m. j. nategh

Hard to cut materials such as hardened steel and super alloys are well known and popular in transportation, aerospace, marine and medical industries, due to their strength, high corrosion and fatigue resistance and high working temperature . However, their lowmachinability is one of the major problems in using them. In this article we examine machinability of the hardened CK45 steel in four processes including; conventional turning, hot turning, ultrasonic assisted turning and hot ultrasonic assisted turning as a hybrid machining. The results of these four processes are compared with each other. The heating technique is induction type which has much lower construction cost compared to other techniques such as laser beam and plasma arc. It has been illustrated in the present study that combining the heating technique with ultrasonic vibration has the most effect in improving surface quality and reducing cutting forces compared to other turning process. The chip formation under the heat and ultrasonic vibration and its influence on the surface quality have also shown that hybrid process has the most affection.

In this paper, the contents of Heron’s treatise and the Persian manuscripts on lifting heavy weights have been investigated as a means to make preparations for comparing the Persian manuscripts to each other and to Heron’s treatise, and to evaluate the originality of the Persian manuscripts. The somewhat 22 manuscripts preserved in various libraries in Iran have been written during the 9AH/15AD to 13AH/19AD centuries. They have not yet been investigated. Some of them are attributed to Ibn Sīnā and some others to Ḥazīn Lāhījī. Abū Alī bin ʻabd al-Jalīl Khārazmī has also been named as an author. In the present paper it would be verified that these manuscripts are not independent from each other and can neither be attributed to Ibn Sīnā and Ḥazīn Lāhījī. The contents of these manuscripts are comparable to the second book of Heron’s treatise but independent of it.