Abstract:
A tray unloader for rod-like articles of the tobacco industry includes a horizontally-movable, slidable carriage supporting an independently-driven tray inverting carrier arranged to pick up an upright full tray from a receiving position and invert it during movement to an unloading position. In the unloading position articles are received directly over opposed horizontal bands having a delivery channel between confronting ends and defining the initial level at which articles are received over most of the width of the tray. Downstream of the channel is a conveyor which operates at a relatively high rate during a first phase of unloading for each tray and at a reduced rate during a second phase, so as to allow controlled emptying of the tray and establishment of the residual level of articles in the channel after completion of unloading of each tray.

Description:
This application is a continuation of PCT/GB99/03285, filed Oct. 5, 1999. 

   BACKGROUND OF THE INVENTION 
   This invention relates to container unloading apparatus, particularly apparatus for unloading containers of rod-like articles such as cigarettes or cigarette filter rods. 
   In the cigarette industry it is known to transport cigarettes and cigarette filter rods in trays, each of which typically contains 4,000 articles, at least partly between a producing machine, such as a cigarette or filter rod making machine, and a receiving machine, such as a cigarette packing machine or a filter rod assembling machine. In the case of cigarettes containers may be unloaded at the packing machine, or upstream of it for conveyance to the packing machine in a multi-layer stream of articles. In the case of filter rods, although the containers may similarly be unloaded at the filter rod assembling machine, it is common to unload them at or upstream of a pneumatic filter rod distributor unit, from which filter rods are pneumatically conveyed to the filter rod assembling machine. Again, the filter rods may be conveyed in a multi-layer stream of articles subsequent to unloading. The present invention is particularly, but not exclusively, concerned with apparatus suitable for unloading trays in any of these situations. 
   BRIEF SUMMARY OF THE INVENTION 
   According to a first aspect of the invention apparatus for unloading containers for rod-like articles comprises a carrier for receiving a full container in a receiving position in a first orientation, and means for moving the carrier to an unloading position at which the carrier is in a second orientation, the moving means including means for translating the carrier and means for rotating the carrier. The translating means and rotating means are preferably independently controlled, so that relative translation and rotation between the receiving and unloading positions may be varied. Preferably the translating means is linear. The receiving and unloading positions may be substantially at the same level, eg so that the path of the translating means is substantially horizontal. Preferably the rotating means is effective to rotate the carrier so that a container is rotated between said first and second orientations, eg through substantially 180° so that a container is upright at the receiving position and inverted at the unloading position. 
   In a preferred arrangement the translating means and the rotating means are reversible. In this case an unloaded container may be moved from the unloading position to a position intermediate the unloading and receiving positions, from which intermediate position transfer means may remove the unloaded container, eg in a direction transverse to the path of said translating means. 
   In a preferred arrangement the carrier means comprises a carnage slidable between the container receiving and unloading positions and a rotatable carrier mounted on the carriage. 
   The location of the unloading position may be determined by reference to the contents of the container, eg the lengths of the rod-like articles relative to a fixed datum position. 
   Means may be provided for advancing containers to the receiving position, eg on substantially horizontal conveyor bands. Particularly where the containers are advanced in abutment at least adjacent the receiving position, it is preferred that said translating means and rotating means are arranged such that initial movement of a container away from the receiving position includes both translational and rotational components: in this way a container may be removed from a flat surface containing an abutting line of containers upstream of the receiving position. 
   Preferably at least one of the translating and the rotating means includes means for moving the carrier to a preferred position following a stoppage. Such means may include means for interrogating at least one detector for the position of the carrier and subsequently moving the carrier to a reference position in a direction determined by the results of said interrogation. 
   According to another aspect of the invention apparatus for unloading containers of rod-like articles comprises means for delivering a container to an unloading position at which articles are unloaded though an open end of the container, and means for conveying unloaded articles away from the unloading position along a path, wherein the conveying means extends substantially across said open end at said unloading position except at said path. Preferably the extent of said path is substantially less than the extent of said open end, so that the conveying means extends across a substantial part of the width of said open end, eg with the path arranged centrally of said width. Preferably the container is so orientated at said unloading position (eg inverted) that said open end and said conveying means extend substantially horizontally with said conveying means immediately below said open end. In this way articles unloaded from the container, eg by release of a plate confining the articles in the container, have a very small distance to fall onto the conveying means. The level of articles already unloaded in said path may be controlled such that it is substantially the same as that of said conveying means. In a preferred arrangement the conveying means comprises endless band conveyor means, preferably opposed bands defining said path between their confronting ends. 
   By arranging that the conveying means is substantially immediately adjacent the open end of the container at the unloading position, the distance through which articles have to move at the unloading position from the container is both small and determinate, thereby eliminating or substantially reducing the disadvantages experienced in some prior art arrangements, namely that relatively complicated mechanisms are needed to maintain a surface of unloaded articles relatively flat to receive the next unloaded batch from a container and/or that there is a risk of unloaded articles becoming misaligned as they fall through an excessive distance onto that surface after unloading. 
   According to a further aspect of the invention apparatus for unloading containers of rod-like articles comprises means for delivering a container to an unloading position, and means for conveying unloaded articles away from the unloading position, wherein the conveying means is driven at a first relatively high speed during a first phase during which a first, major part of the contents of a container are unloaded and at a second, lower speed during a second phase during which the remainder of the contents of a container are unloaded. Preferably the transition between said first and second phases takes place dependent on a signal from detector means sensing the level of articles in or from an unloading container. Preferably the conveying means includes first conveyor means immediately adjacent the unloading container and second conveyor means downstream of said first conveyor means for conveying away a multi-layer stream of articles. The ratio of speeds of the first and second conveyor means preferably differs in said first and second phases: in one arrangement wherein the first conveyor means comprises confronting band conveyors and the second conveyor means comprises a further band conveyor the ratio of the speeds of the first conveyor means to the second conveyor means is 55% in the first phase and 105% in the second phase. It will be appreciated that these ratios will vary at least dependent on the height of any stream being conveyed by the second conveyor means. 
   Further detector means may be provided for stopping the conveying means substantially when the contents of a container have been unloaded. The further detector means may comprise a level detector arranged in the path of unloading articles immediately downstream of the unloading position. 
   The conveying means may convey a stream of articles to a variable capacity reservoir. Articles unloaded from a container may be received in the reservoir, which may have associated with it sensors for detecting the relative capacity of the reservoir and for controlling the conveying means in accordance with a signal derived from the sensor. 
   The various aspects of the present invention may be embodied in common apparatus. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS. 
     The invention will be further described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: 
       FIG. 1  is a perspective view of part of an apparatus for unloading trays of rod-like articles, 
       FIG. 2  is a perspective view of part of the apparatus of  FIG. 1  with some parts in different operative positions, 
       FIG. 3  is a side view of the apparatus as shown in  FIG. 2 , 
       FIG. 4  is a side view, similar to  FIG. 3  but with some parts in different positions, 
       FIG. 5  is a schematic side view showing relative operative positions of the apparatus of FIG.  1 . 
       FIG. 6  is a front view of the apparatus, in the direction of arrow VI in  FIG. 3 , 
       FIG. 7  is a detail plan view of part of the apparatus of  FIG. 1 , and 
       FIG. 8  is a perspective view of part of the apparatus of  FIG. 1 , showing details of a drive arrangement for a tray carriage. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows tray handling apparatus for delivering full trays  10  containing rod-like articles (not shown) to an unloading position  10 A at which the trays are inverted to unload the articles to a conveyor system  12  ( FIG. 6 ) in which the articles are conveyed away in a multi-layer stream of articles moving transverse to their lengths. Full trays  10  are delivered in an upright condition to a pick-up position  10 B by an upper conveyor comprising laterally spaced bands  14 . As shown in  FIG. 5 , trays  10  are normally disposed in abutment upstream of the tray in position  10 B, which tray is maintained stationary by a pivoted latch  16  (FIG.  3 ), so that the bands  14  may continue to operate with an abutting line of stationary trays maintained up to the position  10 B by the latch. 
   Referring also to  FIG. 8 , a tray carriage  18  is supported by and slidably movable relative to a pair of slideways comprising linear actuators  20  which extend parallel to the bands  14  from positions laterally adjacent the pick-up position  10 B. The carnage  18  comprises a frame  19  spanning and movable along the actuators  20  between positions adjacent the positions  10 A and  10 B under action of a servo drive motor  22  (FIG.  2 ). The frame  19  is attached to load plates  21  of the actuators  20  such that the carriage  18  is cantilevered beyond the travel limit  25  of the actuators when it is in the unloading position  10 A. The motor  22  operates both actuators  20  through a common shaft  23 . 
   A tray carrier  24  is pivotally supported at  26  on the carriage  18  and is pivotable, under action of a servo drive motor  28 , through 180° between a position at which it can receive an upright tray  10  at the position  10 B and a position at which it maintains an inverted tray at the unloading position  10 A. Referring to  FIGS. 1-3 , the tray carrier  24  comprises a backplate  30 , against which the rear face of a tray  10  is located when a tray is in place in the carrier, and a pair of pivoted side clamps  32  which operate under action of a pneumatic cylinder  34  operating through a rotor  36  and a pair of links  38 , to clamp a tray in place on the carrier. The clamps  32  comprise an over centre mechanism and have the added capability of pulling a slightly misaligned tray into alignment on the carrier  24  as they clamp the tray. Also mounted on the carrier  24  is a release plate  40  which, in the position shown in  FIG. 1 , covers the open top of a tray received from the pick-up position  10 B and is slidably supported by guides  42  so as to be movable, under action of a pneumatic cylinder  44 , into a retracted position following insertion of a tray  10  at the unloading position  10 A, as shown in FIG.  2 . 
   As will be explained hereinafter, trays  10  which have been unloaded are returned by the tray carrier  24  to an upright condition in a position intermediate positions  10 A and  10 B. An empty tray transfer mechanism  46  receives each empty tray and deposits it on an empty tray conveyor comprising laterally spaced bands  48  located below the bands  14 . The mechanism  46  comprises a tray support  50 , on which the base of the tray  10  is received, and a clamp  52  which is pivoted to the support about a horizontal axis and movable between a position clear of the support to allow reception of a tray from above and the position shown in the drawings, in which it engages the upper surface of the base of the tray to locate it on the support. The support  50  is mounted on a four bar (parallel bar) linkage  54  so as to be maintained in the same orientation as it is moved between a tray receiving position (above the position shown in  FIG. 4 ) and a tray delivering position, as shown in  FIGS. 1-3 , in which the empty tray is deposited on the bands  48  which subsequently convey the tray away. The linkage  54  is pivotally connected to the support  50  and to a fixed backplate  60 , and is operated by an actuating rod  56  and a linear actuator with braking capability in the form of an Acme lead screw  58 , itself pivotally connected to a fixed part  62  of the apparatus. The connection between the actuating rod  56  and the linkage  54  is by way of a pivotal mounting in a bracket  64  connected to the linkage: in  FIG. 4  the end of the rod  56  is shown separated from the bracket  64  but in operative condition these would be connected, as shown in FIG.  3 . 
   In operation, trays  10  filled with rod-like articles are advanced by the bands  14  in the direction indicated in  FIG. 1. A  leading tray  10  is stopped at the position  10 B, engaged by the latch  16  (FIG.  3 ). Normally trays  10  accumulate in line abutment on the bands  14  behind a tray in position  10 B, as indicated in FIG.  5 . 
   The carriage  18  is advanced towards the position  10 B with the carrier  24  in an upright condition and the tray clamps  32  in retracted positions. A leading part of the carriage  18  has a part (eg an inclined face, not shown) adapted to cooperate with the inclined leading face of the latch  16  so as to pivotally displace it when the carriage reaches the position  10 B and allow the leading full tray  10  to be engaged by the carrier  24 . At this time the clamps  32  are operated to grip the tray  10 . The release plate  40  may be moved to an extended position to cover the open top of the tray at any time after a tray has emptied and before the next full tray begins to be turned over: one currently preferred timing is to extend the plate when the carriage is in position  10 C ( FIG. 5 ) just prior to delivery of an empty tray to the empty tray transfer mechanism  46 . 
   After a tray  10  has been located on the carrier  24  by the clamps  32 , the motors  22  and  28  operate substantially simultaneously so that initial movement of the tray from the position  10 B includes linear and rotational components. This facilitates removal of a tray from the position  10 B when there is an immediately abutting following tray on the bands  14  (by providing a compound movement which draws the bottom trailing corner of the tray upwards and forwards). After a leading tray has been withdrawn from the position  10 B the latch  16 , released from its displacement by the carriage  18 , returns under action of a counterweight to its previous position so that the next tray advanced by the bands  14  is stopped at position  10 B. 
   The carriage  18  moves away from the position  10 B and the carrier  24  is rotated through 180° to invert the tray  10 , such movement and rotation being complete at the unloading position  10 A. The motors  22  and  28  are independently controlled: hence the relative rates (including acceleration and deceleration) at which the carriage  18  may be moved and the carrier  24  rotated are independently controllable. In this way, it is possible to adjust the positions of the carriage  18  at which the carrier  24  assumes given rotational positions: although initiating linear and rotational movement at the same time at the position  10 B is preferred, linear and rotational movements may start at different times and proceed continuously or intermittently at different rates, eg the start of rotational movement could be delayed until some movement of the carriage  24  has occurred or rotational movement of the carrier  24  may be completed in stages so that after an initial movement the carrier is maintained in a fixed inclined position while the carriage moves for some distance. The relative rates and positions at which linear and rotational movements take place may be varied in accordance with parameters associated with the articles contained in the trays: for example, cigarettes are more delicate than filter rods and so may not tolerate such rapid inversion of a tray. Another possibility is that the relative rates of linear and rotational movement may be varied in accordance with the lengths of the articles contained in the trays. 
   At the unloading position  10 A the release plate  40  is withdrawn, allowing the articles contained in the tray to descend to the conveyor system  12 . The apparatus includes a transparent stationary front plate  66  ( FIG. 5 ) at the unloading position  10 A and extending also at the front of the conveyor system  12 , to confine the articles if necessary. 
   When unloading of the contents of a tray at the unloading position  10 A is complete, the carriage  18  is retracted and the carrier  24  rotated to an upright condition during movement to the position  10 C (FIG.  5 ), intermediate the positions  10 A and  10 B. As before, relative rotational and linear movements may be adjustable: as the tray is empty during this phase of movement, no consideration as to imposition of excessive forces on delicate articles is necessary. 
   At the position  10 C the empty tray  10  is delivered to the empty tray transfer mechanism  46 . The linkage  54  is raised so that the support  50  abuts the bottom of the tray  10  and the clamp  52  is pivoted upwards and subsequently down onto the upper face of the bottom of the tray to clamp it to the support. The pivoted clamps  32  on the carrier  24  are retracted to release the tray, which is subsequently moved down on the support by the linkage  54  until it rests on the upstream ends of the bands  48  in position  10 D (FIG.  5 ). The clamp  52  is retracted just prior to placement of the empty tray  10  on the bands  48  so that the empty tray can be conveyed away from position  10 D by the bands. During the initial part of movement of the empty tray transfer mechanism  46 , as soon as the tray is clear of the carrier  24 , the carriage  18  is advanced from position  10 C to position  10 B to pick up the next fill tray  10  and commence the next cycle. 
   It will be apparent that the position of the carriage  18  is critical to correct operation of the unloading apparatus. Thus, after any stoppage, eg disconnection from an electrical supply, it is arranged that the carriage  18  is moved by the motor  22  to a preferred definite position from which subsequent movements are made as determined by the control system. As shown in  FIG. 7 , in order to achieve this the carriage  18  carries with it a sensor bar  94  which moves along a path parallel to and adjacent one of the actuators  20  as the carriage moves. The sensor bar  94  is stepped so as to comprise a first, longer portion  96  and a second, shorter portion  98 . Fixed to the (stationary) frame of the actuator  20  and just below the path of the bar  94  are three sensors  100 ,  102 ,  104 , each capable of detecting when the bar  94  is located above the sensor. 
   The carriage  18  is movable between end positions  18 A and  18 B as shown in FIG.  7 . Position  18 A is beyond the tray unloading position  10 A and position  18 B is beyond the full tray pick-up position  10 B. Sensor  100  is located so that it is just covered by the bar  94  at position  18 B, as indicated in FIG.  7 . Sensor  104  is located so that it is just covered by the shorter portion  98  of the bar  94  at position  18 A. At an intermediate position  18 E, approximately halfway between positions  18 A and  18 B, the sensor  102  is just covered by the end of the longer portion  96  of the bar  94  when the carriage  18  is in position  18 B; in other words, the length of the portion  96  just exceeds the distance between sensors  100  and  102 . 
   In operation, after any stoppage sensor  102  is used to determine if the carriage  18  is to the left (as viewed in  FIG. 7 ) of position  18 E (the sensor is covered by the portion  96 ) or if it is to the right (the sensor is uncovered). Subsequently, in either case the carriage  18  is moved towards position  18 E, and the switching transition (between sensor  102  being covered and uncovered or vice versa) used to determine when that position is reached. At that position the movement is stopped and the absolute position of the carriage  18  is reestablished, at the known reference position  18 E. The carriage  18  can then perform a precisely controlled movement to any position along its path. 
   If the carriage  18  reaches position  18 A or  18 B, each of which is beyond the respective end of the normal operating range of movement of the carriage, sensor  100  or  104  detects this and signals a fault. 
   It will be appreciated that position of the carrier  24  is similarly critical to correct operation of the apparatus. A precisely analogous control system is provided to move the carriage  24  into a reference rotational position, the only difference being that the parts corresponding to the sensor bar  94  and the corresponding sensors are arranged on an arcuate path about the axis  26 . 
   In the tray unloading position  10 A the position at which the carriage  18  stops may be adjustable: in this way it is possible, if required to operate the apparatus so that the unloading position is determined by reference to the articles contained in the tray, eg so that the free ends of the articles are located a fixed distance from the plate  66 , instead of by reference to parts of the tray or apparatus itself. The position at which the carriage  18  stops at the pick-up position  10 B may be similarly adjustable: in particular this may need to be varied if for instance a different style of tray  10  were used necessitating a different tray clamping mechanism. 
   Referring to  FIG. 6 , the conveyor system  12  downstream of the unloading position  10 A comprises confronting endless bands  70  having horizontal upper runs arranged substantially immediately below the unloading position  10 A. Extending from the opening between the ends of the bands  70  is a vertical channel  72  leading to a further conveyor band  74  extending horizontally towards a variable capacity reservoir  76 . An upper band  78  is arranged above the band  74  along part of its length. 
   The reservoir  76  comprises an arcuate top plate  80  and an arcuate side plate  82  arranged opposite the downstream end of the conveyor band  74  and pivotable about an axis  84  so as to be movable between the position shown in full lines in  FIG. 6  (in which the reservoir  76  is substantially fill) and the position  82 A shown in dotted lines (in which the reservoir is substantially at its minimum capacity). At its lower end the reservoir  76  has an outlet  86  leading downwards onto a horizontal conveyor band  88 . A top band  90  is arranged above the downstream end of conveyor band  88 . 
   Rod-like articles unloading from a tray at position  10 A are urged by conveyor bands  70  into channel  72 . A substantially continuous multi-layer stream of articles is received in the channel  72  and delivered by way of bands  74  and  78  to the variable capacity reservoir  76 . The pivoted plate  82  is lightly counterweighted so that it is urged in a clockwise direction as shown in  FIG. 6  to maintain slight pressure on the articles in the reservoir so as to confine the articles and prevent the occurrence of voids. Articles are withdrawn from the outlet  86  of the reservoir by the bands  88  and  90 . A stream of articles delivered by the bands  88 ,  90  may be conveyed to further processing apparatus. For example, where the articles are cigarettes, the further processing apparatus may be a cigarette packing machine; where the articles are filter rods, the apparatus may be a distributor for pneumatically conveying the filter rods to a filter cigarette assembling machine. 
   The bands  70 ,  74  and  78  are controlled separately. The bands  70  run at the same speed as each other, as do the bands  74 ,  78  and  88 ,  90  respectively. In various operative conditions the speeds of the bands  70 ,  74  and  88  depend on the level of fill (volume) of the reservoir  76  and on the status of upper and lower article level detectors  92 ,  94  located respectively at and adjacent the unloading position  10 A. Each of the detectors  92 ,  94  may comprise opto-electronic means which senses the presence of adjacent articles, eg by sensing interruption of a beam of radiation: such means are well known in the cigarette industry. The upper detector  92  is positioned immediately above the channel  72  at a height corresponding to a level reached by the articles when a tray at unloading position  10 A is about 80% unloaded. The lower detector  94  is positioned at the upper end of the channel  72  just below the level of the bands  70 . 
   While the majority of the contents of a tray at the unloading position  10 A are being delivered to the conveyor system  12  the detector  92  is covered, ie detects articles. In this situation, the bands  70  are run at a speed which bears a fixed relationship to the speed for the time being of the band  74 . A preferred ratio is that the bands  70  have a speed which is set at about 55% of the speed of the band  74 . If the reservoir or volume value is less than a predetermined high value (eg corresponding to 85% of maximum capacity) the band  74  is run at a fixed high speed so as to unload the tray rapidly. With filter rods, for example, this speed may be as high as that corresponding to a flow rate of 48,000 rods per minute (with a stream height on conveyor  74  of about 120 mm and rod diameters of about 8 mm). If the reservoir volume value exceeds the predetermined value the speed of band  74  is reduced to approximately that of band  88  (which is itself typically determined by downstream apparatus). In this condition the speed of band  74  may be progressively controlled according to reservoir capacity. For example, between 85% and 95% reservoir capacity the speed of the band  74  may be progressively reduced, eg from a value corresponding to 5% in excess of the speed of band  88  to a value corresponding to 5% less than that of the band  88 . If the reservoir volume value exceeds 95% capacity the band  74  will be stopped. During all of this time (while the detector  92  detects articles), the speed of bands  70  is 55% of that of the band  74  for the time being. 
   As soon as detector  92  is uncovered, indicating that the tray at unloading position  10 A has typically unloaded 80% of its contents, the speed of band  74  is fixed (eg at a rate corresponding to 12,000 rods per minute for filter rods as mentioned hereinbefore). In this condition, ie with detector  92  uncovered, bands  70  run slightly faster than band  74 , eg at 105% of the speed of band  74 . Once this final stage of unloading of a tray at the unloading position  10 A has started, bands  70  and  74  run at these speeds until detector  94  is uncovered, irrespective of the capacity of reservoir  76 . When detector  94  is uncovered the band  74  is stopped and the bands  70  run for a predetermined short additional time (eg 0.5 seconds) before stopping also. 
   In a preferred mode of operation the speed of band  74  is controlled according to the angular position (θ,  FIG. 5 ) of the pivoted plate  82 . Thus, where θ is in the following ranges the speed of band  74  is as indicated: 
   0°-17° Stopped; 
   18°-69° High speed (eg corresponding to 48,000 cpm); 
   70°-79° Controlled speed based on speed of band  88  (eg progressively reducing from above to below speed of band  88 ); 
   80°-90° Stopped (unless detector  92  is uncovered); Low speed (eg corresponding to 12,000 cpm) if detector  92  is uncovered and detector  94  covered; 
   90° Stopped—reservoir  76  is in a jam condition (fault). 
   Under normal running conditions the reservoir  76  is never allowed to fill such that the angle θ exceeds 80°. This provides enough remaining capacity (with θ between 80° and 90°) that if the downstream demand for articles stops just as detector  92  is uncovered (so that band  88  is stopped) there is enough remaining room in the reservoir  76  to accept all remaining articles unloaded from a tray  10  in the unloading position  10 A in a controlled manner. 
   After a tray has been completely unloaded the empty tray is removed and a new full tray moved into position  10 A as hereinbefore described. On retraction of the release plate  40 , articles in the new full tray have a minimum distance to fall (eg a few millimeters maximum) onto the bands  70  and the articles at the top of the channel  72 . During the tray change the bands  70  and  74  remain stationary so that the level of articles in the channel  72  remains approximately the same as that of the bands  70 .