A gear profile measurement system and method

Abstract

The application discloses a gear profile measurement system and method, comprising a measurement module, a sample loading module and a data processing module; the measurement module comprises a measuring head, an auxiliary lifting structure and a sensor, the measuring head can scan and measure a gear to be measured; the auxiliary lifting structure can lift the measuring head; the sensor can collect displacement data of the measuring head and output the displacement data to the data processing module; the sample loading module can drive the gear to be measured to rotate; the data processing module can determine whether the measuring head is in a climbing stage according to the received displacement data, control the auxiliary lifting structure to lift the measuring head in the climbing stage, lower the measuring head at the top of the gear and control the sample loading module to switch the rotation direction after one rotation; the auxiliary lifting structure is controlled to lift the measuring head, so that the measuring head skips the climbing stage and prevents the measuring head from being stuck during the measurement; the full profile of the gear to be measured is obtained by using forward and reverse rotation scanning of the measuring head, errors are separated by using the data processing module, and the measurement result accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gear measurement, and in particular to a gear profile measurement system and method. Background Art

[0002] Harmonic gear transmission technology is a new type of transmission technology with the advantages of large transmission ratio, simple structure, smooth movement, low impact and low noise. It is widely used in robotics, aerospace, CNC machine tools, ships, energy and other fields. The harmonic gear device consists of a rigid wheel, a flexible wheel and a wave generator. During the meshing process, the wave generator drives the flexible wheel to deform, thereby realizing the transmission of power and motion. As a key component of robots, harmonic reducers have an important impact on the manufacturing and technological development of robots. However, at present, the performance of domestic harmonic reducers is quite different from that of foreign ones, and most high-end products are imported. Therefore, the research on harmonic reducer related technologies has a great driving force for the development of China's robotics industry.

[0003] The meshing of the flexspline and rigid wheel during operation of a harmonic reducer is crucial to the transmission process. The compliance of the gear tooth profile of the actual component with the design requirements is crucial for a smooth transmission. A good tooth profile can improve the transmission performance of the harmonic reducer, making gear tooth profile measurement essential. Furthermore, the meshing and wear conditions during transmission are of great value in gear tooth profile design. By analyzing the surface profile of the meshed flexspline and rigid wheel after operation, the operating condition of the harmonic reducer can be determined, guiding tooth profile improvements to improve the meshing between the flexspline and rigid wheel. However, the flexspline and rigid wheel of a harmonic reducer have small modules and a variety of tooth profiles. Their modules range from 0.2 to 0.5 mm, and their tooth height and pitch are generally less than 1 mm, making measurement challenging. Furthermore, there are many different types of gear tooth profiles, and commonly used gear measurement equipment often uses involute tooth profile comparisons to obtain measurement results. Standard measurement equipment is not available for measuring the profiles of other tooth profiles, such as double circular arcs and cycloids. Currently, commonly used methods for measuring gear profiles include three-dimensional coordinate measuring machines (CMMs), step profilers, optical measurement, and image recognition. CMMs are generally used to measure the profiles of larger workpieces, and their probes are relatively large in diameter, making it difficult to measure the profiles of small parts with complex contours. Step profilers, designed to measure the profiles of planar structures, cannot measure the entire circumference of a gear. They are also prone to jamming and needle skipping when measuring the flanks of the gear's ascending section, reducing measurement accuracy and even damaging the probe and the workpiece surface. Optical measurement, due to the large flank slope of small-module gear teeth, often causes the measuring light to be reflected in other directions and not return to the receiver, resulting in loss of measurement data. Image recognition can capture images of the gear's edges, but only the end face profile is obtained, not the mid-section profile. Furthermore, edge blurring also presents a problem, making it unsuitable for measuring the profiles of small-module gears. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problem of low gear profile measurement accuracy and to provide a gear profile measurement system and method.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A gear profile measurement system includes a measurement module, a sample loading module, and a data processing module; the measurement module includes a probe, an auxiliary lifting structure, and a sensor, wherein the probe can scan and measure the gear to be measured; the auxiliary lifting structure can lift the probe; the sensor can collect displacement data of the probe and output the displacement data to the data processing module; the sample loading module can drive the gear to be measured to rotate; the data processing module can determine whether the probe is in a climbing stage based on the received displacement data, control the auxiliary lifting structure to lift the probe during the climbing stage, lower the probe on the top of the gear, and control the sample loading module to switch direction after rotating one circle.

[0007] In some embodiments of the present invention, the sensor includes a first displacement sensor and a second displacement sensor, and the first displacement sensor and the second displacement sensor are installed relative to each other, and the angle between their axes is greater than 179° and less than 180°.

[0008] In some embodiments of the present invention, the data processing module performs installation error separation and rotation error separation based on the data collected by the first displacement sensor and the second displacement sensor to obtain a restored profile of the gear after error separation.

[0009] In some embodiments of the present invention, the measurement module further includes an auxiliary probe for separating rotation errors.

[0010] In some embodiments of the present invention, the measuring head is a probe, the auxiliary measuring head is an optical measuring head, and the sample loading module is a precision turntable.

[0011] In some embodiments of the present invention, the data processing module separates the installation error using the following formula:

[0012]

[0013] Among them, θ i is the angle between the probe and the initial measuring position centered on the gear being measured, β i is the angle between the horizontal axis and the initial measurement position, e is the eccentricity error, α0 is the eccentricity angle, s is the alignment error, r i is the radius of the gear being measured.

[0014] In some embodiments of the present invention, the data processing module performs an inverse Fourier transform on R(ω) to obtain the profile information of the gear being measured. The expression of R(ω) is:

[0015] R(ω)=S(ω) / H(ω)

[0016] Wherein, S(ω) is the result of Fourier transform of S, S is a weighted summation formula constructed by combining the measurement results of the first displacement sensor and the measurement results of the second displacement sensor, and H(ω) is a weight function.

[0017] In some embodiments of the present invention, the data processing module separates the rotation error using the following formula:

[0018]

[0019] Among them, S A (γ) is the measurement result of the first displacement sensor, S B (γ) is the measurement result of the second displacement sensor, c0 and c1 are weight coefficients, γ is the angle between the probe and the initial measurement position with the gear being measured as the center, is the angle between the first displacement sensor and the second displacement sensor, r(γ) is the radius of the gear under test at angle γ, The angle of the gear being measured The radius below.

[0020] In some embodiments of the present invention, the auxiliary lifting structure includes a single chip microcomputer and an electric push rod, and the single chip microcomputer can drive the electric push rod to lift the probe according to the signal sent by the data processing module.

[0021] The present invention also proposes a gear profile measurement method, which uses the gear profile measurement system as described above to measure the profile of the gear to be measured, including the following steps: S1: driving the sample loading module to rotate, thereby driving the gear to be measured installed on the sample loading module to rotate; S2: measuring the gear to be measured by scanning the probe; S3: collecting the displacement data of the probe through the sensor; S4: receiving the displacement data through the data processing structure, and judging whether the probe is in the climbing stage, if so, the data processing module sends a signal to control the auxiliary lifting structure to lift the probe, and lower the probe on the top of the gear; S5: controlling the sample loading module to rotate one circle and then switch the direction through the data processing module; S6: outputting the gear restoration profile through the data processing module.

[0022] The present invention has the following beneficial effects:

[0023] The gear profile measurement system proposed in the present invention uses a probe to scan the profile of the gear to be measured. The sensor collects the displacement data of the probe and outputs the displacement data to the data processing module. The data processing module can control the auxiliary lifting structure to lift the probe and output the gear restoration profile and other technical features. During the measurement process, the sensor can feed back the displacement data to the data processing module, and the data processing module determines whether the probe is in the climbing stage. If it is in the climbing stage, it can be achieved by controlling the auxiliary lifting structure to lift the probe so that the probe skips the climbing stage, thereby preventing the probe from getting stuck during the measurement process. After the sample loading module of the present invention rotates one circle, that is, after completing the measurement of the side tooth profile, it switches the turntable direction and re-measures. It can achieve the use of forward and reverse measurement to obtain the full profile of the gear, and realize the use of the data processing module to separate the errors in the measurement results, thereby achieving the profile measurement of small-module gears with tooth height and tooth clearance at the level of hundreds of microns, thereby improving the accuracy of the measurement results.

[0024] In addition, in some embodiments, the present invention also has the following beneficial effects:

[0025] By using the probe to scan along the gear and obtain the full profile of the gear, it is possible to use the data processing module to separate the errors in the measurement results, and then realize the profile measurement of small-module gears with tooth height and tooth clearance at the level of hundreds of microns, thereby improving the accuracy of the measurement results.

[0026] By setting up two sensors, the two-point method and curve fitting can be used to eliminate system installation errors and measurement errors, thereby improving the measurement accuracy of small module gear profiles.

[0027] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1(a) is a force analysis diagram of the climbing stage in gear measurement;

[0029] Figure 1(b) is a force analysis diagram of the stable stage in the gear measurement;

[0030] Figure 1(c) is a force analysis diagram of the descending stage in the gear measurement;

[0031] Figure 2 is a schematic structural diagram of a measurement system in an embodiment of the present invention;

[0032] Figure 3 is an overall schematic diagram of a measurement system in an embodiment of the present invention;

[0033] Figure 4 is a flow chart of the measurement work in an embodiment of the present invention;

[0034] Figure 51 is a schematic diagram showing the combined effects of eccentricity error and alignment error in an embodiment of the present invention;

[0035] Figure 6 This is the principle diagram of error separation of the three-point method;

[0036] Figure 7(a) is a schematic diagram of the special state of the three-point method;

[0037] Figure 7(b) is a schematic diagram of the principle of the two-point method;

[0038] FIG8( a ) is the profile measurement result of the flexspline measured in Example 1;

[0039] FIG8( b ) is a comparison diagram of the measurement results of Example 1 and the measurement results of a commercial profilometer;

[0040] Figure 8(c) is an enlarged view of the interval of the boxed portion in Figure 8(b);

[0041] Figure 8(d) is the comparison deviation result of the tooth surface profile along the falling edge in Example 1;

[0042] FIG8( e ) is a comparison deviation result of the tooth surface profile along the rising edge in Example 1. ...

[0043] The accompanying drawings are numerals as follows:

[0044] 1 is a computer, 2.1 is a first displacement sensor, 2.2 is a second displacement sensor, 3 is a driving actuator, 4 is an air bearing, 5 is a probe, 6 is a precision turntable, 7 is a gear to be measured, 8 is a single chip microcomputer, and 9 is an electric push rod. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and in combination with preferred embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0046] It should be noted that the directional terms such as left, right, up, down, top, and bottom in this embodiment are merely relative concepts, or are based on the normal use status of the product, and should not be considered as restrictive.

[0047] Regarding the measurement difficulties of harmonic flexspline, the contact probe method is still the mainstream method due to its advantages of reliability and stability. Generally, the probe is combined with a rotary table to obtain the position change information of the contact point, and then extract the tooth profile. However, when using the probe to measure the flexspline tooth profile, the probe performs contact scanning along the flexspline surface. Due to the frequent switching of the tooth top / tooth bottom, the probe is prone to deflection due to force imbalance during the rising stage, and even gets stuck and interrupts the measurement. Figure 1(a), Figure 1(b), and Figure 1(c) are the climbing, stabilization, and descending stages of the probe measurement process, respectively. Under normal circumstances, as shown in Figure 1(c), when the probe descends along the side tooth surface, the resultant force on the probe tip can reach a balanced state, so the entire probe will only move back and forth following the tooth surface, so that the movement of the probe can infer the position change of the tooth surface, that is, the profile. As shown in Figure 1(a), the probe often gets stuck when climbing along the side tooth surface. Analysis of the force acting on the probe reveals that when the probe climbs along the side tooth surface, the support force N exerted by the flexspline surface on the probe, the friction force fs, and the preload force P on the probe are directed to the left. The air bearing provides a uniform and symmetrical force on the probe root, so the probe is subjected to a force to the left as a whole. Then, due to the cantilever effect, the probe tip is subjected to a torque. When the torque provided by the front and rear of the air bearing cannot balance the aerodynamic torque applied to the probe tip, the probe will deflect and even contact the inner wall of the bearing, causing the probe to get stuck. In short, the falling edge can generally be completed smoothly, while the rising edge will tilt to a certain extent or even get stuck due to the unbalanced torque, resulting in increased measurement error or even inability to measure.

[0048] The following embodiment of the present invention proposes a gear profile measurement system and method, which can realize the profile measurement of small-module gears with tooth height and tooth clearance at the level of hundreds of microns, and eliminate system installation errors and measurement errors through the two-point method and curve fitting, thereby realizing high-precision measurement of the small-module gear profile.

[0049] A gear profile measurement system proposed in an embodiment of the present invention includes a measuring module, a sample loading module, and a data processing module; the measuring module includes a probe, an auxiliary lifting structure, and a sensor, and the probe can scan and measure the measured gear 7; the auxiliary lifting structure can lift the probe; the sensor can collect displacement data of the probe and output the displacement data to the data processing module; the sample loading module can drive the measured gear 7 to rotate; the data processing module can determine whether the probe is in a climbing stage based on the received displacement data, control the auxiliary lifting structure to lift the probe during the climbing stage, lower the probe on the top of the measured gear 7, and control the sample loading module to switch direction after rotating one circle.

[0050] In a preferred embodiment, the data processing module performs installation error separation and rotation error separation based on the data collected by the first displacement sensor 2.1 and the second displacement sensor 2.2 to obtain a restored profile of the measured gear 7 after error separation.

[0051] In a preferred embodiment, the auxiliary lifting structure includes a single chip microcomputer 8 and an electric push rod 9. The single chip microcomputer 8 can drive the electric push rod 9 to lift the probe according to the signal sent by the data processing module.

[0052] An embodiment of the present invention further provides a gear profile measurement method, which uses the gear profile measurement system described above to measure the profile of a gear to be measured, comprising the following steps: S1: driving a sample loading module to rotate, thereby driving a gear to be measured 7 mounted on the sample loading module to rotate;

[0053] S2: Scan and measure the gear 7 to be measured by the probe; S3: Collect displacement data of the probe through the sensor; S4: Receive the displacement data through the data processing module and determine whether the probe is in the climbing stage. If so, the data processing module sends a signal to control the auxiliary lifting structure to lift the probe and lower the probe on the top of the gear; S5: Control the sample loading module to switch the direction after rotating one circle through the data processing module; S6: Output the gear restoration profile through the data processing module.

[0054] In a specific embodiment, during two-point measurement, the optical probe can be replaced with a probe 5, similarly obtaining two sets of contour data for calculation. However, the use of two probes can accelerate damage to the workpiece surface and require a reduction in the turntable's rotation speed, thereby reducing measurement speed. Similarly, the probe can be replaced with an optical probe, but optical probes can suffer from high measurement noise and inaccurate flank flank measurement. Therefore, the optimal solution is to use the probe for contour measurement as the primary probe and the optical probe for rotation error separation as the auxiliary probe.

[0055] In addition, by reducing the pressure between the probe and the workpiece, the entire circumferential profile of the gear can be directly measured in one circle. However, this requires that the contact force between the probe and the workpiece be always controlled within a very small range, which is a high requirement. The embodiments of the present invention can reduce the requirements for equipment performance and achieve high-precision measurement at a low cost.

[0056] The following is specific embodiment 1:

[0057] In this embodiment, the probe is a probe 5, the sensors are a first displacement sensor 2.1 and a second displacement sensor 2.2, and the sample loading module is a precision turntable 6. The surface profile of the gear 7 is measured by contact scanning with the probe 5. The hardware system can be divided into a measurement function and a sample loading component. Measurements are performed by contact scanning with the probe 5, and the displacement of the probe 5 is acquired via the first displacement sensor 2.1. Therefore, the measurement component can be divided into three parts: the first displacement sensor 2.1, the air bearing 4, the probe 5, and the probe shaft. Sample loading involves mounting the gear 7 on the precision turntable 6. This allows the probe to scan along the gear 7 by rotating the gear, thereby acquiring the full profile of the gear 7. Furthermore, because the gear 7 has a side tooth flank with an excessively steep slope, the probe 5 can easily become stuck during the climbing phase. To address this issue, an auxiliary lifting mechanism is proposed to allow the probe to skip the climbing phase. After the measurement is completed, the probe rotates in the opposite direction to scan the other side tooth flank, acquiring the profile. Finally, the two measurement results are combined to achieve full profile measurement. Therefore, a drive actuator 3 is designed in the system. The specific device can use an electric push rod 9, which is driven by the single-chip computer 8 and can lift or lower the probe 5. It is part of the auxiliary lifting structure; the displacement of the probe 5 is monitored by the first displacement sensor 2.1. If the probe is found to be in the climbing stage, the computer 1 with a data processing module sends a signal to the single-chip computer 8 to control the movement of the drive actuator 3, thereby lifting the probe 5. The air bearing 4 can keep the probe 5 rod in a suspended state, minimize the friction during the measurement process, and keep the probe 5 in a free motion state. The overall design diagram of the system is shown in the figure below. Figure 2 As shown in the measurement process flow chart Figure 4 shown.

[0058] The specific workflow is as follows: 1) Start the first displacement sensor 2.1 and the second displacement sensor 2.2 to start data collection. The measurement of the second displacement sensor 2.2 is non-contact measurement. It only needs to measure the data points of the tooth top and tooth bottom of the gear to separate the rotation error, provide a reference position for contour splicing, and drive the precision turntable 6 to rotate, driving the measured gear 7 to rotate; 2) During the scanning measurement process of the probe 5, the current displacement value is monitored in real time, and the probe 5 climbing judgment is performed. If the displacement value of the probe 5 is monitored to increase continuously, it is determined that the probe 5 is currently on the rising edge of the gear, and the control drive actuator 3 is controlled to lift the probe 5, skip the measurement of the rising edge, and lower the probe near the tooth top; 3) The tooth profile part of the falling edge is measured normally, and the above steps are repeated until the full-circle contour measurement of the gear is completed. Then, the rotation direction of the precision turntable 6 is manually switched to supplement the measurement of the tooth profile on the other side; 4) After completing all contour measurements, the data of the first displacement sensor 2.1 and the second displacement sensor 2.2 are combined to perform installation error separation and rotation error separation to obtain the gear restoration contour after error separation.

[0059] By analyzing the built contour measurement system and establishing the corresponding mathematical geometric model, we can get the following Figure 5 The mathematical model of the gear center O' and the turntable center O is the eccentricity error e, the angle between the gear center O' and the turntable center O is the eccentricity angle α0, the distance between the sensor axis and the turntable center axis is the alignment error s, the sensor zero point is G, the distance between the zero point and the turntable center is p, and the measurement value of the first displacement sensor 2.1 is m i .

[0060] In this model, there are two main errors: the installation eccentricity error e caused by the misalignment between the gear center and the turntable center during gear installation, and the probe alignment error s caused by the misalignment between the probe and the turntable center. The probe measurement value can be divided into the sum of three parts, namely the distance from the probe zero point to the turntable center, the horizontal component of the installation eccentricity error, and the horizontal component of the distance between the needle tip and the gear center. The probe measurement point P i The angle between the initial measurement position P0 and the gear center is θ i , the angle between the horizontal axis and the initial measurement point P0 is β i , the corresponding rotation angle of the gear is θ i .

[0061] When the turntable rotates through an angle of β i When the gear's corresponding rotation angle is θ i , the deviation between these two angles is defined as ε i , so that the relationship between the probe measurement value and the turntable angle and the corresponding angle and radius of the measured gear can be established. The specific formulas are shown in equations (1) to (5).

[0062]

[0063] β i =θ i -ε i (2)

[0064]

[0065]

[0066]

[0067] By deducing the above formula, the eccentricity error and alignment error in the measurement results can be separated.

[0068] In addition to eccentricity error and alignment error, the measurement results also include rotation error, which can be separated using the three-point method. The three-point method requires the use of three displacement sensors for synchronous measurement, and the rotation error separation is achieved through three sets of synchronous measurement data. Figure 6 The figure shows the principle diagram of the three-point method. The three sensors are separated by a certain angle. Sensor A and sensor B are separated by angle a, and sensor B and sensor C are separated by angle β. When the turntable rotates, the three sensors synchronously measure the part contour curve.

[0069] When the turntable drives the parts to rotate, the data of sensors A, B, and C can be expressed by the following formulas (6), (7), and (8): A (γ), S B (γ), S C (γ) represents the measured values ​​of sensors A, B, and C, r(γ), r(γ+α), and r(γ+β) are the radii of the gear under test at the corresponding angles, and δ x (γ), δ y (γ) is the component of the rotation error of the rotary table in the x and y axis directions when the rotary table is at angle γ.

[0070] S A (γ)=r(γ)+δ x (γ) (6)

[0071] S B (γ)=r(γ+α)+δ x (γ)·cosα+δ y (γ)·sinα (7)

[0072] S C (γ)=r(γ+β)+δ x (γ)·cosβ+δ y (γ)·sinβ (8)

[0073] The two-point method is a simplified form of the three-point method under special conditions. In this special condition, the angle between sensor A and sensor B is π / 2, and the angle between sensor B and sensor C approaches π / 2. That is, the angle between sensor A and sensor C approaches π but is not equal to π. Because the rotational errors in the x- and y-directions must be separated, the two sensors cannot be placed directly opposite each other and must be placed less than 180 degrees apart. Simulation optimization determined that the optimal placement position is between 179 and 180 degrees, resulting in an axis angle greater than 179° and less than 180°, as shown in Figure 7(a) below.

[0074] In this state, the measurement data from sensor B is essentially useless for error separation, so sensor B can be discarded, and the three-point method is converted to a two-point method, as shown in Figure 7(b). The two-point method sacrifices some accuracy compared to the three-point method but is easier to implement because accurate positioning of two sensors is much simpler than that of three sensors.

[0075] The data processing steps of the two-point method are as follows: Combine the measurement result S of the first displacement sensor 2.1 A (γ) and the measurement result S of the second displacement sensor 2.2 B (γ) Construct the weighted summation formula S, where is the angle between the first displacement sensor 2.1 and the second displacement sensor 2.2, c0 and c1 are weight coefficients, and we can get:

[0076]

[0077] Performing Fourier transform on formula (9) yields formula (10):

[0078] S(ω)=c0·R(ω)+c1·R(ω)e iωβ (10)

[0079] After extracting the common factors from the formula, R(ω) can be expressed as follows:

[0080] R(ω)=S(ω) / H(ω) (11)

[0081] Where H(ω) is the weight function, which is as follows:

[0082] H(ω)=c0+c1·e iωβ (12)

[0083] Finally, performing an inverse Fourier transform on R(ω) yields the profile of the measured part. When using the two-point method, a second displacement sensor 2.2 is required to obtain gear tooth vertex data for the two-point method calculation. Given the characteristics of small-module gears, the spot size of the second optical displacement sensor 2.2 should be sufficiently small to minimize measurement distortion.

[0084] This embodiment proposes a design scheme that combines probe contact measurement and laser sensor measurement, realizes the contour measurement function of small module gears, separates the measurement errors in the measurement results, and improves the accuracy of the measurement results.

[0085] To address the problems of stuckness and needle skipping during the measurement process, an auxiliary lifting structure was designed. By combining the two profiles after forward and reverse measurement, the complete profile of the flexspline was successfully measured. After error separation and splicing of the measurement results, the original tooth profile of the harmonic reducer flexspline was obtained. This was then compared and verified using a commercial profilometer, confirming the usability of the profile measurement system. The specific measurement results are shown in Figure 8(a). The target flexspline is a GJCS-25-80, and its full-circle tooth profile was measured. The numbers on the circumference represent angles, and the numbers within the circle represent the flexspline radius (μm). A commercial profiler SEF680 was used to measure a portion of the flexspline's profile. The results of the comparison interval are shown in Figures 8(b) and 8(c), where the horizontal axis is the spatial coordinate, representing the lateral measurement position of the profiler probe. Figure 8(c) is a partial enlargement of the boxed portion in Figure 8(b). The measurement error of the commercial profiler SEF680 is minimal in the enlarged portion, which serves as the comparison interval. Figure 8(d) shows the comparison deviation result of the tooth surface profile along the falling edge, i.e., the comparison deviation of the result on the right gear tooth. The comparison deviation is within 20 μm. Figure 8(e) shows the comparison deviation result of the tooth surface profile along the rising edge, i.e., the comparison deviation of the result on the left gear tooth. Some large comparison deviations are due to measurement distortion caused by interference between the commercial profiler probe and the flexspline. This embodiment preliminarily solves the need for flexspline profile measurement in harmonic reducers and has the prospect of being applied to the precision measurement of other types of rotating parts.

[0086] Example 2:

[0087] In this embodiment, a Keyence laser displacement sensor LK-G30 is used as the first displacement sensor 2.1, a STIL CCS PRIMA spectral confocal displacement sensor is used as the second displacement sensor 2.2, a precision turntable TD-170-50 series is used as the object turntable, the target flexspline is a GJCS-25-80 flexspline, and the probe 5 is manufactured in-house with a probe radius machined to 2 μm. When the system is set up, the target flexspline is mounted on the precision turntable 6, and the first displacement sensor 2.1 and the second displacement sensor 2.2 are mounted relative to each other with an axis angle of 179° to 180°. Then, measurement is started, and the turntable speed is set to 0.05° / s. During the measurement process, a Keyence laser displacement sensor monitors the probe position in real time and communicates with computer 1 in real time, feeding back position data. The data processing module in computer 1 then runs a pre-programmed program to detect whether the probe is in the climbing phase. If so, it sends a signal to the Arduino Uno microcontroller, which in turn controls actuator 3 to pull back probe 5, skipping the climbing phase. One second later, probe 5 is lowered, re-engaging the gear at the tooth top position and measuring the subsequent falling edge profile. After the turntable rotates 360°, the tooth profile measurement for one side is complete. The turntable then switches direction and repeats the measurement, achieving full circumference measurement of the gear. The measured data is then separated using fitting formulas to separate the eccentricity and alignment error parameters, as well as the workpiece installation error. This data is then combined with the measurement results from the spectral displacement sensor to separate the rotational error, ultimately yielding the complete gear profile.

[0088] The embodiments of the present invention have the following features:

[0089] 1) The embodiment of the present invention solves the problem of probe easily getting stuck by using a bidirectional rotation measurement method, and realizes full profile measurement of small module gears with large aspect ratio structures;

[0090] 2) In the embodiment of the present invention, the probe position is collected by a laser sensor and fed back to the host computer. The data processing module in the host computer determines whether it is in the climbing stage, and then sends a command to the single-chip microcomputer to drive the electric push rod to work. The embodiment of the present invention can monitor the measurement process in real time and feedback to drive the electric push rod to realize the auxiliary lifting function.

[0091] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0092] 1. It can realize full-circle profile measurement of small module gears.

[0093] 2. The full-circle profile measurement is achieved through the bidirectional rotation measurement method, skipping the scanning in the climbing phase to avoid the occurrence of jamming problems.

[0094] 3. The installation error and rotation error are separated by the error separation method, which does not require the measurement system and the workpiece to be installed very precisely.

[0095] 4. The equipment used in the embodiment of the present invention is simple, the system is not complicated, and the cost can be effectively reduced.

[0096] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. Those skilled in the art will recognize that several equivalent substitutions or obvious variations can be made without departing from the scope of the present invention, and that any equivalent performance or application should be considered to fall within the scope of protection of the present invention.

Claims

1. A gear profile measurement system, characterized in that: It includes measurement module, sample loading module and data processing module; The measuring module includes a probe, an auxiliary lifting structure, and a sensor. The probe can scan and measure the gear being measured; the auxiliary lifting structure can lift the probe; the sensor can collect displacement data of the probe and output the displacement data to the data processing module; The sample loading module can drive the gear to be tested to rotate; The data processing module can determine whether the probe is in the climbing stage based on the received displacement data, control the auxiliary lifting structure to lift the probe during the climbing stage, lower the probe on the top of the gear, and control the sample loading module to switch direction after rotating one circle; The sensor includes a first displacement sensor and a second displacement sensor, wherein the first displacement sensor and the second displacement sensor are installed relative to each other, and an angle between their axes is greater than 179° and less than 180°; The data processing module performs installation error separation and rotation error separation based on the data collected by the first displacement sensor and the second displacement sensor to obtain a restored profile of the gear after error separation.

2. The gear profile measurement system according to claim 1, characterized in that: The measuring module further comprises an auxiliary measuring head for separating rotation errors.

3. The gear profile measurement system according to claim 2, characterized in that: The measuring head is a probe, the auxiliary measuring head is an optical measuring head, and the sample loading module is a precision turntable.

4. The gear profile measurement system according to claim 3, characterized in that: The data processing module separates the installation error by the following formula: Among them, θ i is the angle between the probe and the initial measuring position centered on the gear being measured, β i is the angle between the horizontal axis and the initial measurement position, e is the eccentricity error, α0 is the eccentricity angle, s is the alignment error, r i is the radius of the gear being measured.

5. The gear profile measurement system according to claim 4, characterized in that: The data processing module performs inverse Fourier transform on R(ω) to obtain the profile information of the gear being measured. The expression of R(ω) is: R(ω)=S(ω) / H(ω) Wherein, S(ω) is the result of Fourier transform of S, S is a weighted summation formula constructed by combining the measurement results of the first displacement sensor and the measurement results of the second displacement sensor, and H(ω) is a weight function.

6. The gear profile measurement system according to claim 5, characterized in that: The data processing module separates the rotation error by the following formula: Among them, S A (γ) is the measurement result of the first displacement sensor, S B (γ) is the measurement result of the second displacement sensor, c0 and c1 are weight coefficients, γ is the angle between the probe and the initial measurement position with the gear being measured as the center, is the angle between the first displacement sensor and the second displacement sensor, r(γ) is the radius of the gear under test at angle γ, The angle of the gear being measured The radius below.

7. The gear profile measurement system according to claim 1, wherein: The auxiliary lifting structure includes a single chip microcomputer and an electric push rod. The single chip microcomputer can drive the electric push rod to lift the measuring head according to the signal sent by the data processing module.

8. A gear profile measurement method, characterized in that: Using the gear profile measuring system according to any one of claims 1 to 7 to measure the profile of the gear being measured, The following steps are involved: S1: driving the sample loading module to rotate, thereby driving the gear to be measured mounted on the sample loading module to rotate; S2: Measure the gear being measured by scanning with a probe; S3: Collect displacement data of the probe through the sensor; S4: receiving the displacement data through the data processing module and determining whether the probe is in the climbing stage; if so, the data processing module sends a signal to control the auxiliary lifting structure to lift the probe and lower the probe on the top of the gear; S5: Controlling the sample loading module to rotate one circle and then switch the direction through the data processing module; S6: Outputting the restored gear profile through the data processing module.

Images