GB2176165A - Bag opening device for packaging - Google Patents

Abstract

Bag opening apparatus uses a pin 8a to penetrate both the upper and lower panels 16 and 17 respectively, of packaging bags, and then upon retraction of the pin from an anvil hole 10, the upper panel 16 is entrained by the pin while the lower panel is held down, for example by means of adhesive carrier tapes on which the bags are mounted. <IMAGE>

Description

SPECIFICATION Bag opening device for packaging The present invention relates to apparatus for opening plastics packaging bags.

Hitherto, plastics packaging bags have been presented to a packaging location either by advancing them using carrier tapes pulled along a loading table towards the opening location, or by presenting a stack ofthe bags on a wicket type holder in which it is always the uppermost bag on the stack which is opened, or by advancing a chain of side-sealed bags (i.e. a chain of bags in which the mouths ofthe bags face sidewardly ofthe continuous chain, the sides of the bags are sealed bytransverse sealed lines of the chain, and the closed end of each bag is defined by the fold line of the web forming the chain). In each case, there is a need for positive opening of the bag art a loading location before a product can be inserted therein.It may even be desirable for the opened bag then to be conveyed to a loading location from the opening location.

Traditionally the opening operation has been carried out using either (a) an air jet biown across the top ofthe bag to causethe mouth to open and the bag then to billow up ready for loading, or (b) lifting the uppermost panel ofthe bag with one or more suction pads, or (c) lifting the bag using an adhesive-coated lifting member engaging the outside ofthe bag, or (d) mechanically ruffling the bag to form a wrinkle in the upperwall which can then be exploited by the injection of inflating airthrough the wrinkle.

All ofthese methods havecertain shortcomings as regards ensuring reliable and positive bag opening action. Furthermore, the adhesive-coated lifting members usually require a removable adhesive tape which constitutes a costly consumable item, and the suction pad system has the additional disadvantage of a high powerconsumptionto maintainthesuction pads operative for bag opening.

It is an object ofthe present invention to provide a new bag opening system which does not rely on a vacuum effect, and which is more positive than a pneumatic opening system or known mechanical opening system.

Accordingly, the present invention provides apparatus for opening packaging bags, comprising meansforsupporting a packaging bag in aflat configuration, a penetrating member driven for movementtowardsandthroughtheflatheld bag to penetrate at least one wall ofthe bag whilethe penetrating member is moving in a first direction; means for reversing the movement ofthe penetrating member after penetration of the bag material; and means for holding down that one of said panels on the side ofthe bag remote from the position ofthe penetrating membertowards which it retracts during its reversed of movement.

In orderthatthe present invention may more readily be understood the following description is given, merely by way of example, with reference to several embodiments of the invention, illustrated in the accompanying drawings in which Figure lisa perspective view of a bag opening table showing a chain oftaped imbricated bags on the table readyforopening; Figure2 is a vertical section ofthetip of a bag opening pin and the anvil table with which it cooperates; Figure3showsthe pin and table of Figure 2 during the pin retraction phase; Figure4shows a view, similar to Figure 2, but representing an alternative form of bag opening pin suitableforlipped bags; and Figure 5is a view similar to Figure 3, but showing the pin of Figure 4.

Referring now to Figure 1, there can be seen a bag opening table generally designated 1, having thereon an array of imbricated packaging bags 2 connected to a pair of adhesive tapes 3 which are drawn into a tape pulling unit4to index the bags 2, as required. In this particular embodiment, the bags have equal length upper and lower panels. However it is possible for eitherthe upper panel orthe lower panel to be longer than the other one in order to provide a bag having an extended lip on one face.

Across bar5 ofthe loading table carries a pairof pneumatic rams 6which operate to reciprocate a pair of spaced "opening pin" carriers 7, each ofwhich carries a respective opening pin 8. When each ram 6 is operated, the opening pins 6 descend towards anvil blocks 9 overhanging the edge of the opening table, and the pins 8 enter suitably dimensioned holes 10 in the anvil blocks 9.

Figure 1 shows that the holes lOin the anvil blocks 9 are just on the inboard side ofthe two tapes 3, and it is preferred that the spacing between the tapes 3 and the holes 9 be very small, for example ofthe order of 5 to lOmm.

It will of course be appreciated that in the embodimentshown in Figure 1 the adhesion of the carrier tapes 3 to the mouth end of the leading bag 2 (the bag having its mouth portion placed on the anvil blocks 9) will hold down the lower panel ofthe bag, leaving the upper panel free to be lifted away from it to the open the bag. The lifting action is derived by virtue ofthe fact that as the pins 8 are retracted from the holes 10, there must be some grip ofthe material ofthe uper bag panel on the pins 8to effectthe opening action. The design ofthe pins to achieve this will be described below.

The cross bar 5 includes a longitudinal slot 11 to allowthetwo rams 6to be adjusted towards and away from one another by virtue of an adjustment wheel 12 which can be rotated in one direction to close the rams 6together, and in the opposite directionto movethem apart,forexample by means of a lead screw mechanism . The wheel 12 is also linked to a similar mechanism which effects movement together and apart of the two anvil blocks 9.

The adjustment wheel 13 can be operated to vary the height of the cross bar Sin its raised position, for the purposes of adjusting the height ofthe bag mouth opening in the opened condition.

A suitable optical sensor may serve to stop the indexing action when the bag 2 reaches the desired position on the anvil block 9, and to extend the rams 6 at that time to begin the opening operation. Oncethe pins have reached the bottom of their stroke, they automatically retractto lift the top bag panel whilethe lower bag panel is held in place by the adhesion to the tapes 3.

Alternatively, the retention of the lower bag panel in place may be achieved by a hold-down finger arrangementwhere the lower panel ofthe bag is longerthan the upper one to provide a "lower-lipped" bag configuration. Another possibility is for a suction pad to be built in to the bag supporttableto hold the lower panel down.

Figure 2 shows a plain pin 8a having a sharpened tip 14and a roughened shank 15to increase friction of the shankwith the upper bag panel 16. As shown,the hole 10 inthe upperwall ofthe anvil block9 is largerin cross-section than the pin 15, with the resultthat both thetop bag panel 16 and the lower bag panel 17 can enterthe hole 10 as the pin descends.

When the pin lifts, the material of the top bag 16 adheres to the surface ofthe pin shank 15, but slips relative to the material ofthe lower panel 16, with the resultthatthe upper panel lifts with the pins to initiate the opening action, as shown in Figure 3. As the pin retracts from this large hole 10, it has a better grip on thetop panel 16than on the lower bag panel 17. Itis therefore well able to open an unlipped bag (i.e. one having the upper and lower panels 16 and 17 co-extensive) as illustrated in Figures 2 and 3.

The lower panel 16 is of course held down bythe adhesion to the tape 3 (not shown in Figures 2 and 3) but may be held down by any alternative system,well known in the art, for example suction as indicated above.

The roughening ofthe shank 15 ofthe pin 8a may, for example, be achieved by threading the shank, or by knurling the shank. Another possibilityfor increasing the grip of the pin 8a on the upper bag panel 16 isto provide a bulbous end to the pin,just above the maximum diameter part ofthe conical tip 14. Thus whereas the bag can readily be penetrated by the sharp tip 14 and then adopts a downwardly extending "sleeve" configuration around the pin,the lifting ofthe pin 8a uses this "downwardly extending sleeve" configuration to liftthetop bag panel 1 6with it and the lifting is enhanced by virtue ofthis bulbous formation (not shown)justabove the tip 14.

Figure 4, shows a two part pin 8b intended for bags having an extended upper lip. This pin comprises a collar 18 freely slidable about a plain shank 19 ofthe pin and resiliently connected to the pin carrier 7 by means of a helical spring 20.

The pin has, atthe bottom ofthe shank 19, an external annular channel 21 bounded at one side by the shank 19 and atthe other side by a conical tip portion 22 ofthe pin terminating atthe pin point.

As the pin descends, the conical tip 22 penetrates the upper bag panel 16 and enters the hole 10 in the upperwall ofthe anvil block 9. As this timethe material ofthe upper panel 16 immediately surrounding the hole formed in it by penetration of the tip 22 forms a downwardly extending sleeve structure extending into the channel 21 ofthe pin.

Asthetip22 penetratesthe upper bag panel 16,the spring-biased collar 18 presses yieldably down againstthe top panel 16. During further descent ofthe pin carrier7, the tip 22 and the channel 21 achieve the Figure 4 configuration, while the collar 18 retains its position of pressing yieldably down on to the top panel 16.

As the pin carrier7 rises, the shank 19 and the tip 22 begin to retract, as shown in Figure 5, while the collar 18 remains in contact with the top panel 16. During further ascent ofthe pin 8b towards the Figure 5 configuration, the resilience of the spring 20 holds the collar 18 down in a position where the peripheral part ofthe upper panel 16 around the hole penetrated by the pin 8b becomes clamped between the back ofthe conical tip 22 (i.e. the lower wall of the channel 21) and the lowerface ofthe collar 18, thereby positively clamping the upper bag panel 16 in position and causing itto be lifted upon further ascent of the pin carrier 7.

Once the pin 8, 8a or 8b has reached its top position, pneumatic bag inflation will have taken over as the mechanism lifting the top bag panel 16, and subsequentlythetop bag panel 16 is separatedfrom the pin. Separation may be achieved by the action of ripping the bag 2 off the pins 3 as the product is inserted, or by any other mechanism for example retracting the pin into the collarto shed the bag panel 16. Any unsightly holes in thetop bag panel 16 resulting from separation will be in the bag region adjacentthemouthandconsequentlywill bestripped from the bag during a subsequenttrimming operation as is conventional in the art of bagging.

Separation by retracting the pins 8b into the collars 18 has the advantagethattheseparation can be accurately timed in the bag opening cycle.

Alternatively, the bag need not be opened by inflation as the pins rise. For example, the opened bag may be transferred mechanically, possibly still carried on the pins 8, 8a, 8b, to a bag loading location from the bag opening location. Alternatively the bag opener may be used to open the bags, simplyfor unsticking the bags which may then be allowed to reclose.

During tests carried out with pins ofthe type shown in Figure lit was found that the bag opening action was notdependentupon variations inthe bag condition,such as oxidation drying,the presence of moisture, orthe presence ofsurfacewrinkles.

As a further test of the apparatus in accordance with the present invention,the embodimentof pins shown in Figures 2 and 3 and in Figures 4and Swere used with several different types of bags, with very high success rates. In one test, the interior ofthe bags waswetted,to cause the lips to adhere together, and in anothertestthe bag lips were closed on to 1 cm square pieces of double-sided adhesivetapecloseto the entry point of the pins, in orderto simulate lip sticking. In each case, the pins of Figures 2 and 3 and 4 and 5 were able to open the bags reliably.

Afurther possibility which has been successfully tested on "lipped" bags uses the configuration in which it is the upper panel 16 which has the lip, and which therefore adherestothetapes by its inwardly facing surface. The reliability of the opening action of the present invention is such that it may in practice by desirableto mountthe bags on the cardertapes in this inverted configuration so that each bag has a' known sticking action which has to be overcome on opening. It is from time to time found that with unlipped bags, intended to be adhered to the tapes by one wall panel only,theshifting ofthe upper (i.e.

non-adhered) panel relative to the lower panel may result in it sticking to the tape, thus making some bags more difficultto open than others in the same chain.

Claims (13)

1. Apparatus for opening packaging bags, comprising means for supporting a packaging bag in a flat configuration, a penetrating member driven for movementtowards and through theflat held bagto penetrate at least one wall of the bag while the penetrating member is moving in a first direction; means for reversing the movement of the penetrating member after penetration ofthe bag material; and means for holding down that one of said panels on the side of the bag remote from the position ofthe penetrating membertowards which it retracts during its reversed movement.

2. Apparatus according to claim 1,wherein there aretwosaid penetrating members.

3. Apparatus according to claim 1 or claim 2, wherein the or each said penetrating member is a pin having a sharp point.

4. Apparatus according to claim 3, wherein said pin has a roughened shank.

5. Apparatus according to claim 4,wherein said roughened shank is formed by threading the pin shank.

6. Apparatus according to claim 3 or4, wherein said pin has a maximum diameter portion close to the tip end ofthe pin, defining the bulbous partofthe pin intended to penetrate said at least one panel of a bag supported by the bag supporting means.

7. Apparatus according to any one of claims 3 to 5, wherein said pin has a reduced diameter portion between the tip and the major part ofthe shank, defining a channel into which bag material may resiliently move.

8. Apparatus according to claim 7, wherein the tip portion of the pin on the side of said reduced diameter portion remote from the said major part ofthe shank comprises a conical tip portion having the base ofthe cone ofthe same diameter as the said remainder of the shank.

9. Apparatus according to claim 7 or claim 8 and including a collarfitting closely around said remainder ofthe shank, and slidable relative to the shank.

10. Apparatus according to claim 9, and including meansyieldablyconnectingthesaidcollartothe shank for resilient biasing ofthecollartowardsthetip end of said pin.

11. Apparatus according to any one ofthe preceding claims, and including means for adjusting the line of action of the or each penetrating member.

12. Apparatus according to any one ofthe preceding claims, wherein said bag supporting means comprises a bag supporting surface having an anvil surface for penetration by said penetrating member after penetration of the bag to be opened.

13. Apparatus according to claim 12when appendenttoclaim 1 1, and including means for adjusting the position of the or each hole in the anvil to accommodate the change in position of the or each said piercing member.

13. Apparatus according to claim 12when appendentto claim 11, and including means for adjusting the position of the or each hole in the anvil to accommodate the change in position of the or each said penetrating member.

14. Apparatus according to anyone ofthe preceding claims, and including means for carrying the opened bag away from said bag support means fortransportto a bag loading location.

15. Bag opening apparatus constructed and adapted to operate substantially as herein before described, with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1 to 3 and 11 to 13 above have been deleted ortextuallyamended.

(b) New ortextually amended claims have been filed asfollows:

1. Apparatus for opening packaging bags, comprising meansforsupporting a packaging bag in a flat configuratiori, a piercing member driven for movementtowar is and through the flat held bag to penetrate at least one wall of the bag while the piercing member is moving in a first direction; means for reversing the movement of the piercing member after penetration of the bag material; and meansfor holding down that one of said panels on the side of the bag remote from the position ofthe piercing membertowardswhich it retracts during its reversed movement.

2. Apparatus according to claim 1,whereinthere are two said piercing members.

3. Apparatus according to claim 1 orclaim2, wherein the or each said piercing member is a pin having a sharp point.

11. Apparatus according to any one ofthe preceding claims, and including meansforadjusting the line of action of the or each piercing member.

12. Apparatus according to any one ofthe preceding claims, wherein said bag supporting means comprises a bag supporting surface having an anvil surface for penetration by said piercing member after penetration of the bag to be opened.