GB1559966A - Safety device for machines - Google Patents

Description

(54) A SAFETY DEVICE FOR MACHINES (71) I, CARL-ERIC WIKLUND of Stenbocksvagen I4, S-815 00 Tierp, Sweden, a Swedish Subject, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a safety device for machines, such as lathes, drilling machines or the like, in which at least one key or tool is used for adjusting the machine, such as the chuck thereof, between various work operations, comprising a switch which is connected to the drive of the machine and which through a dog is actuated by the operation of the adjustment key in order to disconnect the drive when the adjustment key is removed from a predetermined position of rest and to connect the drive when the key is returned to said position of rest.

A device of the above-mentioned type is previously known by the US patent specification 2 713 407. In that device the adjustment key is secured to one end of a flexible chain, the other end of which is attached to a spring-loaded reel. The spring of this reel normally biases reel in a direction to cause the chain to be wound about the spool of the reel.

For controlling the position of the adjustment a bead is disposed on the chain for engaging an arm of a switch for the drive of the machine. By the fact that the adjustment key is secured to the chain and spring-loaded therethrough difficulties arise when using the key, since this always tends to return to the position of rest. Therefore this reel and chain device will result in a reduced reliability in operation. Further this device is completely inappropriate to be used in connection with weighty adjustment keys, such as chuck keys for lathes or the like. The object of the present invention is to eliminate the abovementioned drawbacks and provide a device which leads to an efficient elimination of accidents and which makes it possible for the operator to freely perform the work operations and the adjustments of the machine.

According to the invention this is achieved by a device wherein a casing is arranged for the adjustment key, the key being wholly or partially insertable to said position of rest within said casing, and wherein the dog of the switch is disposed at least partially projecting into said casing so as to perform said disconnecting and connecting of the drive of the machine by direct engagement with the adjustment key when this is removed from and inserted in the cavity respectively. Hereby a reliable and effective device is provided which by the absence of connecting means between the adjustment key and the switch does not interfere with the operator's work.

Further the device of the invention serves as a handy and easily accessible holder of the adjustment key when this is not used.

An embodiment of the invention will be described in detail hereinafter with reference to the accompanying drawings wherein: Fig 1 is a view in perspective of the device with an adjustment key inserted therein.

Fig 2 is a sectionalized side view of the device of Fig 1.

Fig 3 is a view from below in Fig 2.

Fig 4 is a view similar to Fig 2 but showing an adjustment key inserted in the device.

The device shown in the drawings comprises a housing 1 designed to be mounted on or adjacent to a lathe, a miller, a drilling machine or the like, said housing having a through casing 2 open at the ends. This casing comprises a cylindrical portion 4 as well as a conical portion 3 serving to facilitate the insertion of an adjustment key 6 into the casing. Furthermore the casing 2 is changeable by casings of other sizes so as to receive, with a suitable clearance, various types of adjustment keys. A bent edge 5 of the casing attends to the supporting and localization of the casing 2 relative to the housing 1 together with the bottom end of the casing abutting against the edge of a circular aperture in the bottom of the housing.

The wall of the casing 2 is provided with a recess or slit 11 through which porjects a dog generally designated 8. This dog comprises a roller 10 which is rotatably mounted on the end piece of an arm 9 which is connected to a switch 7 for the drive or source of power of the machine. The arm 9 is spring-loaded in order to urge roller 10 to a position in which it is at least partially porjetcing into the casing.

The switch 7, which has holes 14 for the fastening thereof in the housing 1, is arranged to disconnect the drive of the machine when dog 8 assumes the position shown in Fig 2 and maintain this disconnection until the envelope surface of the adjustment key 6 will bring the dog at least partially out of the casing 2 on which occasion the arm 9 once again changes over the switch to permit driving of the machine.

In order to render the fastening of the housing to a machine possible there is provided a nut arrangement 12 having an axial opening 13 which permits the leading in of connection leads between the switch 7 and the drive of the machine.

The device according the invention is used in the following manner: In normal operation of the machine the adjustment key 6 is inserted in the casing 2 and the dog 8 of the switch 7 is at least partially forced out of the casing. In this state the switch 7 has connected the drive of the machine, permitting work to be done. When an adjustment of e.g. a lathe chuck is thereafter required the adjustment key 6 is removed from the casing.

Then the dog 8, thanks to the spring-loading, moves at least partially into the casing, what means that the switch is actuated through the arm 9, thereby disconnecting the drive of the machine, When the adjustment operation has been accomplished the adjustment key is once again inserted in the casing 2 and thereby driving of the machine is permitted.

In an embodiment not shown in the drawings the casing and the adjustment key are provided with analogous recesses and projections or the like. Hereby it is guaranteed that only the correct adjustment key can be inserted in the casing.

The expression "drive" used above should be understood in its widest sense because the invention is not merely limited to use in connection with machines having an electrical drive but it is applicable to e.g. machines being hydraulically or pneumatically driven too. Thus the switch may be of the electrical type as well as of any other type adapted to the driving device.

Further it should be observed that the clearance between the adjustment key and the casing must not, in order to secure a correct function of the device, exceed certain limits determined by the extension of the dog 8 within the casing and the features of the switch. If the clearance would be too great to guarantee a safe function the casing may simply be replaced by another casing having other dimensions.

From Fig 4 it appears in detail how the adjustment key 6 is inserted in the casing 2 and how the roller 10 of dog 8 is forced out of the casing. In this position the switch 7 is actuated in order to permit driving of the machine.

Of course the intervention is not merely limited to the embodiment described above and shown in the drawings, but many modifications are possible within the scope of the attached claims. Thus the device according to the invention may advantageously be realized on or integral with the machine in question directly in connection with the manufacture thereof. Further the casing may be realized in another way than that shown in the drawings where the casing extends completely through the housing and where the adjustment key is suspended by means of the transversely projecting pins. Instead of such an arrangement the casing may be provided with a bottom supporting the adjustment key and in connection to which the dog of the switch may be disposed.

WHAT I CLAIM IS 1. A safety device for machines of the type in which at least one key is used for adjusting the machine between various work operations, comprising a switch which is connected to the drive of the machine and which through a dog is actuated by the operation of the adjustment key in order to disconnect the drive when the adjustment key is removed from a predeterminated position of rest and to connect the drive when the key is returned to said position of rest, characterized in that a casing is arranged for the adjustment key, the key being wholly or partially insertable to said position of rest within said casing, and that the dog of the switch is disposed at least partially projecting into said casing so as to perform said disconnecting and connecting of the drive of the machine by direct engagement with the adjustment key when this is removed from and inserted in the cavity respectively.

2. A safety device according to claim 1, wherein the dog projects into the casing through a slit in the wall of the casing.

3. A safety device according to claim 1 or 2, wherein the dog is spring-loaded in order to aim at assuming a position in which it is at least partially projecting into the casing and wherein the dog is arranged to be urged out of the casing when the adjustment key is inserted in the casing.

4. A safety device according to anyone of the preceding claims, wherein the dog comprises a roller disposed at one end of an arm the opposite end of which is connected to the switch.

5. A safety device according to anyone of claims 1 to 3, wherein the casing is removably mounted in a housing for the safety device.

6. A safety device according to claim 1, wherein the casing and the adjustment key are provided with analogous projections and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. The switch 7, which has holes 14 for the fastening thereof in the housing 1, is arranged to disconnect the drive of the machine when dog 8 assumes the position shown in Fig 2 and maintain this disconnection until the envelope surface of the adjustment key 6 will bring the dog at least partially out of the casing 2 on which occasion the arm 9 once again changes over the switch to permit driving of the machine. In order to render the fastening of the housing to a machine possible there is provided a nut arrangement 12 having an axial opening 13 which permits the leading in of connection leads between the switch 7 and the drive of the machine. The device according the invention is used in the following manner: In normal operation of the machine the adjustment key 6 is inserted in the casing 2 and the dog 8 of the switch 7 is at least partially forced out of the casing. In this state the switch 7 has connected the drive of the machine, permitting work to be done. When an adjustment of e.g. a lathe chuck is thereafter required the adjustment key 6 is removed from the casing. Then the dog 8, thanks to the spring-loading, moves at least partially into the casing, what means that the switch is actuated through the arm 9, thereby disconnecting the drive of the machine, When the adjustment operation has been accomplished the adjustment key is once again inserted in the casing 2 and thereby driving of the machine is permitted. In an embodiment not shown in the drawings the casing and the adjustment key are provided with analogous recesses and projections or the like. Hereby it is guaranteed that only the correct adjustment key can be inserted in the casing. The expression "drive" used above should be understood in its widest sense because the invention is not merely limited to use in connection with machines having an electrical drive but it is applicable to e.g. machines being hydraulically or pneumatically driven too. Thus the switch may be of the electrical type as well as of any other type adapted to the driving device. Further it should be observed that the clearance between the adjustment key and the casing must not, in order to secure a correct function of the device, exceed certain limits determined by the extension of the dog 8 within the casing and the features of the switch. If the clearance would be too great to guarantee a safe function the casing may simply be replaced by another casing having other dimensions. From Fig 4 it appears in detail how the adjustment key 6 is inserted in the casing 2 and how the roller 10 of dog 8 is forced out of the casing. In this position the switch 7 is actuated in order to permit driving of the machine. Of course the intervention is not merely limited to the embodiment described above and shown in the drawings, but many modifications are possible within the scope of the attached claims. Thus the device according to the invention may advantageously be realized on or integral with the machine in question directly in connection with the manufacture thereof. Further the casing may be realized in another way than that shown in the drawings where the casing extends completely through the housing and where the adjustment key is suspended by means of the transversely projecting pins. Instead of such an arrangement the casing may be provided with a bottom supporting the adjustment key and in connection to which the dog of the switch may be disposed. WHAT I CLAIM IS

1. A safety device for machines of the type in which at least one key is used for adjusting the machine between various work operations, comprising a switch which is connected to the drive of the machine and which through a dog is actuated by the operation of the adjustment key in order to disconnect the drive when the adjustment key is removed from a predeterminated position of rest and to connect the drive when the key is returned to said position of rest, characterized in that a casing is arranged for the adjustment key, the key being wholly or partially insertable to said position of rest within said casing, and that the dog of the switch is disposed at least partially projecting into said casing so as to perform said disconnecting and connecting of the drive of the machine by direct engagement with the adjustment key when this is removed from and inserted in the cavity respectively.

2. A safety device according to claim 1, wherein the dog projects into the casing through a slit in the wall of the casing.

3. A safety device according to claim 1 or 2, wherein the dog is spring-loaded in order to aim at assuming a position in which it is at least partially projecting into the casing and wherein the dog is arranged to be urged out of the casing when the adjustment key is inserted in the casing.

4. A safety device according to anyone of the preceding claims, wherein the dog comprises a roller disposed at one end of an arm the opposite end of which is connected to the switch.

5. A safety device according to anyone of claims 1 to 3, wherein the casing is removably mounted in a housing for the safety device.

6. A safety device according to claim 1, wherein the casing and the adjustment key are provided with analogous projections and

recesses respectively whereby insertion of erroneous means into the casing is prevented.

7. A safety device for a machine, constructed and arranged substantially as herein described, with reference to the accompanying drawings.