• 한국정밀공학회지
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• 제24권10호
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• pp.37-45
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• 2007

End-milling is intermittent cutting process performed by a tool with a number of teeth. Its cutting forces are commonly measured by the tool dynamometer which has rectangular coordinates. In this case, the pattern of cutting forces is different according to cutting conditions. At a certain cutting condition, the sign of cutting force changes from positive to negative during a revolution of one tooth. The change of force direction excites a cutting tool and severe vibration arises when radial depth of cut increases. In this study, cutting experiments and simulations were carried out in order to explain the cause of the change of the cutting force direction. In addition, the effect of the cutting force change was discussed in terms of chatter vibration in end milling.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.23-27
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• 1992

종래부터 공작기계의 성능은 그 공작기계가 발휘하는 가공정도와 가공능률이라고 하는 막연한 개념으로 취급되어 왔으나, 최근 가공정도나 가공능률을 저해하는 제현상, 예를 들면 채터나 열변형 등에 관한 정력적인 연구가 진행되면서 이들이 발생기구가 명확히 됨과 동시에 이들 제현상의 발생한계로부터 가공성능을 정량적으로 평가 해왔다. 그러나 연구보고라는 말의 성격상 연구의 대부분이 특정 현상이나 요소에 대하여 기술한 것이기 때문에 제 현상을 총괄하여 공작기계의 성능을 체계화한 것이라고볼 수는 없다. 여기서 공작물의 물림조건에서 발생 되고 있는 여러가지 문제점 중에서 척킹(chucking)된 공작물의 물림강성이 채터 진동의안정한계, 즉 가공한계에 미치는 영향에 대해서는 선삭가공에서 척 가공방식이 일반적으로 널리사용되고 있다는 점을 감안할 때 매우 중요한 과제이다. 그 중에서도 척에 물린 공작물의 경우에는 절삭저항의 작용위치와 죠의상대적인 위치에 의한 공작물 강성의 변화가 가공정도에 커다란 영향을 미친다는 것이 오래 전부터 지적되고있느 사항 중의 하나이다. 따라서 척-공작물계의 동적인 특성이 절삭현상에 미치는 영향에 대하여 동적인 관점에서 검토할 필요가 있다.

• 한국생산제조학회지
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• 제6권3호
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• pp.103-110
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• 1997

This study provides the useful actual data instead of the experience data using in industrial fields. Especially, values of each components of cutting force are effective in the rake angle, setting angle and cutting area. Many researches have been made on the work piece materials, kinds of bite materials, rake angle, nose radius and depth of cut, but a few on the bite setting angle. In order to select optimal cutting speed, it was summarized the following results are achieved; A chieved that an affect of cutting resistance on the setting angle is a little under giving experimental conditions and therefore a worker can be choose the value of it randomly.

• 한국기계가공학회지
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• 제11권6호
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• pp.88-93
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• 2012

In this study, Machining fine shaft was examined by Lathe. method is proposed to control the thrust force to 0. through relationship between the cutting depth and the thrust force in turning, fine-shaft of less than 0.1mm diameter in turning is confirmed experimentally. also we propose practical expression to control thrust force in turning Through to change the approach angle, optimal tool design would be possible in turning.

• 한국공작기계학회논문집
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• 제10권5호
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• pp.39-44
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• 2001

In this paper, drill fred mechanism, cutting depth measuring device and sensing buzzer of drill contact were investigated in order to develop the micro-hole drilling machine. Also, measuring device of cutting resistance was developed in order to estimate cutting resistance from change of cutting condition. The results show that extremely-low fled rate(less then $17{\mu}m/S$${\mu}{\textrm}{m}$ /s) can be done and cutting depth can be measured by up to 1${\mu}{\textrm}{m}$ with developed drilling machine. Accordingly we could assemble a very cheap micro-hole drilling machine($\phi$ 0.05~0.5 mm). Also we got the some properties of cutting performance i.e. under the same condition, cutting torque decreases as increase of spindle speed and rapid fled of drill brings about the inferior cutting state under low spindle speed.

• 한국생산제조학회지
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• 제18권5호
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• pp.469-476
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• 2009

Hard facing overlay welding in high chromium carbide is a representative way of extending the fatigue life or recompensing damage, because workpiece surface is uniformly overlay-welded by alloy material. In general, grinding process is currently used for finish due to hardness of weld material. The development of tool material, such as PCBN, has made it possible to use turning instead of grinding. There are many advantages of hard Owning, as lower equipment costs, shorter setup time, fewer process steps, higher material removal rate, better surface integrity and the elimination of cutting fluid. In this paper, machining characteristics and cutting performance are examined to investigate turning possibility of overly welding in high chromium carbide.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.18-24
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• 1999

ThisPaper investigates the feasibility of using acoustic emission signal analysis for the detection of built-up edge during machining. Experiments were conducted on a CNC-lathe using conventional carbide insert tools under various cutting conditions. The cutting forces were also measured for comparisons. Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. It is shown that under conditions in which a built-up edge is generated, the variation of $AE_{rms}$ signal with cutting speed can be quite different from the generally accepted linear, monotonic increase as previously reported. The feasibility of utilizing $AE_{rms}$ in built-up edge sensing is suggested.

• 한국생산제조학회지
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• 제22권1호
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• pp.85-91
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• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.

• 대한기계학회논문집
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• 제11권1호
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• pp.74-81
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• 1987

본 논문에서는 구상흑연주철을 어니일링하여 퍼라이트기지와 페라이트기지의 양을 조정하므로서 절삭성이 어느 정도 향상되는가를 실험검토하였다. 제일보에서는 퍼라이트기지가 페라이트기지로 변화할 때에 절삭비, 전단각 및 절삭저항에 어떠한 영 향을 주는가를 검토하였고, 본보에서는 기지조직의 변화가 전단응력 및 절삭에너지에 미치는 영향을 검토하였으며 각조직에 대한 절삭방정식과 절삭정수를 결정하였다.

• 한국기계가공학회지
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• 제13권2호
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• pp.108-116
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• 2014

Considering the run-out effect and cutting force coefficients, the cutting force profile of half immersion end-milling was analyzed in detail. The effects of three specific cutting-force coefficients and three edge-force coefficients are verified. Through a detailed investigation, it is proved that the radial cutting force coefficients and are the major factors which increase the cutting forces Fx and Fy in end-milling. However, the axial cutting force coefficients have no influence on the force Fx and Fy changes in end-milling. Also, the analyzed end-milling force model shows good consistency with the actual measured force with regard to Fx and Fy. Thus, this model can be used for the prediction of the force history in end-milling with run-out, and it incurs a different force history with different start and exit immersion angles as well as holding effects.