A composite coating process for crane bearing surface electrospark deposition

Abstract

The present invention discloses a process for electrospark deposition of a composite coating on the surface of a crane bearing. The process comprises the following steps: sanding the crane bearing and electrode with sandpaper until the surface roughness of the crane bearing and electrode is no greater than 2 μm; ultrasonically cleaning the crane bearing and electrode in anhydrous ethanol at room temperature to remove surface grease and impurities, and then drying them at room temperature; electrospark deposition of a transition coating on the crane bearing using a silver electrode; and electrospark deposition of a surface coating on the crane bearing using a B83 electrode. The present invention utilizes an electrospark deposition process to deposit a composite coating of silver and B83 on the surface of the crane bearing. The crane bearing after composite coating deposition exhibits low friction, strong load-bearing capacity, excellent stability, and high reliability.

Description

Technical Field

[0001] The invention relates to an electrospark deposition composite coating technology, and is particularly suitable for use on crane bearing bushes, and specifically relates to an electrospark deposition composite coating process for the surface of a crane bearing bush. Background Art

[0002] The sliding bearing bushes on existing cranes are made of cast iron, babbitt alloy or bronze, which are widely used in existing crane sliding bearings. However, their disadvantages are that cast iron bushes have relatively large friction, and the bushes and shaft diameter are very easy to wear; babbitt alloy bushes are expensive and have poor fatigue resistance, especially when the bearing temperature rises, the load-bearing capacity deteriorates; bronze bushes have slightly larger friction and sometimes damage the shaft diameter. Summary of the Invention

[0003] The purpose of the present invention is to design a crane sliding bearing bushing with low friction, high load-bearing capacity, good stability and high reliability.

[0004] To achieve the above object, the technical solution adopted by the present invention is a process for electrospark deposition composite coating on the surface of a crane bearing, comprising the following steps:

[0005] Step 1: polish the crane bearing and electrode with sandpaper until the surface roughness of the crane bearing and electrode is no more than 2 μm; Step 2: ultrasonically clean the crane bearing and electrode in anhydrous ethanol at room temperature for 15 minutes to remove grease and impurities on the surface, and then blow dry them with a hair dryer at room temperature;

[0006] Step 3: Using a silver electrode to perform electrospark deposition to form a transition coating on the crane bearing;

[0007] Step 4: Use B83 electrode to perform electrospark deposition to form the surface coating of the crane bearing.

[0008] Preferably, the electrodes in step 1 include silver electrodes and B83 electrodes.

[0009] Preferably, in step 3, the voltage of the silver electrode during electrospark deposition is 40-60V, the duty cycle is 30%-40%, the discharge frequency is 300Hz-400Hz, the electrode speed is 400r / min-600r / min, and the working efficiency is 1min / cm 2 -2min / cm 2 .

[0010] Preferably, in step 4, when the B83 electrode is subjected to electrospark deposition, the discharge voltage is 20-30V, the duty cycle is 20%-30%, the discharge frequency is 400Hz-500Hz, the electrode speed is 600r / min-800r / min, and the working efficiency is 2min / cm 2-3min / cm 2 .

[0011] Preferably, the movement speed of the silver electrode and the B83 electrode in steps three and four is 3 mm / s, and they move along a broken line trajectory while ensuring uniform pressure. The swing amplitude is 10 mm and deposition is performed at room temperature. Argon (Ar99%) with a flow rate of 15 L / min is used for atmosphere protection, and the angle between the rotating electrode and the bearing surface is maintained at 40 to 60 degrees.

[0012] Preferably, the copper content in the crane bearing material is 89.10%, the tin content is 9.38%, the phosphorus content is 0.72%, and the impurity content is 0.80%; the silver content in the silver electrode is 99.99%, the impurity content is 0.01%, and the diameter of the silver electrode is 3 mm and the length is 100 mm; the copper content in the B83 electrode is 5.83%, the tin content is 83.10%, the antimony content is 11.02%, and the impurity content is 0.05%, and the diameter of the B83 electrode is 3 mm and the length is 100 mm.

[0013] Preferably, when sandpaper is used to polish the crane bearing bush and the electrode, 400#, 600#, 800#, 1000# and 1200# sandpaper are used to polish the crane bearing bush and the electrode in sequence.

[0014] The beneficial effects of the present invention are: adopting a safe and environmentally friendly new technology of electrospark deposition composite coating to achieve the advantages of small friction, strong load-bearing capacity, good stability, high reliability and the like of the crane sliding bearing bush. DETAILED DESCRIPTION

[0015] Example 1

[0016] A crane bearing surface electrospark deposition composite coating process comprises the following steps:

[0017] Step 1: Design the bearing shell dimensions, bearing shell inner diameter, length, and clearance according to the actual operating conditions of the crane;

[0018] Step 2: After rough machining of the crane bearing blank, the inner hole is turned on a lathe with a 0.5mm machining allowance. Before turning, tools, gauges, and fixtures should be cleaned with alkali to remove oil stains. No lubricant or coolant should be added during the turning process. The inner surface of the bearing after low-speed machining should not come into contact with other objects.

[0019] Step 3: Use 400#, 600#, 800#, 1000#, and 1200# sandpaper to polish the crane bearing and electrode in sequence until the surface roughness is no more than 2μm; after polishing, ultrasonically clean the crane bearing and electrode in anhydrous ethanol at room temperature for 15 minutes to remove grease and impurities on the surface, and then blow dry them with a hair dryer at room temperature;

[0020] Step 4: Before electrospark deposition of the coating, clamp the crane bearing with a bench and install the electrode material to be deposited on the welding gun; connect the power supply and argon gas to the electrospark deposition equipment, firmly connect the cathode power supply to the bench, and adjust the argon gas flow to prepare for coating deposition;

[0021] Step 5: Use silver anti-friction electrode material to form a transition coating for the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 60V, duty cycle 30%, discharge frequency 300Hz, electrode speed 400r / min, and working efficiency 1min / cm 2 ;

[0022] Step 6: Use B83 anti-friction electrode material to form the surface coating of the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 30V, duty cycle 20%, discharge frequency 400Hz, electrode speed 600r / min, working efficiency 3min / cm 2 In step 7, the electrode is moved at a speed of about 3 mm / s in any case, along a broken line trajectory while ensuring uniform pressure, with a swing amplitude of about 10 mm, to ensure the stability of the discharge and the arc stability on the workpiece surface as much as possible, so as to obtain excellent deposited layer quality; deposition is performed using a handheld gun at room temperature, with argon (Ar99%) at a flow rate of 15 L / min for atmosphere protection, to avoid contamination of the deposition area by elements such as oxygen or nitrogen; the angle between the rotating electrode and the bearing surface is 40 degrees;

[0023] In step 8, the anti-friction coating of the crane bearing is scraped, that is, the surface is scraped over the entire width of the bearing at one time.

[0024] In this embodiment, the copper content of the crane bearing material is 89.10%, the tin content is 9.38%, the phosphorus content is 0.72%, and the impurity content is 0.80%; the silver content of the silver electrode is 99.99%, the impurity content is 0.01%, and the silver electrode has a diameter of 3 mm and a length of 100 mm; the copper content of the B83 electrode is 5.83%, the tin content is 83.10%, the antimony content is 11.02%, and the impurity content is 0.05%, and the B83 electrode has a diameter of 3 mm and a length of 100 mm.

[0025] Example 2

[0026] A crane bearing surface electrospark deposition composite coating process comprises the following steps:

[0027] Step 1: Design the bearing shell dimensions, bearing shell inner diameter, length, and clearance according to the actual operating conditions of the crane;

[0028] Step 2: After rough machining of the crane bearing blank, the inner hole is turned on a lathe with a 0.5mm machining allowance. Before turning, tools, gauges, and fixtures should be cleaned with alkali to remove oil stains. No lubricant or coolant should be added during the turning process. The inner surface of the bearing after low-speed machining should not come into contact with other objects.

[0029] Step 3: Use 400#, 600#, 800#, 1000#, and 1200# sandpaper to polish the crane bearing and electrode in sequence until the surface roughness is no more than 2μm; after polishing, ultrasonically clean the crane bearing and electrode in anhydrous ethanol at room temperature for 15 minutes to remove grease and impurities on the surface, and then blow dry them with a hair dryer at room temperature;

[0030] Step 4: Before electrospark deposition of the coating, clamp the crane bearing with a bench and install the electrode material to be deposited on the welding gun; connect the power supply and argon gas to the electrospark deposition equipment, firmly connect the cathode power supply to the bench, and adjust the argon gas flow to prepare for coating deposition;

[0031] Step 5: Use silver anti-friction electrode material to form a transition coating for the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 50V, duty cycle 35%, discharge frequency 350Hz, electrode speed 500r / min, and working efficiency 1.5min / cm 2 ;

[0032] Step 6: Use B83 anti-friction electrode material to form the surface coating of the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 25V, duty cycle 25%, discharge frequency 450Hz, electrode speed 700r / min, and working efficiency 2.5min / cm 2 In step 7, the electrode is moved at a speed of approximately 3 mm / s under all circumstances, following a broken-line trajectory while ensuring uniform pressure, with a swing amplitude of approximately 10 mm, to ensure discharge stability and arc stability on the workpiece surface as much as possible, so as to obtain excellent deposited layer quality; deposition is performed using a handheld gun at room temperature, with argon (Ar 99%) at a flow rate of 15 L / min for atmosphere protection, to avoid contamination of the deposition area by elements such as oxygen or nitrogen; the angle between the rotating electrode and the bearing surface is 50 degrees;

[0033] In step 8, the anti-friction coating of the crane bearing is scraped, that is, the surface is scraped over the entire width of the bearing at one time.

[0034] In this embodiment, the copper content of the crane bearing material is 89.10%, the tin content is 9.38%, the phosphorus content is 0.72%, and the impurity content is 0.80%; the silver content of the silver electrode is 99.99%, the impurity content is 0.01%, and the silver electrode has a diameter of 3 mm and a length of 100 mm; the copper content of the B83 electrode is 5.83%, the tin content is 83.10%, the antimony content is 11.02%, and the impurity content is 0.05%, and the B83 electrode has a diameter of 3 mm and a length of 100 mm.

[0035] Example 3

[0036] A crane bearing surface electrospark deposition composite coating process comprises the following steps:

[0037] Step 1: Design the bearing shell dimensions, bearing shell inner diameter, length, and clearance according to the actual operating conditions of the crane;

[0038] Step 2: After rough machining of the crane bearing blank, the inner hole is turned on a lathe with a 0.5mm machining allowance. Before turning, tools, gauges, and fixtures should be cleaned with alkali to remove oil stains. No lubricant or coolant should be added during the turning process. The inner surface of the bearing after low-speed machining should not come into contact with other objects.

[0039] Step 3: Use 400#, 600#, 800#, 1000#, and 1200# sandpaper to polish the crane bearing and electrode in sequence, with the surface roughness not exceeding 2μm; after polishing, ultrasonically clean the crane bearing and electrode in anhydrous ethanol at room temperature for 15 minutes to remove grease and impurities on the surface, and then blow dry them with a hair dryer at room temperature;

[0040] Step 4: Before electrospark deposition of the coating, clamp the crane bearing with a bench and install the electrode material to be deposited on the welding gun; connect the power supply and argon gas to the electrospark deposition equipment, firmly connect the cathode power supply to the bench, and adjust the argon gas flow to prepare for coating deposition;

[0041] Step 5: Use silver anti-friction electrode material to form a transition coating for the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 40V, duty cycle 40%, discharge frequency 400Hz, electrode speed 600r / min, and working efficiency 2min / cm 2 ;

[0042] Step 6: Use B83 anti-friction electrode material to form the surface coating of the crane bearing by electrospark deposition; adjust the parameters to discharge voltage 20V, duty cycle 30%, discharge frequency 500Hz, electrode speed 800r / min, and working efficiency 2min / cm 2In step 7, the electrode is moved at a speed of about 3 mm / s under any circumstances, moving along a broken line trajectory while ensuring uniform pressure, with a swing amplitude of about 10 mm, to ensure the stability of the discharge and the arc stability on the workpiece surface as much as possible, so as to obtain excellent deposited layer quality; deposition is carried out using a handheld gun at room temperature, and argon (Ar99%) with a flow rate of 15 L / min is used for atmosphere protection to avoid contamination of the deposition area by elements such as oxygen or nitrogen; the angle between the rotating electrode and the bearing surface is 60 degrees;

[0043] In step 8, the anti-friction coating of the crane bearing is scraped, that is, the surface is scraped over the entire width of the bearing at one time.

[0044] In this embodiment, the copper content of the crane bearing material is 89.10%, the tin content is 9.38%, the phosphorus content is 0.72%, and the impurity content is 0.80%; the silver content of the silver electrode is 99.99%, the impurity content is 0.01%, and the silver electrode has a diameter of 3 mm and a length of 100 mm; the copper content of the B83 electrode is 5.83%, the tin content is 83.10%, the antimony content is 11.02%, and the impurity content is 0.05%, and the B83 electrode has a diameter of 3 mm and a length of 100 mm.

[0045] Comparative Example

[0046] Comparative Example The performance of the crane bearing with the electrospark deposition composite coating in Example 1 was verified by comparing the crane bearing without the electrospark deposition composite coating as the control group. The friction coefficient, operating stability and reliability of the crane bearing were examined through tribological tests and bench tests.

[0047] The thickness of the electrospark deposition composite coating in Example 1 is 80 μm, and the resulting coating has fewer microcracks on the surface, a relatively smooth and dense surface, and good integrity. The composite coating has good metallurgical bonding with the bearing surface, and the deposited structure is dense. Since the electrospark deposition technology rapidly heats and cools the bearing surface, the grains in the deposited layer are very dense, refined, and evenly distributed. The surface friction coefficient of the composite coating tends to be stable after running-in, and the friction coefficient after running-in is about 0.177. The wear mechanism of the silver-B83 composite coating is mainly plastic deformation and abrasive wear. Under the same conditions, the friction coefficient of the crane bearing without electrospark deposition composite coating in the prior art is about 0.324. Research on the tribological properties of the composite coating under dry friction conditions shows that the composite coating prepared by electrospark deposition technology has lower friction resistance. The surface friction coefficient of the crane bearing with the electrospark deposition composite coating is about 54.6% of that of the crane bearing without electrospark deposition composite coating. The wear mechanism of the crane bearing without electrospark deposition composite coating in the prior art is mainly severe plowing wear and fatigue delamination. The ESD composite coating can effectively inhibit fatigue delamination, exhibit plastic deformation, and be accompanied by abrasive wear.

[0048] During installation, the bearings must be cleaned and free of debris to prevent damage to the bearing shells or lubrication system surfaces. During the bearing installation process, strict installation standards must be adhered to, ensuring that the measured dimensions meet the required specifications. Particular attention should be paid to ensuring that the assembly clearance between the journal and the bearing shell meets the required specifications. The crane bearings were bench tested after being filled with lubricant and idled for a total of one hour. Following the idle run, they were loaded for three hours at a load of 100N. Analysis of the load test data showed that the bearings coated with the ESD composite coating operated stably and maintained normal temperatures. After bench testing, the bearing shells showed minimal surface scratches and minimal wear. Overall, the bearing shells operated stably and reliably. In contrast, existing crane bearings without ESD composite coatings exhibited severe wear and minor damage to the journal. The ESD composite coating's operating characteristics are its ability to withstand short-term damage without recurrence under dynamic lubricant conditions and at relatively high temperatures, while maintaining excellent stability and reliability under rated load conditions.

[0049] The invention uses an electrospark deposition process to deposit a silver and B83 composite coating on the surface of a crane bearing. After the composite coating is deposited, the crane bearing has low friction, strong load-bearing capacity, good stability and high reliability.

Claims

1. A crane bearing surface electrospark deposition composite coating process, characterized in that The following steps are involved: Step 1: polishing the crane bearing and electrodes with sandpaper, wherein the electrodes include silver electrodes and B83 electrodes, until the surface roughness of the crane bearing and electrodes is no more than 2 μm; Step 2: Ultrasonic cleaning of the crane bearings and electrodes in anhydrous ethanol at room temperature to remove grease and impurities on the surface, and then drying at room temperature; Step 3: Using a silver electrode to perform electrospark deposition to form a transition coating on the crane bearing; When the silver electrode is electrospark deposited, the voltage is 40-60V, the duty cycle is 30%-40%, the discharge frequency is 300Hz-400Hz, the electrode speed is 400r / min-600r / min, and the working efficiency is 1min / cm 2 -2min / cm 2 ; Step 4: Use B83 electrode to perform electrospark deposition to form the surface coating of the crane bearing. When the B83 electrode performs electrospark deposition, the discharge voltage is 20-30V, the duty cycle is 20%-30%, the discharge frequency is 400Hz-500Hz, the electrode speed is 600r / min-800r / min, and the working efficiency is 2min / cm 2 -3min / cm 2 .

2. The crane bearing surface electrospark deposition composite coating process according to claim 1, characterized in that: In steps three and four, the movement speed of the silver electrode and the B83 electrode is 3 mm / s. They move along a broken line trajectory and ensure uniform pressure. The swing amplitude is 10 mm and deposition is performed at room temperature. Argon gas with a flow rate of 15 L / min is used for atmosphere protection, and the angle between the rotating electrode and the bearing surface is maintained at 40 to 60 degrees.

3. The process for electrospark deposition composite coating on the crane bearing surface according to claim 1, characterized in that: The copper content in the crane bearing material is 89.10%, the tin content is 9.38%, the phosphorus content is 0.72%, and the impurity content is 0.80%; the silver content in the silver electrode is 99.99%, the impurity content is 0.01%, and the diameter of the silver electrode is 3mm and the length is 100mm; the copper content in the B83 electrode is 5.83%, the tin content is 83.10%, the antimony content is 11.02%, and the impurity content is 0.05%, and the diameter of the B83 electrode is 3mm and the length is 100mm.

4. The process for electrospark deposition composite coating on the surface of a crane bearing according to claim 1, characterized in that: When using sandpaper to grind the crane bearings and electrodes, use 400#, 600#, 800#, 1000#, and 1200# sandpaper to grind the crane bearings and electrodes in sequence.

5. The process for electrospark deposition composite coating on the surface of a crane bearing as claimed in claim 1, characterized in that: In step 2, the crane bearing and electrode are ultrasonically cleaned in anhydrous ethanol at room temperature for 15 minutes to remove grease and impurities on the surface, and then blown dry with a hair dryer at room temperature.