A real-time monitoring method and system for broken blades based on edge computing

Abstract

The present invention discloses a real-time monitoring method and system for tool breakage based on edge computing, which belongs to the field of numerical control technology. Before monitoring, the edge computing module is connected to the numerical control system, and the acquisition card and the vibration sensor are connected through the interface on the edge computing module; during trial processing, the edge computing module synchronizes and caches all trial processing vibration amplitude data and spindle current data, and determines the spindle current data change threshold and the upper and lower limits of the spindle current data; during monitoring, the edge computing module is connected to the numerical control system, and the edge computing module obtains the spindle current data in the numerical control system. When the change in the spindle current within a preset time exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within a preset time, the edge computing module determines that a tool breakage occurs. In this way, not only the computing pressure of the main station is reduced, but also the accuracy of the judgment of the tool breakage situation is improved.

Description

Technical Field

[0001] The present invention belongs to the field of numerical control technology, and more specifically, relates to a real-time monitoring method and system for broken tools based on edge computing. Background Art

[0002] In the process of machining parts of CNC machine tools, due to unreasonable tool paths, unstable cutting forces, poor tool consistency, uneven workpiece materials, tool aging, stress fatigue and other reasons, tool breakage is very likely to occur, resulting in the generation of waste products and scrap parts. Especially in automated and intelligent production lines, due to unattended operation, if the abnormal state of the tool cannot be discovered in time, it will often affect the automatic production of the production line, and then affect the production rhythm of the production line, causing the production line to fail to work normally. Therefore, it is necessary to find a method that can monitor the condition of tool breakage in real time to deal with the problem of tool breakage during the machining process.

[0003] There are two main existing technical solutions for monitoring broken blades: non-real-time monitoring and real-time monitoring.

[0004] Non-real-time monitoring includes manual inspection, laser beam inspection, machine vision inspection, etc. Manual inspection usually relies on the operator's experience or quantitative methods. This mode increases the intensity of manual work and reduces the service life of the tool and production and processing efficiency. Compared with manual inspection, laser beam inspection, machine vision inspection, etc., although they make up for their shortcomings to a certain extent, they cannot monitor the status of the tool during the processing process and can only perform offline inspection of the tool status, which affects the production and processing efficiency.

[0005] Real-time monitoring determines the tool breakage status by real-time monitoring of the key characteristic quantities before and after the tool breaks during the processing process. The key characteristic quantities mainly include the motor current, sound signal, vibration signal, etc. of the spindle or inverter. Technology for detecting tool breakage through spindle current load, etc.: When a small tool is semi-finished or finished at high speed, due to the small amount of cutting, there is no obvious stable change in the motor current of the spindle or inverter before and after the tool breaks, that is, the sensitivity is not high, and the tool breakage phenomenon cannot be effectively determined. Tool breakage detection by sound change: After the tool breaks, the sound wave will be abnormal, and the tool breakage can be determined by sampling and analyzing the sound wave. The disadvantage is that the sound wave analysis is relatively complicated, and it requires no external sound interference, and has high requirements for environmental factors. Technology of vibration sensor built into the tool handle: multiple components are integrated in a small space, the structure is complex, the cost is high, and multiple types of tool handles need to be designed separately.

[0006] In addition, the existing real-time monitoring technology can also be divided into two types according to the judgment of the broken tool body. One is the judgment of the CNC system: judging the tool status through the data inside the CNC system (such as the spindle current), the disadvantage is that it occupies the computing resources of the CNC system and the accuracy is not high; the other is the judgment of an independent computer outside the CNC system: the sensor is connected to the computer, the computer collects sensor data to judge the tool status, and then communicates with the CNC system through Ethernet, the disadvantage is that the transmission time is long, the transmission delay is uncertain, and the integration is low. Summary of the invention

[0007] In view of the defects of the prior art and the need for improvement, the present invention provides a real-time monitoring method and system for broken tools based on edge computing, aiming to solve the technical problem that the existing real-time monitoring technology can only judge the tool status through data inside or outside the CNC system alone, resulting in occupying the computing resources of the CNC system or poor real-time performance.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a real-time monitoring method for broken knives based on edge computing, comprising:

[0009] Before monitoring, the edge computing module is connected to the CNC system, and the acquisition card is connected to the vibration sensor through the interface on the edge computing module. The vibration sensor is installed in the area affected by the cutting vibration of the CNC machine tool;

[0010] During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module, and at the same time, the edge computing module obtains the spindle current data in the numerical control system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; determines the spindle current data change threshold according to all the calculated maximum changes of the trial processing spindle current data; and determines the upper limit and lower limit of the spindle current data according to the maximum and minimum values ​​of the trial processing vibration amplitude data;

[0011] During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current within the preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that a tool breakage has occurred.

[0012] Furthermore, the edge computing module is connected to the numerical control system through the NCUC bus.

[0013] Furthermore, during the trial processing, after all the trial processing vibration amplitude data are collected, the maximum value max and the minimum value min are taken; the preset threshold value is greater than

[0014] Furthermore, before monitoring, the vibration sensor is fixed in the area affected by the cutting vibration of the CNC machine tool by using a strong magnet adsorption or a threaded connection.

[0015] Further, the determining the spindle current data change threshold value according to all calculated maximum change amounts of the trial processing spindle current data includes: taking an average of all calculated maximum change amounts of the trial processing spindle current data as the spindle current data change threshold value;

[0016] The method of determining the upper limit and lower limit of the spindle current data based on the maximum and minimum values ​​of the trial machining vibration amplitude data includes: obtaining the spindle current data at the moment corresponding to the maximum value of the trial machining vibration amplitude data as the upper limit of the spindle current data; obtaining the spindle current data at the moment corresponding to the minimum value of the trial machining vibration amplitude data as the lower limit of the spindle current data.

[0017] Furthermore, during monitoring, after the edge computing module determines that a tool breakage has occurred, it feeds back an alarm message to the numerical control system, so that the numerical control system controls the driving device to stop running according to the feedback information.

[0018] In a second aspect, the present invention provides a real-time monitoring system for broken knives based on edge computing, including: an edge computing module, an acquisition card, and a vibration sensor;

[0019] Before monitoring, the edge computing module is connected to the CNC system, the interface on the edge computing module is connected to the acquisition card and the vibration sensor, and the vibration sensor is installed in the CNC machine tool cutting vibration affected area;

[0020] During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module, and at the same time, the edge computing module obtains the spindle current data in the numerical control system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; the edge computing module determines the spindle current data change threshold value according to all the calculated maximum changes of the trial processing spindle current data; and determines the upper limit value and lower limit value of the spindle current data according to the maximum value and minimum value of the trial processing vibration amplitude data;

[0021] During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current within the preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that a tool breakage has occurred.

[0022] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0023] (1) Different from the existing real-time monitoring technology that can only determine the tool status through data inside or outside the numerical control system, the present invention synchronizes and caches all trial processing vibration amplitude data and spindle current data before monitoring, and determines the spindle current data change threshold through the change of the vibration amplitude data, and determines the upper and lower limits of the spindle current data through the upper and lower limits of the vibration amplitude data; during monitoring, it is only necessary to obtain the spindle current data in the numerical control system in real time, and when the change in the spindle current within a preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within a preset time period, it is determined that the tool is broken. In this way, on the one hand, the present invention uses the edge computing module to monitor the broken tool status in the machine tool processing process in real time, which reduces the computing pressure of the main station, reduces the data transmission cost, and improves the integration; on the other hand, since the edge computing module can synchronize the vibration amplitude data (external data) and the spindle current data (internal data), it is possible to establish a connection between the external data and the internal data before monitoring, and determine the change threshold and upper and lower limits of the internal data when the tool breaks through the external data. Therefore, during monitoring, it is only necessary to obtain the internal data to judge the broken tool situation, which is particularly suitable for automated and intelligent production scenarios.

[0024] (2) The present invention adopts the NCUC bus connection and communication mode, which is stable and reliable, ensures the real-time performance of broken knife monitoring, and simplifies the connection of IO cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic flow chart of a method for real-time monitoring of broken knives based on edge computing provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of edge computing module connection provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the installation position of the vibration sensor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0030] See also Figure 1 , combined with Figure 2 and Figure 3 The present invention provides a real-time monitoring method for broken blades based on edge computing, comprising:

[0031] Before monitoring, the edge computing module is connected to the CNC system, and the acquisition card is connected to the vibration sensor through the interface on the edge computing module. The vibration sensor is installed in the area affected by the cutting vibration of the CNC machine tool;

[0032] During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module, and at the same time, the edge computing module obtains the spindle current data in the numerical control system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; determines the spindle current data change threshold according to all the calculated maximum changes of the trial processing spindle current data; and determines the upper limit and lower limit of the spindle current data according to the maximum and minimum values ​​of the trial processing vibration amplitude data;

[0033] During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current within the preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that a tool breakage has occurred.

[0034] Specifically, Figure 2 As shown, before or during monitoring, the edge computing module is connected to the CNC system through the NCUC bus. After the edge computing module is connected to the CNC system, it can be correctly identified by the CNC system and displayed in the topology of the CNC system.

[0035] like Figure 3As shown, the vibration sensor is fixed in the area affected by the cutting vibration of the CNC machine tool by means of strong magnet adsorption or threaded connection, specifically including the four vertical sides of the workpiece 2, the front, back, left, and right of the fixture 3 or the end position of the spindle 1.

[0036] During the trial processing, after all the trial processing vibration amplitude data are collected, the maximum value max and the minimum value min are taken; the preset threshold value is greater than At the same time, the average of all the calculated maximum changes in the trial processing spindle current data is used as the threshold value of the spindle current data change; the spindle current data at the time corresponding to the maximum value of the trial processing vibration amplitude data is obtained as the upper limit value of the spindle current data; the spindle current data at the time corresponding to the minimum value of the trial processing vibration amplitude data is obtained as the lower limit value of the spindle current data.

[0037] During monitoring, when the edge computing module determines that a tool breakage has occurred, it will feed back the alarm information to the CNC system, so that the CNC system will control the drive device to stop running according to the feedback information.

[0038] In order to further illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0039] When a twist drill is used on a CNC machine tool to drill a workpiece, the tool is prone to breakage. Before monitoring, the vibration sensor is adsorbed on the end of the spindle with a strong magnet, the vibration sensor signal line is connected to the acquisition card, the acquisition card is connected to the USB interface of the edge computing module, and the edge computing module uses the NCUC bus to communicate with the Huazhong 8 CNC system. During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module. At the same time, the edge computing module obtains the spindle current data in the CNC system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; averages all the calculated maximum changes of the trial processing spindle current data as the spindle current data change threshold; obtains the spindle current data at the time corresponding to the maximum value of the trial processing vibration amplitude data as the upper limit of the spindle current data; obtains the spindle current data at the time corresponding to the minimum value of the trial processing vibration amplitude data as the lower limit of the spindle current data; wherein, during trial processing, after all the trial processing vibration amplitude data are collected, the maximum value max and the minimum value min are taken; the preset threshold is greater than During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current during the processing stage exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that the tool is broken and sends a tool breakage alarm feedback information to the CNC system. The master station then controls the drive device to stop running according to the feedback information.

[0040] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A real-time monitoring method for broken blades based on edge computing, characterized in that: include: Before monitoring, the edge computing module is connected to the CNC system, and the acquisition card is connected to the vibration sensor through the interface on the edge computing module. The vibration sensor is installed in the area affected by the cutting vibration of the CNC machine tool; During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module, and at the same time, the edge computing module obtains the spindle current data in the numerical control system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; according to all the calculated maximum changes of the trial processing spindle current data, the spindle current data change threshold is determined; And according to the maximum and minimum values ​​of the trial machining vibration amplitude data, determine the upper and lower limits of the spindle current data; During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current within the preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that a tool breakage has occurred.

2. According to the edge computing-based real-time monitoring method for broken blades according to claim 1, it is characterized in that: The edge computing module is connected to the numerical control system through the NCUC bus.

3. According to the edge computing-based real-time monitoring method for broken blades according to claim 1, it is characterized in that: During the trial processing, after all the trial processing vibration amplitude data are collected, the maximum value max and the minimum value min are taken; the preset threshold value is greater than 4. The method for real-time monitoring of broken blades based on edge computing according to claim 1 is characterized in that: Before monitoring, use a strong magnet or threaded connection to fix the vibration sensor in the area affected by the cutting vibration of the CNC machine tool.

5. The method for real-time monitoring of broken blades based on edge computing according to claim 1 is characterized in that: The step of determining the spindle current data change threshold value according to all calculated maximum change amounts of the trial processing spindle current data comprises: taking an average of all calculated maximum change amounts of the trial processing spindle current data as the spindle current data change threshold value; The method of determining the upper limit and lower limit of the spindle current data based on the maximum and minimum values ​​of the trial machining vibration amplitude data includes: obtaining the spindle current data at the moment corresponding to the maximum value of the trial machining vibration amplitude data as the upper limit of the spindle current data; obtaining the spindle current data at the moment corresponding to the minimum value of the trial machining vibration amplitude data as the lower limit of the spindle current data.

6. The real-time monitoring method for broken blades based on edge computing according to claim 1 is characterized in that: During monitoring, after the edge computing module determines that a tool breakage has occurred, it feeds back the alarm information to the numerical control system, so that the numerical control system controls the drive device to stop running according to the feedback information.

7. A real-time monitoring system for broken knives based on edge computing, characterized in that: include: Edge computing module, acquisition card, vibration sensor; Before monitoring, the edge computing module is connected to the CNC system, the interface on the edge computing module is connected to the acquisition card and the vibration sensor, and the vibration sensor is installed in the CNC machine tool cutting vibration affected area; During trial processing, the vibration sensor collects the trial processing vibration amplitude data of the tool and sends it to the edge computing module, and at the same time, the edge computing module obtains the spindle current data in the numerical control system; after the edge computing module synchronizes and caches all the trial processing vibration amplitude data and the spindle current data, it calculates the maximum change of the trial processing spindle current data corresponding to the maximum change of the trial processing vibration amplitude data within the preset time length when it exceeds the preset threshold; The edge computing module determines a spindle current data change threshold value according to the maximum change amount of all the trial processing spindle current data calculated; And according to the maximum and minimum values ​​of the trial machining vibration amplitude data, determine the upper and lower limits of the spindle current data; During monitoring, the edge computing module is connected to the CNC system, and the edge computing module obtains the spindle current data in the CNC system. When the change in the spindle current within the preset time period exceeds the spindle current data change threshold, or the spindle current exceeds the upper limit or lower limit of the spindle current data within the preset time period, the edge computing module determines that a tool breakage has occurred.

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