INVESTIGATION THE MICRO HARDNESS AND MICRO STRUCTURE IN FRICTION DRILLING

Abstract

Friction drilling process is a non-traditional hole making method which a no-chip drilling process was formed by thermal friction. In this friction drilling experimental study, the selected spindle speeds were 2400rpm, 3600rpm, and 4800rpm, feed rates was 75mm/min and tool material were HSS and WC tools with 240, 360, and 480 conical angles and 24mm, tool cylindrical region lengths. The specimens were St37 and A7075–T651 alloys with thickness of 4mm and 6mm. It was analysed the effect of experimental parameters on the micro hardness and micro structure. Maximum micro hardness values were obtained at 3600rpm spindle speed, 360 and 480 conical angles the smaller micro hardness was obtained at 240 tool conical angle. in In friction drilling of St37 steel alloy higher micro hardness values were obtained than in friction drilling of A7075-T651 aluminium alloy. Because of deficient precipitation hardening of St37 steel alloy the micro hardness was not changed over.

Keywords

• Friction drilling, Micro hardness, Micro structure, Spindle speed, Conical angle,

SÜRTÜNMELİ DELMEDE MİKRO YAPI VE MİKRO SERTLİĞİN ARAŞTIRILMASI

Öz

Sürtünmeli delme, geleneksel olmayan, sürtünme sonucu oluşan ısının etkisi ile delik delme yöntemidir. Bu çalışmada, 2400d/dak, 3600d/dak ve 4800d/dak dönme hızlarında, 75mm/dak ilerleme hızında, cidar kalınlığı 4mm ve 6mm olan St 37 ve A7075–T651 alaşımlarına sürtünmeli delme yöntemiyle delikler delinmiştir. Delme esnasında koniklik açısı 240, 360 ve 480, silindirik bölge uzunluğu hl=24mm olan HSS ve WC takımlar kullanılmıştır. Elde edilen deliklerin, mikro sertlik ve mikro yapı üzerindeki etkisi araştırılmıştır. Maksimum mikro sertlik değeri 3600d/dak dönme hızında, 360 ve 480 koniklik açılarında, 240 koniklik açısında ise daha düşük değerler elde edilmiştir. St37 çelik alaşımında, A7075-T651 alüminyum alaşımına göre daha yüksek mikro sertlik değerleri elde edilmiştir. St37 çelik alaşımında çökelti sertleşmesi olmadığından mikro sertlik değerinde fazla değişiklik olmamıştır.

Anahtar Kelimeler

• Sürtünmeli Delme, Mikro sertlik, Mikro yapı, Devir sayısı, Koniklik açısı,

Kaynakça

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