The Research On The Vibration Characteristics Of 9Z-4C Chaff Cutters

Chaff cutters is one of the most important equipment in industry,which has the advantages on simple structure and small size,meanwhile,it is easy to transport and operate,so,the chaff cutters is suitable for raising cattle,sheep and other livestock based on the above advantages.But the majority of thechaff cutters has serious problem with vibration in our country,some parts can be wear and tear easily and shorten the initial life,in addition,it can even endanger the health of operators.However,at present,the identification of the vibration source of the chaff cutters is not clear,and the study on the factors affecting the vibration is not perfect,also,the vibration characteristics of the main parts of the chaff cutters are not analyzed.In view of these problems,vibration signal can be collected in this paper,the vibration signal per-processing,the factors of the vibration,the time domain and frequency domain and the vibration characteristics of the parts can be researched in this paper.The main research work is as follows:(1)A test-bed with adjustable rotation speed was designed to study the transmission part and cutting part on the chopper.The test-bed was build based on the type of 3263A2acceleration sensor,MI7106 signal acquisition instrument and the MI7106 analysis system.Based on the different the rotational speed on spindle and feeding shaft,6 different spindle speedand 10 different feeding speed were selected,we choose 20 test conditions under empty and load conditions.On this basis,taking the chopper as the testing object,we select feeding device,feeding extrusion device,variable speed device,cut device and toss deviceas five points,the vibrating signals can be collected by using vibration test systemunder the 20 different working conditions,and then,5 points of the signal in the X,Y,Z directions can be obtained.(2)In order to pre-tax the vibration signal of chopper,an improved particle swarm optimization wavelet threshold algorithm was proposed.In this method,wavelet threshold algorithm is adopted to denoising the vibration signal,differentiated function with parameters can be used to calculatedthe threshold function,level-dependent threshold and the optimal parameters of threshold function can be obtained by the particle swarm optimization algorithm with SURE fitness function.In order to verify the effectiveness of the algorithum in this paper,three commonly used algorithms and the algorithm in this paper were adopted,we do the denoising test on the different signal-to-noise ratio in baseline signals(Block,Bumps,Doppler and Heavy sine).The experimental results show that the performance of the proposed algorithm is comparable to the traditional particle swarm optimization algorithm,and bothalgorithm are better than the standard soft threshold denoising algorithm and the continuous differentiated threshold function denoising algorithm.For the chopper vibration signal,using the self-power spectrum to evaluate the denoising effect.The test results showed that the algorithm not only retained the good robustness of the traditional particle swarm optimization wavelet algorithm,but also realized the noise reduction of the chopper vibrating signal.(3)Based on the different working condition,the time domain of the vibrating acceleration on each measuring point are analyzed in X,Y,Z direction.For all the conditions,the result show that direction of Z feeding device,feeding extrusion device and variable speed device have the maximum vibration,meanwhile,cut device and toss device in X direction vibration is the largest.(4)The time domain of the vibration acceleration with 5 measuring point in each direction under different working condition can be analyzed,During the no-load condition,the vibration in X direction can be influenced due to the toss device,both the vibration in Y direction and Z direction can be influenced due to the variable speed device.During the Load condition,the vibration in X,Y,Z can be influenced due to the toss device.(5)The vibration of chopper under the no-load condition and load condition can be influenced by the factors of material,spindle speed and the feed roller speed,based on this paper research,the result show as follows,the vibration of chopper under the load condition is much higher than the no-load condition in most cases,meanwhile,The influence on cut device and toss device with material is much higher than the extrusion device and variable speed device.There is no regular rules to analyze the vibration of chopper when the speed of the spindle and feed roller has been increased.Along with the speed of the feed roller being increased,the vibration of the chopper has been increased when the spindle speed does not change.Along with the speed of the spindle being increased,the vibration of the chopper has been decreased when the feed roller speed does not change.(6)Based on the HHT algorithm and denoising algorithm on the third chapter in this paper,the frequency of the vibration signal characteristics can be obtained.The resulted can be combined with the results in the fourth chapter,frequency domain can be analyzed based on the typical 12 groups of chopper’s signal that we selected.The source of vibration with each parts can be obtained based on the characteristic frequency and excitation frequency with theoretical calculation,the results are as follows:1)The feeding extrusion device is main vibration source when the feeding device has no-load,variable speed device and chopper are main vibration source when the feeding device has load.The variable speed device is main vibration source when the extrusion device has no-load,feeding device is main vibration source when the extrusion device has load.The cut device is main vibration source when variable speed device has no-load;extrusion device and feeding device are main vibration source when variable speed device has load.The extrusion device,feeding device and the variable speed device are main vibration sources when cut device has no-load;variable speed device is main vibration source when cut device has load.The feeding extrusion device is main vibration source when toss device has no-load;variable speed device and cut device are main vibration sources when toss device has load.2)The feeding extrusion device is main vibration source when chopper has no load on X direction,variable speed device and cut device are main vibration sources when chopper has load on X direction.The variable speed device and feeding device are main vibration sources when chopper has no load on Y direction,the feeding extrusion device is main vibration sources when chopper has load on Y direction.The cut device is main vibration source when chopper has load on Z direction,the feed device is main vibration source when chopper has no load on Z direction.(7)The feeding device and toss device on chaff cutters were analyzed using the finite element calculation of the free modal.Also,the cut device was analyzed using the finite element calculation of constraint modal,nonzero before six of the natural frequency and the corresponding vibration mode can be obtained,also,each of the corresponding vibration model characteristic was analyzed.The result as follows,the maximum deformation of feeding device is concentrated on the middle of the feeding inlet on both sides of the plate and the middle of bottom of the feeding groove.The maximum deformation about 28.73 mm.The maximum deformation toss device is concentrated on the discharging mouth edge,the maximum deformation about 3.123mm.The maximum deformation toss device is concentrated on the edge of the each knife dish,the maximum deformation about 20.30mm.