Research On Process Optimization Of Conical Pick Based On Critical To Quality

The conical pick is the teeth of road-header and shearer,whose quality determines the efficiency of road-header and shearer.Because of the contact with coal and rock during the working process,the conical picks are subjected to large impact load,alternating stress,corrosion stress.Therefore,how to improve the reliability and service life of conical pick is one of research hotspots.In this paper,the conical pick is object of research,which improves the service life of conical pick and optimizes the manufacturing process based on critical to quality of conical pick.Main research contents and conclusions are as follows:1)The extraction model of critical to quality of conical pick: firstly,the Fuzzy Analytic Hierarchy Process(FAHP)is used to analyze the market demand and obtain the weight of customer demand,and the weight of expert is obtained by Fuzzy Clustering(FC),which is used to obtain the comprehensive weight of customer demand.Secondly,the correlation between customer demand and manufacturing quality characteristics is established based on the Quality Function Deployment(QFD),which is used to map the weight of manufacturing quality characteristics.Finally,the critical to quality of conical pick are obtained by the 80/20 rule,which include impact toughness(Pick body),hardness(Pick head?Pick body),shear strength(Seam welding),diameter of pick head(00.3f25-),and diameter of pick body(+0.10f25).2)The extraction model of critical to process of conical pick: the critical to process of conical pick was analyzed by the Fish-Bone Diagram and Causal Matrix Model,which is tempering,braze welding – quenching.3)The process assessment of conical pick based on the Process Failure Mode and Effects Analysis(PFMEA): through the process assessment of conical pick,the potential failure modes in process(includes step)were obtained by the criterion of potential failure modes.The potential failure modes were evaluated by Risk Priority Number(RPN).Under the 95% confidence level,the corresponding improvement measures was given for the potential failure modes that RPN is more than 50.4)The multi-objective optimization model of conical pick cryogenic process: the effectiveness of conical pick cryogenic process is verified based on orthogonal experiment of cryogenic process,which could increase the service life of conical pick.Further,based on the analysis of orthogonal experiment,the objective function of conical pick was constructed by QFD model.Finally,under the constraints of cryogenic process parameters and process cost,the multi-objective optimization model of cryogenic process was build,and optimal group of process parameter was cryogenic temperature: 77 k,cryogenic time: 24 h,number of alternation: 2.The experiment is carried out on the theoretical optimal process group.The experimental results show that the theoretical optimal group has better mechanical properties than the orthogonal experimental group.Compared with group 1(normal heat treatment group),the tip hardness,tip wear,body hardness,body wear and impact toughness of conical pick of the optimal process group respectively increased by 1.35 times,1.49 times,1.02 times,1.18 times and 1.23 times.