EP0443278A1 - Method of manufacturing a metallic framework for sections made of a synthetic resilient material - Google Patents

Abstract

A mild-steel strip is first of all cut up transversely so as to define contiguous lamellae (1) which are separated from each other perpendicularly to the axis of symmetry of the strip. Next the latter is flattened and then subjected to longitudinal stretching followed by work hardening. The strip thus treated may be used as reinforcement for a section made from elastomer. <IMAGE>

Description

The present invention relates to a method of manufacturing a metal frame for profiles in a resilient synthetic material, for example an elastomer or plastomer.

It is known that, in the automobile industry, sealing elements are used on a very large scale comprising a clamp part which covers a flange or a rebate of the bodywork, and a sealing member integral with the forming part. pliers. It can also be used alone, to protect rebates or as an element of embellishment. This clamp can also serve as a support for a body with a distinctly attractive appearance.

In all cases, this clamp usually has a U-shaped cross section and it has a metal frame, generally made of steel or aluminum, onto which a polymer such as plasticized polyvinyl chloride or vulcanized rubber has been extruded.

Lips of this polymer protrude on the internal faces of the branches of the U in the direction of the opposite branch, in order to ensure the attachment of the clamp on the flange or on the rebate of which it is integral.

It is this type of reinforced profiles that the present invention is interested in and it aims to propose a frame which is able to make the part flexible and which has a spring effect with respect to its support, due to 'appropriate work hardening of this reinforcement.

• dans une première phase, ou phase de découpe - emboutissage, on pratique dans une bande en acier doux des découpes perpendiculaires à son axe longitudinal pour y définir des lamelles identiques, attenantes deux à deux, alternativement en un emplacement disposé suivant l'axe longitudinal de la bande et en deux emplacements disposés symétriquement par rapport à cet axe suivant deux droites parallèles à celui-ci, en écartant simultanément les unes des autres, au moment de la découpe, dans un plan perpendiculaire à l'axe, d'une part, au niveau de cet axe, les parties des lamelles contiguës non solidaires les unes des autres suivant cet axe et les extrémités de ces lamelles, et, d'autre part, au niveau des droites parallèles à cet axe, les parties des lamelles contiguës non solidaires les unes des autres à ce niveau, en laissant sensiblement contiguës les extrémités latérales de ces lamelles;
• dans une seconde phase, ou phase de redressage, on aplatit la bande obtenue à l'issue de la première phase pour amener sensiblement bord à bord et dans un même plan les lamelles attenantes prédécoupées dans la première phase;
• dans une troisième phase, on étire longitudinalement la bande obtenue à l'issue de la seconde phase, de manière à écarter les unes des autres les parties non attenantes des languettes contiguës, de façon qu'elles forment dans la partie centrale de la bande des parallélogrammes sensiblement réguliers;
• enfin, dans une quatrième phase, qui suit immédiatement la troisième phase ou qui est conduite simultanément avec celle-ci, on écrouit la bande étirée obtenue à l'issue de la troisième phase, par compression suivant toute sa surface.

To this end, the subject of the present invention is a method of manufacturing a frame for profiles made of a resilient synthetic material, characterized by the following successive phases:

• in a first phase, or cutting - stamping phase, cuts are made perpendicular to its longitudinal axis in a mild steel strip to define identical lamellae, adjoining two by two, alternately at a location arranged along the axis longitudinal of the strip and in two locations arranged symmetrically with respect to this axis along two straight lines parallel thereto, simultaneously separating from each other, at the time of cutting, in a plane perpendicular to the axis, by on the one hand, at the level of this axis, the parts of the contiguous lamellae which are not integral with each other along this axis and the ends of these lamellae, and, on the other hand, at the level of the lines parallel to this axis, the parts of the contiguous lamellae not integral with each other at this level, leaving the lateral ends of these strips substantially contiguous;
• in a second phase, or straightening phase, the strip obtained at the end of the first phase is flattened so as to bring substantially adjoining edges and in the same plane the adjoining lamellae precut in the first phase;
• in a third phase, the strip obtained at the end of the second phase is stretched longitudinally, so as to separate from one another the non-adjoining parts of the adjoining tongues, so that they form in the central part of the strip substantially regular parallelograms;
• finally, in a fourth phase, which immediately follows the third phase or which is carried out simultaneously with the latter, the stretched strip obtained by the third phase is hardened by compression along its entire surface.

Advantageously, in a fifth phase, the strip is subjected to an additional work hardening operation, by compressing more significantly, following at least two parallel ribbons arranged symmetrically with respect to the longitudinal axis, the lateral parts extending the contiguous parallelograms. formed of lamellae.

The strips obtained by this process, the profile reinforcements produced from these bands, in particular the reinforcements with U-section, and the profiles made of material. synthetic resilient fitted with such a frame embedded at least partially in the elastomer constitute other objects of the invention.

The first phase of cutting and stamping the strip can be carried out easily by devices that are usual in the art.

To flatten, during the second phase, the deformed strip obtained at the end of the first phase, a train of flattening rollers will be used, without however exerting excessive compression.

The third phase, or stretching phase, could lead to a very significant elongation of the strip, of the order of 45%.

The final work hardening phase can finally be carried out using a train of rollers compressing the strip along its entire surface. This work hardening could lead to a reduction in the thickness of the strip of the order of 25%.

Finally, additional work hardening can be exerted on the edges of the strips using rollers arranged in parallel along at least two parallel strips of the strip, symmetrically with respect to the axis of symmetry thereof.

As indicated, it is possible to produce from a strip thus treated an armature with a U-section and an elastomer profile in which is embedded at least part of this armature, which have great flexibility and which exert a significant clamping force on the flanges or rebates they are required to equip, by a marked spring effect of the two branches of the U.

It will also be noted that the reinforcement thus produced allows, for equal performance, to achieve a serious saving of metal, since the elongation phase combined with the hardening phase results in a gain of metal which can reach 50% per unit. length.

Various documents of the prior art describe metallic reinforcements relatively close to those of the invention, or prepared by methods approaching that of the application. However, they differ significantly from those of the present application.

This is how DE-A 2 801 082 relates to a metal frame made up of adjoining strips 16 along two lateral bands arranged symmetrically, and therefore very different from that on request. In addition, its slats are first deformed like louvers (see Figure 1) before being flattened, and there is no mention of stretching phase.

Likewise, GB-A-2067 105 describes an armature of equally different shape and there is no stretching phase proper, the stretching resulting from the passage between rollers 5 a -5 b of a particular type (see figures 8 and 9). There is also no deformation of the slats and straightening thereof.

Finally, in EP-AO 277 425, the shape of the reinforcement described is also different and it is produced by a process which does not include phases of deformation of the tongues, of straightening of the latter and of work hardening of the strip stretched.

• La figure 1a est une vue en perspective de la bande de métal à l'issue de la première phase de découpe-emboutissage du procédé conforme à l'invention;
• La figure 1b est une vue latérale suivant la flèche F₁ de la figure 1a;
• La figure 1c est une vue de bout de la bande suivant la flèche F₂ de la figure 1a;
• La figure 1d est une vue de bout de la bande suivant la flèche F₃ de la figure 1a;
• Les figures 2a et 2b sont des vues de la bande analogues aux figures 1a et 1b, à l' issue de la seconde phase du procédé ou phase d'aplatissement de la bande;
• Les figures 3a et 3b sont des vues de la bande analogues aux figures 1a et 1b, à l'issue de la dernière phase du procédé, après étirage et écrouissage de la bande.
• La figure 4 est une vue en perspective, avec arrachement partiel, d'un profilé en élastomère équipé d'une armature métallique réalisée par un procédé selon l'invention.

The accompanying drawings, which are not limiting, will better highlight these differences and illustrate the various process phases according to the invention.
In these drawings:

• FIG 1a is a perspective view of the metal strip after the first phase of cutting and stamping the process according to the invention;
• Figure 1b is a F₁ along arrow side view of Fig 1a;
• Figure 1 c is an end view of the strip along the arrow F₂ of Figure 1 a ;
• Figure 1 d is an end view of the strip along the arrow F₃ of Figure 1 a ;
• Figures 2 a and 2 b are the views of the analogous band in Figures 1a and 1b, at the end of the second process phase or flattening phase of the strip;
• Figures 3 and 3b are views similar to the strip to Figures 1a and 1b, after the last process step, after drawing and work-hardening of the strip.
• Figure 4 is a perspective view, partially broken away, of an elastomer profile equipped with a metal frame produced by a method according to the invention.

Reference will first be made to FIGS. 1 a , 1 b and 1 c of the drawings, which show the profile produced, by simultaneous cutting and stamping, from a continuous rectilinear metal strip, not shown.

The starting strip is made of mild steel, cold rolled, the breaking strength of which is around 520 ± 40 megapascals.

This strip is cut, perpendicular to its longitudinal axis of symmetry II, so as to define there lamellae 1, perpendicular to the axis of symmetry II of the strip and adjoining two by two to the adjoining lamellae, alternately at a connection point 2 arranged along axis II, and along two points 3, arranged symmetrically along lines II-II parallel to the axis of symmetry II, near the lateral edge of the strip.

Simultaneously, the adjoining lamellae 1 are separated from each other, on either side of the plane of origin of the strip, on the one hand, at the level of axis II and, in the opposite direction, at their level. lateral edge, for the lamellae joined in locations 3 (Figure 1 c ), and, on the other hand, at the lines II-II, leaving the lateral edges contiguous substantially in the original plane, for the lamellae joined to the locations 2 (Figure 1 d ).

The deformed strip resulting from this first operation is then flattened using a train of rollers, in order to obtain the profile illustrated by FIGS. 2 a and 2 b , where it can be seen that the strips 1 joined at locations 3 define in the central part of the strip of substantially regular parallelograms, which extend laterally by ends of divergent branches.

The first two operations result in a slight work hardening of the metal strip.

It is then stretched and compressed either simultaneously or in two closely spaced phases, to obtain the profile shown in Figures 3 a and 3 b. As indicated above, this operation results in a marked work hardening of the metal and in a significant elongation of the strip, at the same time as by a reduction in its thickness. The compression operation is carried out along the entire surface of the strip and is preferably followed by additional work hardening, along at least two strips 6 arranged symmetrically with respect to the axis of symmetry of the strip, on the parts of the strips 1 laterally extending the parallelograms, at locations 3.

The metal strip thus treated can then be folded back to form a frame 4 of U-section, as shown in FIG. 4, which is sheathed by extrusion of a layer 5 of an elastomer to produce a profile forming a clamp, suitable for example to cover a flange of an automobile body, which differs from the usual profiles by increased flexibility and a large return force in position on a support. In FIG. 4, a distinction is made between the locations 3 where the strip has undergone additional work hardening laterally along two parallel strips arranged symmetrically with respect to its axis.

All the operations mentioned above are usual operations in the art, achievable with conventional tools, and which therefore make it possible to obtain, without appreciable increase in cost, a profile reinforcement having technical characteristics superior to those of the known technique, saving metal up to at least 50%.

Claims (7)

Method of manufacturing a reinforcement for profiles in a resilient synthetic material, characterized by the following successive phases: - in a first phase, or cutting-stamping phase, cuts are made perpendicular to its longitudinal axis in a mild steel strip to define identical lamellae (1), adjoining two by two, alternately at a location (2) arranged along the longitudinal axis (II) of the strip and in two locations (3) arranged symmetrically with respect to this axis along two straight lines (II-II) parallel to the latter, simultaneously separating each other, at the time of the cut, in a plane perpendicular to the axis (II), on the one hand, at the level of this axis, the parts of the contiguous lamellae which are not integral with each other along this axis and the ends of these lamellae and, d on the other hand, at the straight lines (II-II) parallel to this axis, the parts of the contiguous lamellae which are not integral with each other at this level, leaving the lateral ends of these lamellae substantially contiguous; - In a second phase, or straightening phase, the strip obtained at the end of the first phase is flattened so as to bring substantially adjoining edges and in the same plane the adjoining strips (1) precut in the first phase; - in a third phase, the strip obtained longitudinally is stretched at the end of the second phase, so as to separate from one another the non-adjoining parts of the contiguous tabs, so that they form in the central part of the strip substantially regular parallelograms; - Finally, in a fourth phase, which immediately follows the third phase or which is carried out simultaneously with the latter, the stretched strip obtained by the third phase is hardened by compression along its entire surface. Method according to claim 1, characterized in that the stretching phase of the strip leads to an elongation of the latter of the order of at least 45%. Method according to one of claims 1 and 2, characterized in that the work hardening phase of the strip results in a reduction in the thickness thereof of the order of at least 25%. Method according to one of claims 1 to 3, characterized in that, in a fifth phase, the strip is subjected to an additional work hardening operation, by compressing more significantly, following at least two parallel ribbons (6) arranged symmetrically with respect to the longitudinal axis (II), the lateral parts extending the contiguous parallelograms formed by the lamellae (1). Metal strip produced by a method according to one of claims 1 to 4. Metal reinforcement (4), in particular reinforcement with a U-shaped cross section, for a profile in a resilient synthetic material, produced from a strip according to claim 5. Reinforced profile in a resilient synthetic material (5) comprising a frame (4) according to claim 6, at least partially embedded in said material.

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