Construction method of time-varying dynamic model for high-feed turning external thread parts

Abstract

The invention relates to a construction method of a time-varying dynamic model for high-feed turning of external thread members; the method comprises the steps of I, using, based on the Rayleigh beam vibration theory, a nose track spiral line equation as an integration object to solve a workpiece strain energy and kinetic energy equation for a tool that performs cutting along the nose spiral track; II, considering, based on an established tool instant cutting force model, the impact of 'quasi-regeneration effect' upon instant cutting force for turning a large-pitch thread member so as to correct the existing instant cutting force model and perform numerical solution; III, describing boundary conditions of thread member turning through a vibration mode function, and performing solving; IV, establishing and solving a workpiece vibration model according to the virtual work principle and the method of separation of variables. The large-pitch external thread member vibration equation established herein is capable of predicting a sharply varying position of a workpiece upon vibration and displacement, and can assist in adjusting and optimizing parameters of a machining process for large-pitch thread members.

Description

technical field [0001] The invention relates to a method for establishing a vibration model of an external threaded part during processing, in particular to a method for establishing a time-varying dynamics model for high-feed turning external threaded parts. Background technique [0002] High-feed cutting is widely used in high-efficiency cutting of key parts of large-scale equipment represented by large-pitch screws. In the high-feed and long-stroke machining process alternately along multiple directions, the dynamics and tribology of the process system have chaotic characteristics, the cutting vibration characteristics are changeable, the machining accuracy and surface integrity of the left and right thread surfaces and the high performance of the tool It is difficult to guarantee service, which becomes the bottleneck restricting the substantial improvement of high-feed cutting efficiency. [0003] Although the existing studies have established various vibration models o...

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Problems solved by technology

In the high-feed and long-stroke machining process alternately along multiple directions, the dynamics and tribology of the process system have chaotic characteristics, the cutting vibration characteristics are changeable, the machining accuracy and surface integrity of the left and right thread surfaces and the high performance of the tool It is difficult to guarantee service life, which becomes the bottleneck restricting the substantial improvement of high-feed cutting efficiency

[0003] Although the existing studies have established various vibration models of rotating workpieces under the action of moving loads, they only simplify the processing object to polished rods. The pitch of a machined thread is only modeled along the axial distance of the workpiece, which does not reflect the actual machining path of the thread machining, which restricts the analysis of the machining accuracy and surface morphology of the thread raceway through the established vibration model. Research

At the same time, in the study of the instantaneous cutting force of large-pitch threaded parts, the technological characteristics of axial layered cutting due to the need for thread machining have not been considered. Adding the "regeneration-like effect" to the cutting force model does not reveal the processing characteristics. The nature of the chatter phenomenon that occurs during

[0004] In view of the particularity of high-feed cutting technology and assembly precision requirements of screws and nuts, during the cutting process, the dynamic response of the large-pitch screw system is more complicated than that of shaft workpieces under general cutting methods.

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