US3157983A - Method for the manufacture of stuffing box packings - Google Patents

Description

R. RADKE Nov. 24, 1964 METHOD FOR THE MANUFACTURE OF STUFFING BOX PACKINGS Filed Aug. 18, 1958 PREPAREA MlXTUREOF FIBERS/4ND LUBRKCATINGSUUDS ENVELOP FIBERS WlTH LUBRICATINGSOUDS FORM PAPER-LIKE FOILS DRY FOILS AND DEVIL INTO ENVELOPE!) FIBERS SPIN INTO A ROVlNG MAKE STUFFING BOX PACKING INVENTOR RudolfRadife BY /6W d 5 ATTORNEYS United States Patent 3,157,583 METHOD FQR THE MANUFAtIIURE 9F STUEFRNG BGX PACKlNGS Rudolf Baillie, 53 Schwalbenschwanz,Frankfurt am l t lain, Eschersheim, Qerinany Filed 18, 195 3, Ser. No. 755,456 '7 Claims. 57-464) The present invention relates to a method for the production of stuffing box packings and to stufiin box packings manufactured according to this method.

In general, stufiing box packings are made of fibers in combination with solids having lubricating properties, and preferably also with bonding agents and with lubricants having a consistency which varies between the liquid and the semi-solid, such as waxes, fats and oils.

It has been suggested to manufacture stuffing box packings of the above type by spinning fibrous materials, such as abestos, into yarns and coiling these yarns into reels, preferably in such a manner that the yarn windings of each separate layer are crossed with windings of the preceding separate layer on the reel. These reels are then impregnated with the bonding agent, e.g. with natural or synthetic rubber, and a solid lubricant, e.g. graphite, is applied.

It has also been suggested to wind sleeve-shaped stufiing-bo-x packings from a paper-like fibrous sheet or fiber fleece and then apply the solid lubricant to the same after impregnation thereof, preferably with a bonding agent such as a glue or rubber solution.

The graphited sleeves are pressed in a tool to shorten the height. The die in the tool has a smooth inner surface and a smooth outer surface which form smooth surfaces on the stuffing box packing which is pressed against the inner and outer surfaces of the die. The stufiing box packing is made firm by the pressing. Due to the previous graphiting the whole surface is thereby coated with a thin film of graphite.

Such packings, which generally have a base of glued paper, are not particularly resistant against steam or water and other liquids.

The thin film of graphite on the surface wears 0E after a relatively short time, and the exposed dry fibers will then cause very considerable friction.

For these reasons the useful life of such packings is often very short and they are of poor quality.

According to other methods, thin plastic or rubber bonded fibrous foils containing some added graphite have been manufactured on calenders. But for technical reasons in the production thereof the proportion of graphite should in general not exceed 28% and in no case 50%. Rolled stuffing box packings made in this manner are rather hard and do not possess good sliding properties due to the comparatively low graphite content.

Finally, stufiing box packings are known which are plaited from threads such as artificial silk, or made from fabrics woven of such threads. The artifical silk threads are produced by mixing colloidal graphite into a viscose solution or into a melt of the material which is to be drawn into yarn; the graphite is then forced out of the spinning nozzle together with the material. Thus the threads of this type which were discharged from the nozzle into the precipitation bath or were formed when the melt was setting, consisted of a uniform mixture of artificial silk and of graphite finely distributed throughout each fiber. Now although these graphite fibers, when used as components of stuffing box packings, have a certain lubricant effect, they are still very imperfect, since the amount of graphite is too small and the graphite is not present predominately on the outside of the fibers, and also not in the form of minute flakes. It has also Hce been found that the impregnation of all stuffing box packings known so far, whether they consist of yarns, woven, knitted or plaited textile fabrics, or of paper-like foils or fleeces deteriorated rapidly, since in these materials the graphite is present merely on the surface of the threads or foils but not inside thereof.

The novel feature of the present method for the manufacture of stufiing box packings consisting of fibrous yarns and lubricating solids is the application of the solid lubricant to the fibers used in the manufacture of the yarn such that every single fiber is completely enveloped thereby. These fibers are then spun into yarns and the packing is manufactured in the usual manner preferably by ordinary textile process.

This method can be based on fibers of many different types, i.e. both on organic fibers such as cotton, wool, silk, artifi ial silk, polytetratluorethylene, polyamide, etc., and on inorganic fibers such as asbestos, glass, quartz, slag and mineral wool etc.

The lubricant used is primarily graphite; but other lubricant additives in powder form, such as mica, talc, molybdenum disulphide and the like can also be used, also certain metal powders-such as lead, copper, tin, aluminum and zinc.

The method is performed by adding the lubricating solids, e.g. graphite, during the processing of the individual fibers such that before the spinning of a yarn the fibers are completely enveloped by the lubricant. The graphite or other solids will therefore actually be added to the fibrous materials not later than on the card.

A bonding agent is in most cases used at the same time. Various types of such agents can be used, e.g. organic or inorganic adhesives. Particularly suitable are natural and synthetic rubbers such as polymers and copolymers of isobutylene, ethylene, styrene and their homologues, polyvinyl chloride, polyvinyl ether, polyvinyl acetate, polyvinyl alcohols, polyacrylic nitriles, polyacrylic esters, polyacrylic amides, polyurethanes, polymers of adipic acid and their derivatives; isocyanates, polyesters, terepthalic acid reins, halogenated plastics, especially those containing fluorine; phenol, cresol and other condensation resins, silicone resins and rubbers; animal, vegetable and synthetic glues; inorganic bonding agents such as water glass and the like, or mixtures or copolymerizates of these substances.

All these bonding materials may be used in various forms, as liquids, in plastic form, as solutions, emulsions, latices and suspensions. In these forms the agents are applied to the fibers, if necessary, together with a coag ulant, such as an acid, a salt with an acid reaction or any other electrolyte. f a rubber latex is used together with asbestos, no coagulants are in general required.

The solid substances can be applied in various ways to the fibers, such as by dipping the fibers, which then must not yet have been spun into yarns, into a solution or dispersion of a bonding agent, or by stirring or scattering the loose fibers into a dispersion or a solution of the agent together With the solid lubricant. The entire mixture is then thoroughly worked, and the bonding agent is precipitated on the fiber by coagulation together with the solid lubricant; the substance is then dried, unravelled and spun in the usual manner.

The primary material for the production of the yarn can also be obtained by brushing or spraying such a liquid or solution on the dried fibrous material not later than when on the card, after which the solid lubricants are applied, or by immersing, brushing or spraying on mixtures ofthe solutions containing the bonding agent or dispenrsions with the finely dstributed solid lubricants. In each case the solids are applied either after the individual fibers have been coated with the bonding a ents,

or the solids and the bonding agents are applied together. If the solids are applied after the bonding agents they may either be sprayed on or applied electrostatically.

After each single fiber has been coated with the solids as described above and preferably also with the bonding agents, they are spun into yarn in the usual manner.

If the solid lubricants adhere to the fibers by themselves the use of bonding agents is not necessary.

For another method of the production of such yarns the individual fibers and the lubricating solids, preferably together with the bonding agents, are mixed together to form a pulp such as is used in the manufacture of paper. This pulp is then processed so as to give paperlike sheets or fleeces, which are then cut into narrow strips and twisted together (similar to paper string) so that yarn-like threads are obtained which are then treated in the same way as described above to form packings.

This subsequent treatment can be carried out in a variety of ways: either by producing reels having layers of yarn windings, wherein the windings of each layer are crossed with the windings of the preceding layer to make them strong enough; or, as in the manufacture of textiles, by producing woven, knitted or plaited fabrics having a width roughly equal to the axial length of the packing required which are then rolled up to give the packings required. Alternatively, wider fabrics can be made which are then cut up into widths of the required size.

The threads can also be plaited or laced around a former to a suflicient thickness to obtain a packing.

It is also possible to wind a long thread of the type described above around the metal former to be packed, thus building up the packing at the point at which it is required.

These and other objects of this invention will bea come more apparent upon consideration of the following description taken together with the following drawings diagrammatically showing some of the packing embodiments and in which:

FIGURE 1 is a flow chart of one mode of this invention.

FIGURES 2 and 3 show a packing wound of individual layers of yarn to form a coil, in section and in plan with parts thereof cut away;

FIGURE 4 shows a packing produced by rolling up a woven or knitted fabric;

FIGURE 5 shows how the material can be plaited around a former to provide a packing, and

FIGURE 6 shows how a single long thread of the the type described above is wound around a shaft in order to produce a packing where it is required.

In FIGURES 2 and 3 the packing is built up of a number of layers 1 and 2 of yarns; the direction of the threads 3 and 4 of two adjacent layers of yarn are opposite such that the threads cross each other thereby giving the reel greater strength. In FIGURE 4, woven or knitted fabric 6 is rolled on a former forming a packing 5. In FIGURE 5, a thread 8 or slightly wider braids made from such threads are plaited to form a fabric which is then wound onto the former 15. The reel 7 so produced is then removed from the former and can be used as packing. FIGURE 6 shows how a long thread 9 is wound on a shaft 10 whose diameter at 12 is slightly larger than at 13. Winding of the thread commences at the shoulder 11 and is continued until the diameter of the reel is approximately the same as that of the shaft at 12.

This characteristic of the invention of enveloping practically all fibers individually with the solid lubricant enables a large quantity of the later to be introduced into the stuffing box packing. With conventional methods, in which yarns, fabrics or foils were coated with lubricating additives only on the outside, eg with graphite, not more than to by volume of these solid additives could be incorporated into the stuffing box packing; with the present method, on the other hand, up to by volume can be incorporated into the packing in such a manner that these lubricating solids are uniformly distributed over the entire cross section of the packing. As a result the packing contains a very high proportion of these solid lubricants which are not so easily washed or worn out.

Many of these solid lubricants are in the form of small flakes with a characteristic crystal latice associated with a particularly low coefiicient of friction. Other additives, such as lead, aluminium or copper in powder form are mostly so soft that they very soon assume this shape of small flakes in operation, thereby again providing very good friction characteristics.

The packings can also be treated with certain chemicals if particular properties are required, eg to improve the resistance against very cold or very hot fluids such as ordinary water, boiler feed water, or sea water; against acids, lyes, salt solutions; against inorganic and organic solvents and their mixtures, oils and gases; against food stuffs, medicines etc. Particularly suitable for use as such additives are silicones and synthetic oils and rubbers containing fluorine, but in general any of the substances mentioned above as bonding agents can be used for this purpose. These and other substances can either be incorporated with the fibers or they can be applied to the packings in the form of solutions, melts, emulsions or suspensions. In the same way fats can be added to the yarn or the packings, or the packings can be fat impregnated in the known manner.

Example I Spun fibers made of asbestos or other fibrous raw material are processed in a quantity of about 60%, with 35% powdered graphite and 5% natural rubber latex (measured dry) in a pulp engine in the usual paper making manner, i.e. with about 50 times as much water added; the fibers will then be enveloped with the graphite. The actual amount of water may differ according to the condition of the fibers. Basically the amount of water shall be about 10 to times the amount of solids and shall increase as the proportion of fibers in the mixture increases.

In order to improve the adhesion of the graphite to the fibers the latex can be coagulated by the addition of a trace of acid. The mixture is then made into paper-like foils on the endless wire or the board machine; after drying these are cut up into fibers by means of a deviling machnie or similar appliance. This gives individual fibers each of which is completely enclosed in graphite.

These fibers which are completely enclosed in graphite are then processed in the manner usually in the textile industry to be made into threads. First they are oriented on the card in the usual manner to obtain a roving, then they are spun by being rotated on a spinning machine and finally doubled on a twining machine. The threads so produced are completely saturated with graphite and can be made into stufiing box packings by plaiting on a plaiting or lacing machine or by weaving, knitting and final process of the woven, knitted or plaited fabrics in the usual manner.

Example 2 10 parts of cotton fibers are mixed with a suspension containing 87 parts of graphite and such an amount of a 20% solution of acrylonitrile in dimethyl formamide that the dry components of acrylonitrile weigh about 3 parts. Inorder to achieve proper mixing the suspension consisting of the graphite and the acrylonitrile solution is added to the fibers while the latter are moving over heated surfaces. This will evaporate the solvent leaving individual fibers completely enclosed in graphite which are then processed in the manner usual in the textile industry as described in Example 1. The ratio of (cotton fibers-i-bonding agent): graphite is about 23:77 by volume.

Example 3 Abestos spining fibers are processed in the usual manner on a card or a double card. The corresponding lap is treated with a graphite suspension consisting of 95 parts by weight of graphite and 100 parts by weight of a 5% neoprene latex in such manner that all fibers are completely enclosed in graphite which requires a ratio of about 80 parts by volume of graphite to 20 parts by volume of asbestos and bonding agent. Then the dispersion agent is removed by heating, and the graphite fiber lap is processed in the usual manner to give a roving which is made into a packing by weaving, knitting, plaiting or just by winding it on a mandrel or a shaft.

Example 4 Loose asbestos spinning fibers are sprayed with a solution of nitrocellulose in amyl acetate such that the quantity ratio of asbestos to solvent-free nitrocellulose solution is 98:2. Then a mixture of approximately equal parts of talc and mica is applied according to an electrostatic flaking method in such a manner that every single fiber is completely enclosed; this must be done as soon as possible after the nitrocellulose solution has been applied so that the fibers are still sticky. In this manner such a quantity of the talc-mica mixture is applied as will produce a ratio of 70 parts by volume of talc and mica to 30 parts by volume of fibers and bonding agent.

Example 5 8 parts by weight of cellulose staple fibers about 30 to 80 millimeters long are suspended in water in a pulp machine in the usual manner, and 90 parts by Weight of natural graphite containing 98 to 99% of carbon are added. The amount of water should be about 20 to 50 times the amount of fibers. Then a quantity of natural rubber latex corresponding approximately to two parts of the dry substance is added, and finally a coagulant, e.g. a weak acid or alum. These chemicals precipitate the rubber and the graphite onto the fibers in such a way that the mixture can be processed to give a homogeneous fiber fleece. After it has been dried this fleece is cut up in a deviling machine; the fibers are then made into a sliver on the card and finally into a yarn on a spinning machine. A woven or knitted fabric can be produced from such yarns which can be turned into stutling box packings. In these packings the ratio by volume of (fibers and bonding agent) to graphite is about 15 to 85.

Example 6 Into a solution of 3 parts of polyvinyl acetate (referred to as the dry material) in amyl acetate are stirred one after the other the following: 10 parts of molybdenum disulphide, 75 parts of fine lead dust and parts of chrysotyl asbestos fibers.

The substance is dried by evaporating the solvent. Any large lumps which may have formed are cut up in a deviling machine; the material is then processed so that the fibers are made into a sliver in the same manner as given in Example 5. The ratio by volume is about 54 parts of fibers and bonding agent to 46 parts of lead and molybdenum disulphide.

It is understood that the methods described above for enclosing the individual fibers in solid substances, applying the bonding agents and solids, processing of the individual fibers to give yarns and processing the yarns to give finished packings are only mentioned here as examples of the present invention but are not intended to limit the scope of the invention in any way. The amount of protection for the invention is to be described by the following claims.

I claim:

1. In a process for producing stuffing box packings made up of oriented fibers formed into yarns and solids having lubricating properties on said fibers, the steps which comprise preparing a mixture including staple fibers and lubricating solids in small flake form, the Volume of the solids being at least 30% of the fibers and solids combined, forming a paper-like foil of the mixture and drying the foil, deviling the foil to form individual fibers, subsequently carding the fibers to form a sliver, intertwining the sliver into a yarn and forming the packing from said yarn in a suitable manner, whereby every individual fiber is substantially completely enveloped by the solids.

2. The process of claim 1 wherein an adhesive binding agent is added in the step of preparing the mixture.

3. The process of claim 1 wherein the staple fibers are asbestos fibers.

4. The process of claim 1 wherein the staple fibers are cot-ton fibers.

5. The process of claim 1 wherein the staple fibers are cellulose staple fibers.

6. The process of claim 1 wherein the staple fibers are glass fibers.

7. The process of claim 1 wherein the staple fibers are mineral wool fibers.

References (Jilted in the file of this patent UNITED STATES PATENTS 267,537 Johns Nov. 14, 1882 862,899 Garlock Aug. 13, 1907 926,996 Morris July 6, 1909' 951,827 Miller Mar. 15, 1910 1,256,881 Deventer Feb. 19, 1918 1,608,165 Brown et al. Nov. 23,1926 1,982,381 Hayes-Gratze Nov. 27, 1934 2,099,242 Stewart Nov. 16, 1937 2,134,324 Brackett Oct. 25, 1938 2,210,004 Rautenstrauch Aug. 6, 1940 2,301,998 Berstein et al. Nov. 17, 1942 2,404,952 Fiechter July 30, 1946 2,667,684 Boyer et a1. Feb. 2, 1954 2,743,511 Genovese May 1, 1956

Claims (1)

1. IN A PROCESS FOR PRODUCING STUFFING BOX PACKINGS MADE UP OF ORIENTED FIBERS FORMED INTO YARNS AND SOLIDS HAVING LUBRICATING PROPERTIES ON SAID FIBERS, THE STEPS WHICH COMPRISE PREPARING A MIXTURE INCLUDING STAPLE FIBERS AND LUBRICATING SOLIDS IN SMALL FLAKE FROM, THE VOLUME OF THE SOLIDS BEING AT LEAST 30% OF THE FIBERS AND SOLIDS COMBINED, FORMING A PAPER-LIKE FOIL OF THE MIXTURE AND DRYING THE FOIL, DEVILING THE FOIL TO FORM INDIVIDUAL FIBERS, SUBSEQUENTLY CARDING THE FIBERS TO FORM A SILVER, INTERTWINING THE SILVER INTO A YARN AND FORMING THE PACKING FROM SAID YARN IN SUITABLE MANNER, WHEREBY EVERY INDIVIDUAL FIBER IS SUBSTNATIALLY COMPLETELY ENVELOPED BY THE SOLIDS.

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