Laser cladding repairing method for heavy-load universal coupling shaft sleeve

Abstract

The invention discloses a laser cladding repairing method for a heavy-load universal coupling shaft sleeve, which comprises the following specific steps of: 1, preheating the shaft sleeve by adopting a heat treatment furnace at the preheating temperature of 200-250 DEG C, and preserving heat for 4 hours; secondly, a heating belt is wound around the outer circle of the shaft sleeve so that the shaft sleeve can be continuously heated in the cladding process; thirdly, the two symmetrical flat faces of the shaft sleeve are subjected to alternate laser cladding through an inner hole optical head; and fourthly, the shaft sleeve is integrally fed into a furnace for annealing, the annealing temperature is 500-550 DEG C, heat preservation is conducted for 5-7 h, slow cooling is conducted along with the furnace, and after the temperature is lower than 100 DEG C, the shaft sleeve is discharged out of the furnace for air cooling. When the flat surface of the shaft sleeve is cladded, an alternate cladding method is adopted, so that a cladding layer has time to fully release stress to reduce crack defects of the cladding layer caused by stress concentration, and heat preservation and slow cooling of the cladded surface are realized through continuous heating, so that the cladding surface gradually releases stress to avoid cracking of the cladding layer caused by rapid cooling.

Description

Background Art

[0001] In the production line of the steel mill's wide and thick plates, hot-rolled thin plates, steel pipes, and steel production lines, the function of the heavy-duty universal coupling is to transmit the power of the motor tooth end to the roller end to drive the roller to rotate. The shaft sleeve in the heavy-duty universal coupling is an important part of the tooth end and shaft end of the heavy-duty universal coupling. Because it is in a high-torque and high-strength environment, the performance and strength requirements of the shaft sleeve are extremely high. The failure mode of the shaft sleeve is mainly corrosion and wear, and the two symmetrical flat surfaces inside the shaft sleeve are the main locations where wear occurs.

[0002] High-hardness, high-wear-resistant materials are usually used when laser cladding is used to repair the flat surface of a sleeve. Therefore, the internal stress of the cladding layer after laser cladding is large, which will cause cracks in the cladding layer. The thicker the cladding layer and the more layers are clad, the greater the risk of cracking. At present, when the flat surface of the sleeve is clad with multiple layers, one surface is clad continuously, and the risk of cracking during the cladding process is controlled by preheating. After the cladding is completed, an asbestos blanket is used to keep warm and cool slowly to prevent the cladding layer from cracking due to excessive cooling. However, the above cladding method is not very effective in removing stress, resulting in the following situations that still occur frequently: 1. The cladding layer is torn due to excessive internal stress during laser cladding; 2. The residual stress inside the cladding layer is still too large after insulation and slow cooling, causing the cladding layer to crack during the boring and milling of the sleeve. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a laser cladding repair method for a heavy-duty universal coupling sleeve. When cladding the flat surface of the sleeve, an alternating cladding method is used to allow the cladding layer to fully release stress and reduce crack defects caused by stress concentration in the cladding layer. The cladding completed surface is kept warm and slowly cooled by continuous heating, so that the cladding surface gradually releases stress to avoid cracking of the cladding layer caused by rapid cooling. At the same time, the present invention further reduces the stress of the cladding layer and avoids cracking of the cladding layer by preheating before cladding and overall annealing after cladding.

[0004] The laser cladding repair method for a heavy-duty universal joint shaft sleeve of the present invention comprises the following specific steps: 1. preheating the shaft sleeve in a heat treatment furnace: the preheating temperature is 200-250°C and the shaft sleeve is kept warm for 4 hours; 2. a heating belt is wrapped around the outer circle of the shaft sleeve so that the shaft sleeve is continuously heated during the cladding process; 3. an inner hole laser head is used to perform alternate laser cladding on two symmetrical flat surfaces of the shaft sleeve; 4. the shaft sleeve is annealed in a furnace as a whole: the annealing temperature is 500-550°C and the shaft sleeve is kept warm for 5-7 hours, and the shaft sleeve is slowly cooled along with the furnace, and air-cooled after the temperature is lower than 100°C.

[0005] Wherein: In step 3: when the cladding thickness of the two flat surfaces of the sleeve is thin, clad one flat surface first and then clad the other flat surface.

[0006] Among them: In step three: when the cladding thickness of the two flat surfaces of the sleeve is relatively thick, and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the left flat surface and the right flat surface, the cover layer is also clad in the above order.

[0007] Among them: In step three: when the cladding thickness of the four flat surfaces of the sleeve is relatively thick and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the upper left flat surface, the lower right flat surface, the lower left flat surface, and the upper right flat surface, the cover layer is also clad in the above order.

[0008] Among them, in step three: the base cladding material is a wear-resistant stainless steel material, and its chemical composition and mass percentage are: 15-18.5% Cr, 0.8-1.5% Ni, 0.6-1.2% Mo, 0.8-1.2% B, 0.6-1.5% Si, <0.5% C, <0.8% Mn, and the balance is Fe; the cover cladding material is a high-strength wear-resistant stainless steel material, and its chemical composition and mass percentage are 14-17% Cr, 1.4-2.4% Ni, 0.8-1.2% Mo, 1.0-1.5% B, 1.4-1.7% Si, <0.5% C, <1.0% Mn, and the balance is Fe.

[0009] The advantages of the laser cladding repair method of the present invention are as follows: First, when the flat surface cladding thickness is relatively thick, the cladding layer is divided into two layers, the bottom surface and the cover surface, and the two (four) flat surfaces are clad alternately. This layered + alternating cladding method allows the cladding layer that has been clad to have time to fully release stress, thereby reducing crack defects caused by stress concentration in the cladding layer; at the same time, during the cladding process, the sleeve is continuously heated by winding a heating belt, so that the bottom layer (cover surface layer) is kept warm and cooled slowly, and the cladding surface gradually releases stress to avoid cracking of the cladding layer caused by rapid cooling; therefore, the flat surface cladding The thickness of the cladding can reach 15mm; second, the base layer increases the bonding strength between the cladding layer and the substrate, and through the selection of materials, the strength of the cladding layer is gradually improved from the substrate, the packaging surface, and the cover surface, ensuring the reliable connection between the cladding layer and the substrate, improving the hardness of the cladding layer and its wear resistance, thereby extending the service life of the sleeve; third, a heat treatment furnace is used for preheating before cladding to reduce the temperature difference during cladding and reduce the possibility of cracking; fourth, after the cladding is completed, the sleeve is annealed as a whole to remove the stress inside the cladding layer to prevent the cladding layer from cracking due to excessive cooling rate.

[0010] In summary, the laser cladding repair method of the present invention fully releases stress during cladding and performs corresponding treatments to avoid cracking before and after cladding, so that the stress inside the cladding layer during and after the cladding is completed can be fully reduced, and the occurrence of cracking of the cladding layer caused by excessive internal stress during laser cladding and excessive residual stress inside the cladding layer during boring and milling of the sleeve can be avoided, thereby improving the one-time success rate of the sleeve cladding, eliminating the need for rework and reducing the cost of the sleeve. The thickness of the cladding layer in the present invention can reach 15 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a parts diagram of the shaft sleeve in embodiment 2 of the present invention.

[0012] Figure 2 It is a parts diagram of the shaft sleeve in embodiment 3 of the present invention.

[0013] Figure 3 It is a parts diagram of the shaft sleeve in embodiment 4 of the present invention. DETAILED DESCRIPTION

[0014] The present invention is further described in detail below with reference to the embodiments.

[0015] Example 1

[0016] The laser cladding repair method of the heavy-loaded universal joint sleeve of the present invention comprises the following steps: 1. preheating the sleeve in a heat treatment furnace: the preheating temperature is 200-250°C, and the sleeve is kept warm for 4 hours; 2. a heating belt is wrapped around the outer circle of the sleeve so that the sleeve is continuously heated during the cladding process; 3. an inner hole laser head is used to perform alternate laser cladding on two symmetrical flat surfaces of the sleeve; 4. the sleeve is annealed in the furnace as a whole: the annealing temperature is 500-550°C, the sleeve is kept warm for 5-7 hours, and the sleeve is slowly cooled along with the furnace, and air-cooled after the temperature is lower than 100°C.

[0017] In step three: 1. When the cladding thickness of the two flat surfaces of the sleeve is relatively thin, one flat surface is clad first and then the other flat surface; 2. When the cladding thickness of the two flat surfaces of the sleeve is relatively thick and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the left flat surface and the right flat surface, the cover layer is also clad in the above order; 3. When the cladding thickness of the four flat surfaces of the sleeve is relatively thick and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the upper left flat surface, the lower left flat surface, the upper and lower right flat surfaces, and the lower right flat surface, the cover layer is also clad in the above order.

[0018] It can be seen from the above that: 1. When the thickness of the flat surface cladding is thin, the stress generated by the cladding is small, and the cladding of a flat surface can be completed at one time; 2. When the thickness of the flat surface cladding is thick, the flat surface is divided into two layers, the base layer and the cover layer, and the stress generated by the cladding is large. The base layer and the cover layer of the flat surface are clad alternately, so that before the cover cladding is carried out, the base layer has time to fully release the stress, reducing the crack defects of the cladding layer caused by stress concentration, and greatly reducing the cracking risk of multi-layer superimposed cladding.

[0019] In step three: the base cladding material is a wear-resistant stainless steel material, and its chemical composition and mass percentage are: 15-18.5% Cr, 0.8-1.5% Ni, 0.6-1.2% Mo, 0.8-1.2% B, 0.6-1.5% Si, <0.5% C, <0.8% Mn, and the balance is Fe; the cover cladding material is a high-strength wear-resistant stainless steel material, and its chemical composition and mass percentage are 14-17% Cr, 1.4-2.4% Ni, 0.8-1.2% Mo, 1.0-1.5% B, 1.4-1.7% Si, <0.5% C, <1.0% Mn, and the balance is Fe.

[0020] Example 2

[0021] like Figure 1 As shown, the sleeve has two symmetrical flat surfaces: surface A and surface B. The flat surface repair size is 1mm. The laser cladding repair method is as follows:

[0022] (1) Preheat the sleeve in a heat treatment furnace at 200°C for 4 hours;

[0023] (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the cladding robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation;

[0024] (3) Use an inner hole laser head for laser cladding: first clad the A surface, then rotate the sleeve 180° to clad the B surface; the cladding material is high-strength wear-resistant stainless steel; the cladding power is 3.0KW, the scanning speed is 900mm / min, and the single-layer cladding thickness is 1.5mm;

[0025] (4) The sleeve is put into a heat treatment furnace for annealing at a temperature of 500°C. After reaching the temperature, it is kept at this temperature for 6 hours and then slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled.

[0026] (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

[0027] In this embodiment, since the thickness of the flat surface cladding is relatively thin, the stress generated by the cladding is relatively small, and the risk of cracking of the cladding layer is relatively small, so the cladding of one flat surface is completed at one time. When cladding another flat surface, the flat surface that has been clad is kept warm and slowly cooled under the action of the heating belt, so that the stress of the cladding surface is gradually released to avoid cracking of the cladding layer caused by rapid cooling. At the same time, an annealing process is added after laser cladding, which greatly reduces the internal stress of the cladding layer and reduces the risk of cracking of the cladding layer.

[0028] Example 3

[0029] like Figure 2 As shown, the sleeve has two symmetrical flat surfaces: surface C and surface D. The flat surface repair size is 5mm. The laser cladding repair method is as follows:

[0030] (1) Preheat the sleeve in a heat treatment furnace at 200°C for 4 hours;

[0031] (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation;

[0032] (3) Use the inner hole laser head to perform laser cladding in an alternating cladding manner. Each flat surface is divided into bottom cladding and cover cladding: first perform bottom cladding on the C surface, then rotate the sleeve 180° to perform bottom cladding on the D surface, then rotate the sleeve 180° to perform cover cladding on the C surface, and finally rotate the sleeve 180° to perform cover cladding on the D surface; the cladding power of bottom cladding is 2.8KW, the scanning speed is 900mm / min, the total cladding is three layers, and the single layer cladding thickness is 1.3mm; the cladding power of cover cladding is 2.5KW, the scanning speed is 900mm / min, the total cladding is two layers, and the single layer cladding thickness is 0.9mm;

[0033] (4) The sleeve is put into the heat treatment furnace for annealing at a temperature of 550°C. After reaching the temperature, it is kept warm for 7 hours. The workpiece is slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled.

[0034] (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

[0035] In this embodiment: Since the thickness of the flat surface cladding is relatively thick, the stress generated by continuous cladding is relatively large. At this time, the flat surface is divided into a base layer cladding and a cover layer cladding, and the base layers and cover layers of the two flat surfaces are clad alternately, so that the base layer of the flat surface has time to fully release stress before the cover cladding, reducing the crack defects caused by stress concentration in the cladding layer, and greatly reducing the cracking risk of multi-layer superimposed cladding. At the same time, the base layer (cover layer) is kept warm and slowly cooled under the action of the heating belt, so that the cladding surface gradually releases stress to avoid cracking of the cladding layer caused by rapid cooling, so the thickness of the cladding layer can reach 15mm without cracking, pores and other defects. At the same time, compared with the method of surfacing welding and laser cover, it saves the cost of one annealing and one boring and milling.

[0036] Example 4

[0037] from Figure 3 It can be seen that the sleeve has four flat surfaces: upper left, lower left, upper right, and lower right: E surface, F surface, G surface, and H surface. The flat surface repair size is 2mm: The laser cladding repair method at this time is as follows:

[0038] (1) Preheat the sleeve in a heat treatment furnace at 250°C for 4 hours;

[0039] (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation;

[0040] (3) Use the inner hole laser head to perform laser cladding in an alternating cladding manner. Each flat surface is divided into bottom cladding and cover cladding: bottom cladding is: first perform bottom cladding on the E surface, then perform bottom cladding on the F surface; after rotating the sleeve 180°, first perform bottom cladding on the G surface, then perform bottom cladding on the H surface; the order of cover cladding is the same as that of bottom cladding; the cladding power of the bottom cladding material is 2.5KW, the scanning speed is 900mm / min, one layer is clad, and the single layer cladding thickness is 1.0mm; the cladding power of the cover cladding is 2.5KW, the scanning speed is 900mm / min, two layers are clad, and the single layer cladding thickness is 0.9mm;

[0041] (4) The sleeve is put into the heat treatment furnace for annealing at a temperature of 530°C. After reaching the temperature, it is kept warm for 6 hours. The workpiece is slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled;

[0042] (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

[0043] In this embodiment: Since the thickness of the flat surface cladding is relatively thick, the stress generated by the cladding is relatively large. At this time, the flat surface is divided into two layers of cladding, namely, the base layer and the cover layer. In addition, there are two flat surfaces on each side, so the four flat surfaces are clad alternately in the manner of the upper left, then the lower left, then the upper right, and finally the lower right. In this way, the base layer has time to fully release the stress before the cover cladding, reducing the crack defects caused by the stress concentration of the cladding layer, and greatly reducing the cracking risk of multi-layer superimposed cladding. At the same time, the base layer (cover layer) is kept warm and slowly cooled under the action of the heating belt, so that the cladding surface gradually releases the stress to avoid cracking of the cladding layer caused by rapid cooling; therefore, the thickness of the cladding layer can reach 15mm without cracking, pores and other defects. During the cladding process, the cladding sequence of upper left → lower left → upper right → lower right is realized by the up and down movement of the optical head + 180° rotation of the sleeve, avoiding damage to the optical head due to rotation, and greatly improving the efficiency. Of course, the specific cladding order can be adjusted, but as long as it is layered and alternating cladding, it should be within the protection scope of this application.

[0044] The advantages of the laser cladding repair method of the present invention are: first, when the flat surface cladding thickness is relatively thick, the cladding layer is divided into two layers, the bottom surface and the cover surface, and the two (four) flat surfaces are clad alternately. This layered + alternating cladding method allows the cladding layer that has been clad to have time to fully release stress, thereby reducing crack defects caused by stress concentration in the cladding layer; at the same time, during the cladding process, the sleeve is continuously heated by winding the heating belt, so that the bottom layer (cover surface layer) can be kept warm and cooled slowly, and the cladding surface gradually releases stress to avoid cracking of the cladding layer caused by rapid cooling; therefore, the flat surface The thickness of the superimposed cladding can reach 15mm; second, the base layer increases the bonding strength between the cladding layer and the substrate, and through the selection of materials, the strength of the cladding layer is gradually improved from the substrate, the packaging surface, and the cover surface, ensuring the reliable connection between the cladding layer and the substrate, improving the hardness of the cladding layer and its wear resistance, thereby extending the service life of the sleeve; third, a heat treatment furnace is used for preheating before cladding to reduce the temperature difference during cladding and reduce the possibility of cracking; fourth, after the cladding is completed, the sleeve is annealed as a whole to remove the stress inside the cladding layer to prevent the cladding layer from cracking due to excessive cooling rate.

[0045] In summary, the laser cladding repair method of the present invention fully releases stress during cladding and performs corresponding treatments to avoid cracking before and after cladding, so that the stress inside the cladding layer during and after the cladding is completed can be fully reduced, and the occurrence of cracking of the cladding layer caused by excessive internal stress during laser cladding and excessive residual stress inside the cladding layer during boring and milling of the sleeve can be avoided, thereby improving the one-time success rate of the sleeve cladding, eliminating the need for rework and reducing the cost of the sleeve. The thickness of the cladding layer in the present invention can reach 15 mm.

Claims

1. The laser cladding repair method of the heavy-loaded universal joint sleeve has the following specific steps:

1. Preheat the sleeve in a heat treatment furnace: the preheating temperature is 200-250℃, and the sleeve is kept warm for 4 hours; 2. Wrap the outer circle of the sleeve with a heating tape to continuously heat the sleeve during the cladding process; 3. Use an inner hole laser head to alternately laser clad the two symmetrical flat surfaces of the sleeve; 4. Anneal the sleeve as a whole in the furnace: the annealing temperature is 500-550℃, and the sleeve is kept warm for 5-7 hours, and then slowly cooled with the furnace. When the temperature is lower than 100℃, the sleeve is air-cooled out of the furnace.

2. The laser cladding repair method according to claim 1 is characterized in that: in step three: when the cladding thickness of the two flat surfaces of the sleeve is thin, one flat surface is clad first and then the other flat surface is clad.

3. The laser cladding repair method according to claim 1 is characterized in that: in step three: when the cladding thickness of the two flat surfaces of the sleeve is relatively thick and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the left flat surface and the right flat surface, the cover layer is also clad in the above order.

4. The laser cladding repair method according to claim 1 is characterized in that: in step three: when the cladding thickness of the four flat surfaces of the sleeve is relatively thick and the cladding layer is divided into a base layer and a cover layer, an alternating cladding method is adopted: after the base layer is clad in the order of the upper left flat surface, the lower right flat surface, the lower left flat surface, and the upper right flat surface, the cover layer is also clad in the above order.

5. The laser cladding repair method according to claim 1 is characterized in that: in step three: the base cladding material is a wear-resistant stainless steel material, and its chemical composition and mass percentage are: 15-18.5% Cr, 0.8-1.5% Ni, 0.6-1.2% Mo, 0.8-1.2% B, 0.6-1.5% Si, <0.5% C, <0.8% Mn, and the balance is Fe; the cover cladding material is a high-strength wear-resistant stainless steel material, and its chemical composition and mass percentage are 14-17% Cr, 1.4-2.4% Ni, 0.8-1.2% Mo, 1.0-1.5% B, 1.4-1.7% Si, <0.5% C, <1.0% Mn, and the balance is Fe.

6. The laser cladding repair method according to claim 2 is characterized in that: The sleeve has two symmetrical flat surfaces: surface A and surface B. The flat surface repair size is 1mm. The laser cladding repair method is as follows: (1) Preheat the sleeve in a heat treatment furnace at 200°C for 4 hours; (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the cladding robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation; (3) Use an inner hole laser head for laser cladding: first clad the A surface, then rotate the sleeve 180° to clad the B surface; the cladding material is high-strength and wear-resistant stainless steel; Cladding power 3.0KW, scanning speed 900mm / min, single layer cladding thickness 1.5mm; (4) The sleeve is put into a heat treatment furnace for annealing at a temperature of 500°C. After reaching the temperature, it is kept at this temperature for 6 hours and then slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled. (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

7. The laser cladding repair method according to claim 3 is characterized in that: The sleeve has two symmetrical flat surfaces: surface C and surface D. The flat surface repair size is 5mm. The laser cladding repair method is as follows: (1) Preheat the sleeve in a heat treatment furnace at 200°C for 4 hours; (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation; (3) Use the inner hole laser head to perform laser cladding in an alternating cladding manner. Each flat surface is divided into bottom cladding and cover cladding: first perform bottom cladding on the C surface, then rotate the sleeve 180° to perform bottom cladding on the D surface, then rotate the sleeve 180° to perform cover cladding on the C surface, and finally rotate the sleeve 180° to perform cover cladding on the D surface; the cladding power of bottom cladding is 2.8KW, the scanning speed is 900mm / min, the total cladding is three layers, and the single layer cladding thickness is 1.3mm; the cladding power of cover cladding is 2.5KW, the scanning speed is 900mm / min, the total cladding is two layers, and the single layer cladding thickness is 0.9mm; (4) The sleeve is put into the heat treatment furnace for annealing at a temperature of 550°C. After reaching the temperature, it is kept warm for 7 hours. The workpiece is slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled; (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

8. The laser cladding repair method according to claim 4 is characterized in that: The sleeve has four flat surfaces: upper left, lower left, upper right, and lower right: E surface, F surface, G surface, and H surface. The flat surface repair size is 2mm: The laser cladding repair method at this time is as follows: (1) Preheat the sleeve in a heat treatment furnace at 250°C for 4 hours; (2) The preheated sleeve is hoisted onto the roller frame, and the height of the roller frame is adjusted to meet the requirements of the robot; the outer circle of the sleeve is wrapped with a heating belt for continuous heating, and the outer surface of the heating belt is covered with an asbestos blanket for insulation; (3) Use the inner hole laser head to perform laser cladding in an alternating cladding manner. Each flat surface is divided into bottom cladding and cover cladding: bottom cladding is: first perform bottom cladding on the E surface, then perform bottom cladding on the F surface; after rotating the sleeve 180°, first perform bottom cladding on the G surface, then perform bottom cladding on the H surface; the order of cover cladding is the same as that of bottom cladding; the cladding power of the bottom cladding material is 2.5KW, the scanning speed is 900mm / min, one layer is clad, and the single layer cladding thickness is 1.0mm; the cladding power of the cover cladding is 2.5KW, the scanning speed is 900mm / min, two layers are clad, and the single layer cladding thickness is 0.9mm; (4) The sleeve is put into the heat treatment furnace for annealing at a temperature of 530°C. After reaching the temperature, it is kept warm for 6 hours. The workpiece is slowly cooled with the furnace. When the temperature is lower than 100°C, it is taken out of the furnace and air-cooled; (5) The cladding surface is polished to remove the oxide scale and slag, and the cladding layer is subjected to flaw detection and hardness testing.

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