An Optimal Quality Control Method for Small Samples Based on Process Capability

A quality control method and technology of small samples, applied in adaptive control, general control system, control/regulation system, etc., can solve the problems of increasing false alarms or taking false alarms, large deviation of results, ignoring the value of small samples, etc. To achieve the effect of improving product quality and good control effect

Inactive Publication Date: 2017-02-15
方志耕
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  • Abstract
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  • Claims
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Problems solved by technology

Because the small sample itself has great volatility, this means that the inappropriate selection of small samples directly leads to large deviations in the results during correction, increasing the possibility of false alarms or false alarms
In the previous models, no explanation was given on how to take a small sample, and it was believed that the larger the sample, the better even though it was a small sample, while ignoring the value of small samples for correction

Method used

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  • An Optimal Quality Control Method for Small Samples Based on Process Capability
  • An Optimal Quality Control Method for Small Samples Based on Process Capability
  • An Optimal Quality Control Method for Small Samples Based on Process Capability

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Embodiment Construction

[0026] The present invention relates to a small sample optimal quality control method based on process capability, which is characterized in that it comprises the following steps:

[0027] (1) Determine the objective function: Among them, z is the optimization constraint target value, R is the sample range, T is the standard tolerance set in advance, m is the number of sample groups, is the average range;

[0028] (2) Determine the constraints: For products produced in the same process, their ranges are subject to normal distribution

[0029] Assuming that the number of samples in each group is 4,

[0030] So After being standardized, it obeys the Student's distribution, that is, Then calculate the confidence interval according to the given confidence 1-α;

[0031] When the range is smaller, it indicates that the product is more stable, then when

[0032] A confidence interval is obtained as

[0033] Among them, R is the sample range, S is the standard deviati...

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Abstract

The invention discloses a small-sample optimal quality control method based on a process capability. The method includes the following steps: 1. determining an objective function; 2. determining constraint conditions; 3. determining a concrete form of a model. Based on Bayes correction, the method studies a small sample which has utilization values to the correction and screens and discriminates the small sample through construction of a rapid judgment model and judges a process quality problem and thus under a condition that the process quality is known, a process quality control chart is designed to monitor a production process and the control chart is continued to be corrected according to a produced small sample and finally a better control effect can be achieved finally. At the same time, setting of a benchmark table also provides a reference for judgment of the process capability problem through use of the small sample.

Description

technical field [0001] The invention relates to a small sample optimal quality control method based on process capability. Background technique [0002] At present, the use of small samples for process quality inspection has always been a key issue that many scholars are committed to solving. The reason why it is so valued is that it has very important practical application value in production. However, small samples are unstable, so it is difficult to give a specific and general theoretical method. The idea of ​​process quality management has a long history, and its core idea is to use process capability instead of unqualified rate to judge whether the product meets the production requirements. In the 1920s, American scholar Shewhart [1] proposed the concept of process control and the method of realizing process control, and drew a process quality control chart, which is the Shewhart control chart that is still widely used today. When Zhang Gongxu and Lu Chunshan [2-3] i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G05B13/04
Inventor 方志耕李维东陈洪转陈顶
Owner 方志耕
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