Method for modifying half mold for modifying mold for vehicle body parts

Abstract

The present invention relates to a method for modifying a half-mold of a mold (2) for a body part (6), characterized in that the method comprises the following steps: - realizing at least one cavity (4) in the half-mold of the mold (2); and - realizing at least one protrusion (12) on the surface of at least one protrusion (7) of the half-mold of the mold by laser grinding.

Description

Technical Field

[0001] The present invention relates to the field of car body parts manufacturing, and more particularly to molds for manufacturing these parts. Background Art

[0002] Some vehicle body parts have one or more patterns on their surface which are produced directly on the part, i.e. the pattern is not present in the form of a component added to the part. Such a pattern can be made to appear on the part, for example, by locally changing the surface state of the part to obtain a prominent optical effect (e.g. an impression of depth) and / or by changing the degree of darkness of the part.

[0003] In order to modify the surface state, one or more areas of different appearance can be obtained by one or more surface treatments of the sanding type (for example sanding by chemical etching), while other areas are protected by masking.

[0004] For example, the mold can be frosted, which results in the surface of the part injection-molded in the mold having frosting to obtain a part with a special surface state. This method produces frosting on the entire surface or a large surface of the mold.

[0005] To achieve a more matte area on a body part, the area of ​​the mold where the part will be made can be sandblasted or shot peened to adjust, reduce or increase the gloss level.

[0006] Finally, these solutions are not acceptable for small areas located next to areas of the body part that should not be changed, because these areas are not precise enough and it is difficult to mask the areas that should not be changed in order to leave only the small area exposed. Summary of the invention

[0007] The invention aims in particular to provide a method which makes it possible to obtain a body part comprising at least one pattern with an outstanding optical effect but also with a certain mattness, which is simpler and faster than the methods of the prior art, while making it possible to select very precisely the areas whose surface state and / or mattness are modified.

[0008] For this purpose, the subject of the invention is a method for remodeling a mold half of a mold for producing a car body part, characterized in that the method comprises the following steps:

[0009] - realizing at least one cavity in a mold half; and

[0010] - at least one relief is realized by laser grinding at the surface of at least one raised portion of the mold half.

[0011] Thus, the half-mold of the mold obtained comprises at least one protrusion at its raised surface. The body part molded in this mold will comprise one or more recesses (corresponding to the protrusions made by laser grinding) comprised in one (or more) recesses (corresponding to the protrusions of the mold). These recesses can be linear and extend in one or more directions, for example at an angle of 0° to 90° with the vertical axis Z of the vehicle. This allows to obtain specific optical effects depending on the direction of extension. For example, the parts of these recesses extending vertically on the part mounted on the vehicle constitute light traps, which can enhance the depth effect of the pattern. Conversely, the parts of these recesses extending horizontally on the part mounted on the vehicle reflect light to a great extent, which allows to significantly reduce the depth impression of the pattern. This avoids having to realize a mold comprising excessively large protrusions and recesses, which leads to extended cycle times and increases the risk of cosmetic defects on the molded part. Laser grinding allows to realize the one or more protrusions with high precision to obtain one or more of the sought optical effects.

[0012] Furthermore, laser grinding of the mold halves allows obtaining a repetitive, regular pattern achieved with high precision.Finally, the one or more recesses present on the body part (ie the "recessed" areas on the surface of the body part) are protected from scratches.

[0013] The method according to the invention may further comprise one or more of the following features:

[0014] - the projections are arranged so as to obtain a body part comprising a recess extending at least partially in a vertical and / or horizontal direction when the body part is mounted on a motor vehicle;

[0015] the convex part has a line shape arranged to obtain a body part on which the concave part has a horizontal and / or vertical line shape when the body part is mounted on the motor vehicle;

[0016] - the depth of the cavity is 0.1 mm to 1.5 mm;

[0017] - the frosting step is a second frosting, and the projection is a second projection, the method further comprising a step of realizing a first projection in a half of the mold by frosting between realizing the cavity and realizing the second projection;

[0018] - the first projection is realized on the entire half of the mold;

[0019] - Both sanding steps are carried out in the same area of ​​one half of the mould;

[0020] - the two sanding steps are carried out in different areas of the mould halves;

[0021] - The first sanding step is carried out by chemical sanding or by electrospark machining.

[0022] The invention also relates to a mould for a car body part, which mould is obtained by the transformation method according to the invention.

[0023] Finally, the invention relates to a body part obtained by molding using a mold according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be better understood on reading the following description, which will be given by way of example only, with reference to the accompanying drawings, in which:

[0025] Figure 1 is a front view of a half mold of a mold according to the present invention;

[0026] Figure 2 yes Figure 1 A sectional view of a half-mold of the mold along section II and a body part realized with the mold according to the present invention; and

[0027] Figure 3 It is a three-dimensional view of a part of a vehicle body part realized by means of the mold according to the invention. DETAILED DESCRIPTION

[0028] Hereinafter, reference will be made to directional terms such as "longitudinal axis X", "lateral axis Y", "vertical axis Z", "front", "rear", "upper", "above", "lower", "beneath", etc. These terms are meant to refer to the common orientation of a motor vehicle.

[0029] exist Figure 1 2 shows a mold half according to the invention, for example the concave mold of the mold. As described above, the mold half of the mold 2 is modified to obtain a body part comprising one or more recesses which provide a greater or lesser depth impression depending on their extension direction or directions.

[0030] The first step of the method consists in machining the mold 2 so as to form at least one cavity 4 of the mold 2 in one of its halves. Realizing the cavity 4 allows obtaining a projection 7 (in Figure 1 and 2 In other words, a mold half is obtained which comprises a recessed area (cavity 4) and an area (relief 7) which is elevated relative to the recessed area.

[0031] These projections 7 will form recessed areas 8 (at the Figure 3This is the negative of the protrusion 7 formed in the mold 2). The depth of the cavity 4 is approximately a few tenths of a millimeter, preferably 0.1 to 1.5 millimeters, for example equal to 0.5 millimeters. At this stage, the surface of the mold is smooth, and the mold only includes the cavity 4 and the protrusion 7. This processing of the mold 2 can be achieved by conventional techniques known to those skilled in the art.

[0032] After this step, the method may include a first grinding step. This first grinding step may be achieved by chemical grinding or by electrical discharge machining. Figure 1 and 2 The sanding can be carried out on the entire half of the mould 2, or only on predetermined areas (while protecting, for example, areas that are desired to remain smooth during this sanding). The choice of areas where this sanding is carried out depends on the desired final appearance of the body part 6 moulded in the mould 2. This allows obtaining a first grain texture formed by a first set of reliefs 10 of the mould 2 (these reliefs are therefore irregularities of the surface, some of which are Figure 1 and 2 In the example, the number of convex parts can be Figure 1 and 2 ). Figure 2 , projections 10 are also shown, which are present both on the recesses 4 and on the projections 7 .

[0033] The mold can also be polished or sandblasted.

[0034] After this possible first sanding step, the transformation method according to the invention comprises a second sanding step by laser sanding. This step allows the second protrusions 12 of the mold 2 (some of which are Figure 1 and 2 The number of protrusions may be different from that in Figure 1 and 2 These convex portions 12 are Figure 2 In the embodiment of the present invention, it is visible at the protuberance 7 in order to form, on the body part 6 molded by the mold 2, a recess 14 (corresponding to the negative of the protuberance 12, see below) located inside the recessed area 8. This laser grinding makes it possible to realize at least one second protuberance 12 of the mold 2 very accurately on the surface of the protuberance 7. The size of the second protuberance is preferably between 10 and 100 microns, for example equal to 15 microns. Taking into account the depth of the cavity 4 and the height of the second protuberance 12, the height variations are relatively small, which makes it possible to avoid extending the cycle time when producing the body part 6 or reducing the risk of obtaining a body part 6 including one or more cosmetic defects related to variations in the thickness to be injected.

[0035] The orientation of the one or more second protrusions 12 will allow the body part 6 to have one or more recessed areas 8 including one or more recesses 14 forming a pattern and having optical properties as described above.

[0036] In fact, depending on the extension direction or directions of these second protrusions 12 of the mold 2, it is possible to obtain a vehicle body part 6 that locally more significantly concentrates or, conversely, reflects light.

[0037] If the body part 6 comprises one or more recesses 14 extending partially in the vertical direction, this orientation constitutes a light trap. To the observer, the body part 6 then has a darker, more matte appearance and creates the impression of a greater depth than the actual depth of the part at the recesses 14. This allows the impression of a great depth to be obtained without actually having to realize deep recesses (and without the mold 2 having higher second protrusions 12), which would lead to longer cycle times and the risk of shrinkage cavities or other appearance defects on the body part 6.

[0038] If, on the other hand, the body part 6 includes one or more recesses 14 extending partially in the horizontal direction, this orientation creates an area that reflects a large amount of light. For the observer, the body part 6 then has a brighter, more shiny appearance and creates an impression of less depth than the actual depth of the part. In this case, the pattern also contrasts significantly with the rest of the part outside the recesses 14.

[0039] exist Figure 3 1 , it can be seen that a light source 16 (in this case sunlight) emits light 18, some of which reaches the body part 6. The emitted light rays 18 reaching the left recessed area including the vertical recesses 14 are trapped by these vertical recesses. They are reflected very little (a small number of reflected light rays 20), thus creating a greater impression of depth and a more pronounced matte effect for a user 22 observing the body part 6. The emitted light rays 18 reaching the right recessed area 8 including the horizontal recesses 14 are reflected by these recesses 14 to a large extent (many reflected light rays 20), thus creating a smaller impression of depth and a more pronounced reflective effect for a user 22 observing the body part 6.

[0040] As in Figure 1 As shown in the rightmost pattern, it is possible to realize a second convex portion of the mold 12 extending at least partially in a direction that allows obtaining a body part 6 comprising concave portions 14 that extend neither horizontally nor vertically when it is mounted on the motor vehicle. Depending on the angle chosen, these concave portions 14 will be more or less able to trap or, on the contrary, reflect light to obtain the desired optical effect.

[0041] Furthermore, the second projection 12 of the mould 2 allows obtaining a recess 14 of the body part which is virtually scratch-proof, since it is situated in one or more recesses 8 of the body part 6 .

[0042] Advantageously, the second projection 12 of the mould 2 extends at least partially in a direction allowing to obtain a body part comprising a recess 14 extending at least partially in a vertical and / or horizontal direction to obtain the aforementioned optical effect when it is mounted on a motor vehicle.

[0043] Advantageously, the second protrusion 12 of the mold 2 has a linear shape, which is arranged so that the recess 14 on the body part 6 has a linear shape as in Figure 3 The left recessed area 8 of the body part 6 (with the recesses 14 in the shape of vertical lines) will provide a stronger impression of depth and a matte appearance, while the right recessed area 8 of the body part 6 (with the recesses 14 in the shape of horizontal lines) will give a lesser impression of depth and a glossy appearance.

[0044] Laser sanding can be performed as a supplement to the first sanding, for example at the protrusions 7 of the mold 2, or in areas where the first sanding was not performed (because these areas were protected during the first sanding). Thus, it is possible to potentially have three different types of textures, either from the first sanding only, from the laser sanding only, or from a combination of the two sanding steps.

[0045] The invention is not limited to the embodiments described and other embodiments will be apparent to a person skilled in the art. In particular, different patterns or first and second protrusions of the mould than those shown in the figures may be realised and their number may vary.

[0046] Reference numerals list

[0047] 2: Mold

[0048] 4: The cavity of the mold (cavité in French)

[0049] 6: Body parts

[0050] 7: The bulge of the mold (French relief)

[0051] 8: Depressed areas of body parts

[0052] 10: First Boss (French: bossage)

[0053] 12: Second convex part

[0054] 14: Concave part of body parts

[0055] 16: Light Source

[0056] 18: Emitted light

[0057] 20: Reflected Light

[0058] 22: User

Claims

1. A method for modifying a half-mold of a mold (2) for a vehicle body part (6), the method comprising the following steps: - realizing at least one cavity (4) in said half-mold of said mold (2); as well as - at least one relief (12) is achieved by laser grinding on the surface of at least one projection (7) of the mold half, It is characterized in that: - the projection (12) is arranged so as to obtain a body part (6) comprising a recess (14) extending at least partially in a vertical and / or horizontal direction when the body part (6) is mounted on a motor vehicle; - the frosting step is a second frosting step, and the protrusion (12) is a second protrusion, and the method further comprises a first frosting step of realizing a first protrusion (10) in the half-mold of the mold (2) by frosting between realizing the cavity (4) and realizing the second protrusion (12); - The first sanding step is carried out by chemical sanding or by electrical discharge machining.

2. The transformation method according to claim 1, wherein: The second protrusion (12) has a line shape arranged to obtain a body part (6) on which the recess (14) has a horizontal and / or vertical line shape when the body part (6) is mounted on a motor vehicle.

3. The transformation method according to claim 1 or 2, wherein: The depth of the cavity (4) is 0.1 mm to 1.5 mm.

4. The transformation method according to claim 1 or 2, wherein: The first protrusion (10) is realized on the entire half of the mold (2).

5. The transformation method according to claim 1 or 2, wherein: The two sanding steps are carried out in the same area of ​​the mould halves of the mould (2).

6. The transformation method according to claim 1 or 2, wherein: The two sanding steps are carried out in different areas of the mould halves of the mould (2).

7. A mould (2) for a car body part, the mould being obtained by the transformation method according to any one of claims 1 to 6.

8. A vehicle body part obtained by molding using the mold (2) according to claim 7.

Images