A method for grinding ultra-low carbon steel billet

Abstract

The present invention belongs to the technical field of metal grinding, and specifically relates to a method for grinding an ultra-low carbon steel billet, comprising: a grinding process, a shot blasting process, and a strong light flaw detection process; the grinding process comprises a rough grinding process and a fine grinding process; the present invention solves the problem that, during the existing ultra-low carbon steel billet grinding process, metal waste generated by cutting is easily adhered to one side of the grinding mark to form a flanging burr defect, and surface defects are generated after rolling deformation, thereby reducing the generation of metal flanging burrs during the billet grinding process, effectively removing the burr defects, and improving the surface quality of the billet.

Description

Technical Field

[0001] The invention belongs to the technical field of metal grinding, and in particular relates to a grinding method for an ultra-low carbon steel billet. Background Art

[0002] During the continuous casting process of ultra-low carbon steel billets, defects such as pores, slag inclusions or vibration marks may appear on the billet surface due to insufficient deoxidation or fluctuations in the molten steel level.

[0003] Grinding is a common surface treatment for steel billets, and during this process, burrs are prone to forming. This defect occurs because ultra-low carbon steel is extremely soft and highly viscous. During the grinding process, scrap metal from the grinding wheel tends to adhere to the wear marks. If this is not completely removed, the burrs cannot be completely burned away during the subsequent rolling process due to the relatively low heating temperature of the ultra-low carbon steel to prevent localized coarse grains. Instead, they remain on the billet surface, where they deform and form surface defects.

[0004] Therefore, the present invention provides a method for grinding an ultra-low carbon steel billet. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that during the existing ultra-low carbon steel billet grinding process, metal waste generated by cutting is easily adhered to one side of the grinding mark to form a flanging burr defect, and surface defects are generated after rolling deformation. The invention reduces the generation of metal flanging burrs during the billet grinding process, effectively removes the burr defects, and improves the surface quality of the billet.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a method for grinding an ultra-low carbon steel billet, comprising a grinding process, a shot blasting process and a strong light flaw detection process; the grinding process comprises a rough grinding process and a fine grinding process;

[0007] S1-1: The rough grinding is performed by fixing the blank by a caliper on a grinding machine;

[0008] S1-2: The grinding machine measures the grinding wheel diameter and the workpiece height through a program, sets the roughing depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70m / min, and moves the grinding wheel from one end of the workpiece to the other end according to the set pressure. After reaching the other end, it moves horizontally in a clockwise direction for a certain distance. The horizontal movement distance is less than the single-pass grinding width. Then, the grinding wheel moves in the opposite direction to the original end. This action is repeated until the roughing of one side of the workpiece is completed.

[0009] S1-3: Open the caliper, turn the blank 45 degrees clockwise by the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the diameter of the grinding wheel, move the grinding wheel from one end of the blank to the other end according to the set pressure, and repeat the action until the pressure reaches the program set value. Then, one chamfering process of the blank is completed. Repeat steps S1-2 and S1-3 until the last chamfering process of the blank is completed;

[0010] The rough grinding process has a single grinding pass width of ≤1mm, a chamfer width of 14±1mm, a grinding width ≥5-10% of the blank width, and a surface roughness Rz≤60 after grinding;

[0011] In the finishing process, the finishing depth is set to 0.05 mm, and steps S1-1 to S1-3 are used to complete the blank surface and chamfer finishing process;

[0012] The single-pass width of the finishing process is ≤0.05mm, the chamfer width is 14±1mm, the grinding width is ≥4-8%mm of the blank width, and the surface roughness after grinding is Rz≤25;

[0013] The shot blasting current of the shot blasting process is controlled at 35±2A;

[0014] Among them, the carbon content of ultra-low carbon steel billet and wire rod is ≤0.03%, and the rest is iron and other elements.

[0015] Preferably, the grinding process uses a fine grinding wheel for grinding, the grinding wheel particle size is ≥24 mesh, and the abrasive material is zirconium corundum.

[0016] Preferably, the shot blasting process uses steel ball shot blasting particles with a particle size of ≤1.0mm.

[0017] Preferably, before the grinding process, the defect depth of the steel billet is confirmed by using strong light and a depth gauge, and the defect depth is ≥1.0 mm.

[0018] Preferably, the strong light flaw detection process is to detect the steel billet after shot blasting by a flaw detector, the billet travel speed of the flaw detector is controlled at 5-10 cm / s, and a light source with a power of ≥80W is used to inspect the surface of the steel billet.

[0019] Preferably, after the roughing process is completed, the surface roughness of the rough-trimmed billet is measured using a roughness instrument. A total of three points are measured, namely the two ends and the center position of the billet. The arithmetic mean of the three points is taken to obtain the surface roughness data of the billet. If the roughness is greater than 60Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

[0020] Preferably, after the finishing process is completed, a roughness instrument is used to measure the surface roughness of the finished steel billet. A total of three points are measured, namely the two ends and the center position of the billet. The arithmetic mean of the three points is taken to obtain the surface roughness data of the steel billet. If the roughness is greater than 25Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention reduces the probability of flanging burr defects during the grinding process through the mutual coordination of roughing and fine finishing. After the roughing is completed, the surface roughness is controlled at Rz≤60 to ensure the surface quality of the finished product after rolling; and after the fine finishing is completed, the surface roughness is controlled at Rz≤25, which improves the surface smoothness of the billet while eliminating defects.

[0023] 2. The present invention changes the current of the shot blasting machine and the size of the shot blasting particles, thereby ensuring the effective removal of burr defects while avoiding the formation of pit defects on the surface of the blank due to the large impact force of the shot blasting particles, which affects the surface quality of the blank and greatly improves the quality of shot blasting. DETAILED DESCRIPTION

[0024] The following specific embodiments further illustrate the method of using the present invention.

[0025] A method for grinding an ultra-low carbon steel billet, comprising a grinding process, a shot blasting process and a strong light flaw detection process; the grinding process comprises a rough grinding process and a fine grinding process;

[0026] S1-1: The rough grinding is performed by fixing the blank by a caliper on a grinding machine;

[0027] The steel billet after flaw detection is transported to the grinding machine frame by a crane, and the frame chain moves the steel billet to the edge of the frame. The billet is then lifted to the grinding machine loading platform by a robotic arm, and the grinding machine fixes the billet with a caliper.

[0028] S1-2: The grinding machine measures the grinding wheel diameter and the workpiece height through a program, sets the roughing depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70m / min, and moves the grinding wheel from one end of the workpiece to the other end according to the set pressure. After reaching the other end, it moves horizontally in a clockwise direction for a certain distance. The horizontal movement distance is less than the single-pass grinding width. Then, the grinding wheel moves in the opposite direction to the original end. This action is repeated until the roughing of one side of the workpiece is completed.

[0029] S1-3: Open the caliper, turn the blank 45 degrees clockwise by the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the diameter of the grinding wheel, move the grinding wheel from one end of the blank to the other end according to the set pressure, and repeat the action until the pressure reaches the program set value. Then, one chamfering process of the blank is completed. Repeat steps S1-2 and S1-3 until the last chamfering process of the blank is completed;

[0030] The rough grinding process has a single grinding pass width of ≤1mm, a chamfer width of 14±1mm, a grinding width ≥5-10% of the blank width, and a surface roughness Rz≤60 after grinding;

[0031] The grinding wheel grit required for roughing must be ≥24. During the roughing process, the grinding carriage speed should be controlled at 60-70 m / min to avoid excessive grinding speed and the resulting bluing of the surface. The roughing process begins by fully grinding the entire surface of the blank, then fully grinding the corners of the blank in a clockwise direction. The remaining surfaces and corners of the blank are then fully ground in sequence until the last chamfer is completed.

[0032] The finishing depth is set to 0.05 mm in the finishing process; steps S1-1 to S1-3 are used to complete the blank surface and chamfer finishing process;

[0033] The single-pass width of the finishing process is ≤0.05mm, the chamfer width is 14±1mm, the grinding width is ≥4-8%mm of the blank width, and the surface roughness after grinding is Rz≤25;

[0034] The grinding wheel grit required for fine finishing must be ≥24. During the fine finishing process, the grinding carriage speed should be controlled at 50-60 m / s to avoid excessive grinding speed and the resulting bluing of the surface. The fine finishing process begins with full grinding of the blank surface, followed by full grinding of the blank corners in a clockwise direction. The remaining surfaces and corners of the blank are then fully ground in sequence until the last chamfer is completed.

[0035] The shot blasting current of the shot blasting process is controlled at 35±2A;

[0036] By controlling the current, the speed at which the shot blasting material impacts the surface of the steel billet can be controlled. When the mass is the same, the faster the speed, the greater the kinetic energy generated, the greater the impact force of the shot blasting material on the surface of the steel billet, and the better the effect of removing burrs on the surface.

[0037] Among them, the carbon content of ultra-low carbon steel billet and wire rod is ≤0.03%, and the rest is iron and other elements.

[0038] The grinding process uses a fine grinding wheel for grinding, the grinding wheel particle size is ≥24 mesh, and the abrasive material is zirconium corundum.

[0039] Zirconia corundum is used as the primary abrasive in the grinding wheel due to its high hardness, excellent wear resistance, and excellent mechanical strength and thermal shock resistance. It can withstand high pressure and wear while maintaining good cutting performance. Furthermore, the abrasive size can be precisely controlled, improving the wear resistance of the grinding wheel while ensuring the surface quality and roughness of the steel billet after grinding.

[0040] The shot blasting process uses steel ball shot blasting particles with a particle size of ≤1.0mm.

[0041] Before the grinding process, the steel billet is confirmed to have a defect depth by using a strong light and a depth gauge, and the defect depth is ≥1.0 mm.

[0042] Before re-grinding, the billet is inspected for surface quality using a flaw detector at a speed of 5-10 cm / s. A light source with a power of ≥80W is used to inspect the billet surface. If defects are found, a depth gauge is used to measure them. Defects ≥1.0 mm in depth require a combination of rough and fine trimming. Defects <1 mm in depth require a single fine trimming pass. Defects on the billet surface include abnormal vibration marks, warping, overlaps, and pits.

[0043] The strong light flaw detection process uses a flaw detector to detect flaws on the steel billet after shot blasting. The flaw detector controls the billet travel speed at 5-10 cm / s and uses a light source with a power of ≥80W to inspect the steel billet surface.

[0044] Before inspection, the billet needs to be divided into equal parts at intervals of 1 meter. During the billet inspection, a depth gauge needs to be used to record the depth of the pits on the billet surface (the shot blasting material impacts the billet surface, and the impact force is large, resulting in pit defects). When a burr defect occurs, a ruler needs to be used to record the burr length within the 1-meter interval.

[0045] After the roughing process is completed, the surface roughness of the rough-trimmed billet is measured using a roughness instrument. A total of three points are measured, namely, the two ends and the center position of the billet. The arithmetic average of the three points is taken to obtain the surface roughness data of the billet. If the roughness is greater than 60Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

[0046] After the finishing process is completed, the surface roughness of the finished steel billet is measured using a roughness instrument. A total of three points are measured, namely the two ends and the center position of the billet. The arithmetic average of the three points is taken to obtain the surface roughness data of the steel billet. If the roughness is greater than 25Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

[0047] The present invention is further described below with reference to the following examples. Example 1

[0048] As shown in Table 1 below, the ultra-low carbon steel billet grinding method includes a grinding process, a shot blasting process, and a strong light flaw detection process. After the ultra-low carbon steel billet has undergone the grinding process, it is shot blasted by a shot blasting machine. First, steel balls are used for shot blasting. The size of the steel ball particles is 2.0 mm, and the current of the shot blasting machine is 45+2A. The billet travel speed of the shot blasting machine is controlled at 2.5-3 m / min. The depth of the pits on the billet surface after shot blasting is 0.15-0.45 mm, and the burr removal rate on the billet surface is 100%.

[0049] When the current of the shot blasting machine is 45-2A, the size of the shot blasting steel ball particles is 1.0mm, the depth of the pits on the surface of the steel billet after shot blasting is 0.08-0.22mm, and the burr removal rate on the surface of the steel billet is 100%. Example 2

[0050] As shown in Table 1 below, the ultra-low carbon steel billet grinding method includes a grinding process, a shot blasting process, and a strong light flaw detection process. After the ultra-low carbon steel billet has undergone the grinding process, it is shot blasted by a shot blasting machine. First, the shot blasting is performed using steel balls with a particle size of 1.0 mm. The current of the shot blasting machine is 35+2A, and the billet travel speed of the shot blasting machine is controlled at 2.5-3 m / min. The depth of the pits on the billet surface after shot blasting is 0.05-0.15 mm, and the burr removal rate on the billet surface is 100%.

[0051] When the current of the shot blasting machine is 35-2A, the size of the shot blasting steel ball particles is 1.0mm, the pit depth of the steel billet surface after shot blasting is 0mm, and the burr removal rate of the steel billet surface is 100%. Example 3

[0052] As shown in Table 1 below, the ultra-low carbon steel billet grinding method includes a grinding process, a shot blasting process, and a strong light flaw detection process. After the ultra-low carbon steel billet is completed through the grinding process, the billet is shot blasted by a shot blasting machine. First, the shot blasting is performed using steel balls with a particle size of 2.0 mm. The current of the shot blasting machine is 25+2A, and the billet travel speed of the shot blasting machine is controlled at 2.5-3 m / min. The depth of the pit on the billet surface after shot blasting is 0 mm, and the burr removal rate on the billet surface is 88%.

[0053] When the current of the shot blasting machine is 25-2A, the size of the shot blasting steel ball particles is 1.0mm, the pit depth of the steel billet surface after shot blasting is 0mm, and the burr removal rate of the steel billet surface is 80%.

[0054] Table 1

[0055]

[0056] The burr removal rate is calculated by dividing the steel billet surface after shot blasting into equal parts according to a distance of 1 meter. Select the section with the most burrs. Count the sum of the lengths of the burrs within the 1-meter length. Subtract the sum from 1 and divide by 1 meter. For example, if the total length of the burrs within a 1-meter section is 0.15 meters, the burr removal rate is calculated as (1-0.15÷1)*100%=85%.

[0057] Measurement of pit depth on billet surface and burr removal rate after shot blasting:

[0058] ① Use high temperature chalk to mark the steel billet after shot blasting at an equal distance of 1 meter;

[0059] ② The marked steel billet is inspected by a flaw detector. The flaw detector is required to control the billet travel speed at 5-10 cm / s. A light source with a power of ≥80W is used to inspect the billet surface. A vernier caliper is used to count the burr length per meter (the flaw detector is turned off during measurement and is in a stationary state). The minimum surface burr removal rate of the entire billet is used as the measurement indicator of the shot blasting effect.

[0060] ③ Use a depth gauge to measure the depth of the pits on the surface of the steel billet per meter and calculate the fluctuation range.

[0061] In summary, the ultra-low carbon steel billet grinding method provided by the present invention greatly improves the quality of billet grinding by rough grinding and fine grinding, as well as changing the shot blasting machine current and the size of the shot blasting particles. When the shot blasting machine current is 35-2A and the size of the shot blasting steel ball particles is 1.0mm, the pit depth on the billet surface after shot blasting is 0mm, and the burr removal rate on the billet surface is 100%. At this time, the shot blasting effect is the best.

[0062] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for grinding an ultra-low carbon steel billet, comprising a grinding process, a shot blasting process, and a strong light flaw detection process; characterized in that: The grinding process includes a rough grinding process and a fine grinding process; S1-1: The rough grinding is performed by fixing the blank by a caliper on a grinding machine; S1-2: The grinding machine measures the grinding wheel diameter and the workpiece height through a program, sets the roughing depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70m / min, and moves the grinding wheel from one end of the workpiece to the other end according to the set pressure. After reaching the other end, it moves horizontally in a clockwise direction for a certain distance. The horizontal movement distance is less than the single-pass grinding width. Then, the grinding wheel moves in the opposite direction to the original end. This action is repeated until the roughing of one side of the workpiece is completed. S1-3: Open the caliper, turn the blank 45 degrees clockwise by the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the diameter of the grinding wheel, move the grinding wheel from one end of the blank to the other end according to the set pressure, and repeat the action until the pressure reaches the program set value. Then, one chamfering process of the blank is completed. Repeat steps S1-2 and S1-3 until the last chamfering process of the blank is completed; The rough grinding process has a single grinding pass width of ≤1mm, a chamfer width of 14±1mm, a grinding width ≥5-10% of the blank width, and a surface roughness Rz≤60 after grinding; In the finishing process, the finishing depth is set to 0.05 mm, and steps S1-1 to S1-3 are used to complete the blank surface and chamfer finishing process; The single-pass width of the finishing process is ≤0.05mm, the chamfer width is 14±1mm, the grinding width is ≥4-8%mm of the blank width, and the surface roughness after grinding is Rz≤25; The shot blasting current of the shot blasting process is controlled at 35±2A; Among them, the carbon content of ultra-low carbon steel billet and wire rod is ≤0.03%, and the rest is iron and other elements.

2. The method for grinding an ultra-low carbon steel billet according to claim 1, wherein: The grinding process uses a fine grinding wheel for grinding, the grinding wheel particle size is ≥24 mesh, and the abrasive material is zirconium corundum.

3. The method for grinding an ultra-low carbon steel billet according to claim 1, wherein: The shot blasting process uses steel ball shot blasting particles with a particle size of ≤1.0mm.

4. The method for grinding an ultra-low carbon steel billet according to claim 1, wherein: Before the grinding process, the steel billet is confirmed to have a defect depth by using a strong light and a depth gauge, and the defect depth is ≥1.0 mm.

5. The method for grinding an ultra-low carbon steel billet according to claim 1, wherein: The strong light flaw detection process uses a flaw detector to detect flaws on the steel billet after shot blasting. The flaw detector controls the billet travel speed at 5-10 cm / s and uses a light source with a power of ≥80W to inspect the steel billet surface.

6. The method for grinding an ultra-low carbon steel billet according to claim 1, characterized in that: After the roughing process is completed, the surface roughness of the rough-trimmed billet is measured using a roughness instrument. A total of three points are measured, namely, the two ends and the center position of the billet. The arithmetic average of the three points is taken to obtain the surface roughness data of the billet. If the roughness is greater than 60Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

7. The method for grinding an ultra-low carbon steel billet according to claim 1, wherein: After the finishing process is completed, the surface roughness of the finished steel billet is measured using a roughness instrument. A total of three points are measured, namely the two ends and the center position of the billet. The arithmetic average of the three points is taken to obtain the surface roughness data of the steel billet. If the roughness is greater than 25Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

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