A precision machining method for cycloidal gears used in RV reducers

Abstract

The present application relates to the field of gear precision machining technology, and specifically to a method for precision machining cycloid gears for RV reducers. The method comprises: comparing the distribution differences of distance data at each position at different rotation angles to obtain the collision vibration degree at each position of the cycloid gear; obtaining the grinding vibration separation at each position of each tooth of the cycloid gear based on the distribution characteristics of the collision vibration degrees corresponding to the same position sequence of different gear teeth; analyzing the fluctuations of the grinding vibration separation at all positions of the cycloid gear to determine the machining regularity of the cycloid gear; and obtaining the feed adjustment error of the diamond wheel based on the overall distribution of the collision vibration degrees at all positions of the cycloid gear and the machining regularity, in combination with the rotation time of the cycloid gear and the feed rate of the diamond wheel, and determining the feed rate of the diamond wheel after adjustment. The present application aims to improve the machining accuracy of cycloid gears.

Description

Technical Field

[0001] The present application relates to the technical field of gear precision machining, and in particular to a method for precision machining of cycloid gears for RV reducers. Background Art

[0002] The RV reducer is a high-precision, high-rigidity precision reduction device widely used in high-end equipment such as industrial robots and CNC machine tools. It comprises a two-stage reduction structure: a planetary gear transmission and a cycloidal pinwheel transmission. This structure achieves deceleration and torque increase, improving precision and rigidity. The cycloidal gear is a core component, featuring a cycloidal tooth profile meshing with pinwheels and driven by an eccentric shaft for high-precision transmission. Precision machining of cycloidal gears requires three steps: rough grinding, semi-finishing grinding, and fine grinding. During the grinding process, the feed rate is a key factor in determining the precision of the diamond wheel in machining cycloidal gears. A higher feed rate results in a greater unit feed during machining, which in turn increases the grinding force on the diamond wheel and reduces the accuracy of the cycloidal gear. Traditionally, this method measures the thickness of the unmachined area and then adjusts the diamond wheel feed rate.

[0003] With the development of machine learning technology, laser measurement has been applied to industrial processing due to its high precision, small detection spacing, and convenience. However, in the processing of cycloidal gears, the friction between the cycloidal gear and the diamond wheel when grinding the cycloidal gear causes the cycloidal gear to vibrate, resulting in errors in the data measured by laser, resulting in reduced processing accuracy of the cycloidal gear. Summary of the Invention

[0004] In view of the above, it is necessary to provide a precision machining method for cycloid gears of RV reducers to solve the above problems.

[0005] One embodiment of the present application provides a method for precision machining a cycloid gear for an RV reducer, the method comprising:

[0006] Collect distance data for each position on the cycloid gear at each rotation angle;

[0007] Compare the distribution difference of the distance data of each position at each rotation angle with the distance data of the same position at different rotation angles to obtain the collision vibration degree of each position;

[0008] The collision vibration degree at all positions on each gear tooth is obtained and sorted according to the rotation direction of the cycloid gear. Based on the distribution characteristics of the collision vibration degree of different gear teeth corresponding to the same position sequence, the grinding vibration separation value at each position on each gear tooth of the cycloid gear is obtained.

[0009] Analyze the fluctuation of grinding vibration phase separation at all positions of cycloid gears to confirm the machining regularity of cycloid gears;

[0010] Based on the overall distribution of collision vibration at all positions of the cycloid gear and the machining regularity, combined with the rotation time of the cycloid gear and the feed rate of the diamond wheel, the feed adjustment error of the diamond wheel is obtained;

[0011] According to the feed adjustment error of the diamond wheel, confirm the feed rate of the diamond wheel after adjustment.

[0012] Preferably, the rotation angles are selected at equal intervals according to the rotation direction at preset angles.

[0013] Preferably, the time interval between collecting data of the same position of the cycloid gear for collecting two adjacent rotation angles is equal to the time required for the cycloid gear to rotate by a preset angle.

[0014] Preferably, the collision vibration degree at each position is obtained by:

[0015] Calculate the mean value of the distance data at each position under all rotation angles; calculate the difference between each rotation angle and the mean value of the distance data, average the corresponding differences under all rotation angles, and obtain the collision vibration degree at each position.

[0016] Preferably, the difference between each rotation angle and the mean of the distance data is determined by the absolute value of the difference.

[0017] Preferably, the grinding vibration separation amount at each position of each tooth of the cycloid gear is obtained as follows:

[0018] Extract the collision vibration degree of all positions corresponding to each tooth in the cycloid gear to form a collision vibration degree subsequence;

[0019] The element range value of each position sequence in all collision vibration degree subsequences is obtained as the grinding vibration separation value of each position in each tooth of the cycloid gear.

[0020] Preferably, the determination of the processing regularity of the cycloid gear is specifically as follows:

[0021] The sequence of grinding vibration separations at all positions of each tooth of the cycloid gear is recorded as a grinding vibration separation sequence;

[0022] The difference between the number of extreme points after filtering of the grinding vibration separation sequence and the preset number of extreme points is obtained, and after positive fusion with the preset value, negative correlation mapping is performed to obtain the processing regularity of the cycloid gear.

[0023] Preferably, the specific formula for obtaining the feed adjustment error of the diamond wheel is: Where, Indicates the feed adjustment error of the diamond wheel; represents the average collision vibration of the cycloid gear at all positions; t represents the time required for the cycloid gear to rotate by a preset angle; Indicates the current feed rate of the diamond wheel; It represents the processing regularity of cycloid gear; exp() represents the exponential function with natural constant as base.

[0024] Preferably, the feed rate of the diamond wheel after adjustment is determined according to the feed adjustment error of the diamond wheel, specifically:

[0025] The ratio of the feed adjustment error of the diamond wheel to the time required for the cycloid gear to rotate a preset angle is calculated, and the difference between the current feed rate of the diamond wheel and the ratio is used as the adjusted feed rate of the diamond wheel.

[0026] Preferably, the adjustment time interval of the diamond wheel feed rate is equal to the time required for the cycloid gear to rotate a preset angle.

[0027] This application has at least the following beneficial effects:

[0028] The embodiment of the present application collects data through a laser rangefinder and calculates the collision vibration degree to accurately evaluate the vibration conditions during processing; based on this, the grinding vibration separation amount is calculated to further optimize the feed adjustment error of the diamond wheel, thereby adjusting the feed rate, effectively reducing the processing error, and making the cycloid gear dimensional accuracy closer to the design requirements, meeting the strict high-precision requirements in the high-end equipment field, and laying the foundation for subsequent improvement of processing stability.

[0029] The fluctuations in impact vibration are used to calculate the machining regularity, providing a direct reflection of the regularity of grinding vibration. If the regularity is abnormal, the diamond wheel feed rate is adjusted promptly to avoid increased vibration caused by unstable grinding forces, reduce machining fluctuations, and enhance the stability of the entire machining process. A stable machining process not only ensures precision, but also reduces scrap rates and improves production efficiency.

[0030] Based on high precision and high stability, this application reduces rework and scrap caused by machining errors, significantly improving production efficiency. At the same time, the quality of each batch of cycloid gears is more consistent, reducing quality fluctuations, improving product reliability, enhancing the company's market competitiveness in the field of high-end equipment, and bringing greater economic benefits to the company. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a cycloid gear precision machining method for an RV reducer provided in this application;

[0032] Figure 2This is a partial schematic diagram of the teeth of the cycloid gear provided in this application. DETAILED DESCRIPTION

[0033] In the description of the embodiments of this application, words such as "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "or," and "for example" is intended to present the relevant concepts in a concrete manner.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of this application. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] It should also be noted that the terms "first" and "second" in this application and its accompanying drawings are used to distinguish similar objects, rather than to describe a specific order or precedence. The methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the methods. Without departing from the scope of protection of this application, the order of execution of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0036] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0037] This application proposes a cycloid gear precision machining method for RV reducer, which is applied to the field of gear precision machining technology. Figure 1 , the method comprises the following steps:

[0038] S1: Collect the distance data of each position on the cycloid gear at each rotation angle.

[0039] During the machining process of a cycloid gear, the gear is typically placed horizontally, and each tooth is machined by rotating the gear. In this embodiment, the center of the cycloid gear is used as the origin, and the contact point between the cycloid gear and the diamond wheel is at 0 degrees. A laser rangefinder is installed at 60 degrees, 120 degrees, and 180 degrees along the cycloid gear's rotational direction. Each laser rangefinder is positioned at the same distance from the gear's cycloid center. Distance data at each position on the cycloid gear is measured using the laser rangefinder.

[0040] During the processing of the cycloid gear, the axial feed speed of the cycloid gear ranges from In this embodiment, the value is 1500mm / min. The time for the cycloid gear to rotate one circle is , where L represents the circumference of the minimum circumscribed circle corresponding to the current cycloid gear. That is, the maximum radius from the edge of the cycloid gear to its center is obtained as the radius of the minimum circumscribed circle. The value of L is obtained according to the circumference formula of a circle. Since the interval angle between the two laser rangefinders is 60 degrees, the difference between the measurement data of the same position of the cycloid gear by adjacent laser rangefinders is t. Thus, for the data collected by the laser rangefinder installed at 60 degrees, the data collected by the laser rangefinder installed at 120 degrees after time t, and the data collected by the laser rangefinder installed at 180 degrees after time 2×t. The time for each data collection is t min, and the collection frequency is 10 kHz.

[0041] The distance data measured by the laser rangefinder at each rotation angle is arranged in chronological order to form a gear grinding distance sequence corresponding to each rotation angle. Thus, in this embodiment, three gear grinding distance sequences are obtained. Elements at the same position in the sequence represent data from the same position on the cycloid gear.

[0042] It should be noted that the implementer can set the positions of the laser rangefinders at equal intervals according to actual conditions, and this application does not impose any restrictions on this.

[0043] S2: Compare the distribution difference of the distance data of each position at each rotation angle with the distance data of the same position at different rotation angles to obtain the collision vibration degree of each position.

[0044] During the machining process of a cycloid gear, friction occurs between the cycloid gear and the diamond wheel. This friction causes the cycloid gear to heat up and vibrate, which in turn leads to errors in the thickness measurement of the unmachined area of the cycloid gear.

[0045] For the same position on a cycloid gear, in the absence of vibration, the data measured by a laser rangefinder should be identical. However, during the actual machining process, the diamond wheel grinding the cycloid gear causes collisions between the diamond wheel and the cycloid gear, causing the cycloid gear to vibrate. The greater the difference between the values measured by the laser rangefinder at the same position on the cycloid gear, the stronger the vibration. Therefore, the collision vibration degree at different positions on the cycloid gear is calculated using data from different laser rangefinders: the mean of the elements of the same position in all gear grinding distance sequences is calculated; the difference between each element in each gear grinding distance sequence and the mean of the element of the corresponding position is calculated, and the corresponding differences across all gear grinding distance sequences are averaged to obtain the collision vibration degree at the corresponding position of each element. In this embodiment, the difference between variables is calculated using the absolute value of the difference.

[0046] It should be understood that in the analysis of cycloidal gear machining accuracy, higher collision vibrations indicate more unstable grinding forces between the cycloidal gear and the diamond wheel during machining, resulting in reduced stability of the cycloidal gear and, in turn, impacting machining accuracy. Therefore, the machining error assessment results derived from collision vibration calculations are more valuable for reference. When monitoring the quality of the cycloidal gear machining process, accurately measuring collision vibrations can effectively improve the controllability of machining quality and ensure that the cycloidal gear machining accuracy meets the expected standards.

[0047] S3: Obtain the collision vibration degrees at all positions on each gear tooth and sort them according to the rotation direction of the cycloid gear. Based on the distribution characteristics of the collision vibration degrees of different gear teeth corresponding to the same position sequence, obtain the grinding vibration separation at each position on each gear tooth of the cycloid gear.

[0048] The processing of cycloid gears is to grind the teeth of cycloid gears. The teeth of cycloid gears are not smooth planes, but smooth curved surfaces. Therefore, during the grinding process, the tangential angles of contact between the diamond wheel and different positions in the tooth profile are different, resulting in different cutting forces between the diamond wheel and different positions in the tooth profile, and the resulting vibration amounts are also different.

[0049] At the same time, since the processing of cycloid gears requires that the shape of each gear tooth is the same, the collision vibration between the diamond wheel and the cycloid gear has a certain periodicity. The length of the cycle is: , where m represents the number of teeth in the cycloid gear, which is 39 in this embodiment. Therefore, the data length corresponding to each tooth of the cycloid gear is: Where f is the sampling frequency, which is 10kHz in this example.

[0050] Sort the elements of the collision vibration degree according to the rotation direction of the cycloid gear to obtain the collision vibration degree sequence. Sort the collision vibration degree sequence into A subsequence is split, and the final length is insufficient The remaining part is discarded. Because the grinding forces on different teeth should be the same, the collision vibration levels at the same position on different teeth should also be the same. Large differences in the collision vibration levels at the same position on different teeth indicate that the diamond wheel cannot perform stable grinding on the cycloid gear. This can easily lead to excessive grinding, reducing the accuracy of the cycloid gear. Therefore, the extreme difference values of the elements at each position in all collision vibration subsequences are obtained as the grinding vibration separation value for each position on each tooth of the cycloid gear.

[0051] It should be understood that when evaluating the machining accuracy of cycloidal gears, the magnitude of the grinding vibration separation directly reflects the fluctuations in the collision vibration levels at corresponding positions on different gear teeth. A large grinding vibration separation indicates significant variations in the force exerted by the diamond wheel on the cycloidal gear during the grinding process. This instability can reduce machining accuracy. In the precision machining of cycloidal gears, it is necessary to reduce the grinding vibration separation to ensure that the diamond wheel can more closely machine the cycloidal gear and improve machining accuracy.

[0052] S4: Analyze the fluctuation of grinding vibration phase separation at all positions of cycloid gear and confirm the machining regularity of cycloid gear.

[0053] The grinding vibration separation amount at each position of the cycloid gear tooth is obtained, and the separation amount is arranged according to the rotation direction to obtain a grinding vibration separation amount sequence.

[0054] The gear teeth of the cycloid gear are composed of two parts: the tooth top and the tooth bottom. The partial schematic diagram of the gear teeth of the cycloid gear is as follows: Figure 2 As shown. For the grinding vibration separation sequence, the data formed at different positions of a gear tooth, and for different positions of a gear tooth, the vibrations caused are different due to the different grinding angles between different positions and the diamond wheel. The grinding vibration separation sequence only contains a tooth top and its adjacent tooth bottom. Therefore, in an ideal case, the grinding vibration separation sequence should also have only one peak and one trough. In order to reduce the impact of subtle fluctuations on the data, the grinding vibration separation sequence is used as the input of the SG filtering algorithm, and the output result is used as the input of the extreme point detection algorithm. The output is all the extreme values after the grinding vibration separation sequence is filtered. Among them, the calculation of the SG filtering algorithm and the extreme point detection algorithm is an existing well-known technology, and the specific calculation steps will not be repeated here.

[0055] Specifically, the difference between the number of extreme points after filtering the grinding vibration separation sequence and the preset number of extreme points is obtained, and after forward fusion with the preset value, a negative correlation mapping is performed to obtain the processing regularity of the cycloid gear. In this embodiment, the difference between the variables is calculated using the absolute value of the difference; the forward fusion of multiple variables uses the addition calculation method; the preset value range is [0.5, 2], and the value in this embodiment is 1. The preset value can prevent the denominator from being 0 on the one hand, and on the other hand, it can prevent the difference from being too small, resulting in an excessively large processing regularity; the negative correlation mapping of the variable is specifically the inverse of the variable;

[0056] It should be understood that when evaluating cycloidal gear machining stability, the level of machining regularity directly reflects the regularity of the extreme values in the grinding vibration phase separation sequence. A low machining regularity indicates that the vibration regularity during grinding is disrupted, and the interaction between the diamond wheel and the cycloidal gear fluctuates significantly. This irregularity reduces machining stability. In the precision machining of cycloidal gears, it is necessary to increase the machining regularity to ensure more stable machining of the cycloidal gear by the diamond wheel, thereby ensuring machining accuracy and quality.

[0057] S5: Based on the overall distribution of the collision vibration degree at all positions of the cycloid gear and the processing regularity, combined with the time it takes for the cycloid gear to rotate a preset angle and the feed rate of the diamond wheel, the feed adjustment error of the diamond wheel is obtained.

[0058] When the value of the machining regularity of the cycloid gear increases during machining, the error of the cycloid gear will increase. In this case, it is necessary to reduce the feed rate of the diamond wheel on the cycloid gear during machining, that is, to reduce the grinding force of the diamond wheel to ensure smooth and stable machining of the cycloid gear and reduce the machining error of the cycloid gear. Therefore, the feed adjustment error of the diamond wheel is calculated as follows: Where, Indicates the feed adjustment error of the diamond wheel; represents the average collision vibration of the cycloid gear at all positions; t represents the time required for the cycloid gear to rotate by a preset angle, which is 60 degrees in this embodiment; Indicates the current feed rate of the diamond wheel. Generally, the initial value range is [0.1, 2] mm / min. In this implementation, the value is 1 mm / min. It represents the processing regularity of cycloid gears during the processing; exp() represents an exponential function with a natural constant as the base.

[0059] It should be understood that the more irregular the vibration is during the cycloid gear processing, the more regular the processing of the cycloid gear will be, which will lead to an increase in the processing error of the cycloid gear and the feed adjustment error of the diamond wheel. It is necessary to reduce the feed adjustment error of the diamond wheel to improve the processing accuracy of the cycloid gear.

[0060] S6: Confirming the feed rate of the diamond wheel after adjustment according to the feed adjustment error of the diamond wheel.

[0061] The feed adjustment error of the diamond wheel is input into the control system of the cycloid gear processing CNC machine tool. The system will calculate the adjusted feed rate based on the feed adjustment error of the diamond wheel. , the calculation formula is During the machining process, the CNC machine's control system inputs the adjusted feed rate into the PID controller. The PID controller calculates and outputs a control signal using a built-in PID algorithm. The control system uses the PID output to adjust the diamond wheel's feed rate in real time. The diamond wheel's feed rate adjustment interval is equal to the time required for the cycloid gear to rotate a preset angle, ensuring precise machining of the cycloid gear. Ultimately, the CNC machine's high-precision grinding operation transforms the material into a cycloid gear, achieving precise machining of the cycloid gear.

[0062] The flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to the embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the part of the module, program segment or code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action, or may be implemented by a combination of dedicated hardware and computer instructions.

[0063] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A precision machining method for cycloid gears used in RV reducers, characterized in that: The method comprises the following steps: Collect distance data for each position on the cycloid gear at each rotation angle; Compare the distribution difference of the distance data of each position at each rotation angle with the distance data of the same position at different rotation angles to obtain the collision vibration degree of each position; The collision vibration degree at all positions on each gear tooth is obtained and sorted according to the rotation direction of the cycloid gear. Based on the distribution characteristics of the collision vibration degree of different gear teeth corresponding to the same position sequence, the grinding vibration separation at each position on each gear tooth of the cycloid gear is obtained. Analyze the fluctuation of grinding vibration phase separation at all positions of cycloid gears to confirm the machining regularity of cycloid gears; Based on the overall distribution of collision vibration at all positions of the cycloid gear and the processing regularity, combined with the rotation time of the cycloid gear and the feed rate of the diamond wheel, the feed adjustment error of the diamond wheel is obtained; According to the feed adjustment error of the diamond wheel, confirm the feed rate of the diamond wheel after adjustment.

2. A cycloid gear precision machining method for an RV reducer according to claim 1, characterized in that: The rotation angles are selected at equal intervals according to the rotation direction using the preset angles.

3. The method for precision machining of cycloid gears for RV reducers according to claim 1, characterized in that: The time interval between the data collection of the same position distance of two adjacent rotation angle collection cycloid gears is equal to the time required for the cycloid gear to rotate the preset angle.

4. The method for precision machining of cycloid gears for RV reducers according to claim 1, wherein: The collision vibration degree at each position is obtained as follows: Calculate the mean value of the distance data at each position under all rotation angles; calculate the difference between each rotation angle and the mean value of the distance data, average the corresponding differences under all rotation angles, and obtain the collision vibration degree at each position.

5. A cycloid gear precision machining method for an RV reducer according to claim 4, characterized in that: The difference between each rotation angle and the mean value of the distance data is determined by the absolute value of the difference.

6. The method for precision machining of cycloid gears for RV reducers according to claim 1, characterized in that: The grinding vibration separation amount at each position of each tooth of the cycloid gear is obtained as follows: Extract the collision vibration degree of all positions corresponding to each tooth in the cycloid gear to form a collision vibration degree subsequence; The element range value of each position sequence in all collision vibration degree subsequences is obtained as the grinding vibration separation value of each position in each tooth of the cycloid gear.

7. The method for precision machining of cycloid gears for RV reducers according to claim 1, characterized in that: The determination of the processing regularity of the cycloid gear is specifically as follows: The sequence of grinding vibration separations at all positions of each tooth of the cycloid gear is recorded as a grinding vibration separation sequence; The difference between the number of extreme points after filtering the grinding vibration separation sequence and the preset number of extreme points is obtained, and after positive fusion with the preset value, negative correlation mapping is performed to obtain the processing regularity of the cycloid gear.

8. The method for precision machining of cycloid gears for RV reducers according to claim 3, wherein: The specific formula for obtaining the feed adjustment error of the diamond wheel is: Where, Indicates the feed adjustment error of the diamond wheel; represents the average collision vibration of the cycloid gear at all positions; t represents the time required for the cycloid gear to rotate by a preset angle; Indicates the current feed rate of the diamond wheel; It represents the processing regularity of cycloid gear; exp() represents the exponential function with natural constant as base.

9. A cycloid gear precision machining method for an RV reducer according to claim 8, characterized in that: The feed rate of the diamond wheel after adjustment is determined according to the feed adjustment error of the diamond wheel, specifically: The ratio of the feed adjustment error of the diamond wheel to the time required for the cycloid gear to rotate a preset angle is calculated, and the difference between the current feed rate of the diamond wheel and the ratio is used as the adjusted feed rate of the diamond wheel.

10. A cycloid gear precision machining method for an RV reducer according to claim 9, characterized in that: The adjustment time interval of the diamond wheel feed rate is equal to the time required for the cycloid gear to rotate a preset angle.

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