共查询到19条相似文献,搜索用时 552 毫秒
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在发动机制造、飞机制造、机床制造或其他机械制造中,常常会碰到带有双斜平面的零件。图1表示实际生产中所遇到的一种零件。它的上平面相对于底部的基准平面是双向倾斜的。对角度精确度要求不高的双斜平面零件,可以在零件表面上划斜面线,按线找正加工。对角度要求较高的零件.例如其角度公差为±5′或者更高时,划线的加工方法不能保证零件的精度要求。这时,一般要用双向正弦台将零件精确定位,来保证其斜面加工时的角度公差。 相似文献
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基于工序加工能力的并行公差优化设计 总被引:3,自引:2,他引:3
提出一种基于工序加工能力的并行工序公差优化设计方法。在产品的初步结构设计阶段,通过相配零件的加工工艺规划把装配功能公差表示为零件的工序公差,建立以加权制造总成本最小为目标,以并行公差链、标准化的工序公差系数、机床最大经济极限公差为约束的非线性并行公差优化设计模型,求解该模型得到最佳的工序公差。最后给出了并行公差优化设计的一个工程实例,结果表明,所提的方法具有比传统串行等精度方法更合理、工序公差数值更大的优点。 相似文献
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为了改善公差分析规范的手工翻译出错率高和效率低的现状,并帮助公差分析系统理解来自上游的产品设计模型的语义信息,提出一种面向公差分析的几何尺寸和公差(GDT)语义信息翻译方法。对需要翻译的GDT语义信息进行分类,并建立适用于中性文件的EXPRESS模型;使用本体建模语言将得到的EXPRESS模型映射为对应的本体,为后续的推理提供基础;使用语义网规则语言对从本体中提取公差分析规范的规则进行定义和编码,实现语义信息的自动推理功能;在计算机辅助设计系统上开发了GDT语义信息翻译插件,自动提取得到的GDT数据并加入中性文件中,使用Protégé进行本体和规则建模,最终推理出公差分析所需规范。同时使用一个装配模型验证了所提出方法的有效性。 相似文献
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提出一种基于产品设计与制造、支持公差工程语义和并行公差的几何公差计算机辅助建模表示新方法。在CAD系统中,进行装配公差和零件制造公差建模,利用特征的几何公差结构块,求出各种公差带的空间表示函数,计算有关公差带在三维空间中相应自由度的允许变动量,为公差分析和综合提供实用的模型。用工程实例验证了所提出的方法。 相似文献
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详述了在设计非圆曲线零件淬火机床过程中应用运动控制卡实现恒速运动的控制方法。通过设置运动参数,控制程序按照恒速运动数学模型计算,运动控制卡输出脉冲信号分别控制两轴并实现联动,达到零件轮廓相对于淬火机床感应器恒速运动的目的。以偏心轮零件为试件进行运动测试,恒速误差在3%以内,可达到工件的热处理要求,为淬火机床实际应用提供可靠依据。 相似文献
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Modified Elman network for thermal deformation compensation modeling in machine tools 总被引:7,自引:7,他引:0
Zhiyong Yang Minglu Sun Weiqian Li Wenyong Liang 《The International Journal of Advanced Manufacturing Technology》2011,54(5-8):669-676
Thermal deformation is one of the most significant causes of machining errors in machine tools. One effective method is to build a compensation system to offset the thermal errors. Therefore, an accurate model is the key part of the compensation system. This study proposed a modified Elman network (EN) to improve the prediction accuracy of the compensation model in machine tools. And the improved EN can be regarded as a feed-forward neural network with feedback from hidden layer and output layer as an additional set of inputs. The structure of this network determines its dynamic characteristic with memory function. On the other hand, thermal deformation of the spindle contributes the largest part of total thermal errors in precision machining. Then a precise finite element model of machine tool spindle was established. And a new method for calculating the heat transfer convection coefficient on the surface of the spindle was proposed in this paper. The improved EN was used to map the nonlinear relationship between temperature field and thermal errors of the spindle. At last, a verification experiment was implemented on a CNC center and some satisfying results were achieved. 相似文献
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Kuen-Hung Hsieh Tsair-Rong Chen Paul Chang Chia-Hui Tang 《The International Journal of Advanced Manufacturing Technology》2013,64(5-8):889-901
The errors which affect the processing tolerance of a machine tool are due to the built-in volumetric errors in the machine tool structure and also the thermal displacement of the machine tools during its cutting. In this paper, a dual-displacement meter compensation system is developed. The new model has a better tolerance control than the single-displacement compensation meter method; also, it has a great potential for saving a machine’s warm-up time as well as enhancing productivity. A dual-displacement meter is designed to detect the variation of spindle thermal growth and a differential amplifier is applied which ensure a precise output signal tolerance of spindle thermal growth. The unstable signal which is an effect of flatness tolerance of spindle surface is then omitted. Finally, the spindle thermal growth compensations are successfully reduced. It meets the requirement of high-speed machining and high-precision machining application. 相似文献
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现有大部分搅拌摩擦焊设备缺乏对过程变量的有效监控,建立开放式的控制系统是解决这一问题的有效手段,然而搅拌摩擦焊工艺与传统的金属切削有两大不同,即焊接倾角与圆弧切线跟踪功能。现有设备将圆弧切线跟踪功能集成到控制系统中,导致用户研究开放式可控制系统时还需对此功能进行专门的设计,进而导致设备研发周期变长、成本增加。构建了基于Ether CAT的开放式控制系统,以一种龙门式搅拌摩擦焊机床为例,运用D-H法推导出机床全参数化正逆向运动学数学模型,并提出一种简单的平面二维圆弧切线跟踪方法,在已有两轴圆弧插补的基础上不需研究三轴插补算法即可完成搅拌摩擦焊。最后选择一种典型的焊缝轨迹进行运动仿真与焊接试验,验证了机床参数化运动学模型的正确性及圆弧切线跟踪方法的可行性。 相似文献
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在数控机床中,伺服系统是数控机床装置和机床的中间连接环节,是数控系统的重要组成部分。伺服系统接受来自伺服控制器的进给脉冲,经变换和放大转换为机床工作台的位移,使工作台跟随指令脉冲移动。讨论了闭环伺服数控系统的数学模型,对闭环伺服系统的动态、静态性能进行了详细的分析,该研究结果为提高数控加工的控制精度提供了理论基础。 相似文献
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Digitization precision analysis is an important tool to ensure the design precision of machine tool currently.The correlative research about precision modeling and analysis mainly focuses on the geometry precision and motion precision of machine tool,and the forming motion precision of workpiece surface.For the machine tool with complex forming motion,there is not accurate corresponding relationship between the existing criterion on precision design and the machining precision of workpiece.Therefore,a design scheme on machine tool precision based on error prediction is proposed,which is divided into two-stage digitization precision analysis crucially.The first stage aims at the technology system to complete the precision distribution and inspection from the workpiece to various component parts of technology system and achieve the total output precision of machine tool under the specified machining precision;the second stage aims at the machine tool system to complete the precision distribution and inspection from the output precision of machine tool to the machine tool components.This article serves YK3610 gear hobber as the example to describe the error model of two systems and basic application method,and the practical cutting precision of this machine tool achieves to 5-4-4 grade.The proposed method can provide reliable guidance to the precision design of machine tool with complex forming motion. 相似文献
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Qianjian Guo Jianguo Yang Hao Wu 《The International Journal of Advanced Manufacturing Technology》2010,50(5-8):667-675
Thermal errors are the major contributor to the dimensional errors of a workpiece in precision machining. Error compensation technique is a cost-effective way to reduce thermal errors. Accurate modeling of errors is a prerequisite of error compensation. In this paper, four key temperature points of a NC machine tool were obtained based on clustering method. A thermal error model based on the four key temperature points was proposed by using ant colony algorithm-based back propagation neural network (ACO-BPN). The ACO-BPN method improves the prediction accuracy of thermal deformation in the NC machine tool. A thermal error compensation system was developed based on the proposed model, and which has been applied to the NC machine tool in daily production. The results show that the thermal drift in workpiece diameter has been reduced from 33 to 8 μm from its center of tolerance. 相似文献