Mechanism Study On The Influences Of Surface Texture On The Friction And Abrasion Characteristics Of Mould Surface

Moulds are the foundation of industrial development and the ultimate approach for the mass production in factories.They are indispensable in the process of realizing the modernization of industry.The quality of moulds directly affects the quality of products as well as the effectiveness and the R & D capability of factories.At the same time,the service life of moulds directly influences the production cost of products.Therefore,the production level of moulds represents the development level of a country's manufacturing industry.In the process of metal forming,there are many factors that will influence the service life of moulds.The major influencing factor is abrasion,and the speed of which determines the length of the service life of moulds.Therefore,in the research,development and manufacture of moulds,the key to prolonging the service life of moulds is to increase the abrasive resistance of moulds so as to decrease the abrasion loss.Current researchers have found that through the rational design of micro surface topography,the lubrication condition of surface of friction pair can be improved,the load-bearing capacity of oil film can be increased,the friction coefficient can be decreased and the abrasion loss can be lowered.By studying the influences of mould surface topography on friction and abrasion in the material forming process,the paper explores new ways to lower the abrasion loss of moulds and increase their service life.Through simulative calculations and tests,the paper conducts systematic and comprehensive researches on the influences of surface morphology structures and structural parameters on the friction coefficient and the bearing capacity,the influences of different processing methods and machining parameters on surface morphology,the influences of surface morphology on the surface friction coefficient and abrasion characteristics of mould steel and the simulation of abrasion loss of moulds during the sheet metal forming process.Researches on the following aspects have mainly been carried out:(1)Theoretical analysis on the influences of the structure and parameters of surface morphology on the friction coefficient,the friction force and the bearing capacity of the friction pair.Solve the Reynolds equation by adopting the method of Fortran programming,so as to theoretically research the influences of pit structures,such as circular pit,rectangular pit and trapezoidal pit,and different pit area ratios and pit spacing on the surface friction,the bearing capacity and the friction coefficient of micro units.(2)The finite element method analysis on the influences of surface morphology on mold wearFinite element analysis method was used on analysis on the influences of ball crown pit,the abrasion of rectangular groove,and the original surface morphology on mold wear using simple plate mould as an example.The positive effect coefficient on wear and the negative effect of surface morphology structure were compared under the condition of the oil lubrication friction.(3)The influences of surface morphology on the friction and abrasion characteristics of mould steel obtained through chemical etching.Taking Cr12 as the research material,etch the surface of the specimens through chemical etching.It has been discovered through lots of tests and researches that irregular topographies on the surface of the specimens can be effectively and easily obtained with this method.The specific shape,size and depth of the topographies are related to the strength of corrosion agent and the length of corrosion time.Friction and abrasion tests have been carried out based on the above topographies to research the influences of irregular topographies on friction coefficient and abrasion loss in the absence of oil lubrication,and comparative studies have been conducted with the initial surface topographies.(4)Study of the influences of surface morphology on the friction and abrasion characteristics of mould steel obtained through cold pressure technology.Taking Cr12 MoV as research materials,cold pressure technology combined with the way of ball head rotation and the rotation is used in the process of groove surface morphology.The influences of the feed rate of the Y direction and the Z direction of the ball head cutter when it doesn't rotate on the surface roughness,hardness and surface morphology of mould steel during cold pressure processing and the influence rule of those parameters on friction coefficient and abrasion loss of cold work mould steel are analyzed.The influences of the speed of main shaft and the feed rate of the Z direction of the ball head cutter when it rotates in high speed on the surface morphology of mould steel during cold pressure processing and the influence rule of surface morphology on friction coefficient and abrasion loss of cold work mould steel are studied.(5)Conclusion the advantages and disadvantages of the above methods of surface processingThe advantages and disadvantages of the chemical etching method,the ball head cold pressing method(ball head not rotating and high speed rotating)in the surface machining quality were compared on the anti-friction effect,the difficulty of operation,economy and surface morphology of the controllable four aspects.