阅读说明：本技术 一种测量不同冷速下合金凝固行为的装置及方法 (Device and method for measuring alloy solidification behaviors at different cooling speeds ) 是由 黄锋 朱黎明 郭逊 梁思诚 于 2020-12-16 设计创作，主要内容包括：一种测量不同冷速下合金凝固行为的装置及方法。测量不同冷速下合金凝固行为的装置包括内设有模腔的石墨模具、用于开闭模腔的石墨模具盖、套设于石墨模具外壁的水冷缸套、分别设于石墨模具盖顶面和石墨模具底面的上石棉毡和下石棉毡、多个热电偶及用于接收热电偶检测信号的温度采集系统,模腔由多个横截面积不同的圆柱形的检测腔依次同轴连通组成,每个检测腔内均设有测温点,每个测温点沿对应检测腔的径向与石墨模具内壁之间的距离相等,每个测温点与对应检测腔顶面和底面的距离均相等,热电偶分别用于对各个测温点的合金温度进行检测。测量不同冷速下合金凝固行为的装置及方法能够在同一实验过程中对不同冷却速度下凝固的合金进行检测。(A device and a method for measuring alloy solidification behaviors at different cooling speeds. The device for measuring the alloy solidification behavior at different cooling speeds comprises a graphite mold internally provided with a mold cavity, a graphite mold cover for opening and closing the mold cavity, a water-cooling cylinder sleeve sleeved on the outer wall of the graphite mold, an upper asbestos felt and a lower asbestos felt which are respectively arranged on the top surface of the graphite mold cover and the bottom surface of the graphite mold, a plurality of thermocouples and a temperature acquisition system for receiving thermocouple detection signals, wherein the mold cavity is formed by sequentially and coaxially communicating a plurality of cylindrical detection cavities with different cross sectional areas, each detection cavity is internally provided with a temperature measurement point, each temperature measurement point is equal to the distance between the inner wall of the graphite mold along the radial direction of the corresponding detection cavity, each temperature measurement point is equal to the distance between the top surface and the bottom surface of the corresponding detection cavity, and the thermocouples are respectively used for detecting. The device and the method for measuring the alloy solidification behavior at different cooling speeds can detect the alloys solidified at different cooling speeds in the same experiment process.)

1. A device for measuring the alloy solidification behavior at different cold speeds is characterized by comprising a graphite mold, a graphite mold cover, a water-cooling cylinder sleeve, an upper asbestos felt, a lower asbestos felt, a plurality of thermocouples and a temperature acquisition system, wherein the graphite mold is internally provided with a mold cavity, the graphite mold cover is used for opening and closing the mold cavity, the water-cooling cylinder sleeve is sleeved on the outer wall of the graphite mold, the upper asbestos felt and the lower asbestos felt are respectively arranged on the top surface of the graphite mold cover and the bottom surface of the graphite mold, the temperature acquisition system is used for receiving detection, the die cavity is formed by sequentially and coaxially communicating a plurality of cylindrical detection cavities, the cross sections of the detection cavities are different in area, temperature measurement points are arranged in each detection cavity, the distance between each temperature measurement point and the inner wall of the graphite die along the radial direction corresponding to the detection cavity is equal, the distance between each temperature measurement point and the top surface and the bottom surface corresponding to the detection cavity is equal, and the thermocouples are respectively used for detecting the alloy temperature of each temperature measurement point.

2. The apparatus for measuring the alloy solidification behavior at different cooling rates according to claim 1, wherein the die cavity is composed of a plurality of detection cavities with gradually increasing cross-sectional areas from bottom to top, which are sequentially and coaxially communicated.

3. The device for measuring alloy solidification behavior at different cooling rates as recited in claim 1, wherein the thermocouple is disposed through the graphite mold cover and the upper asbestos felt, a fastening rubber ring is sleeved on the thermocouple, and the bottom of the fastening rubber ring is pressed against the top of the upper asbestos felt.

4. The apparatus for measuring alloy solidification behavior at different cooling rates as set forth in claim 1, wherein the vertical projection of the mold cavity is located within the upper and lower asbestos blankets.

5. The device for measuring the alloy solidification behavior at different cooling rates as recited in claim 1, wherein a cooling cavity and a spiral cooling water channel are arranged in the water-cooled cylinder sleeve, the cooling water channel is communicated with a water inlet, and the cooling cavity is communicated with a water outlet.

6. The device for measuring the alloy solidification behavior at different cooling rates as recited In claim 5, wherein Ga-In-Sn cooling liquid is arranged between the graphite mold and the water-cooled cylinder sleeve.

7. The device for measuring the alloy solidification behavior at different cooling rates as recited In claim 6, wherein the bottom of the graphite mold is expanded outwards to form a convex portion, the bottom of the water-cooled cylinder sleeve is recessed inwards to form a concave portion, the convex portion and the concave portion are connected through threads, the Ga-In-Sn cooling liquid is filled between the outer wall of the top of the graphite mold and the inner wall of the top of the water-cooled cylinder sleeve, and a sealing gasket is arranged on the top surface of the convex portion.

8. A method for measuring the solidification behavior of an alloy at different cooling rates by using the apparatus for measuring the solidification behavior of an alloy at different cooling rates according to claim 1, comprising the steps of:

introducing cooling water into the water-cooled cylinder sleeve, pouring molten alloy melt into the mold cavity after cooling water flows out of a water outlet of the water-cooled cylinder sleeve, and receiving temperature change in the alloy cooling process detected by each thermocouple through the temperature acquisition system to obtain an alloy solidification cooling curve;

after the alloy is cooled to room temperature, taking out the alloy cast ingot, sampling near the temperature measuring point of each thermocouple, and analyzing the solidification structure characteristics of each sample;

and (4) integrating the solidification structure characteristics of each sample and the corresponding alloy solidification cooling curve characterization results, and analyzing the solidification behaviors of the alloy at different cooling speeds.

Technical Field

The application relates to the field of alloy solidification, in particular to a device and a method for measuring alloy solidification behaviors at different cooling speeds.

Background

In the manufacturing process of metal materials, solidification of the metal materials has always been one of the most fundamental and important links. Under the premise of definite alloy components, the performance of a casting or an ingot mainly depends on the solidification structure of the alloy, and the cooling speed is an important factor influencing the nucleation and growth in the solidification process of the alloy. Therefore, in order to obtain an ideal solidification structure, the solidification behavior of the alloy at different cooling rates needs to be studied to establish the internal relation between the cooling rate and the corresponding alloy solidification structure in the solidification process, and to clear the range (window) of the solidification cooling rate to be adopted for obtaining a certain solidification structure for the corresponding alloy.

Currently, most laboratories adopt a method that after a target alloy is smelted, a corresponding process is adopted to carry out solidification at a certain cooling speed, and the corresponding solidification behavior of the alloy at the cooling speed is analyzed by combining an alloy cooling curve test and corresponding solidification structure characterization in the solidification process. To analyze the influence of the cooling rate on the solidification behavior of the alloy, the experiment needs to be repeated at different cooling rates, and the experiment period is long and the cost is high. In addition, it is difficult to repeat the above experiments at different cooling rates to achieve the same conditions of other factors, i.e. the experimental results inevitably contain the influence of other factors.

Disclosure of Invention

The device and the method for measuring the alloy solidification behavior at different cooling speeds can detect the solidified alloys at different cooling speeds in the same experiment process, are beneficial to shortening the experiment period, save the experiment cost and improve the accuracy and the reliability of the analysis result.

The embodiment of the application is realized as follows:

the embodiment of the application provides a measure device of alloy solidification action under different cooling rates, it is equipped with the graphite jig of die cavity in including, a graphite jig lid for switching die cavity, the water-cooling cylinder liner of graphite jig outer wall is located to the cover, locate graphite jig lid top surface and graphite jig bottom surface respectively last asbestos felt and lower asbestos felt, a plurality of thermocouples and be used for receiving the temperature acquisition system of thermocouple detected signal, the die cavity comprises a plurality of columniform detection chambeies coaxial intercommunication in proper order, the area of each detection chamber's cross section is different, every detection intracavity all is equipped with the temperature measurement point, every temperature measurement point is equal along the radial distance between the graphite jig inner wall that corresponds the detection chamber, every temperature measurement point is equal with the distance that corresponds detection chamber top surface and bottom surface, a plurality of thermocouples are used for detecting the alloy temperature of each temperature measurement point respectively.

In some alternative embodiments, the mold cavity is composed of a plurality of detection cavities with gradually increasing cross-sectional areas from bottom to top, which are sequentially communicated coaxially.

In some alternative embodiments, the thermocouple is arranged through the graphite mold cover and the upper asbestos felt, a fastening rubber ring is sleeved on the thermocouple, and the bottom of the fastening rubber ring is pressed against the top of the upper asbestos felt.

In some alternative embodiments, the projections of the mold cavities in the vertical direction are located within the upper and lower asbestos mats.

In some optional embodiments, a cooling cavity and a spiral cooling water channel are arranged in the water-cooled cylinder sleeve, the cooling water channel is communicated with a water inlet, and the cooling cavity is communicated with a water outlet.

In some optional embodiments, Ga-In-Sn cooling liquid is arranged between the graphite die and the water-cooling cylinder sleeve.

In some optional embodiments, the bottom of the graphite mold expands outwards to form a convex part, the bottom of the water-cooling cylinder sleeve is sunken inwards to form a concave part, the convex part and the concave part are connected through threads, Ga-In-Sn cooling liquid is filled between the outer wall of the top of the graphite mold and the inner wall of the top of the water-cooling cylinder sleeve, and a sealing gasket is arranged on the top surface of the convex part.

The application also provides a method for measuring the alloy solidification behaviors at different cooling speeds, which is carried out by using the device for measuring the alloy solidification behaviors at different cooling speeds, and comprises the following steps:

introducing cooling water into the water-cooled cylinder sleeve, pouring molten alloy melt into the die cavity after cooling water flows out from a water outlet of the water-cooled cylinder sleeve, and receiving temperature change in the alloy cooling process detected by each thermocouple through a temperature acquisition system to obtain an alloy solidification cooling curve;

after the alloy is cooled to room temperature, taking out the alloy cast ingot, sampling near the temperature measuring point of each thermocouple, and analyzing the solidification structure characteristics of each sample;

and (4) integrating the solidification structure characteristics of each sample and the corresponding alloy solidification cooling curve characterization results, and analyzing the solidification behaviors of the alloy at different cooling speeds.

The beneficial effect of this application is: the device of the different cooling rates of measurement lower alloy solidification action that this embodiment provided is equipped with the graphite jig of die cavity in including, a graphite jig lid for switching die cavity, the water-cooling cylinder liner of graphite jig outer wall is located to the cover, locate graphite jig lid top surface and graphite jig bottom surface respectively last asbestos felt and lower asbestos felt, a plurality of thermocouples and be used for receiving the temperature acquisition system of thermocouple detected signal, the die cavity comprises a plurality of columniform detection chambeies coaxial intercommunication in proper order, the area of each detection chamber's cross section is different, every detection intracavity all is equipped with the temperature measurement point, every temperature measurement point is equal along the radial distance between the graphite jig inner wall that corresponds the detection chamber, every temperature measurement point is equal with the distance homogeneous phase that corresponds detection chamber top surface and bottom surface, a plurality of thermocouples are used for detecting the alloy temperature of each temperature measurement point respectively. The device and the method for measuring the alloy solidification behavior at different cooling speeds provided by the embodiment can be used for detecting the alloy solidified at different cooling speeds in the same experiment process, are beneficial to shortening the experiment period, save the experiment cost and improve the accuracy and the reliability of the analysis result.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a cross-sectional view of an apparatus for measuring the solidification behavior of an alloy at different cooling rates according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a graphite mold in an apparatus for measuring alloy solidification behavior at different cooling rates according to an embodiment of the present disclosure;

FIG. 3 is a sectional view of a water-cooled cylinder jacket in the device for measuring the alloy solidification behavior at different cooling rates provided by the embodiment of the application.

In the figure: 100. a graphite mold; 101. a mold cavity; 102. a boss portion; 110. a graphite mold cover; 120. water-cooling the cylinder sleeve; 121. a cooling chamber; 122. a cooling water channel; 123. a water inlet; 124. a water outlet; 125. a recessed portion; 130. adding an asbestos felt; 140. laying an asbestos felt; 150. Ga-In-Sn cooling liquid; 160. a type K thermocouple; 170. a temperature acquisition system; 180. fastening a rubber ring; 190. a gasket; 200. and (6) measuring temperature points.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the application usually place when in use, and are used only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the devices or elements being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The characteristics and properties of the device and method for measuring the alloy solidification behavior at different cooling rates of the present application are further described in detail with reference to the following examples.

As shown In fig. 1, 2 and 3, an embodiment of the present application provides a device for measuring alloy solidification behavior at different cooling speeds, which includes a graphite mold 100 having a mold cavity 101 therein, a graphite mold cover 110 for opening and closing the mold cavity 101, a water-cooled cylinder sleeve 120 sleeved on an outer wall of the graphite mold 100, an upper asbestos felt 130 and a lower asbestos felt 140 respectively disposed on a top surface of the graphite mold cover 110 and a bottom surface of the graphite mold 100, Ga-In-Sn cooling liquid 150 disposed between the graphite mold 100 and the water-cooled cylinder sleeve 120, five K-type thermocouples 160, and a temperature acquisition system 170 for receiving detection signals of the K-type thermocouples 160, wherein the mold cavity 101 is formed by coaxially communicating five cylindrical detection cavities In sequence, the diameter of the five detection cavities is gradually increased from bottom to top, each detection cavity is provided with a temperature measurement point 200, and the five K-type thermocouples 160 are respectively used for detecting alloy temperatures of the five temperature measurement points 200, the distance between each temperature measuring point 200 and the nearest inner wall of the graphite mold 100 along the radial direction of the corresponding detection cavity is equal, and the distance between each temperature measuring point 200 and the top and the bottom of the corresponding detection cavity is equal. Each K-type thermocouple 160 penetrates through the graphite mold cover 110 and the upper asbestos felt 130 to be arranged, a fastening rubber ring 180 is sleeved on each K-type thermocouple 160, the bottom of each fastening rubber ring 180 abuts against the top of the upper asbestos felt 130, the projections of the mold cavity 101 in the vertical direction are located in the upper asbestos felt 130 and the lower asbestos felt 140, a cooling cavity 121 and a spiral cooling water channel 122 arranged in the cooling cavity 121 are arranged in the water-cooled cylinder sleeve 120, the cooling water channel 122 is communicated with a water inlet 123, and the cooling cavity 121 is communicated with a water outlet 124; the bottom of the graphite mold 100 expands outwards to form a circular protruding part 102, the bottom of the water-cooling cylinder jacket 120 is sunken inwards to form a recessed part 125, the protruding part 102 and the recessed part 125 are connected through threads, Ga-In-Sn cooling liquid 150 is filled between the outer wall of the top of the graphite mold 100 and the inner wall of the top of the water-cooling cylinder jacket 120, and a sealing gasket 190 is arranged on the top surface of the protruding part 102. Wherein, the thickness of the middle part of the bottom wall of the graphite mold 100 is equal to the thickness of the middle part of the top wall of the graphite mold cover 110 and is 5mm, the thickness of the upper asbestos felt 130 is equal to that of the lower asbestos felt 140 and is 5mm, and the water-cooling cylinder sleeve 120 is formed by welding an inner cylindrical surface, an outer cylindrical surface and an upper annular surface and a lower annular surface; the Ga-In-Sn cooling liquid 150 and the die cavity 101 have the same and coincident projection height on the side wall of the graphite die 100, the cooling water channels 122 are arranged at equal intervals In a spiral mode and fixed between the inner cylindrical surface and the outer cylindrical surface of the water cooling cylinder sleeve 120 In a spot welding mode, and the water inlet 123 is communicated with the spiral cooling water channels 122 In a welding mode.

The application also provides a method for measuring the alloy solidification behaviors at different cooling speeds, which is carried out by using the device for measuring the alloy solidification behaviors at different cooling speeds, and comprises the following steps:

placing an annular sealing gasket 190 on the top surface of the convex part 102 of the graphite mold 100, then sleeving the water-cooling cylinder sleeve 120 outside the graphite mold 100 to rotate, connecting the convex part 102 at the bottom of the graphite mold 100 with the concave part 125 at the bottom of the water-cooling cylinder sleeve 120 through threads, clamping the sealing gasket 190 by the graphite mold 100 and the water-cooling cylinder sleeve 120, respectively installing an upper asbestos felt 130 and a lower asbestos felt 140 on the top surface of the graphite mold cover 110 and the bottom surface of the graphite mold 100, and filling the Ga-In-Sn cooling liquid 150 between the outer wall of the top of the graphite mold 100 and the inner wall of the top of the water-cooling cylinder sleeve 120;

respectively arranging temperature measuring points 200 in five detection cavities of a cavity 101 of the graphite mold 100, wherein the distance between each temperature measuring point 200 and the nearest side of the inner wall of the graphite mold 100 along the radial direction of the corresponding detection cavity is equal and 5mm, and each temperature measuring point 200 is positioned in the middle of the height of the corresponding detection cavity along the axial direction, respectively penetrating five K-type thermocouples 160 through a graphite mold cover 110 and an upper asbestos felt 130, respectively sleeving fastening rubber rings 180 on the five K-type thermocouples 160, respectively, enabling the bottoms of the fastening rubber rings 180 to be pressed against the top of the upper asbestos felt 130, enabling the five K-type thermocouples 160 to respectively measure the temperature of the five temperature measuring points 200 when the graphite mold cover 110 covers the sealed cavity 101, and respectively electrically connecting the five K-type thermocouples 160 with a temperature acquisition system 170 through conducting wires;

introducing cooling water into a cooling water channel 122 of the water-cooled cylinder sleeve 120 through a water inlet 123, pouring completely molten alloy melt to be tested into the die cavity 101 after the cooling water enters a cooling cavity 121 through the cooling water channel 122 and is discharged through a water outlet 124, covering the graphite die cover 110 to cover the sealed die cavity 101, and receiving alloy cooling temperature changes detected by the K-type thermocouples 160 through a temperature acquisition system 170 to obtain an alloy solidification cooling curve;

after the alloy is cooled to room temperature, taking out the alloy ingot, cutting the alloy ingot by adopting an electric spark wire cutting technology, sampling near the temperature measuring point of each K-type thermocouple 160, and analyzing the solidification structure characteristics of each sample;

and (4) integrating the solidification structure characteristics of each sample and the corresponding alloy solidification cooling curve characterization results, and analyzing the solidification behaviors of the alloy at different cooling speeds.

The device and the method for measuring the alloy solidification behavior at different cooling speeds provided by the embodiment are provided with the graphite mold 100, the water-cooling cylinder sleeve 120 for carrying out heat conduction cooling on the outer wall of the graphite mold 100 and five K-type thermocouples 160, the mold cavity 101 is formed by sequentially and coaxially communicating five detection cavities with different cross-sectional areas, the five K-type thermocouples 160 are respectively used for detecting the alloy cooling speed in each detection cavity, and the device can realize the analysis of the solidification behavior of the alloy at different cooling speeds in the one-time detection process, thereby effectively shortening the experimental period, saving the experimental cost and improving the accuracy and the reliability of the analysis result.

The mold cavity 101 in the graphite mold 100 has a plurality of coaxially connected cylindrical detection cavities with different cross-sectional areas, which can provide alloy solidification processes with different cooling rates, and the principle is as follows:

the alloy heat dissipation within a certain minute time (dt) is:

Q_t＝mc.dT

wherein Q₁The heat dissipated by the alloy in dT time is m, the mass of the unit alloy is inspected, c is the specific heat capacity of the alloy, and dT is the temperature change of the alloy in dT time;

heat Q conducted away from the side walls of the graphite mold 100 at the same time dt₂Comprises the following steps:

wherein A is the heat conduction area, lambda is the heat conduction coefficient of the graphite mold 100, d is the corresponding section thickness of the graphite mold 100, T is the temperature of the alloy near the inner wall of the graphite mold 100 at the time of investigation, and T is₀Is the outside temperature of the graphite mold 100;

because the upper part and the lower part of the graphite mould 100 are both provided with the upper asbestos felt 130 and the lower asbestos felt 140 which are heat-insulated, the alloy heat In the solidification process is basically led out from the side wall of the graphite mould 100 and is taken away by circulating cooling water after passing through the Ga-In-Sn cooling liquid 150 and the inner wall of the water-cooled cylinder sleeve 120. According to conservation of energy (Q)₁＝Q₂) Is obtained by

From the above formula, the cooling speed in the solidification process of the alloy near the inner wall of the graphite mold 100 is inversely proportional to the thickness d of the corresponding side wall, and different cooling speeds required by different positions in the same graphite mold 100 in the same experiment can be achieved by adopting the design of the variable cross-section thickness on the same graphite mold 100. Furthermore, as can be seen from the above formula, the alloy cooling rateAnd is also influenced by the temperature T outside the graphite mold 100₀Influence of (1), T₀The lower the cooling rate, the faster. T is₀Mainly influenced by the cooling strength of Ga-In-Sn and finally by the water temperature and flow rate of the circulating cooling water. Therefore, in the actual operation process, after the variable-section-thickness graphite mold is designed, the actual cooling speed of each temperature measuring point can be finely adjusted by controlling the circulating cooling water, so that the actual cooling speed approaches to the preset cooling speed.

The Ga-In-Sn cooling liquid 150 is arranged between the graphite mold 100 and the water-cooling cylinder sleeve 120, so that the heat exchange speed between the graphite mold 100 and the water-cooling cylinder sleeve 120 can be increased, the experiment period is shortened, and the experiment cost is saved.

In other alternative embodiments, the thickness of the middle of the bottom wall of the graphite mold 100 is equal to the thickness of the middle of the top wall of the graphite mold cover 110 and may also be 5-7 mm, and the thickness of the upper asbestos felt 130 and the lower asbestos felt 140 is equal to and may also be 4-5 mm.

The embodiments described above are some, but not all embodiments of the present application. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.