Method for measuring performance degradation of ball screw pair based on virtual measurement technology

Abstract

According to the ball screw degeneration method based on the virtual measurement technology, the degeneration degree of the ball screw can be reflected on line through high-frequency signals such as motor current and vibration, and the ball screw does not need to be repeatedly disassembled and assembled between two experiments. Firstly, an online detection experiment device of the ball screw is developed. Then, a ball screw degradation model based on the virtual measurement technology is creatively established; the test device comprises a servo motor, a current sensor, a dynamic torque sensor, a magnetic powder brake and a ball screw. The method has the advantages that the factory production efficiency is greatly improved, the fault occurrence rate is reduced, the capability of predicting the service life of the ball screw is achieved, and the production continuity is improved.

Description

Technical Field

[0001] The present invention belongs to the field of ball screw degradation, and in particular relates to a method for measuring ball screw pair performance degradation based on virtual measurement technology. Background Art

[0002] In terms of signal processing, most existing studies only measure the friction torque, preload, positioning accuracy and repeatability of the ball screw pair at shutdown. Sensors are rarely used to measure high-frequency signals such as vibration and motor current, and signal processing methods related to the accelerated life test of the ball screw pair are rarely involved. It is obviously impossible to accurately describe the dynamic degradation process of the ball screw pair by only considering it, so it is necessary to add sensors to the measurement scheme for measurement. Mechanical equipment sensor signals have the characteristics of multi-source heterogeneity, large frequency differences, and many redundant signals. Based on the classic time-frequency domain signal processing algorithm and feature selection algorithm, the processing method of high-frequency signals in the accelerated life test of the ball screw pair is studied. Removing redundant signals and extracting key features are key issues that need to be solved in the measurement of the accelerated life test of the ball screw pair. Indicators such as preload, friction torque, positioning accuracy, and stiffness can reflect the degradation state of the ball screw pair. However, due to the limitations of measurement equipment and methods, the above indicators often require shutdown or even the use of a special test platform to measure the relevant indicators. On the one hand, it increases the measurement cost and affects the efficiency of the accelerated test. On the other hand, repeated shutdowns and disassembly will also affect the degradation performance of the ball screw pair. Therefore, based on virtual measurement technology, it is necessary to establish a mapping relationship between easy-to-measure signals such as motor current and vibration and difficult-to-measure indicators such as preload and stiffness, and explore the optimal shutdown detection interval corresponding to different degradation stages of the ball screw pair. This is the main problem that needs to be solved in the dynamic measurement of the ball screw pair in the accelerated life test.

[0003] Through the above analysis, the problems and defects of the existing technology are as follows: the indicators reflecting the degradation state of the ball screw pair, such as preload, friction torque, stiffness and positioning accuracy, are limited by the measurement equipment and methods, which affects the measurement accuracy and is not easy to measure. The current technology has the ability to measure the degradation of the ball screw, but most of them are non-on-machine measurement of the degradation degree, and cannot achieve online real-time monitoring. Summary of the invention

[0004] The present invention is implemented as follows: a method for measuring the performance degradation of a ball screw pair based on virtual measurement technology comprises: Step 1: Select the required ball screw according to the data to be measured and connect the sensors of each measurement data; Step 2, collecting and storing the required performance index data during the entire ball screw degradation process; Step 3: In-depth analysis of the changing rules and influencing factors of various signals in the ball screw pair acceleration life test method, identification and removal of redundant high-frequency signals, and extraction of key degradation features; Step 4: Establishing the correlation relationship between the virtual quantity and the low-frequency signal through the correlation algorithm; Step 5: Perform an accelerated life test to accelerate the degradation of the ball screw without damaging the ball screw pair; Step six, according to the correlation algorithm and the screw degradation law, a ball screw pair degradation model based on virtual measurement technology is constructed.

[0005] In view of the problems existing in the prior art, the present invention provides a device and method for measuring the performance degradation of a ball screw pair based on virtual measurement technology.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solution: A device for a ball screw pair acceleration test method based on virtual measurement technology comprises a driving part, a sensor part, a machine tool loading part, a load part and a data analysis part.

[0007] The driving part includes a servo motor, a driver of the servo motor, and a PLC controller. The driving structure is used as the power part of the entire test device to make the ball screw reciprocate at the required speed and time interval.

[0008] The sensor part is used to detect the motor current signal through the current sensor and the dynamic torque sensor to detect and collect the friction torque value.

[0009] The loading part of the machine tool mainly includes a workbench. By adding weight within a range on the workbench, horizontal loading of the ball screw is achieved to simulate the wear of the ball screw in the factory.

[0010] The load part is mainly achieved by connecting a magnetic powder brake at the tail end of the ball screw and controlling the braking force by the current to realize axial loading on the ball screw.

[0011] The data analysis part is mainly composed of a host computer, which performs signal processing and correlation analysis on the signals or data uploaded by the sensors. The invention of the on-machine measurement method of the ball screw pair degradation characteristics based on virtual measurement technology and the ball screw life

[0012] The technology of indirectly predicting difficult-to-measure performance indicators with easy-to-measure signals in the test solves the problem of on-machine measurement of various performance indicators and dynamic characteristics in the accelerated life test of the ball screw pair. It greatly improves the factory production efficiency, reduces the failure rate, and has the ability to predict the life of the ball screw, which improves the continuity of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG1 is a design diagram of a ball screw pair acceleration life test method based on virtual measurement technology of the present invention; FIG2 is a design diagram of the ball screw pair of the present invention; FIG3 is a flow chart of data processing of the present invention; In the figure, 1-servo motor 2-current sensor 3-dynamic torque sensor 4-workbench 5-Data acquisition module 6-Ball screw DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] As shown in FIG. 1 and FIG. 2 , the present invention discloses a ball screw pair acceleration life test method device based on virtual measurement technology, including a driving part, a sensor part, a machine tool loading part, a load part, and a data analysis part.

[0016] The drive structure mainly includes PLC controller, servo motor, and servo motor driver. PLC controls the servo motor driver, which is then connected to the servo motor. The motor is controlled by sending pulses to make it reciprocate at a specified speed and time interval.

[0017] The sensor part mainly includes current sensor and dynamic torque sensor. The current sensor is directly connected to the servo motor driver, and the dynamic torque sensor is connected between the servo motor and the ball screw, which are used to collect current data and friction torque respectively.

[0018] The loading part of the machine tool mainly includes the workbench. By adding weight within a certain range on the workbench, horizontal loading of the ball screw is achieved, simulating the wear of the ball screw in the factory.

[0019] The load part is mainly achieved by connecting a magnetic powder brake at the tail end of the ball screw and controlling the braking force by the current to realize axial loading of the ball screw.

[0020] The data analysis part is mainly composed of a host computer, which performs signal processing and correlation analysis on the signals or data uploaded by the sensors.

[0021] The present invention is implemented in this way: a method for measuring performance degradation of a ball screw pair based on virtual measurement technology comprises: Step 1: Select the required ball screw according to the data to be measured and connect the sensors of each measurement data; Step 2, collecting and storing the required performance index data during the entire ball screw degradation process; Step 3: In-depth analysis of the changing rules and influencing factors of various signals in the ball screw pair acceleration life test method. Identify and remove redundant signals of frequency signals and extract key degradation features; Step 4: Establishing the correlation relationship between the virtual quantity and the low-frequency signal through the correlation algorithm; Step 5: Perform an accelerated life test to accelerate the degradation of the ball screw without damaging the ball screw pair; Step six, according to the correlation algorithm and the screw degradation law, a ball screw pair degradation model based on virtual measurement technology is constructed.

Claims

1. The technical solutions in the embodiments of the present invention are clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

2. As shown in FIG. 1 and FIG. 2 , the present invention discloses a ball screw pair acceleration life test method device based on virtual measurement technology, including a driving part, a sensor part, a machine tool loading part, a load part, and a data analysis part.

3. The drive structure mainly includes PLC controller, servo motor, and servo motor driver. PLC controls the servo motor driver, which is then connected to the servo motor. The motor is controlled by sending pulses to make it reciprocate at a specified speed and time interval.

4. The sensor structure mainly includes a current sensor and a dynamic torque sensor. The current sensor is directly connected to the servo motor driver, and the dynamic torque sensor is connected between the servo motor and the ball screw, which are used to collect current data and friction torque respectively.

5. The machine tool loading structure mainly includes the workbench. By adding weight within a certain range on the workbench, horizontal loading of the ball screw is achieved to simulate the wear of the ball screw in the factory.

6. The load structure is mainly to connect a magnetic powder brake at the tail end of the ball screw and use the current size to control the braking force to achieve axial loading of the ball screw.

7. The data analysis structure is mainly composed of a host computer, which performs signal processing and correlation analysis on the signals or data uploaded by the sensors.

8. The present invention is implemented as follows: a method for measuring performance degradation of a ball screw pair based on virtual measurement technology comprises: Step 1: Select the required ball screw according to the data to be measured and connect the sensors of each measurement data; Step 2: Collect and store the required performance index data during the entire ball screw degradation process; Step 3: In-depth analysis of the changing rules and influencing factors of various signals in the ball screw pair acceleration life test method. Identify and remove redundant signals of frequency signals and extract key degradation features; Step 4: Establishing the correlation relationship between the virtual quantity and the low-frequency signal through the correlation algorithm; Step 5: Perform an accelerated life test to accelerate the degradation of the ball screw without damaging the ball screw pair; Step six, according to the correlation algorithm and the screw degradation law, a ball screw pair degradation model based on virtual measurement technology is constructed.

Images