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Process capability analysis method based on supply product truncation normal distribution quality data

A technology of normal distribution and quality data, applied in data processing applications, complex mathematical operations, instruments, etc., can solve problems such as difficulty in effectively supporting process capability review and supplier selection, and inability to estimate the lower confidence limit of the process capability index.

Inactive Publication Date: 2021-01-01
BEIHANG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

However, the traditional process capability analysis method cannot use the truncated quality characteristic data to analyze the process capability, especially it cannot estimate the confidence lower limit of the process capability index, so it cannot analyze and evaluate the process capability based on the objective quality data of the supplied products. Difficult to effectively support process capability review and supplier selection

Method used

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  • Process capability analysis method based on supply product truncation normal distribution quality data
  • Process capability analysis method based on supply product truncation normal distribution quality data
  • Process capability analysis method based on supply product truncation normal distribution quality data

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Embodiment Construction

[0075] The following takes the electro-hydraulic servo valve as an example, combined with figure 1 , the present invention will be described in further detail.

[0076] Problem background:

[0077] As the core component of the servo system, the electro-hydraulic servo valve has been widely used in the control and adjustment of aerospace vehicles. The spool and the sleeve are two key parts of the servo valve and must be used in pairs. According to engineering experience, if the gap between the valve core and the sleeve is too large, the leakage of liquid can be reduced, but if the gap is too small, the sliding speed of the slide valve will be affected. Therefore, the gap length between the spool and sleeve is a critical quality characteristic of a servo valve. According to the company's technical requirements, the specification limit of the gap length is (LSL, USL) = (30μm, 50μm). This means that all clearances between the spool and sleeve should be within specification lim...

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Abstract

The invention provides a process capability analysis method based on supply product truncation normal distribution quality data. The process capability analysis method comprises the following steps: 1, setting truncation quality characteristics measured by a user; 2, carrying out parameter point estimation based on maximum likelihood estimation; 3, obtaining pseudo complete data based on a data filling calculation method; 4, calculating the confidence lower limit of the process capability index Cpk; According to the invention, the process capability analysis is carried out based on the cut-offquality data of the supply product, and the obtained process capability analysis result is more credible than the process capability conclusion provided by the supplier. According to the method, theprocess capability analysis is carried out based on quantile filling and the generalized confidence interval, not only is the point estimation of the process capability given, but also the confidencelower limit of the process capability is given, the process capability evaluation and recheck can be guided more accurately, and the supplier management decision can be better guided. The method is scientific and good in manufacturability and has wide application and popularization value.

Description

technical field [0001] The invention proposes a process capability analysis method based on truncated normal distribution quality data of supplied products. In view of the outstanding characteristics of the supplied product quality data showing a truncated normal distribution, this method comprehensively uses the maximum likelihood estimation of the truncated normal distribution, the data filling algorithm and the method of the generalized pivot quantity, and the offset process capability index C pk Make an estimate. It can accurately estimate the confidence lower limit of the process capability index based on the quality data of the supplied product measured by the customer (the data is truncated by the specification limit), objectively evaluate the process capability level of the production line of the supplied product, and effectively evaluate the process capability level declared by the supplier. Review to effectively support supplier process capability evaluation and sel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06Q10/06G06F17/18
CPCG06Q10/06395G06F17/18
Inventor 杨军孟繁兵孔雪峰
Owner BEIHANG UNIV