Study On The Relationship Of Different Unilateral Constraints And Rectangular Cup Forming Limit

Rectangular sinks are the common rectangular cup in our daily life, and the single sink is one representative kind of rectangular sinks. The long panel, also the long flange, makes the forming processes of that sink different from the traditional one’s, its variable length still makes its forming limit change. If the relationship between drawing limit and the length of flange could be found out, it can be used to design the same type of cups as guidance. This paper would carry out the following research to study that relationship.1. In order to investigate the relationship between the cup’s drawing limit and the length of flanges, this paper put forward the concept of constraints and defined five concepts as follow:constraint. unconstraint, unilateral constraints, unilateral constraint degree, variable unilateral constraint degree. It established the study model of rectangular cup with unilateral constraint as below:a rectangular cup with unilateral constraint has three flanges in the same size of L. and the rest one in the other size of Z. Furthermore, the rest one is longer than the three ones(L1=L2=L3=L<X).2. So as to analyze the deformation and flowing characteristics of rectangular cup with the different unilateral constraints, this essay focused on the material flow points of the horizontal and vertical directions, the data shows that the flowing department of the short flange which flows to fillet area is more than the long flange’s, this trend shows an increasing trend with the friction factor increases; with the different BHF. the different value of the flowing department between the horizontal short flange and the vertical one is less than zero when BHF is too big or too small.3. In order to analyze the effects of process parameters on the forming limit of rectangular cup with the different unilateral constraints, it chose four process parameters (rough geometric parameters, material properties, mold geometry, stamping process parameters) for detailed analysis. It also used the Inverse and Forward finite element methods to get the optimum blank for rectangular cup with the different unilateral constraints.The drawing limit height was increased by the optimized blank in the finite element analogy and contrast experiments with the same situations, so as to the productions*quality.4. For the purpose of studying the relationship between different unilateral constraint degrees with the drawing limit of rectangular cups, this paper set the short side flange in a certain value, and used the orthogonal test to get the better drawing limit for the cups of each long side flange. Dynaform numerical simulation is using to simulate the forming processes, the four vital factors as follow are taken into account:the friction coefficient. BHF. punch and die clearance, die radius. The results show that when the unilateral constraint degrees range from1to4. the drawing limit decrease clearly. When the unilateral constraint degrees range form4to6. drawing limit is almost flat in the slight decreasing trend.5. For the sake of the relationship between the variable unilateral constraint degrees and rectangular cups" drawing limit, this essay set the cup’s drawing limit as180mm. also used orthogonal methods to design the experiments, and used Dynaform software to simulate the forming processes. The results form the tests show that all the maximum length of the long side flanges are375mm. and variable unilateral constrains are12.5.6.25.4.1667. For the same type of single sinks, the variable unilateral constraint degrees of the test results could be used in the design of those sinks, and make the manufacturing processes and costs reduce.6. In order to predict the cup’s drawing limit with unilateral constrains, the paper based on the BP neural network, used the Matlab neural network toolbox to write the programming language of training, and established the predictive model of drawing limit. The program gets the convergence curve after154times of training, and get the average prediction error as9.05%. The error is in a good condition, so this model could predicted the cup’s drawing limit effectively.