Üçayaklı Ayna İle Tutulan Parçaların Üretim Sonrası Delik Profillerinin Tahmin Edilmesi

Year 2020, Volume: 41 Issue: 2, 542 - 549, 25.06.2020

Fatih Güven

https://doi.org/10.17776/csj.674764

Cited By: 1

Abstract

Üretim planlaması aşamasında delik profilinin tahmin edilebilmesi hassas imalatta doğru kesici takıma karar vermek için önemlidir. Profil tahmini, aynı zamanda üretimde ıskarta oranını da düşürülmesine yardımcı olur. Üreticiler her zaman tüm takımları elinde bulunduramazlar ve an az takımla en iyi üretimi yapmak isterler. Üçayaklı torna aynası, özellikle silindirik parçalar için, farklı boyutlardaki parçaların aynı tezgâhta işlenmesine imkân verir. Fakat üçayaklı ayna sıkıştırma sırasında parçasının şeklinin bozulmasına sebep olur. Bu çalışmada delik profilinin şekil değiştirmesi sayısal olarak incelenmiştir. Tam elastik şekil değiştirme koşullarında farklı malzeme ve cidar kalınlığına sahip parçaların boyutsal değişimi sonlu elemanlar yöntemi ile incelenmiştir. Gerilim altındaki silindiril parça üçgen bir şekil almaktadır. Malzeme ve cidar kalınlığının üçgenleşme açısından önemli değişkenler olduğu görülmüştür. Üçgenleşme sonucunda parçanın istenilen şekil toleranslarında kalıp kalmayacağını tahmin edebilmek için kalın cidarlı basınçlı kaplar teorisine dayanan basit hesaplamalar önerilmiştir. Bu kolay yöntem, seri üretimi yapılan silindirik parçaların ıskarta oranının düşürülmesine imkân vermektedir.

Keywords

Geçme, Kesme, İşleme, Hassas imalat, Tolerans

Post-op bore profile estimation of workpiece clamped using three-jaw chuck

Abstract

Estimating bore profile is important to select an appropriate tool for precision manufacturing in the process planning stage. Also, it helps in reducing the rejection rate of the process. A manufacturer might not be well-equipped and want to make their best with the resource on hand. Three-jaw chuck allows machining a wide range of workpiece, mostly circular parts in a lathe. However, clamping via a three-jaw chuck distorts the workpiece. In this study, the deformation of the bore profile was investigated numerically for circular parts. Finite element analyses were performed to examine dimensional variation for various materials and different wall thicknesses under fully elastic plane stress conditions. The stressed workpiece had a triangular form. Results showed that wall thickness and materials are important parameters on the triangulation of bore diameter. A simple calculation method based on thick-walled vessel theory was proposed to estimate the tolerance grade of the workpiece. This simple method provides the opportunity to reduce the rejection rate in the mass production of circular parts.

Keywords

Fit, Cutting, Machining, Precision, Tolerance

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