阅读说明：本技术 钨海绵基体浸铜方法及装置 (Method and device for soaking copper in tungsten sponge matrix ) 是由 刘燕文 �田宏 李芬 朱虹 王国建 赵恒邦 王小霞 于 2021-09-17 设计创作，主要内容包括：本公开提供一种钨海绵基体浸铜方法及装置,方法包括：将浸铜装置抽真空至第一真空度,排出空气；充入惰性气体,保持真空度为第二真空度；加热熔融无氧铜,将钨海绵基体浸入液体铜中保持时间T后取出；其中,惰性气体与无氧铜和钨不发生化学反应,第二真空度大于第一真空度,在第二真空度下,液体铜不蒸发。本公开通过先将浸铜装置抽真空,可以排出钨海绵基体孔隙中的空气,然后再向浸铜装置中通入适量氢气,使浸铜装置内部呈现一种低真空状态,以抑制熔融铜的蒸发,最终使得铜液可以均匀地浸入钨海绵基体中,大大减少了因难以浸透钨海绵基体而造成的阴极基体车制过程中出现的孔洞,提高了所制备阴极的性能。(The invention provides a method and a device for copper dipping of a tungsten sponge matrix, wherein the method comprises the following steps: vacuumizing the copper leaching device to a first vacuum degree, and exhausting air; filling inert gas, and keeping the vacuum degree to be a second vacuum degree; heating and melting the oxygen-free copper, immersing the tungsten sponge matrix into the liquid copper for a time T, and taking out; wherein the inert gas does not chemically react with the oxygen-free copper and the tungsten, the second vacuum degree is greater than the first vacuum degree, and the liquid copper does not evaporate under the second vacuum degree. According to the method, the copper soaking device is firstly vacuumized, the air in the pores of the tungsten sponge matrix can be discharged, then a proper amount of hydrogen is introduced into the copper soaking device, so that the interior of the copper soaking device is in a low vacuum state to inhibit the evaporation of molten copper, and finally, copper liquid can be uniformly soaked in the tungsten sponge matrix, so that the holes in the turning process of the cathode matrix caused by difficulty in soaking the tungsten sponge matrix are greatly reduced, and the performance of the prepared cathode is improved.)

1. A method for copper impregnation of a tungsten sponge matrix is characterized by comprising the following steps:

vacuumizing the copper leaching device to a first vacuum degree, and exhausting air;

filling inert gas, and keeping the vacuum degree to be a second vacuum degree;

heating and melting the oxygen-free copper, immersing the tungsten sponge matrix into the liquid copper for a time T, and taking out;

and the inert gas does not react with oxygen-free copper and tungsten chemically, the second vacuum degree is greater than the first vacuum degree, and liquid copper is not evaporated under the second vacuum degree.

2. The method of claim 1, wherein the first vacuum is less than or equal to 5 x 10^-4Pa, and the second vacuum degree is 1Pa to 1000 Pa.

3. The method for copper impregnation of a tungsten sponge substrate according to claim 1, wherein the temperature for heating and melting the oxygen-free copper is 1350 ℃ to 1650 ℃.

4. The method for copper impregnation of a tungsten sponge substrate according to claim 1, wherein the time T is 1-5 hours.

5. The method for copper impregnation of a tungsten sponge substrate according to claim 1, wherein before the step of evacuating the copper impregnation apparatus to the first vacuum level, the method further comprises:

placing the oxygen-free copper and the tungsten sponge matrix into the copper leaching device;

wherein the copper leaching device is a vacuum heating furnace, and the weight of the oxygen-free copper is 20-200% of that of the tungsten sponge matrix.

6. The method according to claim 5, wherein the oxygen-free copper is placed in a crucible, and the crucible and the tungsten sponge substrate are placed in a vacuum chamber of the vacuum heating furnace separately from each other;

heating and melting the oxygen-free copper by heating the crucible.

7. The method for copper impregnation of a tungsten sponge substrate as claimed in claim 6, wherein the oxygen-free copper is placed in a metal crucible of tungsten or molybdenum or a graphite crucible.

8. The method for copper impregnation of a tungsten sponge substrate according to claim 1, wherein the oxygen-free copper is melted by induction heating, resistance wire heating or electron beam heating.

9. The method for copper impregnation of a tungsten sponge substrate according to claim 1, characterized in that nitrogen or hydrogen is filled as the inert gas.

10. A tungsten sponge matrix copper leaching device is characterized by comprising:

the vacuum cavity (1) is used for providing a vacuum environment for copper leaching of the tungsten sponge matrix;

the lifting mechanism (5) is used for driving the tungsten sponge matrix to be immersed in and separated from the liquid copper;

a high vacuum pump unit (8) for evacuating the vacuum chamber (1);

a ventilating device (9) for ventilating inert gas into the vacuum cavity (1);

wherein the high vacuum pump unit (8) and the air breather (9) are also used for adjusting the vacuum degree in the vacuum cavity (1), removing air in the tungsten sponge matrix and controlling the liquid copper not to evaporate.

Technical Field

The disclosure relates to the technical field of microwave vacuum electronic devices, in particular to a method and a device for copper dipping of a tungsten sponge matrix.

Background

The microwave vacuum electronic device is widely applied to radar, satellite communication, electron accelerators, global positioning, controllable thermonuclear fusion, future military leading-edge high-power microwave weapons and the like, and has unique functions and excellent performance, and particularly under the conditions of high power and high frequency band, the microwave vacuum electronic device cannot be replaced by other devices. The cathode serving as electron emission is the most central part in a microwave vacuum electronic device, the performance of the cathode directly influences the output performance and the service life of a microwave source, and further influences the performance and the service life of a satellite and a high-power microwave device, the cathode emission performance is an important index of the microwave vacuum electronic device, and the research on the performance of a cathode matrix, an emission substance and a cathode coating film requires a copper soaking method and a copper soaking device for conveniently and reliably soaking the cathode matrix.

In the prior art, a tungsten sponge substrate blank is usually wrapped by a clean oxygen-free copper sheet, then buried in a molybdenum boat paved with alumina powder, and then put into a hydrogen furnace for soaking with continuous hydrogen.

However, when the copper immersion treatment is performed on the tungsten sponge matrix by adopting the method, the capillary lines at the edge of the tungsten sponge framework are mostly in a linear shape due to the pressing process, and the bending degree is lower than that of the capillary tubes in the framework, so that the melting immersion path of the capillary tubes at the edge of the framework is much shorter than that in the framework, and the rising rate along the edge of the framework is high. Therefore, after the molten metal is completely molten, the molten metal liquid instantly melts and soaks the surface of the framework along the edge of the framework, so that the capillary at the part is filled with the molten metal, and because the molten metal speed is poor, part of the capillary in the framework is filled with gas, so that a molten and soaked black core is formed, the turning performance of the tungsten sponge matrix is poor, and holes are formed on the surface of the cathode matrix. The cathode prepared by adopting the tungsten sponge matrix influences parameters such as the emission performance, the evaporation performance, the service life of the cathode and the like.

Disclosure of Invention

Technical problem to be solved

Aiming at the prior technical problems, the disclosure provides a method and a device for copper dipping of a tungsten sponge matrix, which are used for at least partially solving the technical problems.

(II) technical scheme

The invention provides a method for copper impregnation of a tungsten sponge matrix, which comprises the following steps: vacuumizing the copper leaching device to a first vacuum degree, and exhausting air; filling inert gas, and keeping the vacuum degree to be a second vacuum degree; heating and melting the oxygen-free copper, immersing the tungsten sponge matrix into the liquid copper for a time T, and taking out; wherein the inert gas does not chemically react with the oxygen-free copper and the tungsten, the second vacuum degree is greater than the first vacuum degree, and the liquid copper does not evaporate under the second vacuum degree.

Optionally, the first degree of vacuum is equal to or less than 5 × 10^-4Pa, and the second vacuum degree is 1Pa to 1000 Pa.

Alternatively, the temperature at which the oxygen-free copper is heated and melted is 1350 ℃ to 1650 ℃.

Optionally, the time T is 1h to 5 h.

Optionally, before the step of evacuating the copper leaching device to the first vacuum degree, the method for copper leaching of the tungsten sponge matrix further comprises the following steps: placing the oxygen-free copper and the tungsten sponge matrix into a copper leaching device; wherein, the copper leaching device is a vacuum heating furnace, and the weight of the oxygen-free copper is 20-200% of that of the tungsten sponge matrix.

Optionally, placing oxygen-free copper into a crucible, and then placing the crucible and the tungsten sponge matrix into a vacuum cavity of a vacuum heating furnace separately from each other; the oxygen-free copper is heated and melted by heating the crucible.

Alternatively, oxygen-free copper is placed in a metal or graphite crucible of tungsten or molybdenum.

Optionally, the oxygen-free copper is melted using induction heating, resistance wire heating, or electron beam heating.

Alternatively, nitrogen or hydrogen is filled as an inert gas.

Another aspect of the present disclosure provides a device for copper immersion of a tungsten sponge substrate, including: the vacuum cavity 1 is used for providing a vacuum environment for copper leaching of the tungsten sponge matrix; the lifting mechanism 5 is used for driving the tungsten sponge matrix to be immersed in and separated from the liquid copper; the high vacuum pump unit 8 is used for vacuumizing the vacuum cavity 1; a ventilating device 9 for ventilating inert gas into the vacuum cavity 1; wherein, the high vacuum pump unit 8 and the ventilation device 9 are also used for adjusting the vacuum degree in the vacuum cavity 1, removing air in the tungsten sponge matrix and controlling liquid copper not to evaporate.

(III) advantageous effects

The invention provides a copper dipping method for a tungsten sponge matrix, which comprises the steps of vacuumizing a copper dipping device to exhaust air in pores of the tungsten sponge matrix, introducing a proper amount of hydrogen into the copper dipping device to enable the interior of the copper dipping device to be in a low vacuum state so as to inhibit evaporation of molten copper, and finally enabling copper liquid to be uniformly dipped into the tungsten sponge matrix, so that holes in a cathode matrix turning process caused by difficulty in dipping the tungsten sponge matrix are greatly reduced, and the emission performance, the evaporation performance, the service life of a cathode and other parameters of the prepared cathode are improved.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a structure of a copper immersion device for a tungsten sponge matrix according to an embodiment of the disclosure;

FIG. 2 schematically illustrates a flow chart of a method for copper impregnation of a tungsten sponge matrix according to an embodiment of the disclosure;

FIG. 3 schematically illustrates a flow chart of a method for copper impregnation of a tungsten sponge matrix according to another embodiment of the disclosure;

FIG. 4 schematically illustrates a surface topography of a cathode substrate prepared according to a conventional method of embodiments of the present disclosure;

fig. 5 schematically illustrates a surface topography of a vacuum-fabricated cathode substrate according to an embodiment of the present disclosure.

[ description of reference ]

1-vacuum Chamber

2-heating body

3-oxygen free copper

4-vacuum cover plate

5-lifting mechanism

6-tungsten sponge matrix

7-crucible

8-high vacuum pump unit

9-aeration device

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

It should be noted that in the drawings or description, the same drawing reference numerals are used for similar or identical parts. Features of the embodiments illustrated in the description may be freely combined to form new embodiments without conflict, and each claim may be individually referred to as an embodiment or features of the claims may be combined to form a new embodiment, and in the drawings, the shape or thickness of the embodiment may be enlarged and simplified or conveniently indicated. Further, elements or implementations not shown or described in the drawings are of a form known to those of ordinary skill in the art. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints.

Unless a technical obstacle or contradiction exists, the above-described various embodiments of the present disclosure may be freely combined to form further embodiments, which are all within the scope of protection of the present disclosure.

While the present disclosure has been described in connection with the accompanying drawings, the embodiments disclosed in the drawings are intended to be illustrative of the preferred embodiments of the disclosure, and should not be construed as limiting the disclosure. The dimensional proportions in the drawings are merely schematic and are not to be understood as limiting the disclosure.

Although a few embodiments of the present general inventive concept have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the claims and their equivalents.

Fig. 1 schematically shows a structure diagram of a tungsten sponge matrix copper leaching device according to an embodiment of the disclosure.

According to the embodiment of the disclosure, as shown in fig. 1, the tungsten sponge matrix copper leaching device comprises: the device comprises a vacuum cavity 1, a heating body 2, oxygen-free copper 3, a vacuum cover plate 4, a lifting mechanism 5, a tungsten sponge base body 6, a crucible 7, a high vacuum pump unit 8 and a ventilation device 9. The copper immersion apparatus may be, for example, a vacuum high-temperature furnace in which a vacuum chamber 1 for accommodating a crucible 7, an elevating mechanism 5, and the like provides a vacuum environment for copper immersion of a tungsten sponge substrate. The heating body 2 is used for heating the oxygen-free copper and the tungsten sponge matrix in the crucible 7. The lifting mechanism 5 is, for example, in a sealed slidable connection with the vacuum cover plate 4, so that the lifting mechanism 5 can drive the tungsten sponge matrix 6 to move up and down, and to be immersed in and separated from the molten liquid copper. The lifting mechanism 5 may be partially fixed in the vacuum chamber 1, for example, and may move the tungsten sponge base 6 up and down by rotating and pulling, for example. The high vacuum pump assembly 8 is used for evacuating the vacuum chamber 1. And a ventilating device 9 for ventilating inert gas into the vacuum chamber 1. By using the high vacuum pump unit 8 and the ventilation device 9 in a matching manner, the vacuum degree in the vacuum cavity 1 can be adjusted, air in the tungsten sponge matrix is removed, and the liquid copper is controlled not to be evaporated, so that the copper liquid can be uniformly immersed in the tungsten sponge matrix, and holes in the cathode matrix vehicle manufacturing process caused by the fact that the tungsten sponge matrix is difficult to soak are greatly reduced.

Fig. 2 schematically illustrates a flow chart of a method for copper impregnation of a tungsten sponge matrix according to an embodiment of the disclosure.

According to an embodiment of the present disclosure, as shown in fig. 2, a method for copper impregnation of a tungsten sponge substrate includes, for example:

s210, placing the oxygen-free copper and tungsten sponge matrix into a copper soaking device.

According to the embodiment of the disclosure, the copper leaching device is a vacuum heating furnace. For example, oxygen-free copper is placed in a crucible, and the crucible and the tungsten sponge base body are placed in a vacuum chamber of a vacuum heating furnace separately from each other. The weight of the oxygen-free copper is, for example, 20% to 200% of the weight of the tungsten sponge matrix 6. The crucible 7 is, for example, a metal crucible or a graphite crucible which can withstand a high temperature of at least 1700 ℃.

And S220, vacuumizing the copper leaching device to a first vacuum degree, and exhausting air.

According to an embodiment of the present disclosure, the air in the vacuum chamber 1 is pumped out, for example, using the high vacuum pump assembly 8 until the degree of vacuum in the vacuum chamber 1 reaches 5 × 10^-4pa or less, the higher the vacuum degree is, the more beneficial to improving the effect of later-stage copper leaching. At this time, the vacuum chamber 1 is in a high vacuum state, and air in the pores of the tungsten sponge base 6 is also evacuated.

And S230, filling inert gas, and keeping the vacuum degree to be a second vacuum degree.

According to the embodiment of the disclosure, after the vacuum chamber 1 is vacuumized, nitrogen, hydrogen or other inert gases which do not chemically react with oxygen-free copper and tungsten are filled into the vacuum chamber 1 through the ventilation device 9, so that the vacuum degree is kept between 1Pa and 1000Pa, at the moment, the vacuum chamber 1 is in a low vacuum state, evaporation of molten copper can be inhibited, and because the vacuum chamber 1 is still in the vacuum state, the inert gases are difficult to enter pores of the tungsten sponge matrix 6, few gases exist in the pores of the cathode tungsten sponge matrix, so that the copper cannot be uniformly immersed into each pore in the tungsten sponge matrix due to gas resistance, and the immersion time is greatly shortened. Thus, the molten liquid copper can be rapidly and uniformly immersed in the tungsten sponge matrix 6.

S240, heating and melting the oxygen-free copper, immersing the tungsten sponge matrix into the liquid copper for a holding time T, and taking out. Wherein the inert gas does not chemically react with the oxygen-free copper and the tungsten, the second vacuum degree is greater than the first vacuum degree, and the liquid copper does not evaporate under the second vacuum degree.

According to embodiments of the present disclosure, the oxygen-free copper is heated and melted, for example, by heating a crucible. The heating means is, for example, induction heating, resistance wire heating or electron beam heating. After heating and melting the oxygen-free copper, the tungsten sponge matrix 6 is moved downwards and immersed into the liquid copper by adjusting the lifting mechanism 5, the holding time T is kept for 1 to 5 hours according to the size of the tungsten sponge matrix 6, and then the lifting mechanism 5 is adjusted to move the tungsten sponge matrix 6 upwards and away from the liquid copper, so that the copper immersion of the tungsten sponge matrix is completed.

According to an embodiment of the present disclosure, the heating temperature of the vacuum chamber 1 is, for example, between 1350 ℃ and 1650 ℃. When the heating temperature is below 1350 deg.c, the copper in the crucible cannot completely infiltrate into the tungsten sponge matrix. At temperatures above 1650 c, however, the evaporation of oxygen-free copper is very severe and the maintenance of the vacuum atmosphere in the vacuum chamber is compromised, thereby compromising the control of the copper leaching process. In addition, too high infiltration temperature can cause large copper shrinkage during cooling, and the compactness of the alloy is influenced. This is because the liquid state shrinkage and solidification shrinkage values of the metal larger than the solid state shrinkage value are the root cause of the generation of shrinkage cavities. The higher the infiltration temperature, the longer the liquid state shrinkage time, and the larger the shrinkage cavity volume becomes.

Fig. 3 schematically shows a flow chart of a method for copper impregnation of a tungsten sponge matrix according to another embodiment of the disclosure.

According to an embodiment of the present disclosure, as shown in fig. 3, a method for copper impregnation of a tungsten sponge substrate includes, for example:

s310, placing the oxygen-free copper 3 into the crucible 7, and suspending the tungsten sponge matrix 6 on the vacuum cover plate 4.

S320, utilizing the high vacuum pump unit 8 to vacuumize the vacuum cavity 1 to 5 multiplied by 10^-4pa or less.

S330, filling nitrogen, hydrogen or other inert gases which do not chemically react with oxygen-free copper and tungsten, keeping the vacuum degree between 1Pa and 1000Pa, heating the tungsten sponge matrix 6 and the crucible 7 to 1350 ℃ to 1650 ℃ through the heating body 2, keeping the temperature, heating and melting the oxygen-free copper 3 in the crucible 7, immersing the tungsten sponge matrix 6 into oxygen-free copper liquid in the crucible 7 by using the lifting mechanism 5, keeping the temperature for 2 hours for example, and immersing the copper into the tungsten sponge matrix 6.

And S340, lifting the tungsten sponge matrix soaked with the oxygen-free copper away from the liquid level of the oxygen-free copper so as to prevent the tungsten sponge matrix from being bonded together by the oxygen-free copper after cooling.

And S350, after the vacuum cavity 1 and the tungsten sponge matrix are cooled to room temperature, recovering the vacuum cavity 1 to normal pressure, opening the vacuum cover plate 4, taking out the tungsten sponge matrix, and finishing the copper soaking treatment of the tungsten sponge matrix.

In the art, room temperature generally means 20 ℃ to 30 ℃ and atmospheric pressure means 1.013X 10⁵Pa。

The technical solution of the present disclosure will be described in detail below with reference to specific examples. It should be noted that the following specific examples are only for illustration and are not intended to limit the disclosure.

Comparative example 1

A method of copper impregnation of a tungsten sponge, for example comprising the steps of:

step A, placing oxygen-free copper 3 into a crucible 7, and suspending a tungsten sponge matrix 6 on a cover plate 4 of a vacuum chamber.

And step B, filling hydrogen to ensure that the pressure in the cavity is greater than the normal pressure, heating the tungsten sponge matrix 6 and the crucible 7 to 1550 ℃ through the heating body 2 so as to heat and melt the oxygen-free copper in the crucible, immersing the tungsten sponge matrix 6 into the oxygen-free copper liquid in the crucible 7 by using the lifting mechanism 5, and preserving heat for 5 hours to immerse the copper into the tungsten sponge matrix.

And step C, lifting the tungsten sponge matrix soaked with the oxygen-free copper away from the liquid level of the oxygen-free copper so as to prevent the tungsten sponge matrix from being bonded together by the oxygen-free copper after cooling.

And D, stopping filling hydrogen after the hydrogen chamber and the tungsten sponge matrix are cooled to room temperature, opening a hydrogen chamber cover, taking out the tungsten sponge matrix, and finishing copper soaking treatment of the tungsten sponge matrix.

The test results are shown in table 1.

TABLE 1 impregnation of copper for 5 hours at 1550 ℃ under hydrogen

The average value of the impregnation rate was calculated to be 92.38%.

Fig. 4 schematically illustrates a surface topography of a cathode substrate prepared according to a conventional method of embodiments of the present disclosure.

According to the embodiment of the present disclosure, the tungsten sponge matrix is impregnated with copper in a hydrogen furnace by passing through hydrogen gas, the copper is difficult to impregnate the tungsten sponge matrix, and the prepared cathode matrix has a plurality of pores which are not impregnated with copper and are more enclosed by dotted circles in fig. 4.

Example 1

A method of copper impregnation of a tungsten sponge, for example comprising the steps of:

step A, placing oxygen-free copper 3 into a crucible 7, and suspending a tungsten sponge matrix 6 on a vacuum cover plate 4.

And step B, utilizing a high vacuum pump unit 8 to vacuumize the vacuum cavity 1 to 5 multiplied by 10pa or below.

And step C, filling nitrogen, hydrogen or other inert gases which do not chemically react with the oxygen-free copper and the tungsten, keeping the vacuum degree between 1Pa and 1000Pa, heating the tungsten sponge matrix 6 and the crucible 7 to 1550 ℃ through the heating body 2 so as to heat and melt the oxygen-free copper in the crucible, immersing the tungsten sponge matrix 6 into the oxygen-free copper liquid in the crucible 7 by using the lifting mechanism 5, and preserving the heat for 5 hours so as to immerse the copper into the tungsten sponge matrix.

And D, lifting the tungsten sponge matrix soaked with the oxygen-free copper away from the liquid level of the oxygen-free copper so as to prevent the tungsten sponge matrix from being bonded together by the oxygen-free copper after cooling.

And E, after the vacuum cavity and the tungsten sponge matrix are cooled to room temperature, restoring the vacuum cavity to normal pressure, opening the vacuum cover plate 4, taking out the tungsten sponge matrix, and finishing the copper leaching treatment of the tungsten sponge matrix.

The test results are shown in table 2.

TABLE 2 immersion of copper at 1550 deg.C for 5 hours under vacuum

The average value of the impregnation rate was calculated to be 96.79%.

As can be seen from Table 2, under the same copper leaching temperature and time, the vacuum copper leaching impregnation rate can reach more than 96 percent, which is much higher than the impregnation rate of 92.38 percent of hydrogen copper leaching in Table 1, and the impregnation rate is improved by more than 4 percent.

Fig. 5 schematically illustrates a surface topography of a vacuum-fabricated cathode substrate according to an embodiment of the present disclosure.

According to the embodiment of the disclosure, as shown in fig. 5, by immersing the tungsten sponge substrate in copper in a vacuum environment, the copper can uniformly fill the tungsten sponge substrate, so that the turning performance of the tungsten sponge substrate is very good, and no hole appears on the surface of the cathode substrate.

In summary, the embodiment of the present disclosure provides a method for copper-dipping a tungsten sponge substrate. The oxygen-free copper and the tungsten sponge substrate are heated by the heating body in a vacuum environment, so that the oxygen-free copper is immersed into the tungsten sponge substrate. The method is simple and easy to implement, low in cost, good in copper leaching effect and good in application prospect.

The product embodiment is similar to the method embodiment in portions where details are not given, and please refer to the method embodiment, which is not described herein again.

It should be understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", etc., mentioned in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. And the shapes, sizes and positional relationships of the components in the drawings do not reflect the actual sizes, proportions and actual positional relationships.

In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, the disclosure may lie in less than all features of a single disclosed embodiment. Thus, the following claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the disclosure.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present disclosure, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise. To the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.