GB2121001A - Packaging film dispensers - Google Patents

Abstract

In a packaging film dispenser a roll of film mounted on a core tube is supported to rotate as film is dispensed and an adjustable braking effort is applied in the radial direction to the inside of the core tube to enable tensioning of the film paid off from the roll. The braking means (30) may include two coacting brake members (35 and 32), member (35) being made fast frictionally to the inside of the core tube for rotation therewith by an expansible friction member (31) carried by the member (35). Brake member (32) is fixed against rotation to a stationary part (14) of the dispenser. A handle (15) of the dispenser is effective to expand the friction member (31) into tight contact with the core tube and to control the braking effort established by the coacting brake members (32,35), and handle (16) is for manipulating the entire dispenser. Alternatively, member (32) may be omitted and member (35) may be non-rotatably held in the dispenser with friction member (31) or a flexible and expansible skirt as part (35b) adjustably bearing against tube to control rotation thereof. The roll may be held between two horizontal arms of an upstanding three-sided frame, the upright arm carrying the handle (16), the handle (15) and the braking means (30) being carried on the upper horizontal arm, and the plug (19) on the lower horizontal arm. <IMAGE>

Description

SPECIFICATION Packaging film dispensers The present invention relates to packaging film dispensers, and more particularlyto dispensers having improved mechanism for controlling film tension.

Palletised loads of objects such as cartons are commonlywrappedwith polymeric stretch film applied in the manner of a bandage around the load. The film is dispensed from a roll thereof and pulled taut as it is being wrapped around the load, automatically in the case of a powered wrapping machine or manually in the case of a hand dispenser. Failure to tension the film adequately can lead to insecu rely wrapped loads.

Film rolls are commonly supplied on cardboard core tubes. In many dispensers it is the practice to compress the core tubes axially between end stops, at least one ofwhich is held stationary, to establish a frictional resistance to rotation ofthe roll, thus to control tension in the film being dispensed. In other dispensers the core tube is loaded axially and used as a force transmitter to a brake device which, when appropriately loaded, retards rotation of the roll.

I have noticed that roll braking means which demand axial loading of a core tube can prove unreliable. For example, core tubes loaded axially can give lengthwise and thus shorten slightly. Braking effort and thus film tension will then fall. Mishandling offilm rolls, i.e. dropping ontheirends, may also effectively shorten their core tubes and result in insubstantial braking effort. Also, although core tubes are made to given nominal lengths, there is often an appreciable variation in actual length from tube to tube. The variation can be such that for some rolls their cores are too shortfor a dispenser to deliver an adequate braking effort.

I have apprehended that core tube bores are susceptible ofgreater constancy than their lengths, sincetheyare produced by winding on accurately dimensioned mandrels. This realisation has aided me to devise an improved braking mechanism which does not rely on axial loading of a core tubeto achieve the necessary braking effort.

According to the present invention, there is provided a packaging film dispenser, comprising means to mount a roll offilm wound on a core tube for rotation during dispensing, braking means to resist rotation of the roll, and adjusting means for adjustably biasingtogethera non-rotaryelementofthe braking means and a rotational elementthereofto control the braking effort established by the braking means, the rotational element being furnished with means for releasably engaging this element with the inside ofthe core tube in a manner assuring joint rotation with the core tube when the said means is engaged with the core tube.

A dispenser according to the invention can be a manually-operated tool organ automaticorsemi- automatic, powered machine. In a manual tool,the adjusting means conveniently has a twist-type hand grip for ease of adjustment of the braking effort and hence the tension in the film wrapping applied to e.g. a loaded pallet.

In preferred embodiments of the invention, the adjusting means is operable to cause the core tube engaging means to engage the core tube nonrotatably in the course of setting the braking effort.

rhe core tube engaging means is advantageously one r more expansible friction member(s) in the form of O-rings. Such members are readily able to exert a firm friction grip on the inside ofthe core tube.

Preferred embodiments ofthe invention could be set up such that the braking effort is so greatthe braking means is effectively locked, while the core tube engaging means is left in a condition allowing limited slip of the core tube relative thereto. When set upthus,the normally rotational brake element is secured against rotation. Ease of slippage could be varied by use of the adjusting means to control the firmness of engagement with the core tube. Such an arrangement could work adequately, particularly if the core tube were made from a plastics material. Wear of the core tube itself or its engaging means could be significant, however, especially if the coretube is made of cardboard.

Recognitionthatthe preferred embodiments could be set up as just described leads me to contemplate emitting the locked braking means. Instead, the memberfurnished with the meansto engagethe inside of the core tube will be held in the dispenser in any convenient manner against rotation.

Therefore,the present invention further provides a packaging film dispenser, comprising means to mount a roll of film wound on a core tube for rotation during dispensing, means to resist rotation ofthe roll and adjusting means for controlling the resistance to rotation offered thereby, the rotation-resisting means comprising a member held non-rotatably in the dispenserwhich member is furnished with means for frictionally engaging the inside of the core tube more or Iessfirmly according to the setting of the adjusting means.

Embodiments of the invention will now be described in detail by way of example only with reference to the accompanying drawings, in which: Fig. 1 is an elevational view of a first manual film dispenser according totheinvention; Fig. 2 is an enlarged cross-sectional view th rough means for resisting rotation ofthefilm roll during a film dispensing operation; Figs. 3,4 and 5arecross-sectionalviews of alternative components forthe rotation-resisting means; and Fig. 6 is an elevational view of a second manual film dispenser according to the invention.

The invention is described hereinafter, for convenience, in relation to preferred embodiments which are manual film-dispensing tools. The invention could, however, be employed in powered automatic or semi-automaticfilm wrapping machinery.

Afirst preferred embodiment ofthe invention is illustrated in Fig. 1.The tool 10 has a flanged base plate 11 on which a roll offilm 12 is mounted for The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

rotation in an upstanding attitude by a central spine rod ortube 14. The spine 14 is welded or otherwise secured at its bottom end to the base plate 11. For manipulating the tool 10 in use, there are two handles.

One handle 15 is atop the spine directly above the film roll 12. The other handle 16 is on a cranked arm 18 welded or otherwise secured to the base plate. The film roll 12 rests on a rotatable plug 19 which loosely fits around the spine 14so as to be able to rotate freely.

The plug 19 fits into the bottom end of a core tube 20 on which the film is wound. As is now conventional, ground engaging rollers orwheels 21 are mounted between the flanges 22 ofthe base plate 11 on an axle 23. These rollers or wheels 21 ease the user's task when wrapping film around the lower reaches of a palletised load.

In the absence of some means to resist the drawing offilm from the roll 12, it would be impossible to tension a film wrapping properly.

Hitherto it has been common to retard rotation of the film roll 12 as film is drawn therefrom. In several known tools, a plug similarto plug 19 is fitted to the top end ofthe coretube and then forced towards the lower plug by screwing down the handleatopthe spine. The lower plug in such tools coacts with a friction disc sandwiched between itself and the base plate. The downward thrust exerted by the handle axially onto the core tube generates friction forces acting on the latter which resist rotation ofthe core tube and film wound thereon. Some degree of adjustment is possible to the frictional resistance and hence to the film tension byturning the top handle.

Forthe reasons stated earlier in this specification, such a means to retard rotation is notwholly satisfactory.

According to the present invention, thetool 10 is provided with a braking means 30 which does not rely on axial loading ofthe core tube 20. The braking means 30 develops a variable braking effort on the film roll 12, resisting its rotation, depending on the setting of an adjustment means including the handle 15. The braking effort is transmitted to the core tube 20 by core engaging means 31 with which the braking means 30 is provided. The said means 31 engages the inside ofthe core tube 20. No significant axiallydirected force is exerted by the dispenser on the core tube.

The braking means 30 is shown more clearly in Fig.

2. Afirst element 32 of the braking means 30 is fastened non-displaceably and non-rotatably to the upper end ofthe spine 14. Element 32 can be welded and/or pinned to the spine, or can be screw threaded and locked thereto. The non-rotational brake element 32 has an enlarged frusto-conically shaped head 34. A second element 35 of the braking means 30 coacts rotationally with brake element 32. The rotational element 35 has a cup orseating 36 for the head 34 of the non-rotational element 32. The cup is conically tapered, likethe head 34, and forms therewith an interfitting cup-and-cone drag coupling.The cone anglesofthe cup 36 and the head 34 can be the same, but generallythe cone angle of the head will be slightly the largerto enhancethefriction generated in the drag coupling. Frictional resistance to turning of brake element 35 is, of course, governed by howfirmly element 35 is pressed into contact with the head 34.

The adjustment means 15 etc. is operable directly on one ofthe brake elements to control the contact pressure as will be described hereinafter.

The adjustable braking effort developed bythe braking means 30 is coupled to the core tube bythe coretube engaging means 31 with which the rotational brake element 35 is provided. To this end, brake element 35 is in two parts 35a and 35b. They are arranged totelescope one into the otherto compress and radially expand the said means 31. The main part 35a has a central recess 38 in its end opposite the cup 36. The other part 35b informed with a central nose 39 sized to slide freely into the recess 38. Adjacent the recess and nose the two parts 35a,b respectively have confronting faces 40,41 to squeezethe said means 31 when the parts are moved relatively towards one another.The nose 39 provides a seating for the said means31.

The core tube engaging means 31 is here a rubber O-ring of circular cross section.

The nose 39 is longerthanthedepth ofthe companion recess 38. If it bottoms on the recess 38 no further radial expansion ofthe O-ring 31 is possible.

This must be taken into accountwhen designing to suitcoretubesofspecified diameters and when selecting the O-rings. It must be achieved that the O-ring is expanded sufficiently to assure joint rotation (without slip) ofthe core tube 20 and brake element 35.

In the present embodiment, the handle 15 is fast with a length of studding 42 which passes clean through apertures 44,45 in the two parts 35a,b of element35.Thestudding 42 enters a correspondingly screw-threaded bore 46 in the non-rotational brake element32. Arollerthrustrace race 48 is sandwiched between the handle 15 and part 35a. With the parts of the brake mechanism arranged as shown, screwing down the handle 15firstdisplacesthe brake element 35 into contact with brake element 32. Continued turning of the handle displaces part35b relative to the now-arrested part35a, compressing and expanding the O-ring 31 to lock brake element 35 and core tube 20 non-rotatably together.During continued rotation of the handle, parts 35a,b locktogether and are displaced only very slightly relative to the non-rotational brake element 32, thereby loading the brake means 30.

Small twists ofthe handle 15 one way orthe otherthen controls the braking effort established bythe loaded brake means 30. In practice, only about a quarterturn ofthe handle 15 suffices to lockthe brake means 30 solid afterthe O-ring 31 has secured the brake means and the core tube non-rotatablytogether.

It will thus be seen thatconcomitantwith operation ofthe adjustment means (handle 15 etc) to setthe braking effort, the core tube engaging means 31 is rendered operative to establish atightfriction grip on the core tube 20.

Modification of the braking means 30 and the core tube engaging means 31 is possible, as exemplified by Figs. 3 to 5 to which reference is now made.

In Fig. 3, the part35a containing the cup 36 has the projecting nose 39, and the part35b hasthe recess 38 for the nose. The nose in this construction, as well as in the other constructions disclosed herein, can be grooved at49 to seat the O-ring 31 .The faces 50,51 are now inclined so thattogetherthey define a dovetailshaped groove forthe O-ring. This dovetail shape should help to ensure the O-ring is pulled back from the core tube when the handle 15 is turned in a releasing direction.

The O-ring forming the core tube engaging means need not be ofcircularsection. Rectangular or square sectioned rings can be used, for instance, as shown in Figs. 3 and 4.

Should it be felt that one O-ring 31 is not sufficientto achieve non-rotational fastening of the core tube 20 to the rotational brake element, the modification shown in Fig. 4 can be adopted. Here, part35a has the nose 39 and a shoulder 54. The nose, or neck 39 is elongated to receive a plurality of collars 56,57 and a plurality of intervening O-rings 58,59. Collar 56 serves as the part 35b. When this collar is displaced -- by the adjustment means 15-towards shoulder 54 it compresses and expands O-ring 58 between itself and collar 57. The latter similarly compresses O-ring 59 against the shoulder 54. More than two collars and O-rings can be employed. The collars and shoulder 54 can be so shaped as to provide dovetail receivers for O-rings, if desired.

The arrangement shown in Fig. 2 could be modified by extension of the nose 39 shown therein, so as to make use of a plurality of collars and O-rings.

It is not essential forthe core-engaging means to use O-rings, as Fig. shows. Here, the rotational brake element comprises two parts 60,61 the former containing the cup 36. The part 61 has a recess 62 into which a frusto-conical end 64 of part 60 intrudes. The recess 62 is bounded by a skirt 66 rendered flexible and expansible by slits 67. The inner surface of the skirt is tapered approximatelyto match the frustoconical end 64. It will be understood that when part 61 is thrust against part 60, the skirt 66 is caused to flare outwardlyto engage the inside ofthe core tube 20 frictionally. The outside of the skirt could be arranged, if desired to bite positively into the core tube rather than to rely solely on friction for assuring joint rotation ofthe core tube with the rotational brake element.

In any embodiment ofthe invention, the stationary brake element secured to the roll mounting means 14 etc could feature the cup of a cup-and-cone drag coupling. The rotational brake element will then be furnishedwith a cone end to enterthe cup.

The drag coupling between the stationary and rotational brake elements is not essentially of cup and cone type, and may be of disotypefor instance utilising one or more friction discs.

The studding 42 could be replaced by a threaded member fast with the stationary brake element 32 and the roll mounting means. For instance,thethreaded membercould be integral with brake element 32. The handle 15 will in such a case incorporate a female thread.

Removal of an exhausted film roll 12 and replace mentwith a new roll is much simpler with the tool 10 than prior tools. It will be notedthatthe braking means 30 and core tube engaging means 31 are contained wholly within the core tube. The handle 15 is small enough to pass the tube20. Thus, when a film roll needs replacing, all theuser has to do isto slacken the handle and pull the released core tube 20 up overthe handle 15. The fitting of a new film roll simply entails passing it down overthe handle. No dismantling ofthe tool 10 is involved. By contrast, prior tools require inconveniently handles, th rust bearings, plugs and packingsto be removed before rolls can be removed and replaced.

A second embodiment of the invention is shown in Fig. 6. In tool 70 an upstanding three-sided frame 71 is welded to the wheeled base plate 11. The upright side 72 ofthe frame 71 carries the handle 16, while the top handle 15 is mounted on the upper cross-piece 74 directly above the plug 19. The latter isjournalled on a stub shaft 75 fitted to the base plate 11. The film roll core tube 20 rests on the plug as before and again encloses the braking means 30. The braking means 30 and core tube engaging means can be very similarto any of the versions disclosed hereinbefore. It will be observed thatthe tool does not have a central spine extending from the base plate 11 towards the handle 15.

The braking means 30 is fitted underneath the frame cross piece 74 in registry with the handle 15. The stationary brake element is welded or otherwise fitted immovably to the cross piece 74. The rotational brake element is arranged to be drawn upwards bytwisting the handle 15 for locking onto the core tube (through the coretube engaging means 31) and for setting the braking effort. To this end,thethreaded member42 has an enlarged head disposed beneath the part 35b.

Athrust bearing is placed between the said head and part 35b. The threaded member 42 passes through clearance bores in the parts 35a,b, the stationary brake element and the cross piece 74, and is screw-threaded intoafemalethread in the handle 15.

Provided sufficient space is left between the core tube and the underside of the cross piece 74, it may be possible to load the film roll and remove it from the tool by lifting it towards the cross piece 74, after releasing the handle 15 sufficiently. To facilitate this operation, the plug 19 should only enterthe core tube to a very limited extent. Alternatively, the cross piece 74 could be either in two parts hinged together, or hinged to the uprightframe member 72, so that the hinging movement swings the bottom end ofthefilm roll leftwardly and upwardly to clear the plug 19.

That the braking means 30 exerts no significant axial loading on the core tube can be easily demonstrated conclusively. With either ofthe illustrated embodiments it is possible to lock the braking means 30 onto the core tube (by the engagement means 31) such that the core tube does not rest on the plug 19.

If it were contrived to make the frictional resistance to rotation at the cup and cone coupling greaterthan the friction between the core tube and its engagement means 31, the core tube could slip relative to the said meanswhilethe braking means is locked solid. In appropriate cases the ease of slippage, and hence the film tension, could be controlled by the effect of the adjustment means 15 etc on the expansion of the engagement means 31. The latter means then become the means by which rotation ofthefilm roll 12 is resisted. Should it be wished to utilise variable friction between the engagement means and the core tube for resisting rotation, the structures disclosed herein could readily be adapted to suit. Thus, referring to Fig.

2 byway of example, the brake element 32 will be omitted. Part 35a of member 35 will be secured non-rotatably directly to the dispenser. The member 35 will be furnished with the frictional engagement means 31 which will be expanded for more or less firm engagementwith the core tube as appropriate, by adjustment means acting to displace part 35b of member 35 relative to part35a.

Claims (20)

1. A packaging film dispenser, comprising means to mounta roll of film wound on a core tube for rotation during dispensing, braking means to resist rotation ofthe roll, and adjusting means for adjustably biasing together a non-rotary element ofthe braking means and a rotational elementthereofto control the braking effort established by the braking means,the rotational element being furnished with means for releasably engaging this elementwith the inside ofthe coretube in a manner assuring joint rotation with the core tube when the said means is engaged with the core tube.

2. Adispenseraccording to claim 1,whereinthe adjusting means biases the two brake elements together by directly acting on one of them to displace it relative to the other

3. A dispenser according to claim 2, wherein the adjusting means is screw-threaded to a part of the roll mounting means and abuts the said one brake elementto displace the latter during rotation ofthe adjusting means.

4. A dispenser according to claim 1,2 or 3, wherein the brake elements interfit by way of a drag-inducing cup-and-cone coupling.

5. A dispenser according to any of claims 1 to 4, wherein the adjusting meansisoperabletocausethe core tube engaging means to engagethe core tube non-rotatably in the course of setting the braking effort.

6. A dispenser according to any of claims 1 to 5, wherein the core tube engaging means is operable to establish a tight friction grip on the inside ofthe core tube.

7. Adispenser according to claim 6, wherein the rotational brake element is in two parts and carries an expansible friction membertherebetween, the two parts being relatively movable to expand the expansible member into engagementwiththe insideofthe core tube.

8. A dispenser according to claim 7, wherein the two parts ofthe rotational brake element telescope partly one into the otherto expand the friction member.

9. Adispenseraccording to claim 6, wherein the rotational brake element comprises a shoulder and a neck around which a plurality of alternating expansiblefriction members and collars are mounted, the collars being movable along the necktowardsthe shoulder to expand the friction members.

10. A dispenser according to any of claims 7,8 and 9, wherein the or each expansible member is an O-ring.

11. A dispenser according to any of claims 7 to 10, wherein the non-rotary brake element is mounted in the dispenser against displacement and the rotational brake element is displaceable towards and away therefrom the or each expansible friction element being expansible as the rotational element is thrust against the non-rotary brake element.

12. A dispenser according to any of claims 1 to 5, wherein the rotational brake element has two relatively-movable parts, one part having a flexible and expansible skirtand the other part having a nosefor wedging the skirt outwardly for engagement with the insideofthecoretube.

13. A dispenser according to claim 12, wherein the non-rotary brake element is mounted in the dispenser againstdisplacement and the rotational brakeele- ment is displaceable towards and away therefrom, the skirtthereoffl being expanded when the rotational element is thrust againstthe non-rotary brake element.

14. A packaging film dispenser, comprising means to mount a roll offilm wound on a core tube for rotation during dispensing, means to resist rotation of the roll and adjusting meansforcontrolling the resistance to rotation offered thereby, the rotation- resisting means comprising a member held nonrotatably in the dispenser which member is furnished with means forfrictionally engaging the inside ofthe coretube more or less firmly according to the setting oftheadjusting means.

15. Adispenseraccording to claim 14, wherein the said non-rotatable member is in two parts and carries an expansible friction member therebetween the two parts being relatively movable in responseto operation of the adjusting means to varythe expansion of the friction member.

16. Adispenseraccording to claim 14, wherein the said two parts telescope partly one into the other to expand the friction member

17. A dispenser according to claim 14, wherein the said non-rotatable member has a shoulder, a neck and a plurality of collars thereon, expansiblefriction members being mounted between the shoulder and the most adjacent collar and between neighbouring collars, and the collars being movable on the neckto compressandexpandthefrictionmembersin re sponge to operation of the adjusting means.

18. A dispenser according to claim 14, wherein the said non-rotatable member has two relatively-movable parts, one part having a flexible and expansible skirt and the other part having a nose for wedging the skirt outwardly,for engagementwith the inside of the core tube, in response to a relative movement between the parts caused by operation of the adjusting means.

19. A dispenser according to any ofthe preceding claims in theform of a manually operable dispensing tool having atwist4ype handgripforming partofthe adjustment means.

20. Packaging film dispensers substantially as herein described with reference to the accompanying drawings.