A method to improve the impact toughness of lawnmower robot blades

Abstract

This invention provides a method for improving the impact toughness of lawnmower robot blades. The method mainly includes the following steps: preparing a brazing filler metal: the filler metal is NiBSi-Cr3C2 powder, obtained by mechanically mixing NiBSi powder and Cr3C2 powder, with NiBSi powder accounting for 75% of the total mass of the NiBSi-Cr3C2 powder; pretreating the blade substrate, then slowly adding the filler metal to a polyvinyl alcohol aqueous solution and stirring until a paste is obtained; applying the paste to the cutting surface of the blade substrate with a thickness of 0.5 mm, and allowing the coated blade to dry at room temperature for 12-24 hours; then brazing the dried blade using an induction heating device, with the heating temperature controlled at 1000-1150℃; followed by air cooling to room temperature; finally, post-treatment of the blade (heat treatment + quenching + tempering). This invention first applies a coating to the blade substrate using a brazing method, and then performs post-treatment, thereby improving the impact toughness of lawnmower robot blades.

Description

Technical Field

[0001] This invention relates to the field of lawnmower robot blade technology, specifically a method for improving the impact toughness of lawnmower robot blades. Background Technology

[0002] When lawnmower robot blades are used to cut plant stems and leaves, they do not face conditions of impact abrasive wear. In this situation, the cutting surface cannot achieve work hardening, resulting in a slow blade hardening rate and a thin hardened layer, which fails to fully utilize its superior wear resistance. Therefore, an effective solution is needed to address the work hardening problem. Furthermore, during lawnmower robot operations, the blades often encounter impacts from high-hardness objects such as bricks and stones, which exert significant impact forces on the blades. Therefore, the blades must possess high impact toughness.

[0003] To address the issue of insufficient surface work hardening in lawnmower robot blades when cutting plant roots and stems, a coating can be applied to the cutting surface. Brazing achieves a metallurgical bond between the coating and the substrate, significantly improving their adhesion. However, the brazing process requires high-temperature heating of the workpiece to melt the filler metal and bond it to the substrate. Subsequently, during natural air cooling, quenching hardening occurs, leading to brittleness of the substrate and reduced impact toughness. Furthermore, during air cooling, network carbides may form within the blade, further affecting the substrate's toughness. Therefore, after brazing, heat treatment is crucial to control the microstructure of the blade substrate and improve its impact toughness. Currently, heat treatment technology for lawnmower robot blades after brazing is lacking. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for improving the impact toughness of lawnmower robot blades. First, a coating is applied to the blade substrate using a brazing method, and then the blade undergoes post-processing, thereby improving the impact toughness of the lawnmower robot blades.

[0005] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0006] A method for improving the impact toughness of lawnmower robot blades mainly includes the following steps:

[0007] S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder, wherein the mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder;

[0008] S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains.

[0009] S3. Preparation of paste: Slowly add solder to the polyvinyl alcohol aqueous solution and stir evenly to obtain a paste;

[0010] S4. Paste application: Apply the paste to the cutting surface of the tool substrate to a thickness of 0.5 mm, and let the coated tool dry at room temperature for 12-24 hours.

[0011] S5. Coating generation: The dried cutting tool is brazed using an induction heating device, with the heating temperature controlled between 1000 and 1150°C; then it is air-cooled to room temperature.

[0012] S6. Tool heat treatment: Heat the brazed tool to 950-1050℃ and hold for 60-120 minutes.

[0013] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0014] S8. Tempering: Heat the quenched tool to 420-480℃ for tempering and hold for 40-60 minutes. Then remove it from the furnace and air cool.

[0015] Furthermore, the mass fractions of each element in the NiBSi powder are: B 2%, Si 1.5%, and the balance is Ni.

[0016] Furthermore, in step S3, the mass of polyvinyl alcohol is 2% of the solder mass.

[0017] Furthermore, the material of the tool base is high manganese steel.

[0018] Beneficial effects:

[0019] (1) The present invention forms a NiBSi-Cr3C2 coating on the surface of the cutting tool by brazing, which can significantly enhance the wear resistance and corrosion resistance of the cutting tool.

[0020] (2) After the brazing coating is applied, the impact toughness of the tool is improved by heat treatment, which enables the tool to withstand greater impact loads and is less prone to breakage, thus extending the tool's service life.

[0021] (3) The heat treatment method proposed in this invention is simple, has low manufacturing cost, and is easy to adopt for large-scale production. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method for improving the impact toughness of cutting tools in this invention.

[0023] Figure 2 This is an SEM image of the cutting tool in Example 1. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0025] This invention provides a method for improving the impact toughness of lawnmower robot blades. Please refer to [link / reference]. Figure 1 The main steps include the following:

[0026] S1. Preparation of solder: The solder is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder. The mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder. The mass fraction of each element in NiBSi powder is: B 2%, Si 1.5%, and the balance is Ni.

[0027] S2. Tool substrate pretreatment: Take the tool substrate, which is made of high manganese steel, and grind the surface of the tool substrate with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning on the surface of the tool substrate to remove water-soluble impurities and dirt; then use acetone to perform deep cleaning on the surface of the tool substrate to remove oil stains.

[0028] S3. Preparation of paste: Slowly add the solder to the polyvinyl alcohol aqueous solution and stir evenly to obtain a paste; the mass of polyvinyl alcohol is 2% of the mass of the solder.

[0029] S4. Paste application: Apply the paste to the cutting surface of the tool substrate to a thickness of 0.5 mm, and let the coated tool dry at room temperature for 12-24 hours.

[0030] S5. Coating generation: The dried cutting tool is brazed using an induction heating device, with the heating temperature controlled between 1000 and 1150°C; then it is air-cooled to room temperature.

[0031] S6. Tool heat treatment: Heat the brazed tool to 950-1050℃ and hold for 60-120 minutes.

[0032] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0033] S8. Tempering: Heat the quenched tool to 420-480℃ for tempering and hold for 40-60 minutes. Then remove it from the furnace and air cool.

[0034] Example 1

[0035] A method for improving the impact toughness of lawnmower robot blades mainly includes the following steps:

[0036] S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder. The mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder, and the contents of B and Si are 2% and 1.5%, respectively.

[0037] S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and light dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains.

[0038] S3. Preparation of paste: Slowly add the solder to the polyvinyl alcohol (PVA) aqueous solution and stir with a stirrer for 30 minutes to ensure thorough mixing, thus obtaining a paste; wherein, the mass of polyvinyl alcohol is 2% of the mass of the solder.

[0039] S4. Paste Coating: Apply the paste to the cutting surface of the tool substrate to a thickness of about 0.5 mm, and let the coated tool dry at room temperature for 24 hours.

[0040] S5. Coating generation: The dried cutting tool is brazed with an induction heating device at a temperature of 1050℃ to promote a tight bond between the coating and the substrate. Then it is air-cooled to room temperature.

[0041] S6. Tool heat treatment: Heat the brazed tool to 950℃ and hold for 120 minutes to transform the microstructure of the high manganese steel tool matrix into austenite.

[0042] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0043] S8. Tempering: Heat the quenched tool to 420℃ for tempering and hold for 60 minutes. Then remove it from the furnace and air cool.

[0044] Figure 2The image shown is an SEM image of the tool after heat treatment in this embodiment. As can be seen from the image, the microstructure of the tool matrix after heat treatment is mainly composed of austenite with good impact resistance.

[0045] Example 2

[0046] A method for improving the impact toughness of lawnmower robot blades mainly includes the following steps:

[0047] S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder. The mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder, and the contents of B and Si are 2% and 1.5%, respectively.

[0048] S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and light dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains.

[0049] S3. Preparation of paste: Slowly add the solder to the polyvinyl alcohol (PVA) aqueous solution and stir with a stirrer for 30 minutes to ensure thorough mixing, thus obtaining a paste; wherein, the mass of polyvinyl alcohol is 2% of the mass of the solder.

[0050] S4. Paste Coating: Apply the paste to the cutting surface of the tool substrate to a thickness of about 0.5 mm, and let the coated tool dry at room temperature for 24 hours.

[0051] S5. Coating generation: The dried cutting tool is brazed with an induction heating device at a temperature of 1050℃ to promote a tight bond between the coating and the substrate. Then it is air-cooled to room temperature.

[0052] S6. Tool heat treatment: Heat the brazed tool to 970℃ and hold for 120 minutes to transform the microstructure of the high manganese steel tool matrix into austenite.

[0053] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0054] S8. Tempering: Heat the quenched tool to 420℃ for tempering and hold for 60 minutes. Then remove it from the furnace and air cool.

[0055] Example 3

[0056] A method for improving the impact toughness of lawnmower robot blades mainly includes the following steps:

[0057] S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder. The mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder, and the contents of B and Si are 2% and 1.5%, respectively.

[0058] S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and light dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains.

[0059] S3. Preparation of paste: Slowly add the solder to the polyvinyl alcohol (PVA) aqueous solution and stir with a stirrer for 30 minutes to ensure thorough mixing, thus obtaining a paste; wherein, the mass of polyvinyl alcohol is 2% of the mass of the solder.

[0060] S4. Paste Coating: Apply the paste to the cutting surface of the tool substrate to a thickness of about 0.5 mm, and let the coated tool dry at room temperature for 24 hours.

[0061] S5. Coating generation: The dried cutting tool is brazed with an induction heating device at a temperature of 1050℃ to promote a tight bond between the coating and the substrate. Then it is air-cooled to room temperature.

[0062] S6. Tool heat treatment: Heat the brazed tool to 1000℃ and hold for 120 minutes to transform the microstructure of the high manganese steel tool matrix into austenite.

[0063] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0064] S8. Tempering: Heat the quenched tool to 460℃ for tempering and hold for 60 minutes. Then remove it from the furnace and air cool.

[0065] Example 4

[0066] A method for improving the impact toughness of lawnmower robot blades mainly includes the following steps:

[0067] S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder. The mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder, and the contents of B and Si are 2% and 1.5%, respectively.

[0068] S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and light dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains.

[0069] S3. Preparation of paste: Slowly add the solder to the polyvinyl alcohol (PVA) aqueous solution and stir with a stirrer for 30 minutes to ensure thorough mixing, thus obtaining a paste; wherein, the mass of polyvinyl alcohol is 2% of the mass of the solder.

[0070] S4. Paste Coating: Apply the paste to the cutting surface of the tool substrate to a thickness of about 0.5 mm, and let the coated tool dry at room temperature for 24 hours.

[0071] S5. Coating generation: The dried cutting tool is brazed with an induction heating device at a temperature of 1050℃ to promote a tight bond between the coating and the substrate. Then it is air-cooled to room temperature.

[0072] S6. Tool heat treatment: Heat the brazed tool to 1050℃ and hold for 120 minutes to transform the microstructure of the high manganese steel tool matrix into austenite.

[0073] S7. Cooling: The heat-treated tool is then oil-quenched at room temperature.

[0074] S8. Tempering: Heat the quenched tool to 480℃ for tempering and hold for 60 minutes. Then remove it from the furnace and air cool.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 4 is that steps S6-S8 are not included.

[0077] The cutting tools prepared in Examples 1-4 and Comparative Example 1 were subjected to impact toughness tests, hardness tests, and wear tests. The test results are shown in Table 1.

[0078] Impact toughness test: The cutting tools prepared in Examples 1 to 4 and Comparative Example 1 were subjected to impact tests using an impact testing machine.

[0079] Hardness test: The coating surfaces of Examples 1 to 4 and the cutting edge surface of Comparative Example 1 were tested using a Vickers hardness tester.

[0080] Wear test: Using a friction and wear testing machine, the pin-disc reciprocating wear mode was adopted. The test load was set to 60N and the time was set to 20min. Wear tests were conducted on the coatings of Examples 1 to 4 and Comparative Example 1 to evaluate the wear resistance of the cutting tools.

[0081] Table 1. Test results of the cutting tools prepared in Examples 1-4 and Comparative Example 1.

[0082] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Impact toughness (J) 98 108 113 109 62 Hardness (HV) 791 795 811 804 797 <![CDATA[Wear amount (mm 3 )]]> 0.105 0.102 0.093 0.098 0.097

[0083] (1) The impact toughness of the cutting tools prepared in Examples 1-4 was tested to be approximately 105 J, while the impact toughness of the untreated cutting tools was 62 J. The results show that the impact toughness of the coated cutting tools is significantly improved after the treatment of the present invention.

[0084] (2) Through reciprocating wear of the pin disc, under test conditions of 60N and 20min, the wear amount of the tools in Examples 1-4 is approximately 0.1mm. 3 In Comparative Example 1, the wear of the tool is 0.1 mm. 3 In Examples 1-4, the coated cutting tools maintained their wear resistance and improved their impact toughness after heat treatment, resulting in better application performance.

[0085] (3) The hardness of the tool measured in Examples 1 to 4 is about HV800, while the hardness of the tool coating in the comparative example is HV797. The tool coating still has high hardness after heat treatment, and the cutting ability is guaranteed after heat treatment.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for improving the impact toughness of lawnmower robot blades, characterized in that, The main steps include the following: S1. Preparation of brazing filler metal: The brazing filler metal is NiBSi-Cr3C2 powder, which is obtained by mechanically mixing NiBSi powder and Cr3C2 powder, wherein the mass of NiBSi powder accounts for 75% of the total mass of NiBSi-Cr3C2 powder; S2. Tool substrate pretreatment: Grind the tool substrate surface with sandpaper of grits of 200#, 400#, and 800# respectively; then use alcohol to perform preliminary cleaning of the tool substrate surface to remove water-soluble impurities and dirt; then use acetone to perform deep cleaning of the tool substrate surface to remove oil stains. S3. Preparation of paste: Slowly add solder to the polyvinyl alcohol aqueous solution and stir evenly to obtain a paste; S4. Paste application: Apply the paste to the cutting surface of the tool substrate to a thickness of 0.5 mm, and let the coated tool dry at room temperature for 12-24 hours. S5. Coating generation: The dried cutting tool is brazed using an induction heating device, with the heating temperature controlled at 1000~1150℃; then air-cooled to room temperature. S6. Tool heat treatment: Heat the brazed tool to 950~1050℃ and hold for 60~120min. S7. Cooling: The heat-treated tool is then oil-quenched at room temperature. S8. Tempering: Heat the quenched tool to 420~480℃ for tempering and hold for 40~60 minutes. Then remove it from the furnace and air cool.

2. The method for improving the impact toughness of lawnmower robot blades according to claim 1, characterized in that, The mass fractions of each element in NiBSi powder are: B 2%, Si 1.5%, and the balance is Ni.

3. The method for improving the impact toughness of lawnmower robot blades according to claim 1, characterized in that, In step S3, the mass of polyvinyl alcohol is 2% of the mass of the solder.

4. The method for improving the impact toughness of lawnmower robot blades according to claim 1, characterized in that, The material of the tool base is high manganese steel.

Images