GB1566726A

GB1566726A - Machinery safety guards

Info

Publication number: GB1566726A
Application number: GB2238876A
Authority: GB
Original assignee: ASLEN D
Current assignee: ASLEN D
Priority date: 1977-03-25
Filing date: 1977-03-25
Publication date: 1980-05-08

Description

(54) MACHINERY SAFETY GUARDS (7l) I, DOUGLAS ERNEST ASLEN, a British Subject of 16 Pinfold Lane, Romiley, Cheshire, do hereby declare the invention, oKr 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 wd by the following statement: lie invention concerns machinery safety @@@@@ds and has more particular, though not exciusive, reference to guards for machines which employ a rotating cutter or like tool xhting about a vertical axis, such as milling machines of drilling machines.

It is knows in the art to provide a guard for a vertical drilling machine which com pastes a part-cylindrical, transparent shield intended, when in an operative position, to be generally coaxial with the drill bit, the shield being adjustable automatically in the axial direction of the bit to maintain contact with the workpiece, or support thereof, as the drilling head moves down. Such guards as aforesaid are adapted to be moved away f-I the drill bit, for inspection or other purposes. In one arrangement the shield is pivotally mounted in the upper region there af so as to be pivotal upwardly and away from the workpiece about an horizontal axis extending transversely of the drill head axis. In another arrangement the shield is hinged to a body part for pivotal movement about an axis parallel to the drill head axis.

The structures include a spring means adapted to hold the shield in an operative or an inoperative position, as required, the spring means in some instances passing through an over-centre position as the shield moves between its operative and inoperative positions.

With the structures as aforesaid, due to m advertence or otherwise, the shield can be kft in an inoperative position whilst the dnliing operation proceeds, with consequen i risic risk of inapt to the operator.

There is described and illustrated in our coPpending Application No. 22389/76 (Serial No. 1,5727) of even date berewhh a incry Xty guard which comprises a au tubular guard body adapted to be mounted on a non-rotatable part of a drilling machine or the like in generally coaxial relationship with the tool to be carried by such machine and a sleeve slidably mounted on the said body and freely movable in the axial direction thereof, the sleeve being transparent, at least in part, to make visible the region of the drilling tool.

In the safety guard disclosed in our copending Application aforesaid, the sleeve is slidable to an inoperative position whereat such sleeve overlies the guard body, and such sleeve and body are removable from a mounting ring secured to the barrel of the drilling machine to facilitate drill bit change, there being a ball catch or corresponding connection between the guard body and the mounting ring and the body and sleeve being similarly slotted to facilitate removal of the guard in the presence of a drill bit.

Whilst, with the safety guard of our Co- pending Application aforesaid, the guard sleeve will automatically assume an operative position relative to the guard body, and thus inadvertent use of the drilling machine with the sleeve out of position will be avoided, if the guard is removed for, say, drill bit replacement, the drilling operation can be re-started in the total absence of the guard.

The object of the invention is to provide a means whereby the correct positioning of the guard is a pre-requisite to drilling or like machine operation, so that potentially dangerous situations might be avoided.

According to the present invention there is proposed a machinery safety guard having separable parts and switch means, operable by the said separable parts when in a requisite relative disposition consistent with an operative condition of the guard, to maintain an electrical circuit of which the said switch means forms part, wherein the separable parts comprise a guard body and a mounting ring with which the guard body is releasably engageable and having said switch means thereon positioned for operation by said guard body on engagetnent thereof with the mounting ring.

The invention will now be described further. by way of example only, with reference to the drawing filed with the Provisional Specification in which: Fig. 1 is a broken perspective view, from one side and below, of a machine guard having a guard body which is separable from a fixed mounting ring therefor; Fig. 2 is a diagrammatic section of a part of Fig. 1, shown to a larger scale.

Referring now to Figs. 1 and 2, a guard 11 for a drilling machine comprises a mounting ring 12 having a split collar 13 for securing the ring in position on the quill or barrel 14 of the drilling machine, a guard body 16 releasably engageable with the said mounting ring 12, and a guard sleeve 17 captively mounted on the said body 16 and slidable axially thereof.

The mounting ring 12 has a radially inwardly directed flange at its upper end to define a shoulder 12a against which the upper end of the guard body 16 abuts when such body is in position relative to the mounting ring, and ball catches 18 are provided at spaced intervals about the periphery of the mounting ring, the ball catches 18 extending inwardly of the ring for co-operation with a peripheral groove 19 adjacent the top of the body to hold such body in the ring. The guard body 16 and guard sleeve 17 have breaker bars 16a, 17a respectively extending longitudinally thereof, and the guard sleeve 17 has transparent panels 21 to provide ready visibility to the~interior thereof.

Guide slits 22 are provided in the guard sleeve 17 to receive slide pins 23 carried by the body 16, such slits 23 being inclined relative to the axial direction of the guard so that relative movement between the guard body 16 and sleeve 17 in the axial direction thereof is accompanied by a relative rotation therebetween.

Both the guard body 16 and the guard sleeve 17 are slotted as at 16b, 17b respectively, to facilitate removal of the body and sleeve from a drilling head in the presence of a drill bit, not shown.

The guard structure shown in Figs. 1 and 2 is described in greater detail in the Specification of our co-pending Patent Application No. 22389/76 (Serial No. 1,566,727) aforesaid, and further description thereof is not thought necessary.

-In accordance with the present invention, a switch means, is provided which is sensitive to the relative positions of the mounting ring 12 and the guard body 16, such switch means being operable by the guard body 16 when the same is correctly positioned for support by the mounting ring 12.

Thus, referring now more particularly to l'ig. 2, a micro-switch 24 is provided adiacent to the collar 13, and the contact 24a of such micro-switch is positioned in alignment with a stepped hole 26 in the radially inwardly directed flange at the top of the mounting ring, there being a slave contact 27 of T-shaped longitudinal section located within the stepped hole 26, such slave contact 27 being engageable with the switch contact 24a and protruding from the shoulder 12a for abutment by the annular end face of the guard body 16 when engaged with the mounting ring 12 at a position consistent with an assembled condition of the guard structure.

Suitable resilient means, say a helical compression spring, not shown, will be interposed between the underside of the head of the slave contact and the shoulder formed by the stepped bore in the flange.

The switch means conveniently comprise a micro-switch; and is included in the electrical circuit of the drilling machine in such manner as to prevent operation of the machine except when the switch is "made".

In use, with the guard body engaged with the mounting ring, the annular end face of such body engages the lower end of the slave contact and such slave contact, in its turn, operates the switch, maintaining such switch in its operative state whilst the guard body remains in position. On removal of the guard body, the switch is released, and the circuit of which it forms a part is broken, thus preventing starting of the machine.

The invention is also applicable to a machinery guard having a pivotal shield.

The invention is not limited to the use of switch means as embodied in the arrangement specifically described and illustrated, since alternatives will readily present themselves to one skilled in the art. Thus, for example, two of the ball catches 18 where by the guard body 16 is releasably engageable with the mounting ring 12, or two further ball catches or contacts, provided specifically for the purpose, may form spaced contacts in an electrical circuit, the catches or contacts being electrically insulated froF the mounting ring 12 and being electrically connected via the guard body, thus to complete the electrical circuit, when such guard body is in position in the mounting ring.

WHAT I CLAIM IS: 1. A machinery safety guard having separable parts and switch means, operable by the said separable parts when in a requisite relative disposition consistent with an operative condition of the guard, to maintain an electrical circuit of which the said switch means forms part, wherein the separable parts comprise a guard body and a mounting ring with which the guard body is releasably engageable and having said switch means thereon positioned for operation by said guard body on engagement thereof with the mounting ring.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The invention will now be described further. by way of example only, with reference to the drawing filed with the Provisional Specification in which: Fig. 1 is a broken perspective view, from one side and below, of a machine guard having a guard body which is separable from a fixed mounting ring therefor; Fig. 2 is a diagrammatic section of a part of Fig. 1, shown to a larger scale. Referring now to Figs. 1 and 2, a guard 11 for a drilling machine comprises a mounting ring 12 having a split collar 13 for securing the ring in position on the quill or barrel 14 of the drilling machine, a guard body 16 releasably engageable with the said mounting ring 12, and a guard sleeve 17 captively mounted on the said body 16 and slidable axially thereof. The mounting ring 12 has a radially inwardly directed flange at its upper end to define a shoulder 12a against which the upper end of the guard body 16 abuts when such body is in position relative to the mounting ring, and ball catches 18 are provided at spaced intervals about the periphery of the mounting ring, the ball catches 18 extending inwardly of the ring for co-operation with a peripheral groove 19 adjacent the top of the body to hold such body in the ring. The guard body 16 and guard sleeve 17 have breaker bars 16a, 17a respectively extending longitudinally thereof, and the guard sleeve 17 has transparent panels 21 to provide ready visibility to the~interior thereof. Guide slits 22 are provided in the guard sleeve 17 to receive slide pins 23 carried by the body 16, such slits 23 being inclined relative to the axial direction of the guard so that relative movement between the guard body 16 and sleeve 17 in the axial direction thereof is accompanied by a relative rotation therebetween. Both the guard body 16 and the guard sleeve 17 are slotted as at 16b, 17b respectively, to facilitate removal of the body and sleeve from a drilling head in the presence of a drill bit, not shown. The guard structure shown in Figs. 1 and 2 is described in greater detail in the Specification of our co-pending Patent Application No. 22389/76 (Serial No. 1,566,727) aforesaid, and further description thereof is not thought necessary. -In accordance with the present invention, a switch means, is provided which is sensitive to the relative positions of the mounting ring 12 and the guard body 16, such switch means being operable by the guard body 16 when the same is correctly positioned for support by the mounting ring 12. Thus, referring now more particularly to l'ig. 2, a micro-switch 24 is provided adiacent to the collar 13, and the contact 24a of such micro-switch is positioned in alignment with a stepped hole 26 in the radially inwardly directed flange at the top of the mounting ring, there being a slave contact 27 of T-shaped longitudinal section located within the stepped hole 26, such slave contact 27 being engageable with the switch contact 24a and protruding from the shoulder 12a for abutment by the annular end face of the guard body 16 when engaged with the mounting ring 12 at a position consistent with an assembled condition of the guard structure. Suitable resilient means, say a helical compression spring, not shown, will be interposed between the underside of the head of the slave contact and the shoulder formed by the stepped bore in the flange. The switch means conveniently comprise a micro-switch; and is included in the electrical circuit of the drilling machine in such manner as to prevent operation of the machine except when the switch is "made". In use, with the guard body engaged with the mounting ring, the annular end face of such body engages the lower end of the slave contact and such slave contact, in its turn, operates the switch, maintaining such switch in its operative state whilst the guard body remains in position. On removal of the guard body, the switch is released, and the circuit of which it forms a part is broken, thus preventing starting of the machine. The invention is also applicable to a machinery guard having a pivotal shield. The invention is not limited to the use of switch means as embodied in the arrangement specifically described and illustrated, since alternatives will readily present themselves to one skilled in the art. Thus, for example, two of the ball catches 18 where by the guard body 16 is releasably engageable with the mounting ring 12, or two further ball catches or contacts, provided specifically for the purpose, may form spaced contacts in an electrical circuit, the catches or contacts being electrically insulated froF the mounting ring 12 and being electrically connected via the guard body, thus to complete the electrical circuit, when such guard body is in position in the mounting ring. WHAT I CLAIM IS:

1. A machinery safety guard having separable parts and switch means, operable by the said separable parts when in a requisite relative disposition consistent with an operative condition of the guard, to maintain an electrical circuit of which the said switch means forms part, wherein the separable parts comprise a guard body and a mounting ring with which the guard body is releasably engageable and having said switch means thereon positioned for operation by said guard body on engagement thereof with the mounting ring.

2. A machinery safety guard as claimed

in claim 1, wherein the switch means comprises a micro-switch mounted on said mounting ring and a slave contact located on said guard body and positioned so as to cooperate with said micro-switch when said guard body is in engagement with the mounting ring.

3. A machinery safety guard as claimed in claim 1 or claim 2 wherein the guard body and the mounting ring are releasably engageable by ball catch means arranged in spaced disposition peripherally of the said body and ring.

4. A machinery safety guard as claimed in claim 3, wherein the switch means is defined, in part, by adjacent ones of such ball catch means, such adjacent ball catch means being electrically insulated from the separable part in which the same are mounted and forming spaced contacts in an electrical circuit containing the switch means, the other of the separable parts being adapted electrically to connect the said adjacent ball catch means when said separable parts are mutually engaged.

5. A drilling or like machine including a machinery guard as claimed in any one of the preceding claims, said mounting ring being secured to the said machine adjacent the machine tool to be guarded against in a fixed position relative thereto, and said guard body being movable relative thereto, the switch means being connected with the electrical drive circuit of the machine and the said drive circuit being adapted and arranged, when broken, to prevent operation of the machine.

6. A machinery safety guard as claimed in claim 1, and having switch means substantially as hereinbefore described and as illustrated in Figures 1 and 2 of the drawing accompanying the Provisional Specification.

7. A drilling or like machine including a machinery safety guard as claimed in claim 6.