Fault detection method, system, medium and CNC machine tool for feed axis of CNC machine tool

Abstract

The present invention provides a method, system, medium and CNC machine tool for fault detection of a feed axis of a CNC machine tool, wherein the fault detection method comprises: generating an operation program of the CNC machine tool; after the CNC machine tool enters the operation state, collecting operation data associated with the feed axis; generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis; and determining the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault. The present invention accurately diagnoses the fault of the feed axis by collecting and analyzing the torque current of the feed axis when it moves at a uniform speed, so as to timely discover equipment faults, and does not need to increase the detection cost, which is convenient for on-site implementation.

Description

Technical Field

[0001] The invention belongs to the field of CNC machine tool detection and signal processing, and relates to a detection method and system, and in particular to a fault detection method, system, medium and CNC machine tool for a feed shaft of a CNC machine tool. Background Art

[0002] At present, the fault detection of mechanical transmission components of CNC machine tools or other CNC equipment usually requires the use of external detection equipment, such as vibration sensors and analysis equipment, etc. The related equipment costs are high and it is difficult to implement on site. Under normal circumstances, due to cost reasons, users of CNC machine tools or other CNC equipment will not specifically purchase related detection equipment. The use of traditional mechanical detection methods usually requires the disassembly of the machine, which is difficult to implement on site. On-site fault judgment of the spindle and feed axis mostly relies on experience, and problems can only be discovered when more serious processing problems occur. At this time, key components are usually damaged and difficult to repair.

[0003] Therefore, how to provide a fault detection method, system, medium and CNC machine tool for the feed axis of a CNC machine tool to solve the problem that the existing technology relies mostly on experience to judge the faults of the spindle and feed axis. Therefore, the problem will only be discovered when serious processing problems occur in the CNC machine tool, resulting in damage to key components and difficulty in maintenance. This has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a fault detection method, system, medium and CNC machine tool for the feed shaft of a CNC machine tool, so as to solve the problem that the prior art relies mostly on experience to judge the faults of the spindle and the feed shaft. Therefore, the problem will not be discovered until serious processing problems occur in the CNC machine tool, resulting in damage to key components and difficulty in maintenance.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides, on the one hand, a method for detecting a feed axis fault of a CNC machine tool, comprising: generating an operating program for the CNC machine tool; after the CNC machine tool enters an operating state, collecting operating data associated with the feed axis; generating a fault detection parameter of the CNC machine tool based on the operating data of the feed axis; and determining the fault detection parameter of the CNC machine tool to detect whether the CNC machine tool has a fault.

[0006] In one embodiment of the present invention, the operating program of the CNC machine tool is to control the feed shaft to move at a uniform speed, and it needs to reciprocate between the positive and negative limit positions once. When the feed shaft runs to the positive limit position or the negative limit position, the program pauses within a preset pause time period.

[0007] In one embodiment of the present invention, the operation data of the feed axis includes feedback speed, feedback position and / or torque current of the feed axis.

[0008] In one embodiment of the present invention, the fault detection parameters of the CNC machine tool include positive limit setting parameters, negative limit setting parameters, positive limit oscillation detection parameters when stationary, negative limit oscillation detection parameters when stationary, pull plate fault detection parameters and / or accumulated deflection value of the screw.

[0009] In one embodiment of the present invention, the step of generating the fault detection parameters of the CNC machine tool according to the operating data of the feed axis includes: dividing the torque current during movement into N intervals with equal distances according to the feedback position of the feed axis; N is greater than or equal to 2; calculating the average value and variance of the torque current in each interval respectively; wherein the average value of the torque current in each interval includes the current average value of the torque current at the positive limit position and the current average value of the torque current at the negative limit position; the variance of the torque current in each interval includes the variance of the torque current at the positive limit position and the variance of the torque current at the negative limit position; calculating the median of the average value of the torque current and the median of the variance of the torque current during operation.

[0010] In one embodiment of the present invention, the step of generating the fault detection parameters of the CNC machine tool according to the operation data of the feed axis includes: obtaining the positive limit setting parameter by comparing the current average value of the torque current at the positive limit position with the median of the torque current average value; obtaining the negative limit setting parameter by comparing the current average value of the torque current at the negative limit position with the median of the torque current average value; obtaining the positive limit oscillation detection parameter at rest by comparing the variance of the torque current at the positive limit position with the median of the torque current variance; obtaining the negative limit oscillation detection parameter at rest by comparing the variance of the torque current at the negative limit position with the median of the torque current variance; obtaining the pull plate fault detection parameter by comparing the average value of the torque current in the first interval with the median of the torque current average value or by comparing the average value of the torque current in the Nth interval with the median of the torque current average value; and calculating the cumulative deflection value of the screw based on the average value of the torque current in each interval and the median of the torque current average value.

[0011] In one embodiment of the present invention, the step of judging the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault includes: if the positive limit setting parameter is greater than the preset limit mismatch judgment threshold, it is judged as a positive limit setting error; if the negative limit setting parameter is greater than the preset limit mismatch judgment threshold, it is judged as a negative limit setting error; if the positive limit oscillation detection parameter when stationary is greater than the preset stationary oscillation judgment threshold, it is judged that there is oscillation at the positive limit when stationary; if the negative limit oscillation detection parameter when stationary is greater than the preset stationary oscillation judgment threshold, it is judged that there is oscillation at the negative limit when stationary; if the pull plate fault detection parameter is greater than the preset pull plate fault judgment threshold, it is judged that the pull plate has a fault; if the cumulative deflection value of the screw is greater than the preset screw misalignment judgment threshold, it is judged that there is a misalignment fault in the screw.

[0012] Yet another aspect of the present invention provides a fault detection system for a feed axis of a CNC machine tool, comprising: a program generation module for generating an operating program for the CNC machine tool; an acquisition module for acquiring operating data associated with the feed axis after the CNC machine tool enters an operating state; a parameter generation module for generating fault detection parameters of the CNC machine tool based on the operating data of the feed axis; and a fault detection module for determining the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault.

[0013] Another aspect of the present invention provides a medium having a computer program stored thereon, and the computer program, when executed by a processor, implements the method for detecting a feed axis fault of a numerically controlled machine tool.

[0014] The last aspect of the present invention provides a CNC machine tool, comprising: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the CNC machine tool executes the fault detection method of the CNC machine tool feed axis.

[0015] As described above, the fault detection method, system, medium and CNC machine tool of the CNC machine tool feed axis of the present invention have the following beneficial effects:

[0016] The fault detection method, system, medium and CNC machine tool of the feed shaft of the CNC machine tool described in the present invention accurately diagnose the fault of the feed shaft by collecting and analyzing the torque current conditions when the feed shaft moves at a uniform speed, so as to timely discover equipment faults without increasing the detection cost, and it is easy to implement on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flow chart of a method for detecting a feed axis fault of a numerically controlled machine tool according to an embodiment of the present invention.

[0018] Figure 2It is a schematic flow chart of S13 in the fault detection method of the feed axis of a numerically controlled machine tool of the present invention.

[0019] Figure 3 It is a schematic diagram showing the principle structure of a fault detection system for a feed axis of a numerically controlled machine tool according to an embodiment of the present invention.

[0020] Component number description

[0021] 3. Fault detection of feed axis of CNC machine tools

[0022] system

[0023] 31Program generation module

[0024] 32 acquisition modules

[0025] 33 parameter generation module

[0026] 34 Fault detection module

[0027] Steps S11 to S14

[0028] Steps S131 to S134 DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0030] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0031] Embodiment 1

[0032] This embodiment provides a method for detecting a fault of a feed axis of a CNC machine tool, comprising:

[0033] Generating an operating program for the CNC machine tool;

[0034] After the CNC machine tool enters an operating state, collecting operating data associated with the feed axis;

[0035] Generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis;

[0036] The fault detection parameters of the numerically controlled machine tool are determined to detect whether the numerically controlled machine tool has a fault.

[0037] The following will describe in detail the fault detection method for the feed axis of a CNC machine tool provided by this embodiment in conjunction with the diagram. Figure 1 , which is a flow chart of a method for detecting a fault in a feed axis of a CNC machine tool in one embodiment. Figure 1 As shown, the fault detection method of the feed axis of a CNC machine tool specifically comprises the following steps:

[0038] S11, generating an operating program of the CNC machine tool. In this embodiment, the operating program is an operating program set for the feed axis, which is executed by the CNC system.

[0039] Specifically, the operating program of the CNC machine tool is to control the feed shaft to move at a uniform speed (for example, 1200 mm / min), and it needs to reciprocate between the positive and negative limit positions once. When the feed shaft runs to the positive limit position or the negative limit position, the program pauses within a preset pause time period (for example, 1s).

[0040] S12, after the CNC machine tool enters an operating state, collecting operating data associated with the feed axis.

[0041] Specifically, the operation data of the feed axis includes feedback speed, feedback position and / or torque current of the feed axis.

[0042] S13, generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis.

[0043] In this embodiment, the fault detection parameters of the CNC machine tool include positive limit setting parameters, negative limit setting parameters, positive limit oscillation detection parameters when stationary, negative limit oscillation detection parameters when stationary, pull plate fault detection parameters and / or cumulative deflection value of the screw, etc.

[0044] See also Figure 2 , which is a schematic diagram of the process of S13. Figure 2 As shown, the S13 specifically includes the following steps:

[0045] S131, dividing the torque current during movement into N intervals with equal distances according to the feedback position of the feed shaft; N is greater than or equal to 2.

[0046] S132, respectively calculate the average value of the torque current in each interval (the average value of the torque current in each interval is recorded as E1, E2, ..., E n) and variance (the variance of the torque current in each interval is recorded as V1, V2, ..., V n ); wherein the average value of the torque current in each interval includes the average value of the torque current at the positive limit position (in this embodiment, the average value of the torque current at the positive limit position is recorded as E pos ) and the average current of the torque current at the negative limit position (the average current of the torque current at the negative limit position is recorded as E neg ); The variance of the torque current in each interval includes the variance of the torque current at the positive limit position (the variance of the torque current at the positive limit position is recorded as V pos ) and the variance of the torque current at the negative limit position (the variance of the torque current at the negative limit position is recorded as V neg ).

[0047] S133, calculate the median of the average value of the torque current during operation (the median of the average value of the torque current during operation is recorded as E m ) and the median of the torque current variance (the median of the torque current variance is denoted as V m ).

[0048] S134,

[0049] By comparing the average current value of the torque current at the positive limit position with the median of the average current value of the torque current, the positive limit setting parameter is obtained, which is recorded as

[0050] By comparing the average current value of the torque current at the negative limit position with the median of the average current value of the torque current, the negative limit setting parameter is obtained, which is recorded as

[0051] By comparing the variance of the torque current at the positive limit position with the median of the torque current variance, the positive limit oscillation detection parameter at rest is obtained, which is recorded as

[0052] By comparing the variance of the torque current at the negative limit position with the median of the torque current variance, the negative limit oscillation detection parameter at rest is obtained, which is recorded as

[0053] The pull plate fault detection parameter is obtained by comparing the average value of the torque current in the first interval with the median of the torque current average value or the average value of the torque current in the Nth interval with the median of the torque current average value. The parameter is recorded as or

[0054] The accumulated deflection value of the lead screw is calculated based on the average value of the torque current in each interval and the median of the average value of the torque current.

[0055] The calculation formula of the cumulative deflection value of the screw is as follows:

[0056]

[0057] S14, determining the fault detection parameters of the numerically controlled machine tool to detect whether the numerically controlled machine tool has a fault.

[0058] The S14 specifically includes the following process.

[0059] If the positive limit setting parameter is greater than a preset limit error determination threshold (the preset limit error determination threshold is recorded as lim_error_th), it is determined that the positive limit setting is wrong;

[0060] If the negative limit setting parameter is greater than a preset limit error determination threshold (the preset limit error determination threshold is recorded as lim_error_th), it is determined that the negative limit setting is wrong;

[0061] If the positive limit oscillation detection parameter when stationary is greater than a preset stationary oscillation determination threshold (the preset stationary oscillation determination threshold is recorded as still_error_th), it is determined that there is oscillation when the positive limit is stationary;

[0062] If the static negative limit oscillation detection parameter is greater than a preset static oscillation determination threshold (the preset static oscillation determination threshold is denoted as still_error_th), it is determined that there is oscillation at the static negative limit;

[0063] If the plate fault detection parameter is greater than a preset plate fault determination threshold (the preset plate fault determination threshold is denoted as plate_error_th), it is determined that the plate is faulty;

[0064] If the accumulated deflection value of the screw is greater than the preset screw misalignment judgment threshold (the preset screw misalignment judgment threshold is denoted as concentric_error_th), it is determined that the screw has a misalignment fault.

[0065] In this embodiment, the above fault detection steps may be performed simultaneously or sequentially, both of which are included in the protection scope of the present invention.

[0066] The fault detection method for the feed shaft of a CNC machine tool described in this embodiment accurately diagnoses the fault of the feed shaft by collecting and analyzing the torque current conditions when the feed shaft moves at a uniform speed, so as to timely discover equipment faults without increasing the detection cost, and is easy to implement on site.

[0067] A medium (also called a computer-readable storage medium) stores a computer program, which implements the above-mentioned method for detecting the fault of the feed axis of a numerically controlled machine tool when executed by a processor.

[0068] A person skilled in the art can understand that computer-readable storage media: all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

[0069] Embodiment 2

[0070] This embodiment provides a fault detection system for a feed axis of a CNC machine tool, comprising:

[0071] A program generation module, used for generating an operating program for the CNC machine tool;

[0072] A collection module, used for collecting operation data associated with the feed axis after the CNC machine tool enters an operation state;

[0073] A parameter generation module, used for generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis;

[0074] The fault detection module is used to determine the fault detection parameters of the numerically controlled machine tool to detect whether the numerically controlled machine tool has a fault.

[0075] The following will describe in detail the fault detection system for the feed axis of a CNC machine tool provided in this embodiment in conjunction with the diagram. Please refer to 3, which is a schematic diagram of the principle structure of the fault detection system for the feed axis of a CNC machine tool in one embodiment. Figure 3 As shown, the fault detection system 3 for the feed axis of a numerically controlled machine tool includes a program generation module 31 , a collection module 32 , a parameter generation module 33 and a fault detection module 34 .

[0076] The program generation module 31 is used to generate the operating program of the CNC machine tool. In this embodiment, the operating program is an operating program set for the feed axis, which is executed by the CNC system.

[0077] Specifically, the operating program of the CNC machine tool is to control the feed shaft to move at a uniform speed (for example, 1200 mm / min), and it needs to reciprocate between the positive and negative limit positions once. When the feed shaft runs to the positive limit position or the negative limit position, the program pauses within a preset pause time period (for example, 1s).

[0078] The acquisition module 32 is used to acquire the operation data associated with the feed axis after the CNC machine tool enters the operation state.

[0079] Specifically, the operation data of the feed axis includes feedback speed, feedback position and / or torque current of the feed axis.

[0080] The parameter generation module 33 is used to generate the fault detection parameters of the CNC machine tool according to the operation data of the feed axis. In this embodiment, the fault detection parameters include positive limit setting parameters, negative limit setting parameters, positive limit oscillation detection parameters when stationary, negative limit oscillation detection parameters when stationary, pull plate fault detection parameters and / or screw cumulative deflection value, etc.

[0081] Specifically, the parameter generation module 33 divides the torque current during movement into N intervals with equal distances according to the feedback position of the feed axis; N is greater than or equal to 2; the average value and variance of the torque current in each interval are calculated respectively; wherein the average value of the torque current in each interval includes the current average value of the torque current at the positive limit position and the current average value of the torque current at the negative limit position; the variance of the torque current in each interval includes the variance of the torque current at the positive limit position and the variance of the torque current at the negative limit position; the median of the average value of the torque current and the median of the variance of the torque current during operation are calculated.

[0082] The parameter generation module 33 obtains the positive limit setting parameter by comparing the current average value of the torque current at the positive limit position with the median of the torque current average value; obtains the negative limit setting parameter by comparing the current average value of the torque current at the negative limit position with the median of the torque current average value; obtains the positive limit oscillation detection parameter at rest by comparing the variance of the torque current at the positive limit position with the median of the torque current variance; obtains the negative limit oscillation detection parameter at rest by comparing the variance of the torque current at the negative limit position with the median of the torque current variance; obtains the pull plate fault detection parameter by comparing the average value of the torque current in the first interval with the median of the torque current average value or by comparing the average value of the torque current in the Nth interval with the median of the torque current average value; calculates the cumulative deflection value of the screw based on the average value of the torque current in each interval and the median of the torque current average value.

[0083] The fault detection module 34 is used to determine the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault.

[0084] When the fault detection module 34 determines that the positive limit setting parameter is greater than a preset limit error determination threshold (the preset limit error determination threshold is recorded as lim_error_th), it determines that the positive limit setting is wrong;

[0085] When the fault detection module 34 determines that the negative limit setting parameter is greater than a preset limit error determination threshold (the preset limit error determination threshold is recorded as lim_error_th), it determines that the negative limit setting is wrong;

[0086] When the fault detection module 34 determines that the positive limit oscillation detection parameter at rest is greater than a preset still oscillation determination threshold (the preset still oscillation determination threshold is denoted as still_error_th), it determines that there is oscillation at rest at the positive limit;

[0087] When the fault detection module 34 determines that the static negative limit oscillation detection parameter is greater than a preset static oscillation determination threshold (the preset static oscillation determination threshold is recorded as still_error_th), it determines that there is oscillation at the static negative limit;

[0088] When the fault detection module 34 determines that the plate fault detection parameter is greater than a preset plate fault determination threshold (the preset plate fault determination threshold is denoted as plate_error_th), it determines that the plate has a fault;

[0089] When the fault detection module 34 determines that the cumulative deflection value of the screw is greater than a preset screw misalignment determination threshold (the preset screw misalignment determination threshold is denoted as concentric_error_th), it determines that there is a misalignment fault in the screw.

[0090] In this embodiment, the fault detection module 34 may perform the above fault detections simultaneously or sequentially, both of which are included in the protection scope of the present invention.

[0091] It should be noted that it should be understood that the division of the various modules of the above system is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And these modules can all be implemented in the form of software called by processing elements, or they can all be implemented in the form of hardware, or some modules can be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. For example: the x module can be a separately established processing element, or it can be integrated in a certain chip of the above system. In addition, the x module can also be stored in the memory of the above system in the form of program code, and called and executed by a certain processing element of the above system. The implementation of other modules is similar. These modules can be integrated together in whole or in part, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software. The above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASIC), one or more digital singnal processors (DSP), one or more field programmable gate arrays (FPGA), etc. When a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. These modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0092] Embodiment 3

[0093] This embodiment provides a CNC machine tool, including: a processor, a memory, a transceiver, a communication interface and / or a system bus; the memory and the communication interface are connected to the processor and the transceiver through the system bus and complete communication with each other, the memory is used to store computer programs, the communication interface is used to communicate with other devices, and the processor and the transceiver are used to run the computer program, so that the CNC machine tool executes each step of the CNC machine tool feed axis fault detection method as described in Example 1.

[0094] The system bus mentioned above can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The system bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. The communication interface is used to realize the communication between the database access device and other devices (such as clients, read-write libraries, and read-only libraries). The memory may include random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage.

[0095] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0096] The protection scope of the fault detection method for the feed axis of a CNC machine tool described in the present invention is not limited to the execution order of the steps listed in this embodiment. All solutions implemented by adding, reducing or replacing steps in the prior art based on the principles of the present invention are included in the protection scope of the present invention.

[0097] The present invention also provides a fault detection system for a feed shaft of a CNC machine tool. The fault detection system for the feed shaft of a CNC machine tool can implement the fault detection method for the feed shaft of a CNC machine tool described in the present invention. However, the implementation device of the fault detection method for the feed shaft of a CNC machine tool described in the present invention includes but is not limited to the structure of the fault detection system for the feed shaft of a CNC machine tool listed in this embodiment. All structural deformations and replacements of the prior art made according to the principles of the present invention are included in the protection scope of the present invention.

[0098] In summary, the present invention provides a method, system, medium and a CNC machine tool for detecting a feed shaft fault. The method collects and analyzes the torque current of the feed shaft when the feed shaft moves at a constant speed to accurately diagnose the feed shaft fault, so as to timely detect equipment faults without increasing the detection cost, and is convenient for on-site implementation. The present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for detecting a feed axis fault of a CNC machine tool, characterized in that: include: Generating an operating program for the CNC machine tool; After the CNC machine tool enters an operating state, collecting operating data associated with the feed axis; Generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis; Determining the fault detection parameters of the numerically controlled machine tool to detect whether the numerically controlled machine tool has a fault; The step of generating the fault detection parameters of the CNC machine tool according to the operation data of the feed axis includes: dividing the torque current during movement into N intervals with equal distances according to the feedback position of the feed axis; N is greater than or equal to 2; calculating the average value and variance of the torque current in each interval respectively; wherein the average value of the torque current in each interval includes the current average value of the torque current at the positive limit position and the current average value of the torque current at the negative limit position; the variance of the torque current in each interval includes the variance of the torque current at the positive limit position and the variance of the torque current at the negative limit position; calculating the median of the average value of the torque current and the median of the variance of the torque current during operation.

2. The method for detecting a fault of a feed axis of a CNC machine tool according to claim 1, characterized in that: The operation program of the CNC machine tool is to control the feed shaft to move at a uniform speed, and it needs to reciprocate between the positive and negative limit positions once. When the feed shaft runs to the positive limit position or the negative limit position, the program pauses within a preset pause time period.

3. The method for detecting a fault of a feed axis of a CNC machine tool according to claim 2, characterized in that: The operating data of the feed axis include feedback speed, feedback position and / or torque current of the feed axis.

4. The method for detecting a fault of a feed axis of a CNC machine tool according to claim 3, characterized in that: The fault detection parameters of the CNC machine tool include positive limit setting parameters, negative limit setting parameters, positive limit oscillation detection parameters when stationary, negative limit oscillation detection parameters when stationary, pull plate fault detection parameters and / or screw cumulative deflection values.

5. The method for detecting a fault of a feed axis of a CNC machine tool according to claim 4, characterized in that: The step of generating the fault detection parameters of the CNC machine tool according to the operation data of the feed axis comprises: The positive limit setting parameter is obtained by comparing the current average value of the torque current at the positive limit position with the median of the torque current average value; The negative limit setting parameter is obtained by comparing the current average value of the torque current at the negative limit position with the median of the torque current average value; By comparing the variance of the torque current at the positive limit position with the median of the torque current variance, the positive limit oscillation detection parameter at rest is obtained; By comparing the variance of the torque current at the negative limit position with the median of the torque current variance, the negative limit oscillation detection parameter at rest is obtained; The pull plate fault detection parameter is obtained by comparing the average value of the torque current in the first interval with the median of the average value of the torque current or by comparing the average value of the torque current in the Nth interval with the median of the average value of the torque current; The accumulated deflection value of the lead screw is calculated based on the average value of the torque current in each interval and the median of the average value of the torque current.

6. The method for detecting a feed axis fault of a CNC machine tool according to claim 4, characterized in that: The step of determining the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault includes: If the positive limit setting parameter is greater than the preset limit improper judgment threshold, it is judged that the positive limit setting is wrong; If the negative limit setting parameter is greater than the preset limit improper judgment threshold, it is judged that the negative limit setting is wrong; If the static positive limit oscillation detection parameter is greater than a preset static oscillation determination threshold, it is determined that there is oscillation at the static positive limit; If the static negative limit oscillation detection parameter is greater than the preset static oscillation determination threshold, it is determined that there is oscillation at the static negative limit; If the pull plate fault detection parameter is greater than a preset pull plate fault determination threshold, it is determined that the pull plate is faulty; If the accumulated deflection value of the screw is greater than the preset screw misalignment judgment threshold, it is determined that the screw has a misalignment fault.

7. A fault detection system for a feed axis of a CNC machine tool, characterized in that: include: A program generation module, used for generating an operating program for the CNC machine tool; A collection module, used for collecting operation data associated with the feed axis after the CNC machine tool enters the operation state; A parameter generation module, used for generating fault detection parameters of the CNC machine tool according to the operation data of the feed axis; A fault detection module, used for determining the fault detection parameters of the CNC machine tool to detect whether the CNC machine tool has a fault; The parameter generation module is also used to: divide the torque current during movement into N intervals with equal distances according to the feedback position of the feed axis; N is greater than or equal to 2; Calculate the average value and variance of the torque current in each interval respectively; wherein the average value of the torque current in each interval includes the current average value of the torque current at the positive limit position and the current average value of the torque current at the negative limit position; the variance of the torque current in each interval includes the variance of the torque current at the positive limit position and the variance of the torque current at the negative limit position; Calculate the median of the average value of the torque current and the median of the torque current variance during operation.

8. A medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for detecting a feed axis fault of a CNC machine tool as claimed in any one of claims 1 to 6 is implemented.

9. A CNC machine tool, characterized in that: include: Processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the CNC machine tool executes the method for detecting a feed axis fault of a CNC machine tool according to any one of claims 1 to 6.

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