A laser butt welding bimetallic steel plate drill and a manufacturing method thereof

Abstract

The present application relates to the technical field of double-metal composite cutter, and belongs to a laser butt-welded double-metal steel plate drill and a manufacturing method thereof.The double-metal composite cutter comprises a cutting section and a handle section made of different materials, and the manufacturing method specifically comprises the following steps: step one, material selection and pretreatment;step two, mechanical processing;step three, cleaning before welding;step four, preheating and clamping before welding;step five, laser butt welding;step six, post-welding treatment;and step seven, ultrasonic detection and appearance magnifying glass inspection of the welding seam quality.The present application is based on the selection of materials and is different from the conventional welding method.The laser butt welding process is adopted in cooperation with the pre-welding treatment and post-welding tempering treatment, so that the width of the heat-affected zone is effectively reduced, and the residual stress and harmful phase change at the interface are eliminated.The welding seam interface is free of cracks and metallurgical defects, and has high bending strength, so that the structural reliability of the double-metal structure is ensured when the double-metal structure bears the axial force and the torsional moment during the drilling process.

Description

Technical Field

[0001] This invention relates to the field of bimetallic composite cutting tool technology, specifically to a laser-welded bimetallic steel plate drill and its manufacturing method. Background Technology

[0002] High-speed steel (HSS) possesses high hardness, high wear resistance, and good red hardness, making it widely used in the manufacture of cutting tools. However, HSS is expensive, typically 5 to 10 times more expensive than ordinary carbon steel. In HSS plate drills, only the front cutting edge requires high hardness and wear resistance, while the rear chip flute and shank primarily bear torque and bending moment, and do not require the superior cutting performance of HSS material. Instead, they require higher toughness, which ordinary carbon steel possesses after quenching. Therefore, using a monolithic HSS plate drill results in significant material waste, poor toughness in the chip flute section, and, for large-sized tools, extremely high overall material costs, leading to high production costs.

[0003] Existing bimetallic butt welding manufacturing technologies include: 1. Brazing: Brazing high-speed steel cutting tips onto ordinary steel substrates results in low weld strength, easy detachment under high torque, and complex process. Furthermore, since the quenching temperature of high-speed steel is much higher than the brazing temperature, it is only used when the material has been quenched before welding. After welding, the hardness of the material decreases significantly. This process has significant limitations and is difficult to mass-produce.

[0004] 2. Friction welding: This involves butt welding high-speed steel bars with ordinary steel bars. It requires larger high-speed steel bars, and the length loss between the two materials is 5-10mm or more. The weld scars require a large amount of subsequent processing, and the cost remains high.

[0005] There are many other material welding technologies that suffer from high costs and poor weld strength. In addition, with the continuous rise in the price of high-speed steel raw materials, it is of great significance to develop a low-cost, high-efficiency, mass-producible, and high-quality bimetallic steel plate drilling technology. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a laser butt welding bimetallic steel plate drill and its manufacturing method, thereby solving the problems of high manufacturing cost of integral high-speed steel round bars, low toughness of chip removal grooves and shanks in high-speed steel plate drills, and unstable quality of existing bimetallic connections.

[0007] To achieve the above objectives, the present invention provides the following technical solution: On one hand, the present invention provides a laser butt welding bimetallic steel plate drill, including a cutting section and a shank section made of different materials. The cutting section is arranged in an annular tubular shape and has a first connecting surface at its rear end. The shank section has a second connecting surface at its front end that is connected to the first connecting surface. The first connecting surface and the second connecting surface are laser butt welded to form an annular weld. The shank section has a tool holder at its rear end.

[0008] Preferably, the first connecting surface is provided with an outer step and an inner step, the length of which is 1~3mm.

[0009] Preferably, the second connecting surface is provided with an outer step two and an inner step two, wherein the outer step two and the inner step one are fitted with a clearance fit, and the clearance is 0.005~0.03mm.

[0010] Preferably, the length of the second inner step is 0.5~2.5mm.

[0011] Preferably, the connection between the second root of the inner step and the second connecting surface is set as an arc connection with an arc radius ≤ 0.4mm.

[0012] Preferably, the first and second connecting surfaces are stepped or conical surfaces that cooperate with each other, which are used for self-centering during welding and to increase mechanical interlocking.

[0013] On the other hand, the present invention also provides a method for manufacturing the above-mentioned laser butt welding bimetallic steel plate drill, comprising the following steps: Step 1: Material selection and pretreatment; Step Two: Machining; Step 3: Cleaning before welding; Step 4: Preheating and clamping before welding; Step 5: Laser welding; Step Six: Post-weld treatment; Step 7: Inspect the weld quality using ultrasonic testing and a magnifying glass.

[0014] Preferably, in step one, the material selection specifically includes: the cutting section is made of high-speed steel, and the shank section is made of ordinary steel.

[0015] Preferably, in step two, the machining specifically includes: machining the cutting section and the shank section to the design dimensions, machining mutually mating steps or conical surfaces on the first connecting surface and the second connecting surface, performing finishing machining on the welding end face to ensure flatness ≤0.02mm and roughness Ra≤1.6μm, and finishing machining the outer step of the first connecting surface of the high-speed steel cutting section and the outer circle of the shank section to the design dimensions.

[0016] Preferably, step three, the pre-welding cleaning, specifically includes: using ultrasonic cleaning combined with plasma cleaning, or gasoline cleaning combined with alcohol wiping the surface to remove oil stains and oxide film from the end face.

[0017] Preferably, in step four, the preheating and clamping before welding specifically includes: placing the cutting section and the shank section to be welded into the furnace for preheating at a temperature of 200~300℃. After the workpiece reaches the above temperature, it is taken out and the cutting section and the shank section are respectively clamped on the rotating chuck and the moving tailstock of the laser welding equipment, with the end face gap ≤0.01mm, and applying axial preload until the fit is visually inspected and there is no gap.

[0018] Preferably, in step five, the laser welding parameters are: laser power 1.5~15kW, welding speed 0.2~2m / min, spot diameter 0.2~1.5mm, and defocusing amount -10~+15mm; The protective gas is argon or helium, with a flow rate of 8–30 L / min, and the gas is discharged from a ring nozzle at 360°. The workpiece rotates at a constant speed and is circumferentially welded along the mating end face, with an overlap of ≥0.5mm between the start and end points.

[0019] Preferably, in step six, the post-weld treatment specifically involves: placing the weld in a furnace at a temperature below 200-300°C for 2-8 hours to relieve stress; and then performing stress-relieving spheroidizing annealing in a furnace at 800-900°C after this process to improve the weld strength.

[0020] Compared with the prior art, the present invention provides a laser butt welding bimetallic steel plate drill and its manufacturing method, which has the following beneficial effects: 1. This invention employs a bimetallic composite structure, using high-performance high-speed steel only in the cutting section that performs the cutting function, while the shank section uses lower-cost ordinary alloy steel. Through the laser butt welding assembly process of this invention, the two materials achieve reliable bonding at the interface, thereby reducing the overall amount of high-speed steel used and lowering the overall material cost.

[0021] 2. Based on material selection, this invention differs from conventional welding methods by employing laser butt welding technology combined with pre-weld treatment and post-weld tempering, effectively reducing the width of the heat-affected zone and eliminating residual stress and harmful phase transformations at the interface. The weld interface is free of cracks and metallurgical defects, exhibiting high bending strength, thus ensuring the structural reliability of the bimetallic structure under axial force and torsional moment during drilling.

[0022] 3. The cutting section of this invention has high hardness after quenching, maintaining high-temperature red hardness and wear resistance comparable to that of the integral high-speed steel drill bit, ensuring drilling accuracy and durability; the shank and cutter body are made of ordinary alloy steel with better toughness, which can effectively absorb energy when subjected to impact loads, reducing the risk of brittle fracture that is prone to occur in the integral high-speed steel structure, making the drilling process safer, and the service life is comparable to that of the integral high-speed steel plate drill bit.

[0023] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2-3 This is a schematic diagram of the welding blank structure of Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the welding blank structure of Embodiment 2 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0026] Example 1 See Figures 1-3 The present invention provides a laser butt welding bimetallic steel plate drill, including a cutting section 1 and a shank section 2 made of different materials. The cutting section 1 is arranged in an annular tube shape and has a first connecting surface 11 at its rear end. The shank section 2 has a second connecting surface 21 at its front end that is connected to the first connecting surface 11. The first connecting surface 11 and the second connecting surface 21 are laser butt welded to form an annular weld. The shank section 2 has a handle 3 at its rear end.

[0027] Preferably, the first connecting surface 11 is provided with an outer step 111 and an inner step 112, the inner step 112 having a length of 1~3mm.

[0028] Preferably, the second connecting surface 21 is provided with an outer step 211 and an inner step 212, wherein the outer step 211 and the inner step 212 are fitted with a clearance of 0.005~0.03mm.

[0029] Preferably, the length of the inner step 212 is 0.5~2.5mm.

[0030] Preferably, the connection between the root of the inner step 212 and the second connecting surface 21 is set as an arc connection with an arc radius ≤ 0.4mm.

[0031] Specifically, the outer radius of the second outer step is the same as the radius of the first outer step.

[0032] Specifically, the first connecting surface 11 and the second connecting surface 21 are mutually mating stepped surfaces or conical surfaces, used for self-centering during welding and to increase mechanical interlocking.

[0033] On the other hand, the present invention also provides a method for manufacturing the above-mentioned laser butt welding bimetallic steel plate drill, comprising the following steps: Step 1: Material selection and pretreatment; Step Two: Machining; Step 3: Cleaning before welding; Step 4: Preheating and clamping before welding; Step 5: Laser welding; Step Six: Post-weld treatment; Step 7: Inspect the weld quality using ultrasonic testing and a magnifying glass.

[0034] Specifically, in step one, the material selection includes: the cutting section material is set to high-speed steel, such as M2, M35, M42 or powder high-speed steel, and the shank section material is set to ordinary steel, such as 42CrMo or materials with equivalent or higher performance.

[0035] Specifically, in step two, the machining includes: machining the cutting section and the shank section to the design dimensions, machining mutually mating steps or conical surfaces on the first connecting surface 11 and the second connecting surface 21, and finishing the welding end face to ensure flatness ≤ 0.02 mm and roughness Ra ≤ 1.6 μm. The outer step of the first connecting surface 11 of the high-speed steel cutting section and the outer circle of the shank section are finished to the design dimensions.

[0036] Specifically, in step three, the pre-welding cleaning includes: using ultrasonic cleaning combined with plasma cleaning, or gasoline cleaning combined with alcohol wiping the surface to remove oil and oxide film from the end face.

[0037] Specifically, in step four, the preheating and clamping before welding includes: placing the cutting section and the shank section to be welded into the furnace for preheating at a temperature of 200~300℃. After the workpiece reaches the above temperature, it is taken out and the cutting section and the shank section are clamped on the rotating chuck and the moving tailstock of the laser welding equipment, respectively, with the end face gap ≤0.01mm, and applying axial preload until the fit is visually inspected and there is no gap.

[0038] Specifically, in step five, the laser welding parameters are: laser power 1.5~15kW, welding speed 0.2~2m / min, spot diameter 0.2~1.5mm, and defocusing amount -10~+15mm; The protective gas is argon or helium, with a flow rate of 8–30 L / min, and the gas is discharged from a ring nozzle at 360°. The workpiece rotates at a constant speed and is circumferentially welded along the mating end face, with an overlap of ≥0.5mm between the start and end points.

[0039] Specifically, in step six, the post-weld treatment is as follows: after welding, the weld is placed in a furnace at a temperature below 200~300℃ for 2~8 hours to relieve stress. After this process, stress-relieving spheroidizing annealing is performed in the furnace at 800~900℃ to improve the weld strength.

[0040] Example 2 See Figure 4 Steel plate drill φ30×50L specifications: outer diameter 30mm, inner diameter 21.5mm, total length 87mm, cutting depth 50mm.

[0041] Cutting section: Material M2 high-speed steel (W6Mo5Cr4V2), outer diameter 32mm, inner diameter 20mm, axial length L1=15mm, the rear end is provided with a first connecting surface 11, the first connecting surface 11 is provided with an outer step 111: d2 dimension φ31.5mm, length 6mm, the first connecting surface 11 inner step 112: d1 dimension φ21.3mm, length L3 is 2mm.

[0042] Handle section: Material H11, outer diameter d3 φ31.5mm, inner diameter φ20mm, axial length L5=75mm. The front end is machined with a second connecting surface 21, step d4 with a diameter of φ21.29mm and a length L2=1.5mm. The step and the end face are rounded, with an arc R1≤0.4.

[0043] Cleaning before welding: Ultrasonic cleaning combined with plasma cleaning is used, and the surface is wiped with alcohol to remove oil stains from the end face of the welding area and the shaft platform.

[0044] Preheating and clamping before welding: Place the workpieces to be welded into the furnace for preheating at 250 degrees Celsius. After the workpieces reach the above temperature, remove them and clamp the high-speed steel cutting section and the shank section onto the rotary chuck and moving tailstock of the laser welding equipment, respectively, ensuring that the end face gap is ≤0.01mm. Apply axial preload until the fit is visually inspected and there is no gap.

[0045] Laser welding: A fiber laser is used with a laser power of 2kW, a welding speed of 0.4m / min, a spot diameter of 0.6mm, and a defocusing amount of -4mm. The shielding gas is argon or helium with a flow rate of 15L / min. The gas is discharged from the annular nozzle at 360°. The workpiece rotates at a uniform speed and circumferential welding is performed along the butt joint face with a starting and ending overlap of 1mm.

[0046] Post-weld treatment: After welding, place the weld in a 260℃ furnace and hold for 3 hours to relieve stress. After this process, perform stress-relieving spheroidizing annealing at 850℃ in the furnace for 24 hours to improve the weld strength.

[0047] Inspection: No welding defects were found using an electronic magnifying glass combined with ultrasonic testing.

[0048] Post-weld machining: After the tool has been processed and quenched, the machining time for the outer cylindrical grinding of the cutting edge is about 2 minutes and 30 seconds (about 3 minutes if it is a solid high-speed steel material), and the machining time for the chip removal groove is about 9 minutes (10 minutes and 30 seconds if it is a solid high-speed steel material).

[0049] Drilling test: After machining, the tool drilled φ30mm holes in a 50mm thick Q355 steel plate. 270 holes were drilled continuously. The cutting teeth were normal, the weld was intact, and there were no cracks in the weld.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser butt welding drill for bimetallic steel plates, characterized in that: It includes a cutting section (1) made of different materials and a shank section (2). The cutting section (1) is arranged in an annular tube shape and has a first connecting surface (11) at its rear end. The shank section (2) has a second connecting surface (21) at its front end that is connected to the first connecting surface (11). The first connecting surface (11) and the second connecting surface (21) are welded by laser welding to form an annular weld. The shank section (2) has a handle section (3) at its rear end.

2. The laser butt welding bimetallic steel plate drill according to claim 1, characterized in that: The first connecting surface (11) is provided with an outer step (111) and an inner step (112), the inner step (112) having a length of 1~3mm.

3. The laser butt welding bimetallic steel plate drill according to claim 2, characterized in that: The second connecting surface (21) is provided with an outer step two (211) and an inner step two (212). The outer step two (211) and the inner step one (112) are fitted with a clearance, and the clearance is 0.005~0.03mm. The length of the inner step two (212) is 0.5~2.5mm; The connection between the root of the inner step two (212) and the second connecting surface (21) is set as an arc connection with an arc radius ≤ 0.4mm.

4. A method for manufacturing a laser butt welding bimetallic steel plate drill according to any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Material selection and pretreatment; Step Two: Machining; Step 3: Cleaning before welding; Step 4: Preheating and clamping before welding; Step 5: Laser welding; Step Six: Post-weld treatment; Step 7: Inspect the weld quality using ultrasonic testing and a magnifying glass.

5. The method for manufacturing a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step one, the material selection specifically includes: the cutting section is made of high-speed steel, and the shank section is made of ordinary steel.

6. The method for manufacturing a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step two, the machining specifically includes: machining the cutting section and the shank section to the design dimensions respectively, machining mutually matching steps or conical surfaces on the first connecting surface (11) and the second connecting surface (21), performing finishing on the welding end face to ensure flatness ≤ 0.02 mm and roughness Ra ≤ 1.6 μm, and finishing the outer step (111) of the first connecting surface (11) of the high-speed steel cutting section and the outer circle of the shank section to the design dimensions.

7. The manufacturing method of a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step three, the pre-welding cleaning specifically includes: using ultrasonic cleaning combined with plasma cleaning, or gasoline cleaning combined with alcohol wiping the surface to remove oil and oxide film from the end face.

8. The method for manufacturing a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step four, the preheating and clamping before welding specifically includes: placing the cutting section and the shank section to be welded into the furnace for preheating at a temperature of 200~300℃. After the workpiece reaches the above temperature, it is taken out and the cutting section and the shank section are respectively clamped on the rotating chuck and the moving tailstock of the laser welding equipment, with the end face clearance ≤0.01 mm, and applying axial preload until the fit is visually inspected and there is no clearance.

9. A method for manufacturing a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step five, the laser welding parameters are: laser power 1.5–15 kW, welding speed 0.2–2 m / min, spot diameter 0.2–1.5 mm, and defocusing amount -10–+15 mm. The protective gas is argon or helium, with a flow rate of 8–30 L / min, and the gas is discharged from a ring nozzle at 360°. The workpiece rotates at a constant speed and is circumferentially welded along the mating end face, with an overlap of ≥0.5 mm between the start and end points.

10. A method for manufacturing a laser butt welding bimetallic steel plate drill according to claim 4, characterized in that: In step six, the post-weld treatment specifically involves: placing the weld in a furnace at a temperature below 200-300°C for 2-8 hours to relieve stress; and then performing stress-relieving spheroidizing annealing in a furnace at 800-900°C to improve the weld strength.

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