Peng Ying-hong

Research on hybrid expert system application to blanking technology

Abstract This paper introduces the application of a second generation expert system in blanking technology. Depending on the empirical knowledge of domain experts and field literature, an expert system can play an important role in the field of blanking technology. An object-oriented blackboard model is given which can realize hybrid knowledge representation, such as production rules, frameworks and procedures. This paper mainly discusses the structure of the blackboard model and hybrid knowledge representation in blanking technology expert system. Since strip layout is a crucial and determining part in blanking technology, given here is an example of a blackboard model supporting hybrid knowledge representation about the strip layout process.

Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal ‐ mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double‐action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing ...

Simulation of Roll Forming With Dynamic Explicit Finite Element Method

Roll forming is a well known process in which a strip is guided through several sets of rolls that form the strip into the desired shape. However, industrial practice has been largely restricted to empiricism and heuristic rules. To avoid the forming defects and reduce the developing cost, simulation can be used to examine the roll forming process. As a continuous quasi‐static loading process, dynamic explicit finite element method often exhibits greater capability than other implicit methods in reducing CPU time, saving memory and dealing with the contact. However, a key problem, when using dynamic explicit codes, is that the method is a conditional stability algorithm. When using mass scaling or virtual velocity for increasing the time step size, dynamic effects are the fatal weakness. By choosing a series of appropriate control parameters for current damping models and loading velocity curves, the dynamic effects can be minimized to a reasonable level in engineering sense. This paper describes the simu...