A control method for automatic passing of a zinc cone through a skin pass mill of a cold rolling hot galvanizing unit

Abstract

The application discloses a control method for automatic passing of a zinc cone through a skin pass mill of a cold-rolled hot galvanizing unit, real-time acquisition of speed data of rollers of a zinc pot section; automatic judgment of whether a zinc pot occurs shutdown and generates a zinc cone in a furnace section; after the zinc cone is generated, recording of initial positions of the first zinc cone and the last zinc cone and real-time tracking of the positions; real-time calculation of distances L1 and L2 between the first zinc cone, the last zinc cone and the skin pass mill respectively and display on a unit HMI; judgment of whether the skin pass mill is in a roller approach state, if the skin pass mill is in the roller approach state and L1 is equal to a preset distance La, control of the skin pass mill to automatically open a roller gap of the skin pass mill; when the last zinc cone enters the skin pass mill and runs a distance forward, automatic closing of the roller gap of the skin pass mill, so that the skin pass mill continues to be put into use and normal production is resumed. The method has high automation degree, accurate tracking control, does not need manual participation, reduces labor intensity and improves production capacity and benefits.

Description

Technical Field

[0001] This invention belongs to the field of cold-rolled hot-dip galvanizing production control, specifically relating to a control method for an automatic zinc cone passing through a leveling machine in a cold-rolled hot-dip galvanizing unit. Background Technology

[0002] In cold-rolled continuous hot-dip galvanizing units, after galvanizing in a zinc pot in the process section according to the unit's process requirements, a leveling machine (smoothing machine) is generally arranged at the unit's outlet section to smooth the strip steel, eliminating the yield plateau and ensuring the surface roughness meets user requirements. The leveling machine and the zinc pot are usually located in different process sections, with a looper in between to store the strip steel. A simplified diagram of the zinc pot and leveling machine is shown in Part VI. During production, various problems inevitably arise that lead to unit shutdowns. After shutdown, a large amount of molten zinc accumulates and solidifies in the strip steel at the zinc pot, causing significant thickening of the strip steel in this area (many steel companies refer to this thickened area as a zinc cone). If the shutdown is prolonged, to prevent the strip steel at the zinc pot from breaking due to being soaked in molten zinc, the strip steel in the zinc pot section may be periodically jogged. This causes newly entering strip steel to also thicken significantly (creating a zinc cone), meaning there may be several sections of thickened strip steel (strip steel with zinc cones).

[0003] After the original design unit was restarted after the fault was dealt with, the operator needed to go to a certain distance in front of the leveling machine or a looper in front of the leveling machine to track the zinc cone part of the strip. When the strip with the zinc cone ran to a certain distance in front of the leveling machine, the operator manually operated the leveling machine to open the rollers. After all the strips with the zinc cone had passed through the leveling machine, the operator then moved the rollers to the leveling machine for leveling operations.

[0004] The following problems exist with this operation and production: 1. Operators may occasionally forget to monitor the situation on-site, causing strips with zinc cones to reach the leveler while it is closed. Strips with zinc cones are very likely to get stuck on the leveler, causing strip breakage or even damage to the leveler rollers. The work rollers need to be replaced before production can continue, increasing roller wear and delaying the normal resumption of production. 2. Even if operators monitor the situation on-site, the monitoring may not be very accurate, and the actual number of areas with zinc cones cannot be accurately determined. 3. Relying on manual on-site monitoring is labor-intensive and requires a lot of effort from the personnel. Summary of the Invention

[0005] The purpose of this invention is to provide a control method for the automatic passage of zinc cones through a leveling machine in a cold-rolled hot-dip galvanizing unit. This control method can display the distance between the strip with zinc cones and the leveling machine, and can allow the zinc cones to automatically pass through the leveling machine in a quick-opening roll gap mode. The entire process can be completed without operator intervention, improving the safety and continuity of production and creating good economic benefits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a control method for an automatic zinc cone leveling machine in a cold-rolled hot-dip galvanizing unit, characterized by comprising the following steps: S1. Real-time acquisition of speed data of each roller in the zinc pot section within the unit's PLC; S2. Automatically determine whether the furnace section where the zinc pot is located has stopped and generated zinc cones based on the speed data of the rollers in the zinc pot section; S3. After determining that a zinc cone has been generated, record the initial positions of the first and last zinc cones generated, and track the positions of the first and last zinc cones in real time. S4. Based on the positions of the first and last zinc cones, calculate the distance L1 between the first zinc cone and the leveling machine and the distance L2 between the last zinc cone and the leveling machine in real time, and display L1 and L2 on the unit HMI in real time. S5. Determine whether the leveling machine is in the roller-adjusting state. If the leveling machine is in the roller-adjusting state and the distance L1 between the first zinc cone and the leveling machine is equal to the preset distance La, control the leveling machine to automatically enter the quick-opening mode and open the leveling machine roller gap by 10-20mm. When the last zinc cone enters the leveling machine and moves forward a distance of 5-10m, automatically close the leveling machine roller gap, so that the leveling machine can continue to be used and resume normal production.

[0007] Furthermore, when the speed of the furnace section containing the zinc pot is detected to drop to zero and remain so for more than 2 seconds, a shutdown is determined and a zinc cone is generated; The first zinc cone identification step is as follows: Let M0 be the logical variable of the first zinc cone. M0 is initially 0. When the first stop is determined and a zinc cone is generated, M0 is set to 1 and a pulse signal M1 is generated at the moment the first zinc cone is generated. The last zinc cone identification step is: under the condition that M0 is 1, if it is determined again that the speed of the furnace section is zero and lasts for more than 2 seconds, then it is determined that the last zinc cone is generated and the pulse signal M2 of the last zinc cone is generated. Once the last zinc cone has entered the leveling machine and traveled 5-10m forward, reset M0 to 0.

[0008] Furthermore, the real-time distance L1 between the first zinc cone and the leveling machine is L1 = LS1 - LSD1, where LS1 is the total length of the strip from the zinc pot to the leveling machine when the M1 pulse signal is generated; LSD1 is the distance the strip has traveled after the first zinc cone is generated, and LSD1 = 0 when the M1 pulse signal is generated. The distance L2 between the last zinc cone and the leveling machine is L2 = LS2 - LSD2, where LS2 is the total length of the strip from the zinc pot to the leveling machine when the M2 pulse signal is generated; LSD2 is the distance traveled after the last zinc cone is generated, and LSD2 = 0 when the M2 pulse signal is generated.

[0009] Furthermore, LSD1 and LSD2 are calculated as follows: the actual speed v of the tension roller located between the looper outlet and the leveler is obtained, and the length DL of the strip passing through each scanning cycle t of the real-time computer group PLC program is obtained, where DL = vt; within each program scanning cycle, LSD1 and LSD2 are accumulated with DL as the increment to obtain the updated LSD1 and LSD2.

[0010] Furthermore, the preset distance La is 8-15m.

[0011] Compared with related technologies, the present invention has the following beneficial effects: This invention enables automatic tracking and real-time display of zinc cones by adding a control program to the PLC of the unit. Specifically, the distance between the first and last zinc cones and the leveling machine can be displayed on the HMI in real time. If the leveling machine is in the roller-adaptive working state, the leveling machine is controlled to automatically enter the fast-opening mode, automatically opening a certain roller gap so that all the strip steel with zinc cones can automatically pass through the leveling machine, and then resume normal leveling production.

[0012] Using the method of this invention, the unit has a high degree of automation, accurate tracking and control, and no human intervention is required throughout the process, which reduces the labor intensity of operators and improves production capacity and efficiency. Attached Figure Description

[0013] Figure 1 This is a flowchart illustrating the control method of the present invention.

[0014] Figure 2 This is a schematic diagram of the structure of a cold-rolled continuous hot-dip galvanizing unit.

[0015] In the diagram, 1. Furnace; 2. Zinc pot; 3. Strip steel; 4. Loop; 5. Tension roller; 6. Leveling machine. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] As shown in Figure 1, the present invention provides a control method for an automatic zinc cone passing through a leveling machine in a cold-rolled hot-dip galvanizing unit, comprising the following steps.

[0018] (1) Real-time acquisition of speed data of each roller in the zinc pot section of the unit PLC.

[0019] (2) When the speed of the furnace section where the zinc pot is located is detected to become zero and last for more than 2 seconds, it is determined that a shutdown has occurred and a zinc cone is generated.

[0020] (3) After determining that a zinc cone is generated, record the initial positions of the first and last zinc cones generated, and track the positions of the first and last zinc cones in real time.

[0021] The first zinc cone identification step is as follows: Let M0 be the logical variable of the first zinc cone. M0 is initially 0. When the first shutdown is determined and a zinc cone is generated, M0 is set to 1 and a pulse signal M1 is generated at the moment the first zinc cone is generated.

[0022] The final zinc cone identification step is as follows: With M0 set to 1, if the furnace section speed is again determined to be zero and remains so for more than 2 seconds, then the final zinc cone is determined to be generated, and a pulse signal M2 for the final zinc cone is generated. In actual production, M2 may be generated multiple times. For example, when there are 3 zinc cones, the 2nd and 3rd zinc cones will both generate pulse signal M2, meaning M2 is generated twice. The pulse signal M2 generated by the 3rd zinc cone is then the final zinc cone pulse signal. Similarly, when there are 5 zinc cones, M2 will be generated 4 times, and the pulse signal M2 generated by the 5th zinc cone is then the final zinc cone pulse signal.

[0023] (4) Based on the positions of the first zinc cone and the last zinc cone, calculate the distance L1 between the first zinc cone and the leveling machine and the distance L2 between the last zinc cone and the leveling machine in real time, and display L1 and L2 on the unit HMI in real time.

[0024] Specifically, the real-time distance L1 between the first zinc cone and the leveling machine is L1 = LS1 - LSD1, where LS1 is the total length of the strip from the zinc pot to the leveling machine when the M1 pulse signal is generated; LSD1 is the running distance of the strip, and LSD1 = 0 when the M1 pulse signal is generated.

[0025] The distance between the last zinc cone and the leveling machine is L2 = LS2 - LSD2, where LS2 is the total length of the strip from the zinc pot to the leveling machine when the M2 pulse signal is generated; LSD2 is the running distance of the strip, and LSD2 = 0 when the M2 pulse signal is generated.

[0026] LSD1 and LSD2 are calculated as follows: the actual speed v of the tension roller located between the looper outlet and the leveler is obtained, and the length DL of the strip passing through each scan cycle t (e.g., t=20ms) of the real-time computer group PLC program is obtained, where DL=vt; within each program scan cycle, LSD1 and LSD2 are accumulated with DL as the increment to obtain the updated LSD1 and LSD2. (5) Determine if the leveling machine is in the roller-adjusting state. If the leveling machine is in the roller-adjusting state, and the distance L1 between the first zinc cone and the leveling machine is equal to 10m, control the leveling machine to automatically enter the quick-opening mode (this mode opens a certain size of roller gap). Under normal zinc pot temperature and when the operator moves the machine a certain distance every half hour to one hour, the thickness of the zinc cone is much less than 10mm. In this embodiment, the roller gap of the leveling machine is opened by 15mm, which is greater than the height of the zinc cone, to ensure the safe passage of the zinc cone. When the last zinc cone enters the leveling machine and travels forward a distance of 5m, the roller gap of the leveling machine is automatically closed, and M0 is reset to 0; so that the leveling machine can continue to be used and resume normal production.

[0027] Those skilled in the art should recognize that the above examples are merely illustrative of the invention and are not intended to limit the scope of the invention. Any variations or modifications to the above embodiments that are within the scope of the invention's implementation will fall within the scope of the invention's claims.

Claims

1. A control method for an automatic zinc cone passing through a leveling machine in a cold-rolled hot-dip galvanizing unit, characterized in that, Includes the following steps: S1. Real-time acquisition of speed data of each roller in the zinc pot section within the unit's PLC; S2. Automatically determine whether the furnace section where the zinc pot is located has stopped and generated zinc cones based on the speed data of the rollers in the zinc pot section; S3. After determining that a zinc cone has been generated, record the initial positions of the first and last zinc cones generated, and track the positions of the first and last zinc cones in real time. S4. Based on the positions of the first and last zinc cones, calculate the distance L1 between the first zinc cone and the leveling machine and the distance L2 between the last zinc cone and the leveling machine in real time, and display L1 and L2 on the unit HMI in real time. S5. Determine whether the leveling machine is in the roller-adjusting state. If the leveling machine is in the roller-adjusting state and the distance L1 between the first zinc cone and the leveling machine is equal to the preset distance La, control the leveling machine to automatically enter the quick-opening mode and open the leveling machine roller gap by 10-20mm. When the last zinc cone enters the leveling machine and moves forward a distance of 5-10m, automatically close the leveling machine roller gap, so that the leveling machine can continue to be used and resume normal production.

2. The control method for the automatic zinc cone passing through the leveling machine of the cold-rolled hot-dip galvanizing unit according to claim 1, characterized in that, When the speed of the furnace section containing the zinc pot drops to zero and remains so for more than 2 seconds, a shutdown is detected and a zinc cone is generated. The first zinc cone identification step is as follows: Let M0 be the logical variable of the first zinc cone. M0 is initially 0. When the first stop is determined and a zinc cone is generated, M0 is set to 1 and a pulse signal M1 is generated at the moment the first zinc cone is generated. The last zinc cone identification step is: under the condition that M0 is 1, if it is determined again that the speed of the furnace section is zero and lasts for more than 2 seconds, then it is determined that the last zinc cone is generated and the pulse signal M2 of the last zinc cone is generated. Once the last zinc cone has entered the leveling machine and traveled 5-10m forward, reset M0 to 0.

3. The control method for the automatic zinc cone passing through the leveling machine of the cold-rolled hot-dip galvanizing unit according to claim 2, characterized in that: The real-time distance L1 between the first zinc cone and the leveling machine is L1 = LS1 - LSD1, where LS1 is the total length of the strip from the zinc pot to the leveling machine when the M1 pulse signal is generated; LSD1 is the distance the strip has traveled after the first zinc cone is generated, and LSD1 = 0 when the M1 pulse signal is generated. The distance L2 between the last zinc cone and the leveling machine is L2 = LS2 - LSD2, where LS2 is the total length of the strip from the zinc pot to the leveling machine when the M2 pulse signal is generated; LSD2 is the distance traveled after the last zinc cone is generated, and LSD2 = 0 when the M2 pulse signal is generated.

4. The control method for the automatic zinc cone passing through the leveling machine of the cold-rolled hot-dip galvanizing unit according to claim 3, characterized in that: The LSD1 and LSD2 are calculated as follows: the actual speed v of the tension roller located between the looper outlet and the leveler is obtained, and the length DL of the strip passing through each scanning cycle t of the real-time computer group PLC program is obtained, where DL = vt; within each program scanning cycle, LSD1 and LSD2 are accumulated with DL as the increment to obtain the updated LSD1 and LSD2.

5. The control method for the automatic zinc cone passing through the leveling machine of the cold-rolled hot-dip galvanizing unit according to claim 1, characterized in that: The preset distance La is 8-15m.

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