Ultra-low carbon steel billet grinding method

Abstract

The invention belongs to the technical field of metal coping, and particularly relates to an ultra-low carbon steel billet coping method which comprises a coping procedure, a shot blasting procedure and a strong light flaw detection procedure. The grinding process comprises a rough grinding process and a fine grinding process; according to the method, the defects that in the grinding process of an existing ultra-low carbon steel billet, metal scraps generated by cutting are prone to being attached to one side of a grinding crack to form flanging burrs and surface defects are generated after rolling deformation are overcome, the generation of metal flanging burrs is reduced in the billet grinding process, the burr defects are effectively removed, and meanwhile the grinding quality of the ultra-low carbon steel billet is improved. And the surface quality of the blank is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal grinding, and in particular relates to a method for grinding 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] The surface treatment of steel billets is usually done by grinding with a grinding wheel. During the grinding process, flanging burr defects are prone to occur. This defect is caused by the fact that ultra-low carbon steel is extremely soft and highly viscous. During the grinding process, the metal waste produced by the grinding wheel tends to adhere to the side of the wear mark. If it is not removed cleanly in the later stage, in the subsequent rolling process, the ultra-low carbon steel is heated at a low temperature to avoid local coarse grains and other problems. The burr defect cannot be completely burned off and remains on the surface of the billet, which will produce surface defects after rolling deformation.

[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 grinding process of the existing ultra-low carbon steel billet, the metal waste generated by cutting is easily adhered to one side of the wear mark to form a flange burr defect, and surface defects are generated after rolling deformation. The generation of metal flange burrs is reduced during the grinding process of the steel billet, and the burr defects are effectively removed while the quality of the billet surface is improved.

[0006] In order to achieve the above-mentioned 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; 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 blank height through a program, sets the rough grinding depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70 m / min, moves the grinding wheel from one end of the blank to the other end according to the set pressure, and then moves a certain distance in the clockwise direction to the other end. The lateral movement distance is less than the single-pass grinding width, and then moves the grinding wheel in the opposite direction to the original end, and repeats the action until one side of the blank is roughly repaired; S1-3: Open the caliper, turn the blank 45° clockwise through the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the grinding wheel diameter, move the grinding wheel from one end of the blank to the other end according to the set pressing amount, and reciprocate according to the action until the pressing amount reaches the program setting value, and one chamfering process of the blank is completed, and 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 in the shot blasting process is controlled at 35±2A; Among them, the carbon content of ultra-low carbon steel billet wire rod is ≤0.03%, and the rest is iron and other elements.

[0007] 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.

[0008] Preferably, the shot blasting process uses steel ball shot blasting particles with a particle size of ≤1.0mm.

[0009] Preferably, before the grinding process, the defect depth of the steel billet is confirmed by strong light and a depth gauge, and the defect depth is ≥1.0 mm.

[0010] Preferably, the strong light flaw detection process uses a flaw detector to detect the steel billet after shot blasting, the flaw detector's billet travel speed is controlled at 5-10 cm / s, and a light source with a power of ≥80W is used to inspect the billet surface.

[0011] Preferably, after the rough trimming process is completed, a roughness instrument is used to measure the surface roughness of the rough-trimmed billet. A total of 3 points are measured, namely the two ends and the center position of the billet. The arithmetic mean of the 3 points is taken to obtain the surface roughness data of the billet. If the roughness is greater than 60Rz, steps S1-2 and S1-3 are repeated until the roughness requirements are met.

[0012] Preferably, after the finishing process is completed, a roughness instrument is used to measure the surface roughness of the finished billet. A total of 3 points are measured, namely the two ends and the center of the billet. The arithmetic mean of the 3 points is taken to obtain the surface roughness data of the billet. If the roughness is greater than 25Rz, steps S1-2 and S1-3 are repeated until the roughness requirements are met.

[0013] Beneficial effects of the present invention: 1. The present invention reduces the probability of flanging burr defects during the grinding process through the mutual cooperation of roughing and fine grinding. 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 grinding is completed, the surface roughness is controlled at Rz≤25, which improves the surface smoothness of the billet while eliminating defects.

[0014] 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 and 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

[0015] The following specific implementation methods further illustrate the use of the present invention.

[0016] 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; S1-1: The rough grinding is performed by fixing the blank by a caliper on a grinding machine; The steel billet after flaw detection is transported to the grinding machine frame by a crane, and the frame chain is used to move 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 by a caliper.

[0017] S1-2: The grinding machine measures the grinding wheel diameter and the blank height through a program, sets the rough grinding depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70 m / min, moves the grinding wheel from one end of the blank to the other end according to the set pressure, and then moves a certain distance in the clockwise direction to the other end. The lateral movement distance is less than the single-pass grinding width, and then moves the grinding wheel in the opposite direction to the original end, and repeats the action until one side of the blank is roughly repaired; S1-3: Open the caliper, turn the blank 45° clockwise through the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the grinding wheel diameter, move the grinding wheel from one end of the blank to the other end according to the set pressing amount, and reciprocate according to the action until the pressing amount reaches the program setting value, and one chamfering process of the blank is completed, and 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; The number of grinding wheels required for rough repair should be ≥24. During the rough repair process, the speed of the grinding trolley should be controlled at 60-70 m / min to avoid the problem of surface bluing caused by excessive grinding speed. The rough repair process first fully grinds the surface of the blank, then fully grinds the corners of the blank in a clockwise direction, and then fully grinds the other surfaces and corners of the blank in turn until the last chamfer is completed, and the entire rough repair process is completed.

[0018] In the finishing process, the finishing depth is set to 0.05 mm; 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 grinding wheel mesh number required for fine finishing must be ≥24 meshes. During the fine finishing process, the walking speed of the grinding trolley should be controlled at 50-60 m / s to avoid the problem of surface bluing caused by excessive grinding speed. The fine finishing process first fully grinds the surface of the blank, then fully grinds the corners of the blank in a clockwise direction, and then fully grinds the other surfaces and corners of the blank in turn until the last chamfer is completed, and the entire fine finishing process is completed.

[0019] The shot blasting current in the shot blasting process is controlled at 35±2A; 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.

[0020] Among them, the carbon content of ultra-low carbon steel billet wire rod is ≤0.03%, and the rest is iron and other elements.

[0021] 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.

[0022] Zirconia corundum is used as the main abrasive of the grinding wheel because of its high hardness, good wear resistance, excellent mechanical strength and thermal shock resistance, and can withstand greater pressure and wear while maintaining good cutting performance. At the same time, the abrasive size can be finely controlled, which improves the wear resistance of the grinding wheel while ensuring the surface quality and roughness of the steel billet after grinding.

[0023] The shot blasting process uses steel ball shot blasting particles with a particle size of ≤1.0mm.

[0024] Before the grinding process, the defect depth of the steel billet is confirmed by strong light and depth gauge, and the defect depth is ≥1.0mm.

[0025] Before grinding, the billet is inspected for surface quality by a flaw detector. The speed of the flaw detector is controlled at 5-10cm / s. A light source with a power of ≥80W is used to inspect the billet surface. When defects are found, a depth gauge is used for measurement. When the defect depth is ≥1.0mm, rough repair + fine repair is required; if the defect depth is <1mm, fine repair is directly arranged. Defects refer to abnormal vibration marks, warping, reconnection, pits and other defects on the billet surface.

[0026] The strong light flaw detection process uses a flaw detector to detect flaws on the steel billet after shot blasting. The billet travel speed of the flaw detector is controlled at 5-10cm / s, and a light source with a power of ≥80W is used to check the surface of the steel billet.

[0027] Before inspection, the billet needs to be divided into equal parts at 1-meter intervals. 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.

[0028] After the roughing process is completed, the surface roughness of the rough-repaired billet is measured using a roughness instrument. A total of 3 points are measured, namely the two ends and the center of the billet. The arithmetic mean of the 3 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.

[0029] After the finishing process is completed, the surface roughness of the finished billet is measured using a roughness instrument. A total of three points are measured, namely, the two ends and the center 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 25Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

[0030] The present invention is further described below with reference to the examples. Embodiment 1

[0031] 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 subjected to the grinding process, the billet is shot blasted by a shot blasting machine. First, the shot blasting is performed with steel balls, 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%.

[0032] 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%. Embodiment 2

[0033] 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 subjected to the grinding process, the billet is shot blasted by a shot blasting machine. First, the shot blasting is performed with steel balls, the size of the steel ball particles is 1.0 mm, and the current of the shot blasting machine is 35+2A. 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 0.05-0.15 mm, and the burr removal rate on the billet surface is 100%.

[0034] 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 on the surface of the steel billet after shot blasting is 0mm, and the burr removal rate on the surface of the steel billet is 100%. Embodiment 3

[0035] 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 subjected to the grinding process, the billet is shot blasted by a shot blasting machine. First, the shot blasting is performed with steel balls, the size of the steel ball particles is 2.0 mm, and the current of the shot blasting machine is 25+2A. The billet travel speed of the shot blasting machine is controlled at 2.5-3 m / min. The pit depth on the billet surface after the shot blasting is 0 mm, and the burr removal rate on the billet surface is 88%.

[0036] 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 on the surface of the steel billet after shot blasting is 0mm, and the burr removal rate on the surface of the steel billet is 80%.

[0037] Table 1

[0038] The burr removal rate is calculated by dividing the surface of the steel billet after shot blasting into equal parts according to a distance of 1 meter, selecting the section with the most burrs, and calculating 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 to be (1-0.15÷1)*100%=85%. Measurement of pit depth on billet surface and burr removal rate after shot blasting: ① Use high temperature chalk to mark the steel billet after shot blasting at an equal distance of 1 meter; ② The marked steel billet is inspected by a flaw detector, and the billet travel speed of the flaw detector is required to be controlled at 5-10cm / second. The surface of the steel billet is inspected with a light source with a power of ≥80W, and the length of burrs per meter is counted with a vernier caliper (the flaw detector is turned off during measurement to keep it in a static state). The minimum burr removal rate of the entire steel billet is used as the measure of the shot blasting effect; 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.

[0039] In summary, the ultra-low carbon steel billet grinding method provided by the present invention greatly improves the quality of billet grinding through rough grinding and fine grinding, as well as changing the current of the shot blasting machine and the size of the shot blasting particles. When the current of the shot blasting machine 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 best.

[0040] 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 substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope 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 blank height through a program, sets the rough grinding depth to 0.6-1mm, sets the travel speed of the grinding machine trolley to 60-70 m / min, moves the grinding wheel from one end of the blank to the other end according to the set pressure, and then moves a certain distance in the clockwise direction to the other end. The lateral movement distance is less than the single-pass grinding width, and then moves the grinding wheel in the opposite direction to the original end, and repeats the action until one side of the blank is roughly repaired; S1-3: Open the caliper, turn the blank 45° clockwise through the steel turning robot arm of the grinding machine, clamp the caliper to fix the blank, measure the blank height and the grinding wheel diameter, move the grinding wheel from one end of the blank to the other end according to the set pressing amount, and reciprocate according to the action until the pressing amount reaches the program setting value, and one chamfering process of the blank is completed, and 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 in the shot blasting process is controlled at 35±2A; Among them, the carbon content of ultra-low carbon steel billet 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, characterized in that: 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, characterized in that: 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, characterized in that: Before the grinding process, the defect depth of the steel billet is confirmed by strong light and depth gauge, and the defect depth is ≥1.0mm.

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

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-repaired billet is measured using a roughness instrument. A total of 3 points are measured, namely the two ends and the center of the billet. The arithmetic mean of the 3 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, characterized in that: After the finishing process is completed, the surface roughness of the finished billet is measured using a roughness instrument. A total of three points are measured, namely, the two ends and the center 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 25Rz, repeat steps S1-2 and S1-3 until the roughness requirements are met.

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