A method for eliminating liquid surface turbulence in a large-section slab crystallizer

Abstract

The present application relates to a method for eliminating the liquid surface disorder of molten steel in a large-section slab crystallizer, and belongs to the technical field of continuous casting methods in the metallurgical industry. The technical scheme of the present application is: optimizing the structure of the submerged nozzle of the continuous casting crystallizer to inhibit the dynamic instability of the molten steel flow field; increasing the submerged depth of the nozzle; adjusting the PID parameters of the liquid level control system to improve the stability and applicability of the liquid level control system; opening the stopper shaking function to change the flow state of the molten steel in the nozzle and inhibit the liquid surface disorder of the crystallizer. The beneficial effects of the present application are: the periodic disorder of the liquid surface of the crystallizer can be effectively eliminated, the liquid surface fluctuation of the crystallizer can be controlled, the slag entrapment defects caused by the liquid surface fluctuation are reduced, and the product quality of the cast slab is improved; at the same time, the production accidents such as stop pouring and leakage caused by the liquid surface disorder can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for eliminating the liquid surface disorder of molten steel in a large-section slab crystallizer, belonging to the technical field of continuous casting methods in the metallurgical industry. BACKGROUND

[0002] The control of non-metallic inclusions in steel is very high for automobile sheet steel production, because improper molten steel flow pattern in the crystallizer will lead to instability of the liquid surface in the crystallizer, slag entrapment, and in severe cases, affect the quality of the cast slab, leading to defects in the cast slab.

[0003] With the efficient production of steel enterprises, the continuous casting speed is gradually increased, and some steel plants have broken through 2.0 m / min, however, the increase of the casting speed has a significant impact on the flow of molten steel in the crystallizer, especially it will increase the surface flow rate of molten steel in the crystallizer, when the surface flow rate exceeds 0.5 m / s, it will easily cause liquid surface fluctuation, resulting in quality defects of the cast slab.

[0004] The traditional automobile sheet steel metallurgical process emphasizes the formation of balanced upper and lower backflows, and the main role of the upper backflow is: (1) supplying heat to the molten steel above the crystallizer to facilitate the melting of the protective slag, and reducing the unevenness of the primary shell; (2) promoting non-metallic inclusions to move upward with the upper backflow, collide with each other, and aggregate into larger size inclusions, float out of the molten steel and be removed. Therefore, automobile sheet steel production enterprises mostly use a smaller submerged entry nozzle outlet angle of 15° and a shallower nozzle immersion depth of 110-150 mm.

[0005] However, through the study of the flow characteristics of molten steel in the continuous casting crystallizer, it is found that the smaller outlet angle of the submerged entry nozzle, in addition to easily causing liquid surface fluctuation and larger surface flow rate, also has the problem that the turbulent energy of the molten steel in the area below the submerged entry nozzle is low, the lower backflow on both sides periodically converges to the center, making the turbulent energy of the area below the submerged entry nozzle stronger, and then dissipating to the outer area, resulting in periodic disorder of the molten steel flow field in the crystallizer, liquid surface horizontal swing, and intensified fluctuation, increasing the possibility of protective slag being entrapped in the molten steel and being captured by the solidified shell as large inclusions in the steel, especially when the cross-section of the cast slab is greater than 1800 mm, the above problems are more serious. Therefore, how to effectively control the liquid surface fluctuation in the slab continuous casting crystallizer by optimizing the existing continuous casting technology and control method is a technical problem that needs to be solved by the technical personnel in the field.

[0006] Currently, scholars and technical personnel at home and abroad lack systematic research on the periodic disorder of the liquid surface caused by the unreasonable structure of the nozzle side hole in the conventional slab lower crystallizer, and no scholars and technical personnel have studied the method of controlling different types of liquid surface fluctuation in the crystallizer by comprehensively adjusting the PID control system and the mode of the stopper rotation and shaking. SUMMARY

[0007] The application aims to provide a method for eliminating the liquid surface disorder of molten steel in a large-section slab crystallizer, which can effectively eliminate the periodic disorder of the liquid surface in the crystallizer, control the fluctuation of the liquid surface in the crystallizer, reduce the slag entrapment defects caused by the fluctuation of the liquid surface, and improve the product quality of the cast slab, and can effectively reduce the production accidents such as stop pouring and leakage caused by the disorder of the liquid surface, and effectively solve the above problems in the background art.

[0008] The technical scheme of the application is a method for eliminating the liquid surface disorder of molten steel in a large-section slab crystallizer, comprising the following steps:

[0009] (1) optimizing the structure of the submerged nozzle of the continuous casting crystallizer to suppress the dynamic instability of the molten steel flow field;

[0010] (2) increasing the submerged depth of the nozzle;

[0011] (3) adjusting the PID parameters of the liquid level control system to improve the stability and applicability of the liquid level control system;

[0012] (4) turning on the stopper shaking function to change the flow state of the molten steel in the nozzle and suppress the disorder of the liquid surface in the crystallizer.

[0013] In the step (1), the inclination angle of the nozzle is increased from 15 degrees to 25 degrees, and the side hole shape of the submerged nozzle is made into an oval shape.

[0014] In the step (2), the submerged depth of the submerged nozzle, i.e. the distance from the upper edge of the side hole to the liquid surface of the crystallizer, reaches 150 mm.

[0015] In the step (3), when the liquid surface of the crystallizer appears periodic fluctuation, the proportional gain part K P of the adjustment control system is increased within the allowable range; when the fluctuation center value of the liquid surface of the crystallizer deviates from the standard value, the integral gain part K I is reduced within the allowable range; and when the vibration noise of the liquid surface fluctuation of the crystallizer is high, the differential gain part K D is reduced within the allowable range.

[0016] The allowable range for adjusting the proportional gain part K P is 0.6-2.0, the allowable range for adjusting the integral gain part K I is 0.08-0.3, and the allowable range for adjusting the differential gain part K D is 0.05-0.2.

[0017] The PID value of the liquid level control system is adjusted, if the liquid surface of the crystallizer is good and the fluctuation value is less than 5 mm, KP =0.8, K D =0.2, K I =0.2; if the crystallizer liquid surface is slightly poor, the 20% liquid surface fluctuation value is 5-10mm, then the PID parameter needs to be adjusted to K P =1.2, K D =0.1, K I =0.15; if the crystallizer liquid surface fluctuation value is larger, the 10% liquid surface fluctuation value exceeds 10mm, then the PID parameter is adjusted to K P =1.5, K D =0.06, K I =0.1; the above case, when the liquid surface fluctuation tends to be stable, the PID parameter is adjusted to the original value.

[0018] In the step (4), ① after the first furnace casting of the pouring is finished, the timing is started after the molten steel liquid surface in the crystallizer is stable, and the stopper rotation shaking function is started after 10 minutes; ② the stopper shaking of the first four furnaces of the pouring adopts mode one, the rotation frequency is 2Hz, the up and down shaking frequency is 5Hz, and the shaking amplitude is 1mm; ③ after the four furnaces of the pouring, different stopper shaking modes are adopted according to the liquid surface fluctuation of the crystallizer: a. if the liquid surface fluctuation condition is good, the stopper shaking mode one is kept; b. if the liquid surface fluctuation curve appears more jump points, the stopper shaking is switched to mode two, the rotation frequency is 1Hz, the up and down shaking frequency is 2Hz, and the shaking amplitude is 1.5mm, if the jump point cannot be improved, the stopper shaking is closed; c. if the liquid surface fluctuation curve appears irregular large fluctuation, the stopper shaking is switched to mode three, the rotation frequency is 5Hz, the up and down shaking frequency is 10Hz, and the shaking amplitude is 1.0mm.

[0019] The beneficial effects of the present application are: through the methods of changing the water gap structure, the water gap insertion depth, adjusting the PID parameter of the liquid surface control system and controlling the stopper shaking function, the periodic disorder of the crystallizer liquid surface can be effectively eliminated, the crystallizer liquid surface fluctuation is controlled, the slag entrapment defects caused by the liquid surface fluctuation are reduced, and the product quality of the casting blank is improved; meanwhile, the production accidents such as pouring stop and leakage caused by the liquid surface disorder can be effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view of a downward 15-degree rectangular water gap of the background art of the present application;

[0021] Figure 2 is a schematic view of a downward 25-degree elliptical water gap of the present application;

[0022] Figure 3 is a crystallizer liquid surface fluctuation qualified rate graph under different water gap angles of the present application;

[0023] Figure 4 is a mold level fluctuation graph of the present application with a water nozzle immersion depth of 110 mm;

[0024] Figure 5 is a mold level fluctuation graph of the present application with a water nozzle immersion depth of 160 mm;

[0025] Figure 6 is a mold level fluctuation comparison graph of the present application before and after PID system parameter adjustment;

[0026] Figure 7 is a mold level fluctuation graph of the present application before opening the stopper shaking;

[0027] Figure 8 is a mold level fluctuation graph of the present application after opening the stopper shaking. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiment of the application clearer, the technical scheme of the embodiment of the application will be described clearly and completely below in combination with the drawings in the embodiment. Obviously, the described embodiment is only a part of the embodiments of the application, not all the embodiments of the application. Based on the embodiment of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0029] A method for eliminating liquid steel liquid surface disorder in a large-section slab crystallizer, comprising the following steps:

[0030] (1) optimizing the structure of the submerged nozzle of the continuous casting crystallizer, and suppressing the dynamic instability of the steel flow field;

[0031] (2) increasing the immersion depth of the nozzle;

[0032] (3) adjusting the PID parameters of the liquid level control system, and improving the stability and applicability of the liquid level control system;

[0033] (4) opening the stopper shaking function, changing the flow state of the steel liquid in the nozzle, and suppressing the disorder of the crystallizer liquid surface.

[0034] In the step (1), the inclination angle of the nozzle is increased from 15 degrees to 25 degrees, and the side hole shape of the submerged nozzle is made into an oval shape.

[0035] In the step (2), the submerged nozzle insertion depth, i.e. the distance from the upper edge of the side hole to the mold liquid surface, reaches 150 mm.

[0036] In the step (3), when the periodic fluctuation of the crystallizer liquid surface occurs, the proportional gain part K of the adjustment control system is increased within the allowable range. P; ② When the center value of the fluctuation of the liquid surface of the crystallizer deviates from the standard value, the integral gain part K is reduced within the allowable range I ; ③ When the vibration noise of the fluctuation of the liquid surface of the crystallizer is high, the differential gain part K is reduced within the allowable range D .

[0037] The proportional gain part K P The allowable range of adjustment is 0.6-2.0, the integral gain part K I The allowable range of adjustment is 0.08-0.3, the differential gain part K D The allowable range of adjustment is 0.05-0.2.

[0038] The PID value of the liquid level control system is adjusted, if the liquid level of the crystallizer is good, the fluctuation value is less than 5 mm, then K P =0.8, K D =0.2, K I =0.2; if the liquid level of the crystallizer is slightly poor, the fluctuation value of 20% of the liquid level is 5-10 mm, then the PID parameters need to be adjusted to K P =1.2, K D =0.1, K I =0.15; if the fluctuation value of the liquid level of the crystallizer is large, the fluctuation value of 10% of the liquid level exceeds 10 mm, then the PID parameters are adjusted to K P =1.5, K D =0.06, K I =0.1; the above cases are adjusted to the original value when the liquid level fluctuation tends to be stable.

[0039] In the step (4), ① after the first furnace casting of the pouring is finished, the timing is started after the molten steel liquid level in the crystallizer is stable, and the stopper rotation shaking function is started after 10 min; ② the stopper shaking of the first four furnaces of the pouring adopts mode one, the rotation frequency is 2 Hz, the up and down shaking frequency is 5 Hz, and the shaking amplitude is 1 mm; ③ after the four furnaces of the pouring, different stopper shaking modes are adopted according to the liquid level fluctuation of the crystallizer: a. if the liquid level fluctuation condition is good, the stopper shaking mode one is maintained; b. if the liquid level fluctuation curve appears more jump points, the stopper shaking is switched to mode two, the rotation frequency is 1 Hz, the up and down shaking frequency is 2 Hz, and the shaking amplitude is 1.5 mm, if the jump point cannot be improved, the stopper shaking is closed; c. if the liquid level fluctuation curve appears irregular large fluctuation, the stopper shaking is switched to mode three, the rotation frequency is 5 Hz, the up and down shaking frequency is 10 Hz, and the shaking amplitude is 1.0 mm.

[0040] In practical application, the stable liquid level fluctuation and internal flow field can be effectively obtained by adopting the present application, and the technical scheme mainly comprises the following detailed control process:

[0041] 1. Optimizing the structure of the submerged nozzle of continuous casting mold, and inhibiting the dynamic instability of the flow field of liquid steel. ① The inclination angle of the nozzle is increased from 15 degrees to 25 degrees. Increasing the inclination angle of the submerged nozzle can effectively weaken the kinetic energy of the upper backflow area and strengthen the inward convergence of the lower backflow area. In addition to the significant reduction of liquid surface fluctuation and surface flow rate, the low and uneven condition of the turbulent kinetic energy of the liquid steel in the area below the submerged nozzle is significantly improved, thereby eliminating the periodic convergence of the lower backflow on both sides to the center when the nozzle angle is small, making the turbulent kinetic energy in the area below the nozzle stronger, and then dissipating to the outer area, leading to the periodic disorder of the flow field and the intensification of the liquid surface fluctuation. ② The shape of the side hole of the submerged nozzle is optimized to be elliptical, which can effectively reduce the negative pressure area of the side hole of the nozzle by 5%-10%, and inhibit the aggregation of inclusions in the side hole of the nozzle, so as to ensure the symmetry of the flow field in the mold as much as possible, inhibit the formation of flow deviation, and ensure the reasonable flow pattern in the mold.

[0042] 2. Increasing the immersion depth of the nozzle. The immersion depth of the submerged nozzle (the distance from the upper edge of the side hole to the liquid level of the mold) reaches 150 mm. Increasing the immersion depth of the submerged nozzle can reduce the activity of the upper backflow area of the mold, and control the surface flow rate of the liquid steel in the mold at about 0.2 m / s, which can ensure reasonable consumption of the protective slag and good flow pattern and free surface characteristics in the mold.

[0043] 3. Improving the stability and applicability of the liquid level control system. The basic principle of the liquid level control system of the slab continuous casting mold is to control the flow rate of the liquid steel by controlling the position of the stopper, and then to keep the liquid level stable. Therefore, the corresponding parameters of the control system can be adjusted according to the fluctuation: ① When the liquid level of the mold appears periodic fluctuation, the proportional gain part (K P value) of the adjustment control system can be increased within the allowed range (0.6-2.0), which can improve the response speed of the control system and inhibit the periodic liquid level fluctuation; ② When the fluctuation center value of the liquid level of the mold deviates from the standard value, the integral gain part (K I value) can be appropriately reduced within the allowed range (0.08-0.3), thereby eliminating the deviation between the center value and the standard value; ③ When the vibration noise of the liquid level fluctuation of the mold is high, the differential gain part (K D value) can be appropriately reduced within the allowed range (0.05-0.2), which can improve the dynamic characteristics of the control system and increase the anti-interference ability of the control system.

[0044] According to the actual production and different degrees of liquid level fluctuation, the following three control modes are provided for reference. The parameter values can also be adjusted by the operation rules of the PID control parameters described above and the actual situation on site.

[0045]

[0046] 4. Activate the stopper rod shaking function to alter the flow state of the molten steel within the nozzle and suppress surface disturbance in the crystallizer. The activation steps for the stopper rod shaking function mainly include: ① After the first heat of casting is completed, start timing 10 minutes after the molten steel surface in the crystallizer stabilizes, and then activate the stopper rod rotation shaking function. ② For the first four heats, use mode one for stopper rod shaking (rotation frequency of 2 Hz, up-and-down shaking frequency of 5 Hz, shaking amplitude of 1 mm). ③ After four heats, use different stopper rod shaking modes depending on the surface fluctuation in the crystallizer: a. If the surface fluctuation is good, maintain stopper rod shaking mode one. b. If the surface fluctuation curve shows many jumps, switch the stopper rod shaking to mode two (rotation frequency of 1 Hz, up-and-down shaking frequency of 2 Hz, shaking amplitude of 1.5 mm). If the jumps cannot be mitigated, then deactivate the stopper rod shaking. c. If the liquid level fluctuation curve shows large, irregular fluctuations, switch the stopper rod shaking to mode three (rotation frequency of 5Hz, up-and-down shaking frequency of 10Hz, shaking amplitude of 1.0 mm).

[0047]

[0048] Of the four steps, steps 1 and 2 are permanent fixation measures, while steps 3 and 4 require targeted adjustments based on the liquid level in the crystallizer at the production site. Combining these measures, this invention forms a process method that can effectively eliminate molten steel surface disturbances within the slab crystallizer, significantly reducing slab steel defects caused by liquid level fluctuations. It also avoids serious production accidents such as continuous casting leakage caused by excessive liquid level fluctuations due to unstable crystallizer flow fields, thus solving long-standing technical problems hindering continuous casting production and slab quality. Example 1:

[0049] In this embodiment, the crystallizer has a width of 1900 mm, a thickness of 237 mm, and a pulling speed of 1.2 m / min. The on-site liquid level fluctuation detection system found that the pass rate for liquid level fluctuation ≤ ±3 mm was 93.5%.

[0050] To increase the proportion of liquid level fluctuation values ​​≤ ±3 mm, such as Figure 1 and Figure 2 The inclination angle of the submerged gate was increased from 15 degrees downward to 25 degrees downward, and the shape of the side hole of the submerged gate was optimized from rectangular to elliptical. The optimized gate was applied to the slab production line of a steel company. Under the process conditions of a crystallizer width of 1900 mm, a thickness of 237 mm, and a casting speed of 1.2 m / min, the on-site liquid level fluctuations of three months of production castings were statistically analyzed. It was found that, as Figure 3 The pass rate for liquid level fluctuation values ​​≤ ±3mm was 98.8%. Example Two

[0051] In this example, the process conditions are: the width of the crystallizer is 1800 mm, the thickness is 237 mm, the pulling speed is 1.3 m / min, the shape of the submerged nozzle of the crystallizer is an oval side hole, and the inclination angle is 25 degrees downward.

[0052] Due to the increase in the pulling speed, it is found from the on-site statistics of the liquid level fluctuation that, compared with the liquid level fluctuation of the crystallizer when the pulling speed is 1.0 m / min, the liquid surface flow rate of the crystallizer increases when the pulling speed is increased to 1.3 m / min, and the liquid level fluctuation is intensified.

[0053] In order to control the liquid surface flow rate of the crystallizer and suppress the liquid level fluctuation of the crystallizer, the immersion depth of the nozzle is increased from 110 mm to 160 mm, and the liquid level fluctuation is obviously suppressed. The liquid level fluctuation of the crystallizer when the immersion depth of the nozzle is 110 mm and 160 mm at a pulling speed of 1.3 m / min is compared, as shown in Figure 4 and Figure 5 After increasing the immersion depth of the nozzle, the liquid level fluctuation value of the crystallizer is obviously reduced, and basically meets the requirement that the liquid level fluctuation value is ≤±3 mm. Example Three

[0054] In this example, the width of the crystallizer is 2000 mm, the thickness is 237 mm, the pulling speed is 1.2 m / min, the submerged nozzle adopts an inclination angle of 25 degrees downward and an oval side hole, and the immersion depth of the nozzle is 160 mm. Under this process condition, the normal liquid level fluctuation is basically controlled within ±3 mm, but when the cooling of the casting blank is uneven due to the blockage of the nozzles in the secondary cooling section, the crystallizer liquid level is easily caused to fluctuate periodically due to the bulging of the casting blank. When such a liquid level fluctuation of the crystallizer occurs, the PID of the liquid level control parameter needs to be adjusted accordingly. In order to improve the response speed of the system, the proportional coefficient K P is adjusted from 0.8 to 1.0, and it is found that the liquid level fluctuation is obviously suppressed. Subsequently, in order to continue to suppress the liquid level fluctuation, K I is reduced from 0.5 to 0.2, as shown in Figure 6 , and the liquid level fluctuation basically returns to the normal state, and basically meets the requirement that the liquid level fluctuation value is ≤±3 mm. Example Four

[0055] In this example, the width of the crystallizer is 1800 mm, the thickness is 237 mm, the pulling speed is 1.4 m / min, the submerged nozzle adopts an inclination angle of 25 degrees downward and an oval side hole, and the immersion depth of the nozzle is 160 mm.

[0056] When producing ultra-low carbon steel under this process condition, as shown in Figure 7, liquid level appeared liquid level fluctuation. As can be seen from the figure, the liquid level fluctuation exists many fluctuation value more than ±3mm jump point, generally the case is because the stopper rod head exists nodule, in the process of molten steel casting, nodule with molten steel scouring will occur drop, and then cause crystallizer "jump point type" liquid level fluctuation.

[0057] In order to inhibit the occurrence of such liquid level fluctuation, need to adjust the stopper rod shaking mode to mode two, mainly is to reduce the rotation and shaking frequency of stopper rod, rotation frequency adjustment is 1 Hz, shaking frequency adjustment is 2 Hz, at the same time, the vibration amplitude of stopper rod is adjusted to 1.5 mm.

[0058] After adjusting the stopper rod shaking mode, casting about 10 min, such as Figure 8 , crystallizer liquid level fluctuation returns to normal, liquid level fluctuation no jump point appears, fluctuation value is basically less than ±3 mm.

Claims

1. A method for eliminating the turbulence of the liquid surface of steel in a large-section slab crystallizer, characterized in that The method comprises the following steps: (1) optimizing the structure of the submerged nozzle of the continuous casting crystallizer to inhibit the dynamic instability of the molten steel flow field; (2) increasing the submerged depth of the nozzle; (3) adjusting the PID parameters of the liquid level control system to improve the stability and applicability of the liquid level control system; (4) starting the stopper shaking function to change the flow state of the molten steel in the nozzle and inhibit the disorder of the liquid level of the crystallizer; In the step (1), the inclination angle of the nozzle is increased from 15 degrees to 25 degrees, and the side hole shape of the submerged nozzle is made into an oval shape; In the step (2), the submerged depth of the nozzle, i.e. the distance from the upper edge of the side hole to the liquid level of the crystallizer, reaches 150 mm; In the step (3), ① when the crystallizer liquid surface appears periodic fluctuation, the proportional gain part K of the adjustment control system is increased within the allowable range P ; ② when the fluctuation center value of the crystallizer liquid surface deviates from the standard value, the integral gain part K is decreased within the allowable range I ; ③ when the vibration noise of the crystallizer liquid surface fluctuation is high, the differential gain part K is decreased within the allowable range D ; The proportional gain part K P The allowed range of adjustment is 0.6-2.0, the integral gain part K I The allowed range of adjustment is 0.08-0.3, the differential gain part K D The allowed range of adjustment is 0.05-0.2; Adjust the PID value of the liquid level control system. If the liquid level of the crystallizer is good, the fluctuation value is less than 5 mm, then K P =0.8, K D =0.2, K I =0.2; if the liquid level of the crystallizer is slightly poor, the fluctuation value of 20% of the liquid level is 5-10 mm, then the PID parameters need to be adjusted to K P =1.2, K D =0.1, K I =0.15; if the liquid level fluctuation value of the crystallizer is large, the fluctuation value of 10% of the liquid level exceeds 10 mm, then the PID parameters are adjusted to K P =1.5, K D =0.06, K I =0.1; after the liquid level fluctuation tends to be stable, the PID parameters are adjusted to the original value.

2. The method for eliminating the liquid surface turbulence in the crystallizer of large section slab according to claim 1, characterized in that: In the step (4), ① after the casting of the first furnace in the pouring sequence is completed, the timing is started from the stable molten steel liquid level in the crystallizer, and the stopper rotating and shaking function is started after 10 minutes; ② the stopper shaking of the first four furnaces in the pouring is in mode one, the rotating frequency is 2 Hz, the up-and-down shaking frequency is 5 Hz, and the shaking amplitude is 1 mm; ③ after the pouring of four furnaces, different stopper shaking modes are adopted according to the liquid level fluctuation of the crystallizer: a. if the liquid level fluctuation is good, the stopper shaking mode one is maintained; b. if the liquid level fluctuation curve has many jump points, the stopper shaking is switched to mode two, the rotating frequency is 1 Hz, the up-and-down shaking frequency is 2 Hz, and the shaking amplitude is 1.5 mm, if the jump points cannot be improved, the stopper shaking is closed; c. if the liquid level fluctuation curve has irregular large fluctuations, the stopper shaking is switched to mode three, the rotating frequency is 5 Hz, the up-and-down shaking frequency is 10 Hz, and the shaking amplitude is 1.0 mm.

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