Micro Cutting of Tungsten Carbides with SEM Direct Observation Method

jung, Heo-Sung The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.5

This paper describes the micro cutting of wear resistant tungsten carbides using PCD (Poly-Crystalline Diamond) cutting tools in performance with SEM (Scanning Electron Microscope) direct observation method. Turning experiments were also carried out on this alloy (V50) using a PCD cutting tool. One of the purposes of this study is to describe clearly the cutting mechanism of tungsten carbides and the behavior of WC particles in the deformation zone in orthogonal micro cutting. Other purposes are to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, machined surface and tool wear rates by the outer turning of this alloy carried out using the PCD cutting tool during these various cutting conditions. A summary of the results are as follows: (1) From the SEM direct observation in cutting the tungsten carbide, WC particles are broken and come into contact with the tool edge directly. This causes tool wear in which portions scrape the tool in a strong manner. (2) There are two chip formation types. One is where the shear angle is comparatively small and the crack of the shear plane becomes wide. The other is a type where the shear angle is above 45 degrees and the crack of the shear plane does not widen. These differences are caused by the stress condition which gives rise to the friction at the shear plane. (3) The thrust cutting forces tend to increase more rapidly than the principal forces, as the depth of cut and the cutting speed are increased preferably in the orthogonal micro cutting. (4) The tool wear on the flank face was larger than that on the rake face in the orthogonal micro cutting. (5) Three components of cutting force in the conventional turning experiments were different in balance from ordinary cutting such as the cutting of steel or cast iron. Those expressed a large value of thrust force, principal force, and feed force. (6) From the viewpoint of high efficient cutting found within this research, a proper cutting speed was 15 m/min and a proper feed rate was 0.1 mm/rev. In this case, it was found that the tool life of a PCD tool was limited to a distance of approximately 230 m. (7) When the depth of cut was 0.1 mm, there was no influence of the feed rate on the feed force. The feed force tended to decrease, as the cutting distance was long, because the tool was worn and the tool edge retreated. (8) The main tool wear of a PCD tool in this research was due to the flank wear within the maximum value of $V_{max}$ being about 260 $\mu\textrm{m}$.

선삭가공에서 단면 절삭시 공구수명에 대한 연구

金正顯 慶一大學校 2002 論文集 Vol.18 No.-

Tool life is one of the most important factors in cuttingability. Taylor's formula is useful for the tool life analysis. Reichel carried out an axial-direction cutting in order to find constants in Taylor's formula, but his approach wastes much time as well as many workpieces. Brandsma performed a radial-direction cutting for the same purpose, assuming that single-processing in the radial-direction cutting reaches the end of tool life. However, multi-processing is necessary to obtain the constants for the radial-direction cutting. In this study, for determining the constants, both axial- and radial-direction cutting are carried out. Tool wear and cutting force are also investigated experimentally.

Machining Characteristics of Cemented Carbides in Micro Cutting within SEM

Sung-Jung Heo 한국정밀공학회 2004 International Journal of Precision Engineering and Vol.5 No.3

This research describes that the cutting characteristics and tool wear behavior in the micro cutting of three kinds of wear resistant cemented carbides (WC-Co; V40, V50 and V60) using PCD (Poly Crystalline Diamond) and PCBN (Polycrystalline Cubic Boron Nitride) cutting tools by use of the SEM (Scanning Electron Microscope) direct observation method. The purpose of this research is to present reasonable cutting conditions from the viewpoint of high efficient cutting refer to a precise finished surface and tool wear. Summary of the results is as follows: (1) The cutting forces tend to increase as the increase of the weight percentage of WC particles, and the thrust forces was larger than the principal forces in the cutting of WC-Co. These phenomena were different from the ordinary cutting such as cutting of steel or cast iron. (2) The cutting speed hardly influenced the thrust force, because of the frictional force between the cutting tool edge and small WC particles at low cutting speed region such as 2㎛/s. It seemed that the thrust cutting force occurred by the contact between the flank face and work material near the cutting edge. (3) The wear mechanism for PCD tools is abrasion by hard WC particles of the work materials, which leads diamond grain to be detached from the bond. (4) From the SEM direct observation in cutting the WC-Co, it seems that WC particles are broken and come into contact with the tool edge directly. This causes tool wear, resulting in severe tool damage. (5) In the orthogonal micro cutting of WC-Co, the tool wear in the flank face was formed bigger than that in the rake face on orthogonal micro cutting. And the machining surface integrity on the side of the cutting tool with a negative rake angle was better than that with a positive one, as well as burr in the case of using the cutting tool with a negative rake angle was formed very little compared to the that with a positive one.

Machining Characteristics of Cemented Carbides in Micro Cutting within SEM

Heo, Sung-Jung Korean Society for Precision Engineering 2004 International Journal of Precision Engineering and Vol.5 No.3

This research describes that the cutting characteristics and tool wear behavior in the micro cutting of three kinds of wear resistant cemented carbides (WC-Co; V40, V50 and V60) using PCD (Poly Crystalline Diamond) and PCBN (Poly crystalline Cubic Boron Nitride) cutting tools by use of the SEM (Scanning Electron Microscope) direct observation method. The purpose of this research is to present reasonable cutting conditions from the viewpoint of high efficient cutting refer to a precise finished surface and tool wear. Summary of the results is as follows: (1) The cutting forces tend to increase as the increase of the weight percentage of WC particles, and the thrust forces was larger than the principal forces in the cutting of WC-Co. These phenomena were different from the ordinary cutting such as cutting of steel or cast iron. (2) The cutting speed hardly influenced the thrust force, because of the frictional force between the cutting tool edge and small WC particles at low cutting speed region such as 2$\mu\textrm{m}$/s. It seemed that the thrust cutting force occurred by the contact between the flank face and work material near the cutting edge. (3) The wear mechanism for PCD tools is abrasion by hard WC particles of the work materials, which leads diamond grain to be detached from the bond. (4) From the SEM direct observation in cutting the WC-Co, it seems that WC particles are broken and come into contact with the tool edge directly. This causes tool wear, resulting in severe tool damage. (5) In the orthogonal micro cutting of WC-Co, the tool wear in the flank face was formed bigger than that in the rake face on orthogonal micro cutting. And the machining surface integrity on the side of the cutting tool with a negative rake angle was better than that with a positive one, as well as burr in the case of using the cutting tool with a negative rake angle was formed very little compared to the that with a positive one.

정면밀링에서 절삭력을 이용한 절입비와 절삭력비의 실시간 추정

김명곤,권원태 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4

In this paper, presented is a method of on-line estimation of the radial immersion ratio and cutting force ratio using cut-ting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. These force drops are equal to the cutting forces that act on a single tooth at the swept angle of cut and can be obtained from cutting force signals in feed and cross-feed directions. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting forces, the radial immersion ratio is estimated along with the cutting force ratio at that immersion angle. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tan-gential direction cutting force can be estimated by the proposed method very well.

내시경점막하박리술 후 검체를 이용한 육안소견, 입체현미경소견 및 병리지도화 간의 검체 절제방향의 비교

조영관 ( Young Kwan Cho ),조주영 ( Joo Young Cho ),진소영 ( So Young Jin ),조원영 ( Won Young Cho ),정윤호 ( Yoon Ho Jung ),이태희 ( Tae Hee Lee ),김현건 ( Hyun Gun Kim ),김진오 ( Jin Oh Kim ),이준성 ( Joon Seong Lee ) 대한소화기학회 2010 대한소화기학회지 Vol.56 No.5

Background/Aims: The correct pathologic review is very important after endoscopic submucosal dissection. The cut direction of specimen should be the right angle of the closest area between the lesion and the lateral margin for the correct pathologic review. The aim of this study was to evaluate the concordance of the gross finding and stereoscopic finding compared to the pathologic mapping in the setting of the cut direction. Methods: Between December 2008 and May 2009, the objects were 48 specimens in 46 patients who were diagnosed with early gastric cancer and high grade adenoma after endoscopic submucosal dissection. The specimens were stained with hematoxylin and observed by the stereoscopy and analyzed by the image analysis system. The cut direction was divided by an angle of 45 degree based on the oral side of the specimen, and the cut directions of the gross finding, the stereoscopic finding, and the pathologic finding were compared. Results: The concordance of the gross finding in the setting of the cut direction was 68% (33/48), and the kappa value was 0.626, and the concordance of the stereoscopic finding in the setting of the cut direction was 87% (33/48), and the kappa value was 0.874. The accuracy of the gross finding was significantly lower than that of the stereoscopic finding in the setting of the cut direction (p<0.05). Conclusions: The endoscopist needs the careful observation and close attention in the setting of the cut direction of the specimen by gross finding, and stereoscopic analysis may be a useful tool for decision of the cut direction. (Korean J Gastroenterol 2010;56:293-298)

경사면에서 볼 엔드밀을 이용한 고속가공 특성

김남경,김경균 진주산업대학교 2001 산업과학기술연구소보 Vol.- No.8

The use of ball end mill is rapidly growing in die and mold manufacturing. The cutting characteristics, such as cutting force, surface roughness and surface profile, are varied according to the variation of cutting directions. Free surface is cut using ball end mill, the surface profile is greatly varied depending upon the cutting direction. So this study will deal with the characteristics of cutting such as cutting efficiency according to the inclined plane of the workpiece, the cutting force according to tool path, surface profile and the roughness of surface. The optimal cutting direction to be applied the cutting for 3-D sculptured surfaces can be show through the results of this study.

Effects of shaft angle on cutting tool parameters in internal gear skiving

Koichiro Uriu,Tsukasa Osafune,Takanori Murakami,Morimasa Nakamura,Daisuke Iba,Masami Funamoto,Ichiro Moriwaki 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12

Gear skiving has received considerable attention because of its high productivity, particularly in internal gear cutting, and skiving cutter design methods have been widely investigated. At the beginning of a cutter design process, a shaft angle, a center distance, and the number of teeth are examined as basic parameters for cutting gears. In current gear skiving, a shaft angle is generally set to be approximately 20°; however, the reason for selecting this value has not been clarified. In the present study, the validity of the value of shaft angle is discussed by calculating the cutting tool parameters, such as instantaneous rake angles, clearance angles, cut depths, and cutting speeds at continuously moving cutting points against various shaft angles. Therefore, the widely used value of shaft angle would result in moderate cutting tool parameters. In addition, the cutting force and cutter wear would be low when a cutter axis inclines opposite to the gear helix to be cut.

『法集別行錄節要竝入私記』의 경절문 一考 -無心合道門과 看話의 의미 중심으로

윤미란 보조사상연구원 2023 보조사상 Vol.65 No.-

This article was written based on the critical mind about the terms ‘The door of entering the way with no-mind’ (無心合道門) and ‘Observing the keyword’ (看話), which are terms related to ‘the path of direct cutting’ (徑截門) among the three gates buddhist practice mentioned in the inscription of Chinul (知訥). First, I raised a counterargument to some of the arguments that saw the ‘The door of entering the way with no-mind’ as another practice approach that Chinul opened. It was revealed that such a argument was based on a contextual misreading according to the composition of the original text, and that ‘The door of entering the way with no-mind’ was written to clarify the superiority of Seon Buddhism in the process of citing Qingliang Chengguan's (淸凉澄觀) writings to explain Zongmi(780-841)'s theory of sudden enlightenment and gradual cultivation in detail and to help scholars understand Seon Buddhism properly. In addition, through thorough reading of the original text of Excerpts from the Dharma Collection and Special Practice Record with Personal Notes, the meaning of the term ‘Observing the Keyword’ written by Chinul was identified. In other words, based on the various episodes quoted in the path of direct cutting section of Excerpts from the Dharma Collection and Special Practice Record with Personal Notes, especially the episodes of the Platform Sūtra of the Sixth Patriarch (六祖壇經) cited before citing Zen Analects of Ta-hui (大慧語錄), the structure of the Kanhwa practice approach that Chinul must have had was drawn, and the relationship with Ta-hui (大慧)’s Kanhwa Sŏn was also reviewed. Although Chinul’s Kanhwa practice approach actively borrowed the part of Ta-hui (大慧)’s Kanhwa Sŏn that talks about ‘the ten illnesses of the Investigation of (the Hwadu word of) Mu’ (無字話頭十種病), it was revealed that the equation of ‘The path of direct cutting = Ta-hui Sŏn’ should be reexamined. Through this, it was suggested that when ‘the path of direct cutting’ is named ‘Kanhwakyo˘ngjo˘l mun’ (看話徑截門) and used, the nature of the Kanhwa Sŏn should allocate a large share to the Kanhwa practice approach established by Chinul.

방향성 소구경 굴착의 입자 이송특성에 관한 연구

한상목(Sang-Mok Han),김정환(Jeong-Hwan Kim),황영규(Young-Kyu Hwang),우남섭(Nam-Sub Woo),김영주(Young-Ju Kim) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.2

During drilling, the precipitation velocity of cuttings within an annulus depends on the density and configuration of the cuttings, and on the density, viscosity, and rheological characteristics of the drilling fluid. In directional drilling in particular, it is difficult to adjust and control the cuttings. In contrast to vertical drilling, it is very important to evaluate the flow characteristics of a drilling flow field. However, research on the transfer features of cuttings is inadequate. In this study, in order to identify transfer features of cuttings, an experiment was performed under wide-ranging conditions by constructing a slim hole annulus (44 ㎜×30 ㎜) device. In this experiment, the particle volume fraction were influenced by particle size, particle concentration within the flow, pipe rotation, flow volume, and inclination of the annulus. In addition, a mathematical formula for volumetric concentration was deduced and compared to the test results and behavior of cuttings under the other drilling condition was made to be predicted. Therefore, this study can provide meaningful data for vertical and horizontal drilling, and for directional drilling.