مقالات مهندسی مکانیک - ساخت و تولید

The effect of tool geometry and cutting speed on main cutting force and tool tip temperature

Haci Saglama, Suleyman Yaldiz, a,  and Faruk Unsacara

aMechanical Department, Technical Science College, Selcuk University, Konya, Turkey

Received 9 December 2004;  accepted 25 May 2005.  Available online 11 July 2005.

Abstract
In this paper, the effects of rake angle and entering angle in tool geometry and cutting speed on cutting force components and the temperature generated on the tool tip in turning were investigated. The data used for the investigation derived from experiments conducted on a CNC lathe according to the full factorial design to observe the effect of each factor level on the process performance. As the experiments were designed using an orthogonal arrays, the estimates of the average effects will not be biased. During the tests, the depth of cut and feedrate were kept constant and each test was conducted with a sharp uncoated tool insert. For a comparison, the main cutting force and the temperature generated in secondary shear zone for different cutting parameters and tool geometries were calculated by Kienzle approach and with based on orthogonal cutting mechanism, respectively. The average deviation between measured and calculated force results were found as 0.26%. For statistical analyze the orthogonal arrays L16 was used with a total of 16 tests. Finally, it was found that rake angle was effective on all the cutting force components, while cutting speed was effective on the tool tip temperature. The cutting force signals and temperature values provided extensive data to analyse the orthogonal cutting process.

Force measurement in metal cutting is an essential requirement as it is related to machine part design, tool design, power consumptions, vibrations, part accuracy, etc. It is the purpose of the measurement of cutting force to be able to understand the cutting mechanism such as the effects of cutting variables on the cutting force, the machinability of the work piece, the process of chip formation, chatter and tool wear [1]. For over 100 years, metal-cutting researches attempting to understand the cutting behaviour better have investigated the cutting forces in metal cutting. It has been observed that the force values obtained by engineering calculations contain some errors compared to experimental measurements. Since the undeformed chip thickness and the direction of cutting speed vary at every moment, cutting process in milling is geometrically complex. Owing to such complexity, the cutting forces even in steady-state conditions is affected by many parameters and the variation of cutting force with time has a peculiar characteristic [2]. The need for measurement of all cutting force component arises from many factors, but probably the most important is the need for correlation with the progress of tool wear [3]. If this can be obtained, it will be possible to achieve tool wear monitoring in milling based on force variation. Another reason for the cutting forces measurement is that it is a good indicator in detecting tool wear. It is well known that during the cutting process, the cutting parameters such as cutting speed, feed rate and depth of cut often present a deviation from the calculated values. In a three-dimensional cutting operation, three force components are necessary, whereas while drilling or tapping, only a torque and thrust drill are required [4].

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