FR2768648A1 - Face lining moulded plastic car interior trim avoiding waste accumulation in mould - Google Patents

Abstract

During moulding, only part of the sheet periphery is cut away, leaving an intact section forming a tab (2b). This remains to form an attachment section (2c) connected to the rest of the sheet (2a).- DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the mould (4) completing the process as described. It forms the supporting section (22), covered by the decorative sheet (2) on one face (24), which includes passages (14a, 14b). Preferred features: Cutting takes place when the edge of the material is distributed into the mould, and before it has coated the sheet close to the relevant portion, the hammer and anvil are brought into contact. Pressure is then applied to make the cut, after which the mould is opened. Cutting may be carried out by the edge-shearing the portion between projecting and recessed parts, and by local stamping of the portion near its edge, between the projecting and recessed parts

Description

 The subject of the invention is a method and a mold for producing a part comprising a support part made of plastic material (s), covered at least in part on one side by a non-rigid decor sheet and having a passage, as well as this piece.

 It is necessary to understand by non-rigid sheet, a sheet which may be multihull integrating at least one flexible material (PVC, fabric or non-woven material, etc.) which may include a layer of foam or the like, but which is deformable.

 The invention relates in particular to the production of interior trim parts for a vehicle such as a door panel. The realization of passages through such parts can in particular facilitate their fixing and allow the passage of control members through them.

The part covered by the sheet may represent only part of the part.

EP-AO 582075 discloses a method comprising the following steps:
- introduce the sheet into a mold comprising a molding cavity,
- distribute plastic material in the molding cavity, away from an area inscribed in this cavity and cut the periphery of a portion of the sheet opposite this area,
- cool the room,
- open the mold and eject the finished part.

 This process combines the production of the support piece, its covering with the decor sheet and the production of passages passing through the sheet and the support. However, this process is not fully satisfactory. Indeed, it generates falls of material (decor sheet) corresponding to the portion cut at the periphery and these falls of material pollute the tool, in particular by accumulating there.

 The invention aims to solve this problem by providing a simple, robust, inexpensive and easy to implement solution. For this, the invention proposes that one only performs a partial cutting of the periphery (of the periphery) of said portion of the sheet, so that an uncut portion of the sheet defines at least one tongue of fastener, which makes the cut portion (clipped) of the sheet integral with the rest of this sheet.

 Thus, the peripherally cut portion of the sheet no longer remains in the tooling from which it is not always easy to remove it. The attachment tab can be cut later, manually, on a very simple recovery machine, or even kept in the event that its presence will not constitute discomfort.

 An advantageous characteristic of the invention proposes that the cutting is carried out by crushing the periphery of said sheet portion between two elements respectively forming a hammer and anvil.

 This type of cut keeps the sheet and in particular the edges of the cut between the two elements as long as one does not separate these elements from one another. This prevents plastic from appearing on the other side of the sheet by passing through the cut made in the sheet.

Advantageously, the invention proposes that:
- while the material is distributed in the mold and before the material has lapped the sheet near said portion, the hammer is brought and the anvil substantially in contact with one another, then
- a pressure is exerted between the hammer and the anvil in order to carry out the cutting, then
- we open the mold.

The invention also proposes to improve the quality of the cutting of the sheet. To do this, she suggests that we cut:
- by shearing of the periphery of said portion between a projecting part and a recessed part, and
- By local crushing of this portion, near its periphery, between the projecting part and the hollow part.

 This local crushing advantageously completes the shearing of the sheet which, taking into account the play existing between the elements carrying out the shearing, the flexibility of the sheet and its small thickness, may not be perfectly satisfactory. This complementarity ensures that the cutting is effective in the desired part of the periphery of the sheet.

The invention also relates to a mold. EP-A-0 582075 discloses a mold comprising:
- two parts which are movable relative to one another and which define a molding cavity between them,
- a first and a second movable elements with respect to each other between a separated position where they are distant from each other and a close position where they are substantially in contact with each other according to a contact zone in order to cut a sheet disposed between them along this contact zone, these elements passing through the molding cavity in the close position.

 To solve the aforementioned problems, the invention proposes that the contact zone define an open contour.

 In particular, the invention proposes that one of the elements locally has at least one notch limiting said contour.

 An advantageous solution for cutting the sheet consists in that the first element has a hollow part and the second a projecting part intended to be introduced into the hollow part of the first element to cooperate intimately with it and cut by shearing a sheet inserted between them.

 To further improve the cutting, the invention proposes that in the close position, the two elements locally abut one against the other, on the periphery or near the periphery of the projecting part of the second element.

 Still to improve cutting, the invention proposes that the contact zone define a truncated cone.

 The invention further relates to a part. EP-AO 582075 discloses a part comprising a support part made of plastic material (s), covered at least in part by a non-rigid decor sheet and having a passage comprising a recess in said support part and at least one portion of the sheet peripherally cut opposite the recess.

 To solve the aforementioned problems, the invention proposes that the sheet comprises at least one uncut part defining an attachment tab connecting said portion of sheet to the rest of the sheet.

The invention will appear even more clearly in the description which follows, made with reference to the appended drawings in which:
FIG. 1 is a sectional view of a mold according to the invention, during a first step of the process,
FIG. 2 is a sectional view of the mold of FIG. 1, during a second step of the process,
FIG. 3 is a sectional view of the mold of FIG. 1, during a third step of the method,
FIG. 4 is an enlarged view of the detail marked IV in FIG. 2, according to a first variant,
FIG. 5 is a partial view along arrow V in FIG. 4,
FIG. 6 is a view also enlarged of the detail marked IV in FIG. 2, according to a second variant,
FIG. 7 is an enlarged view of the detail marked VII in FIG. 3, according to the second variant,
FIG. 8 is a view also enlarged of the detail marked IV in FIG. 2, according to a third variant,
FIG. 9 is a partial view along arrow IX of FIG. 8.

 Figures 1 to 3 illustrate a mold 4 comprising a movable part 4a, constituted here by a matrix and a fixed part 4b, constituted here by a punch.

 The punch 4b and the die 4a can be moved relatively to one another between an open position illustrated in FIG. 1 where they are widely spaced from each other and a closed position in which they provide a mold cavity 16.

 The mold 4 comprises means 10, arranged on the punch, for introducing a plastic material 1 into the molding cavity. This introduction may advantageously be carried out by injection under pressure with compression.

 It also has obstruction and puncturing means 12a, 12b intended to prevent the presence of material in recess zones 18 and to cut out the periphery of a portion 2c of the sheet facing these zones 18.

 In FIG. 1, the mold being open, a robot 6 comes to position, using a first arm 6a, a sheet 2 on the matrix 4a. This sheet is retained in particular using nails 8.

 In FIG. 2, the mold 4 is partially closed by bringing together the two parts of the mold. The obstruction and perforation means 12a, 12b pinch the sheet 2 at the periphery of the cutting portions 2c of the sheet. The plastic 1, injected on one side of the sheet by a nozzle 10, applies the other side of the sheet 2 against a bearing surface 34 of the matrix 4a.

 In FIG. 3, the injection of plastic material 1 was continued simultaneously with the closing of the mold 4, in order to carry out a compression injection. The plastic 1 completely fills the mold cavity 16.

 The action of the obstructing and perforating means 12a, 12b on the sheet performs a cutting at the periphery of the portions 2c of the sheet 2. As the cutting is not carried out over the entire periphery of the part, there remains a tongue of sheet 2b connecting the cutting portion 2c to the rest of the sheet constituting its main part 2a.

 After the plastic has cooled, the mold is opened and the finished part ejected. FIG. 1 illustrates a finished part 20 comprising a support 22 of plastic material covered on an aspect face 24 of the sheet 2.

 This part 20 comprises holes 14a, 14b passing right through it, in other words passages. Each passage comprises the recess 18 and the portion 2c partially cut out from the sheet 2. This cutout is retained by the attachment tab 2b to the finished piece 20 and in particular to the main part 2a of the sheet.

 Figures 4 to 9 illustrate three alternative embodiments of the obstruction and perforation means 12a, 12b. Given the specific modifications implied by these variants on the mold, the die 4a and the punch 4b have a different marking for each of these variants, respectively 44a, 54a, 64a; 44b, 54b, 64b.

 Figures 4 and 5 illustrate a first variant of obstruction and perforation means 12a. These means include a hammer 42 fixed relative to the die 44a and an anvil 46 fixed relative to the punch 44b. The movement between the hammer 42 and the anvil 46 is therefore due to the opening and closing of the mold. It takes place in a direction 47.

 The hammer comprises a peripheral projecting part 41 which cooperates with a part 45 of the anvil to pinch the sheet 2 between them.

These two cooperating parts 41, 45 are brought into contact with one another before the arrival of plastic material 1 nearby in order to seal between them and thus avoid the presence of plastic material in the recess area 18 opposite the cutting portion 2c of the sheet.

This cutting portion 2c is disposed between the hammer 42 and the anvil 46, and delimited by the respective cooperating parts 45, 41.

 The protruding part 41 of the hammer defines the contact zone between the two cooperating parts 41, 45. It comprises a notch 43 formed in the hollow, so that the latter, and consequently the contact zone between the hammer 42 and the anvil 46 define an open contour limited by the notch 43, as illustrated in FIG. 5. Thus, at the place of this notch 43, the force exerted between the hammer 42 and the anvil 46 for cutting the household sheet the uncut tab 2b.

 The cutting is thus carried out by crushing between the hammer 42 and the anvil 46 and more particularly their cooperating parts 41, 45.

 It should be noted that for simplicity, only the hammer 42 has been shown in FIG. 5.

 In order to improve the cutting of the sheet, the parts 41 and 45 come to bear along a truncated cone whose generatrices are inclined at an angle a relative to the direction of relative movement of these parts. This angle a is here between 30 degrees and 60 degrees and is close to 45 degrees.

 In FIGS. 6 and 7, the means of obstruction and of perforation 12a differ essentially from those of FIGS. 4 and 5 in that the anvil 56 is movable in translation relative to the punch 54b to which it is mechanically linked.

 The anvil 56 slides inside the punch 54b and around a rod 58 fixed to the punch 54b at one end 58a. This rod comprises at another end a tip 58b participating in guiding the anvil 56 and limiting its amplitude of movement towards the hammer 52. This movement is exerted under the pressure of a spring 60, which could in particular be replaced by a jack hydraulic.

 This mobility of displacement of the anvil 56 makes it possible to bring the hammer 52 and the anvil 56 in contact with one another, and to make the seal between them, before complete closure of the mold, as illustrated in Figure 6.

The force between the cooperating parts 51, 55 is then due to the compression force of the spring 60. The injection-compression of plastic material 1 is thus compatible with the production of the passages 14a, 14b.

 When the mold is completely closed, the sliding between the anvil 56 and the punch 54b is no longer possible, so that the force between the cooperating parts 51 and 55 is due to the force of closing the mold exerted between the punch 54b and the matrix 54a. This higher effort causes the fabric to be cut between the cooperating parts 51, 55 by crushing. The contact zone between these two parts is defined by the projecting part 51 of the hammer 52.

 The variant presented in Figures 8 and 9 differs essentially from that illustrated in Figures 4 and 5 in that the cutting is carried out not only by crushing between the cooperating parts 61 and 65 of the hammer 62 and the anvil 66, but also by shearing . Let us specify, moreover, that here the anvil is directly carried out in the matrix 64a.

 It should be noted that for simplification, only the hammer 62 has been shown in FIG. 9.

 The matrix 64a comprises a hollow portion defining the anvil 66 and including a peripheral part 67 forming a border between the anvil 66 and the bearing surface 34 of the matrix 64a. The shearing is caused by the penetration of the hammer 62 into the hollow of the anvil 66 with a slight clearance of the sheet.

 This shear partially cuts the periphery of the portion 2c. It is completed by the crushing of the sheet, near the periphery of the portion 2c, between the cooperating parts 61 and 65 of the anvil 66 and the hammer 62. The contact zone between these parts is defined by the part 61 of the hammer. Here again, the presence of the notch 63 produced on the hammer 62 makes it possible to carry out only a partial cutting of the portion 2c in order to hold it by the attachment tab 2b.

 Of course, the invention is in no way limited to the embodiments described above. Thus, the references made to the fixed parts and to the mobile parts could be reversed.

 In particular, the anvil could be mobile and / or the hammer fixed.

 In addition, the hammer could be tied to the die and anvil it with the punch.

 Certain technical characteristics presented in one of the variants can be combined with those of the other variants. In particular, the device allowing a stepped pressure between the hammer and the anvil presented in FIGS. 6 and 7 could be used to cut the sheet by shearing as illustrated in FIGS. 8 and 9.

 Of course, the invention is in no way limited to the embodiments described above. Thus, one could plan to connect the cut portion and the main part of the sheet by several tabs. We can even plan to make a multitude of small width tabs making a dotted cut.

 When the anvil (or hammer) is fixed to the punch (or to the die), provision could be made to directly form the shape of the anvil (or hammer) in the punch (or in the die), instead of make two separate pieces.

 The mold could further include a bezel (frame) to hold the sheet.

Claims (10)

Claims  1. Method for producing a part comprising a support part (22) made of plastic material (s), covered at least in part on one face (24) by a non-rigid decor sheet (2) and having a passage (14a; 14b), which method comprises the following steps:  - introducing the sheet into a mold (4) comprising a molding cavity (16),  - distributing plastic material (1) in the molding cavity, away from a zone (18) inscribed in this cavity (16) and cutting the periphery of a portion of the sheet opposite this zone,  - cool the room,  - Open the mold and eject the finished part, characterized in that only a partial cutting is made of the periphery of said portion of the sheet, so that an uncut portion (2b) of the sheet defines the minus an attachment tab, which makes the cut portion (2c) of the sheet integral with the rest (2a) of this sheet.  2. Method according to claim 1, characterized in that the cutting is carried out by crushing the periphery of said sheet portion between two elements forming respectively hammer (42; 52; 62) and anvil (46; 56; 66).  3. Method according to claim 2, characterized in that:  - while the material is distributed in the mold and before the material has coated the sheet near said portion, the hammer is brought in and the anvil is substantially in contact with one another, then  - a pressure is exerted between the hammer and the anvil in order to carry out the cutting, then  - we open the mold.  4. Method according to any one of the preceding claims, characterized in that the cutting is carried out:  - by shearing of the periphery of said portion between a projecting part and a recessed part, and  - By local crushing of this portion, near its periphery, between the projecting part and the hollow part.  5. Mold (4) for producing a part comprising a support part (22) made of plastic material (s), covered at least in part on one face (24) by a non-rigid decor sheet (2) and having a passage (14a; 14b), the mold comprising: - two parts (4a, 4b; 44a, 44b; 54a, 54b; Ma, 64b) movable relative to each other and defining between them a molding cavity ( 16), - a first zou (46; 56; 66) and a second (42; 52; 62) elements movable relative to each other between a spaced apart position where they are distant from each other and a close position where they are substantially in contact with one another along a contact zone in order to cut a sheet disposed between them according to this contact zone (41; 51; 65), these elements passing through the molding cavity in the close position, characterized in that the contact zone defines an open contour.  6. Mold according to claim 5, characterized in that one of the elements has at least one notch (43; 53; 63) limiting said contour.  7. Mold according to claim 5 or 6, characterized in that the first element (46; 56; 66) has a hollow part and the second (42; 52; 62) a projecting part intended to be introduced into the part intaglio of the first element to cooperate intimately with it and cut by shearing a sheet introduced between them.  8. A mold according to claim 7, characterized in that in the close position, the two elements come into abutment locally against one another, on the periphery or near the periphery of the projecting part of the second element.  9. Mold according to any one of claims 5 to 8, characterized in that the contact zone (41; 65) defines a truncated cone.  10. Piece comprising a support piece (22) made of plastic material (s), covered at least in part by a non-rigid decor sheet (2) and having a passage (14a; 14b) comprising a recess (18 ) in said support piece and at least a portion (2c) of the sheet peripherally cut opposite the recess, characterized in that the sheet comprises at least one non-cut part (2b) defining a fastening tab connecting said portion (2c) of leaf to rest (2a) of leaf.