Device and method for non-destructive testing of sealing performance of small cigarette box through gas volume transfer method

Abstract

The invention relates to the technical field of cigarette packaging quality detection, and discloses a device and method for non-destructive testing of the sealing performance of a small cigarette box through a gas volume transfer method.The device comprises a sealed measuring cavity, a sample limiting frame, a suction piston, a differential pressure sensor, a small cigarette box sample, a balance valve, a signal collection operation control system and a precise lead screw, the method comprises the following operation steps: calibrating the volume of the sealed measurement cavity as V1; measuring the volume V2 of the cigarette small box sample; recording the initial air volume in the sealed measuring cavity as V3; driving a suction piston to suck air in the sealed measurement cavity through a precision lead screw, recording the air pressure as Pe, and recording the suction capacity as Vp; and the sealing performance is calculated based on the Boyle law. In the detection process, punching is not needed, nondestructive inspection can be achieved, the sample limiting frame evenly distributes local negative pressure through a positioning structure of a six-face semicircular elastic contact, then membrane surface stress concentration is reduced, pressure fracture is avoided, and reliability is high.

Description

Technical Field

[0001] The invention relates to the technical field of cigarette packaging quality detection, in particular to a device and method for non-destructive detection of the sealing performance of a cigarette small box by a gas volume transfer method. Background Art

[0002] Cigarette packaging is the last production link of finished cigarettes. With the development of production technology, the cigarette packaging process mainly uses machines to seal the folded parts at both ends of the cigarette box. Cigarettes with poor sealing will become moldy in a humid environment when stored for a long time, and will become cracked and fragile in a dry climate. At the same time, the aroma of the cigarettes will leak out in large quantities, which directly affects the interests of consumers and the reputation of cigarette manufacturers. In recent years, some consumers have pointed out that some cigarettes have become moldy and cracked. It can be seen that measuring the sealing of cigarette packaging is crucial to improving the cigarette packaging process and improving the sealing of cigarette packaging.

[0003] YQ-JYT 2-2018 "Negative Pressure Vacuum-Water Immersion Method for Determination of Sealing Degree and Leakage Point of Cigarette Boxes" issued by the State Tobacco Monopoly Administration requires punching holes in the cigarette packs, which is a destructive test. Patent CN 112432745A "A Non-destructive Testing Method for Sealing Degree of Cigarette Box Packaging" may cause the sealing film of the cigarette box to burst under the action of negative pressure if the smoking process is not well controlled.

[0004] Based on the above problems, this detection method has been developed to prevent the packaging film of cigarette boxes from bursting when they are in a negative pressure environment. It can detect the sealing degree of cigarette boxes without damage, which can help enterprises improve product quality and reduce production losses. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies in the prior art, the present invention provides a device and method for non-destructive testing of the sealing of cigarette boxes using a gas volume transfer method, which has the advantages of non-destructiveness and high reliability, and solves the problems of destructive testing and easy rupture of the film.

[0007] (II) Technical solution

[0008] In order to achieve the above-mentioned purpose of non-destructive and high-reliability detection, the present invention provides the following technical solutions:

[0009] A device for non-destructively testing the sealing of a cigarette box by a gas volume transfer method comprises a sealed measuring chamber, a sample limiting frame, a suction piston, a pressure difference sensor, a cigarette box sample, a balancing valve, a signal acquisition operation control system and a precision lead screw. The volume of the sealed measuring chamber is greater than the volume of the cigarette box sample, and the precision lead screw is connected to the suction piston and is in a straight line.

[0010] A method for non-destructively testing the sealing performance of a cigarette box by a gas volume transfer method comprises the following steps:

[0011] 1) Record the initial pressure value of the sealed measuring chamber as P0 (normal pressure), and calibrate the volume of the sealed measuring chamber (including the limiting frame and dead zone) as V1;

[0012] 2) Measure the volume V2 of the cigarette box sample (V1>V2);

[0013] 3) Fix the cigarette box sample into the sealed measurement chamber through the sample limiting frame, and record the initial air volume in the sealed measurement chamber as V3, V3 = V1-V2;

[0014] 4) The air in the sealed measuring chamber is sucked by the suction piston driven by the precision screw. The pressure value of the pressure difference sensor and the volume of the suction piston are collected in real time during the suction process. When the suction pressure reaches the set pressure value, the suction is stopped. When the pressure value is stable, the reading of the pressure difference sensor is recorded as Pe, and the suction capacity is recorded as Vp;

[0015] 5) Based on Boyle's law, when the temperature remains constant, the pressure (P) of a certain amount of ideal gas is inversely proportional to its volume (V). Vp is converted to the capacity V4 under the condition of P0, V4 = Vp * (P0-Pe) / P0, where V4-V3 is the air overflowing from the small box. The sealing rate under the specified test conditions is defined as Q = 100% * (V3-V4) / V3. The closer the value of Q is to 100%, the better the sealing effect.

[0016] Preferably, the sealed measuring chamber is made of 304 stainless steel, with an inner wall roughness Ra≤0.8μm, an adjustable volume range of 500-1500mL, and is equipped with a vacuum sealing door and a silicone sealing ring (Shore hardness 70A).

[0017] Preferably, the cigarette box sample is placed in a sealed measuring cavity with the support of a sample limiting rack. The sample limiting rack contacts the six surfaces of the cigarette box sample respectively. The contact part is divided into semicircles (R=3mm) and the surface is covered with a polyurethane elastic layer (thickness 2mm). An adjustable contact pressure of 0.1-0.5MPa is achieved through a gas spring (stroke 50mm, elastic coefficient 20N / mm). The semicircular shape can ensure that there is no damage to the box packaging and prevent the sealing film of the cigarette box sample from bursting during the smoking process. The cigarette box sample is positioned and pressurized by the sample limiting rack to ensure that the negative pressure of the cavity will not cause the sealing film of the cigarette box sample to burst during the suction process of the cavity.

[0018] Preferably, the precision screw is driven by a servo motor with a pitch of 0.5 mm and is equipped with a linear guide rail with an accuracy of ±0.01 mm. The precision screw controls the reciprocating suction of the suction piston.

[0019] Preferably, the differential pressure sensor has a range of -10000 to 0Pa, an accuracy of ±0.1% FS, and a response time of <50ms;

[0020] Preferably, the sealed measurement cavity V1 is calibrated using a standard volume block (accuracy ±0.1%) for multi-point calibration, and the cigarette box sample V2 is measured based on laser scanning 3D reconstruction technology with an accuracy of ±0.5%;

[0021] Preferably, the suction flow control range of the suction piston is 50-500mL / min, the air is pumped to -5000Pa, the time control accuracy is ±0.1s, the pressure is maintained stable (fluctuation ≤±50Pa), the duration is 60±2s, the signal acquisition operation control system collects the internal pressure of the sealed measurement chamber in real time, and records the suction piston displacement data in real time and calculates the air suction capacity, records the pressure change curve (resolution 0.1Pa), and judges the sealing degree of the cigarette box according to the pressure change.

[0022] Compared with the prior art, the present invention provides a device and method for non-destructive detection of the sealing property of cigarette boxes by gas volume transfer method, which has the following beneficial effects:

[0023] 1. The device and method for non-destructive testing of the sealing performance of cigarette boxes by the gas volume transfer method, which uses a suction piston to quantitatively extract and transfer the air in the sealed measuring chamber to reduce the air pressure around the cigarette box sample. After maintaining the pressure for a period of time, the relationship between air pressure and volume is calculated based on Boyle's law. The greater the deviation of the result, the more air leakage the cigarette box sample has. In this process, the cigarette box sample does not need to be punched, thereby achieving non-destructive testing.

[0024] 2. The device and method for nondestructive testing of the sealing of cigarette boxes by the gas volume transfer method evenly distributes the local negative pressure through the positioning structure of the six semicircular elastic contacts of the sample limiting frame, thereby reducing the stress concentration on the membrane surface to avoid compression rupture, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the device of the present invention.

[0026] In the figure: 1. Sealed measuring chamber; 2. Sample limiting rack; 3. Suction piston; 4. Pressure difference sensor; 5. Cigarette box sample; 6. Balance valve; 7. Signal acquisition calculation control system; 8. Precision screw. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1: Standard cigarette box detection

[0029] Parameter settings:

[0030] Pumping pressure: -5000Pa

[0031] Holding time: 60s

[0032] Ambient temperature: 23±1℃

[0033] Relative humidity: 50±5% RH

[0034] Test results:

[0035] Calibration data: V1 = 800.0 mL, V2 = 120.5 mL → V3 = 679.5 mL

[0036] Measured data: Vp = 250.0 mL, Pe = -4980 Pa

[0037] Calculation result: V4 = 250 × (101325-4980) / 101325 = 238.5 mL

[0038] Sealing rate Q = (679.5-238.5) / 679.5×100% = 64.9%

[0039] Example 2: Leakage simulation test

[0040] Microholes with a diameter of 0.1 mm were made on a standard cigarette box, and the test results showed that the Q value dropped to 42.3%, verifying the effectiveness of the method.

[0041] Example 3: Detection of cigarette boxes of different sizes

[0042] Test purpose: To verify the compatibility of the device with cigarette boxes of different specifications

[0043] Test subjects:

[0044] Conventional cigarette box (84mm×54mm×22mm, volume 120.5mL)

[0045] Slim cigarette box (97mm×48mm×18mm, volume 85.2mL)

[0046] Medium cigarette box (89mm×52mm×20mm, volume 93.8mL)

[0047] Parameter settings:

[0048] Pumping pressure: -5000Pa

[0049] Holding time: 60s

[0050] Contact pressure: 0.3MPa

[0051] Test results:

[0052]

[0053] Analysis: The Q value of cigarette boxes of different sizes is stable in the range of 64%-66%, indicating that the device is insensitive to specification differences and the positioning structure has strong adaptability.

[0054] Example 4: Extreme environment testing

[0055] Test purpose: To verify the detection stability under high temperature and high humidity environment

[0056] Test conditions:

[0057] Temperature: 40±1℃

[0058] Relative humidity: 85±5% RH

[0059] Cigarette box type: regular hard box (well sealed)

[0060] Parameter settings:

[0061] Pumping pressure: -5000Pa

[0062] Holding time: 60s

[0063] Dynamic compensation parameters: Enable temperature correction coefficient k = 1 + 0.003 × (40-23) = 1.051

[0064] Test results:

[0065]

[0066] Analysis: The high temperature environment causes gas expansion, and the Q value is underestimated by about 3.2% before correction. Through the temperature compensation algorithm, the Q value returns to the normal range, verifying the necessity of dynamic compensation.

[0067] Example 5: Detection of different leakage types

[0068] Test purpose: To verify the response capability to different forms of leakage

[0069] Simulated leak type:

[0070] 1. Micropore leakage (diameter 0.1mm)

[0071] 2. Crack leakage (length 3mm, width 0.05mm)

[0072] 3. Adhesive layer defects (partial non-bonding)

[0073] Parameter settings:

[0074] Pumping pressure: -5000Pa

[0075] Holding time: 60s

[0076] Ambient temperature: 23℃

[0077] Test results:

[0078]

[0079] Analysis: Different leakage types correspond to characteristic curves, providing data support for the leakage point location algorithm.

[0080] Example 6: Anti-film burst limit test

[0081] Test purpose: To verify the tolerance of the positioning structure to high negative pressure

[0082] Test conditions:

[0083] Cigarette box type: regular hard box (no leakage)

[0084] Pumping pressure: -8000Pa (60% over standard pressure)

[0085] Contact pressure: 0.5MPa

[0086] Test results:

[0087] Continuous test 1000 times, no film rupture

[0088] Average Q value: 64.5% ± 0.7%

[0089] Film surface stress distribution: Maximum stress 1.2MPa (safety threshold 3.5MPa)

[0090] Analysis: The six-sided elastic positioning structure evenly distributes the negative pressure, avoids stress concentration, and breaks through the pressure limitations of traditional methods.

[0091] Example 7: Comparative experiment with water immersion method

[0092] Test purpose: To verify the equivalence of the test methods

[0093] Test object: 200 regular cigarette boxes randomly selected

[0094] Detection method:

[0095] Method of the present invention (Q value)

[0096] Water immersion method (YQ-JYT 2-2018 standard)

[0097] Results comparison:

[0098] Leakage judgment consistency between the two methods: 98.5%

[0099] Linear correlation: R 2 =0.987 (p<0.001)

[0100] Typical difference cases:

[0101] The present invention detected Q = 58% (water immersion method shows tiny bubbles)

[0102] The water immersion method detected 15 boxes with obvious leakage, and the Q value of the present invention was <55%

[0103] Conclusion: The method of the present invention is highly equivalent to the water immersion method and can detect more subtle leaks.

[0104] Example 8: Multi-brand cigarette box detection

[0105] Test purpose: To verify the adaptability to different brands of packaging materials

[0106] Test subjects:

[0107] Brand A (aluminum foil composite film)

[0108] Brand B (aluminized paper)

[0109] Brand C (ordinary cardboard)

[0110] Parameter settings:

[0111] Contact pressure: 0.3MPa (adjusted according to material hardness)

[0112] Pumping pressure: -5000Pa

[0113] Test results:

[0114]

[0115]

[0116] Analysis: The difference in Q values ​​of different materials is due to differences in sealing processes, and the test results are consistent with actual production feedback.

[0117] Example 9: Sealing test after long-term storage

[0118] Test purpose: To verify the applicability of the test method to cigarette packs after long-term storage

[0119] Test conditions:

[0120] Cigarette box type: regular hard box

[0121] Storage conditions: 30°C, 75% RH, 6 months

[0122] Test parameters: standard conditions

[0123] Pumping pressure: -5000Pa

[0124] Holding time: 60s

[0125] Ambient temperature: 23±1℃

[0126] Relative humidity: 50±5% RH

[0127] Test results:

[0128] Q value before storage: 65.0% ± 1.0%

[0129] Q value after storage: 58.2% ± 1.5%

[0130] Characteristics of pressure change curve: The pressure drop rate during the pressure holding stage increases by 0.3Pa / s

[0131] Verification: After storage, the cigarette boxes showed slight mildew, which was consistent with the downward trend of the Q value, proving that the detection method can effectively reflect long-term changes in sealing.

[0132] Example 10: Comparison of different pumping rates

[0133] Test purpose: Optimize the pumping rate parameters

[0134] Test conditions:

[0135] Cigarette box type: regular hard box (no leakage)

[0136] Pumping rate: 50mL / min, 100mL / min, 200mL / min, 300mL / min

[0137] Test results:

[0138]

[0139] Conclusion: When the pumping rate is 200mL / min, the detection efficiency and stability are optimal, which is consistent with the patented technical solution.

[0140] In summary, the device and method for nondestructive testing of the sealing performance of cigarette boxes by the gas volume transfer method quantitatively extracts and transfers the air in the sealed measuring chamber through the suction piston to reduce the air pressure around the cigarette box sample. After maintaining the pressure for a period of time, the relationship between air pressure and volume is verified based on Boyle's law. The greater the deviation of the result, the more air leakage the cigarette box sample has. In this process, the cigarette box sample does not need to be punched, so nondestructive inspection can be achieved. The local negative pressure is evenly distributed through the positioning structure of the six-sided semicircular elastic contacts of the sample limiting frame, thereby reducing the stress concentration on the membrane surface to avoid pressure rupture, and the reliability is high.

[0141] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for nondestructive testing of the sealing performance of cigarette boxes by gas volume transfer method, characterized in that: The invention comprises a sealed measuring chamber (1), a sample limiting frame (2), a suction piston (3), a differential pressure sensor (4), a cigarette box sample (5), a balancing valve (6), a signal acquisition operation control system (7), and a precision lead screw (8); the volume of the sealed measuring chamber (1) is larger than the volume of the cigarette box sample (5); and the precision lead screw (8) is connected to the suction piston (3) and is in a straight line.

2. A method for nondestructive testing of cigarette pack sealing properties using a gas volume transfer method, characterized in that: The following steps are involved: 1) Record the initial pressure value of the sealed measuring chamber (1) as P0 (normal pressure), and calibrate the volume of the sealed measuring chamber (1) (including the limiting frame and the dead zone) as V1; 2) Measure the volume V2 of the cigarette box sample (5) (V1>V2); 3) Fix the cigarette box sample (5) into the sealed measuring chamber (1) through the sample limiting frame (2), and record the initial air volume in the sealed measuring chamber (1) as V3, V3 = V1-V2; 4) driving the suction piston (3) to suck the air in the sealed measuring chamber (1) through the precision lead screw (8), collecting the pressure value of the pressure difference sensor (4) and the volume of the suction piston (3) in real time during the suction process, stopping the suction when the suction pressure reaches the set pressure value, and recording the reading of the pressure difference sensor (4) as Pe when the pressure value is stable, and recording the suction capacity as Vp; 5) Based on Boyle's law, when the temperature remains constant, the pressure (P) of a certain amount of ideal gas is inversely proportional to its volume (V). Vp is converted to the capacity V4 under the condition of P0, V4=Vp*(P0-Pe) / P0, where V4-V3 is the air overflowing from the small box. The sealing rate under the specified test conditions is defined as Q=100%*(V3-V4) / V3. The closer the value of Q is to 100%, the better the sealing effect.

3. The device for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 1, characterized in that: The sealed measuring chamber (1) is made of 304 stainless steel, with an inner wall roughness Ra≤0.8 μm, an adjustable volume range of 500-1500 mL, and is equipped with a vacuum sealing door and a silicone sealing ring (Shore hardness 70A).

4. The device for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 1, characterized in that: The cigarette box sample (5) is supported by the sample limiting frame (2) and placed in the sealed measuring chamber (1). The sample limiting frame (2) contacts the six surfaces of the cigarette box sample (5) respectively. The contact part is divided into semicircles (R=3mm) and the surface is covered with a polyurethane elastic layer (thickness 2mm). An adjustable contact pressure of 0.1-0.5MPa is achieved through a gas spring (stroke 50mm, elastic coefficient 20N / mm). The semicircular shape can ensure that there is no damage to the box packaging and prevent the sealing film of the cigarette box sample (5) from bursting during the smoking process. The cigarette box sample (5) is positioned and pressurized by the sample limiting frame (2), which can ensure that during the suction process of the cavity, the negative pressure of the cavity will not cause the sealing film of the cigarette box sample (5) to burst.

5. The device for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 1, characterized in that: The precision lead screw (8) is driven by a servo motor, has a pitch of 0.5 mm, and is equipped with a linear guide rail with an accuracy of ±0.01 mm. The precision lead screw (8) controls the suction piston (3) to pump back and forth.

6. The device for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 1, characterized in that: The differential pressure sensor (4) has a measuring range of -10000~0Pa, an accuracy of ±0.1% FS, and a response time of <50ms.

7. The method for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 2, characterized in that: The sealed measurement cavity (1) V1 is calibrated using a standard volume block (accuracy ±0.1%) for multi-point calibration, and the cigarette box sample (5) V2 is measured based on laser scanning 3D reconstruction technology with an accuracy of ±0.5%.

8. The method for nondestructive testing of cigarette pack sealing properties by gas volume transfer method according to claim 2, characterized in that: The suction flow control range of the suction piston (3) is 50-500mL / min, and the air is pumped to -5000Pa. The time control accuracy is ±0.1s, and the pressure is maintained stable (fluctuation ≤±50Pa). The duration is 60±2s. The signal acquisition and calculation control system (7) collects the internal pressure of the sealed measurement chamber (1) in real time, and records the displacement data of the suction piston (3) in real time and calculates the air suction capacity, and records the pressure change curve (resolution 0.1Pa). According to the pressure change, the sealing degree of the cigarette box is judged.

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