Patent Application
20140150225
1. Field of the Invention
The present invention relates to a loom, in particular a flat-loom, for producing paper machine clothing which can be utilized, for example, in a paper machine as a forming fabric.
2. Description of the Related Art
It is known that clothing for paper machines produced as a woven structure having warp threads and weft threads are subjected to thermosetting after the weaving process. The objective of this thermosetting process is to stretch, or respectively straighten, curvatures in warp threads extending generally in a machine direction in the finished paper machine clothing which occur during the weaving process at the points where the warp threads tie off over or respectively under the weft threads, in order to avoid dimensional changes in the paper machine clothing during use in the paper machine. Thermosetting can also lead to shrinkage in threads extending in the machine direction and cross machine direction which equally contributes to dimensional stabilization.
In order to implement this thermosetting it is known to guide the woven structure after the weaving process through two rolls in a thermosetting device intended for this process. At least one of these rolls is heated in order to thus achieve thermosetting.
Another approach for thermosetting is the provision of a bar-type heating unit on a loom, between the reed and the breast beam, in other words in a weaving direction prior to a take-up roller system which transports the warp threads and thereby the entire produced woven structure through the weaving zone and thereby unwinds the warp threads from the warp beams. The tension thereby provided in the woven structure, or respectively in the warp threads, is to be selected so that the weaving process can be implemented correctly and that a correct shedding can be ensured. This means that the tension developing in the woven structure can generally not be adjusted to conditions which are ideal for thermosetting.
What is needed in the art is a loom to produce a paper machine clothing in which thermosetting is realizable in an improved manner over the prior art.
The present invention provides a loom for the production of a paper machine clothing, including a weaving zone to produce a woven structure having warp threads and weft threads and, viewed in a weaving direction, subsequent to the weaving zone including a tension zone with a first take-up roller system and a subsequent, second take-up roller system. Each take-up roller system is configured to move the woven structure forward, for example with a respectively predetermined or pre-determinable conveying velocity in order to produce a tension in the weaving direction. A heating arrangement for thermosetting of the woven structure is positioned between the first take-up roller system and the second take-up roller system.
Since in the loom according to the present invention a tension zone is provided following the weaving zone in which the tension can be adjusted between take-up roller systems independently from the tension provided in the weaving zone—namely due to the fact that these take-up roller systems move the woven structure forward thereby producing a tension in the woven structure—optimum tension conditions for thermosetting can be provided in this region in which then also the heating arrangement is effective. The conveying speed of a respective take-up roller system can thereby be firmly predetermined, for example preselected for a respective weaving process or can, for example, be determined by the progress of the weaving process, for example by the tension occurring in the woven structure and may also be changed during the course of a weaving process if necessary.
For purposes of the present invention, all machines employed in the production of flat material, for example paper, cardboard or similar material are considered to be a paper machine.
It is hereby pointed out that if reference is made in the following to the woven structure or respectively certain sides of the woven structure, or conveying speeds for same, the woven structure merely defines a reference dimension or respectively a reference system. It is, however, categorically not necessarily to be considered as a component of the inventive loom.
In order to be able to provide thermosetting over the entire width of the woven structure which is to be produced in the loom according to the present invention, the heating arrangement may include at least one heating unit extending transversely to the weaving direction, for example over the entire width of the woven structure.
On at least one heating unit the heat output is, for example, variable transversely to the weaving direction. This means that on this at least one heating unit different temperatures can be provided, substantially in a width direction of the woven structure which is to be produced and which is to be subjected to a thermosetting process, so that the thermosetting process in the width direction can also proceed with varying quality.
On at least one heating unit, the heat output in at least one first longitudinal region allocated to an edge region of the woven structure may be variable relative to a heat output in a second longitudinal region allocated to a center region of the woven structure.
In this arrangement it becomes possible to provide a higher temperature in one or in both edge regions of the woven structure which is to be produced than in the center region. This is advantageous since, due to the tension present in the woven structure in the warp direction, that is in the weaving direction, the warp threads proceeding in the edge region are forcibly displaced to the inside, in other words in the direction to the center region and have to therefore cover a greater distance. This can be taken into account through the provision of a higher temperature in one or in both edge regions. It may, for example, be provided that the at least first longitudinal region extends over a length in a range between approximately 1/10 and ⅓, for example approximately ¼, of the width of the woven structure.
To ensure that the woven structure which is to undergo a thermosetting process is subjected to an as uniform as possible thermosetting process in its thickness direction, in other words from its one side to its other side, at least two heating units may be arranged on different sides relative to the woven structure.
When implementing weaving processes it may be necessary to stop the loom—for example during a thread break—and to subsequently continue the weaving process. Since in the loom constructed according to the present invention the thermosetting process occurs substantially synchronously to the weaving process, at least one heating unit may be movable in a direction toward the woven structure and away from the woven structure. Possibly occurring excessive thermal stresses of a longitudinal section of the woven structure can thereby be avoided, for example during a stoppage.
It may, for example, be provided that at least one heating unit extends substantially in a straight line across the woven structure, whereby an orientation substantially orthogonal to the weave direction, possibly also tilted to it, can hereby be selected.
In an alternative embodiment of the loom according to the present invention, it may be provided that at least one heating unit extends curved, at least in sections, over the woven structure. In particular, it may hereby be provided that at least one longitudinal region of the at least one heating unit allocated to an edge region of the woven structure is arranged in the weave direction at least in sections upstream relative to a second longitudinal region which is allocated to a center region of the woven structure. This arrangement makes it possible to stagger the thermal interaction of a thus arranged heating unit with the woven structure in the width direction in such a way in regard to a point in time of the passing movement of the woven structure so that—for example with regard to the direction of extension of a weft thread progressing transversely to the weave direction—initially a thermal interaction is produced in at least one of the edge regions, and a thermal interaction is produced only later also in the center region during an additional forward movement of the woven structure in the weave direction. This may contribute to limiting a slanted progression of the warp threads located in an edge region in a direction toward the center region.
In a further embodiment of the loom according to the present invention, at least a third take-up roller system may be arranged in the weave direction between the first take-up roller system and the second take-up roller system. With this it becomes possible to provide a graduated variation of the tension, so that a respective optimum tension can be provided in the woven structure in each partial tension zone which is formed between two immediately successive take-up roller systems.
For this it may, for example, be provided that the third take-up roller system can be operated at a higher conveying speed than the first take-up roller system, and that the second take-up roller system can be operated at a higher conveying speed than the third take-up roller system.
For thermal treatment of the woven structure in the partial tension zones which are formed between the immediately successive take-up roller systems it may be provided that at least one heating unit is arranged between the first take-up roller system and the third take-up roller system and that at least one heating unit is arranged between the third take-up roller system and the second take-up roller system. It may hereby be provided, for example, that at least two heating units are arranged on different sides relative to the woven structure, between the first take-up roller system and the third take-up roller system. Moreover, at least two heating units can be arranged on the same side relative to the woven structure between the third take-up roller system and the second take-up roller system.
In the loom according to the present invention at least one take-up roller system can include at least two take-up rollers between which a conveying nip is formed.
To be able to guarantee defined conveying speeds for the woven structure with the inventive configuration of a loom, at least one take-up roller system can include three take-up rollers, whereby a first conveying nip is formed between a first of these take-up rollers and a second of these take-up rollers, and a second conveying nip is formed between the second of these take-up rollers and a third of these take-up rollers. The woven structure is then always held between two take-up rollers under at least low pressure in a respective conveying nip, whereby due to the provision of two such conveying nips in one take-up roller system a defined forward transportation of the woven structure can be ensured on the one hand, and the occurrence of slack due to the tension in the woven structure can be eliminated on the other hand.
The working width of the loom can be greater than approximately 5 meters (m), for example greater than approximately 6 m.
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:
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
The form of weaving zone 12 can be realized in a conventional manner and because of this will not be discussed in further detail below.
Following weaving zone 12, viewed in the weaving direction which is substantially consistent with the forward movement of warp threads 12, tension zone 34 is located in inventively arranged loom 10. This includes first take-up roller system 36, which essentially is located immediately following breast beam 32. Second take-up roller system 38 is located at the end of tension zone 34 and third take-up roller system 40 is located between first take-up roller system 36 and second take-up roller system 38.
Woven structure 42, which is being produced in weaving zone 12, is moved forward in the weaving direction by take-up roller systems 36, 38, 40. For this purpose, each take-up roller system 36, 38, 40 includes three take-up rollers 44, 46, 48. First conveying nip 50 is formed between first take-up roller 44 and second take-up roller 46. A conveying nip in the sense of the current invention is a linear region progressing substantially transversely, or respectively orthogonally, to the weaving direction wherein the two involved take-up rollers are held against each other under pressure, thereby clamping woven structure 42 between them. In this manner woven structure 42 can be moved forward by driving the transport rollers.
Viewed in the weaving direction, second conveying nip 52, which is formed between second take-up roller 46 and third take-up roller 48, follows first conveying nip 50 which is formed between first take-up roller 44 and second take-up roller 46. Due to the fact that with take-up roller systems 36, 38, 40 always two conveying nips 50, 52 are formed by the interaction of three take-up rollers 44, 46, 48, a defined forward movement of woven structure 42 in the weaving direction is ensured on the one hand. On the other hand, the development of slack between woven structure 42 and individual take-up rollers 44, 46, 48 is practically impossible. It is herein moreover possible to provide individual or all take-up rollers 44, 46, 48 with a friction enhancing surface, for example with a rubber-like or similar material.
Take-up roller system 36 which is located at the beginning of tensioning zone 34 viewed in the conveying or respectively weaving direction serves among other things to draw warp threads 22 from warp beams 18, 20 and to consequently also move woven structure 42 produced therefrom through weaving zone 12. Conveying speed v0 of woven structure 42, which is predefined by first take-up roller system 36, determines substantially also the weaving speed, or respectively the manufacturing speed of the entire loom 10. The tension which is to be provided in warp threads 22 in weaving zone 12 can, for example, be adjusted to a defined value by braking devices acting upon warp beams 18, 20 and/or also by repositioning of tension rollers 24, 26. The tension of first take-up roller system 36 in woven structure 42, viewed in the weaving direction, can then be adjusted completely independent from the tension in weaving zone 12, due to the decoupling effect of first take-up roller system 36. For this purpose, take-up rollers 44, 46, 48 of third take-up roller system 40 and second take-up roller system 38 can be driven respectively with a conveying speed for woven structure 42 which is different from the conveying speed of first take-up roller system 36. When first take-up roller system 36 transports woven structure 42 with a conveying speed v0, third take-up roller system 40 can then, for example, be operated such that it conveys woven structure 42 forward with a speed of 103% of v0. In this manner a tension is produced in the region of woven structure 42 extending between first take-up roller system 36 and third take-up roller system 40 which also contributes to the extension of woven structure 42 in the weaving direction or respectively warp direction. Second take-up roller system 38 can be operated, for example with a speed of 110% of vo, so that an additional tension increase is achieved between third take-up roller system 40 and second take-up roller system 38.
By the three successive take-up roller systems 36, 40, 38, an independent adjustability of the tensions acting respectively in the warp direction upon woven structure 42 in partial tension zones 54, 56 which are formed between them is therefore achieved in tension zone 34. Woven structure 42 can be guided substantially linearly in these individual partial tension zones 54, 56 as can be the case, for example, in second partial tension zone 56. Or, it can be redirected over one or a plurality of guide rollers 58, as is the case in first partial tension zone 54.
Allocated to tension zone 34 is a heating arrangement which is generally identified with 60. In the illustrated example this includes four bar-like heating units 62, 64, 66, 68 extending substantially transversely, for example orthogonally, relative to the weave direction and thereby in the width direction across woven structure 42. The entire width of woven structure 42 which is being transported through tension zone 34 can be covered with each of heating units 62, 64, 66, 68, thereby achieving a thermosetting process in the entire woven structure 42.
First heating unit 62 which—viewed in the weave direction—immediately follows first take-up roller system 36, is located in this case on a side of woven structure 42 which is considered to be the bottom side of same and provides a pre-heating zone. Following in the weave direction, and in the current example located between guide roller 58 and third take-up roller system 40 in first partial tension zone 54, is second heating unit 64. Here it is positioned on the other side, for example on the top side of woven structure 42 and consequently heats woven structure 42 from the other side in an intermediate heating zone. It is hereby pointed out that several, for example two heating units can be positioned adjacent to each other and/or opposite each other in the pre-heating zone as well as in the intermediate heating zone.
In second partial tension zone 56, in other words between take-up roller systems 40, 38, two heating units 66, 68 are located on the same side relative to woven structure 42, in this case on the bottom side of same and provide the final heating zone. Here too, additional, for example two additional, heating units may be provided which can be located on the same side relative to woven structure 42. Likewise they can be positioned on the opposite side, in this case the top side relative to woven structure 42.
Heating units 62, 64, 66, 68 can be in the embodiment of infrared heaters, heating bars, air boxes or hot rolls. Depending on the heating mechanism which possibly requires a direct physical contact or not, they can make contact, or not, with woven structure 42 during the thermosetting process and can be arranged at a distance to same through retention of an air gap. They can be heated to a temperature of 170° C. whereby for threads consisting of a polymer material a temperature range of 120° C. to 170° C. is to be considered a normal operational range. At a conveying speed or respectively weaving speed v0 of approximately 0.1 meter per minute (m/min) and a width of bar-type heating units 62, 64, 66, 68 of approximately 5 centimeters (cm) measured in the weaving direction, woven structure 42 dwells in the region of each heating unit over a time period of approximately 0.5 minute. This is sufficient to achieve a thermal interaction sufficient for thermosetting. If hereby a mechanical tension of approximately 4 kiloNewton per meter (kN/m) is present in woven structure 42, then the curvature regions present in the warp threads will be sufficiently stretched. Since no tension is applied on the weft threads extending transversely to the weave direction these will tighten due to the tension acting upon the warp threads on the one hand and the heating on the other hand, so that the woven structure is stretched in the weave direction, but a decrease in width in the range of between approximately 1 to 10% can be achieved.
Due to the gradual increase or respectively exertion of a tension upon the woven structure in individual partial tension zones 54, 56, an excessively strong tension on warp threads 22 is moreover avoided, so that these will move slightly but not excessively toward the inside in the direction to the center region of woven structure 42 in particular in the edge regions of the woven structure which are located transversely to the weave direction. This means that warp threads 22 progressing in the edge regions of woven structure 42 have to cover a slightly longer path than warp threads 22 moving substantially linearly in the weave direction and which are located in the center region of woven structure 42. In order to achieve uniform thermosetting or respectively exposure over the entire width of woven structure 42 under consideration of this aspect it may moreover be provided that individual, for example all heating units 62, 64, 66, 68, in the width direction of the woven structure are variable in their heat output. It is therefore advantageous if in respective first longitudinal regions L1 which correspond to edge regions R (see
Referring now to
Heating unit 42 extends transversely, in this case for example orthogonally, to weave direction W over woven structure 42 and covers its entire width. In first longitudinal regions L1 allocated to edge regions R the heat output relative to second longitudinal region L2 allocated to center region M can be variable as previously described. In other words, a higher temperature is achievable.
An example of one arrangement is illustrated showing heating unit 64 wherein the heating unit which extends substantially across woven structure 42 does not progress linearly, but curved, in this case arched. The first two longitudinal regions L1 are located upstream relative to the second longitudinal region L2 in regard to weave direction W. One longitudinal region of woven structure 42 indicated by dashed line B in
It is herewith pointed out that the arched curved arrangement of heating unit 64 has been selected merely as an example. One could also select a V-shaped, a W-shaped or otherwise curved, however not necessarily uniform and without corner regions, configuration. It is further pointed out that as well as the straight configuration, also the curved configuration can be provided with each of illustrated heating units 62, 64, 66, 68 or can be realized as desired in combination with the respective other configuration with one or several of the other heating units.
To be able to avoid excessive thermal load of short longitudinal sections of already woven structure 42, in particular in the event of a stoppage of loom 10 during a weaving process, individual heating units 62, 64, 66, 68 of heating arrangement 60 can be moved away from woven structure 42 and can be brought back toward and into contact with woven structure 42 for resumption of the thermosetting process. For this purpose operating mechanisms, for example piston/cylinder, rack and pinion drives or swiveling lever units can be allocated to heating units 62, 64, 66, 68.
It is pointed out that with the previously described loom or respectively its mode of operation a wide range of variations can be undertaken without deviating from the principles of the current invention. For example, at least one of the take-up roller systems could be equipped with only two take-up rollers and consequently with only one single conveying nip, or with more than three take-up rollers. Moreover it may be provided in at least some operating phases that a take-up roller system located downstream relative to the weave direction operates at a lower conveying speed than the take-up roller system located immediately upstream from same. This may for example be necessary in order to achieve a tension adjustment. It is also possible to vary the conveying speeds of the various take-up roller systems during the course of a weaving process, for example in order to keep the tension in tension zone 34, or respectively in partial tension zones 54, 56, constant or to deliberately vary it. For this purpose the tension of the woven structure may for example be acquired and used as a feedback value. This tension acquisition can occur separately for the partial tension zones and can be determined by a sensor arrangement, for example a sensor roll arrangement.
With the inventively arranged loom the thermosetting process can be carried out immediately following the weaving process. This results in an especially efficient production of paper machine clothing since after the weaving process this does not need to pass through an arrangement intended especially for thermosetting. Since due to the take-up roller systems a tension-related separation between the tension zone on the one hand and the weaving zone on the other hand is achieved, each of the two operational processes—the weaving process and the thermosetting process—can be realized under respectively optimum tension conditions. The first take-up roller system following the breast beam serves hereby to adjust the tension conditions in the tension zone, as well as the forward movement of the warp threads and consequently the woven structure in the weaving zone and thereby serves also to adjust the tension conditions in the weaving zone.
The operating width of previously described loom 10 is at least 5 m or greater, for example 6 m or greater. In the past only narrow looms 10 were equipped with pertinent heating units 62, 64, 66, 68.
The loom according to the present invention with such operating widths including weaving structures which extend over the full operating width of loom 10 are to be exposed in their entire width to the influence of heating units 62, 64, 66, 68 for the purpose of thermosetting. Until now it has only been known to expose narrow strips of the woven structure to the influence of heat and to subsequently spirally wind them and to connect them at the butt joints in order to bring the woven structure to the desired width for the production of a paper machine felt. This limitation can be effectively avoided with the described measures.
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 |
|---|---|---|---|
| 10 2011 080 508.7 | Aug 2011 | DE | national |
This is a continuation of PCT Application No. PCT/EP2012/065246, entitled “LOOM FOR PRODUCING A PAPER MACHINE CLOTHING”, filed Aug. 3, 2012, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2012/065246 | Aug 2012 | US |
| Child | 14173172 | US |
