Method for inspecting rod-shaped articles

Abstract

The present invention relates to a method for inspecting a rod-shaped article, the method including: providing a first drum having a plurality of seats; providing an inductive sensor having a coil in at least one of the plurality of seats of the first drum; providing a rod-shaped article including a first susceptor in at least one of the plurality of seats of the first drum, the first susceptor including a conductive material; inserting the rod-shaped article into the coil of the inductive sensor; detecting a maximum or minimum value of a parameter function of the impedance of the coil during insertion of the rod-shaped article; and discarding the rod-shaped article based on the maximum or minimum value of the parameter function of the impedance.

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting components of rod-shaped articles, preferably aerosol-generating articles. The inspection according to the method of the present invention is carried out by means of an inductive sensor.

[0002] Aerosol-generating devices are well known and include an aerosol-forming substrate and an induction heating device. The induction heating device includes an induction source that generates an alternating electromagnetic field that induces eddy currents and hysteresis losses that generate heat within a susceptor. The susceptor is in thermal proximity to the aerosol-forming substrate (e.g., a tobacco substrate). The heated susceptor then heats the aerosol-forming substrate, which includes a material capable of releasing volatile compounds capable of forming an aerosol. [Background technology]

[0003] In some components, the susceptor is located within the aerosol-generating article component. Summary of the Invention [Problem to be solved by the invention]

[0004] Due to manufacturing tolerances, it may occur that the susceptor within a component is not in the desired position or does not have the proper orientation. If the susceptor is left in an incorrect position or orientation, it may result in a lack of product compatibility with respect to aerosol delivery when the component is used in an aerosol generating device.

[0005] It is therefore desirable to detect such defects as early as possible to ensure that only conforming products are manufactured and that unnecessary cost and waste is avoided.

[0006] Furthermore, components (including components that include susceptors) are processed at high speeds (e.g., 5000 components per minute, etc.). Therefore, the time window in which such components can be checked to determine compliance with manufacturing requirements is relatively short. For example, when a component is positioned in the combiner drum, it has a high rotational speed, and the time window for sensors to capture the necessary data to evaluate the shape, position, or presence or absence of a susceptor is approximately 200 milliseconds.

[0007] Therefore, it is desirable to detect susceptor-related defects relatively quickly. [Means for solving the problem]

[0008] According to one aspect, the present invention relates to a method for inspecting a rod-shaped article, the method comprising providing a first drum having a plurality of seats. The method preferably comprises providing an inductive sensor having a coil in at least one of the plurality of seats of the first drum. The method preferably comprises providing a rod-shaped article including a first susceptor in at least one of the plurality of seats of the first drum, the first susceptor comprising a conductive material. The method preferably comprises inserting the rod-shaped article into the coil of the inductive sensor. The method preferably comprises detecting a maximum or minimum value of a parameter function of the impedance of the coil during insertion of the rod-shaped article. The method preferably comprises discarding the rod-shaped article based on the maximum or minimum value of the parameter function of the impedance.

[0009] The method of the present invention includes providing a first drum. The first drum defines a drum rotation axis that is adapted for the first drum to rotate around. The first drum can be mechanically driven, for example, by a drum drive with gears or a toothed belt. The first drum may also be driven by an electric drum drive. The first drum preferably has a cylindrical shape. The first drum preferably has an outer surface. The outer surface is, for example, a substantially cylindrical surface having the drum rotation axis as its geometric center.

[0010] The first drum is adapted to convey rod-shaped articles and rotate them about the rotation axis of the first drum. Preferably, the first drum is adapted to convey and rotate a plurality of rod-shaped articles. Preferably, the first drum is adapted to convey and rotate N rod-shaped articles, where 5 < N < 100, more preferably 20 < N < 50.

[0011] The first drum has at least seats, which are preferably formed on the outer surface of the drum. Preferably, the first drum is adapted to hold rod-shaped articles during conveyance within the seats. For example, the first drum is adapted to hold rod-shaped articles within the seats during rotation of the first drum about its rotation axis. The seats preferably extend in the longitudinal axis direction along the seat axis. The seats are adapted to receive rod-shaped articles as the first drum rotates. Preferably, the rod-shaped articles fit within the seats with their longitudinal axis parallel to the seat axis. Each seat is preferably configured to be able to accommodate a rod-shaped article when the seat axis and the longitudinal axis of the rod-shaped article are parallel. More preferably, the seat axis and the longitudinal axis of the rod-shaped article coincide. Preferably, the seats are adapted to accommodate a single rod-shaped article.

[0012] The seat axis is preferably parallel to the rotation axis of the first drum. Therefore, when the rod-shaped article is positioned within the seat, the longitudinal axis of the rod-shaped article is preferably parallel to the rotation axis of the first drum.

[0013] The first drum preferably comprises N seats, where 5 < N < 100, more preferably 20 < N < 50. All seats are preferably formed on the peripheral surface of the first drum. More preferably, the seats are evenly spaced around the outer surface of the first drum. In some embodiments, the first drum comprises 40 seats.

[0014] All seats present within the first drum preferably have the same geometric shape. For example, each seat comprises a receiving surface adapted to contact the outer surface of the rod-shaped article. The receiving surface preferably includes a concave surface, for example a portion of a cylindrical surface. The receiving surface is a part of the outer surface of the first drum. The receiving surface may be a portion of a cylindrical surface having a diameter equal to or slightly larger than the diameter of the rod-shaped article conveyed by the first drum. The axis of the receiving surface defines the seat axis.

[0015] The seat axis is preferably parallel to the rotation axis of the first drum, and thus when the rod-shaped articles are positioned within the seats of the first drum, their longitudinal axes are parallel to the rotation axis of the first drum.

[0016] The first drum also preferably comprises a first side surface and a second side surface located on two opposite sides of the outer surface. The seat preferably extends from the first side surface to the second side surface on the opposite side. The seat may reach the first side surface, or the second side surface, or both, such that the seat is "open" at both ends. Alternatively, the seat ends do not reach the first side surface or the second side surface, in which case the seat is a "closed" seat.

[0017] Each seat preferably includes a suction opening connected to a suction or pneumatic system adapted to hold the rod-shaped articles in the seat by suction while the drum rotates. For example, there may be more than one suction opening depending on the size and weight of the rod-shaped articles.

[0018] In accordance with the present invention, a rod-shaped article is provided in a seat on a first drum. Preferably, the rod-shaped article is provided in a plurality of seats on the first drum. Preferably, the rod-shaped article defines a longitudinal axis. Preferably, the rod-shaped article defines a first end and a second end.

[0019] The cross section of the rod-shaped article along a plane perpendicular to the longitudinal axis is preferably circular or elliptical. However, the rod-shaped article may also have a rectangular or polygonal cross section. The rod-shaped article preferably has a substantially cylindrical outer surface extending along the longitudinal axis. In the case of a substantially cylindrical rod-shaped article, the longitudinal axis corresponds to the axis of the cylinder.

[0020] The rod-shaped article preferably comprises an aerosol-generating article, or a component of an aerosol-generating article, or two or more components of an aerosol-generating article. The component of the aerosol-generating article may comprise an aerosol-forming substrate. The aerosol-forming substrate may comprise a homogenized tobacco material.

[0021] The rod-shaped article further comprises a first susceptor. The first susceptor is preferably in thermal contact with the aerosol-forming substrate. The thermal contact is created to heat the aerosol-forming substrate. Upon heating, the aerosol-forming substrate emits an aerosol. The first susceptor is preferably surrounded by the aerosol-forming substrate. The first susceptor is preferably completely inserted into the rod-shaped article component, i.e., the first susceptor is not visible from the outside of the rod-shaped article. The first susceptor is preferably surrounded in all directions by the aerosol-forming substrate.

[0022] The first susceptor is preferably closer to the first end of the rod-shaped article than to the second end of the rod-shaped article. When a plane perpendicular to the longitudinal axis divides the rod-shaped article into a first half including the first end and a second half including the second end, the first susceptor is preferably located primarily within the first half. The first susceptor is preferably located at or near the first end of the rod-shaped article. The first susceptor is preferably fully inserted within the rod-shaped article component. The first susceptor preferably extends from the first end to the second end of the rod-shaped article component. The first susceptor preferably defines a longitudinal axis. The first susceptor is preferably inserted within the rod-shaped article such that the longitudinal axis of the first susceptor is parallel to the longitudinal axis of the rod-shaped article. The longitudinal axis of the first susceptor is preferably parallel to the longitudinal axis of the rod-shaped article or forms an angle of less than 20 degrees with the longitudinal axis of the rod-shaped article. More preferably, the longitudinal axis of the first susceptor and the longitudinal axis of the rod-shaped article coincide.

[0023] The longitudinal axis of the first susceptor may be the axis of symmetry of the first susceptor.

[0024] The first susceptor is made of a conductive material. Preferably, the first susceptor is made of a metal. Preferably, the first susceptor is made of a ferromagnetic material. Although the first susceptor is made of a conductive material, it may be covered with another material, for example, a solid (e.g., a layer of a different material) or a liquid (e.g., a gel).

[0025] The first susceptor preferably has a strip shape, the thickness of the first susceptor is preferably comprised between 30 micrometers and 60 micrometers, and the length of the first susceptor is preferably comprised between 5 millimeters and 20 millimeters.

[0026] The rod-shaped article is preferably wrapped in a wrapping sheet.

[0027] At least one seat on the drum is associated with an inductive sensor. More preferably, multiple seats on the drum, and even more preferably, all seats on the drum, are associated with an inductive sensor. In the technical field, the terms "inductive sensor" and "induction sensor" are synonymous. An inductive sensor uses a current induced by a magnetic field to detect nearby conductive objects, such as metal objects. An inductive sensor includes a coil, which is an inductor, to generate a magnetic field, such as a high-frequency magnetic field. When a conductive object, such as a first susceptor embedded in a rod-shaped article, is near a changing magnetic field, current will flow in the conductive object. This resulting current flow in the conductive object creates a new magnetic field that opposes the original magnetic field created by the current flowing in the coil. The net effect is to change the impedance, e.g., resistance, of the "coil and first susceptor" system in the inductive sensor. By measuring the impedance, the sensor can determine when a conductive material is brought near the inductive sensor. The change in impedance depends on the type of conductive material from which the object is made, the distance between the object and the sensor, and the size and shape of the object.

[0028] The inductive sensor may be, for example, a Texas Instruments integrated circuit LCD 1101. The inductive sensor preferably measures the equivalent resistance of the first susceptor. The inductive sensor may measure the impedance and resonant frequency of the equivalent system (coil and first susceptor) by adjusting the amplitude of oscillation in a closed-loop configuration at a constant level while monitoring the energy dissipated by the resonator. By monitoring the amount of power injected into the resonator, the inductive sensor can determine the equivalent parallel resistance of the resonator and return it as a digital value.

[0029] Therefore, an inductive sensor is associated with a seat on the drum, preferably multiple inductive sensors are associated with multiple seats on the drum, one sensor per seat, to detect a parameter that is a function of the impedance of the coil. Preferably, a parameter that is a function of the system "coil and first susceptor" is detected.

[0030] The parameter function of the impedance is preferably the impedance Z of the coil itself, or the equivalent resistance of the coil, or the inductance of the coil.

[0031] The inductive sensor includes a coil defining an internal volume. The internal volume is bounded by the windings of the coil. For example, the inductive sensor includes a cylindrical coil with multiple windings of wire. The coil preferably does not include a core, i.e., the internal volume contains air. The internal volume of the coil is preferably large enough to allow at least a portion of a rod-shaped article to be inserted inside the coil. The overall length of the coil is preferably greater than the length of the first susceptor. The length of the first susceptor refers to the nominal length of the first susceptor when measuring the length of the first susceptor is desired. For proper insertion, the inner diameter of the coil is preferably greater than the diameter of the rod-shaped article. The coil preferably defines a longitudinal axis, hereinafter referred to as the coil axis.

[0032] Preferably, the rod-shaped article is inserted into the coil of the inductive sensor. The insertion can be complete, i.e., the entire rod-shaped article is contained within the internal volume of the coil, or only partially, i.e., only a portion of the rod-shaped article is contained within the internal volume of the coil. However, the rod-shaped article is preferably inserted into the coil so that the entire first susceptor is located within the internal volume of the coil during insertion.

[0033] The coil of the inductive sensor is preferably mounted in the seat of the first drum in such a way that the coil axis and the seat axis are parallel to one another, which preferably results in the coil axis and the longitudinal axis of the rod-shaped article being parallel as well when present in the seat.

[0034] The inductive sensor is used to measure a parameter function of the impedance of the coil, which changes due to the presence of the first susceptor inside the rod-shaped article. For this reason, the inspection device preferably includes a control unit. The control unit is electrically connected to the inductive sensor. The control unit refines the signal coming from the inductive sensor to evaluate a parameter function of the impedance, such as the impedance itself. The control unit may be part of the inductive sensor. The control unit may also be adapted to calculate a maximum or minimum of the parameter function of the impedance, as described in more detail below.

[0035] Relative movement between the rod-shaped article and the inductive sensor is effected to insert the rod-shaped article into the inductive sensor.

[0036] Insertion of the rod-shaped article into the coil is preferably performed from a first end of the rod-shaped article. The first susceptor is preferably closer to the first end than to the second end, and therefore the coil required for insertion from the first end is shorter than for insertion from the second end, in order to ensure that the susceptor is fully inserted within the internal volume of the coil. In this way, only a limited portion of the rod-shaped article needs to enter the coil to investigate the properties of the first susceptor.

[0037] The movement for inserting the rod-shaped article into the coil is preferably a linear movement in a direction parallel to the coil axis. The movement is preferably a linear movement parallel to the coil axis. The movement can be either a movement of the rod-shaped article towards the coil (and the coil is stationary), or a movement of the coil towards the rod-shaped article (and the rod-shaped article is stationary), or a movement of both the coil and the rod-shaped article towards each other. When an element is said to be stationary, it is understood that this is being said with respect to the outer surface of the drum. Thus, the coil or the rod-shaped article may be stationary relative to the outer surface of the drum. The outer surface itself rotates during inspection of the rod-shaped article.

[0038] The movement of the coil, or the rod-shaped article, or both, can be performed in many different ways. For example, the coil includes a first half coil and a second half coil. The first half coil and the second half coil are two portions of the coil divided along a plane parallel to the longitudinal axis of the coil. Thus, the first half coil and the second half coil may have different sizes. More preferably, the first half coil and the second half coil are each half of the coil when divided along a plane containing the longitudinal axis of the coil. Each half coil includes multiple half windings. Each half winding is, for example, a circumferential arc, more preferably half a circumference. The circumferential arc of the first half coil and the corresponding circumferential arc of the second half coil form a winding of the coil. The first half coil and the second half coil are movable relative to each other. The movement performed by the first half coil, the second half coil, or both is preferably translational, i.e., linear, movement. The first and second half coils may be in a first operable position in which they are in contact with each other to form a complete coil and allow current to flow through the coil windings. In this first operable position, each half winding of the first half coil corresponds to a half winding of the second half coil. Furthermore, each half winding of the second half coil corresponds to a half winding of the first half coil. In this first operable position, the contact between the first and second half coils is such that current can flow through the coil formed by the two half coils. Thus, the inductive sensor can detect the characteristics of the susceptor. The conductive strip may be formed, for example, on the outer surface of the drum over which the second or first half coil slides.

[0039] In this system, the rod-shaped article is positioned within the seat and remains stationary as the coil is "formed" around it. Therefore, once the rod-shaped article is positioned on the drum seat, no movement of the rod-shaped article is required to obtain a measurement of the parametric function of the susceptor's impedance. Measurements can be very fast due to the rapid measurements possible with inductive sensors. No complex mechanical parts are required to move the rod-shaped article. The rod-shaped article avoids deformation due to improper handling within the drum.

[0040] Alternatively, the rod-shaped article may be pushed into the interior of the coil, for example by ejecting a stream of compressed air while the rod-shaped article is seated in the drum, in which case the coil is stationary and the rod-shaped article moves.

[0041] Preferably, the measurement performed by the inductive sensor is not a single measurement, but multiple measurements. The various measurements are preferably performed at a fixed frequency. Therefore, the measurement of the value function of the impedance of the coil is preferably repeated several times at a given time interval. The repetition is due to the fact that the parameter function of the impedance of the coil varies depending on the distance of the first susceptor from the coil and on the degree of insertion of the first susceptor inside the coil. This value reaches a maximum or minimum value (depending on how the value is calculated) when the first susceptor is completely inserted inside the coil.

[0042] In operation, a rod-shaped article is positioned within the drum seat where the inductive sensor measures a parameter function of the impedance of the coil as it is altered by the first susceptor. The positioning of the rod-shaped article within the seat may be due to, for example, transfer from another drum or conveyor.

[0043] When a rod-shaped object is placed in the seat, a current is generated to flow through the entire length of the coil, allowing detection of a parameter function of the impedance. If the first susceptor is not present, no eddy currents are generated, and there is no change in the magnetic field generated by the coil. Therefore, in this case, the impedance of the coil does not change during insertion. The value of the "unchanged" impedance of the coil is therefore the maximum or minimum value considered.

[0044] In other cases, the impedance value changes as the rod-shaped article approaches the coil (or the coil approaches the rod-shaped article), and this change is detected by various measurements performed by the inductive sensor. The change is preferably detected until the first susceptor is fully inserted into the coil. The change is also preferably detected when the rod-shaped article is extracted from the coil.

[0045] The measurement of the parametric function of the coil impedance has a maximum or a minimum, or both. This maximum or minimum is an indication of the characteristics of the first susceptor. In fact, the signal output by the inductive sensor depends on the material, size, shape, and distance of the first susceptor. The material is known, the distance is measurable, and the size or shape of the first susceptor can be measured. By knowing the size, such as by knowing the weight, the dimensions of the first susceptor can be obtained, for example, from the minimum or maximum of the signal relative to the impedance of the system "coil and first susceptor" measured by the inductive sensor (the impedance of "coil and first susceptor" also depends on the characteristics of the first susceptor). In this way, it can be determined, for example, whether the susceptor is a whole susceptor.

[0046] Using a simple and quick measurement, the rod-shaped article can be discarded if the maximum or minimum of the impedance value function is not as desired. An improper maximum or minimum value of the impedance value function may indicate a first susceptor that is too short, a first susceptor that is too large, a first susceptor that is missing material, a missing first susceptor, more than one first susceptor inserted together, or other.

[0047] The method preferably includes comparing a maximum or minimum value of the impedance parameter function with a threshold value. The method also preferably includes discarding the rod-shaped article based on the comparison. Preferably, this comparison may be performed by a control unit electrically connected to the inductive sensor. The control unit is preferably adapted to receive a signal from the inductive sensor and compare the signal with a threshold value. The inductive sensor preferably measures a parameter function of the impedance of the system formed by the coil and the first susceptor. Eddy currents are generated in the first susceptor, which is made of a conductive material, which in turn generates a magnetic field. The value function of the impedance measured by the inductive sensor depends on the characteristics of the first susceptor. In some inductive sensor embodiments, the inductive sensor measures resistance. In particular, the inductive sensor is adapted to measure the equivalent series resistance of the first susceptor. Preferably, the first susceptor is considered acceptable if the maximum resistance measured by the inductive sensor is comprised between 200 milliohms and 500 milliohms. Due to the fact that the composition of the first susceptor is known, a comparison of the maximum or minimum value of the impedance with a threshold value makes it possible to determine the characteristics of the first susceptor.

[0048] When the first susceptor is absent from the rod-like article, there is no change in the impedance of the coil, and it is assumed that there are generally no other conductive objects contained within the rod-like article, except for the susceptor.

[0049] The method preferably includes measuring the length of the first susceptor during insertion of the rod-shaped article based on a maximum or minimum value of a parameter function of the impedance of the coil. The measurement made by the inductive sensor may be related to the size of the first susceptor. The length of the first susceptor may be calculated by checking the variation of the signal emitted by the inductive sensor according to the position of the rod-shaped article within the coil. The signal emitted by the inductive sensor depends on the impedance of the system coil and the first susceptor. This parameter function of impedance reaches a maximum (or minimum) level when the entire first susceptor is inside the coil and begins to decrease (or increase) as soon as the end of the first susceptor exits the coil. By comparing this signal with the position of the rod-shaped article inside the coil, it is possible to determine the exact length of the first susceptor.

[0050] Preferably, the method includes measuring a parameter function of the impedance of the coil as a function of time during insertion of the rod-like article. The measurement may be performed at a given frequency. Initiation of the measurement can be, for example, detection of the presence of the rod-like article in the drum seat. The frequency may also be variable; for example, a first frequency may be used when the rod-like article and the coil are more than a given distance from each other, and a second frequency may be used when the rod-like article and the coil are less than a given distance from each other. The second frequency is preferably higher than the first frequency. In this way, more measurements are taken when the coil and rod-like article are closer to each other or when insertion occurs. Preferably, measurements are taken during the entire insertion of the rod-like article into the coil. Preferably, the method includes a step of extracting the rod-like article from the coil. Preferably, measurements are taken during extraction of the rod-like article from the coil.

[0051] More preferably, the method includes measuring the length of the first susceptor based on a profile defined by a parametric function of the impedance of the coil as a function of time during insertion of the rod-shaped article into the coil.

[0052] Preferably, the first susceptor has a nominal length, and the step of providing an inductive sensor comprising a coil in at least one of the plurality of seats on the first drum includes providing an inductive sensor comprising a coil having a length longer than the nominal length of the first susceptor in at least one of the plurality of seats on the first drum. To properly evaluate the maximum or minimum of the impedance parameter function, the entire susceptor is preferably inserted into the coil. For this purpose, the coil is preferably longer than the susceptor. In one preferred embodiment of the present invention, the length of the coil is comprised between 20 millimeters and 40 millimeters. The length of the coil is taken along the coil axis.

[0053] Preferably, the rod-shaped article has a longitudinal axis and the first drum has an axis of rotation, and the step of providing the rod-shaped article including the first susceptor in at least one of the plurality of seats on the first drum includes providing the rod-shaped article in at least one of the plurality of seats on the first drum with the rod-shaped article having a longitudinal axis substantially parallel to the axis of rotation. Preferably, the rod-shaped article moves on an axis parallel to the axis of rotation for easy inspection.

[0054] Preferably, the seat has a seat axis and the coil has a coil axis, and the step of providing an inductive sensor having a coil in at least one of the plurality of seats of the first drum includes providing at least one of the plurality of seats of the first drum with a seat axis that is substantially parallel to the coil axis. The rod-shaped article is preferably moved on an axis parallel to the rotation axis for easy inspection. To measure the characteristics of the first susceptor, the rod-shaped article is inserted into the coil. When the coil and the rod-shaped article have their respective axes parallel to each other, the relative movement performed between the coil and the rod-shaped article is a simple linear movement. Therefore, the mechanical structure is relatively simple.

[0055] The drum has a rotation axis, and each of the plurality of seats defines a seat axis, with the seat axes and rotation axes preferably being parallel to one another. All seats preferably have seat axes parallel to the rotation axis of the first drum. All seat axes preferably are parallel to one another. This may result in the longitudinal axis of the rod-shaped article being parallel to the rotation axis of the first drum when the rod-shaped article is positioned within the seat. To determine the properties of the first susceptor, relative movement between the rod-shaped article and the coil (e.g., either movement of the half coil, or movement of the rod-shaped article, or both) is required. A configuration in which the rod-shaped articles are parallel to the rotation axis of the first drum maximizes the number of rod-shaped articles that the first drum can simultaneously host.

[0056] The coil preferably has a diameter comprised between 10 and 20 millimeters. The diameter of the coil considered in this specification is the inner diameter of the coil, i.e. the diameter available for the insertion of a rod-shaped object. The size of the coil is such that a rod-shaped object can be inserted.

[0057] The rod-shaped article preferably has a first end and a second end, and the first susceptor is preferably located at the first end of the rod-shaped article. The step of inserting the rod-shaped article into the coil of the inductive sensor preferably includes inserting the rod-shaped article into the coil of the inductive sensor so that the first end of the rod-shaped article is located within the coil. The rod-shaped article preferably has an "asymmetrically mounted" first susceptor therein. The first susceptor is preferably located, for example, closer to the first end of the rod-shaped article than to the second end. Therefore, insertion of the rod-shaped article into the coil is preferably performed from the first end of the rod-shaped article. In this way, a smaller coil is required to accommodate the entire first susceptor.

[0058] Preferably, the step of discarding the rod-shaped article based on a maximum or minimum value of the impedance parameter function includes discarding the rod shape if the maximum or minimum value of the impedance parameter function is outside a preset range.

[0059] Preferably, the rod-shaped article has a first end, a second end, and a second susceptor, the first susceptor being located at the first end of the rod-shaped article, and the second susceptor being located at the second end of the rod-shaped article. The method preferably includes providing a second drum having a plurality of seats. The method preferably includes providing an inductive sensor having a coil in at least one of the plurality of seats on the second drum. The method preferably includes transferring the rod-shaped article from the first drum to the second drum so that the rod-shaped article is accommodated in at least one of the plurality of seats on the second drum. The method preferably includes inserting the rod-shaped article into the coil of the inductive sensor on the second drum so that the second end of the rod-shaped article is within the coil. The method preferably includes detecting a maximum or minimum value of a parameter function of impedance of the coil of the inductive sensor on the second drum during insertion of the rod-shaped article. The method preferably includes discarding the rod-shaped article based on the maximum or minimum value of the parameter function of impedance.

[0060] In some embodiments, the rod-shaped article may include two susceptors. Therefore, the method uses two drums, a first drum and a second drum, each of which is used according to the first aspect of the present invention described above. When the rod-shaped article includes a first susceptor and a second susceptor, two drums are used. The first susceptor and the second susceptor are preferably located at two opposite distal ends of the rod-shaped article. Therefore, the first inductive sensor measures the impedance of the coil (of the first inductive sensor) changed by the first susceptor located at the first end of the rod-shaped article. The second inductive sensor measures the impedance of the coil (of the second inductive sensor) changed by the second susceptor located at the second end of the rod-shaped article. Preferably, in the first drum, the relative movement between the rod-shaped article and the coil is along a first axis, while in the second drum, the relative movement between the rod-shaped article and the coil is along an axis parallel to the first axis but in the opposite direction. After inspection in the first drum, the rod-shaped articles are preferably transferred to the second drum. Transfer is preferably performed only if the first susceptor is free of defects. Transfer is performed according to standard on-site methods. Therefore, a fast and thorough check of both the first susceptor and the second susceptor is achieved.

[0061] The first and second drums preferably have the same characteristics, so the second drum has the same characteristics as those described above with reference to the first drum.

[0062] The first susceptor and the second susceptor preferably have the same properties, and therefore the second susceptor has the same properties as those described above with reference to the first susceptor.

[0063] The inductive sensor in the first drum and the inductive sensor in the second drum preferably have the same characteristics, and therefore the inductive sensor in the second drum has the same characteristics as those described above with reference to the inductive sensor in the first drum.

[0064] The step of inserting a rod-shaped article into the coil of the inductive sensor preferably includes sliding the rod-shaped article on the bottom surface of the seat to insert the rod-shaped article into the coil. More preferably, the step of sliding the rod-shaped article on the bottom surface of the seat to insert the rod-shaped article into the coil includes pushing the rod-shaped article into the coil with an air flow. For example, the air flow may be generated by a compressed air system. The compressed air system may include a nozzle adapted to discharge a compressed air flow. The main direction of the compressed air flow is preferably parallel to the longitudinal axis of the seat. Thus, the compressed air flow preferably impinges on one of the ends of the rod-shaped article and pushes it toward the coil. The coil is preferably aligned with the seat, i.e., the longitudinal axis of the coil is parallel to or coincides with the longitudinal axis of the rod-shaped article. The longitudinal axis of the coil is preferably parallel to the average axis of the compressed air flow.

[0065] The compressed air system preferably includes a second nozzle for discharging a compressed air flow opposite to the first compressed air flow to push the rod-shaped article out of the coil. The second nozzle preferably faces the first nozzle at a distance. The distance is preferably longer than the length of the rod-shaped article. The first and second nozzles are preferably located on opposite sides of the coil.

[0066] The coil preferably includes a first half-coil and a second half-coil, and the first half-coil and the second half-coil are movable from a first operating position in which the first half-coil and the second half-coil are in contact with each other to form a coil through which current can flow, to a second operating position in which the first half-coil and the second half-coil are separated from each other and no current can flow, and vice versa. The step of inserting a rod-shaped object into the coil of the inductive sensor preferably includes moving the first half-coil and the second half-coil from the second operating position to the first operating position. When the rod-shaped object is positioned within the seat, the first half-coil and the second half-coil are preferably separated from each other and in the second operating position, so that the volume above the seat is "free" and the rod-shaped object can be positioned on the seat without any obstructions. When the rod-shaped object is within the seat, the first half-coil and the second half-coil are moved to the first operating position, allowing detection of the susceptor characteristics. Therefore, the actuator moves the first half coil or the second half coil until the half winding of the first half coil corresponds to the complementary half winding of the second half coil. The control unit commands the actuator to move the second half coil until it reaches the first operating position. The control unit's command may be triggered by an additional sensor that senses the presence or absence of a rod-shaped article in the seat. Therefore, when the sensor senses the presence of a rod-shaped article, it sends a signal to the control unit, which in turn sends a signal to the actuator to bring the first half coil and the second half coil to the first operating position, which may be detected by the inductive sensor. Alternatively, the command sent by the control unit to the actuator is synchronized with the rotation of the first drum. While the first drum rotates, the control unit is adapted to receive or determine the angular velocity of the drum and the insertion point of the rod-shaped article into the first drum. From this information, the control unit may calculate the angular position of each rod-shaped article in the first drum.The control unit may command an actuator in a seat where the inductive sensor resides to move the first half-coil and the second half-coil from the second operating position to the first operating position at a given frequency.

[0067] Preferably, the method includes the step of calibrating the inductive sensor using a rod-like article including the first susceptor, or the second susceptor, or both, having a length equal to the nominal length.

[0068] The step of discarding the rod-shaped article is preferably performed by a rejection device adapted to reject the rod-shaped article based on a signal emitted by the inductive sensor related to a maximum or minimum of the parameter function of the impedance. If the inductive sensor detects that one of the characteristics of the first susceptor inside the rod-shaped article is outside of a specification range, for example, that the first susceptor is not present or that the length of the first susceptor is too short or too long, the rod-shaped article is preferably not further processed. Rod-shaped articles containing "defective" first susceptors are transferred to a rejection drum, for example, different from the first drum to which rod-shaped articles containing valid susceptors are transferred. The control unit preferably controls a suction system that keeps the rod-shaped articles in their seats in such a way that rod-shaped articles containing defective susceptors are ejected from the seats differently from rod-shaped articles containing valid susceptors. The control unit preferably distinguishes between valid susceptors and defective susceptors. The distinction is preferably based on the characteristics of the susceptor detected by the inductive sensor.

[0069] "Impedance" is a generalization of resistance with a complex value. Impedance Z is a complex number that represents V (voltage) / I (current). For an ideal inductor L such as a coil, the impedance Z L is given by the following formula: TIFF0007823039000001.tif6150 TIFF0007823039000002.tif11170

[0070] TIFF0007823039000003.tif6170

[0071] Hereinafter, the term "rod-shaped article" may refer to any element that may be included within an aerosol-generating article, or it may refer to the complete aerosol-generating article. Such elements are well known in the art and will not be described in further detail below. For example, such a rod-shaped article may include a filter plug, a heat source, a tobacco rod, a charcoal element, etc. Preferably, the rod-shaped article is a plant material-containing article, in particular a tobacco-containing article. The tobacco article may include tobacco cut filler or aerosol-forming reconstituted tobacco. The article may comprise a tobacco rod that is burned or heated. A rod-shaped article according to the present invention may be a complete assembled aerosol-generating article, or may be an element of an aerosol-generating article that is combined with one or more other components to provide an assembled aerosol-generating article for producing an aerosol, such as, for example, a consumable part of a heated smoking device.

[0072] The components of the aerosol-generating article preferably include a tobacco-containing material that includes volatile tobacco flavor compounds that are released from the aerosol-generating substrate upon heating.

[0073] Preferably, the rod-shaped article may include a heat source or a volatile flavor-generating component, such as a menthol capsule, a charcoal element, or a susceptor.

[0074] Furthermore, the rod-shaped article may include multiple components of an aerosol-generating article combined together, or even something other than an aerosol-generating article.

[0075] As used herein, the term "susceptor" refers to a material capable of converting electromagnetic energy into heat. When placed in an alternating electromagnetic field, eddy currents are induced in the susceptor, and hysteresis losses occur, causing the susceptor to heat. When the susceptor is placed in thermal contact with or in close thermal proximity to the aerosol-forming substrate, the aerosol-forming substrate is heated by the susceptor, thereby forming an aerosol. The susceptor is preferably disposed in direct physical contact with the aerosol-forming substrate, for example, within the aerosol-forming tobacco substrate.

[0076] The susceptor may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. A preferred susceptor may include or consist of a ferromagnetic material (e.g., a ferromagnetic alloy, ferritic iron, or ferromagnetic steel or stainless steel). A suitable susceptor may be or include aluminum. A preferred susceptor may be heated to temperatures exceeding 250 degrees Celsius. A suitable susceptor may include a non-metallic core having a metal layer disposed thereon (e.g., a metal track formed on the surface of a ceramic core). The susceptor may have a protective outer layer, such as a protective ceramic or glass layer, encapsulating the susceptor. The susceptor may include a protective coating formed of glass, ceramic, or an inert metal formed over a core of susceptor material.

[0077] The susceptor may be a multi-material susceptor and may include a first susceptor material and a second susceptor material. The first susceptor material is disposed in close physical contact with the second susceptor material. The second susceptor material preferably has a Curie temperature lower than 500°C. The first susceptor material is preferably primarily used to heat the susceptor when it is placed in a fluctuating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum or an iron-based material such as stainless steel. The second susceptor material is preferably primarily used to indicate when the susceptor has reached a specific temperature (the Curie temperature of the second susceptor material). The Curie temperature of the second susceptor material can be used to regulate the temperature of the entire susceptor during operation. Therefore, the Curie temperature of the second susceptor material should be below the ignition point of the aerosol-forming substrate. Suitable materials for the second susceptor material may include nickel and certain nickel alloys.

[0078] The susceptor preferably has the form of a filament, rod, sheet, or strip. When the susceptor has a constant cross-section, for example, a circular cross-section, the outline preferably has a width or diameter of about 1 mm to about 5 mm. When the susceptor has a sheet or strip shape, the sheet or strip preferably has a rectangular shape with a width of about 2 mm to about 8 mm, more preferably about 3 mm to about 5 mm (e.g., 4 mm), and a thickness of about 0.03 mm to about 0.15 mm, more preferably about 0.05 mm to about 0.09 mm (e.g., 0.07 mm).

[0079] Preferably, the rod-shaped article may have a length of about 5 millimeters to about 20 millimeters, preferably about 8 millimeters to about 16 millimeters (e.g., about 12 millimeters). In some cases, the rod-shaped article may have a length of about 40 millimeters to about 85 millimeters.

[0080] In the following, the term "length" refers to the length of a rod-shaped article along its longitudinal axis, unless otherwise specified.

[0081] In the following, the term "rod-like" refers to a generally cylindrical element of substantially cylindrical, oval or elliptical cross section, although other prismatic forms with different cross sections are also possible.

[0082] As used herein, an "aerosol-generating article" is any article that generates an inhalable aerosol when the aerosol-forming substrate is heated. This term includes articles that include an aerosol-forming substrate that is heated by an external heat source, such as an electric heating element. The aerosol-forming article may be a non-combustible aerosol-generating article, which is an article that releases a volatile compound without combustion of the aerosol-forming substrate. The aerosol-forming article may also be a heated aerosol-generating article, which is an aerosol-generating article that includes an aerosol-forming substrate that is intended to be heated, rather than burned, to release a volatile compound that can form an aerosol. This term includes articles that include an aerosol-forming substrate and an integrated heat source (e.g., a combustible heat source).

[0083] The aerosol-generating article may comprise a mouthpiece element, which may be located at the mouth end or downstream end of the aerosol-generating article.

[0084] The aerosol-generating article may comprise at least one filter element.

[0085] The filter segment may be a cellulose acetate filter plug made from cellulose acetate tow. The filter segment may have low or very low particulate filtration efficiency. The filter segment may be longitudinally spaced from the aerosol-forming substrate. The filter segment may have a longitudinal length of 5 millimeters to about 14 millimeters. The filter segment may have a length of about 7 millimeters.

[0086] The plurality of elements of the aerosol-generating article may include at least one of a support element and an aerosol-cooling element.

[0087] The aerosol-generating article preferably comprises a wrapper around the multiple elements of the aerosol-generating article in the form of a rod. The wrapper may comprise at least one of paper and foil.

[0088] As used herein, the term "aerosol-forming substrate" refers to a substrate formed from or including an aerosol-forming material capable of releasing volatile compounds upon heating to generate an aerosol. The aerosol-forming substrate may contain tobacco material, or may contain non-tobacco material, or may contain a combination of both tobacco and non-tobacco material. The aerosol-forming substrate may be a cellulose material impregnated with nicotine, and preferably includes one or more flavors. Advantageously, the aerosol-forming substrate comprises a tobacco material, preferably a homogenized tobacco material, preferably a tobacco material that includes one or more aerosol formers. As used herein, the term "homogenized tobacco material" refers to a material formed by agglomerating particulate tobacco.

[0089] The aerosol-forming substrate preferably contains volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may comprise or consist of a blended tobacco cut filler, or may contain homogenized tobacco material. The homogenized tobacco material may be formed by agglomerating particulate tobacco. The aerosol-forming substrate may additionally contain a non-tobacco-containing material, for example, a homogenized plant-derived material other than tobacco.

[0090] The aerosol-forming substrate is preferably a (preferably crimped) tobacco sheet comprising tobacco material, fiber, binder, and aerosol former. The tobacco sheet is preferably a cast leaf. Cast leaf is a form of reconstituted tobacco formed from a slurry containing tobacco particles, fiber particles, aerosol former, binder, and, for example, flavors.

[0091] The tobacco particles may be in the form of tobacco dust having particles of about 30 micrometers to 250 micrometers, preferably about 30 micrometers to 80 micrometers, or about 100 micrometers to 250 micrometers, depending on the desired sheet thickness and casting gap, which typically defines the thickness of the sheet. The size of the tobacco particles refers to the Dv95 size of the tobacco particles in the volume distribution.

[0092] The fiber particles may also include tobacco stem material, petioles or other tobacco plant material, and other cellulosic fibers (such as wood fibers with low lignin content). The fiber particles may be selected based on the desire to produce sufficient tensile strength in the cast leaf at low lignin content, for example, about 2 percent to 15 percent. Alternatively, fibers such as plant fibers may be used in conjunction with or in place of the above-mentioned fiber particles, including hemp and bamboo.

[0093] The aerosol former included in the slurry forming the cast leaf or used with other aerosol-forming substrates may be selected based on one or more characteristics. Functionally, the aerosol former provides a mechanism for volatilizing the aerosol former when heated above the aerosol former's specific volatilization temperature, enabling the aerosol former to deliver nicotine, flavorings, or both in an aerosol state. Different aerosol formers typically vaporize at different temperatures. The aerosol former may be any suitable known compound or mixture of compounds that facilitates the formation of a high-density, stable aerosol during use and that is substantially resistant to thermal decomposition at the operating temperatures of the induction heating device to be used with the inductively heatable tobacco substrate. The aerosol former may be selected based on its ability to remain stable at or near room temperature, for example, but to volatilize at higher temperatures, e.g., between 40°C and 450°C.

[0094] The aerosol former may also have humectant-type properties that help maintain a desired amount of moisture in the aerosol-forming substrate when the substrate comprises tobacco-derived products, particularly when the substrate contains tobacco particles. In particular, some aerosol formers are hygroscopic materials that function as humectants, i.e., materials that help keep humectant-containing tobacco substrates moist.

[0095] One or more aerosol formers may be combined to take advantage of one or more properties of the combined aerosol formers, for example, triacetin may be combined with glycerin and water to take advantage of triacetin's ability to carry active ingredients and glycerin's humectant properties.

[0096] The aerosol former may be selected from polyols, glycol ethers, polyol esters, esters, fatty acids, and may include one or more of the following compounds: glycerin, erythritol, 1,3-butylene glycol, tetraethylene glycol, triethylene glycol, triethyl citrate, propylene carbonate, ethyl laurate, triacetin, meso-erythritol, diacetin mixtures, diethyl suberate, triethyl citrate, benzyl benzoate, benzyl phenylacetate, ethyl vanillate, tributyrin, lauryl acetate, lauric acid, myristic acid, propylene glycol.

[0097] The aerosol-forming substrate may contain other additives and ingredients (such as flavourings). Preferably the aerosol-forming substrate contains nicotine and at least one aerosol former.

[0098] Aerosol-generating articles according to the present invention may be in the form of combustible filtered cigarettes or other smoking articles in which tobacco material is combusted to form smoke.

[0099] Preferably, the aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-generating article may have a length and a circumference substantially perpendicular to the length. The aerosol-generating article may have an overall length of about 30 mm to about 100 mm, more preferably 40 mm to 55 mm. The aerosol-generating article may have an outer diameter of about 5 mm to about 12 mm, more preferably 6 mm to 8 mm.

[0100] The present invention is defined in the claims. However, the following provides a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0101] Example 1: A method for inspecting a rod-shaped article, comprising: providing a first drum having a plurality of seats; providing an inductive sensor having a coil in at least one of the plurality of seats of the first drum; providing a rod-shaped article including a first susceptor in at least one seat of a plurality of seats of a first drum, the first susceptor including a conductive material; Inserting a rod-shaped article into a coil of an inductive sensor; detecting a maximum or minimum value of a parameter function of the impedance of the coil during insertion of the rod-shaped article; and discarding the rod-shaped article based on a maximum or minimum value of the parameter function of impedance. Example 2: comparing a maximum or minimum value of the impedance parameter function with a threshold value; and discarding the rod-shaped article based on the comparison. Example 3: The method of example 1 or example 2, comprising determining the length of the first susceptor based on a maximum or minimum value of a parameter function of the impedance of the coil during insertion of the rod-shaped article. Example 4: 4. The method according to one or more of Examples 1 to 3, comprising measuring a parametric function of the impedance of the coil as a function of time during insertion of the rod-shaped article. Example 5: The method of example 4, comprising measuring the length of the first susceptor based on a profile defined by a parametric function of the impedance of the coil as a function of time during insertion of the rod-shaped article into the coil. Example 6: A method for manufacturing a semiconductor device, the method comprising the steps of: a first susceptor having a nominal length; and providing an inductive sensor comprising a coil in at least one seat of a plurality of seats of the first drum; 6. The method of one or more of Examples 1-5, comprising providing an inductive sensor in at least one of the plurality of seats of the first drum, the inductive sensor comprising a coil having a length longer than a nominal length of the first susceptor. Example 7: A method for manufacturing a substrate, the method comprising the steps of: providing a rod-shaped article having a longitudinal axis; a first drum having an axis of rotation; and providing a rod-shaped article including a first susceptor in at least one seat of a plurality of seats on the first drum, the rod-shaped article including the first susceptor, the step comprising: The method of one or more of Examples 1-6, comprising providing a rod-shaped article having a longitudinal axis substantially parallel to the axis of rotation in at least one of the plurality of seats of the first drum. Example 8: A method for manufacturing a semiconductor device, comprising the steps of: a rod-shaped article having a first end and a second end; a first susceptor located at the first end of the rod-shaped article; and inserting the rod-shaped article into a coil of an inductive sensor, the step comprising: 8. The method of one or more of Examples 1-7, comprising inserting a rod-shaped article into the coil of the inductive sensor such that a first end of the rod-shaped article is located within the coil. Example 9: The step of discarding rod-shaped articles based on a maximum or minimum impedance value comprises: 9. The method according to one or more of examples 1 to 8, comprising discarding the rod shape if the maximum or minimum value of the parameter function of impedance is outside a preset range. Example 10: A rod-shaped article has a first end and a second end and a second susceptor, the first susceptor being located at the first end of the rod-shaped article, and the second susceptor being located at the second end of the rod-shaped article, and providing a second drum having a plurality of seats; providing an inductive sensor having a coil in at least one of the plurality of seats of the second drum; transferring the rod-shaped article from the first drum to the second drum such that the rod-shaped article is received in at least one seat of the plurality of seats on the second drum; inserting a rod-shaped article into the coil of the inductive sensor on the second drum such that a second end of the rod-shaped article is within the coil; detecting a maximum or minimum value of a parameter function of the impedance of the coil during insertion of the rod-shaped article; Discarding the rod-shaped article based on a maximum or minimum value of the parametric function of impedance. Example 11: The step of inserting a rod-shaped article into the coil of an inductive sensor comprises: 11. The method of one or more of Examples 1-10, comprising sliding the rod-shaped article on the bottom surface of the seat so as to insert the rod-shaped article into the coil. Example 12: The step of sliding a rod-shaped article on the bottom surface of the seat so as to insert the rod-shaped article into the coil comprises: 12. The method of claim 11, comprising pushing the rod-shaped article into the interior of the coil with an air stream. Example 13: The coil comprises a first half-coil and a second half-coil, the first half-coil and the second half-coil being movable from a first operating position in which the first half-coil and the second half-coil are in contact with each other to form a coil through which a current can flow to a second operating position in which the first half-coil and the second half-coil are separated from each other and no current can flow, and vice versa, and the step of inserting a rod-shaped article into the coil of the inductive sensor includes: 11. The method of one or more of examples 1-10, comprising moving the first half-coil and the second half-coil from the second operating position to the first operating position. Example 14: 14. The method of one or more of Examples 1-13, comprising calibrating the inductive sensor using a rod-shaped article comprising the first susceptor, or the second susceptor, or both, having a length equal to the nominal length. Example 15: The method of any one or more of Examples 1 to 14, wherein the rod-shaped article comprises a component of an aerosol-generating article. Example 16: The method according to one or more of Examples 1 to 15, wherein the parameter function of the impedance of the coil is the impedance of the coil itself Z, or the equivalent resistance R of the coil, or the inductance L of the coil. Example 17: The method of any one or more of Examples 1 to 16, wherein the rod-shaped article comprises an aerosol-generating article or a component of an aerosol-generating article. Example 18: The method of Example 17, wherein the aerosol-generating article comprises an aerosol-forming substrate. Example 19: The method of example 18, wherein the aerosol-forming substrate comprises homogenized tobacco material. Example 20: The method of example 18 or example 19, wherein the aerosol-forming substrate surrounds the susceptor. Example 21: A method of manufacturing a rod-shaped article comprising an aerosol-generating article, or a component of an aerosol-generating article comprising an aerosol-forming substrate, the method comprising inspecting the rod-shaped article according to one or more of the methods of Examples 1 to 20.

[0102] The embodiments will now be further described with reference to the following figures: [Brief explanation of the drawings]

[0103] [Figure 1] FIG. 1 is a schematic perspective view, partially in section, of a rod-shaped article containing a susceptor to be inspected in accordance with the method of the present invention. [Figure 2] FIG. 2 is a side view of the rod-shaped article of FIG. [Figure 3] FIG. 3 is a schematic perspective view of an inspection apparatus in a first configuration that functions in accordance with a first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic perspective view of an inspection apparatus that functions in accordance with a second embodiment of the present invention. [Figure 5] 5A to 5C are schematic top views of the inspection apparatus of FIG. 4 in a time sequence. [Figure 6] FIG. 6 shows the sequence of steps for the functioning of the inductive sensor present in the test device of the present invention. [Figure 7] FIG. 7 is a detailed cross-sectional view of an element of the inspection device of FIG. 3, FIG. 4, or FIG. [Figure 8] FIG. 8 is a front view of the elements of FIG. [Figure 9] FIG. 9 is a side view of another embodiment of a rod-shaped article to be inspected in accordance with the present invention. [Figure 10] FIG. 10 is a third embodiment of an inspection device that functions in accordance with the present invention. [Figure 11] FIG. 11 shows two enlarged views of two details of FIG. 10 in two different embodiments. [Figure 12] FIG. 12 shows two enlarged views of two details of FIG. 10 in two different embodiments. [Figure 13] 13 shows two cross-sectional views of the coil of the first embodiment of the inspection device of FIG. 3 in a first configuration and a second configuration, respectively. [Figure 14] 14 shows two cross-sectional views of the coil of the first embodiment of the inspection device of FIG. 3 in a first configuration and a second configuration, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0104] Referring first to FIGS. 1 and 2, an example of a rod-shaped article is generally designated 60. As shown in FIG.

[0105] Preferably, the rod-shaped article 60 comprises several components of an aerosol-generating article (eg, a complete aerosol-generating article).

[0106] The aerosol-generating article 60 comprises a plurality of elements assembled, for example, in the form of a rod. The plurality of elements may comprise a plug element 11, an aerosol-forming substrate 10 in the form of a tobacco plug, a susceptor material 12 positioned within the aerosol-forming substrate 10, a hollow acetate tube 16, a further hollow acetate tube 18, a mouthpiece 2, and an outer wrapper 22. The aerosol-generating article 60 comprises a mouth end 24 and a distal end 26. The rod-shaped article 60 defines a longitudinal axis 61.

[0107] The above-listed elements preferably extend one after the other along the longitudinal axis 61 of the rod-shaped article 60. All elements preferably have the same diameter.

[0108] The cross section of the rod-shaped article 60 along a plane perpendicular to the longitudinal axis 61 is preferably circular.

[0109] The rod-shaped article 60 has a preferably substantially cylindrical outer surface 13 extending along a longitudinal axis 61. The longitudinal axis 61 of the rod-shaped article 60 may correspond to the axis of a cylinder.

[0110] The aerosol-forming substrate 10 may comprise a homogenized tobacco material.

[0111] The susceptor 12 is preferably in thermal contact with the aerosol-forming substrate 10 so that when the susceptor is inductively heated, heat is transferred to the aerosol-forming substrate 10, thereby emitting an aerosol. The susceptor 12 is preferably completely surrounded by the tobacco material that forms the aerosol-forming substrate 10.

[0112] As shown in the embodiment of FIGS. 1 and 2, the susceptor 12 is completely contained within the rod-shaped article 60, and more preferably, completely contained within the aerosol-forming substrate 10.

[0113] The susceptor 12 is made of an electrically conductive material, preferably a metal, and in some embodiments, a ferromagnetic material.

[0114] According to a preferred embodiment, as shown in Figures 1 and 2, the susceptor 12 has the shape of a strip. Alternatively, it may have the shape of a rod. Its thickness is preferably comprised between 30 micrometers and 60 micrometers. The length of the susceptor is preferably comprised between 5 millimeters and 20 millimeters.

[0115] FIG. 3 shows a portion of a preferred embodiment of the drum 4 of the inspection device 100 according to the first aspect of the present invention.

[0116] For clarity, the inspection apparatus 100 is only partially shown in FIG.

[0117] As will become apparent from the following description, the inspection device 100 is adapted to control the quality of the rod-shaped articles 60, in particular the susceptors 12.

[0118] The quality control provided by the inspection apparatus 100 may involve checking the presence, integrity, or correct position of the susceptor 12 as well as any of additional characteristics.

[0119] By way of non-limiting example, such characteristics may include one or more of the length of the susceptor, the thickness of the susceptor, the deviation of the susceptor from linear extension, the deviation of the axis of the susceptor from parallelism with the longitudinal axis 61 of the rod-shaped article 60, and the electromagnetic properties of the susceptor.

[0120] Also, quality control may be carried out at any stage of the manufacturing process of the aerosol-generating article, meaning that the rod-shaped article 60 can be checked when the aerosol-forming substrate 10 is joined to the mouthpiece filter element 2, or any other component fixed thereto, or the aerosol-forming substrate 10 itself, including the susceptor 12, can be checked.

[0121] Referring again to Figure 3, the drum 4 comprises a plurality of seats 41, each adapted to receive a rod-shaped article 60. The seats 41 are preferably located on the outer surface 40 of the drum 4. There are preferably about 20 to 60 (preferably about 40) seats 41 on the drum 4.

[0122] In some embodiments, the drum 4 is cylindrical in shape, and preferably the outer surface 40 on which the seat 41 is located corresponds to the lateral surface of the cylinder.

[0123] Of course, seats 41 are preferably sized and shaped to at least partially receive rod-shaped article 60. Both the size and shape of seats 41 are preferably selected to receive rod-shaped article 60. More generally, quality control preferably involves positioning rod-shaped article 60 in one of seats 41.

[0124] Positioning of the rod-shaped article 60 may occur either by using a suitable positioning device (not shown in the drawings) or by transferring the rod-shaped article 60 in any other possible manner, for example from another drum or conveyor.

[0125] In some embodiments, the testing apparatus 100 may be included in a facility for manufacturing aerosol-generating articles, and the rod-shaped articles 60 may be transferred to the testing apparatus 100 from a conveyor element of the facility.

[0126] The drum 4 is preferably a rotating drum having an axis of rotation 67. As a result, the drum 4 is able to transport the rod-shaped article 60 from a first position to a second position, preferably forming an entrance position where it is positioned on a seat and an exit position where it is removed from the seat. The first and second positions (not depicted in FIG. 3) are separated by an angular rotation of the drum.

[0127] In some embodiments, the seats 41 may be oval shaped to define respective seat axes 42. The seat axes 42 and the rotation axes 67 of the seats 41 are preferably parallel to one another. All axes 42 of the multiple seats 41 are preferably parallel to one another.

[0128] The seat 41 is preferably formed on the outer surface 40 of the drum 4. The seat 41 may also be in the form of a recess realised on the outer surface 40 of the drum 4.

[0129] Nevertheless, it is sufficiently clear that the seat 41 may also be defined by other elements on the outer surface of the drum 4, for example fixed thereto and projecting radially therefrom.

[0130] The drum 4 preferably defines a front face 64 and a rear face (not visible). The rear face is axially opposite the front face 64.

[0131] In some embodiments, the seat 41 may extend from the front surface 64 to the rear surface, i.e., the seat may be provided with opposite open ends.

[0132] In this manner, the rod-like article 60 may be received within the seat 41 by approaching the seat laterally, preferably by sliding along the direction defined by the seat axis 42 .

[0133] As shown in the embodiment of Figure 3, the seat 41 may have a length at least equal to the length of the rod-like article 60 to be checked. Longer seats 41 (which allow the rod-like article 60 to slide therein) may also be used.

[0134] In some embodiments, the axis of rotation 67 of the drum 4 is substantially horizontal.

[0135] The seat 41 may be configured so that the rod-shaped article 60 is ejected from the seat 41 when the rod-shaped article 60 reaches a particular angular position along the rotation axis 67 where gravity acts on the rod-shaped article 60 to release the rod-shaped article 60 from the drum 4.

[0136] The inspection device 100 further includes an inductive sensor 5 positioned at least in one of the plurality of seats 41. It will be appreciated that although the embodiment of Figure 3 depicts a single inductive sensor 5 positioned in a particular seat 41, each seat 41 of the drum 4 may include a respective inductive sensor 5.

[0137] Also, according to a further possible embodiment, an inductive sensor 5 may be provided at selected locations 41, for example at a predetermined angular distance.

[0138] The inductive sensor 5 preferably includes a coil 51 defining an interior volume 50 large enough to receive at least the end of a rod-shaped article 60 therein.

[0139] 7 and 8 show a coil 51 according to a preferred embodiment.

[0140] Coil 51 defines a coil axis 70 and preferably has an inner diameter 71 comprised between 10 millimeters and 18 millimeters, more preferably between 12 millimeters and 16 millimeters. Preferably, inner diameter 71 of coil 51 is 14 millimeters.

[0141] Naturally, the above diameters are selected to make the coil 51 wide enough to receive the mouth end 24 or distal end 26 of the rod-shaped article 60 therein, while at the same time avoiding bulky elements for use in the inspection device 100.

[0142] In some embodiments, the length of the coil 51 is adapted to completely accommodate the rod-shaped article 60 therein.

[0143] Preferably, the length 72 of the coil is comprised between 20 mm and 40 mm, more preferably between 25 mm and 35 mm. The length 72 of the coil 51 is preferably 32 mm.

[0144] In some embodiments, the coil 51 is formed by a pair of parallel wound wires.

[0145] Preferably, the coil 51 has a total number of turns comprised between 26 and 46. More preferably, the number of turns comprises between 30 and 42. Preferably, the number of turns is 32.

[0146] If the coil 51 is formed by a pair of wires, each wire may have half the total number of turns mentioned above.

[0147] The coil 51 is preferably cylindrical in shape and is preferably positioned in the seat such that the coil axis 70 is parallel to the seat axis 42.

[0148] The presence of the susceptor 12 within the rod-shaped article 60 may be sensed by moving the rod-shaped article 60 relative to the coil 51 and considering fluctuations in the feedback signal generated by the interaction between the susceptor 12 and the coil 51.

[0149] To this end, in some embodiments as in FIG. 3, the inspection apparatus 100 comprises a control unit 7 electrically connected to the inductive sensor 5 and adapted to receive a signal from the inductive sensor 5 and to compare the signal with a threshold value in order to detect fluctuations in the signal caused by the presence of the susceptor 12.

[0150] Of course, such fluctuations in the signal may be caused either by moving the coil 51 relative to the rod-shaped article 60, as in the embodiment of Figure 3, or by moving the rod-shaped article 60 relative to the coil 51, as in the embodiment of Figure 4 or Figure 5.

[0151] In general, it will be appreciated that the inductive sensor 5 may generate an alternating magnetic field within the coil 51 that changes when passed by the susceptor 12. More generally, the inductive sensor 5 is configured to generate an alternating magnetic signal in a detection direction that preferably corresponds to the axis 70 of the coil 51.

[0152] The magnetic field generated by the inductive sensor 5 preferably changes when the first end 24, 26 of the rod-shaped article 60, within which the susceptor 12 should be located, is received within the internal volume 50 of the coil 51 of the inductive sensor 5.

[0153] In other words, the magnetic field generated by the passage of the susceptor 12 through the internal volume 50 of the inductive sensor 5 acts against the magnetic field generated by the sensor 5, i.e., by the coil 51. According to Lenz's law, the susceptor 12 acts as a resistor in the coil 51, or more generally in the inductive sensor 5.

[0154] More specifically, when a ferromagnetic material enters a magnetic field, an electromagnetic force is induced in it (Maxwell-Faraday's law), which generates alternating eddy currents. This alternating current generates an induced magnetic field (Maxwell-Ampere's law) that opposes the sensor's magnetic field (Lenz's law).

[0155] The presence or absence of susceptor 12 within rod-shaped article 60 may accordingly be determined in terms of this expected behavior in the magnetic field. If no change occurs when rod-shaped article 60 passes through the alternating magnetic field generated by coil 51, susceptor 12 is likely not present within rod-shaped article 60.

[0156] In contrast, the change may be determined by calculating the impedance of the rod-like article 60, which changes as the susceptor 12 passes through the interior volume 50 of the coil 51, as previously explained.

[0157] According to a preferred embodiment, the feedback signal generated as the susceptor 12 passes through the interior volume 50 can be used to determine other characteristics of the susceptor 12 .

[0158] Referring to FIG. 6, a possible use of the feedback signal may be for the purpose of determining the length of the susceptor 12 .

[0159] FIG. 6 shows how the equivalent resistance of the system “coil and susceptor” varies according to the relative position of the susceptor 12 within the internal volume 50 .

[0160] Initially, when no rod-shaped article 60 is present in the interior volume 50, the feedback signal output by the inductive sensor 5 does not change.

[0161] As the rod-like article 60 enters the interior volume 50, a fluctuation in the feedback signal occurs.

[0162] The feedback signal reaches a minimum level when the entire susceptor 12 is completely inside the inner volume 50 and begins to decrease as soon as the end of the susceptor 12 exits the coil 51 .

[0163] By comparing this signal with the position of the rod-like article 60 within the interior volume 50, the length of the susceptor 12 can be determined.

[0164] The length of the susceptor 12 is preferably estimated according to the peak of the measured equivalent resistance, which is determined after appropriate calibration.

[0165] Alternatively, the impedance parameter function exhibits a maximum rather than a minimum when the susceptor is fully inserted into the coil.

[0166] In such an embodiment, the coil 51, or more generally the internal volume 50 of the inductive sensor 5, is longer than the expected length of the susceptor 12, also according to the coil characteristics mentioned above.

[0167] The length of the coil 51 is preferably selected to be at least 10 millimeters per side longer than the expected length of the susceptor 12 to avoid distortion of the magnetic field at the ends of the coil.

[0168] According to a preferred embodiment, the control unit 7 is configured to determine whether the length of the susceptor 12 corresponds to an expected value by checking the variation of the feedback signal with the position of the rod-shaped article 60 in the internal volume 50.

[0169] Naturally, the control unit 7 may also be adapted to calculate the length of the susceptor 12 located within the rod-shaped article 60 according to different methods, for example taking into account other specific behaviors of the inductive sensor 5 generally during the interaction of the rod-shaped article 1 with the internal volume 50.

[0170] More generally, the equivalent resistance of the feedback signal may indicate the nature or consistency of the shape or composition of the susceptor 12. As a result, further characteristics of the susceptor 12 may be determined by the inspection apparatus 100 of the present invention.

[0171] To introduce the rod-shaped article 60 into the coil 51, in the inspection device 100 of FIG. 3, the coil 51 is divided into two half-coils 65 and 66. The first half-coil 66 is positioned below the outer surface 40 of the drum 4, while the second half-coil 66 is positioned above the outer surface 40 of the drum 4. The two half-coils 65, 66 can be moved from a first operating position shown in FIG. 13, where the two half-coils form the coil 51. In this first operating position, the measurements described above with the inductive sensor, for example, those shown in FIG. 6, can be performed. In the second operating position depicted in FIGS. 3 and 13, the second half-coil 65 is moved along the coil axis 70 and spaced apart from the first half-coil, allowing the rod-shaped article 60 to be positioned within the seat 41. The movement is performed by an actuator 6 connected to a control unit 7.

[0172] In operation of the inspection device 100 of Figures 3, 13, and 14, a rod-shaped article 60 is inserted into the seat 41. When the rod-shaped article is positioned in the seat, the first half coil 66 and the second half coil 65 are in the second operating position, i.e., the two half coils 65, 66 are separated from each other, as in Figures 3 and 14. Once the rod-shaped article 60 is in the seat, the first half coil 66 and the second half coil 65 are moved to the first operating position of Figure 13 so that measurements can be taken using the inductive sensor 5. The relative movement of the first and second half coils is as follows: the first half coil 66 is positioned below the outer surface 40 and is fixed relative to it, while the second half coil 65 is translated back and forth from the first operating position of Figure 14 to the second operating position of Figures 3 and 14, and vice versa. The shifting of the second half coil 65 from the first operating position to the second operating position, and vice versa, is achieved by a piston 69 connected to the actuator 6. The piston 69 is attached to the second half coil and moves the second half coil linearly towards and away from the first half coil, as shown by arrow 68 in Figure 3.

[0173] In a different embodiment of the present invention depicted in FIGS. 4 and 5, instead of the movement of the coil relative to the rod-shaped article as in the embodiments of FIGS. 3, 13, and 14, the movement of the rod-shaped article 60 relative to the coil 51 is performed. In the inspection apparatus 200, the same reference numerals as used in the inspection apparatus 100 are used to identify the same elements. In the inspection apparatus 200, the inductive sensor 5 includes a coil 51, which in this case is attached to the outer surface 40 of the drum 4. The coil 51 (better seen in FIGS. 7 and 8) is located, for example, at one end of the seat 41. The inspection apparatus 200 includes a compressed air system 8, 9 including a compressed air generator 9 and a gun 8 for discharging a compressed air flow. The gun may discharge a compressed air flow in a direction substantially parallel to the seat axis 42, and therefore parallel to the longitudinal axis of the rod-shaped article 60. The gun may be located on one side of the drum 4 and may be stationary, i.e., not rotate with the drum. In this way, a single compressed air system may be used for all seats 41. During rotation, as the rod-shaped article passes in front of the gun 8, a stream of compressed air is discharged, which pushes the rod-shaped article 60 into the coil 51, and the inductive sensor 5 can be used to make the measurements mentioned above. This is shown in FIG. 5, which depicts a series of "screen shots" taken at successive time intervals. At the left edge of the figure, the rod-shaped article 60 is inserted into the seat 41. In a subsequent rotation, the seat with the rod-shaped article 60 passes in front of the gun 8, and a stream of compressed air is discharged by the gun 8 along the direction 83. The rod-shaped article 60 is then pushed into the coil 51 (see the snapshots below from left to right in the figure (up to the dashed line 64)).

[0174] A dashed line 84 separates Figure 5 in two. The second part of Figure 5 to the right of dashed line 84 is taken some time interval later than the part to the left (see below for details).

[0175] The inspection apparatus 100, 200 of the present invention may also comprise a rejection device (schematically depicted as a rectangle 82 in the right part of FIG. 5 ) adapted to reject rod-shaped articles 60 that do not have a susceptor 12 therein or that have a susceptor 12 that does not conform to expected characteristics. As previously explained, the rod-shaped articles 60 may advantageously be rejected based on a signal emitted by the inductive sensor 5, according to a calculation or determination made by the control unit 7. As shown in the right part of FIG. 5 , for example, the effect of the rejection device 82 is to keep defective rod-shaped articles 60 in drum 4 while valid rod-shaped articles 60 are transferred to other drums (not shown) for continuing processing.

[0176] The rod-shaped article 600 may also include a first susceptor 12 and a second susceptor 121 as depicted in Figure 9. The rod-shaped article 600 substantially includes two rod-shaped articles 60 according to the embodiment of Figures 1 and 2.

[0177] When the rod-shaped article 600 includes two or more susceptors, it is preferable to provide an inspection apparatus according to the third embodiment as the inspection apparatus 300 of FIG.

[0178] The inspection apparatus 300 includes two or more checking drums 4, at least a first drum and a second drum, each of which includes a coil 51. The first drum or the second drum is identical to the drum 4, which can be according to either the first embodiment of Figures 3 and 13-14 or the second embodiment of Figures 4 or 5. However, it is preferred that the drums are of the same type, i.e. according to either the first embodiment of the inspection apparatus 100 or the second embodiment of the inspection apparatus 200.

[0179] The first drum 4 is adapted to check the first susceptor 12 of the rod-shaped article 600, while the second drum 4 is adapted to check the second susceptor 121 of the rod-shaped article 600. For example, if the first drum and the second drum are according to the second embodiment of Figures 4 and 5, in the first drum, the compressed air system is located on the first side of the first drum, and in the second drum, the compressed air system is located on the second side of the second drum.

[0180] 11 and 12, after the first susceptor 12 is inspected, the rod-shaped article 600 is transferred from the first drum to the second drum. The first drum and the second drum are substantially in contact with each other. The gap between the first drum and the second drum is such that the rod-shaped article 600 can be inserted therebetween. The transfer takes place between the seat of the first drum and the seat of the second drum.

[0181] In Figure 11, the transfer between two drums 4 according to the first embodiment of Figures 3, 13 and 14 is shown. In Figure 12, the transfer between two drums 4 according to the second embodiment of Figures 4 and 5 is shown.

[0182] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all instances to be modified by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Accordingly, in this context, the number A is understood as A ± 10 percent. Within this context, the number A may be considered to include a numerical value that is within the common standard error for measurement of the property represented by the number A. In some cases, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel property(ies) of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. A method for inspecting a rod-shaped article, comprising: providing a first drum having a plurality of seats; providing an inductive sensor including a coil in at least one of the plurality of seats of the first drum; providing a rod-shaped article including a first susceptor in the at least one seat of the plurality of seats of the first drum, the first susceptor including an electrically conductive material; inserting the rod-shaped article into the coil of the inductive sensor; detecting a maximum or minimum value of a parametric function of the impedance of the coil during said insertion of the rod-shaped article; and discarding the rod-shaped article based on the maximum or minimum value of the parameter function of the impedance.

2. comparing the maximum or minimum value of the parameter function of the impedance with a threshold; and discarding the rod-shaped article based on the comparison.

3. The method according to one or more of claims 1 to 2, comprising measuring the length of the first susceptor based on the maximum or minimum value of the parameter function of the impedance of the coil during the insertion of the rod-shaped article.

4. A method according to one or more of the preceding claims, comprising measuring said parametric function of said impedance of said coil as a function of time during said insertion of said rod-shaped article.

5. 5. The method of claim 4, comprising measuring the length of the first susceptor based on a profile defined by the parametric function of the impedance of the coil as a function of time during insertion of the rod-shaped article into the coil.

6. the first susceptor has a nominal length, and the step of providing an inductive sensor comprising a coil in at least one seat of the plurality of seats on the first drum comprises:

6. The method according to claim 1, further comprising providing an inductive sensor in at least one of the plurality of seats of the first drum, the inductive sensor comprising a coil having a length longer than the nominal length of the first susceptor.

7. the rod-shaped article having a longitudinal axis, the first drum having an axis of rotation, and providing a rod-shaped article including a first susceptor in the at least one seat of the plurality of seats on the first drum; 7. The method of claim 1, further comprising providing the rod-shaped article in the at least one seat of the plurality of seats of the first drum, the rod-shaped article having the longitudinal axis substantially parallel to the axis of rotation.

8. the rod-shaped article having a first end and a second end, the first susceptor being located at the first end of the rod-shaped article, and the step of inserting the rod-shaped article into the coil of the inductive sensor includes:

8. The method according to one or more of the preceding claims, comprising inserting the rod-shaped article into the coil of the inductive sensor so that the first end of the rod-shaped article is located within the coil.

9. the step of discarding the rod-shaped article based on the maximum or minimum value of the parameter function of the impedance, 9. The method according to one or more of the preceding claims, comprising discarding the rod-shaped article if the maximum or minimum value of the parameter function of the impedance is outside a preset range.

10. the rod-shaped article having a first end and a second end and a second susceptor, the first susceptor being located at the first end of the rod-shaped article and the second susceptor being located at the second end of the rod-shaped article; and providing a second drum having a plurality of seats; providing an inductive sensor including a coil in at least one of the plurality of seats of the second drum; transferring the rod-shaped article from the first drum to the second drum such that the rod-shaped article is received in the at least one seat of the plurality of seats on the second drum; inserting the rod-shaped article into the coil of the inductive sensor on the second drum such that the second end of the rod-shaped article is within the coil; detecting a maximum or minimum of the parameter function of the impedance of the coil during the insertion of the rod-shaped article; and discarding the rod-shaped article based on the maximum or minimum value of the parameter function of the impedance.

11. the step of inserting the rod-shaped article into the coil of the inductive sensor, The method according to one or more of the preceding claims, comprising sliding the rod-shaped article on the bottom surface of the seat so as to insert the rod-shaped article into the coil.

12. the step of sliding the rod-shaped article on the bottom surface of the seat so as to insert the rod-shaped article into the coil, 12. The method of claim 11, comprising pushing the rod-shaped article into the interior of the coil with an air current.

13. the coil includes a first half-coil and a second half-coil, the first half-coil and the second half-coil being movable from a first operating position in which the first half-coil and the second half-coil are in contact with each other to form the coil through which current can flow, to a second operating position in which the first half-coil and the second half-coil are separated from each other and no current can flow, and vice versa, and the step of inserting the rod-shaped article into the coil of the inductive sensor includes: The method according to one or more of the preceding claims, comprising moving the first half-coil and the second half-coil from the second operating position to the first operating position.

14. 14. The method according to one or more of the preceding claims, comprising calibrating the inductive sensor using a rod-shaped article comprising the first susceptor, or the second susceptor, or both, having a length equal to the nominal length.

15. A method according to one or more of the preceding claims, wherein the rod-shaped article comprises a component of an aerosol-generating article.

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