US 2400533 A
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Description (OCR text may contain errors)
May 21, 1946.
M. R. BUFFINGTON METHOD OF MAKING RING TYPE 'PMJKIIKIS Filed June 27, 1940 2 Sheets-Sheet 1 y 1946- M. R.,BUFFINGTON 2,400,533
METHOD OF MAKING RING TYPE PACKINGS Filed June 27, 1940 2 Sheets-SheetZ \luinu aggw (2 2'2 A V Malcolm .22. Buffingtom a; Maia W use leather cups on oil Patented May 21, 1946 rmrnon or Mame also ma memos Malcolm B. Bufilngton, Mlliburn, N. 1.; assignor to Lea Fabrics, Inc.,-Newark, N. 3., a corporation of Delaware Application June '27,
oil cups or ring particularly adapted for use in oil packings are mounted on a travelling valve and form the piston of the pump. More particularly, this invention relates to a method for the manufeature of oil cups or packing rings havin certain improved characteristics by which the efliciency in oil pumping operation is greatly improved.
The frequency with which it has heretofore been necessary to pull the sucker rods and to replace the valve cups because of wear and resulting ineili'cient pumping has been annoyance and considerable difllculty in oil pumping operations. The valve cups heretofore used have the tendency, turn inside out when the pumping unit is withdrawn from the working barrel.
Heretofore it has been common practice to well pumps where the fluid pressure is low because the leather becomes soft and pliable when exposed to the oil and'readily conforms to the contour of the pumping barrel. Such leather cups are manufactured from list pieces of leather and have the tendency to return to their original shape when fluid-pressure is applied to the inside of the cups, and particularly so after the leather has been rendering the leather flabby.
Composition cups which are made from fabric and hard rubber compound have been used to a considerable extent in shallow wells, but cups of this material have not proved satisfactory for the reason that the cups do not readily expand to contact with the walls of the pumping barrel. Attempts have been made to avoid saturation of the fabric with the binder so that the hard rubber compound is only molded through the mesh of the fabric and around the threads, thus avoiding the solid, non-flexible construction. However. even though this gives a more pliable cup than would result from the saturation of the fabric, the threads of the fabric are substantially unprotected and are soon e to the action of oil and water through the abrasion which takes place during the pumping action, causing swelling with oil, or excessive shrinking with water. 1
Despite some of the desirable characteristics of leather and composition cups, neither of these materials as heretofore manufactured completely answers the requirements in actual service. In
addition to the frequency'of flopping, these cups a source of x sed to oil.
1840, Serial No. 342,824
- 2 Claims. (CL 1H3.
furthermore, to flop or form of often crease and by-pass fluid when sand or scale is present.
The most difficult service for cup cups must be very flexible to hold the suction in the pumping barrel and at the same be stiff enough to keep from turning inside out when withdrawn from the pumping barrel into the larger diameter of the tubing.
It is not practical to use soft rubber as a binderin cups intended for use in oil pumps. as they would rapidly deteriorate due to the solvent action of the oil, and furthermore, the friction developed between the cups and the pumping barrel causes rapid deterioration of the cups.
For best performance a valve cup should have enough pliability to adjust itself readily to the barrel and should be sufficiently resilient to avoid v damage when withdrawn from the well. In addition, the cups should have a high resistance to long life, even when exposed to high pressures, and temperatures up flopping and also have a to F.
From an inspection of the period of service a very considerable percentage of the wear on the lip and side wall occurs within a few hours from the time of installation. This is particularly of sand is present in the fluid.
Composition cups are stiff when installed and must be in contact with oil for some time, generally at least a day before they soften sumciently to pick up fluid effectively. If sand is present, theedge of the cup is frequently worn off before this adjustment to the One of the objects of the present invention is to provide a form of valvecup or packing ring which is preformed from a unitary piece of fabric and a binding medium into the shape of the cup or ring prior to the finishing or molding operation sothat the fabric in the finished article is in a natural'or undistorted position, and thereby resists forces tending to produce flopping or to turn the cup or ring inside out. Another object of the valve cup or flexible priming. lip which is adapted to present sufllcicnt contact surface with the barrel surface to pick up fluid immediately and which has a sufficient 'zone or section of straight side wall above the bottom of the inside bevel of the lip as not to interfere with the flexibility of the lip invention is to provide a packings is at depths of from 200 to 1000 feet, because the time must form of cups heretofore employed, it is apparent that after a short true where an appreciable amount barrel can take place.
approximate packing ring having a' of the binding medium to provide the portion but sufflcient to keep sand wiped down until normal side wall contact with the barrel wall is effected.
Another object of the invention is to provide a form of valve cup or packing ring in which less friction is developed during pumping action than in the surface to injure the fabric or toscour increasing the friction.
the barrel wall and v the invention is to provide Another object of a novel method of manufacture of valve cups or packing rings in which a fabric is employed in such a manner as not to weaken or tender the fabric during the manufacturing operation and in which the fabric is employed in a way as to minimize the strain on the fabric in the pumping operation and to resist any force tending to flop the cup or to deflect it from its normal position except that of expansion into contact with the barrel surface.
Another object of the invention is to provide a novel method for the manufacture of valve cups or packing rings in which fabric is employedin a manner to give maximum protection by a binding medium, but permitting the fabric to expand or contract not only diametrically of. the cup or ring, but also longitudinally thereof.
Another object of the invention is to provide a method of manufacture of valve cups or packing rings in which a, suitable binding medium is so proportioned with relation to the intersticesof the fabric employed as to permit molding to size without the formation of excess material during the molding operation, thereby avoiding the necessity of trimming the finished product to size. Another object of the invention is to provide a method of manufacture of valve cups or packing rings in which a fabric is employed in a unitary piece and wound on itself to form the desired shape of the finished product, the fabric being preferably in tapered or stepped form so as to permit winding on a mandrel in substantially tubular form in which the superposedsections form the desired contour of the finished product, and which may be maintained in the desired form by the use of a binding medium having the desired properties.
Another object of the invention is to provide a method for the manufacture of valve cups or packing rings which may be readily varied to give the desired properties for low or medium or high pressure operation, by controlling the character required resiliency and flexibility without sacrifice of other desired characteristics.
Another object of the invention is to provide a combination of a valve cup with a follower ring, in which the ring is adapted to exert pressure upon a sealing ridge of the cup, forcing it against the valve shaft. For this purpose. the follower ring is preferably provided with an edge or surface of less slope than that of the sealing ridge on the valve cup, so that downward pressure of t'he adiacent surface of the follower ring causes inward expansion of the sealing lip or ridge.
With these and other objects in view, the invention comprises various features hereinafter described and defined in the claims annexed hereto. 1
The various features of the invention are illustrated in the accompanying drawings showing the invention in its preferred form and illustrating certain of the method steps employed in carrying out the invention.
Referring more in detail to the drawings:
Fig. 1 is a plan view of a section of fabric of a form ready for applying to a mandrel for the winding operation;
.Fig. 2 is a view in elevation of the mandrel or male portion of the mold showing the start of the winding operation;
Fig. 3 is a plan view of the mold portion and fabric illustrated in Fig. 2; I
Fig. 4 is a view in elevation of the male portion of the mold showing the fabric of Fig. 1 completely wound thereon;
Fig. 5 is a view in elevation of the mold with a valve cup material in place in the mold ready for the molding operation; v
Fig. 618 an enlarged sectional view in elevation of a valve cup;
Fig. 7 is a cross-sectional view in elevation of a form of ring packing embodying the invention;
on which a valve cup is shown in operating position thereon.
In carrying out the invention, a heavy fabric having an open weave is preferably used, such as numbered duck or hose duck. A fabric having about 20 picks to the inch may be used for example, which is suitable for the making of cups to be used at substantially any depth of well.
The fabric is first treated with a synthetic rubber compound in a manner as to thoroughly saturate the threads of the fabric and to fill the fabric mesh from one side of the goods to the other,'whereby the fabric is both coated and imcompletely that by cutting a section therefrom, the cut edge exhibits ,a substantially solid section with no uncoated thread portions showing.
In the making of a valve cup or packing ring of the average size, about four layers of the treated fabric are required to form the desired wall thickness and may consist of about 22 ounces of the binder, or synthetic rubber compound to about 12 ounces of fabric per square yard of the product. After the fabric has been treated by the method as above'described, being thoroughly saturated and the necessary weight of the coated material has been built up with the solution or dispersion of the synthetic rubber material, a molding blank of the approximate size and shape of the valve cup or packing ring to be made is prepared by combining the requisite layers of the treated After the molding blanks are prepared, they are given a heat treatment to partially vulcanize the synthetic rubber and to form a substantially unitary member. The molding blanks are then dipped into a solution or dispersion of the synthetic rubber material and are then dried the built-up blank is continuous,
' can take place in the fabric to cause terial such as those resulting from the of oil or oil and "less friction when moving a ainst a metal surface in contact with oil than natural 9,4 ,osa
to form a continuous film of the synthetic rubber material over the entire surface of the blank. The blank is then entered into a mold and vulcanized into a cup-shaped r ring-shaped article composed of a substantially homogeneous product having a unitary reinforcement enclosed in a casing of synthetic rubber compound which is.
firmly vulcanized to the reinforcement.
It will be understood that in carrying out the details 'of the preferred hereinaftermore fully described, in which there is no overflow in the molding operation, the article can be made with the use of less material than is ordinarily required, and since the fabric formin there is no danger of ply separation as occurs in other builtup composite cups having a plurality of separate layers of fabric. Furthermore, there is no tendency of the cups or rings, in which the layers of fabric are parallel with the valve rod, to flop or turn inside out, as is the case with the product made from fiat discs. It will be understood that in each case the tendency is for the product to return 'to' the original shape of the fabric, and since in the product made in accordance with the method of this invention, the fabric is in the natural or un-stressed condition, it will resist deformation from the cup or ring shape. It is unnecessary, therefore, to depend on strength of the binder to aid in the resistance to flopping, and the only adhesion required between the layers of spirally-wound fabric is that necessary to prevent the friction of pumping from rubhing the layers apart. The binder may therefore be chosen substantially in accordance with its resistance to abrasion, the actual tensile strength and binding power between the layers being a secondary consideration.
A novel feature of the invention is the constructicn of a cup or ring shaped packing which will pick up fluid immediately upon entry into the barrel without interfering with the free entry of the cup or packing ring into the barrel. For this purpose a priming lip is provided which has an external cylindrical portion terminating above the tensile the lower edge. of the bevel at the inner side of the lip portion, thereby giving the desired flexibility but preventing action of sand or other abrasive from cutting or wearing oil the edge or lip portion of the cup or packing ring. Other important features pointed out in connection with the following de-- tailed description of the valvecup or packing ring and the method of making the same.
In carrying out the invention. a Dre-shrunk fabric is preferably employed so that if the fabric becomes exposed to water during use or upon wear of the cup or packing ring, no contraction leakage bc-. tween the cup or packing ring and the wall of the barrel. I
Thefabric is preferably first treated with a suitable cement binder comprising synthetic rubber, such as polymerized chloroprene, reaction products of sodium polysulphide and ethylene dichloride, co-polymers of butadiene and aryiic nitrile or styrene, or other synthetic rubber mapolymerl zation of vinyl compounds, which are resistant against oil and retain their-tensile strength over long periods of time when subjected to the action water. These materials develop soft rubber and retain their valuable physical characteristic! even of the invention will be ably out e biasso as on itself to form under severe stress over lon has been found, moreover, that in contact with oil, or oil and water, synthetic rubber, as Neoprene, for example, absorbs oil to a slight extent upon such exposure which causes a reduction in friction against metal surfaces and assists also in maintaining a proper fit against the working surfaces.
In the treatment of the fabric with the binder material. a solution is preferably employed, such as a solution of Neoprene, which soaks or penetrates into the threads and saturates the fabric with the solution. Any ofv the ordinary rubber solvents, such as toluol for example, may be used for the solution of the synthetic rubber material, as Neoprene, or the binder material. After the fabric has been soaked or properly immersed in the binder solution, solvent is allowed to evaporate and subsequent layers are formed on and in the fabric until the desired wall thickness or weight has been obtained. In the making of the average valve cup, for example, I prefer to deposit four layers of Neoprene upon the fabric, which about 22 ounces of synthetic rubber material to about 12 ounces of the fabric.
In the making of the valve cup or a section of the impregnated fabric is cut packing rins. preferand stretch than that obtainable by cutting the fabric parallel to or at right angles with the warp and a tapered strip is formed of the desired di- I,
mansions for forming the article to be made. The strip may be made. if desired, of, stepped-up sections corresponding ing circumferences tions to be used in of the spirally wound secbuilding up the body of the valve cup or packing ring to be made. The width of the sections is equal to the distance in the mished ring from the top of each convolution to the center hole in the cup or ring, the width being sufficient to provide an upper tapering priming lip, which is beveled inwardly from the outer circumference and an inner lip portion at the mounting hole or center opening of the ring or has been stamped or cut out it isformed into a molding the treated fabric, preferably-by spirally winding the fabric cup.
After the strip 2 into suitable form,
of the finished article desired.- This is preferably accomplished by winding or wrapping the str p upon a mandrel l, the strip being wound with the serrations or stepped-up portions downwardly, serving to form the beveled priming lip portion which is built up of layers of increasing as will be apparent by reference 3 of the drawings. The article is preferably formed to size in a mold I, as shown in Fig. 5 of the drawings. the male portion of the moldcomprising a pin part or mandrel d and a ring part 8 having a beveled portion it of proper slope to form the inwardly beveled priming lip portion 2% of the cup or ring, and a female portion or cavitypart i2, between which the article I4 is pressed and suitably heated tongs-fiend to form the final product of the desired dimensions. Adiacent the priming lip 2c is an enlarged cylindrical portion 2! which terminates above the level of the lower end 23 of the priming lip and provides a reinforcement for the edge 25 of the priming lip and forms a flexible construction permitting the priming lip to adiust itself into contact with the working surface or barrel.
periods of time. It
is equivalent to to the lengths of the succeedconvolutionsof the dimensions mold member the cup or ring thus .The layers of synthetic rubber applied to the fabric are'combined with suitable vulcanizing ingredients which are preferably supplied by incorporating the same in a solution of synthetic rubber, as Neoprene, so that when the required heat for vulcanization is applied to the mold, the product will be vulcanized, thus uniting the spirally applied layers of the fabric and forming a unitary mass in which a single section or unit of fabric is imbedded in substantially undistorted form, thereby resisting deformation or flopping thereof when in use or when withdrawn from the pumping barrel.
The mandrel or pin portion 4 of the mold is referably provided with a beveled shoulder portion I6 extending downwardly and inwardly so as to form an inner lip portion i8, forming a sealing ridge to take up the compression of the follower ring when in use and to seal the ridge portion of the cup against the valve body 'or immediately adjacent cylindrical surface contacting with the sealing ridge. As hereinafter described, the follower ring has an end surface which is flat or of less slope than the corresponding surface of the adjacent sealing ridge, so that by pressure of the follower ring against the ridge, the ridge body is brought into contact with the'adlacent cylindrical wall of the valve shaft or valve body. thus preventing leakage of oil between the flange of the packing and the said wall, or along the shaft. a
In assembling the mold, the blank or skeleton form to be molded is slipped over the section of the pin or mandrel 4 on which the ring member 8 is mounted and the female member l2 of the mold is then put into place over the blank and the pin portion. 'By the time that the bottom 22 of the circular or substantially cylindrical blank has contacted with the shoulder portion 24 of the i2, the portion 26 of the female member l2 has passed the. beveled portion ID of the ring member 8, thus entirely confining the blank in the mold before it is subjected to any pressure in the molding operation. By continuing the pressure after the mold is closed, the layers of the, fabric at the bottom 22 of the cup or ring are compressed. and the cup or ring is subjected to pressure as a whole so that the cup or ring is accurately molded to size during the molding operation.
It will be understood that prior to the molding operation, the blank is preferably coated with a film of the synthetic rubber material by dipping the blank into a bath or solution of Neoprene or synthetic rubber containing the necessary vulcanizing ingredients and the fiun is suitably dried before being entered into the mold.
In the molding operation, the pressureof the mold causes the fabric plies and the threads of the fabric to compress or come closer together, forcing the plastic material which is between the threads to the outersurface of the article, but without forcing the material which has been absorbed by the threads out of the threads themselves. Since the threads of the fabric are held in the compressed state until the vulcanization of the. synthetic rubber compound is complete, made will expand properly under pressure not only diametrically of the cup or ring, but also longitudinally thereof, or axially of the cup or ring.
-It will be understood that by the use of a fabv orating effect.
' Parts by weight Neoprene 100 Carbon black 40 Zinc oxide 5 Magnesium oxicle 4 Neozone D, anti-oxidant 2 Cottonseed oil n 5 This compound when vulcanized andtested in a solid slab will show about 70 hardness by the Shore hardness gauge, and it is found that a hardness varying from about 55 to produced by varying the above composition is well suited for the production of cups by the method of the invention for use in wells up to about 1000 feet depth.
In general, soft cups may be used in wells of a depth up to about 1200 feet, in which the-pres sure varies up to about 600 pounds per square inch. Cups of medium hardness may-be used in wells of a depth from about 1200 feet to about 2500 feet, in which the pressure varies from about 600 to 1250 pounds per squareinch. Such cups may be made by the method of the invention by the use of the above composition for soft cups together with an amount of'composition for the making of hard rubber, the amount depending upon the degree of hardness to be proare to be used in wells having a depth of over 2500 to some extent to modify the properties-of the and rings.
For this purpose, the fabric is first treated with a methyl peratures in deep wells, it would have no deteriably impregnated with the methyl cellulose ma- After the fabric has been suit-.
impregnated and coated with a cement composition as above, including Neoprene, but with the addition of a hard rubber composition, the amount of which may be varied as will be understood, in order to obtain the particular properties desired. The Neoprene and hard rubber compositions 'may be added in substantially equal amounts, for example, for the production of a hard cup, the coating and other method steps as above described, being otherwise the same.
The use of the methyl cellulose with the harder compositions renders the cup or ring more flexible than it would otherwise be with this composition by resisting the penetration of the binder composition into the fibres of the threads, by which the fabric layers are united by thin layers of the hard rubber composition on each side of the fabric which in turn are united by small pins of the hard rubber composition passing through the meshes of thefabric forming a unitary relatively flexible structure.
In place Of the methyl .cellulose, or in addition thereto, if desired, I may use a suitable resin, such for example as a water soluble ureaformaldehyde resin, the fabric being impregnated in substantially the same way as has been described in connection with the use of methyl cellulose and dried to impregnate the fibres of the threads without filling or closing the meshes of the fabric. The urea-formaldehyde resin is thermosetting at the temperatures used for the vulcanization of the synthetic rubber or binder composition, the reaction proceeding rapidly so that the fabric becomes relatively stiff immediately and forms a supportfor the cup or ring and prevents the forming or crowding of wrinkles into the sidewall of the article during the molding operation. By the use of a synthetic resin in this way, fabrics having a more open weave and greater flexibility may be employed so that the pins of hard rubber composition passing through the meshes of the fabric to unite the adjacent films or layers of the binder composition may be larger. thus producing a more resistant structure.
After the treatment of the fabric with methyl cellulose or a soluble resin, or both, in the manner above described, the fabric is treated with the synthetic rubber composition or binder preferably with an amount per square yard equal substantially to-the weight of the fabric to be coated or impregnated. It will be understood that the priming lip and the sealing ridge,'as above described are employed on the soft, medium and hard cups, and that the dimensions may vary as will be apparent to those skilled in the art.
In a cup of a diameter of 1 inches, for example, the lip portion 20 of the cup extends inwardly and downwardly to a distance of about 5 inches vertically below the top 25 of the'lip. On the outside of the cup at the lip portion is an enlarged cylindrical portion 2! which extends vertically down on the outside of the cup for a distance of about %2 of an inch, instead of immediately tapering infrom the top of the lip; and terminates above the lower inside edge 23 of the lip portion then merging with the main body portion of the cup which extends downwardly for a distance of about of an inch, which main body has a taper of about .05 to the inch. The lower portion or shoulder portion 21 of the cup then curves inwardly in a rounded curve to the under portion 22 of the cup as shown in Fig. 6 of the drawings, or extends inwardly with a beveled portion in the manner shown in Fig. 'l of the drawings. The diameter of. the main inner surface of the cup may be about 1% inches, said inner surface extending inch. and then merges with the sealing ridge l8 or shoulder which is formed at the upper portion of the lower ring member which has a diameter of about 1% of an inch, as indicated in Fig. 6 of the drawings. The sealing ridge l8 preferably extends inwardly and upwardly at the shoulder portion and may have a taper substantially the. same as that of the priming lip, although the taper may be varied asdesircd, as will be apparent to those skilled in the art.
In Fig. '7 of the drawings is shown a preferred form of ring packing made in accordance with the method of the invention so as to include a unitary section of fabric the spirally formed layers of which reinforce each other and are impregnated with synthetic rubber composition in the manner as above described, the composition depending upon the depth of well in which the packing ring is to be used. It will be noted that the packing ring includes a priming lip member 20' and has a cylindrical portion indicated at 2 i which extends downwardly from the upper edge of the lip portion but terminates above the lower edge '23 of the lip portion so as to render the lip flexible but without presenting a sharp outer edge at an angle of about 51', as indicated, so that the rings may be readily nested.
In Fig. 8 is shown a reverse-beveled cup which is similar to that shown in Fig. 6 of the drawings except that the priming lip 20" instead of sloping downwardly in an inward direction from the out- .er edge, slopes upwardly and inwardly. This form of cup may be used to pack ed the standing valve in the bottom of the pumping barrel. This form of cup may also be used on certain types of traveling valves. In this case the top of the follower rlng may be provided with a hood which fitsover the reverse-bevel. A hole drilled in the hood allows thefiuid to pass to the inside of the cup, thereby permitting the packing to expand wall and the contact surface is relatively small as compared with that of the standard cup. The priming lip it of the form as shown in Fig. 6 of the drawings'may therefore be omitted in this form of cup for the purposes above indicated. The sealing ridge it" is of special importance however in this type of valve cup in order to prevent leakage between the cup and the valve shaft.
It will be understood that various changes or modifications may be made in the method of the invention as above described and also in the article of manufacture of the forms as shown in the drawings without departing from the spirit or scope of the invention as defined in the claims.
Having thus described the invention what is claimed as new is: i Y
1. A method for the manufacture of a cup substantially packing which comprises saturating a fabric with with a vulcanizable rubber cement composition containing synthetic rubber and hard rubberforming ingredients so as to fully saturate the said treated fabric, placing the said impregnated reinforcing member in a mold and vulcanizing the said rubber composition under heat and pressure to form a body portion having a central opening, a base portion having an inwardly extending flange of less diameter than said body portion, an upwardly extending sealing ridge at the inner periphery of the said flange sloping outwardly and downwardly from the apogee thereof and a priming lip at the said beveled top surface having an outer reinforcing cylindrical portion terminating within the limits of the zone of the said beveled top surface.
2. A method for the manufacture of a cup packing which comprises saturating an open mesh fabric with a methyl cellulose solution of about two percent strength, drying the treated fabric,
' forming the fabric into reinforcing layers of a hollow generally cylindrical reinforcing member 7 having an inwardly and downwardly extending nated reinforcing member in a mold of a form adapted to form the said reinforcing member into the desired final form having a body portion with a central opening, an upper priming lip having an inwardly downwardly beveled surface and an external reinforcing cylindrical portion within the zone of the priming lip,
ing ridge extending upwardly from the inner periphery of the said flange and beveled outwardly and downwardly from the apogee of the said ridge so as to cause sealing engagement with the adjacent cylindrical surface by the pressure of a follower ring against the said beveled sealing ridge, and vulcanizlng the said rubber composition under heat and pressure.
MALCOLM R. BUFFINGTON.
a base portion having an inwardly extending flange and a seal-