Laser repairing method for pitted hole of gear

Abstract

The invention provides a laser repairing method for a gear pitted hole, which comprises the following steps: S100, cleaning the pitted hole on a tooth surface, and drying the cleaned pitted hole, the gear being made of alloy steel; s200, the pitting corrosion hole is filled with a modified metal material, first laser cladding treatment is conducted on the pitting corrosion hole so that a transition layer can be formed in the pitting corrosion hole, and the melting point of the modified metal material is lower than that of the alloy steel; s300, carrying out second laser cladding treatment on the pitting corrosion hole to form a cladding layer, wherein the cladding layer is higher than the tooth surface; and S400, the cladding layer is polished so that the cladding layer can be flush with the tooth surface. According to the laser repairing method for the gear pitted hole, the problem that residual water in the pitted hole forms a hole in the cladding layer is solved, gas in the molten pool can be driven to be discharged through flowing of two different melts, the risk that the hole is formed in the cladding layer is reduced, and the laser repairing quality of the gear pitted hole is remarkably improved.

Description

Technical Field

[0001] The invention generally relates to the technical field of gear repair, and in particular to a laser repair method for gear pitting holes. Background Art

[0002] As one of the precision transmission components in high-speed rail equipment, the reliability of gears has a direct relationship with the safety of high-speed rail operation. With the long-term and frequent operation of high-speed rail equipment, some gears have pitting problems, such as the formation of pitting holes on the tooth surface. In order to solve the above pitting hole problem, it can be repaired by laser cladding in the prior art. The laser repair steps for the pitting holes on the tooth surface are usually: first clean and dry the pitting holes and their surroundings, and then perform laser cladding on the pitting holes.

[0003] However, during the laser cladding process of the pitting holes on the tooth surface, due to the short time from the formation of the molten pool to the cooling and solidification, the residual gas in the molten pool may not be discharged in time, resulting in holes in the formed cladding layer, which affects the laser repair effect of the pitting holes on the tooth surface. At the same time, for pitting holes with complex structures in the holes, there may be residual moisture in the cleaning and drying process, which will also cause holes in the cladding layer. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a laser repair method for gear pitting holes.

[0005] The present application provides a laser repair method for gear pitting holes, comprising: S100: cleaning the pitting holes on the tooth surface and drying the cleaned pitting holes, wherein the gear is made of alloy steel; S200: filling the pitting hole with a modified metal material, and performing a first laser cladding process on the pitting hole to form a transition layer in the pitting hole, wherein the melting point of the modified metal material is lower than the melting point of the alloy steel; S300: performing a second laser cladding process on the pitting hole to form a cladding layer, wherein the cladding layer is higher than the tooth surface; S400: Grind the cladding layer to make it flush with the tooth surface.

[0006] Furthermore, the modified metal material is lithium powder.

[0007] Furthermore, the volume proportion of the modified metal material in the pitting hole does not exceed 30%.

[0008] Furthermore, in the second laser cladding process, the cladding material is alloy steel powder.

[0009] Furthermore, the cladding layer is higher than the tooth surface by 0.5-1 mm.

[0010] Furthermore, the process parameters of the first laser cladding treatment are as follows: the laser energy density is 1-3 J / cm 2 , frequency is 10-20kHZ, pulse width is 50-200ns.

[0011] Furthermore, the laser energy density is 5-10 J / cm2, the frequency is 20-50 kHz, the pulse width is 100-200 ns, and the powder feeding speed is 1.0-2.0 r / min.

[0012] The laser repair method for gear pitting holes provided in the present application forms a transition layer by laser cladding in the pitting holes filled with modified metal materials, and forms a cladding layer by laser cladding in the pitting holes with the transition layer formed. This not only solves the problem of residual moisture in the pitting holes forming holes on the cladding layer, but also can use the flow of two different melts to drive the discharge of gas in the molten pool, thereby reducing the risk of holes forming in the cladding layer and significantly improving the laser repair quality of the pitting holes on the tooth surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 A flow chart of a laser repair method for gear pitting holes provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0015] Please refer to the attached Figure 1 The embodiment of the present application provides a laser repair method for gear pitting holes, which is used for laser repairing pitting holes on the tooth surface. The gear is made of alloy steel, and the alloy steel does not contain lithium, such as but not limited to 20CrMnTi alloy steel or 18CrNiMo7-6 alloy steel.

[0016] Laser repair methods for gear pitting holes include: S100: cleaning the pitting holes on the tooth surface and drying the cleaned pitting holes. The cleaning process includes alcohol ultrasonic cleaning, acetone ultrasonic cleaning, etc., and the drying process includes heat drying, etc.

[0017] S200: Fill the pitting hole with a modified metal material, and perform a first laser cladding treatment on the pitting hole to form a transition layer in the pitting hole, wherein the melting point of the modified metal material is lower than the melting point of the alloy steel. Specifically: In the first laser cladding treatment, the laser head acts on a local position in the pitting hole and the modified metal material is deposited at the position. The modified metal material and the surface of the hole wall of the pitting hole are melted together under the action of the laser and form a transition layer after cooling. The transition layer includes a modified metal layer and a metallurgical bonding layer, and the metallurgical bonding layer is formed by part of the modified metal material and the surface of the hole wall of the pitting hole. Since the melting point of the modified metal material is lower than the melting point of the alloy steel, the melting point of the transition layer is lower than the melting point of the alloy steel. In addition, during the first laser cladding treatment process, the melt will at least fill the bottom of the pitting hole. If there is residual water at the bottom of the pitting hole, the water will be directly vaporized and discharged from the pitting hole under the action of the melt to avoid residual water in the pitting hole.

[0018] S300: Perform a second laser cladding treatment on the pitting hole to form a cladding layer, and the cladding layer is higher than the tooth surface. During the second laser cladding treatment, the transition layer melts before the pitting hole wall and the cladding material, and the melt formed by the transition layer during the melting of the cladding material will flow upward to drive the residual gas in the molten pool to discharge the molten pool to avoid residual gas in the molten pool. If the transition layer generates holes due to exhaust in step S200, the transition layer will be melted again in this step, so that the holes can be eliminated.

[0019] S400: Grind the cladding layer to make it flush with the tooth surface. Since the cladding layer is higher than the tooth surface and the modified metal material occupies a large proportion of the surface of the cladding layer, grinding can reduce the modified metal content in the cladding layer and improve the quality of the cladding layer.

[0020] In this embodiment, by first forming a transition layer by laser cladding in the pitting holes filled with modified metal materials, and forming a cladding layer by laser cladding in the pitting holes with the transition layer formed, the transition layer can not only remove the moisture located in the hidden corners at the bottom of the pitting holes from the pitting holes, but also flow up and down with the subsequently formed cladding melt to drive the discharge of gas in the molten pool, effectively reducing the risk of holes formed in the cladding layer, and significantly improving the laser repair quality of the pitting holes on the tooth surface.

[0021] Wherein, preferably, the modified metal material is lithium powder, the average diameter of the lithium powder can be less than 10% of the average pore size of the pitting hole, and its particle size is usually 10-30μm. The average pore size of the pitting hole can be obtained by scanning and measuring with a scanner. Lithium powder has a lower melting point than alloy steel, so that the molten droplets of the transition layer are lower than the melting point of the alloy steel. At the same time, lithium powder also has a smaller density, so that the melt formed by the melting of the transition layer has a lower density than the melt formed by the cladding material and the alloy steel, which helps the up and down flow between the melts. The volume proportion of the modified metal material in the pitting hole does not exceed 30%, for example, 15%, 20%, etc., to control the coverage area of ​​the transition layer in the pitting hole and reduce the content of the modified metal material in the cladding layer.

[0022] Preferably, the cladding layer is higher than the tooth surface by 0.5-1 mm, so that a balance can be achieved between the amount of modified metal material removed and the reduction of grinding workload.

[0023] The cladding material used in the second laser cladding process is aluminum alloy powder, which is the same material as the gear and has good bonding. The particle size of the aluminum alloy powder is 100-200 μm.

[0024] The process parameters of the first laser cladding treatment are as follows: the laser energy density is 1-3 J / cm 2 , frequency is 10-20kHZ, pulse width is 50-200ns. The process parameters of the second laser cladding treatment are as follows: laser energy density is 5-10J / cm2, frequency is 20-50kHZ, pulse width is 100-200ns, and powder feeding speed is 1.0-2.0r / min.

[0025] It should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used above to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means more than two.

[0026] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A laser repair method for gear pitting holes, characterized in that: include: S100: cleaning the pitting holes on the tooth surface, and drying the cleaned pitting holes, wherein the gear is made of alloy steel; S200: filling the pitting hole with a modified metal material, and performing a first laser cladding process on the pitting hole to form a transition layer in the pitting hole, wherein the melting point of the modified metal material is lower than the melting point of the alloy steel; S300: performing a second laser cladding process on the pitting hole to form a cladding layer, wherein the cladding layer is higher than the tooth surface; S400: Grinding the cladding layer to make the cladding layer flush with the tooth surface.

2. The laser repair method for gear pitting according to claim 1, characterized in that: The modified metal material is lithium powder.

3. The laser repair method for gear pitting according to claim 1, characterized in that: The volume proportion of the modified metal material in the pitting holes does not exceed 30%.

4. The laser repair method for gear pitting according to claim 1, characterized in that: In the second laser cladding process, the cladding material is alloy steel powder.

5. The laser repair method for gear pitting according to claim 1, characterized in that: The cladding layer is higher than the tooth surface by 0.5-1 mm.

6. The laser repair method for gear pitting according to claim 1, characterized in that: The process parameters of the first laser cladding treatment are as follows: the laser energy density is 1-3 J / cm 2 , frequency is 10-20kHZ, pulse width is 50-200ns.

7. The laser repair method for gear pitting according to claim 1, characterized in that: The laser energy density is 5-10J / cm2, the frequency is 20-50kHZ, the pulse width is 100-200ns, and the powder feeding speed is 1.0-2.0r / min.

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