Metal fusion bonding – Process – Using explosive energy
Patent
1983-09-07
1985-12-31
Ramsey, Kenneth J.
Metal fusion bonding
Process
Using explosive energy
228 25, B23K 2008
Patent
active
045615853
DESCRIPTION:
BRIEF SUMMARY
Metal elements such as sheet-metal and tubes can be spliced by various known methods of explosion-welding.
FIG. 1 shows schematically some such arrangements.
The explosive charge 1 accelerates either a splice plate 2 towards the elements 3 and 4 to be joined, or a part of one of the elements.
Since a relative large explosive charge must be used in relation to the thickness of the elements or the splicing strip, in order to achieve satisfactory cohesion, the splicing method according to FIG. 1 causes considerable deformation of the elements even if they are supported during the procedure.
In the arrangements shown in a and b where an explosive charge with low detonation speed must be used, the overlap must be made wider than is necessary for the strength of the joint. This is because the pressure relief from the edges of the charge affects the welding process in long, narrow charges so that with decreasing width, only edge effects are finally obtained. Even if the width is increased unjoined edge zones are obtained, see FIG. 2. In some cases such unjoined edge zones may give rise to gap corrosion.
In cases c and d in FIG. 1, a more rapid explosive charge can be used due to the angular arrangement, and a narrower overlap is obtained with satisfactory cohesion. However, these arrangements require great accuracy in preparing the joint and the elements must be fixed together in the correct position so that the angle set is correct along the entire joint. This entails practical difficulty in the case of long joins.
The object of the present invention is to eliminate these difficulties.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows various known methods of explosive welding.
FIG. 2 illustrates the explosive weld obtained in some of the prior methods.
FIG. 3 shows one embodiment of the invention in which a cylindrical charged is enclosed within a cylindrical inert medium.
FIGS. 4 and 5, show various arrangements of the driver plate.
FIG. 6 shows an embodiment of the invention in which simultaneous explosive welding is effected on both sides of the work.
FIG. 7 shows the use of an explosive bonding charge of non-circular cross-section.
The explosive charge is given the simplest and most ideal shape, i.e. cylindrical, and is entirely encased in an inert medium so that the pressure relief and spread of fumes will be delayed until the explosion-welding process is complete.
The overlapping splicing material is also cylindrical so that even if the elements to be joined are somewhat irregular or placed slightly incorrectly, a region will always be obtained where the collision angle is correct for satisfactory adhesion. The relief of the pressure which still occurs with increasing distance from the centre of the charge through the inert medium is compensated by the increase in the angle set, due to the cylindrical shape. The arrangement is shown in FIG. 3.
In the cross-section shown 1 is the charge, 2 the splicing material, 3 and 4 the elements to be joined and 5 the inert material surrounding the charge 1.
In FIG. 3 the splicing material has greater inner than outer radius. However, this is by no means necessary in principle, but facilitates adhesion of the edges and improves the appearance of the join (FIG. 3b).
The shock wave through the inert medium 5 has even further to go due to the eccentric location of the charge in relation to the surface of the splicing material and their different curvatures. Together with the curvature of the splicing material in relation to the metal elements, this determines the speed, both at right angles and parallel to the surface of the elements, at which the collision takes place. The explosion-welding process is thus not directly dependent on the detonation speed of the explosive, but on the detonation pressure, the material properties of the inert medium transmitting the shock wave, the splicing material and the geometry.
Explosives can thus be selected which have favourable properties with respect to slight critical diameter, manufacture, sensitivity, etc.
As for the inert materi
REFERENCES:
patent: 3024526 (1962-03-01), Philipchuk et al.
patent: 3036374 (1962-05-01), Williams
patent: 3455017 (1969-07-01), Zondag
patent: 3797098 (1974-03-01), Bement
patent: 3863327 (1965-02-01), Legate et al.
Nitro Nobel A.B.
Ramsey Kenneth J.
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