Note: Descriptions are shown in the official language in which they were submitted.
~zo~
The subject of the present invention is a
method of explosive welding on a definite segment,
which can find an application especially in the
production and repairs of shell-and-tube heat
exchangers.
The utilization of an explosive in the
processes of binding of metals is known and applied
in the world, for example, in the process of explosive
welding of tubes with tube plates of heat exchangers.
A broad review of the state of art in the
problem of explosive welding of metals has been
presented in an article by B. Crossland entitled:
"Review of the present state-of-the-art in explosive
welding" published in Metals Technology, January 1976.
Hitherto, from British Patents Nos. 1~572rll3~
1~280~451~ 1~521~256~ U. S. Patent No. A,117,966,
G.F.R. Patent No. 1~949~573 there is known a method
of explosive welding in the arrangement of a parallel
set-up of a tube or a plug in relation to the surface
of a hole in a tube plate.
From British Patents Nos~ 9 ~ 387
1~439~141~ 1~541~410~ G.~.R. Patent No. 1~949~573~
U.S. Paten~ No. 4~117~966 there is known a method of
explosive welding with the application of the angle
of initial obliquity of walls of a tube or a plug in
relation to a hole in a tube plate.
In both methods, in all known solutions,
the direction of the course of the detonation process
of an explosive is compatible with the direction of
3Q the course of welding a tube with a tube plate.
Basic disadvantages of the hitherto applied
solutions of the process of explosive welding of tubes
-- 2
with densely perforated tube plates, restricting a
broader application thereof are:
1) for the method of the parallel set-up of the
tube and the hole in the tube plate:
- a relatively large susceptibility of the
process to non-parallelism of the initial
set-up of the tube in relation to the hole
in the tube pla'e,
- the necessity of applying explosives having
a small detonation velocity within the limits
of 2,000 - 4,000 m/sec.,
- the difficulty in producing an explosive
having a small critical diameter ensuring
an appropriate value of the ratio of the
radial velocity of the tube to the deton-
ation velocity, that is the ratio ensuring
an appropriate value of the dynamic collision
angle,
2) for the method with the applicationof the initial
2~ inclination angle of walls of the tube in relation
to the surface of the hole in the tube plate:
- the necessity of labour-consuming connection
of wires of each detonator placed inside the
tube with the explosive network,
- a high cost of effecting one connection,
mainly due to a high cost of the detonator.
The method of explosive welding of materials,
according to the invention, ensures a relatively large
geometrical operating tolerance in the process, a low
unit material cost and unit labour-consumption of
effecting one connection, ana gives a possibility of
welding a tube with a tube plate, in one operation
and by means of one explosive charge, with a segment
greater than the thickness of the tube, with simul-
taneous expanding the tube along the remaining part
of the tube plate.
The method of explosive welding of materials,
according to the invention, consists in that an
explosive charge is placed on a plate to be welded
on and is detonated from the frontal side of the
said plate, ana that the appropriate explosive, the
shape and the dimensions of the gap between the base
plate and the plate to be welded on as well as the
shape of the inertial layer are selected so that at
the segment meant ~or welding the direction of
propagation of the detonation of the explosive and
the direction of propagation of the impact point or
welded materials have opposite senses.
The method according to the invention
ensures ease of the explosive welding operation, a
high yield thereof and a high quality of the bond.
~0 When conducting the process of explosive welding
according to the invention it is possible to use
explosives with very large detonation velocities
greater than S, ono m/sec. Particularl~ advantageous
results are achievea when using the method according
to the invention in the process of welding tubes
with small diameters in densely perforated tube
plates.
The process o~ explosive welding of
materials, according to the invention, is explained
in more detail in an example of its embodiment in the
drawing, in which:-
A
-- ~2C1 ~4~L
FIGURE 1 is a schematic diagram of the method;
FIGU~E 2 shows the assembly prepared for
use; and
FIGURE 3 shows the process of welding a
tube with a tube plate.
An explosive 3 is placed on an inertial
layer 5 and detonated in the direction of the axis
from the frontal side 6 of the base plate 2, driving
the plate 1 to be welded on in the direction of the
~ase plate 2 over the segment A the process of pressure
welding of materials occurs. The geometry of the
arrangement is such that at the segment A the deton-
ation velocity D of the explosive 3 and the projec-
tion Vk of the velocity ~k of the impact point k of
materials being welded have opposite directions.
At explosive welding of a tube with a tube
plate the explosive charge is placed co-axially in a
tube 1. The agent initiating the detonation is
placed from the frontal side of the tube plate 2.
Detonation is initiated by a detonator ~, at indivi-
dual firing or by a detonating fuse in the case of
group charges. The welded bond is obtained over a
segment A. The selection of an appropriate explosive
3, the shape of the charge casing, functioning at the
same time as an inertial layer 5, and providing an
angle ~ o~ a cone-shaped aperture tube plate 2 to be
larger than an angle c~ of dynamic welding ensure that
the explosive welding process progresses according
to the invention.
