The degree of wear on a material’s surface after deep drawing has a great influence on the performance and quality of the product; in particular, tantalum plates are prone to adhesive wear during deep drawing. In this paper, we propose a method to improve the surface quality of deep drawing products by optimizing the servo pulse stroke curve to solve the above problems. At the same time, in order to explore the influence of curve parameters on the adhesive wear of tantalum sheets in deep drawing, nine drawing stroke pulse curves are designed, with three levels and four factors. The finite element method is used to analyze the wear depth change of dies and products after drawing with different curve modes. It is found that the wear results obtained under the different curves differ greatly. Considering the actual production efficiency and production quality, the drawing time and the maximum wear depth are taken as optimization objectives. An analysis of variance is carried out using the Minitab software, considering the maximum wear depth and deep drawing time of the product in the finite element analysis results, and the best parameter combination is obtained for each quality characteristic. Then, the optimal drawing stroke curve is obtained using Taguchi grey relational analysis, with its grey relational grade being the highest among all curves. Finally, the optimal curve is compared against a traditional curve on a servo press. The results show that the surface quality of the product and the drawing efficiency can be improved by the use of the optimized mode; in particular, compared with traditional drawing, the maximum wear depth is reduced by 56.67% and the drawing time is reduced by 18.06%.

3D auxetic structures, which present negative Poisson’s ratio in the uniaxial compression deformation, is an ideal artificial material for meta-implants because of its lightweight, good material property and suitable porosity for bone recovery compared with conventional meta-biomaterials. Selective laser melting (SLM) is commonly used to produce metallic 3D auxetic structures but limited by the melting temperature and reflect rate of the material, and micro assembled (MA) structures is an alternative manufacturing process. However, the influence of size effect in 3D auxetic structures and the difference of the constitutive model of 3D auxetic structure produced by SLM and MA have not been discussed. In tandem of this, the mechanical property comparison of 3D auxetic structures produced by SLM and MA is conducted and a structural surface layer model for 3D auxetic structures is proposed. The result indicated that both SLM and MA structure can achieve auxetic effect. It is found that the Poisson’s ratio of the SLM and MA structures decrease when increasing the size factor of the structure, and the negative Poisson’s ratio effect is more obvious when the Young’s modulus is relatively small. FE simulation result of Poisson’s ratio is closer to experimental result of MA structures due to complexity of 3D auxetic structures. This paper thus provides a relatively helpful constitutive model for the prediction of the mechanical behavior of 3D auxetic structure.

Lubrication is one of the key factors to improve metal-forming quality. In the process of deep drawing, seizing tumors easily occur on the contact surfaces between the tantalum metal and the mold, which greatly affects the forming quality of the deep-drawn parts. Quality-forming quality problems that occur during the deep drawing of tantalum metal are studied from the perspective of lubrication in this paper. Three lubrication media, caster oil, PE (polyethylene) film, and DLC (Diamond Like Carbon) film, were adopted in the deep drawing of tantalum cylindrical cups. A universal testing machine and microscope were used to investigate the effect of lubrication media on the limit-drawing ratio, maximum forming force, and surface topography quality during the deep drawing process of the tantalum sheet. The results reveal that the lubrication of the PE film and DLC film can greatly improve the forming quality of the tantalum metal sheet, in which the DLC film has higher wear resistance and lower friction coefficient and can be used as the lubricating medium in the industrial forming process of tantalum deep-drawn parts.