A method for dimensional quality control of automotive parts comprises the following steps:
(1) Measurement data sampling: the dimensional data of the parts are collected by the line side gage measurement and the coordinate measuring machine, and the measured data results are sent to the central computer for storage and processing;
(2) Measurement data analysis: The measurement data of the line side detector and the measurement data of the coordinate measuring machine are processed respectively. For the measurement data of the line side detector, the mean-range chart is analyzed to obtain the mean-range control chart; For the measurement data of the CMM, the following steps are adopted: (a) The exponential weighted moving average method is used to calculate the error separation, and the trend data and fluctuation data are obtained; (b) Trend analysis charts based on trend data: volatility quality assessment based on volatility data; (c) Using the fluctuation data after data separation to obtain stage 6 values and size process capability evaluation;
(3) Problem identification: According to mean-range control chart, trend analysis chart, stage 6 values and size process capability evaluation
Row problem identification;
(4) Principal component analysis: gives a set of parts analysis data changes of the main model; Correlation analysis: The number of measurement points
The similarity between the trend of data is analyzed and calculated, and the correlation between the dimensions of different parts is analyzed.
(5) Cause determination: combine data analysis and process knowledge model to determine the cause;
(6) Improvement measures: Put forward short-term measures and long-term measures according to the identified reasons and carry out implementation tracking, timely update the tracking status until the defects are suppressed and the problems are solved.
In the case of off-line measurement, sampling time and sample size are very important for quality assessment. According to the commonly used measurement conditions, the invention provides a sampling method suitable for off-line measurement quality assessment of the parts production plant, and samples according to different evaluation requirements
This method can extract assembly dimension quality information timely and effectively, and carry out accurate evaluation. The evaluation index given can evaluate the dimensional quality and dimensional technological capability of the parts. Through the evaluation and analysis, the basis can be given for the evaluation of the tooling condition level of the parts production line in the trial production stage. Due to the timely and accurate feedback, the dimensional quality problem solving cycle can be effectively shortened and the supply speed of new parts can be accelerated. And in the normal production period, can effectively monitor the state of the production line, timely find and solve problems. This paper compares the control and analysis of size quality in the assembly process of mechanical parts, which is suitable for mass production and small sample testing.
