EP0479661A1 - Sliding bag fastener having a plastic closure consisting of mating strips - Google Patents

Abstract

The invention relates to a sliding fastener for sachets or bags having a plastic closure consisting of two mating strips, comprising two lateral wings which define, together with an elongated central sole plate, two convergent passage lanes for the mating strips, this sole plate being supported in an overhanging manner by a central separation rib. According to the invention, the lateral wings (101, 102) of the sliding fastener (100) are connected together by two linking bridges (103, 104), one of which is integral with the separation rib (105), the flexibility of the said bridges permitting automatic positioning of the sliding fastener by separation of its lateral wings; the separation rib (105) extends beyond the linking bridge (103) in the median plane of the sliding fastener so as to reinforce the rigidity of the link between rib and sole plate; the guide facet (115) associated with the smaller of the two strips has an inclined ramp extending over the entire length of the elongated sole plate (108) so as to reinforce the rigidity of this sole plate. Application to the production of sliding fasteners made of plastic material by moulding. <IMAGE>

Description

The present invention relates to slider closures, in which the cursor overlaps two interlocking profiles connected continuously to the edges of a sachet or bag, and allows, depending on its direction of travel, to open or close the closure by disengagement or mutual engagement of the profiles which elastically deform in said cursor.

Such plastic slide fasteners have been around for a long time.

It is thus known to produce a slider comprising two lateral wings connected to each other and which define, with an elongated central sole, two converging passage lanes for nestable profiles, said sole being supported in cantilever by a central rib of separation, and having, on either side of said rib, two guide facets, one of which is associated with the smaller of the two profiles and has an oblique part.

Such a cursor is for example described in French patent No. 1,532,295 filed by the applicant.

However, a cursor of this type has several drawbacks which are inherent in its structure.

A first drawback lies in the fragility of the connection between sole and rib, and in the flexibility of said sole.

Indeed, if we examine Figures 3 and 4 of the aforementioned French patent, we see that the separation rib extends over a short distance relative to the long overhanging length of the elongated sole, which extends to the level of the end of the slider, which induces excessive fragility and flexibility of this sole.

These defects, in addition to the weakness of the part itself, naturally have a very unfavorable effect on the precision of the guidance of the two nestable profiles and the resistance of the cursor to tilting (in a median plane of the cursor). It should also be noted that the guide facet associated with the smaller of the two profiles is formed by a first straight portion, very short, followed by an inclined portion, also very short, which is connected to a long straight portion. which is at the same level as the other facet, for the cantilever part of the elongated sole: now the first straight portion corresponds to the guide travel of the small profile, so that the guidance obtained is relatively imprecise and unreliable.

In addition, the difference in level between the two facets of the sole only exists over a very short length, and this is added to the already mentioned excessive flexibility of the elongated sole, further increasing the risk of the cursor tilting in rough handling.

To these defects is also added the fact that such a slider is not suitable for modern techniques of automatic installation by spacing its lateral wings.

Indeed, the lateral wings of this slider are connected to each other, and over their entire length, by a single thick and not very flexible bottom, so that, even by adding on this bottom longitudinal external ribs able to cooperate with an associated tool , the stiffness of this bottom would considerably hamper the spacing of the lateral wings.

There are also other types of sliders, the structure of which is more particularly adapted to an automatic positioning technique by spreading their lateral wings.

We can for example refer to European patent application No. 0 004 707, in which is described a slider whose lateral wings are connected together by a central connecting bridge, and which is surmounted by longitudinal ribs used to spread the wings lateral for automatic positioning of said slider.

However, such a slider does not have a real elongated sole favoring the guidance of the nestable profiles, but a short portion in the shape of an arrowhead, giving this slider an exit profile in the shape of a trident. In addition, this short portion defines two narrow axial passages through which pass the webs of the closure, so that any burrs in the joint plane may cut these webs at the slightest pressure exerted on the side faces of the slider. Finally, the manufacture by molding of this type of slider is complex, and requires the use of three cores, including two vertical cores passing on either side of the central connecting bridge.

The state of the art is also illustrated by the Luxembourg patent N ° 62,398, the French patents N ° 1,345,580 and N ° 2,268,704, and the Moroccan patent N ° 16,089, all filed by the applicant.

These patents illustrate the efforts and research that may have existed in this field, and this for more than twenty years.

Finally, reference may also be made to English patents N ° 744,730, N ° 914,204 and N ° 1,012,988, to American patents N ° 3,430,329 and N ° 3,324,520, and to Australian patent N ° 463,564.

The object of the invention is to provide a more efficient cursor, which is in particular satisfactory in terms of the quality of guidance of the nestable profiles, the absence of a tendency to tilt in the event of rough handling, and the absence of risk of deterioration of the profiles.

The object of the invention is also to produce a slider which is suitable for automatic laying by spreading its lateral wings, while being capable of withstanding very high laying rates: for information, we are currently targeting production rates higher than 3,000 bags per hour, all operations combined (manufacture of bags, bonding of nestable profiles, and installation of sliders).

The invention also aims to provide a heart seur whose structure allows a monobloc realization in plastic material, by molding, at reasonable financial conditions (therefore with molding installations of simple design and high efficiency, and with a minimum of material for each unitary slider).

• . les ailes latérales du curseur sont reliées entre elles par deux ponts de liaison définissant un évidement central, dont l'un est solidaire de la nervure de séparation, lesdits ponts présentant une flexibilité suffisante pour permettre une pose automatique dudit curseur par écartement de ses ailes latérales ;
• . la nervure de séparation supportant la semelle allongée se prolonge dans l'évidement central, au-delà du pont de liaison qui lui est solidaire et dans le plan médian du curseur, de façon à renforcer la rigidité de la liaison entre ladite nervure et ladite semelle ;
• . la facette de guidage associée au plus petit des deux profils présente une rampe inclinée s'étendant sensiblement sur toute la longueur de la semelle allongée, de façon à renforcer la rigidité de ladite semelle, l'autre facette de guidage étant droite jusqu'à l'extrémité libre de ladite semelle.

It is more particularly a slider for sachets or bags provided with a plastic closure with two interlocking profiles, comprising two lateral wings connected together and which define, with an elongated central sole, two converging passageways for the profiles nestable, said sole being supported in cantilever by a central separation rib, and having, on either side of said rib, two guide facets, one of which is associated with the smaller of the two profiles and has an oblique part, characterized in that:

• . the lateral wings of the cursor are connected together by two connecting bridges defining a central recess, one of which is integral with the separation rib, said bridges having sufficient flexibility to allow automatic positioning of said cursor by spacing its lateral wings ;
• . the separation rib supporting the elongated sole extends in the central recess, beyond the connecting bridge which is integral with it and in the median plane of the slider, so as to reinforce the rigidity of the connection between said rib and said sole ;
• . the guide facet associated with the smaller of the two profiles has an inclined ramp extending substantially over the entire length of the elongated sole, so as to reinforce the rigidity of said sole, the other guide facet being straight up to l free end of said sole.

Preferably, the separation rib extends, over its entire height, substantially up to mid-length of the central recess. A very satisfactory rigidity is thus obtained at the level of the connection between the rib and the elongated sole.

Advantageously also, the separation rib has a thick portion connecting to the connecting bridge which is integral with it, and is extended by a narrower portion beyond said connecting bridge. Such a variation in thickness does not appreciably reduce the rigidity of the connection between the rib and the elongated sole, and facilitates the molding operations since each portion of the rib is produced by one of the two cores which are necessary. to make the cursor.

According to an advantageous characteristic, the guiding facet associated with the smaller of the two profiles has a ramp in two parts, including a gently sloping part adjacent to the separation rib, and a more steep part extending to the free end of the elongated sole. This achieves a very satisfactory progressive guidance for the profile concerned.

Preferably also, the guide facet associated with the smaller of the two profiles has, beyond the separation rib, a substantially constant width up to the free end of the elongated sole. Although symmetry is no longer respected in this case, due to the tapered shape of the elongated sole, this constant thickness provides excellent rigidity at the cantilever end of said sole.

Advantageously also, the elongated sole is tapered symmetrically relative to the median plane of the cursor, with a free end at a distance from the corresponding end of the cursor. In particular, the elongated sole extends from one end of the slider, at the level of the separation rib, to a distance of the order of a quarter of the length of the slider from the other end of said slider, so as to define a common central corridor beyond the free end of said sole, and this common central corridor is delimited by facets parallel to the median plane of the cursor, formed on the inner side of the lateral wings. For example, the common central corridor has substantially the same length as the connecting bridge which delimits it above.

It is also interesting that the lateral edges of the elongated sole and the adjacent inner faces of the lateral wings are inclined at an angle substantially equal to 6 ° relative to the median plane of the cursor, and symmetrically relative to said plane.

Preferably, the central recess substantially concerns half of the total length of the cursor; in particular, the central recess has in section the general shape of an isosceles trapezoid, and admits as plane of symmetry the median plane of the cursor.

It is also advantageous for the cursor to be surmounted by two longitudinal ribs serving to separate the lateral wings with elastic bending of the two connecting bridges by cooperation with an associated tool, during the automatic positioning of said cursor, said longitudinal ribs bordering the central recess and extending to said connecting bridges.

Preferably also, the cursor is in the form of a single piece of plastic material, produced by molding.

• - la figure 1 est une vue en perspective d'un curseur connu, avec un arrachement permettant de mieux voir la semelle en crochet ;
• - la figure 2 est une vue en perspective d'un curseur conforme à l'invention, avec un arrachement permettant de mieux distinguer la nervure de séparation et la semelle allongée qu'elle supporte ;
• - la figure 3 est une vue de dessus du curseur de la figure 2, et la figure 4 une vue en bout de ce curseur;
• - la figure 5 est une vue latérale du même curseur, et la figure 6 une vue de dessous permettant de mieux distinguer les couloirs de passage des profils emboîtables ;
• - les figures 7 à 10 sont des vues et coupes, respectivement selon les lignes VII-VII, VIII-VIII, IX-IX et X-X de la figure 3, permettant de mieux comprendre les déplacements relatifs des profils emboîtables dans le curseur de l'invention ;
• - les figures 11 et 12 illustrent une unité de moulage permettant de fabriquer le curseur précité, la figure 11 montrant en vue de dessus l'insert inférieur et le noyau à tirette associé, et la figure 12 illustrant en coupe les inserts inférieur et supérieur, avec leur noyau associé.

Other characteristics and advantages of the invention will appear more clearly in the light of the description which follows and of the appended drawings, relating to a particular embodiment, with reference to the figures in which:

• - Figure 1 is a perspective view of a known cursor, with a cutaway to better see the hook sole;
• - Figure 2 is a perspective view of a cursor according to the invention, with a cutaway to better distinguish the rib from separation and the elongated sole that it supports;
• - Figure 3 is a top view of the cursor of Figure 2, and Figure 4 an end view of this cursor;
• - Figure 5 is a side view of the same slider, and Figure 6 a bottom view to better distinguish the passage lanes of nestable profiles;
• - Figures 7 to 10 are views and sections, respectively along lines VII-VII, VIII-VIII, IX-IX and XX of Figure 3, to better understand the relative displacements of the nestable profiles in the cursor of the invention;
• FIGS. 11 and 12 illustrate a molding unit making it possible to manufacture the aforementioned cursor, FIG. 11 showing a top view of the lower insert and the associated pull-out core, and FIG. 12 illustrating in section the lower and upper inserts, with their associated nucleus.

FIG. 1 illustrates a known cursor 1, with a cutaway making it possible to better see the short hook sole 6. Such a cursor is similar to that which is described in the European patent application No. 0 004 707 cited above.

The slider 1 has two lateral wings 2, 3, which are connected together by a central connecting bridge 4. This connecting bridge 4 carries a separation rib 5, tapering downwards, and at the lower end of which is provided a short sole 6 in the shape of an arrowhead. On this side of the cursor 1, the lateral wings have internally hooked projections opposite the arrowhead end 6: in FIG. 1, we can see the projection 9 carried by the side wing 2, which thus defines a passage narrow axial 10 through which one of the webs of the closure passes; an identical axial passage is naturally provided on the other side of the arrowhead end 6, opposite the right facet 16 of said end. The arrowhead end 6 has two symmetrical guide facets 7, 8, which are inclined, for guiding the interlocking profiles. The two axial passages open, beyond the arrowhead end 6, into a central corridor 11 delimited by the lateral wings 2, 3. The cursor 1 is also surmounted by two longitudinal ribs 14, 15, which can cooperate with a tool (not shown) which allow automatic positioning of said slider with spacing of the lateral wings 2, 3 (the spacing being effected by bending of the central connecting bridge 4).

A slider of this type has several drawbacks which have already been indicated above with regard to European patent application No. 0 004 707. We note in particular the poor guidance of the interlocking profiles by the facets 7, 8, these being symmetrical with respect to the median plane of the cursor, so that no account is taken of the fact that one of the two interlocking profiles is smaller than the other. The guide stroke is also extremely short, and the common central passage 11 covers the greater part of the length of the slider, so that the resistance to tilting is poor. Sliders of this type are normally made in one piece, by molding, and for this it is necessary to use three cores, including two vertical cores corresponding to the two recesses 12 and 13 separating the wings 2 and 3, on either side of the central connecting bridge 4, and a horizontal core carrying out the lower part of the end in the shape of an arrowhead 6 and of the projections of the lateral wings. The line 17 has been indicated on the figure corresponding to the trace of the joint plane on the facet 16 of the arrowhead end 6, the other symmetrical facet, as well as the two parallel facets carried by the projections of the lateral wings. , naturally have a trace identical to line 17 of the joint plane: therefore, any joint plane burrs risk cutting the webs of the closure at the slightest pressure exerted on the lateral faces of the slider.

We will now describe the cursor, object of the present invention, with reference to FIGS. 2 to 6.

The cursor 100 has two lateral wings 101, 102 which are connected together, not by a central connecting bridge like the cursor known in FIG. 1, but by two connecting bridges 103, 104, defining between them a central recess 120. The two connecting bridges 103, 104 thus extend from each of the ends of the slider, respectively the end 111 said end on the outlet side, and the end 116 said end on the inlet side. These connecting bridges 103, 104 have sufficient flexibility to allow automatic positioning of the cursor 100 by spacing its two lateral wings 101, 102: for this, the cursor 100 is surmounted by two longitudinal ribs 129, 130 serving to separate the lateral wings 101 , 102 with elastic bending of the two connecting bridges 103, 104, which makes it possible to open the passage corridors for the interlocking profiles, according to a technique analogous to that already described above. It should be noted that the central recess 120 opens directly in the interior space of the cursor, so that it will suffice to use a single vertical core for the manufacture of this cursor by molding (as will be explained more far with reference to FIGS. 11 and 12), unlike the known cursor illustrated in FIG. 1.

The two lateral wings 101, 102, linked together by the connecting bridges 103, 104, define, with an elongated central sole 108, two converging passage lanes 117, 118 (only the passage 118 is visible in the perspective view of FIG. 2) for interlocking profiles, said elongated central sole being supported in overhang by a central separation rib 105.

However, unlike what is described in French patent No. 1,532,295 commented above, the separation rib 105 is carried by a connecting bridge (here the connecting bridge 103) and not by a bottom covering the entire length of the slider, and more this separation rib extends into the central recess 120, beyond the connecting bridge 103 which is integral with it and in the median plane 200 of the slider, so as to reinforce the rigidity of the connection between this rib and the central sole elongated 108. The separation rib 105 thus extends over a significant length of the central sole 108, in particular more than half of the length of this sole, which considerably reinforces the resistance to bending at the connection between the separation rib and elongated central sole. Preferably, the separation rib 105 extends, over its entire height, substantially up to mid-length of the central recess 120. Furthermore, the separation rib 105 here has a thick portion 106 connecting to the connecting bridge 103 which is integral with it, and is extended by a narrower portion 107 beyond said connecting bridge. Such a variation in thickness in the separation rib, better visible in the views of FIGS. 3 and 6, does not significantly reduce the rigidity of the connection between the separation rib and the elongated base, and has the advantage of facilitating the operations of molding insofar as each portion 106 and 107 is produced by one of the two cores used to make the cursor 100 by molding, as will be explained below with reference to FIGS. 11 and 12.

The elongated central sole 108, supported in cantilever by the central separation rib 105, has, on either side of said rib, guide facets, one of which is associated with the smaller of the two profiles, and has an oblique part. The general principle of an elongated central sole having two guiding facets with a portion of different height is in itself well known, as is apparent from French patent No. 1,532,295 already cited above. However, in the context of the present invention, the guide facet which is associated with the smaller of the two profiles has here a particular structure which is very different from that described in the aforementioned French patent. Indeed, and in accordance with an essential characteristic of the invention, the guide facet associated with the smaller of the two profiles, here facet 115, has an inclined ramp 115 ′, 115 "extending substantially over the entire length of the elongated sole 108: the advantage of such a structure is twofold, insofar as this makes it possible not only to lengthen the guide travel of the smaller of the two profiles due to the large length of the inclined ramp, but also to considerably reinforcing the rigidity of the elongated sole 108, the guide facet 115 thus fulfilling an additional stiffening function of this sole. The other guide facet, here facet 114, is straight up to the free end 113 of the elongated central sole 108, but it is bordered over its entire length first by the separation rib 105, then by the adjacent reinforcement rib whose upper face constitutes the guiding facet inclined age 115.

This achieves both excellent rigidity for the elongated central sole, which withstands well the flexing forces which can cause the cursor to tilt in its median plane, as well as continuous guidance of the two interlocking profiles (which also contributes resistance to tilting), while making it possible to automatically place the slider by spreading its lateral wings thanks to the flexibility of the two connecting bridges, one of which supports the elongated central sole.

As can be seen in FIG. 2, the guide facet 115 associated with the smaller of the two profiles has a ramp in two parts 115 ′, 115 ", including a gently sloping part 115 ′ adjacent to the separation rib 105, and a steeper part 115 "going to the free end 113 of the elongated sole 108. It goes without saying, however, that a different level variation could be provided, with for example a rounded connection in the vicinity of the end free of the elongated sole 108, as far as one naturally observes the principle of a raised guiding facet which extends substantially over the entire length of said sole, so as not to affect the rigidity of the latter .

The elongated sole 108 is tapered relative to the median plane 200 of the cursor 100, at an angle which is for example of the order of 6 ° relative to the median plane 200, and symmetrically relative to said plane. However, it is advantageous to provide, as is better visible in FIG. 3, that the guide facet 115 associated with the smaller of the two profiles has, beyond the separation rib 105, a width that is substantially constant up to the free end 113 of the elongated sole 108. This makes it possible to preserve the rigidity of the elongated central sole up to the free end of the latter.

The elongated central sole 108 thus has a generally triangular shape, with lateral edges 123 and 124 inclined relative to the median plane of the slider, these lateral edges converging towards each other from the wide end 109 of the sole up to at the other narrow end thereof, which is the free end 113. The face of the wide end 109 of the elongated central sole 108 is preferably contained in the plane of the end 111 of the slider (side end outlet), so as to define an end face relating to both the lateral wings 101, 102, the associated connecting bridge 103, and the separation rib 105. The underside of the elongated central sole 108 also extends along a plane substantially parallel to the straight facet 114 of said sole, with a bottom 127 which may be possible ment bordered by a fillet 128 of connection over the entire periphery of the sole, as can be seen in the figure below from FIG. 6. Such an arrangement does not affect the mechanical characteristics of the slider nor the rigidity of the sole, but facilitates manufacturing operations by molding.

Furthermore, it should be noted that the elongated sole 108 has a free end 113 which is at a distance from the end 116 of the slider (end on the inlet side). This is advantageous not only insofar as it is possible to reduce the cantilever length of the elongated central sole, but also insofar as it is thus possible to have a common central corridor 119 in which open the lateral passage corridors 117, 118, the outlet of this common central corridor towards the outside also being done parallel to the median plane of the slider, which avoids a sudden change of direction for the interlocking profiles and the sails which carry them , at this end of said cursor. Indeed, as can be seen more clearly in FIG. 6, the common central corridor 119 is delimited by facets 121, 122 parallel to the median plane 200 of the cursor, facets which are formed on the inner side of the lateral wings 101, 102.

This arrangement thus provides a significant advantage over the known cursor described in French patent No. 1,532,295 already cited, because the known cursor had an elongated central sole extending to the level of the end edge of the cursor, where an important overhang, with in addition a marked angle for the interlocking profiles and the sails which carry them.

Preferably here, the elongated sole 108 extends from the end 111 of the cursor to a distance of the order of a quarter of the total length of the cursor from the other end 116 of said cursor, so as to define a corridor common central 119, beyond the free end 113 of the sole, extending over approximately a quarter of the total length of said slider. Advantageously, the common central corridor 119 will have substantially the same length as the connecting bridge 104 which delimits it above, since this simplifies the manufacture of the cursor by molding.

As is better visible in the views of FIGS. 3 and 6, the lateral edges 123, 124 of the elongated sole 108, and the adjacent interior faces of the lateral wings 101, 102 (faces 125 and 126), are all inclined according to a same angle with respect to the median plane 200 of the cursor, this angle possibly being substantially equal to 6 ° as indicated above, by being arranged symmetrically with respect to said plane. The internal faces 125, 126 of the lateral wings 101, 102 preferably extend vertically, that is to say perpendicular to the two connecting bridges of the cursor, so as to simplify the manufacture of said cursor by molding: in this case, the central recess 120 has in section the general shape of an isosceles trapezoid, and admits as plane of symmetry the median plane 200 of the cursor. Advantageously also, the central recess 120 relates substantially to half of the total length of the cursor, the other half being distributed over the length of each of the connecting bridges 103, 104. It will moreover be preferable to provide a bridge link 103 long enough to ensure a solid link with the separation rib 105, which explains why this link bridge 103 is shown here longer than the other link bridge 104.

As can be seen in FIGS. 3, 5 and 6, the lateral wings 101 and 102 have externally teeth 140 to facilitate gripping the cursor 100 with two fingers, as is well known in this field.

The operating mode of the cursor 100 which has just been described will be well understood with reference to FIGS. 7 to 10, which are views and sections illustrating the relative displacements of the profiles which fit into said cursor.

If one places oneself on the entry side of the cursor, that is to say in front of the end 116 of the latter, one sees the two interlocking profiles in the state of interengagement (seen in FIG. 7), these profiles and the upper zone of the closing webs which carry them passing through the common central corridor 119. Two interlocking profiles 201, 202 are shown here extending the edges of the associated closing webs 203, 204, it being understood that the precise structure of each of these profiles are simply shown by way of example, and that any other type of nestable profiles can be used. Profile 201 here has two branches with a hook-shaped end, while profile 202 has three branches, two of which have a hook-shaped end: in accordance with the terminology previously used, profile 201 is therefore the most small of the two profiles, that is to say the one concerned by the guide facet 115 in inclined ramp of the elongated central sole. If one places oneself at the opposite end of the slider, on the output side thereof, therefore in front of the end 111 (seen in FIG. 10), the nestable profiles 201 and 202 are then disengaged one of the 'other, by progressive spacing with elastic deformation inside the cursor 100. Intermediate positions are illustrated in Figures 8 and 9, which are sections made substantially in the first and second third respectively, starting from the end on the inlet side of the cursor, that is to say of the end 116 of said cursor.

It goes without saying that the representations of FIGS. 7 to 10 are essentially schematic, and are only intended to illustrate the relative displacement of the nestable profiles in the cursor of the invention (in particular, it should be noted that the separation rib and the sole elongated central unit have not been shown in FIG. 7, so as not to load the representation). These figures clearly show that the small profile, that is to say the profile 201, is guided continuously throughout its contact with the facet 115 in inclined ramp of the elongated central sole 108, so that the small profile remains always well positioned relative to the complementary nestable profile 202, with in addition an effective resistance to the tilting of the cursor in the median plane of said cursor in the event of rough manipulation of the latter.

The foregoing description shows that it has thus been possible to produce a particularly efficient cursor, and in particular very satisfactory in terms of the quality of the guidance of the interlocking profiles, and the absence of a tendency to tilt in the event of rough handling. The elongated central sole remains well positioned relative to the rest of the body of the slider, and its own rigidity is very high compared to known sliders. In addition, such a slider is entirely suitable for automatic laying by spreading its lateral wings, while being able to withstand very high laying rates, compatible with a production rate of 3,500 bags per hour.

We will now quickly describe a molding unit making it possible to manufacture the aforementioned cursor, this in order to illustrate the ease of making this cursor by molding, in the form of a single piece made of plastic, with a molding installation of simple, high-performance design with minimal material for each unit slider.

As can be seen in FIG. 12, a molding unit 300 comprises a lower insert 301 and an upper insert 302, as well as two cores 303 and 304. The lower insert 301 here has three injection points 305, including one injection point located in the median plane of the insert (which corresponds to the median plane of the slider) and provided at the level of the enlarged bottom of the elongated central sole of said slider. The lower insert 301 also includes an axial passage 306 making it possible to insert the horizontal core 303, which is a pull-out core, in a direction parallel to the joint plane. The core 303 has two end tabs 307 and 308, with a relative offset in height between them, to produce a portion of each of the two guide facets of the elongated central sole. The slot 309 defined between the legs 307 and 308 of this core 303 corresponds to the thick portion 106 of the separation rib 105: if one refers to the bottom view of Figure 6, it is thus understood that the legs 307 and 308 of the core 303 extend (when the molding unit is in the injection position, with the inserts arranged one against the other and the two cores in place) up to the level of the rear edge 141 of the central recess 120. The upper insert 302 has a vertical corridor 310 allowing the vertical core 304 to be put in place, the lower portion 311 of which then completes the end of the first horizontal core 303 (when these two cores are in place for injection), in order to make the remaining part of the elongated central sole and of the separation rib, that is to say the parts which extend beyond the edge 141 of the connecting bridge 103. The cutaway illustrated for the vertical upper core 304 mo ntre also a slot 312 which completes the slot 309 of the horizontal core 303 (when the two cores are in place), and corresponds to the narrow portion 107 of the separation rib 105. If we refer again to the view of below in FIG. 6, it can be seen that the thicker portion 106 extends very slightly beyond the edge 141 of the connecting bridge 103, which corresponds, for the vertical upper core 304, to a very slight flaring of the opening of the slot 312: this makes it possible to facilitate the flow of the material during the injection, and to avoid any defect in molding, such as shrinkage, which would risk weakening the mechanical resistance of this rib.

The possibility of using only two cores for the molding operations is naturally very advantageous, insofar as it considerably simplifies the manufacturing operations, and where it makes it possible to have a multitude of cavities for each mold, for example at least twenty -four cavities per mold (each cavity requires a unit of the type illustrated in Figure 12). Once the cursor is produced by molding, it is sent to an automatic installation station, and it is very easily put in place thanks to the longitudinal ribs 129, 130 which cooperate with an appropriate tool (not shown here) to spread the wings side of said cursor.

The molding unit which has just been described is further such that the joint plane is not located at a lateral edge 123 or 124 of the elongated central sole 108, so that these lateral edges are free of any burrs, which ipso facto eliminates any risk of cutting the closing webs when a certain pressure is exerted on the lateral faces of the slider.

The invention is not limited to the embodiment which has just been described, but on the contrary encompasses any variant incorporating, with equivalent means, the essential characteristics indicated above.

Claims (14)

1 / Slider for sachets or bags provided with a plastic closure with two interlocking profiles, comprising two lateral wings connected together and which define, with an elongated central sole, two converging passageways for interlocking profiles, said sole being supported in overhang by a central separation rib, and having, on either side of said rib, two guide facets, one of which is associated with the smaller of the two profiles and has an oblique part, characterized in that: . the lateral wings (101, 102) of the slider (100) are interconnected by two connecting bridges (103, 104) defining a central recess (120), one of which (103) is integral with the separation rib ( 105), said bridges having sufficient flexibility to allow automatic installation of said slider by spacing its lateral wings; . the separation rib (105) supporting the elongated sole (108) extends into the central recess (120), beyond the connecting bridge (103) which is integral with it and in the median plane (200) of the slider, so as to strengthen the rigidity of the connection between said rib and said sole; . the guide facet (115) associated with the smaller of the two profiles has an inclined ramp (115 ′, 115 ") extending substantially over the entire length of the elongated sole (108), so as to reinforce the rigidity of said sole , the other guide facet (114) being straight up to the free end (113) of said sole. 2 / Slider according to claim 1, characterized in that the separation rib (105) extends, over its entire height, substantially up to mid-length of the central recess (120). 3 / Slider according to claim 1 or 2, characterized in that the separation rib (105) has a thick portion (106) connecting to the connecting bridge (103) which is integral with it, and is extended by a more narrow (107) beyond said connecting bridge. 4 / Slider according to one of claims 1 to 3, characterized in that the guide facet (115) associated with the smaller of the two profiles has a ramp in two parts (115 ', 115 "), one part in gentle slope (115 ') adjacent to the separation rib (105), and a more sloping part (115 ") going as far as the free end (113) of the elongated sole (108). 5 / Slider according to one of claims 1 to 4, characterized in that the guide facet (115) associated with the smaller of the two profiles has, beyond the separation rib (105), a substantially constant width to the free end of the elongated sole (108). 6 / Slider according to one of claims 1 to 5, characterized in that the elongated sole (108) is tapered symmetrically relative to the median plane (200) of the cursor, with a free end (113) at a distance from the corresponding end (116) of the cursor. 7 / Slider according to claim 6, characterized in that the elongated sole (108) extends from one end (111) of the slider, at the level of the separation rib (105), up to a distance from the order of a quarter of the length of the slider from the other end (116) of said slider, so as to define a common central corridor (119) beyond the free end (113) of said sole. 8 / Slider according to claim 7, characterized in that the common central corridor (119) is delimited by facets (121, 122) parallel to the median plane (200) of the cursor, formed on the inner side of the lateral wings (101, 102). 9 / Slider according to claim 7 or 8, characterized in that the common central corridor (119) has substantially the same length as the connecting bridge (104) which delimits it above. 10 / Slider according to one of claims 6 to 9, characterized in that the lateral edges (123, 124) of the elongated sole (108) and the adjacent interior faces (125, 126) of the lateral wings (101, 102 ) are inclined at an angle substantially equal to 6 ° relative to the median plane (200) of the cursor, and symmetrically relative to said plane. 11 / Slider according to one of claims 1 to 10, characterized in that the central recess (120) concerns substantially half of the total length of the cursor. 12 / Slider according to claim 11, characterized in that the central recess (120) has in section the general shape of an isosceles trapezoid, and admits as plane of symmetry the median plane (200) of the cursor. 13 / Slider according to one of claims 1 to 12, characterized in that it is surmounted by two longitudinal ribs (129, 130) serving to spread the side wings (101, 102) with elastic bending of the two connecting bridges (103, 104) by cooperation with an associated tool, during the automatic fitting of said slider, said longitudinal ribs bordering the central recess (120) and extending to said connecting bridges. 14 / Slider according to one of claims 1 to 13, characterized in that it is in the form of a single piece (100) of plastic material, produced by molding.

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