Experimental invertigation on forming defects in flat surface-convex edge hemming:roll, recoil and warp。
Forming defects, roll and warp, in hemming of mild steel sheets with flat surface-convex edge geometry are experimentally investigated. The objectives in this study wre to develop fundamental knowledge of the effects of process parameters on the final hem quality (defects including roll-in/out, recoil and warp without wrinkling and hem-out)and to develop improved process and tool design rules for flanging and hemming based on experimental findings. The experiments were designed using half a fractional factorial array with four 2-level factors replicated three times. All main effects were determined as well as non-alias 2-level interactions. Tesults of the experiments were summarized for the use of process and die designers.
Experimental investigation and theoretical analysis of roll forming of electrical resistance welded pipes。
Roll forming is a general term used to describe a large class of continuous manufacturing processes where a long strip of sheet metal is deformed into products with desired geometry by passing through a series of rotating rolls arranged in tandem. Electrical resistance welded (ERW) pipe can be manufactured by roll forming. Based on the updated-Lagrange method in deformation mechanics,an elastic-plastic large deformation spline finite strio method is developed to analyze roll-forming ERW pipe. The longitudinal strains, the opening values, and the springback of the skelp are obtained. Simulated results are compared with the results obtained. They agree well with each other.
Experimental and numerical investigation of grid sheet bending behavior in four-roll bending。
Gird sheet is a sandwich material consisting of two metal face sheets and a core of woven wire mesh that are joined by welding.It has been designed to act as an actively cooled heat shield,e.g.for steam turbine casings.For this purpse,cylindrical parts have to be produced from initially flat gird sheet.This paper focuses on four-roll bending of gird sheet.It is shown that springback and the number of failed spot welds after forming can be reduced by stress relief annealing and appropriate forming conditions.A finite element model of roll bending of grid sheet is presented,which has sht up to predict springback and spot weld failure.
Development of an applied roll forming pass design expert system based on the shape element idea。
A new design idea,based on the “shape element”,is introduced to develop a roll forming pass design expert system.Shape elements recognizing knowledge base,bend angle distribution knowledge base,rolls arranging knowledge base and related reasoning enginer are constructed in the system by using object-oriented method.Pass flower and rolls design can be automatically done.Some examples show that this expert system is practical and effective.