CA2242592A1 - Multiple lead threads for high torque transfer applications - Google Patents
Multiple lead threads for high torque transfer applications Download PDFInfo
- Publication number
- CA2242592A1 CA2242592A1 CA 2242592 CA2242592A CA2242592A1 CA 2242592 A1 CA2242592 A1 CA 2242592A1 CA 2242592 CA2242592 CA 2242592 CA 2242592 A CA2242592 A CA 2242592A CA 2242592 A1 CA2242592 A1 CA 2242592A1
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- Prior art keywords
- threaded
- thread
- threads
- lead
- shoulder
- Prior art date
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- Abandoned
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- 238000012546 transfer Methods 0.000 title description 10
- 230000008878 coupling Effects 0.000 claims abstract description 16
- 238000010168 coupling process Methods 0.000 claims abstract description 16
- 238000005859 coupling reaction Methods 0.000 claims abstract description 16
- 238000005553 drilling Methods 0.000 claims description 14
- 230000000694 effects Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000003197 gene knockdown Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D1/00—Couplings for rigidly connecting two coaxial shafts or other movable machine elements
- F16D1/02—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for connecting two abutting shafts or the like
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/03—Couplings; joints between drilling rod or pipe and drill motor or surface drive, e.g. between drilling rod and hammer
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
- E21B17/042—Threaded
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B7/00—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections
- F16B7/18—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections using screw-thread elements
- F16B7/182—Connections of rods or tubes, e.g. of non-circular section, mutually, including resilient connections using screw-thread elements for coaxial connections of two rods or tubes
Abstract
A threaded coupling for transferring torque comprising a first member having a shoulder and an externally threaded portion with a plurality of thread leads and a second member having an abutment face and an internally threaded portion with a plurality of thread leads. The first member is adapted to be threadedly engaged with the second member with the shoulder abutting the abutment face.
Description
APPLICATION FOR PATENT
lNVENTOR: WILLIAM D. MURRAY
TITLE: MULTIPLE LEAD THREADS FOR HIGH
TORQUE TRANSFER APPLICATIONS
SPECIF~CATION
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field ofthe Invention. The present invention relates generally to threaded connections for high torque transfer applir~*onc The present invention is particularly rt~d for uce in drilling operationc, inclnfling but not limited to drill pipe, drill motors 10 and various other drilling appa-~lus.
lNVENTOR: WILLIAM D. MURRAY
TITLE: MULTIPLE LEAD THREADS FOR HIGH
TORQUE TRANSFER APPLICATIONS
SPECIF~CATION
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field ofthe Invention. The present invention relates generally to threaded connections for high torque transfer applir~*onc The present invention is particularly rt~d for uce in drilling operationc, inclnfling but not limited to drill pipe, drill motors 10 and various other drilling appa-~lus.
2. Description of the Related Art. Many types of col~rlingc and CO~ OI ~
have been used to axially join cylinflrirql m~mbers to one another. In many ;.~ ..ces, it is necessary to l,~rel torsional force and axial force from the one cylin~lric~l member to the other "~ h~ n*mes, it is npcecs~ry that the coupling or conn~ctor be easily 15 connected and ~lisconnecte~l Such a re4u~eme~l e~ ;s using a welded conn~ction to join the two m~mhers Threaded conn~cti~mc have been used for many years to join members to one another in torsional and axial force ~ g applic~tionc~ Th,ez~ed cc~nnpchs)nc transfer axial COLU~)1eSSiV~ and tensile forces and also torsional forces in one direction 20 about the lc.. ,~l . .-1;. .~1 axis of the cylin~1ri~ 1 members. Generally, threaded conn~c*ons allow easy u~....r.;t and disconnect c~pa-hili*es However, certain threaded connPctionc ~621}01 ... 03567/3 EXPRESSMAILNO. I~IU~ q such as tapered pipe thread connections, may be more difficult to disconnect due to the nature of the threaded engagement.
Multiple lead threads have been used in the past for purposes of rapidly threading one member to another. Multiple lead threads include multiple start positions for the 5 beginning threading of the members together. Typically, the thread lead is greater in a mllltiple lead thread than in a single lead thread. As a result of the increased thread lead the travel of the one member relative to the other member is greater for each revolution - of the threaded member than for a smaller thread lead. Thus, multiple lead threads have been used in ;..~ cçs requiring rapid travel of one member on a long threaded member.
0 It is to be understood that the usage of mllltiple lead threads in these instances were not for high torque transfer applictqtion~
U.S. Patent 4,564,225 to Taylor discloses multiple lead threading used for joining sections of casing or tubing. Taylor discloses the joinder of two tubular members, each having radially tapered exterior multiple lead threaded portions and a collar having 15 radially tapered interior multiple lead threaded portions. The threaded portions of the collar are threaded in opposite direction~. Taylor teaches that this coupling arr~ngem~nt decreases field make-up or knock-down time, and greatly reduces any tend~ncy to gall and/or cross thread. In the Taylor threaded colll~c~;on assembly, the tapered threads take the load as the connection is made up. The tapered threads have two points of contact 20 between the threads. The tapered threaded conn~ction of Taylor does not have high torsional strength and is a connection which is not int~n~e(l to be ~lic~semhled.
In addition to having a threaded connection with high torque transferring char~ct~rictics7 it is often required that the size and length of the threaded connection be ...~;..~ <;~fd to a ...;..;...~.. This is particularly true for many pieces of drilling eqllipm~nt 25 and downhole tools used in oil well drilling operations. One example of this limitation is in positive ~ p~ e~ motors used to drill highly deviated wells. The positive displ~cem~nt motor or "drill motor" rotates the drill bit and is powered by drilling mud pl~c~... ;,~d by surface pumps lln~ to the drill motor Liou~ the drill string bore.
In this mode of flrilling the entire drill string need not be continll~lly rotated during 30 drilling. However, the plt;s~ d drilling mud acts on an int~rn~l rotating power 46213-01 ... 03567/3 EXPRESSM~lLNO.lBlU371000US
tr~ncmiccion assembly in the drill motor to rotate the drill bit attached to the lower end of the drill motor. The various components of the power tr~ncmiCcion assembly are typically joined with threaded connections. The plurality of components forming the power tr~ncmicsion assembly are interior of an outer housing assembly. It is important to 5 nn(3~s~nrl that the outside ~ m~t~r of the drill motor is desired to be kept at a ~
m~t~r. Furthermore, the interior components of the power tr~ncmicsion assembly are limited by these exterior conctr~intc and the int~rn~l working operations necessary for the - drill motor. As a result, the threaded connections m~king up and joining the various interior components of the power tr~ncmiccion assembly have limitations as to the 10 diameter of the member and optimally the length of the mud motor is also kept to a minimum. Typically, the threaded connections used in connecting the various co~ ell~ of the drill motor have been a rotary shouldered connection as shown in Fig.
5. Several types of rotary shouldered connections are illustrated in Fig. 5. The rotary shouldered co~nectinn in Fig. 5 between the outer h- ncing members, generally tlesi n~ted 15 as 6, has conical threads with outer abutting shoulders. The rotary shouldered connection between the upper interior members, generally decigr ~t~d as 7, has straight threads with outer abutting shoulders. The rotary shouldered cnnn~ction generally decign~ted as 8 has straight threads with inner abutting shoulders. Typically, much of the torque capacity of the rotary shouldered connection is attributable to the friction of the abutting shoulders 20 but a portion ofthe torque capacity is attributable to a "jackscrew" effect which is based on the lead of the thread and tends to col-.~ress the chnlllders together.
It is desirable to have a high ~LIenglll, high torque Ll~sr~r threaded connection between two cylin~1ric~1 members. It is desirable to have a high strength, high torque r~l threaded connection which can be used in drilling operations, including, but not 25 limited to drill pipe, drill motors and various other drilling a~lus. It is desirable to have a threaded connection design which o~ es the torque Ll~srel capability of the connection given a certain thread ~ mloter.
U21341.. 03~7/3 E~ESSMA~NO.~
BRIEF SIJMMARY OF THE INVENTION
The multiple lead thread connection of the present invention provides a high ~llellg~, high torque transfer threaded co~ cl;on b~lw~e~ two cylindrical members. The present invention can be used in drilling operations, inrlnAing but not limited to drill pipe, 5 drill motors and various other drilling ap,~ lus. The multiple lead thread connection O~ .~s the torque ~ r~. c~r~hility of the connection given a certain thread diameter.
The multiple lead threaded coupling for tr~n~fPrring torque inchlclPs a male joint - having a cylindrical body with a longihl(lin~l throughbore. The cylindrical body has an PxtPm~lly threaded portion with a plurality of thread leads. The cylindrical body also has 10 a shoulder which can be a peripheral shoulder or an end of a pin. The multiple lead threaded coupling also inchltlPs a female joint having a cylindrical body with alongit~l~lin~l throughbore. The cylindrical body has an abutment face and an intPrn~lly threaded portion with a plurality of thread leads. The male joint is capable of threaded çng~gPment with the female joint with the shoulder abutting the abutment face.
In order to more fully understand the drawings refell~d to in the detailed description of the present invention, a brief description of each drawing is presPntP~ in which:
Fig. 1 is a partial cross-sec*on~l view of a threaded connection according to a first 20 embodiment of the mllltip1e start screw threads for high torque transfer applic~o*on~
Fig. 2 is a partial cross-sectional view of a threaded connection according to asecond embodiment of the mllltiple start screw threads for high torque transfer applications;
Fig. 3 is a pel~e~iLiv~ view sL~wi~g the female end portion of a pipe having the25 multiple start screw threads;
Fig. 4 is an enlarged portion from Fig. l; and Fig. 5 is a partial ~iulawa~ view of a portion of a prior art drill motor showing several rotary shouldered threaded connPc~ion~
46213-01 ... 03567/3 EXPRESSMAILNO.T131U~/
DETAILED DESCRIPTION OF THE INVENTION
The present invention of mn1tirle lead threads for high torque transfer applications will now be described in detail with reference to Figs. 1-4. Fig. 1 shows a multiple start, tapered thread, rotary shouldered c- nnçction and Fig. 2 is a multiple start, straight thread, s rotary shouldered connection.
~ ef~rring to Fig. 1, a pin or male threaded tubing joint 10 is threadedly connected to the box or female tubing joint 12. The male tubing joint 10 has an e~ rn~lly threaded - portion 14 and the box tubing joint has int~ lly threaded portion 16. Referring to Fig.
1, the threaded portions 14 and 16 are tapered to facilitate easy stab-in between the male 10 and female thread portions 14 and 16, respectively. Although not necessary in all applications of the present invenhon, the tubing members 10 and 12 are shown having an axial bore 18 ext~n-ling therc~.ough.
Referring to Fig. 3, an abutment face portion 28 of the female tubing joint 12 is shown having a plurality of threads 32a-d as best shown in Fig. 1. Similarly, the male 15 tubing joint 10 includes a corresponding plurality of threads 30a-d as best shown in Fig.
1.
Referring to Fig. 4, the threads 30a-d and 32a-d have a crest 20, a root 22, andflanks 24 and 26 t~xt~nt1ing between the crest 20 and the root 22. It is to be understood that the thread type shown in Figs. 1 and 4 is not critical to the present invention. For 20 eY~mple in Figs. 1 and 4 the threads have been tr mc~ted while in Fig. 2 the threads have not been t~m~te-l Referring to Fig. 3, the threads 32a-d have four leads spaced uniformly at 90~
intervals around the abutment face portion 28 of the female tubing joint 12. While not shown in the drawings, it is to be understood that the threads 30a-d are also spaced 25 ul~ifo~ ly at 90~ intervals on the pin ~ 1ed portion 14.
It is also to be ...ul. . ~uod that the present invention is not limited to the four leads shown in the drawings, but inclndes any mlmher of mnltirle lead threads, incllllling but not limited to two and three leads. The leads will always be ....; rO. ~ly spaced around the male and female tubing joints 10 and 12, lcspe~,lively. For ~Y~mrle7 three leads will be 30 spaced at 120~ intervals and two leads at 180~ intervals.
~213-01.. 03~/3 E~ESSMALNO.~lU371oWUS
F~f~rring to Fig. 1, the male threaded tubing joint 10 includes a shoulder 34 which abuts the abutment face portion 28 of the female tubing joint 12 when the rotaryshouldered connection is made up. As shown in Fig. 4, there is one point of contact between the threads. The point of contact occurring between the flanks 26.
~eferring to Fig. 2, the present invention is shown as a multiple start, straight thread, rotary shouldered conn~ction for high torque transfer applications. Referring to Fig. 2, a pin or male threaded tubing joint 10' is threadedly connected to the box or female - tubing joint 12'. The male tubing joint 10' has an çxt~rn~lly threaded portion 14' and the box tubing joint has int~rn~lly threaded portion 16'. The threaded portions 14' and 16' are 10 straight threads. Although not n~cess~ry in all applications of the present invention, the tubing members 10' and 12' typically have an axial bore 18' çxt~n~in~ the~ ough.Referring to Fig. 2, an abutment face portion 28' of the female tubing joint 12' is shown having a plurality of threads 32a'-d'. Similarly, the male tubing joint 10' includes a corresponding plurality of threads 30a'-d'. As stated above, the threads 30a'-d', 32a'-d' 15 are not truncated as in Figs. 1, 3 and 4. The threads 32a'-d' have four leads spaced , ..,; rO" "ly at 90~ inten als around the a~ul~-le.ll face portion 28' of the female tubing Joint 12'. While not shown in the drawings, it is to be understood that the threads 30a'-d' are also spaced .~..;rollllly at 90~ intervals on the pin threaded portion 14'. As stated above, the present invention is not limited to four leads but is intended to include generally 20 multiple leads.
Still referring to Fig. 2, the male threaded tubing joint 10' inch~(les a shoulder 34' which abuts the abutment face portion 28' of the female tubing joint 12' when the rotary shouldered conn~ction is made up.
The ",.~ ,lc lead, rotary shouldered conn~ction can w;ll.~ (1 a greater torque than 25 a similar single lead, rotary shouldered conn.oction. Thus, without increasing the length of the threaded portions or the outer diameter of the threaded portions, the torsional capacity ofthe rotary shouldered col~l.rc~;on can be increased by ~ n~ing from a single lead thread to a multiple lead thread. A three lead thread has a greater torque capacity than does a two lead thread.
~6213-01 ... 03567/3 EXPRESS M~L NO. I~IU3710WUS
The increased torque capacity results from the increased lead of thread which results from mllltirle lead threads. The lead of a thread is shown as P in Fig. 1. The lead of a thread P is the (1ict~n~e between the threads through one revolution of 360~. It is known in the design of threaded connec*onC that the lead of a thread P affects the 5 torsional capacity of the threaded connection. The lead of the thread P affects what is commonly referred to as the "jackscrew" effect. The jackscrew effect is realized by the increased angle of attack of the threads as the thread lead P increases.
- Q~ l;./ely, the jacl;scl~w contribution to the tor~ion~l capacity to yield a rotary shouldered connection is detçrminP~ from the following equation:
YmA ~ p Y 12 ~2~) 1 0 Where:
Ty = Turning moment or torque required to yield--ft.-lbs.
Ym = Minin~ n yield strength of the material--psi.
P = Lead of Thread - inches A = Cross section area--sq. inches.
The above equation is taken from an industry acc~t~d equation to calculate the torque to yield a rotary shouldered connection publiched by the ~meric~n Petroleum Tnc*hlte (API) in API Recomm~n-led Practice 7G (1990).
Merely for eY~mrl~ry purposes, a single lead thread having a thread lead P of 0.1667" will be co~ d to a double lead thread having a thread lead P of 0.3333". If the 20 m~t~n~l yield ~1" ~Ih and area are cr~ 1 in the ~ from the above equation, the increased thread lead P results in the mlll*rle lead, rotary chollldpred col...rcl;on having twice the jackscrew effect of the single lead, rotary chollld~red conn~oc*on Thepercentage increase in the overall torque required to yield the particular connf~c*on lc on other factors. However, the ~,e..;~ ge increase can easily be on the order of 25 4%fora2-1/2" ~ n~t~rrotaryshoulderedco~ ccl;on havingtwoleadswitha m~tçri~l yield of 15Q000 pounds per square inch. The ~e.~-.l ~ increase ~roves urith a three lead connection.
46213-01 ... 03567/3 EXPRESS M~IL NO. TBlU371000US
CA 02242~92 1998-07-08 The number of leads that can be used will in every instance will be affected by variables such as size of the members, cost, and m~nllf~ct~lring ability. Physically, it is anticipated that three leads can be used on threaded connections of members having a diameter in the range of 1" to 3".
Another benefit of the multiple lead rotary shouldered connection is that highertorque load is achieved while red~cing ~e shoulder load. This further helps to ensure the integrity of the threaded conn~ctinn As a threaded conn~ction is torqued together and the - shoulder 34 abuts the abutment face 28, all of the torque forces are converted to axial forces, if one ignores frictinn These axial forces load the shoulder 34 in compression and 10 load the pin threaded portion 14 in tension. The forces are ll~s~ d between the pin and box by loading of the thread flanks 24. If the same torque is applied on two simil~rly sized threads, one having a double lead thread and the other having a single lead thread, and the cross-sectional areas of the two connections are the same, the reslllting shoulder stress decreases as the lead of thread P increases. In many instances, the shoulder stress 15 is the limiting factor for a threaded cormection. With drilling equipment the goal is often to transmit as much torque as possible. As (li~cllssed above, a multiple lead thread is able to transmit more torque at the same reslllting stress as for a single lead thread.
Having described the invention above, various modifications of the techniques, procedures, m~t~ri~l and e4~ ....r~.l will be a~ clll to those in the art. It is inten~e~ that 20 all such variations within the scope and spirit of the appended claims be embraced thereby.
~6213-01 ... 03567/3 EXPRESSMAILNO.11~1S4371000US
have been used to axially join cylinflrirql m~mbers to one another. In many ;.~ ..ces, it is necessary to l,~rel torsional force and axial force from the one cylin~lric~l member to the other "~ h~ n*mes, it is npcecs~ry that the coupling or conn~ctor be easily 15 connected and ~lisconnecte~l Such a re4u~eme~l e~ ;s using a welded conn~ction to join the two m~mhers Threaded conn~cti~mc have been used for many years to join members to one another in torsional and axial force ~ g applic~tionc~ Th,ez~ed cc~nnpchs)nc transfer axial COLU~)1eSSiV~ and tensile forces and also torsional forces in one direction 20 about the lc.. ,~l . .-1;. .~1 axis of the cylin~1ri~ 1 members. Generally, threaded conn~c*ons allow easy u~....r.;t and disconnect c~pa-hili*es However, certain threaded connPctionc ~621}01 ... 03567/3 EXPRESSMAILNO. I~IU~ q such as tapered pipe thread connections, may be more difficult to disconnect due to the nature of the threaded engagement.
Multiple lead threads have been used in the past for purposes of rapidly threading one member to another. Multiple lead threads include multiple start positions for the 5 beginning threading of the members together. Typically, the thread lead is greater in a mllltiple lead thread than in a single lead thread. As a result of the increased thread lead the travel of the one member relative to the other member is greater for each revolution - of the threaded member than for a smaller thread lead. Thus, multiple lead threads have been used in ;..~ cçs requiring rapid travel of one member on a long threaded member.
0 It is to be understood that the usage of mllltiple lead threads in these instances were not for high torque transfer applictqtion~
U.S. Patent 4,564,225 to Taylor discloses multiple lead threading used for joining sections of casing or tubing. Taylor discloses the joinder of two tubular members, each having radially tapered exterior multiple lead threaded portions and a collar having 15 radially tapered interior multiple lead threaded portions. The threaded portions of the collar are threaded in opposite direction~. Taylor teaches that this coupling arr~ngem~nt decreases field make-up or knock-down time, and greatly reduces any tend~ncy to gall and/or cross thread. In the Taylor threaded colll~c~;on assembly, the tapered threads take the load as the connection is made up. The tapered threads have two points of contact 20 between the threads. The tapered threaded conn~ction of Taylor does not have high torsional strength and is a connection which is not int~n~e(l to be ~lic~semhled.
In addition to having a threaded connection with high torque transferring char~ct~rictics7 it is often required that the size and length of the threaded connection be ...~;..~ <;~fd to a ...;..;...~.. This is particularly true for many pieces of drilling eqllipm~nt 25 and downhole tools used in oil well drilling operations. One example of this limitation is in positive ~ p~ e~ motors used to drill highly deviated wells. The positive displ~cem~nt motor or "drill motor" rotates the drill bit and is powered by drilling mud pl~c~... ;,~d by surface pumps lln~ to the drill motor Liou~ the drill string bore.
In this mode of flrilling the entire drill string need not be continll~lly rotated during 30 drilling. However, the plt;s~ d drilling mud acts on an int~rn~l rotating power 46213-01 ... 03567/3 EXPRESSM~lLNO.lBlU371000US
tr~ncmiccion assembly in the drill motor to rotate the drill bit attached to the lower end of the drill motor. The various components of the power tr~ncmiCcion assembly are typically joined with threaded connections. The plurality of components forming the power tr~ncmicsion assembly are interior of an outer housing assembly. It is important to 5 nn(3~s~nrl that the outside ~ m~t~r of the drill motor is desired to be kept at a ~
m~t~r. Furthermore, the interior components of the power tr~ncmicsion assembly are limited by these exterior conctr~intc and the int~rn~l working operations necessary for the - drill motor. As a result, the threaded connections m~king up and joining the various interior components of the power tr~ncmiccion assembly have limitations as to the 10 diameter of the member and optimally the length of the mud motor is also kept to a minimum. Typically, the threaded connections used in connecting the various co~ ell~ of the drill motor have been a rotary shouldered connection as shown in Fig.
5. Several types of rotary shouldered connections are illustrated in Fig. 5. The rotary shouldered co~nectinn in Fig. 5 between the outer h- ncing members, generally tlesi n~ted 15 as 6, has conical threads with outer abutting shoulders. The rotary shouldered connection between the upper interior members, generally decigr ~t~d as 7, has straight threads with outer abutting shoulders. The rotary shouldered cnnn~ction generally decign~ted as 8 has straight threads with inner abutting shoulders. Typically, much of the torque capacity of the rotary shouldered connection is attributable to the friction of the abutting shoulders 20 but a portion ofthe torque capacity is attributable to a "jackscrew" effect which is based on the lead of the thread and tends to col-.~ress the chnlllders together.
It is desirable to have a high ~LIenglll, high torque Ll~sr~r threaded connection between two cylin~1ric~1 members. It is desirable to have a high strength, high torque r~l threaded connection which can be used in drilling operations, including, but not 25 limited to drill pipe, drill motors and various other drilling a~lus. It is desirable to have a threaded connection design which o~ es the torque Ll~srel capability of the connection given a certain thread ~ mloter.
U21341.. 03~7/3 E~ESSMA~NO.~
BRIEF SIJMMARY OF THE INVENTION
The multiple lead thread connection of the present invention provides a high ~llellg~, high torque transfer threaded co~ cl;on b~lw~e~ two cylindrical members. The present invention can be used in drilling operations, inrlnAing but not limited to drill pipe, 5 drill motors and various other drilling ap,~ lus. The multiple lead thread connection O~ .~s the torque ~ r~. c~r~hility of the connection given a certain thread diameter.
The multiple lead threaded coupling for tr~n~fPrring torque inchlclPs a male joint - having a cylindrical body with a longihl(lin~l throughbore. The cylindrical body has an PxtPm~lly threaded portion with a plurality of thread leads. The cylindrical body also has 10 a shoulder which can be a peripheral shoulder or an end of a pin. The multiple lead threaded coupling also inchltlPs a female joint having a cylindrical body with alongit~l~lin~l throughbore. The cylindrical body has an abutment face and an intPrn~lly threaded portion with a plurality of thread leads. The male joint is capable of threaded çng~gPment with the female joint with the shoulder abutting the abutment face.
In order to more fully understand the drawings refell~d to in the detailed description of the present invention, a brief description of each drawing is presPntP~ in which:
Fig. 1 is a partial cross-sec*on~l view of a threaded connection according to a first 20 embodiment of the mllltip1e start screw threads for high torque transfer applic~o*on~
Fig. 2 is a partial cross-sectional view of a threaded connection according to asecond embodiment of the mllltiple start screw threads for high torque transfer applications;
Fig. 3 is a pel~e~iLiv~ view sL~wi~g the female end portion of a pipe having the25 multiple start screw threads;
Fig. 4 is an enlarged portion from Fig. l; and Fig. 5 is a partial ~iulawa~ view of a portion of a prior art drill motor showing several rotary shouldered threaded connPc~ion~
46213-01 ... 03567/3 EXPRESSMAILNO.T131U~/
DETAILED DESCRIPTION OF THE INVENTION
The present invention of mn1tirle lead threads for high torque transfer applications will now be described in detail with reference to Figs. 1-4. Fig. 1 shows a multiple start, tapered thread, rotary shouldered c- nnçction and Fig. 2 is a multiple start, straight thread, s rotary shouldered connection.
~ ef~rring to Fig. 1, a pin or male threaded tubing joint 10 is threadedly connected to the box or female tubing joint 12. The male tubing joint 10 has an e~ rn~lly threaded - portion 14 and the box tubing joint has int~ lly threaded portion 16. Referring to Fig.
1, the threaded portions 14 and 16 are tapered to facilitate easy stab-in between the male 10 and female thread portions 14 and 16, respectively. Although not necessary in all applications of the present invenhon, the tubing members 10 and 12 are shown having an axial bore 18 ext~n-ling therc~.ough.
Referring to Fig. 3, an abutment face portion 28 of the female tubing joint 12 is shown having a plurality of threads 32a-d as best shown in Fig. 1. Similarly, the male 15 tubing joint 10 includes a corresponding plurality of threads 30a-d as best shown in Fig.
1.
Referring to Fig. 4, the threads 30a-d and 32a-d have a crest 20, a root 22, andflanks 24 and 26 t~xt~nt1ing between the crest 20 and the root 22. It is to be understood that the thread type shown in Figs. 1 and 4 is not critical to the present invention. For 20 eY~mple in Figs. 1 and 4 the threads have been tr mc~ted while in Fig. 2 the threads have not been t~m~te-l Referring to Fig. 3, the threads 32a-d have four leads spaced uniformly at 90~
intervals around the abutment face portion 28 of the female tubing joint 12. While not shown in the drawings, it is to be understood that the threads 30a-d are also spaced 25 ul~ifo~ ly at 90~ intervals on the pin ~ 1ed portion 14.
It is also to be ...ul. . ~uod that the present invention is not limited to the four leads shown in the drawings, but inclndes any mlmher of mnltirle lead threads, incllllling but not limited to two and three leads. The leads will always be ....; rO. ~ly spaced around the male and female tubing joints 10 and 12, lcspe~,lively. For ~Y~mrle7 three leads will be 30 spaced at 120~ intervals and two leads at 180~ intervals.
~213-01.. 03~/3 E~ESSMALNO.~lU371oWUS
F~f~rring to Fig. 1, the male threaded tubing joint 10 includes a shoulder 34 which abuts the abutment face portion 28 of the female tubing joint 12 when the rotaryshouldered connection is made up. As shown in Fig. 4, there is one point of contact between the threads. The point of contact occurring between the flanks 26.
~eferring to Fig. 2, the present invention is shown as a multiple start, straight thread, rotary shouldered conn~ction for high torque transfer applications. Referring to Fig. 2, a pin or male threaded tubing joint 10' is threadedly connected to the box or female - tubing joint 12'. The male tubing joint 10' has an çxt~rn~lly threaded portion 14' and the box tubing joint has int~rn~lly threaded portion 16'. The threaded portions 14' and 16' are 10 straight threads. Although not n~cess~ry in all applications of the present invention, the tubing members 10' and 12' typically have an axial bore 18' çxt~n~in~ the~ ough.Referring to Fig. 2, an abutment face portion 28' of the female tubing joint 12' is shown having a plurality of threads 32a'-d'. Similarly, the male tubing joint 10' includes a corresponding plurality of threads 30a'-d'. As stated above, the threads 30a'-d', 32a'-d' 15 are not truncated as in Figs. 1, 3 and 4. The threads 32a'-d' have four leads spaced , ..,; rO" "ly at 90~ inten als around the a~ul~-le.ll face portion 28' of the female tubing Joint 12'. While not shown in the drawings, it is to be understood that the threads 30a'-d' are also spaced .~..;rollllly at 90~ intervals on the pin threaded portion 14'. As stated above, the present invention is not limited to four leads but is intended to include generally 20 multiple leads.
Still referring to Fig. 2, the male threaded tubing joint 10' inch~(les a shoulder 34' which abuts the abutment face portion 28' of the female tubing joint 12' when the rotary shouldered conn~ction is made up.
The ",.~ ,lc lead, rotary shouldered conn~ction can w;ll.~ (1 a greater torque than 25 a similar single lead, rotary shouldered conn.oction. Thus, without increasing the length of the threaded portions or the outer diameter of the threaded portions, the torsional capacity ofthe rotary shouldered col~l.rc~;on can be increased by ~ n~ing from a single lead thread to a multiple lead thread. A three lead thread has a greater torque capacity than does a two lead thread.
~6213-01 ... 03567/3 EXPRESS M~L NO. I~IU3710WUS
The increased torque capacity results from the increased lead of thread which results from mllltirle lead threads. The lead of a thread is shown as P in Fig. 1. The lead of a thread P is the (1ict~n~e between the threads through one revolution of 360~. It is known in the design of threaded connec*onC that the lead of a thread P affects the 5 torsional capacity of the threaded connection. The lead of the thread P affects what is commonly referred to as the "jackscrew" effect. The jackscrew effect is realized by the increased angle of attack of the threads as the thread lead P increases.
- Q~ l;./ely, the jacl;scl~w contribution to the tor~ion~l capacity to yield a rotary shouldered connection is detçrminP~ from the following equation:
YmA ~ p Y 12 ~2~) 1 0 Where:
Ty = Turning moment or torque required to yield--ft.-lbs.
Ym = Minin~ n yield strength of the material--psi.
P = Lead of Thread - inches A = Cross section area--sq. inches.
The above equation is taken from an industry acc~t~d equation to calculate the torque to yield a rotary shouldered connection publiched by the ~meric~n Petroleum Tnc*hlte (API) in API Recomm~n-led Practice 7G (1990).
Merely for eY~mrl~ry purposes, a single lead thread having a thread lead P of 0.1667" will be co~ d to a double lead thread having a thread lead P of 0.3333". If the 20 m~t~n~l yield ~1" ~Ih and area are cr~ 1 in the ~ from the above equation, the increased thread lead P results in the mlll*rle lead, rotary chollldpred col...rcl;on having twice the jackscrew effect of the single lead, rotary chollld~red conn~oc*on Thepercentage increase in the overall torque required to yield the particular connf~c*on lc on other factors. However, the ~,e..;~ ge increase can easily be on the order of 25 4%fora2-1/2" ~ n~t~rrotaryshoulderedco~ ccl;on havingtwoleadswitha m~tçri~l yield of 15Q000 pounds per square inch. The ~e.~-.l ~ increase ~roves urith a three lead connection.
46213-01 ... 03567/3 EXPRESS M~IL NO. TBlU371000US
CA 02242~92 1998-07-08 The number of leads that can be used will in every instance will be affected by variables such as size of the members, cost, and m~nllf~ct~lring ability. Physically, it is anticipated that three leads can be used on threaded connections of members having a diameter in the range of 1" to 3".
Another benefit of the multiple lead rotary shouldered connection is that highertorque load is achieved while red~cing ~e shoulder load. This further helps to ensure the integrity of the threaded conn~ctinn As a threaded conn~ction is torqued together and the - shoulder 34 abuts the abutment face 28, all of the torque forces are converted to axial forces, if one ignores frictinn These axial forces load the shoulder 34 in compression and 10 load the pin threaded portion 14 in tension. The forces are ll~s~ d between the pin and box by loading of the thread flanks 24. If the same torque is applied on two simil~rly sized threads, one having a double lead thread and the other having a single lead thread, and the cross-sectional areas of the two connections are the same, the reslllting shoulder stress decreases as the lead of thread P increases. In many instances, the shoulder stress 15 is the limiting factor for a threaded cormection. With drilling equipment the goal is often to transmit as much torque as possible. As (li~cllssed above, a multiple lead thread is able to transmit more torque at the same reslllting stress as for a single lead thread.
Having described the invention above, various modifications of the techniques, procedures, m~t~ri~l and e4~ ....r~.l will be a~ clll to those in the art. It is inten~e~ that 20 all such variations within the scope and spirit of the appended claims be embraced thereby.
~6213-01 ... 03567/3 EXPRESSMAILNO.11~1S4371000US
Claims (11)
1. A threaded coupling for transferring torque comprising:
a first member having a shoulder and an externally threaded portion with a plurality of thread leads; and a second member having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said first member threadedly engages said second member with said shoulder abutting said abutment face.
a first member having a shoulder and an externally threaded portion with a plurality of thread leads; and a second member having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said first member threadedly engages said second member with said shoulder abutting said abutment face.
2. The threaded coupling of claim 1, wherein said pluralities of thread leads are straight threads.
3. The threaded coupling of claim 1, wherein said pluralities of thread leads are tapered threads.
4. A threaded coupling for transferring torque in a drilling operation comprising;
a male joint having a cylindrical body with a longitudinal throughbore, said cylindrical body having a shoulder and an externally threaded portion with a plurality of thread leads; and a female joint having a cylindrical body with a longitudinal throughbore, said cylindrical body having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said male joint threadedly engages said female joint with said shoulder abutting said abutment face.
a male joint having a cylindrical body with a longitudinal throughbore, said cylindrical body having a shoulder and an externally threaded portion with a plurality of thread leads; and a female joint having a cylindrical body with a longitudinal throughbore, said cylindrical body having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said male joint threadedly engages said female joint with said shoulder abutting said abutment face.
5. The threaded coupling of claim 4, wherein said pluralities of thread leads are straight threads.
6. The threaded coupling of claim 4, wherein said pluralities of thread leads are tapered threads.
7. The threaded coupling of claim 4, wherein said shoulder is exterior of said externally threaded portion and said abutment face is exterior of said internally threaded portion.
8. A threaded coupling for transferring torque in a drilling operation comprising:
a male joint having a cylindrical body, said cylindrical body having a shoulder and an externally threaded portion with a plurality of thread leads; and a female joint having a cylindrical body, said cylindrical body having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said male joint threadedly engages said female joint with said shoulder abutting said abutment face.
a male joint having a cylindrical body, said cylindrical body having a shoulder and an externally threaded portion with a plurality of thread leads; and a female joint having a cylindrical body, said cylindrical body having an abutment face and an internally threaded portion with a plurality of thread leads;
wherein said male joint threadedly engages said female joint with said shoulder abutting said abutment face.
9. The threaded coupling of claim 8, wherein said pluralities of thread leads are straight threads.
10. The threaded coupling of claim 8, wherein said pluralities of thread leads are tapered threads.
11. The threaded coupling of claim 8, wherein said shoulder is exterior of said externally threaded portion and said abutment face is exterior of said internally threaded portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US89387097A | 1997-07-11 | 1997-07-11 | |
| US08/893,870 | 1997-07-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2242592A1 true CA2242592A1 (en) | 1999-01-11 |
Family
ID=25402266
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2242592 Abandoned CA2242592A1 (en) | 1997-07-11 | 1998-07-08 | Multiple lead threads for high torque transfer applications |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2242592A1 (en) |
| DE (1) | DE19830995A1 (en) |
| GB (1) | GB2327247A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6977059B2 (en) * | 2002-12-04 | 2005-12-20 | Pyrotek, Inc. | Molten metal shaft coupling system |
| WO2012037935A1 (en) | 2010-08-24 | 2012-03-29 | Rothenberger Ag | Coupling parts for connecting a driving device to an expander head |
| DE102010035222B4 (en) * | 2010-08-24 | 2013-04-18 | Rothenberger Ag | Coupling for the axial connection of a drive unit with an expander head |
| DE202012003902U1 (en) * | 2012-04-19 | 2012-10-16 | Günter Urban | pipe connectors |
| US10731423B2 (en) | 2013-10-01 | 2020-08-04 | Baker Hughes, A Ge Company, Llc | Multi-start thread connection for downhole tools |
| US20150093189A1 (en) * | 2013-10-01 | 2015-04-02 | Baker Hughes Incorporated | Multi-start thread connection for downhole tools |
| WO2018098439A1 (en) | 2016-11-28 | 2018-05-31 | Baker Hughes, A Ge Company, Llc | Multi-start thread connection for downhole tools |
| CH717074B1 (en) * | 2020-01-27 | 2023-11-30 | Zermec Gmbh | Tool coupling for tool-free coupling and decoupling of a hollow core drill to a drive unit. |
| EP4015733A1 (en) * | 2020-12-18 | 2022-06-22 | Hilti Aktiengesellschaft | Coupler |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4707001A (en) * | 1986-06-20 | 1987-11-17 | Seal-Tech, Inc. | Liner connection |
| WO1994005893A1 (en) * | 1992-08-28 | 1994-03-17 | Hendrik Corporaal | Drill string coupling |
| GB2309276A (en) * | 1996-01-20 | 1997-07-23 | Boart Longyear Ltd | Threaded joint |
-
1998
- 1998-07-08 CA CA 2242592 patent/CA2242592A1/en not_active Abandoned
- 1998-07-10 DE DE1998130995 patent/DE19830995A1/en not_active Withdrawn
- 1998-07-13 GB GB9815009A patent/GB2327247A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB9815009D0 (en) | 1998-09-09 |
| GB2327247A (en) | 1999-01-20 |
| DE19830995A1 (en) | 1999-01-14 |
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