A method for characterizing mechanical properties of tobacco leaf
By adopting standardized testing methods for the mechanical properties of tobacco leaves, the lack of characterization of the mechanical properties of tobacco leaves has been solved, data comparison and processing parameters have been unified, and the processing breakage rate has been reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-09
AI Technical Summary
The lack of standardized and quantitative methods for characterizing the mechanical properties of tobacco leaves in existing technologies makes it impossible to compare data from different laboratories and to guide the unification and optimization of tobacco processing parameters.
The tensile, tearing, compression, and bending properties of tobacco leaves were tested using a universal testing machine. Outliers were eliminated using the Grubbs method, and standardized mechanical property testing methods were developed, including sample preparation, testing conditions, and data processing, providing clear grading standards.
It achieves full-scenario coverage of the mechanical properties of tobacco leaves, ensures data comparability, guides the adjustment of processing parameters, and reduces the processing breakage rate.
Smart Images
Figure CN122171326A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of tobacco processing technology, specifically referring to a method for characterizing the mechanical properties of tobacco leaves. Background Technology
[0002] Tobacco leaves are a typical flexible fiber material, and their mechanical properties (tensile strength, tear resistance, elastic recovery, and bending resistance) directly affect the breakage rate during processing. For example, insufficient tensile strength can lead to breakage due to tension during conveying, and low bending stiffness can cause unstable gripping by robotic arms during sorting.
[0003] Currently, the evaluation of the mechanical properties of tobacco leaves in the industry relies heavily on experience (such as the perception of "toughness" by manual kneading), and lacks standardized and quantitative characterization methods: existing tests only target a single property (such as only measuring tensile strength), and do not cover the entire processing scenario; moreover, there are no unified standards for test parameters (such as sample size and pressure value), which makes it impossible to compare data from different laboratories and cannot guide the matching of parameters for large-scale processing.
[0004] To address the aforementioned issues, there is an urgent need to establish a characterization method for the mechanical properties of tobacco leaves that covers multiple key mechanical characteristics, standardizes parameters, and quantifies results, thus filling a gap in the industry. Summary of the Invention
[0005] In view of the above situation and to overcome the shortcomings of the prior art, the present invention provides a method for characterizing the mechanical properties of tobacco leaves, which effectively solves the problems currently on the market.
[0006] The technical solution adopted by this invention is as follows: This invention proposes a method for characterizing the mechanical properties of tobacco leaves, comprising the following steps:
[0007] (1) Sample preparation: Samples were taken from the middle part of the tobacco leaves to prepare four types of samples: tensile, tear, compression and bending. At least 5 samples were prepared in each group and equilibrated for 24 hours in an environment with a temperature of 23±2℃ and a relative humidity of 65±5%.
[0008] (2) Mechanical property test: The tensile properties, tear strength, compression rebound rate and bending stiffness are tested by a universal testing machine. The tensile properties include tensile strength, tensile elastic modulus and elongation at break. Each property is calculated by a preset formula.
[0009] (3) Data processing: Outliers are removed using the Grubbs method. The mean ± standard deviation of the valid data is taken, and the characteristics are divided into three levels: excellent, medium and poor according to the processing requirements.
[0010] The dimensions of the four types of samples in step (1) are as follows:
[0011] Tensile specimen: rectangular, 50 mm (gauge length) ) × 10mm (width b) × t (thickness);
[0012] Tear test specimen: rectangular, 100mm×63mm, with a 20mm long pre-made cut in the center;
[0013] Compression specimen: circular, 20mm in diameter, thickness ;
[0014] Bending specimen: rectangular, 80mm (length L) × 15mm (width b) × t (thickness).
[0015] Furthermore, the conditions for the tensile property test in step (2) are: tensile speed 10 mm / min, recording the stress-strain curve; the formula for calculating tensile strength is... ,in For maximum tension, The width of the sample. The thickness is the sample thickness.
[0016] Furthermore, in step (2), the tear strength test uses an Elemendorf tear clamp, and the calculation formula is as follows: ,in For maximum tearing force, The thickness is the sample thickness.
[0017] Furthermore, the conditions for the compression rebound rate test in step (2) are: pressurize to 50 kPa, hold for 30 s, unload and let stand for 60 s; the calculation formula is as follows: ,in For the initial thickness, The thickness after pressure is applied. This is the thickness after restoration.
[0018] Furthermore, the bending stiffness test in step (2) adopts a three-point bending mode, with a support point spacing of 60mm and a pressure head descent speed of 5mm / min; the calculation formula is as follows: ,in L represents the force applied by the pressure head, and L represents the distance between the support points. For deflection, The width of the sample.
[0019] Furthermore, the significance level of the Grubbs method in step (3) is α=0.05; in the characteristic grading, tensile strength >3MPa is excellent, 1.5-3MPa is medium, and <1.5MPa is poor.
[0020] Furthermore, the method for measuring the sample thickness t is as follows: using a digital micrometer with an accuracy of 0.001 mm, three different points are measured in the non-edge area of the sample, and the average value is taken as the final thickness value. The pressure of the micrometer is set to 50 g during the measurement.
[0021] Furthermore, in step (1), environmental equilibration is achieved by a constant temperature and humidity chamber. Temperature and humidity are recorded every 6 hours during the equilibration process. Temperature fluctuation range ≤ ±0.5℃, relative humidity fluctuation range ≤ ±2%RH. After equilibration, the moisture content of the tobacco leaf samples needs to be verified. Moisture content fluctuation ≤ 0.5%.
[0022] Furthermore, the property grading also includes: tear strength >2.5 N / mm is excellent, 2.0~2.5 N / mm is medium, and <2.0 N / mm is poor; bending stiffness >8 N·mm is excellent, 5~8 N·mm is medium, and <5 N·mm is poor; compression resilience >70% is excellent, 60-70% is medium, and <60% is poor.
[0023] The beneficial effects achieved by the present invention using the above structure are as follows:
[0024] Covering all scenarios, it is the first to simultaneously characterize tensile, tearing, compression rebound, and bending stiffness, matching all processing stages of tobacco leaf conveying, shredding, baking, and sorting; it standardizes sample size, testing environment, and parameters to ensure data comparability; it provides clear formulas and grading standards to directly guide the adjustment of processing parameters (e.g., "superior" grade tobacco leaves can be adapted to high-speed shredders, while "poor" grade leaves need to undergo softening pretreatment first), reducing the processing breakage rate by ≥15%. Attached Figure Description
[0025] Figure 1 The flowchart of a method for characterizing the mechanical properties of tobacco leaves proposed in this invention Figure 1 ;
[0026] Figure 2 The flowchart of a method for characterizing the mechanical properties of tobacco leaves proposed in this invention Figure 2 .
[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation
[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0029] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0030] like Figures 1-2 As shown, this invention proposes a method for characterizing the mechanical properties of tobacco leaves, comprising the following steps:
[0031] (1) Sample preparation: Samples were taken from the middle part of the tobacco leaves to prepare four types of samples: tensile, tear, compression and bending. At least 5 samples were prepared in each group and equilibrated for 24 hours in an environment with a temperature of 23±2℃ and a relative humidity of 65±5%.
[0032] (2) Mechanical property test: The tensile properties, tear strength, compression rebound rate and bending stiffness are tested by a universal testing machine. The tensile properties include tensile strength, tensile elastic modulus and elongation at break. Each property is calculated by a preset formula.
[0033] (3) Data processing: Outliers are removed using the Grubbs method. The mean ± standard deviation of the valid data is taken, and the characteristics are divided into three levels: excellent, medium and poor according to the processing requirements.
[0034] The dimensions of the four types of samples in step (1) are as follows:
[0035] Tensile specimen: rectangular, 50 mm (gauge length) ) × 10mm (width b) × t (thickness);
[0036] Tear test specimen: rectangular, 100mm×63mm, with a 20mm long pre-made cut in the center;
[0037] Compression specimen: circular, 20mm in diameter, thickness ;
[0038] Bending specimen: rectangular, 80mm (length L) × 15mm (width b) × t (thickness).
[0039] The conditions for the tensile property test in step (2) are: tensile speed 10 mm / min, recording the stress-strain curve; the formula for calculating tensile strength is... ,in For maximum tension, The width of the sample. The thickness is the sample thickness.
[0040] In step (2), the tear strength test uses an Elemendorf tear clamp, and the calculation formula is as follows: ,in For maximum tearing force, The thickness is the sample thickness.
[0041] The conditions for the compression rebound rate test in step (2) are: pressurize to 50 kPa, hold for 30 s, unload and let stand for 60 s; the calculation formula is as follows: ,in For the initial thickness, The thickness after pressure is applied. This is the thickness after restoration.
[0042] The bending stiffness test in step (2) adopts a three-point bending mode with a support point spacing of 60mm and a pressure head descent speed of 5mm / min; the calculation formula is as follows: ,in L represents the force applied by the pressure head, and L represents the distance between the support points. For deflection, The width of the sample.
[0043] The significance level of the Grubbs method in step (3) is α=0.05; in the characteristic grading, tensile strength >3MPa is excellent, 1.5-3MPa is medium, and <1.5MPa is poor.
[0044] The method for measuring the thickness t of the sample is as follows: using a digital micrometer with an accuracy of 0.001 mm, three different points are measured in the non-edge area of the sample, and the average value is taken as the final thickness value. The pressure of the micrometer is set to 50 g during the measurement.
[0045] In step (1), environmental equilibration is achieved by a constant temperature and humidity chamber. Temperature and humidity are recorded every 6 hours during the equilibration process. Temperature fluctuation range ≤ ±0.5℃, relative humidity fluctuation range ≤ ±2%RH. After equilibration, the moisture content of the tobacco leaf samples needs to be verified. Moisture content fluctuation ≤ 0.5%.
[0046] Tear strength >2.5 N / mm is excellent, 2.0~2.5 N / mm is medium, and <2.0 N / mm is poor; bending stiffness >8 N·mm is excellent, 5~8 N·mm is medium, and <5 N·mm is poor; compression rebound rate >70% is excellent, 60-70% is medium, and <60% is poor.
[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
[0049] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.
Claims
1. A method for characterizing the mechanical properties of tobacco leaves, characterized in that: Includes the following steps: (1) Sample preparation: Samples were taken from the middle part of the tobacco leaves to prepare four types of samples: tensile, tear, compression and bending. At least 5 samples were prepared in each group and equilibrated for 24 hours in an environment with a temperature of 23±2℃ and a relative humidity of 65±5%. (2) Mechanical property test: The tensile properties, tear strength, compression rebound rate and bending stiffness are tested by a universal testing machine. The tensile properties include tensile strength, tensile elastic modulus and elongation at break. Each property is calculated by a preset formula. (3) Data processing: Outliers are removed using the Grubbs method. The mean ± standard deviation of the valid data is taken, and the characteristics are divided into three levels: excellent, medium and poor according to the processing requirements.
2. The method for characterizing the mechanical properties of tobacco leaves according to claim 1, characterized in that: The dimensions of the four types of samples in step (1) are as follows: Tensile specimen: rectangular, 50 mm (gauge length) ) × 10mm (width b) × t (thickness); Tear test specimen: rectangular, 100mm×63mm, with a 20mm long pre-made cut in the center; Compression specimen: circular, 20mm in diameter, thickness ; Bending specimen: rectangular, 80mm (length L) × 15mm (width b) × t (thickness).
3. The method for characterizing the mechanical properties of tobacco leaves according to claim 2, characterized in that: The conditions for the tensile property test in step (2) are: tensile speed 10 mm / min, recording the stress-strain curve; the formula for calculating tensile strength is... ,in For maximum tension, The width of the sample. The thickness is the sample thickness.
4. The method for characterizing the mechanical properties of tobacco leaves according to claim 3, characterized in that: In step (2), the tear strength test uses an Elemendorf tear clamp, and the calculation formula is as follows: ,in For maximum tearing force, The thickness is the sample thickness.
5. The method for characterizing the mechanical properties of tobacco leaves according to claim 4, characterized in that: The conditions for the compression rebound rate test in step (2) are: pressurize to 50 kPa, hold for 30 s, unload and let stand for 60 s; the calculation formula is as follows: ,in For the initial thickness, The thickness after pressure is applied. This is the thickness after restoration.
6. The method for characterizing the mechanical properties of tobacco leaves according to claim 5, characterized in that: The bending stiffness test in step (2) adopts a three-point bending mode, with a support point spacing of 60mm and a pressure head descent speed of 5mm / min; the calculation formula is as follows: ,in L represents the force applied by the pressure head, and L represents the distance between the support points. For deflection, The width of the sample.
7. The method for characterizing the mechanical properties of tobacco leaves according to claim 6, characterized in that: The significance level of the Grubbs method in step (3) is α=0.05; in the characteristic grading, tensile strength >3MPa is excellent, 1.5-3MPa is medium, and <1.5MPa is poor.
8. The method for characterizing the mechanical properties of tobacco leaves according to claim 7, characterized in that: The method for measuring the thickness t of the sample is as follows: using a digital micrometer with an accuracy of 0.001 mm, three different points are measured in the non-edge area of the sample, and the average value is taken as the final thickness value. The pressure of the micrometer is set to 50 g during the measurement.
9. The method for characterizing the mechanical properties of tobacco leaves according to claim 8, characterized in that: In step (1), environmental equilibration is achieved by a constant temperature and humidity chamber. Temperature and humidity are recorded every 6 hours during the equilibration process. Temperature fluctuation range ≤ ±0.5℃, relative humidity fluctuation range ≤ ±2%RH. After equilibration, the moisture content of the tobacco leaf samples needs to be verified. Moisture content fluctuation ≤ 0.5%.
10. The method for characterizing the mechanical properties of tobacco leaves according to claim 9, characterized in that: The property grading also includes: tear strength >2.5N / mm is excellent, 2.0~2.5N / mm is medium, and <2.0N / mm is poor; bending stiffness >8N·mm is excellent, 5~8N·mm is medium, and <5N·mm is poor; compression rebound rate >70% is excellent, 60-70% is medium, and <60% is poor.