Monitoring Cutting Forces In Turning: A Model-Based Approach

2000 ◽  
Vol 124 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Jeffrey L. Stein ◽  
Kunsoo Huh

The importance of monitoring the cutting force in the turning process has been well recognized in industry as well as in the open literature. This paper proposes a cutting force monitoring approach that does not utilize force dynamometers but rather estimates the cutting force based on the spindle motor current and speed as well as a model that relates these measurements to the cutting force. Motor current and speed can not only be inexpensively and reliably measured but, in addition, can be shown, along with the properly chosen model for the model-based estimator, to accurately estimate the cutting force. This method is demonstrated on a CNC lathe and its advantages and limitations are discussed.

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Xiaoping Liao ◽  
Zhenkun Zhang ◽  
Kai Chen ◽  
Kang Li ◽  
Junyan Ma ◽  
...  

Micro-end milling is in common use of machining micro- and mesoscale products and is superior to other micro-machining processes in the manufacture of complex structures. Cutting force is the most direct factor reflecting the processing state, the change of which is related to the workpiece surface quality, tool wear and machine vibration, and so on, which indicates that it is important to analyze and predict cutting forces during machining process. In such problems, mechanistic models are frequently used for predicting machining forces and studying the effects of various process variables. However, these mechanistic models are derived based on various engineering assumptions and approximations (such as the slip-line field theory). As a result, the mechanistic models are generally less accurate. To accurately predict cutting forces, the paper proposes two modified mechanistic models, modified mechanistic models I and II. The modified mechanistic models are the integration of mathematical model based on Gaussian process (GP) adjustment model and mechanical model. Two different models have been validated on micro-end-milling experimental measurement. The mean absolute percentage errors of models I and II are 7.76% and 6.73%, respectively, while the original mechanistic model’s is 15.14%. It is obvious that the modified models are in better agreement with experiment. And model II performs better between the two modified mechanistic models.


2015 ◽  
Vol 799-800 ◽  
pp. 366-371 ◽  
Author(s):  
Deuanphan Chanthana ◽  
Somkiat Tangjitsitcharoen

The roundness is one of the most important criteria to accept the mechanical parts in the CNC turning process. The relations of the roundness, the cutting conditions and the cutting forces in CNC turning is hence studied in this research. The dynamometer is installed on the turret of the CNC turning machine to measure the in-process cutting force signals. The cutting parameters are investigated to analyze the effects of them on the roundness which are the cutting speed, the feed rate, the depth of cut, the tool nose radius and the rake angle. The experimentally obtained results showed that the better roundness is obtained with an increase in cutting speed, tool nose radius and rake angle. The relation between the cutting parameters and the roundness can be explained by the in-process cutting forces. It is understood that the roundness can be monitored by using the in-process cutting forces.


2014 ◽  
Vol 541-542 ◽  
pp. 1419-1423 ◽  
Author(s):  
Min Zhang ◽  
Hong Qi Liu ◽  
Bin Li

Tool condition monitoring is an important issue in the advanced machining process. Existing methods of tool wear monitoring is hardly suitable for mass production of cutting parameters fluctuation. In this paper, a new method for milling tool wear condition monitoring base on tunable Q-factor wavelet transform and Shannon entropy is presented. Spindle motor current signals were recorded during the face milling process. The wavelet energy entropy of the current signals carries information about the change of energy distribution associated with different tool wear conditions. Experiment results showed that the new method could successfully extract significant signature from the spindle-motor current signals to effectively estimate tool wear condition during face milling.


Author(s):  
Bryan Javorek ◽  
Barry K. Fussell ◽  
Robert B. Jerard

Changes in cutting forces during a milling operation can be associated with tool wear and breakage. Accurate monitoring of these cutting forces is an important step towards the automation of the machining process. However, direct force sensors, such as dynamometers, are not practical for industry application due to high costs, unwanted compliance, and workspace limitations. This paper describes a method in which power sensors on the feed and spindle motors are used to generate coefficients for a cutting force model. The resulting model accurately predicts the X and Y cutting forces observed in several simple end-milling tests, and should be capable of estimating both the peak and average force for a given cut geometry. In this work, a dynamometer is used to calibrate the feed drive power sensor and to measure experimental cutting forces for verification of the cutting force model. Measurement of the average x-axis cutting forces is currently presented as an off-line procedure performed on a sacrificial block of material. The potential development of a continuous, real-time force monitoring system is discussed.


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