GB2217288A

GB2217288A - Bag feeding apparatus

Info

Publication number: GB2217288A
Application number: GB8907639A
Authority: GB
Inventors: Richard John Dawson Coleby
Original assignee: Thames Sack and Bag Co Ltd
Current assignee: Thames Sack and Bag Co Ltd
Priority date: 1988-04-07
Filing date: 1989-04-05
Publication date: 1989-10-25
Anticipated expiration: 2009-04-05
Also published as: GB8907639D0; GB8808087D0; GB2217288B

Abstract

An apparatus for feeding open-ended bags 2 which contain a product into a bag closing device 6 for closing the open end of the bag comprises bag spreading arms 7 which (a) enter the open end of the bag, (b) spread opposite edges of the bag apart so that the opening becomes generally linear and the edges are engaged by the spreading means, and (c) travel in a direction opposite to that in which it entered the bag whilst still engaging the bag, to carry the bag with it so that the product is forced to the bottom of the bag by guide arms 9 defining a bag-receiving open-ended slot. The bags may be opened, to allow entry of the arms, by a vacuum head 5. The arms 7 and vacuum head 5 may be mounted on the same or different carriages. <IMAGE>

Description

BAG FEEDING APPARATUS This invention relates to a bag feeding apparatus. It is intended for feeding open-ended bags which contain a product into a bag closing device for closing the open end of the bag.

According to the present invention there is provided a bag feeding apparatus for feeding an openended bag travelling along a path to a bag closing device, the apparatus comprising vacuum means for causing adjacent walls of the bag to separate from one another and thereby open the end of the bag, bag spreading means and means arranged to cause the bag spreading means to (a) enter the open end of the bag and (b) spread opposite edges of the bag apart so that the opening becomes generally linear and the edges are engaged by spreading means.

According to the present invention there also is provided a bag feeding apparatus for feeding an open ended bag travelling along a path to a bag closing device, the apparatus comprising bag spreading means and means arranged to cause the bag spreading means to (a) enter the open end of the bag, (b) spread opposite edges of the bag apart so that the opening becomes generally linear and the edges are engaged by the spreading means, and (c) travel in a direction opposite to that in which it entered the bag,whilst still engaging the bag, to carry the bag with it.

The invention further provides an apparatus comprising a bag feeding apparatus as aforesaid, a bag closing device including guide means defining an openended slot, and means for so conveying open-ended bags along the said path such that each bag passes into and along the said slot.

Figures 1 to 8 of the accompanying drawings are diagrammatic plan views of a first embodiment of the invention in successive stages of operation, and Figures 9 to 14 are similar views of a second embodiment.

Referring to the first embodiment, Figure 1 shows a conveyor 1 travelling from right to left as indicated by the arrows. The conveyor carries bags 2 each of which contains product and each of which has an open end 3. Product is contained within each of the bags.

To one side of the conveyor is arranged a carriage 4 which is capable of travelling longitudinally, i.e.

parallel to the direction of movement of the conveyor 1. A vacuum head 5 is mounted on the carriage 4, and in addition to travelling with the carriage is capable of movement upwards and downwards with respect to the conveyor. A further carriage 6 is mounted on the carriage 4 and is arranged not only to travel with the carriage 4 but also to travel transversely, i.e.

towards and away from the conveyor. The carriage 6 has a pair of bag spreading arms 7 pivotally mounted thereon. The arms are movable between the closed position shown in figure 1 and a spread-apart position which is shown in some of the later figures and will be mentioned in connection with those figures.

A bag closing device 8 is provided downstream of the carriage arrangement just described. Entry into the bag closing device 8 is via a guide device 9 which comprises a pair of arms defining between them a longitudinally extending slot open at both ends. One of the arms 9 can be seen in Figure 1, and the other arm is immediately below the one which is visible, with the slot being between the two arms. Immediately adjacent to the upstream end of the guide device 9 is a sensor 10, for example a photoelectric sensor, which detects the presence of a bag.

Although the bags may be of virtually any material, the present invention is particularly suitable for handling bags made of thin, and therefore very flexible, plastics material, for example thin thermoplastics material. In the case of thermoplastics material the bag closing device 8 is preferably a heat sealer.

At the stage shown in Figure 2 one of the bags 2 has reached the sensor 10 and been detected by it.

This causes vacuum to be applied to the vacuum head 5 and causes the vacuum head to move down towards the upper face of the bag. Detection of the bag by the sensor also causes the carriage 4 to start travelling leftwards in synchronism with the bag.

In the stage shown in Figure 3 the vacuum head 5 reaches the bag and holds the upper face by means of suction. If desired a second, similarly operated vacuum head may be provided to hold the opposite face of the bag,so as to avoid any risk of the whole bag being lifted by the vacuum head, rather than just the upper face thereof. Having engaged the upper face the vacuum head begins to rise, at which point the transverse carriage 6 begins to move towards the conveyor 1, as indicated by the arrow on the carriage 6.

In the stage shown in Figure 4 the vacuum head 5 continues to rise, thus pulling open the mouth of the bag. The spreading arms 7 continue to travel towards the conveyor, and enter the open mouth of the bag.

When the carriage 6 has reached the end of its stroke and the arms 7 have entered the bag to the maximum extent possible the arms are caused to pivot away from one another to their bag-spreading position, as shown in Figure 5. This straightens the mouth of the bag and causes it to assume a generally linear configuration. The spreading action also pulls the upper face of the bag away from the vacuum head 5 (and pulls the lower face away from the second vacuum head,if such is provided). The vacuum is switched off when the vacuum head 5 reaches the end of its upward travel, a position reached at a stage not later than that shown in Figure 7.

As soon as the arms are fully open the carriage 6 begins to retract, the arms remaining in their open position while retraction takes place. The engagement between the arms and edges of the bag means that in the initial stage of this retraction the bag is retracted with the arms. This can be seen in Figure 6, which illustrates, from right to left, three successive positions of the bag. Comparing the first and second of these positions it will be seen that the bag has moved with the arms in the direction of movement of the arms and the carriage 6. Figure 6 also shows the position of product in the bag, and this is indicated by shading.

The bag continues to move with the arms until the product-containing part of the bag reaches the slot defined between the guides 9. The amount of product in the bag and the width of the slot are so chosen that the product-containing part of the bag cannot pass through the slot. Accordingly, when the productcontaining part of the bag reaches the slot the initial effect of further retraction of the arms is to continue to carry the bag with them but force the product further away from the open end of the bag, in so far as this is possible. This has the beneficial effect, at least for certain products, that the product is tightly packed within the bag. This is advantageous from the point of view of ensuring that the bags, once sealed, do not occupy a greater volume than is necessary to contain the product, and it is also beneficial from an aesthetic point of view.Once maximum packing of the product has occurred, further retraction of the arms causes the arms to be pulled out of the bag. It is to be understood, however, that for some products tight packing is not desired, for example if there is a risk of damage to the product. In such instances the step of retracting the arms while they grip the sides of the bag is omitted.

As shown in Figure 7, when the carriage 6 has retracted completely the arms 7 close and the carriage 4 returns to its original position to await the arrival of the next bag. This is shown in Figure 8.

The second embodiment, which is shown in Figures 9 to 14, is substantially the same as the first embodiment except that the carriage 6 is mounted on a longitudinally travelling carriage 14 which is separate from the carriage 4 on which the vacuum head is mounted and which travels independently thereof.

The provision of two independently moving longitudinally travelling carriages means that the embodiment of Figures 9 to 14 is capable of handling bags at a greater rate than is the embodiment of Figures 1 to 8.

The way in which the spreading arms 7 act on the bag is substantially the same in the second embodiment as in the first. What is different is the operation of the vacuum head. It will be seen that in the second embodiment the sensor 10 is located substantially upstream of where it is located in the first embodiment, and that the vacuum head moves towards the bag at an earlier stage (see Figure 9), while the spreading arms 7 are still engaged with the previous bag. By the time the vacuum head has reached the bag and opened the bag mouth the arms 7 have withdrawn from the previous bag and the carriage 14 carrying the arms has returned to its at-rest position (see Figure 10).

When the carriage 4 reaches the carriage 14 (see Figure 11) a limit switch causes the latter to start moving in synchronism with the carriage 4, and at the same time the bag spreading operation commences (see Figures 11 and 12). While the bag spreading operation is taking place the vacuum head is able to return to its initial position (see Figures 12 and 13) so as to be ready to deal with a subsequent bag (see Figure 14).

As can be seen from this last figure, by the time the carriage 6 has retracted completely and the spreading arms 7 have finished their task the carriage 4 which carries the vacuum head has already reached its starting position and has begun to deal with a subsequent bag.

One point which should be emphasised is that unlike at least a majority of the prior art apparatuses in which bag spreading is provided, the present invention, at least as regards the embodiments described above, is suitable for use with bags of thin, highly flexible material, and is not restricted to use with bags of relatively rigid material. It is also to be noted that when the arms 7 retract pulling the bag with them this not only serves to compress product within the bag but also serves to straighten the bag up,should it be skewed, thus ensuring that when the bag is sealed the seal runs straight across the bag and not at an angle.

It will be understood that various modifications can be made to the embodiments described above. For example, although the arms 7 are shown as being pivotally mounted they could be mounted for linear movement away from one another. The carriages 4 and 6 and, if provided, the carriage 14, are conveniently driven by means of compressed air, but they could be driven in some other manner, for example electrically.

Claims

CLAIMS:

1. A bag feeding apparatus for feeding an openended bag travelling along a path to a bag closing device, the apparatus comprising vacuum means for causing adjacent walls of the bag to separate from one another and thereby open the end of the bag, bag spreading means and means arranged to cause the bag spreading means to (a) enter the open end of the bag and (b) spread opposite edges of the bag apart so that the opening becomes generally linear and the edges are engaged by the spreading means.

2. A bag feeding apparatus for feeding an openended bag travelling along a path to a bag closing device, the apparatus comprising bag spreading means and means arranged to cause the bag spreading means to (a) enter the open end of the bag, (b) spread opposite edges of the bag apart so that the opening becomes generally linear and the edges are engaged by the spreading means, and (c) travel in a direction opposite to that in which it entered the bag, whilst still engaging the bag, to carry the bag with it.

3. An apparatus according to claim 2, further comprising vacuum means for causing adjacent walls of the bag to separate from one another and thereby open the end of the bag.

4. An apparatus according to claim 1 or 3, wherein the said vacuum means and the said bag spreading means are arranged for movement in unison with one another in a direction parallel to the said path, but with the bag spreading means movable with respect to the vacuum means in a direction transverse to the said path.

5. An apparatus according to claim 1 or 3, wherein the said vacuum means and the said bag spreading means are arranged for movement independent of one another in a direction parallel to the said path, whereby each can engage the same bag or a different bag, the bag spreading means further being movable in a direction transverse to the said path.

6. An apparatus comprising a bag feeding apparatus according to any preceding claim, a bag closing device including guide means defining and open-ended slot, and means for so conveying open-ended bags along the said path that each bag passed into and along the said slot.

7. A bag feeding apparatus substantially as herein described with reference to Figures 1 to 8 or Figures 9 to 14 of the accompanying drawings.

8. An apparatus comprising a bag feeding apparatus, a bag closing device and a bag conveying means, substantially as herein described with reference to Figures 1 to 8 or Figures 9 to 14 of the accompanying drawings.