Computing a flattest, undercut-free parting line for a convex polyhedron, with application to mold design

Majhi, Jayanth; Gupta, Prosenjit; Janardan, Ravi

doi:10.1007/bfb0014489

Cited by 17 publications

(19 citation statements)

References 9 publications

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“…In other words, a flat parting line reduces the defect cost. Hence it is proposed that the flattest possible parting line be found [Ravi90,Majh99,Chen03]. The available approaches to finding the flattest parting line is limited to simple convex parts.…”

Section: Finding Assembly Configuration With Flattest Parting Linementioning

confidence: 99%

“…Since the 'both' region can be formed by either the core or cavity, it provides a feasible region where an optimal parting line can be located. Priyadarshi and Gupta [Priy04] presented an algorithm that uses the flatness criteria proposed by Majhi et al [Majh99] to find an optimal parting line. The parting line is used to split the 'both' region into core region and cavity region.…”

Section: Introductionmentioning

confidence: 99%

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Algorithms for generating multi-stage molding plans for articulated assemblies

Priyadarshi¹,

Gupta²

2009

Robotics and Computer-Integrated Manufacturing

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Plastic products such as toys with articulated arms, legs, and heads are traditionally produced by first molding individual components separately, and then assembling them together. A recent alternative, referred to as in-mold assembly process, performs molding and assembly steps concurrently inside the mold itself.The most common technique of performing in-mold assembly is through multistage molding, in which the various components of an assembly are injected in a sequence of molding stages to produce the final assembly. Multi-stage molding produces better-quality articulated products at a lower cost. It however, gives rise to new mold design challenges that are absent from traditional molding. We need to develop a molding plan that determines the mold design parameters and sequence of molding stages. There are currently no software tools available to generate molding plans. It is difficult to perform the planning manually because it involves evaluating large number of combinations and solving complex geometric reasoning problems.This dissertation investigates the problem of generating multi-stage molding plans for articulated assemblies. The multi-stage molding process is studied and the underlying governing principles and constraints are identified. A hybrid planning framework that combines elements from generative and variant techniques is developed. A molding plan representation is developed to build a library of feasible molding plans for basic joints. These molding plans for individual joints are reused to generate plans for new assemblies. As part of this overall planning framework, we need to solve the following geometric subproblems -finding assembly configuration that is both feasible and optimal, finding mold-piece regions, and constructing an optimal shutoff surface. Algorithms to solve these subproblems are developed and characterized.

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Section: Finding Assembly Configuration With Flattest Parting Linementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Algorithms for generating multi-stage molding plans for articulated assemblies

Priyadarshi¹,

Gupta²

2009

Robotics and Computer-Integrated Manufacturing

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“…Their objective function is defined as a function of the flatness of the parting line, draw depth, number of side cores required to form the undercuts, machining complexity, etc. Majhi et al [13] presented an algorithm for computing an undercut-free parting line that is as flat as possible for a convex polyhedral object.…”

Section: Two-piece Mold Designmentioning

confidence: 99%

“…This belt provides a feasible region E where an optimal parting line can be located. The flatness criteria proposed by Majhi et al [13] is then used to find the flattest possible parting line.…”

Section: Locating Parting Line Of a Mold-piece Regionmentioning

confidence: 99%

Geometric algorithms for automated design of multi-piece permanent molds

Priyadarshi

Gupta

2004

Computer-Aided Design

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Multi-Piece molds, which consist of more than two mold pieces, are capable of producing very complex parts⎯parts that cannot be produced by the traditional molds. The tooling cost is also low for multi-piece molds, which makes it a candidate for pre-production prototyping and bridge tooling. However, designing multi-piece molds is a time-consuming task. This paper describes geometric algorithms for automated design of multi-piece molds. A multi-piece mold design algorithm has been developed to automate several important mold-design steps: finding parting directions, locating parting lines, creating parting surfaces, and constructing mold pieces. This algorithm constructs mold pieces based on global accessibility analysis results of the part and therefore guarantees the disassembly of the mold pieces. A software system has been developed, which has been successfully tested on several complex industrial parts.

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“…There has been a fair amount of work on the castability problem [1,3,4,5,9,10,11] for the case that there is no core. Chen, Chou and Woo [6] described a heuristic to compute a parting direction to minimize the number of cores needed.…”

Section: Introductionmentioning

confidence: 99%

Casting an Object with a Core

Ahn

Bae

Cheng

et al. 2005

Algorithms and Computation

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This paper addresses geometric problems that concern manufacturing an object using a cast with a core. In casting, molten material is poured into the cavity of the cast and allowed to solidify. The cast has two main parts to be removed in opposite parting directions. To manufacture more complicated objects, the cast may also have a core to be removed in a direction skewed to the parting directions. In this paper, given an object and the parting and core directions, we give necessary and sufficient conditions to verify whether a cast can be constructed for these directions. In the case of polyhedral objects, we develop a discrete algorithm to perform the test in O(n 3 log n) time, where n is the object size. If the test result is positive, a cast with complexity O(n 3 ) can be constructed within the same time bound. We also present an example to show that a cast may have Θ(n 3 ) complexity in the worst case. Thus, the complexity of our cast is worst-case optimal.

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Computing a flattest, undercut-free parting line for a convex polyhedron, with application to mold design

Cited by 17 publications

References 9 publications

Algorithms for generating multi-stage molding plans for articulated assemblies

Algorithms for generating multi-stage molding plans for articulated assemblies

Geometric algorithms for automated design of multi-piece permanent molds

Casting an Object with a Core

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