11:12 AM | апр. 13, 2018
Friction and impact are two factors affecting paddy hulling performance of impeller type paddy husker
. It was hypothesized that reducing the impact as much as possible while increasing the frictional energy will increase the paddy hulling performance. Based on mathematical calculations, the amount of frictional energy almost only depends on the center angle of arch of the blade. Increasing the center angle of arch of the blade will improve the paddy hulling performance. Then, an improved impeller was made and comparative experiments were conducted using the new impeller and the commercial one mounted to both vertical and horizontal axis type husker. The test results showed that under the same hulling ratio, the broken rice ratio of the new impeller is lower than the commercial one by about 6% and 8% in the vertical and horizontal axis type husker, respectively.
The operating parameters for machines of this design are usually determined and set empirically. In this article, some experiments and calculations had been carried out in order to explore the mechanisms involved in husking rice grains using this method. A simple sliding friction rig with load cell and high-speed camera was used to observe the mechanisms that occur during husking. The husking performance of different rubbers was compared for changes in the applied normal load.
It was found that grains rotate between the rubber counterfaces on initial motion before being husked. In addition, harder rubbers were found to husk a higher proportion of entrained grains at lower applied normal load. By measuring the coefficient of friction between rice and rubber samples, the shear force required to husk a given percentage of grains could be calculated and was shown to be constant regardless of rubber type. Based on the mechanism seen in the high-speed video, it was evident that there was a limiting shear stress that was the governing factor over the husked ratio.
In recent years, with the emerging of large-scale rice processing production line, the most of them have realized the automation of production process. which has solved the rice processing line flow control and production process monitoring, improving production efficiency, and greatly reducing the labor intensity of workers. However, the operation of the rice whitener
in the rice processing line is entirely dependent on skilled workers at present. The rice whitening machine, which determines the quality of processing, is the key milling equipment in the rice processing line.