Low-rigidity thin-wall gear ring end face grinding tool

Abstract

The application discloses a low-rigidity thin-wall gear ring end face grinding tool, which comprises an electric permanent magnetic chuck, three fine-tuning precision lifting platforms, three arc-shaped clamping blocks and a flatness measuring device, the three fine-tuning precision lifting platforms and the three arc-shaped clamping blocks are alternately arranged on the surface of the electric permanent magnetic chuck with equal intervals. The application changes the traditional end face adsorption clamping into gear ring cylindrical surface clamping, changes the clamping force from axial to radial, and transfers the error to the non-sensitive direction of machining, so that the gear ring positioning can be rapidly realized, and the machining efficiency of the gear ring is improved; the end face will not be deformed and the error reflection problem will not occur under the large magnetic force, and the clamping force will not affect the precision of the end face grinding process. The electric permanent magnetic chuck is adopted for clamping, so that the deformation problem of the clamping position in the traditional clamping mode is avoided, and the end face grinding production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of gear processing equipment, specifically relating to a low-rigidity thin-walled gear ring end face grinding fixture. Background Technology

[0002] Planetary gear reducers, as a classic transmission structure, are characterized by small size, large transmission ratio, and high transmission efficiency, and are widely used in industrial sectors such as armored vehicles, wind power generation, engineering machinery, and aerospace.

[0003] A planetary gear reducer generally consists of a sun gear, planet gears, a ring gear, and a planet carrier. In recent years, transmission devices have gradually developed towards high-speed and heavy-load applications. Due to the combined internal and external meshing of planetary gear reducers, the meshing accuracy of the internal gears is crucial. Based on this trend, gear grinding in planetary reducers generally uses a precision of grade 5 or higher. However, high-precision gear manufacturing often requires precise control of each process. The ring gear, as a thin-walled part, is the component with the largest deformation and poorest precision in the planetary assembly, resulting in a low yield rate. The end face of the ring gear, as the main positioning surface in subsequent grinding processes, significantly affects the helix and tooth profile accuracy, so strict control of the end face flatness is essential. Existing end face positioning grinding fixtures generally consist of a worktable and a clamping device. The main principle is to place the ring gear on the worktable, and then the clamping device activates to fix the ring gear for end face grinding. While this positioning fixture method can meet the processing requirements of most gears, it is prone to deformation and poor flatness during the processing of weak-rigidity parts like the ring gear, resulting in a low yield rate for ring gear grinding. Therefore, if the flatness of the gear ring can be controlled within 1μm, it will facilitate the positioning and alignment during the subsequent gear grinding process and improve the yield of the gear ring.

[0004] Chinese Patent 113290502A discloses a "grinding fixture for gear end face grinding", which includes three parts: a base, a bent rod, and a clamping device. The fixture achieves the effect of clamping a large gear or a small gear by moving the push rod inside the clamping device.

[0005] Chinese patent CN219444505U discloses "an end face grinding device for gear processing". The device fixes the gear on one side of the machine tool and clamps the gear with a clamping component. The end face is ground by a grinding mechanism on the other side of the machine frame, which can realize the automation of grinding the end face of the gear ring.

[0006] Both patents mentioned above are improvements on existing end-face grinding fixtures without making any substantial changes. The first patent only considers the applicability of the end-face grinding fixture to different gears, but this patent increases the difficulty in manufacturing and assembly and cannot solve the problem of the original end face of the gear ring affecting the grinding flatness. Although the second patent improves production efficiency to some extent, this clamping method cannot improve the flatness of the gear end face.

[0007] In addition, some patents employ interference fits for gear end face grinding. Chinese patent CN219325127U discloses a "Floating Self-Adjusting Two-Top Clamp for Gear Outer Diameter and End Face Grinding," proposing a grinding clamping method suitable for gears with complex shapes and difficult machining. The gear part is fixed on a rotating mandrel, and radial constraint is achieved by the outer circle of a centering expansion sleeve engaging with the inner hole of the workpiece. This patent is applicable to end face grinding of various complex gears with high machining accuracy; however, the use of interference fits can lead to deformation problems in low-rigidity gears.

[0008] In summary, most previous patents focused on increasing grinding speed, such as by adding a re-grinding device, and improving clamping methods to accommodate gears of different specifications. However, none of them considered how to improve the end face grinding accuracy, nor did they address the deformation problem of low-rigidity gears from the perspective of the grinding device itself. Summary of the Invention

[0009] To address the aforementioned problems in the existing technology, this invention aims to design a low-rigidity thin-walled gear ring end face grinding fixture that can solve the deformation problem of low-rigidity gears.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows: a low-rigidity thin-walled gear ring end face grinding fixture, comprising an electro-permanent magnet chuck, a fine-tuning precision lifting platform, an arc-shaped clamping block, and a flatness measuring device, wherein there are three fine-tuning precision lifting platforms and three arc-shaped clamping blocks, which are placed alternately at equal intervals on the surface of the electro-permanent magnet chuck; the arc radius of the arc-shaped clamping block is equal to the radius of the gear ring and is completely in contact with the outer cylindrical surface of the gear ring;

[0011] The flatness measuring device includes a digital dial indicator, an adjustable connecting rod, and a rotary motor. The digital dial indicator is fixed to one end of the adjustable connecting rod, and the other end of the adjustable connecting rod is fixed to the rotary motor. The rotary motor is placed in the center of the electro-permanent magnet chuck. The flatness measuring device is used to measure the flatness of the end face of the ground gear ring.

[0012] Furthermore, the working method of the low-stiffness thin-walled gear ring end face grinding fixture includes the following steps:

[0013] Step 1: Place the fine-tuning precision lifting platform evenly on the electro-permanent magnet chuck, and return all the fine-tuning precision lifting platforms to the zero position to ensure that the upper surface of the fine-tuning precision lifting platform is on the same horizontal plane;

[0014] Step 2: Place the flatness measuring device on the electro-permanent magnet chuck, at the center of the arc-shaped clamp, start the flatness measuring device, rotate it one revolution, adjust the position of the digital dial indicator on the adjustable connecting rod so that the distance between the digital dial indicator and the rotary motor shaft is greater than the root circle radius of the gear ring to be measured and less than the radius of the outer cylindrical surface; adjust the installation position of the rotary motor according to the fluctuation of the data displayed by the digital dial indicator.

[0015] Step 3: Place the gear ring on the surface of the fine-tuning precision lifting platform, and move the gear ring so that the center of the gear ring is at the center of the electro-permanent magnet chuck.

[0016] Step 4: Fit the arc-shaped clamping block against the outer cylindrical surface of the gear ring;

[0017] Step 5: Remove the measuring device, start the electro-permanent magnet chuck, and the magnetic force is transmitted to the arc-shaped clamp, which generates an attractive force to attract the gear ring; start grinding the end face of the gear ring until the thickness of the gear ring meets the requirements;

[0018] Step 6: If the grinding of both end faces of the gear ring is complete, proceed to step 7; otherwise, flip the gear ring over and proceed to step 3.

[0019] Step 7: After grinding both ends of the gear ring, place the calibrated flatness measuring device back onto the electro-permanent magnet chuck for flatness testing to verify whether the end faces of the gear rings ground in this batch are qualified.

[0020] Compared with existing technologies, this solution has the following advantages:

[0021] 1. This invention changes the traditional end-face adsorption clamping to clamping via the cylindrical surface of the gear ring, changing the clamping force from axial to radial, thus transferring the error to a non-sensitive direction in the machining process. This allows for rapid positioning of the gear ring and improves the machining efficiency of the gear ring. The end face will not deform or reproduce errors under large magnetic forces, and the clamping force will not affect the accuracy of the grinding end face process.

[0022] 2. This invention uses an electro-permanent magnet chuck for clamping, replacing traditional clamping methods such as bolt tightening and interference clamping with magnetic clamping. This allows for rapid positioning and clamping of the gear ring, and ensures uniform clamping force across all positions on the end face of the gear ring. This avoids the deformation problem associated with traditional clamping methods and improves the efficiency of end face grinding production.

[0023] 3. The present invention uses arc-shaped clamping blocks for clamping. The surface-to-surface contact method reduces the stress concentration effect of traditional clamping methods. Furthermore, the number of arc-shaped clamping blocks can be changed according to the grinding parameters, making it suitable for various processing steps of gear roughing and fine grinding.

[0024] 4. This invention utilizes three fine-tuning precision lifting platforms, with three points defining a plane, providing a grinding platform with a flatness error of less than 1μm for the gear ring. Attached Figure Description

[0025] Figure 1 This is the overall assembly drawing of the gear ring grinding fixture.

[0026] Figure 2 This is a schematic diagram of a gear ring flatness measuring device.

[0027] Figure 3 This is a schematic diagram of an arc-shaped clamping block.

[0028] Figure 4 This is a schematic diagram of the gear ring of a certain planetary reducer.

[0029] Figure 5 A comparison diagram of the flatness of the end face ground using conventional tooling and the tooling of the present invention is provided (the comparison diagram of the flatness of the end face of conventional tooling and the tooling of the present invention has been enlarged; in reality, the change in the flatness of the end face of the gear ring is difficult to observe with the naked eye).

[0030] In the diagram: 1-Electro-permanent magnet chuck, 2-Gear ring, 3-Flatness measuring device, 4-Arc-shaped clamp, 5-Fine adjustment precision lifting platform, 6-Rotary motor, 7-Adjustable connecting rod, 8-Digital dial indicator. Detailed Implementation

[0031] The invention will now be further described with reference to the accompanying drawings. A method for using a low-stiffness, thin-walled gear ring end face grinding fixture is as follows:

[0032] Step 1: Prepare the electro-permanent magnet chuck 1 and the fine-tuning precision lifting platform 5. The support of these two components will affect the accuracy of the gear ring end face. The flatness of its surface should be within 5μm. Prepare the flatness measuring device 3 and the arc-shaped clamp 4.

[0033] Step 2: Turn off the electro-permanent magnet chuck 1, and place the three fine-tuning precision lifting platforms 5 evenly on the electro-permanent magnet chuck 1 at a 120° angle. Adjust the micrometer screw of the fine-tuning precision lifting platform 5 to restore the three fine-tuning precision lifting platforms 5 to their initial positions, ensuring that the upper surfaces of the three fine-tuning precision lifting platforms 5 are on the same horizontal plane.

[0034] Step 3: Assemble the flatness measuring device. Use the tightening nut to install the rotary motor 6 and the digital dial indicator 8 onto the adjustable connecting rod 7. Ensure that the spindle of the rotary motor 6 and the adjustable connecting rod 7 are as perpendicular as possible (this will affect the flatness value but not the adjustment of the flatness trend). When installing the digital dial indicator 8, select a suitable mounting hole according to the specific dimensions of the gear ring 2. Install the rotary motor 6 at the center of the electro-permanent magnet chuck 1, start the rotary motor 6, check the runout of the digital dial indicator 8, and adjust the position of the connecting rod 7 according to the result to ensure the accuracy of the flatness measuring device 3.

[0035] Step 4: Place the gear ring 2 to be processed on the three fine-tuning precision lifting platforms 5, ensuring that the gear ring 2 to be processed is positioned at the center of the electro-permanent magnet chuck 1.

[0036] Step 5: Gently attach three or more arc-shaped clamps 4 to the outer cylindrical surface of the gear ring 2 to be processed. The arc-shaped surface should be the same size as the outer cylinder of the gear ring 2 to provide sufficient adsorption force for the gear ring 2.

[0037] Step Six: Activate the electro-permanent magnet chuck 1. The magnetic force mainly uses the arc-shaped clamping block 4 to attract and fix the gear ring 2 to its outer cylinder. A fine-tuning precision lifting platform 5 exists between the end face of the gear ring 2 and the end face of the electro-permanent magnet chuck 1, preventing excessive attraction that could cause tilting or deformation of the gear ring 2's end face. Finally, grind the end face of the gear ring 2. This clamping method maximizes the flatness of the gear ring 2's end face. When grinding the other end face, repeat steps four to six. For example, the results are comparable. Figure 5 As shown in the figure, the wavy line represents the undulating shape of the surface of the gear ring 2. By drawing a plane through the bottom and top of the wavy line, it can be clearly seen that the tooling of the present invention can effectively reduce the flatness of the end face of the gear ring 2.

[0038] Step 6: After grinding both ends of the gear ring 2, place the calibrated flatness measuring device 3 back on the center of the electro-permanent magnet chuck 1 to perform flatness testing, ensuring that the center of the measurement trajectory coincides with the center of the gear ring.

[0039] This invention is not limited to this embodiment. Any equivalent concept or modification within the technical scope disclosed in this invention shall be included within the protection scope of this invention.

Claims

1. A working method for a low-stiffness, thin-walled gear ring end face grinding fixture, characterized in that, Based on a low-rigidity thin-walled gear ring end face grinding fixture, the fixture includes an electro-permanent magnet chuck (1), a fine-tuning precision lifting platform (5), an arc-shaped clamp (4), and a flatness measuring device (3). There are 3 fine-tuning precision lifting platforms (5) and 3 arc-shaped clamps (4). The 3 fine-tuning precision lifting platforms (5) and 3 arc-shaped clamps (4) are placed alternately at equal intervals on the surface of the electro-permanent magnet chuck (1). The inner arc radius of the arc-shaped clamp (4) is equal to the outer arc radius of the gear ring (2) and is completely in contact with the outer cylindrical surface of the gear ring (2). The flatness measuring device (3) includes a digital micrometer (8), an adjustable connecting rod (7), and a rotary motor (6). The digital micrometer (8) is fixed to one end of the adjustable connecting rod (7), and the other end of the adjustable connecting rod (7) is fixed to the rotary motor (6). The rotary motor (6) is placed in the center of the electro-permanent magnet chuck (1). The flatness measuring device (3) is used to measure the flatness of the end face of the ground gear ring (2). The method includes the following steps: Step 1: Place the fine-tuning precision lifting platform (5) evenly on the electro-permanent magnet chuck (1), and restore all the fine-tuning precision lifting platforms (5) to the zero position to ensure that the upper surface of the fine-tuning precision lifting platform (5) is on the same horizontal plane; Step 2: Place the flatness measuring device (3) on the electro-permanent magnet chuck (1) at the center of the arc-shaped clamp (4), start the flatness measuring device (3), rotate it one revolution, adjust the position of the digital dial indicator (8) on the adjustable connecting rod (7) so that the distance between the digital dial indicator (8) and the shaft of the rotary motor (6) is greater than the root circle radius of the gear ring (2) to be measured and less than the radius of the outer cylindrical surface; adjust the installation position of the rotary motor (6) according to the data jump displayed by the digital dial indicator (8); Step 3: Place the gear ring (2) on the upper surface of the fine-tuning precision lifting platform (5), and move the gear ring (2) so that the center position of the gear ring (2) is at the center position of the electro-permanent magnet chuck (1); Step 4: Fit the arc-shaped clamp (4) to the outer cylindrical surface of the gear ring (2); Step 5: Remove the measuring device, start the electro-permanent magnet chuck (1), and the magnetic force is transmitted to the arc-shaped clamp (4) to generate an attractive force to the gear ring (2); start grinding the end face of the gear ring (2) until the thickness of the gear ring (2) meets the requirements; Step 6: If the grinding of both end faces of the gear ring (2) is completed, proceed to step 7; otherwise, flip the gear ring (2) over and proceed to step 3. Step 7: After grinding both ends of the gear ring (2), the calibrated flatness measuring device (3) is placed back on the electro-permanent magnet chuck (1) to perform flatness testing and check whether the end faces of the gear ring (2) after this batch of grinding are qualified.

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