IMPROVEMENTS TO BAG HOLDERS

Abstract: A bag holder is intended for realising, for example in a retail outlet, separation of one bag from a web of bags wound up to form a reel (6). The bag holder is provided with a support member (2, 3) in relation to which the reel is rotatable, and a spring (13) which counteracts withdrawal of the web, and further an abutment (5) spaced-apart from the reel, whereby one withdrawn bag which has been brought into engagement with the abutment is separated by the recoil rolling of the web inside the abutment under the action of the spring. The spring is of a length so as to permit rotation a greater number of revolutions than corresponds to the withdrawal of one bag when the reel (6) is expended and is further pre-tensioned in that a band (19) is wound about a rotatable part (21) connected to the reel. One end of the band is secured in a slot (18) in the rotatable part (21) and its other end in a housing (23) fixedly disposed on the support member (2, 3).

Description: IMPROVEMENTS TO BAG HOLDERS TECHNICAL FIELD The present invention relates to a bag holder of the type which is employed for separating bags from a web of bags wound up to a reel, the holder comprising a support member in relation to which the reel is rotatable, an abutment disposed in spaced-apart rela- tionship to the support member, and a rotary device connected to the support member and the reel, the rotary device being arranged to counteract drawing out of the web from the reel and thereby to se¬ parate one drawn-out bag which has been brought into engagement with the abutment by reeling in of the web inside the abutment. BACKGROUND ART Swedish Patent Application No. 8504324-8 discloses a bag holder of the type mentioned by way of introduction. This bag holder in¬ cludes a vertically directed tube which is upstanding from a hori¬ zontal support surface. The web of bags wound up to form a reel is then placed about this vertically directed tube. Interiorly within the tube, there is disposed a helically-shaped coiled spring, which, with its lower end, is non-rotationally connected to the tube, and with its upper end extends slightly above the upper edge of the tube in order there to engage with engagement means interiorly within the bobbin of the reel. The bag holder further includes an abutment dis¬ posed in spaced-apart relationship to the tube, against which abut¬ ment the end of the withdrawn bag located most proximal the tube may be brought into engagement. The bag holder functions such that the free end of the web of bags is grasped and drawn out, the reel being rotated and the spring placed under tension. The web is drawn out such a distance that the outermost bag can be hooked fast to the abutment, whereafter the web is released so that a recoil jerking motion occurs. At this point, the perforations which separate the different bags of the web from one another will rupture so that the portion of the web located in¬ side the abutment will be rolled back onto the reel under the action of the spring. A bag holder of this type functions adequately as long as the reel of bags is not permitted an excessively large variation in dia¬ meter. The reason for this is that, when the reel is new - and con¬ sequently is of large diameter - there is only required a rotation of the order of magnitude of half a turn to one complete turn for withdrawing a bag. On the other hand, the reel must be rotated thro¬ ugh several turns to pay out one bag when it begins to become em¬ pty. This relatively great variation in the size of the required ro¬ tation entails problems, such that in slight degree of rotation, the spring force will be correspondingly slight, while becoming progres- sively greater as the degree of rotation increases. This has had the unhappy consequence that the web of bags has a tendency to break al¬ ready in response to the withdrawal force when the reel approaches becoming empty, while the force of the spring is so slight when the reel is full as to be almost incapable . of generating sufficient power to realise the requisite recoil jerking motion. The above-outlined problem is further accentuated in that at¬ tempts are made to render the reel of bags as large as possible in order to extend the interval of time between reel replenishments. OBJECT OF THE PRESENT INVENTION The object of the present invention is to realise an apparatus of the type disclosed by way of introduction, the apparatus being designed in such a manner as to obviate the above-considered draw¬ back. Hence, the primary object of the present invention is to rea¬ lise an apparatus in which satisfactory spring force is guaranteed already when the reel is new, while, this notwithstanding, the spring force does not increase appreciably when the reel is empty and there is thus required a rotation of several turns for the withdrawal of a single bag. A further object of the present in¬ vention is to realise an apparatus which is both operationally re¬ liable and economical in manufacture. SOLUTION The object forming the basis of the present invention is at¬ tained if the apparatus disclosed by way of introduction is charac¬ terised in that the rotary device is disposed for rotation through a greater number of revolutions than corresponds to the withdrawal of one bag when the reel is empty or almost empty, and that the rotary device is pretensioned when the web is not withdrawn. In one preferred embodiment of the present invention, it suit¬ ably further applies that the rotary device is a spring, the spring being prestressed in that a flexible device is wound about a part rotatable together with the reel, the flexible device being secured. with its one end in the rotatable part and being fixedly disposed with its other end in relation to the support member. In a further embodiment of the present invention which is par¬ ticularly simple to manufacture, it further suitably applies that the spring is a helically-shaped spring which, with its one end, is connected to a rotary rod and, with its other end, is connected to the support member, the rod being provided with an engagement device for non-rotary engagement with the reel and the rotatable part. The subject matter of the present invention is also suitably characterised in that the rod is disposed interiorly within the spring, the engagement device and the rotatable part being disposed at opposite ends of the rod. As a result of these constructive features, the advantage will be afforded that the spring may be made of considerable length and thereby enjoy uniform characteristics without the spring running the risk of being deformed on being placed under tension. Thus, the rod acts as a centering means for the spring. Finally, the subject matter of the present invention is also suitably characterised in that the flexible device is a planar band or strip which is wound with a number of superosed turns, the band being enclosed in a casing which is disposed to retain the wound configuration of the band on rotation of the rotatable part against the tightening direction of the band. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The nature of the present invention and its aspects will be more readily understood from the following brief description of the accompanying Drawings, and discussion relating thereto. In the accompanying Drawings: Fig. 1 illustrates in perspective one variation of the bag holder according to the present invention; Fig. 2 is a vertical section through a part of the bag holder; and Fig. 3 is a view directly from beneath of the part of the bag holder shown in Fig. 2. DESCRIPTION OF PREFERRED EMBODIMENT Referring to the Drawings, Fig. 1 shows one example of a bag holder in which the present invention is applicable. The bag holder comprises a frame post 1 which may be mounted in a shop counter for sale of, for instance, fruit which is to be packed in the bags. At the upper end of the frame post, there are provided two projecting support members 2 on which there is fixedly anchored a vertically directed tube 3. The bag holder further includes two projecting arms 4, extending in opposite directions and provided, at their free ends spaced from the tube 3, with abutments 5. The disclosed bag holder is employed for a web of bags wound up to a reel 6, the individual bags being separated by means of trans¬ verse perforations. Furthermore, holes are provided in the boundary regions between the bags in the central path of the web, such that the portions of the web straddling the holes will constitute carry¬ ing handles for the bags once these have been separated. As will be apparent from the Drawing figure, the reel 6, inti¬ mated by ghosted lines, has been placed about the vertical tube 3, so that the reel is rotatable around the tube. Interiorly in the vertical tube 3, there is provided a rotary device which is coupled to the reel 6 in such a manner as to gene¬ rate a torque against the reel which strives to counteract with¬ drawal of a bag from the reel. If, in this situation, the bag is drawn out against the resistance of the rotary device such a dis¬ tance that the opening between the outermost and next-outermost bags may be brought into engagement with the abutment 5 and the bag is thereafter released, the rotary device will roll up that part of the web located inside the abutment 5, whereby the outermost bag will, by a recoil motion towards the abutment, be separated from the re¬ maining part of the web. The skilled reader of this specification will readily perceive that the tractive force required for drawing out the web from the reel 6 will vary greatly, depending upon the diameter of the reel 6, even if the torque of the rotary device remains constant. Thus, the very diameter variations undergone by the reel during the course of its consumption will occasion a considerable difference in the trac¬ tive force required for drawing out the outermost bag, even if the torque applied from the rotary device were to remain constant. It follows from this that the torque which the rotary device must gen¬ erate when the reel is full will, of necessity, have to be rela- tively great. Further amplification of this torque is undesirable when the reel begins to be empty, since the smaller diameter of the reel at this stage will give rise to a greater tractive force in the web. Fig. 2 is a vertical and diametric section through one of the two tubes 3. It will be apparent from this Figure that the tube 3 is, with its lower end, secured - for example by welding or other suitable means - in the projecting support member 2. At its upper end, the tube 3 is provided with a bearing 7 which is non- rotationally connected with the tube. The bearing 7 has a through bore 8 for the rotary accommodation of a vertical rod 9. At the bottom end of the tube 3, there is disposed a second bearing 10 which is similarly provided with a bore 11 through which the rod 9 extends. Naturally, as further apparent from Fig. 2, there is provided a corresponding aperture in the support member 2. The upper bearing 7 has an anchorage 12 which may be designed as a conical, exteriorly threaded portion which extends downwardly from the underside of the bearing, concentrically about the bore 8. This anchorage 12 serves for securing the upper end of a helically- shaped, preferably tightly-wound, coiled spring 13 which will hereby surround the rotary rod 9. By securing the upper end of the coiled spring 13 to the anchorage 12, this end of the coiled spring will be non-rotationally united to the tube 3 and support member 2. The bottom end of the coiled spring 13 is correspondingly se¬ cured to an anchorage 14 of analoguous design on the rod 9. Hence, it will hereby be possible to rotate the rod 9 against the action of the spring 13, in which case the spring will naturally retract the rod on release. At its upper end, the rotary rod 9 is provided with an engagement member 15 which is in non-rotational unison with a corresponding engagement member 16 fixedly disposed in the bobbin 17 of the reel 6. By way of example, the engagement member 15 may be designed as a planar tongue extending through a slot-like aperture in the engagement member 16 of the bobbin 17. Naturally, the engage¬ ment member 15 on the rod may be of triangular, rectangular or any other appropriate design permitting the transfer of torque between the two engagement members. Suitably, the engagement member 16 of the bobbin 17 may also be permanently fixed in the bobbin and may be of ex-works combination therewith. It will be apparent from the above description of the present invention that if a bag is drawn out from the reel 6, the reel will rotate, with the result that the engagement member 16 of the bobbin 17 will, because of its non-rotational connection to the engagement member 15 of the rod 9, transfer this rotation to the rod, the spring being thus placed under tension. If the bag is then released, the spring 13 will, of course, strive to roll back the bag onto the reel 6 once again. In order to realise a sufficient tractive force against the web when the reel 6 is full, the rotary device must generate a certain minimum torque already after the withdrawal of one bag. This is at¬ tained according to the present invention in that the rotary device is prestressed such that it strives - even before withdrawal of the web - to rotate the reel in a direction for retraction of the web, this being however prevented by the provision of a suitable arrest means. In practice, this is realised in that the lower end portion of the vertical rod 9 is provided with a transverse slot 18 in which there is fixedly disposed one end of a planar band 19, preferably manufactured of woven textile material. The opposite end of the band 19 is secured to a retainer in the form of a pin, stub shaft or the like disposed in the underside of the support member 2. The general requirements of the arrest means are that it shall, in the employment of a prestressed rotary device or spring 13, ar¬ rest rotation in the direction in which the spring strives to rotate the reel 6, while remaining inactive and permitting free rotation of the reel against the action of the spring for at least that number of revolutions which is required for withdrawing one bag when the reel is almost empty, but preferably a further number of revo¬ lutions. In order to attain the desired prestressing in the spring 13, the rod 9 is rotated a desired number of revolutions until contem¬ plated prestressing is achieved. Thereafter, the band 19 is wound onto the lower section of the rod 9 with such direction that the spring force strives to tighten the superposed turns of the band 19 even harder. In this instance, the free end of the band secured in the retainer 20 will hold the band captive and thereby prevent ro¬ tation of the rod 9 and the spring 13, such that the band acts as an arrest against further rotation. If the rod 9 is rotated in the unwinding direction of the web, the spring 13 will be further tensioned, while on the other hand the band 19 will be rotated in such a manner that the tightly-drawn turns in the roll 22 disposed about the bottom end section 21 of the rod 9 will be released from one another. In order, at this point, to prevent the roll 22 from being wound up with such force that the winding direction is wholly or partly reversed, it is vital that the roll be held together exteriorly. This is achieved according to the present invention in that the roll, the end section 21 and the pin 20 are enclosed in a casing which is not shown in Fig. 2 but is in¬ timated by reference numeral 23 in Fig. 3. To prevent axial displacement of the rod 9 caused by the spring when this is placed under tension, the rod 9 is provided with axial bearings (not shown) either at the upper bearing 7 or the lower bearing 10. As has been mentioned above, the intention is to achieve a torque generation from the rotary device which is already of a cer- tain magnitude when withdrawal of the web begins. This torque is then to be sustained unchanged as far as is possible even as the number of rotational revolutions of the rotary device increases, but should preferably fade in strength at such a rate that compensation is ensured for the reducing reel diameter as the reel is succes¬ sively consumed. In order to attain a nominal plateau spring charac ¬ teristic, i.e. a torque which increases but slightly with the number of rotational revolutions, the spring 13 should be as long as pos¬ sible. In this consideration, the shortest conceivable length is that which permits the number of rotational revolutions entailed by the prestressing employed, but in addition at least that number of revolutions required for withdrawing one bag when the reel begins to become empty. Suitably however, the spring should be of such length as to exceed these minimum requirements. DESCRIPTION OF ALTERNATIVE EMBODIMENTS Instead of employing a planar, preferably woven textile band 19, it is possible to employ a band of a solid flexible plastic ma- terial which is preferably manufactured in such a manner that the friction between the superposed turns in the roll 22 be as slight as possible. If such a band is imparted with a certain inherent rigi¬ dity, the band will function as a spring when the rod 9 is rotated. If, furthermore, the band is manufactured in such a manner that, in its rest state, its turns are mutually recumbent, a torque will be generated which is counter-directed to the torque from the spring 13 when this is placed under tension. It is hereby possible to impart to the rotary device a flatter - or even a falling - torque charac¬ teristic in relation to that which prevails when a flexless band 19 is employed. In such a situation, the band 19 and the spring 13 will function as counter-directed spring means. An even more manifest effect in this direction can be achieved if the band 19 is, instead of being manufactured from plastic or textile material, designed as a coiled spring of metal. By adap- tation of the spring properties and prestressing in the two springs, it will hereby be possible to render the torque of the rotary device wholly independent of the number of rotational revolutions of the rod 9. If the spring engaging with the bottom end section 21 of the rod 9 is further strengthened, it is possible to impart to the ro¬ tary device a torque characteristic which goes as far as to compen¬ sate for the different diameters of the reel when it is new and when it is approaching expenditure. By such means, it should be possible to achieve a constant with¬ drawal force for the bags of the web irrespective the size of the reel. The above-described arrest which imparts a pre-tensioning to the rotary device or spring 13 need not be designed in the manner disclosed in the foregoing. Other fundamental solutions may be em¬ ployed to just as great advantage. Thus, it is possible, for ex¬ ample, to place a minor gear wheel at the bottom end of the rod 9, this minor gear wheel being in mesh with a major gear wheel which will hence rotate considerably more slowly than the rod proper. This major gear wheel is then provided with a possibly adjustable or dis- placeable pawl which moves into engagement with a fixed abutment ar¬ resting the rotation of the major gear wheel in that direction in which the rotary device or the spring 13 strives to move the gear wheel. As a result of the gear ratio between the rod 9 and the wheel with the pawl, the rod 9 may rotate a large number of revolutions before the major wheel has completed one revolution and the pawl on the wheel thus enters into engagement with the fixed abutment. The gear ratio between the two gear wheels is suitably selected such that the number of rotational revolutions described by the reel must at least permit withdrawal of one bag when the reel begins to become empty. Instead of employing meshing gear wheels, it is possible to utilise any other type of gearing arrangement, for example a rack and pinion drive, sprocket wheel or the like. Yet a further alternative for realising a stop against the striving of the rotary device 13 to turn the rod 9 so that thepre- tensioning is achieved is by employing the worm gear principle. The travelling non-rotary nut in such a construction may enter into en- gagement with an abutment on the threaded worm rod and thereby pre¬ vent rotation in one direction thereof, while rotation is permitted in the other direction, the nut travelling along the worm rod. If the pitch is relatively great, no self-locking of the worm rod will occur when the nut arrives in engagement with the fixed abutment, at the same time as a relatively short length of the worm rod will nevertheless permit a generous number of rotational revolutions of the rod, such that the available torque range for the reel will be sufficient even when the reel begins to approach complete expend¬ iture. In Fig. 2, the rod could well be hollow or tubular and be in¬ teriorly provided with a thread of relatively large pitch. There is then disposed in this thread a nut or sliding member provided with a non-rotational symmetric through-hole in which there is disposed a fixed bar which is thus located coaxially with the rod 9. For ex¬ ample, this longitudinal bar may be a flat profile, a triangular profile or the like. To realise arrest in a suitable position, the bottom end section 21 of the tube may, for example, be severed and the opening in the plate 2 may be slightly smaller than that shown on the Drawing, so that only the bar disposed coaxially with the tube 9 may pass through the opening. The nut reciprocal in the tube will hereby come into abutment with the plate 2, whereby the ro- tation of the tube 9 will be arrested. The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the spirit and scope of the appended Claims.

Claims: CLAIMS 1. An apparatus in bag holders of the type used for separating bags from a web of bags wound up to form a reel (6), including a support member (2, 3) in relation to which the reel (6) is rotat¬ able, an abutment (5) disposed in spaced-apart relationship to the support member, and a rotary device connected to the support member and the reel, the rotary device being operative to counteract with¬ drawal of the web from the reel and thereby separate one withdrawn bag which has been brought into engagement with the abutment by re¬ coiling the web inside the abutment, characterised in that the ro- tary device is arranged for rotation through a larger number of re¬ volutions than corresponds to the withdrawal of one bag when the reel (6) is empty or almost empty; and that said rotary device is pre-tensioned when the web is not in the state of being withdrawn. 2. The apparatus as claimed in claim 1, characterised in that the rotary device is a spring (13), the spring being pre-tensioned in that a flexible member (19) is wound about a part (21) rotatable together with the reel (6), and is fixedly anchored with its one end in the rotatable part while being secured with its other end in re¬ lation to the support member (2, 3). 3. The apparatus as claimed in claim 2, characterised in that the spring (13) is a helically-shaped spring, which, with its one end, is connected to a rotary rod (9) and, with its other end, is connected to the support member (2, 3), the rod being provided with an engagement member (15) for non-rotational engagement with the reel (6) and with the rotatable part (21). 4. The apparatus as claimed in claim 3, characterised in that the rod (9) is disposed interiorly within the spring (13), the en¬ gagement member (15) and the rotatable part (21) being disposed at opposite ends of the rod (9). 5. The apparatus as claimed in anyone of claims 2 to 4, charac¬ terised in that the flexible member (19) is a planar band which is wound with a number of mutually superposed turns, the band being en¬ closed in a casing (23) which is operative to retain the wound con¬ figuration of the band on rotation of the rotatable part (21) ag- ainst the tightening direction of the band.

Inventors: HEDLUND CLAES, HEDLUND, CLAES
Applicants: HEDLUND CLAES, HEDLUND, CLAES
Application year: 1986
Main classification: A47F13
IPC codes: B65B43