MXPA00003368A - Elongated strip of male touch and close fastener, shaping cylinder and method to produce such a strip - Google Patents

Abstract

Plastic tape (3) goes between pressing cylinder (4) and forming cylinder (5). Pressing cylinder presses tape against forming cylinder so that plastic material penetrates hook-shaped cavities, forming hooks on tape. Hooks on two consecutive sides are oriented in opposite directions. Hooks are oriented with angle alpha of 90 degrees with direction of tape. Independent claims are also included for (1) the description of forming cylinder (5), and for (2) the manufacturing process male gripping section.

Description

TIRA OBLONGA THAT FORMS A MALE SELOSUJETABLE PART, FORMING CYLINDER FOR ITS DEVELOPMENT AND METHOD TO DEVELOP A STRIP OF THIS CLASS DESCRIPTION OF THE INVENTION This invention relates to self-securing systems, and more particularly to a male self-gripping part of such a system, of thermoplastic material or of synthetic plastic, consisting of a strip of thermoplastic material or synthetic plastic of oblong shape, on which it is formed, for example by pressing the synthetic material into cavities, coupling means for example in the form of hooks, hemispherical harpoons or the like. This invention also relates to a forming cylinder for the production of the male self-gripping part of this class, and to a method for producing a male self-gripping part of this kind. According to the prior art, the male self-gripping parts are manufactured in the following manner. A strip of thermoplastic synthetic material, a forming cylinder and a pressing cylinder are extruded between two cylinders. Annular discs are placed around the forming cylinder, and placed adjacent to each other. At the distal end of these annular discs, hook-shaped cavities are formed in each alternate disc. During the passage of the strip of thermoplastic material, the latter is pressed into the cavities by the pressing cylinder and in this way the hooks are formed on the strip of plastic material. The hook-shaped cavities made at the outer peripheral (distal) ends of the annular discs are all oriented in the same direction on one disc and all in the opposite direction on the next disc comprising hook cavities, i.e. one second disc after an intermediate disc without cavities. The result is rows of hooks oriented alternately in the direction of rotation of the disk and in the direction opposite to the rotation of the disk and separated from each other by a distance corresponding to the thickness of an intermediate disk without cavities. The resulting product, that is to say an oblong strip of thermoplastic material in the length of which hook rows have been formed at a distance from each other with alternating hook orientations in each row, has the disadvantage that half of the hooks in the direction of transit of the machine (ie, in the direction of cylinder rotation) are of better quality than the other half with respect to its coupling capacity. The reason for this is that the hooks formed in the direction of transit require their required shape while the others tend to undergo formation after leaving the forming cavity, and lose their acquired shape and particularly flatten in the direction of the strip, which results in a mediocre coupling. It follows that these strips forming the male self-gripping part do not have the same coupling capacity in the pulling direction from which it can be imparted. US-A-5 884 374 discloses a male self-gripping part for which hooks are projected, some of the hooks are oriented in one direction and the other hooks in another direction. However, all the hooks are oriented in the direction of the length of the strip (a = 0o) so that when the hooks leave their production mold, some of them (those in the direction of transit) experience deformation more than others. (those in the other direction). DE-A-4 229 062 discloses a male self-gripping part from which hooks project, some of the hooks are oriented in one direction and other hooks are oriented in the opposite direction, specifically in the two transverse directions one direction. In addition, half of the hooks are oriented in a first direction and the other half of the hooks in another direction perpendicular to the first direction. In addition to the fact that this document makes no mention anywhere of the underlying problems solved by the present invention, is related to a particularly complicated hook configuration which is difficult to produce on a large scale, in mesh system shown, for example, in figure 8 is very complicated if not impossible to obtain in practice. The object of this invention is to eliminate these disadvantages by proposing a male self-gripping part of which the coupling quality of the female part of the self-holding system does not depend on the direction in which the pulling is carried out, and in particular, a part male which is coupled in the same manner for a pull exerted in one direction, for example, in the direction of the length of the oblong strip, as for a pull exerted in the opposite direction. According to the invention, the male self-gripping part consists of an oblong strip, that is to say, a strip having a longitudinal dimension greater than its width dimension, and hooks projecting from the strip and which are placed in parallel rows between each other. in the direction of the length and at a distance from each other, some of the hooks are oriented in one direction and the other hooks in the opposite direction to one direction, and characterized in that more than 50% of the hooks, and preferably of Substantially all the hooks are oriented in a single direction that forms an angle substantially different from zero with respect to the direction of the length of the strip.

Therefore, by arranging to form the inclined oriented hooks with respect to the length direction of the strip, the resulting coupling is less uneven between the case in which the pulling is carried out (the detachment of the female part with respect to the male part) of right-left (in a direction parallel to the length of the strip) or left-right (in the opposite direction). In fact, the difference between the resistance to loosening of the hooks formed with an orientation in the direction of transit of the strip on the cylinders and that of the hooks formed with an orientation in the other direction will decrease as the angle between the orientation of the rolls increases. the hooks and the length of the strip towards 90 °. In fact, this difference, which is maximum for an angle of 0o, will be reduced by a factor equal to the cosine of the angle since, as the angle increases, the component along the X axis corresponding to the The direction of transit will decrease to the advantage of the Y-axis component corresponding to the direction transverse to the direction of transit. Consequently, for a difference of, for example,? F of the deformations of the hooks for the angle?, This difference, for an angle of 45 °, will be only? F cos 45 ° = 0.7? F, that is, an improvement of 30%. According to a preferred embodiment of the invention, the hooks are oriented in the direction of the width of the strip (angle a = 90 °). In this case there is no additional difference between the decoupling strengths between the hooks that depend on whether they are oriented in one direction or another, since all the hooks retain their deformation as well as the others, and all the hooks are formed identically when the hooks leave the respective cavities. According to an improvement of the invention, substantially all the hooks of a row are oriented in the same direction, and the direction of orientation of the hooks is alternated every n rows, where n is a positive integer preferably equal to 1. This results in a particularly homogeneous coupling in each tension direction. According to an improvement, the hooks of a row are of an alternating direction every n hooks, n is a positive integer, preferably equal to 1. In addition, the production of the forming cylinder is simplified. In fact, for a throw width and a given number of rows, the prior art method needs a given number of annular disks. According to the invention, in order to form the strips, discs are no longer used, but rather laminations placed along generatrices of the cylinder, side by side, extending at an angle over the entire periphery of the cylinder and the number of laminations, of a thickness equal to that of the discs, is smaller than that of the annular discs, for a given strip width. Therefore, the present invention also relates to a new forming cylinder which comprises coupling means designed to couple laminations, and laminations placed parallel to the longitudinal axis of the cylinder, certain limitations have in their hook-shaped cavities on the outer edge oriented in the direction of the longitudinal axis, some of certain laminations have their cavities oriented in one direction and the others have their cavities oriented in the other direction. The invention also relates to a method for producing a male coupling part according to the present invention, which comprises passing thermoplastic or synthetic plastic material between a pressing cylinder and a forming cylinder, according to the present invention, into an angle substantially different from zero and which is controlled by the mutual inclination of the two cylinders. Finally, the present invention also relates to a laminated assembly comprising a support on which a self-supporting male part is fixed., for example, constituted by a shoe. A preferred embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation of a system used for the production of a male self-gripping part, in accordance with the invention. Figure 2 is a perspective view in a plurality "of laminations designed to be fixed on a forming cylinder, Figure 3 is an enlarged view of the part of Figure 2. Figure 4 shows a male self-gripping part, in accordance With the invention, Figure 5 is a perspective view of a forming cylinder according to the invention, Figure 6 is a longitudinal cross-section of the cylinder shown in Figure 5. Figure 7 is a side view of a rolling of the forming cylinder in Figure 5, and Figure 8 is an exploded view of the laminations of Figure 2. Figure 1 shows a system for producing a male part of a self-gripping element.An extruder 1 feeds a thermoplastic synthetic material in the form of from a strip 3 to an extrusion nozzle 2. The strip 3 is guided at the outlet of the nozzle 2 between a presser cylinder 4 and the forming cylinder 5.

The forming cylinder 5 consists of a transverse axis 6 on which the cylinder 7 is mounted coaxially and thus rotates therewith. An annular ring 8 forming a support comprising two annular grooves 9 and 10 is mounted on the cylinder 7. The annular grooves 9 and 10 serve to fix the laminations 11. The laminations 11 are substantially in the form of a trapezoidal parallelepiped; to say, the two sides transverse to the longitudinal direction of the parallelepiped are shaped like a trapezoid, in this case isosceles. The lower longitudinal side 12 of the lamination 11 in this manner has a thickness or width less than that of the upper longitudinal side 13 of the lamination 11. The lower part of the lamination 11 is formed with a recess 14 partially closed by two pins 15. and 16, whose shape is complementary to that of the notches 9 and 10 so that the lamination 11 can be fixed to that of the ring 8 by inserting the pins 15 and 16 in the notches 9 and 10 after the dovetail style. . The upper longitudinal side 13 of the lamination 11 is formed with cavities 17 in the form of hooks. These hooks consist of a base and a head 18. The cavities 17 are also formed so that all the hooks of the lamination are parallel to each other and all are oriented in the direction of the length of the lamination.

In this patent application, the term "orientation of a hook" indicates the direction in which the hook engages in a corresponding coupling hole. Therefore, in figure 7, the hooks are oriented in the direction of the drawing plane, in the right-left direction. A plurality of laminations Ia, 11b and 11c adjacent one another are fixed so as to form the entire periphery of the cylinder. The isosceles trapezoidal shape of the transverse sides allows the periphery of the cylinder to be easily obtained. In this example, the outer diameter of the cylinder 7 is 250 mm, the thickness (B2) of the lower side is 0.2 mm and 3927 laminations are placed side by side around the cylinder 7. Each alternating lamination has no hooks on its side 13 upper and these laminations 11b separate two laminations lia and 11c, each with a row of hooks on its upper side 13, all parallel to the direction of the width. However, the rows of the hooks are oriented in opposite directions (lia, right-left, 11c, left-right), this cycle of four laminations, ie a lamination with right-left hooks, a lamination in white, a lamination with left-right hooks and a blank lamination, repeat over the entire periphery of the cylinder. The strip 3 of plastic material passes between the pressing cylinder 4 and the forming cylinder 5 in the molten state. The pressing cylinder 4 presses the strip against the forming cylinder 5 so that the plastic material penetrates inside the hook-shaped cavities 17 so that the rows of the hooks are formed in the strip 3 on one of its sides, the hooks of two consecutive rows are oriented in opposite directions but in the same direction perpendicular to the longitudinal direction or the longitudinal direction of the strip. In this way the hooks are oriented at an angle a = 90 ° with respect to the length direction of the strip. If the angle a is required to be different from 90 ° but not zero, all that is needed, for example, is to adjust by a modification of the mutual inclination of the two cylinders. Therefore, in the case in which the two cylinders are parallel (figure 1) the angle obtained is 90 °. By tilting the forming cylinder at an angle β with respect to the pressing cylinder the resulting angle a is 90 ° - β, so that the required angle a can be adjusted effectively, knowing that an angle a of 90 ° will be preferred. Another procedure is to place each lamination not parallel to the cylinder 5, but by forming the angle ß = 90 ° - ce corresponding to the required angle a and bending each lamination so that its lower edge is in contact with the outer surface of the cylinder over its entire length. The greater the angle ß, the greater the curvature that will have to be provided to the lamination. In the extreme case, ß - 90 ° (ie a = 0 or), this is simply equivalent to the already known case of a ring as in the Velero process. However, the Velero process only provides for case a-0o, which is different from this invention. The laminations 11 can be manufactured by various processes, for example by laser cutting, erosion, etching, corrosion, deep extraction, water jet cutting and so on. For example, it can be manufactured from the following materials: unhardened steel, hardened steel, stainless steel, copper, steel coated with silver (CuNil8 Zn20 and synthetic materials.) The thermoplastic synthetic material for the strip can be a monopolymer, copolymer or tripolymer, for example polypropylene, polyamide, polyethylene, polyester, terephthalate, polybutyl, polyvinyl chloride and the like, and recyclable or biodegradable materials having a natural base, which can be mixed and integrated with all known polymers.

Claims (10)

1. A self-gripping male part of a self-gripping system, consisting of an oblong strip, that is, a strip having a longitudinal dimension greater than its width dimension, and hooks projecting from the strip and placed in parallel rows between them in the direction of the length and at a distance from each other, some hooks are oriented in one direction and the other hooks in the opposite direction to one direction, characterized in that more than 50% of the hooks, and preferably substantially all of the hooks hooks, are oriented in a single direction at an angle a substantially different from zero with respect to the direction of the length of the strip.

2. The male self-gripping part, as described in claim 1, characterized in that the hooks are oriented in the direction of the width of the strip, at an angle = 90 °.

3. The male self-gripping part, as described in claim 1 or 2, characterized in that substantially all the hooks of a row are oriented to the same direction and the direction of orientation of the hooks is alternated every n rows, n is a positive integer preferably equal to 1.

4. The male self-gripping part, as described in claim 1 or 2, characterized in that the hooks of a row are of an alternating direction every n hooks, n is a positive integer, preferably equal to 1.

5. A forming cylinder, characterized in that it comprises a coupling means designed to couple laminations, and laminations placed parallel to the longitudinal axis of the cylinder, side by side so as to complete the periphery of the cylinder, certain laminations have cavities in their outer edge. of hook oriented in the direction of the longitudinal axis, some of certain laminations have their cavities oriented in one direction and the others have their cavities oriented in the opposite direction to one direction.

6. The forming cylinder, as described in claim 5, characterized in that the laminations have the shape of a trapezoidal parallelepiped, a recess partially closed by two pins that are formed in the lower part of the lamination to allow its coupling in the cylinder by means of of two annular notches of an annular ring, which forms a support, after the dovetail style.

7. The forming cylinder, as described in claims 5 or 6, characterized in that each lamination is placed on the outer surface of the cylinder at an angle ß = 90 ° - with the axis of the cylinder, and the lower edge of each lamination is curved so that the bottom edge is in contact with the outer surface of the cylinder along the entire length of the edge.

8. A method for producing male coupling parts, as described in any of claims 1 to 4, which comprises passing a plastic or synthetic thermoplastic material between a presser roll and a forming roll, as described in claim 5 or 6.

9. A stratified assembly comprising a support on which the male self-gripping part is fixed, as described in claims 1 to 4.

10. A laminated assembly, as described in claim 8, characterized in that the support is a shoe.