Patent Publication Number: US-2004055612-A1

Title: Shredded tobacco feeding apparatus for a cigarette manufacturing machine

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a shredded tobacco feeding apparatus for feeding shredded tobacco to a tobacco band of a cigarette manufacturing machine.  
       BACKGROUND ART  
       [0002] In shredded tobacco feeding apparatus of this type, shredded tobacco is pneumatically conveyed in the process of delivery to the tobacco band, to winnow out midribs, ill-cut shredded tobacco (relatively large uncut shreds), etc. included in the shredded tobacco as a material. More specifically, the shredded tobacco feeding apparatus produces an air flow therein that flows toward the tobacco band, and all of the shredded tobacco is made to fall uniformly into the air flow. A major part of the shredded tobacco is borne by the air flow, thus forming a shredded tobacco stream, while relatively heavy shredded tobacco drop down past the air flow. This stage is a primary separation whereby heavy shredded tobacco (most of which are midribs and uncut shreds) are separated from the shredded tobacco.  
       [0003] The heavy shredded tobacco separated out by the primary separation are further subjected to a secondary separation whereby the shredded tobacco is separated into relatively light shreds and relatively heavy shreds. Specifically, the heavy shredded tobacco separated out by the primary separation are released into an upward flow of air, so that relatively light shreds are conveyed upward by the air flow and join the aforementioned shredded tobacco stream. On the other hand, relatively heavy shreds, such as midribs and ill-cut shreds, drop drown despite the upward air flow and are finally discharged from the shredded tobacco feeding apparatus.  
       [0004] In the process of the second separation, however, if the velocity distribution of the air flow is not uniform, the shredded tobacco fails to be separated smoothly in regions where the flow velocity is relatively low. For example, in the case where the secondary separation is performed in a vertically extending passage, the velocity distribution of the air flow in the passage as viewed in the width direction thereof is such that the flow velocity is lower in widthwise opposite regions of the passage than in the central region. Accordingly, the separation of the shredded tobacco takes place less smoothly in the widthwise opposite regions of the passage than in the central region, possibly causing a situation where shreds that should originally be redirected to the shredded tobacco stream stagnate in the widthwise opposite regions of the passage. Such stagnation hinders smooth separation of the shredded tobacco in the stage of the second separation. Moreover, once the shredded tobacco stagnates, the stagnant tobacco grows upward as shreds are successively fed thereon afterward, possibly causing a situation where the passage is clogged with shreds up to the shredded tobacco stream. Such clogging of the passage with shreds can lead to suspension of the entire cigarette manufacturing machine.  
       [0005] In the field of shred tobacco feeding apparatus, therefore, the clogging of the passage with shredded tobacco should be avoided, and there has been a demand for measures to prevent the clogging.  
       DISCLOSURE OF THE INVENTION  
       [0006] A shredded tobacco feeding apparatus for a cigarette manufacturing machine according to the present invention comprises a feed passage extending to a tobacco band of the cigarette manufacturing machine. Shredded tobacco is made to fall to an inlet of the feed passage to be supplied to the feed passage. Also, the shredded tobacco feeding apparatus produces a flow of air in the feed passage that flows toward a suction surface of the tobacco band, to pneumatically convey the shredded tobacco fallen into the inlet of the feed passage by means of the air flow. The shredded tobacco feeding apparatus further comprises a separation chute and a separation passage. The separation chute has an upper end opening in the vicinity of the inlet of the feed passage and is capable of receiving shredded tobacco that falls down across the air flow. The separation passage has an upper end opening into the feed passage on a downstream side of the separation chute and has a lower end opening downward. The shredded tobacco fallen into the separation chute is collected and delivered to an intermediate portion of the separation passage, and the junction between the separation chute and the separation passage is sealed in an airtight fashion. Also, a flow of air flowing toward the feed passage is produced in the separation passage at a location higher in level than the intermediate portion thereof, thereby allowing outside air to be introduced into the separation passage from the lower end thereof. The shredded tobacco feeding apparatus also comprises detection means arranged in the separation passage at a location lower in level than the intermediate portion thereof for detecting stagnation of the shredded tobacco delivered to the separation passage.  
       [0007] With the shredded tobacco feeding apparatus, all of the shredded tobacco being fed to the tobacco band of the cigarette manufacturing machine is winnowed by the air flow, and relatively heavy shredded tobacco separated out by this primary separation is supplied to the separation passage for a secondary separation. In the secondary separation, the shredded tobacco is winnowed by the flow of outside air introduced into the separation passage from the lower end thereof. Shredded tobacco that is borne on the upward flow of outside air is introduced into the feed passage, while shredded tobacco falling down despite the upward air flow is finally discharged to outside of the separation passage. In the process of the secondary separation, if the shredded tobacco stagnates within the separation passage, such stagnation is detected by the detection means.  
       [0008] Thus, in the shredded tobacco feeding apparatus of the present invention, stagnation of the shredded tobacco in the separation passage can be detected, so that appropriate measures can be taken at an early stage. It is therefore possible to prevent clogging of the separation passage with shredded tobacco, which often leads to suspension of the entire cigarette manufacturing machine, whereby the cigarette production efficiency and production capacity can be significantly improved.  
       [0009] The detection means may comprise an optical sensor, and the optical sensor is preferably of the type wherein detection light is emitted in the width direction of the separation passage from one side wall thereof and is received on the opposite side wall of the separation passage. Once the shredded tobacco stagnates inside the separation passage, the stagnant tobacco grows in size upward in the separation passage. Since the optical axis of the detection light is directed in the width direction of the separation passage, the stagnant tobacco blocks the detection light without fail. Sensing the separation passage widthwise permits reliable and efficient detection of stagnation of the shredded tobacco.  
       [0010] The optical sensor may be of a reflection type. In this case, a reflecting mirror is arranged on one of the opposite side walls defining the width of the separation passage, and an optical sensor is arranged on the other side wall. The reflecting mirror has a reflecting surface facing the other side wall, and the optical sensor has a light emitting/receiving surface for emitting the detection light to the reflecting surface and receiving the reflected light.  
       [0011] Numerous particles of shredded tobacco float inside the separation passage and thus may cover the reflecting surface and the light emitting/receiving surface. Accordingly, the detection means preferably includes air blowing means for ejecting air along the reflecting surface or the light emitting/receiving surface. The ejected air serves to prevent the reflecting surface or the light emitting/receiving surface from being covered with particles of shredded tobacco, or to remove the particles already covering the reflecting surface or the light emitting/receiving surface.  
       [0012] More practically, the shredded tobacco feeding apparatus may further comprise alarm means for providing a predetermined alarm when stagnation of the shredded tobacco in the separation passage is detected by the detection means. In this case, the operator of the shredded tobacco feeding apparatus can ascertain the stagnation of the shredded tobacco in early stages and can take appropriate measures (e.g., removal of the stagnant tobacco) promptly thereafter.  
       [0013] Also, the shredded tobacco feeding apparatus may further comprise removing means for removing stagnation of the shredded tobacco in the separation passage when the stagnation of the shredded tobacco is detected by the detection means. In this case, even if the shredded tobacco stagnates, such stagnation is automatically removed, so that the shredded tobacco feeding apparatus can be operated continuously without the need for maintenance by the operator.  
       [0014] Since an alarm is given upon detection of stagnation of the shredded tobacco, the operator can visually confirm the stagnation and remove the stagnation in early stages. This makes it unnecessary for the operator to constantly watch for stagnation of the shredded tobacco. Further, with the removing means for automatically removing stagnation of the shredded tobacco, the work load on the operator can be mitigated. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015]FIG. 1 is a diagram schematically illustrating the construction of a shredded tobacco feeding apparatus according to an embodiment;  
     [0016]FIG. 2 is a diagram illustrating the arrangement of a secondary separator in more detail;  
     [0017]FIG. 3 is a sectional view of a part of the shredded tobacco feeding apparatus, taken along line III-III in FIG. 1;  
     [0018]FIG. 4 is a diagram illustrating in detail how an optical sensor is mounted;  
     [0019]FIG. 5 is a sectional view taken along line V-V in FIG. 4; and  
     [0020]FIG. 6 is a diagram illustrating in detail how a reflecting mirror is mounted.  
    
    
     [0021] BEST MODE OF CARRYING OUT THE INVENTION  
     [0022]FIG. 1 schematically illustrates part of a shredded tobacco feeding apparatus according to one embodiment of the invention. The shredded tobacco feeding apparatus has a gravity chute  2  extending in a vertical direction, and a needle roller  4  and a picker roller  6  are arranged at an upper end of the gravity chute  2 . Shredded tobacco is made to fall from above the needle roller  4 , and as the shredded tobacco passes between the needle roller  4  and the picker roller  6 , a controlled quantity of tobacco is fed into the gravity chute  2 .  
     [0023] The shredded tobacco feeding apparatus has a feed passage  8  therein. The feed passage  8  extends in a horizontal direction from the lower end of the gravity chute  2 , and a primary damper  10  is arranged in a facing relation to the inlet of the feed passage  8 . The primary damper  10  emits a jet of air horizontally at a location beneath the gravity chute  2 , to supply air into the feed passage  8 . The feed passage  8  extends in the direction of air flow from the primary damper  10 , is curved upward along an upper surface of a tobacco stream trough  12 , and reaches a suction surface of a tobacco band  14 .  
     [0024] Tobacco shreds which are relatively light in weight among those dropping from the lower end of the gravity chute  2  are fed into the feed passage  8  by the air flow jetted from the primary damper  10 . The tobacco stream trough  12  also has air outlet holes (not shown) formed in its curved surface to eject air therefrom. Consequently, the shredded tobacco fed into the feed passage  8  forms a tobacco stream running toward the tobacco band  14  together with the air flow. On the other hand, relatively heavy shreds drop (pass) across the air flow without being fed into the feed passage  8 . Usually, in this primary separation, about 10% of the whole shredded tobacco is winnowed out. A separation chute  16  has an upper end opening in the vicinity of the inlet of the feed passage  8 , and receives the shredded tobacco falling down across the air flow. An air locker  18  is connected to a lower end of the separation chute  16 , and the shredded tobacco falling into the separation chute  16  is successively fed into the air locker  18 .  
     [0025] A secondary separator  20 , which extends vertically inside the shredded tobacco feeding apparatus, has an upper end opening into the feed passage  8  on a downstream side of the separation chute  16  and has a lower end open to outside air. The upper end of the secondary separator  20  is bent in the direction of air flow in the feed passage  8 , and air outlet holes (not shown) are formed in the secondary separator  20  in the vicinity of the junction with the feed passage  8  for jetting air from the secondary separator into the feed passage. Air in the secondary separator  20  is guided into the feed passage  8  due to the air jetted from the air outlet holes, so that outside air is introduced into the secondary separator  20  from the lower open end thereof. The thus-introduced outside air creates an upward flow of air inside the secondary separator  20 .  
     [0026] The secondary separator  20  is also connected to the air locker  18  at a portion thereof intermediate between the upper and lower ends. A star wheel  22  is arranged in the air locker  18  and has six vanes disposed on an outer periphery thereof for keeping the junction between the secondary separator  20  and the separation chute  16  in an airtight state. Also, as the star wheel  22  rotates, it takes in the shredded tobacco from the separation chute  16  and delivers same successively into the secondary separator  20 .  
     [0027] Among the tobacco shreds thus delivered into the secondary separator  20 , relatively light shreds are guided upward together with the outside air introduced from the lower end of the secondary separator, and join the tobacco stream in the feed passage  8 . Usually, in this secondary separation, about 95% of the shredded tobacco delivered into the secondary separator  20  is returned to the feed passage  8 . The remaining relatively heavy shreds, which approximately account for 5%, fall down through the secondary separator  20  despite the upward flow of air and are discharged from the lower open end. The shredded tobacco thus discharged accounts for about 0.5% of the total feed of shredded tobacco from the gravity chute  2  and consists mainly of midribs and uncut shreds. The discharged tobacco is received by an oscillating conveyor  24  and transported to a predetermined processing section.  
     [0028]FIG. 2 illustrates the arrangement of the secondary separator  20  in more detail. The secondary separator  20  has a movable wall  26  and a fixed wall  28 , both of which extend inside the shredded tobacco feeding apparatus in a width direction thereof. The movable wall  26  is coupled to a parallel link mechanism  30 , and as an adjusting lever  32  is moved up or down, the movable wall  26  moves toward or away from the fixed wall  28  by an amount corresponding to the manipulation of the adjusting lever. Thus, the opening (cross-sectional flow area) of the secondary separator  20  can be adjusted by manipulating the adjusting lever  32 , so that the aforementioned discharge ratio of shredded tobacco is controlled in accordance with the opening. A throttling ridge  34  with a triangular cross-sectional form is attached to the fixed wall  28  at a location lower in level than the outlet of the air locker  18 , to increase the average flow velocity of air introduced from outside. The increased flow velocity of air serves to promote the separation of the shredded tobacco delivered from the air locker  18  and also to restrain discharge of shreds that should originally be returned to the feed passage.  
     [0029]FIG. 3 illustrates part of the interior of the shredded tobacco feeding apparatus including the secondary separator  20 . The shredded tobacco feeding apparatus has a pair of side frames  36  and  38  on both sides thereof, respectively, and the side frames  36  and  38  constitute opposite side walls of the shredded tobacco feeding apparatus. The secondary separator  20  has a width extending from one of the side frames  36  and  38  to the other, and accordingly, the side frames  36  and  38  also constitute opposite side walls of the secondary separator  20 .  
     [0030] The side frame  36  has a reflection-type optical sensor  40  attached thereto, while the side frame  38  has a reflecting mirror  42  attached thereto for reflecting detection light. The optical sensor  40  has an optical axis L extending across the secondary separator  20  in the width direction thereof at a location lower in level than the outlet of the air locker  18  and at the same time higher in level than the throttling ridge  34 . The optical axis of the reflection-type optical sensor  40  is easier to adjust than in the case of a transmission type sensor, and thus is suited for the construction wherein the sensor is arranged inside the shredded tobacco feeding apparatus, as in this embodiment.  
     [0031]FIGS. 4 and 5 illustrate in detail how the optical sensor  40  is mounted. The optical sensor  40  is fixed to the outer surface of the side frame  36  through an angle member  44 , and a light emitting/receiving window  46  is cut in the side frame  36  in alignment with the optical axis L of the detection light. A light transmitting cover  48  is fitted in the light emitting/receiving window  46  from inside the secondary separator  20 , and has four corners thereof secured to the side frame  36  by screws. Also, a gasket  50  is disposed outside the light emitting/receiving window  46  in close contact with the outer surface of the optical sensor  40  to seal up the light emitting/receiving window.  
     [0032] A deflector  52  is mounted to the inside of the secondary separator  20  at a location lower in level than the transmitting cover  48 , and has three air outlet holes directed upward. Air pressure supplied through an air pipe  54  is introduced into the deflector  52  through the side frame  36 . The deflector  52  ejects air from its three air outlet holes along the inner surface of the transmitting cover  48 , thereby to prevent particles of shredded tobacco from adhering to the inner surface of the cover or to remove the particles already adhering to the cover. This enables the optical sensor  40  to emit and receive the detection light satisfactorily.  
     [0033]FIG. 6 illustrates in detail how the reflecting mirror  42  is mounted. The reflecting mirror  42  is fitted in the side frame  38  from inside the secondary separator  20 , and has a reflecting surface disposed so as to face the side frame  36 . A light transmitting cover  56  is also fitted in the side frame  38  so as to lie over the reflecting mirror  42 . Thus, the reflecting mirror  42  has its surface covered with the transmitting cover  56 .  
     [0034] As in the case of the optical sensor, the reflecting mirror  42  also is associated with a deflector  52  and an air pipe  54 , both attached to the side frame  38 . The deflector  52  ejects air along the surface of the transmitting cover  56 , thereby to prevent particles of shredded tobacco from adhering to the surface of the transmitting cover or to remove the particles already adhering to the transmitting cover. Thus, the reflecting mirror  42  can satisfactorily reflect the detection light from the optical sensor  40 .  
     [0035] While the basic construction of the shredded tobacco feeding apparatus according to the embodiment has been described, a detection system for detecting stagnation of shredded tobacco by the optical sensor  40  is schematically shown in FIG. 1. As mentioned above, the separation of shredded tobacco in the secondary separator  20  is normally effected by means of the upward flow of outside air introduced from the lower end of the secondary separator. Inside the secondary separator, however, the flow velocity of air is lower in regions near the side frames  36  and  38  than in the central region, and accordingly, the shredded tobacco is prone to stagnate in such regions, without being separated smoothly. In addition, the passage of the secondary separator  20  is narrowed in the region where the throttling ridge  34  exists, and thus stagnant shreds may be obstructed by the ridge  34  and remain there. If such stagnant tobacco grows up to the optical axis L of the optical sensor  40  and blocks the detection light, a controller  58  detects the stagnation of the shredded tobacco based on a detection signal from the optical sensor  40 .  
     [0036] The detection system may include an alarm device  60 , for example. For the alarm device  60 , an alarm buzzer, an alarm lamp, a display for displaying an alarm message, etc. may be used. The alarm device  60  provides a given alarm in response to an actuating signal from the controller  58 . On detecting stagnation of the shredded tobacco (hereinafter merely referred to as “shreds” where appropriate), the controller  58  outputs the actuating signal to the alarm device  60 . In response to the alarm, the operator ascertains that shreds are actually stagnating and opens the front cover of the shredded tobacco feeding apparatus to remove the stagnant shreds, for example. The movable wall  26  is made of a transparent acrylic plate, and accordingly, the interior of the secondary separator can be visually examined with ease.  
     [0037] Also, a means for actively removing the stagnation of shreds may be incorporated in the detection system. Such removing means is implemented, for example, by an air vibrator  62  attached to the movable wall  26 . The air vibrator  62  operates to vibrate the movable wall  26  when supplied with air pressure from a pneumatic device  64 . When stagnation of shreds is detected, the controller  58  outputs an actuating signal to the pneumatic device  64 , which in turn actuates the air vibrator  62 . The movable wall  26  is vibrated by the air vibrator  62 , so that the stagnation of shreds in contact with the inner surface of the movable wall is removed.  
     [0038] The output of the actuating signals from the controller  58  may be controlled such that the operations of the alarm device  60  and air vibrator  62  are integrated, for example. Specifically, when stagnation of shreds is detected by the optical sensor  40 , the controller  58  first actuates the air vibrator  62  in an attempt to remove the stagnation. If the stagnation of shreds is removed (i.e., if no stagnation of shreds is detected any longer) after the air vibrator  62  is actuated for a predetermined time or a predetermined number of times, the controller  58  stops actuating the air vibrator  62  without operating the alarm device  60 . On the other hand, if the stagnation of shreds fails to be removed (i.e., if the stagnation of shreds is continuously detected), the controller  58  operates the alarm device  60  to prompt the operator to remove the stagnation.  
     [0039] Also, a timer function for controlling the output of the actuating signals may be incorporated in the controller  58 . For example, when stagnation of shreds is detected, the controller  58  starts a built-in timer/counter to measure the time elapsed after the detection of the stagnation and, after a lapse of a predetermined time period, actuates the air vibrator  62  or the alarm device  60 . The time period to be measured by the timer/counter may be set as needed in the range of, for example, zero seconds to several seconds. Also, the time period to be measured until the operation of the alarm device  60  is started by the controller  58  may be set appropriately in advance, in order to avoid a situation where the alarm is frequently given due to stagnation of shreds lasting only for a short time.  
     [0040] As described above, the shredded tobacco feeding apparatus of the embodiment has the function of detecting stagnation of shreds in the secondary separator, whereby the load on the operator who watches for clogging of the secondary separator with shreds can be greatly reduced. Also, the detection system can operate the alarm device  60  to urge the operator to remove the stagnation of shreds or actuate the air vibrator  62  to actively remove the stagnation, and thus the stagnation of shreds in the secondary separator  20  is never left unattended for a long time. It is therefore possible to prevent trouble that may possibly lead to suspension of the cigarette manufacturing machine, thus contributing to significant improvement in the operating efficiency of the machine.  
     [0041] Also, the detection light can be satisfactorily emitted/received from/by the optical sensor  40  and reflected by the reflecting mirror  42 , as mentioned above, and accordingly, the detection system ensures high accuracy in detecting stagnation of shreds. Thus, the detection system is free from malfunction, enhancing the reliability of the alarm.  
     [0042] The present invention is not limited to the foregoing embodiment and may be modified in various ways. For example, instead of a single optical sensor  40 , a plurality of sensors may be used. In this case, the optical sensors may be arranged one above another, for example, so that the height of stagnant shreds can be detected by stages. Also, in this case, the actuating signal output control by the controller  58  may be modified as follows: In an initial stage of stagnation, for example, the air vibrator  62  is actuated, and as the stagnation develops, the air vibrator  62  is actuated more frequently. Alternatively, as the height of stagnant shreds progressively increases, the volume of the alarm sounded by the alarm device  60  or the content of the alarm message displayed by the alarm device may be changed.  
     [0043] Also, the optical sensor  40  to be used is not limited to the reflection type, and a transmission-type sensor may be used instead. Further, stagnation of shreds may be detected by using other types of sensors, image processing system, etc.  
     [0044] In the foregoing, the air vibrator  62  is exemplified as the means for removing stagnation of shreds, but the stagnation removing means is not limited to the air vibrator alone. For example, the stagnation removing means may be a motor-driven vibrator which is adapted to vibrate the movable wall  26 . Moreover, the stagnation removing means may be implemented by a means for jetting air toward the stagnant shreds or by a mechanically movable arm for removing the stagnation.  
                                                       2:   gravity chute            4:   needle roller            6:   picker roller            8:   feed passage           10:   primary damper           12:   tobacco stream trough           14:   tobacco band           16:   separation chute           18:   air locker           20:   secondary separator           22:   star wheel           24:   oscillating conveyor           26:   movable wall           28:   fixed wall           30:   parallel link mechanism           32:   adjusting lever           34:   throttling ridge           36, 38:   side frame           40:   optical sensor           42:   reflecting mirror           44:   angle member           46:   light emitting/receiving window           48:   light transmitting cover           50:   gasket           52:   deflector           54:   air pipe           56:   light transmitting cover           58:   controller           60:   alarm device           62:   air vibrator           64:   pneumatic device