Design And Application Research Of Layered Unequal Pitch Milling Cutter Based On Burr Control

There are several milling processes involved in the production of automobile engine cylinder head,in which large plane milling is particularly important.This plane is the assembly surface of the engine cylinder head and the cylinder block,and its surface quality and geometric accuracy are important indexes of qualified machining.Burrs occur at the edges of the workpiece during the large facing milling process.In the production line,a deburring process is added in the next process to remove the edge burr,that is,using a brush to remove the edge burr on the workpiece.When the deburring effect of the brush is not ideal or reaches a certain number of times,the brush need to be replaced in time.Therefore,the shape of edge burrs generated by facing milling affects the life of the brush and the time of the deburring process.In addition,the machining vibration during the milling process also affects the workpiece surface quality,spindle life,etc.Research and analysis on machining stability can improve the surface quality of the workpiece and the life of the machine.Based on the above analysis,this paper proposes the application of a layered unequal pitch milling cutter to large-surface milling of a cylinder head.The detailed contents of the research are as follows:First,burrs are divided into entrance burrs and exit burrs according to the location of burrs formed during face milling.Compared to the exit burr,the effect of the entrance burr is negligible.Therefore,a mathematical model of the exit burr is established.According to the mathematical model,the main factor affecting the length of the burr is the cutting depth.Second,The influence of cutting depth on the burr length at the milling outlet is studied by finite element simulation,which determine the cutting depth of the last layer is 0.05 mm.The cutting force is analyzed in frequency domain to determine the tooth spacing.Finally,the spatial distribution of the teeth of the milling cutter is determined,and the milling cutter is designed and manufactured.Third,the cutting force during the milling process is modeled,and the relationship between the cutting force coefficient and the average cutting force is determined using the average milling force model.Through the cutting force coefficient calibration test,the radial and tangential milling force coefficient values are determined in the milling process.Subsequently,a dynamic model of the milling process is established by using the cutting force model and the theory of the effect of cutting thickness regeneration.Forth,based on the semi-discrete method for solving the stability of multi-delay milling,the stability formula of the layered unequal pitch cutter is obtained,and the corresponding Matlab program is written.After obtaining the modal parameters of the tool,the relevant parameters are brought into the solving program,the stability lobe diagram is obtained,and the optimal spindle speed is determined to be 2650r/min.Fifth,based on the stability leaflet map of the layered unequal pitch milling cutter,three cutting parameters are determined for the verification test,and the spindle vibration signal is collected during the test.After the test,the surface roughness,edge burrs,and spindle vibration signals of the workpiece are analyzed to verify the accuracy of the previous analysis and the correct spindle speed.In summary,this paper focuses on the process of large-plane milling of engine cylinder heads,studies the design of layered unequal pitch cutters and the stability of the machining process to ensure the control effect of the cutter on the formation of burrs and the stability of the machining process.