1. Field of the Invention
The invention relates to a belt for a machine for the production and treatment of a fibrous web, in particular a paper, cardboard or tissue machine, as well as to a method to manufacture said belt.
2. Description of the Related Art
Belts are used in machinery for the production and treatment of a fibrous web for example in the press section in order to transport the fibrous web through the press nip and subsequently to a transfer location where the fibrous web is transferred to the following dryer section.
Belts generally comprise at least one polymer coating providing the paper side of the belt into which a load-bearing textile fabric is embedded.
The known transport- or process belts often tend to delaminate during operation. The polymer coating which extends from the paper side to the machine side of the belt was applied from both sides of the textile fabric which therefore has an interior interface at which the polymer coatings separate during operation due to flexing.
In addition, the known transport- and process belts have several coating segments arranged adjacent to each other in cross machine direction, each of which represent only a partial width of the total polymer coating and which together form the polymer coating. The hitherto known transport- or process belts often break at the contact points of the coating segments.
In view of the aforementioned disadvantages, what is needed in the art is improved belts, as well as improved methods for their manufacture.
According to a first aspect of the invention, the present invention provides a transport- or process belt for a machine for the production or treatment of a fibrous web, especially a paper, cardboard or tissue machine, which has a paper side and a machine side, as well as a polymer coating and which includes a load-bearing textile fabric; whereby the textile fabric has a first side facing the paper side and a second side facing the machine side; whereby the textile fabric is permeable and has a permeability of at least 300 cfm, preferably of at least 550 cfm, and the polymer coating extends integrally from the first side of the textile fabric through the openings in the textile fabric to the second side of the textile fabric.
Based on the fact that the textile fabric has a permeability of at least 300 cfm, a polymer coating extending integrally from the first side of the textile fabric through the openings of the textile fabric to the second side of the textile fabric can be formed. Therefore, delamination of the polymer coating is almost impossible. Integrally in this context is to be understood that, viewed in thickness direction of the polymer coating, no interface exists inside the polymer coating extending from the first side to the second side of the textile fabric as could for example develop if the polymer material is applied onto the textile fabric from both sides and then meeting somewhere inside the textile fabric structure, thus forming an interface.
According to a second aspect of the invention, the present invention provides a method for the manufacture of a transport or process belt for a machine for the production or treatment of a fibrous web, in particular a paper, cardboard or tissue machine, with a textile fabric and a polymer coating comprising the following steps:
By providing an overlap area of adjacent coating segments, their bond with each other is clearly improved.
According to a third and alternative and/or additional aspect of the invention, the present invention provides a method for the manufacture of a transport or process belt for a machine for the production or treatment of a fibrous web, in particular a paper, cardboard or tissue machine, comprising the following steps:
The helix-type application of the polymer material upon the textile fabric creates a polymer coating which progresses uninterrupted in machine direction.
According to a fourth alternative and/or additional aspect of the invention, the present invention provides a method for the manufacture of a transport or process belt for a machine for the production or treatment of a fibrous web, in particular a paper, cardboard or tissue machine, by coating a permeable textile fabric with polymer material in a viscous state, whereby a gap shaped forming channel is formed through which the textile fabric is led, whereby the forming channel has a front and a back limiting area each extending parallel to the textile fabric and between which the textile fabric is guided, whereby a first forming belt is provided which provides one of the two limiting areas and which is moved in the same direction as the textile fabric and essentially at the same speed while the viscous polymer material is fed into the forming channel and is carried along by the textile fabric and the first forming belt. Thereafter the first forming belt is separated from the polymer material at the end of the forming channel, whereby the first forming belt in the area of one of its longitudinal edges—on the side facing the textile fabric—has an elevation extending parallel to the longitudinal edge of the forming belt which provides a laterally limiting area of the forming channel.
By providing a lateral limiting area of the forming channel through the forming belt, the width of the overlapping region of the adjacent coating segments can be defined. This allows for a defined control and improvement for bonding between the coated segments.
According to a fifth alternative and/or additional aspect of the invention, the present invention provides a method for the manufacture of a transport- or process belt for a machine for the production or treatment of a fibrous web, in particular a paper, cardboard or tissue machine, by coating a permeable textile fabric with polymer material in a viscous state, whereby a gap shaped forming channel is formed through which the textile fabric is led, whereby the forming channel has a front and a back limiting area each extending parallel to the textile fabric and between which the textile fabric is guided along a transport direction, whereby means are provided through which the textile fabric is held during coating with the viscous polymer material so that it causes no waves or wrinkles.
The means ensure that the textile fabric is centered in the polymer coating. It is further ensured that the textile fabric is evenly embedded in the polymer coating, thereby clearly increasing the dimensional stability of the finished transport or process belt.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
a and 6b shows the device from
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
Textile fabric 5 is permeable and has a permeability of at least 300 cfm, preferably at least 550 cfm. Polymer coating 4 extends integrally from the first side 6 of textile fabric 5 through openings 8 in textile fabric 5 to the second side 7 of the textile fabric 5.
Hereby the polymer coating 4 is preferably produced—at least from the first side 6 to the second side 7 of textile fabric 5—from a single polymer material. This embodiment provides a belt which has practically no tendency to delaminate.
In the current example polymer coating 4 extends in a single piece from paper side 2 of belt 1 to machine side 3 of belt 1, and is produced preferably from a single polymer material from paper side 2 of belt 1 to machine side 3 of belt 1.
Belt 1 can have an overall thickness in the range of approx. 2 mm to approx. 6 mm, whereby preferably the ratio of overall thickness of belt 1 to the thickness of the textile fabric 5 is in the range of 2:1 to 5:1.
The total width of the belt can be in the range of approx. 1 m to approx. 12 m.
The polymer material of the polymer coating exemplarily includes polyurethane. Advantageously the polymer material consists completely of polyurethane. In addition one or several filler(s) may be embedded into polymer coating 4.
Textile fabric 5 has a center plane extending through the center of the thickness of textile fabric 5 which is indicated in the illustration in
In addition, polymer coating 4 is preferably impermeable, so that consequently an impermeable belt 1 is provided.
Textile fabric 5 preferably has a permeability in the range of approx. 500 cfm to approx. 1200 cfm, preferably approx. 550 cfm to approx. 900 cfm.
Textile fabric 5 can be formed by itself or in combination with a woven fabric, a spiral wire or a yarn array. In the current example the textile fabric is provided by a woven fabric.
Textile fabric 5 comprises machine direction threads 9 and cross machine direction threads 10, whereby cross machine direction threads 10 have a greater flexural strength in their longitudinal direction than the machine direction threads 9 in their longitudinal direction. Textile fabric 5 which represents the load-bearing structure of the belt hereby gains a very high flexural strength in cross machine direction (CMD) and thereby a high dimensional stability. The higher flexural strength of cross machine direction threads 10 as opposed to the flexural strength of the machine direction threads can be achieved for example in that the machine direction threads 9 in their cross section have a greater width than height, whereas the cross machine threads 10 in their cross section have a width which is equal to the height. The different flexural strength may however also be influenced or completely determined by the selection of the material or materials from which machine direction threads 9 and cross machine direction threads 10 are manufactured.
In the current design example textile fabric 5 is in the embodiment of a woven fabric 5, meaning that machine direction threads 9 are interwoven with cross machine direction threads 10, whereby in order to form woven fabric 5 machine direction threads 9 are more curved in their longitudinal progression than the cross machine direction threads 10 in their longitudinal progression.
Cross machine direction threads 10 progress preferably not curved in their longitudinal direction.
According to a preferred embodiment of the invention, woven fabric 5 comprises a repeat weaving pattern.
For example the machine direction thread of the first type 9.2 floats on the first side 6 of woven fabric 5 continuously over the three successive cross machine direction threads 10.4-10.6 before it runs on the second side 7 of the woven fabric and forms a bend K over the cross machine direction thread 10.7.
In addition, the repeat includes preferably machine direction threads of the second type 9.1, 9.4 which continuously form a flotation F on the second side 7 of woven fabric 5 in that they cross a second number of successive cross machine direction threads 10.4-10.6, 10.8-10.2, 10.2-10.4, 10.6-10.8 before they run on the first side 6 of the woven fabric 5 and cross a single cross machine direction thread 10.3, 10.7, 10.1 by forming a bend K. Flotation F in the current example is to be understood to mean that a machine direction thread running on one side of the woven fabric crosses more than two successive cross machine direction threads without interweaving with a cross machine thread on the side opposite to the one side. Bend K in the current example is to be understood to mean that one machine direction thread on one side of the woven fabric continuously crosses only one single cross machine thread, whereby the machine direction thread on the side opposite the one side continuously crosses the cross machine threads which are located before and after this single cross machine thread.
As can be seen in the illustration in
As illustrated in
In the repeat of woven fabric 5 the machine direction threads 9.1-9.4 are arranged preferably in the following sequence:
Within the repeat of the woven fabric
The first machine direction thread of the first type 9.2 of the repeat and the second machine direction thread of the first type 9.3 may preferably be offset to each other by one to four, especially two cross machine direction threads 10.4, 10.5.
Viewed in cross machine direction CMD polymer coating 4 consists of several coating segments 4a-4d extending across a partial width of belt 1, whereby adjacent coating segments 4a-4d overlap in an overlap region 11a-11c. Coating segments 4a-4d are connected with each other at least in sections in overlapping region 11a-11c, whereby bonding is provided preferably through chemical cross linking of the polymer material which provides coating segments 4a-4d.
As can be seen from
As can be seen, tabs 12a-12c essentially have a thickness which is consistent with the thickness of the textile fabric. This may be achieved for example by the special process control as described in
Viewed in cross machine direction at least some of the coating segments—for example in the illustration in
For example, coating segment 4a viewed in cross machine direction forms tab 12a on the one end side which, in order to form the overlap region 11a engages in the conforming recess 13b of the adjacent coating segment 4b.
In addition each coating segment 4a-4d has an upper and a lower outside surface whereby the upper and/or lower outside surfaces of adjacent coating segments smoothly adjoin.
In order to coat textile fabric 5 with polymer material in a viscous state a coating apparatus 18 is used by means of which only a partial width of textile fabric 5 can simultaneously be coated. During the coating process continuous textile fabric 5 is moved in the designated machine direction MD of belt 1 and coating apparatus 18 for the viscous polymer material is moved in the designated cross machine direction CMD of belt 1 relative to each other so that after a single movement of coating apparatus 18 from first longitudinal edge 14 to second longitudinal edge 15 of textile fabric 5 the polymer material is applied in a helix-type path 19 onto textile fabric 5, and textile fabric 5 is completely covered with polymer coating 4.
Transport direction T of textile fabric 5 through forming channel 20 described in
In addition the coating apparatus includes a holding device 43 by means of which textile fabric 5 is held in position during coating with the viscous polymer material 22 so that no waves or wrinkles occur.
During application of the helix-type path, the adjacent path segments form coating segments 4a-4d which are known from
It would also be conceivable not to apply the polymer coating in form of an uninterrupted helix type path of viscous polymer material onto the textile fabric, but instead apply several self-contained polymer paths which are located adjacent to each other in cross machine direction.
Coating apparatus 18 is shown. Coating apparatus 18 comprises a forming channel 20 through which textile fabric 5 which at this stage is uncoated at least across a partial width is fed from above and which leaves forming channel 20 in a downward direction, and coated across a partial width. Coating apparatus 18 further comprises means 21 to feed viscous polymer material 21 into forming channel 20.
As already explained the permeable textile fabric has a first side 6 facing the provided paper side and a second side 7 facing the provided machine side.
Viscous polymer material 22 may be applied from one of the two sides 6, 7 onto the permeable textile fabric 5. In the current example viscous polymer material 22 is applied from the first side 6 of the fabric which faces the paper side 2 of belt 1. It is however also conceivable to apply viscous polymer material 22 from the second side 7 of the textile fabric which faces the provided machine side 3 of belt 1.
Due to the fact that polymer material 22 is applied from one of the two sides 6, 7 in a viscous state onto permeable textile fabric 5 so that it flows from the first side 6 of textile fabric 5 through openings 8 of textile fabric 5 to the second side 7 of textile fabric 5, an integral coating 4 is created which extends from the first side 6 to the second side 7 of textile fabric 5 and which, in contrast to a polymer coating which was applied from two sides onto the textile fabric, has practically no tendency to delaminate.
Influencing factors to cause viscous polymer material 22 to flow from first side 6 to second side 7 of the textile fabric may for example be the permeability and the time required to solidify the viscous polymer material. The time in which polymer material 22 is in the viscous state, and the permeability of textile fabric 5 can be coordinated so that the viscous polymer material can flow from first side 6 of textile fabric 5 through openings 8 of textile fabric 5 to its second side 7.
Polymer material 22 may for example have a viscosity in the range of 250 cps to 1000 cps when reaching the forming channel which enables the viscous polymer material to flow from first side 6 of textile fabric 5 through openings 8 of textile fabric 5 to the second side 7.
The polymer material is advantageously solidified after approx. 10 s to 150 s, especially after approx. 10 s to approx. 50 s from the viscous state to a green state.
In its viscous state polymer material 22 comprises a hardener component and a pre-polymer component. The time for solidification of the viscous polymer material and thereby the viscosity is herewith influenced by the initial weight ratio between hardener and pre-polymer, whereby the initial weight ratio is the weight ratio between hardener and pre-polymer at the time of intermixing. The initial weight ratio includes preferably more hardener than polymer. The polymer material includes especially a duroplastic. Advantageously the polymer is a duroplastic.
The initial weight ratio includes for example between 55% and 80% hardener and between 45% and 20% pre-polymer.
Tests conducted by the applicant have shown that the textile fabric advantageously has a permeability of at least 300 cfm, preferably of at least 550 cfm and a maximum of 1200 cfm.
a and 6b illustrate coating apparatus 18 in the area of gap-shaped forming channel 20 along section A-A. Forming channel 20 progresses vertically. Air entrapments in the polymer material during coating can thereby be avoided.
Forming channel 20 is limited on one side and in its thickness by two forming belts 23 and 24.
As already explained, during coating of the permeable textile fabric with viscous polymer material 22, the textile fabric 5 is guided through gap-shaped forming channel 20. Forming channel 20 has a front limiting area 25 and a rear limiting area 26 which respectively extend in forming channel 20 parallel to textile fabric 5 and between which textile fabric 5 is guided. First forming belt 23 provides the front limiting surface 25 and moves in the same direction as textile fabric 5, and essentially at the same speed, while viscous polymer material 22 is fed into forming channel 20 and is carried along by textile fabric 5 and first forming belt 23. At the end of forming channel 20 the first forming belt 23 is separated from the polymer material. As can be seen in
Second forming belt 24 represents the other of the two limiting areas—in the current example the rear limiting area 26—of forming channel 20, whereby second forming belt 24 in the area of one of its longitudinal edges 30 on the side facing textile fabric 5 has an elevation 31 progressing parallel to longitudinal edge 30 of second forming belt 24 and providing a lateral limiting area 32 to forming channel 20.
Second forming belt 24 also moves in the same direction as textile fabric 5 and essentially at the same speed while viscous polymer material 22 is fed into forming channel 20 and is carried along by textile fabric 5 and second forming belt 24. At the end of forming channel 20 the second forming belt 24 is separated from the polymer material 22.
As can be seen in the illustration in
In the current example textile fabric 5 is run in the area of the forming channel squeezed between elevation 28 of first forming belt 23 and elevation 31 of second forming belt 24. Viewed in width direction of forming channel 20 (this is consistent with cross machine direction CMD) elevations 28, 31 of the two forming belts 23, 24 are located at the same height for this purpose.
In other words, elevation 28 of first forming belt 23 and elevation 31 of second forming belt 24, viewed in width direction (CMD) of forming channel 20, are located relative to each other so that the lateral limiting area 29 of first forming belt 23 is arranged as an extension to lateral limiting area 32 of second forming belt 24.
Since the two elevations 28, 31 have the same height, textile fabric 5 is run centered between front limiting area 25 and rear limiting area 26. If the two elevations were to have a different height, textile fabric 5 would be run off-center between front limiting area 25 and rear limiting area 26.
In addition, forming channel 20 has no lateral limiting areas on the other side 35, located opposite the one side 34.
In addition, textile fabric 5 is wider than the two forming belts 23, 24 viewed in width direction CMD of forming channel 20.
By means of the design and layout of the two forming belts 23, 24 described above, a coated area with a defined thickness is formed in the area between front limiting area 25 and rear limiting area 26 of forming channel 20 during coating of textile fabric 5 with viscous polymer material 22; and in the area between the two elevations 28 and 31 of the first 23 and the second forming belt 24 facing each other a tab 12 with a lesser thickness is formed onto the coated area.
On its side facing away from forming channel 20, first forming belt 23 and/or second forming belt 24 may be supported on an opposite surface 36, 37 in a way that the two forming belts 23, 24 are run at a defined distance from each other in the area of forming channel 20 (see
Each of forming belts 23, 24 is continuous and is guided around two guide rolls 42 whereby the respective opposite surface 36, 37 in the area of forming channel 20 is located between the two guide rolls 42.
In addition, on the side facing away from forming channel 20, first forming belt 23 and/or second forming belt 24 can have an elevation/recess 38, 39 progressing parallel to longitudinal edge 27, 30 of forming belt 23, 24 with which forming belt 23, 24 is guided along a corresponding recess/elevation 40, 41 in the opposite surface 36, 37 (see
The direction of travel of both forming belts 23, 24 preferably encompasses an angle of 0.01° to 15°, in particular between 0.2° and 2°, with the longitudinal or machine direction MD of textile fabric 5. Both forming belts 23, 24 move in their direction of travel at a speed in the range of approx. 0.25 m/min. to 1.5 m/min.
b illustrates the subsequent steps in the manufacture of transport or process belt 1.
After the permeable textile fabric has been coated on a partial width with viscous polymer material 22, thus forming the initial coated segment 4a (as shown in
For this purpose forming channel 20 and textile fabric 5 are moved relative to each other in their position in cross machine direction, so that forming channel 20 is located, in segments, in a partial area of the textile fabric which has not yet been provided with a coating segment. Since in the current example the polymer coating is applied in a helix-type path, shifting of the offset of the forming channel relative to the textile fabric occurs continuously. As can be seen from the illustration in
As already explained, the initially formed coated segment 4a has a tab 12a in the overlap area 11a, protruding in cross machine direction CMD and the additional subsequently formed coated segment 4b has a corresponding recess 13b with which tab 12a engages.
Subsequently in the method a bond between the two coated segments 4a and 4b is caused in overlap area 11a.
As already explained in the description of
Immediately after application of polymer material 22, a conversion from the viscous state to a solid state of polymer material 22 is caused. Here it is conceivable that the bond of the two coated segments 4a and 4b in overlap area 11a and the conversion of polymer material 22 from the viscous state to a solid state can occur at least partially simultaneously.
The conversion of polymer material 22 from the viscous state to the solid state includes preferably cross-linking of polymer material 22. In other words, a chemical cross-linking takes place. For this purpose the polymer material may in particular have a hardener component and a pre-polymer component which are intermixed immediately prior to the coating process, whereby cross-linking begins immediately after mixing of the two components.
In order to achieve a good and solid bond of coating segments 4a, 4b in overlap area 11a it is especially advantageous if coating of textile fabric 5 with the polymer material when creating the subsequent coating segment 4b occurs, as long as the polymer material of the initially formed coated segment 4a is not yet completely cross-linked. It is preferable if the subsequent coated segment is produced while the polymer material of the initially formed coated segment 4a remains in a green state.
Tests conducted by the applicant have shown that the ratio between hardener and pre-polymer is adjusted so that the duroplastic polymer material 22 solidifies after approx. 10 s to 150 s, especially after approx. 10 s to approx. 50 s, from the viscous state to a green state.
Tests conducted by the applicant have further shown that a permanent bond of the coated segments which partially overlap each other can be achieved especially when an additional coated segment 4b is formed within 24 hours after a prior coated segment 4a was formed.
In order to make the bond between adjacent coated segments, for example 4a and 4b, or 4b and 4c, very durable it can be advantageous to subject the polymer material of the initially formed coated segment in the area of tab 12b, 12c, 12d to a thermal treatment, especially a heat treatment immediately prior to creating the subsequent coated segment.
As can be seen from the illustrations in
Tabs 12a-12c essentially have a thickness which is consistent with the thickness of textile fabric 5. This can be achieved for example by the specific process control, in other words in that textile fabric 5 is run between the two elevations 28, 31 of the two forming belts 23, 24. The length of tabs 12a-12c can be influenced, for example, through the viscosity of the polymer material during the manufacturing process.
Application of the polymer material is preferably conducted so that the tab of the coated segment which is produced first extends in cross machine direction between 10 mm and 50 mm, especially between 20 mm and 35 mm, into the recess of the subsequently formed coated segment.
The application of the polymer material is in addition conducted preferably so that the respective coated segments 4a-4d extend in cross machine direction CMD between 100 mm and 500 mm, especially between 150 mm and 300 mm.
As can be seen from the illustration in
In addition all coated segments 4a-4d have preferably the same thickness, whereby the upper and/or the lower outside surfaces of adjacent coating segments 4a-4d smoothly adjoin.
It can also be seen in the illustration in
In addition, means are provided by which textile fabric 5 is held in position during coating with the viscous polymer material so that it does not produce any waves or wrinkles. In the current example the means include a first and a second holding device 43, 47 arranged at the height of forming channel 20 and having opposite surfaces 48-51 between which textile fabric 5 is squeezed.
The two holding devices 43, 47 are located outside forming channel 20.
Holding textile fabric 5 in position hereby includes stretching of textile fabric 5 in forming channel 20, in cross direction to the transport direction.
As already explained, front limiting area 25 of forming channel 20 is provided by first forming belt 23; and rear limiting area 26 of forming channel 20 is provided by second forming belt 24 between which textile fabric 5 is guided. Here, the two forming belts 23, 24 run in the same direction and essentially at the same speed as the textile fabric 5.
First holding device 43—viewed in cross direction to the transport direction—is located at a distance from the two forming belts 23, 24, whereby the distance between first holding device 43 and the two forming belts 23, 24 is between 10 cm and 100 cm, preferably between 30 cm and 55 cm.
In the first holding device 43 the two opposite surfaces 48, 49 are provided by a pair of rollers 44, 45 which are rotatable in transport direction of the textile fabric.
Second holding device 47 is provided by the two elevations 28, 31 of forming belts 23, 24 which face toward textile fabric 5 and between which textile fabric 5 is squeezed and guided. In the second holding device 47 an offset of the two opposite surfaces 50, 51 at cross direction to the transport direction is preferably avoided through appropriate means, thereby further avoiding creation of waves or folds in the textile fabric.
Textile fabric 5 is held by the two holding devices 43, 47 in an area which has not yet been coated, whereby textile fabric 5 is coated in the second holding device 47 during the holding process and while a tab is formed.
Textile fabric 5 is held in position during the coating process by the two holding devices 43, 47 so that a centered position of textile fabric 5 in the polymer coating 4 is ensured. In addition, occurrence of wrinkles or waves in textile fabric 5 is avoided during the coating process. Obviously, according to the invention only one of the two holding devices 43, 47 may be provided. However, provision of both holding devices 43, 47 provides an especially effective centering of textile fabric 5, as well as effective avoidance of wrinkles and waves.
In the current example the two opposite surfaces are provided by a pair of rolls 44, 45 which are rotatable in transport direction of textile fabric 5, whereby in the current example each of the two opposite surfaces is rigidly connected with one of the two forming belts 23, 24.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Number | Date | Country | Kind |
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10 2007 055 864.5 | Dec 2007 | DE | national |
This is a continuation of PCT application No. PCT/EP2008/063365, entitled “TRANSPORT BELT AND METHOD FOR THE PRODUCTION THEREOF”, filed Oct. 7, 2008, which is incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/EP2008/063365 | Oct 2008 | US |
Child | 12818806 | US |