Improvements in the Manufacture of Metallic Covers for Electrical Switches, Cut-outs, and the like.
Year: 1898

page_text: Improvements in the Manufacture of Metallic Covers for Electrical
Switches, Cut-outs, and the like.
I, MARK LAWTON, trading as J. Lawton and Sons, of Harford Street, in the
City of Birmingham, Manufacturer, do hereby declare the nature of this invention
to be as follows:-
This invention relates to the manufacture or production of sheet metal covers
or shells, principally to be employed for enclosing the mechanism or parts of
electrical switches cut-outs, fuses and the like, and has for its principal object,
to produce such covers from thin sheet metal, but with parts of the same left
with thicker metal to admit of screw threading.
In carrying out one form of my invention in connection with the formation
of blanks to be subsequently fashioned into switch covers, I take a strip of
metal, of the same thickness as the thickest part of the article to be produced,
and I pass the same through a pair of rolls, one of which has a series of disc-
shaped sinkings formed around its periphery at separated points, whilst the
periphery of the other roll is plain, and is separated from the first-named by
a space equivalent to the thickness to which the outside parts of the metal strip
(surrounding the thickened parts) are to be rolled. These rolls thus transform
the strip into a sheet of metal, but with parts corresponding to the depth of the
sinkings left at the original thickness. The sheet is then cut up into blanks,
each having a thick middle and each blank is subsequently cupped up to form a
dome-shaped shell with a thickened or solid crown which is next pierced and
either the edges of the hole are themselves wormed or the thick metal surrounding
the piercing is turned downwards and then wormed.
As a modification, I may take a square blank of thick metal and operate upon
the same by drop stamping in such a manner that whilst the middle is left intact
or of its original thickness, the surrounding metal is laminated or spread out
and then subsequently fashioned by cupping up into the required dome or like
figure, whose walls are reeder or otherwise patterned as required. The thick
metal is cut out or pierced and screw threaded in like manner as described in the
first arrangement.
Instead of rolling or drop stamping, the metal surrounding the intact parts
may be spread out by hydraulic means, or the original blank may be thinner
than the thicker central part required to take the threading, but thicker than
the thinnest part. Then by the application of pressure to edge portions of the
blank, (the edges themselves being confined) the metal is made to flow inwards
and provide the increased thickness at the middle, which is then operated upon
hofare described

page_text: Instead of thickening the metal at the middle, I may leave the metal at the
edges of a blank intact to receive screw threads at the mouth or lips of the cover
when formed, the middle part in this case being thinned and cupped and either
pierced or not as required. Or an annular thickening may be left or formed at
any desired part of the blank, with the metal, both inwards and outwards of the
same, being thinned and subsequently fashioned or otherwise treated.
The application of my invention to the production of metallic covers for
electrical cut-outs, fuses and the like and also to other covers enclosing mechanism
for various purposes, differs in no essential particular from its application to
switch covers as herein described.
Dated this 20th day of Santambar 1808
Improvements in the Manufacture of Metallic Covers for Electrical
Switches, Cut-outs, and the like.
T, MARK LAWTON, trading as J. Lawton and Sons, of Harford Street, in the
City of Birmingham, 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 manufacture or production of sheet metal covers
or shells, principally to be employed for enclosing the mechanism or parts of
electrical switches, cut-outs, ceiling roses, fuses and the like, and has for its
principal object, to produce such covers from thinned metal blanks, parts of
which are thickened or left thick to admit of the same being screw-threaded, or
for strengthening the covers, or other purposes.
I will first describe my invention in connection with the production of a switchi
or like cover of the kind represented in cross section in Figure 1 and marked a,
Figure 2 being a view of the cover before the hole a¹, in the thickened part 2 of
the crown is serew threaded and Figure 3 a section of the same inverted and
before the hole, in the said thickened crown is drilled. In the production
of special blanks adapted to he subsequently fashioned by suitable tools into
such a cover as is represented in the said figures, I take a strip of metal such
as represented in plan in Figure 4 and edge view in Figure 5 and marked b, of
the same thickness as the thickest part of the article to be produced, and I pass
the same through a pair of rolls, one of which has a series of disc-shaped sink-
ings formed around its periphery at separate points, whilst the periphery of the
other roll is plain, and is separated from the first-named by a space equivalent
to the thickness to which the outside parts b¹, of the metal strip (surrounding
the thickened part 2) are to be rolled. These rolls thus transform the strip b
into the sheet of metal represented in plan in Figure 6 and edge view (partly
in sections in Figure 7, in which the parts b², corresponding to the depth of the
sinkings in the roll are left at the original thickness or nearly so. The sheet
is then cut up into blanks, (marked in Figure (i) each having a thick middle,
and these blanks are subsequently cupped up to form a dome-shaped shell with
a thickened or solid crown (see Figure 3) which is next pierced (see Figure 2)
and the edges of the hole wormed as in Figure 1.
Figure 8 represents a section of another form of switch cover in which the

page_text: edges a³, of the hole a, in the thickened crown a¹, are turned downwards or
inwards before being threaded, so as to make provision for a more extended
screwing.
This cover may be made from a circular disc of metal (shown in plan and
edge view in Figure 9) of a thickness throughout equal to the thickened crown a¹
to be produced, and the outer parts b', surround the centre 62, are thinned by
suitable tools, leaving the said middle part 2, intact or of the original thickness and
forming the blank represented in plan and cross section in Figure 10, the outer
and thinned parts of which are cupped to the desired domed figure whilst the
thick metal is pierced and the parts surrounding the piercing turned down pre-
paratory to screwing.
As a modification, I may produce blanks with thickened parts for the purpose
herein described by taking a square piece of thick metal and operating upon the
same by drop stamping in such a manner that whilst the middle is left intact
or of its original thickness, the surrounding metal is laminated or spread out
and then subsequently fashioned by cupping up into the required dome or like
figure, whose walls are reeded or otherwise patterned as required. The thick
metal is cut out or pierced and screw threaded in like manner as described in
the first arrangement.
Instead of giving the desired figure to the blanks by rolling or drop stamping,
the metal surrounding the parts to be left intact may be spread out by hydraulic
means, or the original blank may be thinner than the thicker central part re-
quired to take the threading, but thicker than the thinnest part. Then by the
application of pressure to edge portions of the blank, (the edges themselves
being confined) the metal is made to flow inwards and provide the increased
thickness at the middle, which is then operated upon as before described.
Instead of producing the blanks with the thicker metal at the middle, I may
leave the metal at the edges of a blank intact to receive screw threads at the
mouth or lips of a cover for cut-outs and the like, as is represented in section
in Figure 11.
A blank for this purpose is represented in plan and cross section in Figure 12,
the same being produced, as before, by stamping, rolling or otherwise from
strips or pieces of metal of a thickness equal to that which the edge parts 62 are
to have, the middle part in this case being thinned and cupped into the dome
figure represented in Figure 13, with the thickened part coming inside the
mouth, whilst the crown may be pierced or not, as required. In order to pre-
vent the mouth of the cover being reduced in diameter by the said thickened
edge and facilitate the cupping of the blank by ordinary press tools, the addi-
tional thickness may come upon the outside of the mouth as represented in
Figure 14, whilst when the cover requires to be screw-threaded at both the
mouth and at the piercing in the crown I may produce circular blanks having
thickened parts at both the middle and edges.
Or annular thickenings for any purpose may be left or formed at any desired
parts of the blanks, with the metal. both inwards and outwards of the same,
being thinned and subsequently fashioned or otherwise treated in any way as
may be desired.
The application of my invention to the production of metallic covers for elec-
trical cut-outs, fuses and the like and also to other covers enclosing mechanism
for various purposes, differs in no essential particular from its application to
switch covers as herein described.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
-
First In the manufacture of metallic covers for electrical switches, cut-outs
and the like making the said covers from metal blanks, parts of which are
thickened or left thick substantially as described and set forth.

page_text: Secondly: In the manufacture of metallic covers for electrical switches, cut-
outs and the like; the processes herein described of producing blanks having
thickened parts substantially as and for the purpose herein described and set
forth.
Dated this 10th day of June 1995.
MARK LAWTON.
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicant.