A kind of degradable plastic packaging bag air permeability detection equipment

Abstract

The application discloses a kind of degradable plastic packaging bag air permeability detection equipment, belongs to air permeability detection technical field, including cabinet and upper detection bin, detection bin is formed by fixed seat and pullable loading seat, inside is equipped with bag mouth sealing fixture and air inlet pipe;Loading seat is extracted and put into packaging sample, and bag mouth is sealed by bag mouth sealing fixture, air inlet pipe inflates into bag and makes bag body swell to form high-pressure side, and after loading seat is pushed into fixed seat, it is enclosed to form low-pressure side sealed cavity;Fixed seat is provided with impact assembly that can switch constant pressure loading and impact loading mode, respectively simulate storage stacking extrusion and transportation throw impact working condition, cooperate differential pressure method detection unit and detect gas permeability of bag body two sides in real time.

Description

Technical Field

[0001] This invention relates to the field of air permeability testing technology, specifically to an air permeability testing device for biodegradable plastic packaging bags. Background Technology

[0002] With the advancement of environmental protection policies and the popularization of the concept of sustainable development, biodegradable plastic packaging bags (such as PBAT / PLA blends) have been widely used in many fields such as fresh fruits and vegetables, food preservation, and express delivery. The air permeability of these packaging bags directly determines the shelf life and quality stability of the contents, and is one of the core performance indicators.

[0003] Currently, the air permeability testing of packaging bags mainly uses the differential pressure method or the isobaric method. In the routine testing process, the packaging bag sample is usually laid flat and fixed, and only the air permeability performance of the film layer itself is tested. The actual working conditions of the packaging bag in the actual circulation and use process are not considered. After being loaded with contents, biodegradable packaging bags will be in an inflated state. In addition, during storage, stacking, transportation, sorting, handling and throwing, they will inevitably be subjected to continuous constant pressure or repeated impact. These external forces will directly change the microstructure of the bag wall material, resulting in a significant change in air permeability, which in turn affects the preservation effect of the contents.

[0004] In existing technologies, the testing of air permeability of packaging bags is mostly a routine test that is "static and without external force". It can only obtain the inherent air permeability of the bag material itself and cannot simulate the air permeability under the inflated state in actual use. This results in the test results being out of touch with the actual use scenario of the packaging bag, and the test data lacks accuracy and reference value. It is difficult to meet the needs of large-scale production and accurate testing of biodegradable packaging bags. Summary of the Invention

[0005] The technical solution of the present invention is to provide a device for testing the air permeability of biodegradable plastic packaging bags, which can simulate the conditions of warehousing stacking and compression and transportation throwing and impact, and detect the gas permeability on both sides of the bag in real time with the pressure difference detection unit.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a device for testing the air permeability of biodegradable plastic packaging bags, comprising: The cabinet has a testing chamber on top, and the testing chamber is equipped with a bag-mouth sealing clamp and an air inlet pipe. The testing chamber consists of a fixed base and a loading base; The loading seat can be pulled out to insert the packaging bag sample, and the bag opening is held by the bag mouth sealing clamp. The air inlet pipe passes through the bag mouth sealing clamp and connects to the inside of the bag, which is used to inflate and pressurize the bag, causing the bag to expand and form a high-pressure side. After the loading seat is inserted into the fixing seat, the two together enclose and form a low-pressure side sealing cavity, and the low-pressure side is formed between the low-pressure side sealing cavity and the outside of the bag body; The fixed base is equipped with an impact assembly, which has a constant pressure loading mode and an impact loading mode. Constant pressure loading mode: A constant pressure is continuously applied to the inflated bag to simulate long-term pressure conditions; Impact loading mode: Apply continuous reciprocating impact to the inflated bag to simulate the throwing impact condition; The testing chamber is equipped with a pressure differential permeability testing unit, which is used to detect the gas permeability between the high-pressure side and the low-pressure side.

[0007] As a further embodiment of the present invention, the impact assembly includes a reciprocating drive mechanism and a pressure plate. The reciprocating drive mechanism drives the pressure plate to abut against the outer wall of the bag body, applying a continuous and constant pressure to the bag body. The pressure plate is provided with a ventilation hole.

[0008] As a further embodiment of the present invention, an elastic energy storage component is provided between the movable end of the reciprocating drive mechanism and the pressure plate, and a blocking component is provided inside the fixed base. In the impact loading mode, the reciprocating drive mechanism drives the pressure plate to move downward, compressing the elastic energy storage component to store energy. When the preload applied by the elastic energy storage component to the pressure plate overcomes the resistance of the blocking component to the pressure plate, the pressure plate passes the obstruction of the blocking component, the elastic energy storage component releases the stored energy, and drives the pressure plate to quickly impact the outer wall of the bag, thereby achieving continuous reciprocating impact on the bag.

[0009] As a further aspect of the present invention, the blocking component includes, The mounting base is fixedly installed inside the fixed base; The slide is slidably mounted on the mounting base; The barrier is slidably mounted on the mounting base and elastically connected to the slide base. Both the upper and lower ends of the barrier are provided with chamfers. The drive assembly, mounted on the fixed base, is used to drive the slide to move along the length of the fixed base.

[0010] As a further embodiment of the present invention, the driving assembly includes a driving motor and a driving screw, wherein the output shaft of the driving motor is fixedly connected to the driving screw, and the driving screw is threadedly connected to the slide block.

[0011] As a further aspect of the present invention, the elastic energy storage component includes, The drive frame is fixedly connected to the movable end of the reciprocating drive mechanism; The driven frame is fixedly connected to the pressure plate; A guide rod is threadedly connected to the drive frame, and a trigger plate is fixedly mounted on the top of the guide rod through the driven frame. The energy storage spring is fixedly installed between the drive frame and the driven frame.

[0012] As a further embodiment of the present invention, the side wall of the fixed seat is provided with a horizontally arranged groove, the side wall of the loading seat is fixedly connected to a pressure-drawing pipe that is slidably arranged with the horizontal groove, the fixed seat is slidably provided with a cover plate, the side wall of the cover plate is provided with a guide groove that is slidably engaged with the pressure-drawing pipe, the guide groove is composed of a horizontal section and an inclined section, the guide groove is used to make the cover plate automatically close the detection chamber when the loading seat is inserted, and automatically open the cover plate when it is pulled out.

[0013] As a further embodiment of the present invention, a linear drive mechanism is provided inside the cabinet, the linear drive mechanism being used to drive the loading seat to reciprocate; the linear drive mechanism includes a reciprocating motor and a reciprocating screw, the output shaft of the reciprocating motor being fixedly connected to the reciprocating screw, and the reciprocating screw being threadedly connected to the loading seat.

[0014] As a further aspect of the present invention, the bag opening sealing clamp includes, The upper clamping plate and the lower clamping plate are elastically slidably disposed within the loading seat; The pressure bar is fixedly mounted on the upper clamping plate; The system includes a synchronizing gear and a synchronizing rack. The synchronizing gear is rotatably mounted inside the loading seat. There are at least two synchronizing racks, which are respectively fixedly mounted on the upper clamping plate and the lower clamping plate to achieve synchronous opposite clamping of the bag opening by the upper clamping plate and the lower clamping plate.

[0015] As a further aspect of the present invention, the air permeability detection unit includes a pressure sensor disposed on the low-pressure side, the pressure sensor being used to collect pressure change data on the low-pressure side.

[0016] Compared with the prior art, the beneficial effects of the present invention are: In this invention, the packaging bag samples are tested under an inflated state to realistically reproduce the actual usage form of the packaging bag after it is filled with goods. Two working modes, constant pressure loading and impact loading, are set up to simulate real external force conditions such as warehousing stacking and transportation sorting and throwing. During the application of external force, the pressure difference method is used simultaneously to detect the pressure change between the high-pressure side and the low-pressure side and to calculate the air permeability. This accurately reflects the impact of external force on the microstructure and air permeability of the bag, effectively solving the problem that traditional static testing can only test the inherent air permeability of the material and is disconnected from actual usage scenarios. This significantly improves the authenticity and reference value of the test data, providing testing support for the quality control and large-scale production of biodegradable packaging bags. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall cross-sectional structure of the present invention; Figure 3 For the present invention Figure 2 Enlarged structural diagram at point A in the middle; Figure 4 For the present invention Figure 2 Enlarged structural diagram at point B; Figure 5 This is a schematic diagram of the overall structure of the detection chamber of the present invention; Figure 6 This is a schematic diagram of the cross-sectional structure of the loading seat of the present invention; Figure 7 For the present invention Figure 6 Enlarged structural diagram at point C; Figure 8 This is a schematic diagram of the cross-sectional structure of the fixing seat of the present invention; Figure 9 This is a schematic diagram of the elastic energy storage component structure of the present invention; Figure 10 This is a schematic diagram of the blocking component and its connection structure according to the present invention; Figure 11 This is a schematic diagram of the overall exploded structure of the detection chamber of the present invention; The attached diagram lists the components represented by each number as follows: 1. Detection chamber; 11. Fixed seat; 12. Loading seat; 13. Horizontal groove; 14. Pressure suction pipe; 15. Cover plate; 16. Horizontal section; 17. Inclined section; 2. Bag mouth sealing clamp; 21. Air inlet pipe; 22. Upper clamping plate; 23. Lower clamping plate; 24. Pressure rod; 25. Synchronous gear; 26. Synchronous rack; 3. Impact assembly; 31. Pressure plate; 32. Reciprocating drive mechanism; 4. Elastic energy storage component; 41. Drive frame; 42. Driven frame; 43. Guide rod; 44. Trigger plate; 45. Energy storage spring; 5. Barrier assembly; 51. Mounting seat; 52. Slide seat; 53. Barrier component; 6. Drive assembly; 61. Drive motor; 62. Drive screw; 7. Linear drive mechanism; 71. Reciprocating motor; 72. Reciprocating screw. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1-11 The present invention provides a technical solution comprising: The cabinet has a testing chamber 1 on top, and a bag-mouth sealing clamp 2 and an air inlet pipe 21 are installed inside the testing chamber 1. The loading seat 12 can be pulled out relative to the fixed seat 11 to place the biodegradable plastic packaging bag sample to be tested into the testing chamber 1. After the packaging bag sample is placed in, the bag opening is clamped and sealed by the bag mouth sealing clamp 2 to achieve the airtightness of the bag body. The air inlet pipe 21 passes through the bag mouth sealing clamp 2 and extends into the bag body. During the test, gas is introduced into the bag body through the air inlet pipe 21 and pressurized, causing the bag body to expand and unfold in the testing chamber 1, and the internal space of the bag body forms a high-pressure side for testing. After the loading seat 12 is pushed into the fixing seat 11, the fixing seat 11 and the loading seat 12 cooperate to enclose each other, forming a closed low-pressure side sealed cavity inside the detection chamber 1. This low-pressure side sealed cavity is located outside the bag body and constitutes the low-pressure side for detection. An impact assembly 3 is mounted on the mounting base 11. The impact assembly 3 is configured to have two operating modes: constant pressure loading mode and impact loading mode. In constant pressure loading mode, the impact component 3 applies continuous and constant pressure to the bag body in the inflated state to simulate the actual working conditions of the packaging bag being subjected to long-term pressure during storage, stacking and transportation. In the impact loading mode, the impact component 3 applies continuous reciprocating impacts to the inflated bag to simulate the repeated impacts that the packaging bag is subjected to during sorting, throwing, and handling.

[0021] The testing chamber 1 is also equipped with a pressure difference method air permeability testing unit. During constant pressure loading or impact loading, the testing unit collects the gas permeation parameters between the high pressure side and the low pressure side to detect and obtain the gas permeability of the bag under the corresponding external force conditions, thereby evaluating the air permeability stability of the biodegradable plastic packaging bag under pressure or impact conditions. During testing, the loading seat 12 is first pulled out, and the biodegradable plastic packaging bag sample is placed inside. The bag opening is clamped by the bag mouth sealing clamp 2 to ensure a leak-free seal. Then, air is injected into the bag through the air inlet pipe 21 to inflate the bag to a preset state, forming a stable high-pressure side. Subsequently, the loading seat 12 is inserted into the fixing seat 11, so that the two enclose a sealed low-pressure side cavity, constituting the low-pressure side. According to the testing requirements, the working mode of the impact component 3 is switched, selecting either constant pressure loading mode or impact loading mode to simulate the stress conditions of the packaging bag in actual use. At the same time, the pressure difference method air permeability detection unit is activated to detect the pressure change between the high-pressure side and the low-pressure side in real time. The gas permeability is calculated through the pressure change data, accurately capturing the dynamic changes in the air permeability performance of the bag under constant pressure or impact conditions. The test data, pressure change curve, and air permeability value are recorded simultaneously to complete the test of the air permeability of the biodegradable plastic packaging bag under the corresponding working conditions.

[0022] This invention conducts testing on packaging bag samples under inflated conditions, realistically reproducing the actual usage form of the packaging bag after it is filled with goods. It also features two working modes: constant pressure loading and impact loading, simulating real external force conditions such as warehousing stacking and transportation sorting. During the application of external force, the differential pressure method is used to simultaneously detect the pressure change between the high-pressure and low-pressure sides and calculate the air permeability. This accurately reflects the impact of external force on the bag's microstructure and air permeability, effectively solving the problem that traditional static testing can only test the inherent air permeability of the material and is disconnected from actual usage scenarios. This significantly improves the authenticity and reference value of the test data, providing testing support for the quality control and large-scale production of biodegradable packaging bags.

[0023] As a further embodiment of the present invention, the impact component 3 includes a reciprocating drive mechanism 32 and a pressure plate 31; the reciprocating drive mechanism 32 adopts a linear drive motor or cylinder, and its output end is connected to the pressure plate 31 in a transmission connection, which can drive the pressure plate 31 to approach or move away from the outer wall of the bag in a vertical direction. In constant pressure loading mode, the reciprocating drive mechanism 32 drives the pressure plate 31 to move downward and continuously abut against the outer wall of the bag in an expanded state. The pressure plate 31 applies a continuous and constant pressure to the bag, simulating the real working condition of the packaging bag being subjected to long-term pressure during storage, stacking, and transportation. To ensure the smooth progress of air permeability testing, the pressure plate 31 is provided with a ventilation hole, which is connected to the low-pressure side sealed cavity in the testing chamber 1. This ensures that the gas on the high-pressure side can smoothly permeate through the bag wall to the low-pressure side, avoiding distortion of air permeability test data due to obstruction by the pressure plate 31, and ensuring the accuracy of the differential pressure air permeability testing unit.

[0024] As a further embodiment of the present invention, an elastic energy storage component 4 is provided between the movable end of the reciprocating drive mechanism 32 and the pressure plate 31, and a blocking component 5 is provided in the fixed base 11. In the impact loading mode, the reciprocating drive mechanism 32 drives the pressure plate 31 to move downward. The blocking component 5 provides lateral support and resistance to the pressure plate 31, hindering its descent. During this process, the elastic energy storage component 4 is gradually compressed and accumulates elastic potential energy, achieving energy storage. The preload applied by the elastic energy storage component 4 to the pressure plate 31 gradually increases until it overcomes the resistance of the blocking component 5. The pressure plate 31 then passes the blocking limit of the blocking component 5, and the elastic energy storage component 4 instantly releases the stored energy, driving the pressure plate 31 to move rapidly downward and impact the outer wall of the bag. The reciprocating drive mechanism 32 continuously cycles the above actions, enabling the pressure plate 31 to continuously impact the bag, thereby realistically simulating the repeated impact conditions experienced by the packaging bag during transportation, sorting, and throwing. At the same time, the pressure difference method air permeability detection unit monitors pressure changes in real time, accurately reflecting the changes in the air permeability of the bag under impact.

[0025] As a further embodiment of the present invention, the mounting base 51 is fixedly disposed inside the fixed base 11, and is used to provide a mounting and sliding support base for the entire barrier assembly 5; The slide block 52 is slidably mounted on the mounting base 51 and can slide back and forth along the length of the mounting base 51. The barrier 53 is slidably disposed with the mounting base 51, and the barrier 53 and the slide base 52 are elastically connected by a compression spring, so that the barrier 53 can yield and elastically reset when it is squeezed; the upper and lower ends of the barrier 53 are provided with bevels. The elastic energy storage component 4 includes a driven frame 42, which is fixedly connected to the pressure plate 31. The chamfered structure is used to guide the driven frame 42 when the pressure plate 31 drives the driven frame 42 to move past the barrier 53, so as to avoid jamming and ensure that the driven frame 42 can smoothly complete the action of passing past the barrier 53. The drive assembly 6 is mounted on the fixed base 11 and is used to drive the slide 52 to move along the length of the mounting base 51. When it is necessary to switch the impact loading mode or adjust the impact trigger threshold, the drive assembly 6 drives the slide 52 to move. Then, through the compression spring connection between the slide 52 and the blocking member 53, the blocking member 53 is driven to adjust the length of its extension from the mounting base 51, thereby adjusting the blocking resistance of the blocking assembly 5. The longer the length of the blocking member 53 extends from the mounting base 51, the greater the blocking resistance to the driven frame 42, and vice versa, so as to adapt to the impact force requirements under different detection scenarios. When the blocking member 53 is completely retracted into the mounting base 51, it no longer limits the driven frame 42 and the pressure plate 31. The device switches to constant pressure loading mode to ensure that the pressure plate 31 can smoothly abut against the outer wall of the bag and apply constant pressure during constant pressure loading.

[0026] During the operation of the impact loading mode, the reciprocating drive mechanism 32 drives the pressure plate 31 to move downward. The blocking member 53 limits the pressure plate 31 through the driven frame 42, so that the elastic energy storage member 4 is compressed and stores energy. When the pre-tightening force applied by the elastic energy storage member 4 to the driven frame 42 overcomes the resistance of the driven frame 42, the blocking member 53 retracts into the mounting base 51, and the driven frame 42 passes over the obstruction of the blocking member 53. At this time, the elastic energy storage member 4 quickly releases the stored energy, driving the pressure plate 31 to quickly impact the outer wall of the bag, completing one impact action. The reciprocating drive mechanism 32 continuously drives the bag, so as to realize the continuous reciprocating impact of the bag, which truly simulates the repeated impact conditions of the packaging bag being transported and thrown.

[0027] As a further embodiment of the present invention, the drive assembly 6 includes a drive motor 61 and a drive screw 62, the output shaft of the drive motor 61 is fixedly connected to the drive screw 62, and the drive screw 62 is threadedly connected to the slide block 52. The drive motor 61 is fixedly mounted on the fixed base 11. It is a servo motor with adjustable speed and precise positioning. It can precisely control the rotation angle and speed of the drive screw 62, thereby achieving precise adjustment of the moving distance of the slide 52. The drive screw 62 is rotatably mounted on the fixed seat 11 through the bearing seat, and its axis direction is consistent with the length direction of the mounting seat 51. This ensures that when the drive screw 62 rotates, it can drive the slide 52 to slide smoothly back and forth along the length direction of the mounting seat 51 without any deviation or jamming. The slide 52 has an internal threaded hole that matches the drive screw 62. The drive screw 62 and the internal threaded hole of the slide 52 form a threaded transmission engagement, which converts the rotational motion of the drive motor 61 into the linear motion of the slide 52.

[0028] When the blocking resistance of the blocking component 5 needs to be adjusted, the drive motor 61 is started. The output shaft of the drive motor 61 drives the drive screw 62 to rotate in the forward or reverse direction. The drive screw 62 drives the slide 52 to move along the length of the mounting base 51 through the threaded transmission. The slide 52 then drives the blocking component 53 to move synchronously through the compression spring between it and the blocking component 53, adjusting the length of the blocking component 53 extending out of the mounting base 51. Through the precise control of the drive motor 61, the extension length of the blocking component 53 can be steplessly adjusted, thereby precisely controlling the blocking resistance of the blocking component 5 on the driven frame 42. This adapts to the impact detection requirements of biodegradable plastic packaging bags of different thicknesses and materials, ensuring the accuracy and stability of the impact force adjustment. When it is necessary to switch to the constant pressure loading mode, the drive motor 61 drives the drive screw 62 to rotate in the reverse direction, moving the slide 52 and causing the blocking component 53 to retract completely into the mounting base 51, releasing the limit on the driven frame 42 and the pressure plate 31, ensuring the smooth operation of the constant pressure loading mode.

[0029] As a further embodiment of the present invention, the elastic energy storage component 4 includes a drive frame 41, a driven frame 42, a guide rod 43, and an energy storage spring 45; The drive frame 41 is fixedly connected to the movable end of the reciprocating drive mechanism 32, and moves up and down linearly synchronously with the reciprocating drive mechanism 32 to provide power input for the entire elastic energy storage component 4. The driven frame 42 is fixedly connected to the pressure plate 31 and is used to transmit the elastic force to the pressure plate 31 to achieve pressure and impact on the bag.

[0030] The guide rod 43 is threadedly connected to the drive frame 41. The top of the guide rod 43 passes through the driven frame 42 upwards, and a trigger plate 44 is fixedly installed at the top of the guide rod 43. The outer diameter of the trigger plate 44 is larger than the diameter of the through hole on the driven frame 42 through which the guide rod 43 passes. It is used to limit and block the movement, preventing the driven frame 42 from slipping off the top of the guide rod 43 during the up and down movement, and ensuring that a reliable assembly relationship is always maintained between the drive frame 41, the driven frame 42, and the guide rod 43. The energy storage spring 45 is installed between the drive frame 41 and the driven frame 42. When the reciprocating drive mechanism 32 drives the drive frame 41 to move downward and the driven frame 42 is limited by the blocking component 5, the energy storage spring 45 is gradually compressed and stores elastic potential energy. When the force is sufficient to overcome the blocking resistance, the energy storage spring 45 quickly releases energy, pushing the driven frame 42 and the pressure plate 31 downward to impact the bag body, completing a single impact action.

[0031] As a further embodiment of the present invention, a horizontal groove 13 is provided on the side wall of the fixed base 11, and a pressure-drawing pipe 14 is fixedly connected to the side wall of the loading base 12. The pressure-drawing pipe 14 is slidably engaged with the horizontal groove 13 and can move back and forth along the horizontal direction together with the loading base 12. A cover plate 15 is slidably disposed on the fixed base 11. The side wall of the cover plate 15 is provided with a guide groove that slides with the pressure tube 14. The guide groove is composed of a horizontal section 16 and an inclined section 17. When the loading seat 12 is pushed into the fixed seat 11, the pressure suction pipe 14 moves along the horizontal groove 13. At the same time, the pressure suction pipe 14 moves along the horizontal section 16 of the guide groove to the inclined section 17. When the pressure suction pipe 14 moves along the inclined section 17, it pushes the cover plate 15 down, so that the cover plate 15 automatically closes the detection chamber 1, ensuring that a sealed environment is formed inside the detection chamber 1, providing reliable conditions for differential pressure detection on the low-pressure side. When the loading seat 12 is pulled outward, the pressure-drawing pipe 14 moves along the inclined section 17 of the guide groove to the horizontal section 16. During this process, the cover plate 15 is moved upward, so that the cover plate 15 automatically opens the test chamber 1, which is convenient for taking out and putting in the packaged bag sample. Through the cooperation of the pressure-drawing pipe 14 and the guide groove, the pushing and pulling action of the loading seat 12 and the opening and closing action of the cover plate 15 are synchronized. The automatic sealing and opening of the test chamber 1 can be completed without additional drive. The structure is simple and the operation is stable.

[0032] As a further embodiment of the present invention, a linear drive mechanism 7 is provided inside the cabinet. The function of the linear drive mechanism 7 is to drive the loading seat 12 to move smoothly back and forth in the horizontal direction, realize the automatic pushing and pulling of the loading seat 12, replace the manual pushing and pulling operation, improve the automation and accuracy of equipment operation, and adapt to the large-scale testing needs of biodegradable plastic packaging bags. The linear drive mechanism 7 includes a reciprocating motor 71 and a reciprocating screw 72. The reciprocating motor 71 is fixedly installed inside the cabinet and is a servo reciprocating motor, which features precise positioning and smooth operation. It can accurately control the moving distance and speed of the loading seat 12, avoiding uneven force during manual pushing and pulling that could cause the loading seat 12 to shift, jam, or have poor sealing, thus affecting the detection accuracy. The output shaft of the reciprocating motor 71 is fixedly connected to the reciprocating screw 72, ensuring that when the reciprocating motor 71 starts, it can drive the reciprocating screw 72 to rotate synchronously in the forward or reverse direction, achieving stable power transmission. The reciprocating screw 72 is rotatably assembled inside the cabinet through the bearing seat, and its axial direction is consistent with the moving direction of the loading seat 12. The reciprocating screw 72 is threadedly connected to the loading seat 12, and the two form a threaded transmission engagement, which converts the rotational motion of the reciprocating motor 71 into the horizontal linear motion of the loading seat 12. When it is necessary to put in or take out the sample from the packaging bag, the reciprocating motor 71 is started. The output shaft of the reciprocating motor 71 drives the reciprocating screw 72 to rotate in the opposite direction. Through the threaded transmission, the loading seat 12 is pulled outward until it moves to the preset position, which is convenient for the operator to put in or take out the sample. After the sample is placed and clamped and sealed, the reciprocating motor 71 rotates in the forward direction, driving the reciprocating screw 72 to rotate synchronously. This drives the loading seat 12 to push into the fixed seat 11 until the loading seat 12 and the fixed seat 11 are precisely fitted together, forming a sealed low-pressure side sealing cavity to ensure the sealing of the test.

[0033] As a further embodiment of the present invention, the bag opening sealing clamp 2 includes an upper clamping plate 22, a lower clamping plate 23, a pressure rod 24, a synchronous gear 25, and a synchronous rack 26; Both the upper clamping plate 22 and the lower clamping plate 23 are elastically slidably disposed in the loading seat 12 and remain closed in their natural state, which facilitates the initial clamping of the bag opening at the beginning; the pressure rod 24 is fixedly disposed on the upper clamping plate 22 and is used to drive the upper clamping plate 22 upward under the action of external force, thereby realizing the opening of the clamp; Synchronous gear 25 is rotatably mounted inside loading seat 12. At least two synchronous racks 26 are provided, respectively fixedly mounted on upper clamping plate 22 and lower clamping plate 23, and both mesh with synchronous gear 25. When the pressure rod 24 is pulled upward or pushed, the pressure rod 24 drives the upper clamping plate 22 to move upward, and the synchronous racks 26 on the upper clamping plate 22 move accordingly. Under the transmission of synchronous gear 25, the synchronous racks 26 on the lower clamping plate 23 drive the lower clamping plate 23 to move downward, so that the upper clamping plate 22 and the lower clamping plate 23 open synchronously in opposite directions, making it easy to insert the bag opening into the clamp. After the pressure rod 24 is released, the upper clamping plate 22 and the lower clamping plate 23 return to the closed state under the action of elastic force, and synchronously clamp the bag opening in opposite directions, providing a sealing guarantee for the inflation and pressurization of the bag.

[0034] In conjunction with the opening and closing action of the cover plate 15, when the cover plate 15 descends, it will abut against the pressure rod 24, realizing the linkage sealing between the bag mouth sealing clamp 2 and the cover plate 15; specifically, when the loading seat 12 is pushed into the fixed seat 11, the suction pipe 14 moves along the inclined section 17 of the guide groove, pushing the cover plate 15 downward to close the detection chamber 1; when the cover plate 15 is about to seal the loading seat 12, its bottom will simultaneously abut against the top of the pressure rod 24, applying downward pressure to the pressure rod 24, causing the pressure rod 24 to press against the clamp 2. 2. A downward squeezing force is generated, which, through the transmission action of the synchronous gear 25 and the synchronous rack 26, causes the lower clamping plate 23 to move upward; thereby increasing the sealing and clamping force of the upper clamping plate 22 and the lower clamping plate 23 on the bag opening, completely preventing air leakage during the inflation and pressurization process; when the loading seat 12 is pulled out from the fixed seat 11, the pressure rod 24 loses its downward pressure, and the upper clamping plate 22 and the lower clamping plate 23 restore their initial clamping force; while ensuring the sealing effect during testing, it is convenient for operators to pick up and put down the packaging bag samples.

[0035] As a further aspect of the present invention, the air permeability detection unit includes pressure sensors disposed on the high-pressure side and the low-pressure side. The pressure sensors are used to collect pressure change data on the low-pressure side. During the detection process, the high-pressure side maintains a constant air pressure, while the low-pressure side is a closed cavity, forming a stable pressure difference across the bag. Gas slowly permeates through the bag from the high-pressure side to the low-pressure side. The low-pressure side pressure sensor collects pressure change signals in real time and uploads them to the control system. The true air permeability of the bag under constant pressure or impact conditions is calculated through the pressure-time curve, providing accurate data support for the performance evaluation of biodegradable packaging bags.

Claims

1. A device for testing the air permeability of biodegradable plastic packaging bags, characterized in that, include: The cabinet has a testing chamber (1) on top, and a bag-mouth sealing clamp (2) and an air inlet pipe (21) are installed inside the testing chamber (1). The testing chamber (1) consists of a fixed base (11) and a loading base (12); The loading seat (12) can be pulled out to put in the packaging bag sample and the bag opening is clamped by the bag mouth sealing clamp (2). The air inlet pipe (21) passes through the bag mouth sealing clamp (2) and connects to the inside of the bag to inflate and pressurize the bag, so that the bag expands and forms a high pressure side. After the loading seat (12) is inserted into the fixing seat (11), the two together enclose a low-pressure side sealing cavity, and the low-pressure side is formed between the low-pressure side sealing cavity and the outside of the bag body; An impact component (3) is provided on the fixed base (11). The impact component (3) has a constant pressure loading mode and an impact loading mode: constant pressure loading mode: a constant pressure is continuously applied to the bag in the expansion state to simulate long-term pressure conditions. Impact loading mode: Apply continuous reciprocating impact to the inflated bag to simulate the throwing impact condition; The detection chamber (1) is equipped with a pressure difference method air permeability detection unit, which is used to detect the gas permeability between the high pressure side and the low pressure side.

2. The air permeability testing device for biodegradable plastic packaging bags according to claim 1, characterized in that: The impact assembly (3) includes a reciprocating drive mechanism (32) and a pressure plate (31). The reciprocating drive mechanism (32) drives the pressure plate (31) to abut against the outer wall of the bag body and apply a continuous constant pressure to the bag body. The pressure plate (31) has a ventilation hole.

3. The air permeability testing device for biodegradable plastic packaging bags according to claim 2, characterized in that: An elastic energy storage component (4) is provided between the movable end of the reciprocating drive mechanism (32) and the pressure plate (31), and a blocking component (5) is provided inside the fixed base (11). In the impact loading mode, the reciprocating drive mechanism (32) drives the pressure plate (31) to move downward, so that the elastic energy storage component (4) is compressed and stores energy. When the pre-tightening force applied by the elastic energy storage component (4) to the pressure plate (31) overcomes the resistance of the blocking component (5) to the pressure plate (31), the pressure plate (31) passes the obstruction of the blocking component (5), the elastic energy storage component (4) releases the stored energy, and drives the pressure plate (31) to quickly impact the outer wall of the bag, so as to achieve continuous reciprocating impact on the bag.

4. The air permeability testing device for biodegradable plastic packaging bags according to claim 3, characterized in that: The blocking assembly (5) includes a mounting base (51) fixedly disposed within a fixed base (11); The slide (52) is slidably mounted on the mounting base (51); The barrier (53) is slidably disposed with the mounting base (51) and elastically connected with the slide (52). Both the upper and lower ends of the barrier (53) are provided with bevels. The drive assembly (6) is mounted on the fixed base (11) and is used to drive the slide (52) to move along the length of the fixed base (11).

5. The air permeability testing device for biodegradable plastic packaging bags according to claim 4, characterized in that: The drive assembly (6) includes a drive motor (61) and a drive screw (62). The output shaft of the drive motor (61) is fixedly connected to the drive screw (62), and the drive screw (62) is threadedly connected to the slide (52).

6. The air permeability testing device for biodegradable plastic packaging bags according to claim 3, characterized in that: The elastic energy storage component (4) includes, The drive frame (41) is fixedly connected to the movable end of the reciprocating drive mechanism (32); The driven frame (42) is fixedly connected to the pressure plate (31); The guide rod (43) is threadedly connected to the drive frame (41), and the top of the guide rod (43) passes through the driven frame (42) and is fixedly provided with a trigger plate (44). The energy storage spring (45) is fixedly installed between the drive frame (41) and the driven frame (42).

7. The air permeability testing device for biodegradable plastic packaging bags according to claim 1, characterized in that: The fixed seat (11) has a horizontal groove (13) on its side wall. The loading seat (12) has a pressure-drawing pipe (14) that is slidably connected to the side wall of the loading seat (12). The fixed seat (11) has a cover plate (15) that is slidably provided. The cover plate (15) has a guide groove on its side wall that is slidably engaged with the pressure-drawing pipe (14). The guide groove is composed of a horizontal section (16) and an inclined section (17). The guide groove is used to make the cover plate (15) automatically close the detection chamber (1) when the loading seat (12) is inserted and automatically open when it is withdrawn.

8. The air permeability testing device for biodegradable plastic packaging bags according to claim 1, characterized in that: The cabinet is equipped with a linear drive mechanism (7), which is used to drive the loading seat (12) to move back and forth. The linear drive mechanism (7) includes a reciprocating motor (71) and a reciprocating screw (72). The output shaft of the reciprocating motor (71) is fixedly connected to the reciprocating screw (72), and the reciprocating screw (72) is threadedly connected to the loading seat (12).

9. The air permeability testing device for biodegradable plastic packaging bags according to claim 1, characterized in that: The bag opening sealing clamp (2) includes an upper clamp (22) and a lower clamp (23), both of which are elastically slidably disposed within the loading seat (12); The pressure bar (24) is fixedly mounted on the upper clamping plate (22); Synchronous gear (25) and synchronous rack (26), wherein the synchronous gear (25) is rotatably disposed within the loading seat (12); There are at least two synchronous racks (26) and they are fixedly installed on the upper clamping plate (22) and the lower clamping plate (23) respectively, so as to realize that the upper clamping plate (22) and the lower clamping plate (23) clamp the bag opening synchronously.

10. The air permeability testing device for biodegradable plastic packaging bags according to claim 1, characterized in that: The air permeability detection unit includes a pressure sensor disposed on the low-pressure side, which is used to collect pressure change data on the low-pressure side.

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