Full-automatic high-precision pulse force hammer for test modal test

Abstract

The invention belongs to the field of machine tool performance testing, and particularly relates to a full-automatic high-precision pulse force hammer used for a test modal test. According to the technical scheme, the device comprises a rack module, a knocking execution module, a force adjusting module, a time interval adjusting module and a force measurement and point measurement feedback module, the knocking execution module, the force adjusting module, the time interval adjusting module and the force measurement and point measurement feedback module are installed on the rack module, and the knocking execution module is used for conducting knocking action; the strength adjusting module is used for determining the knocking strength before knocking is executed, the time interval adjusting module is used for determining the time length between two times of knocking before knocking is executed, and the force and point measuring feedback module is used for detecting the knocking execution strength and the knocking point position accuracy. According to the full-automatic high-precision pulse force hammer provided by the invention, the knocking force and the knocking interval can be accurately controlled, and the knocking force and the knocking point location are measured by adopting the force sensor and the laser measuring instrument so as to ensure the accuracy of the knocking result of the pulse force hammer.

Description

Technical Field

[0001] The invention belongs to the field of machine tool performance testing, and in particular relates to a fully automatic high-precision pulse force hammer for experimental modal testing. Background Art

[0002] The structural dynamic characteristics have an important impact on the stability of the system. So far, there are two commonly used methods for testing the structural dynamic characteristics. The first is the analytical method, that is, finite element analysis, which can obtain modal parameters such as natural frequency and modal vibration shape by geometrically establishing a finite element model, setting boundary conditions and material properties, etc.; the second is to determine the modal parameters of the system by measuring the frequency response function of the system.

[0003] The limitation of finite element analysis is that it is impossible to determine parameters such as the damping of the material. At the same time, due to the simplification of boundary conditions and models, it is difficult to establish a finite element model that accurately reflects the structural characteristics. Therefore, modal testing is required, and the results of finite element analysis calculations provide a reference for the arrangement of test points and the selection of excitation points in subsequent modal tests.

[0004] Modal testing technology is to measure the input and output signals of the structure through experiments, and measure its transfer function through data processing, so as to identify its modal parameters. There are two excitation methods: exciter excitation and hammer excitation. The exciter has the characteristics of being able to obtain a large force amplitude and frequency, but it may cause interference signals to the structural response when it contacts the structure. In summary, in order to obtain more accurate results, the hammer method is generally used in the test. The hammer method is a fast, simple and effective method that uses a "hammer" equipped with a force sensor to stimulate the test structure, with the help of modern testing technology and the fast Fourier transform of a microcomputer, as well as the pulse experiment principle and modal theory to quickly obtain the modal coefficients of the structure.

[0005] The existing manual pulse hammer, semi-automatic pulse hammer and fully automatic pulse hammer have disadvantages such as poor portability and high price, which limit the application of pulse hammer in specific occasions. Moreover, they are greatly affected by human control factors. When repeated excitation is performed, problems such as inaccurate striking position, unrepeatable force, and uncontrollable interval duration cannot be completely solved, resulting in poor repeatability of the excitation force pulse signal, thus affecting the test accuracy. Summary of the invention

[0006] The invention provides a fully automatic high-precision pulse force hammer for experimental modal testing. The striking force and striking interval can be accurately controlled. A force sensor and a laser measuring instrument are used to measure the striking force and striking point to ensure the accuracy of the striking result of the pulse force hammer.

[0007] The technical solution of the present invention is as follows: A fully automatic high-precision pulse force hammer for experimental modal testing comprises a rack module, a knocking execution module, a force adjustment module, a time interval adjustment module and a force measuring point feedback module. The knocking execution module, the force adjustment module, the time interval adjustment module and the force measuring point feedback module are installed on the rack module. The knocking execution module is used to perform a knocking action, the force adjustment module is used to determine the knocking force before executing the knocking, the time interval adjustment module is used to determine the time length between two knocks before executing the knocking, and the force measuring point feedback module is used to detect the force of the knocking execution and the accuracy of the knocking point.

[0008] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, the rack module includes a rack seat, a slider rack and an angle adjustment unit, and the rack seat and the slider rack are installed together through the angle adjustment unit.

[0009] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, the angle adjustment unit includes a gear transmission mechanism and a ratchet mechanism, the gear transmission mechanism includes a driving gear, a driving gear shaft, a driven gear and a driven gear shaft, the driving gear shaft and the driven gear shaft are rotatably connected to the frame seat through bearings, two driving gears are symmetrically fixed on the driving gear shaft, two driven gears are symmetrically fixed on the driven gear shaft and are respectively fixed on both sides of the tail of the slider frame, and the two driving gears are respectively meshed with the two driven gears; the ratchet mechanism includes a ratchet, a push rod and a pendulum block, the ratchet is fixedly mounted on the driving gear shaft and is located between the two driving gears, the push rod is fixedly mounted on the frame seat, the pendulum block is rotatably connected to the push rod through a pin, and the pendulum block is used to position the ratchet.

[0010] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, the striking execution module includes a parallelogram rod group, a lead rod, a slider, a stroke column and a cylinder, the head end of the parallelogram rod group is rotatably connected to the stroke column, the tail end of the parallelogram rod group is rotatably connected to the slider, and the slider is slidably connected to the slider frame; one end of the lead rod is rotatably connected to the head of the slider frame, the other end of the lead rod and the piston rod of the cylinder are rotatably connected to the middle part of the parallelogram rod group, and the cylinder body of the cylinder is rotatably connected to the frame seat.

[0011] Furthermore, in the fully automatic high-precision pulse force hammer for experimental modal testing, the force adjustment module includes a sleeve, a spring box, a force storage spring, a hammer head, an operating rod, an adjustment plate and a return spring, the sleeve is fixedly mounted on the head of the slider frame, the spring box is slidingly arranged in the sleeve, a plurality of force storage springs are placed in the spring box, and the hammer head is provided at the bottom of the spring box; the stroke column is sleeved on the operating rod, a return spring is provided between the operating rod and the stroke column, the adjustment plate is fixedly mounted on the end of the operating rod, and the adjustment plate is opposite to the force storage spring.

[0012] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, the stroke column is provided with a vertical cavity, the lower end of the vertical cavity is provided with an annular clamping platform, and the middle part of the vertical cavity is provided with three gear slots; the middle part of the operating rod is provided with an annular boss, and the annular boss is provided with a gear clamping block; the return spring is arranged between the annular clamping platform and the annular boss; five force storage springs are placed in the spring box, one of which is arranged at the center of the spring box, and the other four force storage springs are arranged in parallel in pairs and symmetrically distributed on both sides of the force storage spring located at the center; the baffle plate is in a bow tie shape, and by rotating the operating rod, the baffle plate is respectively opposite to: one force storage spring, three force storage springs or five force storage springs; the gear clamping blocks respectively enter the three gear slots to realize the gear fixation of the operating rod.

[0013] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, the time interval adjustment module includes a motor, a cam, a camshaft, a rocker arm and a rocker arm shaft, the motor is fixedly mounted on the frame seat, the camshaft is rotatably connected to the frame seat, the cam is fixedly mounted on the camshaft, and the output end of the motor is connected to the camshaft through a flange; the two ends of the rocker arm are respectively a U-shaped end and an I-shaped end, and the rocker arm is fixedly mounted on the rocker arm shaft; arc-shaped sliding grooves are respectively provided on both sides of the frame seat, the two ends of the rocker arm shaft are respectively placed in the two sliding grooves, and a nut is installed on the part of the rocker arm shaft exposed from the frame seat to lock it in place; the U-shaped end of the rocker arm is installed at the bottom of the spring box, and the I-shaped end of the rocker arm is installed tangentially with the cam.

[0014] Furthermore, in the fully automatic high-precision pulse force hammer for experimental modal testing, the force measurement point feedback module includes a force sensor, a laser measuring instrument and a display, the force sensor is installed on the hammer head, the laser measuring instrument is installed on the slider frame, and the force sensor and the laser measuring instrument are connected to the display via a data cable.

[0015] Furthermore, in the fully automatic high-precision pulse hammer for experimental modal testing, a limiting structure is provided on the slider frame, and the limiting structure enables the spring box to move axially below the lowest end surface of the slider frame.

[0016] The beneficial effects of the present invention are as follows: the fully automatic high-precision pulse force hammer for experimental modal testing provided by the present invention can accurately control the force and interval of the knocking, and use a force sensor and a laser measuring instrument to measure the force and point of the knocking to ensure the accuracy of the knocking result of the pulse force hammer. The present invention can improve the test efficiency and reduce the time and cost of manual operation. Since the present invention has high precision and high reliability, the cost of repeated testing can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a fully automatic high-precision impulse hammer used for experimental modal testing; Figure 2 This is a schematic diagram of the rack module; Figure 3 is a schematic diagram of an angle adjustment unit; Figure 4 This is a schematic diagram of the tapping execution module; Figure 5 This is a schematic diagram of the assembly of the operating lever, baffle plate and travel column; Figure 6 Assemble the cross-section view of the operating lever and the travel column; Figure 7 It is a schematic diagram of the time interval adjustment module; Figure 8 is a schematic diagram of a pendulum; Fig. 9 This is a schematic diagram of the state of the force storage spring installed in the spring box. DETAILED DESCRIPTION

[0018] like Figure 1-9 As shown, a fully automatic high-precision pulse force hammer for experimental modal testing includes a rack module, a knocking execution module, a force adjustment module, a time interval adjustment module and a force measuring point feedback module. The knocking execution module, the force adjustment module, the time interval adjustment module and the force measuring point feedback module are installed on the rack module. The knocking execution module is used to perform knocking actions, the force adjustment module is used to determine the knocking force before executing the knocking, the time interval adjustment module is used to determine the time length between two knocks before executing the knocking, and the force measuring point feedback module is used to detect the force of the knocking execution and the accuracy of the knocking point.

[0019] The rack module includes a rack seat 1, a slider rack 2 and an angle adjustment unit, wherein the rack seat 1 and the slider rack 2 are installed together through the angle adjustment unit. The angle adjustment unit includes a gear transmission mechanism and a ratchet mechanism, wherein the gear transmission mechanism includes a driving gear 13, a driving gear shaft 14, a driven gear 15 and a driven gear shaft, wherein the driving gear shaft 14 and the driven gear shaft are rotatably connected to the rack seat 1 through a bearing, wherein two driving gears 13 are symmetrically fixedly mounted on the driving gear shaft 14, and two driven gears 15 are symmetrically fixedly mounted on the driven gear shaft and are respectively fixedly mounted on both sides of the tail of the slider rack 2, and the two driving gears 13 are respectively meshed with the two driven gears 15; the ratchet mechanism includes a ratchet 16, a push rod 10 and a pendulum block 11, wherein the ratchet 16 is fixedly mounted on the driving gear shaft 14 and is located between the two driving gears 13, the push rod 10 is fixedly mounted on the rack seat 1, and the pendulum block 11 is rotatably connected to the push rod 10 through a pin, and the pendulum block 11 is used to position the ratchet 16. The push rod 10 and the pendulum block 11 can make the ratchet 16 rotate to a specified angle and then get stuck, so as to adjust and fix the knocking angle; the pendulum block 11 and the push rod 10 can realize relative rotation, and the pendulum block 11 is swung to the other side of the push rod 10 for manual reversal, so that the ratchet 16 can realize reverse rotation to a specified angle and then get stuck, so as to achieve the purpose of reverse adjustment of the angle.

[0020] The knocking execution module includes a parallelogram rod group 3, a lead rod 17, a slider 27, a stroke column 4 and a cylinder 5. The head end of the parallelogram rod group 3 is rotatably connected to the stroke column 4, the tail end of the parallelogram rod group 3 is rotatably connected to the slider 27, and the slider 27 is slidably connected to the slider frame 2; one end of the lead rod 17 is rotatably connected to the head of the slider frame 2, the other end of the lead rod 17 and the piston rod 18 of the cylinder 5 are rotatably connected to the middle part of the parallelogram rod group 3, and the cylinder body of the cylinder 5 is rotatably connected to the frame seat 1.

[0021] The force adjustment module includes a sleeve 6, a spring box 25, a force storage spring 26, a hammer 7, an operating rod 8, an adjustment plate 19 and a return spring 20. The sleeve 6 is fixedly mounted on the head of the slider frame 2, the spring box 25 is slidably arranged in the sleeve 6, and the hammer 7 is provided at the bottom of the spring box 25; the travel column 4 is sleeved on the operating rod 8, and the adjustment plate 19 is fixedly mounted on the end of the operating rod 8; the travel column 4 is provided with a vertical cavity, the lower end of the vertical cavity is provided with an annular clamping platform, and the middle part of the vertical cavity is provided with three gear clamping grooves; the middle part of the operating rod 8 is provided with an annular boss, and the annular boss is provided with a gear clamping block; the return spring 20 is provided with a spring 25, and the spring 25 is provided with a spring 26, and the spring 26 is provided with a spring 26; the spring 25 is provided with a spring 26, and the spring 26 is provided with a spring 26; the spring 25 is provided with a spring 26, and the spring 26 is provided with a spring 26; the spring 25 is provided with a spring 26, and the spring 26 is provided with a spring 26; the spring 26 ... The spring 20 is arranged between the annular clamping platform and the annular boss; five force storage springs 26 are placed in the spring box 25, one of which is arranged at the center of the spring box 25, and the other four force storage springs 26 are arranged in pairs and symmetrically distributed on both sides of the force storage spring 26 at the center; the baffle plate 19 is in a bow-tie shape, and the baffle plate 19 faces the force storage spring 26. By rotating the operating rod 8 to enter three gears respectively, the baffle plate 19 faces: one force storage spring 26, three force storage springs 26 or five force storage springs 26; the gear blocks enter the three gear slots respectively to realize the gear fixation of the operating rod 8. A limiting structure is provided on the slider frame 2, and the limiting structure enables the spring box 25 to move axially below the lowest end surface of the slider frame 2.

[0022] The time interval adjustment module includes a motor 21, a cam 22, a camshaft 23, a rocker rod 9 and a rocker rod shaft 24, wherein the motor 21 is fixedly mounted on the frame seat 1, the camshaft 23 is rotatably connected to the frame seat 1, the cam 22 is fixedly mounted on the camshaft 23, and the output end of the motor 21 is connected to the camshaft 23 through a flange; the two ends of the rocker rod 9 are respectively a U-shaped end and an I-shaped end, and the rocker rod 9 is fixedly mounted on the rocker rod shaft 24; arc-shaped sliding grooves 12 are respectively provided on both sides of the frame seat 1, the two ends of the rocker rod shaft 24 are respectively placed in the two sliding grooves 12, and a nut is installed on the part of the rocker rod shaft 24 exposed from the frame seat 1 to lock it in place; the U-shaped end of the rocker rod 9 is mounted at the bottom of the spring box 25, and the I-shaped end of the rocker rod 9 is installed tangentially with the cam 22.

[0023] The force measurement point feedback module includes a force sensor, a laser measuring instrument and a display. The force sensor is installed on the hammer head 7, the laser measuring instrument is installed on the slider frame 2, and the force sensor and the laser measuring instrument are connected to the display via a data line.

[0024] The working process is as follows: 1. Manually operate the ratchet 16 to rotate to the specified angle, and the push rod 10 and the pendulum block 11 will clamp the ratchet 16 to adjust and fix the striking angle; this operation must be performed when installing the product and will not affect the subsequent automatic operation of the pulse hammer; 2. By rotating the operating lever 8 into three gear positions, the baffle plate 19 is respectively opposite to: one force storage spring 26, three force storage springs 26 or five force storage springs 26 to determine the force of the knocking; the force generated by the force storage spring 26 being fully compressed and restored at the same time is the force of the knocking; the force storage spring 26 provides a buffering capacity for the subsequent knocking of the force hammer to better control the force and make the knocking process more stable; 3. The time length between two taps is determined by controlling the switch and rotation speed of the motor 21 to realize the intermittent adjustment function; 4. The U-shaped end of the swing rod 9 is against the bottom of the spring box 25; the cylinder 5 is used for stroke driving, and the parallelogram rod group 3 and the lead rod 17 are limited, so that the stroke column 4 is translated downward to compress the force storage spring 26 to store force, so as to prepare for the subsequent ejection of the hammer body 7; the slider 27 is limited by the slider frame 2, and can only be translated along the straight line where the longest dimension line of the slider frame 2 is located. The cylinder 5 controls the lead rod 17 to rotate, so that the stroke column 4 is accurately translated along the straight line, and is always in a coaxial state with the spring box 25 and the sleeve 6, without interference; 5. When the force storage spring 26 is in a fully compressed state, the initial position of the cam 22 is the position where the swing rod 9 and the cam 22 are tangent to each other and are located at the maximum stroke of the cam. The motor 21 drives the cam 22 to rotate, so that the swing rod 9 suddenly leaves the maximum stroke of the cam and loses its supporting force, so that the connection between the hammer head 7 and the spring box 25 is instantly ejected under the elastic force of the fully compressed force storage spring 26, completing the knocking action; at the same time, the swing rod 9 swings and descends along the sliding slot 12; 6. The cylinder 5 drives the parallelogram rod group 3 and the lead rod to move so that the travel column 4 moves upward, preparing for compressing the storage spring 26; 7. The motor 21 drives the cam 22 to continue to rotate, driving the swing rod 9 to gradually swing upward. At this time, the U-shaped end of the swing rod 9 also pushes the spring box 25 to move upward, and the hammer head 7 also moves upward to achieve the effect of retraction; One rotation of the cam 22 is one stroke for the hammer head 7 to pop out and retract, and at the same time, the possibility of a second strike due to inertia is effectively avoided; 8. The force measurement point feedback module is used to detect whether the force and the knocking point of the knocking are accurate to ensure the accuracy and effectiveness of the knocking; the laser measuring instrument is installed on the slider frame 2 to facilitate the measurement of the deviation between the knocking point and the initial setting point; 9. Continue to perform steps 4-8 to complete the tapping work.

Claims

1. A fully automatic high-precision impulse hammer for experimental modal testing, characterized in that: It includes a rack module, a knocking execution module, a force adjustment module, a time interval adjustment module and a force measuring point feedback module. The knocking execution module, the force adjustment module, the time interval adjustment module and the force measuring point feedback module are installed on the rack module. The knocking execution module is used to perform knocking actions, the force adjustment module is used to determine the knocking force before executing the knocking, the time interval adjustment module is used to determine the length of time between two knocks before executing the knocking, and the force measuring point feedback module is used to detect the force of the knocking execution and the accuracy of the knocking point.

2. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 1 is characterized in that: The rack module comprises a rack seat, a slider rack and an angle adjustment unit, and the rack seat and the slider rack are installed together through the angle adjustment unit.

3. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 2 is characterized in that: The angle adjustment unit includes a gear transmission mechanism and a ratchet mechanism. The gear transmission mechanism includes a driving gear, a driving gear shaft, a driven gear and a driven gear shaft. The driving gear shaft and the driven gear shaft are rotatably connected to the frame seat through bearings. Two driving gears are symmetrically fixed on the driving gear shaft. Two driven gears are symmetrically fixed on the driven gear shaft and are respectively fixed on both sides of the tail of the slider frame. The two driving gears are respectively meshed with the two driven gears; the ratchet mechanism includes a ratchet, a push rod and a pendulum block. The ratchet is fixedly mounted on the driving gear shaft and is located between the two driving gears. The push rod is fixedly mounted on the frame seat. The pendulum block is rotatably connected to the push rod through a pin, and the pendulum block is used to position the ratchet.

4. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 2 is characterized in that: The knocking execution module includes a parallelogram rod group, a lead rod, a slider, a stroke column and a cylinder. The head end of the parallelogram rod group is rotatably connected to the stroke column, the tail end of the parallelogram rod group is rotatably connected to the slider, and the slider is slidably connected to the slider frame; one end of the lead rod is rotatably connected to the head of the slider frame, the other end of the lead rod and the piston rod of the cylinder are rotatably connected to the middle part of the parallelogram rod group, and the cylinder body of the cylinder is rotatably connected to the frame seat.

5. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 4 is characterized in that: The force adjustment module includes a sleeve, a spring box, a force storage spring, a hammer, an operating rod, an adjustment plate and a return spring. The sleeve is fixedly mounted on the head of the slider frame, the spring box is slidably arranged in the sleeve, a plurality of force storage springs are placed in the spring box, and the hammer is provided at the bottom of the spring box; the travel column is sleeved on the operating rod, a return spring is provided between the operating rod and the travel column, the adjustment plate is fixedly mounted on the end of the operating rod, and the adjustment plate faces the force storage spring.

6. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 5, characterized in that: The stroke column is provided with a vertical cavity, the lower end of the vertical cavity is provided with an annular clamping platform, and the middle part of the vertical cavity is provided with three gear clamping slots; the middle part of the operating rod is provided with an annular boss, and the annular boss is provided with a gear clamping block; the return spring is arranged between the annular clamping platform and the annular boss; five force storage springs are placed in the spring box, one of which is arranged at the center of the spring box, and the other four force storage springs are arranged in parallel in pairs and symmetrically distributed on both sides of the force storage spring located at the center; the baffle plate is in a bow tie shape, and by rotating the operating rod, the baffle plate is respectively opposite to: one force storage spring, three force storage springs or five force storage springs; the gear clamping blocks respectively enter the three gear clamping slots to realize the gear fixation of the operating rod.

7. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 5, characterized in that: The time interval adjustment module includes a motor, a cam, a camshaft, a rocker arm and a rocker arm shaft. The motor is fixedly mounted on the frame seat, the camshaft is rotatably connected to the frame seat, the cam is fixedly mounted on the camshaft, and the output end of the motor is connected to the camshaft through a flange; the two ends of the rocker arm are respectively a U-shaped end and an I-shaped end, and the rocker arm is fixedly mounted on the rocker arm shaft; arc-shaped sliding grooves are respectively provided on both sides of the frame seat, the two ends of the rocker arm shaft are respectively placed in the two sliding grooves, and a nut is installed on the part of the rocker arm shaft exposed from the frame seat to lock it in place; the U-shaped end of the rocker arm is installed at the bottom of the spring box, and the I-shaped end of the rocker arm is installed tangentially with the cam.

8. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 5, characterized in that: The force measurement point feedback module includes a force sensor, a laser measuring instrument and a display. The force sensor is installed on the hammer head, the laser measuring instrument is installed on the slider frame, and the force sensor and the laser measuring instrument are connected to the display via a data line.

9. The fully automatic high-precision impulse hammer for experimental modal testing according to claim 5, characterized in that: The slider frame is provided with a limiting structure, and the limiting structure enables the spring box to move axially below the lowest end surface of the slider frame.

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