共查询到20条相似文献,搜索用时 62 毫秒
1.
针对三角网格曲面五轴数控加工中普遍使用的截平面法加工行距较窄、加工效率较低的问题,提出一种可变行距的宽行加工刀具路径生成方法。首先,以三角网格数据重构为基础,提出一种基于KdTree网格区域划分的求交算法,实现了网格数据点的快速获取;然后,分析环形刀及三角网格曲面的几何特性,在无曲率干涉条件下提出通过改变侧倾角并优化前倾角使刀具有效切削半径最大化的方法,获得以加工行距最大化为优化目标的最佳刀具倾角组合;最后,结合三角网格曲面的特性建立一种环形刀刀具离散模型,并提出了相应的干涉检测与修正方法。仿真实验表明,在相同加工条件下,本文加工行距优化方法较现有方法明显增大了加工行距、提高了加工效率,而且所提出的刀具干涉与修正处理方法能有效避免局部刀底干涉及全局刀杆干涉现象的发生。 相似文献
2.
3.
4.
在曲面加工过程中,刀具路径是影响切削效率和加工质量的关键因素之一;在CAM软件中,可供选择的刀具路径较多。文章主要介绍平行铣、环形铣、等高外形铣三种常用的曲面加工刀具路径特点和适用范围以及对曲面加工精度的影响。 相似文献
5.
五轴联动机床是数控加工机床中的高端设备,刀具除包含常规直线运动外还包含绕轴线转动,能够以任意角度到达作业空间的任何位置。五轴联动机床除了加工精度非常高之外,还能加工自由曲面等复杂表面,广泛一用于航天、潜艇等高要求的领域。文章对五轴联动机床相关特点等进行相应介绍。 相似文献
6.
7.
8.
9.
10.
由于自由曲面的几何复杂性,所以自由曲面相对来说较难加工。工作主要集中在对于精加工操作的刀位轨迹的步距进行优化。给定任意的自由曲面,并且生成了加工的G&M机器代码,在三坐标数控机床上利用球头铣刀进行曲面加工。在偏置曲面上产生刀具路径规划。考虑到曲面的强度和单一性因素,所以生成等间隔平面往复式刀具路径。所产生的刀具路径要符合在给定的曲面上所规定的误差。输入的是.prt格式的曲面实体模型,输出的是包含加工代码的.txt文件。最后将给出实例用来证明本算法的有效性。 相似文献
11.
12.
13.
14.
15.
《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
16.
17.
感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
18.
19.
The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献
20.
从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献