Development of a Recursive Frequency Based Filter With Application to Chatter Control

1993 ◽  
Author(s):  
Karl B. Ousterhout
Keyword(s):  
Machine Tool ◽  
Real Time ◽  
Digital Signal ◽  
Work Piece ◽  
Machining Processes ◽  
Damping Characteristics ◽  
Analytical Work ◽  
Chatter Control ◽  
Performance Limitation ◽  
Processing Techniques

Abstract In most machining processes, large amounts of energy are needed to accomplish the machining operation. When this energy is transmitted through a structure that has minimal damping characteristics, such as a lathe or a milling machine, self sustained oscillations (chatter) can develop. When chatter develops, it can be viewed as a basic performance limitation of the machine tool. In order to suppress the chatter, a real-time controller using digital signal processing techniques has been implemented. This paper discusses a novel way of computing the transfer function of the machine tool-work piece combination and illustrates how a real-time active chatter controller could be designed and integrated into existing machine tools to overcome this performance limitation. Currently, experimental verification of the analytical work is being pursued.

The Development of a Real Time Recursive Frequency Based Active Chatter Controller

1995 ◽  
Author(s):  
Sun Kim ◽  
Karl B. Ousterhout
Keyword(s):  
Machine Tool ◽  
Real Time ◽  
Digital Signal ◽  
Machining Processes ◽  
Damping Characteristics ◽  
Sustained Oscillations ◽  
Performance Limitation ◽  
Novel Method ◽  
Processing Techniques ◽  
Signal Processing Techniques

Abstract In most machining processes, large amounts of energy are needed to accomplish the machining operation. When this energy is transmitted through a structure that has minimal damping characteristics, such as a lathe or a milling machine, self sustained oscillations (chatter) can develop. When chatter develops, it can be viewed as a basic performance limitation of the machine tool. In order to suppress the chatter, a real-time controller using digital signal processing techniques has been implemented. This paper discusses a novel method for the real time computation of the transfer function of the machine tool-workpiece combination and illustrates how a real-time active chatter controller can be designed and integrated into existing machine tools to overcome this performance limitation.

Design of a Force Feedback Chatter Control System

1972 ◽  
Vol 94 (1) ◽  
pp. 5-10 ◽  
Author(s):  
C. Nachtigal
Keyword(s):  
Machine Tool ◽  
Frequency Domain ◽  
Transient Response ◽  
Force Feedback ◽  
Design Procedure ◽  
Experimental Tests ◽  
Work Piece ◽  
Regenerative Chatter ◽  
Chatter Control ◽  
The Stability

The analysis of machine tool chatter from frequency domain considerations is generally accepted as a valid representation of the regenerative chatter phenomenon. However, active control of regenerative chatter is still in its embryonic stage. It was established in reference [2] that a measurement of the cutting force could be effectively used in conjunction with a controller and a tool position servo system to increase the stability of an engine lathe and to improve its transient response. This paper presents the design basis for such a system, including both analytical and experimental considerations. The design procedure stems from a real part stability criterion based on the work by Merritt [1]. Because of the unknown variability in the dynamics of a machine tool system, the controller parameters were chosen to accomodate some mismatch between structure and tool servo dynamics. Experimental tests to determine the stability zone of the controlled machine tool system qualitatively confirmed the analytical design results. The experimental results were consistent in that the transient response tests confirmed the frequency domain stability tests. It was also demonstrated experimentally that the equivalent static stiffness of a flexible work-piece system could be substantially increased.

scholarly journals Identifying Direct Electrical Energy Demand in Wire-Cut EDM

2020 ◽  
Vol 39 (1) ◽  
pp. 171-178
Author(s):  
Anis Fatima ◽  
Amir Iqbal Syed
Keyword(s):  
Energy Consumption ◽  
Machine Tool ◽  
Energy Demand ◽  
Copper Wire ◽  
Electrical Energy ◽  
Working Fluid ◽  
Work Piece ◽  
Main Concern ◽  
Product Cycle ◽  
Machining Processes

Non-traditional machining processes are popular for generating complex features on the work piece. With advances in material engineering, new ways of cutting technologies has been emerged. However, EDM (Electric Discharge Machining) has gained recognition for producing extraordinary surface finished, intricate part geometries with accuracy and its ability to cut through difficult to machined materials. However, like every product cycle, manufacturing processes also require energy to convert raw materials into finished product. In manufacturing operations, energy input gives carbon footprints which have an effect on our environment. It is observed that reducing energy consumption is becoming the main concern of manufacturers because of enforcing environmental laws and due to the economics of the processing. It is argued that world’s 70% of energy consumption is consumed by manufacturing sector. The aim of the work was to identify direct energy demands in wire cut EDM. The variability in energy demand was explored by operating wire cut EDM at no-load and loaded conditions.Stainless steel S304 was used as a work piece. Experiments were performed on three different wire-cut EDM.Molybdenum wire, brass wire and copper wire were used as an electrode wire and distilled water was used as a working fluid. During the experiment, electrical current was measured and the variation of power requirement was evaluated. Power required by different features of EDM was compared with the existing energy models and factors were identified that consume most of the electrical energy. Further, a comparison is made between traditional and non-traditional machining processes. This contribution will help to assess energy efficiency of EDM technology and identify priority areas for improvements. This work is also significant for machine tool designers for optimum utilization of energy,reduced environmental impact and reduced production cost of their machine tool.

scholarly journals Numerical Modeling and Experimental Validation in Orthogonal Machining of Aluminum Al 6061-T6 Alloy

2020 ◽  
Vol 39 (1) ◽  
pp. 179-194
Author(s):  
Suhail Akram ◽  
Shafi uddin ◽  
Syed Hussain Imran Jaffery ◽  
Mian Aamir Jalil ◽  
Syed Waqar Hyder Kazmi
Keyword(s):  
Energy Consumption ◽  
Machine Tool ◽  
Energy Demand ◽  
Copper Wire ◽  
Working Fluid ◽  
Work Piece ◽  
Main Concern ◽  
Product Cycle ◽  
Machining Processes ◽  
Power Requirement

Non-traditional machining processes are popular for generating complex features on the work piece. With advances in material engineering, new ways of cutting technologies has been emerged. However, EDM (Electric Discharge Machining) has gained recognition for producing extraordinary surface finished, intricate part geometries with accuracy and its ability to cut through difficult to machined materials. However, like every product cycle, manufacturing processes also require energy to convert raw materials into finished product. In manufacturing operations, energy input gives carbon footprints which have an effect on our environment. It is observed that reducing energy consumption is becoming the main concern of manufacturers because of enforcing environmental laws and due to the economics of the processing. It is argued that world’s 70% of energy consumption is consumed by manufacturing sector. The aim of the work was to identify direct energy demands in wire cut EDM. The variability in energy demand was explored by operating wire cut EDM at no-load and loaded conditions.Stainless steel S304 was used as a work piece. Experiments were performed on three different wire-cut EDM.Molybdenum wire, brass wire and copper wire were used as an electrode wire and distilled water was used as a working fluid. During the experiment, electrical current was measured and the variation of power requirement was evaluated. Power required by different features of EDM was compared with the existing energy models and factors were identified that consume most of the electrical energy. Further, a comparison is made between traditional and non-traditional machining processes. This contribution will help to assess energy efficiency of EDM technology and identify priority areas for improvements. This work is also significant for machine tool designers for optimum utilization of energy,reduced environmental impact and reduced production cost of their machine tool.

scholarly journals Real-time machine simulation using cutting force calculation based on a voxel material removal model

2019 ◽  
Vol 105 (5-6) ◽  
pp. 2321-2328
Author(s):  
Marco Witt ◽  
Marco Schumann ◽  
Philipp Klimant
Keyword(s):  
Cutting Force ◽  
Real Time ◽  
Material Removal ◽  
Work Piece ◽  
Time Machine ◽  
Machining Processes ◽  
Starting Point ◽  
Material Removal Model ◽  
Machine Simulation ◽  
Force Calculation

Abstract Machining processes must be adjusted regarding tolerances in dimension and shape to fulfill product requirements. For this purpose, machine simulations are used to allow a preliminary characterization of the given process, thus minimizing the number of physical prototypes and scrap parts. However, these simulations are either extremely specialized for single problems, e.g., dynamic machine behavior, or they are simplified to a kinematic simulation of the machine without considering the machine behavior at all. This article presents a new approach for a real-time machine simulation by combining four types of simulations to close this gap. This proposed approach uses a voxel-based material removal inside a kinematic machine simulation as input parameters for a cutting force calculation. Afterwards, the forces are applied to a multi-body simulation of the static machine behavior. Starting point of the simulation is a hardware-in-the-loop coupling of a real CNC and a real-time visualization of a virtual machine tool. The simulation is experimental verified by comparing the simulated cutting forces and displacements with the measured forces during the process and the resulting shape of the manufactured work piece. The presented conclusions show the general applicability of the proposed method for the simulation of milling processes.

45. Education at distance: Broadcasting ECG rounds to Southeastern Ontario (BESO Project). An innovative approach for teaching electrocardiography

2007 ◽  
Vol 30 (4) ◽  
pp. 51 ◽  
Author(s):  
A. Baranchuk ◽  
G. Dagnone ◽  
P. Fowler ◽  
M. N. Harrison ◽  
L. Lisnevskaia ◽  
...  
Keyword(s):  
Health Care ◽  
Real Time ◽  
Digital Signal ◽  
Teaching Methodology ◽  
Care Providers ◽  
Long Distance ◽  
Medicine Clerkship ◽  
Time Problem ◽  
The Impact ◽  
Ecg Interpretation

Electrocardiography (ECG) interpretation is an essential skill for physicians as well as for many other health care professionals. Continuing education is necessary to maintain these skills. The process of teaching and learning ECG interpretation is complex and involves both deductive mechanisms and recognition of patterns for different clinical situations (“pattern recognition”). The successful methodologies of interactive sessions and real time problem based learning have never been evaluated with a long distance education model. To evaluate the efficacy of broadcasting ECG rounds to different hospitals in the Southeastern Ontario region; to perform qualitative research to determine the impact of this methodology in developing and maintaining skills in ECG interpretation. ECG rounds are held weekly at Kingston General Hospital and will be transmitted live to Napanee, Belleville, Oshawa, Peterborough and Brockville. The teaching methodology is based on real ECG cases. The audience is invited to analyze the ECG case and the coordinator will introduce comments to guide the case through the proper algorithm. Final interpretation will be achieved emphasizing the deductive process and the relevance of each case. An evaluation will be filled out by each participant at the end of each session. Videoconferencing works through a vast array of internet LANs, WANs, ISDN phone lines, routers, switches, firewalls and Codecs (Coder/Decoder) and bridges. A videoconference Codec takes the analog audio and video signal codes and compresses it into a digital signal and transmits that digital signal to another Codec where the signal is decompressed and retranslated back into analog video and audio. This compression and decompression allows large amounts of data to be transferred across a network at close to real time (384 kbps with 30 frames of video per second). Videoconferencing communication works on voice activation so whichever site is speaking has the floor and is seen by all the participating sites. A continuous presence mode allows each site to have the same visual and audio involvement as the host site. A bridged multipoint can connect between 8 and 12 sites simultaneously. This innovative methodology for teaching ECG will facilitate access to developing and maintaining skills in ECG interpretation for a large number of health care providers. Bertsch TF, Callas PW, Rubin A. Effectiveness of lectures attended via interactive video conferencing versus in-person in preparing third-year internal medicine clerkship students for clinical practice examinations. Teach Learn Med 2007; 19(1):4-8. Yellowlees PM, Hogarth M, Hilty DM. The importance of distributed broadband networks to academic biomedical research and education programs. Acad Psychaitry 2006;30:451-455

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