Mechanistic Modeling for Predicting Cutting Forces in End-milling Operations with Cylindrical Flat-End and Ball-End Milling Cutters

Abstract

Milling forces affect tool life, dimensional accuracy, surface topography and cutting temperature in the machining process. Further, the prediction of milling forces is very important for designing cutting tools and machine tools. The mechanistic approach is commonly employed for the prediction of milling forces. In this study, a mechanistic model was presented to predict the cutting forces in end milling operations. The end milling operation was considered for two different cutting tools, namely cylindrical flat and ball-end milling cutters. A number of analyses were performed on AISI 1045 steel at different feed rates (0,06 and 0,09 mm/tooth) and tool rake angles (6 and 10) by keeping the cutting speed constant at 100 m/min. The effectiveness of the mechanistic model was demonstrated by comparing the predictions with experimentally obtained forces during cylindrical flat-end milling. While the mechanistic model predicted the feed force with an average error of 3,64%, a larger prediction error of 6,09% was observed for the normal force. In addition to verification of the cutting force model, a simulation study was conducted to examine the influences of feed rate and cutting tool rake angle on cutting forces during ball-end milling operation. In simulations performed using a tool with a positive rake angle of 6, increasing the feed rate from 0,06 to 0,09 mm/tooth caused the feed and normal force amplitudes to increase by approximately 30%. When the tool rake angle was changed from 6 to 10 at feed rate of 0,06 mm/tooth, the increase in cutting forces was around 45%. Consequently, the tool rake angle should be adjusted at 6 to reduce energy consumption.

Keywords

• End milling cutters
• Cutting forces
• Mechanistic modeling
• Simulation

Silindirik Düz ve Küresel Uçlu Takımlarla Parmak Frezeleme Operasyonlarında Kesme Kuvvetlerinin Tahmini İçin Mekanistik Modelleme

Öz

Frezeleme kuvvetleri, işleme sürecinde takım ömrünü, boyut doğruluğunu, yüzey topografyasını ve kesme sıcaklığını etkilemektedir. Ayrıca, kesici takımların ve takım tezgahlarının tasarımı için frezeleme kuvvetlerinin tahmin edilmesi çok önemlidir. Frezeleme kuvvetlerinin tahmini için genellikle mekanistik yaklaşım kullanılmaktadır. Bu çalışmada, parmak frezeleme operasyonlarında kesme kuvvetlerini tahmin etmek için mekanistik model sunulmuştur. Parmak frezeleme operasyonu silindirik düz ve küresel uçlu iki farklı kesici takım için ele alınmıştır. Kesme hızı 100 m/dak’da sabit tutularak farklı ilerleme hızlarında (0,06 ve 0,09 mm/diş) ve takım talaş açılarında (6 ve 10) AISI 1045 çeliği üzerinde bir dizi analiz gerçekleştirilmiştir. Mekanistik modelin etkinliği, silindirik düz uçlu takımla frezeleme sırasında deneysel olarak elde edilen kuvvetlerle tahminlerin karşılaştırılması ile ortaya konmuştur. Mekanistik model ilerleme kuvvetini %3,64’lük ortalama hatayla tahmin ederken, normal kuvvet için %6,09’luk daha büyük bir tahmin hatası gözlemlenmiştir. Kesme kuvveti modelinin doğrulanmasına ek olarak, küresel uçlu takımla frezeleme işlemi sırasında ilerleme hızı ve kesici takım talaş açısının kesme kuvvetleri üzerindeki etkilerini incelemek amacıyla bir simülasyon çalışması yürütülmüştür. 6 pozitif talaş açısına sahip takım kullanılarak yapılan simülasyonlarda ilerleme hızının 0,06 mm/diş’ten 0,09 mm/diş’e artırılması ilerleme ve normal kuvvet genliklerinin yaklaşık %30 artmasına neden olmuştur. 0,06 mm/diş ilerleme hızında takım talaş açısı 6’den 10’ye değiştirildiğinde kesme kuvvetlerindeki artış %45 civarındadır. Sonuç olarak, enerji tüketimini azaltmak için takım talaş açısı 6 olarak ayarlanmalıdır.

Anahtar Kelimeler

• Parmak frezeler
• Kesme kuvvetleri
• Mekanistik modelleme
• Simülasyon

Kaynakça

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