Fluid sprinkling – spraying – and diffusing – With cleaning means – drip collecting – waste disposal or soil... – Nozzle cleaner – flusher or drainer
Reexamination Certificate
1999-10-22
2001-02-27
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
With cleaning means, drip collecting, waste disposal or soil...
Nozzle cleaner, flusher or drainer
Reexamination Certificate
active
06193167
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a plant for automatic spray application of paint through a spray nozzle included therein, said plant comprising at least two arrangements for providing paint for spray application connected to the spray nozzle through first supply lines arranged in parallel to each other, means for feeding paint in the respective line from the respective arrangement to the spray nozzle as well as first valve means arranged in the respective line downstream of the feeding means with respect to the feeding direction and controllable to open and close the fluid connection between respective arrangement and the spray nozzle so as to allow spraying of paint coming from one arrangement at the time, as well as a method for automatic spray application of paint.
Such a plant may have different fields of use, but the use of such a plant for painting objects, such as car bodies, by a spray painting robot will hereinafter be mainly discussed for illuminating the invention but not in any way restricting it.
A plant of this type having at least two mutually parallel lines is used primarily so as to reduce the time periods of inactivity when changing paint or color by cleaning one of the lines and make it ready for feeding any new paint it hasn't fed before, while the other of the lines feeds a paint of a certain type to the spray nozzle, so that change of arrangement, i.e. application of a paint of a new type, may take place rapidly.
The arrangements, which usually are constituted by color changing arrangements with a magazine of a series of different paints or colors as well as solvents and valves and regulating means belonging thereto, are most often comparatively bulky and heavy and are bad suited to be placed close to the spray nozzle, for example in the robot case, and for instance when painting car bodies a move of the arrangement to the region of the spray nozzle would mean that the robot couldn't come into and paint the car body internally, so that the first line usually has a considerable length, which for example in the case of spray painting robots for painting vehicles may amount to some meters. When the arrangement providing paint to the spray nozzle is to be changed the paint present in the first line in question is in these plants already known flushed out through the spray nozzle to the exterior and gets completely lost. It is usually sprayed out by flushing the line by a solvent provided by the arrangement. The great length of the first line means that a not negligible volume of paint is lost in this way at each change, which over a longer period of time results in high costs. Furthermore, the paint sprayed out is bad for the environment and smear the surroundings, so that, for example cabins in which painting takes place have to be cleaned relatively frequently. It is not possible to solve this problem with paint losses by spraying the paint out into containers instead, since an unacceptable large amount thereof would be required and the paint is also degraded in the contact with air.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a plant of the type mentioned in the introduction, which finds a remedy to the inconveniences mentioned above of conventional plants.
This object is according to the invention obtained by providing such a plant with a device adapted to, after feed of paint through a first line to the spray nozzle followed by closing the associated valve means for changing to another arrangement providing paint, at a location upstream of the associated first valve means with respect to the spray feeding direction into this first line feed such a volume of a fluid in the reverse direction with respect to the feed that the paint present in this first line is pushed back into the arrangement without the latter being reached by the fluid.
By supplying a fluid to the first line in this way for pushing the paint present in the first line back all the paint pushed back, into the arrangement may be saved and used next time paint of that type is to be supplied to the spray nozzle through the arrangement. It is an important characteristic of the invention that not that much fluid is fed into the first line that also this fluid reaches the arrangement, since that would unacceptably lower the quality of paint in the arrangement. The plant according to the invention not only results in a considerable saving of paint and therefore costs, but the minimal waste of paint is considerate of the environment and cleaning of possible cabins in which the spray application is carried out becomes almost superfluous.
According to a preferred embodiment of the invention the device has means for dosing the fluid for feeding a predetermined volume thereof into the first line in the reverse direction. Such a dosing means is advantageous, since it is extremely important that the volume of fluid fed into the first line in the reverse direction is well adjusted, and the obtaining this is facilitated by such a dosing means.
According to another preferred embodiment of the invention the dosing means is adapted to ensure feeding of a volume of fluid in the reverse direction of the first line substantially corresponding to the volume of this first line from the location of the inlet of the fluid into this first line and to the associated arrangement. A minimum waste of paint is obtained by this design of the dosing means.
According to another preferred embodiment of the invention, the dosing means comprises means for adjusting the predetermined volume of fluid fed by the aforementioned means, which constitutes a simple and reliable realization of the dosing means. It is underlined that “corresponding” is to be given a broad sense and means that the stroke volume is so selected that the fluid fed into the first line exactly manages to push substantially all the paint present in the first line back into the arrangement in question without entering therein itself.
According to another preferred embodiment of the invention, the device comprises means adapted to feed the fluid into the first line with a pressure exceeding the pressure of the paint present in the first line, the means for feeding the fluid comprises a piston cylinder actuated by a pressure medium on the first side of the piston so as to press a fluid located on the opposite side of the piston out of the cylinder, and the surface for the action of the pressure medium upon the first side of the piston exceeds the surface for the action of the piston upon the fluid on the other, second side of the piston for obtaining a pressure increase between the pressure medium and the fluid. For example the compressed air normally already available in an industrial building may by this be used for feeding the fluid into the first line, which also constitutes a further preferred embodiment of the invention.
According to another preferred embodiment of the invention, the device is adapted to feed a fluid in the form of an agent cleaning the first line into the first line in the reverse direction thereof. This is very advantageous, since a flushing of the fluid back out of the first line will then automatically result in a cleaning of the first line, which in any case is necessary before the first line may be filled again by paint of another type for spray application thereof.
According to another embodiment of the invention the device is adapted to feed a solvent into the first line. A cleaning of such a first line by a solvent is normally required, and by using a solvent for pushing the paint back into the arrangement in this way the flushing of the solvent out of the first line may in this way result in an automatic cleaning thereof.
According to another embodiment of the invention the arrangements are color changing arrangements, which constitutes a very preferred application of the plant according to the invention.
According to another embodiment of the invention the plant has a second line connected to the first line through a second valve means and means adapted to, after t
ABB Flexible Automation A/S
Hwu Davis
Kashnikow Andres
Pollock Vande Sande & Amernick
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