Quality inspection method, device and system for punching of folding chairs

Abstract

The present application relates to the field of data processing technology, and specifically to a quality inspection method, device and system for punching processing of folding chairs, the method comprising: collecting all pressure data during each punching process of a folding chair steel pipe; dividing the pressure data during each punching process into two categories; dividing the time period of each type of pressure data into a preset number of stages; obtaining the deviation index of each type of pressure data in each stage during each punching process, and marking each stage of the pressure data during each punching process; obtaining the abnormal evaluation value of the pressure data during each punching process; obtaining the time abnormality index of the pressure data during each punching process; and performing quality inspection on each punching process. The present application aims to improve the accuracy of quality inspection of punching processing of folding chairs.

Description

Technical Field

[0001] The present application relates to the field of data processing technology, and in particular to a quality inspection method, device and system for punching of folding chairs. Background Art

[0002] The main purpose of punching holes in folding chairs is to achieve lightweight design and simplify the assembly process. By punching holes of specific shapes and sizes on the tubes or plates of folding chairs, punching not only helps to reduce the weight of the steel tubes, but also serves as a key point for connecting various components, thereby improving the convenience of assembly and disassembly. Punching holes are usually completed through stamping, which is a metal forming technology that applies pressure to metal sheets or tubes through dies and stamping equipment to cause plastic deformation to obtain the desired shape and size.

[0003] The stamping process is usually highly dynamic, and the changes in pressure over time show regularity and suddenness. Traditional pressure data analysis methods often focus on post-evaluation and rely on the statistical results of historical data. This may lead to the inability to capture instantaneous changes and sudden anomalies in the punching process of folding chairs in a timely manner, affecting the accuracy of quality inspection results. Summary of the invention

[0004] In view of the above, it is necessary to provide a quality inspection method, device and system for punching processing of folding chairs to solve the above problems.

[0005] According to one aspect of the present application, a quality inspection method for punching a folding chair is provided, the method comprising:

[0006] Collect all pressure data during each punching process of the folding chair steel pipe;

[0007] The moment corresponding to the minimum trough value of the pressure data in each punching process is recorded as the splitting moment, and the pressure data in each punching process is divided into two categories; based on the distribution characteristics of the extreme value points of each type of pressure data in each punching process, the time period of each type of pressure data is divided into a preset number of stages;

[0008] Compare the curve shape characteristics after fitting the pressure data at the same stage between each punching process and the historical punching process, and the degree of change of the pressure data over time, obtain the deviation index of various pressure data at each stage in each punching process, and mark each stage of the pressure data of each punching process;

[0009] According to the marking values ​​of all types of pressure data in each stage and adjacent stages during each punching process, the abnormal evaluation value of the pressure data during each punching process is obtained; the time lengths corresponding to the two types of pressure data during each punching process are compared, and the time anomaly index of the pressure data during each punching process is obtained by combining the discrete degree of the time lengths corresponding to each punching process and all previous punching processes;

[0010] Based on the time anomaly index and anomaly evaluation value of the pressure data during each punching process, quality inspection is performed on each punching process.

[0011] The time period of each type of pressure data is divided into a preset number of stages, specifically:

[0012] The curves fitted by various pressure data in each stamping process are recorded as various pressure fluctuation curves; the first maximum point of various pressure fluctuation curves is used as the first stage segmentation point, the time period corresponding to all pressure data before the moment corresponding to the first stage segmentation point of various pressure data is recorded as the elastic deformation stage, and the time period corresponding to all remaining pressure data of various pressure data is recorded as the waiting segmentation stage of various pressure data;

[0013] According to the numerical difference characteristics between each extreme point and the adjacent extreme point on the corresponding curve of the to-be-segmented stage of each type of pressure data, the division index of each extreme point is obtained;

[0014] The extreme point with the largest division index is taken as the second-stage segmentation point; the time period corresponding to all pressure data before the corresponding moment of the second-stage segmentation point in the stage to be segmented of each type of pressure data is recorded as the plastic deformation stage, and the time period corresponding to all the remaining pressure data in the stage to be segmented of each type of pressure data is recorded as the fracture stage.

[0015] Wherein, the partition index of each extreme point is obtained, including:

[0016] For each type of pressure data in the stage of being segmented, the absolute value of the slope of the line between each extreme point and the previous extreme point is obtained, recorded as the first slope; the absolute value of the slope of the line between each extreme point and the next extreme point is obtained, recorded as the second slope; the difference between the second slope and the first slope is used as the division index of each extreme point.

[0017] The deviation index of various pressure data at various stages in each punching process is obtained as follows:

[0018] Obtain the slope of the pressure data on various pressure fluctuation curves during each punching process, and use the discrete degree of the slope of the pressure data at each stage during each punching process as the fluctuation index of various pressure data at each stage during each punching process;

[0019] Obtain the extreme value of each type of pressure data in each stage during each punching process and the corresponding time interval; use the ratio of the extreme value to the time interval as the trend value of each type of pressure data in each stage during each punching process;

[0020] The difference in fluctuation index between the current punching process and the historical punching process at the same stage is calculated and recorded as the first difference. The difference in trend value between the current punching process and the historical punching process at the same stage is recorded as the second difference. The first difference and the second difference between the current punching process and all historical punching processes are merged to obtain the deviation index of various pressure data between the current punching process and the historical punching process at each stage.

[0021] The step of marking each stage of the pressure data of each punching process based on the deviation index is specifically: marking each stage where the deviation index is greater than a preset deviation threshold as a preset value greater than 0, and marking it as 0 otherwise.

[0022] The abnormal evaluation value of the pressure data obtained during each punching process is specifically:

[0023] The abnormal evaluation value of the pressure data during each punching process is recorded as , its formula form is: ;in, Indicates the number of all stages in each punching process; , It represents the mark value of the pressure data in the jth and j+1th stages of each punching process; j represents the sequence number of the stage; norm[] represents the normalization function.

[0024] The time anomaly index of the pressure data obtained during each punching process is specifically:

[0025] The absolute value of the difference between the time lengths corresponding to the two types of pressure data in each punching process is calculated, and the opposite number is obtained after multiplying it with the variance value of the time lengths corresponding to each punching process and all previous punching times. The opposite number is used as the exponent of the exponential function, and the result of the exponential function is used as the time anomaly index of the pressure data in each punching process.

[0026] The process of performing quality inspection on each punching process includes:

[0027] The time anomaly index and the anomaly evaluation value of the pressure data in each punching process are normalized respectively. When the normalized value of the time anomaly index and the normalized value of the anomaly evaluation value of the pressure data in each punching process have a value greater than or equal to the preset quality inspection threshold, it is judged that the corresponding punching process has a quality problem; otherwise, it is judged that the corresponding punching process does not have a quality problem.

[0028] According to another aspect of the present application, a quality inspection device for punching processing of folding chairs is provided, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0029] According to another aspect of the present application, a quality inspection system for punching of folding chairs is provided, wherein a computer program is stored in the system, and when the computer program is executed by a processor, any one of the above-mentioned quality inspection methods is implemented.

[0030] This application has at least the following beneficial effects:

[0031] Since two holes can be processed at the same time during punching of steel pipes, the pressure data during each punching process is divided into two categories, corresponding to the punching process of the two holes respectively, which helps to clearly analyze the punching process of each hole and distinguish the pressure fluctuations and changes between the two holes, so as to more accurately evaluate the processing quality of each hole; according to the change characteristics of the pressure data when punching each hole, the various types of pressure data are divided into several stages, which can more easily identify whether abnormal fluctuations occur in a specific stage; by comparing the pressure data of each punching with the pressure data of historical punching, the deviation index is obtained, which has the beneficial effect of helping to quickly identify the difference between the current punching process and each stage of the historical data, and marking each stage of each punching process, which can be Identify the deviation of pressure data at different stages; obtain the abnormal evaluation value and time abnormality index of pressure data in each punching process. The beneficial effect is that by analyzing the distribution of values ​​in the deviation stage, the abnormal conditions in the entire punching process can be cumulatively identified, and the analysis of the change in the length of the classified data interval can help determine the potential abnormalities in the stamping process; further, based on the time abnormality index and abnormal evaluation value of the pressure data in each punching process, real-time quality detection is performed on each punching process; by analyzing these two characteristics, the slight deviations that may exist in the processing process can be identified to ensure the accuracy and quality stability of each punching; through real-time detection, deviations or faults in the punching process can be quickly discovered, early warnings can be given and measures can be taken to avoid the accumulation of quality problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of the steps of the quality inspection method for punching of folding chairs provided in this application;

[0033] Figure 2 A schematic diagram of the division of the punching process provided for this application;

[0034] Figure 3Schematic diagram for obtaining the punching processing quality inspection results provided in this application. DETAILED DESCRIPTION

[0035] In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a concrete manner.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0037] It should also be noted that the terms "first" and "second" in this application and the accompanying drawings are used to distinguish similar objects, rather than to describe a specific order or sequence. The method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the present application, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0038] See also Figure 1 , which shows a flow chart of the steps of a quality inspection method for punching a folding chair provided by an embodiment of the present application, the method comprising the following steps:

[0039] Step 1: Collect all pressure data during each punching process of the folding chair steel pipe.

[0040] This application mainly considers the abnormal pressure data of the steel pipe of the folding chair during stamping. Therefore, this application installs the pressure sensor at the connection between the punching head and the equipment, and collects the pressure data of the steel pipe during the punching process on the CNC lathe through the pressure sensor. In this application, the pressure data collection frequency is set to 10kHz, and the implementer can obtain it according to the actual situation. This application does not impose any restrictions on this.

[0041] Step 2: The moment corresponding to the minimum trough value of the pressure data in each punching process is recorded as the splitting moment, and the pressure data in each punching process is divided into two categories; based on the distribution characteristics of the extreme points of each type of pressure data in each punching process, the time period of each type of pressure data is divided into a preset number of stages.

[0042] Pressure data is closely related to the deformation of the steel pipe during the punching process. By monitoring the pressure changes generated during the punching process, it is possible to determine whether the steel pipe has undergone plastic deformation under appropriate pressure and to evaluate whether the deformation is uniform. The basic principle of punching is to apply high-speed impact force through the punch to cause the steel pipe to undergo plastic deformation in a very short time, thereby forming a hole on the steel pipe. During the punching process, the pressure data can be divided into several different stages in order to better grasp the deformation of the steel pipe in each link and ensure the quality of the punching.

[0043] During the stamping process, the punch head needs to punch through two steel tube walls, and the space between the two steel tube walls is hollow. Therefore, when the punch head successfully penetrates the first steel tube wall, the pressure will drop rapidly until it reaches the minimum value. At this time, the punch head has not fully completed the task, but has touched the second steel tube wall, and the pressure will rise again and enter the next hole stamping. Based on this, the moment corresponding to the minimum trough value of the pressure data during each punching process is recorded as the split moment, the pressure data of all moments before the split moment is recorded as the first category, and all remaining pressure data is recorded as the second category.

[0044] When the punch first contacts the steel pipe, the pressure begins to gradually rise. At this stage, the steel pipe mainly undergoes the elastic deformation stage, that is, it can return to its original shape after deformation. As the punch continues to press down, the pressure continues to increase until it reaches the yield point of the steel pipe. At this time, the steel pipe begins to enter the plastic deformation stage and can no longer fully return to its original state. At this stage, the deformation of the steel pipe is irreversible, that is, the shape of the steel pipe cannot be restored to its original state after it changes. As the punch continues to press down, the hole gradually forms, and the pressure may fluctuate, but generally remains at a high level. When the punch completely penetrates the steel pipe, the steel pipe breaks at the edge of the hole and enters the fracture stage. During this stage, the pressure may drop suddenly because the steel pipe has been cut and the punch is no longer resisted by the steel pipe. However, if the punch continues to press down, the pressure may increase again because the punch continues to apply pressure to the steel pipe until the punching process is completed.

[0045] According to the above analysis, the punching process can be divided into three main stages: elastic deformation stage, plastic deformation stage and fracture stage. For the production of folding chairs, since folding chairs are usually assembled from steel pipes, and steel pipes usually have an upper and lower two-layer structure, during the stamping process, the entire process will experience repeated changes in the above stages. Therefore, various types of pressure data are divided into stages.

[0046] Specifically, curve fitting is performed on various pressure data in each stamping process to obtain various pressure fluctuation curves; the first maximum point of each pressure fluctuation curve is used as the first-stage segmentation point, the time period corresponding to all pressure data before the moment corresponding to the first-stage segmentation point of each type of pressure data is recorded as the elastic deformation stage, and the time period corresponding to all remaining pressure data of each type of pressure data is recorded as the stage to be segmented of each type of pressure data.

[0047] Furthermore, for each type of pressure data in the stage to be segmented, the absolute value of the slope of the line between each extreme point and the previous extreme point is obtained, which is recorded as the first slope; the absolute value of the slope of the line between each extreme point and the next extreme point is obtained, which is recorded as the second slope; the difference between the second slope and the first slope is used as the division index of each extreme point; the extreme point with the largest division index is used as the second-stage segmentation point; the time period corresponding to all pressure data before the corresponding moment of the second-stage segmentation point in the stage to be segmented of each type of pressure data is recorded as the plastic deformation stage, and the time period corresponding to all the remaining pressure data in the stage to be segmented of each type of pressure data is recorded as the fracture stage.

[0048] In this embodiment, the difference between the slopes is measured by the absolute value of the difference. The change in pressure data during the stamping process is different. When the pressure has not reached the yield point, the change in pressure will increase with time. Therefore, when the first stage segmentation point is obtained, it can be directly determined whether the obtained pressure data has decreased; when the pressure data decreases, it indicates that the plastic deformation stage has begun. When the obtained pressure suddenly drops and the amplitude of the change is relatively large, the plastic deformation stage and the fracture stage can be distinguished.

[0049] At this point, the pressure data in each punching process is divided into two categories, and each category is divided into three stages; among them, the division diagram of the punching process is as follows Figure 2 shown.

[0050] Step 3: Compare the curve shape characteristics after fitting the pressure data at the same stage between the current punching process and the historical punching process, and the degree of change of the pressure data over time, and obtain the deviation index of various pressure data at each stage in the current punching process.

[0051] By analyzing the pressure data collected at each stage and its characteristic changes, anomalies in the pressure data can be identified. In the actual punching process, some problems may occur. For example, due to inaccurate positioning, the cylindrical steel pipe may slip, causing the punching to deviate from the predetermined center; in addition, if the punching pressure is set too high, it may cause excessive deformation of the material during punching, thereby affecting the punching accuracy. These problems may have an adverse effect on the quality of the punching.

[0052] The slope of the pressure data on various pressure fluctuation curves during each punching process is obtained, and the discrete degree of the slope of the pressure data at each stage during each punching process is used as the fluctuation index of various pressure data at each stage during each punching process. In this embodiment, the discrete degree of multiple variables is measured in the form of variance.

[0053] Obtain the range value of each type of pressure data in each stage during each punching process and its corresponding time interval; use the ratio of the range value to the time interval as the trend value of each type of pressure data in each stage during each punching process; the trend value can reflect the change characteristics of each type of pressure data in each stage during the punching process.

[0054] Furthermore, the fluctuation index and trend value of the same stage between the current punching process and the historical punching process are compared to obtain the deviation index of various pressure data in the current punching process at various stages: the difference in the fluctuation index between the current punching process and the historical punching process at the same stage is calculated, which is recorded as the first difference; the difference in the trend value between the current punching process and the historical punching process at the same stage is recorded as the second difference, and the first difference and the second difference between the current punching process and all historical punching processes are merged to obtain the deviation index of various pressure data between the current punching process and the historical punching process at various stages.

[0055] In this embodiment, in the process of obtaining the deviation index, the difference between the two variables is measured in the form of the absolute value of the difference; multiple variables can be fused using a mixed operation of addition and multiplication, that is, the deviation index is specifically: calculating the product of the first difference and the second difference between the current punching process and each historical punching process; and taking the sum of the products between the current punching process and all historical punching processes as the deviation index of various types of pressure data between the current punching process and the historical punching processes at each stage.

[0056] Each stage where the deviation index is greater than the preset deviation threshold is marked as a preset value greater than 0, otherwise it is marked as 0; in this embodiment, the deviation threshold is 0.7; the preset value is 1, and the stage marked as 1 indicates that the pressure data of this stage has seriously deviated; the implementer can adjust the preset value according to the actual situation, and this application does not impose any restrictions on this.

[0057] Step 4: According to the marking values ​​of all types of pressure data in each punching process at each stage and adjacent stages, the abnormal evaluation value of the pressure data in each punching process is obtained; the time lengths corresponding to the two types of pressure data in each punching process are compared, and the discrete degree of the time lengths corresponding to each punching process and all previous punching processes is combined to obtain the time anomaly index of the pressure data in each punching process.

[0058] Since the data changes in each stage of the stamping process are a continuous whole, if the data in the previous stage deviates, while the data in the next stage deviates less, it can be considered that the deviation in the previous stage was caused by the impact force generated by the equipment during normal operation, rather than abnormal factors. This deviation will not affect the subsequent product quality and should not be regarded as an abnormal situation.

[0059] According to the marking values ​​of all types of pressure data in each stage and adjacent stages during each punching process, the abnormal evaluation value of the pressure data during each punching process is obtained, which is recorded as , its formula form is: ;in, Indicates the number of all stages in each punching process; , represents the mark value of the pressure data in the jth and j+1th stages during each punching process; j represents the sequence number of the stage; norm[] represents the normalization function. The normalization function in this embodiment adopts the sigmoid function. The implementer can select a suitable normalization function according to the actual situation, and this application does not limit this. It should be noted that, It can measure whether the pressure data of two consecutive stages are judged to be seriously deviated. When the pressure data of adjacent stages are seriously deviated, the punching quality is more likely to be abnormal. At the same time, the influence of the final stage on the quality of the overall product is greater. The larger it is, the greater the abnormal evaluation value of the pressure data in each punching process.

[0060] When analyzing abnormal pressure data, you cannot rely solely on the deviation index to determine whether the pressure data is abnormal. Although the deviation index can reflect the fluctuation of pressure data, when the pressure data deviates, this deviation does not necessarily mean an abnormality. In fact, pressure fluctuations may be caused by external factors such as impact force, rather than actual abnormal conditions. Therefore, when judging whether the pressure data is abnormal, other possible interference factors must be taken into account, and the deviation index cannot be used as the only judgment criterion.

[0061] By comparing the time lengths corresponding to the two types of pressure data in each punching process, combined with the discrete degree of the time lengths corresponding to each punching process and all previous punching times, the time anomaly index of the pressure data in each punching process is obtained: the absolute value of the difference between the time length of the first type of pressure data and the time length of the second type of pressure data in each punching process is calculated, multiplied by the variance value of the time length corresponding to each punching process and all previous punching times, and then the opposite number is obtained, the opposite number is used as the exponent of the exponential function, and the result of the exponential function is used as the time anomaly index of the pressure data in each punching process.

[0062] The time lengths of the two types of pressure data during each punching process are judged. If the punch head deviates from the center of the steel pipe during punching, the time spans of the two types of data obtained will be asymmetric, and the time length of each type will deviate, resulting in a larger time anomaly index.

[0063] Step 5: Based on the time anomaly index and anomaly evaluation value of the pressure data during each punching process, quality inspection is performed on each punching process.

[0064] The time anomaly index and the anomaly evaluation value of the pressure data in each punching process are normalized respectively. When the normalized value of the time anomaly index of the pressure data in each punching process and the normalized value of the anomaly evaluation value have a value greater than or equal to the preset quality inspection threshold, it is judged that the corresponding punching process has a quality problem and the parameters in the process need to be adjusted; otherwise, it is judged that the corresponding punching process has no quality problem. In this embodiment, the preset quality inspection threshold value is 0.7, and the normalization method adopts the maximum minimization method.

[0065] Among them, the schematic diagram of obtaining the punching processing quality inspection results is as follows Figure 3 shown.

[0066] Based on the same concept as the method embodiment of the present application, a quality inspection device for punching processing of folding chairs is provided, including a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the steps of any one of the above methods when executing the computer program.

[0067] Based on the same concept as the method embodiment of the present application, a quality inspection system for punching processing of folding chairs is provided, wherein a computer program is stored in the system, and when the computer program is executed by a processor, any one of the above-mentioned quality inspection methods is implemented.

[0068] In summary, since two holes can be processed at the same time in each punching of a steel pipe, the pressure data in each punching process is divided into two categories, corresponding to the punching process of the two holes respectively, which helps to clearly analyze the punching process of each hole and distinguish the pressure fluctuations and changes between the two holes, so as to more accurately evaluate the processing quality of each hole; according to the change characteristics of the pressure data when each hole is punched, the various types of pressure data are divided into several stages, which can more easily identify whether an abnormal fluctuation occurs in a specific stage; by comparing the pressure data of each punching with the pressure data of historical punching, the deviation index is obtained, which has the beneficial effect of helping to quickly identify the difference between the current punching process and each stage of the historical data, and marking each stage of each punching process. The deviation of pressure data at different stages can be identified; the abnormal evaluation value and time abnormality index of pressure data in each punching process can be obtained. The beneficial effect is that by analyzing the distribution of values ​​in the deviation stage, the abnormal conditions in the entire punching process can be cumulatively identified, and the analysis of the change in the length of the classified data interval can help determine the potential abnormalities in the stamping process; further, based on the time abnormality index and abnormal evaluation value of the pressure data in each punching process, real-time quality detection is performed on each punching process; by analyzing these two characteristics, the slight deviations that may exist in the processing process can be identified to ensure the accuracy and quality stability of each punching; through real-time detection, deviations or faults in the punching process can be quickly discovered, early warnings can be given and measures can be taken to avoid the accumulation of quality problems.

[0069] It should be noted that the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the system, method and computer program product according to the embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

[0070] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A quality inspection method for punching of folding chairs, characterized in that: The method comprises the following steps: Collect all pressure data during each punching process of the folding chair steel pipe; The moment corresponding to the minimum trough value of the pressure data in each punching process is recorded as the splitting moment, and the pressure data in each punching process is divided into two categories; based on the distribution characteristics of the extreme value points of each type of pressure data in each punching process, the time period of each type of pressure data is divided into a preset number of stages; Compare the curve shape characteristics after fitting the pressure data at the same stage between each punching process and the historical punching process, and the degree of change of the pressure data over time, obtain the deviation index of various pressure data at each stage in each punching process, and mark each stage of the pressure data of each punching process; According to the marking values ​​of all types of pressure data in each stage and adjacent stages during each punching process, the abnormal evaluation value of the pressure data during each punching process is obtained; the time lengths corresponding to the two types of pressure data during each punching process are compared, and the time anomaly index of the pressure data during each punching process is obtained by combining the discrete degree of the time lengths corresponding to each punching process and all previous punching processes; Based on the time anomaly index and anomaly evaluation value of the pressure data during each punching process, quality inspection is performed on each punching process.

2. The quality inspection method for punching of folding chairs according to claim 1, characterized in that: The time period of each type of pressure data is divided into a preset number of stages, specifically: The curves fitted by various pressure data in each stamping process are recorded as various pressure fluctuation curves; the first maximum point of various pressure fluctuation curves is used as the first stage segmentation point, the time period corresponding to all pressure data before the moment corresponding to the first stage segmentation point of various pressure data is recorded as the elastic deformation stage, and the time period corresponding to all remaining pressure data of various pressure data is recorded as the waiting segmentation stage of various pressure data; According to the numerical difference characteristics between each extreme point and the adjacent extreme point on the corresponding curve of the to-be-segmented stage of each type of pressure data, the division index of each extreme point is obtained; The extreme point with the largest division index is taken as the second-stage segmentation point; the time period corresponding to all pressure data before the corresponding moment of the second-stage segmentation point in the stage to be segmented of each type of pressure data is recorded as the plastic deformation stage, and the time period corresponding to all the remaining pressure data in the stage to be segmented of each type of pressure data is recorded as the fracture stage.

3. The quality inspection method for punching of folding chairs as claimed in claim 2, characterized in that: The step of obtaining the partition index of each extreme point includes: For each type of pressure data in the stage of being segmented, the absolute value of the slope of the line between each extreme point and the previous extreme point is obtained, recorded as the first slope; the absolute value of the slope of the line between each extreme point and the next extreme point is obtained, recorded as the second slope; the difference between the second slope and the first slope is used as the division index of each extreme point.

4. The quality inspection method for punching of folding chairs as claimed in claim 2, characterized in that: The deviation index of various pressure data at various stages in each punching process is obtained as follows: Obtain the slope of the pressure data on various pressure fluctuation curves during each punching process, and use the discrete degree of the slope of the pressure data at each stage during each punching process as the fluctuation index of various pressure data at each stage during each punching process; Obtain the extreme values ​​of various pressure data in each stage of each punching process and their corresponding time intervals; The ratio of the extreme difference value to the time interval is used as the trend value of each type of pressure data at each stage during each punching process; The difference in fluctuation index between the current punching process and the historical punching process at the same stage is calculated and recorded as the first difference. The difference in trend value between the current punching process and the historical punching process at the same stage is recorded as the second difference. The first difference and the second difference between the current punching process and all historical punching processes are merged to obtain the deviation index of various pressure data between the current punching process and the historical punching process at each stage.

5. The quality inspection method for punching of folding chairs according to claim 1, characterized in that: The method of marking each stage of the pressure data of each punching process based on the deviation index is specifically: marking each stage where the deviation index is greater than a preset deviation threshold as a preset value greater than 0, otherwise marking it as 0.

6. The quality inspection method for punching of folding chairs according to claim 1, characterized in that: The abnormal evaluation value of the pressure data obtained during each punching process is specifically: The abnormal evaluation value of the pressure data during each punching process is recorded as , its formula form is: ;in, Indicates the number of all stages in each punching process; , It represents the mark value of the pressure data in the jth and j+1th stages of each punching process; j represents the sequence number of the stage; norm[] represents the normalization function.

7. The quality inspection method for punching of folding chairs according to claim 1, characterized in that: The time anomaly index of the pressure data in each punching process is obtained as follows: The absolute value of the difference between the time lengths corresponding to the two types of pressure data in each punching process is calculated, and the opposite number is obtained after multiplying it with the variance value of the time lengths corresponding to each punching process and all previous punching times. The opposite number is used as the exponent of the exponential function, and the result of the exponential function is used as the time anomaly index of the pressure data in each punching process.

8. The quality inspection method for punching of folding chairs as claimed in claim 1, characterized in that: The process of quality inspection for each punching process includes: The time anomaly index and the anomaly evaluation value of the pressure data in each punching process are normalized respectively. When the normalized value of the time anomaly index and the normalized value of the anomaly evaluation value of the pressure data in each punching process have a value greater than or equal to the preset quality inspection threshold, it is judged that the corresponding punching process has a quality problem; otherwise, it is judged that the corresponding punching process does not have a quality problem.

9. A quality inspection device for punching a folding chair, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A quality inspection system for punching of folding chairs, wherein a computer program is stored in the system, characterized in that: When the computer program is executed by a processor, the quality detection method according to any one of claims 1 to 8 is implemented.

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