Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having separate expander means – With hole forming means
Patent
1993-08-13
1996-06-04
Saether, Flemming
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having separate expander means
With hole forming means
408226, F16B 1304
Patent
active
055226868
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a self-drilling blind tension rivet which includes a rivet casing with a stop flange and a rivet spindle on one end of which a drilling unit is provided, and at other end region of which at least one rotation and tension force application element is provided to apply force by rotation and tensioning of a tool for drilling and setting the blind tension rivet.
Self-drilling blind rivets have already become known in various designs. For example, a self-drilling blind rivet is known from DE-A-2,554,557, where the rivet spindle or shank has over its entire length two parallel surfaces that extend along the spindle where the rivet casings or sleeves have surfaces complimentary to the surface of the spindle, in order to achieve a torsion-locked connection between the rivet spindle and the rivet casing. On the one hand, a special construction of the rivet casing is recruited, whereby the rivet spindle and the rivet casing must be precisely tailored to fit each other. On the other hand, immediately upon setting of the rivet, that is, upon application of tensioning movements, problems arise. When setting a tightened blind rivet relatively large forces, acting in the axial direction of the tensioning spindle, must be applied, so that a fixed clamping of the rivet spindle in an appropriate tool is necessary.
The same problems arise in a design of a self-drilling rivet disclosed in DE-A-2,548,860 where the rivet spindle has a quadratic cross-section. In this design as well, it is intended that a rotation-locked connection be established between the rivet spindle and the rivet casing, and thus here too, a special design of the open area cross section of the rivet casing will be needed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a self-drilling blind rivet which would ensure a simple installation of the end region of the tensioning spindle thereof in a tool and, on the other hand, it will enable the transfer of the tensioning forces when setting an optimal clamping action on the tool.
According to the invention, the tensioning shank or spindle of the rivet has at least one protrusion, or similarly designed force application section at its end region having the rotational and tensioning force application element that emanates from the free end and passes across at least a portion of the length of the free projecting region over the rivet sleeve, said protrusion running over the cross section of the section of the tensioning shank and parallel to the axis of the tensioning shank. The section for force application is provided over at least a part of its surface with roughening, transverse ribs, undulations, knobs, or a knurled edge.
In this manner the rivet shank can be pushed into the tool with no problems, since no back-cutting is necessary as for the other known designs. Due to the protrusions or similar elements protruding radially over the cross-section of the shank, a sufficiently good rotational engagement of the tensioning shank with the tool will occur during the drilling process. Precisely due to the formation of at least one partial section of the section for the force application with toughening, transverse ribs, undulations, knobs or a knurled edge, no particularly large radial clamping forces are needed for the rivet shank in order to transfer the relatively large axial forces when setting the tension blind rivet. Therefore, a simple pressing of the corresponding tool parts onto the section of the tensioning shank for the force application suffices to achieve a sufficient friction force due to the surface configuration of the corresponding partial section or a partial force-closed connection when setting the rivet.
Due to the special design of the tensioning section of the shank it will suffice, for example, to provide clamping jaws that are held spring-loaded in a conical portion of the tool.
One particularly simple design is obtained when the section for force application has two diametrically opposing protrusions, or
REFERENCES:
patent: 369248 (1887-08-01), Johnson
patent: 3935786 (1976-02-01), Murray
patent: 4245544 (1981-06-01), Freeman
patent: 4629380 (1986-12-01), Gunkel et al.
patent: 4920837 (1990-05-01), Phillips
patent: 5183357 (1993-02-01), Palm
patent: 5256017 (1993-10-01), Smirnov
Saether Flemming
SFS Rhomberg Gesellschaft m.b.H.
SFS Stadler Holding AG.
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