US2172430A - Single ply drier felt with asbestos facing - Google Patents

Description

sept. l12, 1939.

W. A. BARRELL SINGLE PLY DRIER FELT wlTH AsBEsTos FACING Filed 001'.. 14, 1937 IWW Patented Sept.l .12, 1939 l UNITED #STATES l PATENT or-HCE I *.sINGu-z PLY 1 imHingis;.enig,wrm` asBEs'ros A i William A. Harrell', North Andover, Mass., assignor to Lawrence Duck ompany, Lawrence,

Mass., a corporationoi Massachusetts Application October 14, 1937, Serial No. 168,856y

8 Claims.

,asbestos ber; which contains a minimum of cations to the lines 4-4 5-5 asbestos in its construction; which is sufficiently porous to permit ready escape oi' water vapor from the paper; which will notl glaze over on the surface after long continued use; and which stretches less and preserves more nearly its original Width than asbestos faced felts of single ply construction heretofore made. Its purposes are in the main the same as those of the drier felt' disclosed in my pending application Serial No.

153,309, led July 13, 1937 (Letters Patent No. 2,168,928 -granted vAugust 8, 1939). 4.It embodies a -diierentsolution of the same problem, while as compared with the felt of said prior application its objects are to reduce the ratio of asbestos strands to strands made of other materials, and to produce astronger and more rugged felt which, under like conditions of use, willv elongate less and diminish in width the felt-there described.

The principles and particulars of the invention are described in the following specification in connection with the drawing, in which,-

Fig. 1 isa face view of l.a fragment of a drierl felt embodying this invention;

Fig. 2 is a rear or. bottom plan View of the same i'elt; Y

Fig. 3 is a diagrammatic face plan view of the felt vshowing the constituent strands separated and spaced apart for clearness of illus-5 tration; I

Figs. 4 and 5 vare longitudinal sectional view g and Fig. 6 a cross sectional view of the felt shown in Figs. 1 and 2 but o n avscale twice as large as the latter iigures. The planes on which such sections are cut correspond in relative loand S-Grespectively o1' Fig. 3. A

Like reference characters designate the same parts wherever they occur in all the gures.

In its preferred construction, the felt ofthis invention is constructed mainly of cotton and contains a relatively small proportional contentl of asbestos. It is made of .body warp, and weit or lling, strands interwoven as a plain weave, and iloat warp strands, part of which are as` bestes and the rest of cotton overlying the face.

The body warp strands are designated a and b,

less than (ci. 13s-ssa) r and the strands or picks of iilling are designatedc anddistinguished from one another where necessary by exponents. t a passes under a pickc' of the illing, lover the next adjacent or successive pick c, under the next successive. pick c3., over the next pick c4;

c2 and 'c3 of the filling, under the next pick c4,- over the next three 'picks c5, c,'c",.under' the next.

pick cs; and so on throughout the length of the felt. The iloat warp strands further comprise' an asbestos strand e which passes under the pick c2 of the iilling, over the groupr of successive picks c, c4, c5, under the pick, c, over the-next three picks c", ca and cg; and so on throughout the length of the felt. The float warp strands furthea` comprise a cotton, strand l which passes over the same groups of successive as'the strand d. The oat warp strands further `comprise a cotton strand g whichpasses over the same groups of successive picks of the tilling and under the same isolated picks as the strand e. The pattern of such float warp strands is repeated in succession throughout the -widtl'i of the felt. The oat warp'strands alternate I with the body warp strands thus:g, b, e, a, l,

Thus the loops lof any oat warp pass under l,the middle one of each group oi three picks vwhich are overpassed by the next iloat warp at either side.

Although I have 'described certain of the achwarp strand designated f picks of filling and under the same isolated picks g strands as being oi asbestos, it is not to'be in- -A ierred that they are made wholly and exclusively of-asb'estos iiber. Inasmuch as asbestos alone cannot practicably be spun with enough looseness and softness to be capable of spreading out so as to make a smooth and nearly continuous surface, and at the same time. lwith enough tensile strength to hold together in weaving. the asbestos bers. are combined with other4 fibers or strands having greater tensile strength. I prefer to use compound strands of the construction shown in my Letters Patent No. 2,(i98,995 granted November 16, 1937, although I may, without departure from the invention, use strands of other constructions whether now known or which may become known hereafter. In any event the term asbestos strand" is used 'in this speciiication and in the following claims with a scope wide enough to include all strands containing-suicient asbestos to serve the purposes hereinafter described.

material laid in parallel, or slightly twisted together.

The body warp and float warp strands are all taken from the same beam, but as the take up of the body warp strands in weaving is greater than that of the float warp strands (due to the fact that the body warp strands pass over and under every other pick of filling, while the iloat warp strandspass under only one in four picks), they are put under greater tension and the oat warp strands are laid loosely onthe face of the felt. 'I'his virtual freedom from tension of the oat warps is important, particularly as to the asbestos strands, because these are relieved of tensile stress and strain in carryingl the paper through the drier, and left free to be mashed down and spread out by the pressure against the drums of the drier.

The relatively large size of the weft strands is important for a number of reasons, It causes the body warp strands to be somewhat indented into .the weft strands in the course of the weaving,

and resists crimpingV or bending of the weft strands by the pulling tension of the warp strands subsequently. Such crimping of weft strands tendsA to reduce their overall length and hence to narrow the fabricf of which they are a part.'

Hence the resistance to crimping aiorded by the thick weits here prevents any substantial or considerable narrowing of the felt in use. Another function and purpose of the thick wefts is to hold the seam where the ends of the felt are sewed together on the drier.

In the illustrative specimen there are ten each of the body warp strands a and b and ve each of the warp strands d, e, f and g per inch of width .of the felt, and twelve picks of filling per inch of length. These details, however, may be widely varied, and so also may the dimensions and struc- Y ture of the component strands.

riens made in accordance with the principles of the felt herein described'. and of like or equivalent construction, contain a minimum of proportional content of asbestos, but enough to protect the body warp strands and form a suc'iently smooth face to avoid making so-called felt marks inthe soft wel: paper. l

, In being flattened in the course of normalusage the soft asbestos strands spread out so that they wholly or nearly i111 the interstices between them and the adjacent cotton float warp strands and so make the desired smoothness of face. But

wide spacing of the asbestos strands and presence of intermediate cotton strands between them in the face of the present felt prevents development 'of any such impervious glazed surface covering and insures the preservation of numerous smallopen spaces uniformly distributed over the face of the felt, wide enough to permit free passage of vapor, but not wide enough to permit intrusion of the paper.

All of the iloat warp strands, the cotton as well as the asbestos strands, are so moved by the harnesses which control them in weaving that they are caused to lie on the surface of the felt outside of the more tightly tensioned body warp strands, and largely overlie and cover the wales or loops of the latter which overlie the weft strands. Thus the body warp strands are prevented from coming into'direot contact with the paper and are insulated in some measure from the destructive eiIects of heat and moisture and do not becomel so weak las to break untilA the overlyingstrands havebecome unserviceable. No 1 pulling load is imposed on the strands whichform the contact surface, andthe strands which take the tension are preserved for a useful life as long as that of the strands which compose thersurface, This result is accomplished with the use of less material and with a construction of felt having less thickness and weight than the two ply felts of the prior art. The single ply construction and the bulky weft strands, which are indented rather than crimped by the pull of the warp strands,

makes the felt more porous than the commercialV two ply felts and preserves its original porosity Y in substantially full measure. The resistance of the weft strands to crimping prevents the warp strands from being crowded appreciably more closely together. l

As compared with the commercial Iasbestos drier felts of the prior art the present felt is approximately 20% thinner, approximately 33% lighter in weight, and has breathing ability (ability to permit passage of vapor due to its porosity) which is lacking in the prior felts. It does not run wet, (i. e., deliver -the paper with more than its permissiblecontent of moisture, and it dries in its return passage to the receiving point more rapidly than the. prior art felts. A Its thickness is slightly greater than that of the felt ,described in my application Serial No. 153,309, (Patent 2,168,928)l but its weight is approximately the same and it contains a much smaller proportional content of It has greater strength an less capacity to narrow down in use. Y

While cotton is theA preferred material for all the nonstrands of this felt, and is the material which in practice will be used in the great majority of the felts made according to this invention, it is not the only material which may be used. I wish to make it understood that any other materials suitable for the purpose may be used .within the scope -of the protection here felt manufacture heretofore, but also others -asbestos warp and filling strands,

which may by test and experience be foimd hereafter to be satisfactory. Strands of such other suitable materials may be combined with cotton strands or with one another in producing a felt according to the invention.

What I claim and desire to secure by Letters Patent is:

1. A drier felt for paper machines comprising a warp and filling of non-asbestos strands woven as a plain weave with alternate warpstrands passing over, and intermediate warp strands passing under, the same picks of filling and each warp strand passing over and under successive picks in sequence, float warp strands containing asbestos nber each extending loosely over groups of successive picks and under single picks between such groups, and non-asbestos iioat warp strands similarly arranged picks of filling, the asbestos and nonfioat warp strands being located in alternation with one another across the felt and protectiveiy overlying the first named warpstrands on the paper-contact face of the felt. v 2. A drier felt for paper machines comprising a plain-woven body made of interwoven'nonasbestos float warp strands of soft texture arranged loosely on one face'of said body with loops at intervals interwoven with non-adjacent picks of the nlling, the lengths' of such iloat 'warp strands between said loops each overlying a group of successive picks, and non-asbestos float warp strands interspersed among the asbestos strands in suflicient number and sufiiciently near together to prevent formation of a continuous asbestos surface of the felt by spreading of the asbestos strands; the warp strands of the b ody being substantially' overlaid and protected by the float warp strands.

3. A drier felt as set forth in claim 2 in which the iilling strands are morebulky than the nonasbestos warp strands and are indented thereby, whereby they substantially prevent narrowing of the felt under the stresses applied in normal usage.

contact side of the felt, each of said iloat warp A strands being arranged to lie loosely over a group of successive picks of the filling and having loops passing under single picks of the -iilling between successive ZrOuDS. said loops beingv so arranged with respect to saidl that each float warp strand over the picks of the iilling which are underpassed by the loops Iof adjacent strands.

5. A drier telt for paper machines consisting of cotton body warp strands, cotton float warp strands, asbestos iloat warp strands and a cotton niling, the with all the picks of the iilling and alternate strands thereof passing opposltely to the intermediate strands around such picks, the iloat warp strands lying loosely on one face of the felt over groups of successive picks of lling and under single picks between successive groups,

each of said loops being arranged between two ofthe body warp strands, and the float warp strands being sufficiently numerous and close together to make a substantially smooth papercontact surface, and the cotton float warp strands being sunlci'ently numerous and interspersed among the asbestos strands at short enough intervals to prevent formation of a continuous asbestos surface on the felt by spreading of the asbestos strands.

6. A'drier ielt as set forth in claim 5, in which the iilling strands are bulkier than the cotton warp strands sumciently to prevent substantial narrowing of the felt under conditions of service.

'1. A single ply drier felt consisting of warpand weft strands closely interwoven to form a vself-contained body with the substantially in the same plane, and iloat warp strands each passing over a group of successive weft strands, under the next weft strand, over a group comprised by a number of the next successive weit strands, under the yweft strand next following said group, and so on in repeated sequence; the over-passing portions of -said noat warp strands lying directly on the face of said body in contact therewith outside of and, to some extent over, the loops of the body warp strands which lie in said face.

8. A single ply drier felt comprising nonasbestos body warp and weft strands woven together in a plain weave, containing asbestos lying under less'tension than the first named -warp strands over the face of the felt and overlying they body warp strands thereoi','said iioat warp strands having loops at intervals passing betweenbody warp strands and around certain non-adjacent weft strands with which said non-asbestos warp strands are interwoven.

WHLIAMLBARREIL.

weft strands all and iloat warp strands ones of the same body warp strands being interwoven

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