A standard inertia device for calibrating a torque sensor and a method of using the same

Abstract

The present invention discloses a standard inertia device for torque sensor calibration and a method for using the same. The device comprises an air bearing, wherein the diameters of the upper and lower ends of the air bearing are both smaller than the diameter of the middle part, the upper end of the main shaft of the air bearing is connected to a mounting tray, the mounting tray is connected to a standard inertia disk, the lower end of the main shaft of the air bearing is connected to a coupler, a circular grating is mounted on the lower surface of the coupler with screws, a reading head mounting bracket is symmetrically mounted on the lower part of the air bearing and on both sides of the coupler housing, the lower end of the reading head mounting bracket is fixedly connected to the reading head with screws, the detection surface of the reading head is opposite to the engraved surface of the circular grating and is parallel to the section of the circular grating; the geometric center lines of the mounting tray, the standard inertia disk, the air bearing, the coupler, the reading head mounting bracket, the reading head and the circular grating are kept coaxial after installation. The present invention solves the problem of large measurement error of the current standard inertia device and can realize the function of torsion angle measurement of the calibrated torque sensor.

Description

Technical Field

[0001] The invention relates to a standard inertia device for calibrating a torque sensor and a use method thereof, and belongs to the field of torque parameter calibration, in particular to the technical field of dynamic parameter calibration of a torque sensor. Technical Background

[0002] Torque sensors are widely used in aviation, aerospace, ships, weapons, robots and many other fields. In mechanical transmission systems, torque is not only an important parameter for measuring the output power of the power system, but also an important indicator for monitoring the working status and health of the power system. In recent years, with the development of the industry, the technical indicators of equipment in the industry have become increasingly higher. For occasions where dynamic torque parameters are measured, torque sensors that have only been calibrated with static torque parameters no longer meet the use requirements. Therefore, the demand for dynamic torque parameter calibration of torque sensors is becoming increasingly obvious.

[0003] At present, the method of dynamic torque calibration is still in the exploratory stage. There are two main calibration methods: the first is the negative step method, that is, first apply a torque load to the coaxially connected standard torque sensor and the calibrated torque sensor, and then use a special device to remove the torque load in the shortest possible time, thereby forming a negative step excitation, recording the output waveforms of the standard torque sensor and the calibrated torque sensor, and performing comparative calibration; the second is the sinusoidal excitation method, that is, using a sinusoidal torque generator to excite the torque sensor equipped with a standard inertia load, measuring the angular acceleration of the standard inertia load, calculating the product of angular acceleration and inertia as the standard torque, comparing the standard torque waveform with the output waveform of the calibrated torque sensor, and completing the calibration of the calibrated torque sensor. In addition, the relevant metrology agency uses the comparison method to calibrate the dynamic torque parameters, that is, under the application of dynamic sweep torque, compare the output values ​​of the standard torque sensor and the calibrated torque sensor. The standard torque sensor used is a dynamic torque sensor purchased from abroad, and its frequency and torque amplitude are limited.

[0004] However, the above method has a limited calibration amplitude range for torque sensors and cannot calibrate torque sensors with a larger amplitude range. Based on this, Guizhou Aerospace Metrology and Testing Technology Research Institute has developed a device and calibration method for calibrating torque sensors using the braking natural frequency method and applied for a Chinese patent, with the announcement number CN 110987293 A. The structure of the device is as follows: Figure 1As shown, it includes a standard inertia device A and a calibrated torque sensor B, a brake C, a clutch D, and a servo motor E. The standard inertia device A is rigidly connected to the calibrated torque sensor B and keeps rotating at a high speed. A braking torque is applied to the calibrated torque sensor B. The standard inertia device A generates torsional vibration after the speed drops to zero. The square of the torsional vibration frequency is inversely proportional to the inertia value of the standard inertia device A and is directly proportional to the stiffness of the calibrated torque sensor B. The amplitude of the torsional vibration depends on the size of the braking torque. The angular acceleration change of the standard inertia disk is measured by a circular grating. The product of the angular acceleration and the standard inertia value is the standard dynamic torque excitation amplitude. The waveform of the standard dynamic torque is measured and compared with the dynamic torque sensor to be calibrated to complete the calibration.

[0005] However, the standard inertia device A of the device has the following problems:

[0006] 1. The connection method between the air bearing and the standard inertia disk means that the inertia of the air bearing does not participate in the inertia calculation of the calibration device, resulting in errors in measurement accuracy;

[0007] 2. The glass ring grating is installed on the standard inertia disk. Each time the standard inertia disk is replaced, the glass ring grating must be removed and reinstalled, resulting in a decrease in the measurement accuracy of the glass ring grating. Summary of the invention

[0008] The purpose of the present invention is to provide a standard inertia device for torque sensor calibration, as a part of a dynamic torque sensor calibration device using a braking natural frequency method, for generating dynamic torque excitation, overcoming the above problems and improving the measurement accuracy of the calibration device.

[0009] The technical solution adopted by the present invention is a standard inertia device for calibrating a torque sensor, comprising an air bearing, a standard inertia disk, a coupler, a reading head and a circular grating, wherein the diameters of the upper end and the lower end of the air bearing are both smaller than the diameter of the middle part, the upper end shoulder of the main shaft of the air bearing is connected to the mounting tray, the standard inertia disk is connected to the mounting tray, the lower end of the main shaft of the air bearing is connected to the coupler, the circular grating is mounted on the lower surface of the coupler with screws, the lower part of the air bearing and the two sides of the coupler housing are symmetrically mounted with a reading head mounting bracket, the lower end of the reading head mounting bracket is fixedly connected to the reading head with screws, and the detection surface of the reading head is opposite to the engraved surface of the circular grating and parallel to the tangent surface of the circular grating;

[0010] The geometric center lines of the mounting tray, standard inertia disk, air bearing, coupler, reading head mounting bracket, reading head and circular grating are kept coaxial after being installed.

[0011] Furthermore, an opening is provided at the upper end of the installation tray, and a T-shaped support cover is installed at the opening, and a geometric center line of the T-shaped support cover is coaxial with the installation tray.

[0012] Furthermore, the T-shaped support cover and the mounting tray are clearance-fitted, and the diameter difference of the fitting parts is less than 20 μm.

[0013] Furthermore, the installation tray and the standard inertia disk are fastened together by a 1# expansion sleeve, and the geometric center line of the 1# expansion sleeve is coaxial with the installation tray.

[0014] Furthermore, the air bearing and the mounting tray are fastened together by a 2# expansion sleeve, and the geometric center line of the 2# expansion sleeve is coaxial with the air bearing.

[0015] Furthermore, the air bearing and the coupler are fastened together by a 3# expansion sleeve, and the geometric center line of the 3# expansion sleeve is coaxial with the air bearing.

[0016] Furthermore, the diameter of the main shaft of the air bearing is not less than 100 mm, and the coupler is adapted to the air bearing.

[0017] Furthermore, the standard inertia disk is annular, and its height is not less than the height of the 1# expansion sleeve.

[0018] A method for using a standard inertia device for calibrating a torque sensor comprises the following steps:

[0019] (1) Before using the device, measure the inertia of the rotating parts except the standard inertia disk to obtain the total inertia J 1 ;

[0020] (2) Calculate the inertia J of the standard inertia disk 2 :Assume the stiffness of the calibrated torque sensor is k 0 , inertia is J 0 , the calibration frequency is f 0 ,but:

[0021]

[0022] According to the tightening pressure P of the 1# tightening sleeve, the difference ΔR between the inner and outer diameters of the standard inertia disc satisfies:

[0023] ΔR>PR / σ

[0024] Where R is the inner diameter of the inertia disc; σ is the pressure on the surface of the standard inertia disc in contact with the expansion sleeve when the expansion sleeve reaches the rated expansion force.

[0025] (3) After installation, measure and adjust the spindle verticality and unbalanced shake error until they meet the design technical indicators, and then calibrate the torque sensor.

[0026] Furthermore, the measurement and adjustment method for the spindle verticality and unbalanced shaking error is as follows:

[0027] C1. Measurement method: a. Measurement of the verticality of the spindle: Place the electronic level on the edge of the standard inertia disk, slowly rotate the standard inertia disk clockwise and counterclockwise for one circle each, record the output of the level at the corner position every 10°, and then take the average value of multiple groups of results based on the level indications at two corners with an interval of 180°. The calculated result is no more than 4 arc seconds; b. Measurement of unbalanced shaking error: At a given speed, synchronously collect the output signal of the capacitance micrometer and the output signal of the angle measuring instrument, analyze the spindle shaking of the calibration device at different speeds, and the maximum shaking amplitude is no more than 1mm;

[0028] C2. Adjustment method: If the spindle plumbness result does not meet the above indicators, reinstall the standard inertia disk to ensure that the geometric center line of the standard inertia disk is not tilted until the design technical indicators are met; if the unbalanced shaking result does not meet the above indicators, re-tighten the expansion sleeve installed with the standard inertia disk, adjust the fastening screws on the expansion sleeve to adjust the geometric center of the standard inertia disk until the design technical indicators are met.

[0029] The beneficial effects of the present invention are:

[0030] 1. By combining the air bearing with the standard inertia disk and using the main shaft of the air bearing as part of the standard inertia device, the support problem of the standard inertia device is solved, the friction torque of the supporting system is reduced, and the torsion angle measurement function of the calibrated torque sensor can be realized. It is suitable for the standard inertia device for dynamic torque sensor calibration;

[0031] 2. By changing the connection method of the circular grating, the reading head and the standard inertia disk, the standard inertia disk and the air bearing are connected by installing a tray, and the circular grating and the reading head are independently connected to the air bearing. Under the condition of ensuring effective measurement, the problem of reduced measurement accuracy caused by replacing the standard inertia disk and disassembling the circular grating is solved;

[0032] 3. Use expansion sleeves to replace screws to connect the air bearing and mounting tray, mounting tray and standard inertia disk, air bearing and coupler. The coaxiality between the device components is improved through friction connection. The expansion sleeve has better rigidity than screws, which solves the problem of low measurement accuracy caused by torsion error.

[0033] 4. The installation tray is opened and a T-shaped support cover is installed to prevent deformation of the standard inertia disk when tightening. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a simplified structural diagram of the dynamic torque sensor calibration device using the braking natural frequency method;

[0035] Figure 2 It is a cross-sectional view of the structure of the present invention.

[0036] Markings in the figure: 1. T-type support cover, 2. Mounting tray, 3. 1# expansion sleeve, 4. Standard inertia disk, 5. 2# expansion sleeve, 6. Air bearing, 7. 3# expansion sleeve, 8. Coupler, 9. Reading head mounting bracket, 10. Reading head, 11. Circular grating. DETAILED DESCRIPTION

[0037] The present invention will be further explained below in conjunction with the accompanying drawings to facilitate better understanding by those skilled in the art.

[0038] See also Figure 1 A standard inertia device for torque sensor calibration and a method for using the same. The standard inertia device is used as a part of a dynamic torque sensor calibration device using a braking natural frequency method to generate dynamic torque excitation.

[0039] A standard inertia device for calibrating a torque sensor comprises a T-shaped support cover 1, a mounting tray 2, a 1# expansion sleeve 3, a standard inertia disk 4, a 2# expansion sleeve 5, an air bearing 6, a 3# expansion sleeve 7, a coupler 8, a reading head mounting bracket 9, a reading head 10, and a circular grating 11.

[0040] The diameters of the upper and lower ends of the air bearing 6 are both smaller than the diameter of the middle part, and the diameter of the main axis of the air bearing 6 is not less than 100 mm. The shape and size meet the design requirements, which is conducive to improving the measurement accuracy of the device.

[0041] The mounting tray 2 is fixedly connected to the upper end shoulder of the main shaft of the air bearing 6, and the standard inertia disk 4 is connected to the mounting tray 2; specifically, the mounting tray 2 and the standard inertia disk 4 are fastened with a 1# expansion sleeve 3, the standard inertia disk 4 is annular, and its height is not less than the height of the 1# expansion sleeve 3, and the geometric center line of the 1# expansion sleeve 3 is coaxial with the mounting tray 2, and the air bearing 6 and the mounting tray 2 are fastened with a 2# expansion sleeve 5, and the geometric center line of the 2# expansion sleeve 5 is coaxial with the air bearing 6. The use of an expansion sleeve connection is conducive to enhancing the coaxiality of the mounting tray 2, the standard inertia disk 4 and the air bearing 6, and the expansion sleeve has a higher rigidity than the screw, which effectively reduces the torsion error of the device and improves the measurement accuracy.

[0042] Among them, an opening is set at the upper end of the mounting tray 2, and a T-shaped support cover 1 is installed at the opening. The geometric center line of the T-shaped support cover 1 is coaxial with the mounting tray 2. The T-shaped support cover 1 and the mounting tray 2 are clearance-fitted, and the diameter difference of the fitting part is less than 20μm, which provides support for the mounting tray 2 and prevents the mounting tray 2 from being deformed when the standard inertia disk 4 is tightened.

[0043] The lower end of the main shaft of the air bearing 6 is connected to a coupler 8, and the coupler 8 is adapted to the air bearing 6 and is used to install the calibrated torque sensor. Specifically, the air bearing 6 and the coupler 8 are fastened with a 3# expansion sleeve 7, and the geometric center line of the 3# expansion sleeve 7 is coaxial with the air bearing 6. The rigidity between the air bearing 6 and the coupler 8 is enhanced by friction connection, and the torsion error is reduced. The lower surface of the coupler 8 is screwed to install a circular grating 11, and the lower part of the air bearing 6 and the two sides of the coupler 8 housing are symmetrically installed with a reading head mounting bracket 9. The lower end of the reading head mounting bracket 9 is fixedly connected to a reading head 10 by screws. The detection surface of the reading head 10 is opposite to the engraved surface of the circular grating 11 and is parallel to the tangent surface of the circular grating 11. The reading head 10 and the circular grating 11 are used to measure the torsion angle of the calibrated torque sensor.

[0044] The geometric center lines of the T-shaped support cover 1, mounting tray 2, 1# expansion sleeve 3, standard inertia disk 4, 2# expansion sleeve 5, air bearing 6, 3# expansion sleeve 7, coupler 8, reading head mounting bracket 9, reading head 10, and circular grating 11 remain coaxial after installation, and the sum of their inertias is the inertia value of the standard inertia device.

[0045] When calibrating a torque sensor, a standard inertia disk is configured according to the stiffness and calibration frequency of the torque sensor to be calibrated. A method for using a standard inertia device for calibrating a torque sensor includes the following steps:

[0046] (1) Before using the device, measure the inertia of the rotating parts except the standard inertia disk to obtain the total inertia J 1 ;

[0047] (2) Calculate the inertia J of the standard inertia disk 2 :Assume the stiffness of the calibrated torque sensor is k 0 , inertia is J 0 , the calibration frequency is f 0 ,but:

[0048]

[0049] According to the tightening pressure P of the 1# tightening sleeve, the difference ΔR between the inner and outer diameters of the standard inertia disc satisfies:

[0050] ΔR>PR / σ

[0051] Where R is the inner diameter of the inertia disc; σ is the pressure on the surface of the standard inertia disc in contact with the expansion sleeve when the expansion sleeve reaches the rated expansion force.

[0052] (3) After installation, measure and adjust the spindle verticality and unbalanced shake error until they meet the design technical indicators, and then calibrate the torque sensor.

[0053] Among them, the measurement and adjustment methods for the spindle verticality and unbalanced shaking errors are as follows:

[0054] C1. Measurement method: a. Measurement of the verticality of the spindle: Place the electronic level on the edge of the standard inertia disk, slowly rotate the standard inertia disk clockwise and counterclockwise for one circle each, record the output of the level at the corner position every 10°, and then take the average value of multiple groups of results based on the level indications at two corners with an interval of 180°. The calculated result is no more than 4 arc seconds; b. Measurement of unbalanced shaking error: At a given speed, synchronously collect the output signal of the capacitance micrometer and the output signal of the angle measuring instrument, analyze the spindle shaking of the calibration device at different speeds, and the maximum shaking amplitude is no more than 1mm;

[0055] C2. Adjustment method: If the spindle plumbness result does not meet the above indicators, reinstall the standard inertia disk to ensure that the geometric center line of the standard inertia disk is not tilted until the design technical indicators are met; if the unbalanced shaking result does not meet the above indicators, re-tighten the expansion sleeve installed with the standard inertia disk, adjust the fastening screws on the expansion sleeve to adjust the geometric center of the standard inertia disk until the design technical indicators are met.

[0056] The parts not described in detail in the present invention are all known technologies to those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A standard inertia device for calibrating a torque sensor, comprising an air bearing (6), a standard inertia disk (4), a coupler (8), a reading head (10) and a circular grating (11), Features: The diameters of the upper and lower ends of the air bearing (6) are both smaller than the diameter of the middle part; the upper end of the main shaft of the air bearing (6) is connected to the mounting tray (2); the mounting tray (2) is connected to the standard inertia disk (4); the lower end of the main shaft of the air bearing (6) is connected to the coupler (8); the lower surface of the coupler (8) is screwed to mount the circular grating (11); the lower part of the air bearing (6) and the two sides of the coupler (8) housing are symmetrically mounted with a reading head mounting bracket (9); the lower end of the reading head mounting bracket (9) is screwed to fix the reading head (10); the detection surface of the reading head (10) is opposite to the engraved surface of the circular grating (11) and is parallel to the tangent surface of the circular grating (11); The geometric center lines of the mounting tray (2), the standard inertia disk (4), the air bearing (6), the coupler (8), the reading head mounting bracket (9), the reading head (10), and the circular grating (11) remain coaxial after installation; The installation tray (2) and the standard inertia disk (4) are fastened together by a 1# expansion sleeve (3), and the geometric center line of the 1# expansion sleeve (3) is coaxial with the installation tray (2); The air bearing (6) and the mounting tray (2) are fastened together by a 2# expansion sleeve (5), and the geometric center line of the 2# expansion sleeve (5) is coaxial with the air bearing (6); by combining the air bearing with a standard inertia disk, the main axis of the air bearing is used as a part of the standard inertia device.

2. A standard inertia device for calibrating a torque sensor according to claim 1, Features: An opening is arranged at the upper end of the installation tray (2), and a T-shaped support cover (1) is installed at the opening. The geometric center line of the T-shaped support cover (1) is coaxial with the installation tray (2).

3. A standard inertia device for calibrating a torque sensor according to claim 2, Features: The T-shaped support cover (1) and the mounting tray (2) are clearance-matched, and the diameter difference of the matching parts is less than 20 μm.

4. A standard inertia device for calibrating a torque sensor according to claim 1, Features: The air bearing (6) and the coupler (8) are tightly connected by a 3# expansion sleeve (7), and the geometric center line of the 3# expansion sleeve (7) is coaxial with the air bearing (6).

5. The standard inertia device for calibrating a torque sensor according to claim 1, Features: The diameter of the main shaft of the air bearing (6) is not less than 100 mm, and the coupler (8) is compatible with the air bearing (6).

6. A standard inertia device for calibrating a torque sensor according to claim 1, Features: The standard inertia disk (4) is annular, and its height is not less than the height of the No. 1 expansion sleeve (3).

7. A method for using a standard inertia device for calibrating a torque sensor according to any one of claims 1 to 6, It is characterized in that The following steps are involved: (1) Before using the device, measure the inertia of the rotating parts except the standard inertia disk to obtain the total inertia J 1 ; (2) Calculate the inertia J of the standard inertia disk 2 :Assume the stiffness of the calibrated torque sensor is k 0 , inertia is J 0 , the calibration frequency is f 0 ,but: According to the tightening pressure P of the 1# tightening sleeve, the difference ΔR between the inner and outer diameters of the standard inertia disc satisfies: ΔR>PR / σ Where R is the inner diameter of the inertia disc; σ is the pressure on the surface of the standard inertia disc in contact with the expansion sleeve when the expansion sleeve reaches the rated expansion force; (3) After installation, measure and adjust the spindle verticality and unbalanced shake error until they meet the design technical indicators, and then calibrate the torque sensor.

8. The method for using the standard inertia device for calibrating a torque sensor according to claim 7, It is characterized in that The measurement and adjustment methods for the spindle verticality and unbalanced shaking errors are as follows: C1. Measurement method: a. Measurement of the verticality of the spindle: Place the electronic level on the edge of the standard inertia disk, slowly rotate the standard inertia disk clockwise and counterclockwise for one circle each, record the output of the level at the angle position every 10°, and then take the average value of multiple groups of results based on the level readings at two angles with an interval of 180°. The calculated result shall not be greater than 4 arc seconds; b. Measurement of unbalanced shaking error: At a given speed, synchronously collect the output signal of the capacitance micrometer and the output signal of the angle measuring instrument, analyze the spindle shaking of the calibration device at different speeds, and the maximum shaking amplitude is no more than 1mm; C2. Adjustment method: If the spindle plumbness result does not meet the above indicators, reinstall the standard inertia disk to ensure that the geometric center line of the standard inertia disk is not tilted until the design technical indicators are met; if the unbalanced shaking result does not meet the above indicators, re-tighten the expansion sleeve installed with the standard inertia disk, adjust the fastening screws on the expansion sleeve to adjust the geometric center of the standard inertia disk until the design technical indicators are met.

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