[11] Patent Number: (cid:9)
`ate of Patent: (cid:9)
`[45] (cid:9)
`
`4,475,839
`Oct. 9, 1984
`
`4,401,396 8/1983 McKay (cid:9)
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`403/268 X
`
`FOREIGN PATENT DOCUMENTS
`681550 10/1952 United Kingdom (cid:9)
` 403/267
`Primary Examiner—Andrew V. Kundrat
`Attorney, Agent, or Firm—D. Peter Hochberg
`[57] (cid:9)
`ABSTRACT
`A sucker rod fitting for connecting together in an end-
`to-end relationship a plurality of sucker rods to form a
`sucker rod string for driving a pump in an oil well by an
`above ground oil pumping unit, the fitting comprising
`an elongated body having a central bore extending from
`an open end to a closed end, and the bore being defined
`at its end sections by cylindrical end walls, and between
`its end sections by alternately converging and diverging
`tapered sections which cause any breakage in a retained
`sucker rod to occur within the fitting.
`
`11 Claims, 2 Drawing Figures
`
`United States Patent [19]
`Strandberg (cid:9)
`
`[54] SUCKER ROD FITTING
`[75] Inventor: Donald G. Strandberg, Park Forest,
`Ill.
`[73] Assignee: Park-Ohio Industries, Inc.,
`Cleveland, Ohio
`[21] Appl. No.: 482,800
`[22] Filed: (cid:9)
`Apr. 7, 1983
`[51] Int. C1.3 (cid:9)
`[52] U.S. Cl. (cid:9)
`
` F16D 9/00
` 403/2; 403/267;
`403/268
` 403/265, 266, 267, 268,
`403/2
`
`[58] Field of Search (cid:9)
`
`[56] (cid:9)
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,127,741 11/1978 Bauer et al. (cid:9)
`4,315,699 2/1982 Lusk (cid:9)
`4,360,288 11/1982 Rutledge, Jr. et al. (cid:9)
`
` 403/268 X
` 403/361
` 403/268
`
`/3
`
`Petitioners' Exhibit 1004
`John Crane v. Finalrod
`IPR2016-01786
`Page 1 of 5
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`U.S. Patent (cid:9)
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`Oct. 9, 1984 (cid:9)
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`4,475,839
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`13
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`FIG .I
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`15
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`FIG.2
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`Page 2 of 5
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`1
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`SUCKER ROD FITTING
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`4,475,839
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`2
`a difficult and slow process to grasp the shattered part
`of the lower part of the sucker rod string and lift it to
`the surface, especially since it is not uncommon for such
`breaks to occur 1000 feet or more in the production tube
`5 beneath the surface of the earth. Once the part of the
`sucker rod string with the broken sucker rod is recov-
`ered, the rod is replaced by removing the failed rod and
`inserting the new rod in the couplings at its opposite
`ends.
`
`10
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`BACKGROUND OF THE INVENTION
`In order to supply the pressure required to draw oil
`from the ground such as when the oil pressure itself is
`insufficient to lift the oil to the earth's surface, it is
`conventional to place a pump in the well and to drive
`the pump by a pumping unit on the earth's surface. The
`pumping unit is often connected to the pump by a string
`SUMMARY OF THE INVENTION
`of interconnected sucker rods known as a sucker rod
`An object of the invention is provided an improved
`string. Although steel sucker rods have been widely
`sucker rod fitting which is effective and economical.
`used, it has more recently been found that lighter
`Another object is to provide a sucker rod fitting
`weight plastic and fiberglass reinforced plastic sucker
`rods are more effective since they allow use of smaller 15 wherein a sucker rod which has failed in a sucker rod
`string can be replaced in a fast and easy manner.
`motors and pumping units, are not subject to the corro- (cid:9)
`sion on steel rods, and they are less expensive to operate (cid:9)
`The inventor has found that the foregoing objects can
`be achieved by providing a sucker rod fitting config-
`in the field. (cid:9)
`Such non-metal rods must be connected in an end-to- (cid:9)
`ured to cause breaks which do occur in the sucker rod
`end relationship to achieve the length required to con- 20 to occur in the fitting itself rather than on a section of
`nect the pump and the pumping unit, while providing (cid:9)
`the rod outside of the fitting. Such a fitting substantially
`rigidity to this rod string and to enable replacement of (cid:9)
`eliminates the broomstraw effect, wherefore the sev-
`sections of the rod string when failures occur rather (cid:9)
`ered part of the string can be lifted from the production
`than requiring replacement of the entire rod string. (cid:9)
`tube so that the broken rod can be replaced.
`While steel rods generally have lengths of 25 to 30 feet 25 According to a preferred embodiment of the inven-
`and diameters of z to 1 inches, plastic and fiberglass (cid:9)
`tion, a fitting for a sucker rod includes an elongated
`reinforce plastic rods may be longer. For example, Ben- (cid:9)
`member having a bore extending from an open end
`net Industries markets a standard fiberglass reinforced (cid:9)
`towards a closed end. The central portion of the bore is
`resin rod having a length of 37 feet 6 inches and an outer (cid:9)
`defined by alternately long radially outwardly tapered
`diameter of 1 inch. In deep wells whose production 30 surfaces and short, radially inwardly tapered surfaces,
`tubes, through which the sucker rod string extends,
`the respective surfaces being dimensioned to cause fail-
`exceed about 3000 feet, a combination of steel rods and
`ures of a retained sucker rod which do occur, to occur
`fiberglass reinforced plastic rods are now frequently
`within the fitting.
`used. Sucker rod fittings are used to connect individual
`sucker rods. For example, U.S. Pat. No. 4,315,699 dis- 35 BRIEF DESCRIPTION OF THE DRAWINGS
`closes a fitting having a high strength, elongated, metal
`FIG. 1 shows a sucker rod retained at its opposite
`cylindrical retainer and a stack of metal collets whose (cid:9)
`ends in a pair of sucker rod fittings according to the
`inner peripheral profile has the shape of a plurality of (cid:9)
`invention.
`pairs of truncated cones placed base-to-base, with the (cid:9)
`end collet abutting the retainer; a potting compound is 40 FIG. 2 shows a partially sectioned, side view of a
`sucker rod fitting according to the invention.
`poured into the space between a received rod and the (cid:9)
`rings for locking the rod in place. Joslyn Manufacturing
`DETAILED DESCRIPTION OF THE
`and Supply Company of Chicago, Ill. at one time made
`PREFERRED EMBODIMENT
`a fitting from a solid piece of steel having a bore extend-
`ing from an open end to a closed end; cylindrical sur- 45 Referring first to FIG. 1, a sucker rod assembly 11 is
`shown comprising a fiberglass rod 3, or more specifi-
`faces defined sections at opposite ends of the bore, and (cid:9)
`cally a resin plastic rod having reinforcing fiberglass
`four intermediate sections were defined by alternately (cid:9)
`fibers running lengthwise therein, whose respective
`long, outwardly diverging surfaces and short, inwardly (cid:9)
`ends are received by identical sucker rod fittings 5. As
`converging surfaces. The length of the respective inter- (cid:9)
`mediate sections were equal. Fiberflex Products, Inc. of 50 shown more clearly in FIG. 2, each fitting 5 includes a
`threaded connector end 7, a collar 9, a wrench flat it
`Big Spring, Texas markets a similar product. The latter (cid:9)
`and a body portion 13 into which a bore 15 extends.
`company is the assignee of U.S. Pat. No. 4,360,288 (cid:9)
`Bore 15 is dimensioned to receive the end of rod 3
`which discloses a sucker rod fitting or connector having (cid:9)
`which is retained in the bore by an appropriate potting
`an axial receptacle for a cylindrical fiberglass rod. The (cid:9)
`receptacle is a blind bore defined by a series of out- 55 compound. Sucker rod assemblies 1 are used to transmit
`power from a pumping unit located above ground to a
`wardly converging tapered surfaces into which an ad- (cid:9)
`remote pump located in an oil well. Assemblies 1 are
`hesive material is placed to form, when cured, a series (cid:9)
`coupled together by internally threaded couplers or
`of wedge shaped annuluses about the rod to secure it in (cid:9)
`female couplings dimensioned and threaded to cooper-
`the fitting. A collet is attached to the open end of the (cid:9)
`60 ate with connector ends 7. Since the wells are often
`fitting to align the rod with the fitting. (cid:9)
`thousands of feet deep, it is not unusual for from 25 to
`One of the time-consuming and expensive problems (cid:9)
`200, 37i foot long fiberglass sucker rods to be con-
`in the field associated with sucker rod fittings is the (cid:9)
`nected together in oil wells in which they are used.
`replacement of sucker rods which have failed. In the (cid:9)
`It was explained earlier that a problem which has
`case of fiberglass reinforced plastic rods used with the (cid:9)
`known fittings described above, breakage generally 65 plagued prior art fiberglass sucker rod assemblies is the
`tendency of rods which fail in the field to break outside
`occurs outside of the fitting, and the break is character- (cid:9)
`of the fitting, with the break being characterized by
`ized by a broomstraw effect where the plastic or resin (cid:9)
`loose fibers or a broomstraw effect. It has been found by
`and fiberglass strands separate. With such a break, it is (cid:9)
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`4,475,839
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`the present inventor that the broomstraw effect can be
`avoided by configuring and dimensioning bore 15 so
`that any breaks of rod 13 which do occur, will occur
`within the bore. When breaks of rods 3 occur in this
`manner in a production tube in the field, it is a routine
`and relatively simple task to lift the upper part of the
`string from the tube, and to lower a fish (a mechanical
`clamp) into the tube to grasp the severed end of the
`sucker rod string and pull it to the gound surface so that
`the string can be repaired.
`Fitting 5 has been found to assure that breaks which
`occur in rod 3 are located within bore 15. Body 13 has
`an open end and a closed end. The body has an inner
`surface comprising various sections which define bore
`15. A first cylindrical section 17 is disposed adjacent the
`open end, section 17 being symmetrical about an axis Y
`which is the central axis of bore 15. Section 17 has an
`inner diameter D and a length Li, D being slightly
`larger than the outer diameter of sucker rod 3 so that
`rod 3 can slide into bore 15. A first long tapered section
`19 is located next to section 17. Section 19 is defined by
`a wall tapering radially outwardly from the wall of
`section 17 towards the closed end of bore 15 to a first
`short tapered section 21 (the terms "outwardly" and
`"inwardly" are based on axis Y as a reference). Section
`19 has a length L2. Section 21 tapers inwardly from the
`end of section 19 towards the closed end and terminates
`at a second long tapered section 23. Section 21 has a
`length L3 and the same inner diameter D at its narrow-
`est part as section 17. Section 23 tapers outwardly from
`section 21 towards the closed end, and has a length L4.
`Section 23 ends at a second short tapered section 25
`which tapers inwardly from the end of section 23 to a
`narrow portion having the diameter D. Section 25 has a
`length L5. A third long tapered section 27 begins at the
`narrowest part of the section 25, and tapers outwardly
`towards the closed end. The length of section 27 is L6.
`A third short tapered section 29 tapers inwardly from
`the end of section 27 towards the closed end of bore 15,
`section 29 having the inner diameter D at its narrow end
`and a length L7. A second cylindrical section 31 extends
`between section 29 and the closed end, and has the inner
`diameter D and a length L8.
`Length L2 of long tapered section 19 is less than
`lengths L4 or L6 of long tapered sections 23 and 27. The
`lengths L3, L5 and L7 are substantially equal. Length L8
`of second cylindrical section 31 is less than length Li of
`first cylindrical section 17. Fittings 5 for use with rods
`3 having diameters of 1 inch have a diameter D of 1 50
`inch, and the lengths L2, L4 and L6 of the three long
`tapered sections are in the proportion :1i:1}.Prefera-
`bly, lengths L2, L4 and L6 are, respectively inches, 1
`inches and 1 inches where D is 1 inch. Furthermore,
`when the foregoing proportional relationship is met, 55
`lengths L1 and L8 of the two cylindrical sections are in
`the proportion 1 11/161 for fittings 5 for 1 inch diame-
`ter sucker rods, and when L2= inches, L4= 1 inches
`and L6 = 1 inches, Li =1 11/16 inches and 'L8=
`inches. (cid:9)
`When fittings 5 are to be used with rods 3 having
`outer diameters of inches, diameter D is I inches, and
`lengths L2, L4 and L6 are in the proportion 1:1:1, and are
`preferably of the lengths I inches, 1 inch and 1 inch.
`Furthermore, lengths Li and L8 are in the proportion 1 65
`11/16 and 1; and when the lengths of L2, L4 and L6 are
`inch, 1 inch and 1 inch, lengths Li and L8 are 1 11/16
`inches and s inches respectively.
`
`4
`For each of the examples described above, the
`lengths L3, L5 and L7 of the short tapered sections are
`preferably equal, and for the specific lengths mentioned
`the lengths of the short tapered sections are conve-
`niently 3/16 inches. The long tapered sections are pref-
`erably tapered by the same amount; for the specific
`examples described, this taper is 4°. In order to assem-
`ble sucker rod assemblies fittings 5 are held vertically
`with the open end up and an appropriate potting com-
`pound is injected into the open end of bores 15 of fit-
`tings 5 so that the compound falls to the closed end of
`bore 15. The rod ends are inserted into the open ends of
`bores 15 of fittings 5 whose dimension D is slightly
`greater than the diameter of the rod, and the rod dis-
`places the potting compound toward the open end of
`bore 5 and fills the void between the rod and the inner
`surfaces defining bore 15. Once the potting compound
`cures, it adheres to rod 3 and blocks against withdrawal
`of the rod from the fitting by virtue of the filling of the
`recesses of the tapered sections.
`Fittings according to the invention which are config-
`ured and dimensioned as described above have been
`found to confine breakage of the sucker rods which
`25 does occur, to be located near the juncture of the first
`short tapered section 21 and the second long tapered
`section 23.
`Fittings according to the invention are preferably
`made from an appropriate steel, such as A. I. S. I. 4620
`cold rolled carbon steel having minimum 85,000 P. S. I.
`maximum 115,000 P. S. I. tensil strength, and Rockwell
`Hardness C17-C22. The fittings can be fabricated from
`standard rod stock using conventional machine tools.
`The invention has been described in detail with em-
`phasis on the preferred embodiment, but it should be
`understood that variations and modifications within the
`spirit and scope of the invention may occur to those
`skilled in the art to which the invention pertains.
`I claim:
`1. A sucker rod fitting for receiving an end of a
`sucker rod and for coupling the received sucker rod to
`another sucker rod, said sucker rod fitting comprising:
`an elongated body having an open end and a closed
`end, and an inner wall defming a generally cylindri-
`cal bore extending from said open end to said
`closed end;
`said inner wall comprising:
`a first cylindrical section adjacent said open end
`defming the axis of said bore and having a prede-
`termined inner diameter slightly larger than the
`diameter of the sucker rod;
`a first long tapered section tapering outwardly
`from said first cylindrical section toward said
`closed end and having a predetermined length;
`a first short tapered section tapering inwardly from
`said first long tapered section toward said closed
`end to a position defining said predetermined
`diameter and having a predetermined length;
`a second long tapered section tapering outwardly
`from said first short tapered section toward said
`closed end and having a predetermined length;
`a second short tapered section tapering inwardly
`from said second long tapered section toward
`said closed end to a position defming said prede-
`termined diameter and having a predetermined
`length;
`a third long tapered section tapering outwardly
`from said second short tapered section toward
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`said closed end and having a predetermined
`length;
`a third short tapered section tapering inwardly
`from said third long tapered section toward said
`closed end to a position defining said predeter- 5
`mined diameter and having a predetermined
`length; and
`a second cylindrical section extending from said
`third short tapered section toward said closed
`end and having said predetermined diameter; (cid:9)
`wherein said sections are dimensioned to cause a
`sucker rod received in said bore and engaged by
`said wall sections having said predetermined
`diameter to break within said bore when break-
`ing stress is applied to the sucker rod. (cid:9)
`2. The invention according to claim 1 wherein the
`predetermined length of said first long tapered section is
`less than the predetermined lengths of either of said
`second or third long tapered sections.
`3. The invention according to claim 2 wherein the 20
`predetermined length of said second and third long
`tapered sections are substantially equal.
`4. The invention according to claim 2 wherein the
`predetermined lengths of said second cylindrical section
`is less than the predetermined length of said first cylin- 25
`drical section.
`5. The invention according to claim 2 wherein the
`predetermined diameter is one inch, and the predeter-
`mined lengths of said first, second and third long ta-
`pered sections are in the proportion 8:18:18. (cid:9)
`6. The invention according to claim 2 wherein the
`predetermined diameter is one inch, and the predeter-
`
`6
`mined lengths of said first cylindrical section; said first,
`second and third long tapered sections; and said second
`cylindrical section are in the proportion 1
`11/16:8:11:11:1.
`7. The invention according to claim 2 wherein the
`predetermined lengths of said first, second and third
`short tapered sections are substantially equal.
`8. The invention according to claim 2 wherein said
`first, second and third long tapered sections are tapered
`by substantially the same amount.
`9. The invention according to claim 2 wherein the
`predetermined diameter is g inches, and the predeter-
`mined lengths of said first, second and third long ta-
`pered sections are in the proportion A:1:1.
`10. The invention according to claim 2 wherein the
`predetermined diameter is A inches, and the predeter-
`mined lengths of said first cylindrical section; said first,
`second and third long tapered sections; and said second
`cylindrical section, are in the proportion 1 11/16:1:1:1:g.
`11. A sucker rod fitting for receiving an end of a
`fiberglass sucker rod and for coupling the received
`sucker rod to another sucker rod, said sucker rod fitting
`comprising an elongated member having internal sur-
`faces defining a bore extending from an open end of said
`member to a closed end, said internal surfaces including
`alternately long, radially outwardly tapered surfaces
`extending toward said closed end, and short radially
`inwardly tapered surfaces extending toward said closed
`end, said surfaces being dimensioned to cause breaks
`which occur in a received sucker rod to occur within
`said bore.
`
`* (cid:9)
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`* *
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