GB2481011A - Fastening System - Google Patents

Abstract

A fastening system comprises a first component 1 and a second component 8. The first component 1 is located in a blind hole B and has a tubular body that has been castellated at one end to provide a number of expanding cantilevers 4 and a number of latching cantilevers 5. The second component 8 has a truncated conical form 12 which contain latching recesses 9. A load E is applied to the conical component 8 that causes the conical form 12 to travel the distance G inside the castellated component 1, forcing the expanding cantilevers 4 to lift outwards to produce a positive holding contact 13 with the cylindrical surface of blind hole B. On completion of travel G, latching hooks 6 on the first component 1 enter the latching recesses 9 to ensure that the holding contact 13 is maintained as the conical component 8, that caused the expansion, cannot now become disengaged.

Description

I

Dual Fastening System This invention relates to the interaction between the two component parts of a fastening system, that under a load combine to expand diametrically into a holding contact within a hole and finally become locked together to maintain their assembled position.

Minimum preparation is required as the fastening system can function in a coarse drilled or formed hole and is activated by a simple hammer blow. It is intended for lightweight applications in Industrial Assembly, Furniture Manufacture and Building Construction.

The first component has a basically tubular body castellated by slots cut along part of its length to create a number of narrow, flexible cantilever shaped elements. Some of the cantilevers are devised to expand the external diameter of the castellated component, the remaining cantilevers have internal attaching elements added at their free to lift end.

The second component has a truncated conical form whose lead diameter coincides with the internal diameter of the cantilevers. Attaching recesses are provided in the conical form at a set distance from the front face of the lead diameter.

An example of an application (a headed fastener) using the system is described below.

The castellated component is seated in a blind hole provided in one part of an assembly.

The conical component extends from the head of the fastener and is passed through a hole in the second part of the assembly until its lead diameter is adjacent to free to lift end of the cantilevers. A load is applied to the fastener head that forces the conical form to enter the castellated component causing the free end of the expanding cantilevers to lift outwards, thus increasing the effective outside diameter of the castellated component and forcing a holding contact to be made with the cylindrical surface of the blind hole.

The two components complete their movement when hooks provided at the free end of the attaching cantilevers finally reach and, due to the residual load created in the lifted cantilever, enter and latch into recesses in the conical form thus locking the components together to maintain the contact within the blind hole as the conical component that caused the expansion of the castellated component cannot now become disengaged.

In this application, a pre-determined gap between the fastener head and the second part controls the process and the parts are clamped together when the gap is finally closed.

According to the present invention there is provided a dual fastening system derived from the interaction between two component parts, where one component is basically a tube, seated in a blind hole, that has been cut along part of its length to create a number of free to lift expanding and attaching elements and a truncated conical component with a leading diameter that coincides with the internal diameter of the tubular component; the system is activated when a load is applied to the conical component that causes its leading diameter to enter and travel inside the cut end of the tubular component, the conical form forces the expanding elements to lift into a holding contact in the blind hole and on completion of the movement the attaching elements become fastened into recesses provided in the conical form thus maintaining the holding contact as the conical component causing the expansion of the tubular component cannot now be disengaged.

A dual fastening system as described would either create a tight fit in a hole provided in a hard material or a penetrating hold in a compressible material. It requires a blind hole to provide a reaction surface to enable the device to function when the load is applied.

Through holes would require an anvil or a solid table to provide the reaction surface.

The castellated component relies on being produced in a material capable of bending without fracture and returning to its original position when the lifting engagement on the conical slope is completed, thus allowing the latching hooks to become engaged in the latching recesses as required.

The castellated component can be produced in a suitable injection moulded plastic material and the diagrammatic drawings below are based that method of manufacture.

Alternatively a castellated component could be produced from steel or aluminium strip that is blanked, pressed and formed into a tubular shape. This method enables the slots to be replaced by slits to give a greater area of contact.

The conical component can be made from a wide range of plastic, aluminium or steel materials using well known manufacturing methods such as injection moulding, die-casting and turning. The conical component has two functions; the activating part of a duel fastening system and as an integral part of a variety of industrial applications.

The two components can be made of different materials to improve the holding capacity within a hole or to suit a particular application or for decorative appearance.

The basic dual fastening system is described in detail below and shown in diagrammatic form on drawing Sheet 1/5.

Design variations to the basic system that will improve holding capacity within a hole, show alternative latching methods and provide for other than flat bottomed blind holes are described below with reference to drawings shown on Sheets 2/5 and 3/5.

The design variations featured on these drawings can be fully or partially interchanged and used as required to suit the various materials and applications encountered.

Typical applications for a dual fastening system are described below with reference to drawings shown on Sheets 4/5 and 5/5.

For clarity all drawings are produced using the same scale. The conical engaging angles are shown as the same, but angles and engaging lengths can vary to suit applications.

Numbers are used to identify the various dual fastening system elements and capital letters identify peripheral parts, actions and sections.

It is intended that for generally industrial use a much smaller scale for the components would be introduced and the engaging angles and lengths would be customised to suit the different applications and the materials used. Although, there is no restriction on larger diametrical and longitudinal sizes if appropriate component materials are utilised.

V

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:-Figure 1 shows basic features and initial location of a dual fastening system.

Figure 2 shows a Section XX through the castellated component.

Figure 3 shows the two types of cantilever partially lifted by the conical component.

Figure 4 shows the two dependent fastening locations after the activation of the system.

Figure 5 shows alternative cantilevers and other design features, prior to activation.

Figure 6 shows Section YY through the cantilevers to illustrate different combinations.

Figure 7shows Section ZZ through a guide channel.

Figure 8 shows Fig.5 design features after activation.

Figure 9 shows table or anvil required for through hole applications.

Figure 10 shows drilled hole location.

Figure 11 shows angled slots to improve contact.

Figure 12 shows outer and inner angles added to cantilevers, prior to activation.

Figure 13 shows the improved location of Fig.12 achieved after activation.

Figure 14 shows short lift, parallel length and alternative latch device prior to activation.

Figure 15 shows the location and latching of Fig.14 after activation.

Figure 16 shows inner and outer serrations as an alternative design, prior to activation.

Figure 17 shows how variable engagement can be achieved after activation of Fig.16.

Figure 18 shows a headed fastener application, prior to activation.

Figure 19 shows the headed fastener after activation.

Figure 20 shows internal thread insert.

Figure 21 shows extending thread application.

Figure 22 shows a double-ended application, prior to activation.

Figure 23 shows the double-ended application after activation.

Figure 24 shows a flush fitting collar with a hook as a typical external application.

Figure 25 shows a cable or rod end anchor.

Figure 1 shows the principle features and initial positioning of a dual fastening system, which comprises of a tubular castellated component I with slots 2 cut along part of its length 3 to create expanding cantilevers 4 and latching cantilevers 5 with a hooks 6 and whose outside form 7 is reduced and chamfered to avoid fouling hole B when activated; and a second, truncated conical, component 8, with latching recesses 9, whose leading diameter 10 coincides with and is positioned adjacent to the internal diameter 11 of the castellated component 1. Prior to activation the castellated component I is seated at A in a blind hole B provided in an assembly part C. Datum line D is a given starting point for the conical component prior to activation. Section XX is featured in Fig. 2.

Figure 2 is the Section XX which shows the six slots 2 that produce three expanding cantilevers 4 and three latching cantilevers 5.

Figure 3 shows a partially activated dual fastening system where an applied load E has moved the conical component 8 a distance F and entered the castellated component 1.

The conical form 12 has started to lift the expanding cantilever 4 into contact with the blind hole B and is also partially lifting the latching cantilever 5.

Figure 4 shows the fully activated dual fastening system where the applied load E has forced the truncated conical component 8 to travel the distance G inside the castellated component I and the expanding cantilevers 4 have been lifted by the conical form 12 to penetrated 13 the assembly part C to create a holding contact firmly within blind hole B. On completing of the engagement the hooks 6 automatically latch into the recesses 9, due to the residual load gained in the latching cantilevers 5 as the hooks 6 are lifted by the conical form 12, thus locking the castellated component I and the truncated conical component 8 together to maintain the assembled position in blind hole B. Figure 5 shows a design variation where the expanding cantilever 4 has serrations 15 added to the external form and is weakened 16 near the end of slots 2 to assist bending.

The hooks 6 are located in a guide channel 17 that directs the latching cantilever 5 to the latching recesses 9 in the truncated conical component 8.

As shown, the castellated tubular component I and the truncated conical component 8 are positioned in the blind hole B prior to activation.

Both cantilevers are lightly in contact with the conical form 12 as a pre-assembly aid.

Section VY is featured in Fig.6 and Section ZZ is featured in Fig.7.

Figure 6 is the Section YY which shows twelve slots 2 that produce nine expanding cantilevers 4 and three latching levers 5.

Any number or combination of the two types of cantilever can be used to suit different materials and applications. Increasing the number of slots produces narrow cantilevers.

In some application the slots can be replaced by slits to increase the cantilever width.

Figure 7 is the Section ZZ which shows the guide channel 17 whose introduction also restricts rotation of the truncated conical component 8 after assembly.

Figure 8 shows the applied load E has activated the components as shown in Fig.5 and the serrations 15 have penetrated 13 into the surface of blind hole B. Figure 9 shows a part H with a through hole J which is positioned on a solid table K to provide a reaction surface L to enable the dual fastening system to function in this type of assembly. The drawing shows the components position after activation.

Figure 10 shows a castellated component I with a chamfer 18 added to seat in a typical drilled hole M in assembly part C. Figure 11 shows angled slots 19 that increase the circumferential holding contact.

Figure 12 shows an outer angular surface 20 and an inner angular surface 21 added to the expanding cantilever 4 to improve the eventual contact.

In addition Figurel 2 shows an annular recess 22 to eliminate the need for orientation of the components and the conical form 12 terminating at the recess 22 thus shortening the truncated conical component 8 by a length 23, making the design more compact.

Figure 13 shows Fig.1 2 activated by E; the outer angular surface 20 is fully engaged over length 24 with the blind hole B to increase contact and holding capability and the inner angular surface 21 is fully in contact with conical form 12 to underpin the contact of the outer surface 20, creating a wedge effect that is held in position by latching hooks 6.

The following designs of a dual fastening systems have been evolved from all the above and follow the same basic concept of one component causing a second component to expand under an applied load and then the two components become locked together to maintain their assembled position. The castellated and conical components titles have been slightly changed to identify and describe the new design features.

Figure 14 shows an extended castellated component 25 with expanding cantilevers 26 having outer parallel engaging surfaces 27 and inner parallel engaging surface 28 and extended latching cantilevers with latching lugs 29. The activating part is a low-lift component 30 with an initial short conical form 31 followed by a parallel length 32 and finally an inclined slot 33. The inner surface of the latching Iugs 29 locates on the parallel length 32 and a formed lead 34 is positioned in contact with the short conical form 31 prior to activation. The intention is to produce a long, parallel fit in a hole.

Figure 15 shows the assembled position of Fig.14 after activation by an applied load E. The short conical form 31 has lifted expanding cantilevers 26 into a long, tight fit 27 in blind hole B which is maintained in position by the parallel length 28 and the latching lugs 29 have been forced to bend into the inclined slot 33, thus holding the two components together, which finally abut 35 to increased the stability of the assembly.

Figure 16 shows a serrated version that provides for varying expansion and a stepped engagement of the dual fastening system components to accommodate materials and manufacturing tolerances found in coarse applications.

The serrated castellated component 36 has an internal conical form at the lifting end of the latching cantilever 37 with a number of serrations shown that have a short incline 38 followed by a return 39 to begin the next short incline 38.

The serrated conical component 40 has external annular serrations shown that have a corresponding short incline 38 followed by a return 39 to begin the next short incline 38.

Figure 17 shows Fig.16 after activation by an applied load E where the serrated conical component 40 has engaged with the serrated castellated component 36 to a depth that can vary due to the penetrable properties of part C, size of blind hole B, the dimensions of the components 39 and 40, applied load E and the resulting final serration location.

The following Fig.18 to Fig.25 describe typical applications for a dual fastening system that can utilise all or parts of the design variations and features shown in Fig.5 to Fig. 17 as determined by the component and assembly part materials that may be encountered.

Figure 18 shows the truncated conical component as part of a headed fastener 41, prior to assembly, that has been located through a hole in part N and into initial contact with a variant castellated component 42 that is located in the point of a drilled hole M in part C. The initial, pre-determined, gap 0 controls the assembly process.

Figure 19 shows the activation of Fig.19 under the applied load E that has caused the penetration 4 into part C as the latching hooks 6 locate in recesses 9. The engaging movement produced by the load E has caused the gap 0 to close, thus resulting in the headed fastener 41 clamping parts N and C together. An adjusting compression angle introduced to the fasteners head would allow for manufacturing tolerances. Not drawn.

Figure 20 shows a part view of an application requiring a flush fitting internal screw thread 43 where the material of the assembly part C is unsuitable for machining.

The conical form is shown latched into position in the manner as described previously.

The thread could be substituted by an internal spline or shaped hole as required.

Figure 21 shows a part view of an application requiring a projecting threaded stud 44.

Alternatively other flush fitting projections from surface of part C could be introduced, for example, round posts or angled shelf supports. Holes or other shapes could be added to the projections enabling other parts to be attached or supported thus giving further assembly opportunities.

Figure 22 shows a double-ended dual fastening system, prior to activation, intended to replace a conventional dowel and improve its assembly function.

Two opposing castellated components 45 are seated in blind hole B in part C and blind hole P in second part Q. A double-end conical component 46 is positioned between and in contact 47 with the two components 45 and the combined lengths create the gap R between parts C and Q. The three components can be lightly engaged at 47 to preset the required overall length as an aid to production. This operation can be completed away from parts C and Q. Figure 23 shows the double-ended dual fastening system (Ref. Fig.22) after activation.

A load E is applied to second part Q that closes the gap R (Ref. Fig.22) and activates both of the dual fastening systems simultaneously and equally as the components in this instance are symmetrical. The arrangement could vary, but is shown this way for clarity.

The double-ended conical component 46 has engaged with both of the castellated components 45 to create an assembly between part C and second part Q. The components could be of varying sizes and design; determined by the materials used and the application. The load could be applied to both parts or alternatively one side of the system could be assembled first followed by the other.

The improved performance of a dowel provided with a double-ended dual fastening system is achieved by the ability of the system to expand into a holding contact in holes, whereas a conventional dowel requires a tight manufactured fit produced by closely controlled machined tolerances or alternatively with glue to maintain the dowels position.

Another application for a double-ended dual fastening system would be to provide a right-angled version of the double-ended cOnical component to be used in conjunction with two castellated components located in two parts to create a mitred joint. Not drawn.

Figure 24 shows a typical external application utilising a flush filling collar 48 to give operational load support, in this case for a hook 49.

Other examples, using this arrangement, could be for the hook 49 to be replaced by an eyelet, knob or for a collar with a decorative finish.

Figure 25 shows a conical component 50 with a through hole 51. A rod or cable S with an anchor T is located through the hole 51. The dual fastening system is activated and the rod or cable S is held by the anchor T within the body the part C. A further development for a plastic dual fastening system, where a one-part component would simplify assembly, could be achieved by adding a weak contact joint between the castellated component and the conical component that would break as a load is applied.

The weak joint would be a thin piece of material located between the extreme end of the latching hook and the lead diameter of the conical form. Any jagged edges would be in the clear space at the back of the recess when the activation is complete. Not drawn.

Claims (6)

1. CLAIMS1. A dual fastening system derived from the interaction between two component parts, where one component is basically a tube, seated in a blind hole, that has been cut along part of its length to create a number of free to lift expanding and attaching elements and a second, truncated conical, component with a leading diameter that coincides with the internal diameter of the cut tubular component; the system is activated when an end load is applied to the conical component that causes its leading diameter to enter and travel inside the cut end of the tubular component, the conical form forcing the expanding elements to lift outwards and into a holding contact within the blind hole and on completion of the movement the attaching elements become fastened into recesses provided in the conical form thus maintaining the holding contact as the conical component that caused the expansion of the tubular component cannot now be disengaged.See basic dual fastening system drawings Sheet 1/5.
2. 2. A dual fastening system as claimed in Claim 1 where the lifting and attaching elements are located at the active end of the tubular component whose other end is seated on an established reaction surface to absorb the applied load.
3. 3. A dual fastening system as claimed in Claim 1 and Claim 2 where detailed variations to the basic design are introduced that would improve performance.See variation drawings Sheets 2/5 and 3/5.
4. 4. A dual fastening system as claimed in Claim 1 where the conical component is an extended integral part of a fastening application used to create an assembly.See application examples on drawing Sheets 4/5 and 5/5.
5. 5. A dual fastening system as claimed in any proceeding claims that can be made from plastic or metal materials or from a combination of these materials.
6. 6. A dual fastening system substantially as herein described above and illustrated in the accompanying drawings.amendments to the claims have been filed as follows 1. A dual fastening system derived from the interaction between two component parts, where one component is basically a tube, seated in a blind hole, that has been cut along part of its length to create a number of free to lift expanding and attaching elements and a second, truncated conical, component with a leading diameter that coincides with the internal diameter of the cut tubular component wherein the system is activated when an end load is applied to the conical component that causes its leading diameter to enter and travel inside the cut end of the tubular component, the conical form forcing the expanding elements to lift outwards and into a holding contact within the blind hole and on completion of the movement the attaching elements become fastened into recesses provided in the conical form thus maintaining the holding contact as the conical component that caused the expansion of the tubular component cannot now be disengaged.2. A dual fastening system as claimed in Claim I where the lifting and attaching elements are located at the active end of the tubular component whose other end is seated on an established reaction surface to absorb the applied load.3. A dual fastening system as claimed in any proceeding claims that can be made from plastic or metal materials or from a combination of these materials.4. A dual fastening system substantially as herein described above and illustrated in the accompanying drawings.I..... * .S I.... * * * * S... *. * S