| Optimisation
des procédés de production de réfrigérateurs
assistés par ordinateurs |
| Cet
article technique traite de la solution mise au point pour
répondre au problème des lignes de production
de réfrigérateurs, au moment où l'on constate
une demande accrue pour des systèmes de production plus
souples en raison de la diversification de la fabrication de
caisses de réfrigérateurs. Cette solution est
basée sur une technologie de communication de pointe
permettant d'établir un transfert d'informations maximal
entre les niveaux de la cellule et du contrôle. Cet article
met également en avant les avantages que cela présente
pour les fabricants, notamment en termes de qualité de
fabrication, de contrôle de la production et de rentabilité. |
|
| Optimierung
von computergestützten Produktionsverfahren für Kühlgeräte |
| Dieser
technische Bericht erläutert Lösungen für die
Probleme, die auf einer Produktionslinie für Kühlgeräte
auftreten können. Die Nachfrage nach flexibleren Produktionssystemen
ist beträchtlich gestiegen, da die Herstellung von Kühlgeräten
so fassettenreich geworden ist. Die Lösung basiert auf
der Verwendung von hochmoderner Kommunikationstechnik, um einen
vollständigen Informationstransfer zwischen der Zellen-
und Steuerebene sicherzustellen. Der Bericht hebt auch die
Vorteile für Hersteller hervor, besonders in Bezug auf
die Qualität der Fertigung, die Produktionssteuerung und
die wirtschaftliche Effizienz. |
|
| Ottimizzazione
di processi di produzione di refrigeratori automatizzati |
| Questo
articolo tecnico spiega come risolvere il problema di riuscire
a produrre armadietti per refrigeratori con caratteristiche
diverse su linee di produzione tradizionali. Nella soluzione
proposta viene utilizzata una tecnologia di comunicazione
innovativa per garantire un trasferimento completo sia a
livello di cella che di sistema di controllo. Il documento
illustra anche i vantaggi della nuova tecnologia in termini
di qualità, controllo, costi ed efficienza. |
|
The enormous diversity of models in refrigerator production demands highly flexible production lines. The manufacturing process is driven by shorter production life cycles or varying batch sizes, which in turn determine the requirements of production-plant technologies. To meet these demands, information technology (IT) must also be consistently adapted to manufacturing conditions - which is why it is particularly significant to have a permanent overview of all operator control and processing parameters.
In most manufacturing companies, factory level and cell level are typically completely separate from one another in terms of IT, or they are only very loosely linked. Interaction remains predominantly manual, and it is often not possible to automatically exchange operator control and processing parameters between factory level and cell level.
Additionally, current IT, with all its principles and standards, more frequently dictates how automation is used. (Automation technology itself has always been subject to continuous change.)
Modern field-bus systems are based on these principles and, therefore, establish
greater information-exchange continuity to the office environment at the corporate
factory level. Industrial automation is, therefore, following the trends in
the office environment where IT has long been established, accompanied by a
substantial reorganization of structures, systems, and processes.
Integrating
IT in automation opens up new opportunities for worldwide data communication
between automation systems.
User Benefits
User benefit always manifests itself ultimately in lower total costs of ownership, boosted performance, and enhanced quality as a result of the installation and operation of automation systems. These advantages specifically affect planning, wiring, engineering, documentation, assembly, start-up, and running production of refrigerated appliances.
The reduction of the total life-cycle costs represents an extra benefit. This may manifest itself in the form of easy modifications and greater up-time because of information being available for regular diagnoses, preventive maintenance, simple parameter setting, data-flow continuity, and asset management, to mention a few examples. (See Figure 1.)
Field Level to Factory Level
Typical automation solutions have a variety of technology systems made by manufacturers. On the field/actuator/sensor level, a sensor-actuator bus transmits signals from the binary sensors and actuators. A very simple and inexpensive installation that can transmit the terminals' data and supply voltages on the basis of a shared medium will be needed for this purpose.
On the control level (field level), decentralized peripherals, such as I/O modules, measuring transducers, drives, valves, and operator terminals communicate with the automation systems via a powerful real-time communication system. Process data are transmitted cyclically, while alarms, parameters, and diagnoses data will be transmitted acyclically, as required.
Figure 1. Typical automation solutions
(CLICK for bigger image). |
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On the cell level, controls such as PLCs and IPCs communicate with each other,
and IT systems in the office environment "talk" via their standards. Some examples
include Ethernet, TCP/IP, intranet, or the Internet. The information flow demands
large data packages and a multitude of high-capacity communication functions.
On the operational level, the controls of production and assembly equipment are closely linked to the higher-level production master computer and to computers for materials handling and warehousing. However, on the factory level, only PCs are used. (See Figure 2.)
Figure 2. LinFlex production line. |
|
Vertical Continuity
These systems typically use different software and operator interfaces. With so many different solutions, communication problems frequently result. Data have to be entered and then read out a number of times because there is no uniform system for loading larger data volumes.
The fundamental idea is to have a uniform technical basis for individual solutions. Ultimately, customers will benefit from integrated project management and operator communication philosophy.
Features of Fully Integrated Continuity
With Shared Data Management, the data will only be entered once. These data are then available to the user throughout the factory, at the PLC or computer levels and at the visualization system or decentralized peripherals. If any data are required elsewhere, the software will retrieve the data from the shared database. This renders time-consuming consistency checks unnecessary.
Figure 3. Metering system |
|
This communication system also uses Scaling Systems. This single, fully integrated, but modular software will design, configure, program, commission, test, and monitor all components and systems that are part of one solution. The user is able to find suitable tools for any solution in one operator interface.
The open-interface system denotes that communication is fully integrated, meaning that data may be exchanged without any problems between individual systems and components. For example, when a PLC is designed, it is not necessary to know what type of communication network will be used later. The network is only one selection criterion in terms of design. It may be modified or added any time later; therefore, a decentralized arrangement of various automation solutions is no longer a problem.
An integrated system such as this leads to cost cuts in design, maintenance, and staff training. Optimum utilization of hardware also means lower hardware costs.
Figure 4. Process data |
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Compatible and Modular Solution
Once an automation solution has been created, it can easily be extended at any time, either on the centralized or decentralized principle, because components and software are compatible and modular, and a solution never represents a finished, fixed system.
External systems may also use the shared database through defined interface standards. OPC (OLE for Process Control) means that process data can be displayed in Windows®-based operator, monitoring, and control systems.
Selection of Operator Communication and Monitoring Systems
The operator communication and monitoring systems are the interface between operator and machine, known as the Human Machine Interface (HMI). Operator panels display functions, switches, and process values. Such visualization is a clear and simple way for the operator to see and understand processes, fault messages, and measured values.
This is accomplished with field-level HMIs using the following: line-based devices for local operator control and process monitoring, graphic-display devices for user-friendly local operator control and process monitoring, and a Windows®-based systems for use in the plant-floor environment. (See Figure 3)
Window Control Center
Windows Control Center (WinCC) is a powerful process-visualization system based on Windows® NT/2000. The 32-bit system is able to provide pre-emptive multitasking, which means that responses to any process events or alarms will be quick and effective. WinCC is also easily retrofitted in existing automation systems, and it contains a shared database with standard applications for data exchange with other Windows® applications. The computers used have interfaces for communication with the cell level and an Ethernet interface for links to operational/factory levels.
All process values are filed in a database. Examples of these process values include mixhead number, pressure, flow, mixhead temperature, tank temperature, barcode, date/time, shift number, operator name, etc. These data can be retrieved from the plant floor. An Open Data Base Connectivity (ODBC) link to Microsoft Office applications such as Excel or Access may also be used to access the data. This means that ordinary Microsoft Office tools may be used to retrieve information on the current process right up to factory level. (See Figures 4 and 5.)
Figure 5. Process history database |
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Instant Knowledge Equals Higher Efficiencies
Just as IT is continuously changing, so are the demands of collecting more process data, especially optimizing production processes. The benefit of knowing data instantly and having a history provides tools for maintenance and possible avoidance of production problems. The bottom line is higher efficiencies, resulting in tangible and intangible cost savings. Hennecke's computer-aided production process system has had successful experience by integrating all levels - controls, cell, operational, and factory.
This is an edited version of a paper that was presented at the Polyurethanes
Expo held in Orlando, FL, U.S., Oct. 1-3, 2003.
About
the Authors |
| David
R. Hanne is a senior technical sales specialist
for the Hennecke
Machinery Group, a business unit of Bayer
Polymers LLC (Pittsburgh, PA, U.S.). Mr. Hanne, who has worked for Hennecke
since 1984, has an MBA from Duquesne University (Pittsburgh,
PA, U.S.) and a B.S. in Electrical Technology Engineering from
Penn State University (State College, PA, U.S.). |
|
| Ralf
Konopka has studied general electrical engineering at
Cologne Technical University. He joined Hennecke
GmbH in 1995
as a certified engineer responsible for programming and commissioning
production lines for refrigerated appliances. |
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