Abstract
The invention relates to an industrial fabric and its use. The industrial fabric (1) comprises several machine direction (MD) yarns (2, 2a, 2b) and several cross machine direction (CMD) yarns (3). The MD-yarns are twisted relative their longitudinal axis so that the twisted yams have sloped surfaces (4) at least on a web side surface (P) of the textile. The textile is usable in paper machine, pulp machine or filtering machine.
Claims
1. An industrial textile for supporting a fibre web in a processing machine, the textile (1) comprising: a web side surface (P), which is facing towards the fibre web to be processed during use of the industrial textile; a roll side surface (R), which is facing towards the processing machine during the use; several machine direction (MD) yarns (2) and at least some of them have flat cross sections; and several cross machine direction (CMD) yams (3); characterized in that the textile (1) is a woven fabric and comprises several machine direction yams (2, 2a, 2b), which are twisted relative to their longitudinal axis; and wherein the twisted flat machine direction yarns (2, 2a, 2b) expose as slanted surfaces (4) at least on the web side surface (P).
2. The textile as claimed in claim 1, characterized in that all of the machine direction yarns (2) are twisted.
3. The textile as claimed in claim 1 or 2, characterized in that each of the slanted surfaces (4) formed of the twisted flat machine direction yarns (2) appear as portions having shape of an outer surface of a segment of a truncated circular cone (6) at least on the web side surface (P) of the textile (1) when seen from the web side surface (P).
4. The textile as claimed in claim 1, characterized in that the textile (1) comprises several adjacent first machine direction yarns (2a) and second machine direction yarns (2b) which are twisted towards opposite cross machine directions (CMD), whereby first surfaces (4) of the flat first machine direction yarns (2a) on the web side surface (P) are slanted towards a first longitudinal edge of the textile (1) and second surfaces (4) of the flat second machine direction yarns (2b) are slanted towards an opposite second longitudinal edge of the textile (1).
5. The textile as claimed in claim 1, characterized in that at least the web side surface (P) of the textile (1) comprises grooves (5) in the cross machine direction (CMD), the grooves (5) being between adjacent slanted surfaces (4) formed of the twisted flat machine direction yarns (2a, 2b) exposing at the cross machine direction yarns (3).
6. The textile as claimed in claim 1 any of the preceding claims 1 to 5, characterized in that the textile (1) is a woven fabric and has a single-layer structure so that the textile (1) has cross machine direction yarns (3) only in one single layer; and the machine direction yarns (2, 2a, 2b) have 2-shed weaving structure.
7. The textile as claimed in claim 1, characterized in that the textile (1) is a dryer fabric for a dryer section of a paper machine.
8. The textile as claimed in claim 1, characterized in that the textile (1) is a pulp supporting fabric for a pulp machine.
9. A use of an industrial textile, wherein the textile (1), which is in accordance with claim 1, is used in a paper machine, pulp machine or filtering machine; and wherein high pressure fluid sprays are directed to the web side surface (P) of the textile (1) for washing the textile structure, whereby fluid sprays hitting the twisted machine direction yarns (2, 2a, 2b) are directed further from the sloping surfaces (4) into the structure of the textile (1).
Description
BRIEF DESCRIPTION OF THE FIGURES
[0040] Some embodiments are described in more detail in the accompanying drawings, in which
[0041] FIG. 1 is a schematic perspective view of an industrial textile provided with a seam and thereby having a shape of an endless loop,
[0042] FIG. 2 shows schematically a diagram presenting some features of an industrial textile,
[0043] FIG. 3 is a schematic view of a web side surface of an industrial textile,
[0044] FIG. 4 is a schematic cross sectional view of an industrial textile seen in a machine direction,
[0045] FIG. 5 is a schematic top view showing two adjacent machine direction yarns of an industrial textile,
[0046] FIG. 6 is a schematic side view of a machine direction yarn of an industrial textile, and
[0047] FIGS. 7 and 8 are schematic top views of surface topographies of web side surfaces of two industrial textiles.
[0048] For the sake of clarity, the figures show some embodiments of the disclosed solution in a simplified manner. In the figures, like reference numerals identify like elements.
DETAILED DESCRIPTION OF SOME EMBODIMENTS
[0049] FIG. 1 shows some basic features of a feasible industrial textile 1. The industrial textile 1 may be a woven structure comprising machine direction yarns 2 and cross machine direction yarns 3, which are crossing each other. The industrial textile may be a fabric, which is flat woven and its seam ends SE1 and SE2 may be connected to each other for forming a seam S when installed on a web processing machine. The industrial textile 1 is configured to run in the machine direction MD. The industrial textile 1 comprises a web side surface P against which a web to be processed is arranged on the processing machine. An opposite side is a roll side surface which is against rolls and other machine elements of the processing machine.
[0050] FIG. 2 is a diagram showing that an industrial textile may be formed by weaving, or alternatively, it may be formed by utilizing non-woven technology, such as winding. FIG. 2 also indicates that industrial textiles are used in different web processing machines, such as paper machines, filtering machines and pulp machines.
[0051] FIG. 3 shows a web side surface P of an industrial textile 1. The textile 1 comprises several flat machine direction yarns 2 and several cross machine direction yarns 3. Cross section of the machine direction yarns 2 may be substantially rectangular and cross section of the cross machine direction yarns 3 may be round. The machine direction yarns 2 are twisted relative to their longitudinal axis whereby they expose as slanted surfaces 4 on the web side surface P. As can be noted adjacent first MD-yarns 2a and second MD-yarns 2b are twisted towards opposite cross machine directions. Thereby, the web side surface comprises slanted first surfaces of the flat first machine direction yarns 2a and slanted second surfaces of the flat second machine direction yarns 2b. Between the slanted surfaces 4 directed to opposite directions are cross machine direction grooves 5, which are indicated in FIG. 3 by means of broken lines.
[0052] All the CMD-yarns may be similar yarns and may have the same cross sectional areas. Alternatively, it is possible to use two types of CMD-yarns having different cross sectional areas and/or cross sectional shapes in order to provide the surfaces of the textile 1 even more open structure. In FIG. 3 it is shown by means of broken lines 3a larger CMD-yarns, which alternate with smaller CMD-yarns 3. Alternatively, CMD-yarns having round cross section and CMD-yarns having flat cross sections may alternate in the textile structure for increasing free voids on the surface.
[0053] Further, the above disclosed issues may be applied also for the MD-yarns, whereby cross sectional areas and/or cross sectional shapes of the flat MD-yarns may vary in order to increase open surface of the textile. Thus, dimensions of the adjacent flat and twisted MD-yarns may be different in special cases, as well as cross sectional shapes may vary.
[0054] FIG. 3 further discloses that the industrial textile may have a weaving pattern, wherein the MD-yarns 2 pass above one CMD-yarn yarn 3, pass below one adjacent CMD-yarn and repeat this two-shed pattern further. This way, the disclosed industrial textile 1 may have a symmetrical one layer structure wherein the twisted MD-yarns 2 expose as slanted surfaces 4 on both surfaces of the textile. Thereby, the roll side surface R may also comprise transversal grooves 5. When both surfaces are provided with the grooves, flow of washing liquid through the textile structure may be increased and washing result improved.
[0055] FIG. 4 shows that an industrial fabric comprises slanted surfaces 4 on a web side surface P as well as on a roll side surface R. Machine direction yarns 2 are twisted relative to their longitudinal axis as can be clearly seen from FIG. 4. The structure comprises twisted first MD-yarns 2a and twisted second MD-yarns 2b twisting direction of which yarns are opposite to each other. Thus, the differently slanted surfaces 4 of the MD-yarns 2a, 2b alternate on the surfaces P, R of the textile 1. When a washing liquid flow or flushing flow FF with high pressure is directed against the web side surface of the textile 1 the flow is directed from the slanted surfaces 4 of the MD-yarns 2a, 2b towards an inner structure of the textile, and is not splashed randomly away from the surface P. After the liquid washing step, the textile may be dried by directing a dryer air flow against the web side surface P. The slanted surfaces 4 direct also the air flow through the textile structure. Thanks to the slanted surfaces 4, washing energy contained in the liquid and air flows is more effectively utilized for removing accumulated dirt and fibers from the textile structure. Thus, properties of the industrial textile may be recovered and operational life of the textile may be longer than in known solutions. Further, since the washing energy is directed effectively through the textile, lower pressures may be used in washing liquid sprays. Washing units with lower pressures (300 bar) are more reliable and less inexpensive compared to washing units generating extremely high pressures (500-600 bar). An additional advantage is that washing water jets having lower pressures do not damage structures of the yarns 2, 3 of the textile 1.
[0056] FIG. 5 shows two adjacent machine direction yarns 2a, 2b of an industrial textile 1. The MD-yarns 2a, 2b are twisted into opposite directions whereby their slanted surfaces 4 on the web side surface P are also directed to different directions. Further, the slanted surfaces 4 formed of the twisted flat machine direction yarns appear as portions having shape of an outer surface of a segment of a truncated circular cone 6, which shape is indicated by broken lines.
[0057] FIG. 6 is a side view of a machine direction yarn 2. The MD-yarn 2 has been permanently deformed by weaving forces or other manufacturing forces of the textile, and possibly, also by means of transverse forces caused by strong shrinkage of CMD-yarns.
[0058] FIGS. 7 and 8 are schematic top views of surface topographies of web side surfaces P of two industrial textiles 1. Potential surface contact points and surface areas are shown in the FIGS. 7 and 8 by using lighter colour whereas darker colour indicates non contacting areas i.e. void volume 8 on the surface. It can be noted from FIG. 7, that the contact areas represent about 50% of the total surface of the industrial textile 1. In FIG. 8 the industrial fabric 1 has about 10% surface contact area. In both embodiments number of contact points is very high and still the surface contact area is low.
[0059] The drawings and the specification associated thereto is merely intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims.
