GB2124176A

GB2124176A - Improvements in stretch wrapping machines

Info

Publication number: GB2124176A
Application number: GB08215096A
Authority: GB
Inventors: Alan Redfearn; Frederick David Homfray
Original assignee: UNITED PACKAGING IND
Current assignee: UNITED PACKAGING IND
Priority date: 1982-05-21
Filing date: 1982-05-21
Publication date: 1984-02-15

Abstract

A stretch wrapping machine for wrapping a load with a web 1 of stretchable plastics film dispensed from a roll 2 of the film mounted in the machine, includes a heating device, such as a hot air blower 4, arranged to warm the plastics web as it is dispensed from the roll during a wrapping operation. The hot air blower is coupled to the dispensing mechanism so that it is actuated only whilst the web is being dispensed from the roll 2 and over-heating of the web is avoided. In a modification Fig. 2 (not shown), the air blower is replaced with an electrically heated roller which can be moved into and out of contact with the web. <IMAGE>

Description

SPECIFICATION Improvements in stretch wrapping machines The present invention relates to stretch wrapping machines, that is, machines for wrapping loads with webs of stretchable plastics foil or film which is dispensed, under tension, from a roll of the web mounted in the machine. Such machines may be used for circularly or spirally wrapping even or uneven loads, such as a single article or stack of goods on a pallet, in order to bind the load in place, protect the load during transportation and storage and/or guard against pilferage.

During a stretch wrapping operation, the plastics web is stretched to a considerable extent in order to bind the load securely. For example, it may be stretched by 50-60%.

Such a degree of stretching causes the width of the film to be significantly reduced as it is pulled from the roll. This reduction is commonly referred to as "necking-in". It results in the use of more wrapping film than would otherwise be necessary in wrapping operations.

It is an object of the present invention to alleviate the necking-in problem and enhance the stretchability of a web of plastics wrapping film as it is dispensed from a wrapping machine. Another object is to improve the cling properties of the film, that is, the ability with which over-lapping or superposed portions of the film adhere together to provide a sealed and secure wrapping.

To this end, the invention consists in a machine for wrapping a load with a web of stretchable plastics film dispensed from a roll of the film mounted in the machine, which includes a heating device arranged to warm the plastics web as it is dispensed from the roll during a wrapping operation.

The invention can be used to alleviate necking-in and improve the cling properties of any of the types of plastics film normally used for stretch wrapping purposes, such as, PVC, polypropelene or polyethelene film.

The heating device may comprise a hot air blower arranged to direct a stream of hot air onto the web substantially across the full width thereof, the blower being coupled to the dispensing mechanism so that it is actuated only whilst the web is being dispensed from the roll. Hence, the blower is automatically turned-off whilst the web is not being dis pensed in order to avoid over-heating of the web. Alternatively, the heating device may comprise a heated roller, with means being provided for urging the web out of contact with the roller when the web is not being dispensed, so as to avoid over-heating of the web.

In order that the invention may be more readily understood, reference will now be made to the accompanying diagrams, in which: Figure 1 is a plan view illustrating one embodiment of the invention, and Figure 2 is a perspective view illustrating another embodiment.

Referring to Fig. 1, this illustrates a wrapping machine in which a web of stretchable plastics film 1 is drawn, under tension, from a roll 2 of the web suitably supported in the machine. The web 1 is drawn from the roll about a guide roller 3 for circularly or spirally wrapping about a load (not shown) disposed adjacent the guide roller. Located between the roll 2 and the guide roller 3 is a hot air blower 4 which extends transversely of the web across its full width and has a nozzle 5 for directing a stream of hot air against the full width of the web. The blower is electrically coupled to the machine drive so that hot air is only directed against the web whilst it is being dispensed, and the blower is inoperative when the web is stationary and not being advanced relative to the blower.In this way, the blower warms the web whilst it is being disposed and is prevented from over-heating and melting the web when the latter is stationary. Hence, during a wrapping operation, the blower warms the web dispensed from the roll upstream of the load and this serves to reduce necking-in and improve the stretchability and cling properties of the film.

In the embodiment illustrated in Fig. 2, the web 6 of plastics wrapping film dispensed from the roll 7 supported in a wrapping machine is arranged to be warmed by an electrically heated roller 8 having its circumference coated with a layer of rubber or other elastomeric material. Downstream of the heated roller, the web is engaged by a release roller 9 which is suitably mounted on spring loaded arms so as to be resiliently swingable in an anti-clockwise direction about the roller 8, as indicated in Fig. 2. When the web 6 is being dispensed from the roll, it is drawn under tension about the heated roller 8, as shown in the Figure, and against the action of the spring-loaded release roller 9 so that the web travels about the heated roller and is warmed by its contact therewith. When the web 6 is not being dispensed from the roll, the spring-loaded roller 9 tends to swing about the roller 8 in anti-clockwise direction so as to release the web from contact with the heated roller and prevent over-heating of the web.

Whilst particular embodiments have been described, it will be understood that modifica tions can be made without departing from the scope of the invention.

1. A machine for wrapping a load with a web of stretchable plastics film dispensed from a roll of the film mounted in the ma

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in stretch wrapping machines The present invention relates to stretch wrapping machines, that is, machines for wrapping loads with webs of stretchable plastics foil or film which is dispensed, under tension, from a roll of the web mounted in the machine. Such machines may be used for circularly or spirally wrapping even or uneven loads, such as a single article or stack of goods on a pallet, in order to bind the load in place, protect the load during transportation and storage and/or guard against pilferage. During a stretch wrapping operation, the plastics web is stretched to a considerable extent in order to bind the load securely. For example, it may be stretched by 50-60%. Such a degree of stretching causes the width of the film to be significantly reduced as it is pulled from the roll. This reduction is commonly referred to as "necking-in". It results in the use of more wrapping film than would otherwise be necessary in wrapping operations. It is an object of the present invention to alleviate the necking-in problem and enhance the stretchability of a web of plastics wrapping film as it is dispensed from a wrapping machine. Another object is to improve the cling properties of the film, that is, the ability with which over-lapping or superposed portions of the film adhere together to provide a sealed and secure wrapping. To this end, the invention consists in a machine for wrapping a load with a web of stretchable plastics film dispensed from a roll of the film mounted in the machine, which includes a heating device arranged to warm the plastics web as it is dispensed from the roll during a wrapping operation. The invention can be used to alleviate necking-in and improve the cling properties of any of the types of plastics film normally used for stretch wrapping purposes, such as, PVC, polypropelene or polyethelene film. The heating device may comprise a hot air blower arranged to direct a stream of hot air onto the web substantially across the full width thereof, the blower being coupled to the dispensing mechanism so that it is actuated only whilst the web is being dispensed from the roll. Hence, the blower is automatically turned-off whilst the web is not being dis pensed in order to avoid over-heating of the web. Alternatively, the heating device may comprise a heated roller, with means being provided for urging the web out of contact with the roller when the web is not being dispensed, so as to avoid over-heating of the web. In order that the invention may be more readily understood, reference will now be made to the accompanying diagrams, in which: Figure 1 is a plan view illustrating one embodiment of the invention, and Figure 2 is a perspective view illustrating another embodiment. Referring to Fig. 1, this illustrates a wrapping machine in which a web of stretchable plastics film 1 is drawn, under tension, from a roll 2 of the web suitably supported in the machine. The web 1 is drawn from the roll about a guide roller 3 for circularly or spirally wrapping about a load (not shown) disposed adjacent the guide roller. Located between the roll 2 and the guide roller 3 is a hot air blower 4 which extends transversely of the web across its full width and has a nozzle 5 for directing a stream of hot air against the full width of the web. The blower is electrically coupled to the machine drive so that hot air is only directed against the web whilst it is being dispensed, and the blower is inoperative when the web is stationary and not being advanced relative to the blower.In this way, the blower warms the web whilst it is being disposed and is prevented from over-heating and melting the web when the latter is stationary. Hence, during a wrapping operation, the blower warms the web dispensed from the roll upstream of the load and this serves to reduce necking-in and improve the stretchability and cling properties of the film. In the embodiment illustrated in Fig. 2, the web 6 of plastics wrapping film dispensed from the roll 7 supported in a wrapping machine is arranged to be warmed by an electrically heated roller 8 having its circumference coated with a layer of rubber or other elastomeric material. Downstream of the heated roller, the web is engaged by a release roller 9 which is suitably mounted on spring loaded arms so as to be resiliently swingable in an anti-clockwise direction about the roller 8, as indicated in Fig. 2. When the web 6 is being dispensed from the roll, it is drawn under tension about the heated roller 8, as shown in the Figure, and against the action of the spring-loaded release roller 9 so that the web travels about the heated roller and is warmed by its contact therewith.When the web 6 is not being dispensed from the roll, the spring-loaded roller 9 tends to swing about the roller 8 in anti-clockwise direction so as to release the web from contact with the heated roller and prevent over-heating of the web. Whilst particular embodiments have been described, it will be understood that modifica tions can be made without departing from the scope of the invention. CLAIMS

1. A machine for wrapping a load with a web of stretchable plastics film dispensed from a roll of the film mounted in the ma chine, including a heating device arranged to warm or heat the plastics web as it is dispensed from the roll.

2. A machine as claimed in claim 1, in which the heating device comprises a hot air blower arranged to direct a stream of heated air onto the web substantially across the full width thereof.

3. A machine as claimed in claim 2, in which the hot air blower is adapted to be actuated substantially only whilst the web is dispensed from the roll.

4. A machine as claimed in claim 1, in which the heating device comprises a heated roller arranged to engage the web, and means is provided for disengaging the heated roller and web when the web is not being dispensed.

5. A machine for wrapping a load with a web of stretchable plastics film, constructed and adapted to operate substantially as hereinbefore described with reference to Fig. 1 or 2 of the accompanying drawings.