FR3109329A1 - Process for making a motor vehicle floor panel - Google Patents

Abstract

The invention relates to a method for producing a floor panel (1) of a motor vehicle, providing for: producing in a plate a plurality of pre-cuts having a plurality of recessed areas separated by non-recessed areas, so that said pre-cut is fractionated; making a protective layer (16) of elastomeric polyurethane, said polyurethane furthermore inserting itself into said recessed areas by overmolding said plate according to its thickness; making a cutout (9) forming at least one orifice (11), the inner wall (12) of which has reinforcing parts (13) where the polyurethane extends along the entire thickness of said panel, said reinforcing parts being separated between them from each other by joining parts (15) where the polyurethane extends only a fraction of the thickness of said panel. Figure 2a

Description

Process for producing a motor vehicle floor panel

The invention relates to a method for producing a motor vehicle floor panel and a panel obtained by such a method.

It is known to produce a motor vehicle floor panel by a method comprising the following steps:

• provide a plate with a back side and a front side,
• placing said plate in a mold forming a molding cavity, said back face being pressed against the bottom of the mold, said cavity being arranged so as to define a molding space above said front face,
• fill said space with an elastomeric polyurethane precursor mixture, so as to produce a protective layer of elastomeric polyurethane overmolding said front face,
• after demolding, make at least one cutout so as to form at least one orifice.

Such an orifice allows in particular the passage of a member such as a seat base.

And the fact of using elastomeric polyurethane to make the protective layer makes it possible to have a layer that is particularly robust in terms of abrasion.

However, with such a way of proceeding there is the risk of insufficient cohesion between the protective layer and the plate on the periphery of the orifice, said layer risking separating from said plate on said periphery, which in particular causes a aesthetic damage.

To overcome this drawback, it has been proposed to make in the plate, before it is placed in the mold, at least one cutout defining a widened orifice, said mold being arranged so as to occupy the central part of said widened orifice while allowing the polyurethane to be inserted at its periphery by overmolding said plate according to its thickness, which makes it possible to reinforce the cohesion between the protective layer and said plate at the periphery of said orifice.

However, such a means of proceeding is not suitable for a situation where it is desired, from a common panel base, to produce a plurality of types of panels adapted to different variants of the same vehicle, the panel of a reference vehicle model differing from that of another model by a variation in the locations of the orifices.

Indeed, in this situation it would be necessary to provide as many types of molds as vehicle models, which would complicate the production of the panels and their manufacturing cost.

Furthermore, in such a situation, it is preferable to provide one type of plate per type of panel, said plate being provided only with the required orifices, in order to avoid having on the panel areas in which orifices of the plate would be obscured by the protective layer; in fact, such zones would constitute parts of the panel with less mechanical resistance to depression, whereas such resistance is required on a maximized surface in the case of a vehicle floor panel.

This results in another additional manufacturing cost linked to the production of as many types of plates as types of panels.

The object of the invention is to overcome these drawbacks.

To this end, and according to a first aspect, the invention proposes a method for producing a motor vehicle floor panel, said method comprising the following steps:

• provide a plate with a back side and a front side,
• making in said plate a plurality of pre-cuts in the general shape of a strip closing on itself, said strip having a plurality of recessed areas separated by non-recessed areas, so that said pre-cut is split,
• placing said plate in a mold forming a molding cavity, said back face being pressed against the bottom of the mold, said cavity being arranged so as to define a molding space above said front face,
• filling said space with an elastomeric polyurethane precursor mixture, so as to produce a protective layer of elastomeric polyurethane overmolding said front face, said polyurethane also inserting itself into said recessed zones by overmolding said plate according to its thickness,
• after demoulding, making on at least part of said pre-cuts a cutout extending in the middle part of the width of the strip and closing on itself, so as to form at least one orifice, the internal wall of said orifice having reinforcing parts , located directly above said recessed zones, where the polyurethane extends along the entire thickness of said panel, said reinforcing parts being separated from each other by junction parts where the polyurethane extends only according to a fraction of the thickness of said panel.

With the proposed arrangement, the internal wall of the orifice has reinforcement parts where the polyurethane extends along the entire thickness of the panel, which makes it possible to substantially reinforce the cohesion between the protective layer and the plate on the periphery. of said orifice.

In addition, when it is desired to produce a variety of panels differing from each other by the location of the orifices, it suffices to provide a plate common to this diversity, said plate being provided with all the pre-cuts likely to lead or not to subsequent cutting to make a hole.

In the case of a pre-cut which has not been the subject of a subsequent cut, the zone of the panel where said pre-cut is located presents a notable resistance to depression due to the existence of a part of the plate inside said pre-cut, said part being attached to the rest of said plate by the non-recessed areas.

According to a second aspect, the invention proposes a panel obtained by such a process.

Other particularities and advantages of the invention will appear in the following description, made with reference to the attached figures, in which:

,

And

are partial schematic front views (FIG. 1a) and along two section lines AA (FIG. 1b) and BB (FIG. 1c) of a panel according to a first embodiment before the orifice is cut;

,

And

are partial schematic front views (FIG. 2a) and along two section lines CC (FIG. 2b) and DD (FIG. 2c) of the panel of FIG. 1 after the orifice has been cut;

,

And

are partial schematic front views (FIG. 3a) and along two section lines EE (FIG. 3b) and FF (FIG. 3c) of a panel according to a second embodiment before the orifice is cut;

,

And

are partial schematic front views (FIG. 4a) and along two section lines GG (FIG. 4b) and HH (FIG. 4c) of the panel of FIG. 3 after the orifice has been cut.

With reference to the figures, a method for producing a motor vehicle floor panel 1 is described, said method comprising the following steps:

• provide a plate 2 having a back side 3 and a front side 4,
• make in said plate a plurality of pre-cuts 5 in the general form of a strip closing on itself, said strip having a plurality of recessed areas 6 separated by non-recessed areas 7, so that said pre-cut is split,
• placing said plate in a mold forming a molding cavity, said back face being pressed against the bottom of the mold, said cavity being arranged so as to define a molding space above said front face,
• filling said space with a precursor mixture of elastomeric polyurethane, so as to produce a protective layer 16 of elastomeric polyurethane overmolding said front face, said polyurethane also inserting itself into said recessed zones by overmolding said plate according to its thickness 8,
• after demoulding, make on at least part of said pre-cuts a cutout 9 – for example by laser or by blade – extending in the middle part of strip width 10 and closing on itself, so as to form at least one orifice 11 - in particular organ passage - the inner wall 12 of said orifice having reinforcing parts 13, located directly above said recessed areas, where the polyurethane extends along the entire thickness 14 of said panel, said reinforcing parts being separated from each other by junction portions 15 where the polyurethane extends only according to a fraction of the thickness of said panel.

According to one embodiment, the plate 2 is based on wood fibers bonded together by a bonding agent, for example based on urea-formaldehyde resin.

According to the first embodiment of Figures 1 and 2, the polyurethane does not extend, in an orifice 11, along the thickness 8 of the plate 2 in the junction part 15.

According to the second embodiment of FIGS. 3 and 4, the method further comprises, before placing the plate 2 in the mould, an additional machining step opposite place 4 in the non-recessed zones 7 so as to reduce their thickness, so that, in an orifice 11, the polyurethane extends according to the thickness machined in the junction parts 15.

It should also be noted that the machining can allow, due to the roughness provided, a better grip of the protective layer 16, in particular when the plate 2 is based on wood fibers.

According to one embodiment, the molding cavity is arranged so that the protective layer 16 generally has a thickness of less than 4 mm.

According to an embodiment not shown, the polyurethane can overflow around the periphery of the recessed zones 6 opposite the back 3, so as to reinforce the anchoring of the protective layer 16 on the plate 2.

Finally, a panel 1 made by such a process is described, said panel comprising a plate 2 whose front face 4 is overmolded by a protective layer 16 of elastomeric polyurethane, said panel further comprising at least one orifice 11 made by cutting in said panel, the inner wall 12 of said orifice having reinforcing parts 13 where the polyurethane extends along the entire thickness 14 of said panel, said reinforcing parts being separated from each other by junction parts 15 where the polyurethane extends only along a fraction of the thickness 14 of said panel.

As mentioned above, the panel 1 may have pre-cuts 5 that have not been cut 9, the area of said panel where said pre-cut is located having a significant resistance to depression due to the existence of a plate part 2 inside said pre-cut, said part being attached to the rest of said plate by the non-recessed areas 7.

Claims (6)

Method for producing a motor vehicle floor panel (1), said method comprising the following steps:

• provide a plate (2) having a reverse side (3) and a front side (4),
• making in said plate a plurality of pre-cuts (5) in the general form of a strip closing on itself, said strip having a plurality of recessed areas (6) separated by non-recessed areas (7), so that said pre-cut is split,
• placing said plate in a mold forming a molding cavity, said back face being pressed against the bottom of the mold, said cavity being arranged so as to define a molding space above said front face,
• filling said space with a precursor mixture of elastomeric polyurethane, so as to produce a protective layer (16) of elastomeric polyurethane overmolding said front face, said polyurethane also being inserted into said recessed zones by overmolding said plate according to its thickness (8),
• after demoulding, making on at least part of said pre-cuts a cutout (9) extending in the middle part of the width (10) of the strip and closing on itself, so as to form at least one orifice (11), the internal wall (12) of said orifice having reinforcing parts (13), located directly above said recessed zones, where the polyurethane extends along the entire thickness (14) of said panel, said reinforcing parts being separated from each other others by joining parts (15) where the polyurethane extends only according to a fraction of the thickness of said panel.

Method according to Claim 1, characterized in that the plate (2) is based on wood fibers bonded together by a bonding agent. Method according to one of Claims 1 or 2, characterized in that the polyurethane does not extend into an orifice (11) according to the thickness (8) of the plate (2) in the junction part (15). Method according to one of Claims 1 or 2, characterized in that it further comprises, before the positioning of the plate (2) in the mould, an additional step of machining in front of the place (4) in the non-recessed areas (7) so as to reduce their thickness, so that, in an orifice (11), the polyurethane extends according to the thickness machined in the junction parts (15). Method according to any one of the preceding claims, characterized in that the molding cavity is arranged so that the protective layer (16) generally has a thickness of less than 4 mm. Panel (1) produced by a method according to any one of the preceding claims, said panel comprising a plate (2) whose front face (4) is overmoulded by a protective layer (16) of elastomeric polyurethane, said panel further comprising at least one orifice (11) made by cutting in said panel, the internal wall (12) of said orifice having reinforcing parts (13) where the polyurethane extends along the entire thickness (14) of said panel, said reinforcing parts being separated from each other by junction parts (15) where the polyurethane extends only according to a fraction of the thickness (14) of said panel.