As a high-tech technology, laser technology has been applied in almost all walks of life. Laser processing technology refers to various advanced material processing technologies that use high-energy density laser beams as a means to change the form or properties of materials through physical and chemical interactions between laser beams and materials. Laser processing involves multiple disciplines such as laser physics, materials, electronics, machinery and engineering heat transfer, and integrates multiple technologies such as laser, manufacturing, control and computer application. It has become a typical advanced manufacturing technology that crosses multiple disciplines and integrates multiple technologies. Laser processing has the characteristics of non-contact, no pollution, small heat-affected area, high processing accuracy and optional area processing, and it is irreplaceable by other manufacturing methods under specific processing conditions. Therefore, laser technology has been applied in many industries.

Due to the characteristics of its own application and the complexity of the working object, agricultural machinery, especially the backward design and processing methods in the agricultural machinery manufacturing industry, has few innovations, long new product development cycles, high costs, rough manufacturing quality, and relatively short product life. In order to vigorously improve the manufacturing technology of agricultural machinery and develop it in parallel with other machinery manufacturing industries, it is necessary to increase the application of advanced manufacturing technologies such as laser in agricultural manufacturing and improve the modern production technology level of agricultural machinery manufacturing enterprises.

Application of laser rapid prototyping in agricultural machinery manufacturing:

Rapid prototyping technology is a general term for the technology of rapid production of samples or parts directly based on CAD models. It integrates modern scientific and technological achievements such as CAD technology, CNC technology, laser technology and material technology, and is an important part of advanced manufacturing technology. It can automatically, directly, quickly and accurately materialize design ideas into prototypes with certain functions or directly manufacture parts based on CAD models (electronic models), and generate almost any complex parts without molds and tools, solving the problem of rapid docking from design to manufacturing. Therefore, this technology can quickly evaluate and modify product designs, effectively shorten the product R&D cycle, reduce development costs, meet the requirements of today’s increasingly competitive market for rapid development and rapid manufacturing of new products, and improve the market competitiveness of products and the comprehensive competitiveness of enterprises.

Laser selective sintering is one of the important process methods in rapid prototyping manufacturing. This technology uses the principle of adding materials layer by layer to slice and partition the three-dimensional solid model to generate a scanning path for laser sintering; then, the laser beam is scanned along the scanning path by an x-Y laser scanner to sinter and assimilate the same body powder material (such as plastic powder, nylon powder, wax, ceramic or), mixed powder of metal and binder or metal powder, etc. layer by layer. After sintering and layer by layer stacking, the required three-dimensional workpiece is finally formed. This manufacturing method has the characteristics of fast forming speed, high precision, good surface quality, simple post-processing and time saving. It is a vital technology and has created a new method for the development of manufacturing technology.

The production process of agricultural machinery has its own characteristics. Most parts have complex shapes, such as tillage machinery, land preparation machinery and harvesting machinery. In addition, there are many complex curved surfaces, such as plow body curved surface, rotary tiller rotary blade, water pump impeller and feed screw, etc., and their shapes need to be adjusted accordingly according to the specific production situation. Therefore, the development of such agricultural machinery parts using traditional mechanical processing methods not only takes a long time and complex processing technology, but also is difficult to achieve the desired effect. The use of advanced laser rapid prototyping integrated technology not only greatly shortens the development cycle of new products and reduces development costs, but also improves manufacturing quality over traditional manufacturing methods.

Application of laser surface strengthening and heat treatment:

Laser surface strengthening and heat treatment technology is a new type of material surface treatment technology developed in the past 20 years. The principle of laser surface strengthening technology is to use the characteristics of laser’s strong penetration ability. When the metal surface is heated to a critical transition temperature just below the melting point, its surface is rapidly austenitized, and then rapidly self-cooled and quenched, and the metal surface is rapidly strengthened. Laser surface strengthening and heat treatment can be divided into three categories: First, the metal does not melt when the laser is irradiated, but the structure changes. This type of process is mainly laser phase change hardening (laser quenching); second, the metal melts when the laser is irradiated, and the structure changes after cooling or other elements are added to improve the surface properties, including laser melting, laser alloying, laser amorphization and microcrystallization; third, the metal surface vaporizes when the laser is irradiated, thereby causing a change in structure. This type of process is mainly laser shock hardening. The common theoretical basis of the above-mentioned various laser heat treatment processes is the law of interaction between laser and matter and its metallurgical behavior.

Laser heat treatment is the development and supplement of traditional heat treatment technology. It can solve the material strengthening problems that other surface treatment methods cannot solve or are difficult to solve. After laser treatment, the surface strength of the casting layer can reach HRC60 or above, and the surface hardness of medium carbon, high carbon steel and alloy steel can reach HRC70 or above, thereby improving its wear resistance, fatigue resistance, corrosion resistance and oxidation resistance, and extending its service life.

Laser heat treatment is widely used in the automotive industry. Almost all key parts of many vehicles (such as cylinder block, cylinder liner, crankshaft, camshaft, exhaust valve, valve seat or piston ring, etc.) can be treated with HJ laser heat treatment. Similarly, agricultural locomotives should also be widely used. In agricultural production, the working conditions of machines are varied. Some machines (plows, cultivators, seeders and harvesters) work directly in abrasive media, causing many parts to wear out quickly. On the other hand, in order to obtain sufficient strength, the material consumption of the machine is large, which not only wastes materials but also appears bulky. For such parts, the hardness after laser hardening treatment is 5% to 20% higher than that of conventional quenching. Laser alloying can select new materials to form a new alloy layer based on the substrate to obtain satisfactory performance. In addition, due to the improved performance after treatment, low-performance substrates can be selected, thereby reducing the mass of the substrate.

Application of laser in agricultural machinery parts repair:

Laser cladding (also known as laser melting) is a new surface modification technology. It adds cladding material to the surface of the substrate and uses a high-energy-density laser beam to melt it together with a thin layer on the surface of the substrate to form a filler cladding layer that is metallurgically bonded on the surface of the substrate. Since laser cladding can clad high-melting-point materials on the surface of low-melting-point substrates, and the composition of the materials is not limited by the usual thermodynamic conditions of alloy metallurgy. Therefore, the range of cladding materials used is quite wide, including nickel-based, cobalt-based, iron-based alloys, carbide composite alloy materials, and ceramic materials. Among them, laser cladding of alloy materials and carbide composite materials is relatively mature and has been put into practical use. Due to the nearly adiabatic rapid heating process generated by the high energy density of the laser beam, laser cladding has less thermal impact on the substrate and causes less deformation. Controlling the input energy of the laser can also limit the dilution of the substrate to a very low level (less than 10%), thereby maintaining the excellent performance of the original cladding material.

Therefore, laser cladding technology can improve the wear resistance and corrosion resistance of the material surface, and is mainly used for repairing parts after wear and enhancing the performance of newly manufactured parts. For important parts (such as cylinder liners and pistons in agricultural machinery), due to the large workload, high temperature, high pressure, erosion and different degrees of friction, the wear amount is very large, and the parts need to be scrapped and replaced regularly. For tillage machinery, land preparation machinery and harvesting machinery (such as plows, cultivators, seeders and harvesters), local wear is very fast during operation, and parts are scrapped because of local damage. In order to increase the service life of parts, repair work is of great significance. Laser processing has the unique advantage of selective effect, and laser cladding can easily repair worn parts, so that parts are not scrapped due to local damage, improve the reliability and service life of parts, and achieve better performance requirements again with the lowest investment cost. In addition, repairing molds with lasers can greatly increase the life of molds, and is not limited by shape and size. It should also be vigorously promoted and adopted in agricultural machinery manufacturing.

Several thoughts on the application of laser technology in agricultural machinery manufacturing:

1. Laser processing technology has been vigorously promoted in many industries, and its application in agricultural machinery manufacturing is also imperative. However, the selection of processing types and the use of lasers must start from the basics. Only when this advanced processing method is fully mastered can the traditional process be better improved and the advantages of new technologies be brought into play. Laser processing technology integrates modern scientific and technological achievements such as CAD technology, CNC technology, laser technology and material technology, and the technology covers a wide range. Therefore, when agricultural machinery companies are engaged in laser manufacturing projects, they must analyze their own conditions and needs, consult other machinery companies, identify the direction, find the combination point, proceed step by step, and avoid the so-called “one-step”. Because laser processing technology develops very rapidly, no company can achieve it in one step.
2. The application of laser processing technology in agricultural machinery manufacturing has gradually become popular around the world, mainly because the industry is impressed by the application of laser technology and its actual effects. In addition, the reason for the lack of adoption of laser technology before was that there was insufficient publicity of laser technology and lack of practice. Therefore, agricultural machinery enterprises should introduce and absorb mature scientific research results in industrial production as soon as possible, make good use of the multifunctional laser processing centers that have been established in the industry, and make them serve more agricultural machinery enterprises.
3. In recent years, the manufacturing technology of high-power lasers and auxiliary equipment has been increasingly improved, and its basic theory and production technology have become increasingly mature. Compared with other processing equipment, the price of high-power lasers is not very high. Therefore, the application of laser processing technology in agricultural machinery manufacturing has certain external conditions. In addition, with the rapid development of agricultural industrialization, the strength of agricultural manufacturing enterprises has been significantly enhanced, and the requirements for product quality have become higher and higher, which provides internal motivation and conditions for the application of laser processing technology in agricultural machinery manufacturing. Therefore, the application of laser processing technology in agricultural machinery manufacturing is currently in place. It can be predicted that the introduction of laser processing technology will greatly improve the manufacturing level of agricultural machinery.