Continuous casting billet coping method

Abstract

The invention provides a continuous casting billet grinding method which specifically comprises the following steps that (1) the upper surface and the lower surface of a casting billet are mechanically ground, the standard grinding depth is X, the grinding depth coefficient is lambda = 1, the edge areas, close to two side edges, of the upper surface of the casting billet are ground by X + 1 mm, and other areas are ground by X mm; the edge areas, close to the two side edges, of the lower surface of the casting blank are ground by Xmm, and other areas are ground by X-0.5 mm; the width of the edge area accounts for 1 / 8-1 / 6 of the width of the casting blank; (2) the upper surface and the lower surface of the casting blank subjected to mechanical grinding are subjected to flame grinding once, joints between the upper edge areas and other areas of the upper surface and the lower surface of the casting blank are cleaned through flame grinding to form smooth transition, and the flame grinding depth is 0.3-0.5 mm; and the two side faces of the casting blank are mechanically ground by 5 mm. The problems that an existing mechanical grinding method is low in grinding efficiency and poor in grinding quality are solved.

Description

Technical Field

[0001] The 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 have higher and higher requirements for the surface quality of rolled products, continuous casting billets must be surface ground (3-5mm) to reduce defects such as subcutaneous inclusions and improve the qualified rate of rolled products. Currently, grinding includes manual grinding, mechanical grinding and flame grinding. Manual grinding has low efficiency, high labor intensity and unstable grinding quality; although flame grinding is very efficient, it has the highest investment and the best grinding quality.

[0003] Mechanical grinding mainly uses a high-speed rotating grinding wheel to grind the surface of the ingot. Compared with flame cleaning, it requires less investment, but has problems such as low grinding efficiency and poor grinding quality, including defects in rolled products caused by the grinding wheel embedded in the ingot. Summary of the invention

[0004] According to 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 by 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 sides 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 sides 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-grinded 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 0.3-0.5 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] Wherein, L, W, H represent the length, width, and height of the ingot, respectively; ρ represents the density of steel; a represents the ratio of the width of the edge area to the width of the ingot; h represents the depth of mechanical grinding of the ingot 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 the area near the edge. Therefore, the continuous casting ingot grinding method provided by the present invention proposes different grinding depths for the upper and lower surfaces and the edges, which improves the grinding efficiency and reduces 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 the rolling 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 the pressing amount, and improves the stability of the grinding process.

[0024] Based on the above reasons, the present invention can be widely promoted in the metallurgical field. 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0026] Figure 1 It 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 by no means 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 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 comprises 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 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; 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 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 0.3-0.5 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 to remove the grinding wheel detachment (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, in units of 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, H represent the length, width, and height of the ingot, respectively, in m; 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 specifically described below in conjunction with Examples 1-2, and the effects achieved by the present invention are described in conjunction with Comparative Examples 1-2.

[0043] Example 1

[0044] The continuous casting billet grinding method adopted in this embodiment specifically comprises 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, and then grind the 1 / 8 area (0.2m) of the upper surface of the billet close to the two sides by 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 close to the two sides by 0.5mm; the grinding depth of the grinder 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 sides 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 weighing machine before and after grinding. The weights were 30.5t and 29.9t respectively. The actual grinding weight was 0.6t. Theoretically, the grinding weight should be 0.7t. The corrected grinding depth coefficient calculated by the formula was 1.1. Therefore, the corrected reference grinding depth was 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 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 of shift A is 56 minutes, and the inclusion degradation rate of the billet of one shift is 6.6%. 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 comprises 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 reference 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 grindings 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 sides 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 weighing machine 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 was 0.8. Therefore, the corrected reference grinding depth was 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 was 3.2 mm, the grinding depth coefficient was 0.8, and the grinding depth of the grinding machine was 1 mm per grinding.

[0056] By adopting the technical solution of this embodiment, the grinding time of a cast piece in shift B is 136 minutes, the inclusion degradation rate of the cast piece in one shift is 4.7%, and no defects caused by the grinding wheel appear in the cast piece after grinding. It can be seen from Examples 1-2 that the continuous casting billet grinding method provided by the present invention can ensure that no defects caused by the grinding wheel appear in the cast piece after grinding.

[0057] Comparative Example 1

[0058] The continuous casting billet grinding method adopted in Comparative Example 1 specifically comprises 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 ingot by 5 mm;

[0061] (3) The first ingot (0.23m×1.6m×11m) of Class A was weighed and recorded on the same weighing machine 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 of a cast billet is 90 minutes; the inclusion degradation rate of the cast billet in one shift is 7.5%, of which the defects caused by the grinding wheel are 1.1%. By comparing Example 1 with comparative example 1, it can be seen that the continuous casting billet grinding method provided by the present invention can reduce the grinding time of the cast billet, avoid the defects caused by the grinding wheel, and reduce the inclusion degradation rate of the cast billet.

[0063] Comparative Example 2

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

[0065] (1) Set the grinding depth coefficient of the first 1.6m wide billet to be ground by Team A to 1; 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 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 0.5mm;

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

[0067] In comparative example 2, the grinding time of a cast piece is 56 minutes; the inclusion degradation rate of the cast piece in one shift is 7.7%, of which 1.2% is caused by the grinding wheel. Comparing Example 1 with comparative example 2, it can be seen that comparative example 2 lacks the flame grinding step, resulting in a higher inclusion degradation rate of the cast piece, and because the grinding depth coefficient is not corrected, the grinding amount of some cast pieces is insufficient and there are more 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 sides 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 sides 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-grinded 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 0.3-0.5 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) Wherein, L, W, H represent the length, width, and height of the ingot, respectively; ρ represents the density of steel; a represents the ratio of the width of the edge area to the width of the ingot; h represents the depth of mechanical grinding of the ingot 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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