A processing method for laser quenching a shear blade

Abstract

The application discloses a processing method of laser quenching and strengthening a shear blade, and specifically comprises the following steps: ①, blank making: alloy steel ingots are made through the processes of electric furnace smelting, external refining, vacuum degassing and electroslag remelting, and then the blank of the shear blade body is forged through the forging process of two upsetting and two drawing; ②, heat treatment: the hardness of the blank is adjusted to HB220-280 through the annealing or normalizing and tempering heat treatment process; ③, coating light-absorbing paint on the blade edge; ④, blade edge laser quenching and strengthening treatment: the blade edge of the shear blade is subjected to laser hardening treatment, the treatment width is 20 mm, the treatment depth is 2 mm, and the hardness after the treatment reaches HRC55-60; and ⑤, finishing processing. In the processing method, the main part of the shear blade is subjected to refining treatment by using alloy structural steel, the blade edge is coated with light-absorbing paint and subjected to laser quenching and strengthening treatment, thus forming the structure of 'hard outside and soft inside' on the same main body, the shear blade can shear various strength steels without the blade edge being broken, and the shear blade has excellent fatigue resistance and long service life.

Description

Technical Field

[0001] This invention relates to a cutting tool for shearing steel plates, and more particularly to a method for strengthening the cutting edge of a cutting tool for shearing steel plates. Background Technology

[0002] Steel mills produce a wide variety of steel plates, varying in size and thickness. To meet the shearing needs of steel mills, shearing blades made of various materials and manufactured using various methods have emerged in the market. With increasing market demands for product quality and the continuous development of the steel industry, steel rolling technology is constantly being updated and upgraded, placing higher demands on shearing blade performance. They not only need excellent comprehensive performance to handle various strengths of steel, but also superior fatigue resistance to ensure dimensional accuracy during continuous production.

[0003] Currently, the materials used for shearing steel plates are mainly hot work die steels such as H13, H13K, and HMB. While these materials can meet the shearing requirements, they also have significant drawbacks, including susceptibility to wear and blunting, short service life, and high cost. Patent ZL201110043665.7 discloses a fixed-length shear blade and its manufacturing method. The weight percentage composition of this blade is: C: 0.75-1.0%, Si: 0.60-1.40%, Mn: 0.20-0.50%, P≤0.02%, S≤0.02%, Cr: 6.5-8.0%, Mo: 2.5-4.0%, V: 1.8-3.5%, with the balance being Fe. By increasing the content of C and the precious metal elements Cr, Mo, and V, the hardness and wear resistance of the steel are improved. However, this increases the cost and makes it prone to forming network and blocky carbides, which are difficult to eliminate in subsequent heat treatment processes. Patent ZL202011302560.4 discloses a method for manufacturing a composite shear blade. It uses half high-alloy steel (C: 1.4-1.6%, Si: ≤0.60%, Mn: ≤0.60%, Cr: 11.0-13.0%, Mo: 0.7-1.2%, V: 0.5-1.1%) and the other half carbon steel 45# steel to form a composite shear blade through forging. This reduces the amount of precious metals by half, saving costs. The composite structure also reduces the brittleness of the shear blade and reduces the risk of breakage. However, its manufacturing process is too complicated and the cost reduction is not significant. Summary of the Invention

[0004] The problem this invention aims to solve is to provide a processing method for laser-hardened shear blades. The main body of the shear blade is made of refined alloy structural steel, while the cutting edge is coated with a light-absorbing coating and then laser-hardened, forming a "rigid on the outside and flexible on the inside" structure on the same main body. This allows it to cut steels of various strengths without chipping, and also exhibits excellent fatigue resistance, extending its service life. Furthermore, the processing method of this invention is simple, low-cost, and environmentally friendly.

[0005] This invention discloses a laser-quenched and strengthened shear blade processing method, the specific steps of which are as follows:

[0006] ① Making blanks: Optimized alloy steel ingots are made through processes such as electric furnace smelting + ladle refining + vacuum degassing + electroslag remelting, and then the blanks of the shear blade body are forged through a two-upsetting and two-drawing forging process.

[0007] ② Heat treatment: The hardness of the blank is adjusted to HB220-280 through annealing or normalizing + tempering heat treatment process;

[0008] ③ Applying light-absorbing coating to the cutting edge: The blank is machined to rough machining dimensions with a surface roughness of Ra6.3, and then a laser light-absorbing coating is applied to the cutting edge.

[0009] ④ Laser hardening treatment of the cutting edge: The cutting edge of the shear blade is laser hardened to a width of 20mm and a depth of 2mm, and the hardness after treatment reaches HRC55-60.

[0010] ⑤ Finishing: Through finishing and grinding processes, the shear blade is machined to the finished size, and the edge finish is ground to Ra0.8.

[0011] In step ①, the specific composition of the shear blade body is: C: 0.40-0.45, Si: 1.10-1.15, Mn: 0.70-0.75, P≤0.01, S≤0.001, Cr: 1.30-1.35, Ni: 0.05-0.08, Mo: 0.70-0.80, V: 0.10-0.20, Ti: 0.01-0.02, Cu: 0.01-0.02, Al: 0.01-0.02, Nb: 0.01-0.02, with the balance being iron.

[0012] In step ②, the annealing process is as follows: the blank is placed in a gas furnace and slowly heated to 800℃-850℃, and held at that temperature for 2 hours to ensure that it is heated fully and evenly. Then, it is cooled in the furnace to below 100℃ before being removed from the furnace. The normalizing + tempering process is as follows: the blank is heated to the normalizing temperature of 860℃-900℃ and then cooled in the air to below 200℃. It is then placed back in the furnace and heated to 350℃-400℃, held at that temperature for 2 hours, and then cooled to room temperature.

[0013] In step ③, the components and weight percentages of the laser light-absorbing coating are: quartz powder: 85%-90%, graphite: 7%-10%, ferromolybdenum: 1%-3%, phenolic resin: 2%, and alcohol as the solvent.

[0014] In step ④: depending on the usage requirements, one or two continuous laser overlapping scans can be performed; the laser power is 1500w-2000w, and the scanning speed is 60mm / min.

[0015] The processing method of this invention is characterized by: the main body of the shear blade being refined from alloy structural steel to homogenize the ferrite structure and reduce the content of harmful elements; its metallographic structure after heat treatment is pearlite + cementite, with a hardness of HB220-280; after the cutting edge is coated with a light-absorbing coating and laser-strengthened, the metallographic structure is hidden acicular martensite + a small amount of retained austenite (e.g., ... Figure 3 As shown), the hardness is HRC55-60; thus forming a "rigid on the outside and flexible on the inside" structure on the same body.

[0016] The advantages of the processing method of this invention are: 1. The external shear blade has high hardness and good wear resistance, and can shear steel of various strengths without the blade chipping. At the same time, the stress generated during the shearing process is absorbed by the flexible inner shear blade body, reducing the impact force on the shear blade and reducing its brittleness, giving the shear blade excellent fatigue resistance. 2. Good wear resistance and the excellent fatigue resistance generated by the flexible inner and outer steel structure ensure the dimensional accuracy of steel plate shearing during continuous production. 3. The main body is made of alloy structural steel, which greatly reduces the amount of precious metals used, and the process is simple, low-cost, and environmentally friendly. Attached Figure Description

[0017] Figure 1 This is a top view of the shear blade of the present invention;

[0018] Figure 2 This is a front view of the shear blade of the present invention;

[0019] Figure 3 This is a metallographic diagram (500X) of the laser-hardened layer of the present invention. Detailed Implementation

[0020] The manufacturing method of the present invention will be further described in detail below with reference to specific embodiments. The above embodiments are only for describing preferred embodiments of the present invention, and are intended to enable people to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent transformations or modifications made based on the spirit and essence of the main technical solution of the present invention should be covered within the scope of protection of the present invention.

[0021] The shear blade in the processing method of this invention is a disc shear blade, the shape of which is shown in the attached figure. Figure 1, 2 As shown.

[0022] Example 1

[0023] A method for manufacturing laser-hardened shear blades:

[0024] Step ①: Making the main blank of the disc shear blade: An optimized alloy steel ingot is made through processes such as electric furnace smelting + ladle refining + vacuum degassing + electroslag remelting. Its specific composition is C: 0.40, Si: 1.10, Mn: 0.70, P≤0.01, S≤0.001, Cr: 1.30, Ni: 0.05, Mo: 0.70, V: 0.10, Ti: 0.01, Cu: 0.01, Al: 0.01, Nb: 0.01, with the balance being iron. Then, the steel ingot is cut and forged into a disc shear blade blank through two upsetting and two drawing processes.

[0025] Step 2, Heat treatment of the main blank of the disc shear blade: Place the main blank of the disc shear blade in a gas furnace and slowly heat it to 850°C, and keep it at that temperature for 2 hours to ensure that it is heated fully and evenly. Then, cool it with the furnace to below 100°C and remove it from the furnace. The hardness of the disc shear blade blank is HB220.

[0026] Step 3: Coating the cutting edge of the disc shear with light-absorbing coating: The heat-treated blank is machined to a surface roughness of Ra6.3, and then the cutting edge is coated with laser light-absorbing coating. The composition and weight percentage of the coating are: quartz powder: 85%, graphite: 10%, ferromolybdenum: 3%, phenolic resin: 2%, and alcohol as solvent.

[0027] Step 4: Laser hardening and strengthening treatment of the disc shear blade edge: The shear blade edge is subjected to laser hardening treatment with a treatment width of 20mm and a depth of 2mm. One continuous laser overlapping scan is performed with a laser power of 1500w and a scanning speed of 60mm / min. The hardness after treatment can reach HRC55.

[0028] Step 5: Finishing the disc shear blade: The shear blade is finished and ground to the finished size and surface finish Ra0.8 through finishing and grinding.

[0029] Clean the qualified disc shears, oil the surface, package them, and put them into storage.

[0030] Example 2

[0031] A method for manufacturing laser-hardened shear blades:

[0032] Step ①: Making the blank: Optimized alloy steel ingots are produced through processes such as electric furnace smelting + ladle refining + vacuum degassing + electroslag remelting. The specific composition is C: 0.42, Si: 1.12, Mn: 0.73, P≤0.01, S≤0.001, Cr: 1.33, Ni: 0.06, Mo: 0.75, V: 0.15, Ti: 0.01, Cu: 0.01, Al: 0.01, Nb: 0.01, with the balance being iron. The steel ingots are then cut and forged into a disc shear blade blank through two upsetting and two drawing processes.

[0033] Step 2, Heat treatment: Place the disc shear blank in a gas furnace and slowly heat it to 800℃, and keep it at that temperature for 2 hours to ensure that it is heated fully and evenly. Then, cool it in the furnace to below 100℃ and remove it from the furnace. The hardness of the disc blank is HB240.

[0034] Step 3: Applying light-absorbing coating to the cutting edge: The heat-treated blank is machined to a surface roughness of Ra6.3. Then, a laser light-absorbing coating is applied to the cutting edge. The composition and weight percentage of the coating are: quartz: 87%, graphite: 9%, ferromolybdenum: 2%, phenolic resin: 2%, and alcohol as solvent.

[0035] Step 4: Laser hardening treatment of the cutting edge: The cutting edge of the shear blade is laser-hardened with a treatment width of 20mm and a depth of 2mm. A single continuous laser overlapping scan is performed with a laser power of 1800w and a scanning speed of 60mm / min. The hardness after treatment can reach HRC57.

[0036] Step 5, finishing: The shear blade is finished and ground to the finished size and surface finish Ra0.8 through finishing and grinding.

[0037] Clean the qualified disc shears, oil the surface, package them, and put them into storage.

[0038] Example 3

[0039] Step 1: Making the main blank of the disc shear blade: An optimized alloy steel ingot is made through processes such as electric furnace smelting + ladle refining + vacuum degassing + electroslag remelting. Its specific composition is C: 0.45, Si: 1.15, Mn: 0.75, P≤0.01, S≤0.001, Cr: 1.35, Ni: 0.08, Mo: 0.80, V: 0.20, Ti: 0.02, Cu: 0.02, Al: 0.02, Nb: 0.02, with the balance being iron. Then, the steel ingot is cut and forged into a disc shear blade blank through two upsetting and two drawing processes.

[0040] Step 2, Heat treatment of the disc shear blade body blank: Place the disc blank in a gas furnace and slowly heat it to the normalizing temperature of 860℃-900℃, hold it at that temperature for two hours, then remove it from the furnace and cool it in the air until it is below 200℃. Then put it back into the furnace and heat it to 350℃, hold it at that temperature for two hours, and then cool it to room temperature to adjust the hardness of the base part to HB280.

[0041] Step 3: Coating the cutting edge of the disc shear with light-absorbing coating: The heat-treated blank is machined to a surface roughness of Ra6.3, and then the cutting edge is coated with laser light-absorbing coating. The composition and weight percentage of the coating are: quartz: 85%, graphite: 10%, ferromolybdenum: 3%, phenolic resin: 2%, and alcohol as solvent.

[0042] Step 4: Laser hardening and strengthening treatment of the disc shear blade edge: The shear blade edge is laser-hardened with a treatment width of 20mm and a depth of 2mm, using a two-stage continuous laser overlapping scan. The laser power used is 2000W, and the scanning speed is 60mm / min. The hardness after treatment can reach HRC60.

[0043] Step 5, finishing: The shear blade is finished and ground to the finished size and surface finish Ra0.8 through finishing and grinding.

[0044] Clean the qualified disc shears, oil the surface, package them, and put them into storage.

[0045] The processing method of this invention is characterized by: the main body of the shear blade being refined from alloy structural steel to homogenize the ferrite structure and reduce the content of harmful elements; its metallographic structure after heat treatment is pearlite + cementite, with a hardness of HB220-280; after the cutting edge is coated with a light-absorbing coating and subjected to laser quenching and strengthening treatment, the metallographic structure is hidden acicular martensite + a small amount of retained austenite (such as... Figure 3 As shown in the image, the hardness is HRC55-60, thus forming a "rigid on the outside and flexible on the inside" structure on the same body. Laser hardening technology utilizes a focused laser beam to rapidly heat the surface of the steel, causing a martensitic phase transformation and forming a hardened layer. Laser hardening has a high heating phase transformation rate and fast cooling speed, requiring no additional cooling medium, making it a green and environmentally friendly hardening process. It can effectively solve the problem of current scissor blades requiring large amounts of precious metals and complex processes.

[0046] The advantages of the processing method of this invention are: 1. The external shear blade has high hardness and good wear resistance, and can shear steel of various strengths without the blade chipping. At the same time, the stress generated during the shearing process is absorbed by the flexible inner shear blade body, reducing the impact force on the shear blade and reducing its brittleness, giving the shear blade excellent fatigue resistance. 2. Good wear resistance and the excellent fatigue resistance generated by the flexible inner and outer steel structure ensure the dimensional accuracy of steel plate shearing during continuous production. 3. The main body is made of alloy structural steel, which greatly reduces the amount of precious metals used, thereby saving costs and being environmentally friendly.

[0047] Therefore, the processing method of this invention strengthens the cutting edge of the shear blade, which is mainly composed of alloy structural steel, through laser quenching, resulting in a strengthened shear blade that meets production requirements and significantly extends its service life. This processing method is not only simple, low-cost, and environmentally friendly, but it also overcomes the harsh working conditions of continuous impact from steel plates of varying hardness during shearing, meeting the ever-increasing production demands of steel mills.

Claims

1. A method for processing laser-hardened shear blades, comprising the following steps: ① Blank Production: Optimized alloy steel ingots are produced through an electric furnace smelting + ladle refining + vacuum degassing + electroslag remelting process. The blank for the shear blade body is then forged using a two-upsetting and two-drawing forging process. ② Heat Treatment: The hardness of the blank is adjusted to HB220-280 through annealing or normalizing + tempering heat treatment. ③ Edge Coating: The blank is machined to rough dimensions with a surface roughness of Ra6.3, and then a laser-absorbing coating is applied to the edge. ④ Laser Hardening Treatment: The shear blade edge is laser-hardened to a width of 20mm and a depth of 2mm, achieving a hardness of HRC55-60. ⑤ Finishing: The shear blade is finished to the final dimensions through finishing and grinding processes, with the edge surface smoothness ground to the desired level. Ra0.8; In step ①, the specific composition of the shear blade body is C: 0.40-0.45, Si: 1.10-1.15, Mn: 0.70-0.75, P≤0.01, S≤0.001, Cr: 1.30-1.35, Ni: 0.05-0.08, Mo: 0.70-0.80, V: 0.10-0.20, Ti: 0.01-0.02, Cu: 0.01-0.02, Al: 0.01-0.02, Nb: 0.01-0.02, with the balance being iron; In step ③, the composition and weight percentage of the laser light-absorbing coating are: quartz powder: 85%-90%, graphite: 7%-10%; ferromolybdenum: 1%-3%, phenolic resin: 2%, and the solvent is alcohol.

2. The method according to claim 1, characterized in that: In step ②, the annealing process is as follows: the blank is placed in a gas furnace and slowly heated to 800℃-850℃, and held at that temperature for 2 hours to ensure that it is heated fully and evenly. Then, it is cooled in the furnace to below 100℃ and removed from the furnace. The normalizing + tempering process is as follows: the blank is heated to the normalizing temperature of 860℃-900℃ and then cooled in the air to below 200℃. It is then placed back in the furnace and heated to 350℃-400℃, held at that temperature for 2 hours, and then cooled to room temperature.

3. The method according to claim 1, characterized in that: in step ④: one or two continuous laser overlapping scans are performed according to the usage requirements; the laser power is 1500w-2000w, and the scanning speed is 60mm / min.

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