Aiming at the problem of uneven wear of rubber rollers in rice hullers, this work systematically revealed the influence mechanism of abnormal paddy flow states on the contact mechanical properties of rubber rollers based on a nonlinear finite element model of the interaction between paddy grains and rubber rollers. The results show that the wear risk of rubber rollers is minimized when the paddy orientation angle ranges from 0° to 15°. At 30°, the contact pressure reaches 12.63 MPa with a sharp increase. At 45°, shear-dominated loading results in a peak von Mises stress of 2.70 MPa, with unsatisfactory rubber roller wear and hulling rate. Paddy orientation angles from 60° to 90° lead to slight rubber roller wear. With a sparse paddy distribution, 3 paddy grains induce shear fatigue in the middle of the rubber roller, whereas 5 grains result in a contact pressure of 7.09 MPa, which can cause local rubber layer detachment. Although 6 paddy grains exhibit the lowest wear risk among sparse distribution conditions, their dynamic stability is poor. Conversely, a dense distribution of 12 paddy grains results in a contact pressure of 6.92 MPa with a time difference of 0.2 ms, featuring a more uniform stress distribution and superior dynamic synchrony. Paddy stacking causes high contact pressure and von Mises stress (up to 13.85 MPa and 5.44 MPa, respectively), which is the primary cause of crack initiation and local spalling on rubber rollers. The mechanical performance of stacked paddy flow is far inferior to that of sparsely and densely distributed paddy flows, which will inevitably cause uneven wear of the rubber rollers. This study provides theoretical support for reducing uneven wear of rubber rollers and improving paddy processing efficiency.

To explore the effects of low temperature and washing on the superfine grinding performance of wheat bran, two types of wheat bran samples were prepared: unwashed wheat bran (UWB) and washed wheat bran (WWB). The vibration grinding experiments of UWB and WWB were carried out at different grinding temperatures by using the low-temperature vibration grinding experimental platform. The results showed that the powder quality of UWB was greatly affected by low temperature, and the effect of low temperature on the WWB was less obvious. The results also showed that the particle size distribution curve of the UWB micro powder changed from a double peak curve to a single peak curve as the grinding temperature decreased. The similarity of the particle size distribution curves of the two types of wheat bran micro powder decreased with the decrease in grinding temperature, and the maximum decrease was about 60%. Compared with the results obtained at ambient temperature, the maximum difference rates of the mass fractions of the two types of wheat bran superfine powder within the grinding temperature range were 29.91% and 50.16%, respectively. At the same grinding temperature, the difference in mass fraction between the two types of wheat bran superfine powder was about 50%. The sensitivity of the yield of UWB superfine powder to grinding temperature was greater than that of WWB. The difficulty of superfine grinding of WWB was greater than that of UWB. According to the laminate theory of composite materials, the essence of the changes in the particle size of UWB superfine powder was revealed, and the relationship between the mass fraction of residual endosperm superfine powder and the grinding temperature was obtained. The results can be applied to improve the yield and quality of the further processing of wheat bran.