Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1996-01-11
1998-10-06
Hughes, S. Thomas
Metal working
Method of mechanical manufacture
Assembling or joining
29 34B, 29243517, 2924353, 411 30, 411 38, 411 69, B23P 1100, F16B 1910
Patent
active
058159061
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns a self-cutting blind rivet/expansion rivet, a method for blind riveting/expansion and an apparatus for performing the method, together with a function for expansion by a combination of these within the same process by means of the tool's replaceable nose.
BACKGROUND OF THE INVENTION
Blind riveting is a known method for joining plates, or for securing plates to a framework.
As a rule, known blind riveting systems consist of a sealed or open rivet with draw nails. The rivet is inserted into a pre-drilled hole in the elements which have to be joined together. The drawing tool is placed over the projecting draw nail and the tool is activated. This can either be performed manually with conventional blind rivet tongs (so-called PO rivet tongs), "accordion" tongs or a pneumatically or hydraulically operated drawing tool. The tool usually consists of three grip jaws. When the tool is pulled/activated, the jaws grip around the draw nail and pull it while at the same time the tool's mouthpiece rests against the rivet head. The draw nail's head, which is secured in the bottom of the rivet, will now cause the rivet to expand/form a flange which is pulled against the inside of the rivet connection. When this is achieved, the elements are clamped together until the draw nail breaks. The draw nail is adapted to break when a favorable pressure is attained for the rivet connection and this is achieved here by the fact that the draw nail can be made of different types of metal or alloys such as, e.g., aluminum, monel and stainless steel. The strength of the rivet connection is determined solely by the breaking strength of rivet and nails.
There are also other known systems for combined connections such as, e.g., screw rivets which both connect the elements and form screw fastenings. These rivets are without draw nails and have instead a threaded section in the bottom. Instead of "jaws" the drawing tool has a hardened screw in "the nose". The rivet is screwed on to this and inserted into the hole in the elements which have to be joined together. The tool is activated and drawing continues until a satisfactory force has been achieved. A rivet connection has now been obtained with a screw fastening. In this type of connection, as a rule the actual screw fastening is the primary factor, since this method takes more time than the blind riveting which is described above.
Both of these rivet types, however, are characterized by the fact that a rivet connection can be achieved without a rivet holder at the back, thus providing significant advantages in those cases where the back of the elements is not accessible.
As described above, blind riveting is dependent on an extra nail (draw nail) which can be considered unnecessary material consumption and which can be left in the rivet leading to spots of corrosion. The "threaded rivets" are very time-consuming to use, and both rivet types are dependent on a separate drilling process, even though blind rivets are known in the patent literature with a self-cutting drilling tip.
In Norwegian patent application 91 2193 there is disclosed a blind rivet which comprises a head with an engagement body for co-operation with a complementarily shaped screw nose on a mounting tool, a self-drilling tip at the outer end of the rivet and an axial hole which over at least part of its length is provided with threads, and where the self-drilling tip forms an integral part of the blind rivet. From the same application there is also disclosed a device for mounting blind rivets, where the device comprises a housing with a drawing system. The drawing system includes a piston and a drawing rod which extends along the entire length of the device and in the front end of the drawing rod there is removably attached a draw pin with an outer part, a detachable rivet holder and a screw nose connected to a motor and a magnet.
By means of this known rivet a screw fastening is obtained for the draw pin and the disadvantages associated with rivets having draw nail
REFERENCES:
patent: 4678384 (1987-07-01), Sparling et al.
patent: 4920833 (1990-05-01), Rosenthal
patent: 5051048 (1991-09-01), Maddox
patent: 5183357 (1993-02-01), Palm
patent: 5259713 (1993-11-01), Renner et al.
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