Manufacturing method for automobile spoilers

Abstract

To provide a manufacturing method for a spoiler that is able to suppress formation of a streak along a parting line after coating, while suppressing a large increase in time and labor required for sanding.SOLUTION: According to the present invention, there is provided a manufacturing method for a spoiler for an automobile comprising a molding step, a sanding step, and a coating step. In the molding step, a hollow resin molding is formed so as to form a ridge along a parting line. In the sanding step, the ridge is removed by performing sanding on a region including the ridge. In the coating step, at least a part of the region on which the sanding is performed is coated.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a spoiler for an automobile. [Background technology]

[0002] A spoiler for an automobile is a part attached to the exterior of a vehicle to reduce the lift of the vehicle. An example of a spoiler for an automobile is a rear roof spoiler that is attached to the rear end of the upper surface of the body.

[0003] Patent Document 1 discloses a method for manufacturing an automobile spoiler by sanding a hollow resin molded body obtained by blow molding and painting the sanded area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-48328 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in some cases, recesses may be formed along the parting line of a resin molded product, and if painting is performed without completely removing the recesses during sanding, streaks may be formed along the parting line after painting. On the other hand, if one tries to completely remove the recesses during sanding, the labor required for sanding increases significantly.

[0006] The present invention has been made in consideration of the above circumstances, and provides a method for manufacturing a spoiler that can suppress the formation of streaks along the parting line after painting while suppressing a significant increase in the labor required for sanding. [Means for solving the problem]

[0007] According to the present invention, there is provided a method for manufacturing an automobile spoiler, comprising a molding step, a sanding step, and a painting step, in which in the molding step, a hollow resin molded body is formed so that a convex streak is formed along a parting line, in the sanding step, a region including the convex streak is sanded to remove the convex streak, and in the painting step, painting is performed on at least a part of the sanded region.

[0008] In the method of the present invention, when forming a resin molded body, a convex streak is formed along the parting line, and the convex streak is removed in a sanding process before painting. In the sanding process, since removing the convex streak requires less work than removing the concave streak, there is no significant increase in the work required for sanding. In addition, since there are no concave streak on the parting line after removing the convex streak, the formation of streaks along the parting line after painting is suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view showing a molding machine 20 for forming a resin molded body 2. [Diagram 2] 2 is a cross-sectional view showing a state after molds 23, 24 of the molding machine 20 in FIG. 1 have been closed. [Diagram 3] 3A and 3B are enlarged views of regions A and B in FIG. 1, and FIG. 3C is an enlarged view of region C in FIG. [Figure 4] 2 is a cross-sectional view showing a resin molded body 2, taken along a cross section perpendicular to the longitudinal direction of a protruding strip 1. FIG. [Diagram 5] FIG. 5A is an enlarged view of region A in FIG. 4, FIG. 5B is a view after the protrusion 1 has been removed from the state of FIG. 5A, and FIG. 5C shows the state after the coating film 3 has been formed from the state of FIG. 5B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described. Various features shown in the following embodiments can be combined with each other. Also, each feature can be an invention independently.

[0011] The method for manufacturing a spoiler according to an embodiment of the present invention includes a molding process, a sanding process, and a painting process. Each process will be described below.

[0012] 1. Molding process In the molding step, as shown in Figs. 1 to 5A, a hollow resin molded body 2 is formed so that a protrusion 1 is formed along a parting line PL.

[0013] A method for forming the resin molded body 2 will now be described in detail.

[0014] 1 shows a molding machine 20 for forming a resin molded body 2. The molding machine 20 is configured to mold a parison 22 extruded from a head 21 using a pair of openable and closable dies 23, 24 to form the resin molded body 2.

[0015] In one example, the parison 22 can be formed by extruding the molten resin obtained by melt-kneading the raw material resin downward from a slit provided in the head 21. The raw material resin is, for example, a thermoplastic resin such as polyolefin or polyester, and examples of the polyolefin include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene-based elastomer, and mixtures thereof. The parison 22 is preferably cylindrical or made of a pair of resin sheets. In either case, a hollow resin molded body 2 can be formed.

[0016] The molds 23, 24 have cavity surfaces 23a, 24a and pinch-off portions 23b, 24b surrounding the cavity surfaces 23a, 24a. When the molds 23, 24 are closed, the cavity surfaces 23a, 24a are combined to form a cavity 25 corresponding to the outer shape of the spoiler.

[0017] The parison 22 is introduced between the open molds 23, 24. The parison 22 is introduced between the open molds 23, 24. Thereafter, as shown in Fig. 2, the molds 23, 24 are closed, and air is blown into the parison trapped in the cavity 25, thereby molding the parison 22 into a shape that conforms to the inner surface of the cavity 25, thereby obtaining a resin molded product 2 with flash 2c.

[0018] This molding may be blow molding, in which air is blown into the interior of the parison trapped within the cavity, or vacuum molding, in which molds 23, 24 apply a vacuum to parison 22 to shape it into a shape that conforms to cavity surfaces 23a, 24a, or a combination of both.

[0019] The parison 22 is sandwiched between the pinch-off portions 23b and 24b to be thinned. In the conventional mold, the outer wall 2a of the resin molded body 2 is pushed toward the hollow portion 2b of the resin molded body 2 by the resin extruded from the pinch-off portions 23b and 24b, and a concave stripe is formed along the parting line PL. On the other hand, in the present embodiment, the pinch-off portions 23b and 24b are provided with chamfered shapes 23b1 and 24b1 (shown in FIGS. 3A and 3B) on the edge on the cavity 25 side, so that the force pushing the outer wall 2a toward the hollow portion 2b is weakened. In addition, since the convex stripe 1 is formed at the position corresponding to the pinch-off portions 23b and 24b, even if the outer wall 2a is pushed into the hollow portion 2b, the height of the convex stripe 1 is merely reduced, and no concave stripe is formed. Therefore, by using the molds 23 and 24 having the configuration of the present embodiment, the formation of the concave stripe along the parting line PL is suppressed.

[0020] The pinch-off portions 23b, 24b preferably have the same shape. In the following, the pinch-off portion 23b will be taken as an example for explanation, but the explanation also applies to the pinch-off portion 24b.

[0021] The chamfered shape 23b1 may be a C-chamfer or an R-chamfer. As shown in FIG. 3A, the chamfered shape 23b1 has a height (length along the tip surface 23b2 of the pinch-off portion 23b) H1 of, for example, 0.1 to 2 mm, preferably 0.3 to 0.7 mm. Specifically, the height H1 may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, or 2.0 mm, and may be within a range between any two of the numerical values ​​exemplified here. The chamfered shape 23b1 has a width (length along a plane perpendicular to the tip surface 23b2) W1 of, for example, 0.1 to 2 mm, preferably 0.3 to 0.7 mm. Specifically, the width W1 is, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, or 2.0 mm, and may be within a range between any two of the values ​​exemplified here. If the height H1 or width W1 is too small, a concave streak is likely to be formed along the parting line PL. On the other hand, if the height H1 or width W1 is too large, the labor required to remove the convex streak 1 in the sanding process increases accordingly.

[0022] Next, the molds 23, 24 are opened, the resin molded body 2 with the burr 2c is removed, and the burr 2c is removed to obtain a hollow resin molded body 2 having a convex streak 1 formed along the parting line PL, as shown in Figures 4 and 5A.

[0023] As shown in FIG. 5A, the convex streak 1 preferably has a tapered shape in a cross section perpendicular to the longitudinal direction of the convex streak 1, and is preferably triangular. The explanation of the height H2 of the convex streak 1 is the same as the explanation of the height H1. The width W2 of the convex streak 1 is twice the width W1. Therefore, the width W2 is, for example, 0.2 to 4 mm, and preferably 0.6 to 1.4 mm. Specifically, the width W1 is, for example, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 3.0, or 4.0 mm, and may be within a range between any two of the numerical values ​​exemplified here. If the height H2 or width W2 is too small, a concave streak along the parting line PL is easily formed. On the other hand, if the height H2 or width W2 is too large, the labor required to remove the convex streak 1 in the sanding process increases accordingly.

[0024] 2. Sanding process In the sanding step, the area including the ridges 1 is sanded to remove the ridges 1 as shown in FIG. 5B.

[0025] The resin molded product 2 obtained in the molding process has minute irregularities on its surface due to die lines, melt fractures, and other factors, and the height from the deepest valley bottom to the highest peak of this minute irregularity (hereinafter referred to as the "maximum height") is about 0.1 to 1 mm. Therefore, when manufacturing a spoiler for an automobile by resin molding, which requires good appearance such as surface smoothness and gloss, the surface is smoothed by sanding. Sanding can be performed by rubbing the surface with sandpaper.

[0026] The maximum height of the minute unevenness after sanding is preferably 25 μm or less. By making the maximum height 25 μm or less, the surface of the resin molded body 2 can be made sufficiently smooth. The lower limit of the maximum height is not particularly limited, but is, for example, 4 μm. If the maximum height is 4 μm, the surface is sufficiently smooth, and it is not technically easy to make the maximum height less than 4 μm. Specifically, the maximum height is, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 μm, and may be within a range between any two of the values ​​exemplified here. The maximum height in the present invention is a numerical value of the surface roughness represented by the roughness symbol Rt, and is in accordance with JIS-B0601. The maximum height is expressed by obtaining cross-sectional curves at several random locations (usually five locations) from the surface of the measured article, and averaging the values ​​of these cross-sectional curves. In this case, it is necessary to extract a reference length (usually 5 mm) from a portion that does not have any exceptionally high peaks or deep valleys.

[0027] Sanding may be performed on the entire surface of the resin molded body 2, or on a partial area of ​​the surface of the resin molded body 2 including the ridges 1.

[0028] 3.Painting process In the painting step, as shown in Fig. 5C, painting is performed on at least a part of the area sanded in the sanding step to form a coating film 3. The area to be painted may be the same as the area to be sanded, or may be narrower or wider than the area to be sanded. It is preferable to sand and paint the entire surface of the resin molded body 2.

[0029] The sanded area is now smooth and can be painted to provide a nice looking spoiler.

[0030] The thickness of the coating film 3 is, for example, 1 to 200 μm, and preferably 10 to 100 μm. Specific examples of the thickness are 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0031] The coating film 3 may be a single layer or multiple layers. In one example, the coating film 3 includes a primer coating film formed on the resin molded body 2 and a topcoat coating film formed on the primer coating film. The primer coating film and the topcoat coating film each have a thickness of, for example, 1 to 100 μm, and preferably 5 to 50 μm. Specifically, the thickness may be, for example, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 μm, and may be within a range between any two of the numerical values ​​exemplified here. The primer coating film and the topcoat coating film can each be formed using, for example, an acrylic urethane paint.

[0032] Sanding may be performed after the primer coating is formed. In one example, the resin molded body 2 obtained in the molding process is subjected to a first sanding to remove the protruding ridges 1, and then a primer coating is formed, followed by a second sanding, and then a topcoat coating is formed. In this case, the surface of the resin molded body 2 is made even smoother by the second sanding, so that the appearance of the spoiler can be further improved. [Explanation of symbols]

[0033] 1: Convex stripe 2: Resin molded body 2a: Exterior wall 2b: Hollow part 2c: Bali 3: Coating 20: Molding machine 21: Head 22: Parison 23: Mold 23a: Cavity surface 23b: Pinch-off section 23b1: Chamfer shape 23b2:Tip surface 24: Mold 24a: Cavity surface 24b: Pinch-off section 24b1: Chamfer shape 25: Cavity PL: Parting line

Claims

[Claim 1] A method for manufacturing an automobile spoiler, comprising a molding step, a sanding step, and a painting step, In the molding step, a hollow resin molded body is formed so that a protrusion is formed along a parting line, In the molding step, the resin molded body is formed using a pair of molds, each of which includes a cavity surface that forms a cavity and a pinch-off portion that surrounds the cavity surface; The pinch-off portion has a chamfered shape on an edge on the cavity side, The convex strip is formed at a position where the chamfered shape of the pinch-off portion is provided, the convex rib has a triangular shape in a cross section of the convex rib perpendicular to a direction along the parting line along which the convex rib is formed, The height of the chamfered shape is 0.1 mm or more and 2 mm or less, The width of the chamfered shape is 0.1 mm or more and 2 mm or less, In the sanding step, the region including the protrusion is sanded to remove the protrusion, In the painting step, painting is performed on at least a part of the sanded area, The coating step includes a step of forming a primer coating film on the resin molded body, and a step of forming a topcoat coating film on the primer coating film, The sanding step includes a step of performing a first sanding on the resin molded body obtained in the molding step, and a step of performing a second sanding after the step of forming the primer coating film and before the step of forming the topcoat coating film.

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