A method for measuring the rebound rate of tobacco stems after stem compression

Abstract

The present invention belongs to the technical field of tobacco stem processing, and specifically relates to a method for determining the rebound rate of tobacco stems after stem compression. By selecting plastic metal strips of different specifications, the metal strips are mixed with tobacco stems and then screened and classified according to diameter intervals, and the tobacco stem content in different diameter intervals is weighed and calculated; the tobacco stems after washing and moisture recovery are then rolled together with the classified metal strips, and after the stems are balanced, the thickness of the tobacco stems and metal strips after rolling is measured, and then the rebound coefficient of the tobacco stems after stem compression is calculated; the rebound rate of the tobacco stems after stem compression can be calculated based on the rebound coefficient of the tobacco stems after stem compression of different diameters and the tobacco stem content in the corresponding diameter intervals. This method measures the rebound rate of tobacco stems after stem compression, and uses the rebound rate to quantitatively evaluate the quality of tobacco stems of different sizes after stem compression, so as to facilitate timely detection of abnormalities in stem compression quality, provide a reference for optimizing stem compression process parameters, and provide technical and theoretical support for tobacco stem grouping processing and homogenization production, thereby improving the tobacco stem cutting and forming effect.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco stem processing, and particularly relates to a method for measuring the springback rate of tobacco stems after stem compression. Background Art

[0002] Tobacco stems are a crucial component of tobacco leaves. With the increasing shortage and price of tobacco leaf raw materials, the utilization rate of tobacco stems has gradually increased. After being processed into cut stems, tobacco stems can be incorporated into cigarette formulations to improve cigarette quality while reducing raw material costs.

[0003] In order to fully improve the utilization rate of different grades of tobacco stem raw materials, the current tobacco stem formula in the industry does not use a single grade of raw materials, but is composed of multiple grades of tobacco stem raw materials. Due to the differences in the sizes of different grades of tobacco stem raw materials in the tobacco stem formula, and the different production environments of different grades of tobacco stems, their quality is naturally inconsistent. In the actual production process, tobacco stems with inconsistent sizes and intrinsic quality pass through the stem press under the same process parameters. The actual pressure that different tobacco stems are subjected to during the rolling process is also inconsistent, resulting in excessive or insufficient rolling of the stems. The thickness of the pressed stems cannot be guaranteed to be consistent, which in turn affects the quality of the pressed stems, which plays a vital role in the subsequent shredded forming.

[0004] At present, the quality of tobacco stems is mainly reflected by measuring the thickness of the pressed stems during the production process. Within a certain range of pressed stem thickness, the thinner the pressed stems, the better the shredded forming effect, and the higher the filling and whole shred rate of the cut stems. However, since tobacco stems are composed of wood fibers, the thickness of the tobacco stems will "rebound" after being processed by the "stem pressing" process. Therefore, only thickness testing of the tobacco stems after pressing cannot reflect the actual thickness of the pressed stems, resulting in a lack of effective basis for judging the quality of tobacco stems. For example, patent application number CN201010602313.6 discloses a method for detecting the thickness of pressed stems and a method for measuring the thickness of pressed stems of tobacco stems in CN201110089059.9. Both methods use the thickness measurement value after the metal fuse roller is pressed as the actual pressed stem thickness of the tobacco stems to judge the working status of the pressing roller of the stem pressing machine, or to judge whether the pressed stem thickness of the tobacco stems exceeds the process standard. However, since tobacco stems are composed of wood fibers and have a loose tissue structure, the tobacco stems will actually rebound to a certain extent after being rolled. At this time, the theoretically measured pressed stem thickness cannot truly reflect the actual pressed stem thickness. Therefore, using the pressed stem thickness to evaluate the quality of pressed stems is one-sided.

[0005] Therefore, it is of great significance to develop a method for measuring the springback rate of tobacco stems after compression and to use the springback rate to accurately evaluate the quality of tobacco stems of different sizes after compression. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for measuring the springback rate of compressed tobacco stems. This method measures the springback rate of compressed tobacco stems and uses it to quantitatively evaluate the quality of compressed tobacco stems of different sizes. This facilitates the timely detection of abnormalities in compressed stem quality, provides a reference for optimizing compression process parameters, and offers technical theoretical support for tobacco stem grouping and homogenization, thereby improving the quality of tobacco stem cuts.

[0007] Since the springback characteristics of tobacco stems directly reflect the quality of pressed stems, and the quality of pressed stems in turn determines their rebound resilience after rolling, the magnitude of the stem rebound can directly reflect the effectiveness of the stem compression. The inventors of this application realized that if the stem rebound rate after compression could be accurately measured, the stem rebound rate could be used to detect quality anomalies during the compression process, allowing timely adjustments to relevant process parameters during the compression process. This could also provide guidance for the preceding process steps. This led to the invention.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for measuring the springback rate of tobacco stems after stem compression comprises the following steps:

[0010] (1) Obtaining plastic metal strips of different diameters and lengths;

[0011] (2) removing broken stems from the tobacco stems and uniformly mixing the tobacco stems after the broken stems have been removed with the metal strips described in step (1);

[0012] (3) partitioning the mixed tobacco stems and metal strips according to their diameters to obtain multiple diameter intervals;

[0013] (4) Weigh and calculate the tobacco stem content in each diameter range;

[0014] (5) Select tobacco stems of different lengths in different diameter ranges and wash and rehydrate them;

[0015] (6) rolling the metal strips of different lengths in each diameter range with the tobacco stems washed and moisturized in step (5);

[0016] (7) Measure the thickness of the metal strips and tobacco stems after rolling in each diameter range, and calculate the rebound coefficient Y of the tobacco stems after rolling according to the following formula: r ;

[0017]

[0018] Where Y r is the stem rebound coefficient after stem compression, t r is the thickness of tobacco stem after pressing, t is the thickness of metal strip after rolling, and r is the diameter range;

[0019] (8) Based on the tobacco stem content in each diameter range and the tobacco stem rebound coefficient after stem compression, the tobacco stem rebound rate Y after stem compression is calculated by the following formula:

[0020]

[0021] Where, Y is the stem rebound rate after stem compression, P i is the tobacco stem content in each diameter range.

[0022] The present application selects plastic metal strips of different specifications, mixes the metal strips with tobacco stems, and then screens and classifies them according to diameter intervals, weighs and calculates the tobacco stem content in different diameter intervals; then rolls the washed and moistened tobacco stems together with the classified metal strips, and after the stems are balanced, measures the thickness of the tobacco stems and metal strips after rolling, and then uses the thickness of the plastic metal strips after rolling as the theoretical value of the stems, and the thickness of the stems after equilibrium as the actual value of the stems after rebound. The ratio of the difference between the actual value of the stems and the theoretical value of the stems to the theoretical value of the stems is the rebound coefficient of the tobacco stems after stem compression; the rebound rate of the tobacco stems after stem compression can be calculated based on the rebound coefficient of the tobacco stems after stem compression of different diameters and the tobacco stem content in the corresponding diameter intervals. The rebound rate takes into account the theoretical thickness of the stems and the actual rebound of the tobacco stems after stem compression. Therefore, the stem compression quality of tobacco stems of different sizes can be more accurately evaluated by the stem compression rebound rate, which facilitates the timely detection of abnormal stem compression quality.

[0023] The plastic metal strip of the present invention can be any soft metal to ensure that it can be rolled into a sheet. As a preferred embodiment of the present invention, the plastic metal strip in step (1) is at least one of copper, aluminum, and tin.

[0024] In order to use the thickness of the metal strip after rolling as the theoretical value of the pressed stem, it is necessary to ensure that the shape and size of the metal strip are similar to the tobacco stem. As a preferred embodiment of the present invention, the cross-section of the plastic metal strip in step (1) is circular or elliptical, with a diameter of 2.5 to 8.0 mm and a length of 10.0 to 65.0 mm.

[0025] Preferably, the crushed stems in step (2) are tobacco stems having a length of less than 10.0 mm and a diameter of less than 2.5 mm. Screening out the crushed stems ensures that the size of the rolled tobacco stems falls within the parameters of the stem pressing machine, thereby preventing different tobacco stems from being subjected to different pressures during the pressing process, thereby preventing excessive or insufficient pressing of the stems and affecting the overall quality of the pressed tobacco stems.

[0026] Partitioning metal strips and tobacco stems of different diameters can improve the accuracy of the measurement results, and the more partitions there are, the higher the accuracy. As a preferred embodiment of the present invention, the diameter intervals in step (3) are divided into five, namely 2.5-3.5mm, 3.5-4.5mm, 4.5-5.5mm, 5.5-6.5mm, and >6.5mm.

[0027] As a preferred embodiment of the present invention, the number m of tobacco stems of different lengths selected in step (5) is ≥30. By selecting multiple tobacco stems of different diameter ranges and lengths for rolling, it is more statistically significant and can avoid problems such as deviation and inaccuracy in calculation results caused by excessive or insufficient compression of individual tobacco stems during the rolling process.

[0028] As a preferred embodiment of the present invention, in the stem washing and rehumidification in step (5), the process parameters of the stem washing are: stem washing circulating water temperature (45-60) ± 3°C, stem washing time 5-10s, and circulating water flow rate 0.4-0.8m / s; the rehumidification temperature is 30±2°C, the humidity is 70±5%, and the time is 1-3h, so as to ensure that the moisture content of the tobacco stems is 30±2%, thereby not affecting the subsequent rolling effect.

[0029] As a preferred embodiment of the present invention, in step (6), the thickness parameter of the pressed stems for rolling the metal strips and tobacco stems of each diameter range is (0.9 to 1.5) ± 0.1 mm.

[0030] In order to further ensure the accuracy of the calculation results, as a preferred embodiment of the present invention, step (6) also includes balancing the rolled metal strips and tobacco stems, and the balancing time is at least 5 minutes, so that the rolled tobacco stems can fully rebound.

[0031] The method for measuring the thickness of the rolled metal strip and the tobacco stem in step (7) is not limited. As a preferred embodiment of the present invention, n equal-divided points of the length of the measurement object are used as measurement points, where n≥3, and the average value of the measurement results is taken.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention provides a method for determining the springback rate of tobacco stems after stem compression, which has a simple measurement process, convenient calculation, and accurate and reliable results, thus filling the gap in the detection of the springback rate of tobacco stems during the stem compression process.

[0034] (2) The stem rebound coefficient after compression defined by the determination method of the present invention can accurately reflect the rebound of tobacco stems of different sizes after rolling. The stem rebound rate comprehensively considers the theoretical thickness of the compressed stems and the actual rebound of the tobacco stems after compression, and can further reflect the comprehensive quality of the compressed stems. Therefore, the corresponding standard reference values ​​under different compression parameter conditions can be established to judge the deviation of the compressed stem quality and further quantitatively evaluate the compressed stem quality.

[0035] (3) The present invention provides guidance for optimizing stem pressing process parameters and adjusting equipment parameters by measuring the stem rebound rate after stem pressing. It can also reflect the relationship between the stem rebound rate and the stem size and stem pressing process parameters, providing technical theoretical support for tobacco stem grouping processing and homogenized production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is a schematic flow chart of a method for determining the springback rate of tobacco stems after stem compression.

[0037] Figure 2 Schematic diagram of the measurement of equally divided nodes for the thickness of the compression stem in Example 1.

[0038] Figure 3 This is a comparison chart of the springback coefficient and rebound rate of the pressed stem under different pressed stem thickness parameters in Examples 1 to 4. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] A method for measuring the springback rate of tobacco stems after stem compression comprises the following steps:

[0042] (1) Select tin metal bars with circular cross-sections and diameters of 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, and 7.0 mm, and cut them into lengths of 10.0 mm, 15.0 mm, 20.0 mm, and 25.0 mm. Four bars of each diameter and length are cut, for a total of 80 bars.

[0043] (2) taking 60 kg of tobacco stems, using a vibrating sorting and screening instrument to remove broken stems less than 10.0 mm in length and less than 2.5 mm in diameter, and then mixing the tobacco stems after the broken stems are removed with the metal bars of different specifications prepared in step (1);

[0044] (3) The mixed tobacco stems and metal strips are placed together on a vibrating sorting screen. The tobacco stems and metal strips with similar diameters are screened into five different diameter ranges by adjusting the screening aperture, namely 2.5-3.5 mm, 3.5-4.5 mm, 4.5-5.5 mm, 5.5-6.5 mm, and >6.5 mm.

[0045] (4) using a balance to weigh the total weight of the tobacco stems and metal strips in each diameter interval and the weight of the tobacco stems in each diameter interval, and calculating the weight percentage of the tobacco stems in each diameter interval (the ratio of the weight of the tobacco stems in each diameter interval to the total weight of the tobacco stems and metal strips) to obtain the tobacco stem content in each diameter interval;

[0046] (5) 60 tobacco stems of different lengths in each diameter range were manually selected and placed in a controllable water washing tank for stem washing and moisture conditioning. The stem washing circulating water temperature was (45-60) ± 3°C, the stem washing time was 5-10s, and the circulating water flow rate was 0.4-0.8m / s. Then, the stems were balanced for 2 hours in an environment with a temperature of 30±2°C and a humidity of 70±5% for moisture conditioning, so that the moisture content and temperature of the tobacco stems met the process requirements (moisture content of 30±2%).

[0047] (6) The tobacco stems and metal strips in each diameter range are placed into the stem press for rolling (the tobacco stems and metal strips in the same diameter range are rolled at the same time), and then the rolled tobacco stems and metal strips are taken out and left to balance for 5 minutes. The thickness parameter of the stem press is set to 0.9±0.1mm.

[0048] (7) Use a digital vernier caliper to measure the thickness of the tobacco stems and metal strips after pressing in each diameter range, such as Figure 2 As shown, the four equal points of the length of the measured object are used as measurement nodes, and the measurement results are averaged with an accuracy of ±0.01mm. The rebound coefficient of the tobacco stem after compression is calculated using the following formula:

[0049]

[0050] Where Y r is the stem rebound coefficient after stem compression, t r is the thickness of tobacco stem after pressing, t is the thickness of metal strip after rolling, and r is the diameter range;

[0051] (8) Based on the tobacco stem content in each diameter range and the tobacco stem rebound coefficient after stem compression, the tobacco stem rebound rate Y after stem compression is calculated by the following formula:

[0052]

[0053] Where, Y is the stem rebound rate after stem compression, P i is the tobacco stem content in each diameter range.

[0054] The measurement and calculation results of this embodiment are shown in Table 1:

[0055] Table 1 Rebound coefficient and rebound rate of tobacco stem after compression in Example 1

[0056]

[0057] As can be seen from Table 1, under the same stem thickness parameters, there are obvious differences in the rebound coefficients of tobacco stems of different diameters after compression, that is, with the increase of stem diameter, the rebound coefficient of tobacco stems after compression gradually increases, indicating that the rebound coefficient of tobacco stems after compression can accurately reflect the rebound of tobacco stems of different sizes after rolling, and that the rebound rate of tobacco stems after compression can be established at a standard reference value corresponding to a stem thickness parameter of 0.9±0.1mm, thereby judging whether there is a deviation in the quality of the compressed stems during the production process, that is, the standard reference value is 0.42. If the rebound rate of tobacco stems after compression is greater than or less than 0.42 during the actual production process (under this stem thickness parameter), it indicates that there is a deviation in the quality of the compressed stems, and the stem compression process needs to be optimized. In addition, the quality of the compressed stems can be quantitatively evaluated based on the deviation value of the rebound rate of tobacco stems after compression.

[0058] Example 2

[0059] A method for measuring the springback rate of tobacco stems after stem compression comprises the following steps:

[0060] (1) Select copper metal bars with elliptical cross-sections and diameters of 2.5 mm, 4.0 mm, 5.0 mm, 6 mm, and 7.0 mm, and cut them into lengths of 10.0 mm, 20.0 mm, 30.0 mm, and 40 mm. Four bars of each diameter and length are cut, for a total of 80 bars.

[0061] (2) taking 60 kg of tobacco stems, using a vibrating sorting and screening instrument to remove broken stems less than 10.0 mm in length and less than 2.5 mm in diameter, and then mixing the tobacco stems after the broken stems are removed with the metal bars of different specifications prepared in step (1);

[0062] (3) The mixed tobacco stems and metal strips are placed together on a vibrating sorting screen. The tobacco stems and metal strips with similar diameters are screened into five different diameter ranges by adjusting the screening aperture, namely 2.5-3.5 mm, 3.5-4.5 mm, 4.5-5.5 mm, 5.5-6.5 mm, and >6.5 mm.

[0063] (4) using a balance to weigh the total weight of the tobacco stems and metal strips in each diameter interval and the weight of the tobacco stems in each diameter interval, and calculating the weight percentage of the tobacco stems in each diameter interval to obtain the tobacco stem content in each diameter interval;

[0064] (5) 30 tobacco stems of different lengths in each diameter range were manually selected and placed in a controllable water washing tank for stem washing and moisture conditioning. The stem washing circulating water temperature was (45-60) ± 3°C, the stem washing time was 5-10s, and the circulating water flow rate was 0.4-0.8m / s. Then, the stems were balanced for 3 hours in an environment with a temperature of 30±2°C and a humidity of 70±5% for moisture conditioning, so that the moisture content and temperature of the tobacco stems met the process requirements (moisture content of 30±2%).

[0065] (6) The tobacco stems and metal strips in each diameter range are placed into the stem press for rolling (the tobacco stems and metal strips in the same diameter range are rolled at the same time), and then the rolled tobacco stems and metal strips are taken out and left to balance for 5 minutes. The thickness parameter of the stem press is set to 1.0±0.1mm.

[0066] (7) Use a digital vernier caliper to measure the thickness of the tobacco stems and metal strips after compression at each diameter interval. Use the points that divide the length of the measured object into three equal parts as the measurement nodes. Take the average value of the measurement results with an accuracy of ±0.01mm. Calculate the rebound coefficient of the tobacco stems after compression using the following formula:

[0067]

[0068] Where Y r is the stem rebound coefficient after stem compression, t r is the thickness of tobacco stem after pressing, t is the thickness of metal strip after rolling, and r is the diameter range;

[0069] (8) Based on the tobacco stem content in each diameter range and the tobacco stem rebound coefficient after stem compression, the tobacco stem rebound rate Y after stem compression is calculated by the following formula:

[0070]

[0071] Where, Y is the stem rebound rate after stem compression, P i is the tobacco stem content in each diameter range.

[0072] The measurement and calculation results of this embodiment are shown in Table 2:

[0073] Table 2 Rebound coefficient and rebound rate of tobacco stem after stem compression in Example 2

[0074]

[0075]

[0076] Example 3

[0077] A method for measuring the springback rate of tobacco stems after stem compression comprises the following steps:

[0078] (1) Select aluminum metal bars with circular cross-sections and diameters of 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, and 8 mm, and cut them into lengths of 30.0 mm, 40.0 mm, 50.0 mm, and 65.0 mm. Four bars of each diameter and length were cut, for a total of 80 bars.

[0079] (2) taking 60 kg of tobacco stems, using a vibrating sorting and screening instrument to remove broken stems less than 10.0 mm in length and less than 2.5 mm in diameter, and then mixing the tobacco stems after the broken stems are removed with the metal bars of different specifications prepared in step (1);

[0080] (3) The mixed tobacco stems and metal strips are placed together on a vibrating sorting screen. The tobacco stems and metal strips with similar diameters are screened into five different diameter ranges by adjusting the screening aperture, namely 2.5-3.5 mm, 3.5-4.5 mm, 4.5-5.5 mm, 5.5-6.5 mm, and >6.5 mm.

[0081] (4) using a balance to weigh the total weight of the tobacco stems and metal strips in each diameter interval and the weight of the tobacco stems in each diameter interval, and calculating the weight percentage of the tobacco stems in each diameter interval to obtain the tobacco stem content in each diameter interval;

[0082] (5) 50 tobacco stems of different lengths in each diameter range were manually selected and placed in a controllable water washing tank for stem washing and moisture conditioning. The stem washing circulating water temperature was (45-60) ± 3°C, the stem washing time was 5-10s, and the circulating water flow rate was 0.4-0.8m / s. Then, the stems were balanced for 1 hour in an environment with a temperature of 30±2°C and a humidity of 70±5% for moisture conditioning, so that the moisture content and temperature of the tobacco stems met the process requirements (moisture content of 30±2%).

[0083] (6) The tobacco stems and metal strips in each diameter range are placed into the stem press for rolling (the tobacco stems and metal strips in the same diameter range are rolled at the same time), and then the rolled tobacco stems and metal strips are taken out and left to balance for 5 minutes. The thickness parameter of the stem press is set to 1.2±0.1mm.

[0084] (7) Use a digital vernier caliper to measure the thickness of the tobacco stems and metal strips after compression at each diameter interval. Use the five equal points of the length of the measured object as the measurement nodes. Take the average value of the measurement results with an accuracy of ±0.01mm. Calculate the rebound coefficient of the tobacco stems after compression using the following formula:

[0085]

[0086] Where Y r is the stem rebound coefficient after stem compression, t r is the thickness of tobacco stem after pressing, t is the thickness of metal strip after rolling, and r is the diameter range;

[0087] (8) Based on the tobacco stem content in each diameter range and the tobacco stem rebound coefficient after stem compression, the tobacco stem rebound rate Y after stem compression is calculated by the following formula:

[0088]

[0089] Where, Y is the stem rebound rate after stem compression, P i is the tobacco stem content in each diameter range.

[0090] The measurement and calculation results of this embodiment are shown in Table 3:

[0091] Table 3 Rebound coefficient and rebound rate of tobacco stem after stem compression in Example 3

[0092]

[0093] Example 4

[0094] The method for determining the springback rate of tobacco stems after compression in this embodiment is substantially the same as that in Example 1, except that the thickness parameter of the compressed stems in the compression machine in step (6) is set to 1.5 ± 0.1 mm. The measurement and calculation results of this embodiment are shown in Table 4:

[0095] Table 4 Rebound coefficient and rebound rate of tobacco stem after stem compression in Example 4

[0096]

[0097] Result Analysis

[0098] Figure 3 It is a comparison diagram of the measurement results of Examples 1-4, from Figure 3 As can be seen from Figure (a), different stem thickness parameters have an impact on the stem rebound rate after stem compression. That is, within the same diameter range, as the stem thickness parameter setting increases, the stem rebound coefficient after stem compression gradually increases. Moreover, under the same stem thickness parameter, as the stem diameter increases, the stem rebound coefficient after stem compression also gradually increases. This can accurately reflect the rebound of tobacco stems of different sizes after rolling. Figure 3 As shown in Figure (b), the measurement results under four different stem thickness parameters show that the stem rebound rate after compression is positively correlated with the set stem thickness value. That is, as the stem thickness parameter increases, the stem rebound rate after compression increases. Therefore, the stem rebound rate after compression can directly reflect the quality of the compressed stems under different stem compression process parameters. Based on the stem rebound coefficient and rebound rate after compression, standard reference values ​​corresponding to different stem thickness parameters can be established to determine deviations in the compressed stem quality during the production process. The measurement results of the stem rebound rate can provide a reference for optimizing the compression process parameters and also provide technical theoretical support for the grouping and homogenization of compressed stems of different sizes.

[0099] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0101] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for measuring the springback rate of tobacco stems after stem compression, characterized in that: The following steps are involved: (1) Obtaining plastic metal strips of different diameters and lengths; (2) screening out broken stems from the tobacco stems, and uniformly mixing the tobacco stems after screening out the broken stems with the metal strips described in step (1); (3) Dividing the mixed tobacco stems and metal strips into different diameter intervals according to their diameters; (4) Weigh and calculate the tobacco stem content in each diameter range; (5) Select tobacco stems of different lengths in different diameter ranges and wash and rehydrate them; (6) rolling the metal strips of different lengths in each diameter range with the tobacco stems washed and moisturized in step (5) in sequence, and rolling the tobacco stems and metal strips in the same diameter range at the same time; (7) Measure the thickness of the metal strips and tobacco stems after rolling in each diameter range, and calculate the rebound coefficient Y of the tobacco stems after rolling according to the following formula: r ; ， Where Y r is the stem rebound coefficient after stem compression, t r is the thickness of tobacco stem after pressing, t is the thickness of metal strip after rolling, and r is the diameter range; The method for measuring the thickness of the rolled metal strips and tobacco stems in each diameter interval is as follows: k equal divisions of the length of the measurement object are used as measurement points, k ≥ 3, and the average value of the measurement results is taken; (8) Based on the tobacco stem content in each diameter range and the tobacco stem rebound coefficient after stem compression, the tobacco stem rebound rate Y after stem compression is calculated by the following formula: ， Where, Y is the stem rebound rate after stem compression, P i is the tobacco stem content in each diameter range.

2. The method for measuring the springback rate of tobacco stems after compression according to claim 1, characterized in that: The plastic metal strip in step (1) is at least one of copper, aluminum, and tin.

3. The method for measuring the springback rate of tobacco stems after compression according to claim 1, characterized in that: The cross-section of the plastic metal strip in step (1) is circular or elliptical, with a diameter of 2.5 to 8.0 mm and a length of 10.0 to 65.0 mm.

4. The method for measuring the springback rate of tobacco stems after compression according to claim 1, characterized in that: The diameter intervals described in step (3) are divided into five ranges, namely 2.5-3.5 mm, 3.5-4.5 mm, 4.5-5.5 mm, 5.5-6.5 mm, and >6.5 mm.

5. The method for measuring the springback rate of tobacco stems after compression according to claim 1, characterized in that: The number m of tobacco stems of different lengths selected in step (5) is ≥ 30.

6. The method for measuring the springback rate of tobacco stems after stem compression according to claim 1, characterized in that: In the step (5) of stem washing and rehumidification, the process parameters of stem washing are: stem washing circulating water temperature (45~60)±3℃, stem washing time 5~10s, circulating water flow rate 0.4~0.8m / s; the rehumidification temperature of the rehumidification is 30±2℃, humidity is 70±5%, and time is 1~3h.

7. The method for measuring the springback rate of tobacco stems after compression according to claim 1, characterized in that: In step (6), the thickness parameter of the rolled tobacco stems for rolling the metal strips and tobacco stems of different lengths in each diameter range is (0.9-1.5)±0.1 mm.

8. The method for measuring the springback rate of tobacco stems after stem compression according to claim 1, wherein: Step (6) further comprises balancing the rolled metal strips and tobacco stems, wherein the balancing time is at least 5 minutes.

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