Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a key cutting
machine, and more particularly to an improved atuomatic key cut-
ting machine having a key carriage that can be pivotably moved
by means of a torsion spring, and can be moved leftward and
rightward along a guide rod by means of a reversible motor as
well as a pair of microswitches in order to effect the key cut-
ting automatically.
In a conventional automatic key cutting machine, the
milling cutter and key carriage are driven by the same motor,
hence cams should be used For obtaining reciprocal movement of
the key carriage. However, the use of cams can only urge the
key carriage to move forward for effecting the key cu-tting, and
cannot urge the same to return to its original position. For
effecting the next key cutting, it is necessary to have the key
carriage pivotably moved by hand to such a degree that the key
blank is moved away from the milling cutter and thus the key
carriage can be moved back to its original position. This will
decrease the cutting speed and its accuracy. Furthermore, it is
impossible for the key carriage to change its moving direction
and to make a stop during its moving period due to the use of
cams.
The present invention provides an improved automatic
key cutting machine comprising two motors, in which one of the
motors is used for driving a milling cutter to ro-tate while the
other motor is a reversible motor and used for driving key
carriage which is moved leftward and rightward in conjunction
with a pair of microswitches. The key carriage can make a stop
during its moving period by means of a double pole, single throw
switch.
According to the present invention there is provided
an automatic key cutting machine comprising: a motor for rota-
tably driving a milling cutter; a key carriage for holding a key
sample to be copied and a key blank to be machined into the form
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of a sample by the milliny cutter; a guide structure alony ~/hich
the key carriage is lineraly movable; bias means for biasing th~
key carriage into a working position in which a key sample
carried thereby is engaged by a guide secured on a frame of the
5 machine, and in which a key blank carried by the carriage is
engaged by said milling cutter; a reversible rotary motor;
rotary-to-linear motion conversion means arranged to convert
rotation of an output shaft of the reversible motor into linear
movement, the key carriage being coupled to said conversion
rneans such that operation of the reversible motor causes the key
carriage to move along the guide structure in a direction
dependent on the sense of rotation of said output shaft; and a
limit arrangement means for automatically de-energizing said
reversible motor to stop the key carriage when the cutting of a
key blank is complete, said limit arrangement means including a
pair of spaced switches connected into the energization circuit
of the reversible motor and a switch-operating member linearly
reciprocable movable by said conversion means between said
switches whereby to operate the latter at respective predeter-
20 mined lirnit positions of the carriage along its guide structure.
Thus according to the present invention the auto-
matic key cutting machine comprises a motor arranged in con-
junction with a toggle switch for driving a milling cutter to
25 rotate. A torsion spring arranged between a guide rod and a key
carriage for biasing a key sample secured on the key carriage
against a guide secured on a frame, and biasing a key blank
secured on the key carriage against the milling cutter for
cutting the key blank. In addition, the following members are
provided; a lead screw slidably engaged with the guide rod; a
reversible motor for driving the key carriage to move leftward
and rightward; a small lead screw; a nut engaged with the small
lead screw and having a protrusion protruding between a pair of
microswitches for butting against the latter in order to enable
the key carriage to make a stop when cutting of the key blank is
completed; and a snap lock for locking the key carriage in such
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a position that the key blank is moved away from the milling
cutter for the convenience of releasing the key sample or
securing a key blank on the key carr1age.
In one embodiment of the present invention said
rotary-to-linear motion conversion means comprise respec-tive
rotary-to-linear action conversion members for driving the key
carriage and for driving the switch-operating member. Suitably
said rotary-to-linear motion conversion means comprise a common
rotary-to-linear motion conversion member for driving both the
key carriage and the switch-operating member. Preferably the
conversion means includes an output member linearly slidable
along said guide structure and mounting the key carriage, the
guide structure being in the form of a guide rod extending
through an aperture in said output member and the key carriage
being pivotal about the axis of the guide rod into its working
position under the action of said bias means. Desirably said
output member is a lead screw serving as a rack gear~ the lead
screw being engaged by a pinion of the conversion means and
having an axial aperture through which said guide rod passes.
More preferably the switch-operating member is provided with a
pair of adjustable screws on opposite sides thereof for engaging
respective ones of the said switches.
An embodiment of the present invention will now be
described by way of example with reference to the accompanying
drawings, in which:-
Figure l is a pictorial view of an embodiment of an
automatic key cutting machine in accordance with the presentinvention;
Figure 2 is a top view oF the automatic key cutting
machine of Figure l;
Figure 3 is a side view of the automatic key cutting
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machine of Figure l;
Figure 4 is a sectional view of a snap lock in accor-
dance with the present invention; and
Figure 5 shows one possible embodiment of the circuit
of the present invention.
Referring now to Fig.s 1 to 4, the automatic key cut-
ting machine of this invention includes a motor Ml secured on abase 5 for driving a pair of milling cutters 3 and 4 secured on
an axis 2 rotatably secured on the base 5. A reversible motor
M2
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is also secured on the base 5 for driving a key carriage 6
to move leftward and rightward. A nut 10 is engaged with
a small leader 9 rotatably secured on the base 5, and hav-
ing a protrusion protruding between a pair of microswitches
15 and 16 for butting against the latter in order to cut off
a circuit of the reversible motor M2, and urge the key carr-
iage 6 to be stopped. The protrusion is also provided with
a pair of regula-ting screws 14 at left and right sides there-
of for serving as a punch rod for respectively butting against
10 microswitches 15 and 16. The nut 10 is fur-ther provided with
an elonga-ted slot 11 for engagement with a rail 12 secured on
the base in order to urge nut 10 to move leftward or right-
ward along rail 12 when small lead screw 9 rotates in a
clockwise or counter-clockwise direction.
The small lead screw 9 is driven by the reversible
motor M2 by means of a bel-t gear 18 as well as a belt 5. A
bevel gear 17 is secured at one end of the small lead screw
9, and meshed with a bevel gear 17' secured on an axis 19 in
order that the latter can be driven by the reversible motor
M2. A worm gear 20 is secured on the axis 19, and meshed
with a lead screw 7 for driving the lat-ter leftward or right-
ward. The lead screw 7 is in a form of a worm, and slidably
engaged with a guide rod 8. A key carriage 6 is secured on
the lead screw 7 in order that the former can be moved together
with the latter. A torsion spring 21 is arranged between the
guide rod 8 and key carriage 6 for biasing a key sample (not
shown) secured on the left end side of the key carriage 6
against a guide 22 secured on the base 5, and for biasing a
key blank 23 secured on the right end key carriage 6 against
the milling cutter 3 in order to urge the milling cutter to
cut the key blank 23 for duplicating a key to be the same as
the key sample (not shown) when the key carriage 6 is moved
leftward and the key sample is moved along -the guide 22.
Referring now to Flg.s 3 and 4, the leader 7 and
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guide rod 8 are respectively provided with an elongated slot
(71,81) arranged in alignment one with the other for receiving
a snap lock 24 in order to enable the key earriage 6 to be
angularly moved and locked in a position away from the eutter
guide for -the convenienee of releasing or seeuring the key
sample and a key blank on the key earriage.
Now please turn to Fig. 5, when the toggle switch
L is in its left side "ON" posi-tion, the movable plate will
be moved to contacts B and D to form a circuit including
motor Ml for driving the rnilling eutters 3 and 4 to rotate,
and a circuit including the reversible motor M2 for driving
key carriage 6 to move leftward for cutting a key blank, and
driving nut 11 to move leftward. The circuit including the
reversible motor M2 will be broken, and motors Ml and M2 will
be stopped when the regulating serew 14 butted against miero-
switeh 15. On the eontrary, when the toggle switch L is in
its right side "ON" position, the movable plate will be moved
to contacts A and C to form a eireuit ineluding Ml for driving
the milling eutters 3 and 4 to ro-tate, and a eircuit including
reversible motor M2 for driving key carriage 6 to move right-
ward for cutting key blank, and driving nu-t 11 to move right-
ward. The eireuit including the reversible motor M2 will be
broken, and motors M1 and M2 will be stopped when the regulat-
ing screw 14 abuts against the mieroswiteh 16. Obviously,
the key earriage ean be moved leftward and rightward without
moving the same away from milling eutter.
The above said eireuits may inelude a double pole,
single throw switeh P for urging reversible motor M2 to be
stopped when switeh P is opened, and motor Ml keeps rotating.
