Synthetic Research On Technology Of Large Scale Progressive Die With High Precision And Complex Structure

Mould & Die is important technical equipment in industrial production. It is also one of the most important developmental foundations for all departments of country economy. The progressive die is a kind of complex and precise forming die. It possesses many advantages such as high efficiency,accuracy and long life. So it is used for many kinds of automation production in sheet metal forming. The progressive die relates to many key technologies including metal forming theory,sheet steel forming process,die design and manufacture,die material and so on. Therefore it is very significant to study the progressive die.According to domestic research actuality and facing the key technical problems of progressive die,the synthetic research on large scale,precise and complex progressive die is developed in this paper. The progressive fin die is selected as research object and aactual product in order to verify the research results.Beginning with metal forming theory,dynamic behavior and characteristics ofplastic state is presented. To find the basic rules for sheet metal forming,many theories are discussed such as dynamical essential,characteristics and analysis methods of plastic deformation and forming limit.The deformation specialties of drawing,blanking,piercing-flanging and bending processes in progressive die are analyzed. The stress-strain relations of four forming processes are reasoned. Their influencing factors are discussed from the view point of die structure. These works provide theory basis for the design and calculation of progressive die.On the basis of the discuss about metal forming theory and the analysis of deformation specialties for four forming processes,the project idea that adopt sub-die schism structure to design die is proposed. By particular design and calculation,a kind of design method system for large scale precise complex progressive die is established. The design part includes the collectivity design,structure design and the design of assistantframework for delivering sheet metal. The calculation part includes die precision calculation,main structure parameters of die and punch,and pressing center calculation.Due to adopting the sub-die schism structure,a new problem is presented,which is how to determine the die-fitting precision in the assembling process. The die-fitting dimension chain and precision optimize mathematics model are established. And the optimize distribution for die-fitting precision is made. At the same time,the key process of manufacturing die is researched. The machining problems about high precision parts of progressive die are solved.Another important problem of progressive die is about the life of die. The analysis of wear failure on the die is made by the author. The progressive die is applied for volume productions under high speed pressing condition. Its life directly influences the cost and quality of product. So it is very important to study the wearable properties of die materials. The wearable mechanism is investigated by making wear tests of two materials Crl2MoV (normal die steel) and CPM10V (power metallurgy die steel). The influence factors for die wearing are studied on the microstructure of die material. The wearable characteristics of steel bonded carbide are also researched. This provides theoretical and experimental basis for substituting homemade materials for imported ones.The collective effect of the above researches is verified in the process of manufacturing a set of large scale precise complex progressive die. After using the die for more than one year,the results show that the die's total pressing times are over 60 million and the quality of the fin made by the die attain the technical standard.