Research On Wear Characteristic And Hole Quality Of Hard Helical Milling For 40CrMnMo Hole-Making

40crmnmo is widely used in manufacturing process of monomer pump due to the good comprehensive performance.However,the quality of machining 40 crmnmo hole has posed a great challenge,owing to high strength and hardness.Spiral milling hole,a novel method for making hole,is an ideal solution for the process of machining hard materials hole.The tool life and the quality of machining hole become the important factor of the economical and reliability of hard spiral milling.In this paper,it was the milling force,tool wear and breakage characteristic and the hole machining quality of 40 CrMnMo that were studied by using TiAlN coated end mill and TiAlSiN coated end milling.The main contents were summarized as follows:(1)The main factors affecting the spiral milling were analyzed and a single factor experiment of helical milling was designed.The influence of different milling parameters,helix angle of tool and the tool wear and breakage on the milling force was analyzed.It was found that the milling force increased as increasing axial feed per tooth and milling speed,increased with the increase of the tangential feed per tooth,and then decreased.The milling force increased with the tool wear and fracture,meanwhile the variation of the milling force had an opposite tendency with the increasing of helix angle.The milling force prediction model was established according to the milling force data and the milling force empirical formula.(2)A single factor experiment was carried out with different coating materials and helical angle tool.The cutting tool wear characteristic,wear mechanism and tool life were analyzed.The experimental results showed that the tool wear was serious during the milling process with the fractured wear patterns of the cutting tools.Tool wear mechanism was mainly including wear and coherence.Tool wear morphology were including end cutting edge breakage at the tool nose,periphery cutting edge breakage,peeling,crack,abrasive wear.Periphery cutting edge breakage was easy to happen along with the increasing of helix angle leading to the strength of periphery cutting edge decreased.This paper presented the impact of the axial feed per tooth,the tangential feed per tooth and milling speed on tool life.Increasing the axial feed per tooth the tool life increased,however,the tool life increased with the increase of the tangential feed per tooth and the cutting speed,and then decreased.In a nutshell,tiAlN coated milling cutter life was better than TiAlSiN coating tool.The milling parameters were optimized based on the BP neural network and the tool life-efficiency surface response method,obtaining the optimal tool life and processing efficiency parameter combination.(3)This paper studied the influence of the tool wear and breakage on hole size and surface quality,showing that the burr formation of the hole were related to end cutting edge wear and breakage.Meanwhile,periphery cutting edge had a direct and significant impact on smearing and scratches of machined surface.The average diameter of the machined hole is less than 10 mm because of a phenomenon of shrinkage during the milling process.As the tool wear and damage increase the hole surface scratche and smearing continue to increase.It was found that the scratche and smearing of machined surface increased as increasing tool wear or fracture.