GB1603241A

GB1603241A - Rivet and method of riveting

Info

Publication number: GB1603241A
Application number: GB90778A
Authority: GB
Original assignee: LINREAD Ltd
Current assignee: LINREAD Ltd
Priority date: 1978-05-11
Filing date: 1978-05-11
Publication date: 1981-11-18

Description

(54) IMPROVED RIVET AND METHOD OF RIVETING (71) We, LINREAD LIMITED, a British Company of P.O. Box 21, Cox Street, Birmingham B3 1RP, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a fastener designed to be secured by riveting and having an improved form providing for controlled upset thereof, and to a method of installing such riveting fasteners in a component or components.

Conventional solid and tubular rivets have a plain shank with a head or head flange formed at one end. After insertion into a preformed hole in a component or components to be riveted, the other end of the rivet is deformed to form a head or flange and tightly grip the components. The components must have sufficient inherent strength to resist crushing by the forces applied to the rivet in deforming it to form the head or flange at the said other end.

Internally threaded tubular rivets which have a preformed head flange at one end of a tubular shank and are internally threaded are normally installed in components by use of an upsetting tool comprising a screwthreaded mandrel and an anvil. The tubular rivet is screwed onto the mandrel so that the preformed head flange is brought into engagement with the anvil. The body of the fastener thus mounted on the upsetting tool is inserted into aligned holes in two or more components to be riveted so that the head flange lies against one of the components. The tool is then operated to retract the mandrel axially with respect to the anvil, thus applying an axial force to the rivet so as to cause the wall thereof to collapse by outward bulging and form a flange opposed to the head flange, the components being held between the said two flanges.Upon subsequent unthreading of the mandrel from the fastener, the internal threading therein is available to receive if desired a screw or bolt whereby other items may be attached to the riveted components.

Further, if desired such a tubular rivet may be used as a rivet bush, or a blind fitting anchor nut, being inserted in one hole in a single component The above known forms of riveting fastener are suitable for the great majority of applications where the components to be riveted resist distortion and in particular have sufficient resistance to crushing by the forces applied in the upsetting of the fasteners.However, with the greater use being made recently of structural materials which have considerably less resistance to crushing than conventional solid materials, for example panel materials typically of sandwich construction and which include one or more foamed plastics or honey-comb core sections sandwiched between glass fibre reinforced plastics or plywood skins or layers, or brake lining material which is difficult to rivet securely using conventional rivets, the need arises for new riveting fasteners and techniques of riveting which will not damage such materials by crushing upon installation.

It is an object of the present invention to provide a means and method to satisfy the above requirements.

The present invention proposes to provide a riveting fastener comprising a shank terminating at one end in a preformed head and having a deformable tubular shank portion extending axially thereof from the other end, and a bore in said shank extending axially from a step at the inner end of the deformable tubular shank portion towards the head, the wall thickness of the shank surrounding the bore being greater than the wall thickness of the deformable tubular shank portion whereby the resistance of the latter portion to expansion by outward collapse or bulging is substantially less than that of the bored portion so that when compressive forces are exerted in an axial direction on the fastener the deformation of the fastener is limited to the outward collapse or bulging of the deformable shank portion to form thereby a securing flange the base of which is substantially aligned with the step at the inner end of the deformable tubular shank portion.

If the axial length of the fastener between the underside of the preformed head and the inner end of the deformable tubular shank portion is approximately equal to that of the thickness of the component or components to be riveted, it will be seen that when installing the fastener the risk that the component or components will be crushed and thereby damaged is minimised.

The invention further proposes to provide a method of installing in structurally weak and crushable components a riveting fastener which comprises a shank terminating at one end in a preformed head and having a deformable tubular shank portion extending axially thereof from the other end, and a bore in said shank extending axially from a step at the inner end of the deformable tubular shank portion towards the head, such method including the steps of inserting the fastener into a hole in the components with the head thereof abutting against one side of the components, engaging a mandrel with the head end portion of the fastener, engaging an anvil with the outer end of the deformable tubular shank portion, and applying an axial force between the mandrel and the anvil to expand the deformable tubular portion outwardly, and subsequently removing the mandrel and anvil.

The riveting fastener may have a solid head or may be tubular in which case the rivet head is constituted by a head flange.

If the head of the rivet is solid, then the bore of the shank is internally threaded and the mandrel will be threaded to engage the screw threads in the wall of the bore. The bore in a tubular rivet may also be threaded for engagement similarly with a threaded mandrel, or may be plain in which case the mandrel used preferably comprises a stem capable of passing through the tubular shank and a head engageable with the head flange of the fastener. After setting the fastener, the mandrel may be withdrawn for further use, or may be designed so that the stem breaks after the deformable tubular portion of the fastener has been expanded, the mandrel head and any portion of stem remaining connected either remaining in place in the fastener or being removed by being pushed or falling away from the preformed head of the fastener.

The fastener when secured in the components is tamper-resistant as it will spin if attempts are made to drill it out.

The outward expansion or deformation of the deformable tubular shank portion, which forms a securing flange at the end of the shank opposed to the preformed head at the other end, has a form which is dictated by the choice of design of the anvil. A wider flange or spread may be achieved according to the design chosen. The anvil may have a substantially flat face which causes the deformable tubular shank portion to collapse outwardly by bulging and fold over on itself, or may have an annular generally inwardly concave pressure-applying face which engages the end of the deformable tubular shank portion and operates to cause the mouth end of the deformable shank portion to flare outwardly and thereby form a flange. In a further alternative, the anvil may be designed to split the deformable tubular shank portion like a petal.

If desired the shank may have external flutes or knurls, such as in the manner of a conventional drive screw, which may bite mto the components to resist rotation of the fastener when the mandrel is threaded into the bore.

A riveting fastener which has a length a between the underside of the preformed head and the inner end of the deformable tubular shank portion may be installed in a component or components having a thickness greater than a by using a tubular spacer member of "top-hat" form comprising a shank having an outwardly directed head flange at one end of a tubular wall portion of greater internal diameter than the external diameter of the riveting fastener, and a radially inwardly directed annular shoulder at the inner end of such tubular wall portion.The fastener is inserted into a hole in the components from one side thereof, and the spacer member is inserted into the hole from the other side of the components, and then by use of the tool and mandrel as disclosed the deformable tubular shank portion of the fastener is deformed outwardly to form its securing flange within and against the annular shoulder at the inner end of the spacer member. If the axial length of the spacer member between the underside of the head flange thereon and the annular shoulder is b, then components having a thickness of a + b can be riveted by use of this combination of fastener and spacer member, the effective length of which combination is a + b.

A threaded bore of the fastener can, after withdrawal of the mandrel and anvil, be utilised to receive a screw or bolt. If a smooth closed finish is desired than a capping member may be inserted into the bore of the fastener (or of the spacer member if used) after installation. Such a capping member if made of a resilient material, e.g. plastics, is easily inserted by plugging it into position.

The invention is further illustrated by way of example in the accompanying drawings, in which: Figure 1 is a side view, partly in crosssection, of a riveting fastener according to the invention; Figure 2 is a cross-sectional view showing a stage in the installation of the fastener of Figure 1 in a structural panel; Figure 3 is a view, similar to Figure 2, showing the fastener at the completion of upsetting; Figure 4 is a view similar to Figure 3 showing the installed fastener and a capping member; Figure 5 is a cross-sectional view showing the fastener of Figure 1 installed in two panels having a combined thickness greater than the axial length of the fastener, by use of a tubular spacer member; Figure 6 is a side view of the spacer member of Figure 5;; Figure 7 is a cross-sectional view showing the installation of another embodiment of riveting fastener according to the invention in a brake lining; Figure 8 shows a headed mandrel; Figure 9 is a view similar to Figure 7 showing the fastener at the completion of upsetting; Figure 10 shows a frangible mandrel; Figure 11 shows the removal of a frangible mandrel from the fastener of Figure 9; and Figure 12 shows a modification of Figure 11.

Referring to the drawings, Figure 1 shows a riveting fastener 1 according to the invention in the form of a rivet having a solid head 2 at one end of a shank 4. The other end of the shank 4 terminates in a deformable tubular shank portion 6, from the inner end 7 of which there extends in the shank 4, axially towards the head 2, a threaded counter-bore 8. The counter-bore 8 extends from a step at the inner end 7 whereby there is an abrupt change in the radial wall thickness of the rivet shank at the inner end 7 of the deformable portion 6.The radial wall thickness of the shank surrounding the counter-bore 8 is appreciably greater than the radial wall thickness of the shank portion 6, whereby the shank portion 6 is more readily deformable by the application thereto of axial forces to cause outward expansion of the tubular potion 6, the forces that are required to be exerted to expand the shank portion 6 being insufficient to cause deformation of the shank axially inwardly of the inner end 7 of the tubular shank portion 6.

The rivet 1 has an axial length a between the underside of the head 2 and the inner end 7 of the tubular shank portion, and over the length (( can be considered substantially non-deforinable.

Figure 2 shows the installation of the rivet 1 in d preformed hole 9 in a panel 10 and a similar hole in a component 10a to be joined to the panel. The panel 10 is of sandwich construction and typically comprises outer skins of glass reinforced plastics 12, a core 13 of foamed plastics material and a ply-wood layer 14 between the foamed plastics core 13 and one of the outer skins 13.

As seen in Figure 2, the rivet 1 is placed in the components and an upsetting tool has been applied to the mouth end of the shank of the rivet. The upsetting tool, only relevant parts of which are shown, comprises a threaded mandrel 20 engaged within the threaded counter-bore 8 of the rivet, and an anvil 22 having a pressure-applying face 23 which is engaged with the outer end of the deformable tubular shank portion 6. Upon operation of the tool, the mandrel 20 is retracted axially with respect to the anvil 22, and this causes the tubular shank portion 6 to collapse outwardly and form a flange securing the rivet 1 in the panel 10 and component 10a as shown in Figure 3. The form of pressure-applying face 23 inustrated causes the shank portion 6 to collapse by outward bulging and form a folded over head flange 6a as shown in Figure 3.After installation of the rivet 1 as descrbed, the mandrel 20 is unscrewed and the tool removed.

It will be seen that the axial forces applied to the rivet by the upsetting tool during the installation of the rivet do not have to be resisted in compression by the panel 10, and that the upset of the rivet is controlled by being limited to the deformable tubular shank portion 6, whereby the act of installing the rivet will not crush or damage the members to be secured, which is a considerable advantage compared to existing fasteners. The overall thickness of the panel 10 and component 10a to achieve this effect has to be substantially the same as the axial length a of the rivet 1.

The mandrel 20 and anvil 22 may be elements of a conventional hand or powered upsetting tool. In addition, fasteners according to the invention can be installed using a reversible powered screw driver tool if the latter is provided with a threaded mandrel and an anvil similar to the mandrel 20 and anvil 22 illustrated. Such a tool would be used by engaging the tip of the mandrel with the entrance to the threaded counterbore 8, rotating the mandrel until the end of the tubular shank portion 6 meets the anvil, and then continuing rotation to cause the shank portion 6 to collapse (Figure 3).

At this point the tool would declutch and be reversed for removal.

Figure 4 shows the application to the installed fastener 1 of a plastics closure cap 26, which has a stem 27 that is plugged into the counter-bore 8 of the rivet to leave the fastener with a smooth finish, as may be required for example in a food-carrying vehicle.

Figure 1 also shows external flutes or knurls 5 on the shank 4, which, when provided, may bite into the material surrounding the hole in a component to be riveted, to prevent the fastener from rotating when the mandrel is screwed into the counter-bore and to resist any pressure applied to the mandrel which may tend to push the fastener back out of the hole in the component.

Figure 5 illustrates the rivet 1 installed in panels 10 and 10a which together have a combined thickness greater than the axial distance a. To this end, use is made of a tubular spacer member 30, illustrated also in Figure 6, in combination with the rivet.

Spacer member 30 comprises at one end an outwardly directed head flange 31, and has a tubular wall portion 32 of greater internal diameter than the diameter of the shank 4 of the rivet and a radially inwardly directed annular shoulder portion 33 at the inner end of the wall portion 32. Optionally the spacer member may also include a tubular wall portion 34 which is a sliding fit on the shank 4 of the rivet, as shown in broken outline in Figure 6. As seen in Figure 5, the collapsed head flange 6a is formed inside the spacer member 30, more particularly the underside of the head flange 6a is drawn against the annular shoulder 33 of the spacer member. The axial length of the spacer member between the underside of the head flange 31 and the annular shoulder is b, and the combined thickness of the components 10 and 10a is a + b.By providing spacer members of different axial lengths, the rivet 1 can be installed in components having a wide range of thickness.

Figure 7 shows another embodiment of riveting fastener according to the invention in the form of a tubular rivet 100 having a tubular shank 104 and a head 102 constituted by an annular flange at one end of the shank. The other end of the shank 104 terminates in a deformable tubular shank portion 106, the wall thickness of which portion 106 is less than the wall thickness of the fastener 100 from the inner end 107 of the portion 106 to the head 102. The shank portion 106 is therefore the portion of the fastener 100 that is most readily deformable by the application to the fastener of axial forces to cause outward expansion of the tubular portion 106, the forces that are required to be exerted to expand the shank portion 106 being insufficient to cause deformation of the tubular rivet wall portion axially inwardly of the inner end 107 of the tubular shank portion 106.

The rivet 100 is shown in Figure 7 positioned in a preformed hole in a brake lining 110 to be riveted to a brake shoe 110a.

If the bore 108 of the rivet 100 is internally threaded, then the rivet 100 can be set in position by means of an upsetting tool as already described and comprising the threaded mandrel 20 and the anvil 22. However, the particular embodiment of tubular rivet 100 shown has a plain bore 108, and to set the rivet in position use is made of a reusable headed mandrel 120 as shown in Figure 8. Mandrel 120 comprises a threaded stem 121 and a head 121a. The stem 121 of mandrel 120 is passed through the bore 108 so that the head 121a is engaged with the head flange 102 of the rivet 100.The stem 121 of the mandrel is then connected to an upsetting tool which includes the anvil 22, and the tool is operated to retract the mandrel 120 axially with respect to the anvil 22, as depicted schematically in Figure 9, and in the manner already described in connection with the first embodiment. This causes the tubular shank portion 106 to collapse outwardly and form a flange 106a securing the rivet 100 and lining 110 to the brake shoe 110a.

After installation of the rivet 100 as just described, the mandrel 120 may be unscrewed from the upsetting tool and removed for use, to set further rivets. Alternatively, the plain headed mandrel 120' as shown in Figure 10 may be designed so that the stem 122 breaks on completion of installation of the rivet 100, whereby the portion of the stem 122 remaining in the upsetting tool may be removed together with the tool and the anvil 22. The stem 122 may be designed to fracture at a predetermined point, so that when the mandrel breaks the head 122a merely falls away from the rivet 100. If the stem 122 fractures so that a portion thereof remains attached to the head 122a, the head and remaining portion of the stem may be pushed oust of the rivet 100 or, depending upon the orientation of the rivet, may fall out by gravity, as schematically depicted in Figure 11.A frangible mandrel 120' is, of course, designed to break by the application thereto of an axial force greater than that required to cause the collapse of the tubular shank portion 106 but less than that required axially to deform the fastener wall from the bottom 107 of the portion 106 of the head 102.

A closure cap as shown in Figure 4 may be used with the rivet 100. Alternatively, in the modification shown in Figure 12, the portion of mandrel 120' remaining after fracture of the stem is utilised to constitute a closure cap. The portion of stem 122 adjacent the head 122a may be formed to grip the wall of the bore 108, e.g. may be knurled, to retain the head and remaining stem portion in position in the rivet 100.

The invention is not limited to the specific forms described above. The riveting fastener will be made in a ductile material, both steel and aluminium being suitable. Other materials, and obvious modifications and addi tions to the invention, will occur readily to those skilled in the art.

WHAT WE CLAIM IS:- 1. A riveting fastener comprising a shank terminating at one end in a preformed head

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

the mandrel is screwed into the counter-bore and to resist any pressure applied to the mandrel which may tend to push the fastener back out of the hole in the component.

Figure 5 illustrates the rivet 1 installed in panels 10 and 10a which together have a combined thickness greater than the axial distance a. To this end, use is made of a tubular spacer member 30, illustrated also in Figure 6, in combination with the rivet.

Spacer member 30 comprises at one end an outwardly directed head flange 31, and has a tubular wall portion 32 of greater internal diameter than the diameter of the shank 4 of the rivet and a radially inwardly directed annular shoulder portion 33 at the inner end of the wall portion 32. Optionally the spacer member may also include a tubular wall portion 34 which is a sliding fit on the shank 4 of the rivet, as shown in broken outline in Figure 6. As seen in Figure 5, the collapsed head flange 6a is formed inside the spacer member 30, more particularly the underside of the head flange 6a is drawn against the annular shoulder 33 of the spacer member. The axial length of the spacer member between the underside of the head flange 31 and the annular shoulder is b, and the combined thickness of the components 10 and 10a is a + b.By providing spacer members of different axial lengths, the rivet 1 can be installed in components having a wide range of thickness.

Figure 7 shows another embodiment of riveting fastener according to the invention in the form of a tubular rivet 100 having a tubular shank 104 and a head 102 constituted by an annular flange at one end of the shank. The other end of the shank 104 terminates in a deformable tubular shank portion 106, the wall thickness of which portion 106 is less than the wall thickness of the fastener 100 from the inner end 107 of the portion 106 to the head 102. The shank portion 106 is therefore the portion of the fastener 100 that is most readily deformable by the application to the fastener of axial forces to cause outward expansion of the tubular portion 106, the forces that are required to be exerted to expand the shank portion 106 being insufficient to cause deformation of the tubular rivet wall portion axially inwardly of the inner end 107 of the tubular shank portion 106.

The rivet 100 is shown in Figure 7 positioned in a preformed hole in a brake lining 110 to be riveted to a brake shoe 110a.

If the bore 108 of the rivet 100 is internally threaded, then the rivet 100 can be set in position by means of an upsetting tool as already described and comprising the threaded mandrel 20 and the anvil 22. However, the particular embodiment of tubular rivet 100 shown has a plain bore 108, and to set the rivet in position use is made of a reusable headed mandrel 120 as shown in Figure 8. Mandrel 120 comprises a threaded stem 121 and a head 121a. The stem 121 of mandrel 120 is passed through the bore

108 so that the head 121a is engaged with the head flange 102 of the rivet 100.The stem 121 of the mandrel is then connected to an upsetting tool which includes the anvil 22, and the tool is operated to retract the mandrel 120 axially with respect to the anvil 22, as depicted schematically in Figure 9, and in the manner already described in connection with the first embodiment. This causes the tubular shank portion 106 to collapse outwardly and form a flange 106a securing the rivet 100 and lining 110 to the brake shoe 110a.

After installation of the rivet 100 as just described, the mandrel 120 may be unscrewed from the upsetting tool and removed for use, to set further rivets. Alternatively, the plain headed mandrel 120' as shown in Figure 10 may be designed so that the stem 122 breaks on completion of installation of the rivet 100, whereby the portion of the stem 122 remaining in the upsetting tool may be removed together with the tool and the anvil 22. The stem 122 may be designed to fracture at a predetermined point, so that when the mandrel breaks the head 122a merely falls away from the rivet 100. If the stem 122 fractures so that a portion thereof remains attached to the head 122a, the head and remaining portion of the stem may be pushed oust of the rivet 100 or, depending upon the orientation of the rivet, may fall out by gravity, as schematically depicted in Figure 11.A frangible mandrel 120' is, of course, designed to break by the application thereto of an axial force greater than that required to cause the collapse of the tubular shank portion 106 but less than that required axially to deform the fastener wall from the bottom

107 of the portion 106 of the head 102.

A closure cap as shown in Figure 4 may be used with the rivet 100. Alternatively, in the modification shown in Figure 12, the portion of mandrel 120' remaining after fracture of the stem is utilised to constitute a closure cap. The portion of stem 122 adjacent the head 122a may be formed to grip the wall of the bore 108, e.g. may be knurled, to retain the head and remaining stem portion in position in the rivet 100.

The invention is not limited to the specific forms described above. The riveting fastener will be made in a ductile material, both steel and aluminium being suitable. Other materials, and obvious modifications and addi tions to the invention, will occur readily to those skilled in the art.

WHAT WE CLAIM IS:- 1. A riveting fastener comprising a shank terminating at one end in a preformed head

and having a deformable tubular shank portion extending axially thereof from the other end, and a bore in said shank extending axially from a step at the inner end of the deformable tubular shank portion towards the head, the wall thickness of the shank surrounding the bore being greater than the wall thickness of the deformable tubular shank portion whereby the resistance of the latter portion to expansion by outward collapse or bulging is substantially less than that of the bored portion so that when compressive forces are exerted in an axial direction on the fastener the deformation of the fastener is limited to the outward collapse or bulging of the deformable shank portion to form thereby a securing flange the base of which is substantially aligned with the step at the inner end of the deformable tubular shank portion.
2. A riveting fastener according to Claim 1 which comprises a solid head.
3. A riveting fastener according to Claim 1, wherein the bore extends through to the said one end of the shank and the preformed head is constituted by a head flange.
4. A riveting fastener according to any one of Claims 1 to 3, wherein the bore in the shank is internally threaded.
5. A riveting fastener according to Claim 3, wherein the bore is a plain bore.
6. A riveting fastener according to any one of Claims 1 to 5, wherein the shank is provided with external flutes or knurls.
7. A riveting fastener according to any one of Claims 1 to 6, in combination with a tubular spacer member comprising a shank having an outwardly directed head flange at one end of a tubular wall portion of greater internal diameter than the external diameter of the riveting fastener, and a radially inwardly directed annular shoulder at the inner end of such tubular wall portion within and against which the deformable tubular shank portion of the fastener can be deformed outwardly to form its securing flange.
8. A riveting fastener according to any one of Claims 1 to 7, including a capping member for insertion into the bore of the fastener (or of the spacer member if present) after installation.
9. A riveting fastener according to Claim 8, wherein the capping member is made of a resilient material.
10. A method of installing in structurallv weak and crushable components a riveting fastener which comprises a shank terminating at one end in a preformed head and having a deformable tubular shank portion extending axially thereof from the other end, and a bore in said shank extending axially from a step at the inner end of the deformable tubular shank portion towards the head, such method including the steps of inserting the fastener into a hole in the components with the head thereof abutting against one side of the components, engaging a mandrel with the head end portion of the fastener, engaging an anvil with the outer end of the deformable tubular shank portion, and applying an axial force between the mandrel and the anvil sufficient to expand the deformable tubular portion outwardly, and subsequently removing the mandrel and anvil.
11. A method according to Claim 10, wherein the mandrel is designed to break upon the application thereto of an axial force in excess of that required to expand the deformable tubular portion of the fastener.
12. A method according to Claim 10 or Claim 11, wherein the anvil has a substantially flat face which causes the deformable tubular shank portion to collapse outwardly by bulging and fold over on itself.
13. A method according to Claim 10 or Claim 11, wherein the anvil has an annular generally inwardly concave pressure-applying face which engages the end of the deformable tubular shank portion and operates to cause the mouth end of the deformable shank portion to flare outwardly and thereby form a flange.
14. A method according to Claim 10 or Claim 11, wherein the anvil is designed to split the deformable tubular shank portion like a petal.
15. A riveting fastener substantially as hereinbefore described with reference to the accompanying drawings.
16. A method of installing a riveting fastener, substantially as described with reference to the accompanying drawings.