Year: 1897

page_text: Date of Application, 16th Mar., 1897-Accected, 15th May, 1897
1, FRANK ASHLEY WILMOT, of Bridgeport, Connecticut, United States of
America, Manufacturer, do hereby declare the nature of this invention, and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement:-
This invention relates to the method of uniting sheet metal edges, and to the
articles of manufacture produced by such method, and has particular reference to
the production of metal tubing which may be made of clock spring steel, although
the method may be employed in connection with the production of other articles
than tubes, and from other metal than steel.
The object of my invention is to produce a joint in which interlocking projections.
and recesses are so brought together under edgewise compression as to cause parts
or molecules of the metal to change their relative positions laterally and thus
become immovably interlocked without appreciably changing the thickness of the
sheet metal at the seam or joint.
With these ends in view I have invented the novel method and the product.
thereof which I will now proceed to describe and then point out in the claims.
In the accompanying drawings:
Figs. 1 and 7 represent completed tubes produced according to my method.
Fig. 2 represents the tube having its edges formed with alternate projections
and recesses and adapted to be brought together and compressed edgewise to form
the completed tube shown in Fig. 1.
Fig. 3 represents two flat strips of metal having their edges united according to
my invention, the particular shape of the interlocking projections and recesses
being similar to the illustration in Fig. 1.
Figs. 4, 5, 6, 8, 9, 10, 11, and 12 are views similar to Fig. 2 but illustrating
different shapes which the edges may have prior to the final edgewise interlocking
and compression, and
Fig. 13 is a view corresponding with Figs. 1 and 7 except that the edges of the
tube have not been brazed and openings are shown not only at the meeting points
of the depressions and projections but at the sides thereof.
Similar reference characters are employed to designate similar parts throughout
the several views.
Referring first to Fig. 2, A designates a blank adapted to be formed into a tube
the edges of which blank are provided with alternate projections a and recesses b
which may be termed the main projections and recesses, these being sub-divided as
by a smaller projection or lug 1 at the center of each recess b, and by a smaller
recess or notch 2 at the center of each projection a.
For convenience in describing my invention, I hereinafter mainly use such terms
as above; but of course another way to describe the shape of the edges of the
blanks would be to refer to the parts 1 and the small parts on each side of a
notch 2 as projections, and to apply the term recesses to the spaces or notches 2
and the spaces each side of a part 1. I prefer however, to distinguish the main
projections a and main recesses b from the smaller ones which sub-divide them, for
the reason that in the forms which I have here chosen to illustrate my invention
the main projections and recesses are substantially rectangular in outline while the
smaller or intermediate ones (termed lugs and notches) have portions which are
more or less curved or inclined.
:

page_text: To permanently unite the two edges of the blank shown in Fig. 2 the said edges.
are closed together about a mandrel, or drawn through a die, or passed through
rolls with or without a mandrel to cause the projections to pass directly into the
recesses as the edges are brought together, and in this direction of movement a
circumferential or edgewise compression is given to the blank so as to cause the
side walls of the lugs 1 to laterally displace the portions of the projections a which
lie each side of the notches 2, thus causing some of the molecules of metal forming
the projections to change their relative positions to some extent, the projeccions
finally becoming clinched together as indicated in Fig. 1, without appreciable
alteration in thickness.
Owing to the sides of the lugs 1 being inclined in opposite directions, the forcing
of the parts together causes the two prongs of the projections a to move laterally
in alternate opposite directions, the shapes of the recesses adjacent to said prongs
on both. pieces or edges of metal being correspondingly altered.
I may employ a small amount of solder at places or throughout the length of
the irregular line of the joint, but I do not limit myself thereto.
In the case of uniting the edges of two flat strips or sheets of metal as
indicated in Fig. 3, the procedure is the same as above described except that
here there would be ΠΟ circumferential compression-merely an edgewise
compression.
As indicated in Fig. 4, the lugs 1 and notches 2 may be omitted from some of
the main recesses and projections, and as indicated in Fig. 5, the lugs 1 may be of
greater length than the two prongs of the projections a, and the notches 2 may
be of greater depth than the recesses b. Or as shown in Fig. 6, the lugs and
notches may be respectively of less length and depth than the main projections
and recesses.
b
In Figs. 7 and 8 I have illustrated a form in which the lugs 1 at the bases of
the recesses and notches 2 in the projections are made angular, the sides of
notches 2 lying at a more acute angle to the line of the joint than the sides
of lugs 1. If preferred the lugs 1 and notches 2 may be omitted from some of
the recesses and projections, in this form also as I have indicated in the drawing.
In Fig. 9 I have illustrated a form in which lugs 1 at the bases of the recesses b
are omitted, the notches 2 in the projections being angular as in Figs. 7 and 8.
In Fig. 10 i have illustrated a form in which notches 2 in the projections a are
omitted, the lugs 1 at the bases of recesses 6 being angular as in Figs. 7 and 8.
In Fig. 11 I have illustrated a form corresponding with Fig. 9 except that the
notches 2 in the projections are curved instead of angular as in Fig. 9. In Fig. 12
I have illustrated a form corresponding with Fig. 10 except that the lugs 1 at the
bases of recesses 6 are curved instead of angular as in Fig. 10. The form
illustrated in Fig. 13 differs from that in Figs. 7 and 8 only in that the recesses and
projections are so shaped as to leave openings 4 at the sides and ends of the
depressions and recesses. It will of course be understood that the joint may or
may not be brazed or soldered from the inside or the outside in places or throughout
the length of the irregular line of the joint. In practice V shaped openings may be
formed in the inner side of the joint by beveling off the ends of the projections
or the bases of the recesses or both on the side of the blank which is to be the
inner side of the tube. These ✓ shaped openings serve as funnels to receive
solder from the inner side, but owing to the fact that the outer surfaces of the
edges must first come in contact, when the final compression is given to the tube, a
joint is formed so close upon the outer side as to be almost invisible.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is:
1. The method of uniting two edges of sheet metal which consists in forming
said edges with interlocking projections and recesses, some of the projections

page_text: having sides which are inclined in opposite directions, and then forcing the pro-
jections and recesses together edgewise and thereby displacing portions of the
metal laterally and in opposite directions to alter the shape of the said projections
and recesses, whereby the parts will be firmly clinched together.
2. The method of making sheet metal tubing which consists in first forming the
edges of the blank with interlocking projections and recesses, some of the pro-
jections of one edge differing in outline from the opposite recesses of the other
edge, and then forcing the projections and recesses together edgewise and thereby
laterally displacing portions of the metal to alter the shape of the said projections.
and recesses, whereby the parts will be firmly clinched together.
3. A tube formed from a blank of sheet metal having upon its edges a continuous
series of interlocking projections and recesses, portions of which have oppositely
inclined sides to form cam surfaces so that, when a circumferential compression is
given to the blank, metal is displaced in opposite directions and locks the said.
edges against separation.
4. A tube formed from a blank of sheet metal having its edges provided with
interlocking projections and recesses, the ends of some of said projections or
recesses differing in outline from the ends of the corresponding parts so that, when
the blank is compressed' circumferentially, metal is displaced sidewise and clinches
the edges firmly together.
5. A tube formed from a blank of sheet metal having upon its edges inter--
locking alternate projections a and recesses, sub-divided by the notches 2 in the
projections a and the cam-shaped lugs 1, the recesses b, the said lugs 1 being
wider than the notches 2, whereby, when the blank is compressed circumferentially,.
the portions of the metal each side of the notches 2 are displaced sidewise and
interlocked.
Dated this 10th day of Fahrry 1897