Patent Description:
In greenhouses it is sometimes necessary to use insect nets in ventilation openings to prevent unwanted insects to enter the greenhouse and in some instances to keep wanted insects from leaving the greenhouse. When installing insect nets in an existing greenhouse, problems with elevated temperatures or humidity or low carbon dioxide levels may arise since insect nets will always to some extent impair the ventilated air flow. This must be considered when designing greenhouses.

Roofs of conventional glass greenhouses are provided with ventilation windows that can be opened and closed. When installing insect nets in such windows, the net installation must be flexible to fill the opening of the window when it is opened, but also be able to fold out of the way of the closing window. One conventional way of doing this is to confection an accordion-type of net construction as seen in <FIG>.

To be able to produce such a construction it is conventional to first produce insect net lamellas, which thereafter are confectioned together into the accordion shape. The lamellas are easily produced using conventional band weaving technique resulting in lamellas with closed longitudinal edges, which can be confectioned with sewing machines. However, there is also a substantial disadvantage of this way of making insect nets, since band weaving produces double weft inserts, and double yarns next to each other decrease the air flow through the net. Without double weft inserts, the airflow increases typically <NUM>-<NUM>%.

To avoid this problem, a conventional full width weaving loom can be used, producing a net typically <NUM>-<NUM> wide. This insect net can be chosen to have any weaving pattern, thereby optimizing ventilation and insect exclusion. The net is later cut into lamellas using a one-step ultrasonic cutting and welding process, leaving a closed edge on the net lamella, suitable to confection with a sewing machine.

A method of manufacturing an insect net according to the preamble of claim <NUM> is already known from <CIT>.

The above objects are achieved with an insect net strip in accordance with claim <NUM> and with a method of manufacturing an insect net strip according to claim <NUM>. Further embodiments are set out in the dependent claims, the description and in the drawings.

As set out herein there is provided a one-step ultrasonic cutting and welding method of manufacturing an insect net strip suitable for confectioning by a sewing machine. The method comprises the steps of.

As set out herein there is also provided an insect net strip produced by cutting the insect net described below along its warp direction (xnet) using the one-step ultrasonic cutting-and-welding method disclosed herein. The insect net strip comprises:.

At least <NUM>% of the warp and weft yarns of the insect net strip are monofilament yarns made of a thermoplastic material, and.

In a further aspect of the invention there is also provided accordion-type assemblies wherein two or more of the inventive insect net strips as described herein which have been produced according to the method also described herein have been sewn together to form accordion-style insect net constructions for use in ventilation openings.

In yet a further aspect of the invention, there is provided a use of the insect net strip as described herein and produced as described herein, in a confectioned accordion-type assembly wherein two or more insect net strips are sewn together.

In the following detailed description, reference is made to the accompanying set of drawings that form a part of the description hereof and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated within the scope of the claims. The following detailed description, therefore, is not to be taken in a limiting sense.

The insect net strip <NUM> described herein is made from a wide (<NUM>-<NUM>) woven insect net cut in the warp direction. <FIG> is a view of a woven insect net <NUM> used for making the insect net strips <NUM> disclosed herein. As seen in <FIG> showing details of the insect net <NUM>, the insect net <NUM> comprises warp yarns <NUM> extending in a warp direction (xnet), i.e., the longitudinal direction of the net, and weft yarns <NUM> having a weft yarn diameter (øwe), and extending in a weft direction (ynet), i.e., the transverse direction of the net. The weft yarns <NUM> extend perpendicular, or substantially perpendicular to the warp yarn direction (xnet) and alternately go over and under the consecutive warp yarns <NUM>. The warp yarns <NUM> and the weft yarns <NUM> are spaced apart from each other leaving air gaps or holes <NUM> in between, wherein the air gaps or holes <NUM> have a width a in the weft direction (ynet) and a length b in the warp direction (xnet) as can be seen in <FIG>. The insect net <NUM> has a first and a second woven selvage edge <NUM>, <NUM> extending in a longitudinal direction of the insect net, parallel to the warp yarns <NUM>. The total width (wnet) of the insect net <NUM> in the transverse direction (ynet) is advantageously adapted to the width of a conventional loom configured to weave an insect net, i.e., about <NUM>-<NUM> wide.

At least <NUM>% of the warp and weft yarns in the insect net are monofilament yarns, made of a thermoplastic material. The insect net can be manufactured from monofilament yarns of any conventional thermoplastic fiber material but advantageously ><NUM> wt. % of the thermoplastic monofilament yarn is a polyester or co-polyester conventional for fiber production, the wt. % being calculated based on the total weight of the yarn. Preferably the polyester is polyethylene terephthalate (PET), wherein at least <NUM> wt. % of the polyester originates from ethylene terephthalate monomers. Additives and other polymers make up the rest. The thermoplastic monofilament yarn material typically has a melting point of <NUM>-<NUM> and a density of <NUM>-<NUM>/cm<NUM>.

Since high air permeability is vital to be able to cool and dehumidify the greenhouse, air permeability is a very important factor in the performance of the insect nets when placed in ventilation openings. However, the main purpose for applying an insect net in openings of a greenhouse is to prevent harmful insects from entering the greenhouse, as well as in some instances, preventing useful insects from escaping the greenhouse. This will only be successful if the size of each one of the open areas in the insect net is small enough to prevent insect passage. Thus, when manufacturing an insect net there is an important balance between optimizing the important air permeability, while at the same time preventing insects from passing through the net.

To optimize air flow, i.e., to increase the air flow, the insect net disclosed herein has a weaving pattern wherein at least <NUM>%, preferably at least <NUM>%, more preferably at least <NUM>%, of the weft inserts are single yarn inserts. Weaving with single weft inserts is advantageous since it enables many different weaving patterns that can optimize insect control. Single weft inserts are advantageous compared to double weft inserts which often diminish air permeability, as will be explained below.

Another factor influencing the air permeability of an insect net is its relative hole area (Ah). The larger the hole area the insect net has, the better air permeability becomes. The insect net used for manufacturing insect net strips herein has a relative hole area in a two-dimensional projection (Ah) of <NUM>-<NUM>%. However, the relative hole area for the insect net is normally <NUM>-<NUM>% to avoid passage of some common insects (see below). The relative hole area in a two-dimensional projection is defined by the ratio of the area of holes to the area covered by yarns in a given area of insect net, and is calculated as follows: <MAT> wherein as seen in <FIG> and <FIG>.

This means that <NUM>% of the total area of the net is covered with holes, the rest (i.e., <NUM>%) is covered by yarn.

This should be compared to an insect net with double weft inserts wherein the dimension of the hole is the same, i.e., <NUM> x <NUM>, the warp yarn diameter (øwa) is <NUM>, and the weft yarn diameter (øwe) is <NUM>.

Such an insect net has a relative hole area (Ah) of <MAT>.

With double weft inserts which is often used in conventional band weaving, the air permeability is less, <NUM>% as compared to <NUM>% with single weft inserts. With wide weaving the weave can be optimized for insect control and high air flow, meaning better possibility to cool and dehumidify the greenhouse, while still preventing passage of unwanted insects. <FIG> show the difference between single and double weft inserts, wherein in <FIG> a band woven insect net with double weft inserts can be compared to an insect net with single weft inserts in <FIG>.

The insect net disclosed herein has a hole size of <NUM>-<NUM> in a two-dimensional projection, i.e., in warp and weft directions of the insect net <NUM>. Preferably the hole size in a two-dimensional projection of the insect net <NUM> is <NUM>-<NUM>, more preferably <NUM>-<NUM>, most preferably <NUM>-<NUM>. This means that the holes of the insect net should have an extension in the warp and/or weft direction of <NUM>-<NUM>, i.e., the extension a in the weft direction is <NUM>-<NUM> and the extension b in the warp direction is between <NUM> to <NUM>. The hole size of the insect net limits the possibility for insects to enter/exit the greenhouse and should be adjusted depending on the type of insect the net is intended to stop. Whiteflies (of the family Aleyrodidea) are stopped by holes having a size of about <NUM> x <NUM>, and Thrips require holes having the size <NUM> x <NUM>, or less to prevent passage.

The insect net disclosed herein has a cross-sectional weft yarn area per net length (A'we/x) of <NUM>-<NUM><NUM>/m in a warp yarn direction. Advantageously, the cross-sectional weft yarn area per net length (A'we/x) is <NUM>-<NUM><NUM>/m in a warp yarn direction. The cross-sectional weft yarn area per net length indicates the area of material the weft yarns accumulate per unit length in the warp direction and is influenced both by the weft yarn diameter (øwe) and weaving picks per cm.

The cross-sectional weft yarn area per net length in the warp yarn direction (A'we/x) of the insect net is determined by the cross-sectional area (A'we) of the weft yarn <NUM> used for weaving the insect net <NUM>, and the number of weaving picks per meter in the warp yarn direction (xnet). Each weft yarn <NUM> has a cross sectional area A'we = π + r<NUM> measured in mm<NUM>. The weaving picks indicates the number of weft yarns <NUM> inserted between the warp yarns <NUM> per meter in the warp yarn direction (xnet) and depends on the distance between two adjacent weft threads, i.e., the length (b) of a hole <NUM>, as well as the diameter of the weft yarn (øwe), both measured in mm (see <FIG>). Thus, the cross-sectional weft yarn area per net length (A'we/x) of the insect net can be calculated as follows: <MAT> wherein.

A method of manufacturing an insect net strip <NUM> from the insect net <NUM> as disclosed above will now be described. The insect net strips <NUM> are advantageously used for confectioning accordion-type insect net assemblies <NUM> (see <FIG>), that may be used in openings to allow ventilation while at the same time prevent passage of insects therethrough. Advantageously the same accordion-type assemblies are further confectioned into accordion-style net constructions <NUM> for use in greenhouse roof ventilation openings as seen in <FIG>.

A one-step ultrasonic cut and seal process is used to manufacture the insect net strip <NUM>, wherein the method comprises the steps of.

The ultrasound cutting and welding tools <NUM> are advantageously cutting wheels (see detail of <FIG>). The cutting wheel used in the ultrasonic cutting and sealing process is selected in such a way that it both cuts the weave and seals the edge in one step. It is also optimized to leave a very narrow deformation zone <NUM>, facilitating subsequent confectioning of the insect net strip <NUM>.

Advantageously an ultrasonic device <NUM> wherein the cutting and welding tool <NUM> is a rotating blunt U-, V- or a mixed U/V- shaped cutting edge is used. The advantage of a rotating wheel is the slower blunting of the edge. The machine also runs smoother with less friction.

When the ultrasonic cutting and welding tools has a V-profile it advantageously has an edge angle α of <NUM>°-<NUM>°, preferably an edge angle α of <NUM>°-<NUM>°, or more preferably an edge angle α of <NUM>°-<NUM>° (see <FIG>).

When the ultrasonic cutting and welding tools has a U-shape it advantageously has an edge radius r of <NUM>-<NUM>, preferably an edge radius r of <NUM>-<NUM> (see <FIG>).

When the ultrasonic cutting and welding tools has a U/V-mix profile it advantageously has an edge angle α of <NUM>° - <NUM>°, preferably an edge angle α of <NUM>° - <NUM>°, or more preferably an edge angle α of <NUM>° - <NUM>°, and an edge radius r of <NUM>-<NUM>, preferably an edge radius r of <NUM>-<NUM> (see <FIG>).

The ultrasonic cutting and welding tool may also have a V-profile with more than one angle, wherein the first angle α<NUM> is <NUM>° - <NUM>° and the second angle α<NUM> is <NUM>° - <NUM>° (see <FIG>).

The ultrasonic energy is applied through a sonotrode <NUM> (see detail of <FIG>) opposing the cutting and welding tool <NUM>. With high enough power applied on the blunt edge of the cutting and welding tool, the weft yarns will be melted together to form a mechanically sealed edge The ultrasonic surface (sonotrode) provides a frequency of <NUM>-<NUM> and an electrical power of <NUM>-500W per cutting/welding tool. This power can be expressed as electrical power put into the ultrasonic controller in relation to the feeding speed of the cloth/net through the cutting machine. The woven insect net <NUM> is fed through the ultrasonic cutting device <NUM> at a speed of <NUM>/min - <NUM>/min.

The ultrasonic cutting and sealing device must apply enough energy in relation to the speed feeding the insect net <NUM> through the ultrasonic cutting device <NUM> to be able to properly melt together the weft yarns resulting in a sealed edge. The cutting edge of the cutting and welding tool <NUM> must have an angle large enough to not just cut, but also to melt the adjacent material. Merely cutting can be performed with a sharper tool and is an easier task than the combined sealing/melting process described herein.

The shape of the cutting tool <NUM> and the power applied will result in a deformed (melted) zone <NUM> some distance away from the edge as seen in <FIG>. This can be seen and measured under the microscope. The width (wdz) of the deformed zone <NUM> is within a certain range if a suitable power, speed and tool shape has been used.

In a further embodiment, the ultrasonic cutting and welding tool <NUM> may be provided with a flat anvil block <NUM> which is placed in front of the cutting wheel (see <FIG>). The flat anvil block <NUM> ensures that the insect net <NUM> intended to be cut is kept close to the sonotrode <NUM> i.e., the counterpart to the cutting and welding tool <NUM> through which the ultrasonic energy is applied. The anvil block <NUM> is advantageously provided with a flat rectangular surface <NUM> which is in contact with the insect net <NUM> being fed into the ultrasonic cutting device <NUM>. The flat rectangular surface has an area of <NUM>-<NUM> x <NUM>-<NUM>, preferably <NUM>-<NUM>,<NUM> x <NUM>-<NUM> (see <FIG>, showing the flat rectangular surface <NUM> that abuts the insect net). The cutting wheel is of the same types as described above. Also, the ultrasonic effect, the frequency and speed are the same as used for the cutting and welding tool <NUM> without a flat anvil block <NUM>.

The flat anvil block <NUM> ensures that at least one warp yarn <NUM> is included in the deformation zone <NUM>, resulting in reliable edges for the insect net strip <NUM> without risk of warp yarns <NUM> unraveling from the edges <NUM>, <NUM>. <FIG> is a view of the edge of an insect net strip produced by a cutting and welding tool <NUM> provided with a flat anvil block <NUM>.

The resulting edges <NUM>, <NUM> are suitable for further confectioning of insect net systems if the weft yarns are connected (melted together) in most cases. The edge is considered suitable if <NUM>% or more of the gaps between adjacent weft yarns in the deformation zone <NUM> have a mechanical connection by weft yarns being melted together. The deformation zone <NUM> along the insect net strip is visible under a microscope and can be measured on the end product.

<FIG> shows an insect net strip <NUM> of the invention which has been produced by cutting an insect net <NUM> described above in a warp direction (xnet). As seen in <FIG>, the insect net strip comprises warp yarns <NUM> extending in a longitudinal direction (xstrip), i.e., in the warp direction of the insect net strip <NUM>, and weft yarns <NUM> having a weft yarn diameter (øwe), and extending in a transverse direction (ystrip), i.e., in the weft direction of the insect net strip <NUM>. The weft yarns <NUM> extend perpendicular, or substantially perpendicular to the longitudinal direction (xstrip) and alternately go over and under the consecutive warp yarns <NUM>. The warp yarns <NUM> and the weft yarns <NUM> are spaced apart from each other leaving air gaps or holes <NUM> in between having a length b in the warp direction (xstrip) and a width a in the weft direction (ystrip).

At least <NUM>% of the warp and weft yarns <NUM>, <NUM> of the insect net strip <NUM> are monofilament yarns, made of a thermoplastic material. The insect net strip <NUM> can be manufactured from monofilament yarns of any conventional thermoplastic fiber material but advantageously ><NUM> wt. % of the thermoplastic monofilament yarn is a polyester or co-polyester conventional for fiber production, the wt. % is calculated based on the total weight of the yarn. Preferably the polyester is polyethylene terephthalate (PET), wherein at least <NUM> wt. % of the material originates from ethylene terephthalate monomers, with the remaining <NUM> wt. % being additives and/or other polymers. Such a material typically has a melting point of <NUM>-<NUM> and a density of <NUM>-<NUM>/cm<NUM>.

The insect net strip <NUM> has a weaving pattern wherein at least <NUM>%, preferably at least <NUM>%, more preferably at least <NUM>%, of the weft inserts <NUM> are single yarn inserts. As explained above for the insect net, weaving with single weft inserts provides the insect net strip with advantageous air-permeabilities.

Advantageously, the insect net strip <NUM> has a relative hole area (Ah) in a two-dimensional projection of <NUM>-<NUM>%, but in order to better prevent insect passage, the relative hole area (Ah) for the insect net strip is advantageously <NUM>-<NUM>%. The relative hole area (Ah) in a two-dimensional projection is defined by the ratio of the area of holes to the area of yarns in a given area of insect net strip and is calculated as shown for the insect net in Formula I above.

The insect net strip <NUM> disclosed herein has a hole size of <NUM>-<NUM> in a two-dimensional projection, i.e., in both the longitudinal and transverse direction of the insect net strip <NUM>. Preferably the hole size in a two-dimensional projection of the insect net strip <NUM> is <NUM>-<NUM>, more preferably <NUM>-<NUM>, most preferably <NUM>-<NUM>.

The insect net strip <NUM> disclosed herein has a cross-sectional weft yarn area per net length (A'we/x) of <NUM>-<NUM><NUM>/m in a longitudinal direction (xstrip). Advantageously, the cross-sectional weft yarn area per net length (A'we/x) is <NUM>-<NUM><NUM>/m in a longitudinal direction (xstrip). The cross-sectional weft yarn area per net length (A'we/x) indicates the material area the weft yarns <NUM> add per unit length in the longitudinal direction (see <FIG>). It is determined by the weft yarn <NUM> diameter (øwe) and weaving picks per meter (m) and is calculated as given in Formula II as described for the insect net above.

The insect net strip <NUM> is obtained by cutting the insect net <NUM> described above in the warp direction (xnet) into strips <NUM> having a width (wstrip) in the transverse direction (ystrip) of <NUM>-<NUM>, preferably a width of <NUM>-<NUM>.

After cutting the insect net <NUM> using the method described herein, the obtained insect net strip <NUM> will have a first edge <NUM> and a second edge <NUM> extending in a longitudinal direction of the insect net strip <NUM> (i.e., in a warp direction (xstrip)) and parallel to the warp yarns <NUM>. The first and second edges <NUM>, <NUM> each comprise a deformation zone <NUM> being constituted by consolidated thermoplastic material deriving from at least the weft yarns <NUM> which have melted together to form a deformation zone <NUM>.

The deformation zone <NUM> is defined as the average distance between the outer edge <NUM>, <NUM> and the visual deformations that has affected the roundness of the outer-most tips of the weft yarns and can be measured under a calibrated microscope.

The deformation zone <NUM> will have a length along the first and second edge <NUM>, <NUM>, and a width (wdz) in the transverse direction (ystrip), wherein the width (wdz) of the deformation zone <NUM> is <NUM>-<NUM> times the weft yarn diameter (øwe) as seen in <FIG>.

This means that with a weft yarn diameter of <NUM>, the width (wdz) of the deformation zone <NUM> is between <NUM> to <NUM>, and with a weft yarn diameter of <NUM>, the deformation zone <NUM> is between <NUM> and <NUM> wide. Preferably the deformation zone <NUM> has a width (wdz) which is <NUM>-<NUM> times the weft yarn diameter (øwe), <NUM>-<NUM> times the weft yarn diameter (øwe), or more preferably the deformation zone <NUM> has a width (wdz) which is <NUM>-<NUM> times the weft yarn diameter (øwe).

To form strong first and second edges <NUM>, <NUM> which will enable good confectioning and prevent unraveling, at least <NUM>% of gaps <NUM> between adjacent weft yarns <NUM> in the deformation zone <NUM> must be closed by consolidated thermoplastic material deriving from at least the weft yarns <NUM> which have melted together. This means that no more than one gap <NUM> out of ten gaps <NUM> between two adjacent weft yarns <NUM> in the deformation zone <NUM> is left unclosed along the cut edge <NUM>, <NUM>. Preferably at least <NUM>%, such as at least <NUM>%, such as at least <NUM>% of the gaps <NUM> between adjacent weft yarns <NUM> are advantageously closed by consolidated thermoplastic material from the weft yarns <NUM> having been melted together in the deformation zone <NUM>.

When used herein, the expression "closed by consolidated thermoplastic material" is intended to mean that adjacent weft yarns <NUM> together with preferably no more than two warp yarns 21a, 21b are melted together with each individual weft yarn <NUM> in the deformation zone <NUM> and form a continuous, or substantially continuous reinforced band-shaped edge portion <NUM>, <NUM> of the insect net strip <NUM>. Ideally, at most one warp yarn 21a is melted together with each individual weft yarn <NUM> in the deformation zone <NUM> to form a continuous, or substantially continuous reinforced band-shaped edge portion <NUM>, <NUM> of the insect net strip <NUM>.

<FIG> is a view of an edge <NUM>, <NUM> of an insect net strip <NUM> cut and sealed by the method described herein. It is seen that the outer ends of all weft yarns <NUM> are thoroughly melted together with the outer most warp yarn 21a along the edge <NUM>, <NUM> to form a deformation zone <NUM> with consolidated thermoplastic material as described herein. Ideally only the outer most warp yarn 21a, i.e., the warp yarn closest to the cut edge <NUM>, <NUM> is involved in the consolidation of thermoplastic material as seen in <FIG>. However, it is acceptable that also the warp yarn 21b second next to the cut edge <NUM>, <NUM> is melted together with each individual weft yarn <NUM> to be included in the consolidation of thermoplastic material in the deformation zone <NUM>. However, in order to provide a narrow edge <NUM>, <NUM> it is preferable that no warp yarns are included in the consolidated thermoplastic material of the deformation zone (see <FIG>). This is acceptable as long as at least <NUM>% of gaps <NUM> between adjacent weft yarns <NUM> in the deformation zone <NUM> are closed. <FIG> is a view of a deformation zone <NUM> wherein some gaps <NUM> (see A, B and C) between adjacent weft yarns <NUM> are not fully closed.

As described above, the width (wdz) of the deformation zone depends on weft yarn thickness. A thinner yarn may give a narrower deformation zone but can still result in a well-sealed edge if the weft material area per net length (A'we/x) is high enough. Wider deformation zones require more power to produce, and consequently there is a practical/economical upper limit of how wide the deformation zone should be.

There is also a disadvantage with a deformation zone which is too wide or solid since it will be harder for a needle to penetrate when confectioning. Very wide deformation zones also tend to smear the melted plastic, resulting in an uneven edge, which also is negative in confectioning.

There are several advantages in manufacturing the insect net strips <NUM> using the method disclosed herein as compared to conventional band weaving to produce the lamellas. The most important advantage being the possibility to use many different weaving patterns and the avoidance of any double weft inserts. With conventional band weaving double weft inserts are often used which will diminish air permeability of the insect net. With wide weaving, the weave can be optimized for insect control and high air flow, resulting in an improved possibility to cool and dehumidify the greenhouse.

Careful selection of weft yarns and the number of picks per centimeter will give the insect net strip <NUM> a high stiffness in the weft direction, making the finished accordion construction robust and more self-supporting, thereby reducing the need of other mechanical support to hold the construction in place in the greenhouse. The shape of the holes in the net may be turned such that they have their longest extension in the weft direction. In this way more material is available for the one-step ultrasonic cut and seal process which will also improve the stiffness in the weft direction, making a subsequent accordion construction stiffer, thereby further reducing the need for extra support in the final product.

Since the selection of warp yarns is of less importance in the present process, it is instead possible to use the warp yarns to optimize the net for insect control and high air flow.

Another advantage is that narrow edges are produced on each side of the insect net strip by the method disclosed herein. Conventional band weaving produces lamellas with bulky selvage edges. This can be seen in <FIG> which is a view of a longitudinally extending edge on a band woven net. Since the double inserted weft yarns each make a loop around the outer most warp yarn, a large amount of material is added in this area. This should be compared to the edges formed using the method disclosed herein (see e.g., <FIG>).

The ultrasonic cutting and sealing technique used in the present method provides an insect net strip with a smooth edge having a deformation zone with a limited width. Weft yarns and the number of picks per centimeter can be selected to give a cross-sectional weft yarn area per net length which is high enough for the edges along the insect net strip to be sealed without including any warp yarn, or at the most one warp yarn. However, one, or at most two warp threads may be included in the deformation zone with consolidated weft and warp yarns. As long as at least <NUM>% of the gaps between adjacent weft yarns are closed, the edges are suitable for confectioning.

The narrow deformation zones are advantageous since wide areas with melted plastic are more difficult for the needle on the sewing machine to penetrate. When lamellas are sewn together to an accordion-type assembly later in the process, the total thickness of the construction becomes substantially lower (><NUM>%) using insect net strips produced with the method disclosed herein. In a greenhouse, everything that is smaller in the ceiling means less shading and more light reaching the plants.

Weaving wider nets and thereafter cutting them into narrow strips using the one-step cutting and sealing method described herein provides a great advantage for the end product.

The insect net strips <NUM> produced by the disclosed method are advantageously used for producing accordion-type insect net assemblies <NUM> (see <FIG>). Such accordion-type assemblies <NUM> can be used in ventilation openings to increase the total area of ventilation through an opening compared to a flat net covering the same opening. The accordion-type assemblies <NUM> may advantageously be used for manufacturing accordion-style ventilation screens <NUM> as can be seen in <FIG> and <FIG>. Such accordion-style ventilation screens <NUM> are typically made from two accordion-type assembly side screens <NUM> connected to an accordion-type assembly middle screen <NUM>.

During production of an insect net accordion-style assembly <NUM>, two insect net strips 20a, 20b are put flat on top of each other and sewn together along one edge <NUM>, <NUM> at the most <NUM> from the outer edge <NUM>, <NUM>. An additional insect net strip 20c is put on top of the first two and sewn together with the upper most insect net strip 20b along the opposite longitudinal edge <NUM>, <NUM> in the same way. This can be repeated with the desired number of insect net strips <NUM> to form an accordion-style assembly <NUM> as seen in <FIG>.

Since the insect net strips <NUM> are made from a material which is stiff enough, no undesired creases or folds will form and when the accordion-style assemblies <NUM> are folded shut, the individual insect net strips <NUM> will lie flat against each other.

For the side screens <NUM>, a triangular recess <NUM> is cut from the accordion-style assembly <NUM> as can be seen in <FIG>. The longitudinal edges 65a, 65b along the recess <NUM> are connected as shown by the arrows, thereby forming a side-screen part <NUM> as shown in <FIG> that can be coupled to the middle screen <NUM> to form the accordion-type screen <NUM> as seen in <FIG>.

The accordion-type screen construction <NUM> can be used in all greenhouse ventilation openings to stop unwanted insects entering the greenhouse. The accordion style confectioning gives a larger total net area than a flat net, with typically <NUM>-<NUM> % higher air flow through the ventilation opening. It is also a flexible construction and easily fixed in a greenhouse ventilation window that can be opened and closed. An example of an accordion style construction is described in <CIT>(C2).

The following examples disclose net insect strips having been cut using the one-step cutting and sealing method described herein.

<FIG> are views of edges cut using the method described herein. <FIG> shows an ideal edge formed in an insect net strip having a cross-sectional weft yarn area per net length of <NUM><NUM>/m. Here it is seen that the outermost warp yarn is included in the deformation zone and that the outer ends of all weft yarns, together with the outermost warp yarn has formed a solid consolidation of thermoplastic material. <FIG> is a view of an insect net strip having a cross-sectional weft yarn area per net length of <NUM><NUM>/m. Although the outermost warp yarn is not completely included in the consolidation of thermoplastic material, the formed edge is still acceptable since gaps between adjacent weft threads are closed. <FIG> show insect net strips having a cross-sectional weft yarn area per net length of <NUM><NUM>/m (16c), and <NUM><NUM>/m (16d) respectively. Here it can be seen that these insect net strips do not have a cross-sectional weft yarn area per net length to obtain an edge with an acceptable deformation zone. The weft yarns cannot melt together to form a consolidation of thermoplastic material thick enough to be able to close gaps between adjacent weft yarns.

<FIG> disclose insect net strips having a yarn thickness of <NUM> and a weft material area per net length of <NUM><NUM>/m which were cut using a frequency of <NUM>, a power of 500W, and at a cutting speed of <NUM>/min by means of different cutting tools. <FIG> shows a deformation zone formed using a V-shaped cutting tool with an edge angle α of <NUM>°. As can be seen in the figure, the deformation zone is acceptable. Although no warp yarn is included in the consolidated thermoplastic material, the gaps between adjacent weft yarns are closed. <FIG> shows the same net having been cut using a hybrid V/U-shaped head with an edge angle α of <NUM>° and a radius r of <NUM> in the center and <NUM>° outside that. This limits the size of the deformation zone but still leaves a good welding with an even edge. <FIG> discloses the net being cut using a V-shaped tool having an edge angle of <NUM>°. This cutting tool is too sharp for this type of net since the warp yarn can easily be pulled out. In <FIG>, a V-shaped tool having an edge angle of <NUM>° was used. This tool is much too sharp since the outer most warp yarn is not held in place.

<FIG> disclose insect net strips having a yarn thickness of <NUM> and a weft material area per net length of <NUM><NUM>/m, which were cut by means of different cutting tools and using different machine settings. <FIG> discloses an insect net strip having been cut using a V-shaped cutting tool with an edge angle α of <NUM>° at a speed of <NUM>/min (500W). As seen the deformation zone is ideal with the outer most warp yarn included in the consolidated thermoplastic material. The edge is even and narrow, while still being strong.

<FIG> discloses an edge of an insect net strip cut using a V-shaped cutting tool having an edge angle α of <NUM>° at a speed of <NUM>/min (400W). Here it is seen that the cutting speed was too high leaving an uneven edge which will be difficult to process during later confectioning steps.

<FIG> shows an insect net strip that was cut with a V-shaped tool with an edge angle α of <NUM>° at a speed of <NUM>/min (400W). The cutting speed was too high since the yarns have not melted enough to form a deformation zone with a consolidated thermoplastic material wherein the gaps between adjacent weft yarns are closed.

Claim 1:
A method of manufacturing an insect net strip (<NUM>), said method comprises the steps of
a) providing a woven insect net (<NUM>) comprising
- warp yarns (<NUM>) extending in a warp yarn direction (xnet) of said woven insect net (<NUM>), and weft yarns (<NUM>) having a weft yarn diameter (øwe), and extending in a weft yarn direction (ynet) of said woven insect net perpendicular to, or substantially perpendicular to said warp yarn direction (xnet) of said woven insect net (<NUM>); and
wherein
- at least <NUM>% of said warp and weft yarns (<NUM>, <NUM>) are monofilament yarns made of a thermoplastic material; characterized in that it further comprises the steps of:
b) feeding said woven insect net (<NUM>) into an ultrasonic cutting device (<NUM>) comprising an ultrasonic surface (<NUM>) and at least two ultrasonic cutting and welding tools (<NUM>);
and
c) feeding said woven insect net (<NUM>) through said ultrasonic cutting device (<NUM>); to obtain an insect net strip (<NUM>) having
- a width (wstrip) in a transverse direction (ystrip), which is smaller than a width (wnet) of said woven insect net (<NUM>); and
- a first and a second edge (<NUM>, <NUM>) extending in a longitudinal direction (xstrip) of the insect net strip (<NUM>) and parallel to warp yarns (<NUM>) of said insect net strip (<NUM>), said first and second edges (<NUM>, <NUM>) each comprising a deformation zone (<NUM>) being constituted by consolidated thermoplastic material deriving at least from weft yarns (<NUM>) of said insect net strip (<NUM>), said deformation zone (<NUM>) having a length along the edge (<NUM>, <NUM>) and a width (wdz) in the transverse direction (ystrip) of the insect net strip (<NUM>), the width (wdz) of said deformation zone (<NUM>) being in the range of between <NUM> and <NUM> times the weft yarn diameter (øwe); and wherein
- at least <NUM>% of gaps (<NUM>) between adjacent weft yarns (<NUM>) in the deformation zone (<NUM>) are closed by at least said weft yarns (<NUM>) being melted together in said deformation zone (<NUM>), thereby forming a consolidated reinforced edge portion (<NUM>, <NUM>) of said insect net strip (<NUM>).