DE1486566A1 - Process for the extrusion of knotless plastic nets and plastic nets produced by the process - Google Patents

Description

Title: Method for extrusion of knotless plastic nets and plastic nets produced by the process.

Description (P 14 86 566.8-27) The invention relates to a A method of extruding knotless plastic netting in which two sets of Extrusion head mouths arranged at a distance from one another for the purpose of connecting the Net mesh strands of the one set by strand crossings with the strands of the other set can be moved relative to each other.

The invention also relates to the method mentioned manufacturable, extruded knotless nets of plastic of the kind such in the British patent pen 836 555 and by means of the also there described device or similar devices can be produced. By using of these devices, the pressed strands form network crossings by mutual Touch and adhesion with or nehe with the Pre # headwaters.

The purpose of the invention is to create a network its dimensional stability, especially in the case of packaging nets of tubular shape, adjusted can be.

Tubular plastic packaging nets should preferably be small or have no longitudinal extensibility, i.e. they should in terms of their dimensions be stable in the longitudinal direction. This requirement is based in part on the fact that the The net has to bear the load of the packed goods if it is vertical, i.e. in the longitudinal direction, is suspended, and partly on the fact that a longitudinal stretching a reduction the diameter of the hose formed by the network, i.e. the transverse dimension; because of the sacks and bags formed from nets with a reduction in the size of the The associated reduction in the clear cross-section is the filling difficult. It is true that the tubular packaging network is intended to facilitate and facilitate of packaging in the transverse direction to a small extent, but this may Resilience, i.e. the transverse extensibility of the network, must not be excessive, otherwise the final pack loses its fort and becomes short and thick. this has an unsightly appearance, aggravation of the fluff, as well as excessive Result in the need for floor space.

With a mesh, i.e. also with a network, the degree becomes the dimensional stability in the longitudinal and transverse direction from the angle between the Netziaschenstrangen and the St @ a @ gpre #direction, i.e. the longitudinal axis of the network. The smaller this angle, the greater the dimensional stability in the longitudinal direction and the less that in the transverse direction; and on the other hand is dimensional stability in the longitudinal direction the smaller and in the transverse direction the larger, the larger this angle is (up to 900). As a result, a jet has one. Mesh strand angle of 450 and symmetrical meshes so the same length and transverse stretchability.

Metse or meshes with low transverse extensibility, as required above is, so indicate high, £ .h. undesirable, longitudinal stretchability; and wise vice versa Nets (or their meshes) high, i.e. undesirable, transverse elasticity, low Longitudinal durability, which is required above, the two mesh forms @@ sitsen thus opposing properties.

Further dead to point out that not the full ferm of everyone Mesh opening is decisive, but the winding of the mesh strands. That's why would be a kite-shaped @@@@ he, the two of which, viewed in the direction of expression, are in front Mas @ hen strands have a small angle, e.g. much less than 45 °, and their on these strands of meshes adjoining meshes an angle corresponding to is greater than 45 °, have lower transverse extensibility than meshes lit equal have large angles, i.e. regular diamond-shaped meshes, which is why it is the The angle of the strands to be considered as described below to should be selected in order to obtain the desired low transverse ductility.

In other words, in nets with constant mesh spacing, i. E. in nets in which every mesh, measured around the circumference of the net tube, is the same is wide, the lower the transverse stretchability, the shorter the transverse strands of meshes are.

The object of the invention is to provide such Mesh shape or such a network structure, i.e. a classification of the meshes in the network to create that the intrinsically unregulated transverse and longitudinal stretchability of the Network is regulated in the sense of a dimensional stability of the network. Under the scheme the extensibility in the two main directions is essentially the reduction understood the unhindered extensibility to fractions of the same, but also the Reduction of extensibility to zero. The task also consists of development of a method for producing the nets according to the invention.

The stated goal is achieved by means of a method of that mentioned at the beginning Type reached, in which it is provided according to the invention that the speed of movement the extrusion head mouths are periodically changed, thereby changing the angle of the mesh strands is changed periodically (cyclically) in such a way that, viewed in the pressing direction, alternating mesh ribbons with different Mesh angles arise.

In a further development of this method it can be provided that the extrusion head mouths moved back and forth with a periodically changing speed with each stroke of movement will. Alternatively, in the method according to the invention, the extrusion head mouths, if they are led in a circle, with a periodically changing speed rotated in opposite directions.

The desired goal, namely the creation of something that does justice to the purpose Kunstatoffnetzes, is alternatively also by means of two more, also from the Method of the type mentioned at the beginning of the invention accessible. The first of these two methods, in which the network by means of a pair driven rollers acting in the same direction is withdrawn, according to the invention in that the drive speed of the rollers is periodically changed in such a way that that the mesh angle is changed periodically accordingly to alternately to produce different ligaments with different angles. On the other hand, there is a @ second alternative method, in which in a known manner dte extruded head mouths are guided in circles and also the resulting hose-like network is guided over a drawing mandrel, according to the invention, that the drawing mandrel is periodically moved axially in the extrusion direction is that the thread angle accordingly changed periodically will.

The three manufacturing processes proposed according to the invention lie therefore the same task is based; they are essentially from the same prior art and differ only in the diversity of their solutions, the but insist on the same principle, namely the control of the mesh strand angle.

That in particular according to one of the three proposed according to the invention Manufacturing process, but possibly. also otherwise producible, plastic net differs from conventional nets in that it is transverse to the longitudinal direction of the network ribbons of meshes of a first shape with ribbons of meshes of another Alternate shape, the mesh angle of which is different from the angle of the mesh Shape is different. These guides show areas of different extensibility in general Longitudinal and transverse direction, whereby the Ge. elasticity of the network in these both directions in the sense of retracting the extensibility to a desired value the same is reduced.

It is expressly pointed out to the * Or place that the inventive Nets can be produced according to the method described above, but that event. other manufacturing processes can also come into question. On the other hand, are suitable The o. X. process exclusively for the production of the nets according to the invention.

In continuing this network. can as a result of additional procedural measures the nets be tubular and the alternating bands different mesh shapes extend transversely around the hose.

There is also the possibility that the plastic in the net strands stretched and molecularly aligned. Due to de. Run the net strands it can be provided that these are round in a screw-like manner in opposite directions to run around the Metsschlauch or that this along os @ illierenden paths, which generally extend in the axial direction of the Metsschlauche, run.

A particularly advantageous embodiment of the invention Plastic netting consists in that in the longitudinal direction of the pilot. Areas diminished Transverse stretchability showing rows of meshes with a. Mesh strand angle of are arranged substantially larger than 350, the number of these areas correspondingly the network length is chosen so that the longitudinal extensibility of the network to a desired The percentage is limited, and that the courses lying between these areas Connecting strands with Winkali, which are lower than those in the former Areas, however, are never greater than 450.

The invention is explained in more detail with reference to the drawing.

1 shows a diagram of a mesh of a network more constant Mesh width to explain the mesh strand angle and the Masohen strands; Fig. 1a is a diagram to illustrate the relationship between Strand angle and strand length; 2 shows a mesh with high longitudinal extensibility and low transverse ductility; 3 shows a mesh with low longitudinal extensibility and high transverse extensibility; Fig. 4 shows a net mesh structure with spaced apart, transverse Areas of meshes of low transverse extensibility; Fig. 4a and Fig. 4b ex. a Course of an individual, by means of reciprocating or revolving Preßkopfoündungen pressed strand; FIGS. 5, 5a and 5b in a representation analogous to FIGS. 4, 4a and FIG. 4b shows a second example of a net mesh structure with spaced apart transverse running areas of meshes of low transverse extensibility and without elongated Mesh crossing points and ex. a strand course; 6, 6a and 6b show a modified one Form of the mesh formation according to the invention, in the case of the transverse, intermediate Ribbons of mesh strands are provided as areas of low transverse extensibility and ex. a strand course; FIGS. 7, 7a and 7b are modified from FIG. 6 Form of mesh training and ex. an associated strand course; Fig. 8a a only pressed net with one according to the invention through changeable opposite speed of the pre # head orifices achieved mesh formation; Pig. 8b shows the ilets of FIG. 8a after it has been stretched for the purpose of molecular alignment the plastic in the net strands and FIG. 9 in an enlarged scale a diagram a single press head part rotating from a variable speed extruded strand, which the different strength of the different strand technite reveals.

The one in Pig. 1 Netsmasche shown consists of mesh strands 1 and crossing points 2. The mesh strands 1 form with the longitudinal axis 3 of the network a strand angle M; the longitudinal axis 3 of the network is also the pressing direction of the network.

The mesh according to Fig. 1 is part of a network .. constant mesh width P, so that the distances between the intersection points 2 along a tubular network its circumference or, in the case of a flat network, across its width is the same in each case are.

One can see that j o is greater than the mesh strand angle h (until su becomes 900, the skier becomes the strand ÄB. Therefore, for a strand AB1 (see Fig. 1a), the shorter than the strand AB the angle M1 is greater than that Angle h and for a strand AB2 that is longer than strand AB, the angle smaller than the angle M.

Note that the angle X in Fig. La is 450, then if AB1 is shorter than 11B and consequently the angle Y1 is greater than the angle M, A net mesh with Net @@ strings like AB1 increases dimensional stability in the transverse direction and a reduced dimensional strength in the longitudinal direction, i.e. a reduced transverse extensibility and an increased longitudinal extensibility. Conversely, a mesh whose Strands AB2 are longer than AB and their angle M2 is smaller than angle Y, have reduced dimensional strength in the transverse direction, which means that the mesh has increased transverse extensibility and reduced longitudinal extensibility.

These two cases are shown separately in FIGS. In Fig. 2 is'der Masohen strand AB1 shorter than bB and the mesh strand angle 11 larger as the angle 1; this has the consequence that the transverse extensibility ET is small while the elongation EL is great. In the mesh shown in Fig. 3 is the Strand AB2 longer than AB and the angle M2 smaller than the angle N, so that the The transverse extensibility ET is large, while the longitudinal extensibility EG is small.

Therefore, it should be noted that a made only from meshes according to Fig.2 Mesh high elasticity, i.e. poor Dimensional strength in the longitudinal direction, and has low transverse extensibility, i.e. good dimensional stability in the transverse direction. In in the same way, one consisting only of stitches of the shape shown in FIG. 3 becomes Nets low elongation, i.e. good dimensional stability in the length direction, and high Transverse extensibility, & .h. low dimensional strength in crosswise direction.

Since, as explained above, little for tubular packs no longitudinal extensibility and, at the same time, reduced transverse extensibility are desirable is, according to the invention, a mesh structure is provided in which rows of mesh strands or meshes of low transverse elongation with rows of meshes or strands Alternate meshes with low elongation.

In Pig. 4, a network is shown schematically in which row 4 of meshes according to # Fig. 2 with an angle M1 and low transverse extensibility with rows 5 of stitches according to FIG. 3 iit a. Angle Y2 and low elongation alternate.

The alternating mesh bands can also be selected from a variety consist of rows of stitches, e.g. in Fig.

4 each band of the mesh type according to FIG. 2 from more than one Masohen row 4 and each band of the mesh type according to FIG. 3 consist of more than one course 5; See, for example, Fig. 8b discussed below.

The network shown in Fig. 4 can, for. B. by means of circular, Consentriocher crimping head sets are pressed as described in the British patent 836 555 are described, according to which one or both press head parts over a stroke length T oscillate. The course of a single strand is shown in FIG. 4a. It has been shown, however, that it is not always necessary to use both press head parts to move, and that if only one part oscillates over the stroke length T and the other Part is fixed, which squeezed out of the press head mouths of the fixed part Strands do not run straight and parallel and to the longitudinal axis, but through the strands squeezed out of the oscillating part into approximately the same shape be drawn like the strands of the oscillating part, making it out of practical All that is necessary is to have a press head part os @ illiert.

Both press head parts are preferably operated at varying speeds rotated in opposite directions, so that each part is a strand of that shown in Fig. 4b Form presses, with the strands then helically around the pressed tubular mesh run (in particular it is advantageous if a part of the strands, as shown in Fig. 4b, and the other part are strands that are a mirror image of those in Fig.

4b are formed, expresses.).

With both types of extrusion, i.e. by means of reciprocating or rotating movement of the extrusion head parts, becomes the speed one or both of the extrusion head parts periodically changed to accommodate the different Mechenßtrangaintel M1 and M2 to get. According to a modification of the invention Method for creating a network can be used at constant speed two Preßkoptteile rotated in opposite directions and the change in the angles M1 and N through Changing the withdrawal speed of the network from the press head parts or else by alternating back and forth movement of the mandrel on which the Netzachlauch is following recorded in the press, although this is not a particularly satisfactory one Procedure represents. In Fig. 4 are in the above described manner at a distance from each other Cross bands or mesh areas 4 are provided, which have limited transverse extensibility ensure the network and interspersed with transverse bands or mesh areas 5 are that bring a limited longitudinal stretchability of the network with it. So owns a net for a packaging bag in a tubular, closed at one end Form during manufacture and filling, as well as in the filled state and during Uses a limited elongation and at the same time because of the at intervals existing cross bands or mesh areas 4, which allow the expansion and the short and prevent thickening of the bag, a limited transverse extensibility, whereby the transverse bands or mesh areas 4 arranged at a distance from one another are similar behave like the straps of a barrel.

Fig. 5 shows a network similar to that in Fig. 4. However, these are adjacent Crossing points 2 'opposite the crossing points 2 of FIG. 4, the elongated are, point intersection atelles. The properties of the network of FIG. 5 are same as those of the network of Fig. 4; furthermore, this network can either by moving one or both press head parts back and forth, creating a strand like is formed in Fig. 5a, or preferably by rotating the parts in opposite directions, thereby forming a strand as in Figure 5b.

6 shows a further modified network design according to the invention shown. While in Fig. 4 and 5 transverse rows of stitches 4 and 4 'are shown, which are symmetrical to their transverse axis and whose four mesh strands are of equal length, are courses 6 with a large mesh angle M1 and a mesh angle 12 provided with courses 5 similar to the stitches 5 according to FIGS alternate. In this case, the stitches 1 form the stitches 6 at a distance mutually arranged transverse lines of reduced transverse extensibility.

The network can be similar to that described with respect to FIGS. 4 and 5, by means of reciprocating press head parts to the strand course shown in Fig. 6a to obtain, or preferably by rotating the parts in opposite directions to obtain a To achieve strand course according to Fig. 6b, are pressed.

FIG. 7 shows a network configuration that has been changed compared to FIG. 6, whose It is a peculiarity that meshes 6 with strands 1 and a Winkol M1 in successive Rows without intermediate rows ton diamond meshes 5 according to FIG. 6 are provided are, wherein the strands 1 are the spaced transverse lines of reduced transverse extensibility represent.

The mesh strand angle for meshes with low transverse extensibility is preferably above 45 °, i.e. about 600; however, in some cases a Angles of 350 already ensure a sufficient value for the transverse extensibility of the network. In all cases, however, the strand angle of meshes is of low elongation smaller than the angle for meshes with low transverse extensibility and always larger than 45 °.

The nets described above are designed only by pressing. Advantageous it is, however, the plastic of the net strands through a molecular orientation Subjugate routes in known manner, with an oriented network of the same Shape like the nets described above with correspondingly enlarged dimensions the net strands arises. Therefore, FIGS. 4 to 7 schematically represent either (a) an only compressed net, i.e. before stretching, on an enlarged scale or (b) the mesh after stretching and with enlarged dimensions. In the aligned Net, the net strands are stretched and the plastic is completely or partially molecularly aligned, while the Betzkreuaungen (bonds) both stretched as well as unstressed could be.

Because the strands in the two types of mesh ribbons are different Having pocket strand angles will be the degree of stretch and the degree of orientation to be different.

Furthermore, the degree of orientation in each type of mesh tape is affects the dimension of the mesh strands in each band as it relates to below Figures 8a, 8b and 9 will be described. The aligned network can also be expanded by expanding be treated in the transverse direction and heat setting of the expanded mesh. By this treatment can make the difference between the mesh strand angles of the meshes ranks are tightened.

As a result of the influence of the angle of the mesh and the rope thickness the peculiarities of the meshes when stretching and aligning in each band change or reverse it as set out below.

With under cyclic back and forth movement (oscillation) of the press head parts or changing the peeling speed, the nets produced retain the original ones Groups of the mesh bands or the mesh strand angles in most cases their Mesh shapes or peculiarities, albeit with enlarged dimensions of the net strands (and thus with larger jilaschen).

In other words: each band with pockets according to FIG to the Even after stretching and molecular alignment, pressing still has meshes according to FIG. 2 and reduced transverse extensibility. Likewise, each owns after extrusion belt equipped with meshes according to FIG. 3 after stretching and molecular alignment still meshes according to FIG. 3 and reduced longitudinal extensibility.

In a network according to the invention, which by cyclically changing the Rotational speed of the constantly opposing press head parts is produced, return however, the extensibility properties of the meshes in each Xaschen ribbon normally change while stretching to molecular alignment. So there are stitches according to Fig. 2 after pressing out into stitches according to FIG. 3 after stretching, while stitches according to FIG. 3 after pressing into stitches according to FIG. 2 after stretching. In this way, stitches that originally had low transverse extensibility after being pressed out, d. H. according to Fig. 2, have relatively high transverse extensibility (i.e. according to Fig. 3) and low elongation converted. Furthermore, meshes show the originally low elongation after pressing with corresponding Transverse extensibility, i.e. according to Fig. 3, have, after stretching, a transverse extensibility, compared to the newly formed meshes in the other bands relatively low is, d. H. they become actual and compared with the meshes in the others Areas for the mesh type according to Fig.

2. Since here nevertheless alternating areas with essentially different Transverse extensibility are present, the inventive. Network training maintain.

In Fig. 8a, a network is shown after squeezing, the one Group of tapes A with a mesh angle of 600, i.e. with one type of mesh according to Fig. 2, and another group of tapes B with a mesh angle from 450, d. H. with a mesh type according to FIG. 3, has. In such a network which is shown without the exact values for the angles, the meshes in Band A has transverse extensibility prior to molecular alignment by stretching, which is low compared to that of the meshes in band B, so that the meshes in volume A contribute to the dimensional stability in the transverse direction of the net, while the meshes in volume B give the net a certain dimensional stability in the longitudinal direction. This is Difficult to recognize, of course, when the net has only been squeezed out.

After the mesh is used for molecular alignment of the plastic in the mesh strands is subjected to stretching (see Fig. 8b), have the Meshes in volume A have a mesh strand angle of 250 and relatively high transverse extensibility, while the meshes in band B are at an angle of the original order of magnitude, e.g. 40 °, and one lower than the newly designed meshes in Volume A Have transverse extensibility.

Hence: Relative Querd @ hnbar- before t.r after the ability of the mesh ribbons stretch stretching Band A A Band B high Band B Band A The reason for this is that # in the case of press head parts rotating in opposite directions, their rotational speed The plastic is cyclically changed in the strands of the larger meshes Mesh strand angle (tape A or according to Fig. 2) stretches sooner and faster than that in the strands of the other stitches (band B eder according to # Fig. 3), so that in the time in which the stretching was originally carried out at a larger mesh strand angle {Mae'ohen of the band A) is completed, the stretching (and thus the mesh angle redesign) the stitches in the other bands (stitches in band B) only slightly advanced, i.e. is still relatively unfinished.

This, in turn, is attributable to the fact that at constant extrusion pressure the stitches of the stitches with a larger thread angle (stitches of the tape A) are necessarily weaker, i.e. contain less plastic, than the mesh strands in the other bands (stitches of band B) and therefore under the tensile stress give in more easily. This is shown schematically in FIG. 9, which shows a single Strand shows the thickness of which changes from that of tape A to that of tape B.

The invention relates to knotless extrusions Plastic nets for which the extrusion head parts come in two concentric sets are arranged. It does not matter whether each extrusion head part is separate, i. separate press head orifices on the side of a common contact or sliding surface has open slots. In the first case, each press head part presses parallel mesh strands and cross the strands of the two sets with each other, touch and adhere to one another, so that the network crossing points are outside of the press head parts. In the second case, the crossing points appear as finished Whole from the press head.

Claims (13)

Claims (P 14 86 566.8-27) 1. Method of extrusion knotless plastic nets in which two sets of spaced apart Strangpre # head openings for the purpose of connecting the net mesh strands of one set moved relative to each other by strand crossings with the strands of the other set are characterized in that the speed of the extrusion head mouths is changed periodically, whereby the angle of the mesh strands so accordingly is changed cyclically that, seen in the pressing direction, mesh belts alternately with different mesh angles. 2. The method according to claim 1, characterized in that the Strangpre # head openings with a periodically changed speed with each movement stroke back and forth be moved. 3. The method of claim 1, wherein the extrusion head mouths are guided in circles, characterized in that the extrusion head mouths rotated in opposite directions at a periodically changed speed. 4. Process for extrusion of knotless plastic nets, at. the two sets of spaced apart extrusions to join the net mesh strands of one set with the strands of the other Sentence are moved relative to each other by line crossings and in which the Net pulled off by means of a pair of driven rollers acting in the same direction is characterized in that the drive speed of the rollers is periodic is changed in such a way that the Masohen strand angle is changed periodically accordingly is to alternately produce different ribbons with different mesh strand angles to manufacture. 5. A method for extrusion of knotless plastic nets in which two sets of spaced extrusion head mouths for the purpose of Connection of the net mesh strands of one set with the strands of the other Sentence are moved relative to one another by line crossing, in which further the Extrusion head mouths are guided in circles and ultimately the resulting tubular network is guided over a mandrel, characterized in that the mandrel is periodically moved back and forth axially in the extrusion direction, that the mesh angle is changed periodically accordingly to alternately to produce different tapes with different mesh strand angles. 6. Extruded knotless plastic mesh manufactured in particular according to a method of the preceding claims, characterized in that transversely to the longitudinal direction of the network ribbons of meshes of a first shape with ribbons of Alternate meshes of a different shape, the mesh strand angle of which differs from the angle the mesh of the first porm is different. 2 Runststoffnetz according to claim 6, characterized in that the Network is tubular and the alternating bands are different Mesh formers across the hose / stretch. 8. plastic net according to claim 6 or 7, characterized in that that the plastic in the net strands is stretched and molecularly aligned. 9. Plastic net according to claim 7 or 8, characterized in that that the net strands are helically round in oppositely running bands run around the net hose. 10. Plastic net according to claim 7 or 8, characterized. that the net strands run along oscillating paths that are generally in Extend the axial direction of the mesh tube. 11. Plastic net according to at least one of claims 6 to 10, characterized marked that each mesh band at least two together lying, rows of stitches. 12. Plastic net according to at least one of claims 6 to 11, characterized characterized in that areas of reduced transverse extensibility in the longitudinal direction of the network depicting rows of stitches with a pitch angle of substantially greater are arranged as 350, the number of these areas according to the network length so is chosen that the longitudinal extensibility of the network to a desired percentage is limited, and that the rows of stitches lying between these areas are connecting strands with angles that are essentially smaller than those in the first-mentioned areas, but are never greater than 450. 13. Plastic net according to claim 7, or claim 7 and one of the the following claims, characterized in that it is closed at one end Bag or similar container is formed.