Note: Descriptions are shown in the official language in which they were submitted.
107~50
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1 BACKGROUND OF THE INVENTION
The present ;nvention relates to an indexing
cover for knock-out punches.
Knock-out punches of the type disclosed in U. S.
Patent No. 2,221,904 issued November 19, 1940 to J. H.
Abramson et al are in common usage. Such punches are fre-
quency used by electricians to form openings or enlarging
existing openings in circuit cabinets, panels, chassis or
junction boxes. When used for enlarging existing openings,
the knock-out punch cannot be easily centered in or aligned
with respect to the opening. Although some existing metal
punches include scribe marks on the cylindrical side wall
of the upper die member, such marks formed in the steel body
are not readily visible under ambient light conditions.
Also on construction sites, the electrician is
frequently confronted with relatively low, ambient light
conditions or areas of limited access making it even more
difficult to align a knock-out punch for proper location
of an aperture formed thereby.
' 20 SUMMARY OF THE INVENTION
~, It is the purpose of the present invention to
provide an index cover which readily fits over a die member
of a knock-out punch and provide indexing projections spaced
at predetermined intervals to provide readily visible
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2~ 25 indexing projections which also can be tactually located
,~ under very low light levels and areas of limited access.
These and other objects of the present invention,
its features and advantages will best be understood by
:. reference to the following description thereof in conjunction
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", 30 with the drawings in which:
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- ` 1076~S~
1 BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of the pTeferred
embodiment of the present invention;
Fig. 2 is a plan view in fragmentary form showing
the use of the present invention in conjuction with a
conventional knock-out punch; and
Fig. 3 is a fragmentary cross-sectional of the
apparatus taken along the sectional lines III-III of Fig. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the Figs. there is shown the
preferred embodiment of an indexing cover 10 of the present
invention. The cover includes a cylindrical body 12 having
an inwardly projecting circular lip 14 extending around
the top thereof. An aperture 15 is thus formed in the top
of the cover to permit normal operation of the knock-out
punch. The bottom of cover 10 is open such that it can be
positioned over the die 32 of a knock-out punch as seen in
Fig. 3.
Extending outwardly from the body 12 is a plurality
of projections 16, 18, 20 and 22 spaced at predetermined
intervals which are 90 in the preferred embodiment. These
projections extend radially outwardly from the axis of the
cylindrical body 12 and are integrally formed. Each of the
projections includesa narrow upper portion 12 and an enlarged
and pointed tip 17 at the lower end which is flush with the
bottom of the body.
r~i In the preferred embodiment the cover was manufac- -
tured by injection molding using a resilient polymeric
material such a polyvinyl chloride or other vinyl polymer
which can be brightly colored to provide a very visible
indexing cover easily utilized under relatively low ambient
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1076950
1 light conditions. The projections 16, 18, 20 and 22 with
their pointed tips 17 further provide mechanical projections
which can be utilized for aligning the cover when mounted
on a knock-out punch as described below by touch even where
the existing light level does not permit visual alignment.
In use, the cover 10 is positioned over the upper
die 32 of a knock-out punch having a central cavity 33 into
which a lower cutting die 34 can be projected. A bolt 36
passes through a plate 28 into which an aperture is to be
cut by the knock-out punch through an existing aperture 29.
The aperture 29 need not be of exact dimension corresponding
to the diameter of bolt 36 inasmuch as the indexing cover
of the present invention eliminates such a requirement.
. F~equently, in fact, the knock-out punch is used for enlarging
existing apertures in which case the bolt 36 is not useful
for providing the desired centering or the location of the
knock-out punch. Thus for example in the embodiment as
seen in Fig. 3, it is desired to enlarge an existing aperture
29 significantly off center to the left as seen in Fig. 3.
The bolt 36 includes a head 38 and is threaded
at the lower end to threadably fit within the cutting die 34
which is similarly threaded. Also a nut 40 is threaded to
the upper end of bolt 38 and fits within the central opening
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15 within the lip 14 of cover 10. In use, the nut 40 is
tightened forcing the bolt 38 upwardly until the cutting
; die 34 pierces the sheet metal plate 28 and cuts a new
aperture centered by means of the indexing cover. As best
seen in Fig. 2, cross hairs 31 and 33 can be scribed on
the plate 28 if desired, the projections 16, 18, 20 and 22
aligned therewith for providing the desired location of
the die regardless of the existence or position of a previous
1(~769~0
1 aperture.
It will be appreciated by those skilled in the
art that the indexing cover 10 is made in a complete set
of different sizes, one for each of the many standard -
knock-out punch dîes. Also it will be appreciated that
the indexing projections need not be spaced at 90 intervals
but can be placed at other relative angular positions
as desired for any given application. These and other
- modifications to the preferred embodiment of the invention
will, however, fall within the spirit and scope of the
present invention as defined by the appended claims.
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