Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-10-05
2001-08-14
Gordon, Paul P. (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S010000
Reexamination Certificate
active
06275741
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an integrated control platform for controlling an injection molding system, and more particularly to apparatus and method for controlling an injection molding system with a single, general purpose computer which performs both the machine-control functions and the human machine interface (HMI) functions. This control architecture thus obviates the need for the analog signal processor and the programmable logic controller used in the prior art.
2. Description of the Related Art
Injection molding systems are widely used for producing great quantities of inexpensive plastic products such as plastic PET preforms which can be blown into the widely-recognized drink containers. Such injection molding systems typically include a plurality of analog and digital devices which carry out the injection molding operations. For example, extruder drives, proportional flow control valves, electric drives, heating and cooling elements, and other electro-hydro-mechanical and electro-mechanical drives are analog devices which perform injection molding functions in a well-known way. Examples of digital devices include proximity switches, clamp pressure limit transducers, digital solenoid valves, etc. Each of these analog and digital devices must not only be controlled with appropriate analog and digital commands, but they are typically provided with feedback sensors which output analog and/or digital feedback signals so that the various devices may be properly controlled to produce high-volume, quality output from the system. For example, the feedback signals may be used in closed loop control to effect real-time changes in the injection molding devices (e.g. temperature set points, injection pressure, etc.). Also, the feedback signals may be used to display operational information (e.g. status, temperature, parts count, etc.) to the operator at the human machine interface or operator control panel.
In the prior art, it was necessary to utilize an analog signal processor (ASP) to provide for real-time control of the various analog devices in the injection molding system. Likewise, it was necessary to provide a programmable logic controller (PLC) to control the various digital devices in the injection molding system. See, for example, U.S. Pat. No. 5,062,052 (incorporated herein by reference) for an example of a known injection molding system utilizing both an ASP and a PLC to control the injection molding machine. While the '052 Patent discloses a general purpose computer, its use is restricted to interfacing between the PLC and the HMI. Both the PLC and the ASP are still required to perform the injection molding operations.
The known injection molding control architecture is limited in that reconfiguration of the injection molding devices cannot be done in real time. Each of the ASP and PLC must be modified or reprogrammed to effect the change. Thus, incorporating new technologies in an injection molding system often requires that the entire system be shut down for reconfiguration. Additionally, the operational status of each injection molding system may only be ascertained at the HMI of each system. Also, injection molding machine manufacturers typically utilize proprietary architecture in their PLC's, thus limiting the variety of new processing techniques than can be applied to such machines. Furthermore, using multiple layers of ASP and PLC processing control imposes a processing penalty and a bottleneck which reduces the speed at which machine changes can be accomplished.
Thus, what is needed is a new injection molding control architecture which provides true real-time control of the injection molding system, allows rapid reconfiguration of system devices, permits the use of readily available off-the-shelf software, and allows system status and control information to be transmitted beyond the system, e.g., to the factory office or even corporate headquarters.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an injection molding control architecture that enables state-of-the-art hardware and software components to be seamlessly integrated into one controller. Another object is to provide such a control architecture that provides true real-time controlling and networking capabilities. Yet another object is to provide an open control architecture that allows easy integration of ancillary equipment and expansion of machine functions. An additional object is to provide intelligent system diagnostics and remote access capabilities to reduce system downtime and to import/export knowledge and information to/from external sources. Yet another object is to provide, in one general purpose computer, injection molding system control functions, human-machine interface functions, motion control functions, sequence logic functions, continuous process control functions, and communication networking functions.
Additional objects of the present invention include providing a standard application programming interface, supporting external communications (such as electronic mail, paging, etc., for supervision, trouble-shooting, and information. exchange between the system and plant management), providing an expert system with embedded process knowledge to assist in system and process set up, providing intelligent alarm management and system diagnostics, and providing predefined templates with embedded options to assist the user in setting up and operating the injection molding system.
The above objects and other advantages according to the present invention may be achieved by an apparatus for controlling an injection molding system which has a plurality of devices that generate a plurality of feedback signals, the apparatus including (i) a human machine interface preferably disposed adjacent the injection molding system and having a display and at least one operator input device, and (ii) a general purpose computer coupled to both the human machine interface and to the plurality of injection molding devices, wherein the general purpose computer performs real-time closed loop control of the plurality of injection molding devices based on the plurality of command and feedback signals.
According to another aspect of the present invention, a single computer for controlling an injection molding system having a plurality of injection molding devices which carry out injection molding processes and provide feedback signals, and a human machine interface having a display and at least one manual input device for inputting operator commands, includes (i) a first input/output for receiving command signals from the human machine interface manual input device or devices, and for providing display signals to the human machine interface display, (ii) a second input/output for receiving the feedback signals directly from the plurality of injection molding devices, and for providing real-time control signals directly to the plurality of injection molding devices, and (iii) a CPU for generating the real-time control signals in accordance with the feedback signals and the command signals, the CPU performing multi-tasking processing of the command signals, the display signals, the feedback signals, and the control signals.
Another aspect of the present invention features an injection molding system which comprises (i) a plurality of injection molding devices for performing injection molding operations, the plurality of devices receiving real-time control signals and outputting real-time feedback signals, (ii) a human machine interface having a display and at least one operator input device, and (iii) a single processor which receives the real-time feedback signals from the plurality of injection molding devices and command signals from the operator input device, multi-task processes the received signals in accordance with a plurality of predetermined injection-molding control programs and display programs, outputs the real-time control signals to the plurality of injection molding devices and outputs the display si
Cabrera Zoila
Gordon Paul P.
Husky Injection Molding Systems Ltd.
Katten Muchin & Zavis
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