Distributed-Parameter Design of Virtual Source Thermal Processing Methods

1995 ◽  
Author(s):  
Charalabos Doumanidis ◽  
Nikolaos Fourligkas
Keyword(s):  
Thermal Processing ◽  
Distributed Parameter ◽  
Material Structure ◽  
Process Conditions ◽  
Virtual Source ◽  
Real Time Control ◽  
Source Power ◽  
Time Control ◽  
Thermal Techniques ◽  
Line Design

Abstract In thermal manufacturing methods, visualization of the thermally generated distributions of material structure and properties in the products forms the basis for the development of a methodology for off-line design of the process conditions in virtual-source thermal techniques. These are implemented by timesharing a single heat source, scanning the external surface of the processed part to generate a flexible heat input distribution, and thus a specified temperature field yielding the desired thermal quality of the product. A numerical simulation of generic thermal processing is developed, integrating a solid conduction description to a flow model in molten regions. This computational model is validated by a comparative thermal study and is used for the design of the virtual source power and trajectory in rapid prototyping of laminated objects with specified geometric tolerances. Virtual-source processing based on real-time control with infrared thermal feedback is currently simulated for other thermal manufacturing processes.

Thermal Simulation and Visualization of Virtual Source Manufacturing Systems

1995 ◽  
Author(s):  
Charalabos C. Doumanidis ◽  
Brian P. Marquis
Keyword(s):  
Manufacturing Systems ◽  
Welding Process ◽  
Material Structure ◽  
Process Conditions ◽  
Virtual Source ◽  
Real Time Control ◽  
Time Control ◽  
Manufactured Products ◽  
Thermal Features ◽  
Thermal Techniques

Abstract This article addresses visualization of the thermally generated distributions of material structure and properties in the manufactured products, and provides a methodology for offline design of the process conditions in virtual source thermal techniques. These are implemented by timesharing a single heat source, scanning the external surface of the processed part to generate a flexible heat input distribution, and thus a specified temperature field yielding the desired thermal quality of the product. A numerical simulation of generic thermal processing is developed, integrating a solid conduction description to a flow model in molten regions. This computational model is validated by a comparative thermal study of classical and a novel scan welding process, in which the torch reciprocates along the joint to provide uniform thermal features. Virtual source processing is currently simulated for other thermal manufacturing processes and their real-time control with infrared thermal feedback.

A New Flexible Rapid Thermal Processing System

1995 ◽  
Vol 389 ◽  
Author(s):  
K. C. Saraswat ◽  
Y. Chen ◽  
L. Degertekin ◽  
B. T. Khuri-Yakub
Keyword(s):  
Control System ◽  
Real Time ◽  
Processing System ◽  
Process Conditions ◽  
Temperature Uniformity ◽  
Real Time Control ◽  
Wafer Temperature ◽  
Time Control ◽  
Wide Range ◽  
Optical Flux

ABSTRACTA highly flexible Rapid Thermal Multiprocessing (RTM) reactor is described. This flexibility is the result of several new innovations: a lamp system, an acoustic thermometer and a real-time control system. The new lamp has been optimally designed through the use of a “virtual reactor” methodology to obtain the best possible wafer temperature uniformity. It consists of multiple concentric rings composed of light bulbs with horizontal filaments. Each ring is independently and dynamically controlled providing better control over the spatial and temporal optical flux profile resulting in excellent temperature uniformity over a wide range of process conditions. An acoustic thermometer non-invasively allows complete wafer temperature tomography under all process conditions - a critically important measurement never obtained before. For real-time equipment and process control a model based multivariable control system has been developed. Extensive integration of computers and related technology for specification, communication, execution, monitoring, control, and diagnosis demonstrates the programmability of the RTM.

Temperature Field Regulation in Thermal Cutting for Layered Manufacturing

1999 ◽  
Vol 121 (3) ◽  
pp. 440-447 ◽  
Author(s):  
N. Fourligkas ◽  
C. Doumanidis
Keyword(s):  
Temperature Field ◽  
Thermal Processing ◽  
Pole Placement ◽  
Time Variability ◽  
Material Structure ◽  
Source Power ◽  
Modeling And Control ◽  
Thermal Sensing ◽  
Process Disturbances ◽  
And Control

A general thermal modeling and control methodology for thermal processing of layered materials for rapid prototyping technologies is established in this article. An analytical multivariable model of lumped temperature outputs generated by heat inputs on a surface grid is developed, based on Green’s function and state-space descriptions. The few independent parameters needed in such a linearized formulation are experimentally identified, and their time-variability reflects the heat transfer nonlinearities and process disturbances. A robust controller with thermal feedback is designed by pole placement methods, to obtain a specified dynamic temperature field yielding the desired material structure and properties. The regulated thermal processing is optimized in real time by proper heat source power modulation and torch guidance through a simulated annealing strategy. Its performance is tested on both the computer model and a laboratory station, using robotically guided plasma-arc cutting and infrared thermal sensing, in regulating the sensitized zone during blanking of an elementary contour pattern on stainless steel.

Sensitivity Analysis of Hydro-Rim Deep Drawing of Cylindrical Cups

Manufacturing ◽  
2003 ◽  
Author(s):  
Jeries J. Abou-Hanna ◽  
Timothy McGreevy ◽  
Abdalla Elbella ◽  
Haithem Algousi
Keyword(s):  
Finite Element ◽  
Deep Drawing ◽  
Material Model ◽  
Chamber Pressure ◽  
Process Conditions ◽  
Plastic Behavior ◽  
Drawing Ratio ◽  
Real Time Control ◽  
Time Control ◽  
Punch Speed

Extensive nonlinear finite element analyses were conducted to help predict practical test conditions of intelligent hydro-rim deep forming of cylindrical cups under controlled cooled punch and heated blank temperatures, punch speed, chamber and rim pressures, and punch friction. The study focused on finding practical process conditions for maximizing the drawing ratio by variations in blank and punch temperatures, friction, rim pressure, chamber pressure, and punch speed. The study was based on an experimental cell that aimed at using real time control of the mentioned parameters to delay the necking process. The finite element material model considered the plastic behavior to be strain rate and temperature dependent. While conventional deep drawing is limited to a Limit Drawing Ratio (LDR) of about 2, the results show that a parameters listed above. Blank temperature, punch friction, rim pressure, and chamber pressure provide significant influence of various degrees on increasing the cup drawing ratio. Blank heating is very effective, but does not by itself guarantee higher LDR. The presence of punch friction coupled with chamber pressure tends to delay the necking and moves the latter up along the cup wall and away from the cup bottom corner. Rim pressure, while difficult to implement, results in significant improvement of the LDR, since it helps push the material into the die, and in doing so reduces the cup-wall tension that causes the material instability. High rim pressure, on the other hand, increases the blank thickness resulting in increased blank holder loads. Punch temperature does not play as critical a role as the blank temperature in maintaining a high LDR under the conditions investigated. The study revealed that punch speed had to be above a certain critical level for a LDR of 4. However, increased punch speed proved to cause higher variations in the thickness along cup wall. It is important to mention that the results of this study do not necessarily apply to all metals; copper material was used here. Metals with low ductility, for example would react differently, a subject of future studies.

Scan Welding: Thermal Modeling and Control of Material Processing

1999 ◽  
Vol 121 (3) ◽  
pp. 417-424 ◽  
Author(s):  
G. Korizis ◽  
C. Doumanidis
Keyword(s):  
Real Time ◽  
Thermal Control ◽  
Joint Surface ◽  
Material Structure ◽  
Real Time Control ◽  
Welding Temperature ◽  
Modeling And Control ◽  
Gas Tungsten Arc ◽  
Time Control ◽  
And Control

This article provides a thermal analysis of scan welding, as a redesign of classical joining methods, employing computer technology to ensure the composite morphologic, material and mechanical integrity of the joint. This is obtained by real-time control of the welding temperature field by a proper dynamic heat input distribution on the weld surface. This distribution is implemented in scan welding by a single torch, sweeping the joint surface by a controlled reciprocating motion, and power adjusted by feedback of infrared temperature measurements in-process. An off-line numerical simulation of the thermal field in scan welding is established, as well as a linearized multivariable model with real-time parameter identification. An adaptive thermal control scheme is thus implemented and validated both computationally and experimentally on a robotic Gas-Tungsten Arc Welding setup. The resulting productivity and quality features of scan welding are comparatively analyzed in terms of material structure and properties of the joint.

Modeling and Real-Time Control of Multizone Thermal Processing System for Photoresist Processing

2013 ◽  
Vol 52 (13) ◽  
pp. 4805-4814 ◽  
Author(s):  
Arthur Tay ◽  
Hui Tong Chua ◽  
Wang Yuheng ◽  
Yang Geng ◽  
Ho Weng Khuen
Keyword(s):  
Real Time ◽  
Thermal Processing ◽  
Processing System ◽  
Real Time Control ◽  
Time Control

Distributed-Parameter Control of the Heat Source Trajectory in Thermal Materials Processing

1996 ◽  
Vol 118 (4) ◽  
pp. 571-578 ◽  
Author(s):  
C. Doumanidis ◽  
N. Fourligkas
Keyword(s):  
Temperature Field ◽  
Heat Source ◽  
Real Time ◽  
Welding Process ◽  
Thermal Control ◽  
Distributed Parameter ◽  
Material Structure ◽  
Parameter Control ◽  
Real Time Control ◽  
Distributed Parameter Control

In thermal manufacturing processes performed by a localized, sequentially moving heat source, simultaneous regulation of multiple thermal quality characteristics requires real-time control of the temperature field developed through the distributed heat input on the part surface. Such control of the thermal field to a desired distribution employs infrared sensing and feedback of the surface temperature hill, to modulate the torch power and motion in-process. The torch trajectory is guided in real time by an efficient optimization algorithm based on the concept of moving complexes. This distributed-parameter control strategy is developed using a numerical simulation model of thermal processing, and its performance is evaluated experimentally in heat treatment of thin stainless steel plates. The thermal controller is applied to the new scan welding process, in which it drives the torch in a reciprocating motion along the weld, yielding a uniform and smooth temperature field, and thus a favorable material structure and mechanical properties. Application of such thermal control to various other material processing methods is also investigated.

A New Flexible Rapid Thermal Processing System

1995 ◽  
Vol 387 ◽  
Author(s):  
K. C. Saraswat ◽  
Y. Chen ◽  
L. Degertekin ◽  
B. T. Khuri-Yakub
Keyword(s):  
Control System ◽  
Real Time ◽  
Processing System ◽  
Process Conditions ◽  
Temperature Uniformity ◽  
Real Time Control ◽  
Wafer Temperature ◽  
Time Control ◽  
Wide Range ◽  
Optical Flux

AbstractA highly flexible Rapid Thermal Multiprocessing (RTM) reactor is described. This flexibility is the result of several new innovations: a lamp system, an acoustic thermometer and a real-time control system. The new lamp has been optimally designed through the use of a “virtual reactor” methodology to obtain the best possible wafer temperature uniformity. It consists of multiple concentric rings composed of light bulbs with horizontal filaments. Each ring is independently and dynamically controlled providing better control over the spatial and temporal optical flux profile resulting in excellent temperature uniformity over a wide range of process conditions. An acoustic thermometer non-invasively allows complete wafer temperature tomography under all process conditions - a critically important measurement never obtained before. For real-time equipment and process control a model based multivariable control system has been developed. Extensive integration of computers and related technology for specification, communication, execution, monitoring, control, and diagnosis demonstrates the programmability of the RTM.

A Real Time Control Architecture for Continuously Managing Patients in a Care Unit

1995 ◽  
Vol 34 (05) ◽  
pp. 475-488
Author(s):  
B. Seroussi ◽  
J. F. Boisvieux ◽  
V. Morice
Keyword(s):  
Real Time ◽  
Linear Time ◽  
Treatment Plan ◽  
Control Architecture ◽  
Real Time Control ◽  
Time Representation ◽  
Time Control ◽  
Continuous Support ◽  
Definition Of ◽  
Computerized System

Abstract:The monitoring and treatment of patients in a care unit is a complex task in which even the most experienced clinicians can make errors. A hemato-oncology department in which patients undergo chemotherapy asked for a computerized system able to provide intelligent and continuous support in this task. One issue in building such a system is the definition of a control architecture able to manage, in real time, a treatment plan containing prescriptions and protocols in which temporal constraints are expressed in various ways, that is, which supervises the treatment, including controlling the timely execution of prescriptions and suggesting modifications to the plan according to the patient’s evolving condition. The system to solve these issues, called SEPIA, has to manage the dynamic, processes involved in patient care. Its role is to generate, in real time, commands for the patient’s care (execution of tests, administration of drugs) from a plan, and to monitor the patient’s state so that it may propose actions updating the plan. The necessity of an explicit time representation is shown. We propose using a linear time structure towards the past, with precise and absolute dates, open towards the future, and with imprecise and relative dates. Temporal relative scales are introduced to facilitate knowledge representation and access.

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