【正文】 孔距及測量孔的深度用，千分尺用于測量孔系之間的同軸度。②決定銑削用量：粗加工余量,查《切削用量簡明手冊》=,取。l 精銑上端面①刀具和機床不變。④計算基本工時式中。②決定銑削用量：粗銑加工余量，查《切削用量簡明手冊》=,取。查《切削用量簡明手冊》表12選擇不重磨損硬質合金套式面銑刀，刀片采用YG6。因此實際切削速度和每齒進給量為：④計算基本工時式中， 。④計算基本工時式中，入切量及超切量查《切削用量簡明手冊》表2..29得， 。④計算基本工時式中，入切量及超切量查《切削用量簡明手冊》表2..29得， 。切削速度的修正系數為， 則 根據機床說明書取。③計算切削速度：查《實用機械制造工藝設計手冊》[8]得當時， 根據機床說明書取。③計算切削速度：查《切削用量簡明手冊》，切削速度的修正系數為，則根據機床說明書取。查《機械制造工藝設計簡冊》表3123取切削速度，取，取切削速度。②確定進給速度及切削速度：選擇60度單刃鏜刀，材料為硬質合金。（7）鏜深20的盲孔l 粗鏜孔至①選用刀具，確定背吃刀量：選擇60度單刃鏜刀，材料為硬質合金根據加工工藝要求取背吃刀量。④確定切削用時= =。③確定主軸轉速n查機床說明書取，切削速度。③確定主軸轉速n查機床說明書取，切削速度。圖41 工序尺寸圖在加工剩余三個孔時，孔的直徑由刀具直接保證，而孔的位置和加工精度則由所涉及的夾具保證。 定位方案的確定工件定位時，影響加工要求的自由度必須限制；不影響加工要求的自由度，有時要限制，有時可不限制，視具體情況而定。可在下端面設計一定位盤與閥體的下端面接觸以限制了工件沿y軸移動、繞x軸轉動以及繞z軸轉動三個自由度；同時通過固定在定位盤上的兩個定位銷與閥體兩孔之間的過渡配合限制了工件繞y軸轉動、沿z軸移動以及沿x軸移動，定位圖如圖41。選擇定位銷（與工件配合的圓柱銷），取定位孔直徑為圓柱銷的基本尺寸，則應選擇g6的圓柱銷，查《機床夾具設計》[10]表41選擇寬度b=4mm的菱形銷。本工序要求保證的位置精度主要是孔與孔間的同軸度誤差，選擇30H7孔中心線作為工序基準，根據基準重合原則，定位基準與工序尺寸重合，因此=0。l 因為基準不重合誤差=0，基準位移誤差=（mm）。在加工工件時通過擰緊螺母使壓板夾壓在工件上端面，同時在采用螺旋壓板組合夾緊時，由于工件接觸表面存在高度誤差，壓板位置不可能一直保持水平，因此可在螺母端面和壓板之間加以墊圈，以防止壓板傾斜時，螺栓不至因受彎曲作用而損壞同時也可減少因夾緊變形而產生的夾緊誤差。圖45 夾緊裝置 夾緊力的計算由圖可知夾緊力的方向與刀具運動方向一致，即與切削力同向。計算夾緊力是一個很復雜的問題，所以一般只能粗略的估算。查《機床夾具設計手冊》[12]得=，=，=，=，=，=，=。查《現(xiàn)代加床夾具設計》得，其中L=10mm,Q=80N，故螺紋夾緊力。在不考慮工件表面變形的情況下，夾緊引起的定位基準位移即為工序基準位移。因為，故夾緊裝置可用。圖52 固定盤二維圖設計完固定盤后還需設計一定位盤，工件直接與定位盤接觸，根據零件尺寸可設計出定位盤定位盤與固定盤通過凸臺連接，通過3個M12T型螺栓擰緊，如圖53所示。最后取平衡塊厚度d=15mm平衡塊如圖55所示。裝配時工件底面直接與定位盤接觸，通過一面兩銷進行完全定位并通過夾緊機構進行夾緊。2）定位盤的安裝 將定位盤通過凸臺直接套在固定盤上，然后利用3個M12螺母與固定盤擰緊。5）轉位分度 加工完成孔1后拔出分度定位器，松開3個M12T型螺栓，定位盤、分度定位機構及工件一起通過定位盤凸臺繞固定盤轉動。6）再轉位分度 重復孔2的加工過程。在大學四年的學習里，我們初步掌握了機械專業(yè)的基礎理論和基本技能，并通過一些必要的實驗和簡單的課程設計獲得了初步的實踐經驗。我國從事閥門生產的企業(yè)很多，且多屬中小企業(yè)。根據《20132017年中國閥門制造行業(yè)供需狀況與對外貿易分析報告》數據顯示，截至2011年底，我國擁有規(guī)模以上閥門企業(yè)(年營收2000萬元以上)1485家，%。致 謝歷時將近四個月的時間終于將這篇論文寫完，在論文的寫作過程中遇到了無數的困難和障礙，都在同學和老師的幫助下度過了。本文引用了數位學者的研究文獻，如果沒有各位學者的研究成果的幫助和啟發(fā)，我將很難完成本篇論文的寫作。Robotics and CIMS, Vol. 1, No. 2, 1984, pp. 167172.附錄A 外文文獻及譯文Machining fixture locating and clamping position optimization using genetic algorithmsNecmettin KayakDepartment of Mechanical Engineering, Uludag University, Go ru , Bursa 16059, Turkey Received 8 July 2004。 Optimization1. IntroductionFixtures are used to locate and constrain a work piece during a machining operation, minimizing work piece and fixture tooling deflections due to clamping and cutting forces are critical to ensuring accuracy of the machining operation. Traditionally, machining fixtures are designed and manufactured through trialanderror, which prove to be both expensive and timeconsuming to the manufacturing process. To ensure a work piece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped, making it imperative to develop tools that will eliminate costly and timeconsuming trialanderror designs. Proper work piece location and fixture design are crucial to product quality in terms of precision, accuracy and finish of the machined part. Theoretically, the 321 locating principle can satisfactorily locate all prismatic shaped work pieces. This method provides the maximum rigidity with the minimum number of fixture elements. To position a part from a kinematic point of view means constraining the six degrees of freedom of a free moving body (three translations and three rotations). Three supports are positioned below the part to establish the location of the work piece on its vertical axis. Locators are placed on two peripheral edges and intended to establish the location of the work piece on the x and y horizontal axes. Properly locating the work piece in the fixture is vital to the overall accuracy and repeatability of the manufacturing process. Locators should be positioned as far apart as possible and should be placed on machined surfaces wherever possible. Supports are usually placed to enpass the center of gravity of a work piece and positioned as far apart as possible to maintain its stability. The primary responsibility of a clamp in fixture is to secure the part against the locators and supports. Clamps should not be expected to resist the cutting forces generated in the machining operation. For a given number of fixture elements, the machining fixture synthesis problem is the finding optimal layout or positions of the fixture elements around the work piece. In this paper, a method for fixture layout optimization using genetic algorithms is presented. The optimization objective is to search for a 2D fixture layout that minimizes the maximum elastic deformation at different locations of the work piece. ANSYS program has been used for calculating the deflection of the part under clamping and cutting forces. Two case studies are given to illustrate the proposed approach.2. Review of related worksFixture design has received considerable attention in recent years. However, little attention has been focused on the optimum fixture layout design. Manassas and Decries[1]used FEA for calculating deflections using the minimization of the work piece deflection at selected points as the design criterion. The design problem was to determine the position of supports. Meyer and Liou[2] presented an approach that uses linear programming technique to synthesize fixtures for dynamic machining conditions. Solution for the minimum clamping forces and locator forces is given. Li and Melkote[3]used a nonlinear programming method to solve the layout optimization problem. The method minimizes work piece location errors due to localized elastic deformation of the work piece. Roy andLiao[4]developed a heuristic method to plan for the best supporting and clamping positions. Tao et al.[5]presented a geometrical reasoning methodology for determining the optimal clamping points and clamping sequence for arbitrarily shaped workpieces. Liao and Hu[6]presented a system for fixture configuration analysis based on a dynamic model