GB2150475A

GB2150475A - Automatic key cutting machine

Info

Publication number: GB2150475A
Application number: GB08406617A
Authority: GB
Inventors: Kuo-Shen Wu
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-11-29
Filing date: 1984-03-14
Publication date: 1985-07-03
Also published as: GB8331863D0; GB8406617D0; GB2150475B

Abstract

The machine has a pivotally-mounted key carriage (6) that is urged by a torsion spring (21) into a working position in which a key sample and key blank carried by the carriage (6) are respectively engaged with a fixed guide (22) and with a milling cutter (3). Bi-directional linear movement of the key carriage (6) is achieved by attaching the latter to an output member (7) of rotary-to-linear motion converter (7, 17) that is kinematically connected to a reversible rotary motor (M2). Limitation of the movement range of the key carriage (6) is effected by means of a pair of limit switches (15, 16) that are connected into the energisation circuit of the reversible member (M2) and are controlled by a member (13) moving in synchronism with the carriage (6). <IMAGE>

Description

SPECIFICATION Automatic key cutting machine The present invention relates to a key cutting machine, and more particularly to an automatic key cutting machine having a key carriage that is pivotally biassed into a working position 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 cutting automatically.

In a conventional automatic key cutting machine, the milling cutter used to cut a key blank and the key carriage used to displace the key blank relative to the cutter, are both driven by the same motor.

As a result, key cutting is generally effected with the carriage moving in only one of its two possible movement directions so that it is necessary after a key-cutting operation to return the carriage to its original position. In order to return the carriage to its starting position, it must be pivoted by hand away from the milling cutter. All these operations decrease the efficiency of the machine.

It is an object of the present invention to provide an automatic key cutting machine with increased operating efficiency.

According to the present invention there is provided an automatic key cutting machine comprising a motor for rotatably 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 of the sample by the milling cutter; a guide structure along which the key carriage is linearly movable; bias means for biassing the key carriage into a working position in which a key sample carried thereby is engaged by a guide secured on a frame of the 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 means 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 for automatically de-energising said reversible motor to stop the key carriage when the cutting of a key bland is complete, said limit arrangement including a pair of spaced switches connected into the energisation circuit of the reversible motor, and a switch-operating member linearly reciprocably movable by said conversion means between said switches whereby to operate the latter at respective predetermined limit positions of the carriage along its guide structure.

An automatic key cutting machine embodying the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the key cutting machine, parts of the machine being cut away or omitted for reasons of clarity; Figure 2 is a top plan view of the key cutting machine; Figure 3 is an end view of the key cutting machine; Figure 4 is a sectional view of a snap lock forming part of the key cutting machine; and Figure 5 shows one possible form of the electrical circuit of the key cutting machine.

Referring now to Figs. 1 to 4, the automatic key cutting machine includes a motor M, secured on a base 5 and arranged to drive a pair of milling cutters 3 and 4 mounted on a shaft 2 rotatably supported on the base 5. A reversible rotary motor M2 is also secured on the base 5 and is coupled via a first rotary-to-linear motion conversion arrangement 7, 20 to a key carriage 6 to cause bi-directional linear movement of the latter along a guide rod 8.The limits of leftward and rightward movement (as viewed in Figures 1 and 2) of the carriage 6 along the guide rod 8 is controlled by a pair of microswitches 15 and 16 that are connected into the energisation circuit of the reversible motor M2 and are arranged to be operated by a switch-operating member 13 driven from the motor M2, via a second rotary-to-linear motion conversion arrangement, so as to move in correspondence with the key carriage 6.

The aforesaid first and second rotary-to-linear motion conversion arrangements will now be described in greater detail.

The first conversion arrangement comprises a pinion 20 meshing with a rack gear constituted by a leadscrew 7. The lead screw 7 is formed with an axial through hole through which the guide rod 8 extends whereby the lead screw 7 is linearly slidable along the rod 8 in dependence on rotation of the pinion 20. The key carriage 6 is fast for linear movement with the lead screw 7. The pinion 20 is mounted on a shaft 19 which is rotatably coupled, via a pair of bevel gears 17, with a further shaft that carries a belt gear 18. The gear 15 is arranged to be driven from the reversible motor M2 by means of a drive belt 5. Due to this arrangement, rotation of the output shaft of the motor M2 is effective to cause leftward or rightward movement of the key carriage 6 depending on the sense of motor rotation.

The second rotary-to-linear motion conversion arrangement comprises a lead screw 9 provided at one end of the shaft carrying the gear 15, and a nut 10 engaged with the lead screw 9. The nut 10 is provided with an elongate slot 11 which is engaged by a rail 12 secured to the base 5. The rail 12 serves to prevent rotation of the nut 10 while permitting linear movement of the latter. The switch-operating member 13 is integral with the nut 10. Due to this arrangement, rotation of the motor M2 causes the nut 10 and thus the member 13, to be linearly displaced to the right or to the left depending on the sense of rotation of the motor M2. The magnitude and direction of this linear displacement will reflect the magnitude and direction of displacement of the key carriage 6.

The switch-operating member 13 is provided on opposite sides with two regulating screws 14, each arranged to operate a respective one of the mi croswitches 15, 16 to cut off the motor M2 when the member 13 (and thus the key carriage 6) has moved into a leftward or rightward limit position.

The key carriage 6 is arranged to hold a key sample (not shown) in its left-hand end and a key blank (also not shown) in its right-hand end; for this purpose, the key carriage is provided with clamping screws (not shown in Figure 1 but visible in Figure 2, though not referenced). The carriage 6 is pivotal about the axis of the rod 8 into a working position in which a key sample held in the carriage engages against a guide 22 secured on the base 5 and in which a key bland held in the carriage engages the milling cutter 3. The key carriage 6 is biased into working position by a torsion spring 21.

During operation of the key cutting machine, the key carriage 6 is in its working position and is displaced along the guide rod 8 such as to cause the milling cutter 3 to machine a key blank in correspondence to the profile of a key sample held in the carriage.

In order to facilitate both the introduction of key blanks and samples into the key carriage 6 and their subsequent removal, the key carriage 6 is provided with a snap lock 24 (see Figures 3 and 4).

The snap lock serves to temporarily secure the carriage 6 in a non-working position in which a key sample and key blank 23 held thereby are spaced from the guide 22 and cutter 3 respectively.

The snap lock 24 comprises a spring-biased pin 25 that is arranged to engage in axially-extending slots 71, 81 formed in the lead screw 7 and guide rod 8; these slots are aligned with one another at least when the carriage is in its non-working position.

The electrical circuit of the key cutting machine is shown in Figure 5. As will become clear below, the motor M, that drives the milling cutters 3, 4, is arranged to be energised continuously regardless of the states of the various switches included in the electrical circuit. In contrast, the operation of the motor M2 is dependent on the limit microswitches 15, 16, on a two-position reversing switch L operable to reverse the direction of rotation of the motor M2, and on an onloff switch P.

The direction of rotation of the motor M2 de pends on which one of two motor input lines is connected to one of the two live conductors of a single phase a.c. supply, the other live conductor being permanently connected to the motor M2. The aforesaid two motor input lines are connected via respective poles of the on/off switch P and via respective ones of the limit microswitches 15, 16 to respective contacts A, B of the reversing switch L.

When the reversing switch L is in a first position, the said one of the live conductors is connected via the contact A, the microswitch 16, and the switch P to one of the two said motor input lines whereby to cause the motor M2 to rotate in one direction; when the key carriage 6 reaches its limit position in the corresponding movement direction, the switch-operating member 13 will open the microswitch 16 to stop the motor M2. Switching the reversing switch L into its second position causes the said one live conductor to be connected via the contact B, the limit microswitch 15, and the switch P to the other of the two said motor input lines to cause the motor M2 to rotate in the opposite direction; in this case, when the key carriage reaches its opposite limit position, the microswitch 15 is opened to stop the motor M2.

Whichever of the said motor input lines is energised, a second pair of contacts C, D of the switch L ensures that the motor M, is energised, connection of the contacts C, D to the motor input lines being made upstream of the switch P to permit the motor M, to continue to operate even when the motor M2 is switched off.

From the foregoing it can be seen that the invention provides an automatic key cutting machine comprising two motors M1, M2 one of which is used for driving the milling cutter, while the other is a reversible motor used for driving the key carriage to move leftward and rightward to adjustable limits set by a pair of microswitches. Furthermore, the direction of movement of the key carriage can be readily reversed by means of the reversing switch L and the carriage can be stopped, without stopping the motor M1, by means of a switch P.

Various modifications to the described key cutting machine are, of course, possible. Thus, for example, the switch-operating member could be mounted for movement with the key carriage 6 rather than being driven by a respective rotary-tolinear motion conversion arrangement.

Claims

1. An automatic key cutting machine comprising a motor for rotatably 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 of the sample by the milling cutter; a guide structure along which the key carriage is linearly movable; bias means for biasing the key carriage into a working position in which a key sample carried thereby is engaged by a guide secured on a frame of the 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 means 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 for automatically de-energising said reversible motor to stop the key carriage when the cutting of a key blank is complete, said limit arrangement including a pair of spaced switches connected into the energisation 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 predetermined limit positions of the carriage along its guide structure.

2. A key cutting machine according to Claim 1, wherein said rotary-to-linear motion conversion means comprise respective rotary-to-linear action conversion arrangements for driving the key carriage and for driving the switch-operating member.

3. A key cutting machine according to Claim 1, wherein said rotary-to-linear motion conversion means comprise a common rotary-to-linear motion conversion arrangement for driving both the key carriage and the switch-operating member.

4. A key cutting machine according to any one of the preceding claims, wherein 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 said working position under the action of said bias means.

5. A key cutting machine according to Claim 4, wherein 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.

6. A key cutting machine according to Claim 4 or Claim 5, wherein the said output member and guide rod are each provided with an elongate slot, said slots being in alignment with each other at least when the carriage has been pivoted from its said working position, against the force of the bias means, into a non-working position in which a key blank placed in the carriage is spaced from said milling cutter, the key carriage being provided with a snap lock engageable in said slots when the carriage is in its said non-working position whereby to lock the carriage in this position so as to facilitate the release and replacement of a key sample or key blank.

7. A key cutting machine according to any one of the preceding claims, wherein the said switchoperating member is provided with a pair of adjustable screws on opposite sides thereof for engaging respective ones of the said switches.

8. A key cutting machine substantially as hereinbefore described with reference to the accompanying drawings.