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Constraint Analysis and Reduction of Over-Constraints for Tolerance Design of Assemblies - A Case Study of Ball Valve Design

조립체 공차설계를 위한 제약해석과 과잉제약 개선 - 볼밸브 설계 사례연구

Park, Jun Il;Yim, Hyunjune
박준일;임현준

  • Received : 2016.02.22
  • Accepted : 2016.07.09
  • Published : 2016.08.01

Abstract

Mechanical designers often make mistakes that result in unwanted over-constraints, causing difficulty in assembly operations and residual stress due to interference among parts. This study is concerned with detection and elimination of over-constraints. Screw theory is a general method that is used for constraint analysis of an assembly and motion analysis of a mechanism. Mechanical assemblies with plane-plane, pin-hole, and pin-slot constraint pairs are analyzed using screw theory to illustrate its utility. As a real-world problem, a ball valve design is analyzed using the same method, and several unwanted over-constraints are detected. Elimination measures are proposed. Nominal dimensions of some parts are adjusted, and dimensions and tolerances of the pins and holes are modified using the virtual condition boundary concept. The revised design is free of over-constraints. General procedure for applying screw theory to constraint analysis is established and demonstrated; it will contribute to improving quality of assembly designs.

Keywords

Over-Constraint;Assembly design;Screw theory;Tolerance design;Ball valve

References

  1. Whitney, D. E., "Mechanical Assemblies: Their Design, Manufacture, and Role in Product Development," Oxford University Press, 1st Ed., pp. 62-111, 2004.
  2. Yu, J., Li, S., Su, H.-j., and Culpepper, M., "Screw Theory Based Methodology for the Deterministic Type Synthesis of Flexure Mechanisms," Journal of Mechanisms and Robotics, Vol. 3, No. 3, Paper No. 031008, 2011.
  3. Cervantes-Sanchez, J. J., Rico-Martinez, J. M., Tadeo-Chavez, A., and Perez-Soto, G. I., "The Kinematic Design of Spatial, Hybrid Closed Chains Including Planar Parallelograms," Robotics and Computer-Integrated Manufacturing, Vol. 27, No. 3, pp. 614-626, 2011. https://doi.org/10.1016/j.rcim.2010.10.008
  4. Fang, Y. and Tsai, L.-W., "Enumeration of a Class of Overconstrained Mechanisms Using the Theory of Reciprocal Screws," Mechanism and Machine Theory, Vol. 39, No. 11, pp. 1175-1187, 2004. https://doi.org/10.1016/j.mechmachtheory.2004.06.003
  5. Dai, J. S., Huang, Z., and Lipkin, H., "Mobility of Overconstrained Parallel Mechanisms," Journal of Mechanical Design, Vol. 128, No. 1, pp. 220-229, 2006. https://doi.org/10.1115/1.1901708
  6. Adams, J. D. and Whitney, D. E., "Application of Screw Theory to Constraint Analysis of Mechanical Assemblies Joined by Features," Journal of Mechanical Design, Vol. 123, No. 1, pp. 26-32, 2001. https://doi.org/10.1115/1.1334858
  7. Rusli, L., Luscher, A., and Schmiedeler, J., "Analysis of Constraint Configurations in Mechanical Assembly via Screw Theory," Journal of Mechanical Design, Vol. 134, No. 2, Paper No. 021006, 2012.
  8. Park, M., Jeong, N., Kim, Y., Kim, Y., Hwang, I. S., et al., "A Study on Design of Seat Retainer for Improving Offshore Ball Valve Performance," Proc. of 2015 Joint Conference of the Korean Association of Ocean Science and Technology Societies, pp. 357-361, 2015.
  9. Mantripragada, R. and Whitney, D., "The Datum Flow Chain: A Systematic Approach to Assembly Design and Modeling," Research in Engineering Design, Vol. 10, No. 3, pp. 150-165, 1998. https://doi.org/10.1007/BF01607157
  10. The American Society of Mechanical Engineers, "Dimensioning and Tolerancing," Y14.5M, 1994.

Acknowledgement

Supported by : 홍익대학교, 대우조선해양주식회사