FR2942423A1 - Trim cushioning forming method for seat element e.g. backrest, of motor vehicle, involves injecting polyurethane foam into casting mold, and closing casting mold during polymerization of polyurethane foam to form lower foam layer - Google Patents

Abstract

The method involves spraying polyurethane foam on a face of a flexible substrate, and introducing the substrate into a die of a press. A punch of the press is applied against the substrate during polymerization of the foam to form an upper foam layer (3) of cushioning (2). The foam layer is introduced into a casting mold, and another polyurethane foam is injected into the mold. The mold is closed during polymerization of the latter polyurethane foam to form a lower foam layer (4) of the cushioning. Self-gripping bands (6) are inserted into style return lines of grooves (36) in the die. An independent claim is also included for a cushioning of a trim of a seat element in a motor vehicle.

Description

B9211 - 2599 1.EN 1 MULTI-DENSITY CARTRIDGE FOR MOTOR VEHICLE SEAT

Field of the Invention The present invention relates generally to motor vehicle seats and, more particularly, to the provision of a seat member lining. The invention applies more particularly to the production of a seat or a backrest for a motor vehicle seat. BACKGROUND OF THE INVENTION Motor vehicle seat upholstery is generally in the form of a quilting coated with a cap. The padding is a block of foam, usually molded to the desired final shape for the seat member. This block is assembled to a frame of the seat and is covered with a textile cap (woven or not), skin or synthetic material. The flexibility of the cap allows it to adapt to the shape of the padding. Depending on the areas of the seat element (for example the medallion of a seat relative to the side rails), the foam constituting the padding may have different hardnesses in the surface of the seat element and / or in its thickness.

Most often, lines or patterns of return of form are provided in apparent face of the padding and are provided with self-gripping strips to hold the cap and B9211 - 2599 1.EN

2 make him marry the forms of padding. The style of return lines are obtained by grooves present in a pouring tank of the apparent face of the padding, these grooves receiving self-gripping strips whose pins are directed on the tank side. The foam then poured on the bowl fixed the self-gripping strips at the bottom of the throats of the padding. One difficulty lies in making curved style reminders, especially in three dimensions. The more complex the styling reminder is, the more likely it is that the pouring foam will get into the grooves and drown the pins of the Velcro strips. But, more and more, seat padding has complex shapes. Abstract It would be desirable to be able to modulate the hardness of a foam padding forming a seat element in the thickness of this element. In particular, it may be desirable to have a seat padding of which an upper layer (the first in contact with a user) is of lesser hardness than an underlying layer.

It would also be desirable for the realization of such padding to be compatible with style reminders of the cap. It would also be desirable to be able to combine different densities and / or hardnesses in the thickness of the padding and in different areas thereof at the surface. To achieve all or part of these objects as well as others, there is provided a method of making a padding of a lining of a seat element for a motor vehicle, comprising the steps of: forming a first layer cushioning by: spraying a first polyurethane foam on one side of a flexible substrate; B9211 - 2599 1.EN

3 introducing the assembly into a press, die-side foam, said die defining the shape of an apparent face of the liner; applying a punch of the press at least the polymerization time of the first foam; and forming a second layer of the padding by: introducing the first layer into a casting mold, foam side bottom of the mold; casting a second polyurethane foam into the mold; and closing the mold at least during the polymerization of the second foam. According to one embodiment of the present invention, the die has style return line defining grooves into which velcro strips are inserted. According to one embodiment of the present invention, the press of the first layer defines zones of different thicknesses according to the portions of the padding. There is also provided a padding for a seat element trim for a motor vehicle comprising: a first press-in layer defining the shape of at least one apparent face of the trim; and a second layer cast on the first. There is also provided a seal for a motor vehicle seat element, comprising such a padding. There is also provided a seat element for a motor vehicle comprising such a lining. There is also provided a car seat 30 comprising at least one such seat element. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features, and advantages will be set forth in detail in the following non-limiting, non-limiting description of particular embodiments in connection with the accompanying drawings in which: B9211-2599 1. EN

Figure 1 is a schematic view of a motor vehicle seat; Figure 2 is a perspective representation of a seat pad according to an embodiment of the present invention; Figure 3 is a schematic sectional view of an embodiment of a forming press in the open position of a first thickness of a padding; Figure 3A illustrates a prior step of forming the first thickness of the padding; Figure 3B illustrates a detail of Figure 3; Fig. 4 is a perspective view of an embodiment of a die of the press of Fig. 3; Fig. 5 is a schematic sectional view of the press of Fig. 3 in the closed position illustrating the making of a first thickness of a padding; Figure 6 is a sectional view of a first thickness of padding obtained by means of a press as illustrated in Figures 3 to 5; Figure 7 is a perspective view, partly in section, of the padding element of Figure 6; Figures 8, 9 and 10 are schematic sectional views illustrating the realization of a second thickness of the padding; and Fig. 11 is a perspective view partially in section of a seat medallion obtained. The same elements have been designated with the same references in the various figures. Detailed Description For the sake of clarity, only the steps and elements useful for understanding the invention are shown and will be described. In particular, the embodiment of the other parts of the seat has not been detailed, the invention being compatible with any conventional embodiment of a lining 35 attached to a frame. In addition, reference will be made to B9211 - 2599 1.EN

qualifiers upper, lower, internal, external, forward, back, etc. according to the seat member in the normal use position, and will be called "apparent" the faces intended to receive the user. Figure 1 is a schematic side view of a seat 1 for a motor vehicle. Such a seat comprises a seat 11 on which is articulated a backrest 12, usually surmounted by a headrest 13. The seat 11, the backrest 12 and the headrest 13 each comprise a lining attached to its frame , usually metallic. The frame 14 of the seat 11 can be connected to the floor 15 of the vehicle by a sliding mechanism. The seat 1 may also include one or more armrests (not shown). Figure 2 is a perspective view of a seat padding 2 of a seat for a motor vehicle. The padding defines a central portion 21 (medallion) framed by two side supports 22 and 23 generally thicker than the medallion, a front rim 24 also generally thicker, and a rear portion 25 most often hidden from below. backrest (12, figure 1) once the seat is assembled. Most often, style 26 reminder lines are defined in the padding, at least at the interfaces between the different parts. These lines of style recall are, in this example, equipped with self-gripping strips so as to hook the inner face of the cap later reported on the padding to form the complete liner. The padding is carried out so as to present, in this example over its entire surface, two layers of foam 3 and 4 having different densities and / or hardnesses. Such layers of different hardness can give an absorption effect when the user sits on the seat and thus improve comfort. An exemplary embodiment of such a padding will be described hereinafter.

B9211 - 2599 1.EN

Figures 3, 3A, 3B, 4, 5, 6 and 7 illustrate the production of a first upper layer 3 of the padding. FIGS. 3 and 5 are sectional views of a tool 5 (press), respectively in the open position and in the closed position, illustrating two steps of formation of the layer 3. FIG. 3A is a schematic section of a previous step 3. Figure 3B is a view of a detail of a die 52 of the press 5 of Figure 3. Figure 6 is a sectional view of the first layer or portion 3 of padding obtained. Figures 4 and 7 are perspective views respectively of the die 52 of the press 5 and the first layer 3 of the padding obtained. The die 52 defines the upper profile of the padding and is similar to a conventional forming die.

The definition of the style return lines 26 is obtained by grooves 526 of the die 52 in which are inserted velcro strips 6 (see the detail of Figure 3B), the pins of the strips being directed on the die side 52. The objective is to fix the self-gripping strips in the foam by their rear face without drowning the pins of these bands. According to the desired style reminders, the strips 6 are rectilinear or curved. FIG. 3A illustrates a first step in which a polyethylene substrate 55 is stretched over a support frame 57 and polyurethane foam 39 is sprayed to an approximately regular thickness with a sputtering tool 58 on one side of the Substrate 55. A known foam spraying process can be used on textile pieces (woven or not), skin or synthetic material. The substrate 55 is flexible and has a relatively small thickness (on the order of one-tenth of a millimeter) compared to the thickness (of the order of a centimeter or several centimeters) of the sprayed foam.

B9211 - 2599 1.EN

While the foam 39 is only partially polymerized and is therefore still sticky, it is attached to the die 52 of the press 5. As illustrated in FIGS. 3 and 4, the die 52 defines the relief of the apparent face. (upper face of the seat) of the padding 2 (Figure 2), so the shape of the apparent face of the pad. In the section of FIG. 3, there appear two cavities 522 and 523 for defining the lateral embossments 22 and 23 and a central recess 521 for defining the inset medallion 21. The grooves 526 for defining the stylus return lines 26 are prominent relative to the bottom of the areas 521, 525, 523 and 524 defining the different portions of the seat. If necessary, a chemical release agent is used.

Once the substrate 55 carrying the foam during polymerization 31 is set up, foam against matrix 52, a punch 56 of the press 5 is applied against the substrate 55. The face of the punch in contact with the substrate is approximately against the form of the matrix 52. Most often, it is a heating press (heating resistors 54). In the example shown, the layer 3 is provided to have a lesser thickness in the parts 32 and 33 (Figure 6) corresponding to the lateral overlays in the portion 31 corresponding to the medallion. As best shown in Figure 5 showing the press in the forming position, the gaps between the inner face of the punch 56 and that of the die 52 are different in different areas of the seat. As shown in FIG. 7, once demolded, the layer 3 of padding obtained has, in apparent face, grooves 36 at the bottom of which are embedded self-gripping strips 6 to define the return lines of style 26. As a of particular embodiment, the press 5 is closed for a duration of a few tens of seconds (for example, of the order of 20 to 40 seconds) after the B9211 - 2599 1.EN

Spraying of the foam on the film 55. The press remains closed the time necessary for the polymerization of the foam (for example, of the order of 40 to 90 seconds) after its closure. The closure of the press while the foam 31 is not yet polymerized allows the strips 6 to be fastened while preventing the foam from filling their pimpled faces, insofar as the foam is not completely liquid when go to press. Figures 8 to 11 illustrate the formation of the lower layer 4 of the seat of Figure 2. Figures 8 to 10 are sectional views illustrating three stages of the manufacturing process in a casting mold. Figure 11 is a perspective view partially in section of the quilting 2 obtained. The first layer 3 resulting from the preceding steps is placed at the bottom of a casting mold 7 whose bottom of the tank 72 coarsely reproduces the matrix 52. In particular, the bottom of the tank 72 preferably reproduces the general shapes of the face Apparent cushioning to preserve the shape of the layer 3 obtained by the previous treatment. However, it is not necessary to reproduce all the details to the extent that the shape of the apparent face of the padding is derived from the previous steps. The tank 72 of the casting mold may thus be coarser than the matrix 52. Where appropriate, this may make it possible to use the same casting mold for padding having first layers defining different apparent faces. In the example described, the layer 4 is thicker than the layer 3 and the tank 72 also defines the lateral faces of the padding. In a variant, the layer 3 defines all or part of these lateral faces. The tank 72 does not include grooves (526, Figure 3A) for receiving the self-gripping strips 6, and instead comprises flat surfaces. If necessary and as shown, these surfaces are nevertheless overhanging (in the orientation of the casting mold) to preserve the grooves 36 of the layer 3.

B9211 - 2599 1.EN

A polyurethane foam 49 is poured into the tank 72 (FIG. 8) on the rear face (not intended to be visible) of the layer 3 by one or more mobile casting heads 74. Where appropriate and as illustrated by FIG. FIG. 9, foams of different densities or natures can be cast according to the zones of the seat (for example a harder foam at zones 42 and 43 defining the lateral rovings with respect to an area 41 defining the medallion of seated). A foaming mold cover 76 is brought back over the tank 72 (FIG. 9). This cover 76 has vent openings 762 allowing the evacuation of air during the polymerization of the foam. As can be seen in FIGS. 10 and 11, foams of different densities are finally obtained according to the regions of the seat, not only in the surface of the padding, but also in its thickness. FIG. 11 illustrates, in dotted lines, a variant according to which a heating sheet 80 is integrated in the first layer 3 of the padding. It then takes advantage of stickiness of the foam used in the pressing step which is expected the beginning of polymerization before applying it against the matrix 52. The sheet 80 is either prepositioned on the matrix, or inserted into the foam ( 39, Figure 3) partially polymerized.

Alternatively, an occupant presence detector is integrated (in addition to or instead of the web 80) in the layer 3. Once the padding is completed, it is wrapped in a cap in the usual way.

An advantage of the present invention is that it allows the realization of a seat element padding for a multi-hardness or multi-density motor vehicle. In particular, the two-step production of the layer comprising the visible face and the lower (generally thicker) layer makes it possible to use foams B9211 - 2599 1.FR

10 different. This advantage is of particular interest for padding removable cap. One can then use for the first layer a foam conferring on the visible face sufficient strength, without having to use this foam generally more expensive for the entire thickness. Another advantage is that it is easy to incorporate Velcro strips curved shape through the partial polymerization of the spray foam before its introduction into the press. This advantage is particularly advantageous in the case of curved lines in three dimensions, for example the lines between the frontal rim and the inset medallion and between this medallion and the side supports. Another advantage is that the invention is compatible with the use of conventional pouring molds, in which a first layer of foam from the press 5 is introduced, the tank of the casting mold being, if necessary, without grooves. reception of Velcro strips. Various embodiments with various variants have been described. It will be appreciated that those skilled in the art may combine various elements of these various embodiments and variants without demonstrating inventive step. In particular, the choice of press and polymerization times depends on the nature of the foam used and is within the reach of the skilled person. In addition, the distribution between the thickness conferred to the different portions of the padding may vary according to seat ranges and hardnesses chosen.

Claims (8)

REVENDICATIONS1. A method of producing a padding (2) of a lining of a seat element (11, 12, 13) for a motor vehicle, characterized in that it comprises the steps of: forming a first layer (3 ) padding by: spraying a first polyurethane foam (39) on one side of a flexible substrate (55); introducing the assembly into a press (5), die-side foam (52), said die defining the shape of an apparent face of the pad; and applying a punch of the press at least the polymerization time of the first foam; and forming a second layer (4) of the padding by: introducing the first layer into a casting mold, foam side bottom of the mold; pouring a second polyurethane foam into the mold; and closing the mold at least during the polymerization of the second foam (49). 2. Method according to claim 1, wherein the matrix (52) comprises grooves (526) for defining styling return lines (26) into which are inserted velcro strips (6). 25 3. Method according to claim 1 or 2, wherein the press (5) of the first layer (3) defines zones of different thicknesses according to the portions of the padding. 4. Quilting (2) for motor vehicle seat element packing (11, 12, 13), characterized in that it comprises: a first press-in layer (3) defining the shape of at least one apparent face of the trim; and a second layer (4) cast on the first one.B9211 - 2599 1.EN 12 5. The padding according to claim 4, obtained by the method according to any one of claims 1 to 3. 6. Garniture for a motor vehicle seat element, characterized in that it comprises a padding (2) according to claim 4 or 5, coated with a cap. 7. Seat element for a motor vehicle, comprising a gasket according to claim 6. 8. Seat for a motor vehicle, comprising at least one seat element according to claim 7.