GB2147385A

GB2147385A - Blind rivets

Info

Publication number: GB2147385A
Application number: GB08424179A
Authority: GB
Inventors: Joseph J Braychak; John P Casey
Original assignee: Tucker Fasteners Ltd
Current assignee: Tucker Fasteners Ltd
Priority date: 1983-09-29
Filing date: 1984-09-25
Publication date: 1985-05-09
Also published as: DE3435587A1; ES291602U; IT8422906A0; AU3368084A; FR2552830B1; ES291602Y; AU569327B2; FR2552830A1; DE3435587C2; JPS6091007A; CA1253017A; IT1175760B; GB8424179D0; GB2147385B

Abstract

A blind rivet body (12) has a plurality of longitudinally-extending circumferentially-spaced weakened lines (26) terminating in spaced relation from the rivet flange (14) and the open end (16) of the rivet body (12) so that upon setting by pulling the mandrel head (24) towards the flange (14), the rivet body separates at the weakened lines (26) to form a plurality of outwardly extending doubled-over petals (32, 34, 36) forming an enlarged secondary head on the rivet body (12). <IMAGE>

Description

SPECIFICATION Blind rivet Background of the Invention Field of the Invention This invention relates to blind rivets and particularly blind rivets having a iarge secondary head.

Statement as to Prior Art There are a number of different types of blind rivets on the market which have a hollow rivet body with a flanged head on one end and open on the opposite end. A mandrel stem is adapted to pass through the opening in the body of the rivet with the mandrel stem having a head position adjacent the open end of the rivet body. The rivet body can then be inserted into the opening in a workpiece with the flange of the rivet lying flat against the surface of the workpiece. The nosepiece of a rivet setting tool is placed against the flange of the rivet body and by pulling the mandrel, the rivet body opposite the flange is upset by the head of the mandrel on the opposite side of the workpiece to form a secondary head on the rivet body thus, securing the rivet to the workpiece. This process is generally known in the art as "setting" the rivet.A continued pulling force on the mandrel stem will break off the mandrel stem from the mandrel head permitting removal of the mandrel stem from the rivet. In this manner, the rivet is secured in the opening in the workpiece with the flange of the rivet against one surface of the workpiece and the formed secondary head against the opposite surface of the workpiece.

Examples of rivets of this type and tools for setting the rivets are illustrated in U.S. Patent numbers 3,254,522; 3,302,444 and 3,324,700.

In the aforementioned types of blind rivets, the rivet body is generally slightly smaller than the opening of the workpiece. Further, the length of rivet body is slightly longer than the thickness of the workpiece. Thus, in the "setting" of the rivet, the secondary head is smaller than the flanged end of the rivet.

Further, in this type of rivet, as the mandrel head is forced against the rivet body to form the secondary head, resulting lateral forces from the rivet body act against the opening in the workpiece. If the workpiece is a soft material, these lateral forces will enlarge or otherwise deform the opening in the workpiece leaving a poor connection.

It is therefore an object of this invention to provide a blind rivet which has a rivet body configuration which can form the secondary head permitting the rivet to be used in soft material.

It is another object of this invention to provide a rivet with an enlarged secondary head to provide a larger bearing area on the workpiece to reduce the likelihood of failure of the bearing area between the secondary head and a workpiece of soft material or workpieces that have holes slightly larger than the body of the rivet.

It is further object of this invention to provide a blind rivet that is capable of fastening a wide range of thickness of workpieces together.

It is also an object of this invention to provide a blind rivet having a rivet body with longitudinally disposed preformed areas of weakness along the body to form the secondary head. The rivet body is of a length such that a wide range of thickness of workpieces can be secured together. During the setting operation, the rivet body is adapted to separate along the longitudinal areas of weakness to form a plurality of spaced petals that form the secondary head.

It is an additional object of this invention to provide longitudinally extending weakened areas along the body of a rivet forming abutting solid body portions which separate when the rivet is set to form an enlarged secondary head on the rivet.

These and other objects will become apparent from the accompanying description along with the drawings.

Brief Description of Drawings Figure 1 is an illustration of the blind rivet assembled on a mandrel; Figure 2 is an illustration of the blind rivet in a workpiece and illustrating the forming of the rivet body at the beginning of setting operation; Figure 4 is an illustration of the set rivet with mandrel removed; Figure 5 is an illustration of the rivet positioned through a considerable thickness of material; Figure 6 is an illustration of the rivet positioned through a thin workpiece; and Figure 7 is an enlarged sectional view taken along the line 7-7 of Figure 1.

Description of the Preferred Embodiment Attention is now directed to Figure 1 which illustrates the rivet 10 having a cylindrical open body 1 2 with a flange 1 4 disposed on one end normal to the longitudinal extent of the body 12. The rivet body 12 is open at 16 on the end 1 8 opposite the flange 1 4.

A mandrel 20 has a stem 22 adapted to pass through the rivet body 1 2 and head 24 adapted to seat against the end 1 8 of the rivet body 1 2. There is a shoulder (not shown) adjacent the mandrel head that has an interference fit into the opening 1 6 to retain the mandrel and rivet in assembled condition, as is well known in the art. The rivet body is adapted to be inserted through the opening in a workpiece and by holding the flange against the workpiece and pulling on the mandrel stem, the mandrel head is forced against the open end of the rivet body to upset the rivet body to form a secondary head on the rivet.

This is a well known procedure in the art of setting blind rivets.

In the conventional rivet, the rivet is supplied in many diameters and lengths so that the rivet body is sized to the opening in the workpiece and the thickness of the workpiece.

That is, in the conventional rivet, a rivet size and length is selected so that the rivet body is slightly smaller than the size of the opening in the workpiece and the rivet length is slightly longer than the thickness of the workpiece, so that, upon forming the rivet, the rivet body has a tight fit in the opening in the workpiece and the secondary head is forced against the surface of the workpiece in a small area.

The rivet of this invention overcomes the necessity of having a plurality of different sized rivets and is able to not only be utilised in a workpiece material that is soft, but will also secure workpieces together that have a wide range of thickness.

As illustrated in Figure 1, the rivet body 12 has a plurality of elongated weakened areas 26 extending longitudinally of the body 1 2 and spaced at 28 and 30 from the flange 1 4 and end 18 of the rivet body. The weakened areas 26 are substantially through the material thickness of the body itself to localise the area in which the rivet body will deform during the forming of the rivet. The weakened areas 26 also are formed in the rivet body without changing the circular cross-sectional contour of the rivet body. Further, with the weakened areas terminating spaced from the flange and end of the rivet body, the flange will not tear loose from the rivet body and the mandrel head will bury into the rivet body and be held thereby after the rivet is set, as will become more apparent hereinafter.Further, the forces normal to the rivet body are less so that the rivet can be utilised with softer material without effecting the shape of the opening in the workpiece. Additionally, since there is less force normal to the rivet body, it is not necessary that the rivet body fit snugly in the opening in the workpiece, as is the case of the conventional rivet, to enable the rivet secondary head to be formed. Therefore, the rivet can be used in oversized holes, that is, holes larger in diameter than the diameter of the rivet body (see Figure 2).

As illustrated in Figure 2 as the mandrel 20 is pulled (while the flange 14 is being held in the conventional manner by the nosepiece of the tool, not shown), the rivet body 1 2 separates along the lines of the weakened areas 26 to form a plurality of wings or petals 32, 34, 36. The weakened areas 26 are circumferentially equally spaced about the rivet body 1 2 so that the axial pulling force of the mandrel head 24 will remain axial, and force each of the petals 32 and 36 out equally from the rivet body 1 2. Further, each of the petals 32 to 36 will deform at their medial area 38 so that the upper and lower deformed portions 40 and 42 will be equal in length.

As the mandrel is further pulled, the secondary head is formed. Because of the length of the rivet body in comparison to the thickness of the workpiece 44 and 46, the deformed portions 40, 42 will extend outwardly beyond the opening 48 in the workpiece even though the opening 48 is larger than the diameter of the rivet body (See Figures 2 and 3). Since the deformed portion 42 overlaps the deformed portion 40, additional rigidity is obtained in the contact of portion 40 with the workpiece. Further, since the weakened areas are circumferentially equally spaced about the rivet body, the axial force of the mandrel head will equally deform the petals 32 to 36. This arrangement enables the rivet of this invention to be used in soft materials without affecting the opening in the workpiece.

Attention is now directed to Figure 3 which illustrates the rivet with the secondary head 50 completely formed. As in a conventional rivet, as the secondary head becomes completely formed, the mandrel stem 22 will break from the head 24 leaving the head formed into the end 1 8 of the rivet body as illustrated in Figure 3. With the rivet body having a uniform cross-section throughout its length and the head 24 becoming surrounded by the deformed open end 16, the head 24 becomes partialiy encapsulated by the rivet body to retain the head 24 in the rivet.

It should be noted that the weakened areas leave the solid portions of the rivet body that form petals 32 to 36 in abutting relation when the rivet is in the free state. This lends structural integrity to the rivet body for handling and insertion of the mandrel during the assembly of the rivet and mandrel. Further, the petals 32 to 36 that form the secondary head have a maximum cross sectional dimension giving maximum surface area contact of the secondary head to the workpiece (See Figure 7).

Another novel feature of the large secondary head rivet of this invention is that the rivet is capable of fastening a wide range of thicknesses of workpieces together. As illustrated in Figure 6, the rivet can be secured to thin workpiece 52 in the same manner as described in connection with securing the workpieces 42 and 44. Because of the weakened areas 26 and their equal longitudinal spacing about the rivet body, the petals 32 to 36 will be equally formed against the workpiece as previously described.

Figure 5 illustrates a substantially thicker group 54 of workpieces being secured together by the novel rivet of this invention. The thickness of workpiece which can be secured together is the depth from the flange to the location longitudinally spaced from the ends of weakened areas 26 adjacent the end 1 8 of the rivet body 1 2. As illustrated in Figure 5, the head 24 of the mandrel will deform the end 18 of the rivet body and the weakened area 56 is exposed beyond the workpiece. In this fashion, the rivet can secure together workpieces of greater thickness lending additional flexibility to the adaptions to which the rivet can be put to use.

It can thus be seen that with a blind rivet having a rivet body with longitudinally equally spaced weakened areas on the rivet body, a larger bearing area of the secondary head can be obtained. Further, the rivet is particularly adaptable for use in soft workpieces and where oversized openings are present in the workpieces. Additionally, the novel rivet of this invention is capable of fastening a wide range of thicknesses of material.

Claims

1. A blind rivet of the type having a flange at one end and adapted to be deformed by the head of mandrel at the opposite end when the mandrel is pulled through the rivet comprising: a. an elongated rivet body carrying a flange on one end and being open at the opposite end; b. said rivet body having a plurality of longitudinally extending weakened areas between the flange and the open end; c. said weakened areas being circumferentially equally spaced about the rivet body and each terminating spaced from said flange and said open end; d. said rivet body having longitudinally extending solid portions between said weakened areas that have abutting line contact at said weakened areas; e. said weakened areas being adapted to separate when the rivet body is deformed to form from said solid portions a plurality of outwardly extending petals that form a secondary head on the rivet.

2. The blind rivet of claim 1 wherein said weakened areas are substantially through the sides of the body of the rivet.

3. The blind rivet of claim 1 wherein said outwardly extending petals equally extend circumferentially outward from the rivet body to form a secondary head.

4. The blind rivet of claim 3 wherein said petals are formed from said solid portions of the rivet body folded upon themselves which lends strength to the secondary head.

5. The blind rivet of claim 1 wherein said weakened area is spaced from said opposite end of the rivet a sufficient distance to enable the mandrel head to deform said opposite end of the rivet adjacent said weakened area.

6. A blind rivet substantially as hereinbefore described with reference to the accompanying drawings.