FR2825945A1 - Manufacture of joint molding with flock sealing against sliding vehicle windows, places sliding film in mold, closes it and injects elastomer - Google Patents

Abstract

Manufacture of joint molding with flock sealing comprises deposition of sliding film is at least one location, within an injection mold. The mold is closed. Elastomer is injected. An Independent claim is included for the corresponding mold, which has a moving core with a surface capable of receiving the flocked film. A sealed joint is also claimed, which includes the co-molded sliding film. No metallic insert is included.

Description

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 PROCESS OF MANUFACTURING BY MOLDING A FLOCKED ELASTOMER SEAL.

 The present invention relates to the field of seals, in particular to seals intended for the automobile, for connection with sliding windows for example.

 Such seals are formed by an extruded elastomer part coated with a flocking allowing the sliding of the glass. US patent US05414961 describes an example of a window wiper. The US patent US04416951 describes another example of a seal comprising a glued flocking zone.

 US Patent US03881980 describes a method of manufacturing by extrusion of seals having a non-abrasive surface, coated with flocking fibers.

 In the closest prior art, such parts are produced by extruding a profile comprising a metal frame.

 FIG. 1 represents an example of a seal produced according to the prior art. It comprises a metallic core (100), generally made of alumunium, overmolded with an elastomer or rubber (101). This element being manufactured by extrusion, the section is necessarily constant, and the protruding parts (102) consist of separate parts, overmolded or assembled by gluing or welding. A flocked film (103) is bonded to the surface of this part. Optionally, the part is flocked online by spraying glue and flock. Lugs (105) are placed in the holes (104) of the part.

 The realization of such a seal requires many interventions, which increases the manufacturing cost. Furthermore, the extrusion manufacturing process is ill-suited to the production of curved joints,

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 corresponding to a growing demand in the automobile industry where the tendency is to use more elaborate forms than in the past. The metal insert has certainly made it possible to manufacture curved parts, a seal according to the state of the art made only of rubber which does not allow the curvature to be preserved.

 These finishing operations by bending the profile, cutting and overmolding the ends entail a high cost resulting from this succession of operations, and the difficulty of producing parts of complex shapes by extrusion techniques.

 The invention aims to remedy these drawbacks by proposing a solution making it possible to produce parts of complex shape, by a single injection cycle, with a reduced cost compared to the solutions of the prior art.

 To this end, the invention relates, according to its most general meaning, to a method of manufacturing by molding a seal made of Thermoplastic or Elastomer-Thermoplastic at least partially coated with a flocked zone characterized in that one deposits in part of an injection mold at least one sliding film, and in that one then proceeds to close the mold and inject the elastomer into said mold.

 Advantageously, the sliding film is applied to the surface of a movable core held back during the elastomer injection phase, then moved into the injection chamber after injection of the elastomer.

 According to a variant, the sliding film is applied to the surface of a first part of a mold, this first part then being partially brought closer to a complementary part, the process consisting in injecting a dose of thermoplastic material into the chamber formed by the two parts partially close together, then to continue the

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 bringing together the two parts of the mold to compress the substrate of the film flocked on the injected material.

 According to a particular mode of implementation, at least two successive injections of different thermoplastic materials are carried out in the same mold.

 According to another embodiment, a first injection of a flexible thermoplastic material such as thermoplastic-elastomer is carried out, and a second injection of a less flexible thermoplastic material such as compact or cellular TP.

 According to a variant, the thermoplastic material is foamed before injection.

 Advantageously, the sliding film is a flocked film having bristles of polyamide or polyester, said bristles being fixed on a hot-melt substrate.

 Alternatively, the sliding film is a plastic film.

 According to another variant, the sliding film is a film coated with Teflon.

 The invention also relates to a mold for implementing the method according to the invention, characterized in that it comprises at least one mobile core having a surface capable of receiving a flocked film.

 It also relates to a seal characterized in that it comprises a co-molded sliding film, and that it does not comprise a metallic insert.

1 à un exemple non limitatif de réalisation, où : - la figure 1 représente une vue d'un joint d'étanchéité selon l'état de la technique ; les figures 2 à 5 représentent les différents états du moule dans un premier exemple de réalisation ; The invention will be better understood on reading the description which follows, referring to the appended drawings relating to

1 to a nonlimiting exemplary embodiment, where: - Figure 1 shows a view of a seal according to the state of the art; Figures 2 to 5 show the different states of the mold in a first embodiment;

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 FIG. 6 represents a joint produced according to the method of the invention; Figures 7 to 11 show the different states of the mold in a second embodiment; Figures 12 to 16 show the different states of the mold in a third embodiment.

 Figure 1 shows a schematic view of a seal according to the prior art. It includes a metal insert (100) which maintains the curve of the part, the rubber having an elasticity which would not guarantee the desired curve.

 This insert (100) is overmolded with an elastomer (101) of which certain zones (103) are coated with a flocked film to facilitate the sliding of a surface in contact, in particular a window pane.

 The object of the invention is to produce a seal which does not require the presence of a metal insert.

 The method of manufacturing a seal according to the invention will be described with reference to the accompanying drawings, illustrating different variants of implementation.

 Figures 2 to 5 show a mold at the various stages of manufacturing a part according to a first variant of implementation of the invention.

 The mold consists of two complementary parts (10, 11), having a connection plane. One of the parts (11) has supply channels (12,13). The two parts of the mold define an injection chamber in a known manner.

 The first step of the process consists in depositing in the first part (10) of the mold a flocked film (14), the bristles being directed towards the surface of the mold. This film is deposited by an operator or by a handling device

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 automated. The film consists of a hot-melt substrate, for example polyester, on which are bonded bristles resistant to injection temperatures, for example bristles of polyester or polyamide.

 The mold is then closed by bringing the two parts (10, 11) together.

 The next step consists in injecting a thermoplastic or thermoplastic-elastomer (TPE) as shown in FIG. 4. The thermoplastic or TPE is determined to be compatible with the substrate of the flocked wire, and to form a homogeneous assembly after injection.

 The next step is to open the mold to remove a single piece of partially flocked elastomer (14).

The seal obtained is shown in Figure 6. It consists of a monolithic part having projecting parts (40), lights for the attachment of accessories, and a flocked surface (42)
Figures 7 to 11 show a particular variant implementation of the method.

 The mold consists of two connectable parts (10, 11) as before. The second part (11) has injection lights (12,13).

 The first part (10) has a movable core (21) movable between a position in which it is spaced from the injection volume, and a working position in which it is pushed towards the molding chamber.

 In the example described, it also includes a second movable core (25) intended to modify the shape of the injection chamber (23).

 This movable core has a surface intended to receive the flocked film (14). The displacement of the mobile core takes place in a direction substantially normal to the surface.

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 The first step is to deposit the flocked film (14) on the receiving surface of the movable core (21) (Figure 7).

 The two parts (10, 11) of the mold are then brought together to close the injection chamber (23). The two mobile cores (21,25) remain in the separated position (Fig. 8).

 The next step is to inject masses of elastomer and thermoplastic (26,27) through the injection channels. the two movable cores (21,25) are always in the separated position (Fig. 9). The injected volume is dosed, and does not fill the entire injection chamber.

 The next step is to introduce the movable cores (21 and 25) into the injection chamber.

 The movable core (21) advances the flocked wire until the substrate comes into contact with the injection mass. The movable core (21) provides controlled compression of the flocked film on the injection material and prevents degradation of the film by excessive pressures encountered during the injection phase.

 The second movable core (25) is also introduced into the injection chamber to form the lips of the seal.

 Figures 12 to 15 show another alternative embodiment.

 The mold has two complementary parts (10, 11). One of the parts has a surface (30) for receiving the flocked film (14).

 The two parts (10, 11) of the mold are initially only partially close together, to form a sealed injection chamber (31). (Figure 13).

 A metered quantity of hot-melt material (33) is then injected into the chamber thus formed (Figure 14).

 After the injection of the hot-melt material only, the two parts (10, 11) of the mold are completely

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 close together, to ensure compression of the flocked film and of the thermoplastic material (Figure 15).

 The pressure exerted on the two parts (10,11) to ensure total closure is less than the injection pressure, in order to avoid degrading the flocked surface.

 FIG. 16 represents a section view of a joint produced with such a mold. It consists of a support, the shape of which can be complex and of non-constant section, coated in certain places by a sliding surface, in the example described a flocked film.

Claims (11)

 CLAIMS 1-Method of manufacturing by molding a seal in Thermoplastic or Elastomer-Thermoplastic at least partially coated with a flocked zone characterized in that one deposits in a part of an injection mold at least a sliding film, and in that one then proceeds to closing the mold and injecting the elastomer into said mold.  2-A method of manufacturing by molding an elastomeric seal according to claim 1 characterized in that the sliding film is applied to the surface of a movable core kept in withdrawal during the elastomer injection phase, then moved into the injection chamber after injection of the elastomer.  3-A method of manufacturing by molding a TP and TPE seal according to claim 1 characterized in that the sliding film is applied to the surface of a first part of a mold, this first part then being brought together partially of a complementary part, the method consisting in injecting a dose of thermoplastic material in the chamber formed by the two partially joined parts, then in continuing the bringing together of the two parts of the mold to compress the substrate of the film flocked on the injected material.  4-A method of manufacturing by molding an elastomeric seal according to any one of the preceding claims characterized in that one proceeds to at least two successive injections of different thermoplastics in the same mold. <Desc / Clms Page number 9>  5-A method of manufacturing by molding an elastomeric seal according to claim 4 characterized in that one proceeds to a first injection of a flexible thermoplastic material such as thermoplastic-elastomer, and to a second injection a less flexible thermoplastic such as compact or cellular TP.  6-A method of manufacturing by molding an elastomeric seal according to any one of the preceding claims characterized in that the thermoplastic material is foamed before injection.  7-A method of manufacturing by molding an elastomeric seal according to any one of the preceding claims characterized in that the sliding film is a flocked film having bristles of polyamide or polyester, said bristles being fixed on a substrate melt.  8-A method of manufacturing by molding an elastomeric seal according to any one of the preceding claims characterized in that the sliding film is a plastic film.  9-A method of manufacturing by molding an elastomeric seal according to any one of the preceding claims characterized in that the sliding film is a film coated with Teflon.  10-Mold for implementing the method according to at least one of the preceding claims <Desc / Clms Page number 10>  characterized in that it comprises at least one movable core having a surface capable of receiving a flocked film.  11-Seal characterized in that it comprises a co-molded sliding film, and that it does not include a metallic insert.