摘要
为了解决非导电工程陶瓷的高效精密加工问题,综合考虑电火花加工和机械磨削的优点,创造性地提出了非导电工程陶瓷双电极同步伺服电火花机械复合磨削新工艺。其原理就是加工时导电磨轮与薄片电极分别与脉冲电源的正、负极相连,薄片电极在伺服机构的带动下紧贴工件表面向磨轮作伺服送进,使薄片电极的前端与磨轮紧贴工件表面形成火花放电通道,由放电通道产生的瞬时高温、高压等作用来蚀除工件,同时在工件上形成一层变质层,该变质层由磨轮的机械磨削作用去除。该加工技术具有生产率高、成本低、对环境无污染等优点。
设计出了非导电工程陶瓷双电极同步伺服电火花磨削机床,详细介绍了薄片电极伺服进给机构等关键部件的结构组成和设计原理。薄片电极伺服进给机构具有恒张力自动送带与退带功能,可以保持稳定的放电间隙,使加工过程稳定持续地进行。
针对该加工技术的特殊要求和传统电阻限流脉冲电源电能利用率低等问题,采用新型拓扑结构和控制策略研制出了调压式节能脉冲电源。该电源具有自适应调压、等电流脉宽及独立电气特性,取消了耗能严重的限流电阻,可提高电能利用率2倍左右,且减小了电源体积。
采用带反馈的脉宽调制技术,研制出了片电极伺服机构直流电机控制系统,可使电火花加工过程稳定持续地进行。利用三相交-直-交变频调速与计算机控制技术,研制出了磨轮主轴的交流变频调速控制系统。
对非导电工程陶瓷电火花磨削特性和工艺规律进行了实验研究,给出了电源的脉宽、脉间、峰值电压、峰值电流、进给速度、磨轮转速和工作液等对材料去除率和加工表面质量的影响规律关系。
设计了非导电工程陶瓷单脉冲尖电极放电蚀除实验装置,研究了单脉冲放电的材料蚀除机理,总结出了相应的规律关系。
A novel technique named double electrodes synchronous servo electrical discharge grinding (DESSEDG) for non-conductive engineering ceramics, which can integrate the advantages of electrical discharge machining (EDM) and grinding, is presented to achieve high efficiency precision machining. This method employs a conductive grinding wheel which rotates fast on the surface of workpiece, and a sheet electrode which is automatically fed to the place where the wheel and workpiece meet. Discharges happen between wheel and sheet electrode under pulse power supply. The sheet electrode is very thin, so it can be considered that discharges are just on the surface of workpiece. The high temperature and pressure of plasma channel can be directly exerted to the workpiece surface to remove material. Then the sparks eroded layer is machined a second time by grinding of the conductive wheel. The advantages of DESSEDG are high efficiency, low processing costs, environmental pollution-free, and so on.
The DESSEDG machine is designed. The sheet electrode servomechanism and other key mechanical components are designed. And the whole prototype machine is developed. The sheet electrode servomechanism can keep a right discharge gap between the sheet electrode and the wheel, and store unused sheet electrode within it.
A new pulse power supply with novel topology and control strategy is put forward, taking into account specific requirement of the EDG machine and the low energy utilization rate of traditional pulse powers which use limiting resistors. The new power supply can provide large-scale adjustable peak voltage, pulse width and pulse interval. Current limiting resistors, which consume high energy, has been eliminated and the energy utilization rate is almost doubled.
A servo-control system for the DC motor of the sheet electrode servomechanism is designed based on PWM with feedback. It can guarantee the stable low-speed turning of the motor. Using AC-DC-AC frequency control and computer control technology, the control circuit of the motor for grinding wheel spindle is designed.
Through a series of experiments, the effects of electrical and non-electrical parameters such as pulse width, pulse interval, peak voltage, peak current, feeding speed, working fluid etc. on material removal rate and surface roughness of the non-conductive engineering ceramic workpieces are discussed in detail.
Experiments for single-pulse discharges on non-conductive engineering ceramics are studied. Effects of the parameters on the discharge craters size are discussed. The mechanism of discharge and material removal is analyzed.
引文
[1] ENGINEERING CERAMICS MARKET OUTLOOK. American Ceramic Society Bulletin, 2003, 82(11): 16-17.
[2] N. Mohri, Y. Fukuzawa, T. Tani, et al. Some considerations to machining characteristics of insulating ceramics - Towards practical use in industry. CIRP Annals - Manufacturing Technology, 2002, 51(1): 161-164.
[3] W Konig, D F Dauw, G Levy, et al. EDM - Future Steps Towards the Machining of Ceramics. Annals of the CIRP, 1988, 37(2): 623-631.
[4] Nancy F. Petrofes, Ahmed M. Gadalla. ELECTRICAL DISCHARGE MACHINING OF ADVANCED CERAMICS. American Ceramic Society Bulletin, 1988, 67(6): 1048-1052.
[5] J. H. Zhang, T. C. Lee, W. S. Lau. Study on the electro-discharge machining of a hot pressed aluminum oxide based ceramic. Journal of Materials Processing Technology, 1997, 63(1-3): 908-912.
[6] I. Puertas, C. J. Luis. A study on the electrical discharge machining of conductive ceramics. Journal of Materials Processing Technology, 2004, 153-154: 1033-1038.
[7] C. S. Trueman, J. Huddleston. Material removal by spalling during EDM of ceramics. Journal of the European Ceramic Society, 2000, 20(10): 1629-1635.
[8] Y. K. Lok, T. C. Lee. Processing of advanced ceramics using the wire-cut EDM process. Journal of Materials Processing Technology, 1997, 63(1-3): 839-843.
[9] N. M. Faulk. Electrical discharge machining of advanced ceramics. Proceedings of the International Conference on Machining of Advanced Materials. Gaithersburg, MD, USA: Natl Inst of Standards & Technology, 1993.
[10] D.F. Dauw, CA. Brown, J.P Van Griethuysen, et al. Surface topography investigations by fractal analysis of spark eroded electrically conductive ceramics. Annals of the CIRP, 1990, 39(1): 161-165.
[11] Chisato Tsutsumi, Keisaku Okano, Tetsuya Suto. High quality machining of ceramics. Journal of Materials Processing Technology, 1993, 37(1-4): 639-654.
[12] Wilfried Koenig, Matthias Popp. Precision machining of advanced ceramics. American Ceramic Society Bulletin, 1989, 68(3): 550-553.
[13] T. B. Thoe, D. K. Aspinwall, M. L. H. Wise. Review on ultrasonic machining. International Journal of Machine Tools & Manufacture, 1998, 38(4): 239-255.
[14] 刘晋春,赵家齐.特种加工.第2版.北京:机械工业出版社,1993.
[15] A. A. Abdel-Rahman, A. A. El-Domiaty. Maximum depth of cut for ceramics using abrasive waterjet technique. Wear, 1998, 218(2): 216-222.
[16] P. Gudimetla, J. Wang, W. Wong. Kerf formation analysis in the abrasive waterjet cutting of industrial ceramics. Journal of Materials Processing Technology, 2002, 128(1-3): 123-129.
[17] G. Spur, S. E. Holl. Ultrasonic assisted grinding of ceramics. Journal of Materials Processing Technology, 1996, 62(4): 287-293.
[18] 古谷克司,前田英昭.旋盤型電解放電加工機绝緣物加工.2006,30(96):1-6.
[19] Indrajit Basak, Amitabha Ghosh. Mechanism of spark generation during electrochemical discharge machining: a theoretical model and experimental verification. Journal of Materials Processing Technology, 1996, 62(1-3): 46-53.
[20] N. Umehara. Magnetic fluid grinding-a new technique for finishing advanced ceramics. CIRP Annals, 1994, 43(1): 185-188.
[21] 久保田護.放電加工放電複合研削.機械技術,1984,32(8):76-80.
[22] B. Bhattacharyya, B. N. Doloi, S. K. Sorkhel. Experimental investigations into electrochemical discharge machining (ECDM) of non-conductive ceramic materials. Journal of Materials Processing Technology, 1999, 95(1-3): 145-154.
[23] K. Allesu, A. Ghosh, H. K. Wuju. Preliminary qualitative approach of a proposed mechanism of material removal in electrical machining of glass. European Journal of Mechanical Engineering, 1991, 36(3): 201-207.
[24] K.Allesu,等.非导电材料的电化学放电加工和其他加工过程的某些实验研究.国际电加工新技术——ISEM-9论文选编.北京:北京科学技术出版社,1991.
[25] 刘永红.非导电超硬材料电加工新技术及其机理探索研究:[博士学位论文],哈尔滨工业大学,哈尔滨:1995.
[26] Yonghong Liu, Zhixin Jia, Jinchun Liu. Study on hole machining of non-conducting ceramics by gas-filled electrodischarge and electrochemical compound machining. Journal of Materials Processing Technology, 1997, 69(1-3): 198-202.
[27] Naotake Mohri, Yasushi Fukuzawa, Takayuki Tani, et al. Assisting electrode method for machining insulating ceramics. CIRP Annals-Manufacturing Technology, 1996, 45(1): 201-204.
[28] 福澤康,谷貴幸,岩根英二等.放電加工機用绝縁性材料加工.電気加工学会誌,1995,29(60):11-21.
[29] 黑松彰雄.新素材·難加工材MEEC加工法.技術,1986,24(12):66-68.
[30] 刘永红.双极性电加工工具:中国,01261619.2[P].2002-07-17.
[31] D.A. Taylor. ADVANCED CERAMICS-WHERE TO NEXT? Materials Australia, 2001, 33(1): 20-22.
[32] 金志浩,高积强,乔冠军.工程陶瓷材料.西安:西安交通大学出版社,2001.
[33] 周玉.陶瓷材料学.北京:科学出版社,2004.
[34] 郑昌琼,冉均国.新型无机材料.北京:科学出版社,2003.
[35] 杜建华,刘永红,李小朋等.工程陶瓷材料磨削加工技术.机械工程材料,2005,29(3):1-3,6.
[36] 铁瑛,赵波,张波等.工程陶瓷材料精密磨削加工技术的新发展.焦作工学院学报(自然科学版),2003,22(3):217-220.
[37] 潘立,张国林,王磊等.陶瓷磨削技术的研究进展.浙江工业大学学报,2003,31(6):641-646.
[38] 许琰,王贵成.工程陶瓷磨削加工的研究及其发展.工具技术,2004,38(9):53-55.
[39] K. Ramesh, S. H. Yeo, S. Gowri, et al. Experimental evaluation of super high-speed grinding of advanced ceramics. International Journal of Advanced Manufacturing Technology, 2001, 17(2): 87-92.
[40] S. M. Rezaei, T. Suto, T. Waida, et al. Creep feed grinding of advanced ceramics. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 1992, 206(B2): 93-99.
[41] Yoshio Ichida, Kozo Kishi, Yuichi Hasuda. Study on one-pass mirror finish grinding technology of fine ceramics (1st report). Development of new metal bonded fine grain diamond wheels and their application to mirror finish grinding. Journal of the Japan Society of Precision Engineering/Seimitsu Kogaku Kaishi, 1992, 58(3): 463-470.
[42] H. Huang, Y. C. Liu. Experimental investigations of machining characteristics and removal mechanisms of advanced ceramics in high speed deep grinding. International Journal of Machine Tools and Manufacture, 2003, 43(8): 811-823.
[43] Takao Nishioka, Yasushi Ito, Takehisa Yamamoto, et al. Surface grinding characteristics of Si_3N_4 ceramics under high-speed and speed-stroke grinding conditions. Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan, 1995, 103(1204): 1238-1242.
[44] I. Inasaki. Speed-stroke grinding of advanced ceramics. Annals of the CIRP, 1988, 37(1): 299-302.
[45] J. Y. Shen, C. B. Luo, W. M. Zeng, et al. Ceramics grinding under the condition of constant pressure. Fujian, China: Elsevier Science Ltd, 2002.
[46] 纳米尔,林滨,关强等.几种工程陶瓷的延性域磨削.天津大学学报(自然科学与工程技术版),1999,32(4):486-491.
[47] Lei Hong, Lijun Li, Chunlei Ju. Investigation of cutting of engineering ceramics with Q-switched pulse CO_2 laser. Optics and Lasers in Engineering, 2002, 38(5): 279-289.
[48] Hong Lei, Li Lijun. A study of laser cutting engineering ceramics. Optics & Laser Technology, 1999, 31(8): 531-538.
[49] 陈可心,张有,廖健宏等.用连续波CO_2激光对氮化硅陶瓷打孔的实验研究.华南师范大学学报(自然科学版),2000,(1):59-62.
[50] Chwan-Huei Tsai, Hong-Wen Chen. Laser milling of cavity in ceramic substrate by fracture-machining element technique. Journal of Materials Processing Technology, 2003, 136(1-3): 158-165.
[51] Matt Henry, Paul M. Harrison, Ian Henderson, et al. Laser milling-A practical industrial solution for machining a wide variety of materials. Nara, Japan: International Society for Optical Engineering, Bellingham, WA 98227-0010, United States, 2004.
[52] 袁根福,曾晓雁.Al_2O_3陶瓷激光铣削试验研究.中国激光,2003,30(5):467-470.
[53] 袁根福,曾晓雁.硬脆性无机材料激光成形加工研究与应用现状.激光与光电子学进展,2002,39(6):47-51.
[54] Z. J. Pei, P. M. Ferreira. An experimental investigation of rotary ultrasonic face milling. International Journal of Machine Tools and Manufacture, 1999, 39(8): 1327-1344.
[55] Ken-ichi Ishikawa, Hitoshi Suwabe, Tetsuhiro Nishide, et al. A study on combined vibration drilling by ultrasonic and low-frequency vibrations for hard and brittle materials. Precision Engineering, 1998, 22(4): 196-205.
[56] 徐文骥,卢毅申,金洙吉等.等离子体在陶瓷加工中的应用.机械工程学报, 2002,38(增刊):73-75.
[57] W. J. Xu, J. C. Fang, Y. S. Lu. Study on ceramic cutting by plasma arc. Journal of Materials Processing Technology, 2002, 129(1-3): 152-156.
[58] Praveen S. Medis, H. Thurman Henderson. Micromachining using ultrasonic impact grinding. Journal of Micromechanics and Microengineering, 2005, 15(8): 1556-1559.
[59] Hirofumi Isoyama, Tetsuo Uchida, Takashi Nagashima, et al. Ultrasonic grinding of fine ceramics for inductively coupled plasma atomic emission spectrometry using slurry nebulization technique. Journal of Analytical Atomic Spectrometry, 2004, 19(10): 1370-1374.
[60] G. Spur, E. Uhlmann, S. E. Holl. Ultrasonic assisted grinding of ceramics. Industrial Ceramics, 2001, 21 (3): 177-181.
[61] Patrick A. Rebro, Yung C. Shin, Frank P. Incropera. Laser-assisted machining of reaction sintered mullite ceramics. New York, NY, United States: American Society of Mechanical Engineers, New York, NY 10016-5990, United States, 2001.
[62] Chih-Wei Chang, Chun-Pao Kuo. An investigation of laser-assisted machining of Al2O3 ceramics planing. International Journal of Machine Tools and Manufacture, In Press, Corrected Proof.
[63] Chih-Wei Chang, Chun-Pao Kuo. Evaluation of surface roughness in laser-assisted machining of aluminum oxide ceramics with Taguchi method. International Journal of Machine Tools and Manufacture, 2006, In Press, Corrected Proof.
[64] I. D. Marinescu. Laser-Assisted Grinding of Ceriamics. High-Performance Ceramics, 1998, 47(5): 314-316.
[65] Jay C. Rozzi, Frank E. Pfefferkorn, Yung C. Shin, et al. Experimental Evaluation of the Laser Assisted Machining of Silicon NitrideCeramics. Journal of Manufacturing Science and Engineering-Transactions of the ASME, 2000, 122(4): 666-670.
[66] 北京市《金属切削理论与实践》编委会.电火花加工.北京:北京出版社,1983.
[67] 福澤康,谷貴幸,岩根英二等.放電加工機用绝縁性材料加工.電気加工学会誌,1994,29(60):11-21.
[68] Yasushi Fukuzawa, Takayuki Tani, Eiji Iwane, et al. New machining method for insulating ceramics with an electrical discharge phenomenon. Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan, 1995, 103(1202): 1000-1005.
[69] Y. Fukuzawa, N. Mohri, T. Tani, et al. Electrical discharge machining properties of noble crystals. Journal of Materials Processing Technology, 2004, 149(1-3): 393-397.
[70] 谷貴幸,福沢康,古谷克司等.绝縁性放電加工.精密工学会誌,1997,63(9):1310-1314.
[71] 福澤康,毛利尚武,谷貴幸.绝緑性材料放電加工法.精密工学会誌,2005,71(5):541-544.
[72] N. Mohri, Y. Fukusima, Y. Fukuzawa, et al. Layer generation process on work-piece in electrical discharge machining. CIRP Annals-Manufacturing Technology, 2003, 52(1): 157-160.
[73] 徐小兵.绝缘性陶瓷电火花加工原理和辅助电极膜制备探讨.新技术新工艺,2003,(5):17-18.
[74] Apiwat Muttamara, Yasushi Fukuzawa, Naotake Mohri, et al. Probability of precision micro-machining of insulating Si_3N_4 ceramics by EDM. Journal of Materials Processing Technology, 2003, 140(1-3 SPEC): 243-247.
[75] Yasushi Fukuzawa, Hiromitsu Gotoh, Naotake Mohri, et al. Line swept surface generation on insulating ceramics by wire electrical discharge machining. Journal of the Australasian Ceramic Society, 2005, 4(1): 17-21.
[76] Takayuki Tani, Yasushi Fukuzawa, Naotake Mohri, et al. Machining phenomena in WEDM of insulating ceramics. Journal of Materials Processing Technology, 2004, 149(1-3): 124-128.
[77] Indrajit Basak, Amitabha Ghosh. Mechanism of material removal in electrochemical discharge machining: a theoretical model and experimental verification. Journal of Materials Processing Technology, 1997, 71 (3): 350-359.
[78] A. Kulkarni, R. Sharan, G. K. Lal. An experimental study of discharge mechanism in electrochemical discharge machining. International Journal of Machine Tools and Manufacture, 2002, 42(10): 1121-1127.
[79] W. Y. Peng, Y. S. Liao. Study of electrochemical discharge machining technology for slicing non-conductive brittle materials. Journal of Materials Processing Technology, 2004, 149(1-3): 363-369.
[80] C. T. Yang, S. L. Song, B. H. Yan, et al. Improving machining performance of wire electrochemical discharge machining by adding SiC abrasive to electrolyte. International Journal of Machine Tools and Manufacture, 2006, 46(15): 2044-2050.
[81] 朱炳森,陈碧新,于兆勤等.特种陶瓷的MEEC加工法.广东工业大学学报,1994,11(1):40-44.
[82] 李小朋,刘永红,于丽丽等.非导电陶瓷双极性砂轮电火花机械复合磨削新技术.2005中国机械工程学会年会论文集.北京:机械工业出版社,2005.
[83] 李明辉.电火花加工理论基础.北京:国防工业出版社,1989.
[84] 何永辉.高效节能式电火花加工脉冲电源的研究:[博士学位论文],哈尔滨工业大学,哈尔滨:1995.
[85] 何永辉.PWM控制节能式电火花加工脉冲电源的研究:[博士学位论文],哈尔滨工业大学,哈尔滨:2001.
[86] Sodick Co., Ltd. EDM PULSE generator with a variable output inductor for producing PULSE with gradually rising edges: United States, 25676581 [P].
[87] 瑞士洛迦诺电子工业股份有限公司.电火花腐蚀金属加工用的脉冲发生器:中国,87107913[P].
[88] Takuji Magara. Power Source for Electric Discharge Machining: United States, 5149931[P].
[89] 赵万生,宋博岩.逆变式电火花加工脉冲电源的研究.哈尔滨工业大学学报,1997,29(6):112-115.
[90] 吴文江,穆新华.采用电流控制策略的新型电火花加工电源研究.电力电子技术,2002,36(2):5-8.
[91] 韩强,赵万生,狄士春.电火花加工放电状态稳定性的研究.电加工,1999,(2):8-12.
[92] 王鸿钰.实用电源技术手册.上海:科学技术出版社,2002.
[93] 刘胜利.现代高频开关电源实用技术.北京:电子工业出版社,2001.
[94] 阮新波,严仰光.脉宽调制DC/DC全桥变换器的软开关技术.北京:科学出版社,1999.
[95] 张卫平.绿色电源——现代电能变换技术及应用.北京:科学出版社,2001.
[96] 张小良.高电压大电流直流固体继电器的电路设计.世界电子元器件,2003,(9):38-39.
[97] 周志敏,周纪海.开关电源使用技术设计与应用.北京:人民邮电出版社,2003.
[98] 秦继荣,沈安俊.现代直流伺服控制技术及其系统设计.北京:机械工业出 版社,1993.
[99] 曹凤国.电火花加工技术.北京:化学工业出版社,2005.
[100] 严瑞瑄.水溶性高分子.北京:化学工业出版社,2000.
[101] 方建华,陈波水,董凌等.环境友好水基电火花线切割金属加工液的研制.润滑油,2004,19(6):38-40.