United States Patent [19]
`Watkins (cid:9)
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`
`US005253946A
`[11] Patent Number: (cid:9)
`[45] Date of Patent: (cid:9)
`
`5,253,946
`Oct. 19, 1993
`
`[54] SUCKER ROD END FITTING
`[75] Inventor: Damon L. Watkins, Levelland, Tex.
`[73] Assignee: Dover Resources, Inc., Tulsa, Okla.
`[21] Appl. No.: 886,525
`[22] Filed: (cid:9)
`May 20, 1992
`[51] Int. C1.5 (cid:9)
`[52] U.S. Cl. (cid:9)
`[58] Field of Search (cid:9)
`
` F16B 11/00
`403/268; 403/265
` 403/268, 265, 269, 332,
`403/334, 369, 404, 409.1, 179
`References Cited
`U.S. PATENT DOCUMENTS
`
`Re. 32,865 2/1989 Rutledge, Jr. et al. (cid:9)
`2,246,568 6/1941 Berliner (cid:9)
`
`3,540,763 11/1970 Yee (cid:9)
`
`3,698,749 10/1972 Yonkers (cid:9)
`
`4,360,288 11/1982 Rutledge, Jr. et al. (cid:9)
`
`4,401,396 8/1983 McKay (cid:9)
`
`4,430,018 2/1984 Fischer (cid:9)
`
`4,433,933 2/1984 Parsons, Jr. et al. (cid:9)
`
`4,475,839 10/1984 Strandberg (cid:9)
`
`
`[56] (cid:9)
`
`403/268
`403/334
`403/265
`403/334
`403/268
`403/13
`403/268
`403/268
`403/2
`
` 403/266
` 403/265
` 403/268
` 403/369
` 403/370
` 403/268
` 403/268
` 405/260
`
`4,585,368 4/1986 Pagan (cid:9)
`4,662,774 5/1987 Morrow (cid:9)
`4,683,953 3/1987 Anderson et al. (cid:9)
`4,691,791 9/1987 Fillet (cid:9)
`4,787,771 11/1988 Allen (cid:9)
`4,822,201 4/1989 Iwasaki et al. (cid:9)
`4,919,560 4/1990 Rutledge, Jr. et al. (cid:9)
`4,958,961 9/1990 Herbet et al. (cid:9)
`Primary Examiner—Randolph A. Reese
`Assistant Examiner—Anthony Knight
`Attorney, Agent, or Firm—Head & Johnson
`ABSTRACT
`[57] (cid:9)
`A connector to secure to the end of a cylindrical rod or
`cylindrical wire. The connector includes an elongated
`body having a receptacle with a cylindrical wall. A
`plurality of axially aligned tapered annuluses, coaxial
`with the receptacle, extend from the cylindrical wall
`into the body. Each annulus has a cross-section tangen-
`tially approaching the cylindrical wall at one end and an
`arcuate opposite end.
`
`7 Claims, 2 Drawing Sheets
`
`Petitioners' Exhibit 1009
`John Crane v. Finalrod
`IPR2016-01827
`Page 1 of 6
`
`(cid:9)
`

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`U.S. Patent (cid:9)
`
`Oct. 19, 1993 (cid:9)
`
`Sheet 1 of 2 (cid:9)
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`5,253,946
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`Fig. f
`( PRIOR ART)
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`Fig.3
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`Page 2 of 6
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`

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`U.S. Patent (cid:9)
`
`Oct. 19, 1993 (cid:9)
`
`Sheet 2 of 2 (cid:9)
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`5,253,946
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`•
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`42
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`40
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`32
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`34
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`36
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`38
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`41
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`4.
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`?1,
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`30
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`44
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`20
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`Fig. 7
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`Fig. 2
`(PRIOR ART)
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`Fig. 4
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`Fig. 6
`(PRIOR ART)
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`Page 3 of 6
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`1
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`SUCKER ROD END FITTING
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`5,253,946
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`10
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`15
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`20
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`25
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`along the annulus and eliminate the concentration of
`shear stress at a particular point in the annulus.
`It is, therefore, a principal object and purpose of the
`present invention to provide an end fitting for a cylin-
`drical rod or cylindrical wire that will spread out the
`force of compression along the adhesive and rod within
`the receptacle of the end fitting.
`SUMMARY OF THE INVENTION
`The present invention provides an improved end
`connector to attach to the end of a cylindrical rod or
`cylindrical wire to act as an end fitting. The connector
`may be connected to another connector so that the rods
`or wires may be connected in end-to-end relationship.
`The connector incudes an elongated body having a
`cylindrical receptacle. A series of tapered annuluses are
`axially aligned with each other and are coaxial with the
`cylindrical receptacle. The shape of each annulus is
`radial rather than straight.
`Each annulus has a cross-section having a pair of
`opposed ends. One end tangentially approaches the
`cylindrical wall. The opposite end is arcuate about a
`center point along an imaginary line which is perpen-
`dicular to the cylindrical wall of the receptacle.
`The design of the annulus results in a more gradual
`change in the amount of compressive force between the
`rod and end fitting from no compressive force to full
`compression.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 discloses a connector or end fitting for a cylin-
`drical rod or cylindrical wire which is partially cut
`away;
`FIG. 2 illustrates an enlarged view taken along the
`circular section line 2-2 of FIG. 1;
`FIG. 3 illustrates an end fitting constructed in accor-
`dance with the present invention;
`FIG. 4 illustrates a connector as shown in FIG. 3
`with the cylindrical rod inserted and adhesive affixed to
`the rod;
`FIG. 5 illustrates a line showing the design of the
`connector shown in FIG. 3;
`FIG. 6 illustrates an outline of a wedge-shaped annu-
`lus in the prior art;
`FIG. 7 illustrates an outline of an annulus for a con-
`nector of the present invention.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`Referring to the drawings in detail, FIG. 1 illustrates
`a partial cross-section of a cylindrical rod 10 which may
`be composed of a fiber reinforced synthetic resin such
`as fiberglass or other lightweight material. The fiber-
`glass rods 10 are connected in end-to-end relationship to
`form a string through use of connectors such as connec-
`tor 12. The connector 12 typically contains an elon-
`gated body having a cylindrical receptacle 14. The
`receptacle includes a series of wedge-shaped annuluses
`16 which are coaxial with the axis of the cylindrical
`receptacle. The annuluses 16 extend into the body and
`are wedge-shaped in cross-section.
`In order to secure the cylindrical rod 10 to the con-
`nector 12, a quantity of adhesive, which is initially in a
`flowable state, is placed in the receptacle 14. The rod is
`then inserted into the receptacle. The adhesive will fill
`each of the wedge-shaped annuluses. The adhesive will
`cure to a solid and adhere to the rod.
`
`BACKGROUND OF THE INVENTION
`I. Field of the Invention
`The present invention relates to a connector device to
`connect the end of a cylindrical rod or a cylindrical
`wire. In particular, the present invention relates to a
`connector to connect the end of the cylindrical rod or
`wire so that the rods or wires are connected therein in
`end-to-end relationship.
`2. Prior Art
`The use of cylindrical or sucker rods is well known in
`underground wells to actuate a pump located in an
`underground well bore of a well. A series of sucker rods
`connected together in end-to-end relationship forms a
`string which extends down into the well hole. The
`string is connected to a pump at one end and to a recip-
`rocating mechanism at the surface or well head in order
`to actuate the pump.
`While at one time steel sucker rods were common,
`synthetic materials, such as fiberglass or other synthetic
`resins are being increasingly used. Fiberglass rods are
`advantageous because they are lighter than metal, with-
`stand corrosive effects better than metal and have
`greater elasticity than metal.
`The individual rods are connected together by metal
`connectors which are generally elongated members
`having an axial receptacle. The connector will typically
`have an opposite threaded end so that a pair of connec-
`tors may be secured together. The sucker rod may be
`connected to the connector through use of an adhesive
`which will bond to the rod.
`Various designs have been suggested to produce a
`good bond and attachment between the rod and the end
`fitting.
`Prior designs include Anderson et al. (U.S. Pat. No.
`4,653,953), Parsons et al. (U.S. Pat. No. 4,433,933) and
`McKay (U.S. Pat. No. 4,401,396). A series of wedge or
`partial cone-shaped recesses extend from the receptacle
`into the body of the connector.
`In order to make the attachment, an initially flowable
`adhesive is placed in the receptacle of the connector. A
`rod is then inserted into the receptacle, the adhesive fills
`the void space in the wedges or partial cone-shaped
`cuts. The adhesive will cure becoming a solid and will
`adhere to the rod. The solid adhesive is bonded to the
`rod and not to the inside of the metal connector.
`When the assembled rod is pulled in tension in its
`threaded ends, the solid adhesive wedges bonded to the
`rod press against and force against the annular wedges.
`Slippage which occurs between the rod body and the
`end fitting causes the larger end of the adhesive wedge
`to separate from the surface of the metal leaving a slight
`gap. (cid:9)
`A compressive force is imparted to the rod itself as
`the metal connector and the adhesive wedge press
`against each other to resist any further slippage. This
`force of compression is applied across the entire interval
`where the adhesive wedge and the metal surface 60
`contact. No compression force is applied in the segment
`adjacent the gap.
`The abrupt change at the end of the gap from no
`compression to full, heavy compression results in a
`concentration of shear stress at that point, leading to the 65
`possibility of failure in the rod.
`Accordingly, there exists a need to design a wedge or
`annulus that will spread out the force of compression
`
`50
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`55
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`Page 4 of 6
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`5,253,946
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`4
`limits the strength and durability of cylindrical rods
`with the prior art design.
`FIG. 4 illustrates the present invention connector or
`end fitting 30 showing a cylindrical rod 40 installed in
`5 the cylindrical receptacle 32. Prior to insertion of the
`cylindrical rod 40, a quantity of initially flowable adhe-
`sive 42 would be inserted into the receptacle. Once the
`cylindrical rod is inserted, the flowable adhesive would
`move and completely fill each of the annuluses 34, 36
`10 and 38. An adhesive would be chosen that would se-
`curely bond to the rod. The adhesive may be cured in
`any number of ways including heating the end connec-
`tor 30 to assist in curing. Upon curing, the adhesive 42
`will become a solid that is securely bonded to the cylin-
`15 drical rod 40.
`The connector 30 has a threaded end 44 which will
`connect with the threaded end of another connector
`(not shown) to form a string of rods in end-to-end rela-
`tionship.
`FIG. 5 illustrates a representation of the cross-section
`of the annulus showing the shape or design of the annu-
`lus through a line 50. The X-coordinate would repre-
`sent an imaginary straight line extending longitudinally
`along the interior wall of the cylindrical receptacle 32.
`25 The X-coordinate would, thus, extend axially along the
`radius of the cylindrical receptacle 32. The Y-coordi-
`nate would represent an imaginary straight line perpen-
`dicular to and intersecting the axis of the cylindrical
`receptacle.
`The line 50 has a pair of opposed ends with an inter-
`mediate portion extending into the body of the connec-
`tion. If the line 50 is divided into segments, the segment
`between the X-Y coordinate origin (or zero point) and
`point 52 would tangentially approach the X-axis in a
`35 convex curve as viewed from within the receptacle.
`The center point 53 of this radial segment between the
`X-Y coordinate origin and point 52 would be along the
`Y-axis. Accordingly, the segment would tangentially
`approach the wall of the cylindrical receptacle 32. The
`40 equation of the segment between the X-Y coordinate
`origin and point 52 would be:
`
`20 (cid:9)
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`30 (cid:9)
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`3
`FIG. 2 illustrates an enlarged view taken along sec-
`tion line 2-2 of FIG. 1 of a portion of the connector 12
`where the adhesive 18 abuts the body of the connector
`12.
`The profile or cross-section of the wedge or partial
`cone-shaped annulus is a straight line which is shown in
`the X-Y plane. When the adhesive 18 cures or hardens
`to a solid, it is securely fastened to the cylindrical rod
`10. While it fills the entire annulus, it is otherwise not
`fastened to the body of the connector 12.
`When the assembled rod 10 and adhesive 18 have
`cured, one connector will be threadably fastened to an
`adjoining connector (not shown) so that the rods will be
`in end-to-end longitudinal relationship.
`When the assembly string is pulled in tension by the
`threaded ends, the adhesive solid wedges 18 that are
`bonded to the rod press against the surface of the
`wedge-shaped annuluses 16. This action prevents and
`resists pulling the cylindrical rod 10 away from the
`connector 12. In practice, a small amount of slippage
`occurs between the cylindrical rod 10 and the end fit-
`ting. This causes the widest portion of the adhesive
`wedge to separate from the mating surface of the con-
`nector receptacle 14 thereby leaving a gap 20 which can
`be easily seen in the enlarged view in FIG. 2.
`A compressive force is imparted to the cylindrical
`rod 10 as the adhesive solid wedge 18 and the surface of
`the annulus 16 of the connector 12 press against each
`other to resist slippage. This compression force is ap-
`plied across the interval for which the adhesive wedge
`18 and the receptacle 14 make contact. This interval is
`shown by brackets 22 and 26. Conversely, the compres-
`sion force is not applied in the area indicated by the
`bracket 24.
`The abrupt change along the adhesive wedge and, in
`turn, the rod from no compressive force to heavy com-
`pressive force results in a concentration of shear stress
`at that point, i.e., at each end of bracket 24. It is at this
`point where most failures would initiate in cylindrical
`rods with existing designs, as seen most clearly in FIG.
`1.
`FIGS. 1 and 2 and the foregoing discussion illustrate
`the prior art and do not constitute a part of the inven-
`tion.
`FIG. 3 illustrates the design of the present invention.
`The connector or end fitting 30 is shown partially cut-
`away to show the substantially cylindrical receptacle 32
`and the tapered annuluses 34, 36 and 38. While three
`annuluses are shown in FIG. 3, it will be understood 50
`that a greater or lesser number might be employed. The
`end connector is constructed from a sturdy metal mate-
`rial.
`The end connector 30 is shown in FIG. 3 prior to
`introduction of a cylindrical rod 40 into the cylindrical 55
`receptacle. The diameter of the cylindrical receptacle
`32 is slightly larger than the diameter of the cylindrical
`rod.
`The annuluses 34, 36 and 38 are axially aligned and
`are coaxial with the cylindrical receptacle 32. (cid:9)
`The present invention reduces the concentration of
`shear stress at the edge of the gap by changing the shape
`of the annulus in the receptacle 32. The shape of each
`annulus is radial rather than straight. The curved profile
`or cross-section in the present invention results in a 65
`more gradual change at the edge of the gap from zero
`compressive force to full compressive force on the cy-
`lindrical rod thus, reducing the shear concentration that
`
`45
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`60
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`Y = R 5 3 - R 7X2
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`The next segment of the line 50 between point 52 and
`point 54 would either be a straight line or, as shown in
`FIG. 5, would be radially arcuate. If arcuate, the center
`point of the radius would be along an imaginary line
`which is perpendicular to the X-axis, and at a position
`such that the X-coordinate is negative and the Y-coordi-
`nate is positive.
`The segment of the line 50 between point 54 and point
`56 is radially arcuate. The center point of the radius
`would be along an imaginary line 58 perpendicular to
`the X-axis. The equation of the segment between points
`54 and 56 would be:
`
`Y = Y55 + Y Rss — (X — x55)2
`
`Y55 is the displacement of point 55 from the X axis
`that is fixed for each annulus.
`Finally, the segment of line 50 between point 56 and
`point 60 is radially arcuate about a center point 57 lies
`along an imaginary line 58 providing a concave curve as
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`Page 5 of 6
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`(cid:9)
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`5
`viewed from within the receptacle. The equation of the
`segment between points 56 and 60 would be:
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`5,253,946
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`6
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`What is claimed is:
`1. A connector to connect the end of a cylindrical
`rod, which connector comprises:
`an elongated body having a receptacle opening
`therein, the opening providing a receptacle wall;
`and
`said receptacle wall being defined by a plurality of
`axially aligned tapered annuluses, each annulus
`having a cross-section defined by a pair of opposed
`ends, one end asymptotically approaching said
`receptacle wall in a convex curve as viewed from
`within said receptacle and the opposite end arcu-
`ately approaching said receptacle wall in a concave
`curve as viewed from within said receptacle.
`2. A connector as set forth in claim 1 wherein an
`initially flowable adhesive may be inserted in said re-
`ceptacle prior to insertion of said cylindrical rod so that
`said adhesive will fill said annuluses and harden or cure
`to form a solid.
`3. A connector as set forth in claim 1 wherein said
`cylindrical rods are fiberglass, and wherein each end Of
`each said rod may be attached to a connector and
`wherein adjoining connectors may be attached to-
`gether.
`4. A connector as set forth in claim 1 wherein each of
`said tapered annuluses differ in length and wherein said
`annuluses are arranged so that the annuluses decrease in
`length from the opening of said receptacle.
`5. A connector to connect the end of a cylindrical rod
`or wire, which connector comprises:
`a tubular body having a cylindrical receptacle; and
`a plurality of axially aligned tapered annuluses ex-
`tending into said body and coaxial with said recep-
`tacle, each annulus having a cross-section radially
`tapered to a tangent with said cylindrical recepta-
`cle at one end of said annulus and radially arcuate
`about a center point positioned within said tubular
`body, and along an imaginary line perpendicular to
`said axis at the other end of said annulus.
`6. A connector as set forth in claim 5 wherein said
`cylindrical rods are fiberglass, each end of each rod may
`be attached to a connector and wherein adjoining con-
`nectors may be attached.
`7. A connector as set forth in claim 5 wherein an
`initially flowable adhesive may be inserted in said re-
`ceptacle prior to insertion of cylindrical rod so that said
`adhesive will fill said annuluses and cure or harden to a
`solid.
`
`Y = Y57 + Ri7 - (X - X57)2
`
`5 (cid:9)
`
`Y57 is the displacement of point 57 from the X axis
`that is fixed for each annulus.
`FIG. 6 illustrates the prior art connector in FIGS. 1 10
`and 2 wherein the cross-section shape 62 of the annulus
`is wedge-shaped. This is to be contrasted with the de-
`sign of shape 64 shown in FIG. 7 which is arcuate.
`It has been found that the design of the present inven-
`tion results in a more gradual change in the amount of 15
`compressive force from no compression to full com-
`pression. This reduces the shear stress impressed on the
`rod that often causes the rod to fail.
`Returning to a consideration of FIGS. 3 and 4, it will
`be observed that the major diameter of the annuluses 34, 20
`36, 38 progressively decreases from the open end of the
`receptacle toward the closed end. This arrangement
`more evenly distributes tensile stress across the critical
`stress points of end connector 30. The three critical
`stress points on end connector 30 occur at the major 25
`diameter of the annuluses 34, 36 and 38. Tensile load on
`end connector 30 generally increases from the open end
`of the receptacle toward the closed end. Progressively
`reducing the major diameters of annuluses 34, 36 and 38
`from the open end of the receptacle toward the closed 30
`end allows tensile stress at the three critical stress points
`of end connector 30 to be balanced or equalized.
`It will also be observed from FIGS. 3 and 4 that the
`length of annuluses 34, 36 and 38 progressively de-
`creases from the open end of the receptacle toward the 35
`closed end. Once the criteria are specified for line 50 of
`FIG. 5, the length and major diameter for each of annu-
`luses 34, 36 and 38 are related to each other in fixed
`relationship. Thus, this invention requiring progressive
`reduction of major diameters of annuluses 34, 36 and 38 40
`from the open end toward the closed end of the recepta-
`cle, inherently also requires progressive reduction of
`the length of annuluses 34, 36 and 38 from the open end
`toward the closed end of the receptacle.
`Whereas, the present invention has been described in 45
`relation to the drawings attached hereto, it should be
`understood that other and further modifications, apart
`from those shown or suggested herein, may be made (cid:9)
`within the spirit and scope of this invention.
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`Page 6 of 6
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`(cid:9)