Search

In order to study the influence of the side drive on the balance state of the threshing drum, this paper used the side eccentric load chain drive as the power on the threshing drum dynamic balance test bench. By analyzing the influence of different radial phases, different axial distances, and spiral combinations of the threshing drum on the counterweight, this paper studies the law of the effect of side partial load chain drive on the dynamic balance of the threshing drum and finds that the side chain drive has obvious influence on the unbalance phase of the threshing drum and the change of the axial distance of unbalance has little effect on the equilibrium state of the threshing drum. And from this, a vibration balance method based on the equivalent unbalance of the chain drive is proposed, which can predict and calculate the unbalance of the threshing drum. The unbalance of the threshing drum predicted by this method is smaller than the actual measured unbalance. The maximum error is 32.64% and the minimum error is 4.6%. In the two tests, the predicted unbalance is 1.24 mm/s in amplitude and 270 degrees in phase and amplitude 1.4 mm/s and phase 120 degrees, respectively. The measured unbalance is amplitude 1.587 mm/s and phases 286 degrees. The error between prediction and actual measurement is less than 32.64%, and the unbalance amplitudes that can be reduced by one-time dynamic balance are 0.856 mm/s and 0.674 mm/s, respectively. The research results in this paper provide an effective method for the balance state of the multidrum side chain transmission.

The main working parts of the cleaning device of a rice combine harvester can be controlled by an established control strategy in real time based on the monitored grain sieve loss. This is an efficient way to improve their cleaning adaptability, since as a consequence, the main working parameters of combine harvesters can automatically adapt to crop and environment changes, and the corresponding cleaning performance can be improved. To achieve the target of cleaning control based on the monitored grain sieve loss, a fuzzy control system was developed, which selected S7-1200 PLC as the main control unit to build the lower computer hardware system, utilized ladder language to complete the system compilation, and used LabVIEW 14.0 software to design the host&ndash, computer interface. The effects of fan speed, guide plate angle, and sieve opening on the grain sieve loss and grain impurity ratio have been investigated through a large number of bench tests. The relevance level of the operating parameters on the performance parameters has been determined also, and finally, a fuzzy control model was developed for the cleaning system. The experiment results indicated that the designed fuzzy control model can control the cleaning section settings, such as fan speed and guide plate angle automatically, and reduce the grain sieve loss to some extent.

In order to solve the problems of deformation caused by traditional threshing rack applied to the variable-diameter cylinder, two high-strength threshing racks (truss-type threshing rack, reinforced plate-type threshing rack) were designed. Through statics quantitative analysis on the basis of theoretical analysis and finite element analysis and calculation conducted on the rigidity and strength characteristics of traditional threshing racks, truss threshing racks and reinforced plate threshing racks, it shows that the reinforced plate threshing rack with higher strength, simpler structure and lighter weight is more suitable for the operation requirements of variable diameter cylinders.

This paper deals with the numerical calculation method of deflection deformation of rice stalks. Due to large deflection of rice stalks caused by reel operation, it is improper to adopt the conventional formula that is usually used in small deflection calculation to fit rice stalk deformation curves. Therefore, a large deflection calculation formula in combination with Simpson&rsquo, s formula was utilized to compute flexural rigidity (EI) and to fit curves. The experiments were conducted under different loads (0.03, 0.04, 0.05, 0.06, and 0.07 N) on a self-established deflection testing rig to verify this method. As a result, the measured results corresponded considerably to ones predicted by this method, furthermore, the flexural rigidity was maintained at a stable level under different loads. This study can provide the basis for establishing a complete deformation model of rice plant and can also be applied in deflection calculation of other stalk crops.

A triaxial ellipsoidal particle model was established according to the physical properties of rice seed, and its impact behaviour against a grain loss sensor was simulated using the discrete element method (DEM). The contact criterion was developed directly by solving the intersection equations, and the contact forces were calculated according to elastic–plastic and Mindlin models. It was shown that the seeds may perform translational and rotational motion in a 3D space after the impact. With the influences of particle shape, orientation and angle of incidence, three typical impact processes were found: single impact, multiple impacts in a short-time, and continuous impacts. Two important parameters for the design of loss sensors are the maximum normal impact force Fn max and the force rise-time tr. Simulations showed that an increase in particle ellipticity strongly enlarged the differences in Fn max. As the ellipticities increased from unity to 2, the defined force ratio η decreased from 100% to about 40%, and this value decreased to less than 20% when ellipticities continuously increased from 2 to 4. Tangential velocity led to an asymmetric variation of η. tr was generally distributed between 12 and 54 μs. In laboratory tests, rice seeds were allowed to free fall onto a loss sensor from a height of 320 mm. Results indicated that the peak output voltage was fluctuated in 1.5–4.5 V, and the rise-time was in 14–48 μs.

Impact damage is the main form of rice threshing and it is also a significant cause of rice injury. Based on contact mechanics, models of the compressed displacement and the largest pressure distribution were established for the case when the threshing tooth obliquely impacts against the rice kernel. A critical velocity formula for impact damage was developed. A computer-aided design model of a rice kernel comprising of three layered ellipsoids was established. HyperMesh software was used to partition mesh elements and to set material and contact parameters for each element, constructing a finite element model for the analysis. Using LS-DYNA software, the impact between the threshing tooth and the rice kernel was simulated and analysed. The simulation showed that the rice husk was subjected to tensile stresses. Tensile stress was a maximum at the front of the contact zone and shifted continuously. The entire kernel rolled during impact. The critical damage velocity for the kernel, corresponding to the critical von Mises stress was 29.5 m s−1, which was in agreement with experimental results.

The giant magneto-impedance (GMI) effect was observed in almost zero-magnetostrictive Co 66.3 Fe 3.7 Si 12 B 18 amorphous ribbon toroidal cores after annealed by a 25 A/mm 2 pulse current density under a transverse magnetic field of 2 kA/m for 30 s. A maximum GMI ratio of 34% and a sensitivity of about 65%/Oe were measured employing a 900 kHz sharp pulse current generated by a CMOS inverter multivibrator. A sensitive non-contact type current sensor composed of an amorphous ribbon toroidal core connected with a pulse current generator, a peak detector, and a differential amplifier is presented. The sensor is able to examine the value and direction of dc current. The measurement accuracy of 0.45% and sensitivity of 0.67 V/A were obtained with full scale ±2.5 A using a power source voltage of 5 V.

"Central Government Allocates a Special Fund of 2.4 Billion RMB to Provide Focused Support for the Project: The State Education Commission and the Ministry of Finance Convene a National Conference to Plan the Implementation of the Program"

Flexural mechanical properties of four kinds of corn stalks were studied on the WDW-300 type micro-control electronic universal material test machine. The load- deformation curves of corn stalks and the maximum load, elastic modulus, flexural strength and deformation value were obtained in the way of 3-point bending. The influence of varieties, cross-sectional area, growth areas and moisture content on the mechanical properties of corn stalks was analyzed. The result that the bending process can be made of linear elastic process, non-linear elastic process and bending fracture process was got. The average anti-flexural strength and elastic modulus of corn stalks are 7.85MPa and 0.15GPa. Differences of Linear elastic range and deformation value of stalks bending exist in the varieties. Under other condition of the same, a positive correlation linear relationship was founded between the maximum load and cross-sectional area of corn stalks. With the increasing of growth areas, the maximum load was decreased gradually. Test result has important guiding significance to the design of high efficiency and low energy consumption corn harvester.

Bionic desorption & damp-tiny material screening technology has been widely used in the industrial and agricultural production, which has not been yet used in cleaning part of Combine Harvester. Current situation in research and application of bionic desorption & damp-tiny material screening technology was introduced in this paper. Similarities and differences between these studies and the urgent problem of rape excursion materials' adhesion with cleaning screen which block hole and lead to an increasing cleaning loss were analyzed and potential application in rape cleaning of the bionic desorption & damp-tiny material screening technology was prospected. Primary design principles of bionic nonsmooth surface cleaning screen were indicated in this paper. Implication feasibility of bionic desorption technology in rape cleaning was preliminarily proved by the comparison test in field between trail produced bionic nonsmooth surface screen and common screen. Suggestions of further implication research of bionic desorption & damp-tiny material screening technology in rape cleaning were given.

On the basis of analyzing disadvantages of conventional prediction model of air-and-screen cleaning device, a new regression model based on support vector machine was proposed to predict and control of cleaning process precisely. Parameters of e-SVR models were determined utilizing non-heuristic Grid Search, heuristic GA and PSO which could avoid the choice of randomness. The effect of samples in different on prediction performance of e- SVR was analyzed compared with BP. The results indicate that the prediction property of e-SVR is better than BP especially in small-sample.

The input gears from the first stage of a combine harvester gearbox have been subjected to experimental testing. A three-dimensional finite element model was established by using Solid Works and the effect of an external load distribution along the gear tooth width was added according to actual working situations. In the Solid Works/Simulation module, the contact relation was established based on the real assembly relations, and to calculate Von Mises stress, on the teeth. Through modal analysis, the gears teeth frequency was analyzed contrastively with the inherent model of the transmission and analyzed the influence of them. The experiment was carried out in the self-made gearbox fatigue test bed. The results indicate that serious pitting appeared on the surface of the teeth when the working time was over 500 hours and the input gears were not measurably distorted, which basically coincides with the analyzed results of the theory.

Damage is easy to occur during the process of harvesting, classification, packaging, transporting, processing, preservation and selling etc. and the detection of internal damage is a difficult problem. Rice kernels were classified as those with none, single, double or multiple stress cracks. An image processing algorithm was used to enhance the object and reduce noise in the acquired image. At the same time a machine -vision system was developed to detect different types of stress cracks in rice kernels. None and single stress cracks were the easiest to detect. Careful positioning of the kernel over the lighting aperture was necessary for accurate detection of double and multiple stress cracks. This system provided an average accuracy of approximately 96.5% to none crack, 93.4% to single crack, 84.2%to double cracks and 83.4% to multiple cracks compared to human inspection. The processing time was between 0.45 and 0.12 s/kernel.