CA2278987A1 - Tube rod - Google Patents
Tube rod Download PDFInfo
- Publication number
- CA2278987A1 CA2278987A1 CA002278987A CA2278987A CA2278987A1 CA 2278987 A1 CA2278987 A1 CA 2278987A1 CA 002278987 A CA002278987 A CA 002278987A CA 2278987 A CA2278987 A CA 2278987A CA 2278987 A1 CA2278987 A1 CA 2278987A1
- Authority
- CA
- Canada
- Prior art keywords
- diameter
- rod
- tube rod
- tube
- female
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000005553 drilling Methods 0.000 claims abstract description 10
- 239000011435 rock Substances 0.000 claims abstract description 9
- 238000009527 percussion Methods 0.000 claims description 5
- 230000013011 mating Effects 0.000 claims description 2
- 230000007704 transition Effects 0.000 description 5
- 238000005336 cracking Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910001149 41xx steel Inorganic materials 0.000 description 1
- AYFVYJQAPQTCCC-GBXIJSLDSA-N L-threonine Chemical compound C[C@@H](O)[C@H](N)C(O)=O AYFVYJQAPQTCCC-GBXIJSLDSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK 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
- E21B17/0426—Threaded with a threaded cylindrical portion, e.g. for percussion rods
Landscapes
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
- Particle Accelerators (AREA)
- Fluid-Damping Devices (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
Abstract
A tube rod for rock drilling has a female threaded end into which a male thread (either on a male connector or on the end of another tube rod) can be screwed to form part of a drill string. The female threaded end is (a) of larger external diameter than the central section of the rod and (b) has an annular groove with an asymmetrical profile, the flank of this groove nearest the to threaded end being steeper than the other flank.
Description
Tube Rod This invention relates to a tube rod for rotary/
percussive rock drilling, and in particular to the way two tube rods are connected one to the other by threads. Tube reds are conventionally connected end to end by thre$ds which allow rods to be screwed together (and unscrewed) to form a drill string which may consist of a large number of connected rods.
Hackgrou d to t a Zavex~,t~.vn Tube rods, and drill strings made up from tube rods, operate in a harsh environment. Considerable stresses are built up in the rods, and these usually manifest themselves in cracking of the rods in the area of the threaded joints. This tracking usually leads to failure of the respective rod. It is therefore desirable to design the threaded ends of the rods in a way which will minimise stress build up at any particular paint, in particular to minimise stress build up at the bottom of the female threads.
Suamiar~r of the. Iaveatioa According to a first aspect of the invention, there is provided a tube rod for percussion rock drilling having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and at least part of the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the
percussive rock drilling, and in particular to the way two tube rods are connected one to the other by threads. Tube reds are conventionally connected end to end by thre$ds which allow rods to be screwed together (and unscrewed) to form a drill string which may consist of a large number of connected rods.
Hackgrou d to t a Zavex~,t~.vn Tube rods, and drill strings made up from tube rods, operate in a harsh environment. Considerable stresses are built up in the rods, and these usually manifest themselves in cracking of the rods in the area of the threaded joints. This tracking usually leads to failure of the respective rod. It is therefore desirable to design the threaded ends of the rods in a way which will minimise stress build up at any particular paint, in particular to minimise stress build up at the bottom of the female threads.
Suamiar~r of the. Iaveatioa According to a first aspect of the invention, there is provided a tube rod for percussion rock drilling having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and at least part of the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the
- 2 -female threaded end and the major part of the tube rod length there is an annular groove having a root diameter (the third diameter) which is less than both the first and the second diameter.
The groove preferably has an asymmetrical profile when seen in cross section parallel to the tube axis, and the flank nearest the threaded end is preferably steeper than the opposite flank.
The adoption of these features has been shown to result in a reduction in stress build up at the bottom of the female threaded end.
It is preferred for the female end to be of the second diameter from its end. up to the annular groove. However it is within the scope of the invention for the female end to be df the second diameter only in a region surrounding the bottom of the threaded end which is where the major ZO stress concentration occurs, or for the female end to be of the second diameter on both sides of the annular groove.
In most cases, the rod will have one male threaded sad sad one female threaded end. However rods with two female threaded ends are conceivable, to be joined end to end by a tubular connector with two male threaded ends.
The hollow bore of~ the rod is preferably reduced in internal diameter at the inner end of the female threaded socket to form a neck, and the bore diameter tapers outwards from the neck to the full bare diameter of the major part of the tube rod length.
The internal diameter of the rod can have a region between the female threaded end and the major part of the tube rod
The groove preferably has an asymmetrical profile when seen in cross section parallel to the tube axis, and the flank nearest the threaded end is preferably steeper than the opposite flank.
The adoption of these features has been shown to result in a reduction in stress build up at the bottom of the female threaded end.
It is preferred for the female end to be of the second diameter from its end. up to the annular groove. However it is within the scope of the invention for the female end to be df the second diameter only in a region surrounding the bottom of the threaded end which is where the major ZO stress concentration occurs, or for the female end to be of the second diameter on both sides of the annular groove.
In most cases, the rod will have one male threaded sad sad one female threaded end. However rods with two female threaded ends are conceivable, to be joined end to end by a tubular connector with two male threaded ends.
The hollow bore of~ the rod is preferably reduced in internal diameter at the inner end of the female threaded socket to form a neck, and the bore diameter tapers outwards from the neck to the full bare diameter of the major part of the tube rod length.
The internal diameter of the rod can have a region between the female threaded end and the major part of the tube rod
- 3 -length where the internal diameter is less than at either side of this region. The internal diameter of the tube rod can taper from the major part of the tube rod length down to this region of leader internal diameter. The internal diameter of the tube rod can also taper from the female threaded end down to this region of lesser internal diameter.
The female threaded end can have an internal shoulder at right angles to the tube axis, with the internal diameter of the tube rod tapering.down from the shoulder to the region of lesser internal diameter. The taper of the internal diameter can be a conical taper but is preferably a radiused taper.
The neck or z~egion of lesser diameter of the internal bore pz~efezably lies on substantially the same cross-section of the rod as the third (external) diameter of the rod.
Preferably the third (external) diameter of the rod lies on a cross-section of the rod which is offset from the centre of the neck or region of lesser diameter in the direction towards the major part of the tube rod length.
The threaded ends can be initially separate from the rod and can be joinEd to a length of oonstant cross section tube by friction welded joints, the length of constant cross section forming the major part of the tube rod length. This is a particularly expedient method of manufacturing which allows standard tube stock to be used for the major part of the rod, with only the ends requiring machining.
The threaded. region of the male end can extend from an annular shoulder, the shoulder being adapted to abut against the end of the female threaded end of another rod when the two rode are screwed together. The male threaded 9 _ .
region is preferably shorter than the female threaded recess so that when the male threaded end is screwed into the female threaded end of another rod until the shoulder abuts the end of the other rod, the male end does not reach the bottom of the female recess. This helps to avoid tensile pre-loading of the joint.
The annular shoulder can be stepped and the mating end of a female threaded end aecti.on of another rod can have a shoulder such that when the rode are screwed together, the shoulders interengage to prevent substantial radial movement of one shoulder relative to the other. This helps to prevent relative radial movement at the shoulder which in turn helps to reduce bending of the asaemb~.ed string of rods.
This feature can represent an independent invention, and thus according to a second aspect of the invention, there is provided a tube rod assembly far perCUSSion rock drilling, the assembly including a plurality of rods connected end to end by joints comprising interengaging male and female Ghzeada wherein when the joints are assembled, an end of a female threaded compozzent is in contact with an external shoulder on the adjacent male threaded component, the external shoulder hava.ng a ciz~cumferentially extending stepped land, with part of the end of the female threaded component fitting around the land to hinder relative radial movement between the two ends at the position of the shoulder.
All the features set out above, either alone or in combination, increase the resistance of the tube rod to cracking, especially cracking at the last thread root at the female end. The addition of the tapered internal bore, the increased outside diameter at the thread portion and the external groove all contribute to dispersing the stresses arising at the thread and internal profile of the female threaded part so that the stresses at these critical regions are reduced.
According to a third aspect of the invention, there is pro~rided a tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the narrowest part of which coincides with the location of the third diameter.
According to a fourth aspect of the invention, there is provided a tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root . diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the internal diameter of the rod tapering into the neck from both aides of the neck.
The invention also extends to a female threaded tube rod end for j oining to a length of tube tv contribute to the formation of a tube rod as set forth above.
Hrief Descziptioa of the Drawings The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 shows a tube rod in accordance with the invention, with the central section foreshortened;
Figure 2 is a cross section through the female threaded end;
Figure 3 is a cross section through the male threaded end;
Figure 4 is a cross-section through an alternative male threaded end:
Figures 5 and 6 are cross-sections through two alternative female threaded ends: and Figure 7 shows a second embodiment of tube rod in accordance with the invention.
Detailed Deaeri~ation of Preferred 8~nbodiments Figure 1 shows a rod which has a central section 7.0, a female threaded end section 12 and a male threaded end section 14. The central section 10 will typically be 1.5 to 2 metres in length (but can be up tv 6 metres long), _ 7.
whilst the male and female threaded end sections will typically each have a length of about 25o millimetres.
The central section l0 is a tube having a constant cross section over its length. Typically the outside diameter will be about 80 to 90 millimetres, and the inside diameter about 65 to 75 millimetres, leaving a wall thickness of about 15 millimetres.
The end sections 12 and 14, both of which have a through bore, will be welded to the centre section to at 16 and 18. This welding can appropriately be achieved through a friction welding process.
The female threaded end section 12 shown in Figure 2 will normally be machined from solid material. Suitable steels are a 3% NiCrMo grade steel or a 3% CrMo grade steel. The section 12 has an internally threaded end 2o, and a tube end 22 which is to be welded to the centre section to at 1B. The external and internal diameters of the section 12 at the tube end 2z will be substantially the same as those of the centre section lo.
The end 2o of the section has an abutment shoulder 24, a mouth 26 into which the male threaded end of another rod will be introduced, a threaded region 28 and a relieved region 3o at the inner end of the thread section.
Figure 2 does not illustzate the thread which will be formed on the inner walls of the region 28. This thread will be a double start trapezoidal thread, of the type well known in connecting tube rods for use in rotary/pereussion rock drilling. The root diametez~ of this thread will be substantially the same as that of the relieved portion 30.
_ g Beyond the relie~red portion 30, the wall thicknesB of the section 12 becomes thicker and as a result the internal bore diameter becomes less. The bore has a narxow neck at 32, and a tapered transition at 34 from the relieved portion 30 to the neck, and a further comically tapered portion 36 from the neck to the tube end 22. The tapered transition 34 is shown in the form of a conical taper, but may alternatively be a radiused taper (see Figure 6).
The external surface of the female portion has a diameter i.n the region 38 which can be the same as that of the central portion 10 or can be larger. The diameter at the end portion 4o is slightly larger than that of the central portion, for example 2% - 6~ larger, and When the diameter at the region 38 is larger than the central portion, it can also be 2 - 6% larger.
Between the first diameter and the second diameter area regions, there is an annular groove 42 which has a root diameter substantially less than either the first or the second diameters. This groove is bounded by a smooth curve, one flank of which closest to the end 24 is steeper than the other flank. Although not shown in this figure, the transition between the steep flank and the surface z4 can be radiused, rather than the sharp edge shown. It will seen from Figure 2 that the base of the groove lies in a cross-sectional plane which incorporates the neck 32.
The radius of the base part of this groove 42 can, for example, be 22.5 millimetres. Between the groove 42 and the neck 32 the female threaded section 7.2 has a greater wall thickness than at any other region of its length.
The male threaded end section 7.4 (see Figure 3) has a threaded boss 44 extending from an unthreaded collar 46.
The diameter of the collar 46 ~.s the same as that of the female end (the second diameter) so that when the male end _ g is screwed into a female end, there is no step in the external diameter at the joint. However the male end could be of the first diameter and/or could have a diameter ramp at the end to blend into the external diameter of the female end without a step.
The Collar 46 has externally a flat at 48 on which serial numbers or other information can be stamped.
The right he.nd end of the portion 14 (as seen in Figure: 3) has a tube end 5o which will match the tube end 22 of the female threaded portion and will match the cross section of the central section 10.
The section has a through bore 52. The threaded portion ~4 will have external threads to match the internal threads 28.
In use, the male end 14 of one rod is screwed into the female end 12 of another rod. The two are screwed together until the shoulder 54 of one male end comes into contact with the shoulder 24 of the female end. There is no contact between the extreme end 56 of the male end and the internal shoulder S8 of the female end.
In Figures 4 to 7, the same reference numerals are used where they denote parts which are directly equivalent to parts described with reference to Figures 1 to 3.
Figure 4 shows a male threaded end section 114 which differs from the section shown in Figure 3 by the introduction of a land 155 which engages, when the rods are screwed together, inside the mouth 26 of the adjacent female threaded end section, and forms a close fit in that mouth so as to prevent any significant radial mo~rement between the shoulders 24 and 54_ This minimises any tendency to bending in the assembled drill rod string.
Figure 5 shows an embodiment where both the neck 132 and the groove 142 are elongated as compared with the embodiment shown in Figure 2. This assists in reducing the stress level at the inner end of the threaded region 28, particularly in the part of the threaded zegion closest to the neck 132.
Figure 6 shows an embodiment similar to that of Figure 2, but where the tapered transition 34 is replaced by a radiused transition 234.
The relationship between the various parameters can be as follows, where:
A represents the external diameter of the central section to E represents the maximum extet~nal diameterof the female threaded end section 14 C represents minimum external diameter of the female threaded end section 7.4 (at the groove 42) D repreaez~ts the smallest internal diameterof the threaded section 14 (at the throat 32) S represents the cure diameter of the female thread 28.
The following relationships hold good for rods in accordance with the invention:
A is less than 8 B is up to 15o~ of E
C is loo - 130 of E
D is 4S - 60~ of E.
In addition to the features described above which reduce the susceptibility of the rod tv stress cracking, the external surface of the rod can be provided with external helically fluted portions 60, 6z (Figure ~). These fluted portions help to enhance the straightness of holes being drilled, by maintaining some contact with the walls of the hole while allowing flow of drilling fluid and drilling debris past the rod up the hole. The rod is thus held straight in the hole, so that the drill bit is always presented to the rock ahead in the correct orientation_ There may be one (60) or two (60,62) of these fluted portions on each rod.
It has suzprisingly been found that the formation of the annular groove 42 helps to reduce stress concentrations in the female threaded end, these concentrations otherwise arising in the area of the last thread root and internal recess of the threaded region 28.
This resistance to failure is enhanced by the increased diameter of the region 40 and by the internal tapered surfaces at 34 and 36.
These measures cause a dispersion of the overall stress so that the stress of the critical point is reduced.
The female threaded end can have an internal shoulder at right angles to the tube axis, with the internal diameter of the tube rod tapering.down from the shoulder to the region of lesser internal diameter. The taper of the internal diameter can be a conical taper but is preferably a radiused taper.
The neck or z~egion of lesser diameter of the internal bore pz~efezably lies on substantially the same cross-section of the rod as the third (external) diameter of the rod.
Preferably the third (external) diameter of the rod lies on a cross-section of the rod which is offset from the centre of the neck or region of lesser diameter in the direction towards the major part of the tube rod length.
The threaded ends can be initially separate from the rod and can be joinEd to a length of oonstant cross section tube by friction welded joints, the length of constant cross section forming the major part of the tube rod length. This is a particularly expedient method of manufacturing which allows standard tube stock to be used for the major part of the rod, with only the ends requiring machining.
The threaded. region of the male end can extend from an annular shoulder, the shoulder being adapted to abut against the end of the female threaded end of another rod when the two rode are screwed together. The male threaded 9 _ .
region is preferably shorter than the female threaded recess so that when the male threaded end is screwed into the female threaded end of another rod until the shoulder abuts the end of the other rod, the male end does not reach the bottom of the female recess. This helps to avoid tensile pre-loading of the joint.
The annular shoulder can be stepped and the mating end of a female threaded end aecti.on of another rod can have a shoulder such that when the rode are screwed together, the shoulders interengage to prevent substantial radial movement of one shoulder relative to the other. This helps to prevent relative radial movement at the shoulder which in turn helps to reduce bending of the asaemb~.ed string of rods.
This feature can represent an independent invention, and thus according to a second aspect of the invention, there is provided a tube rod assembly far perCUSSion rock drilling, the assembly including a plurality of rods connected end to end by joints comprising interengaging male and female Ghzeada wherein when the joints are assembled, an end of a female threaded compozzent is in contact with an external shoulder on the adjacent male threaded component, the external shoulder hava.ng a ciz~cumferentially extending stepped land, with part of the end of the female threaded component fitting around the land to hinder relative radial movement between the two ends at the position of the shoulder.
All the features set out above, either alone or in combination, increase the resistance of the tube rod to cracking, especially cracking at the last thread root at the female end. The addition of the tapered internal bore, the increased outside diameter at the thread portion and the external groove all contribute to dispersing the stresses arising at the thread and internal profile of the female threaded part so that the stresses at these critical regions are reduced.
According to a third aspect of the invention, there is pro~rided a tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the narrowest part of which coincides with the location of the third diameter.
According to a fourth aspect of the invention, there is provided a tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root . diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the internal diameter of the rod tapering into the neck from both aides of the neck.
The invention also extends to a female threaded tube rod end for j oining to a length of tube tv contribute to the formation of a tube rod as set forth above.
Hrief Descziptioa of the Drawings The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 shows a tube rod in accordance with the invention, with the central section foreshortened;
Figure 2 is a cross section through the female threaded end;
Figure 3 is a cross section through the male threaded end;
Figure 4 is a cross-section through an alternative male threaded end:
Figures 5 and 6 are cross-sections through two alternative female threaded ends: and Figure 7 shows a second embodiment of tube rod in accordance with the invention.
Detailed Deaeri~ation of Preferred 8~nbodiments Figure 1 shows a rod which has a central section 7.0, a female threaded end section 12 and a male threaded end section 14. The central section 10 will typically be 1.5 to 2 metres in length (but can be up tv 6 metres long), _ 7.
whilst the male and female threaded end sections will typically each have a length of about 25o millimetres.
The central section l0 is a tube having a constant cross section over its length. Typically the outside diameter will be about 80 to 90 millimetres, and the inside diameter about 65 to 75 millimetres, leaving a wall thickness of about 15 millimetres.
The end sections 12 and 14, both of which have a through bore, will be welded to the centre section to at 16 and 18. This welding can appropriately be achieved through a friction welding process.
The female threaded end section 12 shown in Figure 2 will normally be machined from solid material. Suitable steels are a 3% NiCrMo grade steel or a 3% CrMo grade steel. The section 12 has an internally threaded end 2o, and a tube end 22 which is to be welded to the centre section to at 1B. The external and internal diameters of the section 12 at the tube end 2z will be substantially the same as those of the centre section lo.
The end 2o of the section has an abutment shoulder 24, a mouth 26 into which the male threaded end of another rod will be introduced, a threaded region 28 and a relieved region 3o at the inner end of the thread section.
Figure 2 does not illustzate the thread which will be formed on the inner walls of the region 28. This thread will be a double start trapezoidal thread, of the type well known in connecting tube rods for use in rotary/pereussion rock drilling. The root diametez~ of this thread will be substantially the same as that of the relieved portion 30.
_ g Beyond the relie~red portion 30, the wall thicknesB of the section 12 becomes thicker and as a result the internal bore diameter becomes less. The bore has a narxow neck at 32, and a tapered transition at 34 from the relieved portion 30 to the neck, and a further comically tapered portion 36 from the neck to the tube end 22. The tapered transition 34 is shown in the form of a conical taper, but may alternatively be a radiused taper (see Figure 6).
The external surface of the female portion has a diameter i.n the region 38 which can be the same as that of the central portion 10 or can be larger. The diameter at the end portion 4o is slightly larger than that of the central portion, for example 2% - 6~ larger, and When the diameter at the region 38 is larger than the central portion, it can also be 2 - 6% larger.
Between the first diameter and the second diameter area regions, there is an annular groove 42 which has a root diameter substantially less than either the first or the second diameters. This groove is bounded by a smooth curve, one flank of which closest to the end 24 is steeper than the other flank. Although not shown in this figure, the transition between the steep flank and the surface z4 can be radiused, rather than the sharp edge shown. It will seen from Figure 2 that the base of the groove lies in a cross-sectional plane which incorporates the neck 32.
The radius of the base part of this groove 42 can, for example, be 22.5 millimetres. Between the groove 42 and the neck 32 the female threaded section 7.2 has a greater wall thickness than at any other region of its length.
The male threaded end section 7.4 (see Figure 3) has a threaded boss 44 extending from an unthreaded collar 46.
The diameter of the collar 46 ~.s the same as that of the female end (the second diameter) so that when the male end _ g is screwed into a female end, there is no step in the external diameter at the joint. However the male end could be of the first diameter and/or could have a diameter ramp at the end to blend into the external diameter of the female end without a step.
The Collar 46 has externally a flat at 48 on which serial numbers or other information can be stamped.
The right he.nd end of the portion 14 (as seen in Figure: 3) has a tube end 5o which will match the tube end 22 of the female threaded portion and will match the cross section of the central section 10.
The section has a through bore 52. The threaded portion ~4 will have external threads to match the internal threads 28.
In use, the male end 14 of one rod is screwed into the female end 12 of another rod. The two are screwed together until the shoulder 54 of one male end comes into contact with the shoulder 24 of the female end. There is no contact between the extreme end 56 of the male end and the internal shoulder S8 of the female end.
In Figures 4 to 7, the same reference numerals are used where they denote parts which are directly equivalent to parts described with reference to Figures 1 to 3.
Figure 4 shows a male threaded end section 114 which differs from the section shown in Figure 3 by the introduction of a land 155 which engages, when the rods are screwed together, inside the mouth 26 of the adjacent female threaded end section, and forms a close fit in that mouth so as to prevent any significant radial mo~rement between the shoulders 24 and 54_ This minimises any tendency to bending in the assembled drill rod string.
Figure 5 shows an embodiment where both the neck 132 and the groove 142 are elongated as compared with the embodiment shown in Figure 2. This assists in reducing the stress level at the inner end of the threaded region 28, particularly in the part of the threaded zegion closest to the neck 132.
Figure 6 shows an embodiment similar to that of Figure 2, but where the tapered transition 34 is replaced by a radiused transition 234.
The relationship between the various parameters can be as follows, where:
A represents the external diameter of the central section to E represents the maximum extet~nal diameterof the female threaded end section 14 C represents minimum external diameter of the female threaded end section 7.4 (at the groove 42) D repreaez~ts the smallest internal diameterof the threaded section 14 (at the throat 32) S represents the cure diameter of the female thread 28.
The following relationships hold good for rods in accordance with the invention:
A is less than 8 B is up to 15o~ of E
C is loo - 130 of E
D is 4S - 60~ of E.
In addition to the features described above which reduce the susceptibility of the rod tv stress cracking, the external surface of the rod can be provided with external helically fluted portions 60, 6z (Figure ~). These fluted portions help to enhance the straightness of holes being drilled, by maintaining some contact with the walls of the hole while allowing flow of drilling fluid and drilling debris past the rod up the hole. The rod is thus held straight in the hole, so that the drill bit is always presented to the rock ahead in the correct orientation_ There may be one (60) or two (60,62) of these fluted portions on each rod.
It has suzprisingly been found that the formation of the annular groove 42 helps to reduce stress concentrations in the female threaded end, these concentrations otherwise arising in the area of the last thread root and internal recess of the threaded region 28.
This resistance to failure is enhanced by the increased diameter of the region 40 and by the internal tapered surfaces at 34 and 36.
These measures cause a dispersion of the overall stress so that the stress of the critical point is reduced.
Claims (23)
1. A tube rod for percussion rock drilling, wherein the rod has opposed threaded ends and a major part of its length between the threaded ends, at least one of the ends has a female thread, the major part of the tube rod length having an outside diameter (the first diameter), at least part of the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, and an annular groove is provided between the female threaded end and the major part of the tube rod length, the annular groove having a root diameter (the third diameter) which is less than both the first and the second diameters.
2. A tube rod as claimed in Claim 1, wherein the groove has an asymmetrical profile when seen in cross section parallel to the tube axis.
3. A tube rod as claimed in Claim 2, wherein the flank of the groove nearest to the threaded end is steeper than the opposite flank.
4. A tube rod as claimed in Claim 1, wherein one of the ends has a female thread and the other end has a male thread.
5. A tube rod as claimed in Claim 1, wherein the hollow bore of the rod is reduced in internal diameter at the inner end of the female thread to form a neck, and the bore diameter tapers outwards from the neck to the full bore diameter of the major part of the tube rod length.
6. A tube rod as claimed in Claim 1, wherein the internal diameter of the rod has a region between the female threaded end and the major part of the tube rod length where the internal diameter is less than at either aide of this region.
7. A tube rod as claimed in Claim 6, wherein the internal diameter of the tube rod tapers from the major part of the tube rod length down to the region of lesser internal diameter.
B. A tube rod as claimed in Claim 6, wherein the internal diameter of the tube rod tapers from the female threaded end down to the region of lesser internal diameter.
9. A tube rod as claimed in Claim 5, wherein the female threaded end has an internal shoulder at right angles to the tube axis, and the internal tube bore tapers from the shoulder down to the region of lesser internal diameter.
10. A tube rod as claimed in Claim 7, wherein the taper of the internal diameter is a conical taper.
11. A tube rod as claimed in Claim 7, wherein the taper of the internal diameter is a radiused taper.
12. A tube rod as claimed in Claim 5, wherein the neck or region of lesser diameter of the internal bore lies on substantially the same cross-section of the rod as the third (external) diameter of the rod.
13. A tube rod as claimed in Claim 12, wherein the third (external) diameter of the rod lies on a cross-section of the rod which is offset from the centre of the neck or region of lesser diameter in the direction towards the major part of the tube rod length.
14. A tube rod as claimed in Claim 1, wherein the threaded ends are initially separate from the rod and are joined to a length of constant cross section tube by friction welded joints, the length of constant cross section forming the major part of the tube rod length.
15. A tube rod as claimed in any Claim 1, wherein the male threaded end has a threaded region extending from an annular shoulder, the shoulder being adapted to abut against the end of the female threaded end of another rod when the two rods are screwed together, the male threaded region being shorter than the female threaded recess so that when the male threaded end is screwed into the female threaded end of another rod until the shoulder abuts the end of the other rod, the male end does not reach the bottom of the female recess.
16. A tube rod as claimed in Claim 15, wherein the annular shoulder on the male threaded end section is stepped and the mating end of a female threaded end section of another rod has a shoulder such that when the rods are screwed together, the shoulders interengage to prevent substantial radial movement of one shoulder relative to the other.
17. A tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the narrowest part of which coincides with the location of the third diameter.
18. A tube rod having threaded ends, at least one of the ends having a female thread, the major part of the tube rod length between the threaded ends having an outside diameter (the first diameter) and the or each female threaded end having an outside diameter (the second diameter) which is larger than the first diameter, wherein between the female threaded end and the major part of the tube rod length there is an annular groove having a root diameter (the third diameter) which is less than both the first and the second diameter, and the internal diameter of the rod having a reduced diameter neck, the internal diameter of the rod tapering into the neck from both sides of the neck.
19. A tube rod as claimed in Claim 1, wherein the rod has at least one externally fluted section, the external diameter across the crests of the fluted section being equal to or larger than the second diameter.
20. A tube rod as claimed in Claim 19, wherein the externally fluted section forms the outside diameter of the female threaded end which is of the second diameter.
21. A tube rod assembly for percussion rock drilling, the assembly including a plurality of rods connected end to end by joints comprising interengaging male and female threads wherein when the joints are assembled, an end of a female threaded component is in contact with an external shoulder on the adjacent male threaded component, the external shoulder having a circumferentially extending stepped land, with part of the end of the female threaded component fitting around the land to hinder relative radial movement between the two ends at the position of the shoulder.
22. A female threaded end section for a percussion rock drilling tube rod, the section having a female thread, the section having an annular groove with an asymmetrical profile When seen in cross section parallel to the tube axis between the female threaded end and the opposite end to be connected to a tube rod.
23. A tube rod as claimed in Claim 1, wherein A represents the first diameter B represents the second diameter C represents the third diameter D represents the smallest internal diameter of the female threaded section E represents the core diameter of the female thread in the female threaded end, and wherein A is leas than B
B is up to 150% of E
C is 100 - 130% of E
D is 45 - 60% of E.
B is up to 150% of E
C is 100 - 130% of E
D is 45 - 60% of E.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9816494A GB2340148B (en) | 1998-07-30 | 1998-07-30 | Tube rod |
| GB9816494.0 | 1998-07-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2278987A1 true CA2278987A1 (en) | 2000-01-30 |
Family
ID=10836359
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002278987A Abandoned CA2278987A1 (en) | 1998-07-30 | 1999-07-27 | Tube rod |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0979922B1 (en) |
| AT (1) | ATE258645T1 (en) |
| CA (1) | CA2278987A1 (en) |
| GB (1) | GB2340148B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE368165T1 (en) | 2001-10-22 | 2007-08-15 | Ion Peleanu | BOREHOLE FLUID TREATMENT METHOD AND PUMP LINKAGE THEREFOR |
| SE524155C2 (en) * | 2002-05-22 | 2004-07-06 | Atlas Copco Secoroc Ab | String drill string thread for striking rock drilling |
| CN102926673A (en) * | 2012-12-02 | 2013-02-13 | 中国石油化工股份有限公司 | Destabilization-prevention oil pipe joint |
| EP3095954B1 (en) | 2015-05-22 | 2024-05-15 | Sandvik Intellectual Property AB | Drill rod or adaptor with strengthened spigot coupling |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3067593A (en) * | 1960-08-29 | 1962-12-11 | American Iron & Machine Works | Integral tool joint drill pipe |
| US4601491A (en) * | 1983-10-19 | 1986-07-22 | Vetco Offshore, Inc. | Pipe connector |
| SE8504842L (en) * | 1985-10-17 | 1987-04-18 | Santrade Ltd | DRILLING ROCK FOR BACKGROUND MOUNTING |
| US5358285A (en) * | 1992-12-03 | 1994-10-25 | Prideco, Inc. | Stress relief groove for drill pipe |
| US5355968A (en) * | 1993-05-20 | 1994-10-18 | Grant Tfw, Inc. | Tool joint stress relief groove |
| US5535837A (en) * | 1994-07-05 | 1996-07-16 | Grant Prideco, Inc. | Helical stress relief groove apparatus and method for subterranean well drill pipe assemblies |
-
1998
- 1998-07-30 GB GB9816494A patent/GB2340148B/en not_active Expired - Fee Related
-
1999
- 1999-07-26 AT AT99305930T patent/ATE258645T1/en not_active IP Right Cessation
- 1999-07-26 EP EP99305930A patent/EP0979922B1/en not_active Expired - Lifetime
- 1999-07-27 CA CA002278987A patent/CA2278987A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| GB9816494D0 (en) | 1998-09-23 |
| GB2340148B (en) | 2002-12-31 |
| EP0979922B1 (en) | 2004-01-28 |
| GB2340148A (en) | 2000-02-16 |
| EP0979922A2 (en) | 2000-02-16 |
| ATE258645T1 (en) | 2004-02-15 |
| EP0979922A3 (en) | 2001-01-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |