Note: Descriptions are shown in the official language in which they were submitted.
1 ~his invention is concerned with the manufacture
of rotatable ignition files or f:Lint wheels, for e~ample
for lightexs.
In accordance with -the present invention, I pro-
vide a method of manufacturiny rotatable ignition filesor flint wheels, for example for lighters, comprising
the steps of: cutting elongate wire stock of gauge appro-
priate to the desired diameter of the wheel into blanks of
suitable size; and applying a series of press operations
to the blanks by means of respecti~e punches and dies to
champfer or round off the peripheral edges of the blanks,
to provide axial mounting holes, and to harden the
respective surfaces of the blanks; and the circumferential
surfaces of the respective blanks being formed as friction
surfaces.
Preferably the series of press operations com-
prise the following steps in order: guiding the cut blank
into a die hole and applying pressure thereto by a pair of
opposed punches to initially shape the blank; champfering
or rounding off the peripheral edge of the blank at one
axial end surface thereof by charging the shaped blank
into a second die hole having a bottom formed with a
rounded peripheral edge and applying pressure to the blank
by means of a co-operating punch; thereafter champfering
or rounding off the peripheral edge of the blank at its
other axial surface and simultaneously providing a central
recess in each axial end surface of the blank by inverting
the blank and charging it into a die hole having a bottom
- 1 - J~
1 wi-th a rounded peripheral edge and a small diameter
guide channel for a small dia~e-ter punch opening in the
centre of the said bottom, and applying pressure to the
inverted blank in the bo-ttom of the said die hole between
a co-operating punch formed with a forward end protrusion
on its axial centre line and the said small diameter
punch; and thereafter forming a through aperture along
the axial centre line of -the blank by means of a punch
die.
It should be appreciated that the above sequence
of steps is merely -that which we prefer and alternative
steps are feasible, as are additional steps, as desired.
The invention is hereina~ter more particularly
described by way of example only with reference to the
accompanying drawings, in which:-
Fig. 1 is a perspective view of a raw cut
blank;
Fig. 2 is a sectional view illustrating the
step of initially shaping the blank;
Fig. 3 is a sectional view through the initially
shaped blank;
Fig. 4 is a sectional view illustrating a
subsequent stage of champfering or rounding off one
peripheral edge of the blank;
Fig. 5 shows the blank in sec-tion after appli-
cation of the step illustrated in Fig. 4;
Fig. 6 illustrates a subsequent step of
champfering or rounding off the other peripheral edge
-- 2 --
surEace and ~orming recesses in -the opposite axial faces
of the blank;
Fig. 7 shows the blank a-t the end of -the operation
illustrated in Fig. 6;
Fig. 8 illustra-tes a yet subsequent stage in which
an axial hole is punched through the blank;
Fig. 9 shows in section the blank at the end of
the operation illustrated in Fig. 8;
Fig. 10 shows two alternative embodiments of blank
at the end of the operation illustrated in Fig. 8, the
blanks being shown in section taken along the line A-A
in Fig. 9;
Fig. 11 shows a perspective view of the finished
rotatable ignition file or flint wheel; and
Fig. 12 shows the wheel of Fiy. 11 in section.
Elongate wire stock ~such as iron wire~ of gauge
appropriate to the desired diameter of the finished wheel
is first cut into blanks 1 of suitable size. The blank 1
is charged into hole 4a of a die 3a having a pair of
co-operating punches 2a,2a for applying pressure to the
blank 1 to give it an initial shape suitable for
subsequent working. As will be seen from Fig. 3, the
initial shape has respective recesses la in each axial
end surface.
The thus initially shaped blank is charged into a
second die having a die hole 4_, and pressure is applied
to the blank by means of a co-operating punch 2_. The
bottom surface 4b' has a champfered or rounded peripheral
-- 3 --
1 edge so -that after -the opera-tion illustrated in Fig. 4 when
-the blanl~ 1 is pushed out oE -the die by means of a pin 5,
it has -the configuration shown in Fig. 5, from which
figure it will be seen that -the blank has a rounded or
champfered peripheral edge lb.
The blank is then inverted and charged into the die
hole 4c of a further die also formed with a champfered or
rounded peripheral edge to its bottom surface 4c'. In
this case, an aperture of relatively small diameter in
which is received a punch 2c' of relatively small
diameter opens into the centre of bottom surface 4c'. The
punch 2c also has an axial protrusion in its end surface.
Pressure is applied to the blank 1 in the bottom of the
die hole 4c between the main punch 2c and the small
diameter punch 2c' so that the second axial end surface of
the blank is formed with a champfered or rounded periphery
at lb' and respective recesses lc are formed in the centre
of the respective axial end surfaces (Fig. 7).
The blank 1 is next charged into the die hole 4d
of a conventional punch die 3d and a round, or alternatively
square, cross-sectioned hole ld is punched through the
blank at the position of the recesses lc by means of
co-operating hole making punches 2d,2d.
The blank 1 may then be quenched and a friction
surface is formed at the periphery of the wheel, for
example by forming file cuts le, to complete formation of
the wheel.
1 ~s will be apprecia-ted from the foregoing
description, the series oE co-operating punches and dies
2a,3a, 2b,3b; 2c,3c; and 2d,3d may be operated by
relatively unskilled personnel. The presently described
method avoids -the need for skilled cutting of blanks,
avoids the need for skilled cutting of the peripheral
edges of the blanks by means of champfering tooling, which
avoids the creation of cut chips of the material, and
avoids any need to drill the so-formed champfered blanks.
We have found that there is less wastage of material
by employing the series of punch operations as described
hereinabove than there would be in seeking to perform
similar operations by cutting tools. Moreover, even with
relatively unskilled personnel, the resultant blanks prior
to the cutting operation are relatively more uniform so
that the file cuts le can be more readily formed and there
is less likelihood of sharp edges to those cuts being
created which would tend to lacerate the finger of the
user of a lighter.
The series of punch operations further has the
effect of forming an outer hardened layer lf (see Fig. 12)
on the wheel having better hardness properties, tensile
strength and yield point and a wear resistance which may
be two to three times more than for flint wheels formed
by other processes.
