Locally parallel dimension chain error acquisition method influenced by geometric structure

Abstract

The invention belongs to the field of mechanical manufacturing product assembling error acquisition and discloses a locally parallel dimension chain error acquisition method influenced by a geometricstructure. The method comprises the steps that (a) parallel cooperation of a shaft and two holes is equivalent to a feature of a cylinder, a spinor corresponding to the cylinder is established, and establishment of a Jacobian spinor model is completed; (b) corresponding contact points and analysis points on the shaft and the two holes and an offset size and an offset direction of the analysis points after parallel cooperation of the shaft and the two holes are acquired, and the type of the Jacobian spinor model is determined according to the offset size and the offset direction of the analysispoints; and (c) a geometric relation between all the contact points and the analysis points is obtained, values of a translation vector parameter and a rotation vector parameter in the spinor T are solved and acquired, and the Jacobian spinor model is obtained through the values. Through the method, acquisition of locally parallel dimension chain tolerance information with a leverage effect of the geometric structure is realized, final transmission equipment assembling error precision is improved, an error is lowered, and the method is convenient to use.

Description

technical field [0001] The invention belongs to the field of obtaining assembly errors of mechanical manufacturing products, and more particularly relates to a method for obtaining errors of local parallel dimension chains affected by geometric structures. Background technique [0002] With the development of modern manufacturing industry, mechanical products are becoming more and more super-large, extremely miniaturized, and precise. The structure of the product and its assembly error size chain transmission relationship are becoming more and more complicated. Subject to component design tolerances. Especially for large-scale equipment, the transmission relationship of assembly error dimensional chain is complicated, and there are many local parallel dimensional chains. Once the complex local parallel dimensional chain of the assembly itself is ignored, the error in the final assembly error calculation result will be large, and it is difficult to carry out accurate and reas...

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Problems solved by technology

However, this kind of tolerance modeling method is only suitable for the transfer of a single series dimension chain, and cannot consider the case of complex transfer paths such as partial parallel connections

Such as the Jacobian matrix, although it can well simulate the cumulative process of error transfer along the dimensional chain in the assembly, it cannot simulate the transfer process of expression errors along the parallel dimensional chain

The main reasons are as follows: first, the Jacobian matrix used to represent the transfer of parallel dimension chains is quite complicated; second, there is no relevant research focusing on the expression of the screw model of parallel connection pairs; third, there are many types of parallel connection pairs, and each A type of parallel connection may have different solution methods

For example, the screw parameters of a certain type of parallel connection pairs can be obtained through intersection and union operations, but this method is not suitable for those parallel connection pairs that are affected by the geometry of the parts

[0004] The above tolerance analysis methods are not suitable for solving the local parallel dimensional chain with the geometric leverage effect, and this kind of connection pair exists in a large number of transmission equipment. Once this local parallel connection pair is ignored, it will lead to the final transmission equipment The accuracy of assembly error is reduced, and the error is too large; therefore, it is urgent to study a method to solve this parallel connection pair with geometric leverage effect to improve the calculation accuracy of three-dimensional tolerance analysis technology in complex transmission equipment; at present, there are few related literatures for For its solution, most methods such as the Jacobian screw matrix can only establish an error transfer model for a single series dimensional chain to model and analyze assembly errors. However, this method of simplifying the parallel dimensional chain and only considering a single series dimensional chain will The result of the final assembly error calculation is inaccurate; the only method currently available for local parallel dimensional chains is only to perform intersection and union calculations on the overlapping tolerance areas of local parallel connections; The size is related, that is, the local parallel size chain affected by the geometric structure of the part cannot be solved by simple intersection and union operations

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