EP0011219B1 - Connection of fluid flow path-defining components in down-the-hole hammer drills - Google Patents
Connection of fluid flow path-defining components in down-the-hole hammer drills Download PDFInfo
- Publication number
- EP0011219B1 EP0011219B1 EP79104336A EP79104336A EP0011219B1 EP 0011219 B1 EP0011219 B1 EP 0011219B1 EP 79104336 A EP79104336 A EP 79104336A EP 79104336 A EP79104336 A EP 79104336A EP 0011219 B1 EP0011219 B1 EP 0011219B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hammer drill
- tube
- components
- drill according
- component
- 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.)
- Expired
Links
- 239000012530 fluid Substances 0.000 title claims abstract description 16
- 238000007789 sealing Methods 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims description 13
- 238000010276 construction Methods 0.000 description 5
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- 239000004033 plastic Substances 0.000 description 4
- 229920003023 plastic Polymers 0.000 description 4
- 239000002131 composite material Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920004943 Delrin® Polymers 0.000 description 1
- 229920002430 Fibre-reinforced plastic Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000012858 resilient material Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
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
- E21B17/07—Telescoping joints for varying drill string lengths; Shock absorbers
-
- 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
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
Definitions
- This invention concerns the connection of fluid flow path-defining components in fluid-powered, free piston, down-the-hole hammer drills.
- the invention is especially concerned with the establishment of reliable fluid-tight connections between such components, notwithstanding the high stress and vibration levels to which the components are subject in operation of the drill.
- a piston In a down-the-hole rock drill hammer unit, a piston is caused to reciprocate within a cylinder and to deliver blows to an anvil surface on a bit shank.
- the reciprocation of the piston is accomplished by alternately admitting pressure fluid such as compressed air to working chambers at opposite ends of the cylinder, this admission of pressure fluid to the working chambers, and the exhaust of fluid from these chambers, being controlled at least partly by the motion of the piston within the cylinder and relative to ports formed in the cylinder wall and/or in the piston or in a tube extending therein or therethrough.
- pressure fluid such as compressed air
- certain of the fluid flow paths involve tubes that extend within the device and that are connected to or closely associated with components subject to high levels of stress and/or vibration.
- the piston may carry a tube that extends from one or other end thereof so as to reciprocate with the piston and enter passages in a related component to accomplish a fluid control function during parts of the travel of the piston within the cylinder.
- the piston reciprocates relatively to a central tube that is fixed at one or other of its ends and has ports that communicate with the working chambers in accordance with the position of the piston relatively to the tube.
- a tube is fixed within one or other of the working chambers to enter a passage in the piston for part of the cycle of motion of the latter: a typical instance of this latter arrangement is the so- called foot valve that comprises a tube fixed to a central exhaust passage in the bit shank of a hammer drill and that co-operates with the piston to control the exhaust of pressure fluid from the working chambers.
- An object of the present invention is therefore to provide an interconnection system that avoids the difficulties experienced hitherto in the above discussed situations and that is simple and economical to manufacture.
- a fluid-powered free piston down-the-hole hammer drill comprising fluid flow path-defining components including inner and outer components having adjacent overlapping surfaces is characterised in that each of said overlapping surfaces is formed with at least one circumferential recess, the recesses in the respective components being opposed and together defining an annular space within which an elastomeric sealing/retaining ring is accommodated.
- the overlapping surfaces of the two components are a close fit one within the other and the or each said recess in one such surface is of greater depth than the corresponding recess in the other surface, whereby the or each sealing/ retaining ring is accommodated mainly in the deeper recess so as to facilitate assembly of the connection by telescopic movement of the components relative to one another.
- the over- lappping surfaces may be dimensioned to have an interference fit, but in preferred embodiments they are dimensioned to have a sliding fit.
- each component is formed with a plurality of said recesses so that there are a plurality of spaced-apart annular spaces each accommodating an elastomeric sealing/retaining ring, the plurality of sealing/retaining rings thus providing both a plural seal structure for preventing flow of fluid between the overlapping surfaces, and spaced-apart resilient connections that distribute stresses between the components and also serve to maintain alignment thereof.
- the elastomeric sealing/retaining rings are 0- rings, but rings of other configuration may be employed: in particular, rings of non-circular section may be employed in recesses shaped to co-operate with such rings to provide enhanced sealing performance.
- each elastomeric sealing/retaining ring may be a free element fixed to neither of the components.
- such a ring may be fixed, e.g. by adhesive bonding, in the accommodating recess of one of om the components prior to assembly of the interconnection.
- the components may be formed of any desired materials and may be of the same or of different materials.
- One or the other or both of the components may be of composite construction to provide required properties of structural strength and flexibility or resilience.
- the inner component may have a tapered lead-in to its surface formed with the or each said recess therein. That surface may itself initially be tapered, or the component may be formed to permit such surface to distort to tapered form in the course of assembly, provision being made to distort or restore the shape of the surface after assembly, to a configuration matching the complementary overlapping surface of the outer component.
- the inner component comprises a tube one extremity of which is formed with circumferential recesses and a tapered lead-in, the wall thickness of the tube in the region of this end being such as to enable the tube to distort upon assembly to permit the tube end satisfactorily to enter the outer component having its recesses fitted with elastomeric sealing/ retaining rings.
- a plug for instance, a screw-threaded plug, into the tube end following assembly may then serve to restore the tube end to its initial configuration so that its external surface matches that of the outer component into which is has been so fitted.
- the sealing/retaining ring or rings may be placed under substantial radial compression in the fully assembled interconnection, to achieve a required sealing and/or retaining performance.
- An exhaust tube 7 is fitted to the bore of the valve bottom 5 by an interconnection embodying the present invention and consisting of circumferential recesses in the overlapping surfaces of the bore of the valve bottom 5 and of the exhaust tube 7, respectively, the recesses in these components together defining a series of five annular spaces that accommodate elastomeric sealing/retaining rings 8.
- valve bottom 5 is best seen in Figures 2 and 3 that show the bore to be of untapered cylindrical configuration formed with recesses 9 of rectangular cross-section. The internal corners of the recess cross-section are radiussed and the edges at the bore surface are relieved to avoid sharp corners and edges.
- This valve bottom 5 is formed of steel, case-hardened after all machining operations have been completed.
- FIG 4 shows the form of the exhaust tube 7 prior to assembly.
- This tube is formed of a high strength plastics material such as carbon fibre or glass fibre reinforced plastic, or of a material such as the acetal plastics material sold by DuPont under the Trade Mark “Delrin”.
- the tube has an end portion 10 formed with five part-circular section circumferential recesses 11 at intervals corresponding with the spacing of the recesses 9 in the bore of the valve bottom 5.
- the recesses 9 in the bore of the valve bottom 5 are of substantially greater depth than the recesses 11 on the exhaust tube 7.
- the elastomeric sealing/ retaining rings 8 are mainly accommodated in the recesses 9 and will be reliably retained in their respective recesses during assembly of the interconnection by endwise introduction of the exhaust tube 7 into the bore of the valve bottom.
- the different shapes of the cross- sections of the respective recesses also ensure retention of the sealing/retaining rings 8 during assembly, and ease the assembly operation.
- the end portion 10 of the tube 7, apart from the lead-in 12, is of untapered cylindrical form with an overall diameter such as to provide a sliding fit with the bore of the valve bottom 5.
- the elastomeric sealing/ retaining rings 8, suitably O-rings are fitted to the recesses 9 of the valve bottom bore whereafter the exhaust tube 7 is forced endwise into position in the bore.
- a suitable lubricant is applied to the tube and to the sealing ring-fitted valve bottom bore: the lubricant may be a light oil or a soap or like solution.
- the sealing/retaining rings 8 in the assembled condition of the parts as illustrated in Figures 1 and 2 provide multiple stress paths between the inner component constituted by the exhaust tube 7 and the outer component constituted by the valve bottom 5. These rings also provide multiple seals against leakage between these components and thus reliably hold the tube 7 in place in the valve bottom, notwithstanding high levels of vibration to which the components are subjected during operation, while preventing leakage of pressure fluid from the region of the valve 4 along the outer wall of the tube 7.
- Figure 5 illustrates schematically and in axial section part of the leading end of a down-the-hole hammer drill unit of the valveless type and having a foot valve arrangement involving an interconnection embodying the invention.
- the bit shank 22 is formed with an exhaust passage 25 that extends to outlets in the bit head (not shown) and that is fitted with a foot valve tube 26 that enters a bore in the piston 21 as this approaches its illustrated power stroke-end position, so as to cut off the exhaust flow path for air in the adjacent working chamber of the cylinder whilst providing a flow path for exhaust of air through the piston from the working chamber at the other end of the cylinder defined by the casing 20.
- the foot valve 26, because it is fixed to the bit shank and protrudes from the anvil surface thereof, experiences intense shock and vibration loading in the region of its connection to the bit shank.
- the interconnection arrangement of the invention is therefore well suited to securing the foot valve tube 26 in the bit shank.
- Figure 6 illustrates one constructional form of this interconnection and it will be seen that in this case the foot valve tube 26 is formed with rectangular cross-section circumferential recesses that oppose part-circular section circumferential recesses in an enlarged portion of the bore 25 of the bit shank, the opposed recesses together defining a series of spaced-apart annular spaces each accommodating an elastomeric sealing/retaining ring 27.
- the tube 26 may be made of any suitable material and if desired may be fitted, after assembly, with a pressed-in sleeve to remove any inwards distortion of the tube caused during assembly and to ensure a required fit between the tube and the bore of the bit shank.
- Figure 7 illustrates another construction in which the foot valve tube is of composite configuration, having an end portion 26a formed of one material, for instance metal, and constituting the inner component of the interconnection, and an extension portion 26b formed of a different material (e.g. a plastics material) and suitably attached to the end portion 26a, before or after fitment of the latter to the bit shank 22.
- the composite construction of the foot valve tube in Figure 7 enables the respective portions thereof to be formed of materials chosen to provide the required properties in those portions of the tube.
- the end portion 26a may be formed of metal to provide appropriate rigidity to withstand stresses transmitted through the sealing/retaining rings 27, whereas the portion 26b may be of a material chosen to provide appropriate resilience to seal within the piston bore and to tolerate slight misalignments between the bit and the piston, and/or to be of low mass.
- the portion 26a might be made of a plastics material and the portion 26b of metal, to provide appropriate properties to meet certain performance requirements: for instance to enable the components to withstand the erosion effects that result from water injection.
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- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
- Mutual Connection Of Rods And Tubes (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
- Glass Compositions (AREA)
- Branch Pipes, Bends, And The Like (AREA)
Abstract
Description
- This invention concerns the connection of fluid flow path-defining components in fluid-powered, free piston, down-the-hole hammer drills.
- The invention is especially concerned with the establishment of reliable fluid-tight connections between such components, notwithstanding the high stress and vibration levels to which the components are subject in operation of the drill.
- In a down-the-hole rock drill hammer unit, a piston is caused to reciprocate within a cylinder and to deliver blows to an anvil surface on a bit shank. The reciprocation of the piston is accomplished by alternately admitting pressure fluid such as compressed air to working chambers at opposite ends of the cylinder, this admission of pressure fluid to the working chambers, and the exhaust of fluid from these chambers, being controlled at least partly by the motion of the piston within the cylinder and relative to ports formed in the cylinder wall and/or in the piston or in a tube extending therein or therethrough. There may be further control of the fluid flows by a valve system or the arrangement may be "valveless" and rely entirely on the motion of the piston relative to other components to accomplish the necessary control of fluid flows into and out of the working chambers.
- In many such hammer drills and similar fluid-powered free-piston devices, certain of the fluid flow paths involve tubes that extend within the device and that are connected to or closely associated with components subject to high levels of stress and/or vibration. For instance, the piston may carry a tube that extends from one or other end thereof so as to reciprocate with the piston and enter passages in a related component to accomplish a fluid control function during parts of the travel of the piston within the cylinder. In other cases the piston reciprocates relatively to a central tube that is fixed at one or other of its ends and has ports that communicate with the working chambers in accordance with the position of the piston relatively to the tube. In yet other cases a tube is fixed within one or other of the working chambers to enter a passage in the piston for part of the cycle of motion of the latter: a typical instance of this latter arrangement is the so- called foot valve that comprises a tube fixed to a central exhaust passage in the bit shank of a hammer drill and that co-operates with the piston to control the exhaust of pressure fluid from the working chambers.
- It is a common experience in the operation of such hammer drills that such fluid-conveying tubes as above discussed are prone to failure at their connections to the components to which they are fixed. It is therefore common to adopt connection arrangements that involve the interposition of resilient material to damp the transmission of vibration energy between the respective parts and to effect fluid-tight sealing of the connection. However, the arrangements hitherto used or proposed have in general been rather complex and difficult to manufacture and/or involve problems of assembly in manufacture, so leading to difficulties in servicing in the field, or have shown a lack of reliability in service.
- An object of the present invention is therefore to provide an interconnection system that avoids the difficulties experienced hitherto in the above discussed situations and that is simple and economical to manufacture.
- In accordance with the invention, a fluid-powered free piston down-the-hole hammer drill comprising fluid flow path-defining components including inner and outer components having adjacent overlapping surfaces is characterised in that each of said overlapping surfaces is formed with at least one circumferential recess, the recesses in the respective components being opposed and together defining an annular space within which an elastomeric sealing/retaining ring is accommodated.
- In preferred embodiments of the invention, the overlapping surfaces of the two components are a close fit one within the other and the or each said recess in one such surface is of greater depth than the corresponding recess in the other surface, whereby the or each sealing/ retaining ring is accommodated mainly in the deeper recess so as to facilitate assembly of the connection by telescopic movement of the components relative to one another. The over- lappping surfaces may be dimensioned to have an interference fit, but in preferred embodiments they are dimensioned to have a sliding fit.
- Preferably the overlapping surface of each component is formed with a plurality of said recesses so that there are a plurality of spaced-apart annular spaces each accommodating an elastomeric sealing/retaining ring, the plurality of sealing/retaining rings thus providing both a plural seal structure for preventing flow of fluid between the overlapping surfaces, and spaced-apart resilient connections that distribute stresses between the components and also serve to maintain alignment thereof.
- In preferred embodiments of the invention the elastomeric sealing/retaining rings are 0- rings, but rings of other configuration may be employed: in particular, rings of non-circular section may be employed in recesses shaped to co-operate with such rings to provide enhanced sealing performance.
- The or each elastomeric sealing/retaining ring may be a free element fixed to neither of the components. However in some embodiments such a ring may be fixed, e.g. by adhesive bonding, in the accommodating recess of one of om the components prior to assembly of the interconnection.
- The components may be formed of any desired materials and may be of the same or of different materials. One or the other or both of the components may be of composite construction to provide required properties of structural strength and flexibility or resilience.
- To facilitate assembly of the interconnection, the inner component may have a tapered lead-in to its surface formed with the or each said recess therein. That surface may itself initially be tapered, or the component may be formed to permit such surface to distort to tapered form in the course of assembly, provision being made to distort or restore the shape of the surface after assembly, to a configuration matching the complementary overlapping surface of the outer component.
- Thus, for instance, in one embodiment of the invention, the inner component comprises a tube one extremity of which is formed with circumferential recesses and a tapered lead-in, the wall thickness of the tube in the region of this end being such as to enable the tube to distort upon assembly to permit the tube end satisfactorily to enter the outer component having its recesses fitted with elastomeric sealing/ retaining rings. Introduction of a plug, for instance, a screw-threaded plug, into the tube end following assembly may then serve to restore the tube end to its initial configuration so that its external surface matches that of the outer component into which is has been so fitted.
- By such expedients, the sealing/retaining ring or rings may be placed under substantial radial compression in the fully assembled interconnection, to achieve a required sealing and/or retaining performance.
- Some embodiments of the invention are illustrated by way of example in the accompanying drawings in which:
- FIGURES 1 A and 1B together constitute a part-sectional elevation of a down-the-hole hammer drill unit embodying the invention;
- FIGURE 2 is an enlargement of part of Figure 1A;
- FIGURE 3 is an axial section of the valve part constituting the outer component of the interconnection embodied in the drill unit;
- FIGURE 4 is an axial section of the exhaust tube constituting the inner component of the interconnection embodied in the drill unit:
- FIGURE 5 is a partly schematic axial section of part of another down-the-hole hammer drill unit embodying the invention;
- FIGURE 6 shows in axial section one construction of the foot valve, embodying the invention, in the drill unit of Figure 5; and
- FIGURE 7 illustrates another construction of the foot valve, embodying the invention, of the drill unit of Figure 5.
- The hammer drill unit illustrated in Figures 1A and 1B comprises a
casing 1 fitted with aline 1 a within which a piston 2 is reciprocable to deliver blows on the anvil surface at the end of a bit shank, the reciprocation of the piston 2 being effected by the admission of compressed air alternately to workingchambers liner 1 a under the control of a valve mechanism including avalve element 4. Thevalve element 4 reciprocates within a valve structure including avalve bottom 5 that fits partly within the adjacent end of theliner 1 a and has through-flow passages 6 and a central bore. - An
exhaust tube 7 is fitted to the bore of thevalve bottom 5 by an interconnection embodying the present invention and consisting of circumferential recesses in the overlapping surfaces of the bore of thevalve bottom 5 and of theexhaust tube 7, respectively, the recesses in these components together defining a series of five annular spaces that accommodate elastomeric sealing/retaining rings 8. - The configuration of the
valve bottom 5 is best seen in Figures 2 and 3 that show the bore to be of untapered cylindrical configuration formed withrecesses 9 of rectangular cross-section. The internal corners of the recess cross-section are radiussed and the edges at the bore surface are relieved to avoid sharp corners and edges. Thisvalve bottom 5 is formed of steel, case-hardened after all machining operations have been completed. - Figure 4 shows the form of the
exhaust tube 7 prior to assembly. This tube is formed of a high strength plastics material such as carbon fibre or glass fibre reinforced plastic, or of a material such as the acetal plastics material sold by DuPont under the Trade Mark "Delrin". As shown the tube has anend portion 10 formed with five part-circular sectioncircumferential recesses 11 at intervals corresponding with the spacing of therecesses 9 in the bore of thevalve bottom 5. - It will be observed that the
recesses 9 in the bore of thevalve bottom 5 are of substantially greater depth than therecesses 11 on theexhaust tube 7. Thus the elastomeric sealing/retaining rings 8 are mainly accommodated in therecesses 9 and will be reliably retained in their respective recesses during assembly of the interconnection by endwise introduction of theexhaust tube 7 into the bore of the valve bottom. The different shapes of the cross- sections of the respective recesses also ensure retention of the sealing/retaining rings 8 during assembly, and ease the assembly operation. - The extremity of the
exhaust tube 7 has a tapered lead-in 12 and theend portion 10 of the tube has a central bore that is formed with atapered screw thread 13 for part of its length. - As initially formed, the
end portion 10 of thetube 7, apart from the lead-in 12, is of untapered cylindrical form with an overall diameter such as to provide a sliding fit with the bore of thevalve bottom 5. In assembling the interconnection between the exhaust tube and the valve bottom, the elastomeric sealing/retaining rings 8, suitably O-rings, are fitted to therecesses 9 of the valve bottom bore whereafter theexhaust tube 7 is forced endwise into position in the bore. To assist the introduction of thetube 7 into the bore a suitable lubricant is applied to the tube and to the sealing ring-fitted valve bottom bore: the lubricant may be a light oil or a soap or like solution. - Under the compressive loads imposed upon the
tube end portion 10 by the sealing/retaining rings 8 as the tube is forced into position and therings 8 ride over the lands between therecesses 11, thetube end portion 10 tends to distort and take a slight taper "set". Accordingly, when thetube 7 has been forced fully into place with itsrecesses 11 aligned with thecorresponding recesses 9 of the valve bottom bore, a screw-threadedplug 14 is screwed into the bore of theend portion 10 and because of the taper of thescrew thread 13 in that bore, causes progressive expansion of thetube end portion 10 into close conformity with the bore of the valve bottom. - The sealing/
retaining rings 8 in the assembled condition of the parts as illustrated in Figures 1 and 2 provide multiple stress paths between the inner component constituted by theexhaust tube 7 and the outer component constituted by thevalve bottom 5. These rings also provide multiple seals against leakage between these components and thus reliably hold thetube 7 in place in the valve bottom, notwithstanding high levels of vibration to which the components are subjected during operation, while preventing leakage of pressure fluid from the region of thevalve 4 along the outer wall of thetube 7. - Figure 5 illustrates schematically and in axial section part of the leading end of a down-the-hole hammer drill unit of the valveless type and having a foot valve arrangement involving an interconnection embodying the invention.
- The drill unit illustrated in this Figure 5 comprises a
casing 20 defining a cylinder within which apiston 21 is reciprocable to deliver blows on the anvil surface at the end of abit shank 22 so secured in the end of thecasing 20 by means of achuck 23 and a retaining and sealingring 24 as to have limited freedom for axial movement relatively to thecasing 20. Thebit shank 22 is formed with anexhaust passage 25 that extends to outlets in the bit head (not shown) and that is fitted with afoot valve tube 26 that enters a bore in thepiston 21 as this approaches its illustrated power stroke-end position, so as to cut off the exhaust flow path for air in the adjacent working chamber of the cylinder whilst providing a flow path for exhaust of air through the piston from the working chamber at the other end of the cylinder defined by thecasing 20. - The
foot valve 26, because it is fixed to the bit shank and protrudes from the anvil surface thereof, experiences intense shock and vibration loading in the region of its connection to the bit shank. The interconnection arrangement of the invention is therefore well suited to securing thefoot valve tube 26 in the bit shank. - Figure 6 illustrates one constructional form of this interconnection and it will be seen that in this case the
foot valve tube 26 is formed with rectangular cross-section circumferential recesses that oppose part-circular section circumferential recesses in an enlarged portion of thebore 25 of the bit shank, the opposed recesses together defining a series of spaced-apart annular spaces each accommodating an elastomeric sealing/retaining ring 27. Thetube 26 may be made of any suitable material and if desired may be fitted, after assembly, with a pressed-in sleeve to remove any inwards distortion of the tube caused during assembly and to ensure a required fit between the tube and the bore of the bit shank. - Figure 7 illustrates another construction in which the foot valve tube is of composite configuration, having an
end portion 26a formed of one material, for instance metal, and constituting the inner component of the interconnection, and anextension portion 26b formed of a different material (e.g. a plastics material) and suitably attached to theend portion 26a, before or after fitment of the latter to thebit shank 22. The composite construction of the foot valve tube in Figure 7 enables the respective portions thereof to be formed of materials chosen to provide the required properties in those portions of the tube. Thus theend portion 26a may be formed of metal to provide appropriate rigidity to withstand stresses transmitted through the sealing/retainingrings 27, whereas theportion 26b may be of a material chosen to provide appropriate resilience to seal within the piston bore and to tolerate slight misalignments between the bit and the piston, and/or to be of low mass. Alternatively, theportion 26a might be made of a plastics material and theportion 26b of metal, to provide appropriate properties to meet certain performance requirements: for instance to enable the components to withstand the erosion effects that result from water injection.
Claims (10)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT79104336T ATE3574T1 (en) | 1978-11-10 | 1979-11-06 | CONNECTING THE LIQUID CONTAINING PARTS OF DUCK HOLE DRILLS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB4412878 | 1978-11-10 | ||
GB7844128 | 1978-11-10 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0011219A1 EP0011219A1 (en) | 1980-05-28 |
EP0011219B1 true EP0011219B1 (en) | 1983-05-25 |
Family
ID=10500973
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP79104336A Expired EP0011219B1 (en) | 1978-11-10 | 1979-11-06 | Connection of fluid flow path-defining components in down-the-hole hammer drills |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP0011219B1 (en) |
JP (1) | JPS5575092A (en) |
AT (1) | ATE3574T1 (en) |
DE (1) | DE2965531D1 (en) |
ES (1) | ES485775A0 (en) |
IN (1) | IN152190B (en) |
ZA (1) | ZA795944B (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080099218A1 (en) * | 2006-10-26 | 2008-05-01 | Sandvik Intellectual Property Ab | Air actuated down-the-hole hammer for rock drilling, a drill bit and a foot valve to be used in the down-the-hole hammer |
AU2014202538B2 (en) * | 2013-05-10 | 2018-03-08 | Tricon Drilling Solutions Pty Ltd | Percussive Down-The-Hole Drill |
EP2873799B1 (en) * | 2013-11-18 | 2017-06-14 | Sandvik Intellectual Property AB | Down-the-hole hammer drill bit assembly |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1278127A (en) * | 1968-08-15 | 1972-06-14 | Mission Mfg Co | Improvements relating to percussion tools |
US3791462A (en) * | 1972-03-29 | 1974-02-12 | A Curington | Percussion anvil bits |
US3866746A (en) * | 1973-08-27 | 1975-02-18 | Bakerdrill Inc | Rotary bore hole air hammer drive mechanism |
US3871486A (en) * | 1973-08-29 | 1975-03-18 | Bakerdrill Inc | Continuous coring system and apparatus |
DE2551292C3 (en) * | 1975-11-14 | 1980-03-27 | Institut Gornogo Dela Sibirskogo Otdelenija Akademii Nauk Ssr, Nowosibirsk (Sowjetunion) | Compressed air operated deep hole hammer drill |
DE2609376C3 (en) * | 1976-03-06 | 1978-09-07 | H.P. Walter Gmbh + Co Drucklufttechnik Kg, 3570 Stadt Allendorf | Downhole hammer |
DE2816737C3 (en) * | 1978-04-18 | 1981-03-19 | Hans Philipp 3570 Stadtallendorf Walter | Rotary hammer, especially deep-hole hammer |
-
1979
- 1979-11-06 DE DE7979104336T patent/DE2965531D1/en not_active Expired
- 1979-11-06 ZA ZA00795944A patent/ZA795944B/en unknown
- 1979-11-06 EP EP79104336A patent/EP0011219B1/en not_active Expired
- 1979-11-06 AT AT79104336T patent/ATE3574T1/en active
- 1979-11-07 ES ES485775A patent/ES485775A0/en active Granted
- 1979-11-09 IN IN1169/CAL/79A patent/IN152190B/en unknown
- 1979-11-10 JP JP14597379A patent/JPS5575092A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
ES8100418A1 (en) | 1980-11-01 |
ZA795944B (en) | 1980-11-26 |
EP0011219A1 (en) | 1980-05-28 |
ES485775A0 (en) | 1980-11-01 |
IN152190B (en) | 1983-11-12 |
ATE3574T1 (en) | 1983-06-15 |
JPS5575092A (en) | 1980-06-06 |
DE2965531D1 (en) | 1983-07-07 |
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