Packaging apparatus

Abstract: A sealing and stripping assembly 10 for a packaging apparatus, the assembly includes two shafts 16 which are held in a spaced generally parallel co-extensive relationship with an arm 15 extending from each shaft, and co-operating pairs of closing and stripping bars 21, 22 mounted on the radial extremity of each arm 15 so as to engage a bag material passing through the assembly so as to seal and strip same during a packaging operation, with said arms 15 being driven in synchronism and in opposite rotational directions.

Description: The present invention relates to packaging apparatus and more particularly but not exclusively to packaging apparatus to package food products such as potato crisps. In the packaging of many products, bag material is delivered, to a sealing head, in tubular form. The product to be packaged, is delivered to the sealing head and is located within the bag material. The bag material is sealed transverse of its longitudinal direction of extension, and then the material is located within the bag material. Thereafter, the tube is closed, a stripping apparatus condenses the volume occupied by the product to be packaged, and the bag material again sealed, so that the packaged material is located within a discrete bag. The bag is then severed from the tubular bag material. This packaging operation is generally intermittent, that is not continuous. It is a disadvantage of known apparatus that the sealing, closing, stripping and severing of the bag is achieved by relatively complex apparatus which increases the cost of the machine as well as rendering the machine unreliable. Additionally these known apparatus operate intermittently, and accordingly are slow. GB 1 456 882 discloses a method of controllably disseminating into the atmosphere a substance which is normally flowable under atmospheric pressure which is vaporizable under atmospheric condition. The method of '882 comprises the steps of forming a chamber having a flexible wall part and a wall portion of plastic material, supplying into the chamber under a atmospheric pressure conditions a quantity of said flowable substance, and hermetically sealing the chamber under gas-free conditions. The substance thereafter travels through the plastics material and, at the outer surface thereof evaporates into the atmosphere. US-A-3 850 780 to Crawford et al teaches an extended dwell heat sealer wherein a modified rotary motion is imparted to heated sealing jaws on counter-rotating shafts straddling a web to be sealed. Therefore, the jaws are directed along a linear path while in sealing engagement with the web. Each sealing jaw support is provided with follower rollers engaged with stationary cams coaxially located relative to an adjacent cutting head shaft. The drive train incorporates a cam for providing a constant velocity for the sealing jaws when engaging the web. US-A-3045404 (Wilson) describes a wrapping machine for packing loose articles of a type which create impact on newly created heat seals transverse of the tubular bag material. In this machine, heated jaws are mounted on a pair of counter-rotating shafts so as to contact the bag material periodically and produce the seals. To protect the seals against damage when the articles fall into the package which is being produced the shafts also carry helical springs which contact the bag material just after the formation of a seal and then move away to permit the product to descend against the seal. US-A-2915866 (Bartlo) describes a packaging machine which uses sealing dies which reciprocate up and down and also move transversally of a tubular bag material therebetween to clamp and release the material. The dies produce seals across the bag material and also draw the bag material on to produce the next package. To package bulky lightweight products, like potato chips, the machine employs stripper rods which are carried on spring-loaded levers pivotably mounted on bearing blocks connected with brackets to the dies. During operation, as the dies approach the bag material by moving linearly towards one another the stripper rods contact the bag material first and the levers are caused to pivot on the bearing blocks against the spring force to compress the product and remove product from the zone over which the seal is to be created by the dies. US-A-3070931 (Zwight) describes a packaging machine for packing free flowing light products, such as potato chips. The machine employs a frame which is reciprocated up and down and supports movable jaws which pivot angularly relative to the frame. On the jaws, there are mounted retractable shafts supporting strippers, upper and lower heat sealers and a knife. During operation, the jaws are swung upwardly away from the tubular bag material as the frame moves linearly upwardly and then the jaws are swung inwards towards the bag material to cause the heat sealers to engage on the bag material to create a transverse bottom seal for the package to be formed. The entire frame with the jaws is then moved linearly downwardly by the length of the package to be formed to draw the bag material downwardly and the jaws are swung upwardly away from the bag material again. Product is now dispensed into the partly-formed package. The jaws are next swung inwards towards the bag material to cause the strippers to compress the product into the partly formed package prior to engagement with the sealers. The lower sealers now produce the top seal for the package and the knife separates the package. As mentioned above reciprocal motion , e.g. of the frame of Zwight necessary to advance the bag material and the to and fro pivotal or swinging movements e.g. of the jaws of Zwight are inherently intermittent and slow. According to the invention there is provided a stripping and sealing assembly, for packaging apparatus, said apparatus including a product delivery head and a drive assembly to pass tubular bag material past said delivery head so that product delivered from said head is located within said tubular bag material, said stripping and sealing assembly including a pair of opposing sealing and stripping means located on opposite sides of said bag material at a position downstream from said delivery head relative to the direction of movement of said bag material through said apparatus, said sealing and stripping means being adapted to cooperate to sealingly close portions of said bag material and strip same, a first arm means supporting one of said sealing and stripping means and a second arm means supporting the other sealing and stripping means a pair of generally parallel rotatably driven shafts from each of which there extends radially outwardly therefrom one of the arm means cutting means mounted so as to be adjacent the extremities of the arm means and adapted to cooperate to sever said sealed portions from said bag material to thereby form discreet bags of said product and wherein each sealing and stripping means includes co-operating stripper bars which strip the bag material wherein the arm means via said shafts are rotatably driven continuously through complete revolutions in synchronism in opposite directions about spaced parallel fixed axes extending generally transverse of the direction of movement of the bag material so that prior to sealing said bag material the sealing and stripping means are moved along said bag material to cause the stripper bars to strip same, and wherein each arm means is provided with one of the stripper bars, and the assembly further includes pivotable supports for each stripper bar pivotally mounting the stripper bars relative to said arm means so as to provide for relative movement therebetween. Preferred forms 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 view of a sealing, closing and stripping assembly in operation; Figure 2 is a schematic part sectioned side elevation of the sealing, closing and stripping assembly of Figure 1; Figure 3 is a schematic plan view of the sealing, closing and stripping assembly of Figure 2; Figure 4 is a schematic part sectioned side elevation of a further sealing, closing and stripping assembly to that of Figure 1; and Figure 5 is a schematic plan view of a portion of the sealing, closing and stripping assembly of Figure 4. In Figure 1 there is schematically depicted a stripping, closing and sealing assembly 10 to be employed in a packaging machine. The assembly 10 operates in a rotary manner and accordingly can operate on a continuous basis. The packaging machine has a product delivery head which delivers product 11 to the interior of a tubular bag material 12. The sealing, closing and stripping assembly 10 strips the bag material 12 and severs discrete bags 13 from the bag material 12. The assembly 10 includes two opposing sealing, closing and stripping heads 14 which are each mounted on an arm 15 fixed to a shaft 16. The shafts 16 are rotatably driven in opposite directions and have the same angular velocity. The heads 14 are pivotally mounted on the end of each arm 15 as well as being movable longitudinally of their respective arm 15. The sequence of operation of the above described assembly 10 is as follows. Firstly, the tubular bag material 12 is driven past a product delivery head so that the product 11 is delivered to the interior of the tubular material 12. The heads 14 engage the material so as to sealingly close the bag material 12 at a particular position. For example, in position A, the heads 14 are engaging the material 12 and are severing the bag 13 therefrom. Once the bag 13 has been formed and is allowed to fall freely from the assembly 10, the arms 15 rotate to the position B. Thereafter the heads 14 are forced into engagement with the bag material 12 so as to bring the bag material 12 together for stripping and sealing. The two heads 14 are moved toward each other and are moved in the direction of movement of the material 12 at a velocity greater than the velocity of the material 12. Accordingly, the heads 14 will cause stripping of the bag material 12 to thereby reduce the volume occupied by the product 11. Upon the heads 14 reaching a predetermined position, the bag material 12 is sealed so that a fresh bag is thus formed and severed from the remainder of the material 12. Turning now to Figures 2 and 3 wherein the stripping, closing and sealing assembly 10 is more fully depicted. The heads 14 are mounted on a carriage 17 which is telescopically located on the shaft 15, More particularly, the carriage 17 is spring biased by the spring 18 to a position at the radially outer end of the arms 15. Each of the carriages 17 has an arm 19 to which the heads 14 are pivotally attached by means of pins 20. Each head 14 is provided with a closing bar 21 and a stripper bar 22. Surrounding the shafts 16 are two cam tracks 23 which have a curved portion 24 and a linear portion 25 extending generally parallel to and adjacent to the bag material 12. Each of the heads 14 is provided with a pair of cam followers 26 which engage the cam track 23 so that in cooperation therewith the heads 14 follow a predetermined path. The cam followers 26 are eccentrically mounted so that the distance between the heads 14 is adjustable. Accordingly, in operation, the heads 14 follow a generally linear path defined by the linear portion 25 of the cam track 23 while the bag material 12 is engaged. Thereafter, the heads 14 move from contact with the bag material 12 and follow the curved portion 24 of the cam track 23. Upon reaching the terminal end of the curved portion 24, the heads 14 move to the position C depicted in Figure 2. Once in this position, the closing bars 21 will contact the bag material 12 prior to the stripping bars 22. Upon the bag material 12 being engaged, the heads 14 are driven at a speed faster than the bag material so that the product 11 in the bag material 12 is compacted. As the heads 14 reach the position D depicted in Figure 2, the bag material 12 is sealed and the newly formed bag 13 severed from the bag material 12. On the radially outer end of one of the arms 15 there is provided a knife 27 which severs the bag material 12 to release the bag 13 while additionally, the radially outer ends of the arms 15 operate as sealing jaws in that they are heated so as to sealingly close the bag material 12 prior to the bag 13 being severed from the material 12. It should be appreciated that other means apart from heating could be used to seal the bar, such as the use of adhesives. In Figures 4 and 5 there is schematically depicted a sealing, closing and stripping head assembly 40 including a pair of opposing closing and stripping heads 41 and 42 mounted on two rotatably driven shafts 43 and 44 which are driven in opposite directions and at the same angular velocity. Each assembly includes a pair of arms 45, with each pair of arms 45 being provided at its radially outer extremity with a knife assembly 46, which assembly 46 are also heated in order to seal the bag material passing therethrough in a similar manner to the assembly 10 described with reference to Figures 1 to 3. The arms 45 extend radially from the axis of rotation of the respective shaft 43 or 44. Each of the arms 45 is provided with a support 47 or 48, which supports 47 and 48 receive tube closing and stripper bars 49 to 52. The stripper bars 49 and 50 being supported respectively by arms 55 and 53, and tube closer bars 51 and 52 being supported respectively by arms 56 and 54. Each of the arms 53 to 56 is supported by a pivot assembly 57 which allows rotation of each of the arms 53 to 56 about an axis fixed relative to its associated arm 47 or 48. Additionally, the pivot assemblies 57 resiliently bias the arms 53 to 56 to a position relative to their supports 47 and 48, as depicted in "ghostlines" in Figure 4. The stripper and tube closer bars 49 and 51 are both provided with a plug member 58 while the stripper and tube closer bars 50 and 52 are provided with a socket member 59. During movement of the two pairs of arms 45 when the stripper bars 49 and 50, and tube closer bars 51 and 52 are engaged during a stripping action relative to the tubular bag material,the associated pairs of plug members 58 and socket members 59 are engaged. This ensures that the pairs of stripper bars 49 and 50, and tube closer bars 51 and 52 are held in the correct relative positions. As the arms 45 rotate and the stripper bars and tube closer 49 to 52 approach each other, each pair of stripper bars 49 and 50, and tube closer bars 51 and 52 are located adjacent each other in order to inhibit the location of any product between the two pairs of stripper bars. Once the stripper bars are engaged, further rotation of the arms 45 causes the two pairs (51, 52 and 49, 50) of stripper and tube closer bars to separate longitudinally of the bag material to thereby provide a space of bag material which is free from product, which space of bag material is then engaged by the assemblies 46. This ensures that when the individual bags are sealed and removed from the tubular material there is no product which would hinder sealing and separation. To provide the stripping action, at least the two bars 49 and 50 would have a velocity greater than the velocity of the tubular bag material while in contact therewith. Preferably all four bars 49 to 52 would have a velocity greater than the bag material.

Claims: A stripping and sealing assembly, for packaging apparatus, said apparatus including a product delivery head and a drive assembly to pass tubular bag material (12) past said delivery head so that product delivered from said head is located within said tubular bag material (12), said stripping and sealing assembly including a pair of opposing sealing and stripping means (14, 40, 41, 42) located on opposite sides of said bag material (12) at a position downstream from said delivery head relative to the direction of movement of said bag material (12) through said apparatus, said sealing and stripping means (14, 40, 41, 42) being adapted to cooperate to sealingly close portions of said bag material (12) and strip same, a first arm means (15, 45) supporting one of said sealing and stripping means (14, 40, 41, 42) and a second arm means (15, 45) supporting the other sealing and stripping means (14, 40, 41, 42), a pair of generally parallel rotatably driven shafts (16, 43, 44) from each of which there extends radially outwardly therefrom one of the arm means (15, 45), cutting means (27, 46) mounted so as to be adjacent the extremities of the arm means (15, 45) and adapted to cooperate to sever said sealed portions from said bag material (12) to thereby form discreet bags of said product and wherein each sealing and stripping means (14, 40, 41, 42) includes co-operating stripper bars (22, 49, 50) which strip the bag material (12); wherein the arm means (15, 45) via said shafts (16, 43, 44) are rotatably driven continuously through complete revolutions in synchronism in opposite directions about spaced parallel fixed axes extending generally transverse of the direction of movement of the bag material (12) so that prior to sealing said bag material (12) the sealing and stripping means (14, 40, 41, 42), are moved along said bag material (12) to cause the stripper bars (22, 49, 50), to strip same, and wherein each arm means (45) is provided with one of the stripper bars (22, 49, 50), and the assembly further includes pivotable supports (19, 20, 53, 55, 47, 48, 57) for each stripper bar (49, 50) pivotally mounting the stripper bars (49, 50) relative to said arm means (15,45) so as to provide for relative movement therebetween. The assembly of Claim 1, wherein the sealing and stripping means (40, 41, 42) further includes a pair of tube closing bars (51, 52) with a first one of the closing bars (51) being mounted on said first arm means (45) and the other closing bar (52) being mounted on said second arm means (45) so as to cooperate in closing said tubular bag material (12) at a position upstream thereof relative to said stripper bars (49, 50), further support arms (54, 56) for said closing bars (51, 52), the support arms (52, 53, 54, 55) for said closing and stripper bars providing for separating relative movement between said closing and stripper bars (49, 50, 51, 52) during closing and stripping of said tubular material (12), with at least said stripper bars (49, 50) having a velocity greater than the bag material (12) and greater than the velocity of the closing bars (51, 52) while in contact with the tubular material (12). The assembly of Claim 2, further including a pair of support members (47, 48) fixed to their associated shaft (43,44), and wherein said support arms (53, 54, 55, 56) pivotally attach the associated stripper and closing bars (49, 50, 51, 52) to said support members (47, 48), and means biasing each support arm (53, 54, 55, 56) to a predetermined position relative to its associated support member (47, 48). The assembly of Claim 3, wherein the support arms (53, 54, 55, 56) pivot about axes parallel to said shafts (43, 44), with the support arm axes being spaced from each other both angularly and radially relative to the associated shafts (43, 44). The assembly of Claim 1, wherein each sealing and stripping means includes a closing and stripping head (14), with each head (14) having a closing bar (21) and one of the stripping bars (22) extending generally transverse of the tubular bag material (12). The assembly of Claim 5, further including a first mounting means pivotally attached to the radial extremity of said first arm means (15) and supporting one of the closing bars (21) and one of the stripping bars (22) in a spaced fixed relationship relative to each other and a second mounting means pivotally attached to the radial extremity of the other arm means (15) and supporting the other closing bar (21) and other stripping bar (22) in a fixed relationship relative to each other. The assembly of Claim 6, wherein each mounting means is resiliently biased to a predetermined working relationship so that the closing bars (21) engage the bag material 12) first relative to the stripping bars (22). The assembly of Claim 7, wherein said arm means (15) are rotatably driven so that said heads (14) have a velocity greater than the velocity of said tubular bag material (12) when engaged therewith, prior to sealing. The assembly of Claim 8, further including track means (24) to guide said heads (14) during operation thereof. The assembly of Claim 9, wherein each mounting means is radially movable relative to its associated supporting arm means (15).

Inventors: TAYLOR ALFRED ALEXANDER, TAYLOR, ALFRED ALEXANDER
Applicants: TAYLOR ALFRED ALEXANDER, TAYLOR, ALFRED ALEXANDER
Application year: 1985
Main classification: B65B9
IPC codes: B65B51, B29C65, B65B9