Patent Application
20070218815
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 10 2006 011 618.6 filed Mar. 14, 2006, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
This invention relates to a machine for producing web material, in particular paper or paperboard, which comprises a generally endlessly constructed transport belt guided over a multiplicity of rollers. In addition the invention relates to a method for treating the surface of a transport belt which is integrated in such a machine for producing web material.
2. Discussion of Background Information
In the production of web material such as paper or paperboard, the web material to be produced or the starting material therefore is spread out flat on one or more consecutive transport belts and, using the transport belts, is passed through various sections such as press sections, in which the desired properties of the web material are established and also in particular water is drawn out of the web material. The transport belts which move the web material forward are generally endlessly constructed and guided over a multiplicity of rolls or rollers of which at least some are driven to rotate such that the transport belt moves in the longitudinal direction of the belt. The starting material for the web material to be produced contains a comparatively large fraction of liquid, hence the surface of the transport belt is also covered with liquid and ultra-fine particles of the starting material in particular after passing through press sections.
To obtain an optimum interaction of the transport belts with the web material or starting material therefore, it is known for the belt surface which comes into contact with the web material to be equipped with a surface roughness or for depressions or grooves or flutes to be provided on the surface in order to make available a certain bulk in which the liquid escaping from the web material can be accommodated. Particles escaping from the web material cover the surface of the transport belt and therefore also influence the surface properties of the belt, hence from WO 2005/094403 A1 it is known for the transport belt to be assigned a treatment apparatus with which contaminants on the surface of the transport belt are removed, thus cleaning the surface. For this purpose the transport belt comes into contact with a roller, which is driven to rotate and can rotate or move faster or slower than the transport belt. Large amounts of contaminants can thus be removed from the transport belt. In addition there are apparatuses with which water and/or chemicals can be applied to the surface of the belt in order to support in this way the removal of contaminants from the surface.
The present invention provides a machine for producing web material, in particular paper or paperboard, and a method for treating a transport belt contained in such a machine. With the invention, desired properties can be preserved or achieved during the production of web material throughout the working life of the transport belt.
According to a first aspect of the invention, a machine for producing web material, in particular paper or paperboard, includes at least one transport belt for the web material. The belt is guided over a multiplicity of rolls, and a treatment apparatus is assigned to the transport belt. The apparatus has at least one treatment unit for roughing up a surface of the transport belt.
With the current invention, physical treatment of the surface of the transport belt assures any surface roughness of the belt, which may also exist in the new state for example, is preserved. This may be advantageous because it is not only possible for the surface of the transport belt to be covered with particles contained in the starting material for the web material such that the surface condition can also be changed, but because the surface roughness of the transport belt can be disadvantageously impaired above all due repeatedly passing through press rollers which exert a high load on the surface when such a transport belt is used in press sections. With the inventive machine, it is also possible to vary the surface condition, meaning above all the roughness of the surface, on a transport belt integrated in the machine through a corresponding roughing treatment such that it is also possible to exert a corresponding influence on the production result by changing the surface roughness in the course of use.
In an advantageous embodiment, the treatment apparatus can include at least one treatment unit which can be moved over and across the transport belt transverse to a longitudinal direction of the web. The advantage of a treatment unit which can be moved over and across the transport belt is that it can be constructed comparatively compactly but still be used in conjunction with far wider transport belts. Moreover, it is possible in very simple manner to obtain a variation in the surface condition or surface roughness of such a transport belt in the transverse direction.
In an alternative embodiment, the treatment apparatus can include comprise at least one treatment unit which has a treatment element extending essentially over the entire width of the transport belt.
A very intensive roughing of the surface of the transport belt can be achieved by a treatment apparatus including at least one treatment unit with a treatment element rotating about an axis of rotation. In this case, the rotating treatment element can rotate about an axis of rotation extending essentially in the transverse direction of the belt. This is particularly suitable when such a treatment element extends over and across the entire transport belt or over an essential part of the transport belt.
Alternatively, it is possible for the treatment element to rotate about an axis of rotation which is not parallel to a belt surface of the transport belt. This variant is advantageous in particular when the treatment unit is constructed such that it can move over and across the transport belt in the transverse direction. For example, provision can be made for the axis of rotation to be essentially orthogonal to the belt surface.
The rotating treatment element can be an abrasive brush, for example, a steel brush. Alternatively, the rotating treatment element can provide a rough treatment surface which in the manner of abrasive paper or a file roughs up the surface of the transport belt accordingly when in contact with it.
An embodiment which is very easy to realize constructionally can include, in addition for the treatment apparatus, at least one treatment unit with a beam-like treatment element. In this regard, no rotating treatment elements are required. Instead, a fixed treatment element creates the roughing effect through its interaction with the surface of the transport belt.
As previously explained, it can be advantageous to vary the surface characteristic of a transport belt in the course of its working life. For this purpose, it is also proposed according to the invention for the treatment apparatus to include at least one treatment unit with variable treatment characteristic.
The variable treatment characteristic can be obtained in that, for example, the at least one treatment unit with variable treatment characteristic includes a treatment element providing a rough treatment surface. In this regard, the treatment surface has surface regions of varying roughness.
For example, the treatment surface can be curved and have a varying surface roughness in the curving direction.
Also, provision can be made for the treatment element to be constructed at least partly like a cylinder and for it to be rotatable about an axis essentially parallel to the transverse direction of the transport belt.
To support the surface treatment or/and to remove particles resulting during the surface treatment it is proposed to assign to at least one treatment unit an apparatus for applying liquid to the surface of the transport belt to be treated. The liquid can include a cleaning agent or/and a lubricant for example.
Furthermore, it is possible in principle to provide for the treatment unit to include at least one cleaning unit for cleaning a surface of the transport belt after a roughing treatment is carried out. By using such a cleaning unit, it is possible to ensure that the particles abraded during the surface treatment are not transported into that region in which the transport belt comes into contact with the web material to be produced.
In addition, the treatment apparatus can include a sensor arrangement for detecting the surface condition of the transport belt. By providing such a sensor arrangement it becomes possible to detect when a surface treatment should be carried out, e.g., when the surface of a transport belt becomes too smooth. Further, thanks to the sensor arrangement, it is also possible to detect the result of the treatment, i.e., whether the surface treatment has helped to rough up the transport belt sufficiently.
Furthermore, the treatment apparatus may include at least one treatment unit for roughing up a surface of the transport belt on the web material side or/and at least one treatment unit for roughing up a surface of the transport belt on the machine side. As previously explained, what is advantageous or necessary above all is the treatment of the surface which comes into contact with the web material in order to be able to ensure a constant quality of the web material throughout the working life of the transport belt. However, it can also be advantageous to treat the surface on the rear side, i.e., the machine side or the running side. This surface can also be equipped with a certain roughness in order to ensure that sufficient interaction of static friction is created with the rollers or rolls by which the transport belt is driven into motion. The machine-side surface of the transport belt will also become covered with liquid and contaminants or will become smoother and smoother on account of passing repeatedly through press nips, thus giving rise to a risk of slip between the transport belt and the driving devices. This can be counteracted by roughing treatment of the machine-side surface.
According to another aspect of the current invention, a method for treating a surface of a transport belt provided on a machine for producing web material, in particular paper or paperboard, includes roughing up of the surface of the transport belt.
To ensure particles abraded during the surface treatment do not impair the production result of a machine for producing web material, the method may be performed in a treatment phase in which no web material is transported by the transport belt. Production is not started again until the surface treatment has been performed and the transport belt has been sufficiently cleaned. It should be noted, however, that it is also possible of course for the inventive method to be performed during the production of web material, in which case steps are preferably taken through the use of suitable cleaning units to remove the abraded material before the transport belt comes into contact again with the web material.
Furthermore, the inventive method can be performed such that the surface of the transport belt is treated to provide a surface roughness varying in a transverse direction of the transport belt. A surface roughness varying in a transverse direction can be advantageous above all with regard to easier releasing of the transport belt from the web material to be produced. Here, too, it must be stressed, that it is of course possible alternatively for the surface treatment to be performed such that a slight surface characteristic or surface roughness is achieved over the entire surface in the transverse direction, at least in those regions in which the transport belt comes into contact with the web material to be produced.
The present invention is directed to a machine for producing web material. The machine includes at least one transport belt structured and arranged for transporting the web material, a plurality of rolls over which the at least one transport belt is guided, and a treatment apparatus, assigned to the at least one transport belt, composed of at least one treatment unit structured and arranged to roughing up a surface of the at least one transport belt.
According to the invention, the web material can be paper or paperboard.
In accordance with a feature of the instant invention, the at least one treatment unit may be movable, in a direction transverse to a belt run direction, over and across the at least one transport belt.
Further, the least one treatment unit can include a treatment element extending essentially over an entire width of the at least one transport belt.
The at least one treatment unit may be composed of a treatment element rotatable about an axis of rotation. Moreover, the treatment element can be rotatable about an axis of rotation extending essentially transversely to a belt run direction. Alternatively, the treatment element may be rotatable about an axis of rotation that is not parallel to a surface of the at least one transport belt. In this regard, the axis of rotation may be essentially orthogonal to the surface. Further, the rotatable treatment element can include an abrasive brush, which may be a steel brush. The rotatable treatment element can be structured and arranged to roughen the surface.
According to another feature of the invention, the at least one treatment unit may include a beam-like treatment element.
In accordance with still another feature of the present invention, the at least one treatment unit can be structured and arranged to produce variable treatment characteristics. The at least one treatment unit can include a treatment element with a rough treatment surface. Further, the rough treatment surface may include surface regions of varying roughness. The rough treatment surface may be curved and a roughness of the rough treatment surface can vary in a direction of curvature. The treatment element can include at least a portion of a cylinder rotatable about an axis essentially parallel to a direction transverse to a belt run direction.
Moreover, the machine can include an apparatus for applying liquid to the surface of the at least one transport belt being associated with the at least one treatment unit. The liquid may include at least one of cleaning agent and lubricant.
According to another feature of the instant invention, the treatment apparatus can include at least one cleaning unit for cleaning the surface of the at least one transport belt after the roughing up of the surface.
Moreover, the treatment apparatus can include a sensor arrangement for detecting a surface condition of the at least one transport belt.
The at least one treatment unit can include two treatment units positionable on opposite sides of the at least one transport belt being structured and arranged to roughing up a web contacting surface of the at least one transport belt and a plurality of rolls contacting side of the at least one transport belt.
The invention is directed to a method for treating a surface of a transport belt for a machine for producing web material. The method includes roughing up a surface of the transport belt. The web material can be paper or paperboard.
According to a feature of the invention, the roughing up can occur during a treatment phase when no web material is being transported by the transport belt.
In accordance with still yet another feature of the present invention, the roughing up may produce a surface roughness varying in a direction transverse to a belt travel direction.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.
The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
Such a transport belt 18, as used on machines for producing paper, is generally equipped with a certain surface roughness at least on web material side surface 20, e.g., in a roughness range R, from 0.5 to 80 μm. Such a surface roughness creates a near-surface bulk in which water pressed out of the starting material for producing the paper can be accommodated at least partly, making it possible to prevent or reduce the formation of a continuous water film which impedes the releasing of the web material from transport belt 18.
Through the passing of transport belt 12 through the press nip formed between rollers 14 and 16, which takes place repeatedly or continually during operation, transport belt 18 is constantly exposed during operation to a compression, which, also because of the elasticity of the construction material used for transport belt 18, results in the surface roughness decreasing throughout the course of the belt's working life. Another factor which essentially influences the surface condition or surface roughness of transport belt 18 is the surface wear which is generated by, inter alia, abrasive fillers contained for this purpose in the web material or the starting material. Similarly, particles from the construction material of the web material, which embed in the surface of transport belt 18, lead to a disadvantageous impairment of the surface property. According to the invention, a treatment apparatus 26 is arranged on machine 10 in order to roughen up the surface of transport belt 18 installed on machine 10. Looking in the direction of movement, treatment apparatus 26 lies either after press section 12 or after an apparatus 28 that follows press section 12, which can be used to remove liquid that has collected on surface 20 on the web material side of transport belt 18. Apparatus 28 can comprise, e.g., a suction roller 30 or the like.
Treatment apparatus 26 includes a treatment unit 34 lying opposite a back pressure roller 32. Treatment unit 34 is slidably guided in the transverse direction by a multiplicity of rolls 38 on a rail-like carrier 36 extending transverse to a belt longitudinal direction L. A drive (not shown) is assigned to treatment unit 34 in order to move treatment unit 34 to and fro on carrier 36 transversely to a belt run direction in order to be able to position it opposite or adjacent a desired surface region of transport belt 18.
The exemplary treatment unit 26 presented in
Treatment apparatus 26 can also include a sensor arrangement 46. Sensor arrangement 46 can be arranged to scan, e.g., optically, the surface of transport belt 18 and supply output signals in relation with the surface condition. Thus, sensor arrangement 46 can provide information that can be used, when suitably evaluated, to decide when and/or in which regions of transport belt 18 a roughing treatment should to be performed. Of course, it is also possible to use sensor arrangement 46 or its output signal to decide, after carrying out such a treatment operation, whether the desired surface condition, i.e., roughness, has been obtained.
When it is decided to carry out such a treatment, the transport belt 18 can be driven to rotate in a phase, e.g., when no web material is being produced by machine 10. Transport belt 18 is then guided to move through treatment apparatus 26. Treatment element 40 is held under pressure against surface 20 and driven to rotate in order to roughen up surface 20 of transport belt 18 through the abrasive action of treatment element 40. If necessary, liquid can also be applied using spraying apparatus 44. In this case, treatment unit 34 can be moved transversely to belt longitudinal direction L in order to treat transport belt 18 successively over its entire width. Of course, should it be advantageous or desired, the treatment can be performed differently in certain regions of transport belt 18 in the transverse direction. For example, the contact pressure of treatment element 40 against surface 20 can be changed depending. upon the position of treatment unit 34 in the transverse direction, the speed (rpm) of treatment element 40 can be changed, and the time spent by treatment element 40 in processing various regions of transport belt 18 can be varied. Of course, it is also possible to process surface 20 such that a uniform surface condition or surface roughness is obtained over the entire width and, of course, also over the entire length.
If necessary, it also contemplated that the treatment operation can be performed in a phase in which web material is being moved by transport belt 18. In this regard, it is. advantageous to ensure material abraded from transport belt 18 during the roughing treatment of the surface is removed, so it cannot later contaminate the web material. For this purpose, the treatment unit 34 can include a cleaning element such as a cleaning brush or the like to clean the surface of transport belt 18. In the exemplary embodiment of
Of course, it is understood the above-described treatment unit 34 can be constructed differently than as shown in the illustrated embodiment of
By performing such a surface treatment it is possible not only to preserve original surface roughness during operation but also to ensure that particles integrated in the bulk region of transport belt 18, whose function it is to provide a variation of surface energy, are uncovered again and thus activated. Moreover, through the selective surface treatment the roughness of transport belt 18 can be varied throughout its working life in order to thus identify where an adjustment or optimization of the surface behavior may be necessary during the production of the web material. By way of non-limiting example, it may be advantageous to equip transport belt 18 in the new state with an essentially smooth surface, i.e., with a surface roughness which is smaller than that actually to be provided for the production of paper or the like but which is sufficient for the required release of the web material. During operation, the surface roughness achieving the best production results can be sought or investigated. Thus, the optimum surface roughness is not achieved until operation of treatment apparatus 26 according to the invention.
An alternative embodiment of an inventive machine is presented in
The two treatment units 34 and 34′ can each have spraying apparatuses or the like in order to be able to apply cleaning liquid or a medium influencing the abrasion behavior onto surfaces 20 and 22. Also, a cleaning brush or some other cleaning device can be assigned to treatment units 34 and 34′ in order to remove the particles abraded from surfaces 20 and 22. Of course, it is also contemplated, in a manner similar to the arrangement presented in
Similarly, on the treatment elements 40 and 40′ used in the embodiment in
In the modification presented in
Similar to roller-like treatment elements 40a and 40a′ depicted and described in relation to the exemplary embodiment according to
Another alternative embodiment of treatment unit 34 is depicted in
Of course, it is possible for a spraying apparatus or some other apparatus for applying a liquid medium also to be assigned to treatment unit 34 shown in
With treatment apparatus 26 one or both surfaces of a transport belt 18 can be treated in order to obtain a desired surface roughness. Influence can be exerted selectively on the obtainable surface roughness through the construction or selection of the treatment elements used, the contact pressure, the angle of inclination of the treatment element in particular on the beam-like embodiment presented in
Finally it should be noted that it is of course possible for the previously described invention to be constructed or modified in various other forms. For example, it is possible, given the use of rotating treatment elements for a treatment unit to have several such treatment elements or, for several treatment units to be used as required, each comprising at least one rotating treatment element as required. If several treatment elements are provided in one or, if required, several treatment units, then the treatment elements can rotate in the same direction of rotation or they can have, at least in part, opposing directions of rotation in order thus to create a desired surface condition through superimposition of the treatment characteristics obtainable respectively by means of the treatment elements. In embodiments with treatment units or treatment elements moving transverse to the belt longitudinal direction it is of course possible for such treatment elements to be constructed with an extension length which is smaller than the belt width so that with each positioning transverse to the belt longitudinal direction only a certain longitudinal region of the transport belt is respectively covered and treated by such a treatment element. Of course, it is also possible for treatment elements, which extend over and across the entire width of such a transport belt and are thus able to treat the entire surface of the transport belt without moving transverse to the longitudinal direction of the transport belt, to move in the transverse direction in order to modify the treatment effect in this way.
Further, it should be noted that movement transverse to the belt longitudinal direction or of an extension transverse to the belt longitudinal direction refers movement or direction of extension orthogonal to the belt longitudinal direction. However, given a movement transverse to the belt longitudinal direction it is possible of course for this movement to also coincide with a superimposed movement in the belt longitudinal direction, thus resulting in a movement or direction of extension oblique to the belt longitudinal direction which in each case includes a direction component transverse, meaning orthogonal, to the longitudinal direction.
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 011 618.6 | Mar 2006 | DE | national |
