WO2005022984A1

WO2005022984A1 - Plastic film for ground covering with formed edges

Info

Publication number: WO2005022984A1
Application number: PCT/GR2004/000030
Authority: WO
Inventors: Asterios D. Daios
Original assignee: Daios Asterios D
Priority date: 2003-09-10
Filing date: 2004-05-24
Publication date: 2005-03-17
Also published as: EP1662859A1; GR1007190B; GR20030100373A

Abstract

The invention refers to a plastic film for ground covering with formed edges along its sides that is destined for agricultural use. Each formed edge is folded twice towards the same direction, in such a manner that the first folding (4) has width (b) less than (c) of the second folding (5) and preferably half the width of the latter. The superimposed parts of each formed edge are welded to each other with successive weldings (7i) along its length, preferably transverse and in such a manner that the first folding (4) alongside with the second folding (5) are welded to main body (1) of the plastic film but not to each other. Moreover the first folding (4) is welded to the main body (1) with successive stamp-weldings (8) that can be of any shape and preferably oval or circles having not larger dimensions than half the width (b) of the first folding (4) and are located preferably halfways between two successive transverse weldings (7i). In this manner the weight insertion pockets are formed, that also have an opening for inserting the weight in each pocket almost equal to the length of each pocket. The stamp-weldings (8) pull the first folding (4) towards the main body (1) of the plastic film where it clings in order to close the weight insertion openings and trap soil in the pockets.

Description

Plastic film for ground covering with formed edges

The invention refers to a plastic film for ground covering with formed edges along its sides that is destined for agricultural use. Each formed edge is folded twice towards the same direction, in such a manner that the first folding (4) has width (b) less than (c) of the second folding (5) and preferably to half the width of the latter. The superimposed parts of each formed edge are welded to each other with successive weldings along its length, preferably transverse and in such a manner that the first folding as well as the second are welded to main body of the plastic film but not to each other. Moreover the first folding is welded to the main body with successive stamp- weldings that can be of any shape and preferably oval or circles having not larger dimensions than half the width (b) of the first welding and are located preferably halfway between two successive transverse weldings. In this manner weight insertion pockets are formed, that also have an opening for inserting the weight in each pocket, almost equal to the length of each pocket. The stamp- weldings pull the first folding towards the main body of the plastic film where it clings in order to close the weight insertion openings and trap soil in the pockets.

The use of plastic films that have pockets at their sides is a modern method that is employed for covering cultivations that have to be still accessible under the covered space. Several solutions have been proposed and materialised by the same inventor.

Until now all proposed solutions include simple pockets intended for use with soil at the edges of the film that result from folding the film once and welding them to the plastic film with linear weldings. The openings for weight insertion in the pockets are formed by having small non-welded parts along the plastic film and they are half as long as the pocket itself. Through these small non-welded openings soil is inserted rather difficultly and it is a laborious task. When the film is applied on the field the workers have to open the pocket with one hand and with the other hand have to fill the aforementioned pocket. In order to understand how tedious and demanding this task is, it has to be mentioned that along each metre there are four (4) consecutive pockets and a worker could fill on average only 500 running metres per day, assuming non-comfortable postures and working under adverse weather conditions. The usual phenomenon observed, is that several pockets are omitted and the plastic film can be lifted due to winds in and strong gales.

Furthermore the pockets can be as easily emptied during the use of the film as they can be filled, because the film cannot hinder the soil from exiting the pockets and as a result the pockets have to be refilled during the harvesting period.

Thus there is the need for manufacturing a plastic film with which the exact opposite can be achieved. Namely to fill the weight pockets easily - or automatically - and in a practical manner, and on the other hand assuring that the soil is trapped and cannot escape. Such a proposal arose from the same inventor with PCT/GR02/00047 where the solution was to manufacture the pockets by folding the edges once so that a hopper where soil can be accumulated is formed above each pocket. The accumulated soil slides into the pocket through a small opening that exists between the hopper and said pocket. However the solution proved to be rather problematic since the accumulated soil would not readily slide into the pocket and would not be uniformly distributed into the pockets, on the contrary it would stay underneath the openings during the season that the plastic film was used the soil and would slowly slide out of the pockets.

The reasoning of filling the pockets of the film easily or automatically is also addressed by the current invention, however approaching the said problem from a different angle, where the film has been designed in such a manner that the soil can be readily and uniformly distributed into the pockets and it is also prevented from sliding out of them.

Figure 1 illustrates such a design of a plastic film and figures 2a-2f show several details of such designs.

One such way of manufacturing said plastic film is described in the following paragraphs.

The initial plastic film has any width (a) and length (1) and can be produced employing any of the known production methods. During its production or during a second production stage the two edges (2) along its length are folded to width (b) towards the mid-section of the plastic film leading to a residual length of (a-2b). The new edges (3) are folded again to a width (c) towards the mid-section of the film and in the same direction as before, so that (c) is larger than (b) and preferably about double than the latter so that the width of the end product is equal to a-2b-2c.

The formed plastic film is then directed to a welding station where along its formed two-folded edges the film is welded with successive weldings (7i) preferably transverse and at fixed step. These weldings can have any step and any form.

These transverse weldings (7i) are made in such a fashion that preferably the first (4) and the second (5) foldings are welded onto the main body (1) of the plastic film but not one onto the other (cross-section A- A of Figure 1). This is very important for the proper function of said formed pockets.

If one takes a closer look to the resulting pocket, one could see that between the first folding (4) of the plastic film and the second folding of said film (5) a tubular vault is formed. Furthermore between the main body (1) and the first folding (4) - that are transversely welded one onto the other - there are large openings of approximately equal length to the length of the pocket, through which all the quantity of the soil can readily slide directly into the pocket.

This construction up to the point described, allows the soil to readily enter the pockets but it does not entrap it.

For this reason at any location between two successive transverse weldings (7i) a stamp-welding or a group of stamp-weldings (8) is made that welds only the first folding (4) to the main body (1) of the plastic film and in particular not to its entire length (c) but preferably to less than half the length of it (Detail of figure 1). The stamp-welding (8) during the use of the film will assist the entrapment of the soil. Specifically as the pocket is filled with soil and its volume increases the second folding (5) would be gradually distanced from the main body (1) of the plastic film as well as from the first folding (4) letting each pocket to assume the form of a tubular vault. However the more the first folding (4) is distanced from the second (5), by allowing the volume between them to be filled by soil, the more it would cling onto the main body of the plastic film (1) - due to the existence of the stamp- welding (8) - closing the opening through which soil can enter or escape from the pockets, thus entrapping the soil that has already entered it. The stamp-welding can be of any shape such as a circle, oval, square, triangle, rectangle etc. The successive transverse weldings (7i) are simple linear weldings (7.1,

Figure 2a) or they could be reinforced at their inner end in order to avoid tearing the film at this rather delicate point. The reinforced sections can comprise small horizontal lines (7.2, Figure 2b) or two inclined lines (7.3, Figure 2c) or they can be stamp-weldings (7.4, Figure 2d) etc. and they can be in contact with or at a small distance from the transverse welding. Alternatively instead of a stamp- welding or a group of stamp-weldings, (8) there can be two or more stamp-weldings (8) (Figure 2e, 2f) between two consecutive transverse weldings (7i).

It is obvious that there can be infinite such formed edges by altering the width of the foldings or by altering the shape and the succession of the weldings. When the film is used and after the grower has applied the film on the cultivation line he could throw soil onto the plastic film filling numerous pockets simultaneously, in a manual or automated fashion, in considerably less time compared to the time needed to fill one pocket at a time with the conventional systems. The soil slides through the openings to the pockets and it is entrapped in them due to the synergistic effect of the edges folded twice, the transverse weldings and the stamp-weldings.

Claims

1. Plastic film for ground covering with edges formed in such a fashion so that weight insertion pockets are formed along its sides, that is characterised by the fact that each edge along its side: a. Is folded twice towards the same direction in such a manner that the first folding (4) has width (b) less than width (c) of the second folding (5) and is preferably equal to its half. b. It bears successive weldings (7.i) preferably transverse, of equal or smaller length than width (c) of the second welding that weld the first (4) and the second (5) weldings to the main body (1) of the plastic film without necessarily welding the two of them together, c. It bears between two successive transverse weldings (7i), preferably at half the distance between them, a stamp-welding or a group of stamp- weldings, that weld the first folding (4) to the main body (1) of the plastic film and which have transverse dimensions smaller than the width (b) of the first folding (4) and preferably about the half of it.

2. Plastic film for ground covering with formed edges according to claim 1, that is characterised by the fact that the successive weldings (7i) are reinforced at their inner end, employing a small horizontal welding that spans symmetrically on each side of their axis (7.2) or small inclined weldings at each side of the transverse welding (7.3) or a reinforcement that has the form of a stamp (7.4) etc., in contact with or at a small distance from the main transverse part.

3. Plastic film for ground covering according to claims 1 and 2, that is characterised by the fact that it bears, between two consecutive weldings (7i) two or more stamp-weldings or a group of stamp-weldings (8).

4. Plastic film for ground covering with formed edges according to claims 1 to 3 that is characterised by the fact that, the stamp-weldings can have any possible shape such as circle, oval, square, rectangle, triangle etc.