Sheet metal bending operation planning: Using virtual node generation to improve search efficiency

Abstract

. Sheet metal bending operation planning: Using virtual node generation to improve search efficiency. Journal of Manufacturing Systems, 18(2):127-139, 1999. Readers are encouraged to get the official version from the journal's web site or by contacting Dr. S.K. Gupta (skgupta@umd.edu). manufacturing operations planning, state-space search, sheet-metal bending, and setup planning. Sheet Metal Bending AbstractA large numberofmanufacturing operation planning problems can beformulated as state-space search problems. In case of sheet-metal bending operation planning, processing a search node involves extensive geometric reasoning. Such computationintensive node-processing limits the numberofsearch nodes that can be expanded in a reasonable amount of time, making it di cult to solve real-life operation planning problems.In this paper, we describe a scheme to speed up operation planning by virtual generation of state-space nodes. In this scheme, we eliminate unnecessary computation at the time of node generation by extracting the required information from already generated nodes. Although generation of two di erent search nodes rarely involves identical computation steps, there is considerable overlap in node generation steps. We h a ve divided the node generation step into a number of computation subproblems. When we need to generate a new node, we rst try to see if any of the node generation subproblems have been solved for any of the already generated nodes. If any subproblem has already beensolved for some other node, then we use the solution of that subproblem to save computation time. In such cases, we do not perform node generation computation steps, and therefore we c a l l s u c h node generation virtual.The scheme presented in this paper increases the node generation capability and allows us to consider many more search nodes. The ability to consider more search nodes helps us in solving more complex problems and nding better operation plans.

Sheet-metal bend sequence planning subjected to process and material variations

“…Based on this literature survey two kinds of bend sequence planning methodologies are found: (1) Bend sequence planning methodologies that are aimed to reduce allowable design tolerances for individual bends during the execution of a bending sequence [7,[10][11][12][13][16][17][18][19][20][21][22][23][24] (2) Bend sequence planning methodologies aimed to reduce total bending time by reducing tool and part handling tome, collision avoidance, ergonomic aspects, and geometric constraints [5,11,[25][26][27][28][29][30][31][32][33][34][35][36][37]. It is revealed during this survey that the effects of material and process variations on the overall part accuracy during the execution of a bending sequence is not reported in literature to the best of authors knowledge.…”

Knowledge-based sequence planning of shearing operations in progressive dies

“…These combinations make the number of possible designs so huge that the task becomes very difficult. One of the challenges involved in using state-space searching techniques for process planning is the number of search states will grow exponentially with the number of features (Gupta 1999). Using Figure 1(b) as an example, if the number of work stages is one, then the eight punches (P 1 , P 2 , P 3 , P 4 , P 5 , P 6 , P 7 , P 8 ) should all be placed on that stage.…”

Programming for evaluating strip layout of progressive dies

“…In addition to simplicity, superimposition is also easy to spot any overlapping of the superimposed punches as well as easy to exchange idea between designers. However, superimposing of many punches results in a huge number of possible strip layouts because the number of possible solutions will grow exponentially with number of features [2]. Schaffer [3] were probably the explorer in researching strip layouts for progressive dies.…”