Method for improving impact toughness of mowing robot cutter

Abstract

The invention provides a method for improving the impact toughness of a mowing robot cutter, and the method mainly comprises the following steps: preparing brazing filler metal: the brazing filler metal is NiBSi-Cr3C2 powder and is obtained by mechanically mixing NiBSi powder and Cr3C2 powder, and the mass of the NiBSi powder accounts for 75% of the total mass of the NiBSi-Cr3C2 powder; the method comprises the following steps: pretreating a cutter base body, slowly adding brazing filler metal into a polyvinyl alcohol aqueous solution, and uniformly stirring to obtain paste; then the paste is applied to the cutting face of a tool base body, the coating thickness is 0.5 mm, and the coated tool is subjected to standing drying for 12-24 hours under the room temperature condition; then, the dried cutter is subjected to coating braze coating through induction heating equipment, and the heating temperature is controlled to range from 1000 DEG C to 1150 DEG C; then air-cooling to room temperature; and finally, the tool is subjected to post-treatment (heat treatment, quenching and tempering). According to the method, the coating is firstly coated on the cutter base body by adopting a braze coating method, and then the cutter is subjected to post-treatment, so that the impact toughness of the mowing robot cutter can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of robot lawn mower cutters, in particular to a method for improving the impact toughness of robot lawn mower cutters. Background Art

[0002] When the mowing robot's cutter is used to cut the stems and leaves of plants, it does not face impact abrasive wear. In this case, the cutting surface cannot be hardened, resulting in a slow hardening speed of the cutter and a thin hardened layer, which makes it difficult to exert its superior wear resistance. Therefore, an effective solution to the problem of hardening needs to be found. In addition, when the mowing robot is performing weeding operations, the cutter is often impacted by high-hardness objects such as bricks and stones, which exerts a large impact force on the cutter, so the cutter must have a high impact toughness.

[0003] The problem that the surface hardening of the lawn mowing robot tool is not obvious when cutting plant roots and stems can be solved by coating the cutting surface. The brazing coating method can achieve metallurgical bonding between the coating and the substrate, significantly improving the bonding strength between the two. However, the brazing coating process requires the workpiece to be heated at high temperature to cause the brazing material to melt and bond with the substrate. Afterwards, when the tool is naturally cooled in the air, quenching and hardening will occur, causing the substrate to become brittle and the impact toughness to decrease. In addition, during the air cooling process, network carbides may form in the tool, further affecting the toughness of the substrate. Therefore, after the coating is prepared by brazing coating, it is urgent to use a heat treatment method to regulate the organizational structure of the tool substrate to improve its impact toughness. At present, there is still a lack of heat treatment process technology after the lawn mowing robot tool is brazed and coated. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method for improving the impact toughness of a lawn mowing robot tool. First, a coating is applied to the tool substrate by a brazing coating method, and then the tool is post-processed, thereby improving the impact toughness of the lawn mowing robot tool.

[0005] In order to achieve the above object, the specific scheme adopted by the present invention is: A method for improving the impact toughness of a lawn mowing robot cutter mainly comprises the following steps: S1. Prepare solder: the solder 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. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol aqueous solution, stirring evenly, to obtain a paste; S4, paste coating: the paste is coated on the cutting surface of the tool substrate, the coating thickness is 0.5 mm, and the coated tool is left to dry at room temperature for 12-24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1000-1150°C; then air-cooling to room temperature; S6. Tool heat treatment: Heat the brazed tool to 950-1050°C and keep it warm for 60-120 minutes; S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 420-480℃ for tempering, keep it warm for 40-60min, then take it out of the furnace and air cool it.

[0006] Furthermore, in the NiBSi powder, the mass fractions of the elements are: B 2%, Si 1.5%, and the balance Ni.

[0007] Furthermore, in step S3, the mass of the polyvinyl alcohol is 2% of the mass of the solder.

[0008] Furthermore, the tool substrate is made of high manganese steel.

[0009] Beneficial effects:

[0010] (1) The present invention forms a NiBSi-Cr3C2 coating on the surface of the tool by a brazing coating method, which can significantly enhance the wear resistance and corrosion resistance of the tool.

[0011] (2) After the coating is applied, the tool is heat treated to improve its impact toughness, allowing the tool to withstand greater impact loads without breaking, thereby extending the tool's service life.

[0012] (3) The heat treatment method proposed in the present invention is simple, has low manufacturing cost, and is easy to adopt for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a flow chart of the method for improving the impact toughness of cutting tools.

[0014] Figure 2This is the SEM image of the tool in Example 1. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] The present invention provides a method for improving the impact toughness of a lawn mowing robot cutter. Figure 1 , mainly includes the following steps: S1. Prepare solder: the solder 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; the mass fraction of each element in NiBSi powder is: B 2%, Si 1.5%, and the balance is Ni; S2. Pretreatment of tool substrate: Take the tool substrate, which is made of high manganese steel, and grind the surface of the tool substrate with sandpaper of mesh number 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol aqueous solution, stirring evenly, to obtain a paste; the mass of the polyvinyl alcohol is 2% of the mass of the solder; S4, paste coating: the paste is coated on the cutting surface of the tool substrate, the coating thickness is 0.5 mm, and the coated tool is left to dry at room temperature for 12-24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1000-1150°C; then air-cooling to room temperature; S6. Tool heat treatment: Heat the brazed tool to 950-1050°C and keep it warm for 60-120 minutes; S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 420-480℃ for tempering, keep it warm for 40-60min, then take it out of the furnace and air cool it.

[0017] Example 1 A method for improving the impact toughness of a lawn mowing robot cutter mainly comprises the following steps: S1. Prepare solder: the solder 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, and the contents of B and Si are 2% and 1.5% respectively; S2. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and slight dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol (PVA) aqueous solution, and stirring with a stirrer for 30 minutes to ensure sufficient mixing, so as to obtain a paste; wherein the mass of the polyvinyl alcohol is 2% of the mass of the solder; S4, paste coating: applying the paste on the cutting surface of the tool substrate to a thickness of about 0.5 mm, and leaving the coated tool to dry at room temperature for 24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1050°C, so that the coating is closely combined with the substrate, and then air-cooled to room temperature; S6. Tool heat treatment: Heat the brazed tool to 950°C and keep it warm for 120 minutes to convert the structure in the high manganese steel tool matrix into austenite. S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 420℃ for tempering, keep it warm for 60min, then take it out of the furnace and air cool it.

[0018] Figure 2 The figure shows the SEM image of the tool after the treatment in this embodiment. It can be seen from the figure that the structure of the tool matrix after heat treatment is mainly composed of austenite with good impact resistance.

[0019] Example 2 A method for improving the impact toughness of a lawn mowing robot cutter mainly comprises the following steps: S1. Prepare solder: the solder 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, and the contents of B and Si are 2% and 1.5% respectively; S2. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and slight dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol (PVA) aqueous solution, and stirring with a stirrer for 30 minutes to ensure sufficient mixing, so as to obtain a paste; wherein the mass of the polyvinyl alcohol is 2% of the mass of the solder; S4, paste coating: applying the paste on the cutting surface of the tool substrate to a thickness of about 0.5 mm, and leaving the coated tool to dry at room temperature for 24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1050°C, so that the coating is closely combined with the substrate, and then air-cooled to room temperature; S6. Tool heat treatment: Heat the brazed tool to 970°C and keep it warm for 120 minutes to convert the structure in the high manganese steel tool matrix into austenite. S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 420℃ for tempering, keep it warm for 60min, then take it out of the furnace and air cool it.

[0020] Example 3 A method for improving the impact toughness of a lawn mowing robot cutter mainly comprises the following steps: S1. Prepare solder: the solder 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, and the contents of B and Si are 2% and 1.5% respectively; S2. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and slight dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol (PVA) aqueous solution, and stirring with a stirrer for 30 minutes to ensure sufficient mixing, so as to obtain a paste; wherein the mass of the polyvinyl alcohol is 2% of the mass of the solder; S4, paste coating: applying the paste on the cutting surface of the tool substrate to a thickness of about 0.5 mm, and leaving the coated tool to dry at room temperature for 24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1050°C, so that the coating is closely combined with the substrate, and then air-cooled to room temperature; S6. Tool heat treatment: Heat the brazed tool to 1000°C and keep it warm for 120 minutes to convert the structure in the high manganese steel tool matrix into austenite. S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 460℃ for tempering, keep it warm for 60min, then take it out of the furnace and air cool it.

[0021] Example 4 A method for improving the impact toughness of a lawn mowing robot cutter mainly comprises the following steps: S1. Prepare solder: the solder 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, and the contents of B and Si are 2% and 1.5% respectively; S2. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and slight dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol (PVA) aqueous solution, and stirring with a stirrer for 30 minutes to ensure sufficient mixing, so as to obtain a paste; wherein the mass of the polyvinyl alcohol is 2% of the mass of the solder; S4, paste coating: applying the paste on the cutting surface of the tool substrate to a thickness of about 0.5 mm, and leaving the coated tool to dry at room temperature for 24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1050°C, so that the coating is closely combined with the substrate, and then air-cooled to room temperature; S6. Tool heat treatment: Heat the brazed tool to 1050°C and keep it warm for 120 minutes to convert the structure in the high manganese steel tool matrix into austenite. S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 480℃ for tempering, keep it warm for 60min, then take it out of the furnace and air cool it.

[0022] Comparative Example 1

[0023] The difference between Comparative Example 1 and Example 4 is that steps S6-S8 are not included.

[0024] The knives prepared in Examples 1-4 and Comparative Example 1 were subjected to impact toughness test, hardness test and wear test. The test results are shown in Table 1.

[0025] Impact toughness test: The knives prepared in Examples 1 to 4 and Comparative Example 1 were subjected to impact tests using an impact testing machine.

[0026] Hardness test: The hardness of the coating surfaces of Examples 1 to 4 and the blade surface of Comparative Example 1 were tested using a Vickers hardness tester.

[0027] Wear test: using a friction and wear testing machine, adopting a pin-disk reciprocating wear mode, setting the load to 60N and the time to 20min, respectively, the coatings of Examples 1 to 4 and Comparative Example 1 were subjected to wear tests to evaluate the wear resistance of the tool.

[0028] Table 1 Test results of the knives obtained in Examples 1 to 4 and Comparative Example 1 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

[0029] (1) After testing, the impact toughness of the tools prepared in Examples 1 to 4 was about 105 J, and the impact toughness of the tools without heat treatment was 62 J. The results show that after the treatment of the present invention, the impact toughness of the coated tools is significantly improved.

[0030] (2) Through the reciprocating wear of the pin and disk, under the test conditions of 60N and 20min, the wear amount of the cutting tools in Examples 1 to 4 is about 0.1mm 3 , the wear of the tool in Example 1 is 0.1 mm 3 After heat treatment, the wear resistance of the cutting tools coated with the coatings in Examples 1 to 4 is maintained, and the impact toughness is improved, so the cutting tools have better application performance.

[0031] (3) The tool hardness measured in Examples 1 to 4 is about HV800, and the hardness of the tool coating in the comparative example is HV797. The tool coating still has a relatively high hardness after heat treatment, and the cutting ability is guaranteed after heat treatment.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving the impact toughness of a lawn mowing robot tool. It is characterized in that The main steps are as follows: S1. Prepare solder: the solder is NiBSi-Cr 3 C 2 The powder is made of NiBSi powder and Cr 3 C 2 The powder is obtained by mechanical mixing, wherein the mass of NiBSi powder accounts for 1.3% of NiBSi-Cr 3 C 2 75% of the total mass of powder; S2. Pretreatment of the tool substrate: Grind the surface of the tool substrate with sandpaper of mesh size 200#, 400#, and 800# respectively; then use alcohol to preliminarily clean the surface of the tool substrate to remove water-soluble impurities and dirt; then use acetone to deeply clean the surface of the tool substrate to remove oil stains on the surface of the tool substrate; S3, preparing a paste: slowly adding solder to the polyvinyl alcohol aqueous solution, stirring evenly, to obtain a paste; S4, paste coating: the paste is coated on the cutting surface of the tool substrate, the coating thickness is 0.5 mm, and the coated tool is left to dry at room temperature for 12-24 hours; S5, generating coating: using induction heating equipment to braze the dried tool with coating, the heating temperature is controlled at 1000~1150℃; then air-cooling to room temperature; S6. Tool heat treatment: Heat the brazed tool to 950~1050℃ and keep it warm for 60~120min; S7, cooling: quenching the heat-treated tool with oil at room temperature; S8, Tempering: Heat the quenched tool to 420~480℃ for tempering, keep it warm for 40~60min, then take it out of the furnace and air cool it.

2. A method for improving the impact toughness of a lawn mowing robot cutter according to claim 1, It is characterized in that The mass fractions of the elements in NiBSi powder are: B 2%, Si 1.5%, and the balance Ni.

3. A method for improving the impact toughness of a lawn mowing robot cutter according to claim 1, It is characterized in that In step S3, the mass of polyvinyl alcohol is 2% of the mass of the solder.

4. A method for improving the impact toughness of a lawn mowing robot cutter according to claim 1, It is characterized in that The material of the tool substrate is high manganese steel.

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