Slab machine bright surface cleaning control method
By strictly controlling the acceptance, installation, maintenance and operation of the machine cleaning burners, the problem of machine cleaning stripe defects on the surface of cold-rolled thin plates was solved, the 05 surface quality requirements of high-end automotive panels were achieved, and production efficiency was improved.
Patent Information
- Application Number
- CN202510894421.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-09
AI Technical Summary
High-grade cold-rolled thin plates have machine-cleared streak defects on their surface, which cannot be eliminated through hot rolling, pickling and cold rolling processes, affecting the production quality of high-end automotive panels.
The quality and installation accuracy of the burner are ensured by strictly controlling the acceptance, installation, maintenance and operation of the machine-cleaned burner, including steps such as gap and level measurement, hole dredging, pickling and cleaning, and ignition test.
It effectively eliminates the machine cleaning stripe defects, ensures the brightness of the slab surface after machine cleaning, and improves the quality and production efficiency of cold-rolled thin plates.
Smart Images
Figure CN120606138A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a control method for cleaning the bright surface of a slab machine, and belongs to the technical field of slab machine maintenance technology. Background Art
[0002] Cold-rolled sheet with a high-grade surface is primarily used for the panels of mid- to high-end sedans. With technological advancements and rising consumer demands, the modern appliance manufacturing industry and the construction materials industry are placing increasingly stringent demands on the surface quality of cold-rolled sheet. High-grade cold-rolled sheet surfaces must not only be free of defects as determined by optical inspection but also polished with an oilstone, achieving a so-called 05 finish: free of inclusions, scars, scratches, roller marks, and oil stains. The demand for high-quality products has led to the practice of flame cleaning slabs to remove visible surface defects. A flame cleaning machine utilizes high-speed, high-pressure coal or natural gas combustion with oxygen to generate high temperatures, melting the metal on the slab's surface into molten slag that is blown away. This removes surface and shallow subsurface defects, while also exposing some subsurface defects. These defects are then removed by manual flame cleaning or by hot rolling and oxidation.
[0003] However, in actual production, it was discovered that steel plates produced using the machine-clearing process exhibited a high number of longitudinal dark-marked defects, known as machine-clearing streaks. Research results indicate that machine-clearing streaks primarily form during the machine-clearing process of the slab. The root cause is that the iron scale at the top and base of the machine-clearing ridges is entrained into the substrate during rolling, resulting in the presence of subsurface iron scale at the machine-clearing streaks. Subsurface iron scale can be caused by the instability and collapse of the ridges or by metal flow on the surface of the billet. Furthermore, these machine-clearing streaks cannot be eliminated through various processes, such as hot rolling, pickling, and cold rolling, and are highly hereditary. They appear on the surface of hot-rolled coils and are inherited by galvanized products, resulting in substandard surface finishes, impacting production and quality yields. This has become a significant technical challenge for manufacturers of high-end automotive panels.
[0004] Production practice experience shows that the main reason for the ridges and grooves on the surface of the slab during the flame cleaning process is the aging of the machine cleaning burner. Therefore, by controlling the quality requirements of the acceptance, installation, maintenance and operation of the machine cleaning burner, the purpose of a bright surface of the slab after machine cleaning can be achieved, thereby eliminating the machine cleaning streak defects of high-grade surface cold-rolled thin plates in the subsequent process. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a control method for cleaning the bright surface of a slab machine. This control method starts from the process of acceptance, installation, maintenance and operation of the machine cleaning burner, and can achieve the requirements of cleaning the bright surface of the slab machine, thereby eliminating the machine cleaning stripe defects of high-grade surface cold-rolled thin plates and meeting the 05 surface quality requirements of high-end automobile panels.
[0006] The technical solution to the above technical problems is: A control method for brightening the surface of a slab machine comprises the following steps: The first step is the acceptance of the machine cleaning burner In addition to meeting the requirements of standard drawings and being free of deformation and damage, the machine-cleaned burner must also meet the following standards: The installation gap between the upper preheating block head and the upper preheating block base is less than 0.2mm; The installation gap between the lower preheating block head and the lower preheating block base is less than 0.2mm; The burner size of the upper and lower preheating blocks must be 271.5±0.1mm, otherwise electroplating is required; The second step is to install the machine cleaning burner A measurement is performed each time the burner is replaced. The measurement requires that the edge of the high-pressure water pipe and the edge of the burner on the same side are in the same vertical plane, and a wire weight is used for measurement; The third step is the maintenance of the machine cleaning burner The burner holes of the machine cleaning machine are cleared online, pickled and cleaned offline; Perform an upper and lower level measurement every time the burner is replaced; Replace the clogged burner; For each batch of burners put into production, one combination burner shall be randomly selected for ignition test on the test bench; Step 4: Quality requirements for machine cleaning operations The local unevenness after machine cleaning is h≤2mm and h / W≤10%.
[0007] The control method for cleaning the bright surface of the slab machine mentioned above, the second step of burner installation, first install the 3# and 4# burners, move the 3# burner as close as possible to the 4# burner, then install the 2# and 1# burners in sequence, and then install the 5#, 6#, and 7# burners in sequence. During installation, ensure that the gap between the small preheating blocks is within 0.3mm and the misalignment is within 0.5mm.
[0008] In the above-mentioned control method for cleaning the bright surface of the slab machine, when the burner hole of the machine cleaning is dredged online in the third step, it is prohibited to use an electric drill for dredging, and only manual cleaning with a needle is allowed.
[0009] The control method for brightening the surface of the slab machine mentioned above requires that the upper and lower level measurements of the burners in the third step should be such that the horizontal difference between the 1# burner and the last burner is within 5 mm, the upper level is measured using a U-shaped hose, and the lower level is measured using a spirit level.
[0010] The control method for cleaning the bright surface of the slab machine mentioned above, the requirements for online replacement of the burner in the third step are: two or more burner holes are blocked continuously, three or more burner holes in a row are blocked, and five or more burner holes in a burner are blocked.
[0011] In the control method for brightening the surface of the slab machine, the combined burner in the third step is ignited on a test bench. When the oxygen pressure is 200KPa and the natural gas pressure is 40KPa, the flame height difference is less than 30mm.
[0012] In the above-mentioned control method for machine-cleaned bright surface of slab, the local unevenness and ridges after machine cleaning in the fourth step can only be qualified if they meet the following two conditions: Depth: Width: Length ≧ 1: 6: 10 The groove edge and groove bottom have a smooth transition, with an angle greater than 90° The above-mentioned control method for the bright surface of the slab machine cleaning is as follows: the depth of the depression at the beginning of the machine cleaning in the fourth step is: ≤15mm for the upper and lower surfaces, ≤10mm for the side surfaces; the length of the uncleaned part at the front end of the starting point of the machine cleaning is ≤50mm; and a smooth transition is ensured at the beginning of the cleaning.
[0013] The beneficial effects of the present invention are: This invention is a pioneering method for controlling the bright surface of slab mill cleaning. It addresses the problem of mill cleaning streaks on high-end automotive panels that cannot be eliminated through hot rolling, pickling, and cold rolling processes. This control method effectively controls surface irregularities and scale on the mill-cleaned slab, achieving a bright surface after mill cleaning. This eliminates mill cleaning streak defects in subsequent high-grade cold-rolled thin sheets, providing a strong guarantee for improving slab quality and increasing production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a schematic diagram of the installation requirements for the slab machine burner cleaning; Figure 2 This is a schematic diagram of the side high-pressure water installation requirements for the burner cleaning of the billet machine; Figure 3 This is a schematic diagram of the requirements for controlling local unevenness on the surface of the slab after cleaning by the slab machine.
[0015] The markings in the figure are as follows: 1# burner 1, 2# burner 2, 3# burner 3, 4# burner 4, 5# burner 5, 6# burner 6, 7# burner 7, slab 8, side burner 9, side high-pressure water pipe 10. DETAILED DESCRIPTION
[0016] The main reason for the ridges and grooves on the surface of the slab during the flame cleaning process is the aging of the machine cleaning burner. The present invention achieves the purpose of brightening the surface of the slab after machine cleaning through a series of controls such as the acceptance, installation, maintenance, and operation quality requirements of the machine cleaning burner, thereby eliminating the machine cleaning streak defects of high-grade surface cold-rolled thin plates in the subsequent process.
[0017] The present invention is implemented by following steps: The first step is the acceptance of the machine cleaning burner In addition to meeting the requirements of standard drawings and being free of deformation and damage, the machine-cleaned burner must also meet the following standards: The installation gap between the upper preheating block head and the upper preheating block base is less than 0.2mm; The installation gap between the lower preheating block head and the lower preheating block base is less than 0.2mm; The burner size of the upper and lower preheating blocks must be 271.5±0.1mm, otherwise electroplating is required.
[0018] The second step is to install the machine cleaning burner Burner installation: Install burner #3 and burner #4 first, and place burner #3 as close to burner #4 as possible; then install burner #2 and burner #1 in sequence; then install burner #5, #6, and #7 in sequence. During installation, ensure that the gap between the small preheating blocks is within 0.3mm and the misalignment is within 0.5mm; Side high-pressure water installation: Perform a measurement each time after replacing the burner. Requirements: The edge of the high-pressure water pipe and the edge of the side burner are in the same vertical plane. Measurement method: Use a wire pulley for measurement.
[0019] The third step is the maintenance of the machine cleaning burner When clearing the burner hole of the machine on-line, pickling and comprehensive cleaning are carried out offline, it is prohibited to use an electric drill for clearing. Only manual cleaning with a needle is allowed. Burner upper and lower frame levelness requirements: After each burner replacement, perform an upper and lower level measurement: The level difference between the 1# burner and the last burner must be within 5mm. The upper level should be measured with a U-shaped hose and the lower level with a spirit level. Online replacement requirements: two or more burner holes are blocked continuously, three or more burner holes are blocked in a row, and five or more burner holes are blocked in one burner; Test bench usage requirements: For each batch of burners put into production, one combination burner shall be randomly selected for ignition test on the test bench. When the oxygen pressure is 200KPa and the natural gas pressure is 40KPa, the flame height difference shall be less than 30mm.
[0020] Step 4: Machine cleaning operation quality requirements After cleaning, the local unevenness h≤2mm and h / W≤10%; and the local unevenness and ridges meet the following two conditions to be qualified: ① Depth: Width: Length ≧ 1:6:10 ②Smooth transition between the groove edge and the groove bottom (angle greater than 90°) The depth of the depression at the beginning of machine cleaning is: ≤15mm for the upper and lower surfaces, ≤10mm for the side surfaces; the length of the uncleaned part at the front end of the starting point of machine cleaning is ≤50mm, and a smooth transition is ensured at the beginning of cleaning.
[0021] The control method of this invention achieves a bright surface after mechanical cleaning of continuous casting slabs. Surface irregularities and scale are effectively controlled, eliminating mechanical cleaning streaks in subsequent high-grade surface cold-rolled sheet, ensuring improved slab quality and production efficiency. The incidence of mechanical cleaning streaks in high-grade surface cold-rolled sheet and high-end automotive panels has been reduced from 35.61% to below 0.03%.
Claims
1. A control method for bright surface cleaning of a slab machine, characterized by: It includes the following steps: The first step is the acceptance of the machine cleaning burner In addition to meeting the requirements of standard drawings and being free of deformation and damage, the machine-cleaned burner must also meet the following standards: The installation gap between the upper preheating block head and the upper preheating block base is less than 0.2mm; The installation gap between the lower preheating block head and the lower preheating block base is less than 0.2mm; The burner size of the upper and lower preheating blocks must be 271.5±0.1mm, otherwise electroplating is required; The second step is to install the machine cleaning burner A measurement is performed each time the burner is replaced. The measurement requires that the edge of the high-pressure water pipe and the edge of the burner on the same side are in the same vertical plane, and a wire weight is used for measurement; The third step is the maintenance of the machine cleaning burner The burner holes of the machine cleaning machine are cleared online, pickled and cleaned offline; Perform an upper and lower level measurement every time the burner is replaced; Replace the clogged burner; For each batch of burners put into production, one combination burner shall be randomly selected for ignition test on the test bench; Step 4: Quality requirements for machine cleaning operations The local unevenness after machine cleaning is h≤2mm and h / W≤10%.
2. The control method for bright surface cleaning of a slab machine according to claim 1, characterized in that: For the burner installation in the second step, install the 3# and 4# burners first, move the 3# burner as close as possible to the 4# burner, then install the 2# and 1# burners in sequence, and then install the 5#, 6#, and 7# burners in sequence. During installation, ensure that the gap between the small preheating blocks is within 0.3mm and the misalignment is within 0.5mm.
3. The control method for bright surface cleaning of a slab mill according to claim 1, characterized in that: When the burner hole of the machine cleaning in the third step is dredged online, it is prohibited to use an electric drill for dredging, and only a needle is allowed to be used for manual cleaning.
4. The control method for bright surface cleaning of a slab mill according to claim 1, characterized in that: The requirement for measuring the upper and lower levels of the burners in the third step is that the horizontal difference between the 1# burner and the last burner is within 5 mm, the upper level is measured using a U-shaped hose, and the lower level is measured using a spirit level.
5. The control method for bright surface cleaning of a slab machine according to claim 1, characterized in that: The requirements for online replacement of the burner in the third step are: two or more burner holes are blocked continuously, three or more burner holes are blocked in a row, and five or more burner holes are blocked in one burner.
6. The control method for bright surface cleaning of a slab mill according to claim 1, characterized in that: The combined burner in the third step was subjected to an ignition test on a test bench. When the oxygen pressure was 200 KPa and the natural gas pressure was 40 KPa, the height difference of the flame was less than 30 mm.
7. The control method for bright surface cleaning of a slab mill according to claim 1, characterized in that: The local concave-convex and ridged parts after the machine cleaning in the fourth step can only be qualified if they meet the following two conditions: Depth: Width: Length ≧ 1: 6: 10 The groove edge and groove bottom have a smooth transition, and the angle is greater than 90°.
8. The control method for bright surface cleaning of a slab mill according to claim 1, characterized in that: The depth of the depression at the beginning of the machine cleaning in the fourth step is: ≤15mm on the upper and lower surfaces, ≤10mm on the side, the length of the uncleaned part at the front end of the starting point of the machine cleaning is ≤50mm, and a smooth transition is ensured at the beginning of the cleaning.