FR2777737A1 - Protective net for protecting plants against hail and heavy rain - Google Patents

Abstract

The protective net is of the woven type, made by thrown mesh technology and consisting of a network of two working lines (1,2) which are woven in a specific manner on the vertical rectilinear lines (3). These act as a spring to any transverse forces generated during the fall of hail stones. The specific weaving pattern gives the net a high resistance to tearing.

Description

A 2 777 737

  SCREEN - KNITTED WOVEN TYPE NET FOR

  PROTECTION OF CROPS FROM HAIL

  The present invention relates to a net particularly designed to be placed on crops and thus protect them from hail and rainstorms. For many years there have been nets for the protection of

  crops against the plague of hail.

  The purpose of the nets used was to prevent hail from reaching the crops by creating a screen fixedly arranged on very suitable support structures.

  resistant to withstand the possible load created by hail.

  Faced with the need to develop orchard protection on large surfaces, it appeared necessary to reduce the cost of installations and therefore to develop other systems such as that of mounting with elastic return nets or

  the mounting of flexible devices and much simpler implementation.

  The conventional woven, standard knitted or extruded type threads were well suited to previous installations but did not always give satisfaction in the principle of assembly with elastic return, taking into account the fixing methods and the

  very operation of the installation.

  The object of the present invention is precisely to propose a net of a new type having an elastic behavior on the one hand and comprising elements of

integrated fixing on the other hand.

  The net designated as TISSE-TRICOTE is made on discarded mesh technology machines and it is constructed according to a particular geometry which is

  described according to a mode defined by the diagrams of FIGS. 1, 2 and 3.

  Figure 1 shows schematically the general principle in elastic mounting. In this figure, we observe in zone A the rest position of the threads F1 and F2 which overlap in the central zone a, b. They are stretched by the elastic return systems E1 and E2. Zone B shows the position taken by nets F1 and F2 at the time of the hailstorm which creates a ballast load 1 and 2 which lowers the nets down in the inter-row zone located between aisles d trees or crops. The elastic system then accepts the movement of the nets which, by discharging

  do not bring any overload on the installations and on the trellising structures.

  Figure 2 represents the general diagram of the net which includes at least 3 games

of different wires 1, 2 and 3.

  Lt 2777737 Threads 1 and 2 work according to a specific mesh binding mode. The vertical threads 3 inserted, as in conventional weaving, in the warp or production direction are arranged in a completely rectilinear manner. They provide a net reinforcement function in the production direction on the one hand and the spring role on the other hand. This second function is very important in the operation of a hail barrier with elastic return or flexible device because, precisely, the net entrained by the weight of the hail and released by the elastics must perfectly return to its initial position after spillage without undergoing "poaching". "and deformation

permed.

  The diagram in fig 3 illustrates the principle of spring. The forces F1 exerted on the net in the transverse direction during the fall of the hail tend to cause the deformation of the wires 3 while in opposition to this are staggered the forces F2 internal to the net as well as the general tension T of the net in the longitudinal direction i.e.

  in the length of the rows of crops.

  The wires 3 which are stretched under the general tension T and which therefore cannot accept to lengthen under the zig zag effect oppose this action by creating a SPRING effect which allows the net to react with an excellent elastic recovery without

  risk of poaching or residual deformation.

  FIG. 4 illustrates the network of the net with wires which alternately work in mesh and in sectional weft by resting on the vertical wires, thus preventing any slipping and therefore always maintaining the correct size of the openings, even

  if there is friction on the support structures or directly on the vegetation.

  FIG. 5 shows the arrangement of the insert or fixing cable C integrated directly with the manufacturing. In a particular embodiment, the cable C is

  maintained in the structure of the net with the binding presented in the previous figure 4.

  Figures 6 and 7 show respectively mounting examples with

  classic elastic return system and non-tensioned system with slope.

  In the first device fig. 6, the insert or cable is integrated directly into the production on the edge of the net. This therefore makes it possible to stiffen the selvedge, to considerably reinforce it and allows direct attachment of the fastening elements, in particular

  the bungee cords in the case of elastic return mounting.

  This insert or cable thus integrated also plays the role of force distributor on the edge of the net, avoiding the risks of tearing when the attachment is punctual.

  as is the case with some hooks or pads.

3 2777737

  In the 2nd installation method, fig. 7, the insert or cable I1 for fixing is arranged with the same principle but at a certain distance (d) from the edge of the net so as to create a protective "flap". The latter limits the risks in the case of hail projected at an angle by the wind; the 2 sides of the net are then connected by means D1 either rigidly or flexibly, that is to say allowing the spacing of the 2

  sections of net for "spillage" of hail.

  In another version of the net shown in fig. 8 the insert or cable was also introduced in the central position I2 of the net, this to allow direct fixing to the trellising posts without requiring the installation of any other wire or ridge cable. The connection between 2 sections of net can be done either by D2 connection or also

with the principle of figure 6.

  The advantages of all these innovations provide effective and economical technical responses compared to other types of net which require expensive fixing means, additional equipment (special hooks, plates ...) and impose installation times. longer. The net object of the invention ensures, by its general quality, greater durability of the installations. In a standard version, this net is made up of translucent high density polyethylene technical threads treated against the aggression of ultraviolet radiation. This net has a very low degree of shade and a very high resistance over time despite its permanent exposure to the sun and bad weather.

Claims (5)

  1. Hail protection net characterized in that it is of the woven-knitted type produced in the discarded knit technology comprising a network of threads working alternately in knit and in sectional wefts as well as completely straight threads in the production direction, the technical yarns of known behavior, arranged in a rectilinear direction in the production direction acting as a spring with respect to the forces exerted transversely on the net during the fall of hail, and the alternation of the work of the yarns in meshes and in weft combined the arrangement of straight wires giving the net high tear resistance and almost   impossibility of its propagation when it occurs.   2. Net according to claim 1 characterized in that it comprises on the edges an insert or cable integrated directly in manufacturing to allow the fixing of the net without adding claws or combs, these inserts or cables act as a force distributor avoiding one-off charges which may cause   tears damaging to the net.   3. Net according to claim 2 characterized in that it incorporates inserts or fixing cables on the edges and also in the center of the net to allow fixing   directly on the trellising posts or for other types of mounting.   4. Net according to either of the preceding claims, characterized in that it   is made of specific synthetic material adapted to not create significant shade on crops and very long life despite exposure   permanent in the sun and bad weather.   5. Use of the net according to any one of claims 1 to 4 in assembly with   system called elastic return or all flexible mounting devices.