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在VERICUT软件环境下建立了虚拟数控非圆齿轮磨齿机床.首先基于成形砂轮展成磨削非圆齿轮的基本原理,进行了磨床的运动数据计算,并构造了符合实际加工要求的G代码形式.然后在 VERICUT下进行了机床模型的搭建,并根据实际磨床的系统特性,选择了合适的控制器,配置了相关参数,建立了非圆齿轮数控加工的虚拟磨床系统.最后在VERICUT下进行了非圆齿轮的加工仿真,对加工仿真中各种干涉情况进行了检查.通过该方法,可以很好地验证非圆齿轮磨削理论的准确性,同时为后续非圆齿轮的实际加工提供了可靠依据.

為解決自由曲面工件定位中無法正確求取對應點問題,運用分級兩步定位方法進行定位,達到正確求解的目的.首先在工件曲面和CAD曲面上分別均勻取點,提取曲面上的特征曲面,獲得特征匹配關系,然后算出對應的位姿關系,完成預定位、精定位.為節省計算時間,提出了基于最大特征值優化的采點方法.最后給出實例研究,驗證了方法的正確性. Aimed at the difficulty in getting the corresponding points in free-form surface localization of workpiece, a two-level localization method is presented. Firstly, some points distributed uniformly on workpiece surface and CAD surface are selected. Then the features are extracted and pairs of corresponding features are matched. The transformation is computed to achieve the pre-positioning and the accurate positioning. In this process, a probing strategy based on the optimization of the maximum eigenvalue is proposed to reduce the computing time. Results of a case study prove the validity of the presented method.

接觸式測頭記錄的是球心坐標,而在工件定位過程中實際使用的數據是測頭和工件接觸點的坐標。針對這個問題,提出了測頭半徑誤差補償的迭代方法。從測量點集和CAD模型這兩個角度來看,分別存在一個偏移曲面,將這個偏移量嵌入到工件定位算法中,構建了一個半徑誤差補償的迭代過程。實驗結果表明,和傳統的補償方法的計算結果相比,該補償方法顯著提高了定位精度,并且對算法的計算效率影響不大。 Contact probe records the center of its ball end. The data used in workpiece localization are the coordinate of points where the probe contacts with the workpiece. Focusing on the instance, an iterative method of contact probe error compensation was presented. Viewed from the measurement point set and CAD model individually, there was an offset surface. The iterative compensation method was formed if the offset was embedded in the localization algorithms. The experimental results indicate that the iterative compensation methods improve the localization precision enormously, compared with results using the traditional methods. And its computation efficiency is not affected drastically.

在考慮速度、加速度穩定性和加工誤差精度的基礎上,設計了一個完善的自適應NURBS插補器。該插補器不僅能夠根據曲線的形狀,自適應地調整速度,而且通過加減速處理模塊和速度再修正模塊,使速度在變速過程中始終以恒定的加速度進行升降,從而不僅能夠滿足機床的加減速能力的要求,而且使得機床運行更加平穩,提高了加工精度。計算實例驗證了所設計的離線自適應NURBS插補器的可行性。 A completed adaptive interpolator was developed for non-uniform rational B-spline (NURBS) curves interpolation herein. In the proposed interpolator, both the chord accuracy and the acceleration/deceleration capability of machine tool were considered. Three modules, adaptive-feedrate adjustment, acceleration/deceleration disposal and feedrate modification, were applied to deal with the acceleration/deceleration around the feedrate sensitive sharp corners, and finally a satisfactory result is achieved. A case study was provided to evaluate the feasibility of the developed interpolator at last.

為了克服直線和圓弧插補的各種不足,實現曲線插補,針對數控加工中的連續多段小直線刀具軌跡,提出了一種簡單快捷的B-Spline曲線(NURBS曲線的特殊形式)擬合算法.該算法以標準的B-Spline最小二乘方法為基礎,通過簡化后的誤差計算模塊,可以將擬合后的曲線和原有路徑的偏離控制在要求的范圍內,并提出了可以實現快速連許多段小直線刀具軌跡擬合的搜索方法-最大擬合區間的穩步前進方法.通過實例計算分析,證明了給出的擬合方法可靠高效. In order to overcome the drawbacks of linear and circular interpolation and realize the curve interpolation, an algorithm of B-Spline curve fitting was proposed, to deal with continuous small line segments of the tool path. The algorithm is based on the least square method and can keep the deviation between the fitting curve and the original path within the requtred range. In addition, a steady progress method was proposed to search the maximum fitting interval in continuous small line segments of the tool path. The efficiency and reliability of the proposed fitting algorithm were proved in practice.