Cleaning and liquid contact with solids – Processes – Longitudinally traveling work of bar – strip – strand – sheet...
Reexamination Certificate
2000-03-17
2001-01-23
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Processes
Longitudinally traveling work of bar, strip, strand, sheet...
C134S12200P, C134S144000, C134S172000
Reexamination Certificate
active
06176939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for cleaning a transport belt of a machine for manufacturing a material web, in particular a paper or cardboard web and to a device for cleaning a transport belt of a machine for manufacturing a pulp web, in particular a paper or cardboard web. The cleaning device includes at least one nozzle for imparting a medium under pressure onto the respective transport belt. The nozzle is designed to rotate about a rotational axis at different rotational speeds and where the rotational axis of the nozzle may be tilted.
2. Discussion of Background Information
Devices of the type mentioned here are known. They serve to clean a transport belt, for example, a drying sieve or a press felt, of a machine to manufacture a pulp web. The cleaning device comprises a nozzle that can impart a medium under pressure, for example a liquid, and it is designed to be rotatable about a rotational axis. The spray emanating from the nozzle, which essentially impacts the transport belt vertically removes dirt, pulp fibers, particles, adhesives and the like from the transport belt. Through the rotational movement of the nozzle, the medium is applied to a surface area of the transport belt, through which a uniform cleaning can be achieved. It has been observed that the cleaning effect of the known cleaning devices do not always satisfy the demands and can therefore be improved upon. Furthermore, cleaning devices are known that avoid an insufficient cleaning in that the rotating nozzle imparts a medium under high pressure upon the transport belt. Thus, the power of the spray impacting the transport belt is increased, thereby increasing the cleaning effectiveness. However, it is disadvantageous in that the transport belt is subjected to the intense force of a hard spray, which, for the most part, impacts it vertically; sensitive transport belts, for example those that are made of a fine fabric, are subject to wear and tear, even to outright damage.
SUMMARY OF THE INVENTION
The present invention creates a cleaning device of the type named at the outset that does not demonstrate these disadvantages.
Accordingly, a cleaning device is provided that includes a nozzle that rotates about a rotational axis and wherein the rotational speed of the nozzle, in order to gently clean the transport belt, lies in the range of about 2500 rpm to about 4000 rpm and, for a more intensive cleaning of the transport belt, lies in the range of about 1000 rpm to about 2500 rpm. Through the high rotational speed of the nozzle, the period of time that the spray impacts the same portion of the transport belt is shortened as opposed to that of a slower rotation speed. This makes it possible to use the nozzle to impart a medium under high pressure upon the transport belt to increase the cleaning effectiveness and at the same time to keep the demands on the transport belt low, such that wear of or damage to the transport belt can be practically eliminated.
The force or the energy of the spray emanating from the nozzle at a high speed can also be used to gently clean the transport belt, since the high rotational speed allows the effects that are abrasive to a transport belt to be reduced to a harmless level. Dry sieves and press felts are examples of pinned or multi-filament sieves that undergo a gentle cleaning. The term “multifilament” characterizes transport belts that demonstrate a construction similar to that of textile fabric. The textile fabric consists of interwoven thread fibers, which in turn consist of numerous individual thread fibers. In order to subject a transport belt to an intensive cleaning, the rotational speed of the nozzle is reduced to about 1000 rpm to about 2500 rpm. By doing this, the period of spray application to the same area of the transport belt is extended such that obstinate contaminations on the transport belt can be removed. Due to their construction, single-filament sieves, the textile fabric of which consists of interwoven individual textile fibers, can be subjected to an intensive cleaning. By varying the rotational speed of the nozzle, the transport belt can be cleaned gently as well as intensely with a medium under at least substantially constant pressure.
According to another feature of the present invention, a cleaning device is provided that includes a nozzle that rotates about a rotational axis and wherein the central axis of the nozzle opposes the rotational axis and is tilted at an angle &agr;, lying in a range from about 2°≦|&agr;|≦60°, preferably from about 5°≦|&agr;|≦25°. The effective range of the nozzle can be varied and therefore the intensity of the cleaning controlled, and preferably adjusted. It has been shown that, depending on the inclination of the nozzle, a larger surface area of the transport belt can be cleaned with a peeling effect (gentle cleaning) or a relatively small surface area can be cleaned with a large cleaning impulse (intensive cleaning), whereby in both cases good cleaning results are attainable.
In accordance with another embodiment of the cleaning device, a nozzle is tilted at an angle &bgr; with respect to the surface normal of the transport belt, lying in a range of about −60°≦|&bgr;|≦60°. As a result, the effective range of the nozzle and the intensity of the cleaning can be influenced in an advantageous manner. Therefore, the smaller the angle &bgr; becomes, the more obtuse the angle of the spray that impacts the transport belt. In the opposite manner, an increasing angle &bgr; leads to a decreasing angle between the spray and the transport belt, so that the intensity of the cleaning decreases, whereby a desired cleaning of the transport belt is possible due to the peeling effect of the spray impacting the transport belt, for example, at an acute angle.
In accordance with a further embodiment of the cleaning device, the diameter of the nozzle ranges from about 0.05 mm to about 0.8 mm, and preferably from about 0.1 mm to about 0.4 mm. Through a small nozzle diameter, the use of liquid or gaseous media can be relatively contained, and operational costs of cleaning device can be reduced as a result.
In accordance with a still further embodiment of the cleaning device, the nozzle spaced from the rotational axis by a distance of about 5 mm to about 50 mm, preferably from about 10 mm to about 30 mm. Through the eccentric disposition of the nozzle with respect to the rotational axis, the area affected or cleaning area of the nozzle can be increased such that the effectiveness of the cleaning device can be further improved.
According to another embodiment of the present invention, the nozzle is provided with a medium under a pressure of about 100 bar to about 1000 bar, preferably about 100 bar to about 400 bar. It has been shown that an especially good cleaning result can be attained with a medium under high pressure, like water, for example.
Further embodiments and advantages can be seen from the detailed description of the present invention and the accompanying figures.
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Oechsle Markus
Straub Karlheinz
Coe Philip R.
Greenblum & Bernstein P.L.C.
Voith Sulzer Papiermaschinen GmbH
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