Quality-fluctuation prediction method for multi-procedure processing process

A technology of quality fluctuation and process, applied in instrumentation, adaptive control, control/regulation system, etc., can solve problems such as poor accuracy

Inactive Publication Date: 2012-12-19
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0007] In order to overcome the shortcomings of the poor accuracy of the existing multi-process quality control

Method used

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  • Quality-fluctuation prediction method for multi-procedure processing process

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Embodiment Construction

[0044] The following examples refer to Figure 1~6 .

[0045] The machining process of a part is composed of p related key quality characteristics, including various quality characteristics of size, shape and position. These p quality characteristics constitute the quality state set of the part, and they are monitored as the process changes , the monitoring of fluctuations in the machining process of parts can be completed. It is assumed that m times are collected during processing, and the sample size of each collection is n.

[0046] Then X ij =(X ij1 , X ij2 ,...,X ijp ) is a p-dimensional vector, representing the p-dimensional quality characteristic of the jth observation value in the i-th sample, where i=1, 2,..., m, j=1, 2,..., n. x ij The first component is obtained, which represents the first quality characteristic, 1=1, 2,...,p. Let the p indicators obey the p-dimensional normal distribution N p [μ, ∑], the mean vector μ and covariance ∑ are unknown, and the ...

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Abstract

The invention discloses a quality-fluctuation prediction method for multi-procedure processing process for solving the technical problem that an existing quality control method for multi-procedure processing process is poor in accuracy. The technical scheme of the quality-fluctuation prediction method includes steps of designing a quality fluctuation model for multi-procedure manufacturing process by means of Bayesian state space; processing noise item in the quality fluctuation model for the manufacturing process by means of wavelet filtering, and eliminating noise; designing multielement quality control graph to monitor processing process on the basis of state value after noise elimination, and realizing control of multielement processing process by designing statistics quantity of multielement fluctuation quantity. By taking ternary quality features as object, when the process is at stable state, the average running step length ARL0 of the control graph is increased to 199.624 from 186.535 in the background technology, and false alarm rate is reduced to 0.2% from 6.73% in the background technology. When the process is out of control and offset quantity is (0,5, 0, and 0), the average running step length ARL1 of the control graph is reduced to 168.354 from 170.651 in the background technology, and the false alarm rate is increased to 15.823% from 14.675% in the background technology.

Description

technical field [0001] The invention relates to a method for predicting quality fluctuations in a processing process, in particular to a method for predicting quality fluctuations in a multi-process processing process. Background technique [0002] In the process of parts processing, multiple quality characteristics need to be controlled at the same time, and these quality characteristics affect each other. Traditional quality control methods, when monitoring and adjusting the quality of the processing process, only perform quality monitoring and control on a single process and a single quality characteristic. The adjustment does not take into account the transmission of errors between multiple processes of parts and the mutual influence between various quality characteristics, resulting in inaccurate monitoring. [0003] Document 1 "Shiyu Zhou, Qiang Huang, Jianjun Shi, "State Space Modeling of Dimensional Variation Propagation in Multistage Machining Process Using Differen...

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Application Information

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IPC IPC(8): G05B13/04
Inventor 张定华王佩陈冰杨青龙李山刘凯任静波
Owner NORTHWESTERN POLYTECHNICAL UNIV
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