• Title/Summary/Keyword: Deep Hole Drilling

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A Study on the Characteristics of Deep Hole Drilling Process Using Single Edge Drill with Small Diameters (미소직경의 Single Edge형 드릴을 사용한 심공드릴링 공정의 가공특성에 관한 연구)

  • 최성주;이우영;박원규
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.2
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    • pp.1-8
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    • 2004
  • Applications of the deep hole drilling process can be found in many industries ranging from large aerospace manufacturer to small tool and die shop. Deep hole drilling process with small diameter generally requires high quality and accuracy. But problems which may arise or result from the deep hole drilling process include drill breakage, the generation of a finished part surface which does not satisfy required quality, and process instability. To guaranty the required machining quality and accuracy, it is important to understand and improve the deep hole drilling process. In this study, deep hole drilling experiments using tingle edge drill with small diameter under 2mm have been carried out for difficult to cut materials such as C42CrMo4 and C45pb and the experimental results were analyzed. Feed force and torque versus feed showed linear relationship in both materials. The feed force and torque are decreased as cutting speed is increased but the trends are not uniform in C42CrMo4.

A Study on the Characteristics of BTA Deep Drilling for Marine Part Carbon and Alloy Steels

  • Sim, Sung-Bo;Kim, Chi-Ok
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.3 no.1
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    • pp.40-48
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    • 2000
  • The term "deep holes" is used to describe the machining of holes with a relatively large length to diameter ratio. The main feature of BTA deep hole drilling is the stabilization of cutting force necessary for the self guidance of the drill head. An additional feature is the cutting tool edges that are unsymmetrically placed on the drill head. There is an increasing necessity to predict the hole geometry and other dynamic stability behavior of deep hole drilling guidance. In this study, the effects of BTA deep hole drilling conditions on the hole profile machined piece are analyzed using domain analysis technique. The profile of deep hole drilled work piece is related to cutting speed, feed rate, chip flow, tool wear, and so on. This study deals with the experimental results obtained during the BTA drilling on SM45C, SM55C carbon steels and SCM440 steels under various cutting conditions, and these results are compared with analytical evaluations.aluations.

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A Study on Influence of the Cutting Fluid to Machinability in Deep Hole Drilling (Deep Hole Drilling에서 절삭유가 가공성에 미치는 영향에 관한 연구)

  • 장성규;이충일;전언찬
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.1068-1072
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    • 1997
  • This work deals with on investigation the influence of various additives to a base stock cutting fluid in order to develop a better deep hold drilling. This investigation has been aiming at developing an oil which gives a maximum cutting efficiency at a minimum wear rate of the tool and the guiding pads. The purpose of study is to analyze how guide pad of tools, workpiece and the change of contained quantity of extreme pressure additive in cutting fluids have effects on the hold over size of cutting hole, surface roughness of workpiece,wear rates of guide pad and roundness during the deep hole machining of SM55C with solid BTA drill by using BTA drilling system through experiment. Conclusion reached is as follows. It has been proved that the contained quantity of surphur more affects machinability than that of extreme pressure additive of chlorine of cutting fluid in BTA drilling during Deep Hole Drilling. Considering its base oil, the the contained quantity of extreme pressure assitive of surphur can be different, but it's judged that the range of 1.5 ~ 2.0% is suitable to machinability for workpiece in BTA drilling. Regarding guide pad, it's judged that the reduction of wear is possible in propotion to the contained quantity of exrreme pressure additive of chlorine against supporting of cutting force and Bumishing operation of machining parts in cutting.

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A Study on the characteristic of micro deep hole drilling (마이크로 Deep hole 가공 특성에 관한 연구)

  • 김동우;조명우;이응숙;강재훈;민승기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.1064-1067
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    • 2001
  • Micro drilling is used in the production of fuel injection nozzle, watch, camera, air bearing and pinted circuit boards(PCB) are demanded for high precision. Recently industries of precision production require more small hole, high aspect ratio and high speed working for micro deep hole drilling. But the undesirable characteristics of micro drilling is the small signal to noise ratios, wandering motion of drill, high aspect ratio and the increase of cutting force as cutting depth increase. So in this paper to obtain the optimization of cutting condition a study on the characteristics of micro deep hole drilling used Tool dynamometer is proposed.

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A Study on Cutting Conditions of the Be-Cu Material in Micro Deep Hole Drilling Operation (미세심공드릴 가공에 있어서 Be-Cu 재료의 절삭조건에 관한 연구)

  • 김희남;유숙철;이형원;이원영;이종화;이인수
    • Journal of the Korea Safety Management & Science
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    • v.2 no.2
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    • pp.117-126
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    • 2000
  • Recently micro deep hole drilling is required in the whole industry. However, micro deep hole drilling has still much difficulty because of the lack of drill rigidity and the interruption of chip. We treated a micro deep hole(diameter 0.35mm, depth 3mm) used in a connector jack pin. Therefore, a surface roughness is very important. In this paper, we studied on the variation of the surface roughness for cutting conditions during micro deep hole drilling of Be-Cu material. Most of all, we tried to drill on CNC for the realization of automatization.

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A study on analysis of SM55C worked-shape in the BTA drilling (BTA 드릴링에 있어서 SM55C의 가공면 형상에 관한 연구)

  • 장성화
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1998.10a
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    • pp.84-89
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    • 1998
  • BTA drilling among the deep hole drilling is using for the improvement of productivity and the high-efficient working. As the deep hole drilling with BTA drill is satisfied with the required quality by one-pass processing, more deeper hole depth, the accuracy of materials is affected by bending vibration and cutting speed. This paper is studied that the shapes of material (surface roughness, roundness) is affected by cutting condition compared actual roundness with lobe shape with modeling of computer through the experiments in the BTA drilling system with BTA drill.

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Cutting force regulation of microdrilling using the sliding mode control (슬라이딩 모드 제어를 이용한 마으크로 드릴의 절삭력 제어)

  • 정만실;조동우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.842-846
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    • 1997
  • Micro-hole drilling (holes less than 0.5 mm in diameter with aspect ratios larger than 10) is gaining increased attention in a wide spectrum of precision production industries. Alternative methods such as EDM, laser drilling, etc. can sometimes replace mechanical micro-hole drilling but are not acceptable in PCB manufacture because they yield inferior hole quality and accuracy. The major difficulties in micro-hold drilling are related to wandering motions during the inlet stage, high aspect ratios, high temperature,etc. However, of all the difficulties, the most undesirable one is the increase of drilling force as the drill penetrates deeper into hold. This is caused mainly by chip related effects. Peck-drilling is thus widely used for deep hole drilling despite the fact that it leads to low productivity. Therefore, in this paper, a method of cutting force regulation is proposed to achieve continuous drilling. A proportional plus derivative (PD) and a sliding modecontrol algorithm will be implemented for controlling the spinle rotational frequeency. Experimental results will show that sliding mode control reduces the nominal cutting force and its variation better than the PD control, resulting in a number of advantages such as an increase in drill life, fast stabilization of the wandering motion, and precise positioning of the hole.

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A Study on Cutting Performance of the BTA Drilling (BTA드릴가공의 절삭성능에 관한 연구)

  • 장성규;김순경;전언찬
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.10
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    • pp.65-72
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    • 1998
  • The BTA drilling chip is better for deep hole drilling than other self-piloting with pad drilling chips because the large length to diameter ratio allows a unique cutting force dispersion and better supplies the high pressure fluid. Therefore the BTA is useful for many tasks, such as coolant hole drilling of large scale dies, as well as tube seat drilling, which is essential for the heat exchanger, and variable component drilling for automobiles. Deep hole drilling has several significant problems, such as hole deviation, hole over-size, circularity, straightness, and surface roughness. The reasons for these problems, which often result in quality short comings, are an alignment of the BTA drilling system and the unbalance of cutting force by work piece and tool shape. This paper analyzes the properties through an experiment which com¬pared single-edge BTA drills with multiple-edge BTA drills, as well as the shapes of the tools to cause an unbalance of cutting force, and its effect on the precision of the worked hole. Conclusions are as follows. 1) In SMSSC drilling, 60m/min of BTA with single and multi-edged tools proved the best cutting condition and the lowest wear character. 2) The roundness got a little worse as cutting speed was increased, but surface roughness was hot affected. 3) It was proved that the burnishing torque of both drills approached 26%. which is almost the same as the 24% insisted on by Griffiths, and the dispersion characteristic of the multi-edged BTA drill proved better than the single-edge BTA drill.

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A Study on Machinability of SM55C for Deep Hole Drilling (Deep Hole 가공시 SM55C의 절삭성에 관한 연구)

  • 장성규
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.4
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    • pp.56-63
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    • 1998
  • The purpose of this is to analyze experimentally how the change of cutting speed have effects on hole over size of cutting hole, surface roughness of workpiece and roundness during the deep hole machining of SM55C with solid BTA drill using BTA drilling system. Conclusion reached is as follows. (1) The diameter was expanded for 25$\mu$m at the first section and then was reduced 0$\mu$m and 15$\mu$m respectively at the 10m and 20m section comparing to the diameter of tool with respect to the variation of cutting length at 70m/min of cutting speed. 0.15mm/rev of feed. (2) It was proved that roughness was below 8.67$\mu$m for the whole section of cutting length. (3) The roundness has been below 12$\mu$m. Regarding the polygon phenomenon, it has been proved that not only uneven best at 70m/min of cutting speed. 0.15mm/rev of feed.

Diagnosis and Control of Machining States in Micro-Drilling for Productivity Enhancement (미세구멍 가공의 생산성 향상을 위한 상태식별 및 제어)

  • 정만실;조동우
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.1
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    • pp.117-129
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    • 1998
  • Micro-hole drilling (holes less than 0.5 mm in diameter with aspect ratio larger than 10) is recently having more attention in a wide spectrum of precision production industries. Alternative methods such as EDM. laser drilling, etc. can sometimes replace the mechanical micro-hole drilling but are not acceptable in PCB manufacture because of the inferior hole quality and accuracy. The major difficulties in micro-hole drilling are related to small signal to noise ratios, wandering motions of the inlet stage, high aspect ratios, high temperatures and so forth. Of all the difficulties. the most undesirable one is the increase of drilling force as the drill proceeds deeper into the hole. This is caused mainly from the chip effects. Peck-drilling is thus widely used for deep hole drilling despite that it suffers from low productivity. In the paper, a method of cutting force regulation is proposed to achieve continuous drilling. A PD and a sliding mode control algorithms were implemented through controlling the spindle rotating frequency. Experimental results show that the sliding mode control reduces the nominal cutting force and the variation of the cutting force better than the PD control. The advantages of the regulation, such as increase of drill life, fast stabilization of a wandering motion, and the precise positioning of the hole are verified in experiment.

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