PROCESSING METHOD OF APPEARANCE

CROSS-REFERENCE TO RELATED APPLICATION

[0001]This application claims the priority benefit of Taiwan application serial no. 113148624, filed on Dec. 13, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

[0002]This disclosure relates to a processing method of an appearance.

Description of Related Art

[0003]Generally speaking, the appearance of magnesium and aluminum alloys formed by the injection molding process often has surface defects such as flow marks, gaps, and pores. Consequently, in the processing process, it is often necessary to rely on the complicated steps such as multiple grinding procedures, repeated filling processes, and multiple painting procedures to improve the quality of the appearance. As a result, production time is significantly increased.

SUMMARY

[0004]The disclosure provides a processing method of an appearance, capable of effectively improving appearance quality while reducing production time.

[0005]The processing method of the appearance provided in the disclosure at least includes the following. A metal substrate is produced through an injection molding process. The metal substrate includes magnesium and aluminum alloys. A pickling process is performed on the metal substrate to form a semi-finished metal substrate. A micro-arc oxidation process is performed on a surface of the semi-finished metal substrate to form an appearance surface.

[0006]Based on the above, through the pickling process in this disclosure, at least part of the components that cause appearance defects can be removed, the difference between light and dark can be improved, and the technical effect of improving the appearance quality can be achieved. In addition, the disclosure also effectively reduces production time through the simple process design.

[0007]To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0009]FIG. 1 is a schematic flow chart of a processing method of an appearance according to some embodiments of this disclosure.

[0010]FIG. 2 is a partial schematic diagram of an execution state of an injection molding process for producing a metal substrate according to the processing method of the appearance according to some embodiments of the disclosure.

[0011]FIG. 3 is a partial schematic diagram of a mold used in the injection molding process for producing the metal substrate according to the processing method of the appearance according to some embodiments of the disclosure.

[0012]FIG. 4A is a partial schematic diagram of a surface of the metal substrate that has not been subjected to a pickling process.

[0013]FIG. 4B is a partial schematic diagram of a surface of the metal substrate that has been subjected to a pickling process.

[0014]FIG. 5 is a schematic flow diagram of a specific implementation of the embodiment of FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

[0015]In the following detailed description, for purposes of illustration and not limitation, example embodiments are set forth disclosing specific details in order to provide a thorough understanding of the various principles of the disclosure. However, it will be apparent to one of ordinary skill in the art, having benefit from the disclosure, that the disclosure may be practiced in other embodiments that depart from the specific details disclosed herein. In addition, descriptions of well-known methods and materials may be omitted so as not to obscure the principles underlying the disclosure.

[0016]FIG. 1 is a schematic flow chart of a processing method of an appearance according to some embodiments of this disclosure. FIG. 2 is a partial schematic diagram of an execution state of an injection molding process for producing a metal substrate according to the processing method of the appearance according to some embodiments of the disclosure. FIG. 3 is a partial schematic diagram of a mold used in the injection molding process for producing the metal substrate according to the processing method of the appearance according to some embodiments of the disclosure. FIG. 4A is a partial schematic diagram of a surface of the metal substrate that has not been subjected to a pickling process. FIG. 4B is a partial schematic diagram of a surface of the metal substrate that has been subjected to a pickling process.

[0017]Referring to FIG. 1, the processing method of the appearance according to this embodiment includes at least the following steps. First of all, the processing method in this disclosure is designed based on the appearance formed by magnesium and aluminum alloys. Therefore, corresponding to step S110, the metal substrate including magnesium and aluminum alloys is produced through the injection molding process.

[0018]Referring to FIG. 2, specifically, a mold 100 used in the injection molding process has a fan-shaped flow channel 101, whereby the material entering through an injection port 102 can move forward in a regular and uniform lateral direction (as indicated by solid lines 103 in FIG. 2). In this way, compared with the straight forward movement caused by the current straight-through glue channel (shown as dashed lines 104 in FIG. 2, not this case), the difference in lightness and darkness of the surface of the metal substrate formed by the fan-shaped flow channel 101 of the disclosure is significantly reduced. In some embodiments, the metal substrate is all or part of the housing of the electronic device.

[0019]Referring to FIG. 3, in some embodiments, the mold 100 used in the injection molding process also has an oil circuit for uniform temperature distribution, i.e., there are multiple groups of oil pipelines on the left and right sides of a first portion 100A and a second portion 100B of the mold 100, respectively, so that a workpiece 105 (metal substrate) as a whole (up and down, left and right) reaches a uniform temperature state. As shown in FIG. 3, the multiple groups of oil pipes are the first group of oil pipes 111 and 112 on the upper left side; the second group of oil pipes 113 and 114 on the lower left side; the third group of oil pipes 115 and 116 on the lower left side; the fourth group of oil pipes 121 and 122 on the upper left side; the fifth group of oil pipes 123 and 124 on the lower left side; and the sixth group of oil pipes 131 and 132 from the right side to the left side. However, the disclosure is not limited thereto, the number of groups of oil pipes can be determined according to the actual design.

[0020]Next, corresponding to step S120, a pickling process is performed on the metal substrate to form a semi-finished metal substrate. Then, corresponding to step S130, a micro-arc oxidation process is performed on the surface of the semi-finished metal substrate to form an appearance surface. The micro-arc oxidation process is plasma ceramic micro-arc oxidation (MAO) technology, which allows the formation of a ceramicized texture. Accordingly, the acidic component of the pickling process corrodes both the surface metal of the metal substrate and the components that cause cosmetic defects (e.g., impurities, magnesium oxide, and/or release agents), and therefore the introduction of the pickling process into the processing method can be an effective way to enhance quality of appearance. Specifically, referring to FIG. 4A and FIG. 4B, the impurities are caused by the mold of the injection molding process, and such impurities cause the surface of the metal substrate to have a difference between the bright side (without impurities) and the dark side (with impurities, such as the position pointed out by the arrows in FIG. 4A), and this bright and dark difference will greatly reduce the appearance quality, and the pickling process herein can remove at least part of the components causing the appearance defects, and improve the bright and dark difference as shown in FIG. 4B, to achieve the effect of improving the appearance quality. In addition, this case also effectively reduces production time through the simple process design.

[0021]In some embodiments, the current micro-arc oxidation process is only applied to the interior of the product due to the fact that the appearance defects cannot be effectively removed, whereas the present case effectively improves the problem of appearance defects by introducing a pickling process into the processing method. In this way, the micro-arc oxidation process can be used directly on the appearance surface of the production, so the case after the micro-arc oxidation process does not need to use the appearance of the traditional technology for coating, can effectively avoid the appearance of the coating caused by the user collision of the situation of paint loss, also has an advantage in durability. On the other hand, this case omits the repeated filling processes and multiple painting procedure that are currently commonly used in magnesium and aluminum alloys appearance, which are not environmentally friendly and increase weight. Therefore, the processing method of this case has environmental benefits and can achieve the purpose of lightweighting.

[0022]In some embodiments, the pickling process includes a first soaking procedure and a second soaking procedure, the pH value of the first soaking procedure is greater than or equal to 1 and less than or equal to 3, and the pH value of the second soaking procedure is greater than or equal to 3 and less than or equal to 6. For example, the first soaking procedure uses a strong acid aqueous solution, the second soaking procedure uses a weak acid aqueous solution, and the first soaking procedure is performed before the second soaking procedure. In this way, the more acidic component first corrodes the surface metal of the metal substrate and the component causing the appearance defects (such as impurities, magnesium oxide and/or release agents) in large quantities, and then clean the residual surface metal of the metal substrate and the component causing the appearance defects (such as impurities, magnesium oxide and/or release agents) by means of the less acidic component in order to obtain a more significant upgrading effect, but the disclosure is not limited thereto.

[0023]In some embodiments, the strong acid aqueous solution includes a first chemical component portion and a first pure water (H₂O) portion, and the first chemical component portion at least includes hydrofluoric acid to more accurately achieve the required corrosion effect, but the disclosure is not limited thereto. In some embodiments, the first chemical component portion further includes citric acid, ethanol, sodium lauryl sulfate, lactic acid, isovaleric acid, or a combination thereof.

[0024]In some embodiments, the strong acid aqueous solution consists of a first chemical component portion and a first pure water (H₂O) portion. The weight proportion of the first chemical component portion in the strong acid aqueous solution is between 10 wt % and 20 wt %, and the weight proportion of the first pure water portion in the strong acid aqueous solution is between 80 wt % and 90 wt %, but the disclosure is not limited thereto.

[0025]In some embodiments, the first chemical component portion consists of hydrofluoric acid, citric acid, ethanol, sodium lauryl sulfate, lactic acid, and isovaleric acid. The weight proportion used in the first chemical component portion in descending order are isovaleric acid, lactic acid, citric acid, sodium lauryl sulfate, ethanol, and hydrofluoric acid, or, the weight proportion used in the first chemical component portion in descending order are isovaleric acid, lactic acid, citric acid, ethanol, sodium lauryl ether sulfate, and hydrofluoric acid, but this disclosure is not limited thereto.

[0026]In some embodiments, the weak acid aqueous solution includes a second chemical component portion and a second pure water (H₂O) portion. The second chemical component portion at least includes oxalic acid, phosphoric acid, or a combination thereof (hereinafter referred to as the main weak acid component) to more accurately achieve the required cleaning effect, but the disclosure is not limited thereto. In some embodiments, the second chemical component portion further includes citric acid, ethanol, glycerol, or a combination thereof.

[0027]In some embodiments, the weak acid aqueous solution consists of a second chemical component portion and a second pure water (H₂O) portion. The weight proportion of the second chemical component portion in the weak acid aqueous solution is between 8 wt % and 18 wt %, and the weight proportion of the second pure water portion in the weak acid aqueous solution is between 82 wt % and 92 wt %, but the disclosure is not limited thereto.

[0028]In some embodiments, the second chemical component portion consists of the main weak acid component, citric acid, ethanol, and glycerol. The weight proportions used in the second chemical component in descending order are citric acid, glycerol, ethanol, and the main weak acid component, but the disclosure is not limited thereto.

[0029]In some embodiments, the soaking time of the first soaking procedure is between 20 seconds and 80 seconds, the soaking time of the second soaking procedure is between 120 seconds and 180 seconds, and the first soaking procedure and the second soaking procedure are both carried out at room temperature, but the disclosure is not limited thereto.

[0030]In some embodiments, the pickling process further includes an oil removal and degreasing process before the first soaking procedure to remove grease and slight rust on the surface of the metal substrate to purify the surface and improve the removal effect of the subsequent soaking procedure.

[0031]In some embodiments, the potion used in the oil removal and degreasing process consists of sodium citrate, ethanol, triethanolamine, polyoxyethylene tert-octylphenyl ether and sodium hydroxide. The weight proportions used in the potion in descending order are polyoxyethylene tert-octyl phenyl ether, triethanolamine, sodium citrate, ethanol, and sodium hydroxide, or the weight proportions used in the potion in descending order are polyoxyethylene tert-octyl Phenyl ether, triethanolamine, sodium citrate, sodium hydroxide, and ethanol, but this disclosure is not limited thereto.

[0032]In some embodiments, the composition of the potion used in the micro-arc oxidation process includes a coloring salt, in which the coloring salt includes molybdenum salt (Mo²⁺), titanium salt (Ti⁴⁺), or a combination thereof, to correspond to the desired appearance effect of the appearance.

[0033]In some embodiments, the composition of the potion used in the micro-arc oxidation process further include phosphate (PO₄³⁻), fluoride (F⁻), ammonium salt (NH⁴⁺) or a combination thereof. The weight proportion used in the potion in descending order are phosphate, ammonium salt, fluoride, and coloring salt, or the weight proportion used in the potion in descending order are phosphate, ammonium salt, coloring salt, fluoride, but the disclosure is not limited thereto.

[0034]In some embodiments, different appearance effects can be achieved by adjusting the parameters of current, frequency (to adjust the surface feel, such as roughness), duty cycle (to adjust the color difference and/or color hue), and time used in the micro-arc oxidation process, for example, as shown in Table 1 below, the appearance effects of cement grey stone pattern, cement grey, milk tea white stone pattern, milk tea white, and the like, can be achieved respectively, with the design of these parameters, in which duty cycle is the ratio of the energizing time to the total time in a pulse cycle. The plain color appearance is achieved by the introduction of coloring salts (chromogenic ions) in the micro-arc oxidation process, so that they participate in the reaction and enter the ceramic layer to make the film layer color, while the stone pattern is achieved by using the pulsed (intermittent) output in the micro-arc oxidation process, with the adjustment of the frequency and duty cycle parameter.

[0035]FIG. 5 is a schematic flow diagram of a specific implementation of the embodiment of FIG. 1. It should be noted that the steps (step S112, step 122, step 124, step 126, and step 132) represented by the dashed lines in FIG. 5 are selectively executed according to different product requirements. In other words, the following is a description of the steps that would be used in the design of some embodiments of the product, and is not intended to limit the disclosure, i.e., as long as there is a processing method of the appearance of the product that includes the steps of FIG. 1, it is within the scope of the technology that is intended to be protected in the disclosure. However, when the steps of FIG. 5 are present together, they have an additive effect on the surface of the product, i.e., the appearance of the product can be best rendered when the steps of FIG. 5 are present together.

[0036]Corresponding to step 112, a rough grinding process is further included before performing the pickling process (corresponding to step 120). For example, the rough grinding process uses multiple grinding process, such as using 240-grit sandpaper for the first rough polishing and using 320-grit sandpaper for the second rough polishing, but the disclosure is not limited thereto.

[0037]Corresponding to step 122, between the execution of the pickling process (corresponding to step 120) and the execution of the micro-arc oxidation process (corresponding to step 130), an alkaline neutralization process is also included to reduce the acid residue on the surface of the metal substrate and reduce the corrosion phenomenon, and the cleaning and bleaching allows the residual release agent and impurities to re-emerge, which is helpful for the subsequent fine grinding process.

[0038]In some embodiments, the pH value of the alkali neutralization process is greater than or equal to 11 and less than or equal to 14, in which the alkali neutralization process uses a strong alkali aqueous solution, and the strong alkali aqueous solution at least includes sodium hydroxide to more accurately achieve the required neutralization effect. In some embodiments, the potion components used in the alkali neutralization process further include ethanol, triethanolamine, sodium lauryl ether sulfate, or a combination thereof. Here, the alkali neutralization process is to completely immerse the metal substrate in a tank loaded with chemical solution.

[0039]In some embodiments, the strong alkali aqueous solution consists of a third chemical component portion and a third pure water (H₂O) portion. The weight proportion of the third chemical component portion in the strong alkali aqueous solution is between 25 wt % and 35 wt %, and the weight proportion of the third pure water portion in the strong alkali aqueous solution is between 65 wt % and 75 wt %, but the disclosure is not limited thereto.

[0040]In some embodiments, the third chemical component portion consists of sodium hydroxide, ethanol, triethanolamine, and sodium lauryl ether sulfate, and the weight proportion used in the potion in descending order is sodium hydroxide, sodium dodecyl polyoxyethylene ether sulfate, triethanolamine, ethanol, but the disclosure is not limited thereto.

[0041]Corresponding to step 124, between performing the pickling process (corresponding to step 120) and performing the micro-arc oxidation process (corresponding to step 130), a fine grinding process is also included. In this embodiment, the fine grinding process is performed after the alkali neutralization process. In this way, it can remove the residual release agent and impurities that appear again in the alkali neutralization process to further improve the appearance quality. The particle size of the sandpaper used in the rough grinding process is larger than that of the sandpaper used in the fine grinding process. For example, the fine grinding process uses 600-grit sandpaper for fine polishing.

[0042]Corresponding to step 126, between performing the pickling process (corresponding to step 120) and performing the micro-arc oxidation process (corresponding to step 130), a sandblasting process is further included. The types of grits used in the sandblasting process include zircon sand, brown corundum, or a combination thereof. In this context, zircon sand optimizes the contrast of flow marks on the surface of male mold, while brown corundum enhances the structural imprints on the male mold.

[0043]In some embodiments, the sandblasting process is performed on the entire surface of the metal substrate (non-locally), and the sandblasting process is performed at least twice to achieve a better defect repair effect and further improve the subsequent product yield.

[0044]Corresponding to step 132, after the micro-arc oxidation process (corresponding to step 130), a transparent protective member is formed on the appearance surface, thereby improving the anti-oxidation ability of the metal substrate. In some embodiments, the material of the transparent protective member includes polyurethane (PU), but the disclosure is not limited thereto.

[0045]It should be noted that the release agent spraying process, finishing process, light finishing process, laser engraving assembly process and other common techniques known to those with ordinary knowledge in the technical field can also be carried out according to the actual product requirements, and therefore are not be repeated in the following.

[0046]To sum up, through the pickling process in this disclosure, at least part of the components that cause appearance defects can be removed, the difference between light and dark can be improved, and the technical effect of improving the appearance quality can be achieved. In addition, the disclosure also effectively reduces production time through the simple process design.

[0047]It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.