Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B21/00—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings
  • F16B21/10—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts
  • F16B21/20—Means for preventing relative axial movement of a pin, spigot, shaft or the like and a member surrounding it; Stud-and-socket releasable fastenings by separate parts for bolts or shafts without holes, grooves, or notches for locking members
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B2/00—Friction-grip releasable fastenings
  • F16B2/20—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening
  • F16B2/22—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening of resilient material, e.g. rubbery material
  • F16B2/24—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening of resilient material, e.g. rubbery material of metal
  • F16B2/241—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening of resilient material, e.g. rubbery material of metal of sheet metal
  • F16B2/245—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening of resilient material, e.g. rubbery material of metal of sheet metal external, i.e. with contracting action
  • F16B2/246—Clips, i.e. with gripping action effected solely by the inherent resistance to deformation of the material of the fastening of resilient material, e.g. rubbery material of metal of sheet metal external, i.e. with contracting action the clip being released by tilting the clip or a part thereof to a position in which the axis of the openings surrounding the gripped elements is parallel to, or coincides with, the axis of the gripped elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L3/00—Supports for pipes, cables or protective tubing, e.g. hangers, holders, clamps, cleats, clips, brackets
  • F16L3/08—Supports for pipes, cables or protective tubing, e.g. hangers, holders, clamps, cleats, clips, brackets substantially surrounding the pipe, cable or protective tubing
  • F16L3/12—Supports for pipes, cables or protective tubing, e.g. hangers, holders, clamps, cleats, clips, brackets substantially surrounding the pipe, cable or protective tubing comprising a member substantially surrounding the pipe, cable or protective tubing
  • F16L3/133—Supports for pipes, cables or protective tubing, e.g. hangers, holders, clamps, cleats, clips, brackets substantially surrounding the pipe, cable or protective tubing comprising a member substantially surrounding the pipe, cable or protective tubing and hanging from a pendant

Definitions

• This invention relates more particularly but not exclusively to a retaining ring of a type which is referred to in the art as a 'push-on fix' and which may be introduced axially onto a shaft to firmly grip the shaft (hereinafter referred to as Of the type specified').
• Push-on fixes of the type specified are designed to fulfill certain performance requirements and to withstand axial forces which may be exerted on the fix (in a direction reverse to the introduction direction of the fix on the shaft) after it has been attached onto a shaft.
• the axial force which can be exerted on a push-on fix when attached to a shaft of appropriate size without the fix 'yielding' and then being urged off the shaft will vary somewhat depending upon the hardness value of the shaft.
• the push-on fix may be of carbon spring steel, beryllium copper, phosphor bronze or stainless steel.
• Shafts of high hardness value include cold-rolled steel shafts. Hitherto pushr-on fixes have been made which have a yield point somewhere around IKN.
• a retaining ring comprising a plurality of radially inwardly directed legs or teeth to grip onto a shaft and thereby attach the ring to the shaft on introducing the ring generally axially onto the shaft, the thicknesses of the legs or teeth being so selected relative to their radial extent - and the relative dimensions of the retaining ring being so selected relative to shaft size that the ring is adapted to withstand an axial force in the direction reverse to the introduction direction of the ring on the shaft of at least 4KN before yielding.
• the push-on fix may be such that the yield force lies in the 0 range 4KN to about 9KN and/or the ratio L/t 2 may have a value less than 1.5.
• the thickness of the push-on fix may be about 0.9 mm (in the order of twice the thickness of conventional push-on fixes which may 5 vary from 0.23mm up to 0.5mm over the whole size range of fixes) and/or the radial extent of each tooth may be about 1.1 mm (in the order of 1/3 radial extent of teeth of most conventional fixes).
• the external diameter of the push-on fix may be 20mm (conventional tooth length for a fix of this size is about 0.38mm). 0
• the push on fix may be provided with three equiangularly spaced teeth or legs and/or the legs may extend at an angle of about 45° ( ⁇ 5°) to the general plane of the push-on fix.
• the shaft may have a Vickers hardness value of 250 to 300 and/or the ring may be fitted on the shaft with an interference fit of 0.38mm.
• a retaining ring comprising a plurality of radially outwardly directed legs or teeth to grip into a bore and thereby attach the ring to the bore on introducing the ring generally axially into the bore, the thicknesses of the legs or teeth being so selected relative to their radial extent and the relative dimensions of the retaining ring being so selected relative to bore size that the ring is adapted to withstand an axial force in the direction reverse to the introduction direction of the ring into the bore of at least 4KN before yielding.
• the material of the bore may have a Vickers hardness value of 250 and /or or each leg or tooth may be provided with an arcuate end surface.
• the legs or teeth will be of the same material thickness and dimensions and equiangularly spaced; the material thickness will be the same as the material thickness of the ring.
• FIGURE 1 shows a plan or axial view of the retaining ring
• FIGURE 2 shows a front or radial view of the retaining ring
• FIGURE 3 shows a detail cross sectional view taken on line III— III of FIGURE 1;
• FIGURE 4 shows an experimental graph of a load test done on the retaining ring
• FIGURE 6 shows a theoretical graph of the variation in push-off yield force with L for a constant t and also the variation of push-off yield force with t for a constant L
• FIGURE 7 shows a theoretical graph of variation in push off yield force with material thickness for a range of tooth lengths
• FIGURE 8 shows a theoretical graph of variation in push off yield force with tooth lengths for a range of material thickness.
• FIGURES 1 to 3 show a retaining ring or push-on fix 1 of carbon spring steel having three equidistantly spaced radially inwardly directed legs or teeth 2.
• FIGURES 1 and 2 are drawn twice full size and the external diameter of the push-on fix is 20 mm.
• FIGURE 3 is drawn four times full size.
• the push-on fix is designed to be attached to a generally cylindrical shaft (not shown) of diameter 11.76 mm.
• Each tooth 2 is provided with an arcuate end surface 3 which engages the circular periphery of the shaft.
• Each tooth 2 gradually tapers radially inwardly and has a mean tooth width b (see FIGURE 2).
• the thickness of the fix 1 is designated t and the radial extent of each tooth is designated L.
• the push on fix 1 was attached to the shaft by using a standard assembly tool (not shown) to introduce the fix generally axially onto the shaft in the direction of arrow A (see FIGURE 2).
• a standard load test was carried on the push on fix 1 whilst attached to the shaft and as can be seen from FIGURE 4 the push-on fix withstood a force of 8.7 KN in a direction reverse to arrow A before 'yielding' and then becoming detached from the shaft.
• the teeth 2 are effectively pulled inside out or over centre during the test and a further lesser force is required to push the fix 1 off the shaft once l ⁇ the fix has 'yielded' or failed (yield point).
• FIGURE 4 shows a graph of the push-off force applied P (plotted along the vertical axis) and displacement (initially of the
• the thicknesses of the teeth 2 of the push on fix 1 may be selected relative to their radial extent and the relative dimensions of the shaft so selected that the push-on fix engagement with the shaft can withstand much greater axial forces than conventional push- 5 on fixes.
• the push on fixes in accordance with the present invention will still operate in the elastic mode, but a conventional fix will take a set.
• the tooth deflection is of the same order as the dig-in on the shaft and the deflection due to coning is relatively small.
• the ratio L/ t becomes small, tooth deflection becomes small in comparison with dig- in.
• a value of t close to unity gives a tooth deflection only 1% of the dig-in value.
• the above equations were checked against experimental push-off yield force values. Measured values were up to 25% higher than the theoretical values, probably due to the way in which the teeth tend to dig in even deeper as attempts are made to push the fix off.
• the fix flattens, so gripping the shaft more tightly, and the angle of the teeth (approximately 45°) is such that they tend to dig into the shaft rather than pull off.
• the push-on fix 1 When the push-on fix 1 is fitted on a shaft , the legs bend and the fix cones in the same way as a Belleville washer. In conventional designs of push-on fix, bending of the legs is the main mode of deflection, and coning is relatively unimportant. In the push-on fix in accordance with the present invention, they are of the same order of magnitude.
• the teeth 2 grip the shaft and tend to dig into the shaft material. In the fix 1 there is relatively little deflection of the teeth 2 and so the gripping force is higher and the amount of dig-in larger.
• FIGURE 5 shows a plot of variation of push-off yield force P (in KN) with L/t 2 according to the theoretical model described. This model is based on the push on fix shown in FIGURES 1 to 3 which has an external diameter of 20 mm, an internal diameter of 11 mm, three teeth and a 0.38 mm interference on the shaft.
• FIGURE 5 illustrates the dramatic increase in push off yield force (yield force positions lie on the curve shown in FIGURE 5) where the ratio of L/t 2 * . 4.
• FIGURE 6 shows a theoretical plot of variation of push-off yield force P with LQine A) in which the thickness of the fix basically as shown .
• FIGURES 1 to 3 has been kept constant at 0.9 mm with an interference fit of 0.38 mm on the shaft.
• FIGURE 6 shows a theoretical plot of variation of push-off yield force P with t(line B) in which the length L has been kept constant at 1.1 mm (minimum tooth length for conventional fix of any size) with an interference fit of 0.38 mm on the shaft.
• Range X represents the ideal range of push-on fixes; the fix behaves as a coned-washer spring and bending of the teeth is relatively small.
• Range Y represents the transition range where the teeth will take a set.
• Range Z is the range for conventional push on fixes where tooth bending accounts for most of the interference on the shaft.
• FIGURES 7 and 8 have been included to further illustrate the remarkable increase in yield force which can be obtained over the whole range of push-on fixes.
• FIGURE 7 once again shows variation in push-off force P plotted against material thickness t but this time over a range of thickness of 0.25mm to 1.0mm.
• line B' represents an extension of line B in FIGURE 6 over a range of thickness t not shown in FIGURE 6.
• the conventional thickness is about 0.38mm and therefore as predicted by line B' the yield force would only be about 0.75KN by reducing the tooth thickness to about 1/3 the conventional order of magnitude without altering the conventional thickness of the fix.
• FIGURE 8 shows once again variation in push off force P plotted against tooth length L.
• Line A' represents a portion of line A in FIGURE 6 drawn to different length scale for comparison with lines D and E.
• the shaded area D' E' represents the possible yield point values achievable with conventional fixes showing once again that the theoretical maximum value is still less than 3KN which is generally in line with empirical results.
• the retaining ring in accordance with the present invention has a much higher yield force and therefore can be used in many applications which have not hitherto been practical.
• One such application is in the field of adjustable pipe support arrangements and using a push-on fix retaining ring in an adjustable pipe support arrangement advantageously facilitates manufacture and may considerably cut down on costs of other designs of pipe support arrangement.
• This invention also relates in a second aspect to an adjustable pipe support arrangement used for supporting a pipe along its length and so that the pipe may, for example, be suspended at a fixed distance from an overhead girder.
• a previously proposed pipe support arrangement has a long rigid rod of about 40 cm in length.
• An inherently resilient spring clip or clamping bracket is provided at an upper end of the rod and a one piece pipe bracket is releasably retainable on the lower end of the rod by the use of a locking collar which is slid over free end projections of the bracket.
• the rod itself is provided with a screw- thread along its entire length and at its upper end is screw threadably engaged with the spring clip; at its lower end it is screw-threadably engaged with a specially shaped elongate nut co- operable with the projections on the pipe bracket so that the pipe bracket is retained to the rod by the locking collar being slid over the projections and nut thereby holding the projections in retaining engagement with the nut.
• the spring clip is adapted to fasten the pipe support arrangement to an overhead girder or roof section.
• the distance that the rod extends below the spring clip and therefore the height at which a pipe may be supported in the pipe bracket is variable by way of the screw thread engagement between the clip and rod and by rotating the rod relative to the clip.
• the spring clip is engaged with the rod by means of a screw-thread on the rod.
• the cost of providing a long rod with a screw-thread along its length is a considerable cost of the pipe support arrangement but is necessary to give a full range of adjustment of the height of the pipe (i.e. the distance between the girder and the pipe needs to be variable over the rod length).
• the screw-thread engagement between the spring clip and rod tends to be a disadvantage since the rod has to be rotated to move it up or down relative to the clip.
• the previously proposed pipe support arrangement is provided with a specially shaped nut.
• the nut is shaped so that its exterior will interlock with the bracket projections when the locking collar is in place to retain the pipe bracket to the rod.
• the provision of such a nut tends to be a disadvantage because it is so costly to manufacture.
• an adjustable pipe support arrangement comprising a rod provided at one end with clamping means to clamp onto a fixture, for example a girder, and provided at the other end with a pipe bracket through which the pipe is to extend in use, the pipe bracket being releasably lockable to said other rod end and the rod being longitudinally adjustable relative to the clamping means, said other end of the rod having a retaining ring formed individually from said rod and engaged with said other rod end by a force fit, said bracket having projections which in use embrace the retaining ring and a locking collar which in use surrounds the rod and holds said projections to the rod and retaining ring such that the engagement of the retaining ring on the rod retains the pipe bracket on the rod.
• the retaining ring may have any of the features as hereinbefore mentioned.
• the adjustable pipe support arrangement may have an advantageous adjustment and further according to the present invention there is provided an adjustable pipe support arrangement comprising a rod provided at one end with clamping means to clamp onto a fixture, for example a girder, and provided at the other end with a pipe bracket through which the pipe is to extend in use, the pipe bracket being releasably lockable to said other rod end and the rod being longitudinally adjustable relative to the clamping means by a movement of the rod in each of opposed longitudinal directions of the rod, the adjustable pipe support arrangement carrying releasable locking means in the form of a swivel plate which locks the rod relative to the clamping means against movement in one of said opposed longitudinal directions and the arrangement being such that on release of the releasable locking means the longitudinal position of the rod relative to the clamping means may be adjusted in each of said opposed longitudinal directions by a linear movement of the rod.
• an adjustable pipe support arrangement comprising a rod provided at one end with a clamping bracket to clamp onto a fixture, for example an overhead girder, and provided at the other end with a pipe bracket through which a pipe is to extend in use, the pipe bracket being releasably lockable to said other rod end and the rod being longitudinally adjustable relative to the clamping bracket by a movement of the rod in each of opposed longitudinal directions of the rod, said clamping bracket carrying releasable locking means in the form of a swivel plate which automatically locks the rod relative to the clamping bracket against movement in one of said opposed longitudinal directions but simultaneously allows longitudinal movement of the rod in the other of said opposed longitudinal directions.
• the pipe support arrangement as described in either of the two immediately preceding paragraphs may have a retaining ring formed individually from said rod and engaged with said other rod end by a force fit, said bracket having projections which, in use, embrace the retaining ring and a locking collar which in use surrounds the rod and holds said projections to the rod and retaining ring such that the engagement of the retaining ring on the rod retains the pipe bracket on the rod.
• FIGURE 9 shows a sectional view of a previously proposed pipe support arrangement
• FIGURE 10 shows a sectional view similar to that of FIGURE 9 but of the embodiment of the pipe support arrangement in accordance with the present invention.
• FIGURE 9 shows a previously proposed adjustable pipe support arrangement 1 having a long externally - threaded rod 2 of about 40 cm in length and of generally circular cross section.
• the upper end of the rod is screw threadably engaged with clamping means in the form of a spring clip or clamping bracket 3 having legs 3a which embrace a fixture such as an overhead girder.
• the legs 3a are urged apart as the bracket 3 is fitted onto the girder and teeth 3b 'bite' into the girder to secure the bracket 3 to the girder. In this way the pipe support arrangement may be suspended from the girder.
• specially shaped elongate nut 4 having a blind internal screw thread and of generally circular cross section is screw-threadably engaged on the lower end of the rod 2 and has a knurled surface 4a around the upper peripheral portion thereof.
• the knurled surface 4a is to aid in assembling and dis-assembling the nut 4 from the rod 2.
• the nut 4 is shaped to co-operate with free end projections 5a of a one-piece pipe bracket 5.
• the lower end of the nut 4 has a portion of diminished diameter and may generally be described as diablo shaped although portion 5b is part spherical.
• the pipe is introduced into the pipe bracket 5 and a cylindrical locking collar 6 is introduced axially upwardly onto the rod 2 over and beyond the specially shaped nut.
• the pipe bracket projections 5a are urged more closely together by hand while being arranged to engage and straddle the lower end of the nut 4 and the collar 6 is then moved axially downwardly over the nut 4 and projections 5a so that the projections 5a are held in retaining engagement with the nut 4 by the collar 6.
• the pipe bracket 5 can be released from the rod 2 simply by moving the locking collar 6 axially upwardly beyond the projections 5a which then spring out of engagement with the nut 4.
• the projections 5a need to be disengaged from the nut 4 so that access may be gained to the nut 4.
• the nut 4 may be gripped by the knurled surface 4a to rotate the rod 2 clockwise or anticlockwise to adjust the amount by which the rod extends below the clamping bracket 3 by way of the screw thread engagement between the rod 2 and bracket 3.
• the projections 5a can be re-engaged with the nut 4 in the manner as aforedescribed and the locking collar 6 moved downwardly to retain the pipe bracket 5 to the rod 2 once again.
• Such pipe support arrangements would be arranged along a length of pipe and spaced apart from one another by more than a metre. Therefore, in order to adjust the height of the length of pipe each pipe support rod needs to be individually adjusted.
• the pipes which are supported by such arrangements may be, for example, water pipes or gas pipes and such arrangements are particularly applicable in industrial environments where the pipes which are supported are not necessarily going to be a permanent fixture. In such circumstances the height or incline, for example, of pipes may be important as well as the adjustment height facility.
• FIGURE 10 shows a view similar to FIGURE 9 of an embodiment of an adjustable pipe support arrangement 7 in accordance with the present invention.
• the pipe support arrangement 7 has a generally cylindrical iron rod 8 which has no external screw thread.
• the upper portion of clamping bracket 9 is similar to that of clamping bracket 3 in FIGURE 9 and, therefore, will not be further described.
• the engagement between the rod 8 and bracket 9 is very different to the screw thread engagement described in relation to FIGURE 9:
• a hardened swivel plate 10 has a projection 10a mounted in a slot 11 in one side of the clamping bracket 9.
• the plate 10 can pivot or swivel about the slot 11 from the position shown as position 'A' in FIGURE 9 (which is the rod locking position) to the position shown as 'B * in which the plate 10 is shown in chain-dotted lines (position 'B' is the unlocked position).
• Plate 10 is generally rectangular with a generally central hole 12 passing through the plate 10. Hole 12 is of slightly larger diameter than the rod 8 but when in position 'A' edges 13 and 14 bite into rod 8 as a downward force is applied to rod 8.
• the swivel plate 10 constitutes releasable locking means since the 'released' position corresponds to position B and the plate may be urged to, and held, in this position by a finger or thumb pushing upwardly on the left-hand end of plate 10, which end comprises a finger grip portion extending from the generally rectangular form of the plate 10 and, as viewed in FIGURE 10, in front of the clamping bracket 9.
• a retaining ring R generally of the form shown in FIGURES 1 to 3 is applied onto the lower end of the rod 8.
• the pipe bracket 5' has free end projections 5a' which are shaped to co-operate with the ring R and a locking collar 6' is provided to lock the end projections 5a' to the ring R and to the rod in a similar manner as described in relation to FIGURE 9.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Clamps And Clips (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10559958

Family Applications (1)

Country Status (4)

Families Citing this family (17)

Family Cites Families (13)

• 1984
  • 1984-04-24 GB GB08410385A patent/GB2157786B/en not_active Expired
• 1985
  • 1985-04-23 EP EP19850902076 patent/EP0177598A1/de not_active Withdrawn
  • 1985-04-23 AU AU42198/85A patent/AU4219885A/en not_active Abandoned
  • 1985-04-23 WO PCT/GB1985/000174 patent/WO1985004934A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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