US2180054A - Paper maker's drier felt - Google Patents

Description

PAPER MAKERS DRIER FELT Filed Aug. 2, 1.938

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Patented Nov. 14, 1939 STATES .PTET

PAPER MAKER/S DRIER. FELT Thomas Hindle and Sam Lord, Blackburn, England 2 Claims.

The invention relates to an improved construction of woven drier felt, as used on the drying cylinders of paper making machines, whereby the drier felt will give more eicient and better drying of the paper, that is to say, less steam will be required and the paper will be dried more evenly across the width of the sheet.

The function of a drier-felt on a paper ma'- chine is to press the moist web of paper uniformn ly and successively against the steam-heated cylinders of the machine, thereby facilitating the transmission of heat from the cylinders to the paper for the purpose of drying the latter.

Drier ielts of known construction havea close homogeneous compact texture, and Whilst moisture is readily absorbed from the paper, the passage of air through the felt from one face to the other is very restricted. As a consequence, a drier-felt of such known construction becomes saturated, in which condition, as the moisture lls up the small pores of the felt, it is even more impervious than when dry. Under these conditions the drying of the paper is seriously retarded, and it is essential to maintain the cylinders at a higher temperature than would be otherwise necessary, thus entailing a considerably higher steam consumption.

Furthermore, moisture-laden air may be trapped forming pockets between the paper and the felts, which pockets frequently prevent the paper being dried evenly across the width of the sheet.

To improve the drying of the paper, the drying sections of some paper machines are equipped with various systems of ventilation. In some oi these systems heated dry air is forced into the spaces', or some of them, between the paper, felts, cylinders, etc., and in others the moisture-laden air is extracted from those spaces. In either case, the maximum useful effect of such ventilation is not obtained owing to the highly impervious nature of the drier felts of known construction.

The object of the invention is to provide a drier felt of greatly increased porosity, so as to permit air to pass very freely through the felt from one face to the other, according to the particular requirements of the ventilation system in use, but it will be understood that the improved drier-felt is also particularly advantageous if no special means for ventilation are available, inasmuch that natural ventilation is encouraged due to the pronounced porosity of the drier-felt.

Since the air passes freely through the felt (ci. 13e-ics) it is prevented from becoming saturated and the drying of the paper is thereby accelerated so permitting the cylinders to be operated at a lower temperature with a resultant decrease in steam consumption. Moreover, owing to the lower temperature to which the felt is subiected its useful life will be prolonged.

According "to the invention the drier felt is woven with two or more layers having the warp and weft threads on face and back arranged in groups, each group comprising at least three threads, such groups being interwoven so as to forni well-dened holes at the points where they intersect and so that these holes shall coincide in both or all layers of the drier-felt the weft threads of each group in one layer are in vertical alignment with those oi the corresponding group or groups in the other layer or layers and the threads oi the warp groups which interweave therewith are similarly in vertical alignment.

In the case of a two-layer drier-felt, the two layers may be bound together by an additional intermediate layer of weit, which layer may consist of the same number oi weit threads as Vused to form the face and back layers, or alternatively may consist of a smaller number. f

The invention will be described with reference to the accompanying drawing in which Fig. 1 is a View showing the appearance of the face and of the back of a felt woven in accordance with the invention.

Fig. 2 is a diagrammatic longitudinal section across the weft of a two-layer drier felt in which the surface weft threads and the warp threads are divided into groups of three and one binder weit is employed for a group of three wefts on each surface.

Fig. 3 is a diagrammatic transverse section across the warp of the two layer drier felt shown in Fig. 2.

Fig. 4 is a diagrammatic longitudinal section across the weft of a two-layer drier telt in which the surface weft threads and the warp threads are divided into groups of three, and two binder wefts are employed for a group of three wefts on each surface.

Fig. 5 is a diagrammatic transverse section across the warp of the two layer drier felt shown in Fig. s.

Fig. 6 is a diagrammaticlongitudinal section across the weft of a two-layer drier felt in which the surface weft threads and the warp threads are divided into groups of three and three binder wefts are employed for a group of three weits on each surface.

Fig. 7 is a diagrammatic transverse section through the warp of the two layer drier felt shown in Fig 4.

In the weave illustrated in Figs. 2 and 3 for each repeat there are twelve individual' Warp threads a, i. e., four groups each of three threads and fourteen weft threads b, i. e., four groups each of three threads and two binder threads, one for each pair of groups of surface threads. The warp threads are designated la, Za-IZE, and the weft threads lb, ZL-Mb, the threads 4 and Illo being the binder threads.

As will be seen from Figs. 2 and 3, the rst group of weft threads lb, 3b and 6b and the third group 8b, lill and 3b form one surface of the felt and the second group 2b, 5b and 'lb and fourth group 9b, i2b and Mb, the other surface, the rst and third groups interweaving with the rst group la, 3EL and 5P- and the third group 1a, 9a and Ila of the warp threads and the second and fourth group with the second group 2a, 4a, and 51L and fourth group 8a, Illa and I2a of the warp threads. The binder weft 4b being woven alternately with the first and fourth groups of warp threads and the binder weft Hb with the second and third groups thereof. Neither of the binder wefts lib and lib appear on the surfaces of the felt but lie between each pair of groups of the three surface threads.

The weave illustrated in Figs. 4 and 5 is similar to that shown in Figs. 2 and 3 except that four binder weft threads 3b, 5b, lib and I3b are employed, the threads 3b and 5b following one path and the threads Hb and i3b the alternate path. As before the twelve warp threads are divided into four groups la, 3a and 5a; 2a, lr1 and Ga; la, 9a and lla; and 83, lila and i221 whilst the twelve weft threads forming the surfaces of the felt are divided into four groups Ib, 4b and 1b; 2b, 6b and Sb; 9b, l2b and 15b; and 10b, Mb and I6b respectively. None of the binder wefts 3b, 5b, Hb or I3b appear on the surfaces of the felt but lie between each pair of groups of the three surface threads.

The weave illustrated in Figs. 6 and 7 is similar to that shown in Figs. 2 and 3 and Figs. 4 and 5 except that six binder weft threads 2b, 5b, 8b, IIb, Elib and l'lb are employed, the threads 2b, 5b and 8b following one path and the threads I lb, Mb and iib the alternate path. As before the twelve warp threads are divided into four groups la, 3a and a; 2a, 4a and 5a; la, 9a and Ila; and 8a, Illa and I 2a whilst the twelve weft threads forming the surfaces of the felt are divided into four groups lb, Gb and 1b; 3b, '6b and 9b; 10b, I3b and 18h; and 2b, I 5b and Ib respectively. None of the binder wefts 2b, 5b, 3b, Hb, |11b and l'lb appear on the surface of the felt but lie between each pair of groups of the three surface threads.

Instead of the weft threads and warp threads being divided into groups of three they may be divided into groups of four or more in which case the number of binder weft threads for each pair of groups may be any number from one up to the number of threads in a group.

A felt woven as hereinbefore described produces a pronounced hole a: at each of the points where the groups of Warp a and weft b intersect and the formation of these holes may be assisted by reeding the Warp with siX warp threads per dent, i. e., the warp threads forming each pair of groups. If each group contains four warp threads then they could be reeded eight threads per dent and so on. This however is not essential, as the interweaving of the weft causes the grouping of the warp threads and the interweaving of the Warp causes the group of the weft threads on the face and back.

In a felt woven according to the invention there is no tendency for the groupings of the warp and weft threads to be lost and Consequently when the drier felt is running on the paper machine the holes a: will not be removed.

The improved drier-felt may be woven from vegetable, animal, mineral or artificial threads, or any combination thereof, according to particular requirements.

What we claim as our invention and desire to protect by Letters Patent is:

1. A two layer drier felt comprising groups of weft threads and groups of warp threads on the face and back, the threads of each group lying continuously in side by side relationship and each group containing the same number of threads and at least three, the groups of weft threads of the face being interwoven with the groups of warp threads of the face and the groups of weft threads of the back being interwoven with the groups of warp threads of the back and the groups of each layer being in vertical alignment with those of the other layer whereby well defined coinciding vertical holes are formed at the points where the groups of weft threads intersect the groups of the warp threads and a plurality of intermediate binding weft threads not greater in number than the threads in each surface group, for binding the two layers together which binding weft threads do not appear on either surface but lie between the surface groups each binding thread lying in the same perpendicular plane as a pair of weft threads in the top and bottom surfaces respectively so that it will not obscure any of the vertical holes.

2. A two layer drier felt comprising groups of weft threads and groups of warp threads on the face and on the back, the threads of each group lying continuously in side by side relationship and each group containing three threads, the threads both weft and warp of one group of one surface being in vertical alignment with the corresponding group of the other surface whereby on interweaving the weft and warp groups of each surface well dened Vertical holes are formed, the holes in each surface being in alignment and binder weft threads of a number not greater than three which do not appear on either surface but lie between them the threads of each group lying continuously in side by side relationship,

'THOMAS HINDLE. SAM LORD.

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