• 한국기계가공학회지
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• 제11권3호
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• pp.29-34
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• 2012

This paper reports some experimental results in high speed rigid tapping of magnesium alloy(AZ91D). M3 spiral tap and high speed spindle tapping center of gantry type were used in experiments and thrust forces were measured. The experimental results indicate that the thrust forces are proportional to the spindle speed and depth of cut. The thrust forces increase as the depth of cut increases. M3 Tapping was achieved at the spindle speed of 10,000rpm, depth of cut of 1.5D and total stroke of 32mm.

• 대한기계학회논문집
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• 제18권12호
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• pp.3195-3201
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• 1994

In order to analytically predict tapping torque and thrust force in high speed tapping, a cutting model for main cutting edge with a uniformly restricted tool-chip contact area were developed. From this model equations are derived for the prediction of tapping torque given the cutting conditions, tap geometry, and an empirical factor which is related to the workmaterial. Computed values of torque is shown to compare favorably with those obtained from tapping tests on 16MnCr5. The applied torque about the cutting edge of teeth at lead chamfer is estimated respectively and it is shown that observed value is gradually decreased with following teeth.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.243-246
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• 2000

Productivty of tapping has been increasing through the tcchnological advances in synchronization between spindle rotation and feed motion even in the high spindle speed. However, not much researches have been conducted about tapping process because its complicate cutting mechanism. In order ta investigate the characteristics of the tapping process, this paper concentrates on the analysis of curting torque behavior during one cycle of lapping. As one completc thread is performed through the whole chamfer ercuttlng, cutting torque increases highly in chamfer cutting, but smaothly in full thread cutting Functioning of the threads guide. Cutting torque in backward cutting is smaller than in Sorwerd cutting due to only friction farce in against between the tool and workpiece. And torque behavior of a periodic Sine ripple-mark was identified during one revolution of a tap.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.315-318
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• 1997

In terms of productivity, the speed of machining process has been increasing in most of engineering part. But the tapping process does not reach at enough level compared with other machining processes because of its complicate cutting mechanism. In the high speed tapping process, the one of important elements is tool monitoring system to prevent tool breakage. This paper describes tool monitoring system by acoustic emission(AE) in the tapping process. We used 2 types of AE sensors in this test. The one is commercial sensor which is used in other machining monitoring system like polishing and the other is a self-fabricated sensor for this test. In this test we purpose to find out the frequency of AE signal in tapping process and verify the possibility of applying AE sensor in in-process tapping monitoring system. Also grasp of characteristic of tapping process by AE signal is handled.

• 한국정밀공학회지
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• 제18권11호
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• pp.67-73
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• 2001

This paper aims at developing a torque model for the high-speed tapping with small-diameter taps. As recent industries such as automobile and information technology grows, taps smaller than 5mm in diameter are needed much more. In that occasion, the friction force between a tap surface and a workpiece plays much more important role in the tapping torque than in he larger tapping. Tapping mechanism was analysed based on the tap geometry. It has two steps : one is a forward cutting composed of the chamfered threading and full threading and the other is the backward cutting. The torque by the cutting force in the chamfered threading is calculated using the cutting area and the specific cutting force while the torque by the friction force, which is rather dominant than the cutting force both in the full threading and in the backward cutting, is calculated using the normal force on the threads and the friction coefficient. The experiment has shown that the results by the proposed torque model fit quite well with the acutal measurements within the error of 10%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.304-307
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• 2002

High speed machining was accomplished. through the technological advances which covers the whole field of mechanical industry. But tapping have many troubles because of its complicate cutting mechanism, for example. tool damage, chip elimination and synchronization between spindle rotation and feed motion. But High speed tapping is so important that it marches in step with the flow of the times and make improvement in the productivity. In this paper we analyze mechanism of high speed synchronized tapping with the signal of tapping torque and spindle speed obtained through the newly developed high speed tapping machine(NTT-30B). We made an experiment with this machine on condition of various speed from 1000rpm to 10000rpm. As one complete thread is performed through the whole chamfer cutting, cutting torque increases highly in chamfer cutting, but smoothly in full thread cutting functioning of the threads guide. And the size of cutting torque according to spindle speed(rpm) was not enough of a difference to be conspicuous.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.369-372
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• 2002

In this research, a vision system for detecting tool breakage which is hardly detected by such indirect in-process measurement method as acoustic emission, cutting torque and motor current was developed and embedded into a PC-NC system. The vision system consists of CMOS image sensors, a slit beam laser generator and an image grabber board. Slit beam laser was emitted on the tool surface to separate the tool geometry well from the various obstacles surrounding the tool. An image of tool is captured through two steps of signal processing, that is, median filtering and thresholding and then the tool is estimated normal or broken by use of change of the centroid of the captured image. An air curtain made by the jetting high-pressure air in front of the lens was devised to prevent the vision system from being contaminated by scattered coolant, cutting chips in cutting process. To embed the vision system to a Siemens PC-NC controller 840D NC, an HMI(Human Machine Interface) program was developed under the Windows 95 operating system of MMC103. The developed HMI is placed in a sub window of the main window of 840D and this program can be activated or deactivated either by a soft key on the operating panel or M codes in the NC part program. As the tool breakage is detected, the HMI program emit a command for automatic tool change or send alarm to the NC kernel. Evaluation test in a high speed tapping center showed the developed system was successful in detection of the small-radius tool breakage.

• 대한기계학회논문집A
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• 제39권4호
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• pp.375-382
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• 2015

이음새 없는 용기의 돔(Dome) 및 넥크(Neck) 부분 성형을 위해 일반적으로 열간 스피닝 공정이 이용되나, 대부분 현장 작업자들의 경험이나 시행착오에 의해 제작되고 있다. 이로 인하여 열간 스피닝 공정 시, 용기 넥크 부위의 저부부터 상부까지 내경이 동일한 성형을 요구하지만, 고속회전하는 롤러의 이동에 의하여 재료가 성형되는 스피닝 공정의 특성상, 돔 부분의 끝단부인 넥크 부위에서 내경이 벌어지는 형상오차의 문제가 발생한다. 이에 본 연구에서는 스피닝 가공 후, 탭핑 공정을 위하여 이종재료(Cr-13)가 보충된 나사산 모델에 대하여 이론적 해석 및 유한 요소 해석을 수행한 후, 해석결과를 토대로 작동환경하에서 용기의 구조안전성을 검증하였다.