FR2789559A1 - Injection molding or casting of shoe sole joined to upper directly during injection or by adhesion, is accompanied by insertion of granular core pack assisting manufacture, but removed subsequently, reducing weight - Google Patents

Abstract

Particulate core(s) are located in an already-fabricated shoe (10) sole (12), or in a sole during its fabrication. An upper (18) is fitted to the sole during or after its manufacture. The particles are withdrawn to form cavities (20) shaped identically to the core(s). An Independent claim is included for the sole so produced. Preferred features: In the case of injection or casting with simultaneous core introduction, the core particles are located in zones of the mold corresponding to the sole. The plastic is introduced, surrounding the cores. Polymerization or adhesion of the upper onto the sole is delayed and the particles are withdrawn, to leave the cavity (20) behind. An envelope contains the particles. This is pierced to allow their withdrawal. Sole and envelope are pierced, allowing particles to flow out through the hole, under gravity. They are pierced opposite the core, using a cannula connected to suction, which removes the particles. The top of the sole is pierced. Granule grading facilitates extraction. The envelope has a thick upper surface recovering from compressive forces, the sidewalls being similarly-constructed.

Description

METHOD FOR MANUFACTURING A SHOE SOLE BY

  INJECTION OR CASTING USING A PARTICLE CORE AND

SOLE OBTAINED

  The present invention relates to a method of manufacturing a shoe sole by injection or casting, using a particle core as well as

  the sole obtained by implementing this process.

  A first method of making shoes is known, which consists in making, in a first step, plastic soles by molding or injection, these soles being attached to the upper by gluing or welding in a second step. The upper of a shoe is the upper part of the shoe, usually sewn and made from cut pieces of leather, fabric or a complex thereof. These parts are cut according to particular shapes and assembled to allow

  obtaining the desired volume in the required form.

  For reasons of gain in material and weight, these soles have recesses, in the form of cells both in the heel area of the sole and in the thickness of the rest of the sole as soon as 7 millimeters

  1 5 are exceeded to give an idea.

  These recesses provide a honeycomb structure which stiffens the sole and gives it a good hold to achieve good bonding with the upper. On the other hand, this alveolar structure harms the damping capacity

of the sole.

  As for a sole that would be very loosely structured, its flexibility generate problems of rigidity during the bonding phase of the upper on the

sole, mounting.

  Another method of manufacturing a shoe with a sole is known, known as the injection method. Once the upper has been produced, this upper is introduced into the mold of an injection machine, designed to receive this upper and which has a reserve for the profile of the sole to be produced. The plastic material to constitute this sole is introduced under high pressure into the closed mold, in pasty or liquid form in the reserve provided for this purpose. The lower peripheral edge of the upper is designed to be embedded in the plastic material constituting the sole so that after polymerization and cooling, the

  conformed sole is perfectly fixed on the upper.

  The materials are selected for their good compatibility according to the knowledge of those skilled in the art in order to obtain a suitable quality bond.

  and respecting the desired mechanical strength parameters.

  The sole generally includes a rear part of a stronger

  thickness which is called "heel" for the rest of the description. This

  heel is greedy in raw material which constitutes the sole and also increases the weight unnecessarily. In addition, the heel is the area that is most stressed mechanically since the impact of the foot, during the attack on the ground during the

  walk, basically goes through that heel.

  Therefore, it is necessary to relieve the wearer by providing a cushioning zone to the right of this heel, which zone must also resist the

  compression to take up the efforts, essentially the weight of the wearer.

  On the other hand, in contrast, a priori, the heel must also remain very stable so as not to flare during the attack of the foot on the ground, which would have the effect

  direct to destabilize the walking of the wearer of this shoe.

  It is the same for the sole, apart from the heel and it is also necessary to provide recesses when the thickness becomes significant, generally as soon as the 7 millimeters are exceeded, as indicated previously. Thus, there is a gain in comfort and weight for the wearer, a gain in material for the manufacturer and a simultaneous response to the problems.

  amortization and resumption of efforts.

  However, in the case of rod injection, there is a problem because it is not possible to make recesses during manufacture, during the injection phase. A known solution to at least alleviate the problem of material consumption consists in providing cores. These cores are cores of suitable material, such as reconstituted wood or low cost plastic, shaped to the profile to be produced and arranged in the housing of the sole. During injection or pouring, the plastic material masks said core whose mechanical characteristics allow it

  withstand injection pressures and temperatures.

  The finished sole saved plastic, is

  reduced and nevertheless allows the resumption of efforts.

  These soles on the other hand have very low damping capacities.

  The method of manufacturing a sole according to the invention overcomes these problems and makes it possible to provide recesses in an injected sole.

on stem.

  In the case of sole produced by injection or casting, it is possible to produce cells, open on the top, that is to say towards the upper. In the case of the manufacture of a sole alone, by casting or injection without mounting on a rod, this is obtained by the simple shape of the mold. The problems already indicated above arise again during assembly. In fact, when the desired qualities of cushioning of the sole are obtained for the future wearer, the application of the upper to the sole is done with difficulty since the recovery of the bonding pressure forces is low with a sole.

structured but flexible.

  To this end, according to the invention, the method of manufacturing a shoe sole by injection or casting, attached to a rod, is characterized in that it consists of the succession of the following steps: - establishment of at least one particle core (22) in a sole already manufactured or in the course of manufacture, - mounting of the upper on the sole, simultaneously with the manufacture or subsequently, and - removal of the particles from the core (s) of the sole so as to generate a profile cavity substantially identical to that of the core (s). During the production of a sole with simultaneous positioning of the core (s), by injection or casting, the core (s) are placed in

  the mold, whether the rod is mounted simultaneously or later.

  According to another characteristic, a particle core is used comprising an envelope as a container and a filling material of the particle type and the envelope is perforated to allow the removal of this

filling material.

  According to a first mode, the sole and the envelope are perforated and left

  the particles flow by gravity through the generated hole.

  According to another mode, the sole and the envelope are pierced in line with the core, by means of a cannula connected to suction means and suction is carried out.

  the particles. The hole can be made from above the sole.

  Preferably, the filling material is composed of aggregates of

  dimensions adapted to allow withdrawal through the hole and / or cannula.

  In some variants, an envelope is used having an upper wall and / or thick side walls, which participate in the recovery of

compression forces.

  The invention also relates to the sole thus obtained.

  The method is now described in detail according to a particular, nonlimiting embodiment, with reference to the appended drawings in which the various figures represent: - Figure 1, a sectional view of a sole injected on a rod, provided with a obviously obtained by the method according to the invention, - Figures 2A, 2B and 2C, sectional views of a schematic block diagram of the steps of the method, - Figure 3, a cross-sectional view of a heel obtained after injection and before core removal, - Figure 4, a cross-sectional view of a first variant with

  reinforcement of the upper face, before removal of the particles.

  - Figure 5, a cross-sectional view of a second variant with also reinforced side faces, before removal of the particles, and - Figure 6, a cross-sectional view of a variant, before removal of the particles, with a damping profile attacking the step during the march.

  To simplify the description, the details of the process are given all

  first in the case of a sole injected on the upper.

  In FIG. 1, the shoe 10 comprises a sole 12 injected with a heel 14 and a bearing zone 16 surmounted by a rod 18. The rod is not shown in detail because it is not the object of the invention and the embodiments are numerous. Note that the lower peripheral edge is provided

  to be embedded in the injected plastic.

  The sole 12 has, in the heel, a recess 20, of simplified shape for the representation but whose profile can vary according to the

needs and applications.

  This obviously allows a substantial saving of material and by

therefore weight.

  The process for obtaining this recess is described opposite.

drawings 2A, 2B and 2C.

  First of all, a particle core 22 is produced separately. It consists of an envelope 24 forming a container and a product of

filling 26 forming the content.

  The envelope is made of a material of resistance adapted to withstand temperature and pressure during the injection of the plastic material.

constituting the sole.

  This envelope must also have sufficient mechanical strength to retain the content under the forces generated by the injection pressure, but it should be noted that this pressure is isostatic in the final phase, which limits these needs to an ability to resist disparities during

the mold filling phase.

  We will thus use an envelope made of a sheet of material

  plastic of suitable thickness as will be described later.

  The filling product must have certain mechanical characteristics and in particular, it must withstand the compression forces generated by the injection pressure, this in the range of injection temperatures, to maintain the volume and the shape which were initially given to it. . In addition, this filling product must have an essential characteristic, that of being able to be removed from the envelope which contains it through a hole, by flow, sublimation, dissolution or any other means, said

  hole in this envelope being of very small dimensions.

  As an example of filling products, mineral products such as aggregates, sands, glass beads or products may be used.

  organic particles like sawdust.

  In FIG. 2A, the rod is placed in the mold as well as the core 22

with particles.

  The plastic is then injected as shown in FIG. 2B and the particle core 22 is integrated into the material, in the case shown, more precisely within the heel. Figure 3 is a view in

  cross section showing the envelope and its filling product.

  The step in Figure 2C consists of piercing the sole to make a

  passage 28 for evacuating the particles contained in the envelope.

  To carry out such an operation, different solutions can be envisaged and one of them can be in the form of suction by

  a cannula 30 which provides the perforation and which allows the aspiration of the product.

  This means allows not only confinement of the operation but also the recovery of the filling product in the case where it is recyclable. The

  recovery time is also shortened.

  Note that the envelope remains in the heel because it is generally

  welded to the material constituting the sole.

  The sole then has an empty volume in the heel, the dimensions and shape of which must be adapted according to needs and applications. In the case of recourse to a cannula, the drilling being carried out without removal of material, the passage produced closes by the very elasticity of the material in which the sole is made. The cavity thus produced is

finds it isolated.

  For the passage of the drilling and suction cannula, it is advantageous to pass through the sole in the upper part because, in the case of a hole of larger diameter, this can be masked by the first, which

  is shown in broken lines in Figure 2C.

  This is particularly true for the variants of Figures 4, 5 and 6.

  In the variant of FIG. 4, the core 22 comprises an envelope with thin side walls 32 and bottom 34 while the top wall 36 is thick and constitutes a rigid support as such. Thus the user places his weight on this wall which itself bears on the side walls of the heel of the sole. The cavity generated after removal of the particles provides the finished product with a certain flexibility and a certain power of compression and cushioning of the heel, without the heel buckling under the

  pressure, thus causing a risk of the shoe wearer falling.

  In the case of the variant of Figure 5, the side walls have been reinforced and the side walls participate in the recovery of forces. Stiffness

  of the heel of the sole has been increased.

  In the case of the variant of FIG. 6, the upper face is thick and comes to bear on the edges of the heel. The cavity has a profile which makes it possible to reinforce the recovery of forces at the end of compression, while ensuring, at

  the attack of the step of the wearer of the shoe, a significant damping.

  The whole invention has just been described with regard to injection manufacturing, but it is perfectly and directly transposable to the soles

  made by casting which are then glued on rod.

  In this manufacturing technique, the sole is produced separately by pressureless casting, in a mold and the upper is designed elsewhere then

  the upper is attached to the corresponding sole by gluing.

  For a good bonding of the upper on the sole, the sole must be very rigid. It is detrimental to the quality of the assembly to make a bonding of a rod on a sole which compresses under the pressure exerted during bonding. Weak bonding points are indeed produced by bonding or misalignment of certain portions of the rod relative to the edges of

the sole.

  Also, in accordance with the present invention, the sole is made with a core and then the upper is attached by gluing. For this operation, if we take the same example as described above for the heel, it resists

  pressure and provides feedback during the pressing of the rod.

  After bonding, the particles are removed in the same way as above to form the cavity after joining the sole and the upper to give the finished product the desired flexibility and damping qualities. The cavities and the thicknesses of the walls of the envelope make it possible to achieve all the combinations sought according to the parameters of the shoes manufactured, high heel, low heel, of large cross section,

  thick support area.

  The manufacturing method according to the present invention can also be applied to soles manufactured separately. In this case, one of the cells, made in the sole, is filled with particles and closed during assembly of the rod. This filled cell is then emptied after mounting the rod. The advantage is to be able to benefit from a high rigidity during the

mounting of the rod.

Claims (10)

  1. Method for manufacturing a sole (12) of a shoe (10) by injection or casting, attached to a rod (18) directly during injection or by bonding, - installation of at least one core ( 22) with particles (26) in a sole already manufactured or in the course of manufacture, - mounting of the rod on the sole, simultaneously with manufacture or afterwards, and - removal of the particles from the core (s) of the sole so as to generate a cavity (20) of profile substantially identical to that of the or cores in the sole.   2. A method of manufacturing a shoe sole according to claim 1, characterized in that, in the case of injection or casting with simultaneous introduction of the core (s), it consists of the succession of the following steps: - setting in place of at least one particle core (22) in at least one zone of the mold corresponding to said sole, - injection or pouring of the plastic material into the mold for the production of this sole by including said one or more cores, - delay in polymerization or bonding of the upper to the sole, and - removal of particles from the core (s) of the sole so as to generate a cavity (20) with a profile substantially identical to that of the or cores in the sole.   3. A method of manufacturing a shoe sole according to claim 1 or 2, characterized in that one uses a particle core (22) comprising an envelope as a container and a particle type filling product as content and what the envelope is perforated for   allow the removal of this filling material.   4. Method for manufacturing a shoe sole according to claim 3, characterized in that the sole (12) and the shell are perforated and   the particles are allowed to flow by gravity through the generated hole.   5. A method of manufacturing a shoe sole according to claim 3 or 4, characterized in that the sole is punctured (12) and the envelope in line with the core, by means of a cannula (30) connected to of   means of aspiration and the particles are aspirated.   6. Method of manufacturing a shoe sole according to one of   claims 5, characterized in that one perforates from above the sole.   7. Method for manufacturing a shoe sole according to one   any of claims 3 to 6, characterized in that the material of   filling is made up of aggregates of suitable dimensions for   allow withdrawal through the hole and / or cannula.   8. Method for manufacturing a shoe sole according to one   any of claims 3 to 7, characterized in that a   envelope having a thick upper wall (36) which participates in the recovery of compression forces.   9. Method of manufacturing a shoe sole according to one   any of claims 3 to 8, characterized in that the walls   side (32) of the envelope are thick and participate in the recovery of compression forces.   10. Shoe sole obtained by implementing the method   according to any one of claims 1 to 9.