阅读说明：本技术 多组元径向功能梯度材料设备的熔体流速调节系统及方法 (Melt flow rate adjusting system and method of multi-component radial functional gradient material equipment ) 是由 李静媛 蔡晨 祁明凡 谷金波 于 2020-12-31 设计创作，主要内容包括：本发明属于材料制备领域,公开了一种多组元径向功能梯度材料设备的熔体流速调节系统及其方法,该调节系统包括：原料存储罐、混合漏斗、螺旋杆熔炼机、离心铸造机、温度传感器及控制平台。方法通过控制梯度熔炼得到的成分多组元连续变化的熔体并建立熔体流速与变化组元间的数学关系模型,结合实时反馈数据以适合的速度连续不断将熔体送入离心铸造旋转铸型中,熔体迅速充型并快速凝固,得到成分沿径向连续变化熔体的顺序凝固。本发明具有实时反馈、控制灵活、易于操作,且通过该方法可以实现不同成分合金、树脂、玻璃等材料的径向成分梯度变化大尺寸管材、棒材、实/空心碟、盘的制备,简化了制备流程,降低了时间成本,提高了成品质量及制备效率。(The invention belongs to the field of material preparation, and discloses a melt flow rate adjusting system and a melt flow rate adjusting method of multi-component radial functional gradient material equipment, wherein the adjusting system comprises: raw materials storage jar, mixing funnel, hob smelting machine, centrifugal casting machine, temperature sensor and control platform. The method comprises the steps of controlling a melt with continuously changed components and multiple elements obtained by gradient smelting, establishing a mathematical relation model between the flow rate of the melt and the changed elements, combining real-time feedback data to continuously feed the melt into a centrifugal casting rotary casting mold at a proper speed, quickly filling and quickly solidifying the melt, and obtaining the sequential solidification of the melt with continuously changed components along the radial direction. The method has the advantages of real-time feedback, flexible control and easy operation, and can realize the preparation of large-size pipes, bars, solid/hollow discs and plates with gradient change of radial components of materials such as different-component alloys, resins, glass and the like, simplify the preparation process, reduce the time cost and improve the quality and the preparation efficiency of finished products.)

1. A melt flow rate regulating system for a multicomponent radial functionally gradient material plant, said regulating system comprising: a raw material storage tank, a mixing funnel, a screw rod smelting machine, a centrifugal casting machine, a temperature sensor and a control platform,

the raw material storage tank is used for storing raw materials for preparing the multi-component radial gradient material;

the mixing hopper is used for mixing materials entering from the storage tank and controlling the raw materials to enter the screw rod smelting machine at different speeds;

the screw rod smelting machine is used for sequentially melting the raw materials with different chemical ratios in the mixing hopper according to the feeding sequence to prevent the long-range diffusion of the melt, and controlling the outflow at a proper speed;

the centrifugal casting machine is used for solidifying the melt with the gradient change of components into a radial component gradient material in a centrifugal casting mode;

the temperature sensor is used for monitoring the outer surface temperature of the centrifugal casting machine centrifugal machine cavity and sending the temperature to the control platform;

and the control platform is used for solving the optimal flow rate of the melt at the tail end of the screw and feeding the optimal flow rate back to the feeding end by combining real-time data fed back by the temperature sensor according to the component gradient of the component radial gradient pipe to be prepared and the thickness of each component gradient material.

2. The conditioning system of claim 1 wherein the raw material storage tank is sealingly connected to the mixing hopper, the mixing hopper is connected to the feed port of the screw rod melting machine by a conduit, the discharge port of the screw rod melting machine is connected to the feed port of the centrifugal casting machine,

the temperature sensor is arranged in a centrifugal machine cavity of the centrifugal casting machine and is connected with the control platform.

3. The conditioning system of claim 1, wherein the control platform comprises a lift module, a feed valve, an industrial personal computer, and a flow rate control valve;

wherein the lifting module is arranged at the top of the screw rod smelting machine and is connected with a screw rod of the screw rod smelting machine,

the feed valve is arranged on a pipeline between the mixing hopper and a feed inlet of the screw rod smelting machine,

the flow rate control valve is arranged at the discharge port of the screw rod smelting machine,

the lifting module, the feeding valve and the flow speed control valve are in control connection with the industrial personal computer.

4. A method for adjusting a melt flow rate adjusting system of a multicomponent radial functionally graded material apparatus according to any one of claims 1 to 3, comprising the steps of:

s1) selecting required raw materials according to the components of the multi-element radial functional gradient material required by design and the thickness of the tube wall, and respectively placing the raw materials into raw material storage tanks for later use;

s2), the control platform calculates the flow velocity V of the melt according to the components of the multi-element radial functional gradient pipe to be prepared and the thickness of the pipe wall, and sends the flow velocity V to the mixing funnel, the screw rod smelting machine and the centrifugal casting machine;

s3) the mixing funnel receives a control platform instruction and mixes materials according to the components of the multi-component radial functional gradient pipe and the thickness of the pipe wall, and the materials are conveyed to the screw rod smelting machine after being uniformly mixed;

s4) after entering a melting cavity of a screw rod melting machine, the raw materials are subjected to gradient melting under the separation effect of a screw rod which is tightly attached to the inner wall of the melting cavity and vertically rotates downwards, and the melting temperature and the rotating speed R of the screw rod are regulated and controlled by a control platform, so that the melt with continuously changed components is sent to a centrifugal casting machine at the optimal centrifugal casting speed, namely the melt flow speed V;

s5) the melt enters a centrifugal casting machine at a flow speed V and is rapidly filled in the melting cavity under the action of centrifugal force, and the melt is prevented from being mixed and melted in an efficient production mode of entering and condensing by matching with a water cooling device outside the casting cavity, so that the multicomponent radial functional gradient material with continuously changed components is prepared.

5. The method as claimed in claim 4, wherein the raw material of S1) is metal, alloy, resin or glass, and the particle size is less than 20mm in size and is in various numbers.

6. The method of claim 4, wherein the multicomponent radially functionally graded material is a tube, rod, solid/hollow disk or disc.

7. The method according to claim 4, wherein the specific steps in S2) are as follows:

s2.1) calculating and obtaining the bulk density rho of each raw material according to the density rho of each raw material_j', j-A, B, C … … N, unit: g/cm³；

S2.2) determining the interface between the casting mold and the casting, the interface between the castings with different components and the temperature T of the environment interface in the casting and the centrifugal machine cavity in the unstable heat conduction process in the casting cavity according to a basic equation of the solid internal heat conduction theory, namely a Fourier equation_ijThe formula of ij-OA, AB, BC … … NS (representing the interface between the casting and the mold and each mold) is as follows:

in the formula, b_iAnd b_jThe heat storage coefficient, T, of the casting mold and the casting piece respectively_i0And T_j0Respectively the initial temperature of the casting mould and the initial temperature of the casting;

s2.3) solving the relation between the solidification thickness and the pouring time according to the heat flow relation and the energy conservation relation in the heat exchange process, wherein the formula is as follows:

in the formula, b_sIs the heat storage coefficient of the environment in the cavity of the centrifuge, T_s0Is the initial temperature of the environment in the centrifuge chamber, C_j' and L_j' is the actual specific heat capacity and the actual crystallization latent heat value T of each layer of multicomponent gradient material after mixing_jSD xi is the actual liquidus temperature of the melt of each component, and d xi is the thickness of the solidified layer;

s2.4) obtaining the ambient interface temperature T from S2.2)_ijAnd S2.3) obtaining the flow velocity V of the melt by substituting the formula (3):

wherein A (τ) is the inner surface area of the tube wall at time τ, A_{Runner channel}Is the cross-sectional area of the runner.

8. The method according to claim 4, wherein the screw rotation speed R in S4) is obtained by the following formula (4):

in the formula, R is the rotating speed of the screw; phi is the helix angle of the thread; d_SIs the diameter of the screw; d_BThe diameter of the sleeve opening is; b is the axial distance between the screw edges, and De is the diameter of the charging opening.

9. A large-sized multicomponent radial functionally graded material, wherein the multicomponent radial functionally graded material is prepared by the method according to any one of claims 4 to 8.

Technical Field

The invention belongs to the field of material processing and preparation, and particularly relates to a melt flow rate adjusting system and method for multi-component radial functional gradient material equipment of large-size multi-component alloys, resins, glass and other materials with chemical components changing in a radial continuous gradient manner, such as pipes, bars, solid/hollow discs and discs.

Background

The materials with uniform components under severe service conditions such as aerospace, nuclear fusion and the like cannot meet the requirements, and the composite materials are produced in response to the change requirements of environmental shock on the material performance. The traditional composite material is prepared by means of hot pressing, welding and the like, and the problem of poor performance of defects and the like easily occurs due to large difference among parts of the material. The functional gradient material is a novel composite material which has special functions and is suitable for different environmental requirements because the composition, structure, porosity and other elements of the material are continuously changed from one side to the other side, so that the physical, chemical, mechanical and other properties of the material are continuously changed. It is generally believed that functionally graded materials and components cannot be prepared by conventional metallurgical methods. At present, functional gradient materials are mainly prepared by methods such as vapor deposition, plasma spraying, magnetron sputtering, powder metallurgy, laser cladding, additive manufacturing and the like, but the existing technology has the problems of limited size of prepared materials, high production cost, low efficiency, easy generation of macroscopic cracking, incapability of designing components according to requirements and the like.

Disclosure of Invention

The invention discloses a melt flow rate adjusting system and a melt flow rate adjusting method of a multi-component radial functionally gradient material device, which aim to solve any one of the above and other potential problems in the prior art.

In order to solve the above problems, the present invention discloses a melt flow rate regulating system of a multicomponent radial functionally gradient material device, comprising: the device comprises a raw material storage tank, a mixing funnel, a screw rod smelting machine, a centrifugal casting machine, a temperature sensor and a control platform;

the raw material storage tank is used for storing raw materials for preparing the multi-element radial gradient material;

wherein, feed mechanism in the raw materials holding vessel can regulate and control feed mechanism's rotational speed through control platform, changes the raw materials ratio that gets into the funnel through control feed mechanism's rotational speed.

The mixing hopper is used for mixing materials entering from the storage tank and controlling the raw materials to enter the screw rod smelting machine at different speeds; one end of the mixing funnel is connected with the raw material storage tank;

the screw rod smelting machine is used for sequentially melting the raw materials with different chemical ratios in the mixing hopper according to the feeding sequence to prevent the long-range diffusion of the melt, and controlling the outflow at a proper speed; one end of the screw rod smelting machine is connected with a discharge hole of the mixing hopper;

the screw rod of the screw rod smelting machine is tightly attached to the inner wall of the smelting cavity and vertically rotates downwards, so that the phenomenon of mixing and smelting caused by the long-range diffusion effect of the continuously changed component gradient melt can be effectively avoided;

the centrifugal casting machine is used for solidifying the melt with the gradient change of components into a pipe in a centrifugal casting mode; one end of the centrifugal casting machine is connected with a discharge port of the screw rod smelting machine; and a discharge port at the tail end of the screw rod smelting machine is provided with a flow rate control valve so as to adjust the flow rate of the melt.

The temperature sensor is used for monitoring the temperature of the outer surface of the centrifugal casting centrifuge cavity and sending the temperature to the control platform; the temperature sensor is arranged outside the centrifugal casting melting cavity;

the control platform is used for solving the optimal flow rate of the melt at the tail end of the screw and feeding the optimal flow rate back to the feeding end by combining real-time data fed back by the temperature sensor according to the component gradient of the component radial gradient pipe to be prepared and the thickness of each component gradient material;

the invention also aims to provide a method for preparing a large-size multi-component radial functional gradient material by using the regulating system, which specifically comprises the following steps:

s1) selecting required raw materials according to the components of the multi-element radial functional gradient material required by design and the thickness of the tube wall, and respectively placing the raw materials into raw material storage tanks for later use;

s2), the control platform calculates the flow velocity V of the melt by means of a mathematical model according to the components of the multi-element radial functional gradient material and the thickness of the pipe wall, and the melt is solidified immediately when entering at the flow velocity;

s3) the mixing funnel receives the instruction of the control platform, mixes the materials according to the components of the multi-component radial functional gradient material and the thickness of the tube wall, uniformly mixes the materials and conveys the materials to the screw rod smelting machine;

s4) after the raw material enters a melting cavity of a screw rod melting machine, the raw material is subjected to gradient melting under the separation effect of a screw rod which is tightly attached to the inner wall of the melting cavity and vertically rotates downwards, and the melting temperature and the rotating speed R of the screw rod are regulated and controlled by a control platform, so that the melt with continuously changed components is sent to a centrifugal casting machine at the optimal centrifugal casting speed, namely the melt flow speed V;

s5) the melt enters a centrifugal casting machine at a flow speed V and is rapidly filled in the melting cavity under the action of centrifugal force, and the melt is prevented from being mixed and melted in an efficient production mode of entering and condensing immediately by matching with a water cooling device outside the casting cavity, so that the functional gradient pipe with continuously changed components is prepared.

Further, the mathematical model and the specific algorithm in S2) are as follows:

s2.1) obtaining the bulk density rho of each principle according to the density rho of each raw material_j', j-A, B, C … … N, unit: g/cm³；

S2.2) according to a basic equation of the solid internal heat conduction theory, namely a Fourier equation, the temperature T of the interface between the casting mold and the casting, the interface between the casting with different components and the environment interface in the casting and the centrifugal machine cavity in the unstable heat conduction process in the casting cavity can be determined_ijWhere ij is OA, AB, BC … … NS (indicating the interface between the casting and the mold and each mold), and O is the mold material, the formula is as follows:

in the formula, b_iAnd b_jThe heat storage coefficients, T, of the casting mold (containing the solidified layer casting) and the casting, respectively_i0And T_j0Respectively, the initial temperature of the casting mold (transmitted by a temperature sensor in real time) and the initial temperature of the casting (approximate to the casting pouring temperature);

s2.3) solving the relation between the solidification thickness and the pouring time according to the heat flow relation and the energy conservation relation in the heat exchange process, wherein the formula is as follows:

in the formula, b_sRepresents the heat storage coefficient T of the environment in the cavity of the centrifuge_s0Denotes the initial temperature of the environment inside the centrifuge chamber, C_j’、L_j' is the actual specific heat capacity and the actual latent heat of crystallization, T, of each layer of multicomponent gradient material after mixing_jSThe actual liquidus temperature of the melt of each component;

s2.4) making the following assumptions on the melt entering the centrifuge cavity: (1) after the melt enters the melting cavity, the melt is instantly filled and does not flow relative to the mold wall after the filling is finished, namely the convection heat exchange condition is neglected; (2) when the flow rate of the melt is calculated, according to the melt-in-and-congealing model, namely, the pouring speed just meets the solidification condition, and the solidified material is partially melted due to the latent heat of crystallization released by the newly-entered material. In conclusion, the relationship between the melt flow rate and the continuously changing material and time of the composition gradient is calculated, and the formula is as follows:

wherein A (τ) is the inner surface area of the tube wall at time τ, A_{Runner channel}Is the cross-sectional area of the runner, T_ijGiven by equation (1);

the screw rotation speed R in S4) is obtained by the following formula:

in the formula, R is the rotating speed of the screw; phi is the helix angle of the thread; d_SIs the diameter of the screw; d_BThe diameter of the sleeve opening is; b is the axial distance between the screw edges.

The large-size multi-component radial functional gradient material is prepared by the method.

The invention has the beneficial effects that: due to the adoption of the technical scheme, the invention has the advantages of real-time feedback, flexible control, easy operation and the like. The device continuously sends the raw materials to the mixer through the system control raw material storage, after the raw materials are uniformly mixed according to different proportions, the raw materials are continuously sent to the screw rod smelting furnace to be sequentially smelted under the control of the flow rate, the melt is controlled by the control platform to enter the centrifugal casting machine at the optimal flow rate, and the melt which continuously changes along the axial component is quickly filled and solidified under the action of the centrifugal force, so that the melt is immediately poured and solidified to be converted into the radial gradient material. The method can realize the preparation of large-size pipes, bars, solid/hollow discs and discs with continuously gradient change in radial direction of components of materials such as alloys, resins, glass and the like with different components, simplifies the preparation process, reduces the time cost, and improves the quality and the preparation efficiency of finished products.

Drawings

FIG. 1 is a schematic view of a system for regulating the melt flow rate of a radially graded material in accordance with the present invention.

FIG. 2 is a front cross-sectional view of a melt flow rate regulating system for a radially graded material of the present invention.

FIG. 3 is a side cross-sectional view of a melt flow rate adjustment system for a radially graded material of the present invention.

In the figure:

1. the device comprises a feeding mechanism, a stirring mechanism, a mixing hopper, a lifting module, a feeding valve, a material pipe, a pressure gauge, a water-cooling furnace door, a control panel, a water-cooling furnace door observation hole, a vacuum sealing mechanism, a centrifugal casting furnace door observation window, a centrifugal casting furnace door, a motor, a vacuumizing machine, a screw rod, a double-layer water-cooling vacuum cavity, a heating coil, a flow rate control valve, a crucible, a water spraying device, a casting mold front cover plate, a temperature sensor, a centrifugal machine cavity, a centrifugal casting mold, an upper guide pipe, a lower guide pipe, a temperature sensor, a centrifugal casting mold cavity, a centrifugal casting mold, a heating coil, a flow rate control valve, a crucible, a water spraying device, a casting.

Detailed Description

The principles, aspects and advantages of the present invention will be further fully and completely explained with reference to the accompanying drawings.

As shown in fig. 1 to 3, the present invention is a method for adjusting a melt flow rate of a radial composition gradient material, the adjusting system comprising: the device comprises a raw material storage tank, a mixing funnel, a screw rod smelting machine, a centrifugal casting machine, a temperature sensor and a control platform;

the raw material storage tank is used for storing raw materials for preparing the multi-element radial gradient material;

wherein, feed mechanism 1 in the raw materials holding vessel can regulate and control feed mechanism's rotational speed through control platform, changes the raw materials ratio that gets into the funnel through control feed mechanism's rotational speed.

The mixing hopper is used for mixing materials entering from the storage tank through the stirring mechanism 2 and controlling the raw materials to enter the screw rod smelting machine at different speeds through the feeding valve 5; one end of the mixing funnel is connected with the raw material storage tank;

the screw rod smelting machine is used for sequentially melting the raw materials with different chemical ratios in the mixing hopper according to the feeding sequence to prevent the long-range diffusion of the melt, and controlling the melt to flow out at a proper speed through the lifting module 4; one end of the screw rod smelting machine is connected with the material pipe 6;

wherein, the raw materials are melted under the induction heating of the heating coil 18, the spiral rod 16 is tightly attached to the inner wall of the melting cavity and vertically rotates downwards, and the phenomenon of mixing and melting caused by the long-range diffusion effect of the component gradient continuous change melt can be effectively avoided.

The centrifugal casting machine comprises a casting front cover plate 22, a centrifugal machine cavity 24 and a centrifugal casting mold 25; the centrifugal casting device is used for solidifying the melt with gradient change of components into a pipe in a centrifugal casting mode; the centrifugal casting machine comprises an upper guide pipe 26 and a lower guide pipe 27 which are connected with one end;

the centrifugal machine cavity 24 comprises a water spraying device 21, the outer wall of the centrifugal casting mold 25 is rapidly cooled under the action of the water spraying device 21, the temperature gradient of the casting and the casting mold is increased to provide driving force for casting solidification, and in addition, the water spraying speed is effectively controlled through a control platform to adjust the casting solidification speed.

The temperature sensor 23 is used for monitoring the temperature of the outer surface of the centrifugal casting mold 25 and sending the temperature to the control platform; the temperature sensor is placed in the centrifuge chamber 24;

the control platform comprises a lifting module 4, a feed valve 5, a control panel 9 and a flow rate control valve 19; the device is used for solving the optimal flow rate of the melt at the tail end of the screw and feeding the optimal flow rate back to a feeding end by combining real-time data fed back by a temperature sensor according to the component gradient of the component radial gradient pipe to be prepared and the thickness of each component gradient material;

the control platform controls the lifting module 4, the feeding valve 5 and the flow rate control valve 19 to enable the melt to enter the centrifugal casting machine at the optimal flow rate calculated by the mathematical model according to the mathematical model and real-time data fed back by the temperature sensor 23, so that continuous solidification of the component gradient continuous change material is ensured.

The invention also aims to provide a method for preparing a large-size multi-component radial functional gradient material by using the regulating system, which specifically comprises the following steps:

s1) selecting required raw materials according to the components of the multi-element radial functional gradient material required by design and the thickness of the tube wall, and respectively placing the raw materials into raw material storage tanks for later use;

s2), the control platform calculates the flow velocity V of the melt by means of a mathematical model according to the components of the multi-element radial functional gradient material and the thickness of the pipe wall, and the melt is solidified immediately when entering at the flow velocity;

s3) the mixing funnel receives the instruction of the control platform, mixes the materials according to the components of the multi-component radial functional gradient material and the thickness of the tube wall, uniformly mixes the materials and conveys the materials to the screw rod smelting machine;

s4) after the raw material enters a melting cavity of a screw rod melting machine, the raw material is subjected to gradient melting under the separation effect of a screw rod which is tightly attached to the inner wall of the melting cavity and vertically rotates downwards, and the melting temperature and the rotating speed R of the screw rod are regulated and controlled by a control platform, so that the melt with continuously changed components is sent to a centrifugal casting machine at the optimal centrifugal casting speed, namely the melt flow speed V;

s5) the melt enters a centrifugal casting machine at a flow speed V and is rapidly filled in the melting cavity under the action of centrifugal force, and the melt is prevented from being mixed and melted in an efficient production mode of entering and condensing immediately by matching with a water cooling device outside the casting cavity, so that the functional gradient pipe with continuously changed components is prepared.

The mathematical model and the specific algorithm in the step S2) are as follows:

s2.1) obtaining the bulk density rho of each principle according to the density rho of each raw material_j', j-A, B, C … … N, unit: g/cm³；

S2.2) according to a basic equation of the solid internal heat conduction theory, namely a Fourier equation, the temperature T of the interface between the casting mold and the casting, the interface between the casting with different components and the environment interface in the casting and the centrifugal machine cavity in the unstable heat conduction process in the casting cavity can be determined_ijThe formula of ij-OA, AB, BC … … NS (representing the interface between the casting and the mold and each mold) is as follows:

in the formula, b_iAnd b_jThe heat storage coefficients, T, of the casting mold (containing the solidified layer casting) and the casting, respectively_i0And T_j0Respectively, the initial temperature of the casting mold (transmitted by a temperature sensor in real time) and the initial temperature of the casting (approximate to the casting pouring temperature);

s2.3) solving the relation between the solidification thickness and the pouring time according to the heat flow relation and the energy conservation relation in the heat exchange process, wherein the formula is as follows:

in the formula, b_sRepresents the heat storage coefficient T of the environment in the cavity of the centrifuge_s0Denotes the initial temperature of the environment inside the centrifuge chamber, C_j’、L_j' is the actual specific heat capacity and the actual latent heat of crystallization, T, of each layer of multicomponent gradient material after mixing_jSThe actual liquidus temperature of the melt of each component, d xi is the solidification thickness;

s2.4) making the following assumptions on the melt entering the centrifuge cavity: (1) after the melt enters the melting cavity, the melt is instantly filled and does not flow relative to the mold wall after the filling is finished, namely the convection heat exchange condition is neglected; (2) when the flow rate of the melt is calculated, according to the melt-in-and-congealing model, namely, the pouring speed just meets the solidification condition, and the solidified material is partially melted due to the latent heat of crystallization released by the newly-entered material. In conclusion, the relationship between the melt flow rate and the continuously changing material and time of the composition gradient is calculated, and the formula is as follows:

wherein A (τ) is the inner surface area of the tube wall at time τ, A_{Runner channel}Is the cross-sectional area of the runner, T_ijGiven by equation (1);

the screw rotation speed R in S4) is obtained by the following formula:

in the formula, R is the rotating speed of the screw; phi is the helix angle of the thread; d_SIs the diameter of the screw; d_BThe diameter of the sleeve opening is; b is the axial distance between the screw edges, and De is the diameter of the material inlet.

The large-size multi-component radial functional gradient material is prepared by the method.

The melt flow rate adjusting system and method for a multicomponent radial functionally gradient material device provided by the embodiments of the present application are described in detail above. The above description of the embodiments is only for the purpose of helping to understand the method of the present application and its core ideas; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

As used in the specification and claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect. The description which follows is a preferred embodiment of the present application, but is made for the purpose of illustrating the general principles of the application and not for the purpose of limiting the scope of the application. The protection scope of the present application shall be subject to the definitions of the appended claims.

It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a commodity or system that includes the element.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the application as described herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.