| Precast concrete structure is an important structure type under the current wave of construction industrialization.As an important component of precast concrete structure,precast concrete insulated sandwich panel has great influence on the overall quality assurance of the structure by its quality inspection sampling technology and quality control means.Over the years,China's construction industry has been dominated by onsite construction.In the process of industrialization and standardization,the construction industry is bound to face the renewal and progress of construction technology and quality control of precast concrete structures.However,the quality control means and quality acceptance of precast concrete structures are all based on the treatment of cast-in-place concrete structures.In order to adopt more scientific sampling technology,adopt more reasonable and close to the actual production level of quality characteristic value tolerance requirements in the quality inspection of precast concrete structures,and judge the process quality of components more quickly,this paper develops the research of sampling inspection scheme for quality acceptance of precast concrete insulated sandwich panels and its process quality based on process capability index.The main contents of this paper are as follows:(1)Based on the measured data of the quality characteristic values of 4400 pieces of precast concrete insulated sandwich panels in a large precast component factory from 2015 to 2017,this paper obtains the distribution of quality characteristic values in terms of appearance quality,shape size,pre-embedded reservation,openings of doors and windows,reinforcing bars,as well as the acceptance rate of each item.In addition,the data in 2017 are fitted non-linearly based on the gaussian function to reveal the distribution functions and laws of the values of quality characteristics.(2)In this paper,the sampling inspection of components of precast concrete structures is discussed.The theory of sampling inspection by attributes and sampling inspection by variables is introduced,and the sampling method used in the quality acceptance of insulated sandwich panels is analyzed.The drawbacks of current sampling inspection are pointed out.According to the quality characteristics of different inspection items of insulated sandwich panels,the suitable sampling plans by attributes or sampling plans by variables are determined respectively.A method is proposed to determine the sampling plan that the number of samples does not change significantly with the batch size under a certain error limit.For the sampling plan by variables whose tolerance requirement is double combined specification limits,the plan whose population variance is known when the mean value is the quality index or the unqualified rate is the quality index is studied respectively.It provides a reference for the determination of sample size and judgment rules in the sampling inspection of precast components.(3)According to the fitting results of different quality characteristic values,this paper illustrate the deviation distribution interval under different confidence degrees,and provides the tolerance requirements for the quality acceptance standards within double combined specification limits.of precast components and the reference for the range within double combined specification limits.In addition,process quality analysis based on process capability index are carried out according to the requirements of double combined specification limits,so as to judge the product process capability,timely discover the factors affecting product quality,and make the production process in a stable and controllable state.It provides a method for analyzing and controlling the process quality of precast components. |
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