【文章內(nèi)容簡介】 計[M]．北京化學工業(yè)出版社，北京工業(yè)裝備與信息工程出版社，2005．8[13] 馬綱，王之櫟，韓松元．一種新型搬運碼垛機械手的設計[J]．北京：北京航空航天大學，100083[14] 章躍，張國生．機械制造專業(yè)英語[M]．北京機械工業(yè)出版社，1999．12[15] 楊叔子 楊克沖． 機械工程控制基礎 第五版[M]．武漢：華中科技大學出版社，2005．7[16] 孫桓，陳作模，葛文杰. 機械原理 第七版[M]．北京：高等教育出版社2006．5[17] 李廣弟，朱月秀，[M].北京：北京航空航天大學出版社，[18] [M].北京：科學出版社，2004謝 辭本次設計是對自己大學四年來所學東西的一次總結，在設計中出現(xiàn)過許多的狀況，也從中學習了許多。從分析論文的任務要求，到搜索相關的資料，拓展自己的知識面，一步步收獲頗多。我最初做了一套設計方案，但到后來做到一定的程度時，我發(fā)現(xiàn)最初的設計有很大的缺陷，“從頭再來”。這無疑是對自己設計的一次挑戰(zhàn)和創(chuàng)新，我接受了顏老師給我的建議，從他的身上，我學到了許多，一種以身作則，一種負責的態(tài)度，一種豁達的人生觀。一種學機械就必須按照一定的標準來衡量一切事物的方法論。感謝顏竟成老師對我的精心指導。英 文 翻 譯A Cutter Orientation Modification Method for the Reduction of Nonlinearity Errors in FiveAxis CNC MachiningABSTRACTIn the machining of sculptured surfaces，fiveaxis CNC machine tools provide more flexibility to realize the cutter position as its axis orientation spatially changes .Conventional fiveaxis machining uses straight line segments to connect consecutive machining data points ,and uses linear interpolation to generate mand signals for positions between end points，Due to fiveaxis simultaneous and coupled rotary and linear movements, the actual machining motion trajectory is a nonlinear path. The nonlinear curve segments deviate from the linearly interpolated straight line segments, resulting in a nonlinearity machining error in each machining step. These nonlinearity errors, in addition to linearity error, monly create obstacles to the assurance of high machining precision. In this paper, a novel methodology for solving the nonlinearity errors problem in fiveaxis CNC machining is presented. The propose method is based on the machine typespecific kinematics and the machining motion trajectory. Nonlinearity errors are reduced by modifying the cutter orientations without inserting additional machining data points. An offline processing of a set of tool path data for machining a sculptured surface illustrates that the proposed method increases machining precision. KeywordNonlinear error。 Machine kinematics。 Machining motion trajectory. INTRODUCTIONIn conventional fiveaxis machining, a tool path, represented by the cutter locations data (CLDATA), consists of the spatially varying cutter positions and its axis orientations. These CLDATA are generated based solely on the geometrical properties of the machined surfaces and the cutter. These CLDATA are further processed into NCcodes which is specific to a particular machine configuration. Linear interpolation is then used to generate the required mands for positions along line segment connecting the machining data points. The simultaneous linear and rotary movements are involved in fiveaxis machining since ever new cutter axis orientation requires the motion at least one other axis. There are also coupling effects of the cutter axis will affect the position of the cutter. These simultaneous and coupled movements cause the cutter contract point (CC point) to move in a nonlinear manner. As a result, the machining error in each motion step is made up of not only the linear segmentation approximation error but also an additional machining error. As shown in figure 1 for machining is either a concave surface or a convex surface, a line segment is used to connect two consecutive machining data points (the spindle chunk is the machine control point MCP). Linear interpolation generate intermediate positions along the line segment. The desire surface is design curve(either concave or convex). The linear segment approximates to design curve resulting in the linearity error,δt. Apart from the linearity error . The nonlinear CC point trajectory deviates from the straight line segment (the cutter gage length is constant and MCP is interpolated along the line segment)result in an additional machining error, referred to as the nonlinearity error, δn. In the case that the desire surface is concave(see figure 1a), the total machining error is difference of the nonlinearity error and the linearity error : δtotal=δtδn. The nonlinearity error, in this case, pensate for the total machining error(AIGP Postprocessor,1996。Liu,1994). On the contrary, for the machining of convex surface as shown in figure 1b, the nonlinearity error adds onto the linearity error and enlarges the machining error: δtotal=δt+δn(AIGP Postprocessor,1996。Liu,1994). figure1. The multiaxis CNC machining errorConsequently the nonlinearity error have caused difficulties for ensuring ultraprecision machining requirements. In the machining of airfoil surface, for example, the machining of the contour surface of airfoil to the edges is problematic. The surface curvature on these area changes abruptly, and thus the cutter orientation varies inconsistently from one cutter to the next. These abrupt cutter orientation variations inconsistently from one cutter location to the next .These abrupt cutter orientation are a typical nonlinearity error problem.In order to solve the fiveaxis CNC machining error problem, efforts have been made to treat nonlinearity errors in generate NC codes. Some researchers and postprocessor producers used “l(fā)inearization processes” for this purpose. The basic function of “l(fā)inearization processes ” are inserting machining data points between NC codes where the total machining error is out of the specified tolerance range. Takeuchi et al. (1990) inserted points by subdividing the line segment with equally space d interval. Cho et al. (1993) inserted data points by limiting the maximum machining error within the line interval from the start point to the inserted point to be the tolerance. And, both of them set the cutter orientations varying linearly in successive positions. In the Automation Intelligence Generalization Postprocessor (AIGP)(1996), a “l(fā)inearization processes ” calculates the middle point (MP) between adjacent NCcodes and inserts the MP as an additional data in the NC code. The insertion can be per