A method and system for detecting air tightness of plastic packaging containers for food

Abstract

The present invention discloses a method and system for detecting air tightness of a plastic packaging container for food, and relates to the technical field of air tightness detection. The method for detecting air tightness of a plastic packaging container for food comprises: obtaining an air pressure change image of a vacuum chamber of a vacuum packaging machine in a first time period; using the air pressure change image, determining the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period; obtaining the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine according to the state retention degree in each air pressure change interval; determining the first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period using the environmental interference degree and each air pressure change interval; determining the air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine using the first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period and the second air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to each second time period.

Description

Technical Field

[0001] The present invention relates to the technical field of air tightness detection, and in particular to an air tightness detection method and system for a plastic packaging container for food. Background Art

[0002] Vacuum packaging machines are often used in the food industry because after vacuum packaging, food can resist oxidation, thus achieving the purpose of long-term preservation. If there is a leak in the vacuum chamber of the vacuum packaging machine during vacuuming, it will cause the preserved food to deteriorate and produce toxins. Therefore, when vacuum packaging food, it is very important to detect whether the vacuum chamber of the vacuum packaging machine is leaking.

[0003] In the existing methods, the detection of whether the vacuum chamber of the vacuum packaging machine is leaking is mainly performed by analyzing the threshold range of the air pressure in the vacuum chamber.

[0004] However, the existing methods do not take into account the impact of the packaging environment on the air pressure of the vacuum chamber, resulting in low accuracy of the detection results. Summary of the invention

[0005] The embodiments of the present invention provide a method and system for detecting the air tightness of a plastic packaging container for food, which can improve the accuracy of the detection result.

[0006] According to one aspect of an embodiment of the present invention, there is provided a method for detecting air tightness of a plastic packaging container for food, comprising:

[0007] Acquire an image of air pressure change in a vacuum chamber of a vacuum packaging machine during a first time period;

[0008] Determine the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period by using the air pressure change image;

[0009] Obtaining an environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine according to the state maintenance degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period;

[0010] Determine a first air leakage degree of a vacuum chamber of a vacuum packaging machine corresponding to a first time period by using the environmental interference degree and each air pressure variation interval;

[0011] The leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine is determined by using the first leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period and the second leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to each second time period, and the second time period is a historical time period before the first time period.

[0012] In one aspect of an embodiment of the present invention, there is provided a system for detecting air tightness of a plastic packaging container for food, comprising a vacuum packaging machine, an air pressure sensor and an air tightness detection device;

[0013] Vacuum packaging machines, used to vacuum plastic pack food;

[0014] An air pressure sensor is used to obtain the corresponding air pressure value of the vacuum chamber of the vacuum packaging machine at each moment;

[0015] An airtightness testing device is used to execute the airtightness testing method for food plastic packaging containers provided in any one of the above aspects.

[0016] In the method for detecting the air tightness of a plastic packaging container for food provided by an embodiment of the present invention, an air pressure change image of the vacuum chamber of an empty packaging machine in a first time period is first obtained, and then the state retention degree in each air pressure change interval corresponding to the first time period is determined based on the air pressure change image. Then, based on the state retention degree in each air pressure change interval, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine is obtained. Finally, the environmental interference degree is used to correct each air pressure change interval corresponding to the first time period to obtain the first air leakage degree corresponding to the first time period, thereby obtaining the final air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine based on the first air leakage degree. In this way, the embodiment of the present invention fully considers the influence of the packaging environment on the air tightness detection and eliminates the interference of special factors such as the packaging environment, so that the air tightness of the vacuum chamber of the vacuum packaging machine can be accurately analyzed, thereby improving the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic flow chart of a first method for detecting air tightness of a plastic food packaging container provided by an embodiment of the present invention;

[0019] Figure 2 A schematic flow chart of a second method for detecting air tightness of a plastic food packaging container provided by an embodiment of the present invention;

[0020] Figure 3 A schematic flow chart of a third method for detecting air tightness of a plastic food packaging container provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the air tightness detection method for a plastic food packaging container proposed by the present invention, its specific implementation method, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0022] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0023] In the existing methods, the detection of whether the vacuum chamber of the vacuum packaging machine is leaking is mainly performed by analyzing the threshold range of the air pressure in the vacuum chamber. However, the existing methods do not take into account the impact of the packaging environment on the air pressure in the vacuum chamber, resulting in low accuracy of the detection results.

[0024] The object of the present invention is to provide a method and system for detecting the air tightness of plastic packaging containers for food. In the method for detecting the air tightness of plastic packaging containers for food provided by the embodiment of the present invention, the pressure change image of the vacuum chamber of the empty packaging machine in the first time period is first obtained, and then the state retention degree in each pressure change interval corresponding to the first time period is determined according to the pressure change image. Then, according to the state retention degree in each pressure change interval, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine is obtained. Finally, the environmental interference degree is used to correct each pressure change interval corresponding to the first time period to obtain the first air leakage degree corresponding to the first time period, so as to obtain the final air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine according to the first air leakage degree. In this way, the embodiment of the present invention fully considers the influence of the packaging environment on the air tightness detection, eliminates the interference of special factors such as the packaging environment, so as to accurately analyze the air tightness of the vacuum chamber of the vacuum packaging machine and improve the accuracy of the detection results.

[0025] The following describes a specific embodiment of a method and system for detecting air tightness of a plastic packaging container for food provided by an embodiment of the present invention.

[0026] Figure 1 A flow chart of a method for detecting air tightness of a plastic packaging container for food is provided. The method for detecting air tightness of a plastic packaging container for food can be applied to an air tightness detection device in an air tightness detection system for a plastic packaging container for food. The method for detecting air tightness of a plastic packaging container for food can include the following S101 to S105.

[0027] S101, acquiring an image of air pressure variation in a vacuum chamber of a vacuum packaging machine in a first time period.

[0028] In this embodiment, the first time period may be a preset air pressure detection time period, or may be the time duration for completing vacuuming of food. For example, the first time period may be preset to 1 hour.

[0029] The air pressure variation image is used to characterize the trend of air pressure variation in the vacuum chamber of the vacuum packaging machine within a preset air pressure detection time period.

[0030] As an example, the air tightness detection device may use an air pressure sensor to obtain air pressure values ​​corresponding to various time points in a first time period, thereby forming an air pressure change image of the first time period.

[0031] S102: using the air pressure variation image, determining the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure variation interval corresponding to the first time period.

[0032] In this embodiment, the air pressure change image can be used to divide a plurality of air pressure change intervals corresponding to the first time period. For example, the air pressure change image of the first time period can be divided into a plurality of air pressure change intervals according to a preset division time.

[0033] The state retention degree is used to characterize the stability of the air pressure value in the air pressure variation interval. For example, the air pressure values ​​corresponding to each time point in the air pressure variation interval can be used to perform variance calculation to obtain the state retention degree in the air pressure variation interval.

[0034] As an example, the airtightness detection device divides the air pressure change image of the first time period into multiple air pressure change intervals according to the preset division time. Then, for each air pressure change interval, the airtightness detection device uses the air pressure value corresponding to each time point in each air pressure change interval to perform variance calculation on each air pressure change interval, thereby obtaining the state retention degree in each air pressure change interval corresponding to the first time period.

[0035] S103, obtaining the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine according to the state maintenance degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period.

[0036] In this embodiment, the environmental interference degree is used to characterize the degree of interference of the packaging environment on the air pressure of the vacuum chamber of the vacuum packaging machine. For example, the environmental interference degree can be the degree of interference of the food temperature on the air pressure of the vacuum chamber of the vacuum packaging machine.

[0037] As an example, the influence of food temperature on air pressure is mainly manifested in the initial period of time when the vacuum chamber is evacuated. Therefore, the difference between the state retention degree in the first air pressure change interval corresponding to the first time period and the state retention degree in other air pressure change intervals can be calculated respectively, and then the differences are accumulated to obtain the average value, which is used as the degree of interference of food temperature on the air pressure of the vacuum chamber of the vacuum packaging machine.

[0038] S104, determining a first air leakage degree corresponding to a vacuum chamber of the vacuum packaging machine in a first time period by using the environmental interference degree and each air pressure variation interval.

[0039] In this embodiment, the first air leakage degree is used to represent the air leakage degree of the vacuum chamber of the vacuum packaging machine in the first time period.

[0040] As an example, after obtaining the environmental interference degree, the airtightness detection device can obtain an air pressure correction coefficient corresponding to the environmental interference degree based on the environmental interference degree. Then, the air pressure change value of each air pressure change interval is corrected according to the air pressure correction coefficient to obtain the corrected air pressure change value of each air pressure change interval. The specific process of obtaining the air pressure correction coefficient is: normalize the environmental interference degree, and subtract the difference between the normalized environmental interference degree and the constant 1 as the air pressure correction coefficient. Normalization can be performed using the maximum and minimum value normalization method, which will not be described in detail here. The product of the air pressure correction coefficient and the air pressure change value of each air pressure change interval is used as the corrected air pressure change value of each air pressure change interval.

[0041] Finally, the corrected air pressure change values ​​in each air pressure change interval are accumulated to obtain a first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period.

[0042] S105, determining the leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine by using the first leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period and the second leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to each second time period, wherein the second time period is a historical time period before the first time period.

[0043] In this embodiment, the second time period is a historical time period before the first time period, and the second time period may be a historical preset air pressure detection time period, or may be a historical duration of vacuuming food. The duration of the first time period may be equal to or different from the duration of the second time period.

[0044] The second air leakage degree is used to characterize the air leakage degree of the vacuum chamber of the vacuum packaging machine in the second time period.

[0045] As an example, after obtaining the first air leakage of the vacuum chamber of the vacuum packaging machine corresponding to the first time period, the air tightness detection device accumulates the first air leakage and the second air leakage of the vacuum chamber of the vacuum packaging machine corresponding to each second time period to obtain the total air leakage of the vacuum chamber of the vacuum packaging machine. Finally, the corresponding air leakage inspection degree is determined according to the total air leakage of the vacuum chamber of the vacuum packaging machine.

[0046] Through this embodiment, the pressure change image of the vacuum chamber of the empty packaging machine in the first time period is first obtained, and then the state retention degree in each pressure change interval corresponding to the first time period is determined according to the pressure change image. Then, according to the state retention degree in each pressure change interval, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine is obtained. Finally, the environmental interference degree is used to correct each pressure change interval corresponding to the first time period to obtain the first air leakage degree corresponding to the first time period, so as to obtain the final air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine according to the first air leakage degree. In this way, the embodiment of the present invention fully considers the influence of the packaging environment on the air tightness detection, eliminates the interference of special factors such as the packaging environment, so as to accurately analyze the air tightness of the vacuum chamber of the vacuum packaging machine and improve the accuracy of the detection results.

[0047] As an optional embodiment, S101 may specifically include:

[0048] Using an air pressure sensor, obtaining the corresponding air pressure value of the vacuum chamber of the vacuum packaging machine at each time in the first time period;

[0049] According to the corresponding air pressure values ​​at each moment in the first time period, an air pressure change image of the vacuum chamber of the vacuum packaging machine in the first time period is constructed.

[0050] In this embodiment, the air tightness detection device can perform real-time detection of the air pressure in the vacuum chamber of the vacuum packaging machine every 1 second through the air pressure sensor until the vacuuming of the food is completed.

[0051] According to the obtained air pressure values ​​corresponding to each time point, the obtained air pressure is used as the y-axis and the time corresponding to the air pressure collection is used as the x-axis to construct an air pressure change image of the vacuum chamber of the vacuum packaging machine in the first time period.

[0052] Through this embodiment, the air pressure sensor is used to obtain the air pressure value corresponding to the vacuum chamber of the vacuum packaging machine at each moment, thereby constructing a corresponding air pressure change image, which is helpful for subsequent accurate analysis of the air pressure change image, thereby determining the first air leakage degree corresponding to the vacuum chamber of the vacuum packaging machine and the air pressure change image.

[0053] As an optional embodiment, Figure 2 As shown, S102 may specifically include the following S201-S203.

[0054] S201, using the air pressure change image, determining each air pressure extreme value of the vacuum chamber of the vacuum packaging machine within a first time period;

[0055] S202, segmenting the air pressure change image according to each air pressure extreme value in the first time period to obtain a plurality of air pressure change intervals corresponding to the first time period;

[0056] S203, determining the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure variation interval according to the corresponding air pressure value at each time in each air pressure variation interval.

[0057] In this embodiment, the air pressure extremes include an air pressure maximum value and an air pressure minimum value.

[0058] As an example, after obtaining the air pressure change image, the air tightness detection device can perform smoothing processing using the Douglas Peucker algorithm, and then solve the curve extreme points of the smoothed air pressure change image to obtain the various air pressure extremes corresponding to the air pressure change image.

[0059] Then, the curve in the pressure change image is segmented using the pressure extreme value as a segmentation point, and a sequence range sandwiched between two adjacent extreme value points is taken as a pressure change interval, thereby obtaining multiple pressure change intervals corresponding to the first time period.

[0060] Finally, for each air pressure variation interval, the air pressure values ​​corresponding to each time point in the air pressure variation interval are used to calculate the variance of the air pressure variation interval, so as to obtain the state retention degree in the air pressure variation interval.

[0061] Through this embodiment, the pressure change image is analyzed to obtain multiple pressure change intervals corresponding to the first time period. Then, the state retention degree is calculated for each pressure change interval. This helps to use the state retention degree in each pressure change interval to accurately analyze the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine.

[0062] As an optional embodiment, S203 may specifically include:

[0063] According to the corresponding air pressure values ​​at each moment in the air pressure change interval, the air pressure change trend in the air pressure change interval is obtained;

[0064] The principal component analysis of the air pressure change trend is performed to obtain the air pressure trend line corresponding to the air pressure change trend;

[0065] Accumulate the corresponding air pressure values ​​at each moment within the air pressure change range to obtain the target air pressure accumulated value;

[0066] The accumulated target air pressure value is multiplied by the slope of the corresponding air pressure trend line to obtain the state retention degree of the vacuum chamber of the vacuum packaging machine in the air pressure change range.

[0067] In this embodiment, the air pressure variation trend is a curve formed by connecting the corresponding air pressure values ​​at each time within the air pressure variation interval.

[0068] As an example, the state retention degree can be determined by the following formula (1):

[0069] (1)

[0070] In the formula, represents the state maintenance degree in the jth air pressure change interval, It represents the slope of the pressure trend line in the jth pressure change interval, It represents the air pressure value at the i-th moment in the j-th air pressure change interval. It means that there are n moments in the j-th air pressure change interval. is the sum of the air pressure values ​​at all times in the jth air pressure variation interval.

[0071] The slope of the pressure trend line is There are positive and negative points. When it is greater than 0, it means that the pressure change range is increasing. When it is less than 0, it indicates that the pressure change interval is a trend of decreasing pressure. When the pressure is increasing, the greater the sum of the pressure values ​​at all times in the pressure change interval, the greater the state retention degree in the pressure change interval.

[0072] The state maintenance degree in the jth air pressure change interval It is used to characterize the stability of the air pressure value in the jth air pressure change interval. By analyzing the state maintenance degree in each air pressure change interval, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine can be determined.

[0073] Through this embodiment, the pressure change trend in the pressure change interval is analyzed by using the corresponding pressure values ​​at each moment in the pressure change interval. According to the pressure change trend, the state retention degree of the vacuum chamber of the vacuum packaging machine in the pressure change interval can be accurately determined. This helps to analyze the state retention degree later and accurately judge the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine.

[0074] As an optional embodiment, Figure 3 As shown, S103 may specifically include the following S301-S304.

[0075] S301, arranging each air pressure change interval in chronological order to obtain an interval sequence;

[0076] S302, determining the temperature interference degree of the food temperature on the vacuum chamber of the vacuum packaging machine by using the state maintenance degree in each air pressure change interval in the interval sequence;

[0077] S303, obtaining the condensed water interference degree of the condensed water on the vacuum chamber of the vacuum packaging machine according to the state maintenance degree in each second air pressure change interval in the interval sequence, the second air pressure change interval being each air pressure change interval in the last half of the interval sequence;

[0078] S304, obtaining the environmental interference degree of the packaging environment to the vacuum chamber of the vacuum packaging machine according to the temperature interference degree and the condensed water interference degree.

[0079] In this embodiment, the temperature interference degree is used to characterize the degree of interference of the food temperature on the air pressure of the vacuum chamber of the vacuum packaging machine. In an open environment, the higher the temperature, the lower the air pressure; in a closed environment, the higher the temperature, the higher the air pressure. When packaging food, the temperature of the food will affect the temperature in the vacuum chamber, thereby affecting the air pressure in the vacuum chamber.

[0080] When the temperature of packaged food is overheated, at the beginning of evacuating the vacuum chamber, the air pressure in the vacuum chamber will increase because in a closed environment, the higher the temperature, the higher the air pressure, which will reduce the rate of pressure reduction in the vacuum chamber, making it take more time for the air pressure in the vacuum chamber to drop to the required pressure, thus affecting the judgment of air leakage in the vacuum chamber, making the result obtained when judging the air leakage of the vacuum chamber by air pressure more serious than the actual situation.

[0081] When the temperature of the packaged food is too cold, the temperature and condensation of water vapor in the vacuum chamber will cause a sudden drop in air pressure in the vacuum chamber, which will cause the rate of pressure reduction in the vacuum chamber to become faster, thereby reaching the required air pressure for vacuuming the vacuum chamber more quickly.

[0082] The condensation water interference degree is used to characterize the degree of interference of water vapor condensation in the vacuum chamber on the air pressure of the vacuum chamber of the vacuum packaging machine. When the temperature of the continuously vacuumed food is low, the nearby water vapor will be enriched in the vacuum chamber, causing the humidity in the vacuum chamber to be high. When the humidity in the vacuum chamber is high enough, when the air pressure in the vacuum chamber of the vacuum packaging machine drops to a certain level, the problem of water vapor condensation will occur, causing the air pressure in the vacuum chamber to drop suddenly, so that the air leakage in the vacuum chamber is concealed or the air leakage is judged to be smaller than the actual situation.

[0083] As an example, after obtaining each air pressure variation interval in the first time period, the air tightness detection device sorts the air pressure variation intervals in chronological order, thereby obtaining an interval sequence corresponding to the first time period.

[0084] Then, since the influence of food temperature on air pressure is mainly manifested in the initial period of vacuum chamber evacuation, the difference between the state retention degree in the first air pressure change interval in the interval sequence and the state retention degree in other air pressure change intervals is calculated, and then the differences are accumulated to obtain the average value, which is used as the temperature interference degree of food temperature on the vacuum chamber of the vacuum packaging machine.

[0085] Then, since the influence of water vapor condensation on the air pressure is mainly manifested in the period after the vacuum chamber is evacuated, the state retention degree of each air pressure change interval in the last half of the interval sequence is obtained, and the smallest state retention degree is taken as the condensation water interference degree of the condensed water on the vacuum chamber of the vacuum packaging machine.

[0086] Finally, the temperature interference degree is added to the condensed water interference degree to obtain the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine.

[0087] Through this embodiment, the temperature interference degree of the food temperature on the vacuum chamber of the vacuum packaging machine and the condensed water interference degree of the condensed water on the vacuum chamber of the vacuum packaging machine are considered, so as to accurately obtain the air pressure interference degree of the vacuum chamber of the vacuum packaging machine caused by the packaging environment. This helps to eliminate the interference of the packaging environment in the future, accurately analyze the air tightness of the vacuum chamber of the vacuum packaging machine, and improve the accuracy of the detection results.

[0088] As an optional embodiment, S302 may specifically include:

[0089] Calculate the difference between the state retention degree in the first air pressure change interval in the interval sequence and the state retention degree in each other air pressure change interval;

[0090] Accumulate the retention degree differences to obtain the retention degree accumulation value;

[0091] The temperature interference degree of the food temperature on the vacuum chamber of the vacuum packaging machine is obtained by multiplying the state retention degree in the first air pressure change interval in the interval sequence with the accumulated value of the retention degree.

[0092] In this embodiment, the temperature interference degree can be determined by the following formula (2):

[0093] (2)

[0094] In the formula, represents the temperature disturbance in the pressure change image of the first time period, Indicates the state retention degree in the first air pressure change interval. represents the state maintenance degree in the jth air pressure change interval, and n represents the total number of air pressure change intervals in the air pressure change image of the first time period.

[0095] in, It indicates the cumulative value of the difference between the state retention degree in the first pressure change interval and the state retention degree in the remaining pressure change intervals. The larger the cumulative value, the greater the interference of food temperature on the vacuum chamber of the vacuum packaging machine.

[0096] Temperature disturbance in the pressure change image of the first time period The larger the value is, the greater the environmental interference of the packaging environment on the vacuum chamber of the vacuum packaging machine.

[0097] Through this embodiment, the difference between the state retention degree in the first pressure change interval in the interval sequence and the state retention degree in other pressure change intervals can be used to accurately calculate the temperature interference degree of the vacuum chamber of the vacuum packaging machine by the food temperature. This helps to eliminate the interference of the food temperature in the subsequent process, accurately analyze the airtightness of the vacuum chamber of the vacuum packaging machine, and improve the accuracy of the detection results.

[0098] As an optional embodiment, S304 may specifically include:

[0099] Normalizing the temperature interference degree to obtain a normalized temperature interference degree;

[0100] The condensed water interference degree is normalized to obtain a normalized condensed water interference degree;

[0101] The normalized temperature interference degree and the normalized condensed water interference degree are added together to obtain the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine.

[0102] In this embodiment, the environmental interference degree can be determined by the following formula (3):

[0103] (3)

[0104] In the formula, represents the environmental interference degree in the air pressure change image of the first time period, represents the temperature disturbance in the pressure change image of the first time period, represents the condensation water interference in the air pressure change image of the first time period, Indicates normalization processing.

[0105] in, It indicates the cumulative value of temperature interference and condensation water interference. The greater the temperature interference or the condensation water interference, the greater the environmental interference.

[0106] Environmental interference The larger the value, the greater the interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine. According to the environmental interference degree, each air pressure change interval corresponding to the first time period can be corrected to obtain the accurate first leakage degree of the first time period.

[0107] Through this embodiment, the temperature interference degree and the condensed water interference degree are normalized and then added together, so that an accurate environmental interference degree can be obtained, which is helpful for correcting each air pressure change interval corresponding to the first time period through the environmental interference degree, so as to obtain an accurate first leakage degree in the first time period.

[0108] As an optional embodiment, S104 may specifically include:

[0109] Calculate the slope difference between the pressure trend lines corresponding to two adjacent pressure change intervals in the first time period;

[0110] Accumulate each slope difference to obtain a slope difference accumulation value;

[0111] According to the accumulated value of the slope difference, the environmental interference degree and the target time for the vacuum chamber of the vacuum packaging machine to reach the preset air pressure threshold within the first time period, the first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period is obtained.

[0112] In this embodiment, the preset air pressure threshold is the air pressure value corresponding to the air pressure requirement reached during vacuuming.

[0113] As an example, the first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period can be determined by the following formula (4):

[0114] (4)

[0115] Wherein, E represents the first air leakage degree of the vacuum chamber of the vacuum packaging machine corresponding to the first time period, t represents the target time for the vacuum chamber of the vacuum packaging machine to reach the preset air pressure threshold in the first time period, n represents the total number of air pressure change intervals in the air pressure change image of the first time period, It represents the slope of the pressure trend line in the jth pressure change interval, It represents the slope of the pressure trend line in the j+1th pressure change interval, Indicates the environmental interference degree in the air pressure change image of the first time period.

[0116] in, It is used to indicate the degree of gradual decrease in the rate of pressure reduction in a continuous vacuum state. The larger the value, the slower the rate of pressure reduction in a continuous vacuum state, and the more it conforms to the reaction when there is a leak.

[0117] The larger the first air leakage degree E corresponding to the vacuum chamber of the vacuum packaging machine in the first time period is, the more serious the air leakage degree of the vacuum chamber of the vacuum packaging machine in the first time period is, and the greater the air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine is.

[0118] Through this embodiment, the pressure trend line corresponding to each pressure change interval in the first time period is analyzed, and the first air leakage degree corresponding to the vacuum chamber of the vacuum packaging machine in the first time period can be accurately obtained. This helps to use the first air leakage degree to accurately analyze the air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine in the subsequent use.

[0119] As an optional embodiment, S105 may specifically include:

[0120] Calculate the difference between the first air leakage corresponding to the first time period and the second air leakage corresponding to each second time period to obtain a plurality of air leakage difference values;

[0121] The leakage differences are accumulated to obtain the leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine.

[0122] In this embodiment, the air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine can be determined by the following formula (5):

[0123] (5)

[0124] In the formula, It indicates the leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine monitored for the kth time. Indicates the first air leakage corresponding to the vacuum chamber of the vacuum packaging machine monitored for the kth time. It indicates the second air leakage degree corresponding to the vacuum chamber of the vacuum packaging machine monitored for the kmth time, and N indicates the number of the second time periods.

[0125] in, It is used to indicate the sum of the difference in air leakage between the vacuum chamber of the vacuum packaging machine during the current monitoring and the previous N monitorings. The larger the value is, the greater the air leakage degree of the vacuum chamber of the vacuum packaging machine is.

[0126] The leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine monitored for the kth time The larger the value is, the more the vacuum chamber of the vacuum packaging machine needs to be repaired.

[0127] Through this embodiment, the difference is calculated based on the first leakage degree corresponding to the first time period and the second leakage degree corresponding to each second time period, so as to accurately obtain the current leakage inspection degree of the vacuum chamber of the vacuum packaging machine, thereby accurately completing the airtightness detection of the vacuum chamber of the vacuum packaging machine.

[0128] Based on the air tightness detection method for plastic packaging containers for food, accordingly, the present application also provides a specific embodiment of the air tightness detection system for plastic packaging containers for food.

[0129] As an optional embodiment, a system for detecting air tightness of a plastic packaging container for food includes a vacuum packaging machine, an air pressure sensor, and an air tightness detection device;

[0130] Vacuum packaging machines, used to vacuum plastic pack food;

[0131] An air pressure sensor is used to obtain the corresponding air pressure value of the vacuum chamber of the vacuum packaging machine at each moment;

[0132] An airtightness testing device is used to implement the airtightness testing method for plastic packaging containers for food provided in any one of the above aspects.

[0133] In this embodiment, the vacuum packaging machine is composed of an organic glass cover, a vacuum chamber, a machine body electrical control system and a vacuum system. The lower working room is provided with a hot pressing sealing device, the heating component is a nickel-chromium belt, the device is installed on the bakelite hot pressing body and is absolutely insulated from the vacuum chamber, and the bakelite hot pressing frame is closely attached to the airbag. Before heat sealing, the airbag is in a vacuum state. During heat sealing, the airbag is connected to the atmosphere through an electromagnetic valve to generate a pressure difference, so that the airbag becomes larger, the heating component is lifted up, the sealing bag is pressed tightly, and the heat is heated at the same time to complete the sealing.

[0134] The main sensing element of the air pressure sensor of the air compressor is a film that is sensitive to the strength of the air pressure and a pin opening control. At the same time, it is connected to a flexible resistor in the circuit. When the pressure of the measured gas decreases or increases, the film deforms and drives the pin, and the resistance value of the flexible resistor will change. The 0-5V signal voltage is obtained from the sensor element as the input signal, and the result is transmitted to the computer after A / D conversion into a digital signal that the computer can recognize.

[0135] The airtightness detection device is connected to the vacuum packaging machine and the air pressure sensor, and is used to execute the airtightness detection method for plastic packaging containers for food provided in any one of the above aspects.

[0136] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0137] It should also be noted that the exemplary embodiments mentioned in the present invention describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiments, or in a different order from the embodiments, or several steps can be performed simultaneously.

[0138] The above is only a specific implementation of the present invention. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system, module and unit described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be covered within the protection scope of the present invention.

Claims

1. A method for detecting air tightness of a plastic food packaging container, characterized in that: The method comprises: Acquire an image of air pressure change in a vacuum chamber of a vacuum packaging machine during a first time period; Determining the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period by using the air pressure change image; Obtaining an environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine according to the state maintenance degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period; Determine a first air leakage degree corresponding to the vacuum chamber of the vacuum packaging machine in the first time period by using the environmental interference degree and each of the air pressure change intervals; Determine the leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine by using the first leakage degree of the vacuum chamber of the vacuum packaging machine in the first time period and the second leakage degree of the vacuum chamber of the vacuum packaging machine in each second time period, wherein the second time period is a historical time period before the first time period; The determining, using the air pressure change image, the state retention degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period includes: Determine each extreme value of air pressure in the vacuum chamber of the vacuum packaging machine within the first time period by using the air pressure variation image; According to each air pressure extreme value in the first time period, the air pressure change image is segmented to obtain a plurality of air pressure change intervals corresponding to the first time period; Obtaining the air pressure change trend in the air pressure change interval according to the corresponding air pressure values ​​at each moment in the air pressure change interval; Performing principal component analysis on the air pressure variation trend to obtain an air pressure trend straight line corresponding to the air pressure variation trend; Accumulating the corresponding air pressure values ​​at each time within the air pressure variation interval to obtain a target air pressure accumulated value; The target air pressure accumulated value is multiplied by the slope of the corresponding air pressure trend line to obtain the state retention degree of the vacuum chamber of the vacuum packaging machine in the air pressure change range.

2. The method for detecting air tightness of a plastic food packaging container according to claim 1, characterized in that: The step of acquiring an image of air pressure variation of a vacuum chamber of a vacuum packaging machine in a first time period includes: Using an air pressure sensor, obtaining the corresponding air pressure value of the vacuum chamber of the vacuum packaging machine at each time in the first time period; According to the corresponding air pressure values ​​at each moment in the first time period, an air pressure change image of the vacuum chamber of the vacuum packaging machine in the first time period is constructed.

3. The method for detecting air tightness of a plastic food packaging container according to claim 1, characterized in that: The obtaining, according to the state maintenance degree of the vacuum chamber of the vacuum packaging machine in each air pressure change interval corresponding to the first time period, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine comprises: Arranging the air pressure change intervals in chronological order to obtain an interval sequence; Determine the temperature interference degree of the vacuum chamber of the vacuum packaging machine caused by the temperature of the food by using the state maintenance degree in each of the air pressure change intervals in the interval sequence; According to the state maintenance degree in each second air pressure change interval in the interval sequence, the condensed water interference degree of the condensed water on the vacuum chamber of the vacuum packaging machine is obtained, and the second air pressure change interval is each of the air pressure change intervals in the last half of the interval sequence; According to the temperature interference degree and the condensed water interference degree, the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine is obtained.

4. The method for detecting air tightness of a plastic food packaging container according to claim 3, characterized in that: The method of determining the temperature interference degree of the food temperature on the vacuum chamber of the vacuum packaging machine by utilizing the state maintenance degree in each of the air pressure change intervals in the interval sequence comprises: Calculate the difference between the state maintenance degree in the first air pressure change interval in the interval sequence and the state maintenance degree in each of the other air pressure change intervals; Accumulating the retention degree differences to obtain a retention degree cumulative value; The state retention degree in the first air pressure change interval in the interval sequence is multiplied by the accumulated value of the retention degree to obtain the temperature interference degree of the food temperature on the vacuum chamber of the vacuum packaging machine.

5. The method for detecting air tightness of a plastic food packaging container according to claim 3, characterized in that: The step of obtaining the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine according to the temperature interference degree and the condensed water interference degree includes: Normalizing the temperature interference degree to obtain a normalized temperature interference degree; Normalizing the condensed water interference degree to obtain a normalized condensed water interference degree; The normalized temperature interference degree is added to the normalized condensed water interference degree to obtain the environmental interference degree of the packaging environment on the vacuum chamber of the vacuum packaging machine.

6. The method for detecting air tightness of a plastic food packaging container according to claim 1, characterized in that: The determining, by using the environmental interference degree and each of the air pressure change intervals, a first air leakage degree corresponding to the vacuum chamber of the vacuum packaging machine in the first time period includes: Calculating the slope difference between the air pressure trend lines corresponding to two adjacent air pressure change intervals in the first time period; Accumulating the slope differences to obtain a slope difference accumulation value; A first air leakage degree of the vacuum chamber of the vacuum packaging machine in the first time period is obtained according to the accumulated value of the slope difference, the environmental interference degree and the target time for the vacuum chamber of the vacuum packaging machine to reach a preset air pressure threshold in the first time period.

7. The method for detecting air tightness of a plastic food packaging container according to claim 1, characterized in that: The determining the leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine by using the first leakage degree corresponding to the vacuum chamber of the vacuum packaging machine in the first time period and the second leakage degree corresponding to the vacuum chamber of the vacuum packaging machine in each second time period comprises: Calculate the difference between the first air leakage corresponding to the first time period and the second air leakage corresponding to each of the second time periods to obtain a plurality of air leakage difference values; The air leakage difference values ​​are accumulated to obtain the air leakage inspection degree corresponding to the vacuum chamber of the vacuum packaging machine.

8. A food plastic packaging container air tightness detection system, characterized in that: The system includes a vacuum packaging machine, an air pressure sensor and an air tightness detection device; The vacuum packaging machine is used to perform vacuum plastic packaging on food; The air pressure sensor is used to obtain the air pressure value corresponding to the vacuum chamber of the vacuum packaging machine at each moment; The airtightness detection equipment is used to perform the airtightness detection method for plastic packaging containers for food as described in any one of claims 1 to 7.

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