Measuring device and measuring method for internal friction damping of internal spherical hinge of high-precision instrument equipment

Abstract

The invention belongs to the technical field of high-precision instruments and equipment, and provides a device and a method for measuring internal friction damping of an internal spherical hinge of high-precision instruments and equipment. A test piece of the measuring device comprises a connecting rod and two spherical hinges connected to the two ends of the connecting rod, the connecting rod is fixedly connected with ball rods of the spherical hinges, the measuring device comprises at least two bases, the bases are used for fixing ball cups of the spherical hinges, and the bases are fixed to a clamp; the output end of the vibration exciter is connected with the base, and the input end of the vibration exciter is connected with a signal generator; a displacement sensor, a first force sensor and a second force sensor. According to the technical scheme, the connecting rod and the two spherical hinges connected to the two ends of the connecting rod serve as test pieces, loads and vibration are loaded to the test pieces after the base is directly connected with the ball cup, by means of the structures of the spherical hinges, the number of connecting parts is extremely small, other external friction factors are not introduced, and therefore the data precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of high-precision instrument and equipment technology, and in particular relates to a measuring device and method for measuring the internal friction damping of ball joints in high-precision instruments and equipment. Background Technology

[0002] For high-precision instruments and equipment, the friction of ball joints is a crucial factor affecting the damping of functional components. For example, the Stewart triplex platform uses ball joints to connect its upper and lower platforms and main vibration damping and isolation components; the friction of these joints is a significant factor influencing the platform's damping. Excessive ball joint friction can lead to self-locking between structural components and affect the platform's dynamic behavior. Traditional friction measurement devices, due to their numerous connecting parts, may introduce other external friction factors, resulting in decreased data accuracy. Summary of the Invention

[0003] This application provides a measuring device and method for measuring the internal friction damping of ball joints in high-precision instruments and equipment, which solves the technical problem that the data accuracy of traditional friction measuring devices is reduced due to the introduction of other external friction factors by too many connecting parts.

[0004] This application provides a measuring device for the internal friction damping of ball joints in high-precision instruments. The test component of the measuring device is a connecting rod and two ball joints connected to its two ends. The connecting rod is fixedly connected to the ball joint's ball shaft. The measuring device includes:

[0005] At least two bases are provided for fixing the ball joint's ball head, and the bases are fixed to the clamp.

[0006] A vibrator, the output of which is connected to one of the bases, and the input of which is connected to a signal generator;

[0007] A displacement sensor is used to measure the displacement of the ball head within the ball head seat;

[0008] A first force sensor is installed between the base and the ball joint;

[0009] A second force sensor is installed between the vibrator and the base.

[0010] In one embodiment, the clamping force applied by the clamp to the base is adjustable.

[0011] In one embodiment, the displacement sensor determines the displacement of the ball head by measuring the displacement of the threaded rod.

[0012] In one embodiment, the first force sensor is disposed between one of the bases and a ball joint fixed on the base.

[0013] In one embodiment, the base includes a central base and end bases;

[0014] The connecting rod and the ball joints connected to its two ends form a set of test pieces. The connecting rods of the two sets of test pieces are coaxially arranged, and two adjacent ball joints are fixed to a central base facing away from each other, while the other two ball joints are fixed to the end bases.

[0015] In one embodiment, a through hole is formed on the central base, and the through hole and the outer contour surface of the ball joint seat of the ball joint are in transition fit. The ball joint fixed to the central base is disposed in the through hole, and the first force sensor is disposed between the two ball joints located in the through hole.

[0016] In one embodiment, the side of the central base without the through hole is connected to the output end of the exciter.

[0017] In one embodiment, the measuring device further includes a data acquisition and analysis system that collects the output of the exciter, the output of the displacement sensor, and the outputs of the first force sensor and the second force sensor, and outputs a damping hysteresis curve of the ball joint.

[0018] Based on the same inventive concept, this application also provides a method for measuring the internal friction damping of a ball joint in a high-precision instrument. The ball joints of the two ball joints are respectively fixedly connected to the two ends of a connecting rod. The connecting rod and the ball joints connected to its two ends are used as a set of test pieces. After applying a load in the same direction as the connecting rod to the test piece from the end, a vibration load perpendicular to the direction of the connecting rod is applied to one of the ball joints. The internal friction damping of the ball joint is obtained based on the displacement and load of the ball joint.

[0019] In one embodiment, the measurement method is performed using the aforementioned measuring device.

[0020] In the technical solution of this application, a connecting rod and two ball joints connected to its two ends are used as test pieces. After the base is directly connected to the ball joint seat, loads and vibrations are applied to the test pieces. With the help of the structure of the ball joints in this application, there are very few connecting parts and no other external friction factors are introduced, thus improving the accuracy of the data. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the measuring device for the internal friction damping of the ball joint in the high-precision instrument equipment in Embodiment 1 of this application;

[0022] Figure 2 This is a schematic diagram of the structure of the central base of the measuring device in Embodiment 1 of this application;

[0023] Figure 3Damped hysteresis curve under 4Hz excitation obtained using the measuring device provided in Embodiment 1 of this application for the Japanese SRJ006c ball joint bearing. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The principles and features of the present invention are described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0025] Example 1

[0026] Reference Figure 1 and Figure 2 The high-precision instrument and equipment provided in this embodiment has a measuring device for the internal friction damping of ball joints. The test piece of the testing device is a connecting rod 102 and two ball joints 101 connected to its two ends. The connecting rod 102 is fixedly connected to the ball rod 104 of the ball joint 101. The fixed connection between the connecting rod 102 and the ball head of the ball joint 101 includes threaded connection, interference fit and adhesive bonding, to ensure that friction during measurement is caused only by the relative movement between the internal structures of the ball joint.

[0027] The measuring device includes:

[0028] Two bases, including a middle base 7 and an end base 2, are used to fix the ball head seat of the ball joint 101. Both the middle base 7 and the end base 2 are fixed on the clamp 1.

[0029] The exciter 4 has its output end connected to the central base 7 and its input end connected to the signal generator 5.

[0030] Displacement sensor 9 is used to measure the displacement of the ball head inside the ball head seat;

[0031] The first force sensor 3 is installed between the central base 7 and the ball joint 101;

[0032] The second force sensor 6 is installed between the vibrator 4 and the central base 7.

[0033] In this embodiment, to obtain the frictional damping of the ball joint under different loads, the clamping force applied by the clamp 1 to the end base 2 is adjusted. Specifically, the clamp 1 includes two symmetrically arranged jaws mounted on a slide rail. The jaws can slide on the slide rail or be fixed to the slide rail by fasteners. The two jaws are connected to the two ends of a double-ended stud. By rotating the double-ended stud in different directions, the relative position of the base 2 on the clamp 1 is finely adjusted, thereby changing the force on the ball joint 101 to ensure that the force on the ball joint 101 is the target load. In addition to the aforementioned specific embodiment, other embodiments are also possible, as long as they achieve the application of different clamping forces from the clamp 1 to the end base 2. The first force sensor 3 is located between one of the bases and the ball joint fixed on that base. The data from the first force sensor 3 is read and used as the force on the ball joint 101.

[0034] In this embodiment, the displacement sensor 9 determines the displacement of the ball head by measuring the displacement of the connecting rod 102. A laser emitter can be selected as the displacement sensor 9 and fixed on the experimental platform. The laser focus of the displacement sensor 9 is located at the center point or other reference point of the ball-joint threaded connecting rod. The displacement of the center point or other reference point is the displacement of the ball head. Compared with directly measuring the displacement of the ball head, this measurement method is easier and more accurate.

[0035] In order to obtain the load of the ball joint, in this embodiment, the first force sensor is disposed between one of the bases and the ball joint fixed on the base, and the load of the ball joint is obtained according to the reading of the first force sensor.

[0036] In a preferred embodiment provided in this example, the base includes a central base 7 and end bases 2 located on both sides thereon;

[0037] The connecting rod 102 and the ball joints 101 connected to its two ends form a set of test pieces. The connecting rods 102 of the two sets of test pieces are coaxially arranged, which simplifies the force structure and makes it easier to obtain measurement results. Two adjacent ball joints on the central base 7 are fixed back to back. See [reference needed]. Figure 2 The other two ball joints 101 are fixed to the end base 2. In this embodiment, the first force sensor 3 is installed inside the middle base 7, located between the two ball joints 101. This embodiment further reduces the number of parts and can obtain the load of the ball joints more accurately. In a specific embodiment, a through hole is formed on the middle base 7. The through hole and the outer contour surface of the ball joint seat 103 of the ball joint 101 are transitionally fitted. The ball joint 101 fixed to the middle base 7 is disposed in the through hole, and the first force sensor 3 is disposed between the two ball joints 101 located in the through hole.

[0038] In this embodiment, the side of the central base 7 without the through hole is connected to the output end of the exciter 4.

[0039] In this embodiment, four identical ball joints are used simultaneously for friction damping experiments, improving the accuracy of the results and reducing the impact of manufacturing errors. Furthermore, the relative motion between the ball joint and the base is the only moving part, ensuring a single source of friction damping and significantly improving precision. The device, with its built-in first force sensor 3, allows for the measurement of ball joint damping under different clamping forces, making it suitable for measuring ball joint damping under actual working conditions in various applications, thus possessing engineering practicality. The measuring device is also simple and the experiment is highly repeatable. The key innovation of this implementation lies in the symmetrical arrangement of the four ball joints, which ensures the excitation direction follows a predetermined single degree of freedom, and the relative motion on the left and right sides is consistent, resulting in more accurate results. Compared to test devices that only test one connecting rod and the two ball joints connected to its ends, this implementation more reliably ensures no deflection occurs at different degrees of freedom, thus minimizing test result deviation.

[0040] In this embodiment, the measuring device also includes a data acquisition and analysis system. The data acquisition and analysis system 8 collects the output of the exciter 4, the output of the displacement sensor 9, and the outputs of the first force sensor 3 and the second force sensor 6, and outputs the damping hysteresis curve of the ball joint based on the collected information. Figure 3 Used for Japanese SRJ006c ball joint bearings Figure 1 and Figure 2 The measurement device shown presents the damping hysteresis curve obtained under 4Hz excitation. The graph shows that the hysteresis curve stabilizes after several cycles, exhibiting a relatively complete elliptical shape. Qualitatively, it can be concluded that the curve exhibits excellent viscous damping characteristics at this frequency. Quantitatively, the corresponding damping value can be obtained by fitting the shape of this ellipse.

[0041] When conducting measurements, according to Figure 1 After connecting the testing device, the first force sensor 3, the second force displacement sensor 6, and the displacement sensor 9 are connected to the data acquisition and analysis system 8, and the exciter 4 is connected to the signal generator 5. Turn on the signal generator 5 and set the target excitation frequency and displacement amplitude; turn on the data acquisition and analysis system 8, ensuring that the first force sensor 3, the second force sensor 6, and the displacement sensor 9 can output data normally. Fine-tune the relative position of the base 2 on the fixture 1 to change the force on the ball joint 101, and read the data from the first force sensor 3 to ensure that the force on the ball joint 101 is equal to the target load.

[0042] The exciter 4 is turned on and outputs reciprocating displacement excitation under the control of the signal generator signal 5. In this embodiment, the exciter 4 is used to load the reciprocating displacement excitation to ensure that the friction on both sides of the ball head contact area with the ball rod 104 as the axis can be tested. This ensures that the force measured by the second force sensor 6 is the sum of the frictional forces in the four ball joints 101 in real time, and the displacement signal measured by the displacement sensor 9 is the displacement signal of the movable end of a single ball joint 101. The damping hysteresis curve of a single ball joint can be plotted based on the obtained force and displacement data.

[0043] By changing the frequency of the excitation signal of the vibrator 4 and the relative position of the base on the fixture 1, the damping characteristics of the ball joint under different frequencies and loads can be obtained.

[0044] Using the measuring device provided in this embodiment, a connecting rod and two ball joints connected to its two ends are used as test pieces. After the base is directly connected to the ball joint seat, a load and vibration are applied to the test pieces. Due to the structure of the ball joint itself, there are very few connecting parts and no other external friction factors are introduced, thus improving the data accuracy.

[0045] Example 2

[0046] This embodiment provides a method for measuring the internal friction damping of ball joints in high-precision instruments. The key invention lies in fixing the ball joints of two ball joints to the two ends of a connecting rod. The connecting rod and the ball joints connected to its ends form a test piece. After applying a load in the same direction as the connecting rod to the test piece from its ends, a vibration load perpendicular to the connecting rod is applied to one of the ball joints. The internal friction damping of the ball joint is then obtained based on the displacement and load of the ball joint. By using a connecting rod and the two ball joints connected to its ends as the test piece, and directly connecting the base to the ball joint seat before loading and vibrating the test piece, the structure of the ball joint itself minimizes the number of connecting parts and avoids introducing other external friction factors, thus improving data accuracy.

[0047] By implementing the above measurement method, the measuring device provided in Example 1 can be used to measure the internal friction damping of the ball joint in high-precision instruments and equipment.

[0048] During measurement, the clamping force applied by the fixture to the base is adjusted according to the target load; the output of the signal generator is changed to obtain the damping hysteresis curves of the ball joint at different frequencies.

[0049] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A measuring device for the internal friction damping of a ball joint in high-precision instruments and equipment, characterized in that, The test piece of the testing device is a connecting rod and two ball joints connected to its two ends. The connecting rod is fixedly connected to the ball joints. The measuring device includes: At least two bases are provided for fixing the ball joint's ball head, and the bases are fixed to the clamp. A vibrator, the output of which is connected to one of the bases, and the input of which is connected to a signal generator; A displacement sensor is used to measure the displacement of the ball head within the ball head seat; A first force sensor is installed between the base and the ball joint; A second force sensor is installed between the vibrator and the base.

2. The measuring device according to claim 1, characterized in that, The clamping force applied by the clamp to the base is adjustable.

3. The measuring device according to claim 1, characterized in that, The displacement sensor determines the displacement of the ball head by measuring the displacement of the threaded rod.

4. The measuring device according to claim 1, characterized in that, The first force sensor is located between one of the bases and a ball joint fixed on the base.

5. The measuring device according to claim 1, characterized in that, The base includes a central base and end bases; The connecting rod and the ball joints connected to its two ends form a set of test pieces. The connecting rods of the two sets of test pieces are coaxially arranged, and two adjacent ball joints are fixed to a central base facing away from each other, while the other two ball joints are fixed to the end bases.

6. The measuring device according to claim 5, characterized in that, A through hole is provided on the central base. The through hole and the outer contour surface of the ball joint seat of the ball joint are in transition fit. The ball joint fixed to the central base is located in the through hole. The first force sensor is provided between the two ball joints located in the through hole.

7. The measuring device according to claim 6, characterized in that, The output end of the exciter is connected to the side of the central base where the through hole is not opened.

8. The measuring device according to claim 1, characterized in that, It also includes a data acquisition and analysis system, which collects the output of the exciter, the output of the displacement sensor, and the outputs of the first force sensor and the second force sensor, and outputs the damping hysteresis curve of the ball joint.

9. A method for measuring the internal friction damping of a ball joint in high-precision instruments and equipment, characterized in that, The two ball joints are respectively fixedly connected to the two ends of a connecting rod. The connecting rod and the ball joints connected to its two ends are used as a set of test pieces. After applying a load in the same direction as the connecting rod to the test piece from the end, a vibration load perpendicular to the connecting rod is applied to one of the ball joints. The internal friction damping of the ball joint is obtained based on the displacement and load of the ball joint.

10. The measurement method according to claim 9, characterized in that, The measuring device described in any one of claims 1 to 8 is used to measure the internal friction damping of a ball joint in a high-precision instrument.

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