High efficiency cutting force in cylindrical gear scraping

Different from the traditional hobbing and gear shaping processing, NC strong scraping processing is a high-speed general gear processing method, which can process internal gear, external gear, spur gear or helical gear, and the processing time is short. With the continuous progress of NC technology, the problems that hindered its popularization in the past, such as tool life, vibration and servo synchronization, have been gradually overcome in recent years, making the strong tooth scraping technology begin to receive great attention from the gear processing industry.

However, due to the complexity of geometry and kinematics in the process of NC strong scraping, it brings great challenges to its analysis, modeling and simulation. Guo e et al. Studied the design of strong scraping tool, and proposed a simplified simulation calculation method of resultant force; Tachikawa t et al. Associated the harmonic component of normalized cutting force with process cutting speed, and proposed a modeling method that can avoid structural vibration; In order to deal with the complexity of geometry and kinematics, klocke f et al. Adopted a method of plane intersection to numerically approximate the tool workpiece meshing of each time step.

Recently, tapoglou n et al. Used a CAD based simulation model to calculate the undeformed chip and cylindrical gear geometry in strong scraping. Although this method can meet the demand in the accuracy of cutting force prediction, each prediction needs to recalibrate the cutting coefficient, and this method requires a large amount of calculation.

Therefore, using the discrete geometric modeling method of dexel, the author designs a novel method for predicting the cutting force of strong scraping of cylindrical gears, constructs the kinematic model of strong scraping of cylindrical gears, and applies it to the solid modeling based on dexel. The cutting force of each time step is predicted by combining the two-dimensional chip shape with the oblique cutting model; In order to improve the simulation efficiency, part of the workpiece modeling and superposition are used to estimate the cutting force in the whole process; Finally, the feasibility and effectiveness of the prediction method are verified by strong tooth scraping experiment.

In the process of NC strong scraping machining, the cutting force is time-consuming and complex by modeling and finite element simulation. In order to solve this problem, a new method for predicting the cutting force in strong scraping machining is proposed based on dexel discrete geometric modeling, and the application effect of this method is verified in cutting experiments.

The results show that:

(1) compared with the existing methods, some workpiece simulation combined with superposition method is adopted to improve the calculation efficiency;

(2) without recalibrating the cutting coefficient, the predicted results of cutting force on X, y and Z axes are in good agreement with the measured results;

(3) the RMS error of cutting force prediction is reduced by 7 n on average, that is, the accuracy is improved by about 9.7%; The results provide a more accurate theoretical basis for further preventing the early fatigue failure of the blade and optimizing the process parameters of strong scraping.

However, this method still has the limitation that it can not simulate tool / workpiece vibration. Therefore, in the follow-up work, the author will carry out further research on this problem and test the influence of different process parameter combinations on it.

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