Method for machining an eccentric gear

Abstract

The application discloses a processing method of eccentric gear, and belongs to the technical field of gear processing. The method comprises the following steps: step one, precisely positioning gear steel by using an eccentric shaft hole; step two, collecting gear steel images by a first camera device and correcting the deformed images to actual images; step three, generating a to-be-processed division area on the corrected gear steel images; step four, processing the gear rim, gear root and keyway of the gear steel according to the positioning result by a milling assembly; and step five, obtaining a processing edge contour image and comparing the same with a processing sensitive area division line under a pixel coordinate system, and feeding back a control signal. When the gear steel is processed into an eccentric gear, the relative positioning mode taking the eccentric shaft hole as a reference is adopted, so that error accumulation is avoided. The image preset of the front-end first camera device and the image tracking correction of the second camera device are matched, correction information is continuously fed back, and control information is output.

Description

Technical Field

[0001] This invention belongs to the field of gear processing technology, specifically a method for processing eccentric gears. Background Technology

[0002] Eccentric gears are gears with eccentric motion characteristics and are widely used in various mechanical equipment, such as pumps, compressors, and some special transmission mechanisms. Due to their unique motion mode, eccentric gears can achieve motion characteristics that traditional gears cannot. However, it is precisely because of this special structure that the machining and positioning of eccentric gears become exceptionally complex, especially the positioning and machining of large eccentric gears.

[0003] Eccentric gears differ from ordinary gears in that their center does not coincide with the axis of rotation, resulting in periodic changes in motion during rotation. While this structural feature endows eccentric gears with unique functions, it also increases the difficulty of their manufacturing process. Large eccentric gears, in particular, due to their large size, heavy weight, and eccentric shaft holes, require a large lathe platform and additional tooling fixtures for machining using turning methods. This places high demands on the lathe's specifications, and the excessive deviation of the gear's center of gravity from the lathe's rotation center during rotation can easily cause adverse effects on the lathe. Milling is a machining method that uses a rotating cutting tool to mill the surface of the gear steel to form the gear shape. Milling is suitable for machining small to medium-sized gears, and its machining accuracy depends entirely on the gantry's conveying accuracy. Therefore, it requires extremely high precision and control of the equipment, and the machining accuracy gradually changes due to the gantry's lifespan, leading to accumulated errors. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing eccentric gears to solve the problems mentioned in the prior art.

[0005] A method for machining an eccentric gear is provided, comprising:

[0006] Step 1: After the gear steel is initially positioned by the conveying equipment, it is fed to the cutting platform, where the shaft hole is machined by the cutting mechanism, and then the gear steel is precisely positioned by the positioning equipment that mates with the shaft hole.

[0007] Step 2: The positioning equipment transports the gear steel to the milling machine, and the first camera device captures images of the gear steel. Perspective transformation is performed on specific boundaries to correct the deformed image of the gear steel to the actual image.

[0008] Step 3: Pre-set the gear machining sensitive area division line, match the shaft hole division line within the gear machining sensitive area division line with the gear steel shaft hole, and generate the division area to be processed on the corrected gear steel image;

[0009] Step 4: Use the pixel coordinate system to locate the area to be processed in the image, and the milling component will process the gear steel tooth edge, tooth root and keyway according to the positioning result;

[0010] Step 5: The second camera device tracks the milled part of the gear steel in real time, acquires the processing edge contour image, compares the processing edge contour image with the processing sensitive area division line in the pixel coordinate system, and feeds back the comparison result to the milling component to generate a control signal.

[0011] As a further embodiment of the present invention: the shaft hole in step one is formed by electrical discharge machining (EDM). EDM cuts steel by eroding the surface material of the workpiece through electrical discharge. Since EDM does not require physical contact, it does not generate mechanical stress or deformation, enabling high-precision machining of the shaft hole and ensuring the accuracy of positioning when using the shaft hole as a positioning reference. Furthermore, EDM has excellent machining effects on special gear steels such as hardened steel, high-speed steel, and cemented carbide.

[0012] As a further embodiment of the present invention: Step Six: After the gear steel is machined and formed into gears, the shaft hole is polished and ground. The electrical discharge process generates high temperatures, which may form a heat-affected zone on the workpiece surface. This heat-affected zone may cause surface hardening, microcracks, or changes in material properties at the shaft hole, affecting the fatigue life and durability of the gear shaft hole, and may also form discharge pits or other surface defects. Therefore, after the shaft hole has fulfilled its positioning function, it needs to undergo secondary processing, using polishing and grinding to remove surface defects and the heat-affected zone, ensuring gear quality.

[0013] As a further embodiment of the present invention: In step two, after the first camera device acquires the image of the gear steel, it uses the Canny operator to perform edge detection on the image of the gear steel and uses the horizontal operator to extract the edge, thereby obtaining the shaft hole edge curve and the outer edge curve of the gear steel. The perspective transformation function is formed by the distortion principle of the first camera device. Multiple point parameters on the shaft hole edge curve and the outer edge curve of the gear steel are passed into the perspective transformation function, and the output value is used to regenerate the corrected shaft hole edge curve and the outer edge curve of the gear steel.

[0014] As a further embodiment of the present invention: when performing step four, the milling part of the gear steel is tracked in real time by a third camera device to obtain a machining depth contour image. The machining depth contour image is compared with the machining sensitive area division line in the pixel coordinate system. The comparison result is fed back to the milling component and a control signal is generated.

[0015] As a further embodiment of the present invention: the second and third camera devices employ distortion-free cameras. The second and third camera devices are closer to the processing area than the first camera device, providing images with more detailed information. The distortion-free camera uses its built-in image processing algorithm for distortion correction, providing high-precision images, especially in the edge areas of gear steel processing. This avoids common image stretching or compression problems, ensuring that the captured processing edge contour images and processing depth contour images accurately reflect the geometry and proportions of the processing area.

[0016] As a further embodiment of the present invention: during the milling process in step four, atomized cutting fluid is sprayed onto the milling area. The atomized particle size of the cutting fluid is 0.1 μm to 5 μm, and the atomization rate is 0.5 ml / min to 3 ml / min. Spraying atomized cutting fluid can cool the milling area, lubricate the cutting tools of the milling assembly, and carry away grinding dust through the atomized airflow. The cutting fluid is sprayed in an atomized form, which reduces the occlusion effect on the camera equipment caused by the water droplet-shaped spray of the cutting fluid, preventing blurring and distortion of the acquired image. Therefore, it is also necessary to control the particle size and atomization rate of the atomized cutting fluid.

[0017] As a further embodiment of the present invention: the dust particle size during the grinding of gear steel is between 0.1 μm and 3 μm. Controlling the generated dust particle size is to prevent large dust particles from obstructing and interfering with the imaging equipment, resulting in low image quality and thus affecting processing accuracy. The overall dust particle size is smaller than that of the atomized cutting fluid, facilitating the combination of the atomized cutting fluid with the dust and carrying it away, preventing a large amount of dust from settling on the surface of the gear steel.

[0018] As a further embodiment of the present invention, it also includes a ventilation system that forms an airflow circulation within the milling machine area to remove atomized cutting fluid and dust. After the atomized cutting fluid is sprayed out and acts on the milled part of the gear steel, the ventilation system carries away the surrounding dispersed atomized cutting fluid and dust through the airflow, providing a clear shooting environment for the camera equipment to ensure the accuracy of image capture.

[0019] As a further embodiment of the present invention: images acquired by the second and third camera devices are smoothed and denoised using a Gaussian filter. The Gaussian filter smooths the image by weighted averaging of the values ​​of adjacent pixels, reducing noise and highlighting the main features of the processed edge contour image and the processed depth contour image, facilitating subsequent processing such as edge detection and feature extraction.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] When machining eccentric gears from gear steel, the absolute positioning method is abandoned. Instead, a relative positioning method based on the eccentric shaft hole is adopted. Positioning is then performed by radiating outwards from the eccentric shaft hole as the coordinate origin to define the areas sensitive to machining, thus preventing error accumulation. The precision control of milling is no longer limited to the system presets of the front-end gantry frame. Instead, it utilizes a combination of image presets from the first front-end camera and image tracking correction from the second front-end camera to continuously provide feedback and output control information. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a process flow diagram of a machining method for an eccentric gear;

[0024] Figure 2 This is a comparison table of errors at different parts of the tooth profile of an eccentric gear. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0026] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0027] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0028] Please see Figure 1 As shown, the machining method of the eccentric gear in this embodiment of the invention includes:

[0029] Step 1: After initial positioning via a conveying device, the gear steel is fed to the cutting platform. A cutting mechanism processes the shaft hole, and a positioning device then precisely positions the gear steel by engaging with the shaft hole. The initial positioning accuracy is determined by ensuring that, after the shaft hole is machined, the remaining parts of the gear steel can be machined into a complete, formed gear, using the shaft hole as a reference for positioning. The cutting mechanism is an electrical discharge machining (EDM) device, capable of cutting the shaft hole in one pass, offering advantages such as high cutting precision and high stability of the gear steel during the cutting process. The main body of the positioning device is a shaft head that penetrates the shaft hole and assembles with it for positioning. For some gears, the shaft hole needs to be machined with splines; the shaft head can engage with the splines for positioning, providing a stable reference platform for subsequent machining of the eccentric gear.

[0030] Step Two: The positioning equipment transports the gear steel to the milling machine. The first camera captures an image of the gear steel, and perspective transformation is performed on specific boundaries to correct the deformed image of the gear steel to the actual image. Since this application is used to process large-size eccentric gears, it is difficult for the camera to simultaneously achieve distortion-free and high-resolution image acquisition while encompassing the entire gear steel within the lens. Therefore, two image acquisition methods are used: one is to acquire an image using a distorted camera and then correct the distortion to obtain the actual image; the other is to directly acquire the actual image using a distortion-free camera. However, both methods require image correction processing. Distortion-free cameras use their built-in image processing programs for this purpose, and a distortion-free camera is preferred in this application.

[0031] Step 3: Pre-set the gear machining sensitive area division lines, and match the shaft hole division lines within the gear machining sensitive area division lines with the gear steel shaft hole. This generates the area to be machined on the corrected gear steel image. After the gear steel image is corrected, an X, Y, and Z three-axis pixel coordinate system is generated with the shaft hole as the reference. By using the shaft hole as a reference for positioning, the gear machining sensitive area division lines can be aligned with the gear steel image, thus generating the area to be machined. This area is the machining area of ​​the milling component.

[0032] Step 4: The region to be processed within the image is located using a pixel coordinate system. Based on the location result, the milling component processes the gear steel for the tooth edge, tooth root, and keyway. The position parameters of the sensitive region division line are represented in the coordinate system, thereby generating the region to be processed and providing control signals to the milling component. The milling component then performs processing on specific parts of the gear steel.

[0033] Step 5: The second camera device tracks the milled part of the gear steel in real time, acquiring the machining edge contour image. This image is compared with the machining sensitive area delineation line in the pixel coordinate system. The comparison result is fed back to the milling assembly and a control signal is generated. Before the milling step, a transition milling area can be introduced in the scrap area as a test section. The second camera device tracks and captures this area synchronously, ensuring the milling assembly accurately enters the machining sensitive area delineation line.

[0034] Step Six: After the gear steel is machined and formed into gears, the shaft hole is polished and ground to remove the heat-affected zone caused by electrical discharge machining, ensuring the strength and quality of the shaft hole in the later assembly.

[0035] Example 1

[0036] A method for machining an eccentric gear is provided. The gear steel used for the eccentric gear is ZG42CrM. The outer diameter of the eccentric gear is 3000mm and the shaft hole diameter is 500mm. The first camera device is model MARS-1231-46G5C-P, the second camera device is model MER-131-210U3C, and the third camera device is model MER-131-210U3C.

[0037] S1. After the gear steel is initially positioned by the conveying equipment, it is fed to the cutting platform, where the shaft hole is machined by electric spark cutting. Then, the gear steel is precisely positioned by the positioning equipment that mates with the shaft hole.

[0038] S2. The positioning device transports the gear steel to the milling machine. The first camera device acquires the image of the gear steel. The Canny operator is used to perform edge detection on the image of the gear steel, and the horizontal operator is used to extract the edge, so as to obtain the corrected shaft hole edge curve and the outer edge curve of the gear steel.

[0039] S3. Pre-set the gear machining sensitive area division line, match the shaft hole division line within the gear machining sensitive area division line with the gear steel shaft hole, and generate the division area to be processed on the corrected gear steel image.

[0040] S4. The pixel coordinate system is used to locate the area to be processed in the image. The milling component processes the gear steel tooth edge, tooth root and keyway according to the positioning result. During processing, atomized cutting fluid is sprayed onto the milling part. The atomized cutting fluid has an atomized particle size of 0.5μm to 1μm and an atomization rate of 1ml / min.

[0041] S5. The second camera device tracks the milled part of the gear steel in real time, acquires the processing edge contour image, compares the processing edge contour image with the processing sensitive area division line in the pixel coordinate system, and feeds back the comparison result to the milling component and generates a control signal; the third camera device tracks the milled part of the gear steel in real time, acquires the processing depth contour image, compares the processing depth contour image with the processing sensitive area division line in the pixel coordinate system, and feeds back the comparison result to the milling component and generates a control signal.

[0042] S6. After the gear steel is processed and formed into gears, the shaft hole is polished and ground.

[0043] Fifteen actual detection points were scanned at the gear tooth root, tooth tip, and tooth profile depth, respectively, and compared with the theoretical profile points at the corresponding positions on the gear. The error results of the comparison are as follows: Figure 2 As shown.

[0044] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for machining an eccentric gear, characterized in that, include: Step 1: After the gear steel is initially positioned by the conveying equipment, it is fed to the cutting platform, where the shaft hole is machined by the cutting mechanism, and then the gear steel is precisely positioned by the positioning equipment that mates with the shaft hole. Step 2: The positioning equipment transports the gear steel to the milling machine, and the first camera device captures images of the gear steel. Perspective transformation is performed on specific boundaries to correct the deformed image of the gear steel to the actual image. After the first camera device acquires the image of the gear steel, it uses the Canny operator to perform edge detection on the gear steel image and uses the horizontal operator to extract the edge, obtaining the shaft hole edge curve and the outer edge curve of the gear steel. The perspective transformation function is formed by the distortion principle of the first camera device. Multiple point parameters on the shaft hole edge curve and the outer edge curve of the gear steel are passed into the perspective transformation function, and the output value regenerates the corrected shaft hole edge curve and the outer edge curve of the gear steel. Step 3: Pre-set the gear machining sensitive area division line, match the shaft hole division line within the gear machining sensitive area division line with the gear steel shaft hole, and generate the division area to be processed on the corrected gear steel image; Step 4: Use the pixel coordinate system to locate the area to be processed in the image, and the milling component will process the gear steel tooth edge, tooth root and keyway according to the positioning result; In step four, the milling part of the gear steel is tracked in real time by the third camera device to obtain the machining depth contour image. The machining depth contour image is compared with the machining sensitive area division line in the pixel coordinate system. The comparison result is fed back to the milling component and a control signal is generated. Step 5: The second camera device tracks the milled part of the gear steel in real time, acquires the processing edge contour image, compares the processing edge contour image with the processing sensitive area division line in the pixel coordinate system, and feeds back the comparison result to the milling component to generate a control signal.

2. The method for machining an eccentric gear according to claim 1, characterized in that, The shaft hole in step one is formed by electrical discharge machining.

3. The method for machining an eccentric gear according to claim 2, characterized in that, Step Six: After the gear steel is machined and formed into gears, the shaft hole is polished and ground.

4. The method for machining an eccentric gear according to claim 1, characterized in that, The second and third camera devices use distortion-free cameras.

5. The method for machining an eccentric gear according to claim 1, characterized in that, During the milling process in step four, atomized cutting fluid is sprayed onto the milling area. The atomized cutting fluid has a particle size of 0.1µm to 5µm and an atomization rate of 0.5ml / min to 3ml / min.

6. A method for machining an eccentric gear according to claim 5, characterized in that, The dust particle size during grinding of gear steel is between 0.1µm and 3µm.

7. A method for machining an eccentric gear according to claim 6, characterized in that, It also includes a ventilation system that creates an airflow circulation within the milling machine area to remove atomized cutting fluid and dust.

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