Research On Bionic Design Of Functional Surface Of Multilevel Grinding Head For Pulverizer And Its Highly Efficient Crushing Mechanism

To meet the demand for the production of micron and nano-level functional raw materials,ultrafine grinding technology emerged as the times require,and has now been indispensable for deep processing in many fields such as medicine,chemistry,food,and electronics.The grinding head is a typical functional part of an ultrafine pulverizer,and its surface structure is a key factor that affects the crushing performance.Traditionally,the structural design of the grinding head mostly relies on engineering experience,and the collaborative mechanism for designing the high-efficiency grinding pair is not clear.Thus,it is gradually unable to adapt to the production of high-quality powder,manifested by insufficient grinding with low reduction ratio;high working temperature rise with material thermal deterioration,increased wear of the grinding head,etc.,consuming a lot of energy and materials.The core idea of this paper is “learning from nature”.Focusing on the improvement of the service performance of the key component in a pulverizer,a new method of structural bionics is proposed based on the natural friction pairs of animal teeth,aiming to improve the performance of the grinding head of the pulverizer for more crushing and less friction.That is to increase the grinding fineness and decrease the temperature rise of materials from the source.This paper addresses the following issues:(1)Bionic prototype selection and its reverse reconstruction.Firstly,the bovine dentition was selected as the bio-specimen for bionics research based on the comparative analysis of typical animal teeth adapted to different feeding habits.Secondly,the point cloud data of the bovine dentition was acquired using the 3D blue light scanning system,then the 3D solid model of bovine dentition was reconstructed assisted with Geomagic Studio,a reverse engineering software,after data reduction,noise reduction,and other preprocessing,as well as package processing,polygon editing,and NURBS surface construction,sequentially for the point cloud.It provides a digital foundation for the geometric extraction of the bionic coupling structure.(2)Research on the adaptive masticatory mechanism of bovine dentition.Based on the comparative analysis of the morphology of different teeth in the bovine dentition,the biomechanical principles of chewing movement were analyzed,and the adaptive and efficient masticatory mechanism under the synergistic effect of multiple bovine teeth was further revealed.It offers a new option for designing the multilevel working surface of the grinding head for a pulverizer.(3)Cooperative design and optimization of the surface structure of the bionic multilevel grinding head.Facing the demand for fine grinding,a design method integrated with cutting and grinding for a bionic multilevel grinding head was established by coupling morphological characteristics of incisors and molars in a unified dentition coordinate system,given their cooperative and efficient functional mechanism.To further improve the effectiveness of the bionic design,the simulation plan for material crushing was designed based on the sampling principle of response surface methodology,then it was conducted by introducing the discrete element method,to establish a surrogate model between the resulting breakage rate,the resulting heat generation,and the bionic structure parameters.Further,the multi-objective oriented coupling optimization of bionic structure parameters was solved with the NSGA-II algorithm.(4)Analysis of the efficient crushing mechanism of the bionic grinding head.Taking the grinding fineness and temperature rise of materials as evaluation indicators,a crushing performance test platform was built to verify the effectiveness of the biomimetic approach.The test results show that the crushing ability of the bionic multilevel grinding head is significantly enhanced compared with the similar traditional type.With mung bean as raw materials,the average particle size of the product is reduced by 32.56%,and the yield of micron powder with a size of 1 ～ 100 microns is increased by about 1.2 times.Besides,the temperature rise of crushed materials is slightly reduced.Through simulation analysis and experimental investigation,the effects of different factors on the material crushing behavior were further explored respectively,including the tooth form,structural parameters,and flow field characteristics in the grinding chamber of the grinding head.Consequently,the efficient crushing mechanism of the bionic grinding head was revealed,supporting the optimization of bionic structures.