• Title/Summary/Keyword: High speed milling

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A Study on the Particle Embedding Phenomena on Machined Surface according to Cutting Fluid in End Milling (절삭유 필터링에 따른 엔드밀 가공면 입자 임베딩 현상에 관한 연구)

  • Kim, Jeon-Ha;Hong, Tae-Yong;Lee, Jong-Hwan;Kang, Myung-Chang;Kim, Jeong-Suk
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.4 no.3
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    • pp.39-44
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    • 2005
  • With the development of high speed and accuracy machining, the micro-chips are formed in the machining process and broken particles are circulated with the cutting fluid. The surface roughness and accuracy of part are deteriorated because the metal particles included in the cutting fluid are embedded on machined surface. In this study, the influences of particles for the machined surface according to filtering degrees are evaluated and the embedding mechanism is suggested.

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A study on the Wear Estimation of End Mill Using Sound Frequency Analysis (음향주파수 분석에 의한 엔드밀의 마모상태 추정에 관한 연구)

  • Cho Taik Dong;Lee Chang hee;Sohn Jang Young
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.209-212
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    • 2002
  • The wear process of end mill is a so complicated process that a more reliable technique is required for the monitoring and controling the tool life and its performance. This research presents a new tool wear monitoring method based on the sound signal generated on the machining. The experiment carried out continuous-side-milling for 4 cases using the high-speed steel slot drill under wet condition. The sound pressure was measured at 0.5m from the cutting zone by a dynamic microphone, and was analyzed at frequency domain. The tooth passing frequency appears as a harmonics form, and end mill wear is related with the first harmonic. It can be concluded from the result that the tool wear is correlate with the intensity of the measured sound at tooth passing frequency estimation of end mill wear using sound is possible through frequency analysis at tooth passing frequency under the given circumstances.

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Analysis of Moving Heat Source for Laser Assisted Machining of Plate by Feed Rate Control (이송속도 조절에 의한 평판 레이저 보조가공의 이동 열원해석)

  • Kim, Kwang-Sun;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.12
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    • pp.1341-1346
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    • 2011
  • Currently, many researches are carried out for laser assisted machining, which is one of the important fields in materials difficult to process. However, a prediction of heat source is difficult because of moving heat source. In this paper, a thermal analysis of laser assisted machining of plate by change of heat source size is performed, and preheating temperature by adjusting the feed rate is controlled. It was recognized that the maximum preheating temperature increases according to the decrease in heat source size, and feed rate need to adjust as high speed. The results of this analysis can be used as a reference for preheating temperature prediction in laser assisted milling.

Physicochemical Properties of High Yielding Non-waxy Rice Flours Extruded with Different Moisture Contents (다른 수분함량으로 압출성형한 다수확 멥쌀가루의 이화학적 특성)

  • Jeong, So-Hee;Kang, Wie-Soo;Shin, Mal-Shick
    • Korean journal of food and cookery science
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    • v.27 no.6
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    • pp.745-754
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    • 2011
  • To improve the textural properties of gluten free rice flour based products, the physicochemical and pasting properties of extruded non-waxy rice flours using extruder were investigated. The high yielding Tongil type rice variety, Hanarum was used. Hanarum rice flour was prepared by dry milling from soaked and dried rice grain. The operation conditions of twin screw extruder were 250 rpm of screw speed, $160^{\circ}C$ of barrel temperature, and 24, 27, and 30% of moisture content. Hanarum extruded rice flour (HERF) were lower in crude lipid and ash contents, but higher in crude protein than Hanarum rice flour (HRF). The color values of HERF showed significantly different (p<0.05) with different moisture contents. Water binding capacities, apparent amylose contents, and damaged starch of HERF were higher than those of HRF. Moisture contents affected water binding capacities of HERF. Solubility increased with increasing heating temperature and solubilities of HERF differed significantly (p<0.05). X-ray crystallinity was changed after extrusion cooking and that of HERF showed sharp peaks at $2{\theta}=18-20^{\circ}$. The pasting viscosities of HERF kept lower values (~ 10 RVU) constantly.

Dry Fine Grinding of Rice Husk Ash using a Stirred Ball Mill (교반 볼밀을 이용한 왕겨재의 건식 미세분쇄에 관한 연구)

  • 박승제;최연규;김명호;이종호
    • Journal of Biosystems Engineering
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    • v.25 no.1
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    • pp.39-46
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    • 2000
  • This work was conducted to study the operating characteristics of a grinding system designed to obtain fine rice husk ash powder. To find better utilizing of rice husk, a valuable by-product from rice production, once the rice husk was incinerated and the thermal energy was recovered from the furnace, the ash was fed and pulverized in the grinding system resulting a fine powder to be used as a supplementary adding material to the portland cement manufacturing . The rice husk ash grinding system consisted of a high speed centrifugal fan for the preliminary coarse milling and a dry-type stirred ball mill for the subsequent fine grinding . Total grinding time 9 5, 15, 30, 45 min), impeller speed (250, 500, 750 rpm) , and mixed ratio (4.8, 7.9, 14.9) were three operating factors examined for the performance of a stirred ball mill used for the fine grinding of ash. With the stirred ball mill used in this study, the minimum attianable mean diameter of rice husk ash powder appeared to be 2 ${\mu}{\textrm}{m}$. During the find grinding, the difference in specific surface area of powder showed an increase and the grinding energy efficiency decreased with the increase in total grinding time, impeller speed ,and mixed ratio. For the operating conditions employed , the resulting mean diameter of fine ash powder, specific energy input, and grinding energy efficiency were in the range of 1.79 --16.04${\mu}{\textrm}{m}$, 0.072-5.226kWh/kg, an d1.11-12.15$m^2$/Wh, respectively. Grinding time of 30 min , impeller speed of 750 rpm, and mixed ratio of 4.8 were chosen as the best operating conditions of the stirred ball mill for fine grinding . At these conditions, mean particle diameter of the fine ash, grinding energy efficiency, grinding throughtput, and specific energy input were 2.73${\mu}{\textrm}{m}$, 3.95$m^2$/Wh, 0.25kg/h, and 1.22kWh/kg, respectively.

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Gap Control Using Discharge Pulse Counting in Micro-EDM (미세 방전 가공에서의 방전 펄스 카운팅을 이용한 간극 제어)

  • Jung J.W.;Ko S.H.;Jeong Y.H.;Min B.K.;Lee S.J.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.499-500
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    • 2006
  • The electrode wear in micro-EDM significantly deteriorates the machining accuracy. In this regard, electrode wear needs to be compensated in-process to improve the product quality. Therefore, there are substantial amount of research about electrode wear. In this study a control method for micro-EDM using discharge pulse counting is proposed. The method is based on the assumption that the removed workpiece volume is proportional to the number of discharge pulses, which is verified from experimental results analyzing geometrically machined volume according to various number of discharges. Especially, the method has an advantage that electrode wear does not need to be concerned. The proposed method is implemented to an actual micro-EDM system using high speed data acquisition board, simple counting algorithm with 3 axis motion system. As a result, it is demonstrated that the volume of hole machined by EDM drilling can be accurately estimated using the number of discharge pulses. In EDM milling process a micro groove without depth variation caused by electrode wear could be machined using the developed control method. Consequently, it is shown that machining accuracy in drilling and milling processes can be improved by using process control based on the number of discharge pulses.

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Analyses of structural dynamic characteristics and end milling in a vertical machining center (금형 가공기의 엔드밀 가공 및 구조 동특성 해석)

  • 이신영;김성걸;이장무
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.3
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    • pp.66-74
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    • 1997
  • In a high speed and high precision vertical machining center, chatter vibration is easily generated due to unbalanced masses in rotating parts and changtes of cutting forces. In this paper, modal test is performed to obtain modal parameters of the vertical machining center. In order to predit the cutting force of endmilling process for various cutting conditions, a mathematical model is given and this model is based on chip load, cutting geometry, and relationship between cutting forces and the chip load. Specific cutting constants of the model are obtained by averaging forces of cutting tests. The interactions between the dy- namic characteristics and cutting dynamics of the vertical machining center make the primary and the secondary feedback loops, and we make use of the equations of system to predict the chatter vibration. The chatter prediction is formulated as linear differential-differene equations, and simulated for several cases. Trends of vibration as radial and axial depths of cut are changed are shown and compared.

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The Characterization of Nano-Nickel Catalyst with High Activity by Mechanochemical (MC) Method I. Microstructure of MA Ni-50wt% Al and Preparation of Nano-Ni (기계.화학적 방법으로 제조된 고활성 나노-니켈 촉매의 특성 I. MA된 Ni-50wt% Al 합금의 미세구조 및 나노 촉매 제조)

  • Lee, Chang-Rae;Choe, Jae-Ung;Gang, Seong-Gun
    • Korean Journal of Materials Research
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    • v.9 no.6
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    • pp.615-621
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    • 1999
  • The new process in order to fabricate of Ni catalyst with high activity by the mechanochemical(MC) method which was combined the mechanical alloying(MA) and the chemical treatment process. The microstructure and characterization of mechanically alloyed Ni-5-wt% Al powder and Ni catalyst gained by alkali leaching were investigated byt he various analysis such as XRD, SEM-EDS, HRTEM and laser particle analyzer. The steady state powder with 1~2$\mu\textrm{m}$ mean particle size was obtained after 30hr milling with the PCA of 2 wt% stearic acid under the condition of grinding stainless steel ball to powder ratio of 60:1 and rotating speed fo 300rpm. According to result of HRTEM diffraction pattern, MA powder of the steady state was nanocrystalline $Al_3$$Ni_2$ intermetallic compound. Ni catalyst was obtained after KOH leaching of the steady state powder was about 20nm nanocrystalline which contained about 8 wt % Al.

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Synthesis of thermoelectric Mg3Sb2 by melting and mechanical alloying (용융법과 기계적 합금화에 의한 열전재료 Mg3Sb2의 제조)

  • Kim, In-Ki
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.4
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    • pp.207-212
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    • 2012
  • A single phase $Mg_3Sb_2$ alloy was synthesized by melting the mixture of Mg and Sb metal powders at 1173 K. The figure of merit of the $Mg_3Sb_2$ prepared by melting method increased with temperature and showed a value of $2.39{\times}10^{-2}$ at 593 K. When the $Mg_3Sb_2$ powders were milled at high speed in a planetary ball mill for 12~48 h, Zintle phase ($Mg_3Sb_2$) was maintained as a main phase, but its crystallinity became deteriorated and elemental Sb phase appeared. Sb phase free $Mg_3Sb_2$ could be obtained by the mechanical alloying of high speed ball milling for 24 h using elemental Mg and Sb powder mixtures.

Technologies to Realize High Stiffness Mechatronics Systems in Production Machines (기계장비의 메카트로닉스 고강성화 기술)

  • Lee, Chan-Hong;Song, Chang Kyu;Kim, Byung-Sub;Kim, Chang-Ju;Heo, Segon
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.5
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    • pp.431-439
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    • 2015
  • One of common challenges in designing modern production machines is realizing high speed motion without sacrificing accuracy. To address this challenge it is necessary to maximize the stiffness of the mechanical structure and the control system with consideration on the main disturbance input, cutting forces. This paper presents analysis technologies for realizing high stiffness in production machines. First, CAE analysis techniques to evaluate the dynamic stiffness of a machine structure and a new method to construct the physical machine model for servo controller simulations are demonstrated. Second, cutting forces generated in milling processes are analyzed to evaluate their effects on the mechatronics system. In the effort to investigate the interaction among the structure, controller, and process, a flexible multi-body dynamics simulation method is implemented on a magnetic bearing stage as an example. The presented technologies can provide better understandings on the mechatronics system and help realizing high stiffness production machines.