MXPA99007934A - Multi axial pin seamed papermakers press felt - Google Patents

Abstract

A multilayer papermaker's press felt fabric (1) comprising in combination a woven first fabric layer (3), typically a double layer fabric, has a cross machine direction pin seam (2). A second fabric layer (4) is located on the paper side face of the first fabric layer, and a layer of needled batt (5) is applied to the paper side face of the second layer (4) binding the layers together. A flap (15) comprising a short length of the second fabric layer (4) with attached batt (5) overlays the pin seam area (2) in the first layer. The second layer comprises a plurality of relatively narrow strips, which are located with a lateral edge at a first cant angle of from more than 1°to less than 20°to the machine direction. A third layer, similar to the second layer, can be included on the machine side of the first layer;the strip widths, the cant angles, and the direction of the cant angle relative to the machine direction for each of the two strips need not be the same. The fabric is assembled using a spiral winding technique.

Description

FELT SEWED BY LOOP SEWING AND MULTIPLE LAYERS FOR PAPER MANUFACTURING PRESS BACKGROUND OF THE INVENTION This invention relates to press felts, which are used in the press section of a papermaking machine. In this part of the papermaking machine, the paper web, which can contain up to about 85% water, passes through pairs of opposite rollers so that a large proportion of this water is literally squeezed out of the wet paper web . In this process, the wet paper web is supported by at least one, or transported between two opposite fabrics known as press felts. These press felts are generally constructed with a fabric base structure, which has layers of batting sewn in at least one, and generally both, of their surfaces. Various fabric configurations are used for the fabric base structure, including single layer and double layer woven fabrics, and the fabrics can be woven either flat as a continuous form, or endless as a closed circuit. Endless felts require that the press section be open to allow installation. The sewn felts have open ends for installation and the ends are subsequently joined by sewing, for example by a loop seam in the press section. In any case, in order to install the finished fabric in a section of Press, it is an advantage to provide a seam that can be closed during installation in the press section. Sewing is the most difficult part of making press fabric. Because although it is relatively easy to create a press felt that provides the required properties of adequate strength, proper drainage, and lack of fabric marking, which may or may not be used depends on whether it is possible to provide a seam on the fabric having a adequate life in service, provide the required strength, the required drainage, and most importantly, do not cause paper marking. The most commonly used seam in press felts is a loop seam, where monofilament yarns from each of the two ends of the fabric to be joined are sewn at the ends of the fabric to provide a series of small loops. The two ends of the fabric are joined by interdigitating the two groups of loops, and by inserting a central pin across the width of the fabric. This form of stitching is most often used in press felts based on double layer woven fabrics. Examples of said seams are shown in EP 0 294 951, E.U.A. 4,842,925 and E.U.A. 4,601, 785. These conventional press felts offer easy installation benefits, and easy seam assembly on the machine. However, they have the disadvantage of being limited to applications that can tolerate at least some marking of the paper by the seam, and where the drainage requirements are modest. Another disadvantage is that the wadding applied Wears faster in the sewing area. An area of wadding over the sewing area increases the danger of marking, and further accelerates the rate of wear in the sewing area. This results in premature failure of the press felt due to paper marking problems, or in a mechanical seam failure, or both. Several proposals have been made to solve these difficulties. One proposal that was made is to use two layers of woven fabric, instead of one, to provide what is known as a laminated base structure. Fabrics of this type are presented in the U.S. patent. 3,086,276, wherein the fabric layers are placed in a skewed relationship, and in the U.S. patent. do not. 3,657,068 where a relatively thin cloth and a coarse cloth is disposed on each side of a batting layer. An alternative fabric is presented in U.S. Patent No. 5,110,672. In these references, the layers are laminated together by the wadding, which in the sewing application process is forced to join with all the layers. A common problem in all these structures is that the ends of the cut fabric adjacent to the seam tend to unravel, leaving the wad more or less unsupported in the most important area of the fabric. This results in paper marking, and premature seam failure. Alternatively, it has been proposed to use a laminated structure, examples of which are described in the U.S.A. do not. 4,186780 and in the patent of E.U.A. No. 4,418,726, and sewing with loop stitching each of the fabrics in the laminate. Apart from that this fact does not eliminate any of the difficulties on a single loop seam, it complicates the installation, since now there are two seams to be closed, and not one. This installation step is difficult, takes a long time and eliminates the original purpose of sewing, which is to provide ease of installation. Another proposal is to provide what can be called a "flap" of wadding, which can be reinforced with a portion of the fabric base, which will cover a conventional loop seam, preferably on the paper side of the fabric. Examples of this are described in CA 1, 303,833 and EP 0 294 951 mentioned above. In each of these, in the loop seam construction, a short flap of wadding is provided which is attached to one of the ends to be joined, and which attempts to cover the joint after the loop seam has been assembled. In the patent of E.U.A. No. 4,601, 785 it is recommended to join the batting flap by gluing or sewing. In the patent of E.U.A. 4,842,925 it is recommended to use brittle or soluble yarns adjacent to the seam. Either during or after the stitching step to join the batting, these threads are removed allowing the batting flap to be cut and placed in position. In EP 0 294 951 it is recommended to use an additional layer of machine direction yarns on the cloth base to reinforce the batting flap. Seams of this type are difficult to assemble, and have the disadvantage that the fabric on the flap supports the wadding also frays, leaving the wadding without support, and resulting in marked paper.

BRIEF DESCRIPTION OF THE INVENTION This invention seeks to provide an alternative solution to these problems. A press felt is provided wherein a laminated fabric is used as the base fabric, wherein only the first layer is joined end to end by a loop seam. The second layer is cut to provide a flap that carries batting over the loop seam. The second layer also inclines with respect to the first layer, so that the cut seam is at an angle with respect to particularly the wefts of the fabric, thus inhibiting the loss of these yarns due to the unraveling of the fabric. The second fabric is also made in relatively narrow strips, and in this way decreases the chances of unraveling. Therefore, in a first embodiment, this invention seeks to provide a felt fabric for a multilayer papermaking press comprising, in combination: a first layer of woven fabric to which a loop seam in the transverse direction of the machine is incorporated. , a second layer of fabric on the side of the paper side of the first layer of fabric, a layer of sewn wadding that is applied to the side of the paper of the second layer that penetrates the first layer of fabric, thus joining the first and second layer, and a flap comprising a short length of the second layer of cloth with attached wadding covering the loop seam in the first layer, wherein: (a) the second layer contains a plurality of relatively narrow strips, and (b) the strips of the second layer are located with a lateral end at a first angle of inclination in direction of the machine, and (c) the first angle of inclination has a value of more than 1 ° to less than 20 °. In a second embodiment the fabric also includes a third machine side layer of the first layer wherein: (a) the third layer comprises a plurality of relatively narrow strips, and (b) the strips of the third layer are located with a lateral end at a second angle of inclination in the machine direction, and (c) the second angle of inclination has a value of more than 1 ° to less than 20 °.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in one embodiment with reference to the drawings, wherein: Figure 1 is a section perpendicular to the plane of a press felt through a loop seam, Figure 2 is a side view of partially sectioned paper of a felt for press, and Figure 3 is a side view of the partially sectioned paper of an alternative press felt.

DESCRIPTION OF THE PREFERRED MODALITIES In this invention the following terms are of great importance: "machine direction" refers to the direction taken along the length of the press section, which is substantially parallel to the direction in which the felt moves for press, and the associated term "transverse direction of the machine" refers to the direction substantially at a right angle in the machine direction; "paper side" refers to the side of a press felt, or of the basic fabric structure, this is to the paper when the press felt is installed, and the related term "machine side" refers to the side of the press felt, or of the basic weaving structure, which is find towards the press section rollers when the press felt is installed; and "inclination angle" refers to an angle between a lateral end of a fabric that is part of the basic weaving structure and the direction of the machine. With reference to Figure 1, the section shown is taken along the direction of the machine. The press felt that is generally shown with the 1 is essentially composed of 3 layers, where a fourth can be added, and which includes a seam that is mainly shown with the 2. The base support fabric comprises a first side fabric of the machine 3 including the seam 2. Covering the paper side of the first layer 3 there is a second layer 4; these layers are joined by the applied batt 5 which penetrates through the second layer 4 and to a certain extent of the first layer 3. It is thus desired, an additional layer of batting can be applied to the side of the machine of the first layer 2 as indicated by the number 6. The first layer, which as shown is a relatively simple double layer fabric, includes wefts 7 in the transverse direction of the machine, and warps 8 and 11 in the direction of the machine. The loop seam is formed by weaving back lengths of the warps 8 and 11 respectively to provide the loops 9 and 12 respectively. The seam is joined by the central pin 10 inserted in the loops 9 and 1 1. This form of seam structure is well known.

The second upper fabric on the paper side of the first is a relatively thin fabric and as shown comprises a simple weave with wefts 13 and warps 14. The manner of construction of this fabric layer is described below. In the region of the seam 2 both the second fabric 4 and the batt 5 are cut on line 16 (batting 6, if used, is also cut on line 17) to provide a flap 15. In use, the press felt moves in the direction A, so that the flap 15 goes forward of the line of the central sewing pin 10. In figure 2 there is a sectional view of the face of the paper side layer of the fabric in figure 1. The side of the paper side suitable is the wadding layer 5. The wadding layer 5 covers the second fabric 4, which is located on the paper side of the first layer 3. The first layer 3 is woven to be the width of the press felt, while the second layer is woven as a much narrower strip, so that the two distances X and Y, which are more or less in the cross direction of the machine , be different, being Y greater than X. The second narrower layer is also applied on the pr imera with a side end 4A at an angle of inclination? in the direction of the machine indicated at 4B, which is substantially parallel to the end of the press felt. The second layer is applied using essentially the techniques described by Best et al., In the U.S. patent. No. 5,268,076 and by Rexfelt et al., In the US patent. No. 5,360,656, presentations that are incorporated herein by reference.

The fabric of Figure 2 is assembled as follows. As a first step the first layer of fabric is woven in a suitable double layer design based on the conditions obtaining thus the press section where the press felt is going to be used. It can be of flat weave, or preferably woven as a continuous form. An appropriate length of this fabric is taken and the loop seam 2 is created to provide a continuous stitched loop 3 of the required length. The second layer 4 is woven with the first with a lateral end 4A at a desired angle of inclination? in the direction of the machine 4B, using essential techniques described by Best and others, in the patent of E.U.A. 5,268,076 and by Rexfeit et al. In the US patent. 5,360,656. The wadding layer on the paper side 5 is applied using conventional techniques, or to obtain a desired wadding orientation using the method described by Krcma et al., In a document entitled "Perpendicular Laid Bul and Nonwovens", 7th World Conference of the Institute Textile, Atlanta, Georgia, USA, September 1994, which is incorporated herein by reference. After the wadding has been applied, the wadding 5 and the second fabric layer 4 are cut to 16 on the correct downward side of the center pin line so that the seam can be separated and allow installation in the press section. , and to provide the flap 15. An alternative fabric is shown in figure 3. This fabric is similar to that shown in figures 1 and 2, and is constructed by the same techniques. The fabric as shown has a wadding layer on the paper side 5, and below it is a second layer 4 wound on a first layer 3. In addition, a third layer 20 of the same type as the second layer 4 is also provided on the machine side of the first layer 3. The width Xi and X2 of the strips used in the first and third layers 4 and 20 must be the same. However, these two widths should preferably be selected to avoid a situation where an end line contacting the second layer is aligned with and directly on an end line by contacting the third layer, because no space at the extreme contact at any of the layers should cause marking of the paper. The second layer 4 is wound at a first angle of inclination? -? Between the lateral end 4A and the machine direction indicated at 4B, and the third layer 20 is wound at an angle of inclination? 2 between the end side 20A and the machine direction indicated in 20B. The first and second inclination angles must be the same, and they must be in the same direction in relation to the machine direction. The importance of the combination of using a relatively narrow strip for the second layer, or for the second or third layer, having a lateral end at an angle of inclination? in machine direction, it is that when the second fabric is cut to open the seam at any point there is only a short length of second thread of fabric and, when it is used, third, it can fray when the fabric press is in use . The amount that can be unraveled is limited by the width X of the narrow strip of the layer, and the value of the angle of inclination?.

In experimental fabrics it has been found that angles of inclination as low as 1.7 ° (which corresponds to an angle of 3 cm per meter) can be used successfully, even at a maximum angle of about 20 ° since if this angle the risk of fraying is greater, it becomes a problem again. It seems that an angle of inclination of less than about 10 ° is convenient. The widths related to the first layer and the strips used for the second and third layers, as appropriate, are determined at least in part by the width of the press section. The strips must have a suitable width so that they can be woven, and they must be significantly narrower than the first layer, since if they are too wide, the amount of thread that can be frayed increases. A ratio of at least 2: 1 seems convenient. However, for a broad press section it is not possible to maintain such a low relation, and it seems that the relations of at least about 20: 1 can be useful. It is also possible to use different widths of the strips when both the second and third layers are used. The choice of fabric of the fabric used for each of the layers is open to certain flexibility, and will mainly be determined by the proposed conditions of use. As a generality, the first layer should be a double layer fabric, mainly to facilitate the construction of the loop seam. The second, and when used, the third layer is generally a single layer fabric, and preferably it is a different fabric in terms of yarn count per centimeter than the first layer. It can be a fine fabric or a coarse fabric, and in some applications it is possible to use a second, or third, layer of a double layer fabric. The second and third layer fabrics must also be the same. In addition, these fabrics do not need to be woven, and a strip of woven fabric can be used in certain applications.

Claims (24)

NOVELTY OF THE INVENTION CLAIMS

1. - A multi-layered felt fabric for papermaking press comprising in combination: a first layer of woven fabric that is incorporated into a loop seam in the machine's transverse direction, a second layer of fabric over the side face of the paper of the first layer of fabric, a layer of sewn wadding applied to the side of the paper side of the second layer that penetrates the first layer of fabric joining the first and second layer together, and a flap comprising a length cutting the second layer of cloth with batting covering the loop seam in the first layer, wherein: (a) the second layer comprises a plurality of relatively narrow strips, and (b) the strips of the second layer are located with a lateral end at a first angle of inclination in the machine direction, and c) the first angle of inclination has a value of more than 1 or less than 20 °.

2. A fabric according to claim 1, further characterized in that it includes a third layer on the machine side of the first layer wherein: (a) the third layer contains a plurality of relatively narrow strips, and (b) the strips of the third layer are located with a lateral end at a second angle of inclination in the direction of the machine and, (c) the second angle of inclination has a value of more than 1 or less than 20 °.

3. A fabric according to claim 1, further characterized in that the first angle of inclination has a value of more than 1o to less than 10 °.

4. A fabric according to claim 2, further characterized in that the first inclination angle for the second fabric layer has a value of more than 1 or less than 10 °.

5. A fabric according to claim 1, further characterized in that the second inclination angle for the third layer of fabric has a value of more than 1 or less than 10 °.

6. A fabric according to claim 2, further characterized in that the inclination angles of the second and third fabric layers are equal.

7. A fabric according to claim 2, further characterized in that the inclination angles of the second and third fabric layers are not the same.

8. A fabric according to claim 2, further characterized in that the angles of inclination of the second and third layer of fabric are in the same direction with respect to the direction of the machine.

9. A fabric according to claim 2, further characterized in that the inclination angles of the second and third layers of fabric are not in the same direction in relation to the machine's direction.

10. A fabric according to claim 1, further characterized in that the ratio of the widths of the first and second layers is at least 2: 1.

11. A fabric according to claim 2, further characterized in that the ratio of the widths of the first and second layers is at least 2: 1.

12. A fabric according to claim 2, further characterized in that the ratio of the widths of the first and third layers is at least 2: 1.

13. A fabric according to claim 2, further characterized in that the widths of the second and third layers are equal.

14. A fabric according to claim 2, further characterized in that the widths of the second and third layers are not equal.

15. A fabric according to claim 1, further characterized in that the wadding is oriented in a desired direction.

16. A fabric according to claim 1, further characterized in that the second layer of fabric is flat or knitted.

17. - A fabric according to claim 2, further characterized in that the wadding is oriented in a desired direction.

18. A fabric according to claim 2, further characterized in that the second fabric layer is flat or knitted.

19. A fabric according to claim 2, further characterized in that the third layer of fabric is flat or knitted.

20. A fabric according to claim 1, further characterized in that the first layer is sewn as a double layer fabric.

21. A fabric according to claim 2, further characterized in that the first layer is sewn as a double layer fabric.

22. A fabric according to claim 1, further characterized in that the ratio of the widths of the first and second layer is at least 2: 1 to 20: 1.

23. A fabric according to claim 2, further characterized in that the ratio of the widths of the first and second layers is at least 2: 1 to 20: 1.

24. - A fabric according to claim 2, further characterized in that the ratio of the widths of the first and third layers is at least 2: 1 to 20: 1.