Precise Cutting Force Estimation by Hybrid Estimation of DC/AC Components

2020 ◽  
Author(s):  
Taiki Sato ◽  
Shuntaro Yamato ◽  
Yasuhiro Imabeppu ◽  
Naruhiro Irino ◽  
Yasuhiro Kakinuma
Keyword(s):  
Cutting Force ◽  
Thrust Force ◽  
End Milling ◽  
Moving Average ◽  
Low Frequency ◽  
Friction Model ◽  
Ball Screw ◽  
Estimation Accuracy ◽  
Force Estimation ◽  
Feed Direction

Abstract External sensor-less cutting force estimation using a load-side disturbance observer (LDOB) has potential to estimate the cutting force with high accuracy in both feed and cross-feed directions. However, the accuracy of its low frequency components in feed direction decrease due to effect of the friction and heat of a ball-screw-driven stage. In this study, DC and AC components of the cutting force is estimated by different methods; friction-compensated motor thrust force and LDOB, and the cutting force was estimated in real time by hybridizing them. In particular, regarding the friction model, the dynamic and static characteristics of the friction force in each axis (X, Y, Z) were identified from the idling test results. In addition to the model that depends on the velocity, the characteristics of the friction that depend on the position was also identified and considered when compensating for the motor thrust force. Then, a simple moving average filter with an appropriate window length is applied to the cutting force by LDOB and motor thrust force, and the DC component error of LDOB is corrected by that of motor thrust force. The validity of the proposed method was evaluated through end-milling tests. The experimental results showed that estimation accuracy of cutting force using the proposed method can be greatly improved in feed directions. On the other hand, in cross-feed direction, the cutting estimation was performed using the conventional LDOB.

Sensorless Monitoring of Cutting Force Variation With Fractured Tool Under Heavy Cutting Condition

2016 ◽  
Author(s):  
Yuki Yamada ◽  
Yasuhiro Kakinuma ◽  
Takamichi Ito ◽  
Jun Fujita ◽  
Hirohiko Matsuzaki
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Moving Average ◽  
Cutting Condition ◽  
Force Estimation ◽  
Signal Processing Technique ◽  
Tool Condition ◽  
Force Variation ◽  
Monitoring Performance ◽  
Peak Value

Cutting force is widely regarded as being the one of the most valuable information for tool condition monitoring. Considering sustainability, sensorless cutting force monitoring technique using inner information of machine tool attracts attention. Cutting force estimation based on motor current is one of the example, and it is applicable to detection of tool breakage with some signal processing technique. However, current signal could not capture fast variation of cutting force. By improving monitoring performance of cutting force, the hidden tool condition information is more accessible. In this study, monitoring performance of cutting force variation due to tool fracture was enhanced by using multi-encoder-based disturbance observer (MEDOB) and simple moving average. Friction force and torque which deteriorate monitoring performance was eliminated by moving average. First, monitoring accuracy of cutting force was verified through end milling test. Next, local peak value of estimated cutting force was extracted and the ratio of neighboring peak value was calculated to capture the tool fracture. Estimated value using MEDOB could capture the variation resulting from tool fracture.

Minimum Time Trajectory Planning Along Specified Tool Path With Consideration of Cutting Force Constraint and Feed Drive Dynamics

Manufacturing ◽  
2002 ◽  
Author(s):  
Nejah Tounsi ◽  
Trevor E. Bailey ◽  
Mohamed A. Elbestawi
Keyword(s):  
Cutting Force ◽  
Feed Rate ◽  
Tool Path ◽  
End Milling ◽  
Low Frequency ◽  
Minimum Time ◽  
Force Model ◽  
Modeling And Analysis ◽  
Feed Drive ◽  
Drive Dynamics

This paper proposes an Optimized Feed Scheduling Strategy (OFSS). This strategy integrates the feed drive dynamics with the minimum-time trajectory planing to achieve the desired feed rate at the appropriate tool position along specified tool path. It optimizes the use of the feed drive capabilities and provides good tracking of the cutting geometry variations. The feed scheduling is applied to maintain near-constant cutting force magnitude. An integrated geometric and mechanistic force model is used to estimate the in-cut geometry and the cutting force. A methodology based on time series modeling and analysis is proposed to identify the low frequency feed drive dynamics. The resulting model is applied as an acceleration/deceleration processor (Acc/Dec) to relate the actual feed rate to the commanded feed rate specified in the G-Code file. The effectiveness of the OFSS is analyzed using ball end milling operations. Its performance in terms of productivity and machining safety is assessed based on comparison with other feed scheduling techniques where the trajectory planing does not consider the feed drive dynamics.

Sensorless Cutting Force Estimation in Large Scale Ball-Screw-Driven Machine Tool

2016 ◽  
Vol 1136 ◽  
pp. 645-650 ◽  
Author(s):  
Yuki Yamada ◽  
Yasuhiro Kakinuma ◽  
Takamichi Ito ◽  
Jun Fujita ◽  
Atsushi Tada ◽  
...  
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Control Systems ◽  
Friction Force ◽  
Large Scale ◽  
Metal Cutting ◽  
Estimation Method ◽  
Ball Screw ◽  
Force Estimation ◽  
Non Linear

The cutting force is widely regarded as being the most valuable information when observing a metal cutting process. Considering practicability, indirect cutting force measurement methods which forego additional sensors have been studied in academic field. Disturbance observer-based cutting force estimation method was known as a typical example, and its validity was verified in linear motor driven stage. However, accurate cutting force estimation is still difficult in ball-screw driven stage because of non-linear friction and resonance. In this study, feasibility of sensorless cutting force estimation was verified by using large scale commercial machine tool. Considering that the motion of rotational and translational elements independently, cutting force observer (CFOB) was modeled as two-degree-of-freedom system. The CFOB was mounted to control systems of both stage and spindle head which were driven by ball-screw and servo motor. While friction force and torque have non-linear position dependence, high repeatability was confirmed. Thus, their non-linearity could be attenuated by identifying friction force and torque beforehand machining operation. From experimental results, it was shown that tooth-pass frequency and second harmonics component of the cutting forces could be estimated accurately by using the CFOB. The results were acquired from control systems of both stage and spindle head.

Sensorless Cutting Force Estimation in Ball-Screw-Driven System Using Triple-Inertia Model

2014 ◽  
Vol 1017 ◽  
pp. 619-623
Author(s):  
Yuki Yamada ◽  
Yasuhiro Kakinuma ◽  
Takamichi Ito ◽  
Jun Fujita ◽  
Makoto Sawazaki ◽  
...  
Keyword(s):  
Cutting Force ◽  
Estimation Method ◽  
Ball Screw ◽  
Accurate Estimation ◽  
Force Estimation ◽  
Resonance Frequencies ◽  
Driven System ◽  
Output System ◽  
Simulation Results ◽  
Inertia Model

In this paper, we propose cutting-force-estimation method for a ball-screw-driven system using triple inertia model. In many cases, dual-inertia model is applied to describe the dynamic behavior of the ball-screw-driven system. In this paper, triple-inertia model is applied and cutting force was estimated without additional sensors, such as dynamometer. The cutting force observer is designed, regarding the ball-screw-driven system as two input and three output system. Simulation results indicate that the proposed method enables accurate estimation around the resonance frequencies. Experimental results showed that the proposed method could monitor external force without being interrupted by the inertia forces.Nomenclature

scholarly journals Research on the Relationship between Cutting Force and Machined Surface Quality in Micro Ball End-Milling of Potassium Dihydrogen Phosphate Crystal

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 574
Author(s):  
Ni Chen ◽  
Chunya Wu ◽  
Mingjun Chen ◽  
Liang Li ◽  
Ning He
Keyword(s):  
Cutting Force ◽  
Thrust Force ◽  
End Milling ◽  
Potassium Dihydrogen Phosphate ◽  
Spindle Speed ◽  
Dihydrogen Phosphate ◽  
Dimensional Error ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
The Relationship

Potassium dihydrogen phosphate (KDP or KH2PO4) crystal is widely used as terminal frequency converters in inertial confinement fusion (ICF). However, KDP crystal is a typical difficult-to-cut optical crystal with the characteristic of soft-brittle. In this work, the relationship between cutting force and processed surface quality in micro ball end-milling of KDP crystal with various depth of cut and spindle speed is studied by carried out the micro-milling experiments. Fast Fourier Transform (FFT) algorithm is used to diagnose the recorded cutting force. The periodic change of cutting force and the cutting force after filtering noises can be got through FFT analysis. Through calculating the correlation coefficients between the static component of thrust force and roughness value Ra of machined grooves, as well as the peak-valley (P-V) value of thrust force and dimensional error of machined grooves, the roughness value Ra and dimensional error of machined grooves would be predicted by monitoring the static component and P-V value of the thrust force, respectively. The relatively large spindle speed helps to reduce the roughness value Ra. The spindle speed with moderate value is recommended to reduce the dimensional error of machined groove because the dimensional error of machined groove will increase when the spindle speed is small enough (causing brittle cutting) or large enough (reducing cutting stability).

scholarly journals A Force Sensorless Method for CFRP/Ti Stack Interface Detection during Robotic Orbital Drilling Operations

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Qiang Fang ◽  
Ze-Min Pan ◽  
Bing Han ◽  
Shao-Hua Fei ◽  
Guan-Hua Xu ◽  
...  
Keyword(s):  
Cutting Force ◽  
Thrust Force ◽  
Cutting Parameters ◽  
Force Model ◽  
Drilling Process ◽  
Reinforced Plastics ◽  
Orbital Drilling ◽  
Drilling Parameters ◽  
Drilling Operations ◽  
Machining Properties

Drilling carbon fiber reinforced plastics and titanium (CFRP/Ti) stacks is one of the most important activities in aircraft assembly. It is favorable to use different drilling parameters for each layer due to their dissimilar machining properties. However, large aircraft parts with changing profiles lead to variation of thickness along the profiles, which makes it challenging to adapt the cutting parameters for different materials being drilled. This paper proposes a force sensorless method based on cutting force observer for monitoring the thrust force and identifying the drilling material during the drilling process. The cutting force observer, which is the combination of an adaptive disturbance observer and friction force model, is used to estimate the thrust force. An in-process algorithm is developed to monitor the variation of the thrust force for detecting the stack interface between the CFRP and titanium materials. Robotic orbital drilling experiments have been conducted on CFRP/Ti stacks. The estimate error of the cutting force observer was less than 13%, and the stack interface was detected in 0.25 s (or 0.05 mm) before or after the tool transited it. The results show that the proposed method can successfully detect the CFRP/Ti stack interface for the cutting parameters adaptation.

Prediction of cutting force and temperature rise in the end-milling operation

2006 ◽  
Vol 220 (10) ◽  
pp. 1577-1587 ◽  
Author(s):  
P Palanisamy ◽  
I Rajendran ◽  
S Shanmugasundaram ◽  
R Saravanan
Keyword(s):  
Cutting Force ◽  
Temperature Rise ◽  
End Milling ◽  
Milling Operation
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