题目内容：

英语翻译
1.Introduction
A progressive die is used worldwide for mass production of
sheet metal parts.Design of progressive die is a complex and
highly specialized procedure and typically progressive die design
takes 20% of the lead time from the concept design to the final
stamping manufacture.The diverse nature of products produced
by progressive die demands a high level of knowledge on the part
of the die designer that can only be achieved through years of prac-tical experience.Checking the design features of sheet metal parts,
design of strip-layout,selection of die components,selection of
materials for die components; and modeling of die components
and die assembly are major activities for designing a progressive
die.The traditional methods of carrying out these tasks require
expertise and are largely manual and therefore tedious,time con-suming and error-prone.The quality of die design depends to a
large extent on the designer’s skill,experience and knowledge.A
number of researchers have tried to develop computer aided sys-tems for progressive die.For example,Murikama and Shirai
(1989)developed a CAD/CAM system which is capable of generat-ing assembly and dimensioned part drawings as the final output
but the strip and die layouts have to be done manually by the de-signer.Researchers at National University of Singapore and Insti-tute of High Performance Computing,Singapore also reported to
have developed an integrated modelling and process planning
system (2002) for planning bending operations of progressive dies.
Sima,Lee,and Jang (2004) carried out the study on the develop-ment of center carrier type progressive die for U-bending part pro-cess.Ghatrehnaby and Arezoo (2009) reported to develop an
automated nesting and piloting system for progressive dies.Some
researchers reported to have developed intelligent CAD systems for
progressive die.For example,Duffy and Sun (1991) developed a
knowledge-based system for the design of progressive stamping
dies using a feature-based approach.Lee,Lim,and Nee (1993)
developed IKOOPP,an intelligent knowledge-based process plan-ning system for the manufacture of progressive die plates.Cheok,
Foong,and Nee (1996) reported to have developed an intelligent
planning aid for progressive die design using PC development
tools.Ismail,Chen,and Hon (1996) have also worked on expert
systems for progressive piercing and blanking die design.Zheng,
Wang,and Li (2007) have developed intelligent CAPP system for
automobile panels.