Closing ring applicator tool for open head drums

Abstract

A closing ring applicator tool 100 comprising a set of grippers 28 (see figure 3) configured to engage a drum closing ring 10 at spaced intervals around the outer circumference of the ring 10, the gri

Description

[0001] This invention concerns a tool used to assist in fitting closing rings to open-head drums (industrial containers). In an open head drum, one end of the finished drum body is left open (the "open head”), and a removable lid is fitted across this opening to enclose the drum contents. A rim of the lid is secured to an end chime (i.e. a circumferential flange or lip) surrounding the open end of the drum body. For this purpose, the closing ring has a channel-shaped cross-section, open in the radially inwardly facing direction. A circumferential break in the ring forms two adjacent ends, which can be drawn towards each other and then secured, commonly by a toggle-type latch mechanism. The closing ring can thus be fitted over the rim of the lid and the drum body end chime. The latch mechanism is then operated to draw the ends of the closing ring together and secure them. This clamps the rim of the lid against the drum body end chime around their entire circumference. When desired, the end user can operate the latch mechanism to open the closing ring and remove the drum lid.

[0002] A gasket is usually fitted to seal the joint between the end chime and the lid rim. In some cases, e.g. for liquid-containing drums meeting UN certification requirements, the axial force required to energize the gasket (and hence the torque required to operate the closing ring lever mechanism) can be quite large. In automated production lines, drum fillers will therefore often use a power driven (e.g. pneumatic or hydraulic) press to axially compress the gasket between the drum lid and drum body and ease the operation of the closing ring latch mechanism. However, sometimes individual drums need to be closed by hand without a press or power assistance. This can require great physical effort, which is not only tiring, but also uncomfortable for the operator, because the drum body is difficult to grip. Strain injuries can result. There is also a danger of accidental injury to the operator because the latch mechanism operates with an overcentre action. Under a high applied torque, it can suddenly snap shut with great force.

[0003] The present invention aims to address some or all of these difficulties, by providing a closing ring applicator tool comprising a set of grippers which in use engage a drum closing ring at spaced positions around the outer circumference thereof, the grippers being inwardly movable towards one another substantially parallel to the plane of the drum closing ring so as to reduce its circumference, bring ends of the drum closing ring closer together, and ease closure of a latch mechanism of the drum closing ring. The drum closing ring when the latch mechanism is open has a larger diameter than the drum lid and drum end chime, to enable the drum closing ring to be slipped over the upper end of the drum body and positioned loosely around the drum end chime and lid rim. The inward movement of the grippers substantially parallel to the plane of the drum closing ring at spaced positions around its outer circumference bends the drum closing ring to a smaller diameter and forces it into contact with the drum end chime and lid rim. The drum closing ring, drum end chime, and / or the lid rim typically are profiled so that constriction of the drum closing ring about the drum end chime and lid rim results in a wedging action which cams the lid rim axially downward against the drum end chime, thereby compressing and energizing any gasket fitted in the joint between them into sealing engagement with them. The constriction of the drum closing ring by such inward movement of the grippers assists the constriction of the drum closing ring arising from closure of the latch mechanism, thereby reducing the torque required to close the latch mechanism.

[0004] The latch mechanism therefore can be closed (e.g. by hand) with reduced effort, without necessarily requiring the application of axial force or pressure on the drum lid by external means. In the absence of such axially applied force, there is no need for the tool to apply any counterbalancing reaction forces to the drum closing ring or drum body in the opposite axial direction. Engagement between the tool and the drum body / lid / closing ring assembly may thus be straightforward, as the radially inwardly directed forces applied by the grippers can counterbalance each other.

[0005] The number of grippers in the set may be greater than two. As the drum closing ring constricts, the geometry is such that normally there is only one point around its circumference (along its curving length) where there is no relative sliding movement between the drum closing ring and the drum end chime / lid rim in the circumferential direction. Depending upon the positions of the grippers relative to the circumferential break in the ring at the latch mechanism, the point where such sliding movement is absent is likely to be away from the latch mechanism, typically remote from the latch mechanism in an opposite region of the drum closing ring. The amount of sliding movement progressively increases away from that point along the circumference (curved length) of the ring in each direction towards the corresponding end at the latch mechanism. Without wishing to be bound by theory, using more than two such movable grippers is believed to further constrain the drum closing ring as it constricts, promoting the relative circumferential sliding movement between the drum closing ring and the drum lid and end chime. The drum closing ring is able to move radially inward more evenly along its circumferential length against the resistance of its wedging action on the drum end chime, gasket and lid rim; with less outward bowing between adjacent grippers. The drum closing ring is therefore able to maintain a more circular shape in plan as it moves inwards. This further reduces the pulling force required of the latch mechanism to draw the ring ends together and the corresponding torque required to close the latch mechanism.

[0006] Some or all the grippers may each comprise any one or more of: a roller, a linear bearing, a friction reducing facing, or a deflectable mounting, so that friction between the grippers and the closing ring is reduced as the closing ring moves in the circumferential direction.

[0007] The tool may comprise three grippers, one of which is actuated in use to move radially inward towards the other two, with these other two grippers remaining in radially and circumferentially fixed positions relative to each other in the tool. Such a tool can be mechanically simple, and yet capable of providing consistent and even radially inwardly directed pressure on each drum closing ring (i.e. all the grippers act with similar radially inward force).

[0008] The tool may comprise four grippers, for example two sets of two grippers, with each set engaging opposite segments of the drum closing ring.

[0009] These two sets of grippers in use may be moved diametrically towards one another and may be mounted to the tool so that one set is pivotable relative to the other set about an axis normal to the plane of the closing ring when received in the tool. The grippers may thereby be made self-adjusting to press evenly on the closing ring; with the tool and its actuating mechanism again being kept relatively simple.

[0010] The innermost position of the grippers when constricting the closing ring may be lockingly adjustable to adapt the tool to a range of lid / end chime diameters.

[0011] The tool may be configured so that in use one gripper or set of grippers may be placed on one side of the drum closing ring latch mechanism and another gripper or set of grippers placed on the other side of the drum closing ring latch mechanism, with an actuator operable to move the one gripper or set towards the other gripper or set and the grippers at substantially regular spacings around the circumference of the drum closing ring. A single actuator may thus be used to constrict substantially the entire circumference of the drum closing ring.

[0012] The inward movement of the grippers may be driven by a hand-actuated mechanism. This mechanism may be arranged to self-lock the grippers in a closed position to allow easy operation of the drum closing ring latch mechanism.

[0013] The inward movement of the grippers may be driven by any one or more of: a toggle mechanism, a nut and lead screw, or cam followers and a cam plate or cam plates.

[0014] To reduce the risk of accidental injury, the tool may be engageable with the closing ring latch mechanism to close it.

[0015] For improved safety, ergonomics, and / or ease of use, the tool may further comprise a handle to hold the drum body and lid assembly steady against force applied to the closing ring latch mechanism in use.

[0016] Movement of the grippers may be by a hand-actuated mechanism comprising a handle which is also used to apply a force to the closing ring latch mechanism to close it.

[0017] The invention and some of its further features and advantages may be further understood from the following description of illustrative embodiments, made with reference to the drawings, in which: FIG. 1 shows a closing ring loosely fitted around a drum lid and end chime, ready to be closed by hand; FIG. 2 shows an operator closing the closing ring by hand; FIG. 3 diagrammatically illustrates an operating principle of a tool according to the present invention; FIG. 4 shows a first example of a tool embodying the invention, engaged with a closing ring, ready to assist in closing it about a drum lid and end chime; FIG. 5 shows a second example of a tool embodying the invention, similarly engaged with a closing ring on a drum body and drum lid, in readiness for operation; FIG. 6 is a more detailed view of one of the grippers of the tool of FIG. 5 and its position against the outer circumference of the closing ring; FIG. 7 is a plan view of the tool, drum lid and closing ring of FIG. 5, again in readiness for operation, but with a removable part absent for clarity; FIG. 8 generally corresponds to FIG. 7, but viewed from the direction of arrow VIII in FIG. 7; FIG. 9 generally corresponds to FIG. 5, but shows the tool after a first step in its operation; and FIGs. 10 and 11 show a sequence of further steps in using the tool of FIGs. 5-9 to close the latch mechanism of the closing ring; FIG. 12 is a plan view showing the closing ring fully closed to secure the drum lid to the drum body, and the tool ready for release and removal, and FIGs. 13 and 14 show a third example of a tool embodying the invention, similarly engaged with a drum lid (the drum closing ring and drum body being omitted for simplicity).

[0018] FIG.l shows a drum closing ring 10 having a toggle-type latch mechanism 12 which can be closed to draw two relatively movable ends of the ring 10 together. In this way the drum closing ring 10 can constrict about an end chime and the rim of a removable lid, to secure the lid across the open end of an open head drum. The closing ring 10 is shown loosely fitted around the end chime (which is therefore not visible in FIG.l) of a drum body 14, and similarly around the rim of a removable drum lid 16. The latch mechanism 12 is therefore open, as is apparent not only by the loose fit of the drum closing ring, but also by the radially projecting position of the operating lever of the latch mechanism 12. The drum lid 16 has an inwardly depressed central or annular area 18, defining a shallow central plug with a side wall 20. This plug serves to centre the drum lid 16 in the open end (head) of the drum body 14. An annular flange extends radially outward of the side wall 20 to an outer annular edge of the lid 16, to comprise at least part of the rim of the lid. Like the drum end chime, this flange is at least partly covered by the drum closing ring 10 in FIG. 1 and therefore is not clearly visible. The drum end chime is typically an outwardly curled edge portion surrounding the open end of the drum body 14, the curl being formed from the material of the drum body’s sidewall. An axially compressible annular gasket may be interposed between the drum end chime and the rim of the drum lid 16, to seal between these and / or to seal with any separate linings which may be applied to the lid 16 and / or drum body 14.

[0019] The drum closing ring 10 has a channel-shaped cross-section, defining side walls which converge in a direction from radially inner, open side of the channel, towards the radially outer base of the channel. Therefore, when the latch mechanism 12 is closed to constrict the drum closing ring 10, the convergent side walls of the channel are drawn against the rim of the drum lid 16 on the one hand and the drum end chime on the other. This produces a wedging action which cams the rim of the drum lid 16 axially against the drum end chime to secure the lid 16 firmly in place. This wedging action may also compress and energize any interposed sealing gasket such as described above.

[0020] Where a highly effective seal is required, the axial force needed to compress the gasket can be large, making the closing ring latch mechanism 12 difficult to close by hand. FIG. 2 shows an operative 22 attempting to do so, using a tool improvised from a length of strong metal tubing 24. This is fitted over the operating lever of the latch mechanism 12 to increase the applied torque. However the physical effort required is still considerable, making the work strenuous and tiring. The high torque needed to move the operating lever may also cause the drum body 14 to move. The drum body 14 is difficult to grasp and steady using the operative’s other hand or other parts of their body, such as the knees. The whole operation is therefore ergonomically awkward, carrying a risk of injury. The metal tubing 24 keeps the operative’s hands out of the immediate vicinity of the latch mechanism 12 as it closes. But the tubing 24 can become jammed when the latch mechanism 12 snaps shut. Freeing it requires further effort and again carries a risk of pinch injuries.

[0021] FIG. 3 on the left side diagrammatically illustrates in plan view the opened closing ring 10 loosely fitted to the drum lid 16, as a first stage in securing and sealing the lid 16 to the drum body 14 (not visible in FIG. 3). The ends 10a of the ring 10 are relatively widely spaced apart, whereby the ring diameter is sufficiently enlarged for the ring to be slipped over the rim 16a of the lid 16 and the drum end chime below. The radially inwardly facing channel inside the closing ring 10 thus may be loosely engaged about the drum lid rim 16a, the drum end chime, and any interposed gaskets, liners, and the like. The latch mechanism is omitted from FIG. 3 for clarity / simplicity.

[0022] The right side of FIG. 3 represents a later stage in the closing ring application process (as symbolically indicated by the transition arrow 26), when using a tool embodying the present invention. The outer circumference of the closing ring 10 is engaged at spaced positions by a set of grippers 28. These are inwardly movable towards one another substantially parallel to the plane of the drum closing ring 10, to reduce its overall circumference (including the gap between the ring ends 10a straddled by the latch mechanism 12). This movement is symbolically indicated by the smaller arrows 30 on the right side of FIG. 3. The ends 10a of the drum closing ring are thereby brought closer together, making it easier to close the latch mechanism 12 of the drum closing ring 10. The radially outwardly tapering channel inside the latch ring 10 is thereby wedged over the rim 16a of the drum lid 16 and the drum end chime below, driving the end chime and lid 16 axially towards one another and into firm engagement. A sealing gasket suitably interposed between the drum end chime and the drum lid rim 16a may thus be energised to provide a fluid seal between the lid 16 and the drum body 14.

[0023] The number of grippers used may be sufficient to prevent the portions of the closing ring 10 between circumferentially adjacent grippers from bowing outwardly to a significant degree, as the grippers constrict the ring 10 and force its channel profile over and onto the lid rim 16a and drum end chime. The closing ring 10 thereby constricts evenly onto the lid rim 16a and drum end chime. The closing ring 10 is thereby also constrained to slide in the circumferential direction relative to the lid rim, so that the ends 10a of the closing ring 10 may be brought still closer together. There may thus also be relative movement between the closing ring 10 and the grippers 28 in the circumferential direction of the ring. To reduce friction between the closing ring 10 and the grippers 28, some or all the grippers may comprise a roller rotatable about an axis parallel to the axis of the drum body and drum lid, or other friction reducing arrangements as described elsewhere in this document. The higher the number of grippers 28, the shorter the arcuate distance between them, and therefore the greater the constraint on the closing ring 10. However, the more grippers, the greater the mechanical complexity of the tool. Three or four grippers have been found to provide a hand-operated tool that substantially reduces the torque required to close the closing ring latch mechanism 12.

[0024] Three grippers e.g. spaced substantially evenly around the circumference of the drum lid and closing ring can be actuated to provide consistent and substantially equal radially inwardly directed pressure on the closing ring in a simple manner, e.g. by moving one of the grippers radially inward towards the other two. These other two grippers may remain in radially and circumferentially fixed positions relative to each other in the tool, but the tool as a whole substantially selfcentres over the drum lid and end chime.

[0025] Similarly, consistent and substantially equal radially inwardly directed pressure on the closing ring is achievable in a simple manner using four grippers, by providing the gripers in two sets of two, each set engaging an opposite segment of the closing ring. The grippers may again be substantially evenly circumferentially distributed. The two sets of gripers in use are moved diametrically towards one another and are mounted to the tool so that one set is pivotable relative to the other set about an axis equidistant from the pivoting rollers and normal to the plane of the closing ring when it is received in the tool. All four grippers may thereby apply substantially equal inwardly directed forces to the closing ring, with the tool as a whole being substantially self-centring. Further details of such tools are explained below with reference to FIGs. 4-14.

[0026] FIG. 4 shows a tool 100 comprising three co-planar arms 32a, 32b, 32c, joined at a central point, from which the arms extend radially outward at substantially equal angles to each other. Ends of the arms extend beyond the outer circumference of a closing ring 10 loosely fitted to a drum body 14 and drum lid 16, so that the tool rests on and is supported by the closing ring 10. (FIG. 4 shows the closing ring 10 in the closed condition, as indicated by the position of the latch mechanism 12. But the tool is shown in its "open” position, ready to engage and constrict an open closing ring). The arms 32a, 32b are each of fixed length. They carry respective grippers at their radially outer ends. Each gripper comprises a roller 28a, 28b, journalled to a respective depending stub axle 34a, 34b. The third arm 32c has a radially outer portion comprising a shaft 36a which is telescopically slidable in a radially inwardly positioned guide tube 38. A threaded portion of the shaft 36a carries a toggle link nut 40a. The effective length of the third arm 32c may thus be adjusted by turning the shaft 36a using a spanner, torque wrench or other suitable tool (not shown) engaged with a drive formation 42 at a free outer end of the shaft 36a. The tool 100 may thereby be adjusted e.g. to fit drum lids, drum end chimes and / or lid gaskets of different sizes, e.g. from different drum makers. To set up the tool 100, the tool actuating mechanism may be moved to the "closed" position (as further described below), and a torque wrench then used on the drive formation 42 to tighten the tool to specified torque at which the ring 10 is acted on by the grippers to generate a radially inward force for easing the operation of the ring latch mechanism 12 to a desired degree. The thus-adjusted tool can then be opened to release it from the closing ring 10. When fitted to other drum bodies / drum lids / gaskets / closing ring assemblies of the same size, the tool 100 can then repeatedly apply substantially the same constricting force to those assemblies.

[0027] The shaft 36a also carries a mounting bush 44 carrying a stub-axle 34c, on which a third gripper comprising a roller 28c is journalled. The mounting bush 44 is rotatable on the shaft 36a to allow the above-described adjustment of the shaft 36a, but is prevented from moving axially outward along the shaft 36a by a stop collar 46. In use of the tool, the stub-axle 34c and roller 28c are positioned depending from the shaft 36a, or adopt this position under their own weight. Alternatively, the mounting bush 44 and / or stub shaft 34c may slide in a guide frame (not shown) attached e.g. to the toggle link nut 40a or to the guide tube 38, to prevent the stub-axle 34c from rotating relative to those components about the axis of the shaft 36a. Yet alternatively, the mounting bush 44 and / or stub shaft 34c maybe steadied on the upper rim of closing ring 10 by a stabilising plate or bracket (not shown) extending below the shaft 36a.

[0028] The tool 100 is closed against the closing ring 10 and released from the closing ring 10 by a suitable hand-powered actuating mechanism, e.g. a toggle mechanism 48a as shown in FIG. 4. The toggle mechanism comprises a fulcrum bracket 50 fixed to stand up from the guide tube 38. An operating handle 52 is pivotally mounted at one end to the top of the fulcrum bracket 50. A pair of toggle links 54 are pivotally connected at one end, one on either side, to the toggle link nut 40a. The other ends of the toggle links 54 are pivotally connected to the operating handle 52, close to the fulcrum bracket 50. Pulling on the operating handle 52 in the direction of arrow A thus draws the shaft 36a into the guide tube 38 with mechanical advantage, via the toggle links 54 and toggle link nut 40a. The gripper 28c can thereby be drawn towards the grippers 28a, 28b with considerable force, to constrict the closing ring 10 and ease operation of the closing ring latch mechanism 12.

[0029] As the closing ring 10 constricts about the lid rim 16a and drum end chime (not shown) to bring the ring ends closer together at the latch mechanism 12, the ring may slide circumferentially past the grippers 28a, 28b, 28c. Because the grippers are formed by rollers journalled on the stub-axles 34a, 34b, 34c, sliding friction between the grippers and the closing ring 10 is reduced. The manual effort needed to operate the handle 52 is thereby also reduced.

[0030] The pivot axis at the fulcrum bracket 50 may stand higher above the axis of the shaft 36a than does the pivot axis of the toggle links 54 on the toggle link nut 40a. The handle 52 may therefore operate with an overcentre action to lock the shaft 36a in the guide tube 38 when the gripper 28c has been moved fully radially inward, to lock the tool 100 closed about the closing ring 10. The operator then has both hands available to attend to closing the closing ring latch mechanism 12. The effort needed to do so is significantly reduced due to constriction of the closing ring 10 by the tool 100.

[0031] FIGs. 5-12 relate to another example of a tool embodying the present invention. FIGs. 5-7 show the tool 200 in its opened condition, in which the gripers have been moved outwardly away from one another. The tool 200 can therefore be loosely engaged over a closing ring 10 loosely fitted to an open-head drum body 14 and drum lid 16, so that the tool rests on and is supported by the closing ring 10. In this example the tool has four grippers 28a-28d, each again journalled on a respective stub axle 34a-34d, for rotation about axes parallel to the drum body / lid / closing ring axis; although other numbers and forms of gripper are also possible within the scope of the invention. As perhaps best seen in FIG. 6, each roller has a cylindrical operating surface 56 engageable with the outermost circumference of the closing ring 10. Each roller (gripper) 28a-d further comprises a guide flange 58 positionable below a lower rim 60 of the closing ring 10 and thus below the closing ring 10’s radially protruding profile. The guide flanges 58 therefore act to properly position the tool over the closing ring 10 and positively maintain the tool in the correct engagement as it closes against and constricts the closing ring 10. The rollers (grippers) shown in FIG. 3 are of similar form, although this is not essential to the invention. The guide flanges 58 do not need to transmit any reaction forces as the tool 100 or 200 closes on and constricts the closing ring 10, because the grippers act in opposition to each other substantially in the plane of the closing ring 10.

[0032] Returning to the tool 200 of FIGs. 5-12, a first pair of the grippers, 28a, 28b, is mounted to a first sub-frame 32d and a second pair of the grippers, 28c, 28d, is mounted to a second sub-frame 32e. A hand-operated actuating mechanism 48b is connected between the two sub-frames 32d, 32e, allowing them to be: (a) moved apart so as to open the tool for positioning and initial engagement over and around the loosely assembled drum lid 16 / closing ring 10 / drum end flange; (b) drawn towards each other whereby the grippers constrict the closing ring 10, energize any sealing gasket used to seal the drum lid 16 on the drum body 14, and ease operation of the closing ring latch mechanism 12; and then (c) moved apart once more to release the tool from the thus closed and sealed drum. In this way, the actuating mechanism 48b of tool 200 is analogous to the operating mechanism 48a of the tool 100, which draws the gripper 28c in FIG. 4 towards the grippers 28a, 28b and then releases it again.

[0033] The actuating mechanism 48b of the tool 200 comprises a guide tube 38 in which a rod 36b is telescopically slidable. Neither the guide tube 38 nor the sliding rod 36b of the actuating mechanism 48b need be of round cross-section, because these two parts need not be relatively rotatable about their common axis. Initial tool set-up and / or adjustment to different drum lid etc. diameters can be provided elsewhere in the tool, e.g. in connection with the first sub-frame 32d. For example, a spigot and socket (or similar linearly slidable interfitting) connection 62 (FIG. 7) may be provided between the first sub-frame 32d and the guide tube 38 (or other relevant part of the actuating mechanism 48b), axially aligned with the guide tube 38. An adjustment bolt or screw 64 controls the axial distance that the spigot penetrates the socket. The adjustment bolt or screw 64 may therefore be adjusted and set e.g. using a torque wrench or other suitable tools, as described above in relation to the drive formation 42 of FIG. 4 and for the same purposes. Because there is no need for relative rotation between the guide tube 38 and the sliding rod 36b, the toggle link nut 40a of FIG. 4 may be replaced by a toggle link boss 40b fixed to the protruding end of the sliding rod 36b. To save weight and material, both the guide tube 38 and the sliding rod 36b may be hollow, e.g. slidably interfitting, tubes of e.g. box section. The centre of the second sub-frame 32e is pivotally connected to the free end of the sliding rod 36b, e.g. pivotally connected to the toggle link boss 40b (see FIG. 8). The sub-frame 32e is thereby arranged to pivot on an axis parallel to the axes of the stub axles 34c and 34d. It therefore acts like a whippietree, to even out the forces applied to the closing ring 10 by the actuating mechanism 48b and grippers (rollers) 28c, 28d. Hence the corresponding reaction forces applied by the actuating mechanism 48b via the first sub-frame 32d and the grippers (rollers) 28a, 28b may also be more even.

[0034] In this illustrative example, the actuating mechanism 48b comprises a fulcrum bracket 50 (FIG. 6), fixed to stand up from the guide tube 38. A toggle lever 52a is pivotally mounted at one end to the top of the fulcrum bracket 50. A pair of toggle links 54 are pivotally connected at one end, one on either side, to the toggle link boss 40b. The other ends of the toggle links 54 are pivotally connected to the toggle lever 52a, close to the fulcrum bracket 50. The actuating mechanism 48b thus generally resembles the actuating mechanism 48a of FIG. 4. The pivot axis at the fulcrum bracket 50 may again stand higher above the axis of the sliding rod 36b than does the pivot axis of the toggle links 54 on the toggle link boss 40b. This allows an overcentre action to lock the tool 200 closed about the closing ring 10, again in the manner and for the purposes explained above in relation to the tool 100 of FIG. 4.

[0035] As shown in FIGs. 5 and 9, the tool 200 further comprises an actuating handle 52b removably receivable in an axial socket 68 at the free end of the toggle lever 52a (or otherwise similarly removably connectable to the toggle lever 52a). The empty socket 68 without the actuating handle 52b is shown in FIGs. 7,10, 11, and 12. When thus removed and as shown in FIG. 10, the actuating handle 52b can be turned 90 degrees about its long axis and then pivotally re-attached to the remainder of the tool 200 by inserting a projecting pivot pin 69 through a transverse hole 70 formed in the end of the actuating handle 52b which was formerly received in the socket 68. The actuating handle 52b has a roller 72 rotatably mounted to it or carries another suitable transverse projection. The pivot pin 69 is fixed to the tool 200 at a suitable position (e.g. co-axially above the gripper (roller) 28d) and the actuating handle 52b is configured so that when it is mounted on the pivot pin 69, the roller or transverse projection 72 can depend alongside and outwardly of the projecting end of the operating lever 12a of the opened latch mechanism 12. Manually rotating the actuating handle 52b in the clockwise direction on the pivot pin 69 as shown in FIG. 11 then presses the roller or transverse projection 72 against the latch mechanism operating lever 12a with mechanical advantage, to easily close the latch mechanism 12 even if, despite the constriction of the closing ring 10 by the tool 200, quite a high torque on the operating lever 12a is still needed to fully close the closing ring 10 (e.g. if high force needs to be applied to compress and energize a sealing gasket interposed between the rim 16a of the drum lid and the underlying drum end chime).

[0036] The tool 200 may be fitted with a steadying handle 74 used to counteract the torque applied to the actuating handle 52b by the operator 22 and thereby steady the tool 200 and drum. For example, the steadying handle 74 may be provided at a suitable position to be comfortably grasped in the operator 22’s other hand, such as projecting co-axially upwards from the gripper (roller) 28a. Thus in FIG. 11 the operator 22 is shown applying a pulling force to the actuating handle 52b with their right hand, and a pushing force to the steadying handle 74 with their left hand, to close the closing ring latch mechanism 12. Both user's hands are kept well clear of the latch mechanism's operating lever 12a in the process, so that there is no risk of pinch injuries if the latch mechanism 12 suddenly snaps shut. FIG. 12 shows the closing ring latch mechanism fully closed, whereby the closing ring 10 is fully installed about the drum body 14 and drum lid 16. The actuating handle 52b has been removed from the pivot pin 69, ready for reinsertion into the socket 68 for operation of the toggle lever 52a, to release the tool 200 from the drum closing ring 10.

[0037] Features described above in relation to one embodiment may be used in another embodiment. For example, a removable actuating handle and / or a steadying handle like those described with reference to FIGs. 5-12 may be used in embodiments as described with reference to FIG. 4. In any of the described embodiments, separate manually operated handles or levers may be provided for on the one hand moving the grippers to constrict and release the closing ring, and on the other hand for applying increased force on the latch mechanism operating lever to close it. Different features of equivalent function in the various described embodiments may be substituted or exchanged for one another. For example, the adjustment bolt or screw mechanism and non-rotating sliding rod and toggle link connection boss described in relation to FIGs. 5-12 may be used in tools otherwise as described in relation to FIG. 4 or modifications thereof. The mounting bush 44 may then for example be combined with the toggle link boss 40b. Any of those components and / or the stub axle 34c may be provided with a steadying base engageable with the upper rim of the drum closing ring or the drum lid, to steady the gripper manual actuation mechanism thereon. Or the adjustment shaft, toggle link nut, mounting bush and stop collar of FIG. 4 or suitable modifications thereof, can be substituted for the spigot and socket connection, adjustment bolt or screw, non-rotating sliding rod, and toggle link connection boss described with reference to FIGs. 5-12. In that case, the sub-frame 32e could be arranged to pivot on the mounting bush 44, about an axis parallel to the axes of the stub axles 34c and 34d. The sub-frame 32d could then be substantially rigidly fixed to the guide tube of the adjustment shaft.

[0038] Other hand-operated or power assisted actuating mechanisms could be used to move the grippers into and out of constricting engagement with the drum closing ring: for example, a screw and nut mechanism or mechanisms, an hydraulic cylinder (or cylinders, e.g. in a master / slavefs) arrangement), or cam plate(s) and cam followers. These mechanisms may be configured to be self-locking with the grippers in the closed position, like the previously described embodiments. The tool may have only two grippers or more than four grippers, instead of the three or four grippers previously described. Grippers other than rollers may be used, for example grippers provided with low-friction pads or pads mounted on linear bearings for movement tangential to the closing ring circumference, or grippers on mountings which are able to flex laterally to follow the contracting closing ring as it slides on the circumference of the drum lid / end chime, or grippers without any particular measures to reduce friction against the drum closing ring 10.

[0039] FIGs. 13 and 14 relate to a third example of a tool embodying the present invention. This tool 300 comprises three co-planar arms 32a, 32b, 32c, joined at a common point, from which the arms extend radially outward. Two of the arms 32a, 32b are each of fixed length. The third arm 32c is of variable length since it comprises part of the tool’s actuating mechanism 48c for moving the grippers relative to one another between their open and closed positions. The third arm 32c comprises an inner tube 38a over which an outer sleeve 36b is telescopically slidable. The inner tube 38a (or another suitable part of any of the tools described herein) may carry a support pad 75 or the like by which the tool 300 can be supported e.g. centrally on the drum lid 16. Downward pressure on the tool (e.g. as applied by the user, to close the grippers as further described below), may thereby also compress a sealing gasket between the drum closing ring and the drum end chime. This may make the grippers easier to close, making constriction of the ring and consequent easing of operation of the closing ring latch easier to achieve.

[0040] The outer sleeve 36b carries a bifurcated mounting bracket and pivot pin 76 at its radially outer end. An elongate sub-frame 32f (which may be curved as shown) is mounted at its centre on the pivot pin 76, to pivot in a plane parallel to that of the closing ring in use. A first pair of grippers 28a, 28b is mounted to the subframe 32f, one at each end. A second pair of grippers 28c, 28d is mounted to the radially outer ends of the arms 32a, 32b, one at each end. The grippers may comprise rollers or other friction reducing means bearing radially inwardly against the closing ring as the tool 300 is closed, as previously described. The geometry of the arms 32a-c and the sub-frame 32f is such that the four grippers 28a-d are substantially evenly spaced around the drum lid 16 and closing ring in use of the tool 300.

[0041] The actuating mechanism of the tool 300 further comprises a toggle lever 52c. This is pivotally mounted to the inner tube 38a by a bifurcated fulcrum bracket 78 which is fixed to extend laterally from one end of the toggle lever 52c. A bifurcated toggle link mounting bracket 80 is fixed further along the toggle lever, to extend in the same lateral direction as the fulcrum bracket 78. A toggle link pivot pin 82 extends through and laterally to either side of the outer sleeve 36b. A respective toggle link 54 is pivotally connected between the toggle link pivot pin 82 and a distal end of the toggle link mounting bracket 80, one on either side of the arm 32c. An elongate operating handle (not shown), similar to the handle 52b of the tool 200 described above, is removably receivable in or over the free end 68a of the toggle lever 52c. Pulling downwardly on the operating handle can thereby operate the actuating mechanism 48c to close the grippers 28a-c against the drum closing ring. The operating handle may have a roller or the like for engaging and closing the closing ring latch mechanism as described above regarding the example tool 200. The tool 300 is thus shown to comprise a pivot pin 69 by which the operating handle can be removably mounted to the tool for such use. The tool may also comprise a steadying 5 handle 74 as indicated in broken lines in FIGs. 13 and 14. This may be used as described above with reference to the example tool 200.

[0042] FIG. 13 shows the tool 300 in its closed position, in which the outer sleeve 36b has been drawn radially inward over the inner tube 38a by the actuating mechanism 48c, thereby shortening the third arm 32c and drawing the grippers 28a, 10 28b closer to the grippers 28c, 28d to constrict the closing ring. The gripers 28a, 28b are free to pivot relative to the grippers 28c, 28d via the pivot pin 76, so that all four grippers self-centre on the closing ring. FIG. 14 shows the tool in its open position, in which the outer sleeve 36b is slid radially outwards by the actuating mechanism 48c to lengthen the arm 32c and separate the grippers 28a, 28b, 28c, 28d from one another. 15 In the closed position, a notional line through the pivot axes at the ends of the toggle links 54 lies slightly below (closer to the drum lid 16 than) the pivot axis of the fulcrum bracket 78. The actuating mechanism 48c therefore operates with an overcentre action to lock the tool 300 onto the constricted closing ring when the tool 300 is in its closed state.

Claims

1. A closing ring applicator tool comprising a set of grippers configured to engage a drum closing ring in use at spaced positions around the outer circumference thereof, 5 the grippers being inwardly movable towards one another substantially parallel to the plane of the drum closing ring so as to reduce its circumference, bring ends of the drum closing ring closer together, and ease closure of a latch mechanism of the drum closing ring;in which some or all the grippers comprise any one or more of: a roller, a linear10 bearing, a friction reducing facing, or a deflectable mounting, so that friction between the grippers and the closing ring is reduced as the closing ring moves in the circumferential direction.

2. A closing ring applicator tool as claimed in claim 1, in which the number of grippers in the set is greater than two.15 3. A closing ring applicator tool as claimed in claim 1 or 2, in which the toolcomprises three grippers, one of which is actuated in use to move radially inward towards the other two, with these other two grippers remaining in radially and circumferentially fixed positions relative to each other in the tool.

4. A closing ring applicator tool as claimed in claim 1 or 2, in which the tool20 comprises four grippers spaced apart from each other around the circumference of the closing ring in use.

5. A closing ring applicator tool as claimed in claim 1 or 2, in which the tool comprises two sets of two grippers, with each set engaging opposite segments of the drum closing ring.25 6. A closing ring applicator tool as claimed in claim 5, in which the two sets ofgrippers in use are moveable diametrically towards one another and are mounted to the tool so that one set is pivotable relative to the other set about an axis normal to the plane of the closing ring when received in the tool.

7. A closing ring applicator tool as claimed in any preceding claim, in which the30 innermost position of the grippers when constricting the closing ring is lockingly adjustable.07 02 258. A closing ring applicator tool as claimed in any preceding claim, configured so that in use one of the grippers or a set of the grippers may be placed on one side of the drum closing ring latch mechanism and another of the grippers or set of the grippers placed on the other side of the drum closing ring latch mechanism, with an actuator5 operable to move the one gripper or set towards the other gripper or set and the grippers are at substantially regular spacings around the circumference of the drum closing ring.

9. A closing ring applicator tool as claimed in any preceding claim, in which the inward movement of the grippers is driven by a hand-actuated mechanism.10 10. A closing ring applicator tool as claimed in claim 9, in which the hand-actuatedmechanism is arranged to self-lock the grippers in a closed position.

11. A closing ring applicator tool as claimed in claim 9 or 10, in which the inward movement of the grippers is driven by any one or more of: a toggle mechanism, a nut and lead screw, or cam followers and a cam plate or cam plates.15 12. A closing ring applicator tool as claimed in any preceding claim, in which thetool is engageable in use with the closing ring latch mechanism to close it.

13. A closing ring applicator tool as claimed in claim 12, in which the tool further comprises a steadying handle to hold the drum against force applied to the closing ring latch mechanism in use.20 14. A closing ring applicator tool as claimed in claim 12 or 13, in which movementof the grippers is by a hand-actuated mechanism comprising an operating handle which is also used to apply a force to the closing ring latch mechanism to close it.

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