| Ultrasonic Vibration-Assisted Machining(UVAM)has been successfully applied to the machining of honeycomb composites,The core part of its machining system,ultrasonic disc cutter,is a new tool in the stage of rapid development.The cutting mechanism and tool design method have not yet formed a complete system.As a result,the existing ultrasonic cutting tools of honeycomb composites cladding have many problems,such as large cutting force,high cutting temperature,serious fiber pulling out and low processing efficiency,and can do nothing about the high density of wave-absorbing honeycomb composites.Therefore,this paper adopts the research method combining theoretical analysis,simulation optimization and experiment to analyze the fracture forms of cutting honeycomb composites with different blade cutting tools,introduces the strain energy density factor theory and crack propagation theory,carries out the matching research of blade shape and technology,and designs two kinds of ultrasonic disc cutters for rough and finished wave-absorbing honeycomb based on the principle of minimum energy consumption.The main work and achievements are as follows:1.Modeling of cutting force and analysis of material fracture forms for cutting honeycomb composites with typical edge type ultrasonic disc cutters were carried out.The space kinematics of ultrasonic assisted cutting process of disk tool was modeled.The cutting force model of wave absorbing honeycomb cell panel cutting edge tool and the cutting force model of saw cutting edge tool were established,and the mechanism of cutting wave absorbing honeycomb cell panel by two typical cutting edge tools was revealed.The Ι-ΙΙ-ΙΙΙ type composite fracture was generated under the cutting action,and the Ι-ΙΙΙ type composite fracture was generated under the sawing action.This paper provides a theoretical basis for the establishment of strain energy density factor theoretical model of the fracture mode of cutting and sawing.2.An evaluation method of energy consumption of cutting materials based on strain energy density factor was proposed.Combined with the established cutting force model of cutting edge and saw cutting edge and the fracture type under cutting action,the strain energy density factor theory was innovatively introduced to analyze the mechanism of the difference of cutting forces.The minimum strain energy density factor was obtained by calculating the crack angle caused by the cutting of different edge types.By comparing the minimum strain energy density factor of cutting materials with different cutting edge types,the results show that the saw cutting edge type is suitable for rough machining,and the cutting edge type is suitable for fine machining.3.According to the characteristics of high brittleness impregnation and high stiffness of wave absorbing honeycomb composite materials,the parameters of the tool were optimized by combining the principle of minimum energy consumption and finite element simulation method,and a new ultrasonic saw cutting and cutting tool suitable for the processing characteristics of wave absorbing honeycomb composite materials was designed.According to the vibration characteristics of the tool and the actual processing situation,the tool coating design,reduce the friction,improve the tool life.4.Simulation and experiment of material fracture form under the action of saw cutting edge type and cutting edge type were carried out.ABAQUS finite element simulation and high-speed camera experiments were used to verify the different cutting action forms of the cutting edge and saw cutting edge.The crack generation and cracking Angle of the absorbing impregnated layer were observed during the cutting process,and the correctness of the crack initiation Angle in the theoretical cutting mechanism of strain energy density was verified.5.Experiments on cutting performance of two new ultrasonic cutting tools with different edge types were designed.The cutting performance tests of cutting force,cutting heat,tool wear and surface machining quality were carried out under the same process type.The experimental results show that the average cutting force and cutting heat are 70%.Abrasion resistance and surface machining quality have been greatly improved.Verify the correctness of tool design method and the excellent performance of designed tool. |
PDF Full Text Request