A cooling control method for a work roll of a plate mill and a rolling line

Abstract

This invention discloses a cooling control method and rolling line for work rolls in medium and heavy plate rolling mills, comprising the following steps: S1, installing a cooling water flow detector on the cooling water pipeline of the work roll; S2, determining whether the cooling water flow detector is de-energized; if so, proceeding to step S3; otherwise, continuing the determination and jumping to the rolling mill PLC to read the actual cooling water flow data, determining whether the actual cooling water flow data is less than a set value; if so, the rolling mill stops after completing the current pass; otherwise, the rolling mill proceeds normally with steel feeding and rolling; S3, the rolling mill PLC reads abnormal cooling water flow data; S4, whether the abnormal cooling water flow data is equal to a set threshold; if so, proceeding to step S5; otherwise, returning to step S3; S5, setting the work roll cooling water data to zero; S6, initiating an emergency shutdown in the rolling area. This invention avoids the defects of existing technologies, increases hourly production capacity, reduces energy loss during abnormal shutdowns, and lowers equipment maintenance costs.

Description

Technical Field

[0001] This invention relates to automated control technology for heavy plate rolling mills, and more specifically, to a cooling control method for work rolls and a rolling line for medium and heavy plate rolling mills. Background Technology

[0002] In a medium-thick plate rolling mill, the work rolls are the rolls that directly contact the rolled steel plate, causing deformation and ultimately rolling it into the finished product. The drive rolls, driven by a large motor, are the work rolls. The support rolls are rolls that support the deformation of the work rolls under high rolling force; they are not driven by a motor, and the upper support roll is lifted by a support roll balance cylinder.

[0003] like Figure 1 As shown, a conventional 5m wide and thick plate four-high reversible rolling mill consists of four rolls: upper support roll 1, lower support roll 2, upper work roll 3, and lower work roll 4. Cooling water pipes 5 are connected to the work rolls.

[0004] The main functions of cooling water for the work rolls are:

[0005] 1) Reduce the surface temperature of the rolling mill work rolls to decrease the formation of cracks;

[0006] 2) Reduce the temperature difference between the inside and outside of the rolling mill work rolls to lower the thermal stress on the work rolls and prevent breakage;

[0007] 3) Cooling water can also remove iron oxide scale from the surface of rolled steel plates, reducing the quality defects caused by iron oxide scale being pressed into the steel plate;

[0008] 4) Appropriately reduce the temperature of the rolling mill work roll bearings to improve their service life and avoid roll burnout accidents;

[0009] 5) Cooling water for the rolling mill work rolls can indirectly reduce the wear resistance of the water tank and improve its service life.

[0010] However, after prolonged operation, the finishing mill sometimes experiences upper work roll breakage after rolling four passes under load. Because the breakage occurs in the middle of the roll body, with both sides completely separated, the repair process is time-consuming and labor-intensive, and also leaves black marks on the surface of the upper support rolls. The entire repair process took nearly 18 hours. Analysis of the work roll cross-section shows that the roll body broke in the middle, with both sides exhibiting a pot-bottom shape and the central fragment showing a corresponding concave surface, a typical stress fracture. This indicates that the roll underwent significant thermal fatigue during rolling, and the surface stress exceeded the core tensile strength, leading to the roll breakage. Further analysis of the data acquisition system records revealed that the breakage was primarily caused by a sudden change in the cooling water flow feedback value of the work roll. Summary of the Invention

[0011] In view of the above-mentioned defects in the prior art, the purpose of this invention is to provide a cooling control method and rolling line for work rolls of medium and heavy plate rolling mills, so as to avoid the occurrence of breakage defects in the middle part of the work rolls in the prior art, increase hourly production capacity, reduce energy consumption loss during abnormal shutdowns, and reduce equipment maintenance costs.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] On one hand, a cooling control method for work rolls in medium and heavy plate rolling mills includes the following steps:

[0014] S1. Install a cooling water flow detector on the cooling water pipeline of the working roll;

[0015] S2. Determine whether the cooling water flow detector is de-energized. If yes, proceed to step S3. If no, jump to the rolling mill PLC to read the actual cooling water flow data and determine whether the actual cooling water flow data is less than the set value. If yes, the rolling mill will stop after completing the current pass of rolling. If no, the rolling mill will feed steel and roll normally.

[0016] S3. The rolling mill PLC reads abnormal cooling water flow data;

[0017] S4. Is the abnormal cooling water flow rate data equal to the set threshold? If yes, proceed to step S5; otherwise, return to step S3.

[0018] S5, Set the data for the cooling water of the working roller to zero;

[0019] S6. Emergency shutdown initiated in the rolling zone.

[0020] Preferably, the cooling control method further includes determining the power supply status of the upstream power supply of the cooling water flow detector.

[0021] Preferably, determining the power supply status of the upstream power source of the cooling water flow detector specifically includes:

[0022] A. Turn on the upstream power supply of the cooling water flow detector;

[0023] B. Check if the upstream power supply is de-energized. If yes, proceed to step C; otherwise, continue the judgment.

[0024] C. The rolling mill PLC reads the low-level signal of the auxiliary contact of the previous power supply and jumps to step S6, initiating an emergency shutdown in the rolling area.

[0025] On the other hand, a rolling line for work rolls of medium and heavy plate rolling mills includes a cooling water flow detector installed on the cooling water pipeline of the work rolls, and auxiliary contacts of the power supply switch of the upstream power supply.

[0026] The cooling water flow detector, the auxiliary contact of the power supply switch, and the rolling mill PLC establish data communication.

[0027] The rolling mill line for the work rolls of the medium and heavy plate rolling mill implements the cooling control method for the work rolls of the medium and heavy plate rolling mill.

[0028] This invention provides a cooling control method and rolling line for work rolls in medium and heavy plate rolling mills, avoiding the defects of existing technologies, increasing hourly production capacity, reducing energy loss during abnormal shutdowns, and lowering equipment maintenance costs. It can be applied to similar rolling mill work roll cooling water control methods and has broad application value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the existing rolling mill work roll cooling water layout on site;

[0030] Figure 2 This is a schematic flowchart of the cooling control method of the present invention;

[0031] Figure 3 This is a schematic diagram of the frame of the rolling mill of the present invention. Detailed Implementation

[0032] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] Combination Figure 2 As shown, the present invention provides a cooling control method for work rolls in medium and heavy plate rolling mills, comprising the following steps:

[0034] S1. Install a cooling water flow detector on the cooling water pipeline of the working roll;

[0035] S2. Determine if the cooling water flow detector is de-energized. If yes, proceed to step S3. If no, continue to determine and jump to the rolling mill PLC to read the actual cooling water flow data. Determine if the actual cooling water flow data is less than the set value. If yes, the rolling mill will stop after completing the current pass of rolling. If no, the rolling mill will feed steel and roll normally.

[0036] S3. The rolling mill PLC reads abnormal cooling water flow data;

[0037] S4. Is the abnormal cooling water flow rate data equal to the set threshold? If yes, proceed to step S5; otherwise, return to step S3.

[0038] S5, Set the data for the cooling water of the working roller to zero;

[0039] S6. Emergency stop is initiated in the rolling zone (Quick Stop).

[0040] The cooling control method of the present invention also includes determining the power supply status of the upstream power supply of the cooling water flow detector.

[0041] Determining the power supply status of the upstream power source for the cooling water flow detector specifically includes:

[0042] A. Turn on the upstream power supply of the cooling water flow detector;

[0043] B. Check if the upstream power supply is lost. If yes, proceed to step C; otherwise, continue to check.

[0044] C. The rolling mill PLC reads the low-level signal from the auxiliary contact of the previous power supply and jumps to step S6, initiating an emergency stop in the rolling area.

[0045] Combination Figure 3 As shown, the present invention also provides a rolling line for the work roll of a medium and heavy plate rolling mill, including a cooling water flow detector 10 disposed on the cooling water pipeline of the work roll, and an auxiliary contact 20 for the power supply switch of the upper-level power supply.

[0046] Data communication is established between the cooling water flow detector 10, the auxiliary contact 20 of the power supply switch, and the rolling mill PLC 30.

[0047] The cooling control method for work rolls in medium and heavy plate rolling mills is realized by means of the rolling line of the work rolls of the present invention.

[0048] Example

[0049] See again Figure 2 and Figure 3 As shown, the rolling mill PLC30 control system collects data signals from the cooling water flow detector 10 to determine if the data is abnormal. It also uses the signal from the auxiliary contact 20 of the added power supply switch to determine if there is a power failure. Based on the logic control, it issues a command to stop the rolling mill in case of abnormal water flow. This prevents damage to the rolling mill work rolls caused by abnormal water flow, reduces abnormal mill downtime, and lowers equipment maintenance costs.

[0050] The above-mentioned method for controlling the cooling water of the work rolls of a four-roll reversible rolling mill includes the following steps:

[0051] 1) Power supply for cooling water flow detector 10;

[0052] 2) Determine if the cooling water flow detector 10 is de-energized. If yes, proceed to step 3); if no, continue to determine and jump to the rolling mill PLC 30 to read the actual flow data. Determine if the actual data of the four sets of basic water flow is less than 6. If yes, the rolling mill will stop after completing the current pass rolling. If no, the rolling mill will proceed with normal steel feeding and rolling.

[0053] 3) The flow rate data read by the rolling mill PLC30 is abnormal;

[0054] 4) Are all four sets of basic water flow data equal to the fixed value of 4095 when the power is off? If yes, proceed to step 5); if no, return to step 3.

[0055] 5) Set the data of cooling water flow detector 10 to zero;

[0056] 6) Start Quick Stop in the rolling mill area.

[0057] At the same time, further judgment is made on the power supply status of the upstream power supply of the cooling water flow detector 10:

[0058] A) The upstream power supply of the cooling water flow detector 10;

[0059] B) Check if the upstream power supply is lost. If yes, proceed to step C); otherwise, continue checking.

[0060] C) The rolling mill PLC30 reads the low-level signal from the auxiliary power contact of the previous stage and jumps to step 6), and the rolling mill area starts Quick Stop to stop.

[0061] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A cooling control method for work rolls in medium and heavy plate rolling mills, characterized in that, Includes the following steps: S1. Install a cooling water flow detector on the cooling water pipeline of the working roll; S2. Determine whether the cooling water flow detector is de-energized. If yes, proceed to step S3. If no, jump to the rolling mill PLC to read the actual cooling water flow data and determine whether the actual cooling water flow data is less than the set value. If yes, the rolling mill will stop after completing the current pass of rolling. If no, the rolling mill will feed steel and roll normally. S3. The rolling mill PLC reads abnormal cooling water flow data; S4. Is the abnormal cooling water flow rate data equal to the set threshold? If yes, proceed to step S5; otherwise, return to step S3. S5, Set the data for the cooling water of the working roller to zero; S6. Emergency shutdown initiated in the rolling zone. The cooling control method further includes determining the power supply status of the upstream power source of the cooling water flow detector. Specifically, it includes: A. Turn on the upstream power supply of the cooling water flow detector; B. Check if the upstream power supply is de-energized. If yes, proceed to step C; otherwise, continue the judgment. C. The rolling mill PLC reads the low-level signal of the auxiliary contact of the previous power supply and jumps to step S6, initiating an emergency shutdown in the rolling area.

2. A rolling mill line for work rolls in medium and heavy plate rolling mills, characterized in that: Includes a cooling water flow detector installed on the cooling water pipeline of the working roller, and auxiliary contacts of the power supply switch of the upstream power supply; The cooling water flow detector, the auxiliary contact of the power supply switch, and the rolling mill PLC establish data communication. The rolling mill line for the work rolls of the medium and heavy plate rolling mill implements the cooling control method for the work rolls of the medium and heavy plate rolling mill as described in claim 1.

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