Research On Two-Dimensional Cavity Plunge Milling Technology

Mould is an important process equipment in manufacturing industry.The mass production of industrial products and the research and development of new products are inseparable from mould.Two-dimensional cavity is a common processing content in the production of the mould itself.Plunge milling has the characteristics of high material removal rate and small radial cutting force,which is very suitable for two-dimensional cavity processing of mould.However,when the plunge milling is directly applied to contour machining of two-dimensional cavity,there are usually some problems such as plunge milling collision and rub cut of tool retract,which make the sudden change of load and vibration in the process of plunge milling,affect the life of the tool and even cause the damage of the tool.At present,the tool and technology of two-dimensional cavity plunge milling are drawn from the traditional layer milling,and the characteristics of plunge milling are not fully considered,which hinders the wide application of plunge milling in the field of NC machining.Therefore,it is of great theoretical and practical significance to study the plunge milling tools and process technology of two-dimensional cavity plunge milling.Specific research contents are as follows:Aiming at the plunge milling collision in contour plunge Milling of Two-Dimensional Cavity.By means of cutting simulation,It is found that using the tool with edge angle less than 90 degrees the contact length between the edge and the workpiece increases abruptly when machines to the bottom in contour milling of two-dimensional cavity.The sudden increase of the contact length leads to the sudden change of the load,which is the main reason for the occurrence of the collision of plunge milling;While the contact length with the edge angle greater than 90 degrees is basically constant during the whole processing,that is to say,the tool with the edge angle greater than 90 degrees can avoid the collision of plunge milling.A series of single-tooth tool with edge angle from 87 to 99 degrees are customized.It is verified that the tool with edge angle greater than 90 degrees can effectively reduce the sudden change of load and reduce the radial cutting force,realizing cavity contour plunge milling of twodimensional and the original path withdrawal.The technological characteristics of forward plunge milling,reverse plunge milling,wall plunge milling and slotted plunge milling,as well as the influence of cutting parameters on the cutting force of two-dimensional cavity plunge milling are studied from the angles of cutting force,cutting vibration and machining efficiency,at the same time the step distance and cutter radial cutting depth for two-dimensional cavity contour plunge milling is optimized.The results show that the cutting force of reverse milling is less than forward milling,which is beneficial to prolong the life of the cutter.Under the same cutting conditions,the cutting force of wall plunge milling is smaller than slotted plunge milling,but the vibration intensity of wall plunge milling is larger,and the cutting efficiency is lower than slotted plunge milling,therefore,reverse milling and slotted plunge milling should be considered as the preferred process for two-dimensional cavity contour plunge milling.In wall plunge milling,the radial force and the axial force of down milling are positively correlated with step distance,the radial force of down milling and three-dimensional cutting force of reverse milling are positively correlated with feed per tooth,the tangential force of down milling and reverse milling and the axial force of reverse milling are positively correlated with radial cutting depth.In slotted plunge milling,the three-dimensional cutting force is positively correlated with step distance and feed per tooth.The cutting force does not change with the cutting speed in either wall or slotted plunge milling.Aiming at the open two-dimensional cavity,the semi-closed two-dimensional cavity and the closed two-dimensional cavity the process strategy of variable tool path de-isolated corner,the process strategy of double-row slotted and the combination of double-row slotted and de-residual material,the process strategy of the combination of pre-drilling and singlecircle forming and variable tool path de-isolated corner are put forward respectively.The validity and efficiency of the proposed process strategy are compared through an example of two-dimensional cavity plunge milling with the traditional layer milling.