A dynamic stiffness measuring device

Abstract

The application relates to a dynamic stiffness measuring device, which comprises a frame, an excitation mechanism, a preloading mechanism arranged above the excitation mechanism and a lifting mechanism; the lifting mechanism comprises an upper lifting plate, a lower lifting plate, a plurality of first guide shafts penetrating through the upper lifting plate and the lower lifting plate and a lifter connected to the lower lifting plate; the preloading mechanism is arranged between the upper lifting plate and the lower lifting plate; the preloading mechanism comprises a mass upper connecting plate, a mass lower connecting plate, an inertial mass fixed between the mass upper connecting plate and the mass lower connecting plate, a plurality of second guide shafts penetrating through the mass upper connecting plate and the mass lower connecting plate; one end of the second guide shaft is connected to the lower lifting plate, and the other end is connected to the upper lifting plate; the device further comprises a force sensor and an acceleration sensor. The application has the characteristics of high preloading adjustment flexibility, strong test universality and high detection accuracy.

Description

Technical Field

[0001] This utility model relates to the field of dynamic stiffness measurement, and in particular to a dynamic stiffness measuring device. Background Technology

[0002] Dynamic stiffness is a physical quantity that describes a structure's ability to resist elastic deformation under dynamic loads. Its measurement standard is the dynamic force required to induce a unit amplitude of vibration. In engineering applications, dynamic stiffness directly affects the working accuracy of mechanical systems, such as machine tool cutting stability and gear shaft transmission error control.

[0003] Dynamic stiffness measuring devices simulate the actual working conditions of a workpiece by applying a predetermined static preload (preload) and a superimposed dynamic excitation load, and measure its response to calculate the dynamic stiffness value. In existing dynamic stiffness measuring devices, the setup of the preload mechanism is crucial. A typical preload mechanism usually includes an inertial mass block, a force sensor, and an indenter, used to apply a stable and accurate static preload to the workpiece to simulate its installation state under actual working conditions. Traditional preload mechanisms are fixed to a base by a rigid bracket or gantry; however, this has several significant technical drawbacks: Low adjustment accuracy and efficiency: The height adjustment of the preload mechanism relies on the overall movement of a large support or base, resulting in a rough adjustment process that makes it difficult to achieve high-precision positioning. For tests requiring precise control of the preload contact point, traditional preload mechanisms often require repeated trial and error, leading to low adjustment efficiency and difficulty in ensuring consistency of initial conditions for each test.

[0004] Poor versatility and strong tooling dependence: Because the final height of the preload mechanism is fixed or has a limited adjustment range, when changing to different models or sizes of test pieces, it is often necessary to redesign or replace the supporting tooling below to adapt to the height of the preload mechanism. This greatly increases test preparation time and cost, and reduces the versatility of the equipment and the flexibility of testing.

[0005] Low level of automation and integration: The existing structure is difficult to integrate seamlessly with modern automatic control systems. Achieving highly automated, programmable, and precise preload adjustments is very difficult, limiting the application of this measuring device in automated production lines or high-precision, high-volume testing scenarios.

[0006] Therefore, those skilled in the art have long been dedicated to finding a solution for a dynamic stiffness measurement device that can achieve high-precision, flexible, and rapid adjustment of the preload mechanism. Utility Model Content

[0007] The purpose of this application is to address the shortcomings of the prior art and to provide a dynamic stiffness measuring device.

[0008] The dynamic stiffness measuring device includes: a frame, an excitation mechanism connected to the bottom of the frame, a preload mechanism connected to the frame and disposed above the excitation mechanism, and a lifting mechanism connected to the frame and used to raise or lower the preload mechanism. The lifting mechanism includes an upper lifting plate, a lower lifting plate, a plurality of first guide shafts passing through the upper lifting plate and the lower lifting plate, and a lifter connected to the lower lifting plate; the preload mechanism is disposed between the upper lifting plate and the lower lifting plate. The preload mechanism includes an upper connecting plate for the mass block, a lower connecting plate for the mass block, an inertial mass block fixed between the upper connecting plate for the mass block and the lower connecting plate for the mass block, and a plurality of second guide shafts passing through the upper connecting plate for the mass block and the lower connecting plate for the mass block; one end of the second guide shaft is connected to the lower lifting plate, and the other end is connected to the upper lifting plate; It also includes a force sensor and an acceleration sensor. One end of the force sensor is connected to the excitation mechanism and the other end is connected to the preload mechanism. The acceleration sensor is mounted on the vibration excitation mechanism.

[0009] More specifically, the frame includes a bottom frame plate connected to each other, a top frame plate at the top, and a middle frame plate located between the bottom frame plate and the top frame plate; the excitation mechanism is disposed on the bottom frame plate, and the preload mechanism is disposed between the middle frame plate and the top frame plate.

[0010] More specifically, the frame has a detection through hole on its plate, and the excitation mechanism passes through the detection through hole.

[0011] More specifically, the excitation mechanism includes a support and a vibrator mounted on the support, the support being fixed to the frame base plate, and the vibrator partially passing through a detection through hole.

[0012] More specifically, the exciter is connected to the support via several first dampers.

[0013] More specifically, it also includes a testing fixture for fixing the workpiece to be tested, the testing fixture including a lower fixture that abuts against the excitation mechanism and an upper fixture that abuts against the preload mechanism.

[0014] More specifically, the lower lifting plate has a through hole, and the upper tooling abuts against the lower connecting plate of the mass block through the through hole.

[0015] More specifically, the lifting device includes a motor mounted on the frame base plate and a lifting screw connected to the motor, the lifting screw being threadedly connected to the lower lifting plate.

[0016] More specifically, the number of lifting screws is 2, and the motor drives the lifting screws through a split-drive and a reversing drive connected to both ends of the split-drive.

[0017] More specifically, a second shock absorber is provided between the lower connecting plate of the mass block and the lower lifting plate.

[0018] Compared with the prior art, the dynamic stiffness measuring device provided by this utility model achieves the following significant advantages by integrating the preload mechanism into an independent lifting mechanism: This invention achieves high-precision and high-efficiency application of preload force: Through an independent lifting mechanism, the position of the preload mechanism in the vertical direction (Z-axis) can be precisely and smoothly controlled. This allows the pressure head of the preload mechanism to approach and contact the test piece with micron-level precision, ensuring the precise controllability of the initial position and process of preload force application. Compared with the crude adjustment methods of moving bulky bases or supports in existing technologies, this invention greatly improves adjustment accuracy and efficiency, ensures the consistency of initial test conditions, and lays the foundation for highly repeatable and accurate measurements.

[0019] This significantly improves the versatility and testing flexibility of the device: The lifting mechanism enables the preload mechanism to position itself flexibly over a large stroke, allowing the same measuring device to quickly adapt to test pieces of different heights and models. When changing test pieces, there is no need to design or replace complex lower support fixtures; centering can be achieved simply by adjusting the height of the preload mechanism using the lifting mechanism. This greatly shortens test preparation time, reduces tooling costs, and significantly expands the application range of the equipment.

[0020] This effectively ensures the accuracy and reliability of the measurement results: precise height control ensures that the pressure head of the preload mechanism can be applied vertically and centrally to the loading point of the test piece along the preset axis, avoiding eccentric loads or bending moments caused by improper initial contact positions. This provides a clean and accurate mechanical environment for subsequent superimposed dynamic excitation, fundamentally reducing measurement errors introduced by structural problems of the device itself, thereby significantly improving the accuracy and reliability of dynamic stiffness measurement data.

[0021] In summary, this utility model solves multiple technical problems in terms of accuracy, efficiency, versatility and precision of existing dynamic stiffness measuring devices, and has outstanding technical advantages and broad application prospects. Attached Figure Description

[0022] Figure 1 This is a perspective view of the dynamic stiffness measuring device in this application.

[0023] Figure 2 This is a partial three-dimensional view of the dynamic stiffness measuring device in this application.

[0024] Figure 3 This is a perspective view of the lifting mechanism in this application.

[0025] Figure 4 This is a partial schematic diagram of the dynamic stiffness measuring device in this application.

[0026] In the diagram: 100, Frame; 101, Frame base plate; 102, Frame middle plate; 103, Frame top plate; 200, Excitation mechanism; 201, Vibrator; 202, Spring bracket; 203, Support; 204, First shock absorber; 300, Preload mechanism; 301, Upper connecting plate of mass block; 302, Lower connecting plate of mass block; 303, Second guide shaft; 304, Second shock absorber; 305, Inertial mass block; 400, Lifting mechanism; 401, Upper lifting plate; 402, Lower lifting plate; 403, First guide shaft; 411, Motor; 412, One-to-two transmission; 413, Reversing transmission; 414, Lifting screw; 501, Upper tooling; 502, Lower tooling; 503, Accelerometer; 504, Force sensor. Detailed Implementation

[0027] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0028] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figure 1 As shown, this application provides a dynamic stiffness measuring device. The device adopts a vertical configuration and specifically includes a frame 100, an excitation mechanism 200 connected to the bottom of the frame 100, a preload mechanism 300 connected to the frame 100 and disposed above the excitation mechanism 200, and a lifting mechanism 400 connected to the frame 100 for raising or lowering the preload mechanism 300. This application differs from traditional dynamic stiffness measuring devices where the preload is directly mounted on the frame. This application positions the preload mechanism 300 on the lifting mechanism 400, allowing for more flexible adjustment of the height of the preload mechanism 300, facilitating the measurement of the dynamic stiffness of test pieces of different models or sizes.

[0031] In some specific embodiments, to achieve high-precision and high-efficiency application of preload force, the lifting mechanism 400 includes an upper lifting plate 401, a lower lifting plate 402, several first guide shafts 403 passing through the upper lifting plate 401 and the lower lifting plate 402, and a lifter connected to the lower lifting plate 402. The preload mechanism 300 is disposed between the upper lifting plate 401 and the lower lifting plate 402. When it is necessary to adjust the height of the preload mechanism 300, the height adjustment can be automatically completed simply by activating the lifter. In some specific embodiments, such as... Figure 3 As shown, the lifting device includes a motor 411, a split-drive 412 connected to the shaft of the motor 411, two reversing drives 413 connected to both ends of the split-drive 412, and lifting screws 414 connected to the reversing drives 413. Both lifting screws 414 are threaded onto the lower lifting plate 402. The motor 411 drives the lifting screws 414 through the split-drive 412 and the reversing drives 413, thereby causing the lower lifting plate 402 and the upper lifting plate 401 to move on the first guide shaft 403. The height of the preload mechanism 300 can be conveniently, accurately, and quickly adjusted via the motor 411.

[0032] In some specific embodiments, such as Figure 2As shown, the preload mechanism 300 includes an upper connecting plate 301 for the mass block, a lower connecting plate 302 for the mass block, an inertial mass block 305 fixed between the upper connecting plate 301 and the lower connecting plate 302, and a plurality of second guide shafts 303 passing through the upper connecting plate 301 and the lower connecting plate 302. The inertial mass block 305 can move on the second guide shafts 303. One end of the second guide shaft 303 is connected to the lower lifting plate 402 of the lifting mechanism 400, and the other end is connected to the upper lifting plate 401.

[0033] This device boasts high versatility and testing flexibility. The lifting mechanism 400 enables the preload mechanism 300 to be positioned flexibly within a large stroke, allowing the same measuring device to quickly adapt to test pieces of different heights and models. When changing test pieces, there is no need to design or replace complex lower support fixtures; alignment can be achieved simply by adjusting the height of the preload mechanism 300 via the lifting mechanism 400. This significantly shortens test preparation time, reduces tooling costs, and greatly expands the equipment's application range.

[0034] The lifting mechanism 400 designed in this device can also be integrated with automation components such as encoders and PLCs (Programmable Logic Controllers) to achieve programmed and digital control of the preload height. When a batch of workpieces of the same size needs to be inspected, automatic positioning, automatic loading, and automatic adjustment can be performed according to the pre-set program, meeting the requirements of modern intelligent manufacturing and automated inspection production lines for high cycle time and high consistency of testing equipment, and improving the automation and intelligence level of the entire measurement system.

[0035] In some specific embodiments, such as Figure 2 As shown, the excitation mechanism 200 includes a vibrator 201, with several spring supports 202 connected to its side. The vibrator 201 is connected to a support 203 via the spring supports 202. The support 203 is fixed to the frame base plate 401. To improve space utilization, the lifting mechanism 400 is partially located within the excitation mechanism 200. Specifically, four spring supports 202 are provided on the side of the vibrator 201, each spring support 202 being mounted on a corresponding support 203. The motor 411, the splitter / reverse transmission 412, and the commutator 413 are all positioned in the gaps between the four supports 203.

[0036] The object under test typically has a fundamental modal frequency. To avoid coupling between the device's own frequency and these modes under test, thus interfering with the measurement, in some specific embodiments, this application provides a first shock absorber 204 between the spring bracket 202 and the support 203, and a second shock absorber 304 between the lower connecting plate 302 of the mass block and the lower lifting plate 402. Both the first shock absorber 204 and the second shock absorber 304 can be selected from any one of shock-absorbing airbags, shock-absorbing springs (such as air springs), and shock-absorbing rubber pads. Preferably, both the first shock absorber 204 and the second shock absorber 304 are air springs.

[0037] like Figure 4 As shown, the device also includes a force sensor 504 and an acceleration sensor 503. One end of the force sensor 504 is connected to the excitation mechanism 200, and the other end is connected to the preload mechanism 300. To achieve precise workpiece positioning and ensure coaxial transmission of force and vibration, the device also includes a detection fixture for fixing the workpiece to be tested. The detection fixture consists of an upper fixture 501 and a lower fixture 502. The lower fixture 502 is connected to one end of the force sensor 504 and abuts against the excitation coil of the vibrator 201; a through hole is provided on the lower lifting plate, and the other end of the upper fixture 501 is connected to the force sensor 504 and abuts against the lower connecting plate 302 of the mass block. The acceleration sensor 503 is fixed on the lower fixture 502 and is used to measure the vibration.

[0038] Before testing the dynamic stiffness of the workpiece, the workpiece is first fixed between the upper fixture 501 and the lower fixture 502. This stabilizes the excitation force and vibration signal, reduces signal loss or interference, and makes the test results more accurate. The testing fixture also avoids force signal loss or vibration transmission lag caused by poor direct contact between the workpiece and the equipment (such as slippage of the contact surface, excessive gap, or contact at the workpiece tip). This ensures that the dynamic force and vibration acceleration signals collected by the sensor accurately reflect the stress and vibration state of the workpiece.

[0039] In this application, the frame plate 102 is both the support platform of the lifting mechanism 400 and the operating platform for measuring dynamic stiffness. The frame plate 102 is provided with a detection through hole. The excitation coil of the vibrator 201 passes through the detection through hole and faces the preload mechanism 300. The plane of the vibrator 201 is flush with the frame plate 102, which facilitates the assembly of detection fixtures or temporary placement of workpieces on the operating platform.

[0040] When using the device designed in this application, the workpiece to be tested is first fixed between the upper fixture 501 and the lower fixture 502. After determining the size of the combined testing fixture, the lifting mechanism 400 is activated to raise the preload mechanism 300 to a suitable height. The testing fixture is then placed in the force sensor 504, and the excitation mechanism 200 is activated. Based on the signals from the force sensor 504 and the acceleration sensor 503, the dynamic stiffness of the workpiece to be tested can be calculated.

[0041] The embodiments of this utility model have been described in detail above, but this utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this utility model, and these variations still fall within the protection scope of this utility model.

Claims

1. A dynamic stiffness measuring device, characterized in that, include: A frame, an excitation mechanism connected to the bottom of the frame, a preload mechanism connected to the frame and disposed above the excitation mechanism, and a lifting mechanism connected to the frame for raising or lowering the preload mechanism. The lifting mechanism includes an upper lifting plate, a lower lifting plate, a plurality of first guide shafts passing through the upper lifting plate and the lower lifting plate, and a lifter connected to the lower lifting plate; the preload mechanism is disposed between the upper lifting plate and the lower lifting plate. The preload mechanism includes an upper connecting plate for the mass block, a lower connecting plate for the mass block, an inertial mass block fixed between the upper connecting plate for the mass block and the lower connecting plate for the mass block, and a plurality of second guide shafts passing through the upper connecting plate for the mass block and the lower connecting plate for the mass block; one end of the second guide shaft is connected to the lower lifting plate, and the other end is connected to the upper lifting plate; It also includes a force sensor and an acceleration sensor. One end of the force sensor is connected to the excitation mechanism and the other end is connected to the preload mechanism. The acceleration sensor is mounted on the vibration excitation mechanism.

2. The dynamic stiffness measuring device according to claim 1, characterized in that, The frame includes a bottom frame plate connected to each other, a top frame plate at the top, and a middle frame plate located between the bottom frame plate and the top frame plate; the excitation mechanism is disposed on the bottom frame plate, and the preload mechanism is disposed between the middle frame plate and the top frame plate.

3. The dynamic stiffness measuring device according to claim 2, characterized in that, The frame has a detection through hole on its plate, and the excitation mechanism passes through the detection through hole.

4. The dynamic stiffness measuring device according to claim 3, characterized in that, The excitation mechanism includes a support and a vibrator mounted on the support. The support is fixed to the base plate of the frame, and the vibrator partially passes through a detection through hole.

5. The dynamic stiffness measuring device according to claim 4, characterized in that, The vibrator is connected to the support via several first dampers.

6. The dynamic stiffness measuring device according to claim 2, characterized in that, It also includes a testing fixture for fixing the workpiece to be tested, the testing fixture comprising a lower fixture abutting against the excitation mechanism and an upper fixture abutting against the preload mechanism.

7. The dynamic stiffness measuring device according to claim 6, characterized in that, The lower lifting plate has a through hole, and the upper tooling abuts against the lower connecting plate of the mass block through the through hole.

8. The dynamic stiffness measuring device according to claim 2, characterized in that, The lifting device includes a motor mounted on the frame base plate and a lifting screw connected to the motor, the lifting screw being threadedly connected to the lower lifting plate.

9. The dynamic stiffness measuring device according to claim 8, characterized in that, The number of lifting screws is 2, and the motor drives the lifting screws through a split-drive and a reversing drive connected to both ends of the split-drive.

10. The dynamic stiffness measuring device according to claim 1, characterized in that, A second shock absorber is provided between the lower connecting plate of the mass block and the lower lifting plate.

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