WO2000043153A1

WO2000043153A1 - Surface treating method for light-metal castings and vehicle aluminum wheel surface-treated by the same method

Info

Publication number: WO2000043153A1
Application number: PCT/JP2000/000199
Authority: WO
Inventors: Mitsuji Matsui; Atsushi Yoshida
Original assignee: Ube Industries, Ltd.
Priority date: 1999-01-19
Filing date: 2000-01-18
Publication date: 2000-07-27
Also published as: JP3870698B2

Abstract

This surface treating method comprises the steps of greatly reducing the resin thickness of a substrate when a light-metal casting, such as an aluminum wheel casting (26), is to be coated with a dry-plated layer, pressurizing molten metal filled into a mold cavity (14) under a predetermined high pressure by an injection plunger (16) in order to provide a metallic luster superior in design, casting a light-metal material by the high pressure casting method, as desired, that presses a predetermined region of the molten metal during the solidification of the molten metal by a pressing pin (22) installed on a mold (12), barrel-finishing the casting surface of the casting of light-metal material cast and formed by fully reducing the size and number of pinholes in the casting surface of the casting, applying a resin coating to the polished surface, and forming a metal or metallic compound layer on the resin coating surface by dry plating, thereby providing a light-metal casting, such as an aluminum wheel, having a lustrous design surface.

Description

Description Aluminum wheel for vehicles surface-treated in the same manner as light metal objects

The present invention relates to a surface treatment method for a proud product using a light metal material, and in particular, a light metal structure product by die casting including a vehicle wheel made of aluminum or aluminum alloy, and also mainly. The mold cavity is filled with a molten metal of aluminum or aluminum alloy (hereinafter referred to as aluminum material) and converted into metal pressure by an injection plunger (from the tip of the plunger to the pressure receiving surface of the molten metal). about 5 0 O kgf Z cm ² force in the pressure) applied, et ^{1 1 0 O kgf Z cm 2} (- 5 0 main Gapasu force Le ~ by applying 1 1 0 main Gapasukaru) high pressure of about A manufacturing method in which injection molding is performed, and a presser pin pressure is applied to a specific molten metal part during the solidification process of the molten metal by a pressing pin (squeeze pin) installed in a mold as required. Is called a high-pressure manufacturing method). A surface treatment method for high-pressure light metal products suitable for forming a brilliant surface with excellent metallic luster and design on the entire design surface (鏵 skin surface) or on selected surfaces, and surface treatment according to the method Light metal products.

Conventional technology

Light metal materials, especially aluminum products, such as aluminum wheels, are products that require high gloss and design, as well as high strength parts. Particularly in recent years, in the case of vehicle wheels, more and more users prefer aluminum materials having a metallic luster on the design surface. On the other hand, aluminum products are generally manufactured using the high-pressure structure described above. It is often manufactured by a medium or low pressure manufacturing method using a pressure region lower than the pressure applied by the method (approximately 0.01 megapascal to 0.050 megapascal in low pressure manufacturing). Therefore, there are many pinholes, and there are also large pinholes, and these large pinholes form deep recesses. Various surface treatment methods have been studied to obtain a shiny surface by subjecting such a structured aluminum wheel to a surface treatment. Currently, the following three methods are broadly adopted.

(a) 铸 Forming the design surface of the fabricated aluminum wheel 铸 Buffing the skin surface, or applying a clear coating after buffing.

(b) A method of polishing the surface of the aluminum wheel, which forms the design surface, and applying a wet nickel plating and a chrome plating.

(c) 成 Form the design surface of an aluminum wheel. 法 A method of forming a resin coating layer on the skin surface, applying a dry plating layer, and applying a clear coating on the surface.

In the above-mentioned method, the method (a) has a problem in that it is difficult to puff the pit portion. For this reason, for example, a small opening is left on the design surface, and particularly with a wheel of a design that is hard to be buffed, it may not be possible to obtain sufficient glittering properties as expected.

In addition, according to the method (b), when a large pinhole is present, the surface that has not been machined even if it is polished by mechanical grinding or that has been insufficiently machined has a chrome pattern. Adhesion is weak, and detachment corrosion of the plating layer easily occurs in these portions. In order to improve this point, in the current general example of the plating process, a structure was manufactured as disclosed in Japanese Patent Application Laid-Open No. Hei 6-293974 / Japanese Patent Application Laid-Open No. Hei 6-293939. Chromic acid chromate treatment on the aluminum wheel's design surface.Shot blast treatment to close the pinholes due to the aluminum wheel structure. There are many ways to get 00 Taken. However, in this case, it becomes difficult to recycle the wheel. In other words, if the recycling of plated wheels is outsourced to a recycling company, it costs a lot to separate chrome and nickel from aluminum alloys. Also, when aluminum wheels are redissolved in factories, a large amount of nickel and chromium on the surface enters the aluminum alloy as impurities. For this reason, it is not possible to dissolve only the plated wheel product alone. Therefore, it is dissolved together with the ingot (in the case of the ingot, the nickel and chromium amounts are within the standard). For this reason, there is a problem that it is impossible to perform a large amount of recycling at a time.

For the above reasons, method (C) has been developed and commercialized in recent years. As a publicly known technique relating to the method (c), Japanese Patent Publication No. Hei 6-73393 can be mentioned. In this technology, surface treatment is performed as follows.

(1) After shot blasting the surface of the metal material, apply a powder coating to the surface and apply a base treatment.

(2) Apply a clear undercoat as an intermediate layer on the powder coating.

(3) Sputter chrome on the undercoat.

(4) On top of the sputter ring film, apply a clear top coat.

Such a method is excellent in that a brilliant surface can be obtained without performing a polishing step, which is indispensable in the above methods (a) and (b).

However, on the other hand, the surface roughness of the shot blasted surface must be smoothed in advance by powder coating in order to obtain a design surface having excellent metallic luster and excellent design. When shot blast processing is performed, Irregularities of at least several 10 m are formed on the surface of the material. For this reason, unevenness cannot be smoothed out unless powder coating with a thickness of 100 m or more is applied. In particular, the gloss of the surface is important, and a film thickness of 150 m or more is necessary to ensure that the surface has no irregularities after powder coating.

Next, according to the surface treatment method disclosed in Japanese Patent Application Laid-Open No. Hei 6-222701, a base surface is applied to a design surface of an aluminum wheel obtained by manufacturing, and then aluminum aluminum is sputtered thereon. Tiling is applied, and the surface is protected by clear coating. Thus, the above-mentioned disadvantage caused by providing the dry plating layer is eliminated.

However, even with the method disclosed in Japanese Patent Application Laid-Open No. 6-227201, the pinhole cannot be completely closed. As a result, the gas trapped in the pinholes may expand or destroy the coating film during the process of raising the temperature of the aluminum wheel to about 150 ° C during baking of the base coat, and this may cause spattering. There is a problem in that the surface of the tiling layer has an aberrant surface and it is not possible to obtain a satisfactory design.

Further, the technology disclosed in Japanese Patent Application Laid-Open No. 9-290213 is configured as follows. First, the surface of the metal material is degreased and washed with water. Then, paint at least one layer of the “color base coat” and “color or clear resin”. A “sputtering film” is attached to the surface, and a clear “top coat” is applied on top. In the embodiment of Japanese Patent Application Laid-Open No. 9-292023, the thickness of the “base coat” is 10 to 30 μm, and the powder of 60 to 150 β m is further placed thereon. Has a body paint layer. Therefore, the thickness of the underlayer of the “sputtering film” is 70 to 180 // 111.

However, applying a powder coating that is thicker than usual before dry plating had the following problems. That is, • In order to perform replating with the intention of removing irregularities generated by the shot blasting process, the thicker the base resin layer, the worse the chipping resistance, and the test is performed based on a predetermined test method. Good results will not be obtained in the pass / fail judgment of products.

• The thicker the powder coating, the higher the cost.

• Even if a high hardness dry plating is coated, the thicker the resin layer, the lower the expected surface hardness will be. This is because the resin layer, which is the base of the dry-type mold, is soft, and the thicker the resin layer, the more significantly the effect on the surface hardness.

Recently, in the case of aluminum wheels for vehicles, due to the demand for higher strength by increasing the density inside the structure, the die pressure is set by setting the structure pressure to a high pressure region rather than a low and medium pressure region. May form raw material. In the case of an aluminum wheel formed by applying pressure in such a high pressure range, the release agent applied to the mold may not be sufficiently removed from the surface of the metal material by “degreasing and rinsing” after forming. That is, the release agent adheres firmly to the surface of the metal material during molding, so that it cannot be easily removed.

On the other hand, it is generally accepted that it is difficult to completely eliminate the generation of pinholes from the surface of the manufactured aluminum material even when the manufacturing pressure is set to a high pressure range. . Therefore, in order to close the residual pinhole and release the release agent at the same time, it is common practice to clean the material surface using relatively inexpensive shot blasting. You. That is, in order to apply the method described in Japanese Patent Application Laid-Open No. 9-290213 to the surface treatment of an aluminum product in a high-pressure region, a shot blasting process is performed. Therefore, even in the case of the structure in the high-pressure region, the thickness of the underlayer of the sputtering film still needs to be 100 m or more, and in some cases, 150 m or more. others Therefore, as described above, the deterioration of the chipping characteristics could not be avoided, and the test was failed in the final pass / fail test process of the product.

Disclosure of the invention

In view of the above-mentioned problems in the prior art, the main purpose of the present invention is to select the manufacturing conditions of light metal materials, particularly aluminum materials, to improve the internal strength of aluminum products before surface treatment. By forming the skin surface in a predetermined high quality state in advance, it is possible to have a brilliant surface with excellent metallic luster and design properties and to exhibit good chipping characteristics by subsequent surface treatment. It is an object of the present invention to provide a surface treatment method for light metal products and an aluminum product processed by the surface treatment.

Another object of the present invention is to provide a dry plating film in a surface treatment to obtain a metallic luster by coating a dry plating on a light metal product obtained by a high-pressure production method of a light metal material including an aluminum material. The thickness of the base resin is 10 m or more and 40 m or less, which is thinner than the conventional thickness, and provides a surface treatment method for light metal fence products that achieves metallic luster with excellent design. And there.

It is a further object of the present invention to provide a light metal surface obtained through a high-pressure manufacturing process capable of significantly reducing pinholes generated during manufacturing and also reducing pinhole size. By removing the pinholes on the skin surface and producing a smooth polished surface in the direct polishing process without performing shot blasting or chromic acid chromate treatment, a uniform and thin film resin is obtained. The coating layer is applied as an undercoat, and a dry plating layer of a desired metal such as aluminum is provided to provide excellent glittering and glossy properties, and that the chipping characteristics can be achieved by a predetermined test procedure. An object of the present invention is to provide a surface treatment method for a light metal article having a design surface that can pass the pass / fail judgment, and an aluminum article, particularly an aluminum wheel, surface-treated by the method. In order to achieve the above-described object, the present invention employs a method of performing polishing, particularly barrel polishing, on the surface of a light metal object, instead of the conventional shot blast processing. After the barrel polishing, the first resin coating of the base of the dry plating is applied. The barrel polishing is a method of dry polishing using a mixture of granular material called abrasive and an abrasive. After barrel polishing, a first resin coating layer having a thickness of 10 m or more and 40 β m or less is formed on the polished surface, and a dry-mesh layer is formed on the surface of the first resin coating layer. ing . The dry plating is a method in which a predetermined metal coating layer is formed by a sputtering method, and when the dry plating layer is soft, a transparent second resin coating is applied on the dry plating layer. A topcoat layer was formed.

As a polishing step, a puff polishing step or a liquid honing step can be applied in addition to the barrel polishing step. In buff polishing, a polishing agent is held in a puff made of a flexible material such as cloth, and the buff is rotated and pressed against a workpiece to perform polishing. In this case, the abrasive is fixed to the outer peripheral surface of the puff with an adhesive or mixed with a medium such as water or the like and sprayed on the puff. In addition, the liquid horn is used for polishing with a polishing liquid sprayed from a nozzle onto a work. As the polishing liquid, generally, a mixture of water and aluminum or white random is used. Barrel polishing is advantageous in that the polishing time can be reduced in a shorter time as compared with puff polishing, and that a large amount of processing can be performed and the polishing cost can be reduced. In addition, compared to liquid honing, the polished surface can be made a mirror surface, which is advantageous in that the thickness of the base resin for smoothing the polished surface can be reduced.

Barrel polishing for products manufactured by low-pressure manufacturing or heavy-duty manufacturing When the surface is coated with resin, a part of the painted surface swells from sesame seed size to red bean size. This swelling occurs when the gas in the pinhole, which is often present on the polished surface, expands during the heat treatment in the painting process. In the case of shot blasts that have been used in the past, many pinholes were crushed by the shot particles colliding under high pressure, and the above-mentioned swelling problem was unlikely to occur. However, in the case of Norrell polishing, most of the pinholes remain without being crushed.

In addition, problems arise when dry-painting the painted surface. In other words, even if a substance is put into a chamber and vacuumed due to dry plating, the gas in the pinhole comes out through the resin coating film and the degree of vacuum does not rise easily. . If the resin coating is made thinner as in the present invention, the gas will more easily pass through the resin coating film, and it will take more time to increase the vacuum.

Therefore, in the case of aluminum wheels manufactured by low-pressure manufacturing, etc., it is difficult to obtain a metallic luster with excellent design properties by "barrel polishing, applying resin coating, and then dry plating." Can be easily determined.

The inventor of the present invention has found that the number of pinholes generated on the skin surface and the size of the pinhole diameter (pinhole size) can be sufficiently reduced by the high-pressure manufacturing method, and that the above-described surface treatment can be successfully performed. Was considered. Then, when the above-mentioned surface treatment was applied to the object manufactured by the high-pressure manufacturing method as described above, it was found that it was also possible to obtain an object surface having a metallic luster with excellent design properties. . However, under conditions where pressure is difficult to transmit, such as “small gate area”, the pressure of the injection plunger does not sufficiently propagate from the gate to the skin surface, and the pinhole Still remain on the surface. For this reason, it was not possible to obtain a metal luster surface with sufficiently excellent design properties. Therefore, the present inventors conducted a construction test under `` the mold conditions of an aluminum wheel in which a pressure pin is installed at a position opposite to a mold gate and pressurized in accordance with solidification shrinkage. '' . As a result, it was found that the applied pressure sufficiently propagated to the design surface of the artificial product, and that the surface treatment described above provided a surface having a metallic luster with excellent design properties. It is a thing.

According to the present invention, an injection plunger is applied to a molten metal of a light metal material injected into a metal mold to apply a molding pressure of more than about 50 megapascals to form a product in which generated pinholes on a skin surface are suppressed to a predetermined condition. A polishing step of performing polishing on the skin surface so that the surface roughness of the polished surface is equal to or less than a predetermined value;

A coating step of forming a first resin coating layer on the polishing surface,

Forming a metal or metal compound layer on the surface of the resin coating layer with a dry mechanic;

The present invention provides a surface treatment method for light metal products, characterized by comprising:

Preferably, the predetermined condition of the generated pinholes on the polished surface is a condition that the number of pinholes generated in a predetermined area of the polished surface and the size of the maximum diameter are equal to or smaller than a predetermined value. Preferably, the number of the pinholes per 100 cm ² of the polished surface is in the range of 1 to 15, and the maximum diameter is preferably 2 mm or less. More favorable or to rather is attached to the 1 0 0 cm ² of the polishing surface is in the range of 1 to 1 0 one of the pin hole, the size of the maximum diameter of the pinhole Chikaraku less than 2 mm And the number of pinholes having the maximum diameter of 1.0 mm to 2.0 mm is one or zero.

Preferably, the surface roughness of the polished surface obtained by the polishing step is 6.3 m in Rmax. Preferably, the thickness of the first resin coating layer is 1 Gβm or more and 40 // m or less, and a transparent second resin coating is applied on the dry plating layer of the metal or metal compound. The layer is formed as a top coat layer.

Preferably, the squeezing pressure is applied to a predetermined portion of the molten metal of the light metal material filled in the mold cavity by a pressure pin in a solidification process under a high pressure. It includes a pressurizing step of applying.

According to the present invention, in addition to pressing the molten metal of the aluminum material filled in the cavity of the mold for manufacturing the wheel for a vehicle with the injection plunger, the solidification process of the molten metal is performed by the pressing pins installed in the mold. , 1 in the size of pinholes Lumpur diameter occur铸肌surface of the aluminum鏵物the Hoi Rubosu formation site of the molten metal under pressure. O mm or less, the area 1 0 0 cm ² per 0 or less by the number An aluminum wheel is manufactured by a high-pressure manufacturing method so that the surface roughness is R max and a barrel polished surface is provided so that the surface roughness is 1.6 or less. A resin coating layer of 10 m or more and 40 m or less is provided as an undercoat, and a dry plating layer made of a metal or a metal compound is provided on the resin coating layer. Brightness with a structure in which a transparent top coat layer is formed on the surface to obtain a design surface Vehicle wheel is provided.

In the surface treatment method for light metal objects with the above-described configuration, the aluminum wheel of the high-pressure forged product is polished, so that although the aluminum wheel surface has slight polishing scratches, it can be polished to a degree close to a mirror surface. Therefore, the surface of the aluminum wheel can be mirror-finished by applying a thinner resin coating layer than when shot blasting is applied. In particular, by applying barrel polishing, the resin coating layer is much thinner than when shot blasting is performed, that is, an aluminum wheel with a thickness of 10 m or more and at most 40 m or less. The surface can be mirrored. BRIEF DESCRIPTION OF THE FIGURES

The above and other objects, features and advantages of the present invention will be clarified below based on embodiments with reference to the accompanying drawings.

FIG. 1 is a flow chart illustrating a production process and a surface treatment process of a light metal product according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part schematically illustrating the configuration of a high-pressure manufacturing apparatus for manufacturing light metal objects under high pressure.

FIG. 3 is a schematic cross-sectional view of a high-pressure manufacturing apparatus in which a pressure pin operating mechanism is omitted as a modification of the high-pressure manufacturing apparatus shown in FIG.

FIG. 4 is a cross-sectional view schematically showing the configuration of a barrel polishing apparatus used for carrying out the surface treatment method of the present invention.

FIG. 5 is a cross-sectional view showing an example of the structure of an aluminum wheel manufactured by a high-pressure structure and surface-treated by the surface treatment method of the present invention.

FIG. 6A is an enlarged sectional view showing a surface treatment state of the part A of the aluminum wheel shown in FIG. 5,

FIG. 6B is an enlarged sectional view similar to FIG. 6A of a light metal product surface-treated by a conventional surface treatment method,

FIG. 7 is a schematic perspective view showing a schematic configuration of a test apparatus for testing the anti-tipping performance of a surface-treated light metal article.

Fig. 8 shows a part of the results of a chipping performance test performed on an aluminum wheel structure formed by a conventional medium-pressure or low-pressure method after surface treatment using a conventional surface treatment method. Illustration of the surface part,

FIG. 9 is a partial surface view showing the results of a chipping resistance test performed on an aluminum wheel manufactured by a high-pressure structure and surface-treated by the surface treatment method according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, specific embodiments will be described in detail with reference to the accompanying drawings. To

Referring to the flow chart of FIG. 1 schematically illustrating the steps of the high-pressure structure and the surface treatment according to the present invention, first, the aluminum wheel is formed by the high-pressure structure.

The structure of the rule is performed (step 100). This uses a high-pressure manufacturing apparatus 10 shown in FIG. 2 to fill a cavity 14 of a mold 12 with molten metal of an aluminum material through an injection plunger 16, and the front end of the injection plunger 16. A pressure of approximately 50 megapascals to 110 megapascals is applied to the molten metal in cavity 14 from the surface. Here, as a most preferred embodiment, a pressure pin 20 is provided to face the gate 18 of the mold 12. The pressurizing pin 20 is operated by the hydraulic cylinder 22, and when the molten metal filled in the mold cavity 14 is pressurized by the injection plunger 16, during the solidification process of the molten metal, The part of the molten metal facing the gate 18 is pressurized. Thus, the pressure of the injection plunger 16 is sufficiently transmitted from the gate 18 to the skin surface far from the gate 18. Therefore, it is possible to prevent pinholes from remaining on the surface of the skin after fabrication, and to promote high density after solidification. The operation of the pressurizing pin 20 may be controlled so that the switching force is applied by the switching four-way valve 24 in accordance with a desired pressure curve (time vs. pressure curve) from an optimum timing. It should be noted that without operating the pressure pin 20, even if the above-mentioned high pressure is produced, it is possible to sufficiently reduce the occurrence of pinholes on the skin surface as compared with the case of the low pressure production and the medium pressure production. Therefore, even if a surface treatment described in detail below is applied to a light metal material such as an aluminum material manufactured by a high-pressure manufacturing device without the pressurizing pins 20 (see FIG. 3), the function and effect of the present invention cannot be obtained. You can understand that you can do it. Here, referring again to the flow chart of FIG. 1, the aluminum wheel structure that has been high-pressure manufactured and taken out of the mold 12 is subjected to the desired heat treatment in the heat treatment step (step 105), and then the vehicle is subjected to the desired heat treatment. Dimensions as a wheel The rim is machined according to the shape of the rim (step 106),-The aluminum wheel that has undergone the machining process in this manner is, for example, shown in FIG. As shown in FIG. 4, the top surface is barrel-polished as shown in FIG. 4 (step 110).

In this barrel polishing process, the aluminum wheel structure 26 is attached to a barrel polishing device 28, and first, a medium 30 in which a corn or a cork and an abrasive are mixed is supplied to a barrel tank 3. Input to 2. Then, an aluminum wheel-shaped structure 26 fixed to a disk connected to the motor shaft is inserted into the above-described medium in the barrel tank 32. When the motor Ml is rotated in this state, the rotational motion indicated by the arrow is transmitted via the disk 34, and the aluminum wheel structure 26 is rotated in the media 30. The deer 30 collides with the surface of the aluminum wheel structure 26 and grinds the skin surface of the structure 26 to a fine surface state. In the barrel polishing step, the motor M2 is used when the aluminum wheel structure 26 is previously dropped and positioned in the abrasive in the barrel tank 32.

The aluminum wheel structure 26 that has passed through the barrel polishing process is taken out of the barrel tank 32 of the barrel polishing device 28, and is cleaned and degreased through a degreasing process using an appropriate cleaning agent such as water washing (Step 1 1 2). ), And (4) A normal chromatizing treatment for improving the adhesion between the skin surface and the coating layer is performed (step 114).

After the completion of the chromate treatment, the aluminum wheel structure 26 is dried through a drying process (step 116), and then subjected to an undercoating with a resin paint, that is, an undercoat coating process. (Step 120). In this undercoat coating process, a layer coating is preferably performed by primer coating and solvent-based coating. For primer coating, for example, an epoxy resin coating is used to improve corrosion resistance. In addition, for the solvent-based coating, for example, a polyester-based coating and a 10-melanin-based solvent coating are used to improve the adhesion of the subsequent dry-type coating. In this way, a resin coating layer is formed on the skin surface after barrel polishing, and then the coating layer is baked at 160 ° C to 180 ° C for 20 minutes (step 13). 0). The thickness of the resin coating layer is selected to be 10 μm or more and 40 / m or less.

After the undercoat coating with the resin paint is completed, the upper surface of the undercoat coating layer is subjected to dry plating (step 140). There are three types of dry plating: the sputtering method, the vacuum evaporation method, and the ion plating method.Of these, even if the shape is complex, such as the design surface of an aluminum wheel for a vehicle, the film can be formed. A good spring ring method is optimally used. A sputtering film is formed by forming an aluminum film with a thickness of 0.1 m / m to 1.0 m. When a top coat layer is provided on this sputtering film ( In step 150), a urethane-based, acrylic-based, or epoxy-based resin is used as the paint, and the paint thickness is selected to be about 25 / im to 30 // m. It is also possible to provide the topcoat layer using a powder clearer.

The paint of the top coat layer provided as described above is baked at a temperature of 100 ° C. to 160 ° C. for a time of 20 min (step 160).

According to such an embodiment, the thickness of the resin under the dry plating film is 10 μm or more and 40 μm or less, which is significantly thinner than the conventional thickness, and a metal having excellent design properties A glossy surface treatment was finally obtained for the aluminum wheel product.

FIG. 5 is a cross-sectional view showing an aluminum wheel 26a manufactured by the high-pressure manufacturing method as described above and obtained through the surface treatment step. The wheel rim 40 is provided with a wheel rim 40, and a wheel hub 42 having a center hub hole and the like for enabling connection to an axle. Note that the cross-sectional shape of the aluminum wheel 26a, particularly the cross-sectional shape of the wheel hub 42, varies depending on various demands in consideration of designability and strength, and the illustrated example is merely an example. Need to understand

FIG. 6A is a view showing the A portion of the aluminum wheel 26a taken out, and is an enlarged view of the surface treatment structure of the design surface of the wheel hub 42. FIG. 6B shows the low pressure forming method (G.500 megapascal (approximately 0.5 kg Zcm ² ) on the molten metal surface) according to the conventional technique shown for comparison with FIG. 6A. FIG. 4 is a cross-sectional view showing a case where a similar Army wheel structure manufactured with a pressure-introducing mold (1) was subjected to surface treatment by a conventional surface treatment method.

As is clear from the comparison between the surface treatment structures shown in FIG. 6A and FIG. 6B, in the present invention shown in FIG. 6A, the aluminum wheel structure 26a was formed by the high-pressure structure method. Since the skin surface was originally formed with a smooth surface with pinhole generation reduced sufficiently, the skin surface was subjected to buffing or the like to make the skin surface even smoother. As a result of sequentially forming an undercoat layer, a dry-mesh layer and a topcoat layer by the treatment, the overall thickness of the surface treatment layer does not have to be unnecessarily large. In addition, it is possible to obtain a high-quality design surface utilizing the glitter of a metal film provided as a dry plating layer by sputtering or the like. In the example shown in Fig. 6A, a case where the top coat layer is provided by a primer coating and a solvent-based coating is shown as a preferable typical example, but the top coat layer is provided by a powder clear. It should be understood that it is also possible to provide

On the other hand, in the conventional art shown in FIG. 6B, the pinhole is closed on the skin surface of the aluminum material structure formed by the low pressure forming method, A shot blast treatment is applied, and a thick undercoat layer (polyester-based powder coating) is formed on the shot blast to remove unevenness on the skin surface. In this configuration, an aluminum material film is formed on the smooth surface by a polyester-melanin-based solvent coating layer, and an acrylic silicone-based solvent coating as a top coat layer is applied. This results in an increase in the overall thickness of the surface treatment layer, which results in deterioration of the anti-chipping performance described later.

Fig. 7 shows a quality evaluation test of a design product of a structure made of a light metal material such as aluminum with the required surface treatment applied to the skin surface, especially the design of aluminum wheels for vehicles. 1 schematically illustrates a configuration of a tester mechanism for performing a conventional anti-tipping performance test. As shown in FIG. 7, the member 60 to be tested is placed above the appropriate screen 70 or on the screen surface, and the test surface 60 OA of the member 60 to be tested is placed. A predetermined amount of slabs of a predetermined size are ejected from a predetermined position by a pressurized air flow from a direction perpendicular to the surface, and the size and number of various flaw holes formed in the test target surface 6 OA determine the design surface. It is for quality evaluation.

In FIG. 7, a predetermined amount of a stone mass is injected into the rotor 64 from an arrow S, an air flow of a predetermined pressure is introduced from an arrow R, and the stone is blown out from an injection pipe 66 as shown by an arrow T. This chipping resistance test is a test method based on the American Material Testing Standard (ASTMD3170), and a predetermined hole is formed in the surface 60A to be tested in advance. Pass / fail in quality is determined by visual comparison with the standard sample surface.

As a test condition for anti-chipping performance against a typical aluminum wheel for vehicles, basalt No. 6 (diameter: 4.8 mm to 8.0 mm) is used as a stone mass. The amount of test used was about 100 g of the same stone mass, the injection speed was 50 g / sec, and the injection pressure was 4.1 kg / cm ² (Approximately 0.42 megapascal), the test was performed with the distance to the test surface set to 35 cm. In performing the test, Suga Test Machine Co., Ltd., which is a representative example of a test device having the operating principle shown in FIG.

A stepping stone tester (model: JA400) made by (Suita II, Osaka) was used.

FIGS. 8 and 9 show such an anti-chipping performance test for a vehicle aluminum wheel manufactured by the conventional low-pressure manufacturing method and surface treatment method, and the high-pressure manufacturing method and the high-pressure manufacturing method according to the present invention. This is a test result of the chipping resistance of each wheel design surface of a vehicle aluminum wheel manufactured by the surface treatment method.The wheel according to the prior art shown in FIG. 8 has chipping. It can be seen that the caliber is large and the number of tubing is large.

On the other hand, in the case of the aluminum wheel to be tested according to the present invention shown in FIG. 9, it is understood that the number of chippings is greatly reduced and the diameter of the chipping is small. it can. In other words, it can be seen that the chipping performance of the wheel design surface is far superior to that of the prior art.

Here, referring to Table 1, Table 1 shows that, according to the present invention, the aluminum wheel for a vehicle manufactured by applying a pressure with a high-pressure structure and a pressure pin, the aluminum alloy for a vehicle manufactured only by the high-pressure structure is used. The aluminum wheel manufactured by the low pressure manufacturing method according to the prior art and the two sample structures of the wheel are subjected to the polishing treatment by barrel polishing shown in step 110 in FIG. 1 on each wheel surface. When the polishing depth is set at 40 to 60 μm, 140 to 160 μm> 280 to 300 m, the skin surface area B 1 ~ B 3 shows a pinhole Ichiru state remaining in 1 0 0 cm ² per in (鏵肌portion corresponding to the wheel portion indicated by an aluminum wheel Lumpur 2 6 a arrow B 1 ~ B 3 of shown in FIG. 5) :,

Table 1 Two types of structures produced by applying the high-pressure structure (high-pressure structure + pressure pin or high-pressure structure) based on the present invention in each part B1, B2, and B3 The number of pinholes generated on the polished surface of the sample aluminum wheel is significantly lower than that of the sample aluminum wheel manufactured by the conventional low-pressure manufacturing method, and the pinhole diameter is particularly between 01.0 and 2.0. It can be seen that the number is greatly reduced in the large diameter range of 0. In other words, when the barrel polishing depth is increased, when squeezing pressure is applied by a pressurizing pin in addition to high-pressure molding, it is ensured that 100 cm ² per 100 cm ² regardless of the difference in the wheel position. It can be seen that the number of remaining pinholes is not more than 15 at most, and the number of pinholes with large diameters is extremely small. Therefore, by subjecting a high-pressure aluminum structure having a small number of generated pinholes and a large number of pinholes to a surface treatment in the steps shown in FIG. As shown in Fig. 9, it is possible to obtain a wheel design surface with extremely good anti-chipping performance.

On the other hand, in the sample aluminum wheel manufactured by the low-pressure manufacturing method based on the conventional technology, even if the depth of barrel polishing is increased, a large number of pinholes remain on the polished surface and pinholes with a large diameter remain. You can see that. For this reason, in aluminum wheels using the low pressure method, it is essential to crush this pinhole with a shot blast, and the metal plating layer is increased by increasing the thickness of the undercoat. Spanning under—The coating layer must be leveled. For this reason, when a coating layer is layered on a metal plating layer or the like as a top coat layer, deterioration of the anti-chipping performance of the design surface cannot be avoided as shown in FIG. It is.

In addition, the method for evaluating the coating film performance of the surface treated design surface of aluminum wheels In addition to the chipping performance described above, various test methods such as corrosion resistance test and weather resistance test are commonly used and well known, but the surface treatment method according to the present invention is applied. It was confirmed that the design surface of the light metal structure thus obtained was compatible with the tests by these evaluation methods.

Those skilled in the art can easily understand that the surface treatment of the present invention is not limited to aluminum wheels, but can be applied to other light metal material structures for high pressure fabrication.

Pinhole state on polished surface

錄; IH part barrel polishing depth

Method position 40 60 urn 140 160 μm 200 300 urn

B1 00.5 or less: 5 pieces 0.5 or less: 3 pieces Φ0.5 or less: 2 pieces High pressure ώ 0 5 ~ 1 0-\ Μ method-

+ 00.5 or less: 4 pieces 0.5 or less: 3 pieces 0.5 or less: 5 pieces Pressurized B2 9¾0.5 1.0: Right 00.5 1.0: 1 piece

00.5 or less: 9 pieces

B3 00.5-1.0: 2 pieces 0.5 1.0: 3 pieces 0Ο.5 1.Ο: 2 pieces

00.5 or less: 4 pieces 0.5 or less: 2 pieces 00.5 or less: 2 pieces

Pressure 00.5 or less: 7 pieces 00.5 or less: 5 pieces 0.5 or less: 3 pieces

B2 00.5-1.0: 6 pcs 00.5 L 0: 5 pcs 00.5 1.0: 3 pcs

Φ0.5 or less: 5 pieces ώ Q5 · 8 value ίέθ.5 or less: 4 pieces Φ0.5 L.0: 2 pieces 00.5 1.0: 6 pieces 0 2.0: 1 piece

B3 01.0 2.0: 1

02.0 or more 1 piece

Φ0.5 1.0 2 pieces ώ 0 5 or less5 pieces Φ0.5 or less 2 pieces

B1 Φ 1.0-2.0 1 piece 00.5 ~ 1.0: 2 pieces 0.5 1.0 6 pieces 02.0 or more 3 pieces? 2.0 or more: 2 pieces Φ 1.0 2.0 1 piece Low

Φ0.5 or less 5 pieces 00.5 or less: 3 pieces Φ0.5 or less 6 pieces Pressure B2 Φ0.5 1.0 2 pieces 00.5 1.0: 12 pieces ί61.0 ~ 2.0 1 piece

Φ 1.0 2.0 1 piece 02.0 or more: 1 piece 2.0 or more 2 pieces Φ 2.0 or more 6 pieces

Construction 00.5 or less 9 pieces 00.5 or less: 5 pieces 00.5 or less 4 pieces

B3 0Ο 5 1 · 2 2 00.5 1 0: 6 0.5 1.0 7 01.0 2.0: 1 02.0 or more: 3 1.0 to 2.0 1 Φ 2.0 or more .4 2.0 or more 5 As is apparent from the above description, according to the present invention, before the surface of a light metal material such as an aluminum wheel is coated with a solvent-based resin, which is a base treatment for dry plating, barrel polishing is performed on the aluminum wheel. In the past, a powder coating layer of 100 m or more, and in some cases 150 m or more, was required.However, a solvent-based resin coating layer of 1 Om or more, 40 m By simply applying the following thickness range, the surface is sufficiently smooth, inexpensive, has excellent design, and has excellent anti-chipping performance. The effect was obtained.

Claims

The scope of the claims

1. A structure in which an injection plunger is applied to the molten metal of the light metal material injected into the mold with a pressure of more than approximately 50 megapascals to form a material in which pinholes on the skin surface are suppressed to predetermined conditions. Process and

A polishing step of reducing the surface roughness of the polished surface obtained by subjecting the fist skin surface to a polishing treatment to a predetermined value or less;

A coating step of forming a first resin coating layer on the polished surface after the polishing; and

A surface treatment method for light metal products, characterized by comprising:

2. The predetermined condition of the pinholes generated on the polished surface is a condition that the number of pinholes generated within a predetermined area of the polished surface and the size of the maximum diameter are equal to or smaller than a predetermined value. Surface treatment method for light metal products.

3. There within range of 1 to 1 5 of 1 0 0 the attached to cm ² pinholes of the polishing surface, and wherein the Dearuko size of the maximum aperture is 2. O mm or less The method for surface treating light metal products according to claim 2.

4. The number of the pin holes per 100 cm ² of the polished surface is in the range of 1 to 10, and the size of the maximum diameter is 2.O mm or less, and the maximum The surface treatment method for light metal articles according to claim 3, wherein the number of pinholes having a diameter of 1.0 mm to 2.0 mm is one or zero.

5. The light metal according to any one of claims 1 to 4, wherein a surface roughness of the polished surface obtained in the polishing step is 6.3 m in Rmax. Surface treatment method for objects.

6. The surface treatment method for light metal products according to any one of claims 1 to 5, wherein the first resin coating layer has a thickness of 10 m or more and 40 // ιη or less.

7. The surface treatment method for light metal products according to any one of claims 1 to 6, wherein a transparent second resin coating layer (top coat layer) is formed on the metal or metal compound layer.

8. The method of claim 7, wherein each of the first and second resin coating layers includes a primer coating layer.

9. The surface treatment method for light metal products according to claim 7, wherein the thickness of the transparent second resin coating layer (top coat layer) is 20 m or more and 50 m or less.

10. The surface treatment method for light metal products according to claim 1, wherein the polishing step is a barrel polishing step.

11. The method according to claim 1, wherein the step of forming a metal or metal compound layer by dry plating is a sputtering step.

12. The metallurgical process further includes applying a pressing force to the molten metal of the light metal material filled in the mold cavity during a solidification process of the molten metal under a high pressure by a pressure pin. 3. The surface treatment method for light metal products according to claim 1, further comprising a pressurizing step of applying.

13. The surface treatment method for a light metal material according to claim 1, wherein the light metal material is an aluminum wheel.

14 4. In addition to pressurizing the molten aluminum material filled in the cavity of the mold for vehicle wheel making with an injection plunger, the pressurizing pins installed in the mold will cause the solidification of the molten metal. By pressing the thick part of the cavity, the size of the pinholes generated on the polished surface of the aluminum product after polishing is 2.0 mm or less in diameter, and the number is 1 per 100 cm ^{2 in} area. Five An aluminum wheel is formed by a high-pressure manufacturing method so that the number of pieces is equal to or less than the number of pieces, and the skin surface is barrel-polished to form a polished surface having a surface roughness of 1.6 m or less with Rmax. A resin coating layer having a thickness of 10 μm or more and 40 m or less is provided as an undercoat on the polished surface, and a dry plating layer made of a metal or a metal compound is provided on the resin coating layer. An aluminum wheel for glittering vehicles, characterized in that it has a surface treatment layer with a design surface obtained by forming a transparent top coat layer on the plating layer.

15. The glittering vehicle aluminum wheel according to claim 14, wherein the aluminum material is aluminum.

16. The glittering vehicle wheel according to claim 14, wherein the aluminum material is an aluminum alloy.