Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Article ejector or stripper control
Reexamination Certificate
1999-05-07
2001-11-13
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Article ejector or stripper control
C264S334000, C264S336000, C425S556000, C425S444000, C425S537000, C425S169000
Reexamination Certificate
active
06315543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and method for reducing the cycle time of an injection molding machine. More particularly, the invention relates to an improved device and method for detecting the presence of an article on a mold of an injection molding machine, and controlling the operation of the device on the basis of this detection. The invention further relates to a device and method for removing molded articles from a mold of an injection molding machine before the articles are fully cooled. Both of these devices and methods, when used individually or together in an injection molding machine, reduce the machine's injection cycle time.
2. Description of Related Art
Containers are commonly made by blow molding a parison or preform that is made from polyethylene terephthalate (PET) material. The PET preheat and blow parisons are commonly manufactured by injection molding equipment. Containers may be injection molded in high-volume, multi-cavity molds.
It is important to reduce the overall cycle time for several reasons: (1) greater efficiency and cost-competitiveness; (2) reduced resin degradation due to prolonged residence time in the mold (specifically, acetaldehyde in PET parts); and (3) improved visual part quality (crystallization, seen as cloudy regions in the molded parts, may occur if cycle times are excessive).
Problems may also occur if articles or portions of articles are left on the mold core pins after the ejection cycle. Portions of articles may remain on the core pins due to (1) failure of the ejection system, (2) breakage of the parison during stripping from the cores, or (3) a “short shot” due to insufficient plasticized material being supplied to the mold cavities. If any molded portions remain on the core pins when the injection mold halves close, the injection mold may be damaged or the next successive part may be defective. To prevent this from happening, a conventional injection molding machine is set-up such that the device (e.g., a take-out plate) used to remove the molded parts from the core pins does not leave the molding area until it receives a signal from the injection molding machine controller that all the molded articles (or portions) have been removed from the core. This conservative approach lengthens the total molding injection cycle time. It also does not confirm that all of the molded articles are on the take-out plate and off the mold core pins. Thus, it would be desirable to reduce the injection cycle time by removing this conservatism from the injection molding process.
To further reduce cycle time, it would be desirable to remove the molded articles from the mold core before they are fully cooled. However, in this state, the parts are soft and malleable and susceptible to surface damage and mechanical deformation. Thus, there is also a need to develop a way to extract molded parts while they are still warm to reduce total cycle time.
SUMMARY OF THE PRESENT INVENTION
It is therefore a principal object of the present invention to provide apparatuses and methods for reducing the total injection cycle time needed to mold and safely eject parisons in a multi-cavity mold. The invention is, however, not restricted to parisons, and may apply to any molded article that shrinks onto the core halves of a mold after injection and cooling.
In one aspect of the present invention, an apparatus for controlling a machine controller and a take-out controller of an injection molding machine includes a radiation source, a radiation detector, a machine controller, and a take-out controller. The radiation source projects radiation to a mold plate. The radiation detector receives the projected radiation from the mold plate. The machine controller receives a signal from the radiation detector, determines whether any molded parts or portions of molded parts remain at a predetermined position on the mold plate, and provides a command signal to stop injection operations when it is determined that molded parts or portions of molded parts remain at the predetermined position. The take-out controller substantially simultaneously receives a signal from the radiation detector, determines whether any molded parts or portions of molded parts remain at a predetermined position on the mold plate, and provides a command signal to stop take-out operations when it is determined that molded parts or portions of molded parts remain at the predetermined position.
In another aspect of the present invention, an injection molding machine includes a platen, a mold attached to the platen, a radiation emitting element, a radiation receiving element, a take-out controller and a machine controller. The mold includes at least one core pin extending perpendicular to a surface of the mold and has a longitudinal axis. The radiation emitting element is adjacent the mold and positioned to emit a radiation beam proximate the core pin and perpendicular to the longitudinal axis of the core pin. The radiation receiving element is adjacent the mold and positioned to receive the radiation beam emitted from the radiation emitting element. The take-out controller is connected to the radiation receiving element and receives signals from the radiation receiving element. The machine controller, which is connected to the radiation emitting and receiving elements, provides power and control signals to the elements, and receives signals from the radiation receiving element.
In a further aspect of the invention, an apparatus for detecting the presence of an article on a mold core pin of an injection molding machine includes at least one radiation emitting element, at least one radiation receiving, a take-out controller, and a machine controller. The radiation emitting element is adjacent the mold and positioned to emit a radiation beam proximate the core pin and perpendicular to the longitudinal axis of the core pin. The radiation receiving element is spaced apart from the radiation emitting element and positioned to receive the emitted radiation. The take-out controller is connected to the radiation receiving element and provides a signal to stop a take-out device when the radiation receiving element indicates that the article has not been removed from a predetermined portion of the mold core pin. The machine controller, which is connected to the radiation emitting and receiving elements, provides power and control signals to the elements, and provides a signal to stop injection operations when the radiation receiving element indicates that the article has not been removed from the predetermined position.
In yet another aspect of the present invention, a method of detecting the presence of an article on a mold core pin of an injection molding machine includes positioning a radiation transmitting element to transmit radiation proximate the mold core pin and perpendicular to a longitudinal axis thereof, positioning a radiation receiving element at a position spaced apart from the radiation transmitting element, and determining that an article is still present on the mold core pin when the transmitted radiation is not received by the radiation receiving element. A signal is transmitted substantially simultaneously to both a machine controller and a take-out controller when it is determined that an article is present on the mold core pin.
In still another aspect of the present invention, an apparatus for controlling a vacuum device which removes molded parts from a a mold plate of an injection molding machine includes a controller which controls the vacuum device so as to apply a higher vacuum pressure to the molded parts to begin their removal from the mold plate, and to apply a lower vacuum pressure to the molded parts after they begin moving from the mold plate. This is because partially cooled parts are soft and can be deformed if exposed to a sustained high vacuum pressure.
In still a further aspect of the present invention, an apparatus for removing a molded article from a mold of an injection molding machine includes a plate, at le
Brand Tiemo
Klang Stephan
Lausenhammer Manfred
Luong Hai
Mai Arnold
Husky Injection Molding Systems Ltd.
Nguyen Nam
Nguyen Thu Khanh T.
Zavis Katten Muchin
LandOfFree
Detection and removal system for reducing cycle time of an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Detection and removal system for reducing cycle time of an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Detection and removal system for reducing cycle time of an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2590996