Packaging method and apparatus

Abstract

An apparatus for wrapping a stack of objects vertical side faces and a horizontal top face has a unit for wrapping a film wrapper around the stack such that respective sections of the wrapper extend upward from each of the side faces. A first welder welds ends the film wrapper together at one of the side faces of the stack. A fold-over device folding the film sections over onto the top face of the stack. A second welder welds the folded-over film sections together on the top face of the stack.

Claims

1. An apparatus for wrapping a stack of objects having, relative to a horizontal and longitudinal travel direction, first and second transversely spaced and vertical side faces extending parallel to the direction, a vertical front face transversely bridging front ends of the side faces, a vertical rear face transversely bridging rear ends of the side faces, and a horizontal top face extending between upper ends of the front, rear and side faces, the apparatus comprising: at least one conveyor for advancing the stack in the horizontal and longitudinal travel direction; means for wrapping a film wrapper around the stack such that respective first side, second side, front, and rear film sections of the film wrapper extend upward from the respective faces past the top face; a first welder for welding ends of the film wrapper at one of the faces of the stack; a fold-over device having first and second pairs of transversely spaced, parallel, and upright film-guide plates all extending parallel to the travel direction, the plates of each pair being transversely fixed to each other and jointly transversely movable from an outer position above the respective side face and with the first pair of guide plates confronting the second pair of guide plates perpendicular to the direction into an inner position with the two pairs of plates closely juxtaposed centrally above the stack, the two pairs of plates being so oriented that in the outer position the first and second side film sections project up from the respective first and second side faces of the stack past the top face and are received between the guide plates of the respective first and second pairs, the first and second pairs of plates being movable transversely of the direction toward one another from the outer position for pulling the respective first and second side film sections from between the respective plates and laying the first and second side film sections onto the top face of the stack; respective first and second fold-over members on the first and second pairs of film-guide plates and movable in the travel direction from downstream of the rear face to fold the rear film section over onto the top face of the stack; and a second welder for welding the folded-over film sections onto the top face of the stack.

2. The wrapping apparatus defined in claim 1, wherein in the wrapping means the film wrapper is arrayed as a film wrapper curtain extending transversely to the travel direction of the stack such that as the conveyor advances the stack through the wrapping means the film wrapper comes to rest against the front face and then against the lateral side faces of the stack.

3. The wrapping apparatus defined in claim 1, wherein the first welder includes at least two first welding bars that can be moved relative to each other to pinch the film wrapper together immediately downstream of the stack and weld the wrapper together at the rear side face of the stack.

4. The wrapping apparatus defined in claim 1, wherein the fold-over device is provided with the second welder for welding the folded-over sections of the film together on the top face.

5. The wrapping apparatus defined in claim 4, wherein the second welder includes a second welding bar.

6. The wrapping apparatus defined in claim 1, wherein the fold-over device folds back the first section projecting upward from the front side face against the travel direction, bends inward the first and second lateral sections projecting up from the lateral side faces transverse to the direction and toward each other, and bends the rear section projecting up from the rear side face forward in the direction.

7. The wrapping apparatus defined in claim 1, wherein the front section extending upward from the front face 3 is folded downward by engagement with downstream ends of the guide plates.

8. The wrapping apparatus defined in claim 1, further comprising: at least one welding bar engageable downward with the sections atop the top face.

9. The wrapping apparatus defined in claim 1, further comprising: welding bars for welding the film wrapper together downstream of the stack in a pair of vertical seams generally at a center of the rear side face such that one of the seams lies against the rear side face, and means for cutting the film wrapper between the pair of seams such that the other of the seams aligns with a center of the front side face of another stack moving in the direction.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a schematic perspective view of an apparatus for wrapping a stack 1;

(3) FIG. 2 is a schematic view of the apparatus of FIG. 1 in a first functional position; and

(4) FIGS. 3 to 10 are schematic views showing a top region of the apparatus according to the invention in the second through ninth steps of the method.

SPECIFIC DESCRIPTION OF THE INVENTION

(5) As seen in FIG. 1, an apparatus according to the invention for wrapping a stack 1 of objects, where a wrapping unit 2 for wrapping side faces 3, 4, 5, 6 of the stack 1 with a film wrapper 7 is provided. It can be seen in particular when comparing FIGS. 1 and 2 that the stack 1 in the wrapping unit 2 is preferably, and in this embodiment, fed against a film wrapper curtain 18 extending transversely to a horizontal travel direction D of the stack 1, so that the film wrapper 7 will initially make contact with the leading or front side face 3 and then the two lateral side faces 4 and 5 of the stack 1, which themselves extend vertically and parallel to the direction D. In this embodiment, the stack 1 is moreover transported by at least one conveyor 17 in the travel direction D into, through, and out of the wrapping unit 2. In this embodiment, the stack 1 is parallepipedal with a top face 11 as well as the four side faces 3, 4, 5, 6. Here, the stack 1 is transported on a pallet 25. Further, preferably and in this embodiment, the film wrapper 7 is a weldable thermoplastic film.

(6) In the travel direction D downstream of the stack 1 to be wrapped, a first welder 8 is provided in the form of two double welding bars 19 for welding two wrapper ends 9 at the trailing or rear side face 6 of the stack 1. Here, once the film wrapper 7 rests against the front side face 3 and on the lateral side faces 4 and 5 of the stack 1, the two double welding bars 19 of the first welder 8 are pivoted together. These double welding bars 19 are used to form a weld 24 between the two wrapper ends 9 to be welded on the rear side face 6 of the stack 1. Preferably the two double welding bars 19 of the first welder 8 are vertical and parallel to the vertical side edges of the stack 1. The bars 19 are doubled so as to form a second weld 27 at the same time as the first weld 26, and an unillustrated cutter is provided that severs the film between the welds 26 and 27, so that the second weld 27 is left holding together the two strips 9 forming the curtain 18 and that will come to lie against the center of the leading or front side face 3 of the next stack 1.

(7) The width of the stack 1 and any displacement of the stack 1 on the conveyor 17 are measured between the two spread double welding bars 19. This has not been shown in any more detail in the figures and this measurement is preferably carried out using at least one sensor, in particular at least one ultrasound sensor. As a result, the spacing between the double welding bars 19 can be controlled with or without feedback, so that the stack 1 can easily be passed through between the double welding bars 19.

(8) Sections 12, 13, 14, and 15 of the film wrapper 7 initially project up from the side faces 3, 4, 5, and 6 past the top face 11 of the stack 1, in particular vertically or substantially vertically. In addition as shown in FIGS. 3 and 4 when the stack 1 is moved into the wrapping unit 2, the projecting film section 12 of the front side face 3 is laid back or folded over by a following member onto the top face 11 of the stack 1 toward the center of the stack 1. Preferably and in this embodiment, first and second pairs of film-guide plates 20 and 21 of the fold-over device 10, as will be explained below, act as follower members for folding over the front film section 12 toward the center of the stack 1. Moreover, the height of a stack 1 fed to the wrapping unit 2 or the fold-over device 10 is measured using at least one sensor, in particular using at least one ultrasound sensor. Thus, as the stack 1 moves in, the spacing of the film-guide plates 20 and 21 is adjusted toward the top face 11 of the stack 1. Preferably and in this embodiment, the film-guide plates 20 and 21 are formed of metal sheets.

(9) According to this embodiment, the fold-over device 10 of the apparatus according to the invention has two of the film-guide plates 20 and 21 on each of the two opposite lateral sides 4 and 5 of the stack 1 (see in particular FIGS. 3 to 5). A respective film section 13 and 14 projects from each of the side faces 4 and 5 of the stack 1 past the top face 11 of the stack 1 and up between the respective film-guide plates 20 and 21 to be inserted or received in the fold-over device 10 while the stack 1 is being moved in. In the course of this, here the projecting film sections 13 and 14 are received between the film-guide plates 20 and 21 over the entire length of the film-guide plates 20 and 21 and are spaced from the film-guide plates 20 and 21. This completely received condition of the projecting film sections 13 and 14 is particularly shown in FIG. 6.

(10) According to a preferred embodiment of the invention and in this embodiment, once the film sections 13 and 14 projecting up from the side faces 4 and 5 have been received between the respective pairs of film-guide plates 20 and 21, the two double welding bars 19 of the first welder 8 are initially moved together, as described above. The at least one fold-over member or the at least one fold-over bar is subsequently moved into position for the later folding over of the film sections 15 projecting on the rear side face 6 of the stack 1 at the downstream end of the top face 11. Here, two fold-over members or two fold-over bars 26 are brought into position for this folding over to be carried out later. In the course of this, here the fold-over bars 26 are respectively connected to what relative to the stack 1 are the outer film-guide plates 21 and are pivoted away from the respective film-guide plates 21 into the fold-over position. Preferably and in this embodiment, the fold-over bars 26 each form a U-leg of a U-shaped fold-over bracket 22 fixed to the trailing end of the outer respective film-guide plate 21 and pivoted away or downward from this outer film-guide plate 21 into the fold-over position. In this respect, reference is moreover made to a comparison between FIGS. 5 and 6.

(11) According to a proven embodiment of the invention, once the two double welding bars 19 have been moved together and the fold-over bars 26 or the fold-over brackets 22 have preferably been pivoted into position, the film sections 13 and 14 projecting on the side faces 4 and 5 are subsequently folded over onto the top face 11 of the stack 1. To this end, according to a preferred embodiment of the invention, the two pairs of film-guide plates 20 and 21 move synchronously toward the center of the stack 1 or toward the center of the top face 11. It goes without saying that while this is happening, the film-guide plates 20 and 21 will always be at a sufficient spacing from the top face 11 of the stack 1. This means that as a result of this movement of the two pairs of film-guide plates 20 and 21, the film sections 13 and 14 received between the film-guide plates 20 and 21 are folded onto the top face 11. The path traversed by the film-guide plates 20 and 21 when moving toward the center of the top face 11 of the stack 1 amounts to approximately 75 to 85%, preferably approximately 80% of the height of the film overhang 13 and 14. The pairs of film-guide plates 20 and 21 will then preferably initially remain in a position above the center of the top face 11 of the stack 1. With regard to moving the two pairs of film-guide plates 20 and 21 together, reference is moreover made to a comparison between FIGS. 6 and 7. Here, the two double welding bars 19 of the first welder 8 will then subsequently be moved apart.

(12) As the two fold-over brackets 22 travel along with the respective outer film-guide plates 21 toward the center of the stack 1, the fold-over bars 26 of the two fold-over brackets 22 are moved into the space between the film-guide plates 20 and 21 and the top face 11 of the stack 1. As a result of the application of the fold-over bars 26 of the fold-over brackets 22, the film section 15 projecting on the rear side face 6 of the stack 1 past the top face 11 is folded over onto the top face 11 of the stack 1. Here, the fold-over brackets 22 are then pivoted against the respective outer film-guide plates 21 so that the fold-over bars 26 get out of the space between the film-guide plates 20 and 21 and the top face 11 of the stack 1.

(13) In this embodiment and according to a preferred embodiment of the invention, the film sections 12, 13, 14, and 15 folded onto the top face 11 of the stack 1 will subsequently be fused or welded together. Here, the fold-over device 10 of the apparatus according to the invention includes a second welder 16 in the form of two horizontal welding bars 23 each provided or fixed on a respective one of the outer film-guide plates 21. By moving these horizontal welding bars 23 down onto the top face 11 of the stack 1, the film sections 12, 13, 14, and 15 folded over onto the top face 11 of the stack 1 can be welded together or to one another. Both the front folded-over film section and the rear folded-over film section 15 are welded with the lateral folded-over film sections 13 and 14. After this welding of the film sections 12, 13, 14, and 15 on the top face 11 of the stack 1, the wrapped-up stack 1 is transported off by the conveyor 17 from the wrapping unit 2 or out of the fold-over device 10.