Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1993-10-12
1996-09-24
Jones, David
Metal working
Method of mechanical manufacture
Assembling or joining
2924354, 72476, B21J 1502
Patent
active
055578357
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Introduction
This invention relates to a method of joining several metal sheets by using non-heat-treated rivets made from an aluminium alloy, if any provided with a rivet head, in which rivet punches--being used for forming the riveted head and, if any the rivet head--surround the shank end in question, whereas the two rivet-punches exert on the rivet shank such forces that one (riveted) head or, if any, two heads are formed, without the occurrence of cracks in the head, while at the same time sufficient widening out of the hole takes place. Such a method is known from an Article written by T. H. Speller & J. A. Randolph, which is a reprint from "Aircraft Engineering" (February 1972), issued by General-Electro Mechanical Corp., dealing with AD-rivets.
In the aircraft industry the use of fasteners, like bolts, rivets and blind rivets is wide-spread. These fasteners join parts (metal sheets) and transmit the forces exerted theron. The great majority of fasteners are machine-riveted or hand-riveted joints.
Rivets made from high strength aluminium alloys such as 2017, 2017A and 2024, have to undergo before being applied first a solution heat-treatment to obtain the required deformability. Thereafter they are quenched and stored in a freezing box or similar cold storage space.
This heat treatment has disadvantages, mainly in the field of logistics: additional handling and checking thereof, controlling of the durability of the rivets. That is, the rivets have to be riveted within a restricted time period after the solution heat-treatment. After elapse of said time period, the non-processed remainder of the batch of solution heat-treated rivets, taken from the freezing box at the beginning of said time period, have to go to scrap. This is because from that moment they are unfit for further processing, involving much loss of labour and material.
Reduction of the use of said solution heat-treated rivets would considerably improve the riveting process from a logistics point of view and substantially reduce the costs involved.
2. The Actual Riveting Method
A modern aircraft consists of several thousands of sheet metal components. These components are usually joined by means of rivets. Before a rivet can be installed, the sheets to be joined have to be positioned. Where a rivet is required, a hole is drilled and, if necessary, counter-sunk. After de-burring, the rivet is placed loosely into the hole.
During riveting the rivet is loaded in axial direction, depending on the riveting method, either by an intermittent or a continuous force (gun or press) such that the shank piece projecting through the sheet-stack is deformed. This is the so-called "riveted head" or upsetting. The diameter of the riveted head depends on the riveting force. The higher the riveting force, the greater the diameter of the riveted head.
The dimensions of the riveted head must comply with specifications from rivet and aircraft manufacturers. This means that
D must be between 1,25 d and 1,67 d and
H must be between 0,33 d and 0,67 d
The nominal sizes are D.sub.nom =1,5 d H.sub.nom =0,5 d
A large diameter of the riveted head improves the clamping-on of the sheet-stack. This is favourable for the life-time of the riveted joint. The extent to which the rivet-shank fills the hole, also depends on the riveting force. The higher the riveting force, the better the hole-filling. With sufficient riveting force even "widening out of the hole" may occur as consequence of shank (or slug) expansion of the rivet. Widening out of the hole extends the lifetime of a riveted joint considerably. Since the diameter of the riveted head is easily measurable at any time--as opposed to the riveting force--the diameter of the riveted head is seen as the quality defining parameter.
In the art of aircraft-construction the following alloys are mainly used:
______________________________________ deformability
alloy code shear-strength N/mm.sup.2
mild hard
______________________________________
2117 T3 AD 207 1,7-1,8d
2017 T31 D 234 1,8-1,9d
REFERENCES:
patent: 3426641 (1969-02-01), Rosman
patent: 3561102 (1971-02-01), Diemer
patent: 3908257 (1975-09-01), Briles
patent: 3952401 (1976-04-01), Wagner
patent: 4630463 (1986-12-01), Knowlton
patent: 4864713 (1989-09-01), Roberts et al.
patent: 5060362 (1991-10-01), Birke et al.
P. G. Reinhall et al. "An Analysis of Rivet Die Design in Electromagnetic Riveting", Journal of Vibration, Acoustics, Stress, and Reliability in Design, pp. 65-69, vol. 110, Seattle, Washington, Jan. 1988.
LandOfFree
Method, Rivet-Punch, for joining several metal sheets by using n does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method, Rivet-Punch, for joining several metal sheets by using n, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method, Rivet-Punch, for joining several metal sheets by using n will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1920772