螺旋曲面盘铣刀铣削方法研究

螺旋曲面零件是螺旋类机械的重要组成部分,其精度影响着螺杆机械的性能。研究了螺旋曲面盘铣刀的铣削原理,通过与传统的成形铣削对比,建立了刀具与工件的相对位置及坐标系,研究了工件与刀具的空间啮合条件,为进一步研究高精度复杂螺旋曲面加工技术奠定了理论基础。     

空间圆弧逼近法加工螺旋曲面的参数优化

针对双螺杆混输录转子截面廓形的几何特点，根据空间圆弧逼近原理，即空间的某一段圆弧逼近理论螺旋面的母线，用圆环盘铣刀加工此类螺旋曲面，这段空间圆弧可由铣削时的刀尖空间回转运动轨迹来得到。在铣削螺旋面过程中，刀具参数对所形成螺旋面的精度有很大的影响，为了满足其精度的需要，设计了刀具参数优化计算系统。轴向是影响双螺杆混输泵工作效率及性能的误差敏感方向，在优化计算系统的设计中，把逼近螺旋面与理论螺旋面之间对应点的轴向误差最大值作为刀具参数选择的主要衡量标准，并通过计算实例来验证此种优化方法的可行性。     

一种测定圆柱螺旋铣刀各阶固有频率的方法

通过引入刀杆有效截面系数的概念 ,提出一种在不同悬臂长度下确定刀具各阶固有频率的新方法。该方法对同一把铣刀 ,只需一次性测量计算 ,就可确定其在任意悬臂长度时比较精确的各阶固有频率 ,无需再去关心刀具材料特性参数和几何参数。     

一种动平衡问题的优化求解方法

这里采用了一种优化方法，对切槽机切削刀盘的动平衡问题进行研究，以实现切槽刀最小振幅为目标，得出切削刀盘偏心质量的最佳设计值，并初步验证了此方法的可行性。     

铣刀螺旋角的形成及对切削性能的影响

首先通过铣刀螺旋槽和铣刀前角的数学模型,研究了铣刀螺旋角的形成原理及其对铣刀切削性能的影响。其次用3组不同螺旋角的成形单刃铣刀做切削试验,并记录试验结果。对所得的试验结果进行分析,通过分析可知,铣刀的螺旋角越大,其排屑效果越好,切削纹路越细,最后验证所提理论的正确性。     

一种新的螺旋面加工刀具的CAD生成方法

基于刀具与螺旋面工件之间的关系及基本加工原理,提出了一种新的基于离散点的圆柱螺旋面成形刀具廓形的CAD生成方法——薄片法。采用VB对SolidW orks进行二次开发给出了薄片法的实现程序,并与CAD实体布尔运算法进行了比较。结果表明:该方法不仅精度高,而且具有直观、简单,内存占用小,生成文件小等优点。     

螺杆泵定子内螺旋曲面铣削指状铣刀的有限元分析

应用有限元方法,分析指状铣刀在铣削内螺旋曲面的情况下,刀具的内部应力、变形及其在随加工参数每齿进给量变化而变化的规律,并对指状铣刀的模态进行分析,为减少指状铣刀在加工过程中的非正常磨损现象,提高指状铣刀寿命,提供了优化方案,为优化加工工艺参数提供参考.     

一种加工复杂螺旋曲面的新方法

提出了四自由度刀具变安装角无瞬心包络铣削螺旋曲面的新方法。描述了一种复杂螺旋曲面加工专用数控主轴装置,分析复杂螺旋曲面的加工特点和加工中存在的问题,从而设计出了一种卧式专用数控机床的主轴装置。系统结构简单,运行平稳可靠。     

一种可调式二轴铣刀头架的设计与实现

为降低手术刀柄专用机床的改造成本,设计了一种新型可调式二轴铣刀头架。由于采用了斜齿轮消除间隙机构,有效补偿了调节过程中产生的齿侧间隙。介绍了该装置的结构和工作原理及实现方法,并推导了薄片斜齿轮间加工垫片厚度的计算公式。经实践表明:该装置结构简单、运行平稳,很好地满足了生产要求。     

Shape error compensation in flexible forming process using overbending surface method

In this article, the design of the flexible forming process considering die shape compensation using an iterative overbending method based on numerical simulation is carried out. In this method, the springback shape obtained from the final step of the first forming simulation is compared with the desired objective shape, and the shape error is calculated as a vector norm with three-dimensional coordinates. The error vector is inversely added to the objective surface to compensate both the upper and lower flexible die configuration. The flexible dies are made up of several punches that make a forming die that is equivalent to a solid die, thus the forming surface shape can be reconfigurable with regard to the compensated die shapes. The flexible die shapes are recalculated, and the punch arrays are adjusted according to the overbent forming surface. These iterative procedures are repeated until the shape error variation converges. In addition, experimental verification is carried out using a 2,000-kN flexible forming apparatus for thick plates. Finally, the configuration of the prototype obtained from the experiment is compared with the numerical simulation results, which have consideration of the springback compensation. Consequently, it is confirmed that the suggested method for compensating the forming error could be used in the design of the flexible forming process for thick-curved plates.     

一种便捷的解决螺旋线与拉伸对象垂直的方法

提出了一种便捷的解决螺旋线与拉伸对象垂直的方法,并介绍了其实现过程,利用这一方法能高效、快捷地创建三维螺旋体。     

Continuous flexible roll forming for three-dimensional surface part and the forming process control

Continuous flexible roll forming (CFRF) is an effective sheet metal-forming process used to manufacture three-dimensional surface parts. To obtain a final part with desired shape, the CFRF process should be systematically and accurately controlled in the longitudinal and transverse directions simultaneously. The major purpose of the present work is to establish a system of methods for controlling the continuous forming process. The target surface of desired part is represented by triangular mesh; the transverse control model for adjusting the shape of flexible roll is proposed based on the cubic B-spline curves; and the formulations to determine the downward displacement of upper roll is presented. Finally, the software for controlling CFRF process is developed, and the validity of the presented methods and the effectiveness of the developed software are demonstrated by CFRF test for a typical surface part.     

Investigation on the forming force and surface quality during ultrasonic-assisted incremental sheet forming process

The integration of ultrasonic vibration into the incremental sheet forming (ISF) process can significantly reduce the forming force and bring other benefit     

A new parallel genetic algorithm for solving multiobjective scheduling problems subjected to special process constraint

This study presents a multiobjective scheduling model on parallel machines (MOSP). Compared with other scheduling problems on parallel machines, the MOSP is distinct for the following characteristics: (1) parallel machines are nonidentical, (2) the type of jobs processed on each machine can be restricted, and (3) the multiobjective scheduling problem includes minimizing the maximum completion time among all the machines (makespan) and minimizing the total earliness/tardiness penalty of all the jobs. To solve the MOSP, a new parallel genetic algorithm (PIGA) based on the vector group encoding method and the immune method is proposed. For PIGA, its three distinct characteristics are as follows: Firstly, individuals are represented by a vector group, which can effectively reflect the virtual scheduling policy. Secondly, an immune operator is adopted and studied in order to guarantee diversity of the population. Finally, a local search algorithm is applied to improve the quality of the population. Numerical results show that it is efficient, can better overcome drawbacks of the general genetic algorithm, and has better parallelism.     

A wide-panel forming process to replace conventional roll forming

The geometric basis for the design of a new process to form sheet metal into a flat, corrugated product is described. The underlying principle is to determine a surface between entry of the sheet into the device and the exit of the formed product such that all points across the width of the sheet under go as nearly as possible similar deformation histories and also that longitudinal strain in the sheet is minimized. The surface for forming a product having a sinusoidal profile and also that for a trapezoidal profile are presented as examples. For the sinusoidal product, an empirical equation is developed that relates the strain during forming with the initial and final width, the forming length and the number of profile segments.A physical model shows that a sheet can be formed to such a surface without straining or buckling. Although this paper does not describe the type of tooling or forming machine that would be used to plastically deform steel sheet, the authors believe such a device can be constructed. The results suggest that the new approach would reduce defects such as edge-wave, oil-canning and splitting and that the overall length of the forming device could be an order of magnitude smaller than that for existing roll-forming lines.     

6R型串联机器人工作空间快速求解方法

针对机器人工作空间求解特点,提出了一种基于Matlab中SimMechanics模型并结合蒙特卡洛法的机器人工作空间求解方法.最后与数值法作了实验对比,证明该方法在求解速度上有很大的优势,并且克服了传统方法中对机器人运动学正、反解的依赖.     

螺旋焊管机组中成型机的设计及调型

介绍了螺旋焊管机组的组成和特点及成型机的结构及原理,并对成型机的调型进行了分析。     

A new surface parameterization method based on one-step inverse forming for isogeometric analysis-suited geometry

In an attempt to construct an isogeometric analysis-suited geometry for isogeometric analysis, a new surface parameterization method using the one-step inverse forming (SPIA) is proposed. Initial generation of watertight analysis-suitable geometry (NURBS surfaces) with complex shapes can be a significant bottleneck for isogeometric analysis because computer-aided design models often include ambiguities such as gaps and overlaps. Most of traditional surface parameterization techniques are based on geometric method and limited to finite meshes, while SPIA is a physics-based method using sheet metal forming technique with large elastic–plastic deformation and robust enough and rapid to deal with the finite elements mesh with over 100,000 nodes within 2 min without the necessity to simplify the meshes. Using Coons surface parameterization, global mesh parameterization, and NURBS reconstruction, we can rebuild new computer-aided design models with errors under any tolerance to which isogeometric analysis can be applied. The NURBS surfaces after reconstruction are also used for computer-aided manufacturing.