阅读说明：本技术 磨削装置、磨削方法及航空发动机的叶片 (Grinding device, grinding method and blade of aircraft engine ) 是由 王文理 房建国 朱燏 杜兆才 于 2019-11-05 设计创作，主要内容包括：一种磨削装置、磨削方法及应用,用于对航空发动机的叶片进排气边进行磨削,包括控制器和工作台,工作台上设有六轴机器人、激光测量机构、砂带机、两个纤维磨削机构及工件放置区,工件放置区存放有多个待加工叶片,纤维磨削机构包括磨削支架,变频电机,以及与具有弹性的纤维磨轮,两个纤维磨轮的旋转方向相反。本发明通过具有弹性的纤维磨轮在压力作用下可变形的特性,可以抵消机器人的运动轨迹精度误差,来实现叶片的高精度磨削；通过两个纤维磨轮的旋转方向不同,在一个装置中实现进叶片排气边的磨削加工；通过激光测量机构在线测量掌握代加工叶片的磨削余量,以调整每个代加工叶片的磨削轨迹,从而实现每个代加工叶片的高精度、自适应磨削。(A grinding device, a grinding method and application are used for grinding air inlet and outlet edges of blades of an aircraft engine and comprise a controller and a workbench, wherein a six-axis robot, a laser measuring mechanism, an abrasive belt machine, two fiber grinding mechanisms and a workpiece placing area are arranged on the workbench, a plurality of blades to be processed are stored in the workpiece placing area, each fiber grinding mechanism comprises a grinding support, a variable frequency motor and a fiber grinding wheel with elasticity, and the rotation directions of the two fiber grinding wheels are opposite. According to the invention, the deformable characteristic of the elastic fiber grinding wheel under the action of pressure can offset the motion track precision error of the robot, so that the high-precision grinding of the blade is realized; the grinding processing of the exhaust edge of the blade is realized in one device by the different rotating directions of the two fiber grinding wheels; the grinding allowance of the blades to be machined is measured and mastered on line through the laser measuring mechanism so as to adjust the grinding track of each blade to be machined, and therefore high-precision and self-adaptive grinding of each blade to be machined is achieved.)

1. A grinding device is characterized by being used for grinding air inlet and outlet edges of a blade of an aircraft engine and comprising a controller and a workbench, wherein a six-axis robot, a laser measuring mechanism, an abrasive belt machine, two fiber grinding mechanisms and a workpiece placing area are arranged on the workbench,

the six-axis robot is positioned in the middle of the workbench, and a plurality of blades to be processed are stored in the workpiece placing area;

the fiber grinding mechanism comprises a grinding support arranged on the workbench, a variable frequency motor and an elastic fiber grinding wheel which is connected with the variable frequency motor are arranged on the grinding support, the variable frequency motor and the six-axis robot are respectively positioned at two sides of the fiber grinding wheel, the two fiber grinding mechanisms are positioned at the same side of the six-axis robot, the rotating directions of the two fiber grinding wheels are opposite, one fiber grinding mechanism is used for processing an air inlet edge of the blade to be processed, and the other fiber grinding mechanism is used for processing an air outlet edge of the blade to be processed;

the controller is electrically connected with the six-axis robot, the laser measuring mechanism, the two fiber grinding mechanisms and the abrasive belt machine and is used for controlling the six-axis robot to grab the blade to be processed, measure the distribution of grinding allowance in the laser measuring mechanism, grind the blade in the two fiber grinding mechanisms and polish the blade in the abrasive belt machine.

2. The grinding device of claim 1, wherein the grinding grains of the grinding fiber wheel are made of SiC grains, the grinding fiber wheel has a diameter of 200mm and a thickness of 10mm, and the matrix therein has a medium hardness and a mesh number of 50.

3. The grinding apparatus of claim 1 wherein two of said fiber grinding mechanisms are positioned side by side and said six axis robot is positioned on a horizontal line with the midpoints of the two fiber grinding mechanisms.

4. A grinding apparatus as claimed in claim 3, characterized in that the grinding carriage is provided with a carborundum wheel for dressing the fiber grinding wheel.

5. The grinding apparatus of claim 4 wherein said grinding carriage is of an F configuration including a base plate on said table and two support plates on said base plate, said fiber grinding wheel and carborundum wheel being located between said two support plates.

6. A grinding method is used for grinding air inlet and outlet edges of blades of an aircraft engine, wherein grabbing actions are realized through a six-axis robot, and control actions and data processing procedures are realized through a controller, and the grinding method comprises the following steps:

grabbing a blade to be processed and sending the blade to a laser measuring mechanism for measuring the distribution of grinding allowance;

pressing the blade to be processed with the grinding allowance measured into a fiber grinding wheel of a fiber grinding mechanism at a preset angle to a preset depth for grinding;

sending the grinded blade to be processed into the laser measuring mechanism again for measurement to obtain the processed size, and judging whether the processed size is within a preset size range;

and if so, conveying the grinded blade to be processed into an abrasive belt machine for polishing.

7. The grinding method according to claim 6, wherein after the step of judging whether the machined dimension is within a preset dimension range, the grinding method comprises:

if not, pressing the grinded blade to be processed into the fiber grinding wheel of the fiber grinding mechanism again for grinding.

8. The method for grinding slabs with unequal wall thicknesses as claimed in claim 6, wherein the preset depth ranges from 5mm to 10 mm.

9. A blade for an aircraft engine, characterized in that it is manufactured by using a grinding device according to any one of claims 1 to 5 or a grinding method according to any one of claims 6 to 8.

10. The aircraft engine blade according to claim 9, wherein the grinding speed of the fiber grinding wheel is 30m/s when grinding is performed, and the grinding accuracy of the inlet and outlet edge fillet profile of the aircraft engine blade after grinding is within 0.01 mm.

Technical Field

The invention relates to the technical field of grinding, in particular to a grinding device, a grinding method and a blade of an aircraft engine.

Background

The aviation engine blade has complex profile and high processing technology requirement, and the technical requirement on processing equipment and technology is higher and higher. With the rapid development of computer numerical control technology and grinding technology, the grinding processing of the blade profile is developed from manual grinding, hydraulic profiling grinding to multi-coordinate numerical control grinding.

After the blade profile is precisely forged, the air inlet and outlet edges of the blade need to be milled once to remove the flash so as to ensure the chord length of the blade, then, the fillet of the air inlet and outlet edges needs to be ground to form, the quality requirement of the fillet of the air inlet and outlet edges is high, and the fillet has great influence on the pneumatic efficiency of an engine.

With the increasing maturity of the robot technology, an intelligent grinding device has been developed abroad, and the air inlet and outlet edges of the blades are ground in a multi-axis linkage mode by using a joint robot. However, the grinding process and software control method outside China strictly limit the country, so that the more advanced process is difficult to obtain at home, and the blade air inlet and outlet edges are ground by adopting a manual abrasive belt grinding mode at present. The manual grinding mode is greatly related to the skill of workers, the precision of products cannot be guaranteed, the quality consistency of batch products is poor, the working environment is severe, and the manual grinding mode is not good for the health of the workers.

Disclosure of Invention

The embodiment of the invention provides a grinding device, a grinding method and an aircraft engine blade.

In a first aspect, an embodiment of the present invention provides a grinding device for grinding an air inlet and outlet edge of a blade of an aircraft engine, the grinding device comprising a controller and a workbench, the workbench being provided with a six-axis robot, a laser measuring mechanism, an abrasive belt machine, two fiber grinding mechanisms and a workpiece placement area, wherein,

the six-axis robot is positioned in the middle of the workbench, and a plurality of blades to be processed are stored in the workpiece placing area;

the fiber grinding mechanism comprises a grinding support arranged on the workbench, a variable frequency motor and an elastic fiber grinding wheel which is connected with the variable frequency motor are arranged on the grinding support, the variable frequency motor and the six-axis robot are respectively positioned at two sides of the fiber grinding wheel, the two fiber grinding mechanisms are positioned at the same side of the six-axis robot, the rotating directions of the two fiber grinding wheels are opposite, one fiber grinding mechanism is used for processing an air inlet edge of the blade to be processed, and the other fiber grinding mechanism is used for processing an air outlet edge of the blade to be processed;

the controller is electrically connected with the six-axis robot, the laser measuring mechanism, the two fiber grinding mechanisms and the abrasive belt machine and is used for controlling the six-axis robot to grab the blade to be processed, measure the distribution of grinding allowance in the laser measuring mechanism, grind the blade in the two fiber grinding mechanisms and polish the blade in the abrasive belt machine.

Further, the grinding particles of the fiber grinding wheel are made of SiC particles, the diameter of the fiber grinding wheel is 200mm, the thickness of the fiber grinding wheel is 10mm, the matrix in the fiber grinding wheel is medium-hardness, and the mesh number of the fiber grinding wheel is 50.

Further, the two fiber grinding mechanisms are arranged side by side, and the six-axis robot is located on a horizontal line where the midpoints of the two fiber grinding mechanisms are located.

Furthermore, a carborundum wheel is arranged on the grinding support and used for adjusting the fiber grinding wheel.

Further, the grinding support is of an F-shaped structure and comprises a bottom plate arranged on the workbench and two supporting plates arranged on the bottom plate, and the fiber grinding wheel and the carborundum grinding wheel are located between the two supporting plates.

In a second aspect, the invention provides a method for grinding a plate with different wall thicknesses, which is used for grinding the air inlet and outlet edges of a blade of an aircraft engine, wherein the grabbing action is realized by a six-axis robot, and the control action and the data processing process are realized by a controller, the grinding method comprises the following steps:

grabbing a blade to be processed and sending the blade to a laser measuring mechanism for measuring the distribution of grinding allowance;

pressing the blade to be processed with the grinding allowance measured into a fiber grinding wheel of a fiber grinding mechanism to a preset depth for grinding;

sending the grinded blade to be processed into the laser measuring mechanism again for measurement to obtain the processed size, and judging whether the processed size is within a preset size range;

and if so, conveying the grinded blade to be processed into an abrasive belt machine for polishing.

Further, after the step of judging whether the machined dimension is within a preset dimension range, the grinding method includes:

if not, pressing the grinded blade to be processed into the fiber grinding wheel of the fiber grinding mechanism again for grinding.

Further, the preset depth ranges from 5mm to 10 mm.

In a third aspect, the invention provides a blade of an aircraft engine, which is manufactured by the grinding device or the grinding method.

Further, the grinding speed of the fiber grinding wheel is 30m/s during grinding, and the grinding precision of the air inlet and outlet edge fillet profile degree of the blade of the aircraft engine is within 0.01mm after grinding.

In summary, compared with the prior art, the invention has the following advantages:

(1) the movement track precision error of the six-axis robot can be counteracted through the deformable characteristic of the elastic fiber grinding wheel under the action of pressure, so that the high-precision grinding of the blade is realized;

(2) the grinding processing of the exhaust edge of the blade is realized in one device by the different rotating directions of the two fiber grinding wheels;

(3) the grinding allowance of the blades to be machined is measured and mastered on line through a laser measuring mechanism so as to adjust the grinding track of each blade to be machined, and therefore high-precision and self-adaptive grinding of each blade to be machined is achieved;

(4) the blade of the aircraft engine manufactured by the grinding device or the grinding method has the grinding precision of the intake and exhaust edge fillet profile within 0.01 mm.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic view of the overall structure of a grinding apparatus in an embodiment of the present invention.

Fig. 2 is a top view of the grinding apparatus of fig. 1.

Fig. 3 is a flowchart of a grinding method of the grinding apparatus in the embodiment of the invention.

Fig. 4 is a flowchart of a grinding parameter obtaining method of the grinding apparatus in the embodiment of the invention.

FIG. 5 is a schematic view of a blade pressed into a fiber grinding wheel during grinding in an embodiment of the present invention.

In the figure:

10-a workbench; 11-six axis robot; 12-a laser measuring mechanism; 13-an abrasive belt machine; 14-a fiber grinding mechanism; 141-grinding the support; 1411-a bottom plate; 1412-a support plate; 142-variable frequency motors; 143-fiber abrasive wheel; 144-emery wheel; 15-a workpiece placement area; 16-blade to be processed.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the embodiments described, but covers any modifications, alterations, and improvements in the parts, components, and connections without departing from the spirit of the invention.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

Referring to fig. 1 and 2, the grinding device provided by the invention is used for grinding air inlet and outlet edges of blades of an aircraft engine, and comprises a controller (not shown in the figure) and a workbench 10, wherein a six-axis robot 11, a laser measuring mechanism 12, an abrasive belt machine 13, two fiber grinding mechanisms 14 and a workpiece placing area 15 are arranged on the workbench 10, the six-axis robot 11 is located in the middle of the workbench 10, and a plurality of blades 16 to be processed are stored in the workpiece placing area 15.

Specifically, in the present invention, the fiber grinding mechanism 14 includes a grinding support 141 disposed on the worktable 10, and the grinding support 141 is provided with a variable frequency motor 142 and an elastic fiber grinding wheel 143 connected to the variable frequency motor 142. In the invention, the fiber grinding wheel 143 has certain elasticity, different from a hard grinding wheel, can generate certain deformation under the pressure of a workpiece, can generate different grinding effects by combining different abrasive particle sizes and different grinding speeds, and can adjust the grinding linear speed through the variable frequency motor 142.

Furthermore, the grinding particles of the fiber grinding wheel 143 are made of SiC particles, the diameter of the fiber grinding wheel 143 is 200mm, the thickness of the fiber grinding wheel is 10mm, the matrix of the fiber grinding wheel is medium hardness, and the mesh number of the fiber grinding wheel is 50.

Preferably, the variable frequency motor 142 and the six-axis robot 11 are respectively located at two sides of the fiber grinding wheel 143, and the two fiber grinding mechanisms 14 are located at the same side of the six-axis robot 11, so that the six-axis robot 11 can grab the blade 16 to be processed to the fiber grinding wheel 143 for grinding, and interference with the variable frequency motor 142 during moving and processing is avoided. And the rotation directions of the two fiber grinding wheels 143 are opposite, one is used for processing the air inlet edge of the blade 16 to be processed, and the other is used for processing the air outlet edge of the blade 16 to be processed, so that the grinding processing of the air inlet edge and the air outlet edge of the blade is realized in the same device.

In another preferred embodiment of the present invention, the two fiber grinding mechanisms 14 are arranged side by side, and the six-axis robot 11 is located on a horizontal line where the middle points of the two fiber grinding mechanisms 14 are located, so that the six-axis robot 11 is closer to the two fiber grinding mechanisms 14, and the movement stroke of the six-axis robot 11 can be shortened.

In the present invention, the controller is electrically connected to the six-axis robot 11, the laser measuring mechanism 12, the two fiber grinding mechanisms 14, and the abrasive belt machine 13, and is configured to control the six-axis robot 11 to grab the blade 16 to be processed, measure the distribution of the grinding allowance in the laser measuring mechanism 12, grind the blade in the two fiber grinding mechanisms 14, and polish the blade in the abrasive belt machine 13.

Referring to fig. 1, two fiber grinding mechanisms 14, an abrasive belt machine 13, a laser measuring mechanism 12, and a workpiece placing area 15 sequentially surround the six-axis robot 11, specifically, the working range that the six-axis robot 11 can reach.

Referring to fig. 1, the grinding support 141 is provided with a carborundum wheel 144, and the carborundum wheel 144 is used for adjusting the fiber grinding wheel 143, so as to ensure that the grinding state of each blade 16 to be processed is consistent in the grinding process.

Further, the grinding support 141 is in an F-shaped structure, and includes a bottom plate 1411 disposed on the working table, and two support plates 1412 disposed on the bottom plate 1411, and the fiber grinding wheel 143 and the diamond grinding wheel 144 are disposed between the two support plates 1412, so that the arrangement can provide a good support for the entire fiber grinding mechanism 14.

Referring to fig. 3, the present invention provides a grinding method for grinding the air inlet and outlet edges of an aircraft engine, wherein the grabbing operation is performed by a six-axis robot 11, and the control operation and data processing process are performed by a controller, the grinding method includes steps S110 to S140:

and step S110, grabbing the blade 16 to be processed and sending the blade to the laser measuring mechanism 12 for measuring the distribution of the grinding allowance.

In this step, the six-axis robot 11 grabs the blade 16 to be processed into the laser measuring mechanism 12, and the grinding allowance distribution of each blade 16 to be processed is measured on line in a non-contact manner. According to different grinding allowances, grinding parameters during subsequent grinding can be adjusted, and personalized self-adaptive grinding of each blade 16 to be machined is achieved.

Step S120, pressing the blade 16 to be processed after the grinding allowance is measured into the fiber grinding wheel 143 of the fiber grinding mechanism 14 to a preset depth for grinding.

In this step, the fiber grinding wheel 143 is selected for grinding while air is being supplied and exhausted because the fiber grinding wheel 143 has a certain elasticity and can deform to a certain extent under the pressure of the workpiece, generally to a deformation of 5mm to 10mm, unlike the hard grinding wheel. Different abrasive grit, different grinding speeds in combination with the fiber grinding wheel 1143 can produce different grinding results. The preset depth ranges from 5mm to 10mm according to the degree of deformation of the fiber grinding wheel 143.

Step S130, the grinded blade 16 to be processed is sent to the laser measuring mechanism 12 again for measurement to obtain a processed dimension, and whether the processed dimension is within the preset dimension range is determined.

And step S140, if yes, sending the grinded blade 16 to be processed into the abrasive belt machine 13 for polishing.

In this step, the blade can be polished on the belt sander 13 by gripping the blade by the six-axis robot 11, and the requirement of higher roughness can be met.

Further, after the step of judging whether the machined dimension is within a preset dimension range, the grinding method includes:

if not, the blade 16 to be processed after grinding is pressed into the fiber grinding wheel 143 of the fiber grinding mechanism 14 again for grinding.

In the present invention, the positioning accuracy of the six-axis robot 11 is usually ± 0.1mm, and since the grinding fiber wheel 143 has elasticity, when the blade is grinding, the depth range in which the grinding fiber wheel 143 is pressed is 5mm to 10mm, and the depth tolerance is ± 0.1mm, the accuracy error of the movement trajectory of the six-axis robot 11 can be cancelled. The motion trajectory precision of the six-axis robot 11 can completely meet the requirement of the depth of pressing the blade into the fiber grinding wheel 143, and the depth corresponds to the required force of pressing the blade into the fiber grinding wheel 143, and the high-progress grinding precision of the grade of 0.01mm can be realized by matching with other grinding parameters obtained through tests.

Referring to fig. 4 and 5, an embodiment of the present invention provides a method for obtaining grinding parameters of a grinding device, the grinding device is used for grinding an air inlet and outlet edge of a blade of an aircraft engine, the grinding device comprises a six-axis robot 11 and a fiber grinding mechanism 14, the fiber grinding mechanism 14 is provided with a fiber grinding wheel 143 with elasticity, and the obtaining method comprises steps S210-S230:

step S210, analyzing a plurality of preselected grinding parameters influencing the grinding precision of the fillet of the air inlet and outlet edges of the blade, wherein the preselected grinding parameters comprise an included angle Bt between the blade and a grinding wheel, a grinding linear speed Vt, a pressure Zt for pressing the blade into the fiber grinding wheel and a grinding feed speed Ft;

step S220, grabbing the blade by the six-axis robot 111 and pressing the blade into the fiber grinding wheel 143 for grinding test, so as to verify whether the preselected grinding parameters influence the ground fillet Rt one by one;

and step S230, if so, establishing the relation between the preselected grinding parameters and the ground round angle Rt through a limited number of tests.

It should be noted that, during the grinding test, when other parameters are not changed, the angle Bt between the blade and the grinding wheel has an influence on the elliptical shape of the air intake and exhaust of the blade, and if the elliptical shape of the air intake and exhaust of the blade is not changed, the angle Bt between the blade and the grinding wheel cannot be changed during the grinding process. Namely, the included angle Bt between the blade and the grinding wheel is a constant value and is changed according to the change of the inlet and exhaust edge round angle Rt of the blade.

Specifically, the included angle Bt between the blade and the grinding wheel can be obtained through a grinding test, and then can be directly used when a program of the motion track of the six-axis robot 11 is compiled, the included angle Bt between the blade and the grinding wheel can be realized by changing the track of the six-axis robot 11 by controlling the joint rotation of the six-axis robot 11 and achieving a preset angle during grinding.

Further, it should be noted that, during the grinding test, when other parameters are not changed, the grinding linear velocity Vt has an influence on the blade air intake and exhaust edge rounded corner Rt, and when the elliptical shape of the blade air intake and exhaust is not changed, the grinding linear velocity Vt cannot be changed during the grinding. That is, the grinding linear velocity Vt is constant and changes according to the change of the blade air inlet and outlet edge rounded corner Rt. And the grinding linear speed Vt is (3.14D × n)/60, wherein D is the diameter of the fiber grinding wheel, and n is the rotating speed of the fiber grinding wheel, namely, the grinding linear speed is changed by changing the rotating speed of the fiber grinding wheel, in particular, changing the frequency of a variable frequency motor in the fiber grinding mechanism.

Further, it should be noted that, during the grinding test, when other parameters are not changed, the pressing force Zt of the blade into the grinding wheel is proportional to the pressing depth Ht of the blade into the grinding wheel.

Specifically, the proportional relationship between the pressing force Zt of the blade into the fiber grinding wheel and the pressing depth Ht of the blade on the fiber grinding wheel can be obtained through grinding tests. According to the measured blade allowance, the track program of the six-axis robot 11 is adjusted, and the pressing depth Ht of the blade on the fiber grinding wheel 143 is controlled, so that the pressure Zt of pressing the blade into the fiber grinding wheel can be controlled.

Further, the pressing force Zt of the blade into the fiber grinding wheel has the greatest influence on the grinding accuracy of the ground round Rt, that is, the pressing depth Ht of the blade into the fiber grinding wheel has the greatest influence on the grinding accuracy of the ground round Rt, relative to other parameters.

Further, it should be noted that, during the grinding test, when other parameters are not changed, the slower the grinding feed speed Ft, the larger the removal amount of the air inlet and outlet edges of the blade, and the faster the grinding feed speed Ft, the smaller the removal amount of the air inlet and outlet edges of the blade, that is, the grinding feed speed Ft is inversely proportional to the grinding time.

Specifically, the proportional relationship between the grinding feed rate Ft and the grinding time may be obtained by a grinding test. The grinding feed speed Ft can be directly written in the program when the program of the movement locus of the six-axis robot 11 is compiled, and the preset grinding feed speed can be obtained.

Finally, the invention provides a blade of an aircraft engine, which is manufactured by the grinding device, the grinding method or the grinding parameter obtaining method of the grinding device.

Further, the grinding speed of the fiber grinding wheel 143 during grinding is 30m/s, and the grinding accuracy of the inlet and outlet edge fillet profile of the blade of the aircraft engine after grinding is within 0.01 mm.

In summary, compared with the prior art, the invention has the following advantages:

(1) the flexible property of the elastic fiber grinding wheel 143 under pressure can offset the precision error of the motion track of the six-axis robot 11, so as to realize the high-precision grinding of the blade;

(2) the grinding processing of the exhaust edge of the inlet blade is realized in one device by the different rotating directions of the two fiber grinding wheels 143;

(3) the grinding allowance of the blades to be machined is measured and mastered on line through the laser measuring mechanism 12 so as to adjust the grinding track of each blade to be machined 16, and therefore high-precision and self-adaptive grinding of each blade to be machined 16 is achieved;

(4) verifying the included angle Bt between the blade and the grinding wheel, the grinding linear speed Vt, the pressure Zt for pressing the blade into the fiber grinding wheel, the grinding feed speed Ft and the relationship between the four parameters and the ground fillet Rt through a grinding test so as to facilitate the grinding device to replace a manual mode for grinding processing to achieve higher grinding precision;

(5) determining that the pressure Zt of pressing the blade into the fiber grinding wheel has the largest influence on the grinding precision of the ground fillet Rt;

(6) the blade of the aero-engine, which is manufactured by the grinding parameters obtained by the grinding device, the grinding method or the grinding parameter obtaining method of the grinding device, has the grinding precision of the intake and exhaust edge fillet profile within 0.01 mm.

It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. For embodiments of the method, reference is made to the description of the apparatus embodiments in part. The present invention is not limited to the specific steps and structures described above and shown in the drawings. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.

The above description is only an example of the present application and is not limited to the present application. Various modifications and alterations to this application will become apparent to those skilled in the art without departing from the scope of this invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.