熔覆工艺：根据熔覆材料的供应方式，激光熔覆大致可分为两类，即预置激光熔

Cladding process: According to the way of cladding material supply, laser cladding can be roughly divided into two categories, namely preset laser cladding and synchronous laser cladding. [17] <br>(1) Synchronous laser cladding is to directly feed the cladding material into the laser beam, and simultaneously complete the feeding and cladding. The cladding materials are mainly supplied in powder form, and some cladding materials are also supplied by wires or boards at the same time. The main processes of synchronous laser cladding are: pretreatment of substrate cladding, surface feeding, and heat treatment after laser cladding. <br>(2) Preset laser cladding is to place the cladding material on the cladding part of the substrate surface in advance, and then irradiate the laser beam to scan and melt it. The most common is powder. The main technological process of preset laser cladding: pretreatment of substrate cladding surface, pre-heating of preset cladding material, heat treatment after laser cladding. This method can solve the problem of the reflectivity of the matrix material to the laser, but the coating thickness is controllable. <br>(3) Through many experiments, it was found that proper preheating of the copper substrate can obtain a smooth continuous cladding layer at a lower laser power and a higher moving speed, and the cladding process is stable. Therefore, the laser cladding studied in this paper was performed on a substrate preheated at 300 ° C. In order to meet the use requirements of the guide rail, a thicker coating is prepared by a method of multi-layer multi-pass overlap. The results show that the laser cladding process changes with the size of the substrate, the cladding area and the number of cladding layers. When continuous lap cladding is performed on a substrate with a smaller size, the temperature of the substrate will rise rapidly as the cladding progresses, so the required laser power will be reduced; In the actual rail cladding process, the overall temperature of the substrate is difficult to increase without power adjustment; while in the multilayer cladding process, the laser absorption rate increases due to changes in the surface roughness of the deposited material and the composition of the material and needs to be appropriately reduced Laser power or increase the speed of movement.

Cladding process: According to the mode of supply of cladding materials, laser cladding can be broadly divided into two categories, namely, pre-set laser cladding and synchronous laser cladding. [17]<br>(1) Synchronous laser cladding is the direct feed of the cladding material into the laser beam, while completing the feeding and cladding. The cladding material is supplied mainly in powder form, and some cladding materials are supplied simultaneously by wires or plates. The main processes for synchronous laser cladding are: pretreatment of substrate cladding, surface feeding, and post-laser cladding heat treatment.<br>(2) Pre-set laser cladding is the pre-positionofed cladding material on the cladding part of the substrate surface, and then scanning the melt ingress with laser beam. The most common is powder. The main process of pre-set laser cladding: base cladding surface pretreatment pretreatment pre-installed cladding material preheats laser cladding post-heat treatment. This method can solve the problem of the reflectivity of the substrate material to the laser, but the coating thickness is controllable.<br>(3) Through many experiments, it is found that the proper preheating of copper substrates, can obtain a smooth continuous cladding at a lower laser power and high moving speed, the cladding process is stable. Therefore, the laser cladding studied in this paper is carried out on a substrate that is preheated at 300 degrees C. In order to meet the requirements of the use of rails, a thick coating is prepared by using a multi-layer multi-way connection method. The results show that the laser cladding process varies with the size of the substrate, the area of the cladding and the number of cladding. When continuous cladding is performed on a smaller substrate, the temperature of the substrate will rise rapidly as the cladding progresses, so the required laser power will decrease;

Cladding process: according to the supply mode of cladding materials, laser cladding can be divided into two categories, i.e. preset laser cladding and synchronous laser cladding. [17]<br>(1) Synchronous laser cladding is to send cladding materials directly into laser beam, and complete feeding and cladding at the same time. Cladding materials are mainly supplied in the form of powder, some of which are also supplied by wires or boards at the same time. The main technological process of the synchronous laser cladding is: the pretreatment of the matrix cladding, the feeding of the surface and the heat treatment after the laser cladding.<br>(2) The preset laser cladding is to place the cladding material on the surface of the substrate in advance, and then use the laser beam to scan and melt. The most common is powder. The main process of laser cladding: the surface pretreatment of the substrate cladding, the preheating of the cladding material, the heat treatment after laser cladding. This method can solve the problem of laser reflectivity, but the coating thickness is controllable.<br>(3) Through many experiments, it is found that a smooth and continuous cladding layer can be obtained with low laser power and high moving speed by preheating copper substrate properly, and the cladding process is stable. Therefore, the laser cladding studied in this paper is carried out on the substrate preheated at 300 ℃. In order to meet the use requirements of the guide rail, the thick coating was prepared by multi-layer and multi-channel lapping. The results show that the laser cladding process changes with the substrate size, cladding area and cladding layer number. When the continuous lap cladding is carried out on the substrate with smaller size, the temperature of the substrate will rise rapidly with the cladding, so the required laser power will be reduced; however, due to the rapid heat dissipation of the substrate, the actual rail cladding process at this time, the overall temperature of the substrate is difficult to rise, and no power regulation is required; while in the multi-layer cladding process, due to the surface of the deposited material With the change of roughness and material composition, the laser absorptivity increases, so it is necessary to reduce the laser power or increase the moving speed.<br>