阅读说明：本技术 一种电阻焊接设备及热管的焊接方法 (Resistance welding equipment and welding method of heat pipe ) 是由 李金波 刘哲洪 姚永清 于 2020-06-23 设计创作，主要内容包括：本发明涉及焊接技术领域,公开了一种电阻焊接设备及热管的焊接方法,电阻焊接设备用于对管组件进行焊接,管组件包括主管以及设置于主管内的内衬管,电阻焊接设备包括第一焊接机头、第二焊接机构和电控装置,第一焊接机头包括转动设置的第一电极,管组件套设在第一电极上,第二焊接机头包括转动设置的第二电极,第二电极与第一电极平行设置,第二焊接机头被配置为能够靠近或远离第一焊接机头,以使第一电极和第二电极夹紧或放松管组件的侧壁,电控装置通过输出电缆与第一电极和第二电极电性连接。该电阻焊接设备保障了管组件焊接后接合良好,而且无需对管组件进行加热处理,保持管组件的硬度。(The invention relates to the technical field of welding, and discloses a resistance welding device and a welding method of a heat pipe, wherein the resistance welding device is used for welding a pipe assembly, the pipe assembly comprises a main pipe and a lining pipe arranged in the main pipe, the resistance welding device comprises a first welding head, a second welding mechanism and an electric control device, the first welding head comprises a first electrode which is rotatably arranged, the pipe assembly is sleeved on the first electrode, the second welding head comprises a second electrode which is rotatably arranged, the second electrode is parallel to the first electrode, the second welding head is configured to be close to or far away from the first welding head so as to enable the first electrode and the second electrode to clamp or loosen the side wall of the pipe assembly, and the electric control device is electrically connected with the first electrode and the second electrode through output cables. The resistance welding equipment ensures that the pipe assembly is well jointed after being welded, does not need to heat the pipe assembly, and keeps the hardness of the pipe assembly.)

1. A resistance welding apparatus for welding a pipe assembly (100), the pipe assembly (100) comprising a main pipe (101) and a liner pipe (102) disposed within the main pipe (101), the resistance welding apparatus comprising:

the first welding head comprises a first electrode (1) which is arranged in a rotating mode, and the pipe assembly (100) is sleeved on the first electrode (1);

a second welding head comprising a rotatably arranged second electrode (2), said second electrode (2) being arranged in parallel with said first electrode (1), said second welding head being configured to be able to be moved closer to or away from said first welding head such that said first electrode (1) and said second electrode (2) grip a sidewall of said tube assembly (100); and

and the electric control device (3) is electrically connected with the first electrode (1) and the second electrode (2) through output cables.

2. A resistance welding device according to claim 1, characterized in that said first electrode (1) and said second electrode (2) are both of cylindrical configuration.

3. The resistance welding apparatus according to claim 1, wherein the first electrode (1) and the second electrode (2) have a length equal to or greater than a length of the tube assembly (100), and an outer diameter of the first electrode (1) is smaller than an inner diameter of the tube assembly (100).

4. A resistance welding apparatus according to claim 1, characterized in that said first electrode (1) and said second electrode (2) are rotated in opposite directions.

5. A resistance welding apparatus according to claim 1, wherein the second welding head comprises a second carriage on which the second electrode (2) is rotatably arranged, the second carriage being connected to a first drive mechanism configured to drive the second carriage and the second electrode (2) towards or away from the first electrode (1).

6. The resistance welding apparatus according to claim 1, further comprising:

the second driving mechanism (4) is electrically connected with the electric control device (3), and the output end of the second driving mechanism (4) is connected with the first electrode (1) so as to drive the first electrode (1) to rotate; and

and the third driving mechanism (5) is electrically connected with the electric control device (3), and the output end of the third driving mechanism (5) is connected with the second electrode (2) so as to drive the second electrode (2) to rotate.

7. A method of welding a heat pipe, using the resistance welding apparatus of any one of claims 1-6, for welding a structure in which a pipe assembly (100) is a heat pipe, comprising the steps of:

sleeving the tube assembly (100) over the first electrode (1);

the second electrode (2) presses the side wall of the pipe assembly (100) between the first electrode (1) and the second electrode (2) and forms a welding loop with a welding power supply of the electric control device (3);

the first electrode (1) and the second electrode (2) are rotated to weld the tube assembly (100).

8. A heat pipe welding method according to claim 7, wherein the first electrode (1) and the second electrode (2) stop rotating when the pipe assembly (100) is rotated by an angle equal to or greater than 360 °.

9. A method for welding a heat pipe according to claim 7, wherein after the welding is completed, the second electrode (2) is detached from the welded pipe assembly (100), and the pipe assembly (100) is removed.

10. A method of welding a heat pipe according to claim 7 wherein the first electrode (1) and the second electrode (2) are rotated at equal angular velocities.

Technical Field

The invention relates to the technical field of welding, in particular to a welding method of a heat pipe of resistance welding equipment.

Background

Along with the rapid development of science and technology and the abundance of people's life, electronic products bring great convenience to people's life, wherein the heat dissipation of electronic products is an important difficult problem of electronic product research and development, along with the increase of electronic product functions, the calorific capacity of electronic products is bigger and bigger, and in order to solve the heat dissipation problem of electronic products, the application of ultra-thin heat pipes in electronic products has emerged in a large number at present.

The ultrathin heat pipe comprises a main pipe and a capillary structure attached to the inner wall of the main pipe, when the ultrathin heat pipe is used for heat dissipation, a cooling medium is filled in the heat pipe, and the cooling medium is cooled and reflows through the capillary structure after the hot end of the cooling medium is heated, so that the purpose of heat dissipation is achieved. The ultra-thin heat pipe is different from a common heat pipe in that the total thickness of the pipe wall of the ultra-thin heat pipe is smaller, and the heat dissipation effect is better. Generally, a heat pipe adopts a net burning or powder burning process to weld a capillary structure and a main pipe structure into an integral structure, the total thickness of the ultrathin heat pipe is thinner, the thickness requirement cannot be met by adopting the powder burning process, only the net burning process can be adopted, but the pipe wall of the main pipe is softened in the net burning production process, the hardness of the main pipe cannot be maintained, the heat pipe is deformed, and great difficulty is brought to subsequent processing; and the degree of bonding between the inner wall of the main tube and the capillary structure is likely to be poor.

Disclosure of Invention

The invention aims to provide a resistance welding device and a welding method of a heat pipe, which have good joint after welding, do not need to heat a pipe assembly, keep the hardness of the pipe assembly and avoid the deformation of the pipe assembly.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a resistance welding device, which is used for welding a pipe assembly, wherein the pipe assembly comprises a main pipe and a lining pipe arranged in the main pipe, and the resistance welding device comprises:

the first welding head comprises a first electrode which is arranged in a rotating mode, and the pipe assembly is sleeved on the first electrode;

a second welding head including a rotatably disposed second electrode disposed parallel to the first electrode, the second welding head configured to be movable toward and away from the first welding head to cause the first electrode and the second electrode to grip or release a sidewall of the tube assembly; and

and the electric control device is electrically connected with the first electrode and the second electrode through an output cable.

This resistance welding equipment is through establishing the pipe subassembly cover on first electrode, the second electrode can be close to or keep away from first welding aircraft nose, when the welding, the lateral wall of tight pipe subassembly of first electrode and second electrode clamp to make first electrode, second electrode and electrically controlled device electric connection, rotate the in-process at first electrode and second electrode and weld the pipe subassembly, it is good to have ensured the pipe subassembly welding back joint, and need not to carry out heat treatment to the pipe subassembly, keep the hardness of pipe subassembly, avoid taking place to warp.

As a preferable mode of the resistance welding apparatus, the first electrode and the second electrode are both of a cylindrical structure.

The first electrode and the second electrode are cylindrical structures, the pipe assembly can be subjected to roll welding, and the welding operation is convenient.

As a preferable mode of the resistance welding apparatus, the length of the first electrode and the second electrode is equal to or greater than the length of the pipe assembly, and the outer diameter of the first electrode is smaller than the inner diameter of the pipe assembly.

Through the setting, the pipe assembly in the whole length direction can be welded, the inner diameter of the pipe assembly is smaller than or equal to the outer diameter of the first electrode, the side wall of the pipe assembly can be clamped between the first electrode and the second electrode when the second electrode abuts against the pipe assembly, and the pipe assembly can be driven to rotate conveniently through the rotation of the first electrode and the second electrode, so that the circumferential welding of the pipe assembly is realized.

As a preferable mode of the resistance welding apparatus, the first electrode and the second electrode are rotated in opposite directions.

The pipe assembly is rotated between the first electrode and the second electrode by the rotation directions of the first electrode and the second electrode being opposite, so that circumferential welding of the pipe assembly is achieved.

As a preferable mode of the resistance welding apparatus, the second welding head includes a second support, the second electrode is rotatably disposed on the second support, the second support is connected to a first driving mechanism, and the first driving mechanism is configured to drive the second support and the second electrode to approach or separate from the first electrode.

The second electrode can be close to or far away from the first electrode through the first driving mechanism, so that the first electrode, the second electrode, the tube assembly and the electric control device form a welding loop, and the welding device is convenient to operate and easy to control.

As a preferable aspect of the above resistance welding apparatus, the resistance welding apparatus further includes:

the output end of the second driving mechanism is connected with the first electrode so as to drive the first electrode to rotate; and

and the output end of the third driving mechanism is connected with the second electrode so as to drive the second electrode to rotate.

The second driving mechanism and the third driving mechanism are arranged to facilitate the rotation of the first electrode and the second electrode, and the second driving mechanism and the third driving mechanism respectively drive the first electrode and the second electrode to rotate, so that the control is flexible.

The invention also provides a welding method of the heat pipe, which adopts the resistance welding equipment for welding the structure of the heat pipe of the pipe component, and comprises the following steps:

sleeving the tube assembly on the first electrode;

the second electrode presses the side wall of the tube assembly between the first electrode and the second electrode, and the second electrode and a welding power supply of the electric control device form a welding loop;

the first electrode and the second electrode rotate to weld the tube assembly.

According to the welding method of the heat pipe, the pipe assembly is sleeved on the first electrode, the side wall of the pipe assembly is pressed between the first electrode and the second electrode by the second electrode, a welding loop is formed between the second electrode and the electric control device, the pipe assembly is welded by rotating the first electrode and the second electrode, the welding process is simple and convenient, good joint of the welded pipe assembly is guaranteed, the pipe assembly does not need to be heated, the hardness of the pipe assembly is kept, and deformation is avoided.

As a preferable mode of the welding method for the heat pipe, when the pipe assembly is rotated by an angle equal to or greater than 360 °, the first electrode and the second electrode stop rotating.

When the rotation angle of the welding assembly is more than or equal to 360 degrees, the first electrode and the second electrode stop rotating, so that the whole circumference of the pipe assembly is welded, and the welding is firm.

As a preferable embodiment of the welding method for the heat pipe, after the welding is completed, the second electrode is separated from the welded pipe assembly, and the pipe assembly is removed.

After the welding is finished, the welded pipe assembly is separated through the second electrode, and the pipe assembly is convenient to take down.

As a preferable mode of the welding method for the heat pipe, the first electrode and the second electrode rotate at the same angular velocity.

First electrode and second electrode pivoted angle equal to can be relatively stable to the rotational drive power of pipe subassembly, the welding effect is better.

The invention has the beneficial effects that:

according to the resistance welding equipment, the pipe assembly is sleeved on the first electrode, the second electrode can be close to or far away from the first welding machine head, the first electrode and the second electrode clamp the side wall of the pipe assembly during welding, so that the first electrode and the second electrode are electrically connected with the electric control device, the pipe assembly is welded in the rotating process of the first electrode and the second electrode, good joint of the pipe assembly after welding is guaranteed, the pipe assembly does not need to be heated, the hardness of the pipe assembly is maintained, and deformation is avoided.

According to the welding method of the heat pipe, the pipe assembly is sleeved on the first electrode, the second electrode enables the side wall of the pipe assembly to be pressed between the first electrode and the second electrode, the welding loop is formed between the first electrode and the second electrode, the pipe assembly is welded by the rotation of the first electrode and the second electrode, the welding process is simple and convenient, the good joint of the pipe assembly after welding is guaranteed, the pipe assembly does not need to be heated, the hardness of the pipe assembly is kept, and deformation is avoided.

Drawings

FIG. 1 is a schematic structural view of a tube assembly provided by the present invention;

FIG. 2 is a schematic view of the main pipe and the lining pipe to be assembled according to the present invention;

FIG. 3 is a schematic structural view of a resistance welding apparatus provided by the present invention;

fig. 4 is a schematic structural diagram of the first electrode, the second electrode and the tube assembly during welding by the resistance welding apparatus of the present invention.

In the figure:

1. a first electrode; 2. a second electrode; 3. an electric control device; 4. a second drive mechanism; 5. a third drive mechanism;

100. a tube assembly; 101. a main pipe; 102. and (4) lining the pipe.

Detailed Description

In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. 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 invention.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. 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.

As shown in fig. 1 and 2, the present embodiment provides a resistance welding apparatus for welding a pipe assembly 100, wherein the pipe assembly 100 includes a main pipe 101 and a lining pipe 102, and the main pipe 101 and the lining pipe 102 are welded together by the resistance welding apparatus. In this embodiment, the tube assembly 100 is welded by a resistance welding device in a structure of an ultra-thin heat tube, and the inner liner tube 102 of the heat tube is in a capillary structure. The ultrathin heat pipe is a common heat dissipation structure for heat dissipation of electronic products, when the ultrathin heat pipe is used for heat dissipation, a cooling medium is filled in the heat pipe, and the cooling medium is cooled and reflows through a capillary structure after being heated at a hot end, so that the purpose of heat dissipation is achieved. In the prior art, the pipe wall of the main pipe of the ultrathin heat pipe is softened and deformed in the welding process through a net burning process, so that the subsequent processing is difficult; and avoid the problem that the inner wall of the main pipe and the capillary structure have poor bonding degree. In order to solve the above problem, as shown in fig. 3 and 4, the resistance welding apparatus in the present embodiment includes a first welding head, a second welding head, and an electric control device 3, the first welding head includes a first electrode 1 rotatably disposed, a tube assembly 100 is sleeved on the first electrode 1, the second welding head includes a second electrode 2 rotatably disposed, the second electrode 2 is disposed in parallel with the first electrode 1, the second welding head is configured to be able to approach or be away from the first welding head so that the first electrode 1 and the second electrode 2 clamp or loosen a side wall of the tube assembly 100, and the electric control device 3 is electrically connected to the first electrode 1 and the second electrode 2 through an output cable.

This resistance welding equipment is through establishing pipe assembly 100 cover on first electrode 1, second electrode 2 can be close to or keep away from first welding aircraft nose, when the welding, the lateral wall of pipe assembly 100 is pressed from both sides tightly to first electrode 1 and second electrode 2, so that first electrode 1, second electrode 2 and electrically controlled device 3 electric connection, rotate the in-process at first electrode 1 and second electrode 2 and weld pipe assembly 100, it is good to have ensured that pipe assembly 100 welds the back joint, and need not to carry out heat treatment to pipe assembly 100, keep the hardness of pipe assembly 100.

Optionally, the first electrode 1 and the second electrode 2 are both cylindrical structures, and can perform roll welding on the tube assembly 100, so that the welding operation is convenient. The first electrode 1 and the second electrode 2 are arranged in an up-down opposite mode, the second electrode 2 can be close to or far away from the first electrode 1 along the vertical direction, due to the arrangement, after the pipe assembly 100 is sleeved on the first electrode 1, the abutting force of the pipe assembly 100 and the first electrode 1 can be increased through gravity, the side wall of the pipe assembly 100 can be abutted tightly between the first electrode 1 and the second electrode 2 through the second electrode 2, and the welding effect is guaranteed.

Specifically, the first welding head includes a first bracket (not shown), on which the first electrode 1 is rotatably disposed, and preferably, the first electrode 1 is a cantilever structure disposed on the first bracket, which facilitates the installation of the tube assembly 100. In order to realize the rotation of the first electrode 1, the resistance welding device further comprises a second driving mechanism 4, and the output end of the second driving mechanism 4 is connected with the first electrode 1 so as to drive the first electrode 1 to rotate relative to the first support. The specific structure of the second driving mechanism 4 is not particularly limited as long as the rotation of the first electrode 1 can be achieved.

The second welding head comprises a second support (not shown) on which the second electrode 2 is rotatably arranged, preferably the second electrode 2 is a cantilever structure arranged on the second support, which facilitates abutting the tube assembly 100 on the first electrode 1. The second support is connected to a first drive mechanism configured to drive the second support and the second electrode 2 towards or away from the first electrode 1. The second electrode 2 can be close to or far away from the first electrode 1 through the first driving mechanism, so that the first electrode 1, the second electrode 2, the tube assembly 100 and the electric control device 3 form a conductive welding loop, and the welding device is convenient to operate and easy to control.

In order to realize the rotation of the second electrode 2, the resistance welding device further comprises a third driving mechanism 5, and an output end of the third driving mechanism 5 is connected with the first electrode 1 so as to drive an output end of the third driving mechanism 5 to be connected with the second electrode 2 so as to drive the second electrode 2 to rotate. The specific structure of the third driving mechanism 5 is not particularly limited as long as the rotation of the second electrode 2 can be achieved. In this embodiment, the second driving mechanism 4 and the third driving mechanism 5 respectively drive the first electrode 1 and the second electrode 2 to rotate, so that the control is flexible.

Optionally, the resistance welding apparatus may further include a support frame (not shown in the figure), the first support is mounted on the support frame, the second support is movably mounted on the support frame, the first support and the second support can be mounted through the support frame, and the structure of the specific support frame is not specifically limited herein as long as the first welding head and the second welding head can be mounted.

The electric control device 3 comprises a welding power supply and a control device, the first driving mechanism, the second driving mechanism 4, the third driving mechanism 5 and the welding battery are electrically connected with the control device, and the control device controls the first driving mechanism to drive the second electrode 2 to be close to or far away from the first electrode 1; the second driving mechanism 4 and the third driving mechanism 5 are controlled by a control device to respectively drive the first electrode 1 and the second electrode 2 to rotate, open, close and rotate; the on-off of the welding battery is controlled by the control device so as to realize the connection or disconnection of the welding loop.

The control device controls the welding power supply to be started, the first electrode 1, the second electrode 2, the tube assembly 100 and the welding power supply form a conducted welding loop, and the first electrode 1 and the second electrode 2 discharge at the same time to weld the tube assembly 100 between the first electrode 1 and the second electrode 2; the control device controls the welding power supply to turn on and turn off the welding battery, the first electrode 1, the second electrode 2, the tube assembly 100 and the welding battery form a non-conductive welding loop, at the moment, the first electrode 1 and the second electrode 2 cannot discharge electricity, and welding of the tube assembly 100 cannot be achieved.

As shown in fig. 3, the lengths of the first electrode 1 and the second electrode 2 are equal to or greater than the length of the tube assembly 100, and the outer diameter of the first electrode 1 is smaller than the inner diameter of the tube assembly 100. Can weld whole length direction's pipe assembly 100 through above-mentioned setting, through the internal diameter with the external diameter less than or equal to pipe assembly 100 of first electrode 1, the lateral wall that can be when second electrode 2 supports and presses pipe assembly 100 of pipe assembly 100 presss from both sides tightly between first electrode 1 and second electrode 2 to can be convenient for drive pipe assembly 100 through the rotation of first electrode 1 and second electrode 2 and rotate, in order to realize the circumference welding of pipe assembly 100.

As shown in fig. 4, the first electrode 1 and the second electrode 2 rotate in opposite directions. The tube assembly 100 is rotated between the first electrode 1 and the second electrode 2 by the opposite rotation directions of the first electrode 1 and the second electrode 2 so as to achieve circumferential welding of the tube assembly 100.

The invention also provides a welding method of the heat pipe, which adopts the resistance welding equipment to weld the structure of the heat pipe of the pipe component 100, and the welding method of the heat pipe comprises the following steps:

the tube assembly 100 is fitted over the first electrode 1.

The second electrode 2 presses the side wall of the tube assembly 100 between the first electrode 1 and the second electrode 2 and forms a welding loop with the welding power supply of the electric control device 3.

The first electrode 1 and the second electrode 2 are rotated to weld the tube assembly 100.

According to the welding method of the heat pipe, the pipe assembly 100 is sleeved on the first electrode 1, the second electrode 2 enables the side wall of the pipe assembly 100 to be pressed between the first electrode 1 and the second electrode 2, and a welding loop is formed between the first electrode 1 and the second electrode 2 and the electric control device 3, the pipe assembly 100 is welded through rotation of the first electrode 1 and the second electrode 2, the welding process is simple and convenient, good joint of the pipe assembly 100 after welding is guaranteed, heating treatment of the pipe assembly 100 is not needed, hardness of the pipe assembly 100 is kept, and deformation of the welded heat pipe is avoided.

When the rotation angle of the pipe assembly 100 is greater than or equal to 360 degrees, the first electrode 1 and the second electrode 2 stop discharging and stop rotating, so that the whole circumference of the pipe assembly 100 is welded, and the welding is firm. To achieve a secure weld around the tube assembly 100, the tube assembly 100 may be rotated 380 ° to provide a partial overlap of the welds to ensure the secure weld. Of course, the rotation angle of the pipe assembly 100 can be 400 °, 450 °, 500 °, etc., and the rotation angle of the pipe assembly 100 can be set as required.

After the welding is finished, the second electrode 2 is separated from the welded pipe assembly 100, and the pipe assembly 100 is taken down, so that the pipe assembly 100 is welded, and the pipe assembly 100 is taken down conveniently by separating the second electrode 2 from the welded pipe assembly 100.

Optionally, the angular speeds of the rotation of the first electrode 1 and the second electrode 2 are equal, so that the rotation driving force of the tube assembly 100 can be stable, and the welding effect is good.

In this embodiment, the heat pipe is a copper heat pipe, and the welding of the copper heat pipe is taken as an example for specific description. The copper heat pipe comprises a copper main pipe and a copper pipe network attached to the inner wall of the copper main pipe, and the heat dissipation effect of the copper heat pipe is good.

First, a copper heat pipe is sleeved on the first electrode 1.

Then, the control device controls the first driving mechanism to drive the second electrode 2 to press down and form a conductive welding loop with the copper heat pipe and the second electrode 2.

The control device controls the second driving mechanism 4 and the third driving mechanism 5 to respectively drive the first electrode 1 and the second electrode 2 to rotate reversely and at the same angular speed.

The control device controls the welding power supply to be started, the first electrode 1 and the second electrode 2 discharge at the same time, when the copper heat pipe rotates for 380 degrees, the control device controls the electric control device 3 to be closed, and controls the second driving mechanism 4 and the third driving mechanism 5 to respectively drive the first electrode 1 and the second electrode 2 to stop rotating.

The control device controls the second driving mechanism 4 to drive the second electrode 2 to reset, and the welded copper heat pipe is taken down from the first electrode 1, and at the moment, the welding of the copper heat pipe is finished.

In the description herein, it is to be understood that the terms "upper", "lower", "right", and the like are used in a descriptive sense or a positional relationship based on the orientation shown in the drawings for convenience of description and simplicity of operation, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used merely for descriptive purposes and are not intended to have any special meaning.

In the description herein, references to the description of "an embodiment," "an example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example.

In addition, the foregoing is only the preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.