阅读说明：本技术 一种孔内槽内壁表面抛光装置及其抛光方法 (Polishing device and polishing method for inner wall surface of groove in hole ) 是由 王匀 薛沈伟 李富柱 严莹 张昆 任立辉 于 2021-08-02 设计创作，主要内容包括：本发明提供了一种孔内槽内壁表面抛光装置及其抛光方法,该装置包括上活塞、下外活塞、下内活塞、喷嘴机构和驱动机构,上活塞设置于孔内槽的上端,下外活塞和下内活塞设置于孔内槽的下端,上活塞与孔内槽的上端孔内壁紧密贴合,形成第一腔体,下外活塞的外壁与孔内槽的下端孔内壁紧密贴合,形成第二腔体,上活塞上设有连通至第一腔体的注水孔,下外活塞的顶端还设有若干单向阀,喷嘴机构设置于下外活塞上,且喷嘴位于孔内槽中,驱动机构驱动下内活塞上下运动,使得孔内槽的液体压力交变产生空化,复合喷嘴产生水射流,将空化射流均匀的喷射至孔内槽的各个位置,从而提高孔内槽的表面质量。(The invention provides a polishing device and a polishing method for the inner wall surface of an in-hole groove, the device comprises an upper piston, a lower outer piston, a lower inner piston, a nozzle mechanism and a driving mechanism, wherein the upper piston is arranged at the upper end of the in-hole groove, the lower outer piston and the lower inner piston are arranged at the lower end of the in-hole groove, the upper piston is tightly attached to the inner wall of an upper end hole of the in-hole groove to form a first cavity, the outer wall of the lower outer piston is tightly attached to the inner wall of a lower end hole of the in-hole groove to form a second cavity, a water injection hole communicated with the first cavity is arranged on the upper piston, a plurality of one-way valves are also arranged at the top end of the lower outer piston, the nozzle mechanism is arranged on the lower outer piston, and the nozzle is positioned in the in-hole groove, the driving mechanism drives the lower inner piston to move up and down, so that the liquid pressure of the in-hole groove generates alternating cavitation, the composite nozzle generates water jet, and jets are uniformly jetted to each position of the in-hole groove, thereby improving the surface quality of the grooves in the holes.)

1. The utility model provides a downthehole groove inner wall surface finish device which characterized in that includes: the device comprises an upper piston (1), a lower outer piston (3), a lower inner piston (4), a nozzle mechanism, a workpiece clamp (10) and a driving mechanism;

the processing workpiece (9) is arranged on the workpiece clamp (10), a hole inner groove is arranged on the processing workpiece (9), the upper piston (1) is arranged at the upper end of the hole inner groove, the lower outer piston (3) and the lower inner piston (4) are arranged at the lower end of the hole inner groove, the lower inner piston (4) is positioned inside the lower outer piston (3), the upper piston (1) is tightly attached to the inner wall of the upper end hole of the hole inner groove, the outer wall of the lower outer piston (3) is tightly attached to the inner wall of the lower end hole of the hole inner groove, the upper piston (1), the lower outer piston (3) and the hole inner groove form a closed first cavity, the inner wall of the lower outer piston (3) is tightly attached to the lower inner piston (4), the inner wall of the lower outer piston (3) and the lower inner piston (4) form a second cavity, and the volume of the second cavity is zero in an initial state;

the upper piston (1) is provided with a water injection hole communicated to the first cavity, the nozzle mechanism is installed at the top end of the lower outer piston (3), a nozzle in the nozzle mechanism is positioned in the first cavity, liquid in the second cavity can reach the nozzle, the top end of the lower outer piston (3) is also provided with a plurality of one-way valves (303), and the one-way valves (303) enable the liquid to flow into the second cavity from the first cavity;

the driving mechanism can drive the lower inner piston (4) to move up and down.

2. The polishing device for the inner wall surface of the inner groove in the hole as claimed in claim 1, wherein the nozzle mechanism comprises a water pipe (301) and a nozzle cap (401), the bottom port of the water pipe (301) is communicated with the second cavity, the top end of the water pipe is located in the first cavity, the nozzle cap (401) is installed, and a plurality of nozzles are arranged on the nozzle cap (401).

3. The polishing device for the inner wall surface of the slot in the hole as claimed in claim 2, wherein the nozzle cap (401) is of a cubic structure, the nozzle cap (401) can rotate around the central axis of the water pipe (301), the nozzles are arranged on four outer side walls of the nozzle cap (401), and the nozzles are all deviated from the same side of the central line of the outer side wall.

4. The polishing device for the inner wall surface of the hole and the inner groove as claimed in claim 1, wherein the nozzle mechanism comprises a special-shaped nozzle (1301), the special-shaped nozzle (1301) is mounted at the top end of the lower outer piston (3), a first through hole is formed in the top end of the lower outer piston (3), a second through hole is formed in the special-shaped nozzle (1301), the second through hole is communicated with the first through hole, a plurality of spray holes are formed in the outer wall of the special-shaped nozzle (1301), the spray holes are communicated with the second through hole, and the shape of the outer wall of the special-shaped nozzle (1301) is the same as that of the inner wall surface of the hole and the inner groove.

5. The polishing device for the inner wall surface of the inner groove of the hole as claimed in claim 1, wherein the driving mechanism comprises a connecting rod (5), a fluted disc (6), a worm (7) and a driving motor (14), one end of the connecting rod (5) is connected with the bottom end of the lower inner piston (4), the other end of the connecting rod is connected with the worm wheel (6), the worm wheel (6) is meshed with the worm (7), and the driving motor (14) drives the worm (7) to enable the lower inner piston (4) to reciprocate up and down.

6. The polishing apparatus for the inner wall surface of a groove in a hole according to claim 5, further comprising a control unit (13), wherein the control unit (13) is connected to the driving motor (14).

7. The polishing device for the inner wall surface of the inner groove of the hole as claimed in claim 1, further comprising a positioning mechanism, wherein the positioning mechanism comprises an upper lifting table (8) and a lower lifting table (12), the upper lifting table (8) is connected with the upper piston (1) to control the upper piston (1) to lift, and the lower lifting table (12) is connected with the lower outer piston (3) to control the lower outer piston (3) to lift.

8. The polishing apparatus for the inner wall surface of a groove in a hole according to claim 1, wherein the upper lift table (8) and the lower lift table (12) are each a controllable screw lift table.

9. A polishing method using the polishing apparatus for an inner wall surface of a groove in a hole according to any one of claims 1 to 8, comprising:

step A: mounting a processing workpiece (9) on a workpiece clamp (10);

and B: the control unit (13) controls the positioning mechanism, so that the upper piston (1) is positioned at the upper end of the inner groove of the hole, and the lower outer piston (3) is positioned at the lower end of the inner groove of the hole;

and C: the control unit (13) controls the driving motor (14) to enable the lower inner piston (4) to be tightly attached to the lower wall of the lower outer piston (3), a water injection hole is opened, water is injected into the first cavity, and the water level reaches the lower end face of the upper piston (1);

step D: the control unit (13) controls the driving motor (14), the lower inner piston (4) moves downwards from the highest position to the lowest position, liquid in the first cavity flows into the second cavity, and meanwhile, gas begins to be separated out from the first cavity;

step E: the control unit (13) controls the driving motor (14), the lower inner piston (4) moves from the lowest position to the highest position, the lower inner piston (4) pushes liquid to move to generate cavitation jet flow to be shot into the wall surface of the inner groove of the hole, meanwhile, the pressure in the first cavity continuously rises, and the separated gas is compressed to realize volume alternation;

step F: and D, repeating the step D and the step E until the processing is finished.

Technical Field

The invention relates to the field of surface polishing and machining and manufacturing of grooves in holes of parts, in particular to a device and a method for polishing the surface of the inner wall of the groove in the hole.

Background

With the progress and development of science and technology, a large number of parts with complex shapes are widely applied in various fields such as aerospace, precision instruments, military equipment and the like. The in-hole groove is a relatively complicated processing object, and is often accompanied by problems such as burrs, poor surface quality, and the like after processing. These problems directly affect the service performance of the parts and the quality of the whole equipment, so that the surface of the processed parts needs to be strengthened.

At present, the machining methods such as abrasive flow machining, electrochemical machining and the like can further perform polishing post-treatment on the inner hole. However, the above-mentioned processing method has certain limitations for the inner groove of the hole. The abrasive flow has poor fluidity during the processing process, and is easy to agglomerate in the inner groove, so that the processing effect is not uniform, the electrochemical processing can realize the flow in the inner groove of the hole, but the inner wall is easy to damage, and the processing precision is difficult to accurately control.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a polishing device for the inner wall surface of an in-hole groove, which can improve the surface quality of the in-hole groove.

The present invention achieves the above-described object by the following technical means.

An in-hole groove inner wall surface polishing device comprising: the device comprises an upper piston, a lower outer piston, a lower inner piston, a nozzle mechanism, a workpiece clamp and a driving mechanism;

the processing workpiece is arranged on the workpiece clamp, a hole inner groove is formed in the processing workpiece, the upper piston is arranged at the upper end of the hole inner groove, the lower outer piston and the lower inner piston are arranged at the lower end of the hole inner groove, the lower inner piston is positioned inside the lower outer piston, the upper piston is tightly attached to the inner wall of the hole at the upper end of the hole inner groove, the outer wall of the lower outer piston is tightly attached to the inner wall of the hole at the lower end of the hole inner groove, the upper piston, the lower outer piston and the hole inner groove form a closed first cavity, the inner wall of the lower outer piston is tightly attached to the lower inner piston, the inner wall of the lower outer piston and the lower inner piston form a second cavity, and the volume of the second cavity is zero in an initial state;

the upper piston is provided with a water injection hole communicated to the first cavity, the nozzle mechanism is installed at the top end of the lower outer piston, a nozzle in the nozzle mechanism is positioned in the first cavity, liquid in the second cavity can reach the nozzle, the top end of the lower outer piston is also provided with a plurality of one-way valves, and the one-way valves enable the liquid to flow into the second cavity from the first cavity;

the driving mechanism can drive the lower inner piston to move up and down.

Preferably, the nozzle mechanism comprises a water service pipe and a nozzle cap, the bottom port of the water service pipe is communicated with the second cavity, the top end of the water service pipe is located in the first cavity, the nozzle cap is installed on the water service pipe, and the nozzle cap is provided with a plurality of nozzles.

Preferably, the nozzle cap is of a cubic structure, the nozzle cap can rotate around the central axis of the water service pipe, the nozzles are arranged on the four outer side walls of the nozzle cap, and the nozzles are deviated from the same side of the central line of the outer side wall.

Preferably, the nozzle mechanism comprises a special-shaped nozzle, the special-shaped nozzle is mounted at the top end of the lower outer piston, a first through hole is formed in the top end of the lower outer piston, a second through hole is formed in the special-shaped nozzle and communicated with the first through hole, a plurality of spray holes are formed in the outer wall of the special-shaped nozzle and communicated with the second through hole, and the shape of the outer wall of the special-shaped nozzle is the same as that of the inner wall surface of the hole inner groove.

Preferably, the driving mechanism comprises a connecting rod, a fluted disc, a worm and a driving motor, one end of the connecting rod is connected with the bottom end of the lower inner piston, the other end of the connecting rod is connected with a worm wheel, the worm wheel is meshed with the worm, and the driving motor drives the worm to enable the lower inner piston to reciprocate up and down.

Preferably, the device further comprises a control unit, and the control unit is connected with the driving motor

Preferably, still include positioning mechanism, positioning mechanism includes elevating platform and lower elevating platform, go up the elevating platform and be connected with last piston, control upper piston goes up and down, lower elevating platform is connected with outer piston down, control outer piston lift down.

Preferably, the upper lifting platform and the lower lifting platform are both controllable screw rod lifting platforms.

The invention also provides a polishing method using the polishing device for the inner wall surface of the inner groove of the hole, which comprises the following steps:

step A: mounting a processing workpiece on a workpiece clamp;

and B: the control unit controls the positioning mechanism to enable the upper piston to be positioned at the upper end of the inner groove of the hole, and the lower outer piston to be positioned at the lower end of the inner groove of the hole;

and C: the control unit controls the driving motor to enable the lower inner piston to be tightly attached to the lower wall of the lower outer piston, a water injection hole is opened, water is injected into the first cavity, and the water level reaches the lower end face of the upper piston;

step D: the control unit controls the driving motor, the lower inner piston moves downwards from the highest position to the lowest position, liquid in the first cavity flows into the second cavity, and meanwhile, gas begins to be separated out from the first cavity;

step E: the control unit controls the driving motor, the lower inner piston moves from the lowest position to the highest position, the lower inner piston pushes liquid to move to generate cavitation jet flow to be shot into the wall surface of the inner groove of the hole, meanwhile, the pressure in the first cavity continuously rises, and the separated gas is compressed to realize volume alternation;

step F: and D, repeating the step D and the step E until the processing is finished.

The invention has the beneficial effects that:

1) the invention utilizes the principle of generating cavitation by liquid pressure alternation, the composite nozzle generates water jet, and the cavitation jet is uniformly sprayed to each position of the inner groove in the hole, particularly comprises the corner where the upper wall and the lower wall of the inner groove are jointed with the two surfaces, so that the uniform and blind-spot-free strengthening of the whole inner groove surface in the hole can be realized.

2) The invention actively positions the position of the inner groove of the part by utilizing the mode that the upper piston and the lower piston independently move, thereby avoiding influencing the surface quality of other areas of the part in the processing process, and being particularly suitable for accurately strengthening the surface quality of the inner wall of the groove at various positions in the hole.

3) The medium in the invention can be common tap water, and no secondary pollution is generated, so the invention has the remarkable advantages of low processing cost, environmental protection and the like, and can be widely applied to surface reinforcement of internal grooves at various positions in holes.

Drawings

FIG. 1 is a first schematic structural diagram of an apparatus for polishing the inner wall surface of a groove in a hole according to an embodiment of the present invention;

FIG. 2 is a second schematic structural diagram of an apparatus for polishing the inner wall surface of a groove in a hole according to an embodiment of the present invention;

FIG. 3 is an enlarged cross-sectional view of the lower outer piston and the lower inner piston of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of the lower outer piston and the lower inner piston of FIG. 2;

FIG. 5 is an enlarged view of the nozzle cap of FIG. 3;

fig. 6 is a sectional view showing the internal structure of the nozzle of fig. 5.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

First, an apparatus for polishing the inner wall surface of an intra-hole groove according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Example 1

Referring to fig. 1 to 6, an apparatus for polishing the inner wall surface of an internal groove of a hole according to an embodiment of the present invention includes an upper piston 1, a lower outer piston 3, a lower inner piston 4, a nozzle mechanism, a work holder 10, a driving mechanism, a positioning mechanism, and a case 2.

The workpiece fixture 10 is positioned in the box body 2, the processing workpiece 9 is arranged on the workpiece fixture 10, and an inner hole groove to be polished is formed in the processing workpiece 9.

The upper piston 1 is arranged at the upper end of the hole inner groove, the lower outer piston 3 and the lower inner piston 4 are arranged at the lower end of the hole inner groove, the lower inner piston 4 is positioned inside the lower outer piston 3, the upper piston 1 is tightly attached to the upper end hole inner wall of the hole inner groove, the outer wall of the lower outer piston 3 is tightly attached to the lower end hole inner wall of the hole inner groove, the upper piston 1, the lower outer piston 3 and the hole inner wall form a closed first cavity, the inner wall of the lower outer piston 3 is tightly attached to the lower inner piston 4, the inner wall of the lower outer piston 3 and the lower inner piston 4 form a second cavity, and in an initial state, the volume of the second cavity is zero, namely, the top end inner wall of the lower outer piston 3 is tightly attached to the top end outer wall of the lower inner piston 4.

The upper piston 1 is provided with a water injection hole communicated to the first cavity and can inject water medium into the first cavity. The nozzle mechanism is installed on the top end of the lower outer piston 3, a nozzle in the nozzle mechanism is located in the first cavity, liquid in the second cavity can reach the nozzle, the top end of the lower outer piston 3 is further provided with a plurality of one-way valves 303, and the one-way valves 303 enable the liquid to flow into the second cavity only through the first cavity.

The well nozzle mechanism of this example includes water service pipe 301 and nozzle cap 401, and the bottom port and the second cavity intercommunication of water service pipe 301, the top is located first cavity, and installs nozzle cap 401, and nozzle cap 401 is the cube structure, and nozzle cap 401 can be rotatory around water service pipe 301's the central axis, all is equipped with the nozzle on four lateral walls of nozzle cap 401, and a plurality of nozzles all lean on the homonymy of the central line of place lateral wall, and nozzle cap 401 can rotate spontaneously under the drive of the inertia of water like this.

The driving mechanism comprises a connecting rod 5, a fluted disc 6, a worm 7, a control unit 13 and a driving motor 14, one end of the connecting rod 5 is rotatably connected with the bottom end of the lower inner piston 4, the other end of the connecting rod is rotatably connected with a worm wheel 6, the rotating center of the worm wheel 6 and the rotating center of the other end of the connecting rod 5 are eccentrically arranged, the worm wheel 6 is meshed with the worm 7, the driving motor 14 drives the worm 7, the driving motor 14 is fixed on the outer box 2, and the control unit 13 controls the rotating speed and the rotation stop of the driving motor 14, so that the up-and-down movement of the inner piston 4 is controlled.

The positioning mechanism comprises an upper lifting platform 8, a lower lifting platform 12 and a control unit 13, the upper lifting platform 8 is a controllable screw rod lifting platform, the table surface of the upper lifting platform 8 is connected with the outer end of the upper piston 1 through a bolt, the lower end of the upper lifting platform 8 is fixed on the outer box 2 through a bolt, the lower lifting platform 12 is a controllable screw rod lifting platform, the table surface of the lower lifting platform 12 is connected with the outer end of the lower outer piston 3 through a bolt, the lower end of the lower lifting platform 12 is fixed on the outer box 2 through a bolt, and the control unit 13 controls the upper lifting platform 8 and the lower lifting platform 12 to move.

The working process of the polishing device for the inner wall surface of the groove in the hole according to the embodiment comprises the following steps:

firstly, a processing workpiece 9 is placed on a workpiece clamp 10 on a working platform 11 and clamped, then a lower outer piston 3 and a lower inner piston 44 are inserted into the lower end of a workpiece hole, at the moment, a control unit 13 adjusts a lower lifting platform 12 to determine the position of the lower outer piston 3, so that the top end of the lower outer piston 3 is just aligned with the lower end of the inner groove of the processing workpiece 9 and is kept fixed, the control unit 13 controls a driving motor 14 to just and tightly attach the top wall of the lower inner piston 44 to the bottom wall of the lower outer piston 3, and the stroke of the lower inner piston 44 is minimum at the moment. Next, the control unit 13 adjusts the upper lifting table 8 so that the lower end of the upper piston 1 is aligned with and fixed to the upper end of the inner groove of the workpiece hole, opens the water injection hole of the upper piston 1, injects water into the first cavity until the water level just reaches the lower end of the upper piston 1, and closes the water injection hole.

The control unit 13 controls the driving motor 14 to drive the worm 7 to rotate, so as to drive the fluted disc 6 and the connecting rod 5 to enable the lower inner piston 44 to realize reciprocating motion, the lower inner piston 44 firstly moves from a minimum stroke position to a maximum stroke position, at the moment, water in the first cavity rapidly moves downwards through the one-way valve 303 under the action of gravity and pressure to enter a space formed by the lower inner piston 44 and the lower outer piston 3, then the lower inner piston 44 moves from the maximum stroke position to the minimum stroke position, due to the existence of the one-way valve 303, the water can only enter the nozzle cap 401 from a hole at the lower end of the water pipe 301 to be sprayed out, so that the liquid level in the first cavity rises, the nozzle cap 401 is always submerged in a water medium, nozzles on the nozzle cap 401 are obliquely symmetrical and can spontaneously rotate under the driving of inertia of the water, and the nozzle cap 401 continuously rotates and upwards moves along with the movement of the lower inner piston 44 in the process, the nozzle sweeping area continuously covers all wall surfaces of the whole inner groove, and at the moment, due to the fact that liquid pressure is increased, bubbles separated out when the size is increased are driven by the water jet to collapse close to the wall surfaces, generated micro jet carries out flexible hammering on the wall surfaces, the shot blasting effect is achieved, and the surface quality of the inner groove of the hole is strengthened. After a predetermined number of machining steps, the control unit 13 stops the driving motor 14, and the control unit 13 controls the upper and lower lifters 8 and 12 to move the upper and lower pistons 1 and 3 out of the machined workpiece 9, and unscrews the workpiece retainer 10 and takes out the machined workpiece 9.

Example 2

The structure of the present embodiment is the same as that of embodiment 1 except that the nozzle mechanism is different from that of embodiment 1.

The nozzle mechanism in the embodiment comprises a special-shaped nozzle 1301, the special-shaped nozzle 1301 is installed at the top end of a lower outer piston 3, a first through hole is formed in the top end of the lower outer piston 3, a second through hole is formed in the special-shaped nozzle 1301 and is communicated with the first through hole, a plurality of spray holes are formed in the outer wall of the special-shaped nozzle 1301 and are communicated with the second through hole, the outer wall of the special-shaped nozzle 1301 is identical to the inner wall surface of an in-hole groove in shape, the wall surface of a special-shaped inner groove can be uniformly processed, a cavitation effect is generated in a first cavity under the condition of volume alternation, cavitation bubbles are broken at the position close to the wall surface under the driving of cavitation water jet generated by the special-shaped nozzle 1301, and the generated micro jet can hammer the wall surface to achieve the effect of strengthening the surface quality.

The polishing method of the polishing device for the inner wall surface of the groove in the hole, which applies any one of the above embodiments, comprises the following steps:

step A: placing the work piece 9 on a work holder 10, adjusting the holder to define the necessary degrees of freedom, and clamping;

and B: the control unit 13 controls the upper lifting platform 8 to work, so that the upper piston 1 is positioned at the upper end position of the inner groove of the hole, and the control unit 13 controls the lower lifting platform 12 to move, so that the lower outer piston 3 is positioned at the lower end position of the inner groove of the hole;

and C: the control unit 13 controls the driving motor 14 to make the lower inner piston 4 and the lower wall of the lower outer piston 3 tightly attached, namely the lower inner piston 4 is positioned at the minimum stroke, the small hole of the upper piston 1 is opened, and water is injected into the inner groove until the water just submerges the lower end surface of the upper piston 1;

step D: the control unit 13 controls the driving motor 14 to make the lower inner piston 4 move to the maximum stroke, the liquid in the first cavity flows into the second cavity through the one-way valve 303 due to gravity, meanwhile, the volume of the closed space in the first cavity is increased, the pressure in the closed space is continuously reduced until the internal pressure of the liquid is smaller than the saturated vapor pressure, and gas begins to be separated out;

step E: the control unit 13 controls the driving motor 14, the lower inner piston 4 displaces from the maximum stroke position to the minimum stroke position, the lower inner piston 4 pushes liquid to move to generate cavitation jet flow to be shot into the wall surface of the inner groove of the processing workpiece 9, meanwhile, the pressure in the groove of the processing workpiece 9 continuously rises, and the separated gas is compressed to realize volume alternation;

step F: and D, repeating the step D and the step E until the processing is finished.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., 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. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.