Stripper for pacaging machines

Abstract: A rotary packaging machine employs a pair of co-operating strippers bars (17) which engage the bag material (15) prior to the sealing jaws (16) engaging the bag material (15). The stripper bars (17) have attached to them or formed integral therewith, bag shields (30). The bag shields (30) are arcuate so as to generally extend along an arcuate path having a fixed axis extending from the pivot axis (32) of the supporting lever (26) for the stripper bar (17).

Description: Technical Field The present invention relates generally to packaging machines and to packaging machines of the type employing "strippers". The invention is particularly concerned with a stripper member or mechanism and to a stripping and sealing assembly for use in such machines. Background of the Invention A packaging machine as described in US-A- 4 663,917 has co-operating stripper bars which remove product from the "seal area" and strip the packaging material in order to reduce the volume occupied by the product being packaged. Also closer bars are employed so that there is a length of package within which there is no product, and which is engaged by the sealing jaws. The stripper bars are mounted on rotatably driven arms, with the arms rotating in opposite directions about parallel transversely spaced axes. Both arms rotate "continuously" in their respective angular directions. The above discussed stripper bars move along the bag material to remove any product which may be located in the area to be engaged by the sealing jaws. However, it is a disadvantage of the stripper bars that flanges extend from the bars to engage the bag material to ensure that apart from the stripped length of bag material, the bag material does not engage the sealing jaws. The previously known stripper bars and associated flanges suffer the disadvantage that they further reduce the volume available for the product. Object of the Invention It is the object of the present invention to overcome or substantially ameliorate the above disadvantages. EP-A-0182505 discloses a packaging machine of a non-rotary type. Instead this machine adopts reciprocating movements and uses sealing jaws and stripper jaws which move inwardly and outwardly relative to the bag material. Such a machine does not require shielding. Summary of the Invention The invention also there is provided a stripper member for a stripping and sealing assembly of a rotary packaging machine, said stripper member comprising: a pair of spaced stripper levers with each lever having a first end, and a second end, the first ends of the levers providing for pivotal movement of the mechanism about a pivot axis, a stripper bar extending between the second ends of the levers; and a arcuate bag shield formed integral with or attached to the stripper bar, said shield extending from said stripper bar and having an outer surface radially spaced from said axis by a substantially fixed radius, and an inner surface conforming substantially to said outer surface. The invention also provides a stripping and sealing assembly for a rotary packaging apparatus as defined in claim 2. Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a schematic side elevation of a portion of bag material being stripped, sealed and cut; Figure 2 is a schematic side elevation of a portion of the packaging machine performing the function schematically depicted in Figure 1; Figure 3 is a schematic side elevation of the packaging machine portion illustrated in Figure 2; Figure 4 is a schematic front elevation of the stripper bar and bag shield of Figures 1,2 and 3; and Figure 5 is a schematic side elevation of the stripper bar and bag shield shown in Figure 4. Detailed Description of the Preferred Embodiment In the accompanying drawings there is schematically depicted the portion 10 of a packaging machine. The packaging machine is a rotary machine in that it has a pair of arms 11 which rotate about transversely spaced parallel axes 12 defined by spaced parallel shafts 13. The machine may be constructed in accordance with US-A-4,663,917. The shafts 13 are stationary in respect of their position in the machine, but they rotate continuously in opposite angular directions repeatedly through 360°. The packaging machine has a product delivery head which deliver product 14 to the interior of tubular bag material 15. The bag material 15 is driven, by, for example, the machine shown in US-A-4,910,943. The machine strips and closes the bag material as well as seals the bag material and cuts each bag from the tubular material as it is formed. The sequence of operations is as follows. Firstly, the tubular bag material 15 is driven passed a product delivery head so that product 14 is delivered to the interior of the tubular bag material 15. Thereafter, a pair of co-operating stripper bars 17 (one on each side of the tubular bag material 15) move down the tubular bag material so as to reduce the volume occupied by the product 14. A length of tubular bag material 18 is then ready to be engaged by the sealing jaws 16. However, a pair of tube closer bars 19 located above the stripper bars 17 engage the tubular bag material 15 to prevent further product coming down the tubular bag material 15 to the tubular length 18. The sealing jaws 16 engage the length 18 in between the stripper bars 17 and closer bars 19. Preferably, one of the sealing jaws 16 would be provided with a knife so as to cut discrete lengths of bag material 15 to provide a complete bag 20. It should be appreciated that each portion 10 includes an arm 11 as well as a stripper bar 17 and a closer bar 19. The portions 11 are located on opposite sides of the tubular bag material and co-operate to form discrete bags 20. The following description will be in respect of a single portion 10 only. The shaft 13 of the portion 10 is driven in the direction of the arrow 21. Mounted on the arm 11 is a pair of levers 22 of which only one is illustrated. The levers 22 are spaced in the direction of the axis 12 and support between them the stripper bars 17 and closer bars 19. Each lever 22 is attached to its associated arm 11 by a pivot pin 36. In this regard it should be appreciated that each arm 11 consists of two projections 24 which extend radially from the shaft 13. The projections 24 are spaced longitudinally of the shaft 13 and have the sealing jaw 16 extending therebetween. The sealing jaw 16 has a heated sealing element 25. Each lever 22 is fixed to an associated one of the projections 24. Pivotally mounted on each lever 22 is a stripper lever 26 with each stripper bar 17 extending between the associated pair of levers 26. The associated stripper lever 26 is generally parallel and co-extensive. Also pivotally mounted on each lever 22 is a closer lever 27, with the closer bar 19 extending between the associated pair of levers 27. The levers 26 are spring biased to move in the direction of the arrow 28 while the levers 27 are spring biased to move in the direction of the arrow 29. In this embodiment, the stripper bar 17 is integrally formed with or has fixed to it a bag shield 30. The bag shield 30 is arcuate and extends the length of the stripper bar 17 so as to extend across the bag material 15. The shield 30 has an arcuate outer surface 31 which extends angularly at a substantially fixed radius about the axis 35 about which the lever 26 pivots. Preferably, the concave surface 32 would closely conform to the configuration of the surface 31 so that the shield 30 generally follows an arc having its radius extending from the axis 35. The surface 31 has its radius extending from the axis 35 so that the stripper bar 17 can engage the bag material 15 as close to the sealing jaws 16 as possible. By having the surface 31 curved with a generally fixed radius extending from the axis 35, movement of the sealing jaws 16 toward and away from the bag material 15 will not result in unwanted contact between the shield 30 and the sealing jaws 16. Still further, by having the shield 30 shaped as discussed above, the bag 20 is permitted to assume a shape which maximises the volume available to the product 14 yet ensuring that there is sufficient length 18 for the sealing jaws 16 to properly engage the bag material 15. It should be appreciated that in Figure 2, the sealing jaws 16 are depicted at the position in which the jaws 16 are sealing the bag material and cutting the bag material 15. In Figure 3, the sealing jaws 16 are depicted prior to the position depicted in Figure 2. The above-mentioned stripper bar 17 and bag shield 30 are more fully depicted in Figures 4 and 5. In the present instance the stripper bar 17 and bag shield 30 are integrally formed. The stripper bar 17 and bag shield 30 are attached to the extremities of the levers 26 by means of shafts 34. The bar 17, bag shield 30 and levers 26 provide a stripper member 33. Accordingly the stripper member 33 has a leading portion providing the stripper bar 17 from which leading portion there rearwardly extends the bag shield 30. Extending laterally are the two shafts 34 which enable the stripper member 33 to be attached to the extremities of the levers 26 for pivoting movement about the axis 35 as is best seen in Figure 3.

Claims: A stripper member (33) for a stripping and sealing assembly of a rotary packaging machine, said stripper member (33) comprising: a pair of spaced stripper levers (26) with each lever (26) having a first end and a second end, the first end providing for pivotal movement of the stripper member (33) about a pivot axis, a stripper bar (17) extending between the second ends of the levers (26); and a bag shield (30) formed integral with or attached to the stripper bar (17), characterised in that said bag shield (30) is arcuate and extends from said stripper bar (17); said bag shield (30) having an outer surface (31) radially spaced from said pivot axis by a substantially fixed radius, and an inner surface (32) conforming substantially to said outer surface (31). A stripping and sealing assembly for a rotary packaging apparatus, said apparatus including a product delivery head and a drive assembly to move tubular bag material (15) past said delivery head so that product delivered from said head is located within said tubular bag material (15), said stripping and sealing assembly including a pair of opposing sealing and stripping means (16,17) to be located on opposite sides of said bag material (15) at a position downstream from said delivery head in the direction of movement of said bag material (15) through said apparatus, said sealing and stripping means (16,17) being adapted to co-operate to sealably close portions of said bag material (15) and strip same prior to sealing, a first arm means (11) supporting one of said sealing and stripping means and a second arm means (11) supporting the other sealing and stripping means, a pair of generally parallel rotatably driven shafts (13), located on opposite sides of said bag material (15), from each of which there extends radially outwardly therefrom a respective one of the arm means (11), each sealing and stripping means including a sealing jaw (25) and a pair of stripper members (33) each according to claim 1 with the stripper bars (17), co-operating to strip the bag material (15) prior to the jaws (25) sealably engaging the bag material (15),and wherein the arm means (11) via said shaft (13) are rotatably driven continuously through complete revolutions in synchronism in opposite directions about spaced parallel stationary axes extending generally transverse of the direction of movement of the bag material (15) so that prior to sealing said bag material (15) the stripping and sealing means are moved along said bag material (15) to cause the stripper bars (17) to strip same, the stripper levers (26) serving to pivotably mount the stripper bars (17) on their supporting arm means (11) so as to provide for relative movement between each stripper bar (17) and the associated arms means (11) about the pivot axis, each stripper member (33) being mounted to its respective arm means (11) so that the shields (30) extend away from one another in opposite directions from their respective stripper bars (17) and the arcuate outer surface (32) of each shield (30) faces the respective sealing jaw (25), when the stripper bars (17) are engaged with the bag material (15). A rotary packaging machine incorporating the stripper mechanism of claim 1 or the stripping and sealing assembly of claim 2.

Inventors: TAYLOR ALFRED ALEXANDER, TAYLOR, ALFRED ALEXANDER
Applicants: TAYLOR ALFRED ALEXANDER, TAYLOR, ALFRED ALEXANDER
Application year: 1995
Main classification: B65B51
IPC codes: B65B51, B29C65