WO2013124600A2

WO2013124600A2 - Method for producing a ski by injecting a thermoplastic material into a mould

Info

Publication number: WO2013124600A2
Application number: PCT/FR2013/050375
Authority: WO
Inventors: Patrick Doby; Stéphane Bernard; Antoine Bouvier
Original assignee: Decathlon
Priority date: 2012-02-24
Filing date: 2013-02-22
Publication date: 2013-08-29
Also published as: WO2013124600A3; RU2014137850A; FR2987278A1; FR2987278B1; RU2633157C2; EP2817073A2

Abstract

The invention relates to a method for producing a ski by injecting a thermoplastic material into a mould (1), said method including the steps of: - injecting a thermoplastic material into the cavity (2) of said mould; - letting said thermoplastic material harden in order to obtain a ski having the shape of said cavity; - removing the ski thus formed from said mould; the bottom of said cavity having at least one structured imprint (3) which is arranged to form, during the moulding of said ski, a sliding structure on the sole of said ski.

Description

Method of manufacturing a ski by injecting a thermoplastic material into a mold

The invention relates to a method for manufacturing a ski by injecting a thermoplastic material into a mold.

Document SI-22529 discloses such a manufacturing method which notably provides for:

injecting a thermoplastic material into the cavity of a mold;

- Allow said thermoplastic material to harden to obtain a ski having the shape of said cavity;

removing from said mold the ski thus formed.

In addition, this method may provide, after cooling the ski, to perform at least one step of sanding the sole of said ski. This step not only optimizes skiing properties of the ski, but also cleans any residues.

However, this method is not entirely satisfactory, in that the structuring of the gliding sole requires an additional operation after molding the ski.

Furthermore, document US Pat. No. 4,185,051 discloses a method of manufacturing a ski by injection of thermoplastic materials, in which the soleplate is formed by injecting a thermoplastic resin into the cavity of the mold and on the lower surface. cooled ski, so that said sole is firmly attached to said ski.

However, this method requires an additional step of overmolding by injection of a thermoplastic material, said step being constraining to implement. The invention aims to improve the prior art by proposing a method of manufacturing a ski in a single molding operation, in order to significantly reduce the manufacturing costs while enabling a ski with a sole to be obtained. satisfactory sliding and flexible according to the needs.

For this purpose, the invention proposes a method for manufacturing a ski by injecting a thermoplastic material into a mold, said method providing for:

injecting a thermoplastic material into the cavity of said mold;

removing from said mold the ski thus formed;

the bottom of said cavity having at least one structured impression which is arranged to form, during the molding of said ski, a sliding structure on the sole of said ski.

Other features and advantages of the invention will appear in the description which follows, made with reference to the appended figures, in which:

- Figure 1 is a partial schematic exploded perspective view of the tank of a mold for carrying out a method according to the invention;

- Figures 2 are schematic representations of structured impressions according to one embodiment of the invention respectively. In connection with these figures, a method of manufacturing a ski by injecting a thermoplastic material into a mold 1 is described below.

The thermoplastic material may comprise a polymer, for example based on polyamide (PA), such as Durethan® BKV 130 sold by Lanxess®. The polymer may also be based on polyoxomethylene (POM), polycarbonate (PC), or a mixture of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). Moreover, The polymer may be filled with fibers, for example glass, carbon or linen, especially with a content of between 15% and 30%.

In addition, the polymer may be previously subjected to a steaming, in order to avoid the thermoplastic material any defect related to the absorption of ambient moisture by said polymer. For example, if the polymer is based on Durethan® BKV 130, it can be baked for four hours at 80 ° C.

The method provides for injecting such a thermoplastic material into the cavity 2 of the mold 1. To do this, the thermoplastic material is heated and thermoregulated in a plastic sleeve, for example at a temperature between 240 ° C and 310 ° C, and then injected under high pressure into the cavity 2. In particular, the thermoplastic material can be injected at a pressure between 500 bar and 750 bar.

After injection of the thermoplastic material, the method provides for the molding of the ski by allowing said thermoplastic material to harden, in order to obtain a ski having the shape of the cavity 2, and then to remove from the mold 1 the ski thus formed. To mitigate the shrinkage of the thermoplastic material during its cooling, the method can provide to apply in the mold a constant holding pressure, in particular between 450 bar and 700 bar, in particular to prevent deformation of the gliding sole.

In particular, the bottom of the cavity 2 has at least one structured impression 3 which is arranged to form, during the molding of the ski, a sliding structure on the sole of said ski. Thus, the method allows for a ski with a sole having a sliding structure in a single injection molding operation. In addition, depending on the ski model that is desired, the method may provide for placing and maintaining edges on either side of the footprint 3, in order to mold a ski whose sole is bordered by said edges. In In particular, the edges can already be sharpened before they are placed in the mold 1.

According to an advantageous embodiment, the manufacturing method makes it possible to change the behavior of the ski by the use of an insert placed in the mold 1, possibly in addition to the edge, for example arranged to evolve at least one mechanical property of said ski , in particular among its local stiffness or all along said ski as well as its resistance. In particular, parts of soles may be molded to provide specific goals such as impact resistance, scratch, on the spatula front or rear.

In general, any model and / or any form of structuring are feasible on the bottom of the cavity 2. Different structures can be mixed, staged, sectored at will along the sole. In particular, it is possible to go from one structuring to another, to overlap, to mix, to achieve an evolutionary structuring in the 3 dimensions (width, length, depth) evolving continuously or discontinuously.

Advantageously, each structuring point can be defined individually, for example depending on the type of skier and / or the need. Thus, the evolutionary character of the ski can adapt to the snow on the whole of the glide and the ski-ski contact, thanks to the uneven distribution and thus to the packing as well as non-uniform heating of the snow. In particular, the front creates a film of water, the pad stabilizes and the rear evacuated to improve the glide and adapt the nature of the ski to the settlement of the snow.

In relation with FIGS. 2, the structured imprint 3 may for example have grooves oriented in the length of the ski (FIGS. 2a-2c), or crossed grooves (FIGS. 2d-2f). In addition, according to the desired roughness for the footprint 3, and therefore for the sliding structure of the sole, the grooves form a more or less significant density network. In known manner, the sliding structure allows to evacuate the film of water created by heating between the sole and the snow during use of the ski. As a result, the parameters of the gliding structure, and in particular its roughness, can be chosen according to the level of glide desired for the ski, for example a standard level for a recreational ski or a level more confirmed for a ski of competition. The roughness can also be chosen according to the characteristics of the snow on which the ski will be used, or the desired style effects.

In particular, the bottom of the cavity 2 may have a plurality of impressions 3 which differ in their structure, in particular by the arrangement of their grooves and / or their roughness, and according to the position of said imprints on the length of the ski, the performances of slips and / or the desired style effects. For example, to make a beginner's ski, it can be provided to have a footprint 3 having a greater roughness at the heel of the ski, in order to limit the speed of sliding.

Thus, one can provide a sole whose sliding structure has furrow networks that evolve from the spatula to the heel of the ski, in particular to promote the evacuation of the film of water formed between said sole and the snow.

Furthermore, the roughness of the sliding surface can be chosen according to the characteristics of the thermoplastic material injected, in particular its viscosity. Indeed, when the viscosity of the thermoplastic material is low, said material is easily distributed in the cavity 3 during molding, so that one can provide a structured imprint 3 having grooves of low depth and width. On the contrary, when the viscosity of the thermoplastic material is large, it is necessary to provide a structured cavity 3 having grooves of depth and width, in order to compensate for the poor flow of said material in said grooves. In relation with FIG. 1, the method provides for placing in the mold 1 at least one removable block 4, for example made of aluminum, said block following the ski hill line and having an upper surface 5 on which at least one impression structured 3 is formed. To do this, the vessel 1 of the mold 1 comprises a housing 6 in which the pad 4 may be arranged forming the bottom of the cavity 2 on which the sole of the ski will be formed.

In particular, the removable pad 4 may be chosen from several blocks having different structured impressions depending on the desired structure for the sole of the ski. Thus, the method can allow the manufacture of skis with different gliding soles by simply changing the pad 4 disposed in the mold 1. In Figure 1, a single block 4 is disposed in the housing 6 of the tank, said pad having dimensions substantially equal to those of said housing. In particular, the upper surface 5 of the pavement 4 may include several footprints 3 which differ in their structure, in order to produce a sole whose sliding structure evolves from the spatula to the heel of the ski.

Alternatively, the method may provide to have in the housing 6 several removable blocks 4 of dimensions smaller than those of said housing, said blocks having on their upper surfaces 5 footprints 3 which differ in their structure. Thus, the realization of the bottom of the cavity 2 is more modular.

The structured imprint 3 can be formed on the removable block 4 by grinding. In particular, it is possible to use a conventional grinding machine, comprising a grinding wheel on which a previously chosen structuring pattern is etched by means of a diamond head, the structured imprint 3 then being formed by successive passages of the upper surface 5 of the grinding machine. block 4 on said wheel in rotation. The structured imprint 3 can also be formed by chemical etching. To do this, it is possible to protect certain areas of the upper surface 5 of the pavement 4, then to dip said pavement in an acid bath, in order to form the impression by chemical reaction of the acid on the unprotected areas of said area.

Alternatively, the structured imprint 3 may be formed by removing material by laser ablation on the upper surface 5 of the removable pad 4, or by machining by means of a numerically controlled machine.

Claims

1. A method of manufacturing a ski by injecting a thermoplastic material into a mold (1), said method providing for:

injecting a thermoplastic material into the cavity (2) of said mold;

removing from said mold the ski thus formed;

said method being characterized in that the bottom of said cavity has at least one structured imprint (3) which is arranged to form, during the molding of said ski, a sliding structure on the sole of said ski.

2. Method according to claim 1, characterized in that the structured imprint (3) has furrows oriented in the length of the ski.

3. Method according to claim 1 or 2, characterized in that the structured imprint (3) has crossed grooves.

4. Method according to any one of claims 1 to 3, characterized in that the bottom of the cavity (2) has several imprints (3) which differ in their structure.

5. Method according to any one of claims 1 to 4, characterized in that it provides to dispose in the mold (1) at least one removable block (4) having an upper surface (5) on which at least one structured imprint (3) is formed.

6. Method according to claim 5, characterized in that the removable block (4) is selected from several pavers with different structured impressions (3) depending on the desired structure for the sole of the ski.

7. Method according to any one of claims 1 to 6, characterized in that the thermoplastic material comprises a fiber-loaded polymer.

8. Method according to any one of claims 1 to 7, characterized in that the thermoplastic material is injected into the mold (1) at a pressure between 500 bar and 750 bar.

9. Method according to any one of claims 1 to 8, characterized in that the molding is carried out with a holding pressure between 450 bar and 700 bar.

10. Method according to any one of claims 1 to 9, characterized in that it provides for placing and maintaining edges on either side of the footprint (3) to mold a ski whose sole is bordered by said edges.