Optimal and intelligent computer-controlled sheet metal forming.

摘要

With the objective to develop an optimal and intelligent computer controlled sheet metal forming system, basic issues and possible solutions related to analysis, modeling, sensing and control of sheet metal forming are identified and examined in this project. Modified forms of Duncan test with and without a bead are used to measure sheet forming friction and characterize the effect of a bead penetration on the resulting restraining force. A test apparatus, based on the sensing scheme developed for in-process measurement of local flow restraint, is constructed and characterized with the capability of simultaneously measuring loads normal and parallel to the test surface. The feasibility of monitoring sheet metal forming processes with the acoustic emission measurement is investigated. While a complete analytical solution is not available, finite element modeling with experimentally determined contact boundary conditions and material properties is carried out to analyze the cup-drawing process and establish the physical basis for understanding the acoustic emission behavior during cup-drawing. A computer controlled cup-drawing press with an active bead is developed. Position control of the bead penetration allows in-process variation of the restraining force. Punch position tracking and programmable punch motion permit close-loop process control without loss of formability. Real-time close-loop control of sheet metal forming is demonstrated by controlling the total restraining force in strip-drawing through in-process varying the bead penetration. Fundamental understanding and technological capabilities needed for real-time control of sheet metal forming are established.