Package making – Methods – Applying a partial cover
Patent
1986-12-10
1988-08-16
Sipos, John
Package making
Methods
Applying a partial cover
53441, 53556, 53567, 53585, B65B 913, B65B 1302
Patent
active
047634618
DESCRIPTION:
BRIEF SUMMARY
This invention provides a method and appratus for the wrapping of an article or an assembly of articles.
In the past there has been three common ways of wrapping an article or an assembly of articles with plastic film material. In one method (shrink wrapping) a plastic film bag (or sleeve) a little larger than the load to be wrapped is placed over the load, e.g. an assembly of boxes on a pallet, and then heat is applied to the bag and it shrinks onto the load. This method relies on the plastic bag being stretched and "frozen" in the stretched state at manufacture and the "unfreezing" of plastic bag by heat to allow the plastic bag to contract towards its normal unstretched state, which is smaller than the load. As the unstretched state cannot be attained the plastic bag forms a tensioned wrap around the load.
In a second method (stretch-and-shrink) a bag (or sleeve) of plastic film smaller in cross-section than the load is formed as a puckered band on a frame, the frame is expanded to stretch the puckered band and then the bag is stripped from the frame onto the load. The plastic bag when released from the stretching forces contracts and becomes an elastically embracing wrap around the load.
In the third method (stretch wrapping) a continuous band of stretchable plastic film under tension is wrapped around and around the load like a bandage.
All of the above wrapping methods have goods features and all have disadvantages. In the case of shrink wrapping the advantage is that the equipment needed, namely, a plastic bag and a heat gun or oven, is comparatively inexpensive. The disadvantage is that heat has to be used and and the heat can cause holes in the plastic and can effect goods being wrapped. Another disadvantage occurs where the goods to be wrapped as a bulk quantity are individually wrapped in a material which will stick to the outer wrap due to the use of heat in the wrapping process.
In stretch-and-shrink, the advantages are lack of heat, a very firm wrap around the load, an end cover over the top of the load simultaneously with the wrapping of the load and a substantially mechanised wrap procedure which is quick and efficient. For many applications this form of wrapping is ideal. The disadvantages are that the equipment is in the form of a machine that is reasonably complex and therefore the capital outlay for the machine is a consideration. The loads have to be brought to the machine and substantial space is required for the machine and the performance of the wrapping operation. This method is however without equal in factories where the wrapping of pallet loads is a continuous and substantially mechanised operation. In stretch wrapping the major disadvantages are that the equipment is expensive, it occupies substantial floor space and requires load holding devices to be used whilst the wrapping is performed. Because the method is a true "wrapping" technique there is likely to be an overuse of the wrap material because of the need for operator control. Additionally, there is no automatic way to obtain a top cover over the load as part of the wrapping operation, as is possible with the use of bags in the stretch-and-shrink and the shrink only methods.
The present invention overcomes most of the above disadvantages. It is a no-heat procedure and it can use a sleeve or a bag made of any plastic film material that will allow a limited amount of elastic stretch, substantially all plastic film has this quality. The equipment required to perform the wrapping method is economical to make and easy to service and can be mobile so that it can be taken to the load to be wrapped, whereas with known no-heat wrapping methods the loads to be wrapped have to be taken by a fork lift truck or the like to a wrapping machine in a specific location.
Accordingly, the present invention can be said to provide broadly, a method of wrapping an article or a group of articles hereinafter called a load, by the steps of placing around the load a panel of elastically stretchable sheet material having a length greater than the c
REFERENCES:
patent: 181052 (1876-08-01), De Gray
patent: 2026284 (1935-12-01), Metternich
patent: 3089298 (1963-05-01), Nevendurf
patent: 3495375 (1970-02-01), Burhop
patent: 3621638 (1971-11-01), Grocke
patent: 4605456 (1986-08-01), Annis
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