A high-precision device for measuring the minute inertia product of a precision assembly

Abstract

The present application relates to a kind of high-precision devices for measuring the small inertia product of precision assembly, belong to the field of measurement technology.The main purpose of the present application is to meet the needs of the small inertia product test of small mass and small volume precision assembly;The device includes three parts from top to bottom, measurement device, signal processing device and driving device, by measuring the torque generated by the inertia product of high-speed rotating excitation object, directly measure the inertia product of object, measurement link is direct, avoid introducing other errors.The structure of the whole device is designed, installation and removal are convenient, test procedure is simple, test efficiency is high, and by replacing clamping tool, a variety of components can be measured, and the reusability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of high-precision device for measuring the small inertia product of precision assembly, belong to measurement technical field. BACKGROUND

[0002] Rotational inertia, inertia product (also known as inertia product) and centroid position all belong to the inertia parameters of object. Whether in mechanical design or in the dynamics analysis of object, inertia parameters are important physical quantities of object. In theory, the inertia parameters of any object can be obtained by establishing its three-dimensional model through three-dimensional physical configuration software and numerical calculation, but in actual engineering, because the structure of assembly is complex, it is difficult to accurately consider all design details that affect the measured object during modeling, and the accuracy of inertia parameter identification result cannot be guaranteed, so accurate inertia parameters need to be obtained through experimental test method. Compared with rotational inertia, inertia product is smaller in order of magnitude and more difficult to measure.

[0003] In existing published patent documents, inertia product measurement technology mainly targets heavy mass and large volume instruments and equipment, and the main method is to indirectly calculate the inertia product of the object by first measuring the rotational inertia and then using the mathematical relationship between rotational inertia and inertia product. The operation steps and measurement parameters are more, and there are more error introduction links. The present application proposes a high-precision inertia product direct measurement device for the inertia product measurement technology demand of small mass and small volume precision assembly. SUMMARY

[0004] The main purpose of the present application is to provide a high-precision device for measuring the small inertia product of precision assembly for the small mass and small volume precision assembly small inertia product test demand, which directly measures the inertia product of the object by measuring the torque generated by the high-speed rotating excitation inertia product of the object, and avoids introducing other errors. The structure of the whole device is designed for convenient installation and disassembly, simple test steps, high test efficiency, and can measure various components by replacing the clamping tool, with high reusability.

[0005] To achieve the above purpose, the present application mainly provides the following technical scheme:

[0006] A high-precision device for measuring the small inertia product of precision assembly includes a measurement device, a signal processing device and a driving device from top to bottom;

[0007] The measurement device mainly includes a calibration workpiece, a pressure sensor, a positioning plate, a positioning pin, a clamping frame and a clamping bottom plate.

[0008] The clamping frame is vertically symmetrical and fixed above the clamping bottom plate, the pressure sensor measures the pressure generated at both ends of the calibration workpiece during the measurement process and fixes the workpiece, and the positioning pin and the positioning plate fix the attitude of the calibration workpiece.

[0009] The signal processing device mainly comprises a shell, an industrial control mainboard, a data acquisition card and a lithium battery module.

[0010] The industrial control mainboard, the data acquisition card and the lithium battery module are all installed on the shell, the shell is used for fixing the equipment, the industrial control mainboard is used for recording and processing data, the data acquisition card is used for acquiring data signals in the measurement process, and the lithium battery module is used for power supply.

[0011] The driving device mainly comprises a rotary table for providing high-speed rotation required for measurement.

[0012] The calibration workpiece is an aluminum cylindrical part with openings at both ends, has multiple, and is machined to cut part of the surface, so as to have a human-set inertia product, and mainly functions to calibrate the pressure and torque of the whole device.

[0013] The pressure sensor is a long strip-shaped piezoresistive sensor with threads at both ends, the threads are used to fix the sensor in the clamping tool, each two sensors form a pair, clamp one end of the workpiece to be tested, and a total of two pairs of four pressure sensors completely clamp the workpiece.

[0014] The clamping frame is a long rectangular part with a hollow in the middle and a positioning pin hole, the hollow width is determined according to the size of the measured workpiece, and is used to limit the position of the workpiece and prevent the workpiece from flying out during the measurement process, the inside of the long rectangular object after hollowing has threaded holes at both upper and lower ends, which are used to fix the pressure sensor and wiring, and the outside also has threaded holes, which are used to connect the clamping base;

[0015] The clamping base is a long rectangular part with threaded holes on the surface, which is used to fix the clamping frame and fix the whole tooling on the shell;

[0016] The positioning plate is an aluminum part with a convex groove and a positioning pin hole, which cooperates with the pin hole on the clamping frame through the positioning pin, and positions the calibration workpiece and the real measurement assembly in the clamping tool;

[0017] The data acquisition card is a synchronous acquisition card with 4 input ports, 1 output port and 1 power interface, each input port has a resolution of 24 bits, the sampling rate is up to 215KSPS, and the data line is connected with the data line of the four pressure sensors; the output port is a USB bus port, which is connected with the interface on the industrial control mainboard through the USB data line; the power interface is connected with the lithium battery module through the wire;

[0018] The industrial control mainboard is a small host computer capable of running win10 system, which has a program with corresponding data recording and data analysis functions, has a USB interface, is connected with the data acquisition card through the USB data line, and is connected with the lithium battery module through the wire.

[0019] The lithium battery module is a mobile power supply for supplying power to the test equipment except the turntable, and is mainly connected with the power supply interfaces of various components through wires;

[0020] The shell is three aluminum plates fixed by hexagonal copper columns and bolts, and mainly functions to place the data acquisition card, the industrial control mainboard and the lithium battery module;

[0021] The turntable is a driving device for rotating the table top by a motor, and has a grating disc inside for speed feedback, which can read the rotating speed of the turntable, and the above-mentioned measuring device and signal processing device are installed on the table top of the turntable;

[0022] As preferred, in order to improve the accuracy of signal acquisition, the data acquisition card with high resolution and sampling rate is selected to acquire signals, and the signal is processed through the industrial control mainboard, or a single-chip microcomputer combined with a data acquisition circuit is used to realize the signal acquisition and processing functions;

[0023] As preferred, in order to improve the measurement accuracy of the whole device and the installation convenience, the piezoresistive sensor with threads and a certain structural rigidity is selected, or a flexible sensor with a rigid structure is used, or a piezoelectric sensor, a strain sensor and a capacitive sensor and other types of pressure sensors are used instead of the existing piezoresistive sensor;

[0024] As preferred, in order to simplify the structure, the rate of the grating disc in the turntable is used as the angular velocity, or an angular velocity measuring device is separately arranged on the table top of the turntable to measure the angular velocity of the turntable in real time;

[0025] The method for measuring the inertia product of the device is that first, the pressure sensor and the whole device are calibrated by a calibration workpiece; then, the test workpiece is fixed by the clamping tool and the pressure sensor, the turntable drives the clamping tool to rotate, and then drives the test workpiece to rotate together, the length of the workpiece is taken as the force arm, so that the torque excited by the inertia product is converted into pressure, which is recognized by the pressure sensors at both ends of the workpiece; the signals generated on the pressure sensor are acquired by the data acquisition card, and after processing, are uploaded to the industrial control mainboard for storage and analysis, and then according to the rotating speed information of the turntable, the inertia product of the test workpiece is directly obtained.

[0026] Advantages

[0027] 1. The present application is designed for small and precise components, and the torque excited by the inertia product due to rotation on the component is measured by the pressure sensor, so that the number of force transmission links and measurement parameters is small, the measurement method is direct, the errors introduced in the test links can be effectively reduced, and the measurement accuracy is improved;

[0028] 2、The present application calibrates the whole device by the high-precision machined calibration workpiece, compensates system error, and improves the measurement precision;

[0029] 3、The present application has simple installation mode, few steps, convenient measurement, can avoid damage of precision components caused by too complicated disassembly and assembly, and improves efficiency, can measure various components by replacing the clamping tool, and has high reusability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the rotary balance method;

[0031] Figure 2 is a schematic diagram of the whole device;

[0032] Figure 3 is a three-view diagram of the measuring device;

[0033] Figure 4 is a schematic diagram of the measuring device;

[0034] Figure 5 is an exploded view of the measuring device;

[0035] Figure 6 is a schematic diagram of multiple calibration workpieces;

[0036] Figure 7 is a three-view diagram of the signal processing device;

[0037] Figure 8 is a schematic diagram of the signal processing device;

[0038] Figure 9 is an exploded view of the signal processing device;

[0039] Figure 10 is a schematic diagram of the wiring of main equipment;

[0040] Figure 11 is a cross-sectional view in the clamped state.

[0041] Wherein: 1-measuring device, 11-calibration workpiece, 12-pressure sensor, 13-positioning plate, 14-positioning pin, 15-clamping frame, 16-clamping bottom plate, 17-fixing bolt; 2-industrial control mainboard, 3-housing, 31-housing top plate, 32-housing middle plate, 33-housing bottom plate, 34-mainboard fixing bolt, 35-long hexagonal copper column and bolt, 36-short hexagonal copper column and bolt, 37-acquisition card fixing bolt; 4-data acquisition card, 5-rotary table, 6-lithium battery module; DETAILED DESCRIPTION

[0042] In order to enable personnel in the technical field to better understand the present application scheme, the measurement principle, structure and working mode of the present application will be clearly and completely described below in combination with the drawings.

[0043] The measurement principle of this invention is based on the rotational balance method, such as... Figure 1 As shown, for any rigid body rotating about a fixed point O, its inertia tensor can be expressed in matrix form as follows:

[0044]

[0045] When a rigid body rotates stably about only one axis, the angular velocity acting on the rigid body's base is ω(t) = [0 0 ω z (t)] T Through Euler's dynamic equations

[0046]

[0047] The dynamic relationships of various physical quantities on the integral basis when a rigid body rotates are as follows:

[0048]

[0049] When a rigid body rotates about a fixed axis with a constant angular velocity around a connected base passing through point O, the product of inertia J caused by the simultaneous mass asymmetry of the rigid body relative to both the xOy and xOz planes of the connected base is... Oyz It can then be calculated using the following formula by measuring the torque about the x-axis and the angular velocity of rotation about the z-axis.

[0050] M x =J Oyz ω z 2 (4)

[0051] This invention utilizes torque conversion to directly fix the object being measured using a pressure sensor, thereby converting M... x The measurement is converted into a pressure F measurement through the lever arm L between the pressure sensors, and the calculation formula becomes...

[0052]

[0053]

[0054] The measurement error is caused only by the pressure sensor error and the turntable speed error. Furthermore, there are fewer force transmission links, fewer measurement parameters, and a direct measurement method, which avoids the errors introduced by other force transmission processes and achieves high-precision measurement.

[0055] The structural diagram of this embodiment is shown below. Figure 2As shown, including measuring device 1, industrial control mainboard 2, shell 3, data acquisition card 4, rotary table 5, lithium battery module 6, measuring device 1 is installed on the shell 3 by bolt connection, the shell is installed on the rotary table 5 by bolt connection, when the measuring assembly needs to be replaced, only the bolt is loosened, the measuring device 1 can be removed, the installation mode is simple, the steps are few, and the operation is convenient.

[0056] The specific structure of the measuring device 1 is as shown in Figure 2 、 Figure 3 and Figure 4 The measuring device 1 is composed of a calibration workpiece 11, a pressure sensor 12, a positioning plate 13, a positioning pin 14, a clamping frame 15, a clamping bottom plate 16 and a fixing bolt 17. As shown in Figure 6 , the whole is a simple cylindrical shape convenient for machining, and notches are machined at both ends of the cylinder for positioning the attitude of the workpiece; a groove symmetrical to the center of the rotating shaft is machined on the cylindrical surface for setting the inertia product size, different machining depths obtain different orders of magnitude of the inertia product, and except the groove, symmetrical machining is performed, the purpose is to ensure that the calibration workpiece 11 has only one inertia product. The pressure sensor 12 is a long strip-shaped piezoresistive sensor with threads at both ends, the threads are used to fix the sensor in the clamping tool, each two pressure sensors 12 form a pair, clamping one end of the tested workpiece, a total of two pairs of four pressure sensors 12 completely clamp the workpiece; the range of the pressure sensor 12 is 20N, the accuracy is 1 / 3000, the verification graduation value is 0.006N, cooperating with the clamping distance between the pressure sensors 12, the smallest measurable torque is 1.43x10 -4 Nm. The positioning plate 13 is an aluminum part with a convex groove and two positioning pin holes, the width of the convex groove is the same as the width of the notches at both ends of the calibration workpiece 11, and the positioning plate 13 is fixed on the clamping frame 15 through the positioning pin 14 and the positioning pin hole, so that the calibration workpiece 11 is fixed by the pressure sensor 12 according to the set attitude. The clamping frame 15 is a long rectangular cuboid part with a hollow middle part and two positioning pin holes and four M4 threaded holes, the hollow middle part is mainly used to limit the position of the workpiece and prevent the workpiece from flying out during the measurement process, the long rectangular object after being hollow has two M4 threaded holes at the upper and lower ends, which are used to fix the pressure sensor 12 and the wiring, and the outer side also has threaded holes at the top and bottom. The clamping bottom plate 16 is an aluminum rectangular cuboid part, the surface has four M4 countersunk threaded holes, two M5 through holes and two M3 countersunk threaded holes, the clamping frame 15 is fixed through the fixing bolt 17, and the measuring device 1 is fixed on the shell 3 through bolt connection.

[0057] The specific structure of the signal processing device is as shown in Figure 7 、 Figure 8 and Figure 9As shown, it is composed of industrial control mainboard 2, shell 3, data acquisition card 4 and lithium battery module 6. The industrial control mainboard 2 is a small host computer capable of running win10 system, with built-in data recording and data analysis function program, USB bus interface, can obtain the signal collected by the data acquisition card 4 through the USB data line, and is connected with the lithium battery module 6 through the power line. The data acquisition card 4 is a high-precision synchronous acquisition card with 4 input ports, 1 output port and 1 power interface. Each input port has 24 bit resolution, the highest sampling rate is 215KSPS, and the data line is connected with the data line of 4 pressure sensors; the output port is a USB bus port, which is connected with the interface on the industrial control mainboard 2 through USB data line; the power interface is connected with the lithium battery module 6 through wire. The shell 3 is composed of shell top plate 31, shell middle plate 32, shell bottom plate 33, mainboard fixing bolt 34, long hexagonal copper column and bolt 35, short hexagonal copper column and bolt 36, and acquisition card fixing bolt 37. The shell top plate 31, shell middle plate 32 and shell bottom plate 33 are all octagonal aluminum plates. The shell top plate 31 has two M3 threaded holes, four M5 through holes and a cable tie hole. The shell middle plate 32 has four M3 through holes and eight M5 through holes. The shell bottom plate 33 has eight M5 threaded holes and four M5 countersunk holes. The long hexagonal copper column and bolt 35 and the short hexagonal copper column and bolt 36 are fasteners with M5 threads and threaded holes, four in a group, connecting the shell top plate 31, shell middle plate 32 and shell bottom plate 33 into a whole shell 3. The difference between the two groups is the height, which depends on the height of the industrial control mainboard 2 and the data acquisition card 4. The mainboard fixing bolt 34 is a fastener with M2.5 thread, four in a group, fixing the industrial control mainboard 2 on the shell 3. The acquisition card fixing bolt 37 is a fastener with M5 thread, four in a group, fixing the data acquisition card 4 on the shell 3. The lithium battery module 6 is a mobile power supply, which is fixed on the shell top plate 31 by cable tie, mainly providing power for the equipment installed on the turntable 5.

[0058] The driving device is mainly the turntable 5. In order to keep the turntable 5 stable rotation and reduce the interference of eccentric moment, the measuring device 1, the industrial control mainboard 2, the data acquisition card 4 and the shell 3 are installed so that their centers of gravity pass through the rotating shaft of the turntable 5, and the lithium battery module 6 is symmetrically installed relative to the rotating shaft. The measuring device 1 is designed so that the rotating shaft of the turntable can pass through the geometric center of the calibration workpiece 1 and the measured real workpiece. The lowest rotating speed of the turntable 5 is set to 1500rpm (157rad / s), which can realize the measurement of inertia product in the order of 10 -9 kgm 2 .

[0059] The wiring diagram of the whole device is as follows Figure 10As shown, the cable of the tail of the pressure sensor 12 is led out through the aperture outside the clamping frame 15, and the signal line is connected with the input port of the data acquisition card 4; the industrial control mainboard 2 is connected with the data acquisition card 4 through the USB data line; and the power lines of the pressure sensor 12, the industrial control mainboard 2 and the data acquisition card 4 are connected with the lithium battery module 6.

[0060] The working method of the present example is divided into the following steps:

[0061] First step: first install and deploy the entire device.

[0062] Place the entire device on a horizontal plane, and level the table surface of the turntable 5. After leveling, connect the cables between all the devices on the table surface of the turntable 5, and turn on the data acquisition card 4 and the industrial control mainboard 2 for preheating. At this time, the industrial control mainboard 2 is externally connected with a display. Remove the measuring device 1, slowly twist the two pressure sensors 12 above the clamping frame 8, so that the gap between them is greater than the circumferential diameter of the port of the calibration workpiece 11, remove a clamping frame 15, place the calibration workpiece 11 with no inertia accumulation, install the clamping frame 15 back, and install the measuring device 1 back on the shell 3. Adjust the posture of the calibration workpiece 11 through the positioning plate 13 and the positioning pin 14, and slowly twist the pressure sensors 12 in the opposite direction to clamp the calibration workpiece 11. The pressure sensor 12 below always remains in the twisted state, and the purpose is to ensure that the long-end axis of the calibration workpiece 11 is parallel to the horizontal plane.

[0063] Second step: calibrate the pressure sensor 12.

[0064] After fixing the calibration workpiece 11, connect the pressure sensor 12, read the analog signal output by the pressure sensor 12 through the data acquisition card 4, convert it into a digital signal, and then transmit it to the industrial control mainboard 2. Through the built-in program in the industrial control mainboard 2, display the pressure data on the display. According to the pressure data, compare it with the actual weight of the calibration workpiece 11, and calibrate the pressure sensor 12.

[0065] Third step: determine the overall accuracy.

[0066] After calibrating the pressure sensor 12, open the acquisition program in the industrial control mainboard 2, remove the display, start the turntable, and set the rotation speed of the turntable to a constant value ω. After the turntable rotates stably for a period of time, stop the turntable, connect the display to the industrial control mainboard 2 again, and read the data of the four pressure sensors 12 of the clamping calibration workpiece 11 without inertia accumulation under the rotation speed ω when the turntable rotates stably. According to the data of the pressure sensor 12 and the rotation speed ω of the turntable 5, calculate the inertia accumulation of the calibration workpiece 11. The calculation principle is as follows: Figure 11 As shown, the length of the workpiece itself is used as the force arm, and the torque generated by the inertia accumulation of the rotating excited object is converted into the pressure at both ends of the workpiece. At this time, the torque can be represented as L is the distance between the two clamping sections, F is the maximum pressure difference measured by the pressure sensor 12, and the inertia product of the entire calibration workpiece 11 is represented as The inertia product measured at this time is the system error compensation amount ΔJ, and the size of ΔJ reflects the accuracy of the entire device.

[0067] Step 4: Calibrate the entire device.

[0068] Remove the inertia-free calibration workpiece 11, install the calibration workpiece 11 with a set inertia product of J1, start the turntable 5, set the rotation speed to ω, and repeat steps 1, 2, and 3 to measure the inertia product, denoted as J1', and determine the calibration coefficient of the entire device as

[0069] Step 4: Measure the real component.

[0070] Replace the calibration workpiece 11 with the real component that needs to be measured, and repeat steps 1, 2, and 3 to measure the inertia product, denoted as J2', and the real inertia product of the component can be represented as

[0071] The above detailed description further explains the purpose, technical solutions, and benefits of the invention. It should be understood that the above description is only a specific embodiment of the invention and does not limit the protection scope of the invention. Any modifications, substitutions, equivalent replacements, improvements, etc. within the spirit and principles of the invention should be included in the protection scope of the invention.

Claims

1. A high-precision device for measuring the micro-inertia product of precision components, characterized in that: From top to bottom, it includes three parts of measuring device, signal processing device and driving device; The measuring device mainly includes: calibration workpiece, pressure sensor, positioning plate, positioning pin, clamping frame and clamping bottom plate; The clamping frame is vertically symmetrical fixed above the clamping bottom plate, the pressure sensor measures the pressure generated by the calibration workpiece at both ends during the measurement and fixes the workpiece, and the positioning pin and the positioning plate fix the posture of the calibration workpiece; The signal processing device mainly includes: shell, industrial control mainboard, data acquisition card and lithium battery module; The industrial control mainboard, data acquisition card and lithium battery module are all installed on the shell, the shell is used to fix the equipment, the industrial control mainboard is used to record and process data, the data acquisition card is used to collect data signals during the measurement, and the lithium battery module is used for power supply; The driving device mainly includes a turntable for providing high-speed rotation required for measurement.

2. A high-precision device for measuring the minute inertia product of a precision assembly component according to claim 1, characterized in that: The calibration workpiece is an aluminum cylindrical part with openings at both ends, has multiple, and through machining cutting part of the surface, makes its own with artificial set size inertia product, mainly for the whole device to calibrate pressure and torque.

3. The high-precision device for measuring the small inertia product of a precision assembly according to claim 1, characterized in that: The pressure sensor is a long strip-shaped piezoresistive sensor with threads at both ends; The clamping frame is a hollow rectangular part with positioning pin holes in the middle, the inside of the hollow rectangular object has threaded holes at both ends, and the outside also has threaded holes; The clamping bottom plate is a rectangular part with threaded holes on the surface; The positioning plate is an aluminum part with a convex groove and a positioning pin hole, which cooperates with the pin hole on the clamping frame to position the calibration workpiece and the real measurement assembly in the clamping tool.

4. The high-precision device for measuring the small inertia product of a precision assembly according to claim 1, characterized in that: The data acquisition card is a synchronous acquisition card with 4 input ports, 1 output port and 1 power interface, each input port has a resolution of 24 bits, the sampling rate is up to 215KSPS, and the data line is connected with the data line of the 4 pressure sensors; the output port is a USB bus port, connected with the interface on the industrial control mainboard through USB data line; the power interface is connected with the lithium battery module through wire; The industrial control mainboard is a small host computer that can run win10 system, with corresponding data recording and data analysis function program, has USB interface, connects with data acquisition card through USB data line, and connects with lithium battery module through wire.

5. A high-precision device for measuring the minute inertia product of a precision assembly component according to claim 1, characterized in that: In order to improve the accuracy of signal acquisition, high-resolution and high-sampling-rate data acquisition card is used to collect signals, and industrial control mainboard is used to process signals, or single-chip microcomputer is used to realize signal acquisition and processing function.

6. A high-precision device for measuring the minute inertia product of a precision assembly component according to claim 1, characterized in that: In order to improve the measurement accuracy and installation convenience of the whole device, piezoresistive sensor with threads and certain structural rigidity is used, or flexible sensor with rigid structure is used, or piezoelectric sensor, strain sensor and capacitive sensor are used instead of existing piezoresistive sensor.

7. A high-precision device for measuring the minute inertia product of a precision assembly component according to claim 1, characterized in that: In order to simplify the structure, the rate of the grating disc feedback in the turntable is taken as the angular velocity, or the angular velocity measuring device is separately arranged on the turntable table surface to measure the angular velocity of the turntable in real time.

8. A method of measuring the product of inertia using the apparatus of claim 1, characterized by: Firstly, the pressure sensor and the whole device are calibrated by calibrating workpieces; then the tested workpiece is fixed by the clamping tool and the pressure sensor, the turntable drives the clamping tool to rotate, and then drives the tested workpiece to rotate together, the length of the workpiece itself is taken as the force arm, so that the moment excited by the inertia product is converted into pressure, which is recognized by the pressure sensor at both ends of the workpiece; the signal generated on the pressure sensor is obtained through the data acquisition card, and after processing, it is uploaded to the industrial control mainboard for storage and analysis, and then according to the rotation speed information of the turntable, the inertia product of the tested workpiece is directly obtained.

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