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吉美丽 《机械工人(冷加工)》1997,(12):18-19
在装配精度设计中常常会遇到图1a所示齿轮箱的各有关尺寸设计问题,亦即图1b所示装配尺寸链的计算问题。图中封闭环公差T按装配精度要求给定,各组成环l_1、l_2、l_3、l_4基本尺寸设计出来后,要解决的问题是如何给出各组成环的公差及上、下偏差,也 相似文献
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假偏差在修配法装配尺寸链解算中的应用研究 总被引:3,自引:0,他引:3
通过对修配法装配过程的分析,得到一个确定修配的修配环尺寸的新方法--假偏差法,使复杂的分析计算得以简化,且有规律可循,使计算过程、正确。 相似文献
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对复杂装配体的动平衡理论进行了研究,从系统动不平衡类型的确定、复杂装配体动平衡的原理、方法以及系统动不平衡的校正3个方面,分析了复杂装配体动平衡的特点,给出了复杂装配体整机动平衡的理论方法,为复杂装配体整机动平衡试验提供了理论依据。 相似文献
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尺寸链分析是保证机器装配质量的重要方法.在机械部件的装配中,如果装配的零件数目太多、零件之间的尺寸关系复杂,那么装配尺寸链的求解将变得很困难.图论是一个新兴的数学分支,目前在物理学、化学、运筹学、计算机科学、信息论、网络理论以及经济管理等许多领域都得到广泛的应用.在工程机械装配领域也越来越受到人们的重视.基于装配尺寸链的图论模型,运用矩阵理论提出了一种求解复杂装配尺寸链的方法,并结合滚轮部件装配实例,验证了此方法的有效性. 相似文献
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一、虚公差问题的提出及概念在公差中规定上偏差是尺寸允许的最大值,下偏差是尺寸允许的最小值,只要能保证尺寸不大于上偏差,同时又可保证尺寸不小于下偏差,那么这样的尺寸就可满足公差要求。根据上下偏差的大小,公差可分以下三种情况: 1.上偏差大于下偏差上差减下差即公差。根据定义,在上下偏差之间的任意一个尺寸都能满 相似文献
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Optimum manufacturing tolerance to selective assembly technique for different assembly specifications by using genetic algorithm 总被引:2,自引:1,他引:2
M. Siva Kumar SM. Kannan 《The International Journal of Advanced Manufacturing Technology》2007,32(5-6):591-598
Tolerance on parts dimension plays a vital role as the quality of the product depends on sub components tolerance. Thus, precision
products that are manufactured reflect at high manufacturing cost. To overcome this situation, sub components of an assembly
may be manufactured with wider tolerance, measured (using latest technologies like image processing) and grouped in partition
and corresponding group components may be mated randomly. This present work is to obtain an optimum manufacturing tolerance
to selective assembly technique using GA and to obtain maximum number of closer assembly specification products from wider
tolerance sub components. A two components product (fan shaft assembly) is considered as an example problem, in which the
subcomponents are manufactured with wide tolerance and partitioned into three to ten groups. A combination of best groups
is obtained for the various assembly specifications with different manufacturing tolerances. The proposed method resulted
nearly 965 assemblies produced out of one thousand parts with 15.86% of savings in manufacturing cost. 相似文献
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Optimising tolerance allocation for mechanical components correlated by selective assembly 总被引:1,自引:0,他引:1
Selective assembly can enlarge the tolerances of mechanical components for easier manufacturing. However, the non-independent dimensions of correlated components make it difficult to optimise tolerance allocation for an assembly. This paper proposes a solution for this constrained optimisation problem consisting of tolerances and non-independent dimensions as design variables. The approach is to develop a simplified algorithm applying a Lagrange multiplier method to evaluate the optimal tolerances efficiently. The solution is shown to be a global optimum at the given correlation coefficients. The correlation coefficients are key elements in determining the optimal solution, which is demonstrated in the given examples. The results are helpful in designing tolerances for selective assembly.Notation
A
j
coefficient matrix off
j
-
B
i
coefficient of cost function
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C
total manufacturing cost function
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C
i
manufacturing cost function forx
i
-
F
j
thejth dimensional constraint function
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f
j
thejth quadratic constraint function
-
f
quadratic constraint vector
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H
j
thejth Hessian matrix
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J
kj
element ofn×m Jacobian matrix
-
L
Lagrangian
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m
number of assembly dimensions
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n
number of component dimensions
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p
number of equality dimensional constraints
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T
tolerance vector of component dimensions [mm] or [°]
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tolerance ofx
i
[mm] or [°]
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tolerance ofZ
j
[mm] or [°]
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x
component dimension vector
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x
midpoint vector
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x
i
component dimension [mm] or [°]
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x
i
midpoint ofx
i
[mm] or [°]
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Z
j
assembly dimension [mm] or [°]
-
j
confidence coefficient forZ
j
-
i
confidence coefficient forx
i>
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j
given design value ofZ
j
[mm] or [°]
-
Lagrange multiplier vector
-
j
thejth Lagrange multiplier
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*
Lagrange multiplier vector at the optimum solution
-
correlation coefficient forx
i
andx
k
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x
standard deviation vector
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x
*
standard deviation vector at the optimum solution
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x
0
candidate point satisfying the constraintsf(
x
*
)=0
-
standard deviation ofx
i
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