GB2383390A

GB2383390A - Fastener

Info

Publication number: GB2383390A
Application number: GB0130345A
Authority: GB
Inventors: Ronald Dennis Carpenter
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-19
Filing date: 2001-12-19
Publication date: 2003-06-25
Anticipated expiration: 2021-12-19
Also published as: GB2383390B; GB0130345D0

Abstract

A fastener (A) for joining parts has a tubular body (3) is located in a blind hole (2) in one of the parts. The fastener (A) is driven into the hole (2), reducing the length of the body (3) by contact of the fastener (A) with an end of the hole (2). The body (3) deforms at a weakened section (8 - see figure 2) causing segments (5) to move outwardly of the body (3) and grip the hole (2). When the fastener (A) is installed in the hole a solid section (14) of the body (3) is an interference fit with an inside surface of the segments(5).

Description

FASTENER This invention provides a method of joining parts together by using a fastener that deforms in sequential stages under an applied load, which causes the fastener to expand and become attached to a hole in one part and then clamp against other parts to create an assembly.

Joining parts together using conventional threaded bolts, wood type screws or'pop'rivets are common practices, but tapping holes for bolts or providing plugs (e. g. for screws in concrete) can be time consuming and expensive when the application may not require the full load and holding potential that a thread provides.

Other background considerations :-Machining bolts made from hexagon bar wastes material and time to produce.

Bolts and screws can be readily removed after fitting which may not be desirable if tamper resistance is a requirement.

Alternatively, using a'pop'type rivet when joining parts together often demands the use of proprietary equipment for assembly and is wasteful as a second part, (the stem, mandrel or pin), is not needed and discarded after the riveting operation has been completed.

An object of this invention is to provide a fastener to replace threaded bolts, wood type screws or'pop'rivets when joining parts together in suitable applications. The fastener requires only a drilled or formed hole to attach to and the parts are joined together by a single hammer blow to the head of the fastener, thus reducing the time taken and the need for specialist equipment when replacing bolting, screwing or riveting operations.

Other advantages, when compared with bolts, screws or'pop'rivets, are that the fasteners proposed would be manufactured from less material, are lighter in weight and cannot be readily removed if tamper resistance or security is a requirement.

Excessive drilling of the hole depth in'blind hole'applications is avoided, as a controlled hole depth is necessary for the fastener to function.

Accordingly this invention provides a method of joining parts together with a fastener which is located in a hole in one part and seated on a solid surface, the fastener has a tubular body portion containing a number of segments, which are integrated with the body at its lower end and are not attached to the body for the rest of the segment, so that when a load is applied to the upper end of the fastener the tubular body is deformed and the segments are made to lift outwards and into contact with the hole, simultaneously the load has reduced the length of the body and a solid section of the upper part of the body has travelled under the lifted segments and continues moving into an interference fit with the internal surface of the lifted segments which subsequently forces an increased area of contact of the external surface of the segments against the wall of the hole with a sustained pressure that attaches the fastener to the hole.

The segments could be produced by cutting a number of'V'shaped slots through the wall of the tubular body. The inner profiles of the'V'slots create the segments. The'V'slots are deliberately positioned to create a weakened section to ensure where the tubular body will deform and swell outwards when a load is applied. The segments are integrated with the body on one side of swelling so that the segments will lift at their unrestrained ends in line with the swelling. The outer profile of the'V'slot creates the solid section of the upper part of the body that travels under the lifted segments and into the interference contact that forces the attachment of the fastener to the hole.

A basic fastener is completed by having a flanged head added to the upper end of the tubular body, above the parts being joined together, for the purpose of,-1) providing a surface to take the'applied load'that deforms the tubular body,-2) establishing a'known gap'dimension, located between the underside of the flanged head and the upper surface of the parts, which controls the reduction in the body length that in turn determines the initial segment lift and then the distance travelled under the lifted segments by the solid section of the tubular body, and finally,-3) the clamping the parts together by the underside of the flanged head to create an assembly when the'known gap'is finally closed.

The'applied load'can be provided with a single hammer blow.

For joining parts together in applications where a'thro. hole'is provided in one of the parts, the fastener is located in the'thro. hole' and is seated on a solid load reaction surface provided by the introduction of a tool or by utilising a second part of the assembly.

For joining parts together in drilled'blind hole'applications, the fastener has a conical foot added at the lower end of the tubular body, that sits snugly into the drill point to give a good reaction surface against an applied load. The hole must have a controlled depth for the fastener to function, but this avoids un-necessary, excessive drilling.

The flanged head could be of an angular form that leaves a compressed residual angle, after the blow has been struck and the'known gap'closed, that exerts a sufficient load to clamp the second part and can also accommodate small variations in height created by the dimensional tolerances that will exist in the manufacture of the fastener and the parts.

The diameter of an angular flanged head will increase dimensionally as the head is compressed to its clamping position and this could be utilised to grip inside the internal diameter of another part to create a further assembly opportunity.

A minimum of two segments is necessary in a fastener to enable parts to be joined together.

However the number of segments can be increased to suit the size and type of the fastener.

The segments can be positioned in either direction on the body and can be positioned in alternating directions on the body, if required to suit different materials or applications.

The segments can be produced in multi-level rows on the body to improve the attachment capability when a deeper hole is provided in a solid part (e. g. masonry or concrete).

Two, or more, tubular body stages containing their own rows of segments can be produced to accommodate particular applications The body stages would increase in stepped diameter sizes to enable tool access.

The segments may be other than'V'shapes to suit different materials or applications.

The segments could be truncated, parallel or a shaped to provide a wider contact face than the apex of a'V'gives and could have teeth or other pre-forms added at the free ends to increase the attachment capability of the segment to the wall of the hole.

Serrations could be added locally to the outside of the segments to improve grip in the hole.

Forming the serrations on the segments would'work harden'the surface and would aid penetration into the surface of malleable or plastic materials.

Alternating direction segments can be produced by incorporating holes, slots or other devices positioned to weaken the body at the mid-point on the segments length.

This enables the body length to be kept to a minimum when alternating direction segments are required.

The segments could be partially lifted during manufacture. This would reduce the load required to deform the body and the solid section of the body could be much closer to the lifted segments from the outset, which would make the fastener and parts assembly process more efficient.

Other aids to assist the initial segment lift could be the addition of a chamfer or a formed, truncated foot at the lower end of the tubular body where it sits on the reaction surface, to provide an inward pivot point of contact that would bias the deformation of the body and segment lift in the required outwards direction.

The fastener is preferably produced on an industrial press and made in stages, starting from a flat strip of a malleable material that can be readily formed, such as steel or aluminium.

Several'V'slots are cut into the strip at the flat blanking stage at pre-determined positions that relate to the design of the eventual fastener being produced. The fastener is then formed on the press with suitable punches and dies to produce a deep drawn tubular body with a flanged head at the upper end and an open ended or a conical foot at the lower end.

The deep drawing operation also transfers the'V'slots to their final location near to the lower end of the tubular body.

Shapes other than'V'slots could be added in the same manner.

The'V'slots could be produced as'V'slits that elongate into slots during the deep drawing operation.

Through holes could be added at the open end of the'V'slits to avoid splitting the material during manufacture and to create the required weakened section of the body.

Alternatively the'V'slots could be added by side piercing after the fastener has been formed.

The fastener could alternatively be made by extrusion from a metal blank with the slots side pierced, or rolled from a strip of metal which has slots included or machined from solid.

The fastener requires a suitable hole to be provided in one of the parts of the assembly. The dimensions of the hole diameter are pre-determined, by a calculation using the tubular body diameter and the material thickness of the fastener, to give an interference fit in the hole or to penetrate the surface of lower density materials. The depth of the hole is predetermined, by a calculation using the fasteners tubular body length and the thickness of the parts involved in the assembly, to give the required gap above the parts for assembly.

The hole would be produced by normal engineering methods and to drilling tolerances, but would preferably have a course finish when drilled, or could have longitudinal serrations in the bore when moulded in a plastic material that would provide a suitable surface for the fastener segments to attach to when an application requires a stronger joint.

The fastener is intended for use in applications or products manufactured in metal, masonry,

brick, concrete, wood or plastic materials where a suitable'thro. hole' or'blind hole'and load reaction surface can be provided.

A preferred embodiment of the invention will now be described with reference to the following drawings in which: FIGURE 1 to 4 shows the basis of the invention in sequential steps.

FIGURE 1 shows a basic fastener'A'located in parts prior to assembly.

FIGURE 2 shows the interim stage where the segments have lifted at their unrestrained ends.

FIGURE 3 shows the final assembled position of fastener'A'joining parts together.

FIGURE 4 shows the weak section created by the positioning of the'V'slots FIGURE 5 shows a fastener'A'for use in a'thro. hole'.

FIGURE 6 shows fastener'A'in a'thro. hole' using another part as a reaction surface.

FIGURE 7 shows a basic fastener'F'for use in a drilled'blind hole'.

FIGURE 8 shows a fastener'H', with an angular head, prior to assembly.

FIGURE 9 shows fastener'H'in its final clamping position.

FIGURE 10 shows the angular head of fastener'H'becoming attached to another part.

FIGURE 11 shows fastener'L'with segments in alternating directions.

FIGURE 12 shows fastener'M'with multi-level segments for deep holes.

FIGURE 13 shows fastener'N', a two-stage body application.

FIGURES 14A to 14F show alternative shapes of segments, end forms and serrations.

FIGURES 15A to 15D shows alternating direction segments weakened at mid-length.

FIGURE 16 shows a fastener'P', with a pre-lifted segment, prior to assembly.

FIGURE 17 shows fastener'P'after assembly.

FIGURE 18 shows a fastener'R'with a chamfer added to aid segment lift.

FIGURE 19 shows fastener'R'after assembly.

FIGURE 20 shows a fastener'S'with a formed, truncated foot added to aid segment lift.

FIGURE 21 shows fastener'S'after assembly.

The basis of the invention is illustrated in the sequential steps shown in Figs. 1 to 3 Fig. 1 shows a basic fastener'A'prior to assembly, that has been inserted through a hole 1 in part'B'and then located and seated in a hole 2 of a pre-determined diameter that relates to the fastener diameter and material thickness. The fastener'A'has a tubular body 3 which has several inverted'V'shaped slots 4 cut through the body 3 wall to create segments 5 that are integrated with the body 3 at 6 and are free of the body 3 for the remainder of the inner profile of the'V'shaped slot that includes the apex 7 of the'V'.

The'V'slots are deliberately positioned to create a weakened section 8 on the body 3.

The fastener'A'is seated on a solid reaction surface 9 and has a flanged head 10 positioned above part'B'by a'known gap'11, which controls the assembly process.

The fastener'A'is struck on the flanged head 10 with a hammer blow 12 of sufficient force to deform the body 3 and completely close the gap 11, but at a mid-process stage (see Fig. 2) a partially deformation at the weakened section 8 has caused the body to swell out 13 and the segments 5 are lifted at their unrestrained ends in line with the swelling until the apex 7 of the'V'touches the wall of hole 2 while simultaneously a solid section of the body 14, provided by the outer profile of the'V'slot, has moved by the distance 15 so that the inner and outer profiles of the'V'slot are now close to each other.

Fig. 3 shows the fastener'A'in its final assembled position. The hammer blow 12 has fully closed the gap 11, the segments have been restricted from lifting further by the hole 2 and the solid section of the body 14 has travelled under 17 the lifted segments and moved into an interference fit with the internal surface 16 which subsequently forces an increased area of contact of the external surface 18 of the segments against the wall of the hole with a sustained pressure that attaches the fastener to the hole 2 and the flanged head 10 is firmly clamped against part'B'thus joining all the parts together.

Fig. 4 is a section'XX'through the tubular body 3 at the weakened section 8.

Fig. 5 shows an example of a'thro. hole' application. The fastener'A'is inserted through a hole 1 in a part'B'and located in a'thro. hole' 20 provided in a part'C'. A rigid tool 21, or other solid surface, provides the reaction surface 9. A hammer blow 12 is applied to the flanged head 10 and the fastener'A'subsequently joins part'B'and part'C'together in the same sequential process as described in Figs. 1 to 3.

Fig. 6 shows another'thro. hole' example where a part'D'of an assembly provides the reaction surface 9 when being joined by fastener'A'to a part'E'.

Fig. 7 shows an example of a drilled'blind hole'application. The fastener'F'is inserted through a hole 1 in a part'B'and located in a'blind hole'22, of controlled size and depth, provided in a part'G'. The fastener'F'has a conical foot 23 added to the lower end of the tubular body 3 that fits snugly into the drill point 24 of hole 22 to give a solid reaction surface. All other features of fastener'F'are as the basic fastener'A'described in Fig. 1.

A hammer blow 12 is applied to the flanged head 10 and the fastener'F'subsequently joins parts'B'and'G'together by the same sequential process as described in Figs. 1 to 3.

Fig. 8 is a part view of a fastener'H', prior to assembly, with a formed angular head 25, which has an included height 26 above the known, gap 11, all other features are as basic fastener'A'or for'blind hole'applications as fastener'F'.

Fastener'H'attaches to the hole in part'J'as described previously and clamps part'B'as shown in Fig. 9 where the hammer blow 12 has caused the angular head 25 to be compress the height 26 to a lower height 27 as it comes into contact with part'B'. The remaining residual angle 28 in the formed head 25 ensures a constant clamping load for holding part 'B'to'J'and also accommodates variations in the height of the known gap 11 that may have been created by manufacturing tolerances in fastener'H', parts'B'and'J'.

Fig. 10 shows fastener'H'where the increase in diameter of the compressed angular head 25, following the hammer blow 12, has been utilised to grip inside the internal diameter 29 of a part'K'to create another assembly opportunity.

Segments can be located in various positions or arrangements on the tubular body of a fastener and will respond to an applied load in the same manner as described in Figs. I to 3.

Figs. 11, 12 and 13 show examples of segment configurations Fig. l1 shows fastener'L', prior to assembly, with alternating direction segments 30 and 31 that overlap to create the weakened section 32.

Fig. 12 shows fastener'M', prior to assembly, with two rows of segments 33 and 34 for use in deeper holes. More rows of segments could be introduced to suit the application.

Segment rows would operate independently of each other.

Fig. 13 shows fastener'N'with multi-level body stages containing their own segments. The

first stage 35 is assembled using tool 36 and the second stage 37 follows using tool 38.

Figs. 14A to 14F show segment forms that differ from the'V'shape described thus far, which would function in the same way and could improve the fasteners attachment capability.

Figs. 14A to 14C have a wider attachment face 39 when compared with the apex of the'V.

Fig. 14D has teeth 40 added, Fig. 14E has a preformed end 41 and Fig. 14F has serrations 42 added to the outside of the segment to penetrate into the wall of the attachment hole.

Figs. 15A to Figs. 15D illustrates methods of providing a mid-segment weakened section that will cause the segments to lift in alternating directions and become attached to the hole in the same manner as described in Figs. I to 3 but in alternate opposing directions.

Fig. 15A shows an opened out view of a body 43 containing two segments 44 with a hole 45 added between the segments to create a weakened section 46. When a load is applied to the fastener, as described previously, the body swells outwards at the weakened section 46 and both segments lift and become wedged as shown in sections'XX'and'YY'. Fig. 15B shows a slot 47, instead of a round hole, to facilitate initial segment lift Fig. 15C shows segments with an increased width 48 that weakens the section at 49. Fig. 15D shows an indent 50 into the material that weakens the section between the segments

Figs. 16 shows a fastener'P', prior to assembly, where the segments 51 have been pre-lifted during the manufacturing stage. This enables the leading face 52 of the solid section of the tubular body 3 to be located adjacent to the apex 53 of the lifted segment 51 from the outset of the assembly process. This feature provides an efficient design as the distance travelled by the leading face 52 when attaching the fastener'P'to the hole 2 and the load required for the assembly are both reduced.

Fig. 17 is a part view of the final assembly of fastener'P'.

Fig. 18 shows a fastener'R', prior to assembly, where a chamfer 54 has been added to the lower end of the tubular body 3. The position of the chamfers contact 55 with the reaction surface 9 provides an inward pivot point of contact that aids and ensures the outward direction of the segments 5 when the load 12 is applied.

Fig. 19 shows the final assembly of fastener'R'.

Fig. 20 shows a fastener'S', prior to assembly, that has a formed, truncated foot 56 added to the lower end of the tubular body 3 at the manufacturing stage. The position 57 of the formed foot 56 on the reaction surface 9 provides an inward pivot point of contact that aids and ensures the outward direction of the segments 5 when the load 12 is applied.

Fig. 2 1 shows the final assembly fastener'S')

Claims

1. A method of joining parts together with a fastener which is located in a hole in one part and seated on a solid surface, the fastener has a tubular body portion containing a number of segments, which are integrated with the body at its lower end and are not attached to the body for the rest of the segment, so that when a load is applied to the upper end of the fastener the tubular body is deformed and the segments are made to lift outwards and into contact with the hole, simultaneously the load has reduced the length of the body and a solid section of the upper part of the body has travelled under the lifted segment and continues moving into an interference fit with the internal surface of the lifted segments that subsequently forces an increased area of contact of the external surface of the segments against the wall of the hole with a sustained pressure that attaches the fastener to the hole.

2. A fastener as claimed in Claim I where the segments are created by cutting a number of'V'shaped slots through the wall of the tubular body that are positioned to give a weakened section that will determine where the tubular body deforms and swells outwards following a blow to the fastener.

3. A fastener as claimed in Claim I and Claim 2, where the segments are integrated with the tubular body on one side of the weakened section so that the remaining unrestrained portion of the segments will lift outwards in line with the swelling that occurs when the tubular body deforms following a blow to the fastener.

4. A fastener as claimed in Claims I to 3, where the outer profile of the'V'slot creates the solid section of the upper part of the body that travels under the lifted segments and continues into an interference contact with the internal surface of the segment.

5. A fastener as claimed in Claim 1, where the lower end of the tubular fastener is seated on a surface capable of providing to a positive reaction against an applied load to the upper end of the fastener to ensure the deformation of the fastener.

6. A fastener as claimed in Claim 1, where a flanged head is added to the upper end of the tubular body.

7. A flanged head added to the fastener as claimed in Claim 6, which is capable of taking the'applied load'from a hammer blow or from some other suitable method.

8. A flanged head added to the fastener as claimed in Claim 6, which establishes a 'known gap'dimension, between the under-side of the flanged head and the upper surface of the assembled parts, that controls the reduction in the body length which in turn determines the initial segment lift and then the distance travelled under the lifted segments by the solid section of the tubular body.

9. A flanged head added to the fastener as claimed in Claim 6, which clamps other parts by the under-side of the flanged head to the first part, with the hole, to create an assembly when the'known gap'is finally closed.

10. A fastener as claimed in any preceding claim, where a fastener is to be used in a 'thro. hole' application, the fastener is seated on a load reaction surface provided by the introduction of a separate tool or on a solid surface or by another component part of an assembly.

11. A fastener as claimed in Claims 1 to 9, where the a fastener is to be used in a drilled'blind hole'application, a conical foot is added to the lower end of the tubular body which sits snugly into the drill point to give a good reaction surface against the applied load.

12. A'blind hole'as claimed in Claim 11, where the drill depth is controlled to enable the fastener to function, avoids the wasteful practice of excessive drilling

13. A fastener as claimed in any previous claim where a flanged head with an angular form is added to the upper end of the tubular body that leaves a small compressed residual angle, following the applied load that closes the'known gap', which exerts a sufficient clamping load to hold an assembly together and can also accommodate small variations in height created by the dimensional tolerances that will exist in the manufacture of a fastener and the component parts of an assembly.

14. An angular form flanged head as claimed in Claim 13, where the compressed head will increase dimensionally in diameter and this can be used to grip inside the internal diameter of another part to create a further assembly opportunity.

15. A fastener as claimed in any preceding claim, where a minimum of two segments is necessary for the fastener to function.

16. A fastener as claimed in Claim 15 where any number of segments can be introduced to suit the size and type of fastener.

17. A fastener as claimed in any preceding claim, where segments can be positioned in either direction on the tubular body portion of the fastener.

18. A fastener as claimed in any preceding claim, where segments can be positioned in alternating directions on the tubular body portion of the fastener.

19. A fastener as claimed in any preceding claim, where segments are provided in two or more rows on the tubular body portion of the fastener.

20. A fastener as claimed in any preceding claim, where two or more tubular body portions are added, arranged in stages of increasing diameters to enable tooling access and containing their own rows of segments in each stage, can be produced to accommodate particular applications.

21. A fastener as claimed in Claim I and Claims 5 to 20, where other segment forms are proposed that would provide an improved attachment capability between the fastener and the hole than is achieved by the'V'segment.

22. A fastener as claimed in Claim 21, where the segment has a truncated form to present a wider contact face than the apex of a'V'segment.

23. A fastener as claimed in Claim 21, where the segment is of a parallel form to present a wider contact face than the apex of a'V'segment and the slot has been extended at the integrated end of the segment to create the weakening section in the tubular body.

24. A fastener as claimed in Claim 21, where the segment is of a'necked'form that provides the weakened section in the normal manner, but presents a wider contact face than the apex of a'V'segment.

25. A fastener as claimed in Claims 21 to 24, where several pointed teeth have been added at the segments wider contact face, which will increase the attachment capability of the fastener by having more points of contact with the hole.

26. A fastener as claimed in Claims 21 to 24, where the end of the segments wider contact face has been pre-formed outwards and would thus contact the wall of hole with a positive edge that increases the attachment capability of the fastener.

27. A fastener as claimed in Claims 21 to 24, where serrations have been added to the outside of the segments to improve the grip in the hole. Forming the serrations would'work harden'the contact surface of the segments and aid penetration into the walls of holes provided in parts made from malleable or plastic materials, thus improving the fasteners attachment capability.

28. A fastener as claimed in Claim 1, Claims 5 to 21 and Claims 25 to 27, where alternating direction segments are introduced that have the weakened section positioned between and at the mid-length of the segments to provide a two way lifting action etc. for the segments. This enables the body length to be kept to a minimum when alternating direction segments are required.

29. A fastener as claimed in Claim 28, where the weakened section is created by the introduction of holes between the segments.

30. A fastener as claimed in Claim 28, where the weakened section is created by the introduction of slots between the segments, which improves segment lift.

31. A fastener as claimed in Claim 28, where expanding the segment shape and slot at the mid-length of the segments creates the weakened section.

32. A fastener as claimed in Claim 28, where the weakened section is created by introducing an indent into the material of the tubular body at the mid-length of the segments.

33. A fastener as claimed in any preceding claim, where the segment is partially lifted during the manufacture of the fastener, which would reduce the load required to deform the body, and the solid section of the body could be much closer to the lifted segments from the outset, which would make the fastener and parts assembly process more efficient.

34. A fastener as claimed in Claims 1 to 10, Claims 13 to 27 and Claim 33, where a chamfer is added to the lower end of the tubular body of the fastener that is seated on the reaction surface, which will provide an inward pivot point of contact that would bias the deformation of the body and segment lift in the required outwards direction when a load is applied.

35. A fastener as claimed in Claims 1 to 27 and Claim 33, where a formed, truncated foot is added to the lower end of the tubular body of the fastener that is seated on the reaction surface, which would provide an inward pivot point of contact that would bias the deformation of the body and segment lift in the required outwards direction when a load is applied.

36. A fastener as claimed in Claims 1 to 4, Claims 10 and 11 and Claims 15 to 35, where the slots which define the segments, could be replaced by'slits'cut through the tubular body.

37. A fastener as claimed in any preceding claim, which is manufactured from a malleable material that is readily formed, such as steel or aluminium.

38. A fastener as claimed in any preceding claim, which requires a suitable hole to be provided in one of the parts of an assembly The diameter and depth dimensions of the hole are pre-determined to give the fastener an interference fit in the hole or to penetrate the surface of lower density materials and to clamp against other parts to create an assembly.

39. A suitable hole for the fastener as claimed in Claim 38 would be produced by normal engineering methods and to drilling tolerances but could have a could have a course finish when drilled, or could have longitudinal serrations added to the bore when moulded in a plastic material, that would improve the attaching surface when a stronger joint is required.

40. A fastener as claimed in any preceding claim is intended for use in applications or products manufactured in metal, masonry, brick, concrete, wood or plastic materials where a suitable'thro. hole or'blind hole'and a load reaction surface can be provided.

41. A fastener substantially as described herein with reference to Figures 1-21 of the accompanying drawings.