[0001] This invention relates to a grinding fixture for grinding scissors in accordance
with the preamble of claim 1 and is for instance intended for use in grinding machines
provided with a grindstone and equipped with a fixed support of the type described
in Swedish Patent Application No. 8306325-5.
[0002] So far there has been no good aid for grinding scissors by means of a grindstone.
The blades of the scissors can be plane, be straight or arcuately tapering longitudinally,
have a cross section that is plane or like a partial circle, and have an edge which
is straight or convex lengthwise of the blade. In addition, the cutting angle is very
sharp in scissors.
[0003] However, it is possible by means of this invention, as it is apparent from the characterizing
portions of the claims, to adjust and move the edges of the scissors - one at a time
-across the grindstone by means of a holder or grinding fixture so that the best
possible result is obtained independently of the form of the blades of the scissors.
Also an unexperienced person can grind all types of scissors simply and quickly by
means of the grinding fixture of the invention.
[0004] The invention will be described in greater detail in the form of an example with
reference to the drawing wherein
Fig. 1 is a schematic partial view of a pair of scissors clamped in a fixture according
to the invention,
Fig. 2 shows a cross section of the fixture according to Fig. 1 and
Fig. 3 shows a longitudinal section of the fixture shown in Fig. 1.
[0005] In the figures 1 denotes a grindstone and 2 a support fixedly secured to the grinding
machine in the form of a yoke with an arm 3 extending in parallel with the axis of
the grindstone 1. The grinding machine with support and arm is known per se and is
no part of the invention, and therefore this will not be described more closely but
it is referred to said Swedish Application 8306325-5 in this connection.
[0006] The grinding fixture consists of a support plate 4 which is bent at right angles
and carries a welded pipe or a bushing 5, by means of which the support plate is supported
by the arm 3 so that it can be moved and turned. A threaded, through hole is made
in the wall of the bushing 5 in which a screw provided with a knob is threaded. The
knob has the reference numeral 6. By means of the knob and the screw attached to this
the support plate 4 can be fixed in a suitable position along the arm 3 and at the
intended angle defined by the edge angle of the pair of scissors to be ground.
[0007] A first clamping plate 7 which in the example shown has a layer of low-friction material
8, for example teflon®, on the side facing the support plate 4, abuts on the support
plate 4 freely movably. Moreover, the first clamping plate 7 has two threaded holes
9 in the example shown. Two other clamping plates 10 have through holes 11 corresponding
to the threaded holes 9, through which set screws 12 pass. In the respective second
clamping plate 10 a locking screw 13 provided with a wheel is arranged to be screwed
into the plate at some distance from the set screws 12. In the example shown the threads
of the screw 13 are made in a threaded bushing 14 arranged in the respective plate
10.
[0008] The head of the respective set screw 12 has a partly spherical inside resting in
a corresponding partly spherical seat of the second clamping plate 10. The distance
between the second clamping plates 10 and the first clamping plate 7 can be optionally
adjusted in dependence on the thickness of the blade 15 of the scissors to be ground
by means of the screws 12. In Fig. 3 there is shown a blade of a pair of scissors,
the thickness of which decreases towards the tip and it is clearly apparent from the
figure how different an adjustment is required of the distance of the second clamping
plates 10 from the first clamping plate 7 is required. By the partly spherical head
form of the screw 12 and its coacting seat of the respective clamping plate 10 these
can adjust themselves obliquely and independently of one another relative to the first
clamping plate 7. Consequently there is a possibility for a complete adaptation of
the clamping plates to the form of the blade of the pair of scissors, the edge of
which is to be ground.
[0009] As is clearly apparent from Fig. 2 the free end of the locking screw 13 engages the
first clamping plate 7 and due to the fact that the set screw 12 at the respective
second clamping plate 10 is arranged in the vicinity of the region where the blade
of the pair of scissors is adapted and the locking screw 13 is arranged on the opposite
side relative to the blade and spaced from the set screw 12, the locking screw 13,
when turned, will swing the second clamping plate 10 from the first clamping plate
7 with the set screw 12 as turning point and consequently lock the blade 15 placed
between the edge portions of the clamping plates 10 and 7. By this "lever principle"
it is possible to attain very great locking forces for the blade of the pair of scissors.
[0010] In order to achieve defined locking ranges of the blade of the pair of scissors the
respective second clamping plate 10 at each end of the locking edge area is provided
with a downwardly directed flange 16 (see Fig. 3). These flanges can be simply obtained
by for instance milling the central area in the respective plate. In order to control
the second clamping plates 10 relative to the first clamping plate 7 a pair of guide
pins shematically shown in Fig. 1 and designated by 17 are attached to the respective
plate 10. These pins extend freely movably through the corresponding holes or openings
in the first clamping plate 7. Moreover, helical compression springs can be arranged
around the respective pin 17 between the plates 10 and the plate 7, which springs
tend to separate the plates 10 and the plate 7 automatically which makes it easier
to place the blade of the pair of scissors between the edge portions of the plates.
[0011] Thus, by adjusting the screws 12 the fixture can be adapted to the thickness of
the current blade of the pair of scissors and said blade is clamped in the fixture
when tightening the locking screws 13. Thus, the clamping plates 10 will adapt themselves
automatically to the form of the relative blade independently of whether its cross
section is conical or in the form of a partial circle or if it is conical longitudinally.
The support plate 4 is locked by means of the screw 6 at the arm 3 with the current
edge angle of the pair of scissors, and the part of the fixture formed by the clamping
plates 7 and 10 can now be moved backwards and forwards supporting against the plate
5 while the edge of the pair of scissors is being ground. In this way the motion can
be simply adapted so that the possibly arcuate edge of the pair of scissors is in
contact with the screw all the time. The low fric tion material 8 makes this motion
easier. However, it is to be understood that this low friction material is not necessary
but can be omitted.
[0012] A fixture with two other clamping plates 10 has been described above, but of course
more than two such clamping plates can be used. Of course it is possible, for example
when grinding only small pairs of scissors, to use a fixture having only one second
clamping plate 10. The shapes of the support plate 4, the first clamping plate 7 and
the second clamping plates 10 can of course vary and deviate from the shapes shown
here. Moreover, the guide pins 17 can be attached to the first clamping plate 7 instead
of the plates 10.
1. Grinding fixture for grinding scissors by means of a rotatable grindstone (1) using
an adjustable support arm (3) arranged at the grindstone base and extending transversely
of the grindstone (1) in parallel with the axis thereof as well as a support plate
(4) movably and rotatably fixable to the support arm (3), characterized by a first clamping plate (7) abutting on the support plate (4) freely movably and
at least one second clamping plate (10) having a clamping edge, one blade (15) of
a pair of scissors to be ground being clampable between the clamping edge and the
first clamping plate (7) by means of one or more screws (12, 13).
2. The grinding fixture of claim 1, characterized in that the clamping edge of the second clamping plate (10) has flanges (16) arranged
in spaced relationship, facing the blade (15) of the pair of scissors and extending
transversely of the blade.
3. The grinding fixture of claim 1 or 2, characterized in that two or more second clamping plates (10) are arranged beside each other on
the first clamping plate (7) in order to adapt themselves each and clamp their part
of the blade (15) against the first clamping plate (7).
4. The grinding fixture of any one of the preceding claims, characterized in that the first clamping plate (7) and the second clamping plate (10) are connected
to each other by means of a set screw (12) immediately at the pair of scissors adjusting
the mutual distance of the plates (7, 10).
5. The grinding fixture of claim 4, characterized in that a locking screw (13) is arranged to be screwed into a threaded hole (14)
extending through the first or second clamping plate (7 and 10, respectively), said
hole being located on the opposite side of the set screw (12) relative to the blade
(15) of the pair of scissors to be ground, and that one end of the locking screw (13)
engages the second and first clamping plate (7, 10), respectively.
6. The grinding fixture of any one of the preceding claims, characterized in that the first or the second clamping plate (7 and 10, respectively) has at least
one fixed guide pin (17) coacting with an aperture arranged in the coacting clamping
plate (7, 10) and that a compression spring is arranged between the plates in connection
with the guide pin (17).