KR100876305B1 - Manufaturing method of the die-casting frame for cellular phone - Google Patents

Abstract

A method for manufacturing a die-casting frame is provided to prevent abrasion and damage from occurring due to the friction generated while a portable phone is sliding. A die-casting frame manufacturing method comprises the following steps of: inserting the liquid for heating and melts the aluminum alloy for die-casting at 700~750‹C into the cavity of a mold for molding(S1); and after arranging an alloy frame which is manufactured and cooled in the above step in a press machine, pressing the alloy frame, and then molding the thickness for forming a rail for sliding at both sides of the alloy frame(S2).

Description

MANUFATURING METHOD OF THE DIE-CASTING FRAME FOR CELLULAR PHONE}

The present invention relates to a method of manufacturing a die-casting frame used in a sliding type mobile phone, and more particularly to a rail structure for sliding a mobile phone to ensure a smooth and stable sliding state and also increase the feeling in the sliding operation of the sliding type mobile phone. The present invention relates to a method for manufacturing a die-casting frame, which is formed with a minimum tolerance and is applied to a sliding type mobile phone without variation in thickness for each section.

Die-casting is called die casting, which injects molten metal into a steel mold that has been machined precisely to match the required casting shape. Casting method.

Die-casting products obtained in the above-described manner have better mechanical properties than general injection products, so die-casting is generally used for producing parts such as auto parts, electrical devices, optical devices, weaving machines, measuring instruments, etc., which require more structural stability. It is true.

Recently, however, the die casting method has been applied to mobile phones beyond the production of the above-mentioned parts. The development of die casting alloys suitable for mobile phones showing a tendency to be light and small, or the completion of precise mobile phone structures using such alloys. Many methods are being tried.

Particularly, as the above-mentioned die casting alloy, Patent Registration No. 0141660 (2007.07.16) of Daewon Alloy Co., Ltd. discloses `` Aluminum-Magnesium Alloy for interior and exterior of mobile phones and electronic products ''.

The inventor of the present invention, which has been engaged in the die casting industry related to mobile phone parts for many years, is a disadvantage of the alloy of the registered patent, so that the burrs are not neatly removed in the process of cutting the ball through die casting and removing burs during punching and post-treatment. This leads to failures and to the distortion found during further plating, painting and other post-processing of the frame.

In particular, the disadvantage of the registered patent is that when the heat or physical impact is applied in the post-processing process such as plating process or cutting to the thin and thin product in accordance with the tendency of light and short shrinkage, badness is generated, productivity and cost competitiveness, even Will seriously affect the quality of the finished handset.

In addition, not only the above-described problems for the die-casting alloy itself but also the die casting using only the existing simple casting mold in the sliding type mobile phone cannot lower the tolerance of the rail structure for sliding to the required level in the final product production. Only about 40 to 45% of the produced product is passed as a good product, and the other is a problem that is discarded as defective.

More specifically,

First of all, the present invention and related tolerances in the manufacture of die-casting cellular phone frames mean a one-sided difference between the thickness dimension of the rail and the thickness dimension of the finished rail until the drawing,

Although the tolerance of the rail thickness for sliding is ± 5/100 in the industry, the die-casting process using only casting molds has to be adjusted to ± 6/100 to ± 7/100 even if the tolerance is to be reduced as much as possible. About

Furthermore, the thickness tolerance is also a problem, but in a rail formed of a casting mold, there is a problem in that the thickness of each part of the rail is not constant but is formed differently.

After all, when the case of the sliding mobile phone is formed by die casting, the strength of the case can be guaranteed due to the die casting characteristics.

When comparing the thickness of the final product and the product in the design of sliding motion, the tolerance becomes large and accordingly, the sliding motion becomes loose and stable sliding motion cannot be guaranteed.

In addition, there is a serious problem that the noise is generated due to the sliding operation as the deviation of the thickness also occurs in one rail.

Unless the above-mentioned problem is solved, there is a limitation in applying die casting to a sliding type mobile phone.

In particular, when the sliding type mobile phone case is formed by a simple injection method, not die casting, the period of making the appearance of the mobile phone by injection is a long time itself, and a lot of know-how is accumulated accordingly, but the above-mentioned problems do not occur.

In die casting, since the resin used for die casting is more difficult than the resin used for injection, the melting point is also considerably higher.

In addition, in the current industry situation where die casting has just begun to be applied to exterior products of mobile phones, there is no accumulated know-how.

The inventors have studied the die casting method that can accurately complete the rail structure of the sliding mobile phone.

However, Patent No. 670187 (2007.01.10) `` Multi-stage Pressurized Die Casting Method and Die Using Press '' is disclosed as a conventional technology related to a die casting method.

The above-mentioned Patent No. 670187 relates to a multi-stage pressure die casting method and a mold for casting a liquid state material at a high pressure by using a mechanical press, and a mold and mold opening operation is performed between upper and lower molds using a general mechanical press. After the installation is possible, the upper and lower mold cavities are injected into the liquid metal material using gravity, and the upper mold is lowered to form the lower mold and the metal is injected into the lower mold cavity. Pressurizing the material mechanically, and then finally pressurizing the metal material filled in the cavity of the lower mold by hydraulic pressure using a hydraulic cylinder. The metal is solidified from the moment of being injected into the cavity of the mold. The material is filled into a dense structure inside the cavity and subjected to plastic deformation Is a die casting method characterized in that the casting.

However, the above-mentioned Patent No. 670187 removes shrinkage bonds generated from simple casting, removes casting defects such as shrinkage holes or bubble holes in the product, and simultaneously performs the work of die casting to make molded products having excellent mechanical properties. It is the construction method that pushes work

It is not a technology itself designed to compensate for the deficiency of the sliding type mobile phone rail structure to be implemented in the present invention, there is a difference in the process.

In addition, in order to satisfy consumers' purchase needs for products, the necessity of improving the productability by increasing visual or aesthetic not only in product functions but also in appearance of products is emerging.

Conventional alloys, including the registered patent has a problem in the implementation of high saturation or brightness in the coating process for applying color to the product frame, even if a special coating process that can implement high saturation and high brightness is introduced alloy according to the registered patent It has a component blending ratio that does not match the coating process itself, there is a problem that the product defective rate is increased, such as bubble marks on the appearance of the product after the coating process.

The present invention is to solve the above problems of the prior art, in order to minimize the sliding thickness of the mobile phone rail thickness by adding a press process to avoid the process that was only performed in the existing simple die casting in the frame manufacturing of the mobile phone sliding type. That is the first purpose.

Furthermore, the thickness of the sliding cell phone rail completed to the painting can be maintained at the level of 0.79 to 0.81 mm, that is, the tolerance for the thickness does not occur before the painting step, so that the tolerance is determined only by the thickness of the coating at the time of painting or the highest tolerance is possible. It is an object of the present invention to provide a method for manufacturing a die casting frame that can be maintained at +0.045.

In addition, by providing a constant thickness for the rail to provide a method of manufacturing a die-casting frame that can prevent abrasion and damage caused by the sliding process of the sliding mobile phone, to reduce the stiffness and increase the user experience It aims to do it.

In addition, an object of the present invention is to propose a die casting aluminum alloy, in particular, an aluminum alloy capable of realizing a desired high saturation and high brightness in a later color implementation step, and to propose a method of implementing high saturation and high brightness color of a sliding mobile phone frame in a painting process. do.

The manufacturing method of the die-casting frame which can reduce the tolerance for the thickness of the rail for the sliding-type mobile phone of the present invention for achieving the above object,

An alloy frame molding step of injecting molten aluminum alloy for die casting by heating to 700 to 750 ° C. into a mold cavity; And

The technical frame comprises a thickness forming step of forming a thickness for forming a sliding rail on both sides of the alloy frame by pressing and then placing the cooled alloy frame manufactured in the alloy frame forming step in the press.

In addition, the press of the present invention

The jig portion is provided with a rail forming portion for forming the sliding rail of the alloy frame to be seated on the upper surface of the alloy frame,

Technical features of the press portion for forming a rail for sliding by pressing the alloy frame seated on the jig portion.

In addition, the thickness tolerance of the rail formed through the press is 0 to 0.01,

More preferably, the thickness of the completed rail in the thickness molding step of the present invention is characterized in that the 0.73mm to 0.74mm.

In addition, after the thickness molding step, the coating process to implement the color on the surface of the alloy frame is further included, the coating thickness for the alloy frame in the coating process is characterized in that the technology is 0.03 to 0.035mm on one side.

In addition, the coating process introduced in the present invention

In order to enhance the adhesion to the alloy surface, the first coating step is performed, the first drying step after the first coating step, and the first drying step after the first coating step, and the color to be represented on the product as proceeds after the first drying step 2 A second coating step in which the car painting operation is performed, a second drying step proceeding after the second coating step, and

After the second drying step is made of a third coating step of applying a transparent color to the color-coated frame,

The drying temperature of the first and second drying step is set to 150 to 180 ℃,

The film thickness ratio formed in each coating step is characterized in that the technical 3: 3: 3.

The method of manufacturing the die-casting frame according to the present invention minimizes the thickness tolerance for the sliding type mobile phone rail structure, and maintains the thickness of the sliding type mobile phone rail completed until painting to be maintained at a level of 0.79 to 0.81 mm. Tolerances can be increased by 0.05 and up to 0.03,

In addition, it can form a rail of a constant thickness to prevent the stiffness, friction or noise generated during the sliding process of the sliding mobile phone can meet the user's feeling,

Eventually, the yield can be increased to 90 to 95%, compared to only 40 to 45% of good products produced in the existing full inspection.

In addition, it has the effect of providing excellent aesthetics by enabling high saturation and high brightness color, which is different in quality from existing mobile phone products.

The invention can be explained in more detail as follows with reference to the drawings.

First of all, the present invention is a technique applied to a frame applied to a sliding type mobile phone, more specifically, a frame requiring a sliding structure.

As shown in Figure 5, the sliding cell phone is composed of an upper case (A) and a lower case (B) attached to the number pad that the screen window is visible

A sliding structure for allowing the upper case to slide while being raised relative to the lower case is to be formed in the frame F which is combined with the upper case to form the bottom of the upper case, and in particular, both sides of the edge of the frame F. As a result, rails for sliding should be formed.

Therefore, the alloy frame to the frame mentioned below will be described only in the frame (F) in which the rail structure for sliding is formed in the sliding type mobile phone.

In addition, the surface exposed to the outside when combined with the upper frame (A) in the alloy frame is referred to as the lower surface (20), the opposite surface is referred to as the upper surface (10).

In addition, as mentioned above, the tolerance mentioned in the present invention refers to a design drawing in which the difference in thickness according to the frame formation before painting and the film thickness of one side of the frame by painting the frame are compared with the dimensions on the design drawing. This means minus the thickness of the poem.

The die casting aluminum alloy according to the present invention includes Si, Fe, Cu, Mn, Mg, Cr, Ni, Zn, Ti, Pb, Sn, and other unavoidable impurities in addition to Al, which is a main material and occupies the remaining amount in addition to the remaining components.

The Si is for enhancing the fluidity of the melt, reducing shrinkage, improving heat resistance, and implementing color with high saturation and high brightness, and 7.00 to 8.00 wt% is added.

The Fe is a typical component for improving the demolding performance by reducing the adhesion, 0.50 ~ 0.65% by weight is added.

The Cu is for reducing the adhesion and strengthening the solid solution (particularly for Mg), 1.40 to 1.70% by weight is added, and gives a certain age-hardening to improve hardness and wear resistance, but if it exceeds the upper limit, corrosion resistance Cause degradation.

The Mn is to enhance the corrosion resistance and to support the effect of Fe addition, and is added in an amount of 0.40 to 0.70% by weight, and serves to increase softening resistance and improve surface treatment characteristics at a high temperature.

The Mg is to reduce the corrosion resistance and tensile strength, and the appearance defect rate due to the Si and the color of the product is added 1.60 ~ 1.80% by weight, if less than that the hardness is lowered, if exceeded due to excessive hardness will be reduced fatigue and layer resistance In addition, it is impossible to maintain high-density products, and as time passes after color implementation, bubbles appear on the exterior of the product.

The Cr is for improving abrasion resistance through refinement of crystal grains, and is added in an amount of 0.01 to 0.03% by weight, and contributes to improvement of heat resistance to a certain degree.

Ni is for improving the heat resistance, the 0.03 ~ 0.07% by weight is added, if less than that the heat resistance is lowered, in the case of excess purlin lowers the productivity.

The Zn is to improve the corrosion resistance and strength, and to have brittleness suitable for high saturation and high brightness products, and 0.80 to 1.30 wt% is added, and if it exceeds the upper limit or less than the minimum value, the corrosion resistance decreases and the brittleness becomes excessively strong.

The Ti is to improve the corrosion resistance and strength, 0.01 ~ 0.03% by weight is added.

The Pb and Sn together to improve the formability and machinability, 0.04 to 0.08% by weight and 0.01 to 0.02% by weight are added, respectively, and exceeds the upper limit, hot and cold workability is lowered.

The difference from the components of the alloys described in the above-mentioned Patent Registration No. 0417660 is Cu for reducing adhesion and strengthening of solid solution, Zn for improving corrosion resistance and strength, and for improving brittleness, Cr for improving wear resistance, improving formability and machinability. Sn and Pb for Ni, Ni for improving heat resistance,

Due to the difference in the components, it is possible to prevent breakage and deformation during post-processing such as demoulding, removing burrs, and plating for portable electronic products, and reducing defects even if the thickness is made thinner according to the tendency of thinning and shortening. .

In particular, the Mg, Cr, Ni, Ti, and Zn has a characteristic suitable for protecting the built-in components such as LCD and memory chips of portable electronic products from impact by contributing to the improvement of brittleness characteristics by the interaction of the relative compounding amount. Has been shown to provide

In addition, Mg and Si enable the high-density product of the frame itself, so that air bubbles such as bubbles due to temperature are generated during surface treatment by high temperature in the color realization process, that is, the drying step in the coating process, resulting in appearance defect rate. The problem is solved.

The aluminum alloy component is molded by a die-casting method at a casting temperature of 700 ~ 750 ℃, more specifically, the manufacturing method of the die-casting frame that can reduce the rail tolerance for the sliding mobile phone of the present invention is

As shown in FIG. 1, after the alloy frame forming step (S1) of injecting a molten die-cast aluminum alloy by heating and melting into a mold cavity,

The thickness forming step (S2) of forming the precision thickness for forming a sliding rail on both sides of the alloy frame by placing the pressed alloy frame (F) cooled in the alloy frame molding step (S1) to the press machine (P) and then pressed. Going through,

After the final processing step (S3) including the painting step is completed.

2 is a view schematically showing the press machine (P) used in the thickness forming step of the present invention, the specific operation of the press machine is the same as the conventional various presses, so a detailed description thereof will be omitted.

That is, the press machine (P) is composed of a jig portion 200, the upper surface 10 of the alloy frame is seated, and a press unit 100 for pressing the seated frame to form a rail for sliding on both sides of the alloy frame. do.

In addition, the jig part 200 is provided with a rail forming part 210 for forming a sliding rail of the alloy frame.

Eventually, the alloy frame, which has undergone the alloy frame forming step (S1), is placed in the jig part 200, but one side of the edge of the alloy frame is placed on the rail forming part 210 and then pressed by the press part 100 to the alloy frame F. ) Will form a rail (30).

In this case, the thickness of the rail forming part 210 is preferably adjusted from 0.73mm to 0.73 + 0.01mm to form the desired final rail thickness of the alloy frame.

That is, the thickness of the rail forming part 210 in the press machine (P) so that the thickness (t) of the rail 30 through the thickness forming step (S2) can be a difference value only from 0 to 0.01 when compared with the thickness at the time of design Should be adjusted.

Therefore, the rail thickness (t) of the frame formed by the above method can be adjusted to 0.73 mm, which is the design thickness, and a rail thickness of 0.74 mm can be obtained even if the maximum thickness is within the tolerance range.

The thickness of the die cast alloy frame is not simply formed in the casting mold, but is adopted as a method of drawing down using a press machine in a separate step,

Tolerances on thickness can be guaranteed from 0 to 0.01

Furthermore, since it is a method that is pressed instantaneously by the press, it is possible to obtain the effect that the thickness of each rail is equally formed without variation of each part.

Next, after the thickness molding step (S2) is a post-processing step (S3), including a coating process for implementing the color on the surface of the alloy frame,

Coating is carried out so that the coating thickness of the alloy frame in the coating step is 0.03 to 0.035 mm, respectively, on one side.

Therefore, according to the die casting process according to the present invention incorporating the press method, the tolerance for the rail thickness in forming the alloy frame for forming the rail is guaranteed from 0 to +0.01.

After that, in the post-processing coating process, it is possible to ensure a film thickness of about 0.03 to 0.035 mm on one side.

In the final product, when compared with the dimensions on the design drawing, the tolerance is 0.03 to 0.045, which results in not exceeding the optimum tolerance required for die casting products, ± 0.05,

In addition, when the tolerance is set to zero in the thickness forming step, the tolerance for the rail thickness is determined only by the thickness of the film during the painting step after the coating step.

It will be able to provide products with a structure far superior to the existing sliding cell phone frame.

The post-processing step including the coating in the process of the present invention described above can be understood in more detail through the following examples.

[ Example  : Manufacturing of Portable Electronic Frames]

<Table 1: Composition ratio (wt%) of the alloy component>

Si Fe Cu Mn Mg Cr Ni Zn Ti Pb Sn Al 7.50 0.57 1.45 0.55 1.70 0.02 0.048 1.10 0.023 0.06 0.016  Remaining amount

12 kinds of components having a ratio as shown in <Table 1> and a mixture containing unavoidable impurities are placed in a crucible, melted and put into a mold according to a known method, and then a mobile phone as shown in FIG. 3. Ten frames F each having a rail for sliding of each were manufactured.

Accordingly, each frame having an alloy ratio according to <Table 1> was found to be 38.4kg · f / ㎠ as a result of the brittleness test.

When the rail was formed by the press method in the thickness forming step, the thickness was formed to have a uniform thickness without variation in each part.

The rail thickness (t) was obtained with 7 products with 0.73mm, 4 products with 0.74mm, and 0.745mm slightly thicker than the thickness mentioned, equal to 0.73mm, which is the dimensions on the design drawing.

After that, the painting process is started to color the plated frame, and the film thickness goes from 0.03mm to 0.035mm on one side, and finally the resulting frame rail thickness t is 0.79mm (0.73mm + 0.03 * 2). 0.81 mm (0.74 mm + 0.035 * 2) was confirmed.

In addition, the appearance defects such as bubbles are not visually detected in the finished frame, and it was possible to realize high saturation and high brightness color than existing products.

In other words, in the drying step of the coating process, which is carried out afterwards, heat treatment is performed at a high temperature. However, when the heat treatment is performed at a high temperature, an air layer is formed on the surface of the frame. Therefore, unlike the existing alloy composition ratio, as shown in Table 1, the composition ratio of the alloy, in particular, Mg, which helps to improve the strength and the chemical reaction of Si, was controlled. As a result, the product maintains high density even at high temperatures. This prevents the formation of air layers and enables the production of products without defects in appearance as high saturation and high brightness colors are realized.

In addition, the composition ratio of Zn can be adjusted to provide the brittleness required for high saturation and high brightness products.

Sliding mobile phone frame through die casting and post-treatment improves the strength and appearance performance through plating, and it is possible to obtain a touch or various appearance colors through painting.

4 shows various post processing processes associated with plating and painting.

For reference, in describing the present invention with reference to FIG. 4, in a non-strict sense, 'step' (D, NP, CP, CC, DC) means a comprehensive process, and 'process' refers to the details of each step. Process,

The term 'coating' is used when referring to plating and painting without distinction.

The combination of each manufacturing step associated with FIG. 4 is, for example,

Die casting (D) -chrome plating (CP),

Die casting (D) -nickel plating (NP) -chrome plating (CP),

Die casting (D)-chrome plating (CP)-color coating (CC) (especially black coating (BC) for LCD brackets),

Die casting (D)-nickel plating (NP)-chrome plating (CP)-color coating (CC) (especially black coating (BC) for LCD brackets),

Die Casting (D) -Chrome Plating (CP) -Color Coating (CC) -Diamond Cutting (DC),

Die Casting (D) -Nickel Plating (NP) -Chrome Plating (CP) -Color Coating (CC) -Diamond Cutting (DC),

Die casting (D) -nickel plating (NP) -color coating (CC) -chrome plating (CP), and

Die casting (D)-nickel plating (NP)-color coating (CC)-chrome plating (CP)-diamond cutting (DC), etc.

In consideration of the various possible combinations, arrows related to the process sequence are indicated by solid lines, dotted lines, single-dot chain lines, and double-dot chain lines, respectively.

In addition, hereinafter, the description of FIG. 4 will not describe all the combinations of the various manufacturing steps, but only specific combinations. However, the present invention is not limited by the description of the specific combination.

In the plating process to provide a variety of metal texture with the purpose of strength reinforcement, it is preferable to go through the nickel plating step (NP) and then the chrome plating step (CP) in order to reduce gloss characteristics, strength, and most of all, cost reduction.

If a variety of patterns or lettering through the masking method, even when the color coating (CC) step is mainly performed for the chromium plating step (CP) for the purpose of improving the wear resistance is preferably carried out after the color coating.

After the die-casting step (D), the frame of the sliding type mobile phone is transferred to the plating equipment and subjected to a receipt test to confirm that there are no defects, and then a full-scale nickel plating step is performed (NP).

The nickel plating step (NP) first removes foreign substances and oil on the surface by using an alkaline surfactant, and then washed with running water.

Next, a chemical nickel (Ni) plating process is carried out (NP1), which is to improve the plating quality by forming a conductive film on the surface of the frame or bracket, and uses a commercial grade commercial plating solution. Proceed for 5 to 7 minutes by applying resistance values of ~ 33 ° C, pH 8.3 to 9.3, and 15 mW / cm 2 or less, and then rinse with water.

Subsequently, a copper lactate plating process (NP2) is performed to form a first electroplating layer on the surface of the frame so that the surface has ductility and adhesion, and improves conductivity and reduces shrinkage expansion coefficient of each plating layer. CuSO4 · 5H2O) 200-230 g / l, sulfuric acid (H2SO4) 50-60 g / l, chlorine (Cl) 40-60 ppm, 20-28 ° C., current 650-750 A / CB, voltage 3-4 V / CB 40-40 minutes. Subsequently, it is pickled and neutralized with sulfuric acid and washed with water.

Next, a semi-gloss nickel plating process (NP3) is performed, which is to improve the bonding force between the previous plating layer (copper copper plating layer) and the subsequent plating layer (gloss nickel layer) as a kind of primer.

This semi-gloss nickel plating process uses NiSO4 260 ~ 300g / ℓ, NiCl2 30 ~ 40g / ℓ, boric acid 35 ~ 45g / ℓ, 52 ~ 58 ℃, pH 3.9 ~ 4.5, current 650 ~ 750A / CB, voltage Proceed for 15-25 minutes under 5-7V / CB.

Next, the nickel nickel process (NP4) is carried out. Through this process, scratch and corrosion resistance can be improved. NiSO4 250-310g / ℓ, NiCl2 30-40g / ℓ, boric acid 35-45g / ℓ Mix and use, proceed for 13-17 minutes under 52 ~ 58 ℃, pH 3.9 ~ 4.5, current 750 ~ 850A / CB, voltage 5 ~ 7V / CB.

The difference between the semi-gloss nickel layer and the gloss nickel layer is basically based on the strength of the current density and the kind of the varnish used, and after each process, the recovery process is performed, and after the nickel coating process, water washing is performed. Proceed.

Next, after the nickel plating step, it was considered to adopt a masking method in order to allow a specific pattern or lettering by finally performing a color coating step (CC) for a different color or texture from the nickel plated layer.

The color coating step (CC) first prints a pattern, a number, a logo, etc. on the portion where the previous nickel plating (NP) layer is exposed when the final washing process is performed (CC1). The printing of the masking layer (CC1) may be, for example, silk printing using a printing equipment, and then goes through a drying process.

Subsequently, using a painting facility to proceed with the color coating process (CC2) for realizing the high saturation and high luminance color characteristics of the present invention,

The color coating process carried out in the present invention is the same as the known coating process consisting of the first coating step, the second coating step, and the third coating step, which is the undercoat, the intermediate, and the upper coat. Will you use

The specific working process of each step, that is, the coating thickness and the thickness ratio of each coating, and the drying temperature is different from the existing coating process.

That is, primary coating is performed on the frame where the plating is completed (first coating step). The purpose of the paint spraying in the first painting step is to enhance the adhesion with the paint sprayed in the remaining coating step with the surface of the plated frame. Therefore, the paint sprayed in the first coating step is preferably a paint having a strong acidity so as to perform an adhesive function to the paint sprayed after the corrosion of the plating layer.

Next, the secondary coating work is not immediately performed on the frame in which the primary painting is completed, but the primary painted frame is dried (first drying step). The drying step is preferably dried by hot air, the drying temperature is preferably 150 to 180 ℃.

Next, the secondary painting work is performed on the dried frame (second painting step). The purpose of this step is to represent the desired color in the frame. That is, the paint used in this step is a conventional color paint, the color is selected according to the design requirements. After the secondary coating is completed, the drying process is again performed (second drying step), and the conditions of the second drying step are the same as those of the first drying step.

Next, the third painting is performed on the frame completed until the second drying (third painting step). The purpose of this step is to form a transparent layer on the frame colored to the color to prevent the peeling of the color painted on the frame in accordance with the use and to achieve a high saturation and high luminance color even in aesthetic appearance. Therefore, the paint sprayed in the present painting step is preferably a clear clear paint.

More specifically, it is difficult to implement the color when painting is usually performed on the plating layer. This is because the plated surface is excellent in leveling of the surface as if it is a mirror surface, that is, the smooth state is good, which makes color development difficult. Therefore, the above coating process is required, and the film thickness ratio applied to the frame must also maintain the following ratio.

That is, it is preferable that the film thickness of the coating material apply | coated in each said step is 3: 3: 4. This is because when the film thickness ratio is not maintained, not only the high saturation and high brightness color is implemented, but also the product defect rate is shown by the inventors of the reliability test.

The product reliability test is based on whether the color is peeled off the surface of the product by mixing artificial stone, water, and the finished product together in a test tube of a certain size. In other words, if the color is not peeled off or the color is peeled off at about 1 mm to about 2 mm in size at the corner, the product is accepted as a good product. By the way, the experiment was conducted under the coating conditions, there was no product failure rate.

In particular, in the frame according to the present invention, the color coating step (CC) may be carried out a black coating step (BP) for the bracket undergoes the nickel plating step (NP) or chrome plating step (CP),

Such a black coating may be formed by spraying a paint containing a black pigment, it is possible to repeat the coating and drying several times to improve the coating quality, it is preferable that the matte.

In addition, it is preferable to form fine concavities and convexities on the surface of the frame plated with a strong alkaline (or strong acid) solution before the black coating in order to improve the bonding force.

In addition, if necessary, anodizing is used to oxidize the surface by electrolysis instead of coating to form a passivation film made of aluminum oxide on the aluminum surface (e.g. aluminum products are added to a sulfuric acid solution containing an iron compound). Dipping and applying a current to form a colored anodized film on the surface), and by forming a thin film mainly composed of chromium (Cr) on the surface of the aluminum by a chemical reaction caused by immersing an aluminum material in a solution containing chromate. The black coating layer can be formed by chemical conversion coating or chromate coating.

Next, the chromium plating step (CP) can contribute to improved wear resistance.

First, it is desirable to proceed with the corrosion-resistant reinforcement layer plating step (CP1), which is a porous nickel coatings process in which the microporous coating method developed for the semiconductor manufacturing process or the flat panel display manufacturing process is applied to the general plating field. It is preferable.

The process using a mixture of NiSO 4 220 ~ 270g / l, NiCl 2 60 ~ 80g / l, boric acid 35 ~ 45g / l, 55 ~ 61 ℃, pH 3.9 ~ 4.5, current 650 ~ 750A / CB, voltage 6.4 ~ 6.6 After 2-4 minutes under V / CB, it is washed with water.

This is followed by a chromium activation process (CP2). The process can use commercially available ANKOR® NFDS from Enthone, Inc., a subsidiary of Cookson Electronics, UK, using NFDS 2-3 g / l, 20-30 ° C., under voltage 2-4 V / CB. Run for ~ 50 seconds.

Subsequently, the chromium plating process (CP3) uses a mixture of chromium oxide (CrO3) 210-260 g / l and sulfuric acid (H2SO4) 0.7-1.3 g / l, 35-41 ° C., current 1600-2000 A / CB, voltage 4.8- Proceed for 3 to 5 minutes at 5.8 V / CB, followed by recovery, washing and ion washing (CP4).

Even if the frame pursued in the present invention is a product that is as thin as possible, the deformation does not occur even in the heat applied in each of the above plating processes, thereby increasing the die casting quality as well as the mechanical properties (impact resistance) of the alloy according to the present invention ( Cu), stable post-treatment processes such as removal of burrs during post-demolition (Sn and Pb), and prevent distortion or breakage during plating and other post-processing processes (Ni and Zn), and completed portable electronic products This is because the appearance defect rate does not occur even at, and the strength and shape can be maintained (Cr, Mg, and Si).

In addition, the thinning is possible because the molten alloy is excellent in fluidity.

Next, in order to ensure that only a specific part of the painted frame has glossiness, a frame that has undergone plating and color coating may be considered to undergo a diamond cutting step (DC).

Subsequently, the frame that has undergone the diamond cutting step may achieve perfection of the method and the rust prevention performance of the cutting surface F1 through the transparent protective layer forming step DC1.

For example, the transparent protective layer may use an alkylamine compound system, and may further apply a commercially available lacquer enamel resin to compensate for chemical resistance and weather resistance and to obtain a film maintenance gloss.

In the above description, conventionally known techniques related to each alloy, die casting, press, each plating step and detailed process, and diamond cutting apparatus are omitted, but those skilled in the art can easily infer, infer, and reproduce the art.

In addition, in the above description of the present invention, the present invention has been described in accordance with a specific process order with reference to the accompanying drawings. Various modifications, changes, and substitutions may be made by those skilled in the art. Such modifications, changes, and substitutions are within the scope of protection of the present invention. Should be interpreted as belonging to.

1 is a schematic diagram illustrating a process according to the invention.

Figure 2 is a schematic external view of the press machine introduced in the present invention.

Figure 3 is a mobile phone frame used in the present invention, Figure 3a is a top view, Figure 3b is a bottom view, Figure 3c is a cross-sectional view of A-A.

4 is a process diagram of various post-processing associated with plating and painting according to the invention.

5 is a side view showing the side of the sliding mobile phone.

* Description of the symbols for the main parts of the drawings *

F: Frame P: Press

10: upper surface 20: lower surface 30: rail t: thickness of the rail

100: press portion 200: jig portion 210: rail molding portion

Claims (7)

In the manufacture of sliding mobile phone frame, An alloy frame molding step of injecting molten aluminum alloy for die casting by heating to 700 to 750 ° C. into a mold cavity; And The thickness forming step of forming a thickness for forming a sliding rail on both sides of the alloy frame by pressing and then placing the alloy frame cooled in the alloy frame forming step in the press machine; Press machine used in the thickness forming step The jig portion is provided with a rail forming portion for forming the sliding rail of the alloy frame to be seated on the upper surface of the alloy frame, Method of manufacturing a die-casting frame that can reduce the tolerance of the rail thickness of the sliding-type mobile phone, characterized in that consisting of a press portion for pressing the alloy frame seated on the jig to form the thickness of the rail for sliding. delete The method of claim 1, wherein the thickness tolerance of the rail formed through the press is 0 to 0.01. The method of claim 1, wherein the thickness of the completed rail in the thickness forming step is 0.73 mm to 0.74 mm. According to claim 1, After the thickness forming step further comprises a coating process for implementing the color on the surface of the alloy frame, The coating thickness of the alloy frame in the coating process is 0.03 to 0.035mm on one side, the manufacturing method of the die-casting frame which can reduce the tolerance for the rail thickness of the sliding cell phone. The method of claim 5, wherein the coating process A first coating step in which a primary coating operation is performed to improve adhesion to the alloy surface; A first drying step performed after the first coating step; A second painting step in which a second painting operation is performed in a color to be expressed in a product to be performed after the first drying step; A second drying step performed after the second coating step; And After the second drying step is made of a third coating step of applying a transparent color to the color-coated frame, The drying temperature of the first and second drying step is set to 150 to 180 ℃, The film thickness ratio formed in each coating step is 3: 3: 4 manufacturing method of the die-casting frame that can reduce the tolerance for the rail thickness of the sliding cell phone. The method of claim 1, 3, 4, 5, 6, wherein the alloy frame is 7.00 ~ 8.00% by weight of Si for improving the fluidity of the melt, lowering the export rate, improving the heat resistance, and realizing the color of high saturation and high brightness when coating 0.50 ~ 0.65 wt% Fe for improved demolding performance by reducing tack 1.40 to 1.70 wt% Cu for reduced tack and enhanced solid solution 0.40 to 0.70 wt.% Mn to enhance corrosion resistance and to aid in the effect of Fe addition, 1.60 ~ 1.80% by weight of Mg for improving the brittleness, corrosion resistance and tensile strength and high color and high brightness 0.01 ~ 0.03% by weight Cr for improving brittleness and abrasion resistance, 0.03 to 0.07 wt.% Ni for improving brittleness and heat resistance, 0.80 to 1.30 wt% Zn for improved corrosion resistance and strength, and brittleness, 0.01 ~ 0.03 wt% Ti for improving brittleness and corrosion resistance, 0.04 to 0.08 wt% Pb for improved machinability, 0.01% to 0.02% by weight of Sn for improved formability and machinability, A method of manufacturing a die-casting frame that can reduce the tolerance of the rail thickness of a sliding cell phone, characterized in that it comprises a residual amount of Al and unavoidable impurities.

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