BRIEF DESCRIPTION OF THE DRAWINGS
In order that the present invention may be more readily understood several preferred embodiments of the papermakers dryer fabric structure according to the invention will now be described by way of example with reference to the accompanying drawings wherein:
FIG. 1 shows a cross machine direction view of a first dryer fabric according to prior art;
FIG. 2 further illustrates the first dryer fabric of FIG. 1;
FIG. 3 is a segmentation of a pair of stacked machine direction warp yarns and segmentation of the surface and structural void volume of the first dryer fabric of FIG. 1;
FIG. 4 shows a cross machine direction view of a second dryer fabric according to prior art;
FIG. 5 further illustrates the second dryer fabric of FIG. 4;
FIG. 6 is a segmentation of a machine direction warp yarn and segmentation of the surface and structural void volume of the second dryer fabric of FIG. 4;
FIG. 7 is a definition of void volume inside the structure of the fabric and void volume at the surfaces of the fabric;
FIG. 8 shows a cross machine direction view of a first fabric according to the present invention;
FIG. 9 further illustrates the first fabric according to the present invention;
FIG. 10 is a segmentation of a machine direction warp yarn of the first fabric according to the present invention;
FIG. 11 shows a cross machine direction view of a second fabric according to the present invention;
FIG. 12 is a sketch showing a cross machine direction view of a third fabric according to the present invention;
FIG. 13 is a sketch showing a preformed castellated cross machine direction weft yarn according to the present invention; and
FIG. 14 is a sketch showing a profiled cross machine direction weft yarn according to the present invention.
DETAILED DESCRIPTION
FIG. 1 shows a cross machine direction view of a first dryer fabric A according to prior art. This fabric A is designed to carry a not shown paper web on one fabric surface and is woven from machine direction yarns 1 and cross machine direction yarns 2 wherein the yarns 1, 2 cross over each other to create void volume V.T, V.U1, V.U2 both inside the structure T of the fabric A and at the surfaces U.1, U.2 of the fabric A.
FIG. 2 is a line drawing of a p-CT scan of the first dryer fabric A of FIG. 1. This sample is tomographed with a p-CT-machine, the objects are examined using software such as VGStudioMax to segment the path of a machine direction yarn 1 or stacked machine direction yarns in relation to the cross machine direction yarns 2. The total void volume of structural voids 3 and surface voids 4.1, 4.2 is then separated from the material section. The void volume V.T, V.U1, V.U2 of each void 3 inside the structure T of the fabric A and void 4.1, 4.2 at the surfaces U.1, U.2 of the fabric A is measured.
FIG. 3 is a segmentation of a pair of stacked machine direction warp yarns 1 of the first dryer fabric A of FIG. 1. This segmentation has a calculated void volume V.T inside the structure T of the fabric A of 0.903 mm3 and the void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric A is calculated at 1.504 mm3. Moreover, the ratio of void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric A to void volume V.T inside the structure T of the fabric A is 1.67:1. In this example the fabric A has 3,468 segments in a 100×100 mm area, therefore the void volume V.T inside the structure T of the fabric A is 5,216 mm3/100 mm2 and void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric A is 3,132 mm3/100 mm2.
FIG. 4 shows a cross machine direction view of a second dryer fabric B according to prior art. Also this fabric B is designed to carry a not shown paper web on one fabric surface and is woven from machine direction yarns 1 and cross machine direction yarns 2 wherein the yarns 1, 2 cross over each other to create void volume V.T, V.U1, V.U2 both inside the structure T of the fabric A, B and at the surfaces U.1, U.2 of the fabric B.
FIG. 5 is a line drawing of a p-CT scan of the second dryer fabric B of FIG. 4. This sample is also tomographed with a p-CT-machine, the objects are examined using software such as VGStudioMax to segment the path of a machine direction yarn 1 or stacked machine direction yarns in relation to the cross machine direction yarns 2. The total void volume of structural voids 3 and surface voids 4.1, 4.2 is then separated from the material section. The void volume V.T, V.U1, V.U2 of each void 3 inside the structure T of the fabric B and void 4.1, 4.2 at the surfaces U.1, U.2 of the fabric B is measured.
FIG. 6 is a segmentation of a machine direction warp yarn 1 of the second dryer fabric B of FIG. 4. The segmentation is of void volume V.T inside the structure T of the fabric B between machine direction yarns 1 and cross machine direction yarns 2. These voids 3 are structural as they have an opening between their surfaces, where the said opening is narrower than the length of the shortest surface in the void 3. The segmentation is also of void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric B.
FIG. 7 is a definition of void volume V.T inside the structure T of the fabric B and void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric B. The segmentation of void volume V.T inside the structure T of the fabric B between machine direction yarns 1 and cross machine direction yarns 2 can be seen. These voids 3 are structural as they have an opening between these surfaces, where the said opening is narrower than the length of the shortest surface in the void 3. Furthermore, the segmentation of void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric B, C can also be seen.
The following FIGS. 8 to 14 show dryer fabrics according to the present invention. They have all in common that the machine direction yarns and the cross machine direction yarns of these fabrics are interlaced so that virtually all of the void volume is exposed to the paper web carrying and non-paper web carrying surfaces.
FIG. 8 shows a cross machine direction view of a first fabric C according to the present invention. The cross machine direction yarns 2 form at least one plain weave 5 with multiple wefts 6.1, 6.2 in the same shed 7. The void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric C is significant compared to the void volume V.T in the structure T of the fabric C.
FIG. 9 is a line drawing of a p-CT scan of the first fabric C of FIG. 8. The sample is again tomographed with a p-CT-machine, the objects are again examined using software such as VGStudioMax to segment the path of an machine direction yarn 1 or stacked machine direction yarns in relation to the cross machine direction yarns 2. The total void volume of structural voids 3 and surface voids 4.1, 4.2 is then again separated from the material section. The void volume V.T, V.U1, V.U2 of each void 3 inside the structure T of the fabric B and void 4.1, 4.2 at the surfaces U.1, U.2 of the fabric C is again measured.
FIG. 10 is a segmentation of a machine direction warp yarn 1 of the first fabric C of FIG. 8. The segmentation is of void volume V.T inside the structure T of the fabric C between machine direction yarns 1 and cross machine direction yarns 2. These voids 3 are surface as they have an opening between their surfaces, where the said opening is wider than the length of the shortest surface in the void 3. The segmentation is also of void volume V.U1, V.U2 at the surfaces of the fabric C.
The void volume V.T inside the structure T of the fabric C ranges from 0 to 0.9 mm3, preferably from 0 to 0.5 mm3, and most preferably from 0 to 0.15 mm3 for a path of warp yarn or a stacked warp yarn segment and/or the void volume V.U1, V.U2 at the surfaces of the fabric C ranges from 0.5 to 1.5 mm3 and preferably from 0.75 to 1.0 mm3. The calculated value for the shown fabric C are: calculated void volume V.T inside the structure T of the fabric C of 0.023 mm3 and calculated void volume V.U1, V.U2 at the surfaces of the fabric C of 0.927 mm3.
Furthermore, the void volume V.U1, V.U2 at the surfaces of the fabric C and the void volume V.T inside the structure T of the fabric C have a ratio between 1:1 and 30:1 and preferably between 4:1 and 25:1. The ratio for the shown fabric C has been calculated at 4.03:1.
In this shown example, the fabric C has 8,100 segments in 100×100 mm area, therefore the void volume V.T inside the structure T of the fabric C is 186.3 mm3/100 mm2 and void volume V.U1, V.U2 at the surfaces of the fabric C is 7,508 mm3/100 mm2.
FIG. 11 shows a cross machine direction view of a second fabric D according to the present invention. The cross machine direction yarns 2 form at least one plain weave 8 with a single weft 9 in the same shed 10. The void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric D is significant compared to the void volume V.T in the structure T of the fabric D.
FIG. 12 is a sketch showing a cross machine direction view of a third fabric E according to the present invention. The machine direction yarns 1 are vertically stacked in at least two systems, presently in four systems 11 to 14. Again, the void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric E is significant compared to the void volume V.T in the structure T of the fabric E.
FIG. 13 is a sketch showing a preformed castellated cross machine direction weft yarn 15 of another fabric F according to the present invention. This shown weft yarn 15 is used to fill the internal shape of the weave pattern of machine direction warp yarns 1 and preformed castellated cross machine direction weft yarn 15.
FIG. 14 is a sketch showing a profiled cross machine direction weft yarn 16 according to the present invention. This shown weft yarn 16 would be extruded in a cross sectional shape to fill the void volume V.T inside the structure T of the fabric G in the fabric G.
The inventive fabrics C to G are additionally in common that internal void volume V.T beneath at least one layer of a machine direction yarn 1 and inside the structure T of the fabric C to G ranges from 0 to 0.9 mm3, preferably from 0 to 0.5 mm3 and most preferably from 0 to 0.05 mm3 and/or that the void volume V.T inside the structure T of the fabric C to G ranges from 0 to 3,000 mm3/100 mm2 and preferably from 0 to 250 mm3/100 mm2. The void volume V.U1, V.U2 at the surfaces U.1, U.2 of the fabric C to G ranges from 0 to 10,000 mm3/100 mm2 and preferably from 2,500 to 10,000 mm3/100 mm2.
The additional weft yarns 2 have a yarn diameter between 0.10 and 0.40 mm in order to fill the void volume V.T inside the structure T of the fabric C to G and have a high crimp level in the range of up to two times the vertical dimension of the warp yarn 1. Furthermore, the yarns 1 possess a high warp density, where the warp is not vertically stacked, by increasing the warp cover above 120% and possess a high tension level due to crimp interchange from the effect of the heat setting machine of above 5 kg/cm. Thereby, the yarns possess a melting point below the material used in a comparable parent fabric, which is between 90 and 240° C.
REFERENCE NUMERALS LIST
1 machine direction yarn
2 cross machine direction yarn
3 structural void
4.1 surface void
4.2 surface void
5 weave
6.1 weft
6.2 weft
7 shed
8 weave
9 weft
10 shed
11 system
12 system
13 system
14 system
15 castellated cross machine direction weft yarn
16 profiled cross machine direction weft yarn
- A first dryer fabric (prior art)
- B second dryer fabric (prior art)
- C first dryer fabric (invention)
- D second dryer fabric (invention)
- E third dryer fabric (invention)
- F fourth dryer fabric (invention)
- G fifth dryer fabric (invention)
- T structure
- U.1 surface
- U.2 surface
- V.T void volume
- V.U1 void volume
- V.U2 void volume
Patent Application
20070261753
