The present invention relates to the technical field of laser additive manufacturing, and provides a method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools, comprising: stacking a plurality of agricultural machinery cutting tools to be processed, and clamping and constraining them to form a cutting tool stack; placing the cutting tool stack on a substrate, with the first processing surface facing upward as a cladding surface; using multiple passes of additive printing on the first processing surface to print two layers of cladding layers, forming a triangular structure first coating structure, whose thickness gradient varies; turning the cutting tool stack by 90°, with the second processing surface facing upward as a cladding surface; using multiple passes of additive printing on the second processing surface to print one layer of cladding layers, forming a triangular structure second coating structure, whose thickness gradient varies; finally, using a pneumatic impact shovel to impact the gap at the back of the agricultural machinery cutting tool to separate the agricultural machinery cutting tool. The present invention realizes assembly line production through batch clamping, solves the problem of cracking caused by large heat input of the cladding layer prepared by a single tool, and improves production efficiency.

1 .A method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools, characterized in that it includes the following steps:
Stacking a plurality of agricultural machinery cutting tools to be processed, and clamping and constraining them through tooling to form a cutting tool stack; wherein the coating processing surface of each agricultural machinery cutting tool is the long side working surface and the top surface of the cutting tool directly connected to the long side working surface, and by stacking the agricultural machinery cutting tools, the long side working surfaces of the plurality of cutting tools are stacked to form the first processing surface of the cutting tool stack, and the top surfaces of the plurality of cutting tools are stacked to form the second processing surface of the cutting tool stack, and the first processing surface is adjacent to the second processing surface; placing the cutting tool stack on a substrate with the first processing surface facing upward as a cladding surface; planning the cladding trajectory, laser scanning process and powder feeding process on the first processing surface according to the shape of the long side working surface of the agricultural machinery cutting tool, and accordingly performing laser cladding additive in a protective gas environment, and taking the long side working surfaces of the plurality of agricultural machinery cutting tools. Two layers of cladding layers are printed by multi-pass additive method to form a first coating structure of triangular structure with thickness gradient variation; the thicker side of the first coating structure is located at the end face position adjacent to the second processing surface, forming a support structure for preparing the second coating structure on the second processing surface; the stack of cutting tools is flipped 90°, with the second processing surface facing upward as the cladding surface; the cladding trajectory, laser scanning process and powder feeding process on the second processing surface are planned according to the top surface shape of the cutting tool of the agricultural machinery cutting tool, and laser cladding additive is performed under a protective gas environment accordingly, and a layer of cladding layer is printed by multi-pass additive method on the top surface of the cutting tools of multiple agricultural machinery cutting tools to form a second coating structure of triangular structure with thickness gradient variation; the thicker side of the second coating structure is located at the end face position adjacent to the first processing surface; each agricultural machinery cutting tool is separated by impacting the back gap of the agricultural machinery cutting tool with a pneumatic impact shovel.
2. The method for preparing a high-hardness and wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1 is characterized in that during the laser cladding additive process of the first coating structure and the second coating structure, the laser cladding trajectory adopts a reciprocating method.
3. The method for preparing a high-hardness and wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1 is characterized in that during the laser cladding additive process of the first coating structure, each pass of laser cladding sequentially crosses the long side working surface of the agricultural machinery cutting tool, and after completing the processing of the long side working surfaces of all the stacked agricultural machinery cutting tools under this pass, the laser cladding head rotates 180 degrees to perform the next pass of processing, wherein the overlap rate of adjacent passes is 40%-50%.
4. The method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1 or 2, characterized in that during the laser cladding additive process of the second coating structure, each pass of laser cladding sequentially crosses the top surface of the cutting tool of the agricultural machinery cutting tool, and after completing the processing of the top surfaces of all the stacked agricultural machinery cutting tools under this pass, the laser cladding head rotates 180 degrees to perform the next pass of processing, wherein the overlap rate of adjacent passes is 40%-50%.
5. The method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1, characterized in that during the laser cladding additive process of the first coating structure and the second coating structure, the thickness of the cladding layer presents a gradient change trend, thereby forming a triangular structure.
6. The method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 5, characterized in that the gradient change of the thickness of the cladding layer is achieved by controlling the gradient change of the powder feeding amount.
7. The method for preparing high-hardness and wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1, characterized in that in the laser cladding additive process of the first coating structure and the second coating structure, the cladding powder is selected from Ni-based WC composite materials.
8. The method for preparing high-hardness and wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claims 1-7, characterized in that in the first coating structure of the triangular structure, the maximum coating thickness is 3mm, the minimum thickness is 0.15mm, and the length is 50mm; the cladding passes are 20 passes;
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min;
The powder feeding process planning is shown in Table 1, wherein the powder feeding process includes 20 passes of powder feeding, and the powder feeding amount has a continuous gradient change trend.
9. The method for preparing high-hardness and wear-resistant coating by laser cladding of agricultural machinery cutting tools according to claim 1-7 is characterized in that, in the second coating structure of the triangular structure, the maximum coating thickness is 1.5mm, the minimum thickness is 0.15mm, and the length is 25mm; the cladding passes are 10 passes;
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min;
The powder feeding process planning is shown in Table 2, wherein the powder feeding process includes 10 passes of powder feeding, and the powder feeding amount has a continuous gradient change trend.
10. A high-hardness and wear-resistant coating structure on the surface of an agricultural machinery cutting tool prepared according to the method described in any one of claims 1-9.

Background technology
Agricultural machinery cutting tools are the top priority of modern agricultural development. The development of agricultural machinery cutting tools is a powerful driving force for the advancement of agricultural machinery and the primary task of improving agricultural development. At present, both at home and abroad, efforts are being made to research and apply new technologies and processes to improve agricultural machinery cutting tools. Mower blades, agricultural deep loosening shovels, plowshares, rotary tiller blades, micro-tillage machine knives, agricultural harvester knives, etc. in agricultural machinery are exposed to soil, sand, gravel and debris for a long time. The main failure form of agricultural machinery cutting tools is wear. At present, surfacing technology is the most commonly used technology to improve the wear resistance of agricultural machinery cutting tools at this stage, but it has problems such as large heat-affected zone and easy deformation of workpieces. Therefore, it is picky about the thickness and surface shape of agricultural machinery parts, especially for the processing modification of slightly flat cutting tools, which is easy to cause deformation and internal cracking due to thermal stress.

Invention content
The purpose of the present invention is to propose a simple and efficient method for preparing a high-hardness and wear-resistant cladding layer by laser cladding of agricultural machinery cutting tools, which can realize automated industrial production, high cladding forming accuracy, high surface flatness of the cladding layer, meet the use requirements without post-processing, reduce production costs and shorten processing cycles, and provide a processing solution for solving the production problems of high-performance agricultural machinery cutting tools with low cost and high efficiency.
According to the first aspect of the present invention, a method for preparing a high-hardness wear-resistant coating by laser cladding of agricultural machinery cutting tools is proposed, comprising the following steps:
Stacking a plurality of agricultural machinery cutting tools to be processed, and clamping and constraining them through tooling to form a cutting tool stack; wherein the coating processing surface of each agricultural machinery cutting tool is the long side working surface and the top surface of the cutting tool directly connected to the long side working surface, and by stacking the agricultural machinery cutting tools, the long side working surfaces of the plurality of cutting tools are stacked to form the first processing surface of the cutting tool stack, and the top surfaces of the plurality of cutting tools are stacked to form the second processing surface of the cutting tool stack, and the first processing surface is adjacent to the second processing surface;
Placing the cutting tool stack on a substrate with the first processing surface facing upward as a cladding surface;
Planning the cladding trajectory, laser scanning process and powder feeding process on the first processing surface according to the shape of the long side working surface of the agricultural machinery cutting tool, and accordingly performing laser cladding additive in a protective gas environment, The surface is printed with two layers of cladding layers by multi-pass additive method to form a first coating structure of a triangular structure with a thickness gradient change; the thicker side of the first coating structure is located at the end face position adjacent to the second processing surface, forming a support structure for preparing the second coating structure on the second processing surface;
The stack of cutting tools is flipped 90°, with the second processing surface facing upward as the cladding surface;
The cladding trajectory, laser scanning process and powder feeding process on the second processing surface are planned according to the top surface shape of the cutting tool of the agricultural machinery cutting tool, and laser cladding additive is performed under a protective gas environment accordingly, and a layer of cladding layer is printed on the top surface of the cutting tools of multiple agricultural machinery cutting tools by multi-pass additive method to form a second coating structure of a triangular structure with a thickness gradient change; the thicker side of the second coating structure is located at the end face position adjacent to the first processing surface;
The back gap of the agricultural machinery cutting tool is impacted by a pneumatic impact shovel to separate each agricultural machinery cutting tool.
As an optional implementation, in the first coating structure of the triangular structure, the maximum coating thickness is 3mm, the minimum coating thickness is 0.15mm, and the length is 50mm; the number of cladding passes is 20;
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min;
The powder feeding process includes 20 passes of powder feeding, and the powder feeding amount has a continuous gradient change trend.
As an optional implementation, in the second coating structure of the triangular structure, the maximum coating thickness is 1.5mm, the minimum coating thickness is 0.15mm, and the length is 25mm; the number of cladding passes is 10.
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min;
The powder feeding process includes 10 passes of powder feeding, and the powder feeding amount is in a continuous gradient change trend.
According to the second aspect of the purpose of the present invention, a high-hardness wear-resistant coating structure on the surface of an agricultural machinery cutting tool prepared by the aforementioned method is also proposed.
According to the above technical scheme, the laser cladding preparation method of the high-hardness wear-resistant coating on the surface of an agricultural machinery cutting tool proposed by the present invention realizes assembly line production through batch clamping, which not only solves the problem of cracking caused by large heat input of the cladding layer prepared by a single tool, but also improves production efficiency, realizes the preparation of a gradient wear-resistant coating by adjusting the powder feeding amount to match the appropriate cladding layer thickness, reduces post-processing steps, improves production efficiency, and shortens the production cycle.
It should be understood that all combinations of the aforementioned concepts and the additional concepts described in more detail below can be regarded as part of the inventive subject matter of the present disclosure as long as such concepts do not contradict each other. In addition, all combinations of the claimed subject matter are considered part of the inventive subject matter of the present disclosure.
The foregoing and other aspects, embodiments and features of the teachings of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and/or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned through the practice of specific embodiments according to the teachings of the present invention.

Description of the drawings
The drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or approximately identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is marked in each figure.
Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, wherein:
Figure 1 is a schematic diagram of a laser cladding preparation system for a high hardness and wear-resistant coating on the surface of an agricultural machinery cutting tool according to an embodiment of the present invention.
Figure 2 is a schematic diagram of a high hardness and wear-resistant coating prepared on the surface of an agricultural machinery cutting tool according to an embodiment of the present invention.
Figure 3 is a schematic diagram of a process for preparing a high hardness and wear-resistant coating on the surface of an agricultural machinery cutting tool according to an embodiment of the present invention.
Figure 4 is a schematic diagram of the physical structure of an agricultural machinery cutting tool according to an embodiment of the present invention.
Figure 5 is a schematic diagram of the physical structure of a cutting tool stack formed by vertically stacking agricultural machinery cutting tools according to an embodiment of the present invention.
FIG6 is a schematic diagram of laser cladding additive processing of a cutting tool stack according to an embodiment of the present invention.
FIG7 is a schematic diagram of a coating structure prepared on the surface of a cutting tool stack according to an embodiment of the present invention.
FIG8 is a schematic diagram of a coating structure prepared on the surface of a single agricultural machine cutting tool after the agricultural machine cutting tools of the cutting tool stack according to an embodiment of the present invention are separated.

Specific implementation methods
In order to better understand the technical content of the present invention, specific embodiments are cited and described as follows in conjunction with the accompanying drawings.
In this disclosure, various aspects of the present invention are described with reference to the accompanying drawings, and many illustrative embodiments are shown in the accompanying drawings.
The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in the present invention are not limited to any implementation. In addition, some aspects disclosed in the present invention can be used alone or in any appropriate combination with other aspects disclosed in the present invention.
The laser cladding preparation system for high hardness and wear-resistant coating on the surface of agricultural machinery cutting tools as shown in Figure 1 includes a laser cladding head 1, a control cabinet 3, a cladding processing control system 4, and a carrier gas powder feeder 5. 10 in Figure 1 represents a single agricultural machinery cutting tool, and multiple agricultural machinery cutting tools are stacked vertically to form a cutting tool stack 100, as shown in Figures 5 and 6.
In an optional embodiment, the number of stacks can be determined according to the shape and size of the agricultural machinery cutting tool, and 3-10 are usually selected for stacking to form a processing surface suitable for additive manufacturing. In an embodiment of the present invention, 5 corn harvester cutting tools are stacked as an example.
The laser cladding head 1 is installed on the robot arm, and the control cabinet 3 is used to control the movement of the robot arm according to the control signal of the PLC control system 4, so as to control the laser cladding head to run according to a predetermined trajectory and perform laser cladding additive processing.
The carrier gas powder feeder 5 uses argon gas and is controlled by the cladding processing control system 4 to feed powder to the powder feeding nozzle under the laser cladding head 1 and to the surface of the cutting tool stack 100.
The cladding processing control system 4 can be implemented by an industrial-grade PLC control system.
In conjunction with the example shown in Figure 2-8, the flat-structured cutting tool used in the corn harvester is used as an example for explanation. Generally, the agricultural machinery cutting tool has a rectangular flat structure, including two working surfaces, namely a narrower long side working surface and a cutting tool top surface adjacent to it, as shown in Figures 2, 3, and 4.
In an embodiment of the present invention, agricultural machinery cutting tools 10 are stacked vertically to form an integral cutting tool stack 100, as shown in Figures 5 and 6, and the corresponding surfaces of the cutting tool stack 100, i.e., the processing surfaces respectively formed by the multiple long side working surfaces and the multiple cutting tool top surfaces, are subjected to cladding processing to prepare a coating structure.
In combination with Figures 2 and 3, a first coating structure can be first clad on the processing surface corresponding to the long side working surface, and its edge is flush with the processing surface corresponding to the cutting tool top surface, so as to facilitate the preparation of the second coating structure on the processing surface corresponding to the cutting tool top surface, and the first coating structure constitutes a supporting structure.
We will use a specific example to more specifically describe the process of preparing a high-hardness wear-resistant coating by laser cladding on the surface of agricultural machinery cutting tools. As shown in Figures 3, 5, 6, and 7, it specifically includes the following steps:
Stack multiple agricultural machinery cutting tools 10 to be processed and clamp them through tooling, such as through a flat vise, to form a cutting tool stack 100; wherein the coating processing surface of each agricultural machinery cutting tool is the long side working surface and the top surface of the cutting tool directly connected to the long side working surface. By stacking the agricultural machinery cutting tools, as shown in Figure 5, the long side of multiple cutting tools is The side working surfaces are stacked to form the first processing surface of the cutting tool stack, and the top surfaces of multiple cutting tools are stacked to form the second processing surface of the cutting tool stack, and the first processing surface is adjacent to the second processing surface;
The cutting tool stack 100 is placed on the substrate with the first processing surface facing upward as the cladding surface, as shown in Figure 3;
According to the shape of the long side working surface of the agricultural machinery cutting tool, the cladding trajectory, laser scanning process and powder feeding process on the first processing surface are planned, and laser cladding additive is performed under a protective gas environment accordingly, and two layers of cladding layers are printed on the long side working surfaces of multiple agricultural machinery cutting tools by multi-pass additive method, The first coating structure 101 of the triangular structure is formed, and its thickness gradient changes; the thicker side of the first coating structure is located at the end surface position adjacent to the second processing surface, forming a support structure for preparing the second coating structure on the second processing surface; the cladding powder is selected from Ni-based WC composite materials;
The cutting tool stack 100 is turned 90°, with the second processing surface facing upward as the cladding surface;
The cladding trajectory, laser scanning process and powder feeding process on the second processing surface are planned according to the top surface shape of the cutting tool of the agricultural machinery cutting tool, and laser cladding additive is performed under a protective gas environment accordingly. The top surfaces of multiple agricultural machinery cutting tools are printed with a cladding layer by a multi-pass additive method to form a second coating structure 102 of a triangular structure, whose thickness gradient varies; the thicker side of the second coating structure is located at the end surface adjacent to the first processing surface; the cladding powder is selected from a Ni-based
WC composite material; FIG7 is a schematic diagram of the coating structure prepared on the two surfaces of the cutting tool stack;
The pneumatic impact shovel is used to impact the back gap of the agricultural machinery cutting tool to separate each agricultural machinery cutting tool to obtain a single agricultural machinery cutting tool with a high wear-resistant coating on the surface, as shown in FIG8.
It should be understood that the coating structure is prepared on two adjacent surfaces of the cutting tool stack, and no coating is prepared on the other two surfaces opposite to the two surfaces, and there is a certain gap between the cutting tools. Therefore, in the embodiment of the present invention, the pneumatic impact shovel is used to impact the back gap of the agricultural machinery cutting tool to achieve the separation of the cutting tools.
Among them, the laser cladding process uses a multi-nozzle coaxial carrier gas powder feeding, such as a four-way powder feeding, and the protective gas atmosphere environment and the powder feeding carrier gas during the cladding process are both argon.
As shown in Figures 5 and 6, during the laser cladding additive process of the first coating structure 101 and the second coating structure, the laser cladding trajectory adopts a reciprocating method.
For example, during the laser cladding additive process of the first coating structure 101, each pass of laser cladding is to sequentially cross the long side working surface of the agricultural machinery cutting tool. After completing the processing of the long side working surface of all the stacked agricultural machinery cutting tools under this pass, the laser cladding head rotates 180 degrees to perform the next pass, wherein the overlap rate of adjacent passes is 40%-50%.
During the laser cladding additive process of the second coating structure 102, each pass of laser cladding is to sequentially cross the top surface of the cutting tool of the agricultural machinery cutting tool. After completing the processing of the top surface of the cutting tool of all the stacked agricultural machinery cutting tools under this pass, the laser cladding head rotates 180 degrees to perform the next pass, wherein the overlap rate of adjacent passes is 40%-50%.
In particular, according to the structure of the solvent cutting tool, during the laser cladding additive process of the first coating structure 101 and the second coating structure 102, the thickness of the cladding layer shows a gradient change trend, thereby forming a triangular structure.
In an optional embodiment, it is found through actual experimental tests that when the powder feeding amount is 2.0r/min, the thickness of the cladding layer is 1.5mm. The gradient change of the thickness of the cladding layer is achieved by controlling the gradient change of the powder feeding amount.
Taking the flat-structured cutting tool used in the corn harvester as an example, in the first coating structure 101 of the triangular structure, the maximum coating thickness is 3mm, the minimum thickness is 0.15mm, and the length is 50mm; the cladding passes are 20 passes.
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min.
The first cladding layer is numbered 1, and the powder feeding amount is 0.1r/min. The 20th cladding layer is numbered 20, and the powder feeding amount is 2.0r/min.
The powder feeding process planning is shown in Table 3, wherein the powder feeding process includes 20 passes of powder feeding, and the powder feeding amount changes in a continuous gradient.
In the second coating structure 102 of the triangular structure, the maximum coating thickness is 1.5mm, the minimum thickness is 0.15mm, and the length is 25mm; the cladding passes are 10.
The laser scanning process includes: selecting a laser power of 1300W-2000W, a circular spot of the laser beam, a spot diameter of 5mm, a scanning line speed of 10-30mm/s, an overlap rate of 50%, and an argon protection flow rate of 40-50ml/min.
The powder feeding process planning is shown in Table 4, wherein the powder feeding process includes 10 passes of powder feeding, and the powder feeding amount changes in a continuous gradient.
In another embodiment, the powder feeding amount can be adjusted and determined according to the coating thickness requirement and the line speed value.
Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the definition of the claims.