Research On Friction And Wear Mechanism In Ultrasonic Vibration Assisted Forming Of High Strength Steel

High-strength steel is the most commonly used material to realize the lightweight of automobiles.Due to the high strength,high plasticity and low plasticity of high-strength steel,hot stamping is often used to achieve high-strength steel forming and improve forming accuracy.However,hot stamping has high production energy consumption,complex mold processing,low service life,and high production costs.If the cold stamping process is used to realize the forming of high-strength steel,the springback after forming is large,the forming accuracy is difficult to control,the deformation resistance is large,and the service life of the mold is seriously reduced.The material has volume effect and surface effect under ultrasonic vibration.It is an ideal process to use ultrasonic vibration to assist the forming of high-strength steel.This paper proposes to study the friction mechanism between die and plate and die wear mechanism in high-strength steel stamping under the condition of ultrasonic vibration.The thesis first designs and builds an experimental platform for mold friction and wear under ultrasonic vibration;the experimental platform is used to experimentally study the friction and wear between 22 Mn B5 high-strength steel sheet and Cr12 Mo V mold steel under ultrasonic vibration,mainly to explore the amplitude and relative sliding under ultrasonic vibration conditions.Influence mechanism of velocity and normal pressure on friction between plate and die and die wear;based on Archard wear model,a finite element numerical simulation model of die wear under ultrasonic vibration is established,and the influence mechanism of this numerical model on die wear under ultrasonic vibration is established Analyzed.The research results show that under different lubrication conditions,applying ultrasonic vibration to the mold can reduce the friction between the mold and the blank,and the friction coefficient decreases with the increase of the amplitude,but the relative sliding speed and positive pressure under different lubrication conditions The influence on the friction coefficient is not consistent;under different lubrication conditions,applying ultrasonic vibration to the mold can effectively improve the wear of the mold surface,and the larger the amplitude,the smaller the wear amount,and the increase of the relative sliding speed and positive pressure will aggravate Wear of die surface;the influence mechanism of ultrasonic vibration on die wear and friction between blank and die is given.Using the established finite element numerical simulation model of mold wear under ultrasonic vibration,the numerical model is used to theoretically analyze the effect of ultrasonic vibration on mold wear,and the influence mechanism of ultrasonic vibration frequency on mold wear is discussed.The wear of the large mold is smaller,but the excessively high ultrasonic vibration frequency will aggravate the mold wear.The research results of this paper can provide theoretical and technical support for reducing the manufacturing cost of high-strength steel forming parts and realizing green manufacturing of high-strength steel forming parts.