WO1992006893A1

WO1992006893A1 - Automatic stretch film palletizing apparatus

Info

Publication number: WO1992006893A1
Application number: PCT/SE1991/000682
Authority: WO
Inventors: Anders Billberg
Original assignee: ANDERS BILLBERG AB
Current assignee: ANDERS BILLBERG AB
Priority date: 1990-10-11
Filing date: 1991-10-09
Publication date: 1992-04-30
Anticipated expiration: 1993-04-11
Also published as: SE9003250L; SE9003250D0; AU8724391A

Abstract

The invention relates to an automatic stretch film palletizing apparatus. The apparatus comprises a base (1), grippers, a pivotally suspended plate (2) having protruding arms (3) carrying a vertical film streching unit (10) having film stretching cylinders (11, 12) and a supply roll (15) containing stretch film (20). The film stretching unit may be rotated around a pallet placed within the base (1). The two grippers (30, 35) are arranged vertically and above each other to each retain an edge of the stretch film (20). In front of the grippers (30, 35) are arranged two opposite each other laterally slidable gates containing vertical profiles (40, 45), the gates are independently of each other laterally operable. The profiles (40, 45) have a vertical extension corresponding to the maximum adjustable distance between the grippers. Due to that one profile is provided with a knife edge the stretch film (20) may also, except being retained, be cut by means of the vertical profiles.

Description

Automatic stretch film palletizing apparatus

BACKGROUND OF THE INVENTION

The present invention relates to an automatic stretch film palletizing apparatus for wrapping of a tape, e.g., a plastic stretch film or a or a plastic net as a uniting packing around a product resting on a pallet.

Several different packaging devices for application of a stretch film around a product or a number of products on a pallet are known. The plastic film is contained on a supply roll from which the plastic film is pulled simultaneously as the film is stretched and wrapped, for larger pallets in a helical around the product or products on the pallet.

The stretch film is taken from the supply roll via a film stretching unit which normally constitutes two vertical cylinders rotary mounted in bearings between two bearing plates and parallel to the supply roll, whereby the second cylinder has a slightly larger periphery than the first. The stretch film is fed around each of the cylinders, which are covered with a surface which gives a high friction against the film. As the second cylinder is having a slightly larger periphery it will feed more film than the first cylinder, and consequently the piece of film being between the cylinders all will always be stretched.

Either the pallet itself together with the product or products is rotated or the complete film stretching unit is rotated around the product or products on the pallet at the same time as film is fed and put side by side around the pallet and simultaneously as the vertical position of the film stretching unit in height is changed until the total product or products on the pallet is/are enveloped by the stretch material.

When packaging is finished the stretch film is cut and at the start of a new packaging the film may be held by a fixed gripper during the first revolution when applying the film_* As these devices on request puts the film in a spiral, a width of the supply roll of 500 - 1000 mm will be enough. This is also typically used for items not showing smooth surface sides on the pallet. It is then more simple when starting the packaging process to affix a narrower film onto the item on the pallet than a wide film.

These known packaging devices which offers an automatic packaging of larger objects generally have a complex construction as the film on one hand should be put around the object to be packed and should on the other simultaneously be carried upwards or downwards to achieve a helical ascent corresponding to about half the width of the stretch film. This is done to be able to package products and pallets which often are 2 - 3 times as high as compared to the width of the stretch film which can be handled by the packaging device. Such automatic devices will be expensive and will therefore not be used by small and medium companies producing products which are normally loaded on a pallet before transportation from the factory.

From US-3 793 798 is known a shrink palletized process and apparatus. This device is intended for heat shrink film and does not disclose any fully automatic way to cut and retain the film.

From GB-A-1 581 674 is known an automatic wrapping apparatus which is rotating the pallet. The document discloses clamping and cutting means for the film but the principle for this implies that the pallet must be loaded such that it has fairly flat sides to be able to automatically fix the first layer of film to the pallet.

SUMMARY OF THE INVENTION

The present invention is aimed at accomplishing a fully automatic stretch film palletizing apparatus which is exhibiting a minor number of components and therefore is simple and inexpensive to manufacture. The apparatus of the present invention is easy to combine with a conveyor belt running through for full automatic stretch film palletizing. Additionally the present invention provides the possibility to simply work with such a width of the stretch film, independent of the form of the load on the pallet, that the film will be sufficient wide to vertically fully cover the side of a standard pallet loaded up to, e.g., a height of two meter with a product or packages.

The invention further provides the advantage as the width of the film will cover the total height of the pallet, it is not necessary to put the film helically, which results in a reduced consumption of fixm and an essentially shorter time for packaging and the film stretching unit does not have to be rotated as many around the pallet for a given thickness of film. Further the packaging presents vertically a better stability by consisting of a number of film layers having a matching width especially in the cases when the merchandise is not presenting smooth side surfaces along the height of the pallet.

Due to the simplicity of the device it is very simple to quickly change from a, e.g., 2000 mm wide supply roll of stretch film to, e.g., a 1500, 1000 or 500 mm wide supply roll, whereby a simple adaption may be done dependent of the different subjects to be packaged using stretch film. The apparatus according to the present invention is very fast in operation compared to devices according to the prior art.

The characteristics of the invention are to be found in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail below in form of a preferred embodiment in connection with the enclosed drawings, in which:

Fig. 1 is an in part cut-away radial projection of a packaging device according to the present invention, » Fig. 2 is an in part cut-away top view of the packaging device of Fig. 1,

Fig. 3 is a side elevation of a packaging device of Fig. 1,

Fig. 4 is a plan view of the left side of Fig. 3 seen from the inner side of the packaging device according to the invention showing the grippers closed and the gates having the vertical profiles i the closed position,

Fig. 5 is a plan view of the packaging device according to Fig.4 showing the grippers closed and the gates having the vertical profiles in their opened positions.

Fig. 6 is a plan view of the central portion of Fig. 5 showing the grippers opened.

DETAILED DESCRIPTION 1. Technical description

In Fig. 1 is shown an in part cut-away radial projection of a preferred embodiment of a packaging device according to the present invention. The device comprises a base 1 having four legs, and at -the top a rotary supported round disc 2. Onto the disc 2, two protruding arms 3 are fixed, which are carrying a film stretching unit 10. The film stretching unit 10 has two feeding and stretching cylinders 11 and 12 and a supply roll 15 containing stretch film 20. The film stretching unit will be rotated inside the base 1 around the vertical symmetry axis of the disc 2 by having a motor 4 via a belt 5 driving the disc 2 to rotate and consequently also feeding stretch film 20 from the film stretching unit 10 simultaneously as it moves. At one side of the base 1 is arranged two grippers 30 and 35 which each may retain the stretch film by the respective upper and lower edge of the film.

From Fig. 3 is seen that the lower gripper 30 is arranged fixed by an arm 31 onto one side of the base 1, while the upper gripper 35 is fixed onto a L-shaped profile 36 in the center of the base through the axis supporting the disc 2. The upper gripper 35 is arranged centered above the lower gripper 30, but the gripper 35 may be adjusted in height to be adapted to a different width of the stretch film 20, which in the preferred embodiment may have a width of up to 2000 mm. The profile 36 is provided with a number of through holes 37 corresponding to a different width of the stretch film 20 and in the profile 39, which outside also constitutes supporting axis for the disc 2, there is an internal longitudinal hole having a inside cross section corresponding to the outer cross section of the profile 36. In the profile 39 there is a through hole 38 corresponding to the holes 37 in the profile 36. By means of a locking pin through the hole 38 and at the same time through any one of the through holes 38 the profile

36 may be locked at different heights corresponding to a different width of the stretch film.

The grippers 30 and 35 are constructed as two towards each other revolving 90 degrees disc segments having the edges 30a and 35a, respectively, meeting corresponding edges 30b and 35b, respectively, of the other disc segments provided with a friction layer to in a safe way clamp the edge of the stretch film between the edges of two disc segments (Fig. 5 and 6). Fig. 1 demonstrates how the stretch film is retained by the grippers 30 and 35. The grippers 30 and 35 in the preferred embodiment of the present invention are operated by means of pneumatic controlled pistons arranged at each of the grippers.

From Fig. 2, which is showing the film stretching unit 10 as a top view in a starting position behind the gripper, it is seen that the film stretching unit freely may pass by the upper and lower gripper. Fig. 2 also shows a motor 16 in the stretching unit, which via a gear reduction drives the feeding and stretching cylinders 11 and 12. Additionally there are, as shown by Fig. 1 and 2, in front of the grippers two laterally movable gates 42 and 47 each provided with a vertical profile.40 and 45, respectively, having a length corresponding to the largest width of the stretch film to be used in the apparatus. The vertical profile 40 presents a vertical supporting surface 41 having a slot to receive a knife edge placed in a corresponding position on the vertical profile 45. The gate 42 is provided with two horizontal lower and upper sliding devices 43 and 44 fixing the gate into corresponding tracks of the base 1. The gate 47 is in a similar way provided with two horizontal lower and upper sliding devices 48 and 49 also correspondingly by tracks fixing the gate 47 to the base 1. The sliding devices 43, 44, 48 and 49 are in the preferred embodiment operated by pneumatic pistons. When..the gates 42 and 47 are closing the vertical profiles 40 and 45 will shut tight against each other. When the gates are closed the film stretching unit can not pass, while when the gates 42 and 47 are in their opened positions the film stretching unit may freely pass during its rotation inside the base 1.

2. Function.

In a starting position a pallet 100 having goods to be packaged is centrally present within the base 1, where it is carried, e.g., on a conveyor which at a proper height runs through the base 1. The gates 42 and 47 are closed (Fig. 4) and holding between the vertical profiles 40 and 45 one end of the stretch film 20 contained on the supply roll 15. The grippers 30 and 35 are closed and retains thereby also the stretch film 20 between the respective disc segments. Then the gates 42 and 47 are opened whereby the stretch film from now is retained only by the grippers 30 and 35. When the gates 42 and 47 are opened (Fig. 5) the film stretching unit 10 starts its rotation within the base 1 by means of the motor 4 via the belt 5, simultaneously as the motor 16 feeds an appropriate amount of stretch film 20 from the supply roll 15. The stretch film will thus be put around the pallet 100 being in the middle of the base 1. As the film is stretched by the stretching unit 10 its. will then shrink so it tightly encloses the merchandise on the pallet 100. When the stretching unit has moved slightly more than one revolution around the pallet the grippers 30, 35 are opened and the released end of the stretch film together with the film constituting the next layer is braced to the pallet due to the tension of the stretch film applied by the stretching unit.

The grippers 30 and 35 are left open (Fig. 6) and give a free passage to the stretch film 20 such that at a continued rotation the stretch film 20 is applied direct to the pallet around its entire circumference. After that enough layers have been obtained around the pallet the rotation of the stretching unit is stopped when it is behind the open grippers 30, 35. Then the gate 42 is closed simultaneously as more stretch film is fed such that the gate 42 may move to its closed position. The stretch film will then rest against the supporting surface 41 on the vertical profile 40 of gate 42. Then the gate 47 is closed whereby the stretch film is squeezed between the two vertical profiles 40 and 45. Simultaneously the stretch film 20 is cut and the cut end not squeezed by the vertical profiles 40 and 45 will be stretched and adhere to the layers of stretch film around the pallet. Then palletizing process is ready and the pallet is carried out of the base 1 on the conveyor.

While the vertical profiles 40 and 45 of the gates retain the stretch film 20 behind the knife edge 46 in a direction towards the supply roll 15 the grippers 30, 35 are again closed to hold the stretch film at its respective upper and lower edge and the starting position according to Fig. 4 is again obtained a d the apparatus is thus ready for the next pallet to be wrapped using stretch film.

Claims

1. An apparatus for automatic stretch film palletizing comprising a base (1), grippers, a motor driven pivotally suspended plate (2) having protruding arms (3) carrying a vertically arranged film stretching unit (10) including motor driven film stretching cylinders (11, 12) and a supply roll 15 containing stretch film (20), characterized in that in front of a first gripper (30) and a second gripper- (35) are arranged opposite to each other a laterally movable first gate and a second gate including a respective vertical profile (40, 45) for cutting and retaining the film and that the gates including the vertical profiles are operable independently of each other.

2. The apparatus according to claim 1, characterized in that the first gripper (30) and the second gripper (35) are aligned on top of each other at a side of the base (1) to each retain an edge of the stretch film (20) and that the first and the second grippers (35) are arranged at a fixed position within the base (1) in relation to the rotating film stretching unit (10) whereby the second gripper (35) is provided with a fixing profile (36) movable in a vertical plane to adjust the distance between the first gripper (30) and the second gripper (35).

3. The apparatus according to claim 2, characterized in that the laterally movable vertical profiles (40, 45) each are having a length corresponding to the maximum adjustable distance between the first and the second grippers (30, 35) and each having a first position and a second lateral position; that in the first position the two movable vertical profiles (40, 45) meet in front of the first and second grippers (30, 35).

4. The apparatus according to claim 3, characterized in that the vertical profile (40) of the first gate offers a vertical supporting surface (41) for the stretch film (20) in the first position while the first profile (40) in its second lateral position of the gate is moved away to offer free passing of the film stretching unit (10), and that the second vertical profile (45) of the second gate is provided with a knife edge (46) which in the first lateral position connects to the vertical supporting surface (41) of the first vertical profile (40) in its first lateral position for cutting the stretch film (20) and retaining the remaining stretch film, and that the second vertical profile (45) in its second lateral position offers free passing of the film stretching unit (10).

5. The apparatus according to claim 4, wherein the first and the second grippers (30, 35) in their closed position presenting vertical clamping surfaces (30a, 30b; 35a, 35b), characterized in that in the opened position of the first and second grippers (30, 35) the surfaces (30a, 30b; 35a, 35b) are lying in horizontal planes below the lower and above the upper, respectively, edge of the stretch film to achieve free passing of the stretch film (20).

6. The apparatus according to claim 5, characterized in that the movable fixing profile (36) carrying the second gripper (35) is a L-shaped profile arranged with predetermined quick lock positions (37) corresponding to the available widths of the supply roll of stretch film.

7. The apparatus according to claim 6, characterized in that the quick lock positions (37) are formed by a number of through holes in the profile (36) carrying the second gripper (35) and of a corresponding hole (38) in a centrally in the base (1) secured vertical fixed outer profile (39) inside- which the profile (36) with the upper gripper is arranged, and a quick lock pin is inserted through the hole in the central outer profile and simultaneously through any of the through holes in the profile (36) carrying the second gripper (35); the L-shaped profile (36) having an outer cross sectional contour and the profile (39) having a corresponding inner cross sectional contour which either is circular or having any other geometrically created cross sectional pattern.

8. The apparatus according to claim 7, characterized in that the vertically against each other closing surfaces (30a, 30b; 35a, 35b) are arranged having a friction layer of a resilient material to achieve a friction surface to be able to retain the stretch film (10) when the first and second grippers (30, 35) are closed.

9. The apparatus according to any of the preceding claims,, characterized in that any of the first gripper (30), the second gripper (35), the-first gate containing the vertical profile (40) and the second gate containing the vertical profile (45) may be operated either pneumatically, hydraulically or electrically.