Method for repairing broken tooth damage of gear
By combining machining and laser cladding, the problems of low efficiency and insufficient precision in gear tooth repair have been solved, achieving high-precision and high-performance gear repair and adapting to the repair needs of different gears.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-02-25
- Publication Date
- 2026-05-12
AI Technical Summary
Existing methods for repairing broken gear teeth suffer from low processing efficiency, difficulty in ensuring tooth profile accuracy, and difficulty in simultaneously meeting the performance requirements of the inner and outer sides of the gear.
The broken tooth area of the gear is removed by machining, and a groove is constructed on the inner side as a base surface. Gradient composition design is carried out using laser cladding technology, and the material is filled layer by layer and heat treated to achieve a continuous transition of material and performance, thereby improving the tooth profile accuracy and bonding strength.
It achieves high-precision repair of broken gear teeth, improves material utilization and the performance of the repaired gear, reduces finishing steps, and adapts to the repair needs of different gears.
Smart Images
Figure CN122013174A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of laser cladding remanufacturing technology and relates to a method for repairing broken gear teeth. Background Technology
[0002] Gears are a typical transmission component, widely used in aerospace, automotive manufacturing, and other fields. Gear manufacturing is complex and costly, but gears often operate under harsh conditions such as high temperatures and high loads. Coupled with improper human operation, they are highly susceptible to wear, pitting, and other failures, and in severe cases, tooth breakage, leading to direct scrapping and significant economic losses. Repairing broken gear teeth not only offers economic benefits but also contributes to environmental protection. Laser cladding technology is an advanced remanufacturing technique; due to its small heat-affected zone and excellent bonding performance, it is currently the mainstream method for gear repair.
[0003] For the repair of broken gear teeth, the patent "A Method for Laser Cladding Repair of Gears" (CN114686878A) provides a method for repairing broken gear teeth by laser cladding. This method involves cladding layer by layer and milling to meet the height requirements of each layer, thus completing the repair. Its advantages include reducing residual stress by calibrating the height of each cladding layer, solving the problems of interlayer cumulative error and post-repair spot dispersion. Its disadvantages include the need for alternating laser cladding / height calibration and milling layer by layer, resulting in complex calculations and operations, low processing efficiency, and difficulty in guaranteeing the accuracy of the involute surface. The patent "A Method for Repairing Broken Gears Based on Laser Cladding Technology" (CN120608278A) invented a method for repairing broken gear teeth in coal mine machinery. Its advantages include extending the service life of the gears and expanding their lifespan. However, its disadvantages include unclear repair process paths and schemes, and differences in the properties of the substrate and powder.
[0004] In summary, existing methods for repairing broken teeth still suffer from problems such as low processing efficiency and difficulty in ensuring tooth profile accuracy. Furthermore, they cannot simultaneously meet the different performance requirements of the inner and outer sides of the gear. Therefore, it is necessary to invent a broken tooth repair method that can achieve a continuous transition between materials and performance, so as to improve the tooth profile accuracy and gear performance after repair and achieve efficient resource utilization. Summary of the Invention
[0005] To address the problems of existing technologies and improve the tooth profile accuracy and bonding strength between the gear base and the repair layer after repairing broken involute gears, this invention provides a method for repairing broken gear teeth. This method first uses machining to completely remove all areas of the broken gear tooth, continuing the removal inwards. A smooth, defect-free groove parallel to the gear axis is constructed on the inner side of the tooth root circle. Gear parameters are collected, and this bottom surface is used as a base. After filling the groove, laser cladding is performed to obtain an approximately trapezoidal basic tooth profile, with a certain amount of cladding allowance reserved on both sides of the cladding layer edge. A gradient composition design using iron-based and nickel-based powders is employed for tooth lateral cladding additive manufacturing, resulting in a gradient cladding layer with gradually changing powder concentration. After cladding, the tooth surface is reshaped, removing excess cladding and undergoing heat treatment. The gradient cladding layer allows for a continuous transition in composition and properties, reducing crack formation and thus achieving efficient and high-performance repair of broken gear teeth. This repair method can make the gear tooth profile more in line with the shape of an involute, reduce the collapse of the cladding edge, reduce tooth profile error, reduce subsequent milling and finishing time, improve the performance of the repaired gear, and can be adapted to the repair of different gears, thus achieving resource saving and efficient use of materials.
[0006] The technical solution adopted in this invention is as follows: A method for repairing broken gear teeth involves first removing all areas of the broken tooth to be repaired through machining, continuing the inward cutting to create a groove with its bottom surface parallel to the gear axis on the inner side of the tooth root circle. The gear substrate is preheated, and using this bottom surface as a base, optimal process parameters are applied using a multi-pass, multi-layer process to clad the basic tooth profile, resulting in an approximately trapezoidal basic tooth profile, reserving cladding allowance for subsequent laser cladding. With the laser head vertical and the tooth flank tilted, appropriate process parameters are selected for additive cladding of the tooth flank, preparing a gradient cladding layer to simultaneously meet the performance requirements of the gear's internal and external surfaces. The repaired tooth is then reshaped and heat-treated to complete the repair of the broken gear tooth. The specific steps are as follows: Step 1: Pre-process the gears Using machining methods, all areas of the broken tooth to be repaired on the gear are removed, and the cutting continues inward to obtain a groove with the bottom surface parallel to the gear axis in the root circle. This surface is then finished by grinding with a grinding wheel, cleaned with acetone, and dried to ensure that there is no waste material or solution residue. Step 2: Perform basic tooth profile cladding on the broken gear teeth. Based on the material of the gear to be repaired, iron-based powder is selected. The alloy powder and the gear substrate to be repaired are preheated to reduce the generation of cracks. The process parameters are adjusted, and the bottom surface of the obtained groove is used as the base surface. The laser head is perpendicular to the base surface. The basic tooth shape is clad using a multi-pass, multi-layer cladding method. The part removed from the inner side of the tooth root circle is filled to obtain an approximately trapezoidal basic tooth shape. The tooth thickness is slightly less than the design value, i.e., a cladding allowance is reserved. Step 3: Perform additive manufacturing by cladding the tooth surfaces. Two materials that meet the performance requirements of the inner and outer sides of the gear are selected for gradient composition design. Laser cladding is performed on both sides of the tooth surface to obtain a gradient cladding layer to supplement the cladding allowance reserved in step 2. After preheating the powder, the laser head is vertical and the tooth side is tilted relative to each other. The laser head is scanned from bottom to top in an overlapping manner to avoid interference between the laser head and the gear and reduce the influence of gravity, so that the molten pool remains stable. Laser cladding is performed using the best process parameters. After completion, the gear is turned around to perform cladding additive manufacturing on the other side of the tooth surface. After the laser cladding is completed, the machining allowance on the tooth surface is removed. Step 4: Perform post-processing and performance testing. The clad gears are heat-treated to improve the strength, hardness, and other properties of the repair layer and reduce residual stress. After the heat treatment process, the repair layer is precision-machined using high-precision milling machines and profile grinding machines to further improve the tooth profile accuracy. After the precision machining is completed, the repaired area is subjected to performance testing to ensure that it meets the usage standards.
[0007] The beneficial effects of this invention are: This paper presents a solution to the problem of low tooth profile accuracy and weak bonding strength after gear tooth repair. By employing a layered and zoned cladding method, first performing basic tooth profile cladding, and then performing additive cladding on the tooth flanks, the paper not only achieves control over the forming accuracy of the repaired tooth and improves the tooth surface performance and bonding strength, but also reduces finishing steps, thereby saving metal materials and social resources. This method is highly targeted and achieves high-performance, high-precision repair of broken gear teeth. Attached Figure Description
[0008] Figure 1 This is a basic flowchart of the present invention; Figure 2 A schematic diagram showing the complete removal of the broken tooth and the resulting groove; Figure 3 A schematic diagram of the basic tooth-shaped cladding area; Figure 4 This is a schematic diagram showing the relative positions of the laser head and the gear; Figure 5 This is a schematic diagram of the cladding additive manufacturing area on the tooth side. Figure 6This is a schematic diagram after removing the machining allowance from the tooth surface. Detailed Implementation
[0009] The present invention will be further described in detail below with reference to the accompanying drawings and technical solutions.
[0010] The basic process of a gear tooth breakage repair method of the present invention is as follows: Figure 1 As shown. The gear to be repaired in this embodiment is a standard spur gear with a module of 4 and 16 teeth, made of 45 steel, and the repair layer material is Ni60A powder and 316L powder. The specific steps are as follows: Step 1: Pre-process the gears For the gear tooth breakage damage in this embodiment, a machining method is used to completely remove all areas of the broken tooth to be repaired, resulting in a groove, such as... Figure 2 As shown, the bottom surface of the groove is a horizontal plane parallel to the gear axis. This surface is finished by grinding with a grinding wheel, cleaned with acetone solution and dried to ensure that there is no waste residue. Step 2: Perform basic tooth profile cladding on the broken gear teeth. This embodiment uses 316L powder (45-180μm) to repair broken teeth on a 45 steel gear. High-purity argon (99.99%) is used as both the protective gas and the powder feeding gas. A coaxial powder-feeding laser cladding device is used for cladding. The 316L powder is dried at 80℃ for two hours, cooled, and then poured into the powder feeder. The gear to be repaired is preheated. Optimal process parameters are shown in the schematic diagram. Figure 2 The bottom surface of the groove is used as the base surface for laser cladding. The portion removed from the inner side of the tooth root circle is filled, and a layer-by-layer reduction cladding method is used to obtain the basic tooth shape, such as... Figure 3 As shown; Step 3: Perform tooth surface cladding additive manufacturing using a gradient structure material system. This embodiment uses a gradient structure composed of Ni60A powder and 316L powder, with 316L powder on the inner side and Ni60A powder on the outer side. This compositional gradient ensures both the toughness of the inner side and the hardness of the outer side of the gear. After preheating and drying the powder, laser cladding is performed using a unidirectional scanning method with the laser head vertical and the tooth surface tilted, overlapping from bottom to top. Figure 4 and Figure 5 As shown, after the cladding is completed, the gear is turned around, and the above operation in step 3 is repeated on the other side of the tooth surface to remove the machining allowance; after removal, as shown... Figure 6 As shown; Step 4: Perform post-processing and quality inspection on the gear repair area. The repaired gears underwent heat treatment and precision machining: After the cladding gears cooled to room temperature, the tooth surfaces were preliminarily trimmed using a CNC precision milling machine, and the gears were then subjected to quenching and tempering processes to reduce residual stress. The repaired areas were then precision ground to improve the tooth profile accuracy. After machining was completed, the gears were inspected, and the results showed that all indicators met the usage requirements.
[0011] In summary, the method of this invention achieves high-precision repair of broken gear teeth, improves material utilization and the performance of the repaired gear.
Claims
1. A method for repairing broken gear teeth, characterized in that, First, all areas of the broken tooth to be repaired on the gear are removed by machining, and the cutting continues inward to obtain a groove with a bottom surface parallel to the gear axis on the inner side of the tooth root circle. The gear base is preheated, and the bottom surface is used as the base surface. Combined with the original design parameters of the gear, the basic tooth profile is clad in a multi-pass, multi-layer manner using the optimal process parameters to obtain an approximately trapezoidal basic tooth profile, reserving cladding allowance for subsequent laser cladding processing. With the laser head vertical and the tooth side surface tilted, appropriate process parameters are selected to perform tooth side surface cladding additive manufacturing to prepare a gradient cladding layer to simultaneously meet the performance requirements of the gear inside and out. The repair tooth is then shaped and heat-treated to complete the repair of the broken gear tooth.
2. The method for repairing broken gear teeth according to claim 1, characterized in that, The specific steps are as follows: Step 1: Pre-process the gears Using machining methods, all areas of the broken tooth to be repaired on the gear are removed, and the cutting continues inward to obtain a groove with the bottom surface parallel to the gear axis in the root circle. This surface is then finished by grinding with a grinding wheel, cleaned with acetone, and dried to ensure that there is no waste material or solution residue. Step 2: Perform basic tooth profile cladding on the broken gear teeth. Based on the material of the gear to be repaired, iron-based powder is selected. The alloy powder and the gear substrate to be repaired are preheated to reduce the generation of cracks. The process parameters are adjusted, and the bottom surface of the obtained groove is used as the base surface. The laser head is perpendicular to the base surface. The basic tooth shape is clad using a multi-pass, multi-layer cladding method. The part removed from the inner side of the tooth root circle is filled to obtain an approximately trapezoidal basic tooth shape, i.e., a cladding allowance is reserved. Step 3: Perform additive manufacturing by cladding the tooth surfaces. Two materials that meet the performance requirements of the inner and outer sides of the gear are selected for gradient composition design. Laser cladding is performed on both sides of the tooth surface to obtain a gradient cladding layer to supplement the cladding allowance reserved in step 2. After preheating the powder, the laser head is vertical and the tooth side is tilted relative to each other. The laser head is scanned from bottom to top in an overlapping manner to avoid interference between the laser head and the gear and reduce the influence of gravity, so that the molten pool remains stable. Laser cladding is performed using the best process parameters. After completion, the gear is turned around to perform cladding additive manufacturing on the other side of the tooth surface. After the laser cladding is completed, the machining allowance on the tooth surface is removed. Step 4: Perform post-processing and performance testing. The clad gears are heat-treated to improve the strength and hardness of the repair layer and reduce residual stress. After the heat treatment process, the repair layer is precision-machined using high-precision milling machines and profile grinding machines to further improve the tooth profile accuracy. After the precision machining is completed, the repaired area is subjected to performance testing to ensure that it meets the usage standards.
3. The method for repairing broken gear teeth according to claim 2, characterized in that, In step 2, the tooth thickness of the basic tooth profile is less than the design value.