WO1987003793A1

WO1987003793A1 - Improvements to bag holders

Info

Publication number: WO1987003793A1
Application number: PCT/SE1986/000578
Authority: WO
Inventors: Claes Hedlund
Original assignee: Claes Hedlund
Priority date: 1985-12-19
Filing date: 1986-12-17
Publication date: 1987-07-02
Also published as: SE447201B; EP0252112A1; SE8506028D0

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(13) which counteracts withdrawal of the web, and further an abutment (5) spaced-apart from the reel, whereby one withdrawn bag which has been brought into engagement with the abutment is separated by the recoil rolling of the web inside the abutment under the action of the spring.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 relationship 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 separate 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 includes a vertically directed tube which is upstanding from a horizontal 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 disposed in spaced-apart relationship to the tube, against which abutment 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 inside 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 diameter. The reason for this is that, when the reel is new - and consequently 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 through several turns to pay out one bag when it begins to become empty. This relatively great variation in the size of the required rotation entails problems, such that in slight degree of rotation, the spring force will be correspondingly slight, while becoming progressively greater as the degree of rotation increases. This has had the unhappy consequence that the web of bags has a tendency to break already 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 attempts 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 drawback. Hence, the primary object of the present invention is to realise 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 invention is to realise an apparatus which is both operationally reliable and economical in manufacture. SOLUTION The object forming the basis of the present invention is attained if the apparatus disclosed by way of introduction is characterised 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 suitably 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 particularly 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 transverse 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 carrying handles for the bags once these have been separated.

As will be apparent from the Drawing figure, the reel 6, intimated 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 generate a torque against the reel which strives to counteract withdrawal of a bag from the reel. If, in this situation, the bag is drawn out against the resistance of the rotary device such a distance 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 remaining 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 tractive 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 generate when the reel is full will, of necessity, have to be relatively 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 secured 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 engagement 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 attained 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, arrest 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 revolutions.

In order to attain the desired prestressing in the spring 13, the rod 9 is rotated a desired number of revolutions until contemplated 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 rotation 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 intimated 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 certain 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 successively consumed. In order to attain a nominal plateau spring characteristic, i.e. a torque which increases but slightly with the number of rotational revolutions, the spring 13 should be as long as possible. 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 material 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 rigidity, 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 characteristic 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 adaptation 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 rotary device a torque characteristic which goes as far as to compensate 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 withdrawal 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 employed to just as great advantage. Thus, it is possible, for example, 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 displaceable pawl which moves into engagement with a fixed abutment arresting 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 thepretensioning is achieved is by employing the worm gear principle. The travelling non-rotary nut in such a construction may enter into engagement with an abutment on the threaded worm rod and thereby prevent 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 expenditure.

In Fig. 2, the rod could well be hollow or tubular and be interiorly 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 example, 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 rotation 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

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 rotatable, 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 withdrawal of the web from the reel and thereby separate one withdrawn bag which has been brought into engagement with the abutment by recoiling the web inside the abutment, characterised in that the rotary device is arranged for rotation through a larger number of revolutions 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 relation 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 engagement 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, characterised in that the flexible member (19) is a planar band which is wound with a number of mutually superposed turns, the band being enclosed in a casing (23) which is operative to retain the wound configuration of the band on rotation of the rotatable part (21) against the tightening direction of the band.