JPS6024979Y2 - Pull-out blind rivet assembly - Google Patents

Description

[Detailed description of the invention] The present invention relates to a blind rivet assembly comprising a hollow rivet and a mandrel and assembled by inserting the mandrel into the hollow rivet, and in particular, the lower surface of the mandrel head has a ridge extending in the radial direction. When the mandrel head is pulled when the rivet is rivet-shaped and crimped, the ridge splits the end of the rivet into petal-like shapes.
This invention relates to a blind rivet assembly for tightening and fixing plates, etc.

There are two types of split-tight blind rivets: those in which a vertical line of weakness is attached to the rivet body so that it splits into petals when the head of the mandrel is pulled;
Some such lines of weakness are not attached to the bed body, but are divided by ridges arranged radially on the underside of the mandrel head.

In the latter case, the ridge is usually in the form of a three-, four-, or five-sided pyramidal rim, with the pyramidal shape extending from the warm edge of the mandrel to the mandrel cylinder.

Manufacturing the latter type of rivet is economical because the process is less complex than the former type of rivet, which requires a line of weakness along the rivet body.

However, due to the effect of the ridge on the lower surface of the mandrel head, the rivet body is evenly divided into a predetermined number of petals (for example, if the lower surface of the mandrel head is part of a square pyramid, four
However, experience has shown that to ensure this effect the rivet body must have a uniform thickness within very tight manufacturing tolerances.

The shape of the above mandrel head will be explained with reference to FIGS. 5 to 7.

The lower surface of the head H of the mandrel M is shaped like a pyramid, that is, a square pyramid, and ridges R are formed at the corners.

This ridge R is directly connected from the mandrel head to the mandrel shaft S, and forms a sharp knife.

The split type blind rivet assembly has a hollow rivet inserted into this mandrel, and by pulling the mandrel, the hollow rivet ridge is divided into petal-like parts, but it is weak if the rivet body wall is not uniform. There was a tendency for the wall portion to be cut first, causing the center of the mandrel to shift due to the cutting, and for further cutting that portion to a large extent.

Also, even if the inner diameter of the rivet is slightly off-center with respect to the outer diameter, the body of the rivet will not follow the four lines and will
Sometimes it was divided along book lines, or along just one line.

It has been found that maintaining the tight tolerances required on the rivets to ensure uniform separation can be costly.

The purpose of this invention is to divide the rivet body into even and uniform petal-like sections by means of the ridge on the underside of the mandrel head, thus allowing the rivet to be produced in divided fastening without the need for extremely tight manufacturing tolerances. An object of the present invention is to provide a pull-out type blind rivet assembly.

To distantly relate to this purpose, the divided fastening type pull-out blind rivet assembly according to the present invention is such that the lower surface of the mandrel head is connected to the cylindrical part of the mandrel part in a plane perpendicular to the axis of the mandrel part. In addition, the mandrel head forms a flat shoulder with respect to the mandrel shaft at least at the corner of the pyramidal surface where the ridge is formed.

In other words, the knife edge of the ridge on the lower surface of the mandrel head according to the present invention does not directly contact the end of the hollow rivet, but the flat shoulder is in contact with the rivet end. .

It has been found that when the rivet according to the present invention is used, even when the inner diameter of the rivet body is eccentric with respect to the outer diameter of the rivet body, the rivet body can be reliably and uniformly divided into petal-shaped segments.

This is because when the mandrel is pulled, the ridges press (i.e., are seated) with uniform force against the rivet end before splitting the rivet body, and the subsequent strong pull forces the rivet end to It is believed that each ridge will apply a uniform cutting force to the rivet end when the ridges meet the ridges over the shoulder.

Therefore, the rivet of the blind rivet assembly according to the present invention can have wider manufacturing tolerances than conventional rivets, thereby reducing the manufacturing cost of the rivet.

Hereinafter, an embodiment of a pull-out type blind rivet assembly according to the present invention will be described with reference to FIGS. 1 to 4.

The rivet assembly includes a hollow aluminum alloy rivet 10 having a flange 12 and a uniform wall thickness body 14 without longitudinal lines of weakness.

Additionally, the rivet assembly includes a steel mandrel 16 consisting of a cylindrical shank 18 and a head 22 having a neck 20 that breaks during the rivet tightening process.

The head 22 has a substantially square shape with a rounded peripheral edge 24 and a lower surface 26 shaped like a pyramid and in contact with the peripheral edge 24.

The angle formed by both sides of the pyramidal lower surface 26 of the mandrel head is 80°.
It is.

The difference between the “diagonal” and the minimum “diameter” of the head is approximately 0.26
mm (i.e. 5.5% of the nominal head diameter of 4.70 mm)
).

Each corner of the peripheral edge 24 coincides with a corner of the pyramidal lower surface 26.

The pyramidal lower surface 26 is a plane perpendicular to the axis of the shaft portion 18 and
8, and a flat shoulder 28 perpendicular to the shaft 28 is formed at the corner where the ridge of the pyramidal surface is formed.

At the surface where the mandrel head meets the shank, the diameter of the shank may be equal to or less than the distance between the flats of the pyramidal lower surface 26.

The aforementioned shoulders 28 are therefore either confined to the corners of the mandrel head or run all the way around the shaft.

If this blind rivet assembly is used to join two plates p, p' (FIG. 4), the body 14 of the rivet will fit into the mandrel head without using extremely tight tolerances during rivet manufacturing. The flower petals 30 were evenly and reliably divided into four petals 30 by the lower surface 26 of the flower and curved as shown in FIG.

This is because when the mandrel 16 is pulled, each shoulder 28 presses the end of the rivet body 14 and shapes the end face to some extent, gradually making the pressing force of each shoulder 28 uniform, and then It is believed that this is because each corner (ridge) applies a uniform cutting force (splitting force) to the rivet end when the rivet crosses over its shoulder 28 and contacts the corner (ridge).

[Brief explanation of the drawing]

Figure 1 is a partially sectional front view of the blind rivet assembly, Figure 2 is a view of the head of the mandrel in Figure 1 as seen from a direction rotated 45 degrees from the position in Figure 1, and Figure 3 is the view in Figure 2. Figure 4 is a perspective view showing the rivet assembly after tightening;
Figures 5 to 7 show the mandrel of a conventional split tightening pull-out type blind rivet assembly, with Figure 5 being a front view of the mandrel head, and Figure 6 being a 45° angle from the position shown in Figure 5. FIG. 7 is a view of the mandrel head seen from the direction of rotation, and is a sectional view taken along the line ■--■ in FIG. 6. The symbols of the main parts in the figure are as follows. 10...Hollow rivet, 12...Rivet flange, 14...Rivet body, 16...
...Mandrel, 1 end...Cylindrical shaft part, 20...
...Neck, 22...Head, 24...
Periphery, 26... pyramidal lower surface, 28... curved flat shoulder.

Claims (1)

[Scope of utility model registration request] It has a hollow rivet 10 and a mandrel 16, the lower surface 26 of the mandrel head being shaped like a pyramid with a radially extending ridge so that when the mandrel head is pulled during crimping of the rivet, said ridge is formed. In a pull-out blind rivet assembly in which the rivet end is petal-shaped, the lower surface 26 of the mandrel head is connected to the shank cylinder in a plane perpendicular to the axis of the mandrel head 28. A pull-out blind rivet assembly characterized in that the mandrel head forms a flat shoulder relative to the mandrel shaft at least at the ridge-formed corners of the pyramidal surface.