谷物压入硬度测定方法的研究与优化

Research and the optimization of grain indentation hardness measurement method

为研究一种稳定性与可靠性较高的谷物硬度测定方法,利用压痕深度法和基于压痕曲线法对谷物籽粒进行硬度试验研究,并用正交试验和综合评分法对基于压痕曲线法的因素水平进行优化研究。结果表明:不同因素水平下基于压痕曲线法的重复性高、可靠性整体要优于压痕深度法;基于压痕曲线法的最优参数组合是:加载速度为3 mm/min,压入深度为0.5 mm,压头类型为45°四棱锥,表面粗糙度为400目;利用优化参数测得豌豆硬度较大为82.7 MPa,蚕豆、红豆、黑米、糯米、玉米接近在70~73 MPa之间,绿豆居中为40.8 MPa,小麦和大豆最小在22 MPa左右。基于压痕曲线法在最优参数组合下能够实现谷物硬度测定的统一性和可比性,并且为谷物硬度计的研制提供依据。

In order to develop a method for the determination of grain hardness with high stability and reliability,the hardness test of grain was studied by indentation depth method and indentation curve method,and the factors based on indentation curve method were optimized by orthogonal test and comprehensive scoring method.The results showed that the method based on indentation curve has higher repeatability and reliability than the method based on indentation depth.The optimal parameter combination based on indentation curve method were:loading speed of 3 mm/min,press depth of 0.5 mm,the types of pressure head of 45°rectangular pyramid,the surface roughness of 400 mesh.Using optimized parameters to determination the grain hardness,the hardness of pea was 82.7 MPa,that of broad bean,red bean,black rice,sticky rice and maize was close to 70~73 MPa,mung bean was 40.8 MPa,and wheat and soybean was about 22 MPa.The indentation curve method can achieve the uniformity and comparability of grain hardness measurement under the optimal parameter combination,and provide the basis for the development of grain hardness tester.