A flexible center of mass measurement tooling for eccentric structures

Abstract

A flexible center of mass measuring tool suitable for eccentric structure, comprising a support ring connected with an external measuring device and a product frame connected with a product to be measured, the product frame being located above the support ring and coaxial with the support ring; further comprising support rods uniformly arranged between the support ring and the product frame in the circumferential direction, each support rod being a telescopic adjusting rod, one end of each support rod being hinged to the support ring and the other end being hinged to the product frame. Through reasonable setting of the component structure, the support rods only transmit axial pressure and do not bear shear force and bending moment, completely solving the force coupling problem of the measuring system caused by the gravity center deviation of the eccentric structure, making the load data obtained by the bottom force measuring device more pure, and greatly improving the calculation accuracy of the center of mass coordinates; at the same time, each support rod is a telescopic adjusting rod, so that the operator can independently adjust the height of each support rod, even if the initial state of the product is severely inclined, the product can also be quickly leveled through fine adjustment, shortening the test preparation period, good adaptability and simple operation.

Description

Technical Field

[0001] This invention belongs to the field of quality characteristic testing technology, specifically relating to a flexible centroid measurement fixture suitable for eccentric structures. Background Technology

[0002] With the increasing complexity of modern industrial design, more and more products, in order to meet specific functional requirements, internal load distribution, or external aerodynamic shapes, often exhibit high asymmetry and uneven internal mass distribution, forming "eccentric structures." Traditional measuring fixtures have revealed numerous technical bottlenecks when measuring the center of mass of such eccentric structures.

[0003] Severe stress coupling and shear interference: Traditional centroid measurement fixtures typically use a rigid connection to fix the product under test to the bottom force sensor (or centroid measuring platform). When an eccentric product is placed on a rigid fixture, because its line of action of gravity deviates from the geometric center, it not only generates a vertically downward normal force on the supporting structure, but also generates shear force and bending moment at the rigid connection due to the eccentric moment. Traditional force sensors are often extremely sensitive to shear force and bending moment, leading to reading distortion and consequently, significant errors in centroid calculation.

[0004] Leveling is difficult and unstable: Center of mass measurement requires extremely high system levelness. Even slight tilting introduces a horizontal component of gravity, leading to systematic deviations in the measurement results. When the center of mass deviates from the center of rotation, it generates a gravitational torque that causes the product to rotate, resulting in uneven stress on the support points. Rigid fixtures are prone to slight deformation and can easily cause the product to slip during measurement. Furthermore, there is a lack of convenient, high-precision multi-point independent height adjustment mechanisms, making the initial leveling process time-consuming and laborious.

[0005] Friction causes hysteresis error: During tooling assembly and fine-tuning, the static friction between the kinematic pairs prevents the complete release of internal stresses in the system. Under eccentric loads, these unreleased internal stresses can generate unpredictable hysteresis errors due to minute vibrations during the measurement process, affecting the repeatability and reliability of the measurement. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a flexible centroid measurement fixture suitable for eccentric structures, thereby solving the technical problems of limited measurement accuracy, poor adaptability, and cumbersome operation of existing centroid measurement fixtures when dealing with eccentric structures.

[0007] To achieve the above objectives, the technical solution adopted by the present invention includes: A flexible centroid measuring fixture suitable for eccentric structures includes a support ring connected to an external measuring device and a product frame connected to the product to be measured, with the product frame located above the support ring and the two being coaxial; it also includes at least three support rods evenly distributed circumferentially between the support ring and the product frame, each support rod being a telescopic adjustable rod, with one end of each support rod hinged to the support ring and the other end hinged to the product frame.

[0008] Preferably, one end of each support rod is hinged to the support ring via a bearing, and the other end is hinged to the product frame via a bearing.

[0009] Preferably, the bearing is a high-precision self-aligning ball bearing or a spherical plain bearing.

[0010] Preferably, there are 4 support rods, each of which is evenly distributed at a 90-degree angle along the circumference of the support ring, and the intersection of the force center lines of each support rod coincides with the geometric center line of the support ring.

[0011] Preferably, any support rod includes a forward threaded section, a reverse threaded section, and an intermediate leveling sleeve, with the forward threaded section and the reverse threaded section respectively connected to the two ends of the intermediate leveling sleeve through threaded pairs.

[0012] Preferably, the forward-rotating thread section and / or the reverse-rotating thread section are also provided with anti-loosening nuts, which are tightened after leveling to abut against at least one end face of the intermediate leveling sleeve.

[0013] Preferably, the product rack has a square interface design with the diagonals of the square interface arranged horizontally.

[0014] Preferably, the product rack is equipped with a high-precision dual-axis level mounting base.

[0015] Preferably, both the support ring and the product frame are made of aerospace-grade aluminum alloy or high-strength lightweight alloy materials.

[0016] Preferably, the surfaces of the support ring and the product frame are both subjected to hard anodizing treatment, with a surface hardness of not less than HV400.

[0017] Compared with the prior art, the advantages of the present invention are: (1) The present invention provides a flexible centroid measuring fixture suitable for eccentric structures. Through the reasonable setting of the component structure, the support rods only transmit axial pressure and do not bear shear force and bending moment, which completely solves the problem of force coupling of the measurement system caused by the centroid offset of the eccentric structure. This makes the load data obtained by the bottom force measuring device purer and greatly improves the calculation accuracy of the centroid coordinates. At the same time, each support rod is a telescopic adjustable rod, which allows the operator to independently adjust the height of each support rod. Even if the product is seriously tilted in the initial state, it can be quickly leveled by fine adjustment, which shortens the test preparation cycle. It has good adaptability and is easy to operate.

[0018] (2) The present invention provides a flexible centroid measuring fixture suitable for eccentric structures. The product frame adopts a square interface design and is arranged horizontally diagonally. Combined with the uniform distribution of four support rods, it provides stable anti-overturning support for eccentric products, ensuring the stability of the products during the measurement process and avoiding safety hazards and test errors caused by relative sliding.

[0019] (3) The present invention provides a flexible centroid measuring fixture suitable for eccentric structures. The height of each support rod is independently adjustable. Combined with the bidirectional positive and negative screw structure of the intermediate leveling sleeve, it greatly simplifies the leveling operation process before testing. Even if the product is seriously tilted in the initial state, the operator can quickly achieve levelness through fine adjustment, shorten the test preparation cycle, and improve work efficiency. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the flexible centroid measuring tool applicable to eccentric structures according to the present invention.

[0021] The labels in the diagram represent: 1—Support ring; 2—Product frame; 3—Support rod; 3-1—Bearing; 3-2—Leveling sleeve. Detailed Implementation

[0022] The invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of this invention.

[0023] It should be noted that the directional terms mentioned herein are consistent with the specific directions on the paper in the accompanying drawings or the corresponding directions of the space shown in the drawings; all components and devices in this invention, unless otherwise specified, are components and devices known in the prior art.

[0024] This application discloses a flexible centroid measurement fixture suitable for eccentric structures, including a support ring 1 connected to an external measuring device and a product frame 2 connected to the product to be measured. The product frame 2 is located above the support ring 1 and the two are coaxial. It also includes at least three support rods 3 evenly distributed circumferentially between the support ring 1 and the product frame 2. Each support rod 3 is a telescopic adjustable rod, with one end of each support rod 3 hinged to the support ring 1 and the other end hinged to the product frame 2.

[0025] Its function is as follows: Through the hinged design at both ends of the support rod 3, the support rod 3 only bears axial pressure along its axis during measurement, without bearing horizontal shear force or bending moment. This fundamentally eliminates the multi-dimensional force coupling problem caused by eccentric loads, making the load data obtained by the bottom force measuring device purer and significantly improving the accuracy of the centroid coordinate calculation. Simultaneously, each support rod 3 is a telescopic adjustable rod, allowing operators to independently adjust the height of each support rod 3. Even if the product is initially severely tilted, it can be quickly leveled through fine adjustments, shortening the test preparation cycle. It is highly adaptable and easy to operate.

[0026] Specifically, one end of each support rod 3 is hinged to the support ring 1 via bearing 3-1, and the other end is hinged to the product frame 2 via bearing 3-1.

[0027] Its function is as follows: By using bearing 3-1 as a hinge element, a flexible two-force constraint structure is formed between support rod 3, support ring 1 and product frame 3. When the eccentric product has a tendency to be squeezed laterally, bearing 3-1 at the end of support rod 3 will rotate slightly to release shear force, thereby ensuring that support rod 3 only bears axial pressure and does not bear shear force and bending moment in the measurement state.

[0028] Specifically, bearing 3-1 is a high-precision self-aligning ball bearing or a spherical plain bearing 3-1. It can adaptively release multi-degree-of-freedom angular displacement when the product frame is subjected to eccentric load and tends to tilt, eliminating hysteresis errors caused by static internal stress; the extremely low coefficient of friction ensures that the system can quickly achieve adaptive alignment under eccentric load, improving the repeatability and reliability of measurement.

[0029] Specifically, there are 4 support rods 3, which are evenly distributed at a 90-degree angle along the circumference of the support ring 1, and the intersection of the force center lines of each support rod 3 coincides with the geometric center line of the support ring 1.

[0030] Its function is to make the force on the product rack more even and symmetrical, provide anti-overturning support for eccentric products, and ensure the stability of the product during the measurement process; at the same time, this layout, in conjunction with the square interface design, can effectively distribute the force in the four quadrants.

[0031] Specifically, any support rod 3 includes a forward threaded section, a reverse threaded section, and an intermediate leveling sleeve 3-2. The forward threaded section and the reverse threaded section are respectively connected to the two ends of the intermediate leveling sleeve 3-2 through threaded pairs.

[0032] Its function is as follows: Since the threads at both ends rotate in opposite directions, when the middle leveling sleeve is rotated, the forward and reverse thread sections at both ends will simultaneously retract into the middle leveling sleeve 3-2 or extend outward, thereby achieving stepless fine adjustment of the length of the support rod 3; the operator can independently and precisely adjust the height of each support rod 3, and it can also be used with a precision level to quickly and accurately adjust the test plane to an absolutely horizontal state.

[0033] Specifically, a high-precision dual-axis level is installed on the central area or geometric axis of the product rack 2. When in use, a high-precision dual-axis level can be installed to assist in monitoring and dynamically feeding back the changes in the levelness of the product rack during the leveling and measurement process, making the leveling process visible and data-driven, and enabling operators to complete the leveling operation more efficiently and accurately.

[0034] Specifically, the forward-rotating thread section and / or the reverse-rotating thread section are also provided with anti-loosening nuts. After leveling is completed, tighten the anti-loosening nuts to abut against at least one end face of the intermediate leveling sleeve 3-2.

[0035] Its function is to ensure the long-term stability of the leveling state by setting the anti-loosening nut. During the measurement process, even if there is slight vibration, the anti-loosening nut can effectively prevent the intermediate leveling sleeve 3-2 from loosening or rotating, thereby ensuring the continuous stability of the product rack's levelness.

[0036] Specifically, product rack 2 features a square interface design with the diagonals of the square interface arranged horizontally.

[0037] Its function is as follows: The design of the square product rack 2, combined with the horizontal arrangement of the diagonals, can effectively prevent the eccentric products from sliding relative to each other due to the gravitational torque during the measurement process. In addition, the square layout can effectively distribute the force in the four quadrants, providing stable support for the eccentric products.

[0038] Both the support ring 1 and the product frame 2 in this application are made of aerospace-grade aluminum alloy or high-strength lightweight alloy materials, which reduces the weight of the tooling while ensuring the overall rigidity of the tooling. The surfaces of both the support ring 1 and the product frame 2 are hard anodized, with a surface hardness of not less than HV400, which improves the wear resistance of the tooling surface and extends the service life of the tooling; at the same time, it also reduces the coefficient of friction between the adjustment contact surfaces, making the fine-tuning operation of the tooling during use smoother and further reducing the impact of friction on measurement accuracy.

[0039] Example like Figure 1 As shown in the figure, this embodiment provides a flexible centroid measurement fixture suitable for eccentric structures. The fixture mainly consists of a three-layer architecture: a basic connection layer, a flexible support layer, and a load layer.

[0040] 1. Specific structure of the basic connection layer The basic connection layer includes a support ring 1, which is forged from aerospace-grade ultra-high-strength aluminum alloy to ensure its extremely high rigidity and prevent deformation under heavy loads. Support ring 1 is used to connect to external measuring equipment, such as a triaxial centroid measuring stage, and its external structure can be adjusted according to the equipment interface. The surface of support ring 1 undergoes hard anodizing treatment, with a surface hardness of not less than HV400, to improve wear resistance and reduce the coefficient of friction between the adjustment contact surfaces.

[0041] The support ring 1 is provided with four mounting brackets. The four brackets are evenly distributed at a 90-degree angle along the circumference of the support ring 1. The intersection of the force center lines of the four brackets in the horizontal plane coincides with the geometric center of the support ring 1.

[0042] 2. Specific structure of the flexible support layer The flexible support layer includes four support rods 3. One end of each support rod 3 is hinged to a bracket on the support ring 1 via a bearing 3-1, and the other end is hinged to a bracket on the product frame 2 via a bearing 3-1. The bearings 3-1 are high-precision self-aligning ball bearings or spherical plain bearings 3-1.

[0043] Through this bearing connection design, a flexible two-force constraint structure is formed between each support rod 3, the support ring 1, and the product frame 2. When the eccentric product exhibits a lateral compression tendency, the bearing 3-1 at the end of the support rod 3 will rotate slightly, releasing the shear force. This ensures that each support rod 3 only bears axial pressure along its axis during measurement, without bearing horizontal shear force and bending moment, fundamentally eliminating the multi-dimensional force coupling measurement error caused by eccentric loads.

[0044] To achieve fine-tuning of height, each support rod 3 is equipped with a bidirectional forward and reverse screw leveling mechanism in the middle. Specifically, each support rod 3 includes a forward threaded section, a reverse threaded section, and an intermediate leveling sleeve 3-2. The forward and reverse threaded sections are connected to both ends of the intermediate leveling sleeve 3-2 via threaded pairs. In other words, the intermediate leveling sleeve 3-2 is an internally threaded sleeve with forward and reverse internal threads machined at both ends. The upper and lower ends of the support rod 3 are machined with corresponding forward and reverse external threads (i.e., forward and reverse threaded sections), which are screwed into the internal threads at both ends of the intermediate leveling sleeve 3-2. Because the threads at both ends rotate in opposite directions, the operator only needs to rotate the intermediate leveling sleeve 3-2, and the threaded sections at both ends will simultaneously retract into the sleeve or extend outward, thereby achieving stepless fine-tuning of the length of the support rod 3 to adapt to different height and leveling measurement requirements.

[0045] Each support rod 3 is equipped with a locking nut on both the forward and reverse threaded sections. After the product frame 2 is leveled, the operator tightens the locking nut so that its end face abuts against the corresponding end face of the intermediate leveling sleeve 3-2. The friction force generated by the double nut locking principle can lock the height of the support rod 3, preventing the intermediate leveling sleeve 3-2 from rotating and loosening on its own due to vibration during the measurement process.

[0046] 3. Specific structure of the load layer The load layer includes product rack 2, which adopts a square interface design. The diagonals of the square interface are arranged horizontally to prevent slippage during measurement due to the product's center of gravity deviating from the rotation center. The square layout effectively distributes the force in the four quadrants, ensuring the stability of the product during measurement.

[0047] The product rack 2 is equipped with a high-precision dual-axis level mounting base, which is used to install a high-precision dual-axis level to assist in monitoring and dynamically feeding back the changes in the levelness of the product rack 2 during the leveling and measurement processes.

[0048] Product rack 2 is also made of aerospace-grade ultra-high strength aluminum alloy, and the surface is treated with hard anodizing, with a surface hardness of not less than HV400.

[0049] 4. Operation process of the tooling of the present invention The following describes the usage method of the tooling of the present invention with specific operating steps.

[0050] Step 1: Installation of support rods and bearings. Install the four support rods 3, each equipped with a high-precision bearing 3-1, onto the bracket of the support ring 1, ensuring that each bearing 3-1 rotates freely without jamming.

[0051] Step 2: Product rack installation and initial rough adjustment. Install the product rack 2 on the upper end of each support rod 3, initially ensuring that the diagonals of its square interface are horizontal.

[0052] Step 3: Connect the tooling components to the test bench. Adjust the interface of support ring 1 to fix the entire tooling onto the external measuring equipment.

[0053] Step 4: Independent multi-point fine-tuning. Adjust the height of each support rod 3 independently by rotating the intermediate leveling sleeve 3-2 on each support rod 3. Observe the adjustment using a level installed on the product frame 2 until the level displays the required test accuracy. After leveling, tighten the anti-loosening nut to lock the height of each support rod 3.

[0054] Step 5: Zero the measurement system. Under no-load and horizontal conditions, zero-calibrate the bottom centroid measuring equipment to eliminate the influence of the tooling's own weight on subsequent measurements.

[0055] Step Six: Interface Adjustment. Based on the shape characteristics of the eccentric product to be tested, match and connect the product to product rack 2.

[0056] Step 7: Product hoisting and measurement. The eccentric product is placed stably on product rack 2 using hoisting equipment. The force data of the measuring equipment is read, and the three-dimensional coordinates of the center of mass of the eccentric product are calculated in real time by the system software.

[0057] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0058] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0059] Furthermore, the various implementation methods disclosed in this solution can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content invented by this disclosure.

Claims

1. A flexible centroid measuring fixture suitable for eccentric structures, characterized in that, It includes a support ring (1) connected to an external measuring device and a product rack (2) connected to the product to be tested, wherein the product rack (2) is located above the support ring (1) and the two are coaxial; It also includes at least three support rods (3) evenly distributed circumferentially between the support ring (1) and the product frame (2). Each of the support rods (3) is a telescopic adjustable rod. One end of each support rod (3) is hinged to the support ring (1), and the other end is hinged to the product frame (2).

2. The flexible centroid measuring fixture for eccentric structures according to claim 1, characterized in that, One end of each of the support rods (3) is hinged to the support ring (1) via a bearing (3-1), and the other end is hinged to the product frame (2) via a bearing (3-1).

3. The flexible centroid measuring fixture for eccentric structures according to claim 2, characterized in that, The bearing (3-1) is a high-precision self-aligning ball bearing or a spherical plain bearing (3-1).

4. The flexible centroid measuring fixture for eccentric structures according to claim 3, characterized in that, There are 4 support rods (3), and each support rod (3) is evenly distributed at a 90-degree angle along the circumference of the support ring (1), and the intersection of the force center lines of each support rod (3) coincides with the geometric center line of the support ring (1).

5. The flexible centroid measuring fixture suitable for eccentric structures according to any one of claims 1 to 4, characterized in that, Each of the support rods (3) includes a forward threaded section, a reverse threaded section, and an intermediate leveling sleeve (3-2). The forward threaded section and the reverse threaded section are respectively connected to the two ends of the intermediate leveling sleeve (3-2) through a threaded pair.

6. The flexible centroid measuring fixture for eccentric structures according to claim 5, characterized in that, The forward-rotating thread section and / or the reverse-rotating thread section are also provided with anti-loosening nuts. After leveling is completed, tighten the anti-loosening nuts to abut against at least one end face of the intermediate leveling sleeve (3-2).

7. The flexible centroid measuring fixture for eccentric structures according to claim 6, characterized in that, The product rack (2) is designed with a square interface, and the diagonal of the square interface is arranged horizontally.

8. The flexible centroid measuring fixture for eccentric structures according to claim 7, characterized in that, The product rack (2) is equipped with a high-precision dual-axis level mounting base.

9. The flexible centroid measuring fixture for eccentric structures according to claim 8, characterized in that, Both the support ring (1) and the product frame (2) are made of aerospace-grade aluminum alloy or high-strength lightweight alloy materials.

10. The flexible centroid measuring fixture for eccentric structures according to claim 9, characterized in that, The surfaces of the support ring (1) and the product frame (2) are both subjected to hard anodizing treatment, and the surface hardness is not less than HV400.

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