Composite material-steel mixed gear machining process

Abstract

The invention relates to the field of gear machining, in particular to a composite material-steel mixed gear machining technology. The invention discloses a composite material-steel mixed gear which is an assembled gear adopting a composite material to replace a steel gear radial plate. Due to the fact that additional misalignment deviation introduced by a split type structure of the hybrid gear may exceed the thickness of a tooth surface nitriding or carburizing layer, if a common gear is adopted to accurately grind gear teeth with a hub as the reference, the misalignment deviation cannot be eliminated while the thickness of the tooth surface nitriding or carburizing layer is guaranteed. And the assembling precision and the overall strength of the hybrid gear are greatly influenced. According to the machining process of the composite material-steel hybrid gear, the precision of connecting surfaces of all parts is strictly guaranteed, and enough machining allowance is reserved for secondary machining of an inner hole of a hub after assembly; through secondary machining after assembly, namely finish machining of the hub inner hole and the spline with the inner surface of the gear ring as the reference, misalignment deviation is eliminated, the thickness of a nitriding or carburizing layer on the tooth surface is guaranteed, and the assembly precision and the overall strength of the hybrid gear are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of gear machining, in particular to a composite-steel hybrid gear machining process. BACKGROUND

[0002] The composite-steel hybrid gear uses high specific strength and high specific modulus carbon fiber reinforced resin matrix composite material to replace the spoke of the steel gear, which can achieve the ultimate weight reduction of the gear under the premise of ensuring the meshing strength of the gear, and has broad application prospects in the field of aerospace power transmission.

[0003] At present, the machining process research of composite-steel hybrid gear at home and abroad is relatively scarce. The composite-steel hybrid gear is generally a split structure, which is assembled by steel gear ring, steel hub and composite material spoke through adhesive connection, bolt connection or glue-screw mixed connection. The split structure of the hybrid gear will introduce additional misalignment deviation, and the influence of the misalignment deviation can be reduced through secondary machining after assembly. However, the misalignment deviation introduced by the split structure generally exceeds the thickness of the nitriding or carburizing layer of the gear surface, so the method of grinding the outer gear ring with the hub as the reference in general gear machining cannot completely eliminate the misalignment deviation of the hybrid gear while ensuring the thickness of the nitriding or carburizing layer of the gear surface. In addition, the heat resistance of the composite material is poor, which will produce additional limitations on the arrangement of process steps such as heat treatment.

[0004] Therefore, it is urgent to develop a process scheme that can eliminate the misalignment deviation of each part assembly without affecting the thickness of the nitriding or carburizing layer of the gear ring, and effectively ensure the assembly precision and overall strength of the hybrid gear. SUMMARY

[0005] The purpose of the present application is to provide a composite-steel hybrid gear machining process to overcome the limitations of grinding the outer gear ring with the hub inner hole as the reference in general gear machining, which cannot eliminate the misalignment deviation of the hybrid gear and ensure that the carburizing or nitriding layer of the gear ring surface reaches the specified thickness.

[0006] To solve the above technical problems, the present application provides a composite-steel hybrid gear machining process, which comprises the following steps:

[0007] S1. Blank making: making steel gear ring blanks and steel hub blanks by forging; making composite material spoke blanks by autoclave curing, mold curing or RTM curing process;

[0008] S2. Machining of each component before assembly: machining of the gear ring blank, the hub blank and the composite spoke blank is completed before assembly, the machining of the gear ring blank includes in turn: heat treatment of the gear ring blank, rough machining, semi-finishing, hobbing, heat treatment of the tooth surface, finishing of the connecting surface, gear grinding, the machining of the hub blank includes in turn: heat treatment of the hub blank, rough machining, semi-finishing, spline machining, finishing of the connecting surface, the machining of the composite spoke blank includes in turn: rough machining of the connecting surface, finishing of the connecting surface;

[0009] S3. Precision detection: precision detection is performed on each component in step S2 to ensure that the precision of each component meets the requirements, and the precision of the composite spoke is not less than 6 levels, if it does not meet the requirements, it returns to step S2 for reprocessing;

[0010] S4. Assembly connection: each component is assembled according to the assembly relationship using glueing, mechanical connection or mixed connection to form a mixed gear assembly;

[0011] S5. Assembly processing: the inner hole mounting positioning surface and spline part of the hub are finished with the inner surface of the gear ring as the reference.

[0012] Specifically, the precision of the composite spoke in the thickness direction in step S1 is ensured by the curing mold and the curing process.

[0013] Specifically, the material of the gear ring blank is nitriding steel or carburizing steel, the material of the hub blank is quenched and tempered steel, and the heat treatment of the gear ring blank in step S2 is normalizing or quenching and tempering, the heat treatment of the tooth surface is nitriding or carburizing, and the heat treatment of the hub blank is quenching and tempering.

[0014] Specifically, the connecting surface in step S2 is the connecting surface of the metal part and the composite spoke.

[0015] Specifically, the semi-finishing of the inner hole mounting positioning surface of the steel hub and the spline machining in step S2 need to have sufficient machining allowance for step S5 to ensure that the misalignment deviation introduced by the split gear structure is compensated by step S5.

[0016] Specifically, the connecting part of the composite spoke and the steel gear ring or the steel hub in the mixed gear includes a circular curve for positioning and a special-shaped curve for transmitting torque, and for the machining and detection of the special-shaped curve, in step S2, it needs to be machined by a multi-axis numerical control machine tool, and the precision is guaranteed by the machining precision of the machine tool not less than 6 levels, and in step S3, only the maximum and minimum two extreme diameters of the special-shaped curve are detected, and the maximum and minimum diameters need to meet the related precision requirements.

[0017] Specifically, if the hybrid gear connection contains a bonding process, the bonding surfaces of the machined metal parts should be sandblasted before assembling the connection in step S4, and the thickness of the adhesive and the bonding curing parameters should be determined according to the standard metal-composite connection test.

[0018] Specifically, the steel gear ring and the steel hub are respectively located at the outer and inner circles of the composite spoke, the composite spoke includes side spokes and a middle spoke, the side spokes are located on both sides of the middle spoke, the side spokes and the middle spoke are respectively matched with the steel hub and the steel gear ring through a circular curve and a special-shaped curve, and the steel gear ring, the steel hub and the composite spoke are connected through the connection mode in step S4.

[0019] The composite-steel hybrid gear machining process provided by the application has the beneficial effects that:

[0020] 1. Nitriding and carburizing treatment can improve the hardness of the tooth surface, so that the gear obtains higher strength, and since the misalignment deviation introduced by the split structure of the composite-steel hybrid gear is generally greater than the thickness of the nitriding or carburizing layer, the method of precisely grinding the gear teeth of the gear ring based on the inner hole of the hub can completely eliminate the nitriding or carburizing layer of the tooth surface, which seriously affects the mechanical properties of the gear. The process is a secondary processing after the assembly of the hybrid gear, that is, the inner hole of the hub and the spline are precisely processed based on the inner surface of the gear ring, which eliminates the misalignment deviation and ensures the thickness of the nitriding or carburizing layer of the tooth surface of the gear ring, so that the composite-steel hybrid gear obtains good assembly precision and overall strength.

[0021] 2. The special-shaped curve of the composite spoke can form mechanical interlocking and can transmit larger torque; the circular curve can obtain higher processing precision and improve the fitting precision between the parts. The composite-steel hybrid gear is positioned by the circular curve of the spoke and transmits torque by the special-shaped curve of the spoke, while the bearing performance and assembly precision of the hybrid gear are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the composite-steel hybrid gear machining process flowchart of the application.

[0023] Figure 2 is the composite-steel hybrid gear assembly structure explosion diagram of the embodiment of the application;

[0024] Figure 2 In the figure, 1 is a steel hub, 2 is a steel gear ring, 3 is a composite middle spoke, and 4 is a composite side spoke. DETAILED DESCRIPTION

[0025] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0026] The present application will be further described in detail according to the drawings and embodiments.

[0027] A processing technology of a composite-steel hybrid gear, comprising:

[0028] S1. Blank making: making a gear ring blank and a hub blank by forging; making a composite intermediate web and a composite side web blank by a composite material preparation method of laying up + autoclave curing;

[0029] S2. Machining before assembling each part: machining the gear ring blank, the hub blank, the composite side web blank and the composite intermediate web blank before assembling, the machining of the gear ring blank comprises, in sequence, quenching and tempering, rough machining, semi-finishing, gear hobbing, nitriding, finishing of the connecting surface between the gear ring blank and the composite material, and gear grinding, the machining of the hub blank comprises, in sequence, quenching and tempering, rough machining, semi-finishing, major diameter spline machining, and finishing of the connecting surface between the hub blank and the composite material, the machining of the composite side web blank comprises, in sequence, inner and outer circle rough machining and inner and outer circle finishing, and the machining of the composite intermediate web blank comprises, in sequence, circumferential sinusoidal curve rough machining and circumferential sinusoidal curve finishing;

[0030] S3. Precision detection: detecting the precision of each part in step S2 to ensure that each part meets the requirements, and returning to step S2 for reprocessing if the requirements are not met;

[0031] S4. Assembling and curing: bonding each part according to the assembling relationship using an adhesive, and then placing the bonded semi-finished hybrid gear into an autoclave for pressurization and temperature rise to finally cure the hybrid gear assembly;

[0032] S5. Machining of the assembly: taking the inner surface of the gear ring as a reference to finish machining the spline part of the hub.

[0033] Specifically, the forging of the gear ring blank and the hub blank in step S1 comprises:

[0034] The gear ring blank material is nitriding steel, and the hub blank material is quenched and tempered steel. The bar stock is cut to obtain a cylindrical raw material, and then rough forging and fine forging are performed to obtain the gear ring blank and the hub blank with a larger volume than the finished product. During forging, the deformation resistance of the gear steel is large during rough forging, so a higher temperature is needed to improve the machinability of the metal, and the metal has good machinability at 800-1000°C. Therefore, the rough forging temperature is controlled at about 900°C. The main purpose of fine forging is to improve the forging accuracy of the gear, so the temperature is lower than that of rough forging, and is controlled at about 500°C.

[0035] Specifically, the process of manufacturing the composite material intermediate web plate and the side web plate blank in step S1 includes:

[0036] Plain weave type carbon fiber reinforced resin matrix composite material prepreg is selected as the web plate raw material. According to the quasi-isotropic layer angle design principle, the prepreg is laid up and placed in a hot press tank. The composite material is cured according to the curing parameters of the composite material, and the composite material web plate blank is finally formed. The thickness accuracy of the composite material should be ensured by the hot press tank curing process, and should be not less than 7 levels.

[0037] Specifically, the rough machining of the gear ring and the hub in step S2 includes:

[0038] Rough milling has higher machining efficiency due to its high feed rate and cutting depth. In this rough machining process, the surface of the gear ring blank and the hub blank is rough milled to remove excess material of the workpiece and ensure the basic shape and size of the gear ring and the hub.

[0039] Specifically, the semi-finish machining of the gear ring in step S2 includes:

[0040] The gear ring is semi-finished. The purpose of this semi-finishing is to remove burrs and large machining errors, improve the gear ring outer circle precision, prepare for subsequent gear ring hobbing, and improve the precision of subsequent gear ring hobbing. It also prepares for the finish machining of the connection surface between the gear ring and the composite material, and improves the machining precision of the connection surface between the gear ring and the composite material.

[0041] Among them, since the inner surface of the gear ring is the reference surface for secondary machining after assembly of the hybrid gear, its machining precision needs special attention, and its precision should be not less than 6 levels of precision. If the precision cannot meet the requirements, the inner surface of the gear ring needs to be finished again.

[0042] Specifically, the semi-finish machining of the hub in step S2 includes:

[0043] The hub is semi-finely turned, wherein the hub inner hole has the same size as the small pitch diameter, and a machining allowance of 0.2 mm is reserved for eliminating misalignment deviation after secondary machining. The purpose of the semi-fine turning is to remove burrs and large machining errors, to prepare for subsequent spline machining and improve spline accuracy, and to prepare for subsequent fine machining of the hub and composite material connecting surface and improve the machining accuracy of the hub and composite material connecting surface.

[0044] Specifically, the large diameter machining of the hub spline in step S2 adopts wire electrical discharge machining.

[0045] Specifically, considering that the gear ring in the embodiment is relatively thin, the carburizing treatment temperature is generally 900°C, which will cause excessive thermal deformation of the gear ring and affect the strength of the gear ring. The nitriding treatment temperature is relatively low, generally 500°C, and the generated thermal deformation is small. In order to prevent excessive thermal deformation of the gear ring, the gear ring is subjected to nitriding treatment in step S2.

[0046] Specifically, in order to prevent the thermal deformation caused by nitriding treatment from affecting the fine machining, the nitriding treatment is performed before the fine machining in step S2.

[0047] Specifically, the connecting surface of the gear ring and the composite material web plate and the connecting surface of the hub and the composite material web plate in step S2 are connected and matched with the composite material circular curve and the special-shaped curve as shown in Figure 2 The connecting surface is finely machined by fine turning, wherein the special-shaped curve is machined by a multi-axis numerical control machine tool, and the accuracy is guaranteed by the machine tool machining accuracy. The maximum and minimum two extreme diameters of the special-shaped curve are detected in step S3. The above steps ensure that the machining accuracy is not less than 6 levels.

[0048] Specifically, as shown in Figure 2 The inner and outer circles of the composite material side web plate in step S2 are circular curves, and the circumferential sine curve of the composite material middle web plate is a special-shaped curve. The circular curve of the side web plate is finely machined by fine turning, and the machining and accuracy detection of the special-shaped curve of the middle web plate are the same as those of the gear ring and the hub, and the accuracy is not less than 6 levels.

[0049] After the above steps, all parts of the composite-steel hybrid gear except the hub are machined, and sufficient machining allowance is reserved for secondary machining of the small pitch diameter after assembly.

[0050] Specifically, the mixed gear assembly method of the embodiment adopts adhesive bonding. In order to remove the oxide layer, rust and oil stains on the connecting surface and improve the surface roughness to increase the bonding strength of the interface, the adhesive surfaces of the gear ring, the hub and the web are subjected to sand blasting treatment, acetone cleaning and drying in sequence before assembly and curing in step S4. In step S4, in order to effectively exert the high bonding strength of the adhesive, the adhesive thickness is preferably 0.5 mm and the adhesive is uniformly applied at the bonding position of the composite material side web and the intermediate web and at the connecting surface of the composite material web and the metal part.

[0051] Specifically, in the assembled part in step S5, the spline small diameter of the hub is precisely machined with the inner surface of the gear ring as the machining reference, and the machining precision is ensured to be level 6, so as to eliminate the additional misalignment deviation caused by the split structure of the mixed gear.

[0052] It is apparent for those skilled in the art that the present application is not limited to the details of the above-described embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description.

[0053] The above-described embodiments are part of the embodiments of the present application, but not all the embodiments. The scope of protection of the present application is not limited to this. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

Claims

1. A composite material-steel hybrid gear processing process, characterized in that: The steps include: S1. Blank production: Steel ring gear blanks and steel hub blanks are produced by forging; composite web blanks are produced by autoclave curing, molding curing, or RTM curing processes; S2. Pre-assembly Processing of Components: Complete the machining of the ring gear blank, wheel hub blank, and composite spoke blank prior to assembly. Ring gear blank machining includes, in order: heat treatment, roughing, semi-finishing, gear hobbing, tooth surface heat treatment, connection surface finishing, and gear grinding. Hub blank machining includes, in order: heat treatment, roughing, semi-finishing, spline machining, connection surface finishing. Composite spoke blank machining includes, in order: connection surface roughing and connection surface finishing. S3 precision testing: Step S2 of each component precision testing to ensure that the accuracy of each component meets the requirements, including the composite web precision of not less than 6, if it does not meet the requirements, return to step S2 reprocessing; S4. Assembly connection: Assemble the components according to the assembly relationship using adhesive bonding, mechanical connection, or a hybrid connection method to form a hybrid gear assembly; S5. Assembly processing: Based on the inner surface of the gear ring, the inner hole installation positioning surface and spline parts of the wheel hub are finely processed.

2. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The accuracy of the composite material web in the thickness direction in step S1 is ensured by the curing mold and the curing process.

3. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The ring gear blank material is nitriding steel or carburizing steel, and the hub blank material is quenched and tempered steel. In step S2, the ring gear blank heat treatment is normalizing or quenching and tempering, the tooth surface heat treatment is nitriding or carburizing, and the hub blank heat treatment is quenching and tempering.

4. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The connection surface mentioned in step S2 is the connection and matching surface between the metal part and the composite material web.

5. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The two sub-steps of semi-finishing and spline machining of the inner hole mounting positioning surface of the steel hub in step S2 need to leave sufficient machining allowance for step S5 to ensure that the misalignment deviation introduced by the split gear structure is compensated by the machining in step S5.

6. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The connection between the composite spoke and the steel ring gear or steel hub in the hybrid gear includes a circular curve for positioning and a special-shaped curve for transmitting torque. For the processing and detection of the special-shaped curve, in step S2, it is necessary to use a multi-axis CNC machine tool for processing, and its accuracy is guaranteed by the machine tool processing accuracy to be no less than level 6. In step S3, only the maximum and minimum extreme diameters of the special-shaped curve are detected, and the maximum and minimum diameters need to meet the relevant accuracy requirements.

7. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: If the hybrid gear connection includes a bonding process, the bonding surfaces of the processed metal parts should be sandblasted before the assembly connection in step S4. The adhesive thickness and bonding curing parameters should be determined according to the standard metal-composite joint test.

8. The composite material-steel hybrid gear processing process according to claim 1, characterized in that: The steel gear ring and the steel wheel hub are respectively located on the outer ring and the inner ring of the composite web. The composite web includes a side web and a middle web. The side web is located on both sides of the middle web. The side web and the middle web are respectively matched with the steel wheel hub and the steel gear ring through circular curves and special-shaped curves. The steel gear ring, the steel wheel hub and the composite web are connected through the connection method described in step S4.

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