Film drive assembly

Abstract

A drive assembly (17) to move tubular bag material past a former and deliver a tubular bag material to a packaging machine. The drive assembly (17) includes a pair of drive belts (6) that are parallel and driven in unison by means of a drive pulley (29) and either pulleys (30, 31).

Claims

1. In combination, a former shoulder and a film drive assembly to engage strip film material to move the strip film material downwardly past the former shoulder to form tubular bag material having longitudinally extending edge portions forming a longitudinal seal, the film drive assembly comprising: a loop drive belt having a drive surface to frictionally engage the tubular bag material, the loop drive belt moving along a polygonal path including a first path portion along which the drive surface engages the tubular bag material, the loop drive belt having a plurality of passages extending transversely through the loop drive belt from said drive surface; at least one manifold to be subjected to a reduced air pressure and communicating with the passages for at least a part of said first path portion so that the passages are subjected to a reduced air pressure so that a difference in air pressure across the tubular bag material urges the tubular bag material against said drive surface; a drive pulley engaged with the loop drive belt to cause the loop drive belt to move along said polygonal path in a predetermined direction; a plurality of belt engaging devices, wherein said first path portion is defined as a linear section of said polygonal path that is disposed directly between a first one of the belt engaging devices on an upstream end of the first path portion, and said drive pulley on a downstream end of said first path portion, wherein an entirety of the first path portion is linear and configured and disposed to engage the tubular bag material, wherein the belt engaging devices cooperate with each other and with the drive pulley to provide a second path portion and a third path portion, with the second and third path portions cooperating with said linear first path portion to provide the polygonal path; a backing bar located internally of the tubular bag material; and a heating bar at said first path portion urged toward the backing bar to engage the tubular bag material between the heating bar and backing bar to form the longitudinal seal.

2. The combination of claim 1, wherein said plurality of belt engaging devices further comprises a second belt engaging device.

3. The combination of claim 2, wherein the first and second belt engaging devices are pulleys.

4. The combination of claim 2, wherein the second and third path portions are linear.

5. The combination of claim 2, wherein said loop drive belt is a first loop drive belt, and said film drive assembly further comprises a second loop drive belt, the second loop drive belt being parallel to the first loop drive belt and including a second drive surface and a plurality of second passages extending transversely of the second loop drive belt from the second drive surface, with the second passages communicating with the manifold so that the second passages are subjected to the reduced air pressure to urge the tubular bag material into engagement with the second loop drive belt.

6. The combination of claim 5, wherein the second loop drive belt passes around the drive pulley, the first belt engaging device, and the second belt engaging device.

7. The combination of claim 6, wherein the drive pulley engages the first and second loop drive belts so the first and second loop drive belts are driven in unison.

8. The combination of claim 7, further comprising a heating bar at said first path portion to heat the tubular bag material and being urged into contact with the tubular bag material, the heating bar being located between the first and second loop drive belts.

9. The combination of claim 8, wherein said at least one manifold comprises a first manifold and a second manifold, the first manifold being operatively associated with the first loop drive belt to apply the reduced air pressure thereto, and said second manifold being operatively associated with said second loop drive belt to apply the reduced air pressure thereto.

10. The combination of claim 1, wherein the belt engaging devices are pulleys.

11. The combination of claim 1, wherein the second and third path portions are linear.

12. The combination of claim 11, wherein said loop drive belt is a first loop drive belt, and said film drive assembly further comprises a second loop drive belt, the second loop drive belt being parallel to the first loop drive belt and including a second drive surface and a plurality of second passages extending transversely of the second loop drive belt from the second drive surface, with the second passages communicating with the manifold so that the second passages are subjected to the reduced air pressure to urge the tubular bag material into engagement with the second loop drive belt, the second loop drive belt passes around the drive pulley and the belt engaging devices, the drive pulley engages the first and second loop drive belts so the first and second loop drive belts are driven in unison, and wherein the heating bar is located between the first and second loop drive belts, wherein said at least one manifold comprises a first manifold and a second manifold, the first manifold being operatively associated with the first loop drive belt to apply the reduced air pressure thereto, and said second manifold being operatively associated with said second loop drive belt to apply the reduced air pressure thereto.

13. The combination of claim 1, wherein said loop drive belt is a first loop drive belt, and said film drive assembly further comprises a second loop drive belt, the second loop drive belt being parallel to the first loop drive belt and including a second drive surface and a plurality of second passages extending transversely of the second loop drive belt from the second drive surface, with the second passages communicating with the manifold so that the second passages are subjected to the reduced air pressure to urge the tubular bag material into engagement with the second loop drive belt.

14. The combination of claim 13, wherein the second loop drive belt passes around the drive pulley and the belt engaging devices.

15. The combination of claim 13, wherein the drive pulley engages the first and second loop drive belts so the first and second loop drive belts are driven in unison.

16. The combination of claim 13, wherein the heating bar is located between the first and second loop drive belts.

17. The combination of claim 16, wherein said at least one manifold comprises a first manifold and a second manifold, the first manifold being operatively associated with the first loop drive belt to apply the reduced air pressure thereto, and said second manifold being operatively associated with said second loop drive belt to apply the reduced air pressure thereto.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

(2) FIG. 1 is a schematic isometric view of a former assembly and a drive to engage tubular bag material to pull the bag material past the former assembly;

(3) FIG. 2 is schematic side elevation of the former assembly and drive of FIG. 1;

(4) FIG. 3 is a schematic isometric view of a former shoulder of the former assembly of FIGS. 1 and 2;

(5) FIG. 4 is a schematic front elevation of the former shoulder of FIG. 3;

(6) FIG. 5 is a schematic side elevation of the former shoulder of FIG. 3;

(7) FIG. 6 is a schematic sectioned front elevation of the former shoulder as shown in FIG. 5 sectioned along the line 6-6; and

(8) FIG. 7 is a schematic top plan view of the former shoulder of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) In the accompanying drawings there is schematically depicted a former assembly 10. Previous former assemblies as disclosed in U.S. Pat. Nos. 712,459 and 7,415,809.

(10) The former assembly 10 includes a base 11 to which there is attached a frame 12 that supports a sleeve 13. The sleeve 13 encloses a generally upwardly extending passage 14 to which product is delivered in batches from a weighing machine such as that disclosed in U.S. Pat. No. 7,600,630 and European Patent Application 082909573. The sleeve 13 passes through a former shoulder 15 having an external former surface 16 to which strip film material 47 is delivered to be formed into a tubular configuration. Product is delivered to the passage 14 to be delivered to the interior of the tubular bag material 45. A packaging machine, such as that disclosed in U.S. Pat. No. 4,753,336, positioned below the drive assembly 17 transversely seals and cuts the tubular bag material 45 to form bags of product.

(11) The former assembly 10 may include ducting 46 to deliver an inert gas to the interior of the tubular bag material 45.

(12) The former shoulder 15 is more fully depicted in FIGS. 3 to 7. The shoulder 15 of this embodiment has the external surface 16 surrounding a generally central circular aperture 18 via which product is delivered to the interior of the tubular bag material. The sleeve 13 passes through the aperture 18 so as to project through the internal cavity 19 of the shoulder 15. The cavity 19 is surrounded by the internal surface 20 of the shoulder 15.

(13) In the above described preferred embodiment, the aperture 18 is generally circular. However in other embodiments, the aperture 18 may be generally square or rectangular, depending on the configuration of the bag being formed.

(14) The shoulder 15 is formed from a sheet of stainless steel bent around a generally central upright longitudinal axis 21, with the sheet terminating at a folded rear edge 22. The rear edge 22 is secured to a transverse member 23 of the frame 12. The axis 21 is the central axis of the aperture 18.

(15) Fixed to the internal surface 20 are heaters 24 that heat the external surface 16 over which the film bag material passes so as to be heated. The heaters 24 are located on opposite sides of the aperture 18, in particular the aperture 18 and axis 21 are located between the heaters 24. More particularly the heaters 24 are symmetrically arranged on opposite sides of the axis 21 and extend angularly about the axis 21. Each heater has a transverse width and a longitudinal length greater than the width. Each heater 24 extends longitudinally angularly about the axis 21.

(16) Heating of the tubular bag material 45 as it passes the former shoulder 15 has the advantage of reducing the length of the tubular bag material 45 that needs to be heated by the drive assembly 17. Accordingly the drive assembly 17 can be reduced in height.

(17) The heaters 24 may be electrical resistance heaters, that is the heaters 24 have an electrical resistance so that upon electric power being applied thereto, they are raised in temperature, therefore raising the temperature of the surface 16.

(18) The film bag material passing over the surface 16 is formed into a tubular form with overlapping longitudinal edges. The heaters 24 are located so as to heat the longitudinal edges of the bag material.

(19) Fixed to so as to be supported by the frame 12 is a backing bar 25. The backing bar 25 is located internally of the tubular bag material 45 so that the tubular bag material 45 is located between the backing bar 25 and the drive belts 26. The backing bar 25 may include a heater so that the overlapping longitudinally extending edge portions of the tubular bag material 45 are heated thereby.

(20) The belts 26 engage the tubular bag material 45 and cause the tubular bag material 45 to pass downwardly in the direction 27 past the former shoulder 15 for delivery to a packaging machine below the assembly 17. The packaging machine may be a packaging machine as disclosed in U.S. Pat. No. 4,753,336.

(21) The belts 26 are driven around a loop in the direction 28 by means of a drive pulley 29. The pulley 29 would be connected via shaft to a drive motor. The belts 26 pass about idler pulleys 30 and 31, with the belts 26 passing between the pulleys 29 and 30 along a linear path parallel to the backing bar 25 and axis 21.

(22) Located adjacent the backing bar 25 are vacuum manifolds 32 to which a vacuum is applied. The belts 26 have apertures (not illustrated) that communicate with the vacuum chambers provided by the manifolds 32, with the reduced air pressure being applied to one side of the tubular bag material 45 to urge the tubular bag material 45 into contact with the drive surfaces of the belts 36. The vacuum drive assemblies are shown in U.S. Pat. Nos. 7,124,559 and 4,910,943.

(23) Located between the manifolds 32 is a heating bar 33 that is electrically heated to again aid in raising the temperature of the tubular bag material 45 so that pressures applied to the tubular bag material 45 by the bar 33 and backing bar 25 will cause the longitudinal edge portions of the tubular bag material 45 to be fused so as to be sealingly connected. The bar 33 is urged toward the bar 25 by springs not illustrated.

(24) To drive the belts 26, the pulley 29 is provided with a plurality of drive teeth 36 that engage teeth 37 on the drive surface of the belts 26.

(25) The pulleys 30 and 31 provide belt engaging devices about which the belts 26 pass. In this embodiment, the belt engaging devices are pulleys.

(26) Passing from the pulley 31 to the pulley 29, the belts 26 pass along a first linear path portion 39, while from the pulley 29 to the pulley 30, the belts 26 pass along a second linear path portion 40, while from the pulley 30 to the pulley 31 the belts 26 pass along a third linear path portion 41. The path portions 40 and 41 are inclined to the path portion 39 by acute angles. Accordingly the path portions 40 and 41 have a direction of extension away from the path portion 39. It should be appreciated that in this embodiment there are three pulleys, 29, 30 and 31. However more pulleys may be employed thereby increasing the number of path portions.

(27) An advantage of the above described drive assembly 17 is that the distance between the rotational axes 34 and 35 of the pulleys 29 and 31 is reduced relative to previous machines as it is no longer necessary for the tubular bag material 45 to be heated over an extended length. To provide for this reduced distance between the axes 34 and 35 the further idler pulley 30 is required.

(28) The above described preferred embodiments of the present invention provide the advantage of reducing the overall length of the tubular bag material 45 between the aperture 18 and the packaging machine. It has been found that by reducing this length the product being packaged is maintained in batches having a shorter longitudinal length (a length parallel to the axis 21).