Method for measuring diameter of continuous rod of tobacco industry product

Abstract

A method of measuring the diameter of a continuous rod (CR) of a tobacco industry product (R), comprising the steps of determining a measurement section (S1, S2, S3, S4) on the continuous rod (CR) in relation to the structure of the product (R), determining a measurement time window (T1, T2, T3, T4) in relation to the structure of the product (R) and the transfer speed (v) of the continuous rod (CR), the diameter is measured in the determined measurement section (S1, S2, S3, S4) in a determined measurement time window (T1, T2, T3, T4), wherein the determined measurement time window (T1, T2, T3, T4) is synchronized with the determined measurement section (S1, S2, S3, S4).

Description

[0001] The present invention relates to a method and a system for determining the diameter of rod-shaped articles for the tobacco industry.

[0002] In the prior art, there is a known method of measuring the diameter of a rod-shaped object using an optical system.

[0003] Patent application US2006109485A1 discloses a system for measuring the diameter of a rod-shaped object in the tobacco industry using a light beam. The disclosed method is based on the concept that all light sources illuminate the rod-shaped object at one point at the same time, so that light is scattered from the surface of the object at the illumination point, and the scattered light is detected by a sensor. Here, a sensor is respectively assigned to a light source, so that the profile of a partial surface of the entire circumferential surface of the object illuminated by the light source is determined by one sensor. In order to be able to simultaneously determine the diameter of a predetermined point of the object and without a shadow area, several light sources are required to illuminate the object at this point. Therefore, it is ensured that the diameter of the object is determined quickly and reliably. In addition, several light sources are required to completely cover the object, that is, without shadows or the like.

[0004] In the tobacco industry, products like filter rods and tobacco rods are produced by cutting a continuous rod moving at high speed with the help of a rotating cutting head of a cutting unit. The continuous rod comprises a filling material wrapped with a wrapping material. The filter rod can be filled with one type of filter material or several types of filter materials (combination filter), in which particulate material can also be filled. The filter rod can include aroma capsules or some other inserts. The tobacco rod can include shredded tobacco or reconstituted tobacco leaves as well as some special inserts, such as metal inserts. Therefore, there are repeated sections along the continuous rod of the tobacco industry, and the diameters of these sections can be different due to the different stiffness or hardness of the sections or segments.

[0005] The problem existing in the tobacco industry is to determine the diameter profile of rod-shaped articles, such as ring-shaped rods of tobacco industry products. The diameter profile is a profile showing the distribution of the diameter along the length of the tobacco industry rod-shaped articles. Furthermore, the problem facing manufacturers existing in the prior art can be defined as the continuous or repeated measurement of objects present in the measuring field of the sensor during the production process.

[0006] The invention is defined in claim 1 .

[0007] Preferably, the method for measuring the diameter of a continuous rod of a tobacco industry product according to the present invention comprises the following steps: determining a measurement segment on the continuous rod related to the structure of the product, determining a measurement time window related to the structure of the product and the conveying speed of the continuous rod, measuring the diameter within a determined measurement segment within the determined measurement time window, wherein the determined measurement time window is synchronized with the determined measurement segment.

[0008] Preferably, in the method according to the invention, synchronization between the determined measuring section and the determined measuring time window is achieved by using a signal which represents the cutting moment.

[0009] Preferably, in the method according to the invention, the synchronization between the determined measuring section and the determined measuring time window is obtained by using a signal representing the position of the leading end of the continuous rod of the tobacco industry.

[0010] Preferably, in the method according to the invention, the measurements within the measuring time window are carried out with a first frequency.

[0011] Preferably, in the method according to the invention, the determined measuring section covers the entire length of the product.

[0012] Preferably, the measuring method according to the invention comprises more than one measuring section and more than one measuring window.

[0013] Preferably, the measuring method according to the invention comprises more than one measuring section and the determined measuring time windows overlap one another.

[0014] Preferably, in the method according to the invention, the measurement frequency or the measurement accuracy is different in different measurement time windows.

[0015] Advantageously, the method allows measuring selective sections of continuous rods of the tobacco industry, so the measurement results can be assigned to one or more specific sections of the manufactured product depending on its structure and can be selective, which allows better quality control and provides a more flexible production system.

[0016] The newly proposed method for measuring the diameter of continuous rods of tobacco industry products is able to maintain the designed level of measurement accuracy at high measurement frequencies in dusty environments of factory facilities.

[0017] The present invention is described in detail below with reference to the accompanying drawings in preferred embodiments:

[0018] Figure 1 shows a measuring system used in the method according to the invention;

[0019] Figure 2 The structure of the continuous rod and the section for achieving measurement in the first embodiment are shown;

[0020] Figure 3 shows the case for transport at speed v1 Figure 2 A series of measurement time windows for consecutive rods;

[0021] Figure 4 shows the case for transport at speed v2 Figure 2 A series of measurement time windows for consecutive rods;

[0022] Figure 5 The structure of the continuous rod and the section for achieving measurement in the second embodiment are shown;

[0023] Figure 6 Shows Figure 5 A series of measurement time windows for consecutive rods;

[0024] Figure 7 The structure of the continuous rod and the section for achieving measurement in the third embodiment are shown;

[0025] Figure 8 Shows Figure 7 A series of measurement time windows for consecutive rods;

[0026] Fig. 9 A measuring unit used in a system used in a method according to the invention is shown.

[0027] Figure 1 A fragment of a machine for manufacturing a product for the tobacco industry, namely a combined filter rod R, is shown. A continuous rod CR is formed in a rod forming unit RF and cut into individual products R. Figure 1 A measuring system used in the method according to the invention is shown. Fig. 9 The further explained measuring system comprises a measuring unit 100, a cutting unit 200 and a computing unit 300. The measuring unit 100 comprises a sensor unit 13 with two sensors 10, 11 and a light source 14. The measuring unit 100 performs measurements at a measuring point M at a distance L from a cutting point C, where the cutting unit 200 cuts the rod-shaped object in the form of a continuous rod CR of a tobacco industry product R. The continuous rod CR of the tobacco industry product travels at a speed v in a direction from the measuring point M towards the cutting point C.

[0028] This embodiment of the method for measuring the diameter of a rod-shaped article of the tobacco industry comprises the following steps: a continuous rod CR comprising a product R of the tobacco industry is conveyed at a conveying speed v, and the diameter of the continuous rod CR is measured. When the measuring section S is conveyed in the measuring field of the measuring unit 100, the measurement is performed within a determined measuring time window T, i.e. the determined section S is synchronized with the determined measuring time window T. The synchronization of the determined measuring section S with the determined measuring time window T can be obtained by using a cutting head control signal, a definition of the structure of the product R, a distance between the cutting head of the cutting unit 200 and the measuring unit 100, the conveying speed v, or by measuring the position of the front end of the continuous rod CR, or by any combination of these signals or values.

[0029] Figure 2A continuous rod CR is shown, wherein the internal structure of the product R consists of different segments D, F, G. A certain measuring segment S can be selected to achieve a measurement within each product R, in the embodiment presented, the segment S covers the length of the segment G. Since the continuous rod CR comprises a number of products R to be separated by the cutting head, Figure 2 Four defined measuring sections S1, S2, S3, S4 are shown. Each defined measuring section starts at a point X and ends at a point Y, which can be selected as required and in relation to the structure of the product R. Thus, the first defined measuring section S1 starts at a point X1 and ends at a point Y1, and so on.

[0030] Figure 3 A diagram is shown with measurement results D representing the diameter of the continuous rod CR within certain measurement time windows T1, T2, T3, T4. Each measurement time window starts at a point in time T(X) at which point X of the continuous rod CR is located at a measurement point M in the measurement field of the measuring unit 100 and therefore ends at a point on the time axis representing the moment at which point Y is located at the measurement point M in the measurement field of the measuring unit 100.

[0031] The diameter is measured at a first frequency in a determined measuring section S. The first frequency may be referred to as the sampling frequency, which defines the temporal resolution of the measurement, since it represents the number of individual measurements performed per unit time. An increase in the temporal resolution may be achieved by increasing the sampling frequency in relation to the speed V of the conveyed rod-shaped object or by reducing the speed V and maintaining the sampling frequency constant.

[0032] Figure 4 It is shown how a change in the speed at which the continuous rod CR is conveyed affects the length of the determined measurement time window T, when v2 is higher than v1, the determined measurement time window T becomes shorter and the number of samples per time window is smaller.

[0033] Figure 5 A fragment of another continuous rod-shaped article CR, i.e. a continuous filter rod, provided with uniformly laid inserts K (e.g. aroma capsules or granules) arranged along the length of the rod is shown, wherein a measuring unit 100 and a cutting unit 200 are presented. A second embodiment of the method for measuring the diameter of a rod-shaped article of the tobacco industry comprises the following steps: a continuous rod CR containing a product R of the tobacco industry is conveyed at a conveying speed v, and the diameter of the continuous rod CR is measured at a selected position of the continuous rod CR or in a determined section S. Similarly, when the measuring section S is conveyed in the measuring field of the measuring unit 100, the measurement is performed within a determined measuring time window T, i.e. the determined section S and the determined measuring time window T are synchronized. Figure 5Six defined measuring sections S1, S2, S3, S4, S5, S6 are shown. The sections S1, S3, S5 relate to the diameter of the continuous rod CR where the insert K is located. The sections S2, S4, S6 relate to the diameter of the continuous rod CR between the inserts K. Each defined measuring section starts at a point X and ends at a point Y, which can be selected as required and in relation to the structure of the product R. Thus, the first defined measuring section S1 starts at a point X1 and ends at a point Y1, and so on. The diameter is measured in the first measuring section S1 and in the second measuring section S2. Figure 6 The time windows T1, T2, T3, T4, T5, T6 associated with the segments S1, S2, S3, S4, S5, S6 are presented. The segments S1 and S2 overlap, Figure 6 The time windows T1 and T2 presented in FIG. 1 also overlap. The next segments, namely the third segment S3 and the fourth segment S4 are adjacent, Figure 6 The time windows T3 and T4 in are also adjacent. The fifth segment S5 and the sixth segment S6 are separated. Figure 6 The time windows T5 and T6 in are also separated. Any combination of the variants of the relationship between adjacent segments S and time windows T presented above or only one of them can be implemented in the production process.

[0034] Figure 7 A fragment of another continuous rod-shaped article CR, i.e. a continuous tobacco rod, is shown, wherein a measuring unit 100 and a cutting unit 200 are presented. A third embodiment of the method for measuring the diameter of a rod-shaped article of the tobacco industry comprises the following steps: a continuous rod CR comprising a product R of the tobacco industry is conveyed at a conveying speed v, and the diameter of the continuous rod CR is measured at a selected position, in this embodiment at a section S located at the end of the product R. The section S may cover the entire length of the product R. Similar to the previous embodiments, the determined section S and the determined measurement time window T are synchronized. Figure 7 Three defined measuring sections S1 , S2 , S3 are shown. Each defined measuring section starts at a point X and ends at a point Y, which can be selected as required and in relation to the structure of the product R, similar to the previous embodiments. Figure 8 The time windows T1 , T2 , T3 associated with the segments S1 , S2 , S3 are presented.

[0035] In one embodiment, the defined measurement section S covers the entire length of the product, the measurement system knowing which part of the product to measure at any given time.

[0036] Preferably, the method of measuring diameter of the present invention comprises more than one measuring section and / or more than one measuring window. This can be achieved by a single measuring unit or by additional measuring units not shown in the drawings.

[0037] Preferably, in a method according to a further embodiment more than one measuring section is present and the measuring sections overlap one another.

[0038] Preferably, in the method for measuring diameter of the present invention, there is more than one measuring time window, and the measuring time windows overlap with each other.

[0039] Preferably, in the method for measuring diameter of the present invention, the frequency is different in different measurement time windows.

[0040] A preferred embodiment of the method according to the invention also comprises a second sensor unit and an additional step of measuring the diameter using a second frequency. This can be done in the same determined measurement section or in different measurement sections. In yet another preferred embodiment, the second measurement is achieved with a second accuracy.

[0041] In a further preferred embodiment, the first measurement is a diameter measurement of a first type and the second measurement type is a diameter measurement of a second type. The first type of measurement can be, for example, an analog measurement in which the voltage at the output of the first sensor is proportional to the diameter of the rod-shaped object CR. The characteristics of the sensor do not have to be linear and can be described by any convenient function. The second type of measurement can be digital or also analog, with different sensor properties or different sensor characteristics.

[0042] In another embodiment, the first measurement type uses a laser analog sensor, preferably a photodiode, and the second measurement type uses an optical digital sensor, preferably a CCD sensor.

[0043] The first sensor is preferably operated at a first frequency in the range of 20 kHz to 200 kHz, preferably 100 kHz, and the conveying speed V is in the range of 50 to 600 m / min. The second sensor is preferably operated at a second frequency in the range of 0.5 kHz to 3 kHz, preferably 1 kHz, and the conveying speed V is in the range of 50 to 600 m / min. The second frequency is less than the first frequency, the first accuracy is less than the second accuracy, and the result of the second measurement of the diameter is used to correct the first result of measuring the diameter. The second frequency can be called a correction frequency because it can be used to update the characteristics of the first sensor in response to the presence of a systematic error detected by the second sensor.

[0044] In a preferred embodiment, the sensor unit comprises a group of three individual first type sensors arranged at 120° to each other. In a further preferred embodiment, the sensor unit comprises a group of six individual first type sensors arranged at 60° to each other and / or the sensor unit comprises one, two or three second type sensors.

[0045] The correction frequency is in the range of 10 Hz to 0.001 Hz, preferably 0.1 Hz.

[0046] The first sensor and the second sensor both receive the same light beam from a light source S, which is split by a beam splitter into two beams before reaching the sensor of that type, one of which reaches the first type sensor and the other reaches the second type sensor.

[0047] Fig. 9 Schematic representation of the measuring principle of the measuring unit. The light source 14 emits a collimated light beam 15 with a selected wavelength. The light source can be a laser light source emitting visible light or infrared light. The light beam is guided by the optical unit 16 toward the rod-shaped object CR in the measuring direction. The width of the light beam 15 is selected to be larger than the diameter of the object to be measured, so that the light beam 15 reaches the first sensor 10 above and below the object to be measured (i.e., the rod-shaped object CR). Before reaching the first sensor 10, the light beam is split by the semi-transparent mirror 12, so that the light beam also reaches the second sensor 11.

[0048] In a preferred embodiment, the method for measuring the diameter of a continuous rod of a tobacco industry product as a rod-shaped article CR comprises the step of transmitting the continuous rod through a sensor unit comprising a first sensor 10 and a second sensor 11. The first sensor and the second sensor are analog sensors, while digital sensors can be used in other embodiments. The first operating frequency of the first sensor 10 is higher than the second operating frequency of the second sensor 11. The next step is to calculate the diameter of the transmitted continuous rod CR with the aid of a calculation unit that receives signals from the first sensor and the second sensor. In a preferred embodiment, the diameter of the continuous rod CR is calculated based on the signal of the first sensor 10 using the characteristic that the diameter is related to the value of the signal generated by the first sensor 10.

[0049] The characteristic of a sensor is a function that describes how the measured physical property is converted into an analog electrical signal (i.e. the voltage at the output of the sensor) and how this electrical signal is converted into a measured value (i.e. the diameter of the product R). There are at least two ways to change the characteristics of a sensor, either on the analog side by modifying the analog voltage or on the digital side where the diameter is already measured in a digitally corrected form.

[0050] The next step of the method is to calculate the diameter of the continuous rod based on the signal generated by the second sensor, wherein the diameter is correlated with the signal generated by the second sensor, and to compare the diameter measured by the first sensor and the diameter measured by the second sensor. In a preferred embodiment, the next step includes changing the characteristics of the first sensor 10 so that the value of the signal generated by the first sensor 10 is correlated with the diameter measured by the second sensor 11 if the diameter measured by the first sensor is different from the diameter of the same point on the continuous rod measured by the second sensor 11.

[0051] The first frequency is in the range of 20 kHz to 200 kHz, preferably 100 kHz, and the second frequency is in the range of 0.5 kHz to 3 kHz, preferably 1 kHz.

[0052] In another preferred embodiment, the continuous rod of the tobacco industry product CR is a continuous rod of a multi-segment rod-shaped tobacco industry product, the first frequency is selected to be related to the speed v to obtain at least one first precision sample for each segment, and the second frequency is selected to obtain at least one second precision sample for each multi-segment tobacco industry product.

[0053] In yet another embodiment, the change in the characteristic of the first sensor is performed at a calibration frequency that is less than the second frequency, and the calibration frequency is in the range of 0.001 Hz to 10 Hz, preferably 0.1 Hz.

[0054] In a preferred embodiment, the light beam is split by a beam splitter 12 into two light beams before reaching a sensor of said type, one of said light beams reaching a first sensor 10 and the other reaching a second sensor 11 .

[0055] In a preferred embodiment, a measuring system for measuring the diameter of a continuous rod of the tobacco industry comprises a sensor unit comprising a first sensor 10 and a second sensor 11, the first sensor being an analog sensor and the second sensor being an analog sensor, the operating frequency of the first sensor 10 being higher than the operating frequency of the second sensor 11. The system further comprises a calculation unit arranged to receive signals from the first sensor and the second sensor and to calculate the diameter of the continuous rod. The calculation unit is arranged to calculate the diameter of the continuous rod based on the signal of the first sensor 10 using a property that the calculated diameter is related to the value of the signal generated by the first sensor. The calculation unit is arranged to calculate the diameter of the continuous rod based on the signal generated by the second sensor 11, wherein the diameter is related to the signal generated by the second sensor 11. The calculation unit is arranged to change the property of the first sensor 10 if the diameter measured by the first sensor 10 is different from the diameter measured by the second sensor 11 at the same point on the continuous rod, so that the value of the signal generated by the first sensor 10 is related to the diameter measured by the second sensor 11.

Claims

1. A method for measuring the diameter of a continuous rod (CR) of a tobacco industry product (R), comprising the following steps: determining measuring sections (S1, S2, S3, S4) on said continuous rod (CR) in relation to the structure of the product (R), determining the measurement time windows (T1, T2, T3, T4) related to the structure of the product (R) and the conveying speed (v) of said continuous rod (CR), The diameter is measured within a determined measuring section (S1, S2, S3, S4) within a determined measuring time window (T1, T2, T3, T4), wherein the determined measuring time window (T1, T2, T3, T4) is synchronized with the determined measuring section (S1, S2, S3, S4).

2. The method according to claim 1, wherein the synchronization between the determined measuring sections (S1, S2, S3, S4) and the determined measuring time windows (T1, T2, T3, T4) is achieved by using a signal representing the cutting moment.

3. A method according to claim 1, wherein synchronization between determined measuring sections (S1, S2, S3, S4) and determined measuring time windows (T1, T2, T3, T4) is obtained by using a signal representing the position of the front end (e) of the tobacco industry continuous rod (CR). 4 . The method according to claim 1 , wherein the measurements within the measuring time window ( T1 , T2 , T3 , T4 ) are performed with a first frequency.

5. Method according to any one of claims 1 to 4, wherein the determined measuring section (S1, S2, S3, S4) covers the entire length of the product (R).

6. Method according to any one of claims 1 to 4, wherein the method comprises more than one measuring section (S) and more than one measuring window (T) per product (R).

7. Method according to claims 1 to 6, wherein the method comprises overlapping measurement sections (S) and overlapping measurement time windows (T) for each product (R).

8. The method according to claim 1, wherein the measuring frequency or the measuring accuracy is different in different measuring time windows (T).

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