Special tooth profile end face rounding device for aero-engine gear and machining method

Abstract

The invention relates to a tooth profile end face rounding device special for an aero-engine gear and a machining method. The tooth profile end face rounding device comprises a movable platform, a 3D camera, a positioning tool, a special cutter and a computer. Data acquisition is carried out on the gear end face tooth profile in the sealed box body through the 3D camera, the computer generates an accurate machining path according to the acquired data, and then end face tooth profile rounding machining is carried out on the gear on the numerical control machine tool through the special tool. The positioning tool is provided with four gear positioning stations, four gears can be machined at the same time, and the machining efficiency is improved. The positioning tool comprises a bottom plate, a positioning block and a positioning flange, and six-degree-of-freedom complete positioning of the gear is achieved through precise matching. The device has the advantages of being high in machining precision, high in machining efficiency, high in adaptability, stable in machining quality and the like, and meets the machining requirements of aero-engine gears of different specifications and types.

Description

Technical Field

[0001] The present invention relates to the field of aero-engines, and in particular to a tooth profile end face rounding device and a processing method for aero-engine gears. Background Art

[0002] Aviation gears are key components of aircraft engines. The main accessories of the engine and aircraft's starting, fuel, lubricating oil, hydraulic and other systems are all driven by the engine rotor through the gear transmission device. As the performance and reliability requirements of the entire aircraft continue to improve, the alternating loads and severe impact loads borne by the gears are constantly increasing. The stresses they are subjected to are complex and the working conditions are harsh. This puts higher demands on the gears in terms of materials, precision, strength, durability and reliability.

[0003] Numerous theoretical and practical studies have shown that the sharp corners of gears can cause stress concentration during heat treatment, affecting the mechanical properties of the gears and leading to tooth wear. These sharp corners can also easily cause tooth collisions, generating noise and damage during meshing, reducing gear life. Furthermore, sharp edges are prone to stress concentration, leading to fatigue cracks and, in severe cases, tooth breakage. To reduce vibration and noise during operation, prevent tooth fracture caused by stress concentration, increase tooth strength and life, and facilitate engagement between gears during transmission, rounding the edges of gears has become a crucial process in manufacturing. Since gear tooth surfaces typically undergo carburizing treatment, achieving a surface hardness of up to HRC65, manual grinding is currently the most common method for rounding edges, resulting in poor quality and consistency, and extremely low efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a tooth profile end face rounding device and processing method specifically for aircraft engine gears, so as to solve the problem of low efficiency of the prior art.

[0005] The present invention is implemented by adopting the following technical solution: a special tooth profile end face rounding device for aircraft engine gears, including a mobile platform, a 3D camera, a positioning tool, a special tool and a computer. The 3D camera is set on the mobile platform. The mobile platform has two degrees of freedom in the X / Z direction and is used to adjust the position of the 3D camera. The positioning tool is set below the 3D camera and is set on a CNC machine tool. The special tool is also installed on the CNC machine tool and is used to perform end face tooth profile rounding on the gear.

[0006] Furthermore, the 3D camera is arranged in a sealed box and is connected to a computer and a power plug via a wire to ensure that the environment of the 3D camera is dry and clean during use.

[0007] Furthermore, the positioning tool includes four gear positioning stations for simultaneously processing four gears.

[0008] Furthermore, the positioning tooling includes a base plate, a positioning block and a positioning flange, the positioning block and the positioning flange are both fixed on the base plate, the positioning block is arranged on one side of the positioning flange, the gear is arranged on the positioning flange, and is fastened to the positioning flange through a fastening bolt passing through the gear.

[0009] Furthermore, the gear includes a gear end face, a gear cylindrical surface and a tooth groove, and the positioning flange includes a positioning end face and a positioning cylindrical surface. The positioning end face and the gear end face have the same shape and cooperate with each other, and the positioning cylindrical surface and the gear cylindrical surface have the same shape and cooperate with each other.

[0010] Furthermore, a positioning tooth groove is provided on the side of the positioning block close to the gear, and the positioning tooth groove has the same shape as the tooth groove and cooperates with the tooth groove. A positioning groove is also provided on the positioning block, and a positioning block mounting base is provided under the positioning block. A plurality of positioning pins are provided on the positioning block mounting base, and the plurality of positioning pins are tightly fitted with the positioning groove to achieve precise positioning of the positioning block.

[0011] Furthermore, the special tool is a milling cutter, the forming surface of which is a 1 / 4 arc, and the arc radius is equal to the fillet radius of the tooth profile of the end face to be processed.

[0012] A method for rounding the end face of a tooth profile specifically for an aircraft engine gear is provided. The method is based on the aforementioned device for rounding the end face of a tooth profile specifically for an aircraft engine gear. When the diameter of the gear is larger than the width of the measurement area of ​​the 3D camera, the specific steps include: Step 1: Install and fasten the gear to be processed onto the gear multi-station positioning fixture; Step 2: calibrate the gear machining coordinate system through the gear end face height calibration point and the gear end face center calibration point; Step 3: Convert the gear machining trajectory into the gear machining coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting process; Step 4: Use a 3D camera to check the fillet radius of the detectable area. During the inspection process, the denoising and simplification algorithm, the minimum envelope circle algorithm and the outer contour algorithm are used to obtain the processed tooth profile and fillet radius.

[0013] Furthermore, when the diameter of the gear is smaller than the width of the measurement area of ​​the 3D camera, the specific steps include: Step 1: Install and fasten the gear to be processed onto the gear multi-station positioning fixture; Step 2: Adjust the position of the gear multi-station positioning fixture and the mobile platform so that the end face of the gear to be processed is within the measurement range of the 3D camera; Step 3: Gear data is collected through a 3D camera to obtain a point cloud of the gear end face. The ideal tooth profile for machining is obtained through a series of algorithms, and a gear machining coordinate system is established. Step 4: Convert the gear machining trajectory into the gear machining coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting process; Step 5: Use a 3D camera to check the fillet radius of the detectable area. During the inspection process, the denoising and simplification algorithm, the minimum envelope circle algorithm and the outer contour algorithm are used to obtain the processed tooth profile and fillet radius.

[0014] The tooth profile end face rounding device and processing method for aircraft engine gears described in the present invention have the following beneficial effects: Improve machining accuracy: 3D cameras collect data on the gear end face tooth profile, providing accurate basic data for subsequent rounding path generation. Computer algorithms extract the gear end face tooth profile and accurately generate machining paths, ensuring rounding accuracy.

[0015] Improved processing efficiency: The positioning tooling is designed with four gear positioning stations, which can process four gears simultaneously, avoiding frequent gear clamping and significantly improving processing efficiency. The automated processing process reduces manual intervention and further shortens the processing cycle.

[0016] Enhanced adaptability: The device utilizes CNC machine tools and specialized cutting tools to adapt to the machining needs of aircraft engine gears of varying sizes and types. By adjusting the position of the mobile platform and 3D camera, gears of varying positions and sizes can be precisely measured and machined.

[0017] Guaranteed processing quality: Dedicated tools and precise processing paths ensure the rounding quality of the gear end tooth profile, avoiding gear damage or performance degradation caused by improper processing. The sealed box design ensures a dry and clean environment during the use of the 3D camera, further improving the stability of processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of a tooth profile end face rounding device specifically designed for aircraft engine gears; Figure 2 This is a schematic diagram of the positioning tooling structure; Figure 3 It is a schematic diagram of the positioning flange structure; Figure 4 Schematic diagram of the gear structure; In the figure, 1-mobile platform, 2-3D camera, 3-positioning tooling, 4-special tool, 5-computer, 6-power plug, 31-base plate, 32-positioning block, 33-positioning pin, 34-positioning block mounting base, 35-positioning flange, 36-fastening bolt, 37-gear, 351-positioning end face, 352-positioning cylinder, 371-gear end face, 372-gear cylinder, 373-tooth groove. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0022] like Figure 1-4 As shown, a dedicated end face rounding device for aircraft engine gears comprises a mobile platform 1, a 3D camera 2, a positioning fixture 3, a dedicated tool 4, and a computer 5. The 3D camera 2 is mounted on the mobile platform 1, which has two degrees of freedom in the X and Z directions for adjusting the position of the 3D camera 2. The positioning fixture 3 is positioned below the 3D camera 2. The positioning fixture 3 is mounted on a CNC machine tool, and the dedicated tool 4 is installed on the CNC machine tool. The dedicated tool 4 performs end face rounding on a gear 37. The 3D camera 2 is housed in a sealed enclosure and connected to the computer 5 and a power plug 6 via wires. The sealed enclosure ensures a dry and clean environment for the 3D camera 2 during use. The 3D camera 2 collects data on the gear end face tooth profile, providing basic data for subsequent generation of the gear end face tooth profile rounding path. After receiving the data collected by the 3D camera 2, the computer 5 uses an algorithm to extract the gear end face tooth profile and generate a machining path. The generated tool path is then sent to the machine tool to perform the gear rounding process.

[0023] The positioning fixture 3 includes four gear positioning stations, which can simultaneously process four gears, avoiding frequent gear clamping and significantly improving efficiency. The positioning fixture 3 includes a base plate 31, a positioning block 32, and a positioning flange 35. The positioning block 32 and positioning flange 35 are both fixed to the base plate 31. The positioning block 32 is located on one side of the positioning flange 35. The gear 37 is located on the positioning flange 36. The fastening bolt 36 passes through the gear 37 and the positioning flange 36 to fasten the gear 37 to the positioning flange 36.

[0024] The gear 37 includes a gear end face 371, a gear cylindrical surface 372 and a tooth groove 373, and the positioning flange 35 includes a positioning end face 351 and a positioning cylindrical surface 352. The positioning end face 351 and the gear end face 371 have the same shape and cooperate with each other, and the positioning cylindrical surface 352 and the gear cylindrical surface 372 have the same shape and cooperate with each other.

[0025] The positioning block 32 is provided with a positioning tooth groove on one side near the gear 37. The positioning tooth groove is the same shape as the tooth groove 373 and cooperates with the tooth groove 373. The positioning block 32 is also provided with a positioning groove. A positioning block mounting base 34 is also provided below the positioning block 32. The positioning block mounting base 34 is provided with multiple positioning pins 33. The multiple positioning pins 33 are closely matched with the positioning groove to achieve precise positioning of the positioning block 32.

[0026] During positioning, first, the gear 37 is inserted into the positioning flange 35, and the positioning cylindrical surface 352 and the gear cylindrical surface 372 are precisely matched to realize the positioning of the gear 37 in the horizontal plane; then, the gear end face 371 contacts the positioning end face 351 to realize the height direction positioning of the gear 37; then, the positioning tooth groove of the positioning block 32 is inserted into the gear tooth groove 373 and fits with the gear tooth groove 373 to realize the complete positioning of the six degrees of freedom of the gear.

[0027] The special tool 4 is a milling cutter, and its forming surface is a 1 / 4 arc, and the arc radius is equal to the fillet radius of the end face tooth profile to be machined.

[0028] The processing method of the tooth profile end face rounding device for aircraft engine gears includes two working modes: Working mode 1: Applicable to situations where the diameter of the gear is larger than the measurement area width of the 3D camera. In this mode, the positioning of the gear of this device is achieved through the gear multi-position positioning tooling, and the 3D camera only performs random inspections of the gear fillet radius.

[0029] Step 1: Install the gear to be processed onto the gear multi-station positioning fixture and tighten it, and then tighten the gear in position.

[0030] Step 2: Calibrate the gear end face height using the gear end face height calibration point. Simultaneously, establish the z-axis of the gear machining coordinate system based on the plane normal formed by the three points. The gear end face center can be calibrated using the gear end face center calibration point. This point is the center of the gear end face tooth profile and serves as the origin of the gear machining coordinate system. The x-axis of the gear machining coordinate system can be established by tracking the tool, and the y-axis of the coordinate system can be determined using the right-hand rule. After calibration, the xy-axis of the gear machining coordinate system passes through the axis of symmetry of a tooth groove, completely determining the position of the gear end face tooth profile in the gear machining coordinate system.

[0031] Step 3: Convert the gear processing trajectory into the gear processing coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting processing.

[0032] Step 4: After the gear filleting is completed, the fillet radius of the detectable area is checked by a 3D camera. During the gear calibration process, the CNC machine tool and computer have recorded the geometric parameters of the unprocessed tooth profile, such as the module, number of teeth, pressure angle, and position parameters such as the center of the circle and coordinate system. The gear 3D camera is then used to collect the end face data of the processed gear. The basic point cloud data that can represent the end face tooth profile is obtained through denoising and simplification algorithms. The minimum envelope circle algorithm is then used to obtain the minimum envelope circle of the end face tooth profile (this circle is the processed tooth top circle) after processing, and then the center coordinates of the end face tooth profile are obtained. Based on the center coordinates and the gear geometric parameters, point clouds that are not related to the tooth profile are eliminated to improve calculation efficiency. The processed tooth profile is then obtained through the outer contour algorithm, and the fillet radius is obtained by calculating the normal distance of the tooth profile before and after processing.

[0033] Working mode 2: Applicable to the situation where the diameter of the gear is smaller than the measurement area width of the 3D camera. In this mode, the positioning and detection of the gear of this device rely on the 3D camera.

[0034] Step 1: Install the gear to be processed on the gear multi-station positioning fixture and tighten it.

[0035] Step 2: Adjust the position of the gear multi-station positioning fixture and adjust the mobile platform so that the end face of the gear to be processed is within the measurement range of the 3D camera.

[0036] The third step: Gear data is collected through a 3D camera, and then a series of point cloud noise reduction, recognition and extraction operations are performed to obtain the point cloud of the gear end face to be processed; the addendum circle of the gear end face tooth profile is obtained based on the maximum envelope circle of the calculated point cloud; the tooth profile data points are then obtained through the outer contour extraction algorithm; the ideal tooth profile that best matches the measured tooth profile data points is obtained through the least squares algorithm, and this tooth profile is the tooth profile used for processing; based on the properties of the gear, the gear node position is obtained by intersecting the theoretical pitch circle and the tooth profile curve; the x-axis is established by connecting the midpoints of the two nodes and the midpoint of the tooth addendum circle, the y-axis is established by the perpendicular line to the x-axis, and the z-axis is determined according to the right-hand rule, and then the gear processing coordinate system is established.

[0037] Step 4: Convert the gear processing trajectory into the gear processing coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting processing.

[0038] Step 5: After the gear rounding is completed, the rounding radius of the detectable area is checked using a 3D camera. In the third step, the 3D camera has already obtained the unmachined gear tooth profile. The gear 3D camera then collects the processed gear end face data. A denoising and simplification algorithm is used to obtain basic point cloud data that can represent the end face tooth profile. The minimum enveloping circle algorithm is then used to obtain the minimum enveloping circle of the end face tooth profile (this circle is the machined tooth top circle). The center coordinates of the end face tooth profile are then obtained. Based on the center coordinates and gear geometric parameters, point clouds unrelated to the tooth profile are eliminated to improve computational efficiency. The processed tooth profile is then obtained using the outer contour algorithm. The rounding radius is then calculated by calculating the normal distance between the tooth profile before and after processing.

[0039] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention should be within the scope of protection of the appended claims.

Claims

1. A tooth profile end face rounding device for aircraft engine gears, characterized in that: The invention comprises a mobile platform (1), a 3D camera (2), a positioning tool (3), a special tool (4) and a computer (5), wherein the 3D camera (2) is arranged on the mobile platform (1), the mobile platform (1) has two degrees of freedom in the X / Z direction and is used to adjust the position of the 3D camera (2), the positioning tool (3) is arranged below the 3D camera (2) and is arranged on a numerical control machine tool, and the special tool (4) is also installed on the numerical control machine tool and is used to perform end face tooth profile rounding processing on the gear (37).

2. The tooth profile end face rounding device for aircraft engine gears according to claim 1, characterized in that: The 3D camera (2) is arranged in a sealed box and is connected to a computer (5) and a power plug (6) via a wire to ensure that the environment of the 3D camera (2) is dry and clean during use.

3. The tooth profile end face rounding device for aircraft engine gears according to claim 1, characterized in that: The positioning tool (3) comprises four gear positioning stations, which are used to simultaneously process four gears.

4. The tooth profile end face rounding device for aircraft engine gears according to claim 1, characterized in that: The positioning fixture (3) includes a base plate (31), a positioning block (32) and a positioning flange (35), wherein the positioning block (32) and the positioning flange (35) are both fixed to the base plate (31), the positioning block (32) is arranged on one side of the positioning flange (35), and the gear (37) is arranged on the positioning flange (36) and is fastened to the positioning flange (36) by a fastening bolt (36) passing through the gear (37).

5. The tooth profile end face rounding device for aircraft engine gears according to claim 4, characterized in that: The gear (37) includes a gear end face (371), a gear cylindrical surface (372) and a tooth groove (373); the positioning flange (35) includes a positioning end face (351) and a positioning cylindrical surface (352); the positioning end face (351) and the gear end face (371) have the same shape and cooperate with each other; the positioning cylindrical surface (352) and the gear cylindrical surface (372) have the same shape and cooperate with each other.

6. The tooth profile end face rounding device for aircraft engine gears according to claim 4, characterized in that: A positioning tooth groove is provided on one side of the positioning block (32) close to the gear (37), and the positioning tooth groove has the same shape as the tooth groove (373) and cooperates with the tooth groove (373). A positioning groove is also provided on the positioning block (32), and a positioning block mounting base (34) is provided below the positioning block (32). A plurality of positioning pins (33) are provided on the positioning block mounting base (34), and the plurality of positioning pins (33) are closely matched with the positioning groove to achieve accurate positioning of the positioning block (32).

7. The tooth profile end face rounding device for aircraft engine gears according to claim 1, characterized in that: The special tool (4) is a milling cutter, the forming surface of which is a 1 / 4 arc, and the arc radius is equal to the fillet radius of the end face tooth profile to be processed.

8. A method for rounding the end face of a tooth profile specifically for an aircraft engine gear, based on the device for rounding the end face of a tooth profile specifically for an aircraft engine gear according to any one of claims 1 to 7, characterized in that When the diameter of the gear is larger than the width of the 3D camera's measurement area, the specific steps include: Step 1: Install and fasten the gear to be processed onto the gear multi-station positioning fixture; Step 2: calibrate the gear machining coordinate system through the gear end face height calibration point and the gear end face center calibration point; Step 3: Convert the gear machining trajectory into the gear machining coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting process; Step 4: Use a 3D camera to check the fillet radius of the detectable area. During the inspection process, the denoising and simplification algorithm, the minimum envelope circle algorithm and the outer contour algorithm are used to obtain the processed tooth profile and fillet radius.

9. A method for rounding the tooth profile end face of an aircraft engine gear according to claim 8, characterized in that: When the diameter of the gear is smaller than the width of the 3D camera's measurement area, the specific steps include: Step 1: Install and fasten the gear to be processed onto the gear multi-station positioning fixture; Step 2: Adjust the position of the gear multi-station positioning fixture and the mobile platform so that the end face of the gear to be processed is within the measurement range of the 3D camera; Step 3: Gear data is collected through a 3D camera to obtain a point cloud of the gear end face. The ideal tooth profile for machining is obtained through a series of algorithms, and a gear machining coordinate system is established. Step 4: Convert the gear machining trajectory into the gear machining coordinate system, select the starting point of the tooth profile filleting, and start the tooth profile filleting process; Step 5: Use a 3D camera to check the fillet radius of the detectable area. During the inspection process, the denoising and simplification algorithm, the minimum envelope circle algorithm and the outer contour algorithm are used to obtain the processed tooth profile and fillet radius.

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