CN108581393B

CN108581393B - Metal middle frame processing method, metal middle frame and mobile terminal

Info

Publication number: CN108581393B
Application number: CN201810505021.7A
Authority: CN
Inventors: 包小明
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2018-05-24
Filing date: 2018-05-24
Publication date: 2019-12-10
Anticipated expiration: 2038-05-24
Also published as: CN108581393A

Abstract

the invention relates to a metal middle frame processing method, a metal middle frame and a mobile terminal, wherein the metal middle frame processing method comprises the following steps: providing a plurality of connecting sections; arranging the connecting sections in a die-casting die at intervals, wherein the connecting sections surround a ring-shaped frame with gaps; injecting and filling molten aluminum into a cavity of the die-casting die through a die-casting treatment process, wherein part of the molten aluminum is solidified to form a middle plate integrally formed with the connecting section, and the rest of the molten aluminum is filled into the gap and solidified to form a filled aluminum material; forming a through hole in the position, corresponding to the gap, of the aluminum filling material, injecting glue into the through hole, and curing to form an antenna partition strip; and carrying out surface treatment on the frame, the filling aluminum material and the antenna partition strip. Form the antenna partition strip in the perforation through the mode of injecting glue for the processing technology of antenna partition strip is simple, greatly reduced the processing cost of whole metal center.

Description

Metal middle frame processing method, metal middle frame and mobile terminal

Technical Field

The invention relates to the technical field of mobile terminals, in particular to a metal middle frame processing method, a metal middle frame and a mobile terminal comprising the metal middle frame.

Background

In a mobile terminal such as a mobile phone, in order to enable the mobile terminal to smoothly receive and send information, an antenna isolation strip is arranged in a middle frame of the mobile phone.

disclosure of Invention

the invention solves the technical problem of reducing the production cost of the metal middle frame.

A metal middle frame processing method comprises the following steps:

Providing a plurality of connecting sections;

arranging the connecting sections in a die-casting die at intervals, wherein the connecting sections surround a ring-shaped frame with gaps;

injecting and filling molten aluminum into a cavity of the die-casting die through a die-casting treatment process, wherein part of the molten aluminum is solidified to form a middle plate integrally formed with the connecting section, and the rest of the molten aluminum is filled into the gap and solidified to form a filled aluminum material;

Forming a through hole in the position, corresponding to the gap, of the aluminum filling material, injecting glue into the through hole, and curing to form an antenna partition strip; and

and carrying out surface treatment on the frame, the filling aluminum material and the antenna partition strip.

a metal middle frame is manufactured by adopting the metal middle frame processing method.

a mobile terminal comprises the metal middle frame.

one technical effect of one embodiment of the invention is that: because place each linkage segment interval in die casting die's die cavity, when the aluminium filling material was formed in the solidification of molten aluminium liquid in the clearance between each linkage segment, the position department that corresponds with the gap on the aluminium filling material formed the perforation, formed the antenna partition strip in the perforation through the mode of injecting glue for the processing technology of antenna partition strip is simple, greatly reduced the processing cost of whole metal center. Meanwhile, the tensile stress generated in the cooling forming process of the filling aluminum materials in different gaps is mutually offset, and the frame formed by connecting the connecting sections through the filling aluminum materials cannot be bent and deformed due to unbalanced stress, so that the forming quality of the whole metal middle frame is ensured.

Drawings

Fig. 1 is a schematic perspective view of a connection section in a metal middle frame according to an embodiment;

Fig. 2 is a schematic structural diagram of a middle frame of a metal middle frame according to an embodiment;

FIG. 3 is a schematic structural diagram of a metal middle frame with aluminum filling according to an embodiment;

FIG. 4 is a schematic view of the aluminum material of FIG. 3 with through holes;

FIG. 5 is a schematic diagram of forming an antenna partition strip in the perforation of FIG. 4;

FIG. 6 is a schematic structural view of the metal middle frame of FIG. 5 after surface treatment;

FIG. 7 is a block flow diagram of a method of processing a metal center according to an embodiment;

Fig. 8 is a block flow diagram of the die casting process of fig. 7.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

it will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "inner", "outer", "left", "right" and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

referring to fig. 6, a method for processing a metal middle frame according to an embodiment of the present invention mainly includes the following steps: referring to fig. 1, S310, a plurality of connecting segments 130 are provided. Referring to fig. 2, S320, the connecting segments 130 are then placed in the die casting mold at intervals, the ends of the connecting segments 130 are not connected, and a gap 140 exists between the connecting segments 130, so that the connecting segments 130 surround a ring-shaped frame 100 with a gap 141. Referring to fig. 3, S330, molten aluminum is injected into and fills the cavity of the die casting mold through a die casting process, wherein a portion of the molten aluminum solidifies to form the middle plate 210 integrally formed with the connecting section 130; meanwhile, the rest of the molten aluminum will penetrate into the gaps 141 of the frame 100, the gaps 140 between the connecting sections 130 form the gaps 141 of the whole frame 100, the molten aluminum penetrating into the gaps 141 of the frame 100 will solidify to form the aluminum filler 220, and the aluminum filler 220 can play a role of connecting the connecting sections 130 in series. Referring to fig. 4, S340, next, a through hole 230 is formed in the aluminum filling material 220 at a position corresponding to the gap 141, and referring to fig. 5, glue is injected into the through hole 230 and cured to form the antenna isolation strip 300. Referring to fig. 6, S350, finally, the aluminum filling material 220, the bezel 100, and the antenna partition strip 300 are surface-treated. The middle plate 210, the bezel 100, the filling aluminum material 220, and the antenna partition strip 300 together constitute the metal middle frame 10.

The frame 100 can be made of stainless steel material or titanium alloy material, and can also be made of 6063 aluminum profile. The surface-treated frame 100 provides the metal middle frame 10 with a good appearance. The middle plate 210 formed by die casting may not be subjected to surface treatment, the middle plate 210 has good mechanical strength such as bending resistance and impact resistance, and the middle plate 210 does not bend and deform due to the fact that a large number of parts are loaded. The die-casting molding process can form complex structures such as grooves and holes in the middle plate 210 in a short time, and compared with the traditional CNC process, the production and machining efficiency of the middle plate 210 is greatly improved. The production cost of the metal middle frame 10 is reduced on the basis of ensuring the mechanical strength of the metal middle frame 10.

More importantly, the glue injection can be understood as injecting the molten plastic liquid into the through hole 230 of the aluminum material 220, cooling and solidifying the molten plastic liquid to form the antenna isolating strip 300, and the antenna isolating strip 300 is simple in processing technology, so that the processing cost of the whole metal middle frame 10 is greatly reduced. Meanwhile, because the connecting sections are arranged in the cavity of the die-casting die at intervals, when molten aluminum is solidified in the gaps 140 among the connecting sections 130 to form the filling aluminum materials 220, the tensile stresses generated in the cooling forming process of the filling aluminum materials 220 in different gaps 140 are mutually offset, and the frame 100 formed by connecting the connecting sections through the filling aluminum materials 220 cannot generate the defects of bending deformation and the like due to unbalanced stress, so that the forming quality of the whole metal middle frame 10 is ensured.

The through hole 230 is a through hole located on the aluminum filling material 220, the cross section of the through hole 230 is in a kidney shape, an oval shape or a rectangular shape according to the needs of actual conditions, the through hole 230 can be formed by adopting a laser punching process or an electric spark punching process, and the laser punching process or the electric spark punching process can well ensure the dimensional accuracy and the processing speed of the through hole 230. The antenna partition strip 300 is formed by an injection molding process, for example, by injecting a molten plastic into the through-hole 230 through an injection molding machine and cooling it. The molten plastic may be prepared by melting PBS (poly butylene-styrene, Polybutadiene-acrylonitrile) material, PBT (Polybutylene terephthalate) material, or PPS (Polyphenylene sulfide) material.

referring to fig. 1 and 2, the connecting segments 130 may be formed by a stamping process, and the total number of the connecting segments 130 is four, two of the connecting segments 130 are C-shaped connecting segments 132, and the other two connecting segments 130 are straight connecting segments 131. The middle portion of the C-shaped connecting section 132 is straight, the two end portions are connected to the middle portion in a bending manner, the straight connecting section 131 is straight as a whole, and the C-shaped connecting section 132 can be formed by bending the straight connecting section 131 through a punching device. In other embodiments, the total number of connecting segments 130 may be two, with both connecting segments 130 being C-shaped connecting segments 132.

Referring to fig. 8, the die-casting process of the middle plate 210 mainly includes the following steps:

S321, preheating a cavity of the die-casting die, and preventing the die-casting die from losing efficacy due to defects such as cracking caused by temperature fusion in the process that the die-casting die is rapidly heated from room temperature to molten aluminum liquid temperature. The die-casting die can be preheated by adopting a resistance wire or an electric heating rod, and can also be preheated by introducing media such as hot oil or steam into a pipeline. After the die-casting die is preheated, the temperature range of a cavity of the die-casting die can be 200-250 ℃.

Then, the cavity of the die-casting die is vacuumized, so that gas in the cavity of the die can be pumped out, and further, gas holes and dissolved gas in the middle plate 210 after die-casting forming are eliminated or remarkably reduced, and the mechanical property and the surface quality of the formed middle plate 210 are improved. During vacuumizing, a vacuum pump can be adopted to directly vacuumize the cavity of the die-casting die; or the die-casting die can be placed in a vacuum box, and the vacuum box is vacuumized through a vacuum pump. In other embodiments, for example: or nitrogen can be introduced into the cavity of the die-casting die, the nitrogen can enable hydrogen dissolved in molten aluminum to be diffused into bubbles, when the bubbles float to the surface of the molten aluminum, the bubbles break, and the hydrogen escapes into the atmosphere, so that the residual hydrogen is prevented from forming air holes in the formed middle plate 210. The following steps are repeated: the refining agent is added into the molten aluminum, the refining agent can be prepared by potassium chloride, calcium fluoride and graphite powder according to a certain proportion, and the refining agent can also remove hydrogen in the molten aluminum and remove oxidation slag floating in the molten aluminum.

S322, secondly, transferring the molten aluminum liquid into heat preservation aluminum, meanwhile, applying an electromagnetic field at the bottom of the heat preservation furnace, generating an induction vortex by the molten aluminum liquid, and mixing for 3-5 min under the stirring and oscillation action of the induction vortex, so that all components of the molten aluminum liquid are uniformly mixed, and the crystal structure of the formed middle plate 210 is ensured to be fine and uniform. And then injecting molten aluminum into a cavity of the die-casting die by using a die casting machine, wherein the molten aluminum can be the molten aluminum of ADC 12. Before the filling rate of the die cavity of the die-casting die reaches 70 percent, the injection speed range of the molten aluminum liquid is 0.5m/s-0.8m/s, and simultaneously, the die-casting pressure range of the die-casting machine is 80MPa-85 MPa. Within the injection speed and the pressure range, the molten aluminum can be ensured to rapidly fill the cavity of the die-casting mold, and the defects of hole formation and the like in the middle plate 210 can be avoided.

S323, when the filling rate of the die-casting die cavity is higher than 70%, the injection speed range of the molten aluminum liquid is 1m/S-1.5m/S, and the die-casting pressure range of the die-casting machine is 90MPa-100 MPa. So that the gas is completely discharged out of the molten aluminum.

And S324, finally, when the cavity of the die-casting die is completely filled, obviously, the molten aluminum liquid is also filled in the gap 140 between the two adjacent connecting sections 130, the pressure of the die-casting machine is maintained for 2min to 3min, and then the molten aluminum liquid is gradually cooled to form the solid middle plate 210 and the filled aluminum material 220. The molten aluminum in the die-casting die cavity can be prevented from flowing backwards in a back pressure manner by pressure maintaining, and shrinkage compensation is performed on the middle plate 210 and the filling aluminum material 220, so that the middle plate 210 with a compact crystal structure is formed.

Referring to fig. 2 and 3, for the molten aluminum that has infiltrated into the gap 141 of the frame 100, the molten aluminum filled in the gap 141 may further cover two opposite sides of the frame 100 by the structural design of the die-casting mold cavity, where the two opposite sides of the frame 100 correspond to two ends of the gap 141, and the two ends of the gap 141 refer to two ends in the height direction (Z-axis direction) of the frame 100. When the molten aluminum is solidified to form the aluminum filler 220, the aluminum filler 220 has an i-shaped cross section, a middle portion 221 of the i-shaped aluminum filler 220 is located in the gap 141 of the frame 100 and extends in the height direction of the frame 100, and edge portions 222 of the i-shaped aluminum filler 220 cover opposite sides of the frame 100 and extend in the length direction (Y-axis direction) of the frame 100. By solidifying the molten aluminum liquid in the gap 141 of the annular frame 100 to form the i-shaped aluminum filler 220, the frame 100 can be further prevented from being warped in the height direction due to the restraining action of the edge portion 222 of the i-shaped aluminum filler 220.

Before performing surface treatment on the bezel 100, the aluminum filling material 220 and the antenna partition strip 300, performing heat treatment on the molded middle plate 210 and the aluminum filling material 220, wherein the heat treatment process mainly comprises the following steps:

Firstly, heating the middle plate 210 and the aluminum filling material 220 to 280-310 ℃, preserving heat for 80-120 min and cooling along with a furnace. The process is annealing treatment, and the annealing treatment can eliminate internal stress caused by uneven cooling speed when molten aluminum is crystallized and solidified.

secondly, after annealing treatment, the middle plate 210 and the filling aluminum material 220 cooled along with the furnace are heated to 700-800 ℃, the temperature is preserved for 180-200 min, and oil quenching cooling is adopted. The process is a quenching treatment, which can improve the internal metallographic structure and improve the mechanical strength and hardness of the middle plate 210 and the filling aluminum material 220.

Thirdly, heating the middle plate 210 and the aluminum filling material 220 after oil quenching cooling to 600-650 ℃, preserving heat for 150-170 min and naturally cooling in the air. The process is tempering treatment, namely immediate effect treatment, and the tempering treatment can eliminate intergranular and compositional segregation, so that the internal structures of the middle plate 210 and the aluminum filler 220 are homogenized.

After the connecting section 130 is formed, a plurality of grooves 110 are formed in one surface of the connecting section 130, which forms the inner surface of the frame 100, the cross section of each groove 110 can be in a trapezoidal or rectangular shape, the plurality of grooves 110 are arranged at intervals, or the plurality of grooves 110 can be communicated with each other, the depth of each groove 110 is 1mm-2mm, the grooves 110 can be formed through a laser etching process, specifically, the laser etching process adopts laser with the wavelength of 300nm-1200nm, the working current of 5A-15A and the power density of 100w/cm ² -105w/cm ², and the grooves 110 can also be formed through CNC machining.

after the groove 110 is processed, a plurality of nano-scale micropores 120 can be formed on the surface of the connecting section 130 forming the inner surface of the frame 100, wherein the depth of the micropores 120 is 0.1nm-0.4nm, and the pore diameter is 0.2nm-0.3 nm. Specifically, the frame 100 may be immersed in a specific chemical solution, which is etched on the inner surface to form the nano-scale micro-pores 120 in a honeycomb shape.

Because the groove 110 and the micro-hole 120 are formed on the connecting section 130, when the connecting section 130 is surrounded to form the frame 100 placed in the die-casting die cavity, the molten aluminum will penetrate into the groove 110 and the micro-hole 120, and after the molten aluminum is solidified to form the middle plate 210, the edge part 222 of the middle plate 210 will go deep into the frame 100, so that the middle plate 210 and the frame 100 form a dog-tooth staggered occlusion relationship, thereby improving the bonding force between the middle plate 210 and the frame 100 and ensuring the mechanical strength of the metal middle frame 10.

After the middle plate 210 and the filling aluminum material 220 are molded, surface treatment is performed on the bezel 100, the filling aluminum material 220, and the antenna partition strip 300, the surface treatment mainly including the steps of: first, the frame 100, the aluminum filler 220, and the antenna block strip 300 may be polished by a grinding wheel or the like, and the edge portion 222 of the frame 100 covered with the aluminum filler 220 may be removed, thereby removing the edges of the surfaces of the frame 100, the aluminum filler 220, and the antenna block strip 300, and the adhering substances such as dust. Then, the polished surface is subjected to a sand blasting treatment, for example, sand (such as silicon carbide, quartz sand, copper ore sand, or iron sand) is sprayed at a high speed onto the surfaces of the frame 100 and the aluminum filler 220 by compressed air, a certain roughness is formed on the surfaces of the frame 100 and the aluminum filler 220 by micro-cutting of the sand, and at the same time, the mechanical properties of the frame 100, the aluminum filler 220, and the antenna isolation strip 300 are improved by repeated impacts of the sand, thereby improving the fatigue resistance and wear resistance of the metal center 10. Blasting may be performed in two steps, a first blasting and a second blasting, the grit of the second blasting being smaller than the grit of the first blasting.

then, the whole metal middle frame 10 may be immersed in an alkali solution with a certain PH value, after the alkali solution is used to perform decontamination and degreasing on the rim 100 after sand blasting, the metal middle frame 10 is immersed in an acid solution, and the acid solution neutralizes the alkali solution attached to the metal middle frame 10, so as to perform subsequent anode treatment on the rim 100 and the aluminum filling material 220. Finally, the frame 100 and the aluminum filling material 220 are used as anodes and reacted in the electrolyte for a set time, so that an oxide film is formed on the outer surfaces of the frame 100 and the aluminum filling material 220, and the oxide film can be about 30 μm. Due to the action of the oxide film, the hardness and the wear resistance of the outer surface of the whole metal middle frame 10 are improved, and the service life of the metal middle frame 10 is prolonged. In some embodiments, the anodized frame 100 and the aluminum filler 220 may be dyed and sealed, so that the frame 100 and the aluminum filler 220 have different colors. Namely, pores are formed on the oxide film after the anodic treatment, the dye is filled into the pores, and finally the protective film is adopted for sealing the pores, so that the dye is prevented from overflowing from the pores.

The present invention also provides a metal middle frame 10, where the metal middle frame 10 includes a middle plate 210, a frame 100, a filling aluminum material 220, and an antenna partition strip 300. The metal middle frame 10 is manufactured by the metal middle frame processing method, so that the production cost of the metal middle frame 10 can be effectively reduced on the basis of ensuring the mechanical strength, the metal middle frame 10 is prevented from bending and deforming, and the forming quality of the metal middle frame 10 is ensured.

The invention also provides a mobile terminal which comprises the metal middle frame 10. As used herein, a "terminal" includes, but is not limited to, a device that is configured to receive/transmit communication signals via a wireline connection, such as via a Public Switched Telephone Network (PSTN), a Digital Subscriber Line (DSL), a digital cable, a direct cable connection, and/or another data connection/network, and/or via a wireless interface (e.g., for a cellular network, a Wireless Local Area Network (WLAN), a digital television network such as a DVB-H network, a satellite network, an AM-FM broadcast transmitter, and/or another communication terminal). Communication terminals arranged to communicate over a wireless interface may be referred to as "wireless communication terminals", "wireless terminals", and/or "mobile terminals". Examples of mobile terminals include, but are not limited to, satellite or cellular telephones; a Personal Communications System (PCS) terminal that may combine a cellular radiotelephone with data processing, facsimile and data communications capabilities; PDAs that may include radiotelephones, pagers, internet/intranet access, Web browsers, notepads, calendars, and/or Global Positioning System (GPS) receivers; and conventional laptop and/or palmtop receivers or other electronic devices that include a radiotelephone transceiver.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

the above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A metal middle frame machining method is characterized by comprising the following steps:

providing a plurality of connecting sections;

Injecting molten aluminum into and filling a cavity of the die-casting die through a die-casting treatment process, wherein part of the molten aluminum is solidified to form a middle plate integrally formed with the connecting sections, and the rest of the molten aluminum is filled into the gaps and solidified to form filled aluminum materials which connect the connecting sections in series;

2. The method of claim 1, wherein the antenna isolation bars are formed by an injection molding process.

3. the method of claim 1, wherein the perforations are formed using a laser drilling process or an electrical discharge drilling process.

4. The method of claim 1, wherein the cross-sectional shape of the through-hole is kidney-shaped, oval, or rectangular.

5. The method for processing the metal middle frame according to claim 1, wherein the number of the connecting sections is four, two of the connecting sections are C-shaped connecting sections, and the other two connecting sections are I-shaped connecting sections; in the die-casting die, one linear connecting section is positioned between one ends of the two C-shaped connecting sections, and the other linear connecting section is positioned between the other ends of the two C-shaped connecting sections.

6. The metal center processing method according to claim 1, wherein, before the step of subjecting the peripheral frame and the aluminum filler to the surface treatment, end portions of the aluminum filler extend in a direction perpendicular to the gap and cover opposite sides of the annular frame.

7. The metal middle frame processing method according to claim 1, wherein the die-casting treatment process comprises the following steps:

Preheating a cavity of the die-casting die to 200-250 ℃;

Injecting molten aluminum into a cavity of the die-casting die at a speed of 0.5-0.8 m/s, wherein the die-casting pressure is 80-85 MPa;

when the filling rate of the cavity of the die-casting die is higher than 70%, the injection speed of molten aluminum is 1-1.5 m/s, and the die-casting pressure is 90-100 Pa; and

And when the die cavity of the die-casting die is completely filled, keeping the pressure for 2-3 min and cooling for forming.

8. The method as claimed in claim 1, wherein in the step of providing the connection section, a plurality of grooves are formed on a surface of the connection section forming the inner surface of the rim by a laser etching process, and the depth of the grooves is 1mm to 2 mm.

9. the method as claimed in claim 8, wherein after the grooves are processed by the laser etching process, the inner surface of the connection segment is processed by the nano-treatment process to form micro-holes with a depth of 0.1nm to 0.4nm and a diameter of 0.2nm to 0.3 nm.

10. The method for processing the metal middle frame according to claim 1, wherein the formed middle plate and the aluminum filler are subjected to a heat treatment before the surface treatment is performed on the side frame and the aluminum filler, and the heat treatment comprises the following steps:

heating the middle plate and the filling aluminum material to 280-310 ℃, preserving heat for 80-120 min, and cooling along with the furnace;

heating the middle plate and the aluminum filling material cooled along with the furnace to 700-800 ℃, preserving the heat for 180-200 min and cooling by adopting oil quenching; and

Heating the oil-quenched and cooled middle plate and the filled aluminum material to 600-650 ℃, preserving heat for 150-170 min, and naturally cooling in the air.

11. A metal middle frame, characterized in that it is manufactured by the method of any one of claims 1 to 10.

12. A mobile terminal characterized by comprising the metal bezel of claim 11.