[工学]Chapter 2-2 Numerical Control.ppt

IE 447 - CIM Lecture Notes - Chapter 3 Numerical Control 2.2 Numerical Control (NC) Numerical Control The numerical data required to produce a part is provided to a machine in the form of a program, called part program . The program is translated into the appropriate electrical signals for input to motors that run the machine. 1. The History of CNC 1725-Knitting machine针织机controlled by sheets of punched cardboard 1863-Player piano introduced 1947-John Parsons of Parsons Corp. in Traverse City, Michigan coupled a computer to a jig borer(座标镗床) In 1949, The U.S. Air Force awarded Parsons a ‘contract ’to develop a new type of machine tool that would be able to speed up production methods. Parsons commissioned the Massachusetts Institute of Technology (M.I.T) to develop a practical implementation of his concept1. The NC concept was proposed in the late 1940s by John Parsons of Traverse City, Michigan. Parsons recommended a method of automatic machine control that would control the position of a machine in an attempt to machine ‘helicopter blade叶片. 1955 - John Parsons and US Air Force define a need to develop a machine tool capable of machining complex and close tolerance aircraft parts with the same quality time after time (repeatability). MIT is the subcontractor and builds the machine for the project. 1959 - MIT announces Automatic Programmed Tools (APT) programming language 1960 - Direct Numerical Control (DNC). This eliminates paper tape punch programs and allows programmers to send files directly to machine tools 1968 - Kearney Trecker machine tool builders market first machining center 1970’s - CNC machine tools Distributed Numerical Control 1980’s - Graphics based CAM systems introduced. Unix and PC based systems available 1990’s - Price drop in CNC technology 1997 - PC- Windows/NT based “Open Modular Architecture Control (OMAC)” systems introduced to replace “firmware” controllers. Scientists and engineers at M.I. T built a control system for a tw