Optimization of machining fixture layout for tolerance requirements under the influence of locating errors

Vishnupriyan, S.; Majumder, M. C.; Ramachandran, K. P.

doi:10.4314/ijest.v2i1.59107

Cited by 22 publications

(17 citation statements)

References 19 publications

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“…Kedua penelitian tersebut tidak menggunakan programa matematika, tetapi menggunakan algoritma genetika (genetic algorithm). Serupa dengan kedua penelitian tersebut, Vishnupriyan, et al [12] melakukan optimasi tata-letak lokator untuk memenuhi kebutuhan toleransi yang dipengaruhi oleh kesalahan penempatan, menggunakan algoritma genetika.…”

Section: Pendahuluanunclassified

Model Optimasi Fixturing Benda-kerja dengan Prinsip 3-2-1 Klem Tunggal

Toha

Diratama

Wigenaputra

2017

jti

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Abstract:To hold a workpiece firmly at its place, a fixture is required. Some previous studies have discussed the balance of forces and moments that are based on kinematic model, screw theory, contact force and position error. The most fundamental problem in the design of the fixture is to determine the coordinates of a locator and clamp and a clamping force, so that the workpiece is stable during the machining process. This paper discusses an optimization model to determine the coordinates of the locator and clamp and the clamping force, focusing to the balance of forces and moments. Specifically, the optimization model developed is used for solving the problem of fixturing the workpiece applying the 3-2-1 principle. Numerical examples are given to illustrate the application of the model. The optimization model is solved using standard nonlinear programming software.Keywords: Fixture, force, moment, locator, clamp, optimization. PendahuluanPenetap (fixture) merupakan alat bantu yang digunakan pada pemesinan, perakitan, inspeksi, dan berbagai operasi manufaktur lainnya. Dalam proses pemesinan, benda-kerja akan mengalami gaya dan momen pemotongan, sehingga diperlukan penetap untuk memegang benda-kerja agar diam pada tempatnya. Hal ini diperlukan agar bendakerja hasil pemesinan sesuai dengan spesifikasi desainnya. Penetap terdiri dari lokator dan klem. Lokator berperan untuk menjaga benda-kerja berada pada tempatnya, sedangkan klem berperan untuk menghilangkan pergerakan yang terjadi, dengan memberikan gaya yang akan melawan pergerakan benda-kerja.Suatu benda-kerja pada ruang tiga dimensi, dapat bergerak pada dua-belas arah (memiliki dua-belas derajat kebebasan). Penetapan (fixturing) dengan prinsip 3-2-1 menempatkan tiga lokator bawah, dua lokator samping, dan satu lokator pada samping lainnya, sehingga benda-kerja hanya memiliki tiga derajat kebebasan. Untuk memegang benda kerja pada tempatnya (nol derajat kebabasan), digunakan satu klem atas, satu klem samping, dan satu klem samping lainnya, yang masing-masing berlawanan dengan arah lokator.Untuk memegang benda-kerja pada tempatnya, diperlukan analisis keseimbangan gaya dan momen yang terjadi. Beberapa penelitian sebelumnya yang membahas ini diantaranya adalah Asada dan By [1] yang mengembangkan model kinematik penetap.

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Section: Pendahuluanunclassified

Model Optimasi Fixturing Benda-kerja dengan Prinsip 3-2-1 Klem Tunggal

Toha

Diratama

Wigenaputra

2017

jti

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“…The FEA predictions of workpiece deformationand locator reactions are experimentally verified [5].The layout of fixture including clamp and locator layout play an important role in fixture performance. Vishnuprian et al suggested fixture layout optimization by taking into consideration the effect locator errors.The study presented deterministic location ensured throughout the optimization process and minimal machining errors [6].…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Studies on Fixture-Workpiece Contact and Structural Deformations in Pocket Milling

Yadav¹,

Mohite²

2017

Proceedings of the International Conference on Communication and Signal Processing 2016 (ICCASP 2016)

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Abstract:Geometrical inaccuracies, in a statically clampedworkpiece subjected to cutting forces,aremainly caused by the contact deformationsat the locators and the structural deformations in the body of the workpiece.In addition, during machining the structural deformations continuously increase as the workpiece keeps losing its stiffness on account of metal removal. This condition is also encountered while machining thin walled workpieces. To investigate the relative significance of the structural and the contact deformations,fixture elements workpieceand the contact at their interface is modelled numerically in ANSYS 17.2.A milling fixture with 3-2-1 location principle and two hydraulically operated clamps is developed for pocket milling operation on Al-6061-T6 and a number of experiments are conducted to obtain structural deformation of workpiece. The numerical simulations and experiments were performed for different percentages of metal removal (0%, 20% and 50%) under various clamping pressures varying from 15-25 bar (kg/cm 2 ).The numerically predicted deformations show a good agreement with experimental results. The studies would help in developing an adaptive clamping mechanism to compensate for the changing structural stiffness of the workpiece and thereby keeping a check on the deformations, and hence the machining accuracies.

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“…A Genetic Algorithm (GA) based optimization method is proposed to arrive at a layout of error containing locators for minimum machining error satisfying the tolerance requirements and providing deterministic location. This may be advantageous in cases where a less strict tolerance on locator is acceptable thus reducing the cost of manufacture of locators (Vishnupriyan et al 2010)…”

Section: Introductionmentioning

confidence: 99%