GB2053404A - Machinery guards - Google Patents

Abstract

A guard fore machine, such as a loom, which could eject an unrestrained part such as a shuttle, includes at least two movable elements OFG, IFG to cover an aperture, the outer element OFG being movable against a bias OS by hand pressure, and an inner element IFG being released by an interlock IC, IA with the outer element OFG on sufficient movement of OFG. The interlock prevents the outer element returning until the inner element is returned, e.g. by bias IS. The guard may be arranged as shuttle containment guard for a temple area TE of a loom and adjustably mounted (MP, FGF) on the sley cap SC to permit safe access to the reed RE while at all times ensuring that a shuttle deflected from raceboard RB is directed into a shuttle box SB. The movable guard can extend a fixed guard of similar bar form (OG', IG'). <IMAGE>

Description

SPECIFICATION Machinery guards This invention relates to guards for machines and more particularly but not exclusively to guards for machines which both prevent a moving machine part from trapping an operator and prevent parts of the machine emerging to injure an operator.

Machine guards fixed in place to prevent an operator touching a dangerous part are well known and are often required by law to perform in a specified manner. Such guards can also prevent a loose or broken part of the machine emerging to injure an operator. However it is often essential that an operator has access to a machine, e.g. to make adjustments or load work, and movable guards must be provided which permit this. While fixed guards are relatively easy to provide, movable guards are much more difficult to construct to give safe, reliable operation which is not so complex as to lead an operator to attempt to "defeat" or by-pass the guard. Generally such guards are lightly made to respond to operator contact but do not provide any real barrier as they would then become too massive.

It is an object of the invention to provide a machine guard movable to permit convenient access to a machine under safe conditions and which is effective to provide a barrier around the machine at least preventing unrestrained machine parts from emerging in a dangerous way.

According to the invention there is provided a machine guard for a machine access aperture including at least two movable guard elements biassed to a first position and movable to a second, access permitting, position and being effective in preventing unrestrained machine parts from emerging through the aperture, and an interlock for the elements to permit movement of a second element only after movement of a first element from a first stable, access restricting, position to a second unstable, access permitting, position to release the interlock and permit movement of the second element, the interlock also ensuring the return of the second element to its first, access restricting, position before the return of the first element to its first position, whereby on contact of the guard with an operator the guard is moved to not trap the operator.

The guard may be a guard for the shuttle area of a loom to contain an ejected shuttle and direct it to a shuttle box. The guard may include fixed guard elements extending from a movable guard element over an area where operator access is not needed.

The guard may also include a support bracket in which the two movable elements are mounted one in front of the other to swing under hand pressure, the first, outer, element including an interlock cam and the second, inner, a cam abutment for co-operation to permit the inner element to move only when the outer is sufficiently displaced and to prevent the outer element returning to the stable position until the inner element is returned. The interlock cam may be freely mounted and linked to the first elements by a "lost-motion" arrangement.

The machine may include means to deflect the outer element to release the interlock while the guard is close enough to fixed machine parts to otherwise trap an operator with the interlocked inner guard element.

When the machine is a loom the guard may be of substantial metal bars arranged around the shuttle path and generally parallel to the path in the temple region to move upwards and rearwards from the temple.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a general outline view of the shuttle area of a textile machine; Figure 2 is a detail view of part of the shuttle area of Figure 1 and including a guard according to the invention; Figure 3 shows a detail of an alternative interlock; and Figure 4 shows a detail of another interlock.

Figure 1 shows a general outline view of the shuttle area of a loom. Only those parts relevant to the description of the present invention are shown and these only in a general manner as their particular form is not crucial to the invention. A loom has a smooth raceboard RB along which a shuttle SH is propelled between shuttle boxes, one being shown at SB. The reed, RE, is supported to the rear of the sley cap SC and a warp of yarns extends through the reed under the sley cap, past the raceboard to a take up roller at the front of the loom (not shown). The shuttle provides the weft yarn and the loom operates in known manner to interlace the warp and weft yarns into a woven piece. To permit shuttles to be changed and attended to and warp yarns to be drawn-in access to the raceboard and reed area is needed by an operator.Access is also required to the temple area TE, the operator's shand resting on the temple plate.

The shuttle is not restrained to the loom during its passage from shuttle box to shuttle box. The size and speed of the shuttle are enough to produce a vary dangerous missile if the shuttle is deflected off the raceboard, as can easily happen during weaving.

Accordingly various guards have been proposed to protect operators from escaping shuttles.

Such guards have to meet conflicting needs.

The shuttle must be contained but easy operator access provided. The sley cap reed and raceboard move to and fro during weaving to approach closely to the temple plate TP. As the shuttle path is then close to the temple plate any guard must be interposed between the shuttle and the possible position of a hand on the plate but not create a risk of trapping such a hand or finger.

Figure 1 shows a guard which meets all requirements except that of finger or hand trapping on the temples, which must therefore be removed. The guard is made by welding steel rods, typically 5/1 6" (8 mm), to brackets, e.g. of steel rod, to form two guard members, an outer guard OG and an inner guard IG. The members are formed as shown in Figure 1, with curved brackets clear of the shuttle path, and fixed to the sley cap at guard fixings GF. The slotted brackets permit the guard to be adjusted to the optimum position for shuttle containment. In one arrangement with a shuttle 33 mm high and 42 mm thick running in the angle between the reed and raceboard the inner guard was 50 mm from the reed and 70 mm from the raceboard while the lower outer guard was 75 mm from the reed and 54 mm from the raceboard, which would clash with the temple at the front centre position of the sley.The guard can be made of other materials and dimensions if required provided it is robust enough to retain the shuttle.

To test the guard variously shaped ejection wedges, such as that shown at EW, were placed in the shuttle path at different positions. In all cases the shuttle was contained by the guard and directed safely into the shuttle box at the end of the raceboard.

However, temples are usually required for controlling the cloth width at the fell position and must be installed. The guard must therefore permit their use. Figure 2 shows a movable guard arrangement, particularly for the temple area, which maintains shuttle containment while permitting an operator access to the temple area and avoiding any risk of finger or hand trapping against the temple plate. The guard in Figure 2 replaces the fixed guard outwardly of each fixing GF. (The same references are used for parts common to Figures 1 and 2.) The movable guard embodying the invention and exemplified in Figure 2 has two pivoted finger guard elements OFG, IFG, interlocked to move only in a certain manner. The movable guard is preferably used with a modified form of the Figure 1 guard. The modified outer guard is OG' and the modified inner guard is IG'.

Each modified guard extends a short way beyond the slotted brackets and ends in a half-joint formed by cutting away the inner half of the rod.

The inner and outer finger guard elements, IFG and OFG respectively, are also cut away to mate with the modified guard at half-joints lHJ and OHJ respectively, extending the fixed rods towards the shuttle box. The half-joints are seen to be arranged so that the movable elements cannot swing forward of the fixed rods. The half-joints are strong enough to hold the movable elements against an ejected shuttle to direct it into a shuttle box.

The construction and operation of the movable guard are now described. A mounting plate MP and support flanges SF of any suitable form and material. are secured to sley cap SC by adjustable fixings FGF so that the inner and outer elements IFG and OFG can be aligned with the rods IG and OG respectively. Element OFG is pivoted in flanges SF on suitable curved arms to swing freely inwards and upwards towards the reed and sley cap. A spring OS biasses the element outwardly towards the outer guard OG'. At each pivot of OFG an interlock cam IC is provided securely positioned with respect to the element.

Element IFG is attached to an inner pivot rod IPR housed in bearings in the flanges SF. An interlock abutment IA is provided at each end of pivot rod IPR. Abutment IA is arranged to cooperate with interlock camlC. Element IFG is biassed outwardly by spring IS and an end stop ES on abutment IA limits the outward swing, in conjunction with contact with the fixed guard IF'.

With the movable guard as shown in Figure 2 the guard continues the line of the fixed guard and will direct any deflected shuttle into a shuttle box.

Inner guard element IFG is held in position by the interlock of abutment IA on cam IC, preventing swinging movement towards the reed, and by endstop ES, preventing swinging movement away from the reed.

If access to the reed or shuttle boxes is required when the loom is stopped (at either end as two guards are fitted) the operator can lift outer guard element OFG. The operator is not required to touch the reed or shuttle boxes when the loom is working. If more access is required than provided by lifting element OFG then when element OFG has been lifted to clear cam IC from abutment IA inner guard element IFG can be swung inwards, towards the reed. On release of elements OFG and IFG spring IS will swing element IFG into engagement with fixed guard IG' before cam iC can fall past abutment IA to allow outer element OFG to swing into engagement with fixed guard OG' by the action of spring OS.In this way it is not possible for the guard elements to wedge with element IFG in the lifted position and element OFG down, when a shuttle might be able to escape through the gap left.

In Figure 2 a further cam TC is shown on the temple TE. This is made of a durable compressed fabric reinforced resin bonded material, such as TUFNOL (R.T.M.), and is shaped to engage element OFG, when the sley is forward, to free the interlock of IC and IA. In this way an operator's hand on temple plate TP is not trapped under a locked guard element IFG as the sley moves towards the temple while the shuttle containment is maintained and wedging of the guard elements prevented. The cam TC will be effective as the temple is altered in position, for example for different cloth widths, as it is arranged to act across the full length of element OFG. Clearly the guard elements are of an adequate length to cope with the range of temple movement.

Figure 3 shows an alternative interlock to provide the same action as that described above.

The Figure is a view of the interlock only, other parts being similar to Figure 2. A pawl, IC', on the pivot of element OFG can engage a notch on a cam, IA', on pivot rod IPR. As shown, in the stable guard position preventing access, guard element IFG cannot rotate either way being trapped between the half-joint of rod IG', and the pawl IC'.

It will be apparent that when pawl IC' disengages cam IA' guard IFG can rotate, however element OFG cannot reach a stable position until pawl IC' can again engage the notch in cam IA', when guard IFG is in its stable position. Clearly other interlock forms and guard forms can be envisaged.

Figure 4 shows a further form of interlock including an extra element to extend the operating range of the guard. In Figure 4 elements similar to those described above have similar references.

The guard is mounted as before on sley cap SC by a mounting plate MP and flanges SF.

The inner and outer guard bars IFG, OFG are supported in bearings in flanges SF by respective pivot stub shafts IPS and OPS. Lock bushes LB secured by lock pins LP keep the stub shafts in place. Each lock bush LB has a lug, OIL and IIL respectively. An interlock catch ILC is trapped on the outer shaft OPS, between the bush and the flange, for free rotation on the shaft, subject to the interaction of lug OIL with peg OIP and stopscrew OSS. An extension OGE on the outer guard OFG is connected to a bias spring BS arranged to bias guard OFG to engage guard OG' using half-joints as described above.

The assembly just described is replicated at the remote end, not shown, of plate MP in the same manner as is shown in Figure 2, that with a reversed "handiing".

The action of the interlock is as follows. In Figure 4 the guard is in an intermediate position and being raised toward the fully open position allowing maximum access and also adequate temple clearance to prevent trapping of the operator. Movement onward toward the fully open position raises both guard elements IFG, OFG toward the sley cap SC. This action turns free catch ILC counter-clockwise (in the drawing) by the action of the lug OIL on peg OIP permitting lug IIL to swing beneath catchface CF. The tension in spring BS increases. On release from the fully open position inner guard element IFG moves under its own weight while outer guard element OFG is assisted by spring BS. Catch ILC does not initially restrict the movement of the inner element, even if face CF is riding on lug IlL, because of the "lost motion" between peg OIP and screw OSS.Once lug IIL is clear of face CF catch ILC will restrict movement of lug IIL and prevent significant movement of element IFG out of engagement with element IG' maintaining the shuttle guard form. As outer guard OFG moves toward element OG' lug OIL engages stop screw OSS to hold catch ILC in position.

With this arrangement, as with that in Figures 2 and 3, the outer guard element OFG must be raised before any movement of the inner guard can occur while the possibility of the guard elements jamming in the raised position must be reduced to a minimum. The form of the catch ILC, the free motion of the catch and the "lost motion" in its linkage with lug OIL all contribute to these requirements. Also the free motion of the catch reduces inertia effects when the loom is running while the "lost motion" produces later release and earlier re-engagement of the interlock.

The arrangements described above, provide a guard which is easily raised by contact with an operator's hand but cannot be left in an intermediate position reducing shuttle containment or obstructing its path.

The guard arrangement described above thus permits safe access by an operator to the temple area of a loom while maintaining complete containment of a deflected shuttle and avoiding the trapping of the operator against the temple when the sley moves forward.

Clearly other guard forms for the type of loom and for other textile machines with unrestrained parts can be envisaged and devised within the scope of the invention.

Claims (8)

1. A machine guard for a machine access aperture including at least two movable guard elements biassed to a first position and movable to a second, access permitting, position and being effective in preventing unrestrained machine parts from emerging through the aperture, and an interlock for the elements to permit movement of a second element only after movement of a first element from a first stable, access restricting, position to second unstable, access permitting, position to release the interlock and permit movement of the second element, the interlock also ensuring the return of the second element to its first, access restricting, position before the return of the first element to its first position, whereby on contact of the guard with an operator the guard is moved to not trap the operator.

2. A guard according to Claim 1 for the shuttle area of a loom to contain an ejected shuttle and direct it to a shuttle box.

3. A guard according to Claim 1 or Claim 2 and including one or more fixed guard elements extending from movable guard elements over an area where operator access is not needed.

4. A guard according to Claim 1 or Claim 2 or Claim 3 including a support bracket in which the two movable elements are mounted one in front of the other to swing under hand pressure, the first, outer, element including a cam and the second, inner, a cam abutment for co-operation to permit the inner element to move only when the outer is sufficiently displaced and to prevent the outer element returning to the stable position until the inner element is returned.

5. A guard according to any one of the preceding claims in which the interlock is moved by the first element through a lost motion linkage.

6. A machine guard according to any one of the preceding claims and means on the machine to deflect the outer element to release the interlock while the guard is close enough to fixed machine parts to otherwise trap an operator with the interlocked inner guard element, the guard moving with an operating machine part.

7. A loom machine guard according to any one of the preceding claims of substantial metal round rods or other bars arranged around the shuttle path and mounted generally parallel to the path in the temple region for movement upwards and rearwards from the temple.

8. A machine guard substantially as herein described with reference to Figure 2 or Figure 3 or Figure 4 or Figures 1 and 2 or 1 and 3 or 1 and 4 of the accompanying drawings.