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Патент USA US2412175

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?es, 3, 194-60
FiledOc’c. 26, 1943
~Edmund T. Ridgumy
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P v ‘M
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Patented Dec. 3, 1946
Edmund T. Ridgway, Oaklyn, N. 1., assignor to
The Budd Company, Philadelphia, Pa., a cor
poration of Pennsylvania
Application October 26, 1943, Serial No. 507,659
2 Claims.
(01. 219—10)
The invention relates to electric spot welding,
and more particularly to spot welds with in
creased iatigue resistance at the weld location
and its surroundings.
The invention is concerned with the stresses
concentrated at and around spot welds, especially
shaped and used so as to achieve the proper
amount of compression. Helpful in obtaining the
desired compression is the offset arrangement of
the center of the middle line it of the grooves
ill slightly outside of the middle line M of
the ridges 9, l l, as shown in Figure 2.
The rings or beads help, furthermore, in achiev
in highly stressed structures which have been a
ing the desired object by leading the stresses
serious problem. These stresses are due to the
away from the rough edge iii of the weld nugget
expansion of the material of the weld nugget
during the welding operation and the later con 10 l2 and, as indicated by the arrows it, over the
grooves. This avoids concentration of stresses at
traction thereof after its solidi?cation. It was
the meeting faces and on the irregular edge of
found that, due to these stresses and probably
the weld nugget l2 where a notch effect occurs
due to the irregular shape of the weld nugget in
through irregular fusion or splashing of the weld.
the zone where the members to be united meet,
A further bene?cial influence of said rings is
?ssures or cracks occur which start at the weld 15
due to the fact that they produce a dead end
and which extend gradually into the surround
or retardant if a crack or ?ssure should start at
ing material until the structure is weakened to
the weld.
such an extent that repair or replacement be
Finally, the rings or beads stiffen the area
comes necessary.
around the weld and reduce bending of the in
The outstanding object of the invention is the
side portion l'l comprising the weld nugget so
overcoming of these serious defects.
that the weld nugget is relieved from stress con
The object of the invention is mainly achieved
by providing a ring-shaped bead, groove or ridge
The outside ridge or ridges 5?, ll may per
in the metal part or parts around the spots
to be welded. Applicant’s explanations of the 25 form an additional function, namely that of facil
itating the matching of parts and the location
functions of this head or the like will be given
later on after having described the embodiment
illustrated in the attached drawing.
In the drawing:
of the welds. When two pieces are to be con
nected and the rings or beads indicating the weld
pattern have been made in advance, the smooth
Figure 1 is a fragmentary view of two metal 30
._ sides may match and the projecting beads on
the rough side will serve as a locating means
sheets with two weld connections according to the
when welding.
The invention is, of course, liable to many modi
Figure 2 is a section through the center of
?cations which will occur to those skilled in the
one weld along line 2—2 of Figure 1.
The drawing shows two sheet metal parts 5, 35 art, and which are intended to be covered by
the attached claims.
6 which overlap each other. The .dot-and-dash
What is claimed is:
line 1 indicates the axis of the weld to be de
1. Method of making a spot weld connection,
scribed in the following.
comprising the step of forming an enclosing bead
Sheet 5 is formed with an annular groove 8
on one side and an annular ridge 3 on the other 40 in at least one of the members to be united
and in simultaneously compressing the material
side, both concentrically about the axis ‘l of
surrounded by said head, and the further step
each weld. Groove 8 and ridge 9 are formed
of producing a weld in the central portion only
with correspondingly shaped dies. Similar groove
of the region surrounded by the head in such a
l9 and ridge l l are formed on sheet 6. The weld
nugget I2 is formed in substantially conven 45 manner that compressive forces in the material
around said weld are substantially neutralized.
tional manner and by substantially conventional
2. Method of making a spot weld connection
means in the space surrounded by said grooves
invention; and
and ridges 8, Ill and 9, II.
between parts, comprising the steps of forcing
the material of at least one of the parts radially
sheet and marked by said grooves 8, l8 and 50 and inwardly toward a central weld area to
form a section under compression and welding a
ridges 9, ll produce a small amount of initial
nugget in substantially the central portion of said
compression in the circle in which the weld
compression section only whereby the compres
nugget is formed and this compression counter
sive forces in the compressed section of the ma
acts the shrinkage in the weld nugget which, as
terial external to the weld are neutralized.
explained hereinbefore, is believed to be the main
cause for the start of fatigue failure. The
dies forming the rings should, therefore, be
The rings raised above the one surface of each
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