Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-03-19
2001-02-06
Lee, Thomas C. (Department: 2787)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S018000
Reexamination Certificate
active
06185477
ABSTRACT:
FIELD OF AND BACKGROUND OF THE INVENTION
The invention relates to new and useful improvements in an automation system for the control and regulation of machines and systems used e.g. in the plastics industry, in particular blow molding machines. More particularly, the invention relates to such automation systems having programmable logic controllers (PLC), which can be used to implement the open-loop and closed-loop control functions of the machines and systems as desired, and which have at least one operating and monitoring unit and a local bus (user platform). The programmable logic controllers (PLC) are provided with digital technology blocks which simulate electrical, application-specific switching details. These technology blocks are used to implement, in a modular fashion, the open-loop and closed-loop control functions that are necessary for a particular application. They can be connected to one another and to the user platform via data interfaces.
Plastics processing machines controlled by means of programmable logic controllers are known in the art. One representative such system is described in U.S. Pat. No. 5,062,052, the disclosure of which is incorporated herein by reference. In the past, it has been customary to use special hardware components, i.e. special assemblies, to automate machines in the plastics industry, in particular those for blow molding and injection molding. These known special assemblies have hardware and software which are specially designed for a specific, respective task. The results achieved with the plastics machines are good, but the control systems are highly complex. To cope with new or modified products, both the control programs and the special assemblies have to be adapted to the new machine conditions. Modifications sometimes also require new hardware components.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide a system for automating the control and regulation of machines and systems in the plastics industry, which, in contrast to conventional systems, can easily adapt its control configuration and its scope of performance to the requirements of the specific task at hand without modifying the hardware or the basic software. Another aim is to enable the user to perform these adaptations without needing an in-depth knowledge of such systems, through the use of standardized modules, so-called basic modules.
SUMMARY OF THE INVENTION
These and other objects are achieved in that the technology blocks of the automation system are provided with organization modules. Some of these modules are for function modules which, in turn, have sub-modules in organization modules, these being, in particular, basic modules which can be used to perform the necessary basic steps for automation, for example PID regulating functions, analog-value sensing, etc. Additionally, some of these organization modules have organization blocks, for example for starting up machines, etc.
Designing the automation system in this way obviates the need for previously used, pluggable function modules, known, e.g., from EP 0 603 560 A1, the disclosure of which is hereby incorporated by reference. The complexity of the hardware is correspondingly lower and it is possible to use modular software throughout. This software considerably improves the planning and implementation of the open-loop control and closed-loop regulation of plastics-processing machines, especially linked ones. The solution according to the invention has a software structure which is particularly suitable for plastics-processing machines and which is not known from the general prior art of modular software engineering. his prior art is found, for example, in EP 0 375 487 A1 and FR 2 646 536, which describe general forms of automatic-machinery programs.
Function modules, which in turn have sub-modules, in particular basic modules with which the necessary basic steps of the automation can be carried out, for example PID control functions (Proportional, Integral, Differential, i.e., proportional plus floating plus derivative control), analog value sensing, etc., make it possible to implement all the necessary closed-loop and open-loop functions of plastics-processing machines in an interactive way.
Independent technology functions can be implemented in separate technology software blocks. Each technology block contains all the mechanisms and functions which are necessary for the application of the technology and the integration of the block into the control environment. For blow molding machines, the following technology blocks, among others, can be implemented:
temperature closed-loop control
travel sensing
wall thickness open-loop control with mandrel position closed-loop control
closed-loop-controlled blow molding movement.
The setting of the wall thickness is particularly important for the wall thickness open-loop control and mandrel position closed-loop control of blow molding machines. Here, use is made of various function modules having specific basic modules which relate to specific sub-functions during blow molding.
In particular, the functions of the various function modules include, for example, input value treatment, scaling, etc. as well as further functions, for example, process control, profile calculation, nozzle setpoint value specification, open-loop control and closed-loop control of the ejection procedure, and tube length closed-loop control, which is carried out using a photoelectric cell. A function module is also used when a plurality of extruders interact, for example when processing different grades of material. The same applies to quality monitoring of the products, and also to liquid filling level closed-loop control, which is carried out in synchronization with the machine clock by means of the setpoint value specification of the respective extruder.
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patent: 5182716 (1993-01-01), Stroud et al.
patent: 5613115 (1997-03-01), Gihl et al.
patent: 5777869 (1998-07-01), Welch
patent: 0375487 (1990-06-01), None
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patent: 9311475 (1993-06-01), None
T. Gerstner et al., “Rationelles Projektieren von Automatisierungssystemen,”ATP Automatisierungstechnische Praxis, vol. 36, No. 12 (Dec. 1994), pp. 42-45.
Palm Berthold
Schovenberg Wolfgang
Lee Thomas C.
Patel Nitin
Siemens Aktiengesellschaft
Sughrue Mion Zinn Macpeak & Seas, PLLC
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