A continuous casting billet grinding method

Abstract

The present invention provides a continuous casting billet grinding method, which specifically includes the following steps: (1) mechanically grinding the upper and lower surfaces of the billet, with a reference grinding depth of X and a grinding depth coefficient of λ=1: grinding the edge area of ​​the upper surface of the billet near the two side edges by X+1mm, and grinding the other areas by Xmm; grinding the edge area of ​​the lower surface of the billet near the two side edges by Xmm, and grinding the other areas by X-0.5mm; the ratio of the width of the edge area to the width of the billet is 1 / 8 to 1 / 6; (2) flame grinding the upper and lower surfaces of the billet after mechanical grinding, and cleaning the joints between the edge area and other areas on the upper and lower surfaces of the billet by flame grinding to form a smooth transition, with the flame grinding depth of 0.3 to 0.5mm; mechanically grinding the two side surfaces of the billet by 5mm. The present invention solves the problems of low grinding efficiency and poor grinding quality in existing mechanical grinding methods.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a continuous casting billet grinding method. Background Art

[0002] As high-end automotive steel and other products place increasingly stringent demands on rolled product surface quality, continuous casting ingots must undergo surface grinding (3-5 mm) to reduce defects such as subsurface inclusions and improve the yield rate of rolled products. Current grinding methods include manual, mechanical, and flame grinding. Manual grinding is inefficient, labor-intensive, and produces inconsistent grinding quality. While flame grinding is highly efficient, it requires the highest investment and offers the best quality.

[0003] Mechanical grinding primarily involves grinding the surface of the ingot using a high-speed rotating grinding wheel. While this method requires less investment than flame cleaning, it suffers from low grinding efficiency and poor grinding quality, including defects in the rolled product caused by the grinding wheel being embedded in the ingot. Summary of the Invention

[0004] In view of the above technical problems of low grinding efficiency and poor grinding quality in the existing mechanical grinding methods, a continuous casting billet grinding method is provided.

[0005] The technical means adopted in the present invention are as follows:

[0006] A continuous casting billet grinding method specifically comprises the following steps:

[0007] (1) Mechanically grind the upper and lower surfaces of the ingot, with the reference grinding depth being X and the grinding depth coefficient being λ = 1:

[0008] Grind the edge area of ​​the upper surface of the billet close to the two side edges by X+1mm, and grind the other areas by Xmm; Grind the edge area of ​​the lower surface of the billet close to the two side edges by Xmm, and grind the other areas by X-0.5mm; the width of the edge area accounts for 1 / 8 to 1 / 6 of the billet width;

[0009] (2) The upper and lower surfaces of the ingot after mechanical grinding are flame ground once, and the joints between the upper edge area and other areas on the upper and lower surfaces of the ingot are cleaned by flame grinding to form a smooth transition. The flame grinding depth is 0.3 to 0.5 mm; the two side surfaces of the ingot are mechanically ground by 5 mm.

[0010] Furthermore, it also includes:

[0011] (3) For the first ingot of each shift, grinding is performed according to steps (1) and (2) under the conditions that the reference grinding depth is x1=X and the grinding depth coefficient is λ1=λ. The ingots before and after grinding are weighed on the same weighing machine and the weights w1 and w2 are recorded. The corrected grinding depth coefficient λ2 is calculated according to the following formula. The corrected reference grinding depth is x2=x1*λ2:

[0012] λ2=1000(w1-w2) / ((2WX+Wa-0.5W(1-a)+Hh)Lρ)

[0013] Where L, W, and H represent the length, width, and height of the billet, respectively; ρ represents the density of steel; a represents the ratio of the width of the edge area to the width of the billet; and h represents the depth of mechanical grinding of the billet side, i.e., 5 mm.

[0014] (4) In each shift, except for the first ingot, when the other ingots are ground according to steps (1) and (2), the reference grinding depth used is x2 and the grinding depth coefficient is λ2.

[0015] Furthermore, in step (1), X is 2 to 4 mm.

[0016] Furthermore, step (1) specifically includes:

[0017] First, grind the entire upper surface of the ingot by Xmm, and then grind the edge area of ​​the upper surface of the ingot near the two side edges by another 1mm;

[0018] Then turn the ingot over, first grind the entire lower surface of the ingot to X-0.5mm, and then grind the 1 / 8 to 1 / 6 area of ​​the lower surface of the ingot close to the two side edges for another 0.5mm.

[0019] Furthermore, the grinding depth of the grinding machine used in step (1) is 0.8 to 1.2 mm.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. Combined with the flow characteristics of molten steel in the crystallizer, inclusions are more distributed on the upper surface of the ingot and in the area near the edge. Therefore, the continuous casting ingot grinding method provided by the present invention proposes to use different grinding depths for the upper and lower surfaces and edges, thereby improving the grinding efficiency and reducing metal loss while ensuring quality.

[0022] 2. The continuous casting billet grinding method provided by the present invention removes the grinding wheel embedded objects (mainly aluminum oxide) during mechanical grinding through a manual flame cleaning after mechanical grinding, thereby avoiding rolled material defects caused by the grinding wheel.

[0023] 3. The continuous casting billet grinding method provided by the present invention corrects the grinding depth by weighing so that the grinding depth meets the process requirements, avoids the grinding depth deviation caused by parameters such as the grinding machine pressure and reduction, and improves the stability of the grinding process.

[0024] Based on the above reasons, the present invention can be widely promoted in the field of metallurgy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 This is a schematic diagram of the continuous casting billet grinding method of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, the present invention provides a continuous casting billet grinding method, which specifically includes the following steps:

[0029] (1) Mechanically grind the upper and lower surfaces of the ingot, with the reference grinding depth being X and the grinding depth coefficient being λ = 1:

[0030] Grind the edge area of ​​the upper surface of the billet near the two side edges by X+1mm, and grind the other areas by Xmm; Grind the edge area of ​​the lower surface of the billet near the two side edges by Xmm, and grind the other areas by X-0.5mm; the width of the edge area accounts for 1 / 8 to 1 / 6 of the billet width; the side of the billet refers to the edge in the direction of billet drawing;

[0031] (2) The upper and lower surfaces of the ingot after mechanical grinding are flame-grinded once, and the joints between the edge areas and other areas on the upper and lower surfaces of the ingot are cleaned by flame grinding to form a smooth transition. The flame grinding depth is 0.3 to 0.5 mm; the two side surfaces of the ingot in the direction of billet drawing are mechanically ground by 5 mm; 0.5 mm of the ingot surface is burned off by flame grinding, which can remove the grinding wheel debris (aluminum oxide) embedded in the ingot during mechanical grinding, thereby avoiding defects caused by foreign matter being pressed into the ingot during rolling.

[0032] Furthermore, it also includes:

[0033] (3) For the first ingot of each shift, grinding is performed according to steps (1) and (2) under the conditions that the reference grinding depth is x1=X and the grinding depth coefficient is λ1=λ. The ingots before and after grinding are weighed on the same weighing machine and the weights w1 and w2 are recorded respectively. The unit is t. The corrected grinding depth coefficient λ2 is calculated according to the following formula. The corrected reference grinding depth is x2=x1*λ2:

[0034] λ2=1000(w1-w2) / ((2WX+Wa-0.5W(1-a)+Hh)Lρ)

[0035] Where L, W, and H represent the length, width, and height of the ingot, respectively, in meters; ρ represents the density of the steel, in t / m 3 ; a represents the ratio of the width of the edge area to the width of the billet; h represents the depth of mechanical grinding of the billet side, i.e. 5 mm;

[0036] (4) In each shift, except for the first ingot, when the other ingots are ground according to steps (1) and (2), the reference grinding depth used is x2 and the grinding depth coefficient is λ2.

[0037] Furthermore, in step (1), X is 2 to 4 mm.

[0038] Furthermore, step (1) specifically includes:

[0039] First, grind the entire upper surface of the ingot by Xmm, and then grind the edge area of ​​the upper surface of the ingot near the two side edges by another 1mm;

[0040] Then turn the ingot over, first grind the entire lower surface of the ingot to X-0.5mm, and then grind the 1 / 8 to 1 / 6 area of ​​the lower surface of the ingot close to the two side edges for another 0.5mm.

[0041] Furthermore, the grinding depth of the grinding machine used in step (1) is 0.8 to 1.2 mm.

[0042] The continuous casting slab grinding method of the present invention is described in detail below with reference to Examples 1-2 and the effects achieved by the present invention are described with reference to Comparative Examples 1-2.

[0043] Example 1

[0044] The continuous casting billet grinding method adopted in this embodiment specifically includes the following steps:

[0045] (1) Set the grinding depth coefficient of the first 1.6m wide billet to be ground by Team A to 1, and the reference grinding depth to 2mm; first grind the entire upper surface of the billet by 2mm, then grind the 1 / 8 area (0.2m) of the upper surface of the billet close to the two sides by another 1mm; then turn the billet over, first grind the entire lower surface of the billet by 1.5mm, then grind the 1 / 8 area (0.2m) of the lower surface of the billet close to the two sides by another 0.5mm; the grinding depth of the grinding machine is 0.8~1.2mm per time, and grinding is required 2~3 times;

[0046] (2) The upper and lower surfaces of the ingot after mechanical grinding are flame-grinded by 0.5 mm, and the joints between the edge areas and other areas on the upper and lower surfaces of the ingot are cleaned by flame grinding to form a smooth transition; the two side surfaces of the ingot are mechanically ground by 5 mm;

[0047] (3) The first ingot (0.23m×1.6m×11m) of Class A was weighed and recorded on the same scale before and after grinding. The weights were 30.5t and 29.9t respectively. The actual grinding weight was 0.6t. According to theoretical calculation, the grinding weight should be 0.7t. The corrected grinding depth coefficient calculated by the formula is 1.1. Therefore, the corrected reference grinding depth is 2*1.1=2.2mm.

[0048] (4) Except for the first ingot, the other ingots of Class A were ground according to steps (1) and (2). The reference grinding depth used was 2.2 mm, the grinding depth coefficient was 1.1, and the grinding depth of the grinding machine was 1.1 mm per grinding.

[0049] By adopting the technical solution of this embodiment, the grinding time of a billet in shift A is 56 minutes, the inclusion degradation rate of the billet in one shift is 6.6%, and no defects caused by the grinding wheel appear in the billet after grinding.

[0050] Example 2

[0051] The continuous casting billet grinding method adopted in this embodiment specifically includes the following steps:

[0052] (1) The grinding depth coefficient of the first 1.4m wide billet to be ground by Team B is set to 0.9, and the base grinding depth is 4mm; first, the entire upper surface of the billet is ground by 4mm, and then the 1 / 6 area (0.233m) of the upper surface of the billet close to the two sides is ground by 1mm; then the billet is turned over, and the entire lower surface of the billet is ground by 3.5mm, and then the 1 / 6 area (0.233m) of the lower surface of the billet close to the two sides is ground by 0.5mm; the grinding depth of the grinding machine is 0.8-1.2mm per time, and 4-5 grinding times are required;

[0053] (2) The upper and lower surfaces of the ingot after mechanical grinding are flame-grinded by 0.3 mm, and the joints between the edge areas and other areas on the upper and lower surfaces of the ingot are cleaned by flame grinding to form a smooth transition; the two side surfaces of the ingot are mechanically ground by 5 mm;

[0054] (3) The first ingot (0.23m×1.4m×11m) of Class B was weighed and recorded on the same scale before and after grinding. The weights were 26.9t and 26.0t respectively. The actual grinding weight differed by 0.9t. Theoretically, the grinding weight should be 0.8t. The corrected grinding depth coefficient calculated by the formula is 0.8. Therefore, the corrected reference grinding depth is 4*0.8=3.2mm.

[0055] (4) Except for the first ingot, the other ingots of Class B were ground according to steps (1) and (2). The reference grinding depth used was 3.2 mm, the grinding depth coefficient was 0.8, and the grinding depth of the grinding machine was 1 mm per one grinding.

[0056] Using the technical solution of this embodiment, the grinding time for a single slab during shift B was 136 minutes, and the inclusion degradation rate for the slabs during the entire shift was 4.7%. No grinding wheel-induced defects were observed in the slabs after grinding. Based on Examples 1 and 2, it can be seen that the continuous casting slab grinding method provided by the present invention can ensure that no grinding wheel-induced defects are observed in the slabs after grinding.

[0057] Comparative Example 1

[0058] The continuous casting billet grinding method adopted in Comparative Example 1 specifically includes the following steps:

[0059] (1) Set the grinding depth coefficient of the 1.6m wide ingot to be ground by Team A to 1; grind the upper and lower surfaces of the ingot by 3mm; the grinding depth of the grinding machine is 0.8-1.2mm per time, and grinding is required 3 times;

[0060] (2) Mechanically grind the two sides of the billet by 5 mm;

[0061] (3) The first ingot (0.23m×1.6m×11m) of Class A was weighed and recorded on the same scale before and after grinding. The weights were 30.4t and 29.5t respectively, and the grinding weight was 0.9t.

[0062] In Comparative Example 1, the grinding time for a single slab was 90 minutes; the inclusion degradation rate of the slabs during one shift was 7.5%, of which 1.1% were defects caused by the grinding wheel. Comparing Example 1 with Comparative Example 1, it can be seen that the continuous casting slab grinding method provided by the present invention can reduce slab grinding time, avoid defects caused by the grinding wheel, and reduce the inclusion degradation rate of the slabs.

[0063] Comparative Example 2

[0064] The continuous casting billet grinding method adopted in Comparative Example 2 specifically includes the following steps:

[0065] (1) The grinding depth coefficient of the first 1.6m wide billet to be ground by Team A is set to 1; first, grind the entire upper surface of the billet by 2mm, and then grind the 1 / 8 area (0.2m) of the upper surface of the billet near the two sides by another 1mm; then turn the billet over, first grind the entire lower surface of the billet by 1.5mm, and then grind the 1 / 8 area (0.2m) of the lower surface of the billet near the two sides by another 0.5mm;

[0066] (2) Mechanically grind the two sides of the ingot by 5 mm.

[0067] In Comparative Example 2, grinding time for a single ingot took 56 minutes, and the inclusion degradation rate for a single shift was 7.7%, of which 1.2% were due to defects caused by the grinding wheel. Comparing Example 1 with Comparative Example 2 reveals that the lack of flame grinding in Comparative Example 2 resulted in a higher inclusion degradation rate. Furthermore, the lack of correction for the grinding depth coefficient resulted in some ingots being insufficiently ground and exhibiting a high number of inclusions.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous casting billet grinding method, characterized in that: The specific steps include: (1) Mechanically grind the upper and lower surfaces of the ingot, with the reference grinding depth being X and the grinding depth coefficient being λ = 1: Grind the edge area of ​​the upper surface of the billet close to the two side edges by X+1mm, and grind the other areas by Xmm; Grind the edge area of ​​the lower surface of the billet close to the two side edges by Xmm, and grind the other areas by X-0.5mm; the width of the edge area accounts for 1 / 8 to 1 / 6 of the billet width; (2) The upper and lower surfaces of the ingot after mechanical grinding are flame ground once, and the joints between the upper edge area and other areas on the upper and lower surfaces of the ingot are cleaned by flame grinding to form a smooth transition. The flame grinding depth is 0.3 to 0.5 mm; the two side surfaces of the ingot are mechanically ground by 5 mm.

2. The continuous casting billet grinding method according to claim 1, characterized in that: Also includes: (3) For the first ingot of each shift, grinding is performed according to steps (1) and (2) under the conditions that the reference grinding depth is x1=X and the grinding depth coefficient is λ1=λ. The ingots before and after grinding are weighed on the same weighing machine and the weights w1 and w2 are recorded. The corrected grinding depth coefficient λ2 is calculated according to the following formula. The corrected reference grinding depth is x2=x1*λ2: λ2=1000(w1-w2) / ((2WX+Wa-0.5W(1-a)+Hh)Lρ) Where L, W, and H represent the length, width, and height of the billet, respectively; ρ represents the density of steel; a represents the ratio of the width of the edge area to the width of the billet; and h represents the depth of mechanical grinding of the billet side, i.e., 5 mm. (4) In each shift, except for the first ingot, when the other ingots are ground according to steps (1) and (2), the reference grinding depth used is x2 and the grinding depth coefficient is λ2.

3. The continuous casting billet grinding method according to claim 1, characterized in that: In step (1), X is 2 to 4 mm.

4. The continuous casting billet grinding method according to claim 1, characterized in that: Step (1) specifically includes: First, grind the entire upper surface of the ingot by Xmm, and then grind the edge area of ​​the upper surface of the ingot near the two side edges by another 1mm; Then turn the ingot over, first grind the entire lower surface of the ingot to X-0.5mm, and then grind the 1 / 8 to 1 / 6 area of ​​the lower surface of the ingot close to the two side edges for another 0.5mm.

5. The continuous casting billet grinding method according to claim 1, characterized in that: The grinding depth of the grinding machine used in step (1) is 0.8 to 1.2 mm.

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