HK1237017A1 - Self-piercing rivet - Google Patents

Description

Self-drilling rivet

Technical Field

The invention relates to a self-drilling rivet comprising a support collar and an expandable hollow tubular body, the body having: a first cylindrical portion adjacent the collar at one end, a second cylindrical portion at the other end of the body arranged to receive a drilling element, and an expandable third portion between the first and second cylindrical portions.

Background

It is known to assemble two elements (e.g. one component and one support) together in a simple manner using self-drilling expandable anchor bolts.

Documents FR 2927382 and FR 2992698 describe self-drilling anchor bolts each having a head in the form of a collar, a drilling end and a bolt body extending between the collar and the drilling end. The bolt body has a tapped portion adapted to mate with the threads of the screw. However, in the automotive industry, those types of self-drilling anchor bolts are not satisfactory for manufacturers because the protruding drilling end may cause injury to operators handling the components that have been secured together after the drilling and assembly operations.

In addition, after the drilled ends of the self-drilling anchor bolts are secured to the elements to be secured together, the drilled ends increase the size of those anchor bolts.

Documents US2015/0043995 and CA 2080065 describe self-drilling anchor bolts, each having a drilling end that can be manually removed by an operator after drilling and assembly operations. When the drilling end is not visible or is difficult to access after assembly, manual removal of the drilling end can be difficult, and therefore those self-drilling anchor bolts cannot improve the rate of assembly of the components in the motor vehicle.

Additionally, self-drilling anchor bolts currently in use typically have a bolt body with apertures at both ends. Those apertures interfere with establishing a seal between one side and the other of the elements for assembly that have been assembled together by prior art self-drilling anchor bolts.

In addition, when drilling composite elements using self-drilling anchor bolts, the self-drilling anchor bolts cannot drill "clean" holes because they often cause delamination and tearing of the fibers during drilling, and they also emit dust in an uncontrolled manner. Thus, manufacturers also seek to assemble two components together while avoiding the deposition of dust or drilling debris.

Finally, manufacturers are also seeking to use self-drilling anchor bolts with better shear strength and better tear strength.

Disclosure of Invention

The object of the present invention is to provide a self-drilling rivet which is more compact, is not "aggressive", limits the amount of residue emitted during drilling and still remains compatible with the constraints of the motor vehicle industry for assembling two elements together.

More specifically, the invention provides a self-drilling rivet comprising a supporting collar (bearing ring) and an expandable hollow tubular body having a first cylindrical portion at one end adjacent the collar, a second cylindrical portion at the other end of the body arranged to receive a drilling element, and an expandable third portion between the first and second cylindrical portions, characterised in that the third portion of the body and the drilling element have respective connection means arranged to separate the drilling element from the body during expansion of the third portion of the body.

The self-drilling rivet of the invention may also have the following features:

the hollow tubular body may have a solid axial wall;

the body may have an end wall located on the second cylindrical portion;

the second cylindrical portion may have internal threads;

the expandable third portion may be arranged to deform radially as the second cylindrical portion of the internal thread is driven by traction in axial translation towards the collar;

the second cylindrical portion may be arranged to receive a cylindrical rod extending axially in the body;

the stem may have a first stem portion at one end extending in the first cylindrical portion of the hollow body and projecting beyond the collar of the exterior of the body;

the rod may have a second rod portion at its other end arranged to be received in the second cylindrical portion of the body, the second rod portion having a shoulder for cooperating with the narrowed section of the second cylindrical portion of the body to prevent axial movement of the rod in the body;

the expandable third portion of the body may be arranged to deform radially when the first stem portion of the stem is driven in axial translation by traction;

the stem may have a third stem portion located between the first stem portion and the second stem portion and comprising a frangible region, the third stem portion being arranged such that a portion of the third stem portion is inserted into the first cylindrical portion of the body when the third portion of the body is fully radially expanded;

the portion of the third shaft portion may be defined by a frangible region arranged to lie flush with the collar when the third portion of the body is fully radially expanded;

the drilling element may be in the form of a hollow cylinder mounted via a first end on a second cylindrical portion of the body;

the second cylindrical portion of the body may have a flat portion for preventing rotation of the drilling element relative to the body when the drilling element is mounted on the body;

the drilling element may have a drilling tool in the form of a crown saw (barrel saw) at the second end;

the hollow cylinder of the boring element may have a rim projecting towards the interior of the hollow cylinder between the first and second ends of the boring element to block engagement of the hollow cylinder on the second cylindrical portion of the body;

the drilling element may have first connection means for connecting to the body;

first connecting means for connecting the drill member to the body are in the form of flexible tabs extending axially beyond the first end;

the flexible tabs of the drilling elements may have a rough outer surface;

the expandable third portion of the body may have second connection means for connecting to a drilling element;

the second connecting means for connecting the expandable third portion of the body with the drilled element is in the form of a recess arranged to receive the flexible tab of the drilled element;

the rivets may be made of rolled and welded metal plates; and

the rivet may be made of stamped sheet metal.

With the self-drilling rivet of the present invention, it is possible to quickly and easily assemble two plates or a member with a support. The panel may also be a vehicle floor mat.

By means of the arrangement according to the invention, a compact fastening and a rivet construction which is less dangerous for the operator can be achieved.

After the elements for assembly have been drilled by rotating the rivet with a screwdriver tool cooperating with a threaded portion or projecting rod, the collar bears against the upper element for assembly, then the traction on the tool in axial translation drives the radial expansion of said body, while at the same time automatically ejecting the drilling element from the body, as it is pushed out by the deformation of the third portion of the rivet body.

Ejecting the drilling element enables the operator to continue working without any risk of injury by the drilling tool and this also reduces the space taken up by the rivet.

By performing the drilling and anchoring steps of the self-drilling rivet through the two plates, the two elements are assembled together and this can be done quickly in a simple manner, since it is performed in a single operation when using suitable screwing and pulling tools.

In addition, the arrangement of the drilling element with rough areas and hollow cylinders enables both the drilling of "clean" holes and the retention of emitted drilling debris and dust within the drilling element. Thus, the material is ejected from the rivet body in the form of a "slug" together with the drilling element.

Rivet bodies with threaded portions or stem portions having end walls and solid walls are used to provide side-to-side sealing of assembled elements.

After traction is applied to the stem, a portion of the third portion of the stem remains partially blocked within the first portion of the body adjacent the collar, thereby completely filling the first portion of the rivet body to strengthen the structure of the expanded rivet. The additional and calibrated axial traction exerted on the rod causes the rod to break off in the frangible region so that the broken rod does not protrude beyond the collar and flush with the collar.

Sheet metal rivets with an expanded body including a stem portion provide greater tear and shear strength, meeting automotive industry constraints.

Drawings

The invention will be better understood and other advantages will appear from a reading of the following description and the accompanying drawings, in which:

FIG. 1 is a perspective view of a self-drilling rivet in a first embodiment of the invention;

FIG. 2 is an exploded view of the self-drilling rivet of FIG. 1;

FIG. 3 is a profile view of a self-drilling rivet in a first embodiment of the invention;

FIG. 4 is an axial cross-sectional view of the self-drilling rivet of FIG. 3;

FIG. 5 is an axial cross-sectional view of a self-drilling rivet in a first embodiment of the invention, with its body radially expanded;

FIG. 6 is a perspective view of a self-drilling rivet in a second embodiment of the invention;

FIG. 7 is an exploded view of the self-drilling rivet of FIG. 6;

FIG. 8 is a profile view of a second embodiment of a self-drilling rivet;

FIG. 9 is an axial cross-sectional view of the self-drilling rivet of FIG. 8; and

FIG. 10 is an axial cross-sectional view of a self-drilling rivet according to a second embodiment of the invention, the body of which is radially expanded.

Detailed Description

Fig. 1 to 5 show a rivet 1 for assembling two elements, in particular two plates (P and P' as shown in fig. 5), together in a first embodiment of the invention. As a non-limiting example, the plates may be made of fiberglass.

The rivet 1 comprises a tubular body 2 having both a collar 3 at one end, which bears against one of the two plates to be assembled together for example, and a region (described below) at the other end of the body 2, on which a drilling element 4 is engaged by a sliding fit, this element being visible in the exploded view of fig. 2 in isolation.

As shown in fig. 2, the collar 3 extends in a plane perpendicular to the axis AA of the rivet 1.

The collar 3 may have teeth (not shown) that bite into the surface against which it bears to prevent it from rotating about the axis. The collar 3 may also have a cut around the access hole to the inside of the tubular body 2.

The tubular body 2 is hollow in the form of a drum or cylinder with solid axial walls.

The body 2 comprises three portions extending along an axis AA: a first cylindrical portion 5 adjacent to the collar 3, a second cylindrical portion 6 corresponding to the region for arranging the drilling element 4 by means of an axial sliding fit, and an intermediate third portion 7 between these two cylindrical portions 5 and 6.

The height of the first cylindrical portion 5 generally corresponds to the thickness of the plates P and P' intended to be assembled together.

In a first embodiment, as can be seen in fig. 4, the second cylindrical portion 6 may be internally threaded so as to cooperate with the thread of a screwdriver tool passing through the tubular body 2 via the hole of the collar 3. In this example, the internal thread is located on a tapping punch bushing 8 which is fixed to the second part 6 below the radial narrowing forming the shoulder 20. The bush 8 is fixed to the body 2 by welding or crimping.

The outer surface of the second cylindrical portion 6 may have axially extending flats 9, in this embodiment three flats 9, to facilitate mounting of the drilling element 4 on the second portion 6 of the rivet body 2 and to prevent rotation of the drilling element 4 relative to the rivet body 2.

The second cylindrical portion 6 of the rivet body 2 may have an end wall, as shown in fig. 4.

In this embodiment, the central third portion 7 of the rivet body 2 is in the form of a punch cylinder having an annular zone of weakness 10 in a central transverse plane so that the third portion 7 of the body 2 can expand radially.

The expandable intermediate third portion 7 of the rivet body 2 has first connecting means 11 for connection with the drilling element 4. In this embodiment, three notches 11 projecting towards the inside of the body 2 are arranged axially consecutively to the flat 9 of the second portion 6 of the rivet body 2.

The drilling element 4 is in the form of a hollow cylinder which can be mounted to the second cylindrical portion 6 of the body 2 via the first end 12. The cylindrical inner surface of the drilling element 4 has an edge 13 in the form of a press-in projection visible in fig. 4 and projecting towards the inside of the cylinder to prevent the second part 6 of the rivet body 2 from moving axially when the drilling element 4 is mounted on the second cylindrical part 6 of the body 2.

At the second end, the boring element 4 has a boring tool 14, in particular in the form of a circular crown saw with two-stage toothing. The crown saw has an inner bore and its teeth are distributed circumferentially around the bore to reduce dust generation and fiber extraction during drilling. Thus, during drilling, drilling debris accumulates within the hollow cylinder of the drilling element 4.

The second end of the boring tool 14 may be a diamond coated drill bit type end piece (not shown) without departing from the scope of the invention.

The drilled element 4 has second connection means 15 for connection to the rivet body 2 (more specifically, the intermediate third portion 7 of the rivet body 2), for example in the form of a flexible tab 15 extending axially beyond the first end 12 of the drilled element 4.

In this example, the flexible tab 15 of the drilled element 4 has a rough outer surface, making it possible to improve the quality of the drilling, the end 16 of the flexible tab being inclined towards the inside of the drilled element 4.

Before use, it is necessary to mount the drilling element 4 of the self-drilling rivet 1 on the body 2 of the rivet 1. To this end, while axially mounting the drilling element 4 on the body 2 of the rivet 1, the flexible tabs 15 are spread apart when in contact with the second portion 6 and they slide along the flat 9 of the second portion 6 of the body 2 of the rivet 1. Thereafter, the second cylindrical portion 6 penetrates axially into the hollow cylinder of the drilling element 4 until the inclined end 16 of the flexible tab 15 is housed in the recess 11 of the expandable third portion 7 of the body 2 of the rivet 1. The body 2 of the rivet 1 is prevented from moving axially in the hollow cylinder of the boring element 4 by the inwardly projecting press-in projection edge 13 of the boring element 4. In the present invention, the first connecting means 11 and the second connecting means 15 need to be chosen so as to be able to withstand the rotation applied to the rivet 1 during drilling.

In the present invention, the flat 9 on the second portion 6 of the body 2 also serves to prevent the drilling element 4 from turning relative to the body 2 of the rivet 1 when the drilling element 4 is mounted onto the body 2 of the rivet 1, thus enabling the rotation exerted by the screwdriver tool on the body 2 of the rivet 1 to be transmitted to the drilling element 4.

The rivet 1 is put in place through the two plates P and P 'so that the plates are assembled by driving the rivet 1 rotationally in a conventional screw driving direction by means of a tool acting on the bush 8, which tool passes through the collar 3 so that a hole is made through the two plates P and P' and the plates are assembled together, as shown in fig. 5.

When the collar 3 bears against the upper plate P for assembly together, the second portion 6 of the body 2 is raised towards the collar 3 by means of a tool exerting traction on the threads of the bush 8, thus radially deforming the expandable third portion 7. This radial deformation of the third portion 7 of the body 2 causes the flexible tab 15 to spread apart, so that the end 16 comes out of contact with the notch 11, thus ejecting the drilling element 4 from the body 2 of the rivet 1. This arrangement thus enables the drilling elements 4 containing drilling residues to be simultaneously axially ejected from the body 2 in an automatic manner by the thrust generated by the deformation of the third portion 7 of the body 2 of the rivet 1.

When the third portion 7 is fully expanded, as shown in fig. 5, the third portion 7 of the body 2 forms a bead 17 under the assembled panels P and P'. The bead 17 provides good tear strength and good shear strength. So that the rivet 1 is anchored on both sides of the two plates P and P'.

In the present invention, the rough outer surface of the flexible tabs 15 of the drilled element 4 is used to smooth the inside of the hole to eliminate protruding fibers and/or localized delamination areas.

In a second embodiment of the invention, the stem 18 may be arranged in the rivet body 2 instead of the bushing 8 in the rivet body 2 for cooperation with a screwdriver tool. This variant of the invention is illustrated in figures 6 to 10.

Elements common to both embodiments have the same reference numerals and are not described in detail.

Fig. 6 and 7 show a rivet 1 'according to a second embodiment of the invention for assembling two elements, in particular two plates (P and P' as shown in fig. 10) together.

The rivet 1' has: a hollow tubular body 2 in the form of a drum having a solid axial wall, a first cylindrical portion 5, a second cylindrical portion 6 and a third cylindrical portion 7 extending along an axis AA; a collar 3; and the area on which the drilling element 4 engages with a sliding fit, the drilling element being seen separated in the exploded view of fig. 7.

In a second embodiment, the rivet 1' has a shank 18, which in this embodiment is substantially cylindrical, as can be seen in a separated manner in fig. 7.

The stem 18 for insertion in the body 2 of the rivet 1' comprises three portions extending along the axis AA: a first portion 19 of the stem 18, intended to be inserted in the first portion 5 of the body 2 of the rivet 1', having a length such as to also project beyond the collar 3 outside the body 2 of the rivet 1'; a second portion 21 of the stem 18, intended to be housed in the second portion 6 of the body 2 of the rivet 1'; and a third portion 22 located between the first portion 19 and the second portion 21 of the stem 18, which is housed in the third portion 7 of the body 2 of the rivet 1'.

The portion of the first portion 19 of the stem 18 projecting with respect to the rivet body 2 is used to drive said rivet 1' rotationally in a conventional screw driving direction by means of a tool acting on this portion extending outside the body 2 and also to exert an axial traction.

The second portion 21 of the stem 18 in this embodiment is bullet-shaped with a shoulder 23 which cooperates with a narrowing 20 forming a shoulder in the second portion 6 of the body 2 to prevent the stem 18 from moving axially in the body 2 of the rivet 1'. A second flat (not shown) of the body 2 formed on the inner surface of the second portion 6 of the rivet body 2 engages the second portion 21 of the stem 18 to prevent rotation of the stem 18 relative to the body 2 of the rivet 1'. Thus, the body 2 and the lever 18 are constrained to rotate together about the axis.

The third portion 22 of the stem 18 in this example has a narrowed region corresponding to a region 24 which is frangible under appropriate axial traction. The drilling element 4 is mounted to the second cylindrical portion 6 of the body 2 of the rivet 1' in the same way as described above.

In a second embodiment, a rivet 1 'is placed in position in the two plates P and P' to be assembled together by rotationally driving the rivet 1 'in a conventional screw driving direction using a tool acting on the rod 18, thereby making a hole through the two plates P, P' and assembling them together, as shown in fig. 10.

As mentioned above, when the collar 3 bears against the upper plate P of the plates for assembly together, the second portion 6 of the body 2 is raised towards the collar 3 by means of a tool exerting traction on the stem 18, thus radially deforming the expandable third portion 7, so that the drilling element 4 is disengaged from the body 2 of the rivet 1' by self-ejection.

When the third portion 7 is fully expanded, as shown in figure 10, in addition to the presence of the bead 17 under P and P 'assembled together, the presence of a portion of the third portion 22 of the stem 18 in the first portion 5 of the body 2 of the rivet 1' also enhances the tear and shear strength. The frangible region 24 is arranged so that after the elements P and P 'have been assembled together, the stem 18 is broken in the frangible region 24 so that the portion of the stem 18 that remains inside the body 2 of the rivet 1' does not extend from the body 2 of the rivet 1', but rather the portion of the stem 18 that remains inside the body 2 of the rivet 1' is flush with the collar 3.

In this second embodiment, when the rivet 1' is anchored against both sides of the two plates P and P ', the portion of the stem 18 left inside the body 2 of the rivet 1' is used to fill the entire expanded hollow body, thus mechanically reinforcing the rivet and also sealing the assembly.

In the present invention, the rivets 1, 1' may be made of rolled and welded metal plates or stamped metal plates.

Thus, the drilling element 4 may be clinched from rolled sheet metal by dovetail, welding or crimping, or it may be formed from stamped sheet metal.

The rivets 1, 1' can also be moulded entirely from plastic material or injected from plastic material so that they can be manufactured at low cost and used for assembling e.g. two vehicle floor mats or floor mats with a board.

Without limitation, the rivet 1 may also be used for fixing wiring tunnels, for positioning heavy or light fixing systems, or indeed for internal fixing of vehicles with metallic or composite bodywork.

The rivet 1 may also be made by additive manufacturing of a 3D printer, for example, if manufactured only for a short period.

Claims (22)

1. A self-drilling rivet (1) comprising a supporting collar (3) and an expandable hollow tubular body (2), the body (2) having a first cylindrical portion (5) at one end adjacent the collar (3), a second cylindrical portion (6) at the other end of the body (2) arranged to receive a drilling element (4) and an expandable third portion (7) between the first cylindrical portion (5) and the second cylindrical portion (6), characterised in that the third portion (7) of the body (2) and the drilling element (4) have respective connecting means (11, 15) arranged to separate the drilling element (4) from the body (2) during expansion of the third portion (7) of the body (2).

2. A self-drilling rivet (1) according to claim 1, characterized in that the hollow tubular body (2) has a solid axial wall.

3. A self-drilling rivet (1) according to claim 1 or 2, characterized in that the body (2) has an end wall located on the second cylindrical portion (6).

4. Self-drilling rivet (1) according to claim 1, characterized in that said second cylindrical portion (6) has an internal thread.

5. A self-drilling rivet (1) according to claim 4, characterised in that the expandable third portion (7) is arranged to deform radially when the internally threaded second cylindrical portion (6) is driven by traction in axial translation towards the collar (3).

6. A self-drilling rivet (1) according to claim 1, characterized in that the second cylindrical portion (6) is arranged to receive an axially extending cylindrical stem (18) in the body (2).

7. A self-drilling rivet (1) according to claim 6, characterized in that said stem (18) has at one end a first stem portion (19) which extends in said first cylindrical portion (5) of the hollow body (2) and projects beyond said collar (3) outside said body (2).

8. A self-drilling rivet (1) according to claim 7, characterized in that said stem (18) has at its other end a second stem portion (21) arranged to be housed in said second cylindrical portion (6) of said body (2), and said second stem portion (21) has a shoulder (22) for cooperating with the narrowing (20) of said second cylindrical portion (6) of said body (2) to prevent axial movement of said stem in said body (2).

9. A self-drilling rivet (1) according to claim 8, characterized in that the expandable third portion (7) of the body (2) is arranged to deform radially when the first stem portion (19) of the stem is driven in axial translation by traction.

10. A self-drilling rivet (1) according to claim 9, characterized in that the stem has a third stem portion (22) located between the first stem portion (19) and the second stem portion (21) and comprising a frangible region (24), and in that the third stem portion (22) is arranged so that a portion of the third stem portion (22) is inserted in the first cylindrical portion (5) of the body (2) when the third portion (7) of the body (2) is fully radially expanded.

11. A self-drilling rivet (1) according to claim 10, characterized in that said portion of the third stem portion (22) is defined by said frangible region (24) arranged flush with the collar (3) when the third portion (7) of the body (2) is fully radially expanded.

12. A self-drilling rivet (1) according to claim 1, characterized in that the drilling element (4) is in the form of a hollow cylinder for mounting on the second cylindrical portion (6) of the body (2) via a first end (12).

13. A self-drilling rivet (1) according to claim 12, characterized in that the second cylindrical portion (6) of the body (2) has a flat (9) for preventing the drilling element (4) from rotating with respect to the body (2) when the drilling element (4) is mounted on the body (2).

14. A self-drilling rivet (1) according to claim 12, characterized in that the drilling element (4) has a drilling tool (14) in the form of a crown saw at the second end.

15. A self-drilling rivet (1) according to claim 14, characterized in that the hollow cylinder of the drilling element (4) has a rim (13) which protrudes towards the inside of the hollow cylinder between the first end (12) and the second end of the drilling element (4) to block the engagement of the hollow cylinder on the second cylindrical portion (6) of the body (2).

16. A self-drilling rivet (1) according to claim 12, characterized in that the drilling element (4) has first connecting means (15) for connection to the body (2).

17. A self-drilling rivet (1) according to claim 16, characterized in that the first connecting means (15) for connecting the drilling element (4) to the body (2) are in the form of a flexible tab (15) extending axially beyond the first end (12).

18. A self-drilling rivet (1) according to claim 17, characterized in that the flexible tab (15) of the drilling element (4) has a rough outer surface.

19. A self-drilling rivet (1) according to claim 16, characterized in that the expandable third portion (7) of the body (2) has second connecting means (11) for connection to the drilling element (4).

20. A self-drilling rivet (1) according to claim 19, characterized in that the second connecting means (11) for connecting the expandable third portion (7) of the body (2) with the drilling element (4) are in the form of notches arranged to receive flexible tabs (15) of the drilling element (4).

21. Self-drilling rivet (1) according to claim 1, characterized in that it is made of rolled and welded metal sheet.

22. Self-drilling rivet (1) according to claim 1, characterized in that it is made of stamped sheet metal.