Research On Fragmentation Mechanism Of Machined Aggregate And Rapid And Continuous Detection Technology Of Particle Shape

Mechanical aggregate is made of crushing machinery and equipment through different processing technology,and it is the main component of road structure.The main factors affecting the quality of pavement engineering are the shape and gradation of aggregate particles.When the content of needle-like particles in aggregate is high,the compressive strength,rutting resistance and water stability of pavement will be seriously reduced.During the rolling operation,excessive needle-like particles content will lead to significant cracking and depression of the mixture,resulting in collapse and depression of the asphalt pavement.Needle flake is produced by the production of processing equipment.Traditional needle flake particles are detected manually.This method is inefficient and the detection results are easily affected by the subjective operation of the experimenters.The application of digital image processing technology can quickly collect and analyze the shape of aggregate particles,which can greatly improve the production efficiency.Therefore,this paper is based on the theory of mechanical fragmentation and digital image processing.The technology has carried out in-depth research on fast and continuous detection of broken aggregate shape,and completed the following work:(1)Based on the analysis of aggregate and its mechanical properties,mechanism and processing technology,the structure and working principle of common crushing machinery used in pavement engineering are studied and analyzed,and the selection theory of processing technology and equipment and key parameters are analyzed.Through the study of digital image processing technology,the principle curve of camera selection based on moving state is put forward.The model selection and parameter solution of the industrial camera,the influence factors of the external reverse light source on the object imaging and the solution of the function fitting formula are completed.Complete the design and manufacture of image acquisition equipment for indoor simulation of aggregate falling,and establish an image acquisition system based on binocular camera.(2)Based on the binocular camera acquisition system,the algorithm technology of continuous and fast acquisition and digital image processing of the falling mechanism aggregate image is proposed.The calculation of two-dimensional image size of aggregate particles and the reconstruction of three-dimensional size of aggregateparticles are completed.On the basis of manual measurement of aggregate size,the error analysis of the size calculation results of aggregate particle image is carried out,and the error of the image processing algorithm in this paper is obtained.(3)An image method for calculating the content of needle-flake particles is proposed.The accumulative content of needle-flake particles is selected as an evaluation index to evaluate the quality of aggregates continuously and rapidly.By calculating accumulative needle-flake particle content and error analysis,the error calculation of image calculation results and manual measurement is completed,and its accuracy is verified.(4)The construction of a rapid and continuous evaluation system for particle shape is completed,and the research on shape acquisition and processing technology of digital image of aggregate particles based on three-dimensional size is completed,and the continuous and rapid evaluation method and detection system of aggregate particle shape are established.Quantitative evaluation is carried out from the evaluation indexes of accuracy,accuracy and timeliness of the system,and the calculation of each evaluation index is put forward.Formula to complete the performance analysis of the system.Finally,based on the project of Yunnan Provincial Department of Communications,500 mechanical aggregates were selected as test samples,and the binocular camera aggregate particle rapid continuous detection system was applied to carry out the test.The needle-like particle content of aggregate sample is obtained,and provides a reference for the selection of mechanical aggregate engineering processing technology and crushing machinery.