Coating apparatus – Immersion or work-confined pool type – Work-confined pool
Reexamination Certificate
2000-07-21
2003-06-17
Lamb, Brenda A. (Department: 1734)
Coating apparatus
Immersion or work-confined pool type
Work-confined pool
C118S262000, C118S413000, C118S261000
Reexamination Certificate
active
06579368
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention.
The present invention relates to an apparatus for the application of a liquid or pasty medium to a moving base.
2. Description of the related art.
A base for the application of a liquid or pasty medium, in the case of direct application, is the surface of a fiber material web, in particular of paper or cardboard. Alternatively, in the case of indirect application, the surface of a transfer element, for example a transfer roll, transfers the medium to the material web, the medium being brought into contact with the moving base in an application chamber. The application chamber is bounded on the inlet side by a metering doctor device, with respect to the running direction of the base with the two doctor devices being arranged on a carrying beam.
An application apparatus of this type is disclosed, for example, by DE 44 44 779 A1. In the case of this application apparatus, the metering doctor device bounding the application chamber on the outlet side is designed as a roll doctor, whose doctor bed is fixed directly on the carrying beam via a holding blade. In order to influence the setting of the metering doctor against the base in accordance with the operation, an actuating device is provided. On the inlet side, the application chamber is likewise bounded by a roll doctor device, the doctor bed accommodating the doctor rod being fixed to a carrier beam by a spring-loaded holder. Specific influence of the setting of the sealing doctor rod against the base is not possible during the continuous operation of the application apparatus. Because of the above-described holding of the doctor devices by flexible blades, the distance between the two roll doctors can vary slightly, which entails a corresponding variation in the volume of the application chamber. Consequently, the medium has to be fed to the application chamber with a high excess in order to ensure in the application chamber pressure relationships which permit a reproducible coat weight of the medium leaving the application chamber of the application layer to be obtained.
The same is also true of the application apparatus disclosed by EP 0 319 503 B1 (see, in particular,
FIG. 10
) and the application apparatus disclosed by DE 84 14 904 U1. The two last-mentioned application apparatuses additionally have the disadvantage that the doctor bed or the blade holder of at least one of the two doctor devices is also used at the same time for bounding the feed line for feeding the medium into the application chamber. On the one hand, this creates sealing problems and, on the other hand, when the setting of the respective doctor device against the moving base is changed, it also inevitably leads to an influence being exerted on the quantity of medium fed to the application chamber per unit time (medium feed rate). Such an influence further has a detrimental effect on the pressure relationships prevailing in the application chamber.
In addition, DE 196 52 289 A1 discloses an application apparatus of the generic type in which both the sealing doctor device and the metering doctor device are a doctor rod. The two doctor rods are accommodated in a common doctor bed, in which the feed line for the medium is also located. The feed line is fixed to the carrying beam via an elastic blade. Furthermore, two actuating devices are provided, one of which acts on the doctor bed in the region of the sealing doctor rod and the other acts in the region of the metering doctor rod. Although, in the case of this application apparatus, on the one hand the size of the application chamber and on the other hand the quantity of medium fed per unit time depend to a lesser extend on the setting of the two doctor devices against the base. The disadvantage with this arrangement is that a change in the influence of one of the two actuating devices on the doctor bed always leads to an influence being exerted on the setting of the respective other doctor device against the moving base, so that coat weight and excess quantity cannot be adjusted independently of each other.
For completeness, reference should further be made to DE 29 13 053 A1 in relation to the prior art.
SUMMARY OF THE INVENTION
By contrast, the present invention specifies an application apparatus of the generic type which, while maintaining the capability of independently exerting an influence on the setting of the two doctor devices against the moving base, makes it possible to obtain defined volume and/or pressure relationships in the application chamber.
According to the invention, an application apparatus of the type mentioned at the beginning uses two doctor devices which are fixed to an essentially rigid supporting unit provided on the carrying beam. On account of the essentially rigid construction of the supporting unit, the doctor devices are kept at a predetermined distance from each other in the running direction of the base. On account of the rigidity~of the supporting unit, this predetermined distance is, in this case, essentially independent of the quantity of medium fed to the application chamber per unit time, the pressure prevailing in the application chamber and the respective setting of the two doctor devices against the base. Furthermore, the essentially rigid supporting unit ensures a defined arrangement of the two doctor devices in the transverse direction of the base as well. Overall, in this way, the conditions prevailing in the application chamber and medium feed, in particular volume and/or pressure, can be reproduced so reliably that the excess quantity which leaves the application chamber past the sealing doctor device can be reduced considerably, as compared with the prior art and, consequently, a high-quality application layer can be obtained. As a result of reducing the excess quantity, the circulated quantity of the medium can be reduced, and thus the delivery pump assigned to the medium feed can be designed to have a correspondingly lower performance and therefore to be more cost-effective in procurement and operation.
Moreover, the essentially rigid supporting unit permits the two doctor devices to be fixed to it in such a way that their settings against the moving base can be influenced independently of each other, without a change to the setting of one of the two doctor devices which would otherwise result in back-effects on the setting of the respective other doctor devices. The resulting decoupling of the two doctor devices simplifies their driving and thus increases their adjustment potential. This can be achieved, for example, by making it possible for the two doctor devices to be fixed to the supporting unit independently of each other.
In a development of the invention, it is proposed that the supporting unit include feed channels which feed the medium from a distribution pipe to the application chamber. In this way, the influence exerted on the quantity of medium fed to the application chamber per unit time can be decoupled largely, if not completely, from the influence exerted on the setting of the two doctor devices against the base. For example, the feed channels can be constructed as through holes, bores or the like in the supporting unit. Alternatively, the feed channels could also run through at least one of the doctor devices, for example through a doctor bed of a roll doctor device. In particular in the case of an application apparatus with a relatively low operating width and/or an application apparatus for applying medium at a relatively low coat weight, it may be advantageous for the distribution pipe also to be formed in the supporting unit. This simplifies, at least, the construction of the carrying beam.
In order to be able to achieve the most uniform possible distribution of the medium emerging from the feed channels in the transverse direction of the base, that is to say over the operating width, it is proposed that at least one baffle plate be arranged on the supporting unit in the area of the outlet openings of the feed channels into the application chamber. This baffle plate prevents t
Henninger Christioph
Kohl Bernhard
Kurtz Rüdiger
Kustermann Martin
Mendez-Gallon Benjamin
Lamb Brenda A.
Taylor & Aust P.C.
Voith Sulzer Papiertechnik Patent GmbH
LandOfFree
Apparatus for the application of a liquid or pasty medium to... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for the application of a liquid or pasty medium to..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for the application of a liquid or pasty medium to... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3087902