Gear surface strengthening method, gear and transmission system

Abstract

The invention relates to the technical field of machining, and provides a gear surface strengthening method and a gear, and according to the strengthening method provided by the invention, for special workpieces such as large gears, laser shock strengthening and laser quenching are used for meeting the treatment requirements of workpieces of different sizes. And the composite strengthened layer is obtained through laser shock strengthening and laser quenching, so that the hardness and the wear resistance of the material are improved, and the anti-fatigue performance of the material is also improved.

Description

Technical Field

[0001] The present application relates to the field of mechanical processing technology, and in particular to a gear surface strengthening method, a gear and a transmission system. Background Art

[0002] Gears, as a basic mechanical transmission element, are widely used in various mechanical equipment. Their main function is to transmit motion and power. Among them, large gears play an important role in engineering machinery. For example, in the transmission systems of shield machines, cranes, wind turbines and other equipment, large gears can transmit powerful power and torque to ensure the normal operation of the machinery. The surface treatment of large gears often requires special equipment and processes, and the overall treatment requires a longer time period. In addition, the heat distribution and cooling speed are difficult to control, which affects the microstructure and performance of the gears. Summary of the invention

[0003] In view of this, the present application provides a gear surface strengthening method, a gear and a transmission system, the purpose of which is to solve the above technical problems to a certain extent.

[0004] A first aspect of the present application provides a method for strengthening a gear surface, the strengthening method comprising:

[0005] Divide the gear into a plurality of equal division areas in the circumferential direction, and perform laser shock strengthening on each division area to form a shock strengthening layer, wherein the overlap rate of the laser shock strengthening is 10-40%;

[0006] Laser quenching is performed on each graduated area to form a quenching strengthening layer, wherein the overlap rate of the laser quenching is 20-60%.

[0007] On the basis of the above technical solution, optionally, performing laser shock peening on each graduated area to form a shock-peened layer further comprises:

[0008] The pulse energy of the laser shock peening is 8-15J, and the spot diameter is 1-3mm.

[0009] Based on any of the above technical solutions, optionally, dividing the gear into a plurality of equal division areas in the circumferential direction further comprises: each division area includes a tooth top, a tooth surface and a tooth groove of a same tooth of the gear;

[0010] The performing laser shock peening on each graduated area to form a shock-peened layer further comprises: applying different pulse energies to the tooth top, tooth surface and tooth groove.

[0011] Based on any of the above technical solutions, optionally, performing laser shock peening on each graduated area to form a shock-peened layer further comprises:

[0012] The impact angles of the laser shock peening on the tooth top, tooth surface and tooth groove are all within the range of 0-45°.

[0013] Based on any of the above technical solutions, optionally, performing laser quenching on each graduated area to form a quenching strengthening layer further comprises:

[0014] The laser power of the laser quenching is 1000W-1600W.

[0015] Based on any of the above technical solutions, optionally, performing laser quenching on each graduated area to form a quenching strengthening layer further comprises:

[0016] The laser continuously scans the surface within each graduation area to perform the laser quenching.

[0017] Based on any of the above technical solutions, optionally, the strengthening method further includes:

[0018] Before performing the laser shock peening, an energy absorbing coating is provided on the surface of the gear, wherein the energy absorbing coating is configured to absorb energy of the laser;

[0019] After the laser shock peening, the energy absorbing coating on the gear surface is removed.

[0020] Based on any of the above technical solutions, optionally, performing laser shock peening on each graduated area to form a shock-peened layer further comprises:

[0021] Deionized water is used to provide a constrained layer for the laser shock peening, and the thickness of the constrained layer is 1-2 mm.

[0022] In a second aspect, the present application provides a gear, wherein the gear is manufactured by the above gear surface strengthening method.

[0023] In a third aspect, the present application provides a transmission system, which includes the gears as above.

[0024] According to the strengthening method provided by the present application, laser shock strengthening and laser quenching can be used to process special workpieces such as large gears to meet the needs of workpieces of different sizes. The composite strengthening layer obtained by laser shock strengthening and laser quenching not only improves the hardness and wear resistance of the material, but also improves the fatigue resistance of the material.

[0025] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram showing a flow chart of a method for strengthening a gear surface provided according to an embodiment of the present application;

[0028] Figure 2 A schematic diagram showing a three-dimensional diagram of an execution device of a gear surface strengthening method provided in an embodiment of the present application;

[0029] Figure 3 A schematic diagram showing a gear partition according to a gear surface strengthening method provided in an embodiment of the present application;

[0030] Figure 4 A schematic diagram showing laser shock strengthening of a gear surface strengthening method provided in an embodiment of the present application is shown;

[0031] Figure 5 The residual stress variation diagram under different treatment processes is shown. DETAILED DESCRIPTION

[0032] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application 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 application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0036] According to an embodiment of the present application, a method for strengthening the surface of a gear is provided. The following processing and the accompanying drawings are used to specifically describe the steps and working principles of the strengthening method.

[0037] According to the strengthening method provided in the embodiment of the present application, the strengthening method includes:

[0038] Divide the gear into a plurality of graduated areas in a circumferential direction, and perform laser shock peening on each graduated area to form a shock peening layer, wherein the overlap rate of the laser shock peening is 10-40%;

[0039] Laser quenching is performed on each graduated area to form a quenching strengthening layer, wherein the overlap rate of the laser quenching is 20-60%.

[0040] Thus, according to the strengthening method provided in the embodiment of the present application, laser shock strengthening and laser quenching can be used to process special workpieces such as large gears to meet the needs of workpieces of different sizes. The composite strengthening layer obtained by laser shock strengthening and laser quenching not only improves the hardness and wear resistance of the material, but also improves the fatigue resistance of the material.

[0041] In the embodiment, as an example, the overlap rate of the laser shock peening is 20% or 30%.

[0042] In an embodiment, as an example, the overlap rate of laser quenching is 30%, 40% or 50%.

[0043] In the embodiment, laser quenching is an advanced quenching technology that uses a high-energy laser beam to irradiate the surface of the material, so that the surface temperature rises rapidly to above the phase transition point (but below the melting point). Due to the good thermal conductivity of the metal, when the laser beam is removed, the material cools rapidly by itself without contamination by the quenching cooling medium. By changing the organizational structure of the material surface, the hardness and wear resistance are improved.

[0044] In the embodiment, the laser shock peening technology is a method of strengthening the metal surface by irradiating the metal surface with a high-energy pulsed laser to generate a high-temperature and high-pressure plasma, thereby forming a shock wave on the metal surface. In the laser shock peening process, an absorption layer and a constraint layer are usually used to optimize the strengthening effect. The fatigue performance and service life of the material can be significantly improved. Moreover, since the laser shock technology is a non-contact technology, it has little effect on the surface roughness of the material, avoiding damage and contamination to the material.

[0045] Both methods use laser as energy to process the surface of the material, so both can achieve precise control over the energy input. Secondly, due to the technical characteristics of laser shock and laser quenching themselves, precise control of the strengthened area can be achieved.

[0046] According to the strengthening method provided in the embodiment of the present application, performing laser shock strengthening on each graduated area to form a shock strengthened layer may also include: the pulse energy of the laser shock strengthening is 8-15J, and the spot diameter is 1-3mm.

[0047] According to the strengthening method provided in an embodiment of the present application, dividing the gear into a plurality of equal graduation areas in the circumferential direction also includes: each graduation area includes the tooth top, tooth surface and tooth groove of the same tooth of the gear; performing laser shock strengthening on each graduation area to form an impact strengthening layer also includes: applying different pulse energies to the tooth top, tooth surface and tooth groove.

[0048] According to the strengthening method provided in the embodiment of the present application, laser shock strengthening is performed on each graduated area to form a shock strengthened layer, and the impact angles of the laser shock strengthening on the tooth top, tooth surface and tooth groove are all within the range of 0-45°.

[0049] According to the strengthening method provided in the embodiment of the present application, performing laser quenching on each graduated area to form a quenching strengthening layer also includes: the laser power of the laser quenching is 1000W-1600W.

[0050] According to the strengthening method provided in the embodiment of the present application, performing laser quenching on each graduated area to form a quenched and strengthened layer further includes: continuously scanning the surface in each graduated area with a laser to perform laser quenching.

[0051] According to the strengthening method provided in an embodiment of the present application, the strengthening method further includes: before performing laser shock strengthening, providing an energy absorbing coating on the surface of the gear, wherein the energy absorbing coating is configured to absorb the energy of the laser.

[0052] According to the strengthening method provided in the embodiment of the present application, performing laser shock strengthening on each graduated area to form a shock strengthened layer also includes: using deionized water to provide a constrained layer for laser shock strengthening, and the thickness of the constrained layer is 1-2 mm.

[0053] According to the strengthening method provided in an embodiment of the present application, the strengthening method further includes: after laser shock strengthening, removing the energy absorbing coating on the surface of the gear.

[0054] Based on the above description of the enhancement method, the execution process of the enhancement method is further described below.

[0055] The device for executing the strengthening method includes a laser strengthening system, a clamping system and an infrared positioning system, specifically including a robotic arm 1, an infrared positioning device 2, a laser impact device 3, a laser quenching device 4, a three-jaw chuck 5 and a gear 6.

[0056] The three-jaw chuck 5 in the clamping system is responsible for fixing the gear and rotating the gear, and cooperates with the laser impact device 3 and the laser quenching device 4 to process the gear 6.

[0057] The laser impact device 3 and the laser quenching device 4 are both equipped with a laser quenching head and a laser impact head by a robotic arm 1. With the assistance of the robotic arm, processing at different angles can be performed on parts with complex structures such as gears.

[0058] The infrared positioning device 2 is installed on the robot arm to assist the laser strengthening equipment in strengthening the workpiece. By scanning and positioning the gear contour, a three-dimensional gear morphology is formed, and different strengthening areas are processed in coordination with the laser strengthening system.

[0059] In the embodiment, the gear is pre-treated, the surface is cleaned, and the gear surface is sprayed with black paint as an absorption layer, which can not only absorb the energy of the high-energy laser and generate enough plasma to form a shock wave, but also protect the surface of the workpiece from being damaged. Then the gear is fixed.

[0060] In the embodiment, due to the irregular structure of the gear, the areas of the gear that need to be strengthened can be divided into tooth tops, tooth surfaces, and tooth grooves. Since the tooth tops, tooth surfaces, and tooth grooves are located at different positions of the gear, an infrared positioning system can be used to scan the three-dimensional contour of the gear, and then locate different strengthening areas respectively.

[0061] In the embodiment, the parameters of laser shock are determined according to different strengthening areas, and laser shock is performed with deionized water as a constraint layer. The gear parts are fixed with a three-jaw chuck, and the rotation of the three-jaw chuck is used in conjunction with the laser shock equipment to set the laser shock incident angle θ, pulse energy E, spot size d1, overlap rate α1 and three-jaw chuck rotation angle γ (γ=360° / Z, Z=number of teeth). According to the infrared positioning system, the different strengthening areas divided are fed back to the laser shock device, and the laser shock parameters are adjusted according to different areas. After strengthening one tooth, the three-jaw chuck is rotated with a rotation angle of γ=360° / Z, and the laser shock strengthening process is repeated. After the shock is completed, it is rotated again by γ=360° / Z until one rotation is completed to complete the strengthening of the entire gear.

[0062] In the embodiment, the gear after laser shock is subjected to secondary pretreatment, the purpose of which is mainly to clean the black paint on the surface of the gear. Ultrasonic cleaning is used to remove the residual black paint, and then drying is performed.

[0063] In the embodiment, the gear to be processed twice is fixed, and the parameters of laser quenching are selected according to the different strengthening areas located by the infrared system, mainly including laser power P, laser scanning speed v, spot size d2, overlap rate α2 and three-jaw chuck rotation angle γ, (γ=360° / Z, Z=number of teeth). As in the laser shock process, the different strengthening areas divided are fed back to the laser shock device according to the infrared positioning system, and the laser shock parameters are adjusted according to different areas. After strengthening one tooth, the three-jaw chuck is rotated, and the rotation angle is γ=360° / Z. The laser shock device strengthening process is repeated. After the shock is completed, it is rotated again by γ=360° / Z until one rotation is completed to complete the strengthening of the entire gear.

[0064] In a more specific example, a gear made of 42CrMo material is selected as the processing material, the number of gear teeth is Z=50, and the module is 2.

[0065] The first step is to ultrasonically clean the gear surface for about 10-15 minutes, then take it out and dry it.

[0066] Use a spray gun to evenly spray black paint on the gear's tooth top, tooth surface, and tooth groove. The black paint serves as an absorption layer with a thickness of about 100 μm.

[0067] The second step is to fix the gear on the work platform, use the infrared optical sensor positioning system to scan the outline of the gear, and plan three different strengthening areas of the tooth top, tooth surface, and tooth groove in the three-dimensional morphology map. The laser impact trajectory is planned by coordinating the rotating fixture with the laser impact. Turn on the pure water circulation system so that during the laser impact process, there is a 1-2mm layer of pure water on the strengthened surface as a constraint layer. The angle of the laser impact is θ, which is the angle between the laser impact direction and the vertical direction. The angles of the laser impact on the tooth top, tooth surface, and tooth groove are 0°, 45°, and 15° respectively.

[0068] The process parameters of laser shock treatment are: laser wavelength is 1064nm; pulse energy is 8-15J, laser pulse width is 15ns, spot diameter is 1-3mm, overlap rate is 10-40%, for example, if the overlap rate is set to 20%, the pulse energy acting on the tooth top is 10J, the pulse energy acting on the tooth surface is 12J, and the pulse energy acting on the tooth bottom is 8J. Since the gear is fixed on the fixture and the laser shock parameters in different areas are different, the different strengthening areas divided are fed back to the laser shock device according to the infrared positioning system, and the laser shock parameters are adjusted according to different areas. After strengthening one tooth, the three-jaw chuck is rotated at an angle of 7.2°, and the laser shock device strengthening treatment is repeated. After the shock is completed, it is rotated again by 7.2° until one circle is rotated to complete the strengthening of the entire gear.

[0069] The third step is to perform a secondary ultrasonic cleaning on the gear after laser impact and then dry it.

[0070] The fourth step is to fix the gear again, and locate the laser quenching area according to the infrared optical sensor. Since the laser parameters required for different areas are different, the laser quenching process parameters are: laser power 1000W-1600W, scanning speed 14mm / s, spot size 20mm×20mm, overlap rate 20-60%, for example, the overlap rate is set to 40%. So, like the laser shock operation, the laser power of 1600W is selected for quenching the tooth top first, the laser power of 1400W is used to treat the tooth surface, and the laser power of 1200W is used to treat the tooth groove. Since the gear is fixed on the fixture and the laser shock parameters in different areas are different, the different strengthening areas divided are fed back to the laser shock device according to the infrared positioning system, and the laser shock parameters are adjusted according to different areas. After strengthening one tooth, the three-jaw chuck is rotated, the rotation angle is 7.2°, and the laser shock device strengthening process is repeated. After the shock is completed, it is rotated again by 7.2° until one rotation is completed to complete the strengthening of the entire gear.

[0071] The composite strengthening of laser shock and laser quenching can significantly improve the residual stress, hardness and wear resistance of the material. The above technical effects are verified by performing residual stress detection and friction and wear tests on the above 42CrMo.

[0072] Table 1. Residual stress data under different treatment processes

[0073]

[0074] Through Table 1 and Figure 5 From the data, it can be concluded that the combined strengthening treatment of laser quenching and laser shock peening can make the maximum residual stress reach -849MPa, and the affected depth range can reach about 1mm. Compared with laser quenching and the combined treatment process of laser quenching and shot peening, the former has a larger residual stress value, a larger affected depth range, and a more uniform distribution of residual stress.

[0075] Friction and wear tests were carried out by treating the steel under different combined processes, and the results are shown in Tables 2 and 3.

[0076] Table 2. Dry friction coefficient table

[0077]

[0078] Table 3. Oil friction coefficient table

[0079]

[0080] Friction and wear tests were carried out on samples with different treatments. It can be seen intuitively from the data in Tables 2 and 3 that the combined strengthening method of laser quenching and laser shock can greatly improve the wear resistance of 42CrMo compared with the other two treatment methods.

[0081] According to a second aspect of an embodiment of the present application, a gear is provided. The gear is manufactured by the above method.

[0082] According to a third aspect of an embodiment of the present application, a transmission system is provided. The transmission system includes the gears as above. The transmission system may be, for example, a transmission structure in a shield machine, a crane or a wind turbine.

[0083] The above are only preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. All equivalent structural changes made by using the contents of the present application specification and drawings under the innovative concept of the present application, or directly / indirectly applied in other related technical fields are included in the protection scope of the present application.

Claims

1. A method for strengthening the surface of a gear, characterized in that: The strengthening method comprises: Divide the gear into a plurality of graduated areas in a circumferential direction, and perform laser shock strengthening on each graduated area to form a shock strengthened layer, wherein the overlap rate of the laser shock strengthening is 10-40%; Laser quenching is performed on each graduated area to form a quenching strengthening layer, wherein the overlap rate of the laser quenching is 20-60%.

2. The strengthening method according to claim 1, characterized in that: The performing laser shock peening on each graduated area to form a shock-peened layer further comprises: The pulse energy of the laser shock peening is 8-15J, and the spot diameter is 1-3mm.

3. The strengthening method according to claim 1, characterized in that: The step of equally dividing the gear in the circumferential direction into a plurality of indexing regions further comprises: each indexing region includes a tooth top, a tooth surface and a tooth groove of a same tooth of the gear; The performing laser shock peening on each graduated area to form a shock-peened layer further comprises: applying different pulse energies to the tooth top, tooth surface and tooth groove.

4. The strengthening method according to claim 3, characterized in that: The performing laser shock peening on each graduated area to form a shock-peened layer further comprises: The impact angles of the laser shock peening on the tooth top, tooth surface and tooth groove are all within the range of 0-45°.

5. The strengthening method according to claim 1, characterized in that: The performing laser quenching on each graduated area to form a quenching strengthening layer further comprises: The laser power of the laser quenching is 1000W-1600W.

6. The strengthening method according to claim 1, characterized in that: The performing laser quenching on each graduated area to form a quenching strengthening layer further comprises: The laser continuously scans the surface within each graduation area to perform the laser quenching.

7. The strengthening method according to claim 1, characterized in that: The strengthening method further comprises: Before performing the laser shock peening, an energy absorbing coating is provided on the surface of the gear, wherein the energy absorbing coating is configured to absorb energy of the laser; After the laser shock peening, the energy absorbing coating on the gear surface is removed.

8. The strengthening method according to claim 1, characterized in that: The performing laser shock peening on each graduated area to form a shock-peened layer further comprises: Deionized water is used to provide a constrained layer for the laser shock peening, and the thickness of the constrained layer is 1-2 mm.

9. A gear, characterized in that: The gear is manufactured by the gear surface strengthening method according to any one of claims 1 to 8.

10. A transmission system, characterized in that: The transmission system comprises a gear as claimed in claim 9.

Images