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
  • 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 relates to the retention of one or more elements concentrically within the bore of another element.
• abutment has comprised a retaining ring in the form of a resilient or solid circlip or segmented annulus receivable in a recess in the inner bore of a member such as a tubular member to provide the abutment or shoulder and which extends beyond the inner face of the bore to retain the element.
• a difficulty with this latter arrangement relates to the magnitude of the annular area of the bearing surface available to support the retaining ring. This is determined by the depth of the recess which is in turn governed by the wall thickness of the tubular member.
• It is an object of this invention is to provide a retention means which enables the amount of machining involved in the provision of the support for an element so that the dimensions of the abutment is minimal and machining of the one or more elements is reduced and where the degree of support can be increased without an increase in the wall thickness of the tubular member to allow a recess or abutment to be machined to provide sufficient support to receive and locate an element and retain it in the correct location for the service life of the elements.
• the invention resides in a retention means for retaining a first element of circular cross-section within a space of complementary cross-section in a second element said means comprising a plurality of axially spaced annular recesses formed in the wall of the space and a retaining ring having an axial length at least equal to the spacing between the outer edges of the outermost recesses and where the radially outermost face is of complementary profile to the profile of the wall between said outer edges, said ring having an outside diameter corresponding to the diameter of the recesses said retaining ring being in direct abutting contact with the first element.
• the retaining ring is formed of a plurality of segments.
• the retaining ring is capable of resilient radial compression to an external diameter at least equal to the internal diameter of the second element.
• One application of the invention relates to the support of components within the casing of a fluid operated down hole hammer or motor.
• Down hole hammers utilise piston type motors which develop energy levels which are usually directly related or related, in part to the diameter of the piston and piston bore of the hammer. The larger the piston bore the greater the energy potential of the motor and thus the hammer.
• In designing and manufacturing such a piston type motor for a down hole hammer it is necessary to locate or contain several internal components in specified positions within a cylindrical casing and to retain such components within the casing of the motor assembly in an exact position for the life of the unit to ensure the assembly functions correctly and its maximum efficiency.
• Such components include drill bit bushings, guides, check valves, valve bodies, air distribution valve or valve components, internal cylinders, control rod retainers, control rods, make-up components, or assemblies. These are usually located on a shoulder, abutment or a retaining ring located within the piston case or internal cylinder in order to support the item and as to retain that item and adjacent items in their exact position.
• the or each abutment, counterbore shoulder or retaining ring provide insufficient annular surface area to adequately locate or maintain the mating parts securely without premature or undue wear taking place.
• a single locating shoulder for a given wall thickness with a single retaining ring may have insufficient area and is therefore prone to deformation or wear resulting in movement and mislocation of the internal components that are located and supported by it.
• the need to form a shoulder by the machining of a counter bore at one or either end of the cylinder or piston case of sufficient area will reduce or minimise the piston bore.
• the need to machine or form a recess of sufficient depth or provide a shoulder of adequate area to locate a single retaining ring in order to locate and retain internal components will also reduce, either the size of the bore, or reduce the wall thickness of the cylinder or piston case in the region of recesses, which in turn reduces the strength of the casing and the capacity of the casing to accommodate for wear which reduces the life of the component.
• the outer face of the hammer is subject to wear and therefore the casing needs to have sufficient thickness to be able to accommodate for normal wear of the exterior face of the casing.
• the invention also resides in a down the hole hammer wherein at least some of the components are supported within the casing by a retention means of the form as described above and wherein the casing comprises the second element and the at least some components comprise the first element.
• the casing is reversible.
• the first element comprises the air delivery or valving assembly of the hammer.
• the air delivery or valving assembly is supported at one end of the hammer casing between a make-up ring and the top-sub and where the make-up ring is in direct contact with the retaining ring.
• the air delivery or valving assembly is formed with a radial flange received in a rebate provided in the abutting faces of the make-up ring and the top-sub.
• the flange can be resiliently supported within the rebate and the resilient support can comprise a resiliently compressible member located to at least one side of the flange. Alternatively the flange can be located precisely face to face contact of the components.
• the use of a retaining ring located in the internal bore of a down hole hammer cylinder or piston case where the ring has a plurality of shoulders which locate on a similar number of recesses machined in the cylinder or piston case bore avoids the need to machine a single recess of sufficient diameter to create sufficient shoulder area to support the retaining ring and to maintain the wall thickness to ensure the integrity or strength of the cylinder causing. Therefore, the load support area available to support or locate internal components can be maximised by increasing the number of recesses and shoulder in the ring for higher energy generation by the piston motor assembly.
• the retaining ring can be accurately located by means of closely machined tolerances in forming recesses and the retaining ring in order for movement of the retaining ring to be
• the plurality of shoulders provides a sufficient load area in order to minimise deformation or wear in comparison to a single shoulder or single recess. This greatly increases the life of the assembly and minimises the need to replace or repair components by maintaining the location of the components through the support provided by the retaining ring and by the retaining ring being firmly locked in the recess.
• the piston case and retaining ring can be made reversible so that wear in one direction on similarly facing shoulders of piston case recesses or shoulders on the retaining ring can be overcome by installing the retaining ring in the reverse manner. This serves in prolonging the effective file of the piston case and retaining ring and the ability to form a shoulder and locate mating components correctly.
• the piston case can be made reversible and the retaining ring will locate on shoulder recesses that have not been worn or which are worn to a lesser extent than if there had been only one locating shoulder abutment or internal recess in the piston case or cylinder.
• the retaining ring can also be machined in such a manner that the external and internal diameters can be used to locate the retaining ring concentric to the piston bore and in turn accurately align a component fitted through the centre of the retaining ring, concentric to the piston bore.
• Figure 1 is a sectional elevation of a down the hole hammer of the type described above where the components shown are supported according to the first embodiment of the invention and;
• Figure 2 is an enlarged sectional view illustrating the interengageme ⁇ t between a portion of a down the hole hammer, a make-up ring and a retaining ring according to the second embodiment.
• Figure 1 illustrates a first embodiment of the invention in use in a down the hole hammer which comprises a hammer casing 11 which supports a top-sub 12 from its one end.
• the other end (not shown) of the hammer casing 11 supports a drill chuck (not shown) and a piston (not shown) is accommodated between the top- sub 12 and the drill chuck for reciprocation in the space so defined.
• Operation of the hammer is effected by means of high pressure air which is delivered to the hammer via the top-sub 12 through a check valve assembly 1 and a control rod 13.
• the abutting ends of the check valve assembly 14 and the control rod 13 are formed with flanges 16 and 17 of corresponding diameter.
• the flanges 16 and 17 are clampingly received between the inner end of the top-sub 12 and make-up ring 18.
• the abutting faces of the top-sub 12 and the make-up ring 18 are each formed with a recess 19 and 20 at their inner edges and the flanges 16 and 17 of the check valve assembly and control rod are received in the recesses which have a diameter corresponding to the diameter of the flanges.
• a compressible ring 21 and 22 is received in each recess 19 and 20, to each side of the flange.
• a pair of closely adjacent annular recesses 23 and 24 are formed in the wall of the hammer casing 11.
• the recesses receive and support a retaining ring 25 which has an outer surface defined by a pair of annular ribs 26 and 27 each having an outer diameter corresponding to the inner diameter of the recesses 23 and 24.
• the retaining ring 25 has an inner diameter which is less than the inner diameter of the hammer casing 11 such that it extends into the space
• the retaining ring 25 is formed of two semicircular segments to facilitate its location in the recess 22 during assembly of the hammer.
• the external face of the make-up ring is formed with an annular rebate 30 which is received over the retaining ring 23 whereby the inner face of the retaining ring is snugly received against the radial face of the rebate.
• the axial faces of the retaining ring 23 are tapered inwardly and the inner end of the rebate 30 is of complementary profile which ensures positive interengagement between the make-up ring and retaining ring on the top-sub being tightened against the make-up ring.
• each of the axial faces 31 and 32 of each rib 26 and 27 provide a bearing surface for the retaining ring 23 and thus serve to increase
• the depth of the recesses accommodating the retaining ring can be reduced while ensuring the bearing surface is of an adequate area to provide the required support for the anticipated forces to be borne by the bearing surface.
• the bearing surface area can be increased even though the depth of the recesses is reduced in comparison to conventional retaining rings This can enable the use of a cylinder casing having a thinner wall that would be the case where conventional retaining rings were used.
• the hammer casing may be formed with an uncontoured bore with the exception of the recess 22 and if desired may be made to be reversible by providing a set of recesses at each end of the casing.
• the only machining required relates to the formation of the recesses.
• the number of recesses may be increased beyond the two as described in relation to the embodiment to increase the surface area of the bearing surface and/or reduce the depth the recesses.
• Figure 2 illustrates a second embodiment of the invention in use in the make-up assembly of a down the hole hammer.
• the arrangement is of the same form as shown in Figure 1.
• the difference however in the case of the second embodiment comprises the provision of a stepped axial face 33 and 34 to each side of the retaining ring which can each be received in a complementary rebate 30 formed in the make-up ring and the absence of a tapered external face.
• the scope of the present invention need not be limited to the particular scope of the embodiments described above and in particular can relate to any situation where a shoulder or abutment is required to support a component in a bore or cylinder of a down hole hammer at any location with that bore or cylinder or any like location.
• the invention can have application in containing components within the casing of the hammer such; as drill bit supports; cylinders or internal sleeves; valve bodies or air distribution bodies; make-up components as well as control rods or valves stems or feed tubes and top-subs as described in relation to the embodiments referred to above.
• Provision of a retaining ring which is supported within the casing by a plurality of recesses not only serves to increase the support area for the retaining ring but also, facilitates an increase in the internal bore of the hammer, which in turn enables maximisation of the diameter of the piston and therefore the effectiveness of the hammer. There is also the ability to be able to reduce the wall thickness of the cylinder case and to be able to manufacture the cylinder to be reversible.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Percussive Tools And Related Accessories (AREA)

Applications Claiming Priority (5)

Publications (2)

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• 1996
  • 1996-03-20 EP EP96905605A patent/EP0821767A4/de not_active Withdrawn
  • 1996-03-20 WO PCT/AU1996/000153 patent/WO1996029520A1/en not_active Application Discontinuation
  • 1996-03-21 AR AR33584496A patent/AR001384A1/es unknown

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Non-Patent Citations (1)

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