阅读说明：本技术 活套气动控制系统及可自动调节张力的活套控制方法 (Loop pneumatic control system and loop control method capable of automatically adjusting tension ) 是由 杨家满 廖子东 容臻芹 蔡国强 戴坚辉 王宝 李霖 吴建城 丘相林 林勋荣 于 2021-07-29 设计创作，主要内容包括：本发明涉及活套气动控制系统,与起套辊连接,包括气缸及与气缸连接的三个控制回路,分别是第一控制回路、第二控制回路和第三控制回路；第一控制回路与气缸的有杆腔连通,第一控制回路上设有第一二位三通换向阀,第二控制回路与第三控制回路均通过切换阀与无杆腔管路连通,无杆腔管路与气缸的无杆腔连通,无杆腔管路上设置有单向节流阀,第二控制回路上设置有第二二位三通换向阀,第三控制回路上依次设置有第一减压阀、蓄能器和第三二位三通换向阀；本发明也公开了可自动调节张力的活套控制方法,使用所述活套气动控制系统,与级联调速系统配合,构成闭环活套控制系统。本发明扩展了系统的管理与控制能力,降低了操作人员的劳动强度。(The invention relates to a loop pneumatic control system, which is connected with a loop-rising roller, and comprises an air cylinder and three control loops connected with the air cylinder, namely a first control loop, a second control loop and a third control loop; the first control loop is communicated with a rod cavity of the cylinder, a first two-position three-way reversing valve is arranged on the first control loop, the second control loop and the third control loop are communicated with a rodless cavity pipeline through a switching valve, the rodless cavity pipeline is communicated with a rodless cavity of the cylinder, a one-way throttle valve is arranged on the rodless cavity pipeline, a second two-position three-way reversing valve is arranged on the second control loop, and a first pressure reducing valve, an energy accumulator and a third two-position three-way reversing valve are sequentially arranged on the third control loop; the invention also discloses a loop control method capable of automatically adjusting the tension, and a closed loop control system is formed by using the loop pneumatic control system and matching with the cascade speed regulation system. The invention expands the management and control capability of the system and reduces the labor intensity of operators.)

1. The loop pneumatic control system is characterized by being connected with a loop lifting roller (16) and comprising an air cylinder (11) and three control loops connected with the air cylinder (11), wherein the three control loops are connected with an air source pipeline and respectively comprise a first control loop, a second control loop and a third control loop;

the hydraulic cylinder is characterized in that the first control loop is communicated with a rod cavity of the cylinder (11), a first two-position three-way reversing valve (6) is arranged on the first control loop, the second control loop and the third control loop are communicated with a rodless cavity pipeline through a switching valve (9), the rodless cavity pipeline is communicated with the rodless cavity of the cylinder (11), a one-way throttle valve (10) is arranged on the rodless cavity pipeline, a second two-position three-way reversing valve (7) is arranged on the second control loop, and a first reducing valve (5), an energy accumulator (12) and a third two-position three-way reversing valve (8) are sequentially arranged on the third control loop.

2. The looper pneumatic control system according to claim 1, wherein a first shut-off valve (1) and a second pressure reducing valve (3) are provided on the air supply line.

3. The looper pneumatic control system according to claim 2, wherein a filter (2) is further provided on the air supply line, the filter (2) being located between the first shut-off valve (1) and the second pressure reducing valve (3).

4. A looper pneumatic control system according to claim 3 wherein an oil mist device (4) is further provided on the air supply line, the oil mist device (4) being located between the second pressure reducing valve (3) and the three control circuits.

5. The looper pneumatic control system according to claim 4, wherein a second shut-off valve is further provided on the third control circuit, the second shut-off valve being located between the first pressure reducing valve (5) and the accumulator (12).

6. A loop control method capable of automatically adjusting tension by using the loop pneumatic control system as claimed in claim 5, wherein the loop pneumatic control system is matched with a cascade speed regulation system to form a closed loop control system;

when the head of a rolled piece (15) enters a loop downstream rolling mill (14) from an upstream rolling mill (13) and bites, a first two-position three-way reversing valve (6) is started to disconnect a first control loop, a second two-position three-way reversing valve (7) is started to communicate a second control loop, a third two-position three-way reversing valve (8) is started to communicate a third control loop, a switching valve (9) is started to communicate the second control loop with a rodless cavity pipeline, a gas source enters a rodless cavity of a cylinder (11) through the second control loop, gas in a rod cavity of the cylinder (11) is discharged through the first two-position three-way reversing valve (6) of the first control loop, a piston rod of the cylinder (11) extends out to jack a sleeve roller (16), and the sleeve roller (16) lifts the rolled piece (15) to form an arc line;

when the initial looping amount of the loop is finished, the loop starting roller (16) reaches a looping amount limit position, the second two-position three-way reversing valve (7) is disconnected, the switching valve (9) is controlled to enable the third control loop to be communicated with the rodless cavity pipeline, the air source enters the third control loop from the beginning to provide a stable constant pressure air source for the air cylinder (11), and when the loop scanner detects that the loop height is different from a set value, the loop control system corrects the speed of the rack to maintain the looping amount through the cascade speed regulation system in proportion according to the deviation detected by the loop scanner;

when the tail end of a rolled piece (15) approaches to the previous frame of the loop, the loop control system sends a loop descending instruction to gradually reduce the loop amount, the second control loop and the third control loop are disconnected, the first two-position three-way reversing valve (6) is communicated, an air source enters a rod cavity of the air cylinder (11) through the first control loop, air in the rod-free cavity of the air rod is discharged through an air valve of the one-way throttle valve (10), and the loop lifting roller (16) descends.

7. The loop control method according to claim 6, characterized in that, throughout the adjustment of the height of the jacking rollers (16), part of the gas source enters the third control circuit, and the gas source at high pressure enters the accumulator (12) through the first pressure reducing valve (5).

8. The loop control method according to claim 7, characterized in that when the loop scanner detects that the loop height exceeds a set value, the loop amount is maintained by proportionally reducing the speed of the upstream frame of the loop by a cascade speed regulating system, and the height of the loop-raising roller (16) is kept constant;

when the loop scanner detects that the height of the loop is lower than a set value, the speed of an upstream frame of the loop is increased in proportion through a cascade speed regulating system to maintain the loop quantity, and the height of the loop lifting roller (16) is kept unchanged.

9. The loop control method as claimed in claim 6, characterized in that the gas in the rodless chamber of the gas rod is slowly exhausted through the gas valve of the one-way throttle valve (10) to reduce the loop dropping speed.

10. The loop control method according to claim 6, characterized in that the gas pressure in the accumulator (12) is adjusted by adjusting the first pressure reducing valve (5) and the second pressure reducing valve (3) to adapt to the loop amount of rolled pieces (15) of different specifications.

Technical Field

The invention relates to the technical field of automatic control of a rod and wire production line, in particular to a loop pneumatic control system and a loop control method capable of automatically adjusting tension.

Background

The loop control is an important component of an automatic loop control system for the hot continuous rolling of the bar and wire rods, the loop control system consists of equipment in two fields of machinery and electricity, and the control process is also the comprehensive reflection of various factors. Frequent adjustment of the loop easily causes instability of various factors, and steel piling of a rolling line or influence on product quality are easily caused.

At present, after the position signal of steel is measured by a scanner of a loop and a certain time is delayed, a loop control system sends an adjusting signal to start the height loop amount of a loop lifting wheel, namely, the loop lifting height of the loop is controlled or the loop amount input according to the height reaches a set value, the loop control system starts closed-loop adjustment, the tension between frames can be stabilized through adjustment for a period of time, and the product size precision can enter a stabilization stage. The loop control mode takes long time, relatively late starting and very late loop adjustment of the loop amount are delayed, so that the tension adjustment between a time period when a rolled piece starts to bite into a rack from a head and the tension adjustment between the racks are out of control easily, the size of the rolled piece is fluctuated, particularly, the fault of steel piling and pulling is easily generated under the condition of roller groove abrasion or during the adjustment of a roller gap after the roller is replaced, the problem of the size of the rolled piece which is dozens of meters is caused, and even the steel piling accident is caused to influence the normal production. The adjustment time of the extensive process is long, so that the dimension precision of a long section of a rolled piece is not good enough, the parameters such as time delay control and the like are required to be manually set, the process requirements are difficult to meet, and certain difficulties exist in daily maintenance and fault treatment; therefore, how to improve the control precision of the loop and optimizing the performance of the loop control system are the key points for solving the problems.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a loop pneumatic control system and a loop control method capable of automatically adjusting tension, so that full-automatic setting and control of a loop are realized, and the management and control capability of the system is expanded, thereby simplifying the adjustment process and reducing the labor intensity of operators.

The technical purpose of the invention is realized by the following technical scheme:

the loop pneumatic control system is connected with the loop lifting roller and comprises an air cylinder and three control loops connected with the air cylinder, wherein the three control loops are connected with an air source pipeline and respectively comprise a first control loop, a second control loop and a third control loop;

the hydraulic cylinder control system is characterized in that the first control loop is communicated with a rod cavity of the cylinder, a first two-position three-way reversing valve is arranged on the first control loop, the second control loop and the third control loop are communicated with a rodless cavity pipeline through a switching valve, the rodless cavity pipeline is communicated with a rodless cavity of the cylinder, a one-way throttle valve is arranged on the rodless cavity pipeline, a second two-position three-way reversing valve is arranged on the second control loop, and a first reducing valve, an energy accumulator and a third two-position three-way reversing valve are sequentially arranged on the third control loop.

In one embodiment, a first stop valve and a second pressure reducing valve are arranged on the air source pipeline.

In one embodiment, a filter is further arranged on the air source pipeline, and the filter is located between the first stop valve and the second pressure reducing valve.

In one embodiment, an oil atomizer is further arranged on the air source pipeline, and the oil atomizer is located between the second pressure reducing valve and the three control circuits.

In one embodiment, a second stop valve is further provided on the third control circuit, the second stop valve being located between the first pressure reducing valve and the accumulator.

The loop control method capable of automatically adjusting tension uses the loop pneumatic control system to be matched with a cascade speed regulation system to form a closed loop control system, and comprises the following specific steps:

when the head of a rolled piece enters a lower-stream rolling mill (14) of the loop from an upper-stream rolling mill to bite, a first two-position three-way reversing valve is started to disconnect a first control loop, a second two-position three-way reversing valve is started to communicate a second control loop, a third two-position three-way reversing valve is started to communicate a third control loop, a switching valve is started to communicate the second control loop with a rodless cavity pipeline, a gas source enters a rodless cavity of a cylinder through the second control loop, gas in the rod cavity of the cylinder is discharged through the first two-position three-way reversing valve of the first control loop, a piston rod of the cylinder extends out to jack a sleeve roller, and the sleeve roller lifts the rolled piece to form an arc line;

when the loop scanner detects that the loop height is different from a set value, the loop control system corrects the speed of the rack in proportion to maintain the loop quantity through the cascade speed regulation system according to the deviation detected by the loop scanner;

when the tail end of the rolled piece approaches to the previous frame of the loop, the loop control system sends a loop descending instruction to gradually reduce the loop amount, the second control loop and the third control loop are disconnected, the first two-position three-way reversing valve is communicated, the air source enters the rod cavity of the air cylinder through the first control loop, the air in the rod-free cavity of the air rod is discharged through the air valve of the one-way throttle valve, and the loop lifting roller descends.

In one embodiment, part of the air supply enters the third control circuit and the high-pressure air supply enters the accumulator through the first pressure reducing valve during the whole process of adjusting the height of the jacking rollers.

In one embodiment, when the loop scanner detects that the loop height exceeds a set value, the speed of an upstream frame of the loop is proportionally reduced through a cascade speed regulating system to maintain the loop amount, and the height of the loop starting roller is kept unchanged;

when the loop scanner detects that the height of the loop is lower than a set value, the speed of an upstream frame of the loop is increased in proportion through the cascade speed regulating system to maintain the loop quantity, and the height of the loop starting roller is kept unchanged.

In one embodiment, air in the rodless cavity of the air rod is slowly exhausted through the air valve of the one-way throttle valve, and the sleeve descending speed is reduced.

In one embodiment, the air pressure in the accumulator is adjusted by adjusting the first pressure reducing valve and the second pressure reducing valve to adapt to the sleeve amount of different specifications of rolled pieces.

In conclusion, the invention has the following beneficial effects:

the loop pneumatic control system realizes the stable adjustment of the loop-rising roller, and the loop control method which uses the loop pneumatic control system and can automatically adjust the tension is matched with the cascade speed regulation system to form a closed loop control system, so that not only is the head of a rolled piece completely brought into loop high closed loop adjustment control, and the dimensional precision of the head is ensured, but also the whole control process does not need an operator to input any loop data on the system, the full automatic setting and control of the loop is realized, and the management and control capability of the system is expanded, thereby simplifying the adjustment process and reducing the labor intensity of the operator.

Drawings

FIG. 1 is a schematic diagram of a loop pneumatic control system of the present invention;

fig. 2 is a schematic representation of different loop amounts.

In the figure: 1-a first stop valve, 2-a filter, 3-a second pressure reducing valve, 4-an oil atomizer, 5-a first pressure reducing valve, 6-a first two-position three-way reversing valve, 7-a second two-position three-way reversing valve, 8-a third two-position three-way reversing valve, 9-a switching valve, 10-a one-way throttle valve, 11-a cylinder, 12-an accumulator, 13-an upstream rolling mill, 14-a downstream rolling mill, 15-a rolled piece and 16-a sleeve lifting roller.

Detailed Description

The invention is described in detail below with reference to the figures and examples.

It should be noted that all the directional terms such as "upper" and "lower" referred to herein are used with respect to the view of the drawings, and are only for convenience of description, and should not be construed as limiting the technical solution.

For long-material rolling lines such as rod and wire materials, the rise and fall control of the loop directly influences whether normal production can be carried out, steel can be slipped out to cause an accident if the loop is too early and a rolled piece 15 is not bitten into a downstream rolling mill 14, steel piling or steel drawing can be generally caused to influence the quality of a finished product head if the loop is too late, steel piling or steel drawing can be generally caused to influence the quality of a finished product tail if the loop is too early, the phenomenon of strip steel drifting can be generated if the loop is too late, and the rolling rhythm and the quality of a finished product can be influenced seriously. The existing loop is controlled by a PLC (programmable logic controller), a steel biting current or hot metal detector of a motor is used as a detection signal in principle, and the loop is started when two adjacent racks of the loop simultaneously contain steel; when the loop is adjacent to the upstream frame, the loop falls down instantly when no steel exists. However, since the moving speed of the rolled piece 15 is high, a certain time is required for loop starting, and the rolled piece 15 may reach the next rolling mill when the loop starting is completed, at this time, the upstream rolling mill 13 needs to be accelerated to complete the loop starting process and then decelerated and restored, all the rolling mills in the upstream need to be accelerated and decelerated in a cascade manner, and a plurality of loops need to be overlapped for many times, which is very unfavorable for the stability of a rolling line.

The invention provides a looper pneumatic control system, which is connected with a looper roll 16 as shown in figure 1 and comprises an air cylinder 11 and three control loops connected with the air cylinder 11, wherein the three control loops are all connected with an air source pipeline and respectively comprise a first control loop, a second control loop and a third control loop, the first control loop is a v1 line in figure 1, the second control loop is a v2 line in figure 1, and the third control loop is a v3 line in figure 1;

the hydraulic cylinder control system is characterized in that the first control loop is communicated with a rod cavity of the cylinder 11, a first two-position three-way reversing valve 6 is arranged on the first control loop, the second control loop and the third control loop are communicated with a rodless cavity pipeline through a switching valve 9, the rodless cavity pipeline is communicated with the rodless cavity of the cylinder 11, a one-way throttle valve 10 is arranged on the rodless cavity pipeline, a second two-position three-way reversing valve 7 is arranged on the second control loop, and a first reducing valve 5, an energy accumulator 12 and a third two-position three-way reversing valve 8 are sequentially arranged on the third control loop.

Wherein, a first stop valve 1, a filter 2 and a second reducing valve 3 are sequentially arranged on the air source pipeline.

And an oil atomizer 4 is further arranged on the air source pipeline, and the oil atomizer 4 is positioned between the second pressure reducing valve 3 and the three control loops.

Wherein, a second stop valve is also arranged on the third control loop and is positioned between the first reducing valve 5 and the accumulator 12.

It can be seen that in the loop pneumatic control system, the energy accumulator 12 is always communicated with the air source, so as to maintain that the rolled pieces 15 of the same specification store a certain amount of loop quantity under the condition of no tension, and the loop quantity of the rolled pieces 15 of different specifications can be kept to be in a tension-free state by adjusting the pressure of the first pressure reducing valve 5 and the pressure of the second pressure reducing valve 3.

The invention also provides a loop control method capable of automatically adjusting tension, which uses the loop pneumatic control system to be matched with a cascade speed regulation system to form a closed loop control system, and comprises the following specific steps:

when the head of a rolled piece 15 enters a loop downstream rolling mill 14 from an upstream rolling mill 13 and bites, a first two-position three-way reversing valve 6 is started to disconnect a first control loop, a second two-position three-way reversing valve 7 is started to communicate a second control loop, a third two-position three-way reversing valve 8 is started to communicate a third control loop, a switching valve 9 is started to communicate the second control loop with a rodless cavity pipeline, a gas source enters a rodless cavity of a cylinder 11 through the second control loop, gas in the rod cavity of the cylinder 11 is discharged through the first two-position three-way reversing valve 6 of the first control loop, a piston rod of the cylinder 11 extends out to jack a sleeve lifting roller 16, and the sleeve lifting roller 16 lifts the rolled piece 15 to form an arc line;

when the initial looping amount of the loop is finished, the loop starting roller 16 reaches a looping amount limit position, the second two-position three-way reversing valve 7 is disconnected, the switching valve 9 is controlled to enable the third control loop to be communicated with the rodless cavity pipeline, the air source enters the third control loop from the beginning, a stable constant-pressure air source is provided for the air cylinder 11, and when the loop scanner detects that the loop height is different from a set value, the loop control system corrects the speed of the rack to maintain the looping amount through the cascade speed regulation system according to the deviation detected by the loop scanner;

when the tail end of a rolled piece 15 approaches to the previous frame of the loop, the loop control system sends a loop descending instruction to gradually reduce the loop amount, the second control loop and the third control loop are disconnected, the first two-position three-way reversing valve 6 is communicated, an air source enters a rod cavity of the air cylinder 11 through the first control loop, air in a rodless cavity of the air rod is discharged through an air valve of the one-way throttle valve 10, and the loop lifting roller 16 descends.

Further, the air pressure in the accumulator 12 is adjusted by adjusting the first pressure reducing valve 5 and the second pressure reducing valve 3 so as to adapt to the sleeve amount of rolled pieces 15 with different specifications.

Further, part of the gas source enters the third control circuit, and the high-pressure gas source enters the accumulator 12 through the first pressure reducing valve 5.

Further, when the loop scanner detects that the height of the loop exceeds a set value, the speed of an upstream rack of the loop is reduced in proportion through a cascade speed regulating system to maintain the loop amount; when the loop scanner detects that the loop height is lower than a set value, the speed of an upstream rack of the loop is increased in proportion through the cascade speed regulating system to maintain the loop quantity.

Further, the air in the rodless cavity of the air rod is slowly exhausted through the air valve of the one-way throttle valve 10, and the sleeve descending speed is reduced.

The following specific examples illustrate the sleeve opening and closing process of the present invention:

the curved rolled piece 15 between the frames is guided by a loop lifting roller 16 through a loop control system, so that the rolled piece 15 forms a loop on a loop table, and the loop scanner is used for measuring the loop amount of the loop to indirectly measure the length of the loop, namely the length of the loop is indirectly measured according to the height of the loop. The adjustment range of the loop and the storage amount of the loop are limited, and when the speed of adjacent frames is unreasonably matched or the deviation of the loop starting amount is too large due to other reasons, the loop control system is not in time to adjust or cannot adjust, so that the fault phenomenon of steel piling or breakage of the rolled piece 15 can be caused. The loop scanner compares the actual value of the measured loop quantity with a set value according to the principle that the measured loop quantity is in a linear relation with the length of the loop, and then guides and automatically reversely adjusts all upstream rolling mills to the speed of the rolling mill where the tail of the rolled piece 15 is located through a cascade speed regulating system according to the deviation of the actual value of the loop quantity and the set value. In the whole loop control process, the loop amount of the loop is adjusted by correcting the speed of the upstream rolling mill 13 through a cascade speed regulating system, the loop amount of the loop is in a positive correlation with the difference between the speed of a rolled piece 15 at an inlet of the loop and the speed of the rolled piece 15 at an outlet, as shown in fig. 2, when the inlet speed is greater than the outlet speed, the loop amount of the loop is gradually increased, as shown by a curve a in fig. 2; when the inlet speed is equal to the outlet speed, the amount of the loop remains constant, as shown by curve b in fig. 2; when the inlet speed is lower than the outlet speed, the amount of loops is gradually reduced, as shown by curve c in fig. 2.

When the head of a rolled piece 15 enters a downstream rolling mill 14 of the loop from an upstream rolling mill 13 and bites, a loop control system controls a first two-position three-way reversing valve 6 to be started to disconnect a first control loop, controls a second two-position three-way reversing valve 7 to be started to connect a second control loop, controls a third two-position three-way reversing valve 8 to be started to connect a third control loop, controls a switching valve 9 to be communicated with a rodless cavity pipeline, controls a gas source to enter the second control loop and enter a rodless cavity of a cylinder 11 through the second two-position three-way reversing valve 7 and a one-way throttle valve 10, simultaneously discharges gas in a rod cavity of the cylinder 11 through the first two-position three-way reversing valve 6 of the first control loop, extends out a piston rod of the cylinder 11 to jack a jacking sleeve roller 16, the jacking sleeve roller 16 lifts the rolled piece 15 to form an arc line, and high-pressure gas directly enters the rodless cavity of the cylinder 11, the sleeve can be quickly pulled up;

meanwhile, part of the gas source enters a third control loop and enters an energy accumulator 12 through a first pressure reducing valve 5, and the third control loop is not communicated with a rodless cavity pipeline, so that the gas pressure in the energy accumulator 12 is small and relatively stable in the process of lifting the sleeve lifting roller 16, and the method is favorable for preventing the sleeve amount of the rolled piece 15 from being suddenly changed in the time of preventing the initial sleeve lifting delay, for example, in the sleeve lifting process, the acting force of the rolled piece 15 on the sleeve lifting roller 16 may be changed, and the energy accumulator 12 absorbs impact to ensure that the sleeve lifting roller 16 quickly and stably lifts the rolled piece 15;

after the sleeve lifting roller 16 reaches the sleeve amount limit position when the initial sleeve amount of the loop is completed, as shown by a curve b in the attached drawing 2, the loop control system controls the second two-position three-way reversing valve 7 to be disconnected and controls the switching valve 9 to enable the third control loop to be communicated with the rodless cavity pipeline, the air source enters the third control loop, a stable constant-pressure air source is provided for the air cylinder 11 through the first pressure reducing valve 5, the energy accumulator 12, the third two-position three-way reversing valve 8 and the switching valve 9, and the high-pressure air source is depressurized through the first pressure reducing valve 5 and enters the energy accumulator 12 to provide supporting force for the sleeve lifting roller 16. When the loop scanner detects that the loop height exceeds or is lower than a set value, the loop control system corrects the speed of the rack in proportion through the cascade speed regulation system according to the deviation detected by the loop scanner to maintain the loop amount, in the adjusting process, the pressure of an air source in a rodless cavity of the air cylinder 11 is not influenced by the air pressure of the first control loop, namely, the energy accumulator 12 provides constant supporting force for the loop starting roller 16, the set value of the loop amount is ensured to be unchanged, the speed second flow balance between the racks is realized, and the loop starting roller 16 cannot shake due to insufficient supporting force of the air cylinder 11, so that the possibility of stacking steel for a rolled piece 15 caused by the air pressure problem is greatly reduced;

when the tail end of a rolled piece 15 approaches to a previous frame of the loop, a loop control system sends a loop lowering instruction to gradually reduce the loop amount, a second two-position three-way reversing valve 7 on a second control loop and a third two-position three-way reversing valve 8 on a third control loop are disconnected, a first two-position three-way reversing valve 6 of a first control loop is communicated, an air source enters a rod cavity of an air cylinder 11 through the first control loop, air in the rod cavity of the air rod is discharged through an air valve of a one-way throttle valve 10, and resistance is arranged at the air valve of the one-way throttle valve 10, so that a loop lifting roller 16 is lowered at a slower speed, and therefore, the loop lifting and loop dropping process is completed.

In the loop pneumatic control system, the first control loop, the second control loop and the third control loop are all communicated with the energy accumulator 12, and the energy accumulator 12 can play a role when an air source enters any one control loop, so that the smooth adjustment of the loop starting roller 16 is realized.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.