Adaptive Cutting Force Control with a Hybrid Axis System

2013 ◽  
Vol 7 (4) ◽  
pp. 378-384 ◽  
Author(s):  
Berend Denkena ◽  
◽  
Felix Flöter

Cutting forces have a major effect on the results of a machining process. High loads on the tool can lead to surface geometry and surface roughness that are less than optimal. However, due to its high implementation costs, cutting force control is not often used on milling machines. The paper presents a new approach by integrating a hybrid axis system in the force control loop. This offers a more dynamic and accurate way to influence cutting forces, but it also results in a more complex control problem. Therefore, how the nonlinear and time-varying characteristics of the cutting process can be modeled and considered for an automated operation is comprehensively shown. The interaction of process estimation and control is demonstrated with a PID-Control structure. Experimental results are presented.

2009 ◽  
Vol 3 (4) ◽  
pp. 445-456 ◽  
Author(s):  
Atsushi Matsubara ◽  
◽  
Soichi Ibaraki

Much research has gone into machining process monitoring and control. This paper reviews monitoring and control schemes of cutting force and torque. Sensors to measure cutting force and torque, as well as their indirect estimation, are reviewed. Feedback control schemes and model-based feedforward scheduling schemes of cutting forces, as well as tool path optimization schemes for cutting force regulation, are reviewed. The authors’ works are also briefly presented.


2010 ◽  
Vol 142 ◽  
pp. 209-213
Author(s):  
Tong Wu ◽  
Can Zhao ◽  
Guang Bin Bu ◽  
Dun Wen Zuo

In this paper, test method was used to study the distribution of cutting force while blade machined with 4-axis and 5-axis NC program. The main difference between the two program was given. The difference of machining forms between 4-axis and 5-axis has led to their cutting forces distribution were different. The change of cutting force in 4-axis machining was large while the 5-axis machining was relatively stable. 5-axis cutting force had no impact comparing with 4-axis, which is more suitable for blade machining.


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.


2018 ◽  
Vol 764 ◽  
pp. 279-290
Author(s):  
X.D. Wang ◽  
W.L. Ge ◽  
Y.G. Wang

The characteristics of cutting forces vibration and its effects to the hole quality in reaming aluminum cast alloy using a poly-crystalline diamond (PCD) step reamer in dry and wet conditions were studied. First, centrifugal force vibration model of the PCD step reamer during machining process was established and through the analysis of the model, it can be concluded that the maximum amplitude of the vibration is positively related to the angular velocity of the reamer. Then, thrust force and cutting torque were measured by a Kistler Dynamometer during reaming process and these vibration frequency and amplitude were analyzed by fast Fourier transformation (FFT). Hole quality was evaluated by hole diameter and surface roughness. Results show that, as the spindle speed increases, the stability of thrust force and cutting torque deteriorates gradually, and there was a severe vibration in the cutting force and the surface roughness when the spindle speed reached 10000 rpm in wet and 7000 rpm in dry cutting conditions. Compared the variation of hole surface roughness and vibration characteristic of cutting forces, it can be observed that the trends are very consistent, the surface roughness deteriorates when cutting forces become unstable. Therefore,the cutting forces stability was an important factor that influence the hole quality. Cutting fluid has a positive effect to stabilize the reaming process and was beneficial to improve the hole quality.


2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
A. H. El-Sinawi

This work presents a comprehensive approach to the control of tool's position, in the presence of machine tool structure vibration, nonlinear cutting force, and random tool vibration due to random distribution of microhardness of workpiece material. The controller is combination of Proportional and linear quadratic gaussian- (P-LQG-) type constructed from an augmented model of both tool-actuator dynamics and a nonlinear dynamic model relating tool displacement to cutting forces. The latter model is obtained using black-box system identification of experimental orthogonal cutting data in which tool displacement is the input and cutting force is the output. The controller is evaluated and its performance is demonstrated.


Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 840 ◽  
Author(s):  
Rashid Ali Laghari ◽  
Jianguang Li ◽  
Mozammel Mia

Cutting force in the machining process of SiCp/Al particle reinforced metal matrix composite is affected by several factors. Obtaining an effective mathematical model for the cutting force is challenging. In that respect, the second-order model of cutting force has been established by response surface methodology (RSM) in this study, with different cutting parameters, such as cutting speed, feed rate, and depth of cut. The optimized mathematical model has been developed to analyze the effect of actual processing conditions on the generation of cutting force for the turning process of SiCp/Al composite. The results show that the predicted parameters by the RSM are in close agreement with experimental results with minimal error percentage. Quantitative evaluation by using analysis of variance (ANOVA), main effects plot, interactive effect, residual analysis, and optimization of cutting forces using the desirability function was performed. It has been found that the higher depth of cut, followed by feed rate, increases the cutting force. Higher cutting speed shows a positive response by reducing the cutting force. The predicted and experimental results for the model of SiCp/Al components have been compared to the cutting force of SiCp/Al 45 wt%—the error has been found low showing a good agreement.


Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4031 ◽  
Author(s):  
Ming Luo ◽  
Zenghui Chong ◽  
Dongsheng Liu

In the milling process, cutting forces contain key information about the machining process status in terms of workpiece quality and tool condition. On-line cutting force measurement is key for machining condition monitoring and machined surface quality assurance. This paper presents a novel instrumented working table with integrated polyvinylidene fluoride (PVDF) thin-film sensors, thus enabling the dynamic milling force measurement with compact structures. To achieve this, PVDF thin-film sensors are integrated into the working table to sense forces in different directions and the dedicated cutting force decoupling model is derived. A prototype instrumented working table is developed and validated. The validation demonstrates that profiles of the forces measured from the developed instrumented working table prototype and the dynamometer match well. Furthermore, the milling experiment results convey that the instrumented working table prototype could also identify the tool runout due to tool manufacturing or assembly errors, and the force signal spectrum analysis indicates that the developed working table can capture the tool passing frequency correctly, therefore, is suitable for the milling force measurement.


2019 ◽  
Vol 57 (6) ◽  
pp. 773 ◽  
Author(s):  
Hai Ha Thanh

This article presents analysis of inverse dynamics of serial manipulators in milling process. Cutting forces and complicated motion involve to difficulties in solving dynamics problems of robots. In general, cutting forces are determined by using empirical formulas that lead to errors of cutting force values. Moreover, the cutting forces are changing and causing vibration during machining process. Errors of cutting force values affect to the accuracy of the dynamic model. This paper proposes an algorithm to compute the cutting forces based on the feedback values of the robot's motion.    


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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