Method and device for predicting assembly dimension and form and position precision of product

Abstract

The invention provides a method and a device for predicting assembly dimension and form and position precision of a product. The method includes the steps: acquiring design data and measurement data for the assembly dimension and form and position precision of the product; mapping the design data to sextuple deviation random vectors expressed by a sextuple statistical model and the mapping measurement data to sextuple deviation confirmation vectors expressed by the sextuple statistical model; according to the sextuple deviation random vectors and the sextuple deviation confirmation vectors, constructing a sextuple deviation statistic model for the assembly dimension and form and position precision of the product, and solving mean vectors, variances and a covariance matrix; constructing an assembly deviation directed graph of the product according to the sextuple deviation statistic model and an assembly datum and assembly restrictions of the product; realizing accumulation of the assembly dimension and form and position precision of the product according to the assembly deviation directed graph; and predicating the assembly precision of the product according to cumulants of the assembly dimension and form and position precision of the product. Using the scheme of the method can lead analysis of the assembly precision of the product to be more precise.

Description

technical field [0001] The invention relates to the field of mechanical engineering, in particular to a method and device for predicting product assembly dimensions and shape and position accuracy. Background technique [0002] Product assembly parameters, such as size and shape accuracy, are of great significance for tolerance design, product assembly accuracy prediction, and assembly accuracy assurance. The expression of product size and shape accuracy, and the accumulation of size and shape accuracy are the basic work of tolerance design and product assembly accuracy prediction. [0003] However, in the precision expression of the size and shape of the existing products, there are the following problems: [0004] (1) The expression between product size and shape and position accuracy is not uniform. In the current GPS (Geometric Technical Specifications for Products) standard, the specification and inspection of limits and fits, and geometric accuracy are explained sepa...

AI Technical Summary

Problems solved by technology

[0010] However, the deviation drift model completely relies on a new solid modeling system to express dimensions and tolerances, which has great limitations in software implementation

Since most of the current CAD systems are still based on ideal geometry for entity representation, the practicability of the deviation drift model is not strong

[0011] In terms of product size or shape and position accuracy accumulation, there are mainly: 1. Dimensional chain model, which can effectively solve the problem of dimensional accuracy accumulation, but does not involve collaborative analysis of shape and position accuracy; 2. Changing geometric constraint network model, firstly introducing constraints The concept of network, used to consider the accumulation of shape and position accuracy, provides an effective way for the transfer of shape and position deviations, but does not consider the positive and negative accumulation of deviations; 3. The state space transfer model is mainly used for the second type of assembly The accumulation of assembly accuracy and the establishment of the state space transfer model are mostly based on the 3-2-1 clamping and positioning method for thin plate parts, and the deviation expression and transfer model are not universal

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