Research On Design And Manufacturing Process Of Cold Pressing Precision Forming Die With Surface Texture

Surface texture can actively improve the tribological properties of the surface of the part.The surface texture of the friction pair manufactured by the method of cold pressing precision forming is an advanced industrialized surface texture manufacturing method,and one of its core technologies is the design and manufacture of the imprinting mold.The manufacturing level and craftsmanship of molds represent the level of industrialization of a country.The research and application of precision mold products with surface microstructures is a hot spot of current research,especially in micro-electromechanical systems,aerospace,communications and electronic technology,and precision instruments.And machinery,biology and medical equipment and other fields.The main technologies used in mold microstructure processing include EDM,electrochemical processing,micro ultrasonic processing,laser processing,micro beam processing,precision ultra-precision processing technology and various composite processing technologies.The molds for surface texture cold forming have not only the performance requirements of general molds for strength,rigidity,precision,wear resistance,etc.,but also the requirements for surface microstructure manufacturing,which is difficult to design and manufacture.This article proposes laser processing and electric discharge forming.The composite process solves the problem of surface texture processing on the surface of the superhard mold material,and at the same time improves the processing efficiency of the surface texture of the cold forming mold,and analyzes the surface morphology and mechanical properties of the manufactured mold,as well as the manufacturing process The influence of parameters on the surface properties of the mold.The main research contents and results of this paper are as follows:(1)Analyzed the basic principles and application characteristics of EDM,and designed a multi-unit combined surface texture cold press forming mold.The surface texture of the mold adopts spherical crown micro-protrusions,and the overall size of each mold unit is 20×20×20 mm,the size parameters of the spherical crown micro-protrusions on the mold surface are diameter: 100μm、200μm、300μm,and pitch: 1200μm;laser processing and EDM processing technology are used to process each mold unit to obtain spherical crown micro-protrusions Mold.(2)Using laser processing technology to prepare circular micro-pits on the surface of the graphite electrode,the morphology of the micro-pits on the surface of the graphite electrode after laser processing,and the size data of the micro-pits were obtained.At the same time,the graphite electrode was also obtained.Compared with the surface of the graphite electrode after laser processing,the surface loss morphology of the sample after the EDM treatment has changed in the surface size of the sample.And using laser processing and EDM combined processing technology,the smallest microscopic bump size that can be obtained is 100 μm.(3)Using the EDM reverse engraving process,the surface of the graphite electrode is prepared with micro-pit surface texture,and the spherical crown micro-protrusion array is fabricated on the surface of the mold steel,and the topography and the protrusion size data are obtained at the same time.The difference between the size of the die steel micro-protrusion and the electrode size is ±5μm.The mechanical properties of the surface texture of the mold after manufacture were analyzed.Compared with the untreated sample,the surface of the sample after the EDM treatment showed higher microhardness and roughness values.And the sample also showed a higher residual stress value.(4)By changing the machining current parameters of the EDM process,the effects of the machining current on the microhardness,surface roughness,and surface residual stress of the mold surface were studied separately.The microhardness,surface roughness and surface residual stress will increase accordingly.(5)The effects of the machining current parameters of the EDM process on the material removal rate(MRR)and graphite electrode wear rate(EWR)of the EDM process are studied.The results show that: when the machining current value is constant,the 100μm sample MRR and EWR The value is the largest,and the MRR and EWR values of the 300μm sample are the smallest.In addition,when the diameter of the micro-pits or micro-protrusions of the sample is constant,as the processing current increases,the MRR and EWR values will also increase.(6)Synthesizing the change law curve corresponding to the surface properties of the processing current and the mold steel,it can be obtained: when processing with a smaller current,the surface roughness and surface residual stress of the mold obtained are smaller,and the surface finish is better.The consumption of graphite electrodes is relatively small,but the processing efficiency is low.When processing with higher current,the obtained mold surface has higher microhardness,better hardness and wear resistance,and the workpiece material is removed faster,and the processing efficiency is higher.However,the mold surface is not smooth enough at this time.And it is prone to defects such as cracks.