Laser-arc hybrid additive manufacturing method for copper / steel bi-metallic sliding bearing

Abstract

This invention discloses a laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings, specifically implemented according to the following steps: Step 1, substrate pretreatment; Step 2, substrate preheating; Step 3, process parameter setting; Step 4, additive manufacturing. This invention solves the problems of the existing technology, such as the stringent requirements of traditional copper / steel bimetallic arc welding of copper alloys for sliding bearings, the large heat input leading to numerous stress defects, the coarse microstructure of the heat-affected zone, and the low efficiency of laser additive manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings. Background Technology

[0002] Sliding bearings are characterized by high load-bearing capacity, small size, and simple structure, and are widely used in low-speed, heavy-load applications. The structure of sliding bearings can be designed in a modular fashion, making them suitable for higher-capacity wind turbines. Their flexible installation structure makes on-site installation and maintenance possible. The lower production cost and ease of on-site installation and disassembly of sliding bearings can reduce the development and maintenance costs for wind turbine manufacturers.

[0003] Common materials for sliding bearings include gray cast iron, copper-based bearing alloys, and Babbitt alloys. Gray cast iron is suitable for low-speed, light-load, and non-impact conditions. Babbitt alloys have good anti-friction and wear resistance, but their strength is relatively low. Copper-based bearing alloys have good mechanical strength and corrosion resistance, making them suitable for medium-speed, heavy-load, and impact-load conditions.

[0004] As a bearing material, copper alloys need to be combined with steel plates to form copper / steel composite bearings. Currently, common methods for copper / steel composite bearings include interference fit, powder metallurgy, casting, and additive manufacturing. The interference fit method uses an extrusion process to achieve 100% fit between the outer sleeve and inner liner. Patent application number CN02235172.8 and publication number CN2549251Y discloses a bimetallic precision-formed sliding bearing bushing with oil pockets. Its outer sleeve is composed of a steel part and a thin-walled inner liner made of phosphor bronze strip, assembled through interference fit. Its advantages include low processing cost, but low bonding strength and the inability to form a thin-walled alloy layer. Powder metallurgy involves layering copper alloy powder onto the surface of steel, followed by compaction and sintering to form a bimetallic bearing. Patent application CN200910102193.0 and publication CN101649858A disclose a method for manufacturing a powder metallurgy bimetallic sliding bearing, which uses powder metallurgy to prepare a dissimilar alloy layer on the inner wall of a steel sleeve. However, this method often suffers from insufficient compaction density, leading to porosity defects. Furthermore, the sintering process easily produces coarse grains, ultimately affecting the bearing's load-bearing and fatigue performance. Casting, using centrifugal casting or direct casting, composites copper alloys onto the steel substrate surface, resulting in high bonding strength. However, it is prone to defects such as segregation and porosity, and is not suitable for manufacturing thin-walled bimetallic sliding bearings.

[0005] Additive manufacturing is a method of depositing copper alloy materials layer by layer on a steel substrate using heat sources such as electric arcs or lasers. Patent application CN202110127634.3 and publication CN 112935248A discloses a bimetallic sliding bearing and its preparation method. This method involves surfacing tin bronze, aluminum bronze, and brass onto the inner or outer surface of a seamless steel sleeve using oxy-acetylene flame welding, argon arc welding, or plasma welding. While these methods produce strong copper alloy layers, they suffer from high heat input, susceptibility to defects, and stringent process requirements. Regarding the joining of dissimilar metals, patent application CN201910198142.6 and publication CN 110253162A disclose a method combining laser additive manufacturing and laser welding for joining dissimilar metal materials. By using a transition metal plate with a gradient of additive elements, dissimilar metal welding is transformed into homogeneous metal welding, effectively solving the welding difficulties caused by the large difference in melting points between dissimilar metals. However, it requires the addition of transition metal materials, making the process relatively complex, and the efficiency of laser additive manufacturing is low. Patent application number CN202010017172.5 and publication number CN111151875A discloses a method for improving the strength of laser-welded copper-steel dissimilar metal joints, effectively combining laser texturing technology with laser welding technology to improve the bonding strength of copper-steel dissimilar metals. However, it requires the use of two lasers for sequential processing, making the process complex and the welding efficiency low. Summary of the Invention

[0006] The purpose of this invention is to provide a laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings, which solves the problems of the traditional sliding bearing copper / steel bimetallic arc welding copper alloy process, which has stringent requirements, large heat input leading to many stress defects, coarse microstructure in the heat-affected zone, and low efficiency of laser additive manufacturing.

[0007] The technical solution adopted in this invention is a laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings, which is implemented according to the following steps:

[0008] Step 1: Substrate pretreatment;

[0009] Step 2: Preheat the substrate;

[0010] Step 3: Setting process parameters;

[0011] Step 4: Additive manufacturing.

[0012] The invention is further characterized in that,

[0013] Step 1 is implemented in the following steps:

[0014] First, the seamless steel sleeve of the processed sliding bearing is fixed on the turntable, and the chuck is used to support the inner wall of the steel sleeve so that the normal of the steel sleeve is parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent.

[0015] Step 2 is implemented in the following steps:

[0016] The substrate is preheated using high-frequency induction heating, and the surface temperature is detected using an infrared thermometer to ensure uniform preheating.

[0017] The preheating temperature in step 2 is 200-250℃.

[0018] Step 3 is implemented in the following steps:

[0019] Step 3.1: Set the relative positions of the laser and the electric arc molten pool:

[0020] The laser beam is positioned in front and the electric arc is behind. The distance between the center of the molten pool and the center of the laser spot is 1-3 mm. An angle is formed between the laser beam and the welding gun. The laser head and the electric arc welding gun are fixed to the robot arm by the welding gun and laser head fixing fixture. The laser head is connected to the laser by an optical fiber. The electric arc welding gun is connected to the electric arc welding machine and the automatic wire feeder.

[0021] Step 3.2: Set the laser heat source parameters:

[0022] The laser focus is set below the surface of the steel substrate, the laser power is set, and the light output mode is continuous constant power light output;

[0023] Step 3.3: Set the arc welding parameters;

[0024] Step 3.4: Set motion parameters

[0025] Set the heat source motion parameters and plan the additive manufacturing path: adopt a full-circle stepped progressive path, that is, after the chuck rotates one circle, the laser source and the arc welding gun are moved along the normal direction by 1 / 2 to 1 / 4 of the single-pass cladding width, and then the next circle of additive manufacturing is carried out. This cycle is repeated until the entire layer of copper alloy is deposited.

[0026] In step 3.1, the angle between the laser beam and the welding torch is 30-60°.

[0027] In step 3.2, the laser focal point is located 0.5 to 2 mm below the substrate surface, with a laser power of 500-1000W and a laser wavelength of 1064nm.

[0028] The arc parameters in step 3.3 are as follows: arc current 90-150A, arc voltage 15-20V, copper alloy welding wire extension 10-15mm, shielding gas 100% argon, gas flow rate 10-25L / min, copper alloy welding wire is solid copper alloy welding wire, and the wire diameter range is 0.8-1.6mm.

[0029] The heat source motion parameters in step 3.4 are set as follows: the welding line speed is 300-500 mm / min, the chuck speed is calculated and set according to the welding line speed and workpiece diameter, the heat source oscillation frequency is 1.0~3.0Hz, the amplitude is 0~8mm, and the additive overlap is 1 / 2~1 / 4 of the single-pass cladding width.

[0030] Step 4 is implemented in the following steps:

[0031] Step 4.1: Under-layer additive welding. Based on the previous three steps, the under-layer additive welding is completed on the sliding bearing steel base workpiece. The copper alloy and the steel base achieve mutual fusion metallurgical bonding to form an under-layer with copper-steel bimetallic fusion layer 2. Finally, the impurities, including welding slag, on the surface of the under-layer copper alloy are cleaned.

[0032] Step 4.2, Layer stack additive welding: On the basis of the base layer, complete the layer stack additive welding of the 2nd to nth layers to obtain the copper alloy layer 1 of the required thickness. Before each layer stack additive welding, the surface of the previous layer, including the weld slag, needs to be cleaned.

[0033] The beneficial effects of this invention are that the laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings utilizes both laser and electric arc as dual heat sources acting on the molten pool, significantly improving cladding efficiency, reducing welding heat input, and thus mitigating grain coarsening, deformation, and residual stress. Compared to traditional processing methods, it offers advantages such as larger process margin, deeper molten pool, formation of a mutually soluble layer between copper and steel, and higher bonding strength. This invention employs a laser-arc composite additive manufacturing method to prepare copper / steel bimetallic sliding bearings, achieving automatic deposition of copper alloy onto the steel body, greatly improving manufacturing efficiency while saving on copper alloy material usage. Furthermore, this laser-arc composite additive method can be used for the rapid repair of localized defects in copper / steel bimetallic sliding bearings, reducing maintenance costs. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the cross-section of the copper-steel bimetallic sliding bearing of the present invention;

[0035] Figure 2 This is a schematic diagram of the laser-arc composite additive manufacturing of the copper-steel bimetallic bearing of the present invention.

[0036] In the figure: 1. Copper alloy layer; 2. Copper-steel bimetallic fusion layer; 3. Seamless steel sleeve of sliding bearing; 4. Fixture for fixing welding torch and laser head; 5. Laser head; 6. Arc welding torch; 7. Laser beam; 8. Copper alloy welding wire; 9. Molten pool. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] To address the challenges of traditional copper / steel bimetallic arc welding processes for sliding bearings, including stringent requirements, high heat input leading to numerous stress defects, coarse microstructure in the heat-affected zone, and low efficiency of laser additive manufacturing, this invention improves the processing technology of copper / steel bimetallic bearings. The principle is as follows: Figure 1 As shown, laser heat source is added to the gas metal arc welding (GMAW) process, forming a laser-arc composite fused wire deposition technology. The principle of this technology is to use both laser and electric arc as dual heat sources acting on the molten pool. The laser guides and stabilizes the arc, while the arc increases the metal's absorption rate of the laser, thus enhancing the deposition process through droplet transfer. Compared to traditional arc welding, laser-arc composite additive manufacturing technology offers advantages such as greater weld pool depth, higher deposition efficiency, lower heat input, and less deformation and residual stress.

[0039] The laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings of the present invention is implemented according to the following steps:

[0040] Step 1: Substrate pretreatment;

[0041] Step 1 is implemented in the following steps:

[0042] First, the seamless steel sleeve 3 of the processed sliding bearing is fixed on the turntable, and the sleeve is supported by the claws to make the normal of the sleeve parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent.

[0043] Step 2: Preheat the substrate;

[0044] Combination Figure 1 , Figure 2 Step 2 is implemented in the following steps:

[0045] The substrate is preheated using high-frequency induction heating, and the surface temperature is detected using an infrared thermometer to ensure uniform preheating.

[0046] The preheating temperature in step 2 is 200-250℃.

[0047] Step 3: Setting process parameters;

[0048] Step 3 is implemented in the following steps:

[0049] Step 3.1: Set the relative positions of the laser and the electric arc molten pool:

[0050] The laser beam 7 is positioned in front and the electric arc is behind. The distance between the center of the molten pool 9 and the center of the laser spot is 1-3mm. An angle is formed between the laser beam 7 and the electric arc welding gun 6. The laser head 5 and the electric arc welding gun 6 are fixed to the robot arm by the welding gun and laser head fixing fixture 4. The laser head 5 is connected to the laser by optical fiber. The electric arc welding gun 6 is connected to the electric arc welding machine and the automatic wire feeder.

[0051] Step 3.2: Set the laser heat source parameters:

[0052] The laser focus is set below the surface of the steel substrate, the laser power is set, and the light output mode is continuous constant power light output;

[0053] Step 3.3: Set the arc welding parameters;

[0054] Step 3.4: Set motion parameters

[0055] Set the heat source motion parameters and plan the additive manufacturing path: adopt a full-circle stepped progressive path, that is, after the chuck (sliding bearing steel base workpiece) rotates one circle (that is, completes one circle of additive manufacturing), the laser source and arc welding gun are moved along the normal direction by 1 / 2 to 1 / 4 of the single-pass cladding width, and then the next circle of additive manufacturing is carried out. This cycle is repeated until the entire layer of copper alloy is deposited.

[0056] In step 3.1, the angle between the laser beam and the welding torch is 30-60°.

[0057] In step 3.2, the laser focal point is located 0.5 to 2 mm below the substrate surface, with a laser power of 500-1000W and a laser wavelength of 1064nm.

[0058] The arc parameters in step 3.3 are as follows: arc current 90-150A, arc voltage 15-20V, copper alloy welding wire 8 dry extension 10-15mm, shielding gas 100% argon, gas flow rate 10-25L / min, copper alloy welding wire 8 is a solid copper alloy welding wire with a diameter range of 0.8-1.6mm.

[0059] The heat source motion parameters in step 3.4 are set as follows: the welding line speed is 300-500 mm / min, the chuck speed is calculated and set according to the welding line speed and workpiece diameter, the heat source oscillation frequency is 1.0~3.0Hz, the amplitude is 0~8mm, and the additive overlap is 1 / 2~1 / 4 of the single-pass cladding width.

[0060] Step 4: Additive manufacturing.

[0061] Step 4 is implemented in the following steps:

[0062] Step 4.1: Under-layer additive welding. Based on the previous three steps, the under-layer additive welding is completed on the sliding bearing steel base workpiece. The copper alloy and the steel base achieve mutual fusion metallurgical bonding to form an under-layer with copper-steel bimetallic fusion layer 2. Finally, the impurities, including welding slag, on the surface of the under-layer copper alloy are cleaned.

[0063] Step 4.2: Layer stacking additive welding. Based on the base layer, complete the layer stacking additive welding for layers 2 to n to obtain the required thickness of copper alloy layer 1. Note that before each layer stacking additive welding, the surface of the previous layer, including weld slag, must be cleaned of impurities.

[0064] This invention relates to a laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings. Based on arc additive manufacturing, a laser heat source is added to form a laser-arc composite fused wire deposition technology. The laser and the arc act as dual heat sources on the molten pool 9. The laser is in front and the arc welding gun is behind. The laser guides and stabilizes the arc, and the arc increases the absorption rate of the metal to the laser, so that the laser and the arc produce a good coupling effect, achieving high-quality and efficient preparation of copper / steel bimetallic sliding bearings.

[0065] Example 1

[0066] A laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings includes the following steps:

[0067] Step 1: Substrate Pretreatment

[0068] First, the 320mm diameter seamless steel sleeve (42CrMoA) of the sliding bearing is fixed on the turntable. The sleeve is supported by claws on the inner wall so that the normal of the sleeve is parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent.

[0069] Step 2: Preheating the substrate

[0070] The substrate is preheated using high-frequency induction heating at a temperature of 200–250°C. An infrared thermometer is used to detect the surface temperature to ensure uniform preheating.

[0071] Step 3: Setting process parameters

[0072] Step 3.1: Set the relative positions of the laser and the electric arc molten pool.

[0073] According to the welding process settings, the laser beam is in front and the electric arc is behind. The distance between the center of the molten pool and the center of the laser spot is 2mm. The angle between the laser beam and the welding gun is 60°. The laser head 5 and the electric arc welding gun 6 are fixed on the robot arm by the welding gun and the laser head fixing fixture 4. The laser head 5 is connected to the laser by optical fiber. The electric arc welding gun 6 is connected to the electric arc welding machine and the automatic wire feeder.

[0074] Step 3.2: Set the laser heat source parameters

[0075] According to the welding process, the laser focus is set below the surface of the steel substrate, specifically about 1mm below the substrate surface. The laser power is set to 800W, the light output mode is continuous constant power output, and the laser wavelength is 1064nm.

[0076] Step 3.3: Set the arc welding parameters

[0077] The arc parameters are set according to the welding process as follows: arc current 120A, arc voltage 18.8V, wire extension 15mm, shielding gas 100% argon, gas flow rate 15L / min, welding wire is copper alloy solid welding wire, and welding wire diameter is 1.2mm.

[0078] Step 3.4: Set motion parameters

[0079] The heat source motion parameters are set according to the welding process, with a welding line speed of 350 mm / min. The chuck rotation speed is set accordingly, the heat source oscillation frequency is 2 Hz, the amplitude is 5 mm, and the additive overlap is half the width of a single cladding pass. The additive manufacturing path is planned in the robot program: a stepped, progressive path is adopted, meaning that after the chuck (sliding bearing steel base workpiece) rotates one revolution (completing one revolution of additive manufacturing), the laser source and arc welding torch move along the normal direction by half the width of a single cladding pass, and then the next revolution of additive manufacturing is performed. This cycle continues until the entire layer of copper alloy is deposited.

[0080] Step 4: Additive Manufacturing

[0081] Based on the first three steps, complete the automatic program setting for additive manufacturing, then start the bottom layer additive welding program to complete additive welding on the sliding bearing steel substrate workpiece, and finally clean the surface of copper alloy and other impurities such as weld slag.

[0082] Example 2

[0083] A laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings includes the following steps:

[0084] Step 1: Substrate Pretreatment

[0085] First, the pre-processed steel sleeve (45 steel) with a diameter of 530mm is fixed on the turntable. The sleeve is supported by chucks on the inner wall of the sleeve so that the normal direction of the sleeve is parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent.

[0086] Step 2: Preheating the substrate

[0087] The substrate is preheated using high-frequency induction heating at a temperature of 200–250°C. An infrared thermometer is used to detect the surface temperature to ensure uniform preheating.

[0088] Step 3: Setting Additive Manufacturing Process Parameters

[0089] Step 3.1: Set the relative positions of the laser and the electric arc molten pool.

[0090] According to the welding process settings, the laser beam is in front and the electric arc is behind. The distance between the center of the molten pool and the center of the laser spot is 1.5mm, and the angle between the laser beam and the welding gun is 30°. The laser head and the electric arc welding gun are both integrated on the same axis of the robot.

[0091] Step 3.2: Set the laser heat source parameters

[0092] The laser focus is set below the surface of the steel substrate, specifically about 1 mm below the substrate surface. The laser power is set to 1000W, the light output mode is continuous constant power output, and the laser wavelength is 1064nm.

[0093] Step 3.3: Set the arc welding parameters

[0094] The arc parameters for the bottom layer are set as follows: arc current 150A, arc voltage 19.5V, wire extension 15mm, shielding gas 100% argon, gas flow rate 20L / min, and the welding wire is a solid copper alloy (CuSn10P1) welding wire with a diameter of 1.2mm.

[0095] The high-level arc parameters are set as follows: arc current 140A, arc voltage 19.7V, wire extension 15mm, shielding gas 100% argon, and gas flow rate 20L / min.

[0096] Step 3.4: Set motion parameters

[0097] The heat source motion parameters are set according to the welding process, with a welding line speed of 400 mm / min. The chuck rotation speed is set accordingly, the heat source oscillation frequency is 2.5 Hz, the amplitude is 6 mm, and the additive overlap is half the width of a single cladding pass. The additive manufacturing path is planned in the robot program: a stepped, progressive path is adopted, meaning that after the chuck (sliding bearing steel base workpiece) rotates one revolution (completing one revolution of additive manufacturing), the laser source and arc welding torch move along the normal direction by half the width of a single cladding pass before proceeding to the next revolution of additive manufacturing. This cycle continues until the entire layer of copper alloy is deposited.

[0098] Step 4: Additive Manufacturing

[0099] Step 4.1: Underlying additive welding. Based on the first three steps, complete the automatic program setting for additive manufacturing, then start the underlying additive welding program to complete the underlying additive welding on the sliding bearing steel base workpiece. Finally, clean the surface of the underlying copper alloy and other impurities such as weld slag.

[0100] Step 4.2, Layer Additive Welding: After completing the automatic program setting for layer additive manufacturing on the basis of the bottom layer, start the layer additive welding program to complete the second layer additive manufacturing on the sliding bearing steel base workpiece. Note that before layer additive welding, the surface of the previous layer needs to be cleaned of welding slag and other impurities.

[0101] Example 3

[0102] A laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings includes the following steps:

[0103] Step 1: Substrate Pretreatment

[0104] First, the 565mm diameter seamless steel sleeve (42CrMoA) of the sliding bearing is fixed on the turntable. The sleeve is supported by claws on the inner wall so that the normal of the sleeve is parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent.

[0105] Step 2: Preheating the substrate

[0106] The substrate is preheated using high-frequency induction heating at a temperature of 200–250°C. An infrared thermometer is used to detect the surface temperature to ensure uniform preheating.

[0107] Step 3: Set the relative positions of the laser and the electric arc molten pool.

[0108] According to the welding process settings, the laser beam is in front and the electric arc is behind. The distance between the center of the molten pool and the center of the laser spot is 2mm, and the angle between the laser beam and the welding gun is 30°. The laser head and the electric arc welding gun are both integrated on the same axis of the robot.

[0109] Step 3: Setting Additive Manufacturing Process Parameters

[0110] Step 3.1: Set the relative positions of the laser and the electric arc molten pool.

[0111] According to the welding process settings, the laser beam is in front and the electric arc is behind. The distance between the center of the molten pool and the center of the laser spot is 1.5mm, and the angle between the laser beam and the welding gun is 30°. The laser head and the electric arc welding gun are both integrated on the same axis of the robot.

[0112] Step 3.2: Set the laser heat source parameters

[0113] The laser focus is set below the surface of the steel substrate, specifically about 0.5 mm below the substrate surface. The laser power is set to 600W, the light output mode is continuous constant power output, and the laser wavelength is 1064nm.

[0114] Step 3.3: Set the arc welding parameters

[0115] The arc parameters for the bottom layer are set as follows: arc current 90A, arc voltage 17.5V, wire extension 13mm, shielding gas 100% argon, gas flow rate 15L / min, and the welding wire is a solid copper alloy (CuSn12Ni2) welding wire with a diameter of 1.2mm.

[0116] The high-level electric arc parameters are set as follows: arc current 90A, arc voltage 17.8V, wire extension 13mm, shielding gas 100% argon, gas flow rate 15L / min, and the welding wire is a copper alloy (CuSn12Ni2) solid welding wire with a diameter of 1.2mm.

[0117] Step 3.4: Set motion parameters

[0118] The heat source motion parameters are set according to the welding process, with a welding line speed of 300 mm / min. The chuck rotation speed is set accordingly, the heat source oscillation frequency is 2.0 Hz, the amplitude is 4 mm, and the additive overlap is half the width of a single cladding pass. The additive manufacturing path is planned in the robot program: a stepped, progressive path is adopted, meaning that after the chuck (sliding bearing steel base workpiece) rotates one revolution (completing one revolution of additive manufacturing), the laser source and arc welding torch move along the normal direction by half the width of a single cladding pass before proceeding to the next revolution of additive manufacturing. This cycle continues until the entire layer of copper alloy is deposited.

[0119] Step 4: Additive Manufacturing

[0120] Step 4.1: Underlying additive welding. Based on the first three steps, complete the automatic program setting for additive manufacturing, then start the underlying additive welding program to complete the underlying additive welding on the sliding bearing steel base workpiece. Finally, clean the surface of the underlying copper alloy and other impurities such as weld slag.

[0121] Step 4.2, Layer Additive Welding: After completing the automatic program setting for layer additive manufacturing on the basis of the bottom layer, start the layer additive welding program to complete the 2nd to 3rd layer additive manufacturing on the sliding bearing steel base workpiece. Note that before layer additive welding, the surface of the previous layer needs to be cleaned of welding slag and other impurities.

Claims

1. A laser-arc composite additive manufacturing method for copper / steel bimetallic sliding bearings, characterized in that, The specific steps are as follows: Step 1: Substrate pretreatment; Step 1 is implemented in the following steps: First, the seamless steel sleeve (3) of the processed sliding bearing is fixed on the turntable, and the chuck is used to support the inner wall of the steel sleeve so that the normal of the steel sleeve is parallel to the horizontal plane. Then, the surface is removed by grinding with a grinding wheel. Finally, the oil and impurities on the surface are cleaned with a cleaning agent. Step 2: Preheat the substrate; Step 2 is implemented in the following steps: The substrate is preheated using high-frequency induction heating, and the surface temperature is detected using an infrared thermometer to ensure uniform preheating. The preheating temperature in step 2 is 200~250℃; Step 3: Setting process parameters; Step 3 is implemented in the following steps: Step 3.1: Set the relative positions of the laser and the electric arc molten pool: The laser beam (7) is positioned in front and the electric arc is positioned behind. The distance between the center of the molten pool (9) and the center of the laser spot is 1-3 mm. An angle is formed between the laser beam (7) and the electric arc welding gun (6). The laser head (5) and the electric arc welding gun (6) are fixed on the robotic arm by the welding gun and laser head fixing fixture (4). The laser head (5) is connected to the laser by an optical fiber. The electric arc welding gun (6) is connected to the electric arc welding machine and the automatic wire feeder. In step 3.1, the angle between the laser beam and the welding torch is 30-60°; Step 3.2: Set the laser heat source parameters: The laser focus is set below the surface of the steel substrate, the laser power is set, and the light output mode is continuous constant power light output; In step 3.2, the specific focal position of the laser is 0.5~2mm downward from the substrate surface, the laser power is 500-1000W, and the laser wavelength is 1064nm. Step 3.3: Set the arc welding parameters; The arc parameters in step 3.3 are as follows: arc current 90-150A, arc voltage 15~20V, copper alloy welding wire (8) dry extension length 10~15mm, shielding gas 100% argon, gas flow rate 10~25 L / min, copper alloy welding wire (8) is a solid copper alloy welding wire, and the diameter range of the welding wire is 0.8~1.6mm; Step 3.4: Set motion parameters Set the heat source motion parameters and plan the additive manufacturing path: adopt a full-circle stepped progressive path, that is, after the chuck rotates one circle, the laser source and the arc welding gun are moved along the normal direction by 1 / 2 to 1 / 4 of the single-pass cladding width, and then the next circle of additive manufacturing is carried out. This cycle is repeated until the entire layer of copper alloy is deposited. The heat source motion parameters in step 3.4 are set as follows: the welding line speed is 300-500mm / min, the chuck speed is calculated and set according to the welding line speed and workpiece diameter, the heat source oscillation frequency is 1.0~3.0Hz, the amplitude is 0~8mm, and the additive overlap is 1 / 2~1 / 4 of the single-pass cladding width. Step 4: Additive manufacturing; Step 4 is implemented in the following steps: Step 4.1: Additive welding of the bottom layer. Based on the previous three steps, additive welding of the bottom layer is completed on the sliding bearing steel base workpiece. The copper alloy and the steel base achieve mutual fusion metallurgical bonding to form a bottom layer with copper-steel bimetallic fusion layer (2). Finally, the impurities, including welding slag, on the surface of the bottom layer copper alloy are cleaned. Step 4.2, stacking layer additive welding: On the basis of the bottom layer, the 2nd to nth layers of stacking layer additive welding are completed to obtain the copper alloy layer of the required thickness (1). Before stacking layer additive welding, the surface of the previous layer of welding layer, including impurities such as welding slag, needs to be cleaned.

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