Method for producing a net with elongated stitches

Abstract

A method, an elongating device, a Raschel knitting machine comprising the elongating device for producing nets with elongated stitches and a net comprising elongated stitches is described. The method comprises the steps of continuously generating new loops for elongating the two rows of loops by additional loops and dragging the rows of loops in a machine direction, generating a first stitch of the weft by joining the weft to a loop of the first row and to a loop of the second row, and positioning the first stitch across a surface of an elongating device for preventing the first stitch from traveling with the warps knitted to loops in the machine direction. The joining is configured for elongating the first stitch by pulling additional weft material, and the surface of the elongating device is carrying out a reciprocating movement towards the first stitch. Further, an elongating device for elongating of the stitches is described.

Claims

1. A method for producing a net with an elongated stitch made of a weft, the net formed by at least two warps knitted to at least two rows of loops and by at least one weft joining the at least two warps by at least one stitch, the method comprising: continuously generating new loops for elongating the at least two rows of loops by additional loops and dragging the at least two rows of loops in a machine direction; and generating a first stitch of the at least one weft by joining the at least one weft to a loop of the first row and to a loop of the second row by joinings, including positioning the first stitch across a surface of an elongating device for preventing the first stitch from travelling with the warps knitted to loops in the machine direction, wherein the joinings are configured for elongating the first stitch by pulling additional weft material and the surface of the elongating device carries out a reciprocating movement, wherein on the surface of the elongating device a projection is provided for preventing the first stitch from moving off the surface, and by dragging the net, the first stitch is moved towards the projection, wherein during the reciprocating movement, the inclination of the surface is modified, and at a specific inclination of the surface, the first stitch is released off the surface over the projection.

2. The method of claim 1, wherein: the elongating device is positioned between two needles used for knitting the at least two rows of loops and below a hole needle for guiding the at least one weft from one needle to the other needle; the elongating device is attached at one end to a guide bar for the reciprocating motion; and the elongation device has at another end an abutment portion that presses against an abutment element for a free reciprocating motion between an attaching position where the abutment portion abuts the abutment element and a pressing position where the abutment portion is pressed against the abutment element.

3. The method of claim 1, further comprising: generating a predetermined number of further stitches of the at least one weft by joining the at least one weft to a loop of the first row and to a loop of the second row; positioning the predetermined number of further stitches across the surface of the elongating device together with the first stitch; and moving the predetermined number of further stitches towards the projection by dragging the net in the machine direction, wherein the projection is flexible and when the predetermined number of further stitches act on the projection, the first stitch is released.

4. The method of claim 1, further comprising: positioning the first stitch on a further surface of the elongating device after having left the surface, wherein the further surface is angled with respect to the first surface for keeping the stitch under tension.

5. The method of claim 1, wherein the reciprocating motion corresponds to a path in an arched manner.

6. The method of claim 1, wherein the elongating device comprises: an oblong, flexible object with a surface and with an abutment portion; an attachment means for attaching a driving means; and a flexible projection on the surface of the oblong, flexible object.

7. A method for producing a net with an elongated stitch made of a weft, the net formed by at least two warps knitted to at least two rows of loops and by at least one weft joining the at least two warps by at least one stitch, the method comprising: continuously generating new loops for elongating the at least two rows of loops by additional loops and dragging the at least two rows of loops in a machine direction; generating a first stitch of the at least one weft by joining the at least one weft to a loop of the first row and to a loop of the second row by joinings, including positioning the first stitch across a first surface of an elongating device for preventing the first stitch from travelling with the warps knitted to loops in the machine direction; and positioning the first stitch on a second surface of the elongating device after having left the first surface, wherein the second surface is angled with respect to the first surface for keeping the stitch under tension, wherein the joinings are configured for elongating the first stitch by pulling additional weft material and the first surface of the elongating device carries out a reciprocating movement.

Description

(1) Hereinafter, the invention is described in more detail by means of the drawings wherein

(2) FIG. 1 is a schematic drawing of a net according to the state of the art;

(3) FIG. 2 is a schematic drawing of an embodiment of an elongating device according to the invention in a side view;

(4) FIG. 3 is a schematic drawing of the embodiment of the elongating device of FIG. 2 in a front view from the left side in FIG. 2;

(5) FIG. 4 shows another embodiment of the elongating device in a perspective view;

(6) FIGS. 5a and 5b are schematic drawings of the embodiment of the elongating device of FIG. 2 in two positions during movement on a bow-like path of the reciprocating motion;

(7) FIG. 6 is a schematic drawing illustrating the production of a net as in a front view with an elongating device according to FIG. 2;

(8) FIG. 7 is a schematic drawing of an embodiment of the Raschel knitting machine in a side view illustrating the position of the surface for positioning a stitch for elongating the stitch;

(9) FIG. 8 is an illustration of an embodiment of the a net according to the present invention, stretched along a direction parallel to the warps in comparison to a net according to the state of the art; and

(10) FIG. 9 is an illustration of an embodiment of the a net according to the present invention, stretched along a direction perpendicular to the warps in comparison to a net according to the state of the art.

(11) FIGS. 2 and 3 are schematic drawings of the same embodiment of the elongating device that may be used for elongating the stitch 4 during production of a net comprising elongated stitches. FIG. 2 is a side view and FIG. 3 is a front view from the left side of FIG. 2.

(12) The elongating device of this embodiment comprises a bent and oblong object that is flexible due to its bent form and the material used. The material is a steel. The bent, oblong object is formed by of a first portion 10, a second portion 12 and a third portion 14 between the first portion 10 and the second portion 12 integrally formed by a material stripe. At the junctions of the third portion 14 to the first portion 10 and to the second portion 12 the object is angled, wherein the second portion 12 is bent towards the first portion 10.

(13) The second portion 12 is configured at a loose end that is not connected to the third portion 14 to abut against an abutment element (not shown) by the abutment portion 16. The junction between the second portion 12 and abutment portion 16 may be configured to bend when a force is exercised for example in the first portion 10 towards the third portion 14 such that the abutment portion 16 stays flatly abutted against the abutment element, thereby pressing against the abutment element.

(14) At or close to the junction of the first portion 10 and the third portion 14 a projection 18 is provided on the upper surface of the first portion 10, which is the surface that is directed away from the second portion 12.

(15) For a better understanding a single stitch 4 is shown in FIGS. 2 and 3 which is not part of the elongating device. The upper surface of the first portion 10 is the surface for positioning a stitch 4. The stitch 4 is crossing the upper surface. As shown, the projection 18 is formed on the same surface as the surface on which the stitch 4 is positioned and forms a barrier for the stitch 4 if the stitch 4 is moved along the upper surface towards the third portion 14. As shown in FIG. 3, the stitch 4 is hidden behind the projection 18 in the front view. Further, the projection 18 has a width that is smaller than the width of the upper surface 10 and is centrally positioned on the upper surface with respect to the width of the upper surface.

(16) The form of the first portion is not specifically limited to the embodiment as described referring to FIG. 2. The form of the first portion may be adapted to the specific Raschel knitting machine to which the elongating device is attached.

(17) In another embodiment the third portion 14 is not present at all and the second portion is directly connected to the first portion 10. Further, the angles may be rounded.

(18) In FIG. 4 another embodiment of the elongating device is shown in a perspective view. The elongating device comprises a first portion 10, which is provided with a surface for positioning a stitch and a projection 18, a second portion 12, which is provided with an abutment portion 16 for pressing against an abutment element (not shown) and a third portion 14. Between the second portion 12 and the third portion 14 a fourth portion 19 is provided. The junctions of the fourth portions are angled in the same direction as the other junctions.

(19) Further, the projection 18 of this embodiment is integrally formed as a stud that has been blanked out off the first portion 10. The stud forms a projection 18 being a barrier for a stitch positioned on the surface of the first portion 10, thereby preventing the transfer of the stitch towards the second portion 14. The projection 18 is flexible. The projection 18 may be pressed down depending on the force acting on the projection 18. In other words, the projection 18 is a lip or a piece of material that is connected to the first portion 10 by a line junction. Thus, when an adequate force is acting on the surface of the lip, the lip may be pressed down.

(20) Further, as shown in FIG. 4, the embodiment of the elongating device comprises an attachment means 20 for attaching the elongating device to a movement means (not shown). In the embodiment shown in FIG. 4 this attachment means 20 is a hole configured for example for fitting a screw through it.

(21) FIGS. 5a and 5b are schematic drawings of the embodiment of the elongating device of FIG. 2 in two positions during movement on a bow-like path during production of a net. FIGS. 5a and 5b are a side view along for example the long axis of a Raschel knitting machine in which the hole needles 22 are arranged. FIG. 6 is a front view corresponding to FIG. 5b. Thus, FIGS. 5a, 5b and 6 illustrate a method for producing the net with elongated stitches according to one embodiment of the invention. The principle of elongating the stitch 4 is illustrated referring to the elongating device that is shown in FIG. 2. However, other embodiments of the elongating device may be used accordingly in the same method.

(22) In FIGS. 5a, 5b, and 6, a row of loops made of warps 2, wefts 3, and joining points 5 are shown. Further, stitches 4 are shown that are positioned on the surface of the elongating device and other stitches 4 that are not on the surface of the elongating device. The stitches 4 that are positioned around the second portion 12 are loosely positioned around the second portion 12. This is illustrated in FIG. 6 by the three irregular lower stitches 4. The stitches 4 that are positioned on the first portion 10 and the third portion 14 are kept under tension. Accordingly, in FIG. 6 these upper two stitches 4 are illustrated by straight lines following the surface of the object of the elongating device.

(23) Further, hole needles 22 for guiding the weft, hole needles 24 for guiding the warps and needles 26 for creating the loops of the warps 2 are shown. During production of the net, the needles 26 carry out an up and down reciprocating motion, the hole needles 24 make a rotating movement around the needles 26 and the hole needles 22 make a reciprocating translational motion from one needle 26 to another needle 26.

(24) In FIGS. 5a and 5b the net is extending vertical to the paper plane in the machine direction 7 and in FIG. 6 the net is positioned parallel the paper plane.

(25) The wefts 3 and the warps 2 are connected to material sources (not shown). During production of the net, the net is moved in the machine direction 7 and additional material may be pulled from the material sources. A stitch 4 that is positioned on the first portion 10 or the third portion 14 and that is joined to the loops of two warps 2 is pulled towards the joining points when the net moves in the machine direction 7. Since the stitch 4 is positioned on the surface of the object the stitch 4 may not follow this force and additional material is pulled and the stitch 4 is elongated.

(26) The first portion 10 reaches from one side of the hole needle plane of the hole needles 22 for the wefts to the other side. Thus, a weft 3 that is dragged from one needle 22 to another needle 22 and after forming a stitch 4 when moved in the machine direction 7 the stitch 4 is positioned on the upper surface of the first portion 10.

(27) The first portion 10 of the object of the elongating device is attached to a driving means 21. The driving means comprises a guide bar that is coupled to an element that is configured to swing around an axis parallel to the long axis of the Raschel knitting machine for transmitting a reciprocating motion.

(28) At an end of the object that is not attached to the driving means 21 the second portion 12 presses against an abutment element (not shown). As shown in FIG. 5a, the driving means 21 is in a first position and accordingly the elongating device is in a corresponding first position. If the driving means 21 starts the motion, the elongating device follows the movement with the first portion 10 and the third portion 14. The first portion 12 is abutting against an abutment element (not shown) and, therefore, bends. This is shown in FIG. 5b. Thus, when the driving means turns from the position as shown in FIG. 5a to the position as shown in FIG. 5b the object is bent in the moving direction on a bow-like path. This is illustrated in FIGS. 5a and 5b by the double arrow.

(29) The moving on the bow-like path is carried out at as a reciprocating motion at a frequency of at least 1000 cycles/minute. In other embodiments the moving may be carried out at any machine operating frequency.

(30) During the production of the net and further proceeding of the net in the machine direction 7 and the reciprocating motion a stitch 4 that is positioned on the surface of the first portion 10 moves towards the projection 18 and its way is blocked by the projection 18. The stitch 4 that is now acting on the projection 18 continuous to be elongated as long as the stitch 4 is acting on the projection 18. With increasing length of the stitch the force with witch the stitch 4 is acting on the projection increases. The projection is flexible and when the stitch 4 acts on the projection 18 with an adequate force, the stitch 4 is released.

(31) It is noted that in an alternative embodiment of the method it is not the stitch 4 itself which alone causes the projection to release the stitch, but only when a predetermined number of stitches 4 act on the projection, the projection releases the stitch that was acting first on the projection.

(32) An embodiment of the Raschel knitting machine is shown in FIG. 7 in a side view. The embodiment comprises needles 26 (only one is visible in FIG. 7) and needle bar 28 to which the needles 26 are attached, hole needles 24 (only one is visible in FIG. 7) for the warps and the first guide bar 30 (Comb one) to which the hole needles 24 for the warps are attached, hole needles 22 (only one is visible in FIG. 7) for the wefts and the second guide bar 32 (Comb two) to which the hole needles 22 for the wefts are attached, and a common guide bar 34, i.e. the stitch comb bar, to which the elongating devices are attached. Further, a surface 36 is shown. When the net is produced, it is over this surface that the rows of loops are dragged downwards.

(33) The elongating devices are only illustrated by a line 38, representing the plane in which the surface for positioning the stitch of the elongating device is positioned. Thus, the surface is positioned and attached to the stitch comb bar 34, and below the hole needles 22 for the wefts. Further, the surface extends from the one side of a working plane in which the hole needles 22 for the wefts are positioned to the other side of the working plane.

(34) In an embodiment, in which the elongating device is bent, the elongating device is bent downwards, thus the elongating device is attached to the stitch comb bar 34, reaches through the plane formed by the hole needles 22 for the wefts, is bent downward in a bow like form and abuts against the surface 36. The elongating device is not in a fixed contact to any other part of the Raschel knitting machine between the stitch comb bar 34 and the surface 36 for allowing a free movement according based on the reciprocating movement. The attaching to the stitch comb bar 34 and the abutting to the surface 36 are configured for a vibrational motion of the elongating device based in a reciprocating motion of the stitch comb bar 36.

(35) Further, it is noted that the needle 26 and the plane in which the surface is positioned may cross each other since the surface is positioned between the needles 26 as illustrated in FIG. 7.

(36) FIGS. 8 and 9 illustrate an embodiment of the net A according to the present invention in comparison to the conventional net B. The reference signs used for the net B carry the mark and correspond to the ones used in FIG. 1.

(37) The net A may be stretched in a direction parallel to the warps 2 as shown in FIG. 8 and perpendicular to the warps 2 as shown in FIG. 9.

(38) Net A and net B comprises a row of loops of the warps 2, 2 and the stitches 4, 4 made of the weft 3, 3. The row of loops are joined to the weft 3, 3 every 2 loops in a regular zig-zag pattern. Thus, the distance between two joinings 5, 5 of adjacent stitches 4, 4 towards the same adjacent warp 2, 2 is 4 loops.

(39) The length of the stitches 4 of the net A are longer than the stitches 4 of net B.

(40) A conventional net B, for example for the packaging of pallets, has the following characteristics: production width 48 cm, length d of 4 loops equal 57 mm, with elasticity from 15% up to 40%. The stitches 4 of net B are linearly extending. Thus, when the net B is stretched parallel to the rows of loops, the net B narrows very much during stretching.

(41) The stitches 4 of net A are elongated, i.e. at the same distance d the stitches 4 are not linearly extending. Net A has stitches 4 with a length larger than 40-95% of the original stitch 4 of net B (elongating factor 140% to 195%). Consequently, even if the pallet net is stretched more than 100% of the original length, the stitches 4 are still loose and vertical forces are not or at least less applied over the net. Thus no or at least much smaller narrowing is experienced, when the net A is stretched to a length D that is larger than d. This is shown in FIG. 8.

(42) Another important aspect is shown in FIG. 9 in that the net A when the stitches 4 are stretched has a much larger width than net B when the stitches 4 are stretched. Thus, for production of a net having a width of 1230 mm and length of 4 loops equal 57 mm net A may have 52 warps 2 (rows of loops) and net B may have only 48 warps 2 (rows of loops). This is shown in FIG. 9. The distance Z in FIG. 9 is larger than the distance z in FIG. 9.