FR2862560A1 - Motor vehicle interior trim component covering layer shaping procedure uses mould with base and closing member forming cavity in which covering layer is formed - Google Patents

Abstract

The procedure, which includes inserting the covering layer (11) in a mould (33) and pressing it against the inner surface by evacuating the gas, consists of using a mould with a base (39) and a peripheral closing member (41) that form a cavity (71) with a draft region. The closing member of the mould has a central surface (61) facing the mould's central axis (Y - Y') against which the covering layer is pressed. It is moved into its closed position along the axis, and before the shaped covering layer is extracted from the mould the closing member is removed.

Description

The present invention relates to a method of forming a skin

  for wrapping a piece of interior equipment of a motor vehicle, comprising the steps of:

  - insertion of the skin into a mold; - Plating the skin against a wall of the mold by evacuation of the gas present between the skin and the wall of the mold through the wall of the mold; - Removal of the skin from the mold.

  EP 0 477 476 discloses a process of the aforementioned type, in which an outer covering skin is applied against the microporous textured wall of a mold by suction through this wall, so as to form on this skin a face of textured appearance.

  Some automotive interior equipment parts, however, have complex shapes including peripheral parts undercut. The forming of an outer covering skin for this type of part requires a mold having an undercut cavity.

  A method of the aforementioned type does not give complete satisfaction to form this type of parts. Indeed, the withdrawal of the skin from the mold, especially in the undercut portion, is difficult to achieve without damaging the skin.

  An object of the invention is therefore to provide a method of forming a covering skin of a motor vehicle part in a porous mold comprising an undercut portion, in which the removal of the skin from the mold is ease.

  For this purpose, the subject of the invention is a process of the aforementioned type, characterized in that the mold comprises a bottom portion and a peripheral closure portion and continuous around its periphery around a central axis, the bottom portions and closure device defining a cavity which has an undercut region, and in that the method comprises, before the withdrawal step, at least one step of opening the mold by relative movement of the closure part relative to the bottom portion along said central axis.

  The method according to the invention may comprise one or more of the following characteristics, taken alone or in any technically possible combination: the closure part has a central surface extending opposite said central axis substantially completely parallel to said central axis; convergently towards said central axis towards the outside of the mold; the closing part is movable in relative translation with respect to the bottom part along said central axis, between a closed position of the mold, in which the bottom and bottom parts are in contact along a contact surface, and an opening position of the mold, wherein the bottom and bottom portions are spaced, and in the vicinity of the undercut cavity, the contact surface extends substantially perpendicular to said central axis; the insertion step comprises the phases of: placing the peripheral part of the skin on an outer face of the closure part; and inserting the central portion of the skin into the undercut cavity; and it comprises, before the opening step, a step of cutting the peripheral portion of the skin bearing on said upper face; and the surface of the walls which delimit the undercut cavity is at least partially textured.

  The subject of the invention is also a mold for forming a skin for covering a piece of interior equipment of a motor vehicle, of the type comprising: means for inserting the skin into the mold; means for plating the skin against a wall of the mold by evacuating the gas present between the skin and the wall of the mold through the wall of the mold; means for removing the skin from the mold; characterized in that the mold comprises - a bottom portion and a peripheral closure portion and continuous on its periphery about a central axis, the bottom and closure portions defining a cavity which has an undercut region; and - means for opening the mold by relative movement of the closure part relative to the bottom portion along said central axis.

  The mold according to the invention may comprise one or more of the following characteristics, taken alone or in any technically possible combination: the closing part has a central surface extending in front of said central axis substantially completely parallel to said central axis or convergently towards said central axis towards the outside of the mold; the closing part is movable in relative translation with respect to the bottom portion along said central axis, between a closed position of the mold, in which the bottom and bottom parts are in contact along a contact surface, and a mold opening position, in which the bottom and bottom portions are spaced, and in the vicinity of the undercut cavity, the contact surface extends substantially perpendicular to said central axis; and the surface of the walls which delimit the undercut cavity is at least partially textured.

  The subject of the invention is furthermore a covering skin of a piece of interior equipment of a motor vehicle, characterized in that it comprises an undercut part having a textured appearance face, said part having a single peripheral seal plane on said outer face.

  An exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which: - Figure 1 is a sectional view, taken along a median plane, of a covering skin according to the invention when removing it from a forming mold; - Figure 2 is a view similar to Figure 1, in a first step of a forming method according to the invention; - Figure 3 is a view similar to Figure 2, in a second step of the method; - Figure 4 is a view similar to Figure 2, in a third step of the method; - Figure 5 is a view similar to Figure 2, in a fourth step of the method; and - Figure 6 is a view similar to Figure 2, in a fifth process step.

  A covering skin 11 according to the invention is shown with reference to Figure 1. The forming of this skin 11 is carried out by a method according to the invention in the device 13 shown in Figures 1 to 6.

  The skin 11 is intended to dress a piece of motor vehicle equipment that has a peripheral undercut portion, for example a pocket of storage pockets.

  As illustrated in Figure 1, the skin 11 has a bottom wall 15 and a side wall 17 comprising a peripheral portion 19 in reverse.

  The skin 11 is made for example of a multilayer thermoplastic material, comprising for example an outer layer of thermoplastic polyolefin (TPO) appearance and an inner layer of polypropylene foam (PP).

  The thickness of the skin 11 is between 0.7 mm and 4 mm.

  As illustrated in FIG. 1, the side wall 17 extends continuously around a central axis XX 'substantially orthogonal to the bottom wall 15. The undercut portion 19 also extends continuously around the X-X 'axis.

  The bottom wall 15 and the undercut portion 19 have a textured appearance outer face 21 comprising surface asperities, including a plurality of depressions and bumps. The depth of the recesses is, for example, between 0.2 mm and 1.0 mm.

  The forming device 13 of the skin 11 comprises heating means 31 shown in FIG. 2, a forming mold 33 shown in FIGS. 2 to 5, means 35 for inserting the skin 11 into the mold 33 shown in FIGS. 3 and 4, and means 37 for cutting the skin 11 shown in FIG. 5.

  With reference to FIG. 2, the heating means 31 comprise, for example, an infra-red radiation source or a heating plate intended to bring the skin 11 to a softening temperature of, for example, between 150 ° C. and 200 ° C.

  The forming mold 33 comprises a lower shell 39, an upper shell 41 and suction means 43.

  The lower shell 39 is microporous and comprises a bottom wall 45 which defines a bottom cavity delimited by an inner face 47. The inner face 47 extends continuously around a vertical central axis Y-Y 'of the mold 33.

  This inner face 47 has a texture of shape conjugated to the texture of the external face of appearance 21 of the skin 11 after forming.

  This face 47 is for example made by assembling micrometallic particles.

  The lower shell 39 also has a peripheral edge 49 for receiving the upper shell 41. This edge 49 comprises an inner peripheral surface 51 adjacent to the inner face 47 and extending substantially in a plane perpendicular to a central axis YY ' of the mold 33. The edge 49 further comprises an outer peripheral surface 53 flared opening facing the upper shell 41, upwards in Figure 2.

  The upper shell 41, also microporous, comprises a peripheral wall 55 delimiting a central opening 57. The wall 55 has a lower edge 59 of shape conjugated to the peripheral edge 49 of the lower shell 39.

  The wall 55 further has a central inner surface 61 which extends continuously around the central axis YY ', opposite this axis Y3o Y'.

  As illustrated in Figure 2, this central face 61 comprises a lower peripheral region 63, converging towards the central axis YY 'outside the mold 33, upwards in the Figure. This lower region 63 has a texture similar to the inner face 47 of the lower shell 39.

  The central surface 61 further comprises an upper region 65 which extends substantially parallel to the central axis YY '. This region 65 is devoid of surface roughness.

  The upper shell 41 is movable in translation along the central axis Y-Y 'between a closed position of the mold 33 shown in Figure 2, and an open position of the mold 33 shown in Figure 6.

  In the closed position of the mold 33, the lower edge 59 of the upper shell 41 rests on the peripheral edge 49 of the lower shell 39. The inner faces 47, 61 of the shells 39, 41 define a forming cavity 71 of the skin 11. The forming cavity 71 comprises an undercut peripheral region 73 which extends around the central axis Y-Y 'delimited by the lower region 63 and the region 75 opposite the internal face 47. .

  In the closed position of the mold 33, the end 76 of the inner surface 51 adjacent to the inner face 47 is also adjacent to the lower region 63, and defines a peripheral seal plane of the forming cavity 71.

  In the open position of the mold 33, the upper shell 41 is spaced from the lower shell 39.

  Furthermore, the flared surface 53 of the edge 49 of the lower shell 39 facilitates the positioning of the upper shell 41 with respect to the lower shell 39 during closure of the mold 33.

  The suction means 43 comprise a vacuum pump 81 comprising a suction inlet 83 connected to each of the lower and upper microporous shells 39 and 41. When the pump 81 is activated, the gas present in the forming cavity 71 is therefore sucked by the vacuum pump 81 through the walls 45, 55 of the mold 33.

  The insertion means 35 of the skin 11 in the mold 33, shown in FIG. 3, comprise a punch 85 whose cross section, taken along a plane orthogonal to the central axis of the mold Y-Y ', is substantially conjugated. of the horizontal section of the central opening 57 of the upper shell 41, to the thickness of the skin 11 near.

  The punch 85 has a smooth outer surface 87 intended to push the skin 11 into the mold 33.

  For this purpose, the punch 85 is movable between a retracted position, away from the mold 33 (FIG. 3), and an insertion position in the forming cavity 71 of the mold 33 (FIG. 4), in which the region lower 89 of the outer face 87 is disposed in the vicinity of the inner face 47 of the lower shell 39.

  The cutting means 37 (FIG. 5) comprise a retractable blade 91 of substantially cylindrical shape. The horizontal cross section of the edge 95 of the blade 91 is substantially conjugate with the shape of the edge 93 delimiting the central opening 57 of the upper shell 41.

  The blade 91 is movable between a retracted position away from the mold 33 and an active cutting position, shown in FIG. 5, in which the edge 95 of the blade is in contact, along the edge 93, with the upper face 97 of the mold 33.

  The method of forming the skin 11 shown in Figure 1 in the forming device 13 will now be described with reference to Figures 2 to 5.

  This method comprises a step of heating the skin 11, a step of inserting the skin 11 into the mold 33, a step of plating the skin 11 against the walls 45, 55 of the mold 33, and a step of removing the skin 11 the skin 11 of the mold 33.

  In the heating step, with reference to FIG. 2, the skin 11 comprising at least one layer of a thermoplastic material is brought opposite the heating means 31, which are arranged above the mold 33.

  Initially, the outer faces 21, 101 of the skin 11 are devoid of relief.

  The skin 11 is then brought to a softening temperature of between 150 ° C. and 200 ° C. by the heating means 31.

  The step of inserting the skin 11 into the mold 33 comprises a laying phase, represented in FIG. 3, in which the peripheral portion 103 of the skin 11 is applied to the upper face 97 of the upper shell 41 and fastened on this upper face 97, for example by gripping by a suitable clamping member 104.

  Then, the punch 85 is brought opposite the central opening 57 of the mold 33 and inserted into the mold 33 as illustrated in FIG. 4.

  During this insertion phase, the punch 85 pushes the central portion 105 of the skin 11 into the forming cavity 71 until the central portion 105 is disposed in the vicinity of the textured inner face 47. The central portion 105 is then disposed in contact with the inner face 47 or spaced from this face 47.

  In the plating step, the vacuum pump 81 is activated, and the gas present between the skin 11 and the walls of the mold 33 is sucked by the vacuum pump 81. A vacuum is created in the forming cavity 71.

  Under the effect of this depression, the skin 11 is pressed against the walls 45, 55 of the mold 33, and the texture of the external appearance face 21 of the skin 11 is then formed.

  The punch 85 is then removed from the mold 33.

  The removal step comprises a cutting phase of the skin 11, a mold opening phase 33 and a skin ejection phase 11.

  In the cutting phase illustrated in FIG. 5, the blade 91 is brought into its active cutting position in order to separate the peripheral portion 103 from the skin 11.

  In the opening phase of the mold 33 shown in FIG. 6, the upper shell 41 is displaced in translation along the central axis YY 'from its closed position to its open position in order to disengage the skin 11, particularly with respect to its undercut portion 19.

  During this movement, the smooth central region 65 of the inner face 61 slides against the side wall 17 of the skin 11, without damaging the skin 11.

  In the ejection step (Figure 1), the skin 11 is disengaged from the lower shell 39, by axial displacement upwards, without encountering any obstacle. A conventional ejector shell 39, shown schematically by an arrow, is used for this purpose.

  The opening of the upper shell by axial translation along the axis YY 'thus makes it possible, before the ejection step, to free the space opposite the undercut portion 19 of the skin 11. which avoids damaging the skin 11 during its ejection.

  Due to the continuity of the central face 61 of the peripheral wall 55 and the inner face 47 of the hollow wall 45, the skin 11 formed in the mold 33 has, on its outer surface 21, a joint plane 131 unique device, substantially perpendicular to a central axis XX 'of the part 11, which also improves its aesthetic appearance.

  In one embodiment of the method, the inner piece of equipment can be made by overmolding a support frame in the skin 11, by injecting a thermoplastic resin into the forming cavity 71, or by foaming.

  Thanks to the invention which has just been described, it is therefore possible to have a negative thermoforming method, to form a covering skin 11 having a portion 19 against peripheral undercut, extending continuously around a central axis X-X ', without the step of removing the skin 11 of the forming mold 33 degrades the aesthetic appearance of the skin

Claims (10)

  A method of forming a skin (11) for covering a piece of interior equipment of a motor vehicle, comprising the steps of: - inserting the skin (11) into a mold (33); - Plating the skin (11) against a wall (45, 55) of the mold (33) by evacuation of the gas present between the skin (11) and the wall (45, 55) of the mold (33) through the wall ( 45, 55) of the mold (33); - removing the skin (11) from the mold (33); characterized in that the mold (33) comprises a bottom portion (39) and a peripheral closure portion (41) and continuous on its periphery about a central axis (Y-Y '), the bottom portions and closure member (39, 41) defining a cavity (71) having an undercut region; and in that the method comprises, prior to the step of removing, at least one step of opening the mold (33) by relative movement of the closure portion (41) relative to the bottom portion (39) along of said central axis (Y-Y ').   2. Method according to claim 1, characterized in that the closing portion (41) has a central surface (61) extending opposite said central axis (Y-Y ') substantially completely parallel to said central axis (Y-Y) ') convergently towards said central axis (Y-Y') towards the outside of the mold (33), and in that, during the plating step, the skin (11) is pressed against the central surface ( 61) of the wall (55).   3. Method according to one of claims 1 or 2, characterized in that the closing portion (41) is movable in relative translation relative to the bottom portion (39) along said central axis (Y-Y ') between a mold closing position (33), in which the bottom and the closure parts (39, 41) are in contact along a contact surface (49), and an opening position of the mold (33), wherein the bottom and closure portions (39, 41) are spaced apart, in that, in the vicinity of the undercut cavity (71), the contact surface (49) extends substantially perpendicular to said central axis ( Y-Y '), and in that the step of opening the mold comprises moving the closing part (41) in translation along the central axis (Y-Y') from its closed position until 'to its open position.   4. Method according to any one of the preceding claims, characterized in that the insertion step comprises the phases of: - laying of the peripheral portion (103) of the skin (11) on an outer face (97) of the closing portion (41); and - inserting the central portion (105) of the skin (11) into the undercut cavity (71); and in that it comprises, before the opening step, a step of cutting the peripheral portion (103) of the skin (11) bearing on said upper face (97).   io 5. Method according to any one of the preceding claims, characterized in that the surface (47, 63) of the walls (45, 55) defining the cavity (71) against undercut is at least partially textured, and in that that the plating step comprises forming a texture on an appearance face of the skin (11) by plating the skin against the textured portion.   6. Mold for forming (33) a skin (11) for covering a piece of interior equipment of a motor vehicle, of the type comprising: - means (35) for inserting the skin (11) into the mold (33); - means (43) for plating the skin (11) against a wall (45, 55) of the mold (33) by evacuation of the gas present between the skin (11) and the wall (45, 55) of the mold (33). ) through the wall (45, 55) of the mold (33); skin removal means (11) of the mold (33); characterized in that the mold (33) comprises: - a bottom portion (39) and a closing portion (41) peripheral and continuous on its periphery about a central axis (Y-Y '), the bottom portions and closure (39, 41) defining a cavity (71) having an undercut region; and - means for opening the mold (33) by relative movement of the closing part (41) with respect to the bottom part (39) along said central axis (Y-Y ').   7. Mold according to claim 6, characterized in that the closing portion (41) has a central surface (61) extending opposite said central axis (Y-Y ') substantially completely parallel to said central axis (Y-Y). ') or convergently towards said central axis (Y-Y') towards the outside of the mold (33).   8. Mold according to one of claims 6 or 7, characterized in that the closing portion (41) is movable in relative translation relative to the bottom portion (39) along said central axis (Y-Y '). between a mold closing position (33), in which the bottom and the closure parts (39, 41) are in contact along a contact surface (49), and an opening position of the mold (33), wherein the bottom and closure portions (39, 41) are spaced apart, and in that, in the vicinity of the undercut cavity (71), the contact surface (49) extends substantially perpendicular to said axis central (Y-Y ').   9. Mold according to any one of claims 6 to 8, characterized in that the surface (47, 63) of the walls (45, 55) defining the cavity (71) against undercut is at least partially textured.   10. skin (11) of a piece of interior equipment of a motor vehicle, characterized in that it comprises a portion (19) in counterpane having an outer surface of appearance (21) textured, said skin ( 11) having a single peripheral joint plane (131) on said outer face (21).