WO1999051496A1

WO1999051496A1 - Manipulation apparatus and method to open a bag

Info

Publication number: WO1999051496A1
Application number: PCT/NZ1999/000038
Authority: WO
Inventors: Clifford Bruce Steele; John Paul Koke
Original assignee: Sealed Air (Nz) Limited
Priority date: 1998-04-03
Filing date: 1999-03-31
Publication date: 1999-10-14
Also published as: CA2323599A1; KR20010042328A; JP2003517401A; BR9909341A; AU3177099A

Abstract

Apparatus and method to easily open bags mechanically. In particular, the invention provides a bag manipulation apparatus (1) which includes two or more engagement elements (2, 3), and each engagement element includes one or more mechanical gripping means of a movable gripper blade (5), a fixed gripper block (8) and rubber pads (6), characterised in that at least one engagement element includes a driving apparatus such as a pneumatic ram (4) configured to drive the engagement element to place the gripping means of the engagement element in contact with the side of a bag (10) in such a way that the side of the bag can be gripped by the gripping means, and subsequent movement of one engagement element relative to the other engagement element is sufficient to open the bag.

Description

MANIPULATION APPARATUS AND METHOD TO OPEN A BAG

TECHNICAL FIELD

This invention relates to improvements in and associated with devices used to manipulate bags. Specifically, the present invention may be adapted to open a plastic bag once it is formed at the end of the bag manufacturing process.

BACKGROUND ART

Plastic bags have many and varied uses. They have found applications in a large number of industries and are manufactured in large quantities.

In some cases the plastic bag manufacturing process includes a stage where an extruded tube of plastic film is fed through a series of rollers, then sealed and cut at particular points to form plastic bags. The tube of extruded plastic film is commonly known as tubestock.

Normally a freshly made bag is produced unopened with the sides of the bag in contact with each other. Unopened bags need to be opened when they are to be packed with product after the bag is formed.

A machine operator or packer individually handle and open each bag if the bag is to be filled just after it has been manufactured. Unfortunately such manual handling of bags is to be avoided if possible, as this greatly increases the cost and time frames associated with manufacturing, opening and filling a bag.

To be easily processed into a plastic bag, tubestock is preferably "blocked". Tubestock is considered blocked when both sides of the tubestock are in close contact with one another with minimal air inside the tubestock. Usually the smooth and intimate contact between the two faces of the tubestock keeps the tubestock blocked, making it appear and behave like a single layer of plastic film.

1 Blocked tubestock is preferred when the tubestock is to be printed or when the tubestock is to be passed though handling devices such as 'nip' or turning rollers. If the tubestock is not blocked and the two sides become separated, nip rollers may create folds, wrinkles or creases in the tubestock which can result in poor sealing, poor print quality and visually unacceptable bags.

Once the tubestock is cut into a series of lengths and the end of a length is sealed, a "blocked" plastic bag is formed. Unfortunately difficulties arise when the bag is to be opened and packed with product.

Again, if a blocked newly formed plastic bag is to be filled, additional time and effort must be expended to open the bag. Blocked plastic bags are also relatively difficult to open by hand because of the smooth and intimate contact between the two faces of the bag. As a consequence of this intimate contact blocked plastic bags usually take more time for a machine operator or packer to open.

Some bag manufacturing machines 'unblock' tubestock before the required bags are formed by trapping a large bubble of gas (typically air or nitrogen) in the tubestock prior to the tubestock entering the sealing and cutting area of the machine. However, this increases the risk of wrinkles or creases being formed in the tubestock, which can result in poor quality bags being produced

One known automated bag opening apparatus operates with use of vacuum driven suction cups. Suction cups are applied to either side of a newly formed bag and a vacuum is applied to the cups. This allows the cups to hold the sides of the bag, and when the cups are drawn away from one another, the bag is opened.

However, this type of automated bag opening system involve a number of problems. Because the cups are vacuum driven the apparatus is relatively hard to maintain and run. Air filters associated with the vacuum pumps used need to be cleaned and checked frequently to ensure no blockages or damage occurs to the apparatus.

If the cups contact the bag at a fold or a crease they cannot easily form a seal against the bag wall, as the crease or fold allows air to leak through into the cup. In these cases the connection between the bag and the vacuum driven cup may not be strong enough to allow the cup to open the bag.

A device which addressed any or all of the problems discussed above would provide a considerable advantage over the prior art. Specifically, it would be desirable to have a bag opening apparatus which could be easily and cheaply operated and maintained, and which could consistently open unopened bags formed from blocked, unblocked or partially blocked tubestock.

A device which could be readily and easily integrated into standard bag manufacturing apparatus would also be of advantage. Specifically the applicant has developed "bag manufacturing machines which allow a bag to be formed dispensed and filled in the one location. These devices are discussed in detail in PCT Application No. PCT/NZ94/00039, and New Zealand Patent Application Nos 286910, 299534 and 328269. A bag manipulation apparatus which could be configured for use in such machines would be of great advantage.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a bag manipulation apparatus which includes two or more engagement elements, and

each engagement element includes one or more mechanical gripping means

characterised in that

at least one engagement element includes a driving apparatus configured to drive the engagement element to place the gripping means of the engagement element in contact with the side of a bag in such a way that the side of the bag can then be gripped by the gripping means, and

subsequent movement of one engagement element relative to the other engagement element is sufficient to open the bag.

In another aspect there is provided a method of manipulating a bag using bag manipulating apparatus characterised by the steps of:

a) bringing two or more engagement elements in contact with the side of the bag, and

b) gripping the bag with mechanical gripping means associated with the engagement elements, and

c) moving at least one engagement element relative to the other engagement element to open the bag.

It should be appreciated that the provision of a positive and mechanical action by gripping means to hold the side of the bag overcomes a number of the problems associated with the prior art, and in particular those associated with the vacuum driven suction cups. With the use of mechanical gripping means, there is no need to maintain a vacuum or provide all of the maintenance required to ensure vacuum pumps are kept clean and unblocked.

Further, by having positive gripping means associated with engagement elements, it is immaterial whether the gripping means meets a fold or a crease in the bag material as a strong grip will still be achieved.

In a preferred embodiment the bag manipulating apparatus is capable of interfacing to, and be associated with, at least one standard bag forming machine currently used in bag manufacture. This configuration of the invention allows bags to be automatically manipulated easily and quickly within the bag manufacturing process.

By opening the bag as part of the manufacturing process the time of a machine operator may be saved, as well as allowing the manufacture, opening, and filling of a bag to be automated. Further, automatic opening is more hygienic than manual opening.

Reference throughout the specification shall now be made to the present invention as being used to open an unopened bag. However, it should be appreciated by those skilled in the art that other forms of manipulation may be conducted using the present invention, and reference to the opening of the bags only should in no way be seen as limiting.

The bag manipulating apparatus preferably includes at least two engagement elements. An engagement element may be positioned on either side of a bag to allow the gripping means of each engagement element to manipulate same. However, in alternative embodiments, any number of engagement elements may be configured for use with the present invention and reference throughout the specification to two only should in no way be seen as limiting. For example in an alternative embodiment, the bag manipulation apparatus may include four engagement elements positioned around an unopened bag in a substantially rectangular configuration. Gripping means associated with each engagement element may then open the unopened bag to form four sides on the bag, and allow product to be dropped directly into the opened bag.

In a preferred embodiment each engagement element includes one gripping means only. Preferably only one gripping means is required on each engagement element to grip and open a bag. However, alternative embodiments may employ any number of gripping means on an engagement element as required. For example in some embodiments the present invention may be employed to open large, thick plastic bags, and two or more gripping means may be required on each engagement element.

An engagement element may consist of any type of framework or structure used to mount and move a gripping means. In a preferred embodiment an engagement element used may include a framework onto which one or more gripping means may be mounted. Such a framework allows the engagement element to move each gripping means as required during an operation of the invention.

In a preferred embodiment an engagement element may include a driving apparatus. Such a driving apparatus may be configured to drive an engagement element relative to another engagement element to place the gripping means of each engagement element in contact with the side of a bag.

In a preferred embodiment an engagement element driving apparatus may include a pneumatically driven ram. Such a ram may be linked to a fixed point on a wall, floor, or a fixed frame work and used to drive an engagement element towards or away from this fixed point as required. In a further preferred embodiment the ram used may be linked to a fixed point on a frame work.

Alternative embodiments may not include a pneumatic ram as a driving apparatus

6 discussed above. For example in one alternative embodiment an electric solenoid, hydraulic or electrical motor may drive an engagement element up or down a guide or track as required.

In a preferred embodiment where an engagement element is brought in the vicinity of a bag, one or more gripping means mounted on the engagement element may be placed in physical contact with the bag. When an engagement element is brought within the vicinity of the bag this allows the gripping means of the engagement elements to hold a bag.

Once the bag is held by opposing gripping means on opposite sides of the bag, the engagement elements on each side can activate the gripping means to grip each side of the bag.

As can be appreciated once the gripping means of engagement elements located on either side of the bag have gripped a bag, movement of one engagement element relative to the other will open the bag. In a preferred embodiment one engagement element moves relative to another to open a bag by moving away from the other engagement element. In this way the unsealed end of a bag maybe opened wide to a degree or amount determined by the distance moved by an engagement element.

Reference throughout the specification shall now be made to an engagement element as including one gripping means only. However, it should be appreciated by those skilled in the art that any number of gripping means may be used on each engagement element and reference to one only should in no way be seen as limiting.

In a preferred embodiment a gripping means may be configured with two opposing faces. These faces may be configured to move towards and away from one another as required during operation of the gripping means.

This configuration of opposing faces allows the gripping means on opposite sides of the bag to firstly hold a bag between them. Then the opposing faces of the gripping means on each side of the bag "pinch" the side of a bag as they are moved together. Pinching the side of a bag between these two faces will then allow the gripping means to grip the bag. In this way, the two opposing faces of a gripping means may use a mechanical shearing action to trap or confine a portion of the bag to grip the bag.

Reference throughout the specification shall now be made to a gripping means as including two faces positioned adjacent to one another and adapted to move substantially towards and away from one another. However, it should be appreciated that other configurations of gripping means may be used in conjunction with the present invention, and reference to the two faces only discussed above and should in no way be seen as limiting. For example, in other embodiments any type of jaws or pinchers which may pinch or trap a portion of a bag may be used in conjunction with the present invention.

In a preferred embodiment each of the two faces used in a gripping means may be formed from a rectangular block mounted onto a guide track of an engagement element. The rectangular block used may contact and grip a portion of the bag strongly using a wide surface area contact. The resulting frictional connection between the block and a portion of the bag allows the block to impart a mechanical shearing action to the bag wall, and pinch a portion of same using an adjacent second block.

In a preferred embodiment each block used in a gripping means may include a surface which allows a strong frictional and non abrasive contact between the gripping means and the unopened plastic bag. The surface used may allow a gripping means block to be placed in contact with a bag with a strong frictional connection between the bag and the block, allowing the block to apply a shearing force to the bag wall. The frictional surface used may also be non abrasive to ensure that the bag wall is not torn or damaged by contact with the block.

SUBSTTTUTE SHEET (RULE 26) In a preferred embodiment the surface of each block used may be formed from rubber. Rubber provides strong frictional yet non abrasive contact between a bag wall and a block. However, in alternative embodiments, materials other than rubber may be used in the construction of a gripping means block. For example, in other embodiments plastics materials or any form of dimple or textured surface may be used in the formation of a gripping means block, and reference to the use of rubber only above should in no way be seen as limiting.

In a preferred embodiment one face of a gripping means may be connected to a driving apparatus. This allows one face to be moved substantially towards or away from the other face employed.

In a further preferred embodiment the driving apparatus used with one gripping means face may be a pneumatic ram similar to that used and discussed with respect to an engagement element. In such an embodiment the pneumatic ram may drive a rectangular block along a mounting track towards and away from a second rectangular block.

Alternative embodiments may not employ a driving apparatus with one face only of a gripping means. For example in an alternative embodiment one driving apparatus may be linked to each face of a gripping means. In this embodiment each face of a gripping means may require its own driving apparatus to grip a large or thick walled bag.

In preferred embodiments of the present invention, at least one face of the gripping means may have a biasing force against it so that the face acts as a retainer. The use of such a retainer allows the strong gripping forces of a gripping means to be readily disengaged or reduced after a bag is open thus avoiding possible tearing of the bag. The retainer may hold a bag open with a light force only, allowing the open bag to be manipulated or moved easily without having to fight against the gripping force of a gripping means.

SUBSTTTUTE SHEET (RULE 26) In one embodiment of the present invention, the biasing means may be in the form of an air pressure regulator on the driving apparatus used with the gripping means. However, the applicant believes that with films that are "sticky" there may still be problems with this approach with the film staying together in the "gripped" configuration once the bag has been removed from the bag manipulation apparatus.

In further preferred embodiment the biasing means of the face acting as a retainer may include a spring. The spring may be linked to the framework of an engagement element and biases one block of a gripping means towards the second block used. In such an embodiment the spring retainer may be linked to the gripping means block which is not driven by a pneumatic ram.

In use, the first block may be driven towards the second, providing a strong shearing action to the bag in contact with each gripping means block. Once the bag wall has been sheared and a portion of the bag is pinched, the pneumatic ram may bottom out or hit a mechanical stop outside the gripping area. The spring force of the retainer will then bias the two faces of the gripping means together with a reduced force. In this way, a strong shearing action force can be applied to the wall of a bag which is then reduced when the bag is opened, allowing the open bag to be manipulated or pulled from the apparatus without significant effort.

As can be appreciated by those skilled in the art, the strength of the grip on a bag may be easily varied by changing the force between each opposing face of a gripping means when a bag is 'pinched'. The retainer discussed above can be used to easily control the force between each gripping means face.

The present invention may also be easily incorporated into an existing bag manufacturing line and provide a 'linking' stage to an automated bag filling production line. The present invention may be used to fully automate the manufacture, opening and filling of a bag.

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SUBSTTTUTE SHEET (RULE 26) However in other embodiments the present invention may also be used to open and move a bag to another location. A bag may be manufactured and opened using the present invention and then transported to another location before it is filled. Those skilled in the art should appreciate that it is not necessary to immediately fill a bag once it has been opened.

The present invention provides many advantages over existing prior art devices.

The bag manipulating apparatus discussed above may be maintained and operated in a relatively cost effective manner. The mechanical elements of the present invention may be easily checked, cleaned and modified when compared with other prior art devices.

The present invention may also be used to consistently open unopened bags formed from block, unblocked or partially blocked tubestock.

The present invention allows a bag to be gripped relatively tightly when opened, and then be held open by a small retaining force. This allows the opened bag to be easily removed from the bag manipulation apparatus.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

Figures la -Id show the components and operation of the present invention as configured in one embodiment;

DETAD ED DESCRIPTION OF THE DRAWINGS

Figures la to Id show a bag manipulation apparatus generally indicated by arrow 1 configured and operating in accordance with one embodiment of the present

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SUBSTTTUTE SHEET (RULE 26) invention.

The bag manipulation apparatus (1) includes a fixed engagement element (2) and a moveable engagement element (3), between which is a newly formed bag (10),

The moveable engagement element (3) can be moved towards the fixed engagement element (2) through operation of a pneumatic ram (4).

Each engagement element (2 & 3) includes gripping means which comprise of a moveable gripper blade (5) and a fixed gripper block (8).

The moveable gripper blades (5) can be driven towards and away from the gripper block (8) by pneumatic cylinders (7).

The gripper blocks (8) are moveable slightly within the engagement elements (2 & 3) against a spring (9).

The outer faces of the engagement elements (2 & 3) and gripper blades (5) include rubber pads (6).

In operation, the bag manipulation apparatus depicted may work as follows.

With respect to Figure la, the newly formed bag (10) is positioned between the two engagement elements (2 & 3). The gripping means comprising of the moveable gripper blade (5) and fixed gripper block (8) are apart from each other.

The next step in the process is illustrated in Figure lb whereby the pneumatic cylinder (4) moves the moveable engagement element (3) towards the fixed engagement element (2). Movement of the engagement element (3) causes the rubber pads (6) on both of the engagement elements (2 & 3) and gripper blade (5) to hold the bag (10) between them.

The third stage is illustrated in Figure lc whereby the pneumatic cylinders (7) move

12 the moveable gripper blades (5) towards the gripper blocks (8). The frictional effect of the rubber pads (6) on the bag in combination with the movement of the gripper blade (5) by the cylinder (7) causes the bag (10) to be gripped between the face (5 A) of the moveable blade (5) and the face (8 A) of the gripper block (8).

The biasing effect of the spring (9) behind the gripper block (8) ensures that although the bag is held by the gripping means, the force is not sufficient to tear the bag when the bag is removed from the machine nor cause stickier plastic films to adhere to each other.

The final stage is illustrated in Figure Id whereby the cylinder (4) moves the engagement element (3) away from the fixed engagement element (2). As the gripping means in each engagement elements has one side of the bag pinched between them, this movement causes the bag (10) to open, giving of course the desired result.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the appended claims.

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SUBSTTTUTE SHEET (RULE 26)

Claims

WHAT WE CLAIM IS:

1. A bag manipulation apparatus which includes two or more engagement elements, and

each engagement element includes one or more mechanical gripping means

characterised in that

2. A bag manipulation apparatus as claimed in claim 1 wherein the driving apparatus is in the form of a pneumatic ram.

3. A bag manipulation apparatus as claimed in either claim 1 or claim 2 wherein the gripping means includes two adjacent faces configured to move towards and away from each other during the operation of the gripping means.

4. A bag manipulation apparatus as claimed in claim 3 wherein the faces of the gripping means use a mechanical shearing action to trap or confine a portion of the bag to grip the bag.

5. A bag manipulation apparatus as claimed in either claim 3 or claim 4 wherein the gripping means or engagement element includes a frictional surface.

6. A bag manipulation apparatus as claimed in any one of claims 1 to 5 wherein a portion of a gripping means is configured to act as a retainer.

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SUBSTTTUTE SHEET (RULE 26)

7. A method of manipulating a bag using bag manipulating apparatus characterised by the steps of:

8. A bag manipulation apparatus substantially as herein described with reference to and as illustrated by the accompanying drawings.

9. A method of manipulating a bag substantially as herein described with reference to and as illustrated by the accompanying drawings.

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SUBSTTTUTE SHEET (RULE 26)