GB1596237A

GB1596237A - Machinery guarding device

Info

Publication number: GB1596237A
Application number: GB1232578A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-24
Filing date: 1978-05-24
Publication date: 1981-08-19

Description

(54) MACHINERY GUARDING DEVICE (71) I, JAMES MALCOLM SHARP, a British subject, of 22 Railway Road, Idle, Bradford, West Yorkshire 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:- This invention relates to a machinery guarding device and has been developed primarily, though not exclusively, with a view to shielding and preventing access to large pieces of machinery such as carding machines.

It is only in recent years that the Factory Inspectorate have been requiring the installation of guards to shield workers from carding machines, and a number of different designs of guard have been supplied. In addition to providing protection against coming into contact with moving parts of the machine, there is also a requirement that some form of "interlock" should be provided which should ensure that unauthorised personnel should not be able to gain access to the machinery while the latter is still in operation.

To satisfy this requirement, a number of mechanical-type interlocks have been made which are coupled-up with control mechanisms for the machinery in such a way that unauthorised opening of a guard to gain access to the machinery should result in automatic stoppage of the machinery.

These interlocks have only been partly successful because the enormous inertia stored-up in machinery of this type means that the parts of the machinery continue to move for quite a long time after drive to the machinery has been interrupted.

Furthermore it has been the practice, in known guards for carding machines, to provide a number of access zones at which access can be obtained without involving stoppage of the machinery. Generally, a special (over-riding) key is provided for use at the access zones which only authorised personnel should be allowed to use. These over-riding keys are additional keys intended for use at a main interlock position on the guard, at which automatic stoppage of the machinery should occur following operation of the key.

With regard to the over-riding keys, It has been found in practice that this cannot be properly supervised, so that unauthorised personnel are able to gain access to the machinery without involving automatic stoppage thereof.

It is desirable that guards for carding machines should allow for visual inspection of the machinery during operation, and to this end known guards have been provided with windows. Known guards are made of sheet metal, and the provision of windows involves additional labour and material costs.

Also, known guards comprises a number of separate door-like parts which are positioned throughout the length of the machinery, and to gain access throughout the length of the machinery, it is necessary to open or dismount all of these separate parts.

The present invention has been developed primarily, though not exclusively, with a view to overcoming some or all of the above drawbacks of the known guards.

According to the invention, there is provided a machinery guarding device which comprises spaced-apart upright supports, a rotatable support extending substantially horizontally between said upright supports, a flexible metal guard mounted on said rotatable support so as to be movable, upon rotation of the latter, between a lowered machinery-guarding position and a rolled-up machinery-access position, an interlock mounted on the guarding device for movement into locking engagement with said metal guard when the latter is in said machinery-guarding position, and inspection apertures formed in said metal guard to enable inspection of machinery to be guarded by the guarding device when the metal guard is in the machinery-guarding position.

In an embodiment according to the invention, a guarding device is provided which has only a single component, (the flexible metal guard) which requires to be moved between the guarding and access positions, so that there is no necessity to provide special limited access zones as in the known guards. This avoids the necessity to provide the over-riding keys, which is an important safety feature.

Preferably, an electrical control system is connected to said interlock, for controlling the movement of the latter between locking and unlocking positions, and includes a first switch for initiating the movement of the interlock to the locking position, a second switch for initiating the movement of the interlock to the unlocking position, and a delay circuit operable to delay the movement of the interlock to the unlocking position following operation of said second switch.

The delay circuit provides a predetermined delay, following operation of the second switch, before the metal guard can be moved to the access position, so that all motion of the machinery (to be guarded by the guarding device) can be arrested before access can be had thereto.

The metal guard may be constructed somewhat in the manner of a "roller door" of the type used in garages, i.e. a flexible metal construction composed of horizontal metal strips hingedly connected together to enable the construction to be rolled-up to an access position and unrolled to a guarding position. The metal strips may be provided with inspection apertures readily by stamping or other suitable metal-forming operations.

One embodiment of machinery guarding device according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a machinery guarding device having a metal guard occupying a machinery-guarding position; Figure 2 is a side view of the guarding device with the metal guard shown rolled-up to a machinery-access position; Figure 3 is a side view of an interlock for locking the metal guard in the guarding position, with the interlock shown in the locked position; Figure 4 is a view, similar to Figure 3, showing the interlock in the unlocked position; Figure 5 is a detail view illustrating the interlock in locking engagement with the metal guard; and Figure 6 is a circuit diagram of an electrical control system for controlling the operation of the interlock.

Referring now to Figures 1 and 2 of the drawings, a machinery guarding device is designated generally by reference numeral 10, and comprises a pair of spaced-apart upright supports 11 and 12, a rotary support 13 extending horizontally between the upper ends of the supports 11 and 12, and a flexible metal guard 14 mounted on the support 13.

The metal guard 14 is mounted on the rotary support 13 so as to be capable of being rolled-up to a machinery-access position as shown in Figure 2, and unrolled to a lowered machinery-guarding position as shown in Figure 1. The metal guard 14 may be constructed to be suitably flexible to carry out movements between its two positions in any convenient manner. By way of example only, the metal guard 14 may be constructed somewhat similarly to the construction of "roller doors" of the type used in garages i.e. composed of horizontally extending strips which are hingedly connected together.

Any convenient drive mechanism may beprovided to rotate the support 13 and, by way of example only, a chain drive system 15 is shown in Figures 1 and 2.

To enable visual inspection of machinery being guarded by the guarding device 10 during operation of the machinery, inspection apertures 16 are formed at appropriate positions in the metal guard 14.

As illustrated, inspection apertures 16 are formed substantially throughout the horizontal and vertical extent of the metal guard 14, though it will be appreciated that the inspection apertures may be provided at any required pre-determined locations corresponding to particular parts of the machinery to be inspected.

In order to lock the metal guard 14 in the machinery-guarding position, a mechanical interlock 17 is mounted on the guarding device e.g. near the upper end of support 12 and is moveable to locking engagement with the metal guard 14 only when the latter occupies the guarding position shown in Figure 1. The construction and operation of the interlock will now be described in more detail, with reference to Figures 3 to 5. The interlock 17 comprises a locking bar 18 which is moveable longitudinally between a locking position shown in Figure 3 and an unlocking position shown in Figure 4.The movement of the bar 18 is controlled by a solenoid 19 which forms part of an electrical control system which will be described in more detail below with reference to Figure In Figure 5, the bar 18 is shown occupying a position of locking engagement with the metal guard 14, in that an opening 20 is formed in one of the horizontal stips of the guard 14 which comes into registry with the bar 18 when the guard 14 occupies the lowered guarding position. In the event that the bar 18 fails to register with the opening 20, it will not be possible for the machinery to be started-up. However, in addition, and as described in more detail below, operation of the electrical control system to effect unlocking of the bar 18 will involve a time delay between initiation of the unlocking operation and the actual unlocking movement of the bar 18.Upon initiation of the unlocking movement, the electrical control system will automatically cause stoppage of the machinery which is being protected, and the delay before unlocking of the bar 18 should be of sufficient duration to enable the motion of the machinery substantially to be arrested.

The electrical control system which will control the operation of the interlock, and also the machinery to be protected, is illustrated schematically in the circuit diagram of Figure 6. The control system comprises a relay R1 having contacts R1A, R1B and R1C, a solenoid S having contacts LS 1 and LS2, and first and second switches 21 and 22. Operation of the first switch 21 initiates the movement of the interlock to the locking position, and operation of the second switch initiates the movement of the interlock to the unlocking position.

A delay circuit is provided in the control system comprising a time delay R2 which is operable to delay the movement of the interlock to the unlocking position following operation of the second switch 22.

Closure of the first switch 21 energises the relay Rl so that contacts R1A, RIB and RIC are moved by the relay to closed positions. This causes energising of the solenoid S with consequent movement of the lock bar 18 to the locking position.

When the solenoid S has moved the lock bar 18 to the fully locked position, contacts LS1 and LS2 will be moved to the closed positions. However, in the event of the lock bar 18 failing to resister with opening 20, contacts LS1 and LS2 will not be closed, so that the machinery cannot be started-up.

When the contacts LS1 and LS2 are closed, this then holds the relay R1 closed, so as to complete the emergency stoD circuit 23 of the machinery to be protected, thereby allowing the machinery to be started-up.

Closure of the second switch 22 energises the time delay R2 which causes an associated contact R2A to open and an associated contact R2B to close for the duration of the time delay as set by the delay R2. This opens the emergency stop circuit 23, as relay Rl is now opened, and holds the solenoid S closed for the duration of the delay period. At the end of the delay period contact R2B then opens, thereby deenergising the solenoid S which thereby releases the bolt 18. Therefore, upon closure of the second switch 22, the drive to the machinery will be immediately interrupted, but the interlock will not release the metal guard 14 until the end of the predetermined delay period.

Upon release of the lock bar 18, the circuit is now reset and can be operated again.

The machinery guarding device described above with reference to the drawings has been designed primarily for use with carding machines. To this end, the metal guard 14 will have a length sufficient to provide a guarding and access-preventing capability throughout the length of the part of the carding machine to be shielded. Side panels 24 and 25 may be attached to the supports 11 and 12 respectively, and have windows 26 through which the ends of the carding machine can be inspected.

While the described embodiment of machinery guarding device is primarily intended for use with carding machines, it should be understood that the invention is applicable in guarding and preventing access to machinery and parts thereof other than carding machines.

WHAT I CLAIM IS: 1. A machinery guarding device which comprises spaced-apart upright supports, a rotatable support extending substantially horizontally between said upright supports, a flexible metal guard mounted on said rotatable support so as to be movable, upon rotation of the latter, between a lowered machinery-guarding position and a rolled up machinery-access position, an interlock mounted on the guarding device for movement into locking engagement with said metal guard when the latter is in said machinery-guarding position, and inspection apertures formed in said metal guard to enable inspection of machinery to be guarded by the guarding device when the metal guard is in the machinery-guarding position.

2. A machinery guarding device according to claim 1, in which an electrical control system is connected to said interlock, for controlling the movement of the latter between locking and unlocking positions, and includes a first switch for initiating the movement of the interlock to the locking position, a second switch for initiating the movement of the interlock to the unlocking position, and a delay circuit operable to delay the movement of the interlock to the unlocking position following operation of said second switch.

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

Claims

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

metal guard 14, in that an opening 20 is formed in one of the horizontal stips of the guard 14 which comes into registry with the bar 18 when the guard 14 occupies the lowered guarding position. In the event that the bar 18 fails to register with the opening 20, it will not be possible for the machinery to be started-up. However, in addition, and as described in more detail below, operation of the electrical control system to effect unlocking of the bar 18 will involve a time delay between initiation of the unlocking operation and the actual unlocking movement of the bar 18.Upon initiation of the unlocking movement, the electrical control system will automatically cause stoppage of the machinery which is being protected, and the delay before unlocking of the bar 18 should be of sufficient duration to enable the motion of the machinery substantially to be arrested.

The electrical control system which will control the operation of the interlock, and also the machinery to be protected, is illustrated schematically in the circuit diagram of Figure 6. The control system comprises a relay R1 having contacts R1A, R1B and R1C, a solenoid S having contacts LS 1 and LS2, and first and second switches 21 and 22. Operation of the first switch 21 initiates the movement of the interlock to the locking position, and operation of the second switch initiates the movement of the interlock to the unlocking position.

A delay circuit is provided in the control system comprising a time delay R2 which is operable to delay the movement of the interlock to the unlocking position following operation of the second switch 22.

Closure of the first switch 21 energises the relay Rl so that contacts R1A, RIB and RIC are moved by the relay to closed positions. This causes energising of the solenoid S with consequent movement of the lock bar 18 to the locking position.

When the solenoid S has moved the lock bar

18 to the fully locked position, contacts LS1 and LS2 will be moved to the closed positions. However, in the event of the lock bar 18 failing to resister with opening 20, contacts LS1 and LS2 will not be closed, so that the machinery cannot be started-up.

When the contacts LS1 and LS2 are closed, this then holds the relay R1 closed, so as to complete the emergency stoD circuit

23 of the machinery to be protected, thereby allowing the machinery to be started-up.

Closure of the second switch 22 energises the time delay R2 which causes an associated contact R2A to open and an associated contact R2B to close for the duration of the time delay as set by the delay R2. This opens the emergency stop circuit 23, as relay Rl is now opened, and holds the solenoid S closed for the duration of the delay period. At the end of the delay period contact R2B then opens, thereby deenergising the solenoid S which thereby releases the bolt 18. Therefore, upon closure of the second switch 22, the drive to the machinery will be immediately interrupted, but the interlock will not release the metal guard 14 until the end of the predetermined delay period.

Upon release of the lock bar 18, the circuit is now reset and can be operated again.

The machinery guarding device described above with reference to the drawings has been designed primarily for use with carding machines. To this end, the metal guard 14 will have a length sufficient to provide a guarding and access-preventing capability throughout the length of the part of the carding machine to be shielded. Side panels 24 and 25 may be attached to the supports

11 and 12 respectively, and have windows 26 through which the ends of the carding machine can be inspected.

While the described embodiment of machinery guarding device is primarily intended for use with carding machines, it should be understood that the invention is applicable in guarding and preventing access to machinery and parts thereof other than carding machines.

WHAT I CLAIM IS: 1. A machinery guarding device which comprises spaced-apart upright supports, a rotatable support extending substantially horizontally between said upright supports, a flexible metal guard mounted on said rotatable support so as to be movable, upon rotation of the latter, between a lowered machinery-guarding position and a rolled up machinery-access position, an interlock mounted on the guarding device for movement into locking engagement with said metal guard when the latter is in said machinery-guarding position, and inspection apertures formed in said metal guard to enable inspection of machinery to be guarded by the guarding device when the metal guard is in the machinery-guarding position.
2. A machinery guarding device according to claim 1, in which an electrical control system is connected to said interlock, for controlling the movement of the latter between locking and unlocking positions, and includes a first switch for initiating the movement of the interlock to the locking position, a second switch for initiating the movement of the interlock to the unlocking position, and a delay circuit operable to delay the movement of the interlock to the unlocking position following operation of said second switch.
3. A machinery ' guarding device

according to claim I or 2, in which the metal guard is a flexible metal construction composed of horizontal metal strips hingedly connected together to enable the construction to be rolled-up to an access position and unrolled to a guarding position.
4. A machinery guarding device according to claim 3, in which said inspection apertures are formed in said metal strips.
5. A machinery guarding device according to claim 4, in which said inspection apertures are stamped out of said metal strips.
6. A machinery guarding device according to claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.