Tribology Behaviour In Micro U-Deep Drawing With The Mould Modified By DLC Film

Micro sheet forming was focused by researches from home and abroad and was rapidly developed because of its mass production, high efficiency, high precision, low cost and no pollution. The most complex and abroad applied micro sheet forming is micro deep drawing. Friction between the billet and the mould is one of the most important factors affecting the whole process of metal forming, such as forming energy, forming limit, surface quality and geometry of the product, tool life and so on. Size effect on friction in micro sheet forming was systematically studied in this paper, and lubrication method suit for micro sheet forming was also studied, both of which have great significance in promoting the development of micro forming process.A U-deep drawing mould was developed. The influence of the specimen surface topography, blank holder force, lubrication conditions and groove width to friction in micro U-deep drawing was investigated in this paper. The results showed that the friction increased with increasing the surface roughness and blank holder force. Friction size effect occurred and the friction coefficient increased with the decrease of the specimen size with the lubrication with oil. The deep drawing force increased with increasing the groove width.Because friction size effect occurred by using liquid lubricants, solid lubrication film was chosen. DLC was fabricated on the die by using plasma immersion ion implantation and deposition device. Structure and composition analysis was studied by atomic force microscope and Raman spectrum. Property analysis was investigated by ball-on-disk test, scratch test, and nano-indentation test. The results showed that DLC was superior as a lubricant in micro forming.Tribology behaviour in Micro U-deep drawing process was studied with the mould modified by DLC. The influence of the specimen surface topography and groove width to friction in micro deep drawing was investigated. The results showed that the DLC coated mould greatly decreased the forming force, compared to the lubrication with oil, the lubrication property of DLC film was fine and can decrease the friction force effectively. Friction size effect not occurred with the lubrication with DLC film, but the degree of the reduction of the friction force was approach to that lubrication with oil.