value form a square relationship, compared with the amplitude value spectrum, the power spectrum can more highlight the linear spectrum components of harmonics and the meshing frequency, and reduce the vibration signal. No. 1 causes "burr" phenomenon.
In addition to being widely used in chemical industry, right-angle gearbox is also used in other fields. After failures occur, we should not rush to adopt too many means and measures to correct them. We should first analyze the causes of the failures, which link they occur, identify the potential safety hazards, and select the most appropriate strategies and methods to deal with and diagnose them. Only in this way can we get twice the result with half the effort. Hunan Lijia Machinery Manufacturing Co., Ltd. is one step ahead in the field of right-angle gear box in China, especially in H series right-angle gear box.