Abstract:
An air conveyor for transporting plastic bottles, in which bottles are driven by applying air, in the area of the bottle openings. In a partial area of the air conveyor, means are provided to apply air to the bottle bodies. These means are arranged such that the bottles are essentially oriented vertically with the openings of the bottles facing upwards and the bottom of the bottles facing downwards.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of priority of German Patent Application No. 102007048545.1 filed Oct. 9, 2007. The entire text of the priority application is incorporated herein by reference in its entirety. 
     FIELD OF THE DISCLOSURE 
     The disclosure relates to an air conveyor for transporting plastic bottles by applying air to the opening area of the bottles geared to a method of transporting plastic bottles with an air conveyor. 
     BACKGROUND 
     Air conveyors are frequently used for transporting plastic bottles in industrial plants. In such plants, the bottles are in most cases suspended with their supporting rings in guide rails and are moved forward by means of air. As no complex mechanism is required for this type of progressive movement, such a plant is less susceptible to failures. 
     In a known air conveyor of the applicant, the application of air is effected in the area of the bottle openings, whereby the driving force mainly acts on the bottle openings. With this method, more than 30,000 bottles per hour can be transported in an air conveyor, and the transport speeds are correspondingly high. 
     However, as speed is increasing, aerodynamic drag also plays an increasing role. As aerodynamic drag is highest in the area of the largest surfaces of action of the bottles and as only at the bottle openings air is applied to the bottles, the bottles have a very oblique position. This oblique position of the bottles does not have any negative effect when the bottles are being transported. However, when a bottle is to be transferred to another transport device (e.g. a sawtooth or zigzag star) at the end of an air conveyor, the oblique position of the bottles can cause difficulties. 
     SUMMARY OF THE DISCLOSURE 
     Therefore, the object underlying the present disclosure is to render the bottle transfer to another conveyor in the end area of an air conveyor essentially less susceptible to failures without slowing down the bottles in the process. 
     Bottles usually comprise a more or less pronounced supporting ring in the opening area which is required for manipulation purposes in the production and/or in the further treatment in subsequent plants. The air conveyor for transporting plastic bottles moves the bottles by applying air to the bottle openings, the bottles to be transported hanging with their supporting ring at a rail. During transport, the bottles are in an oblique position. To orient the bottles in the end area of the air conveyor as vertically as possible, in a partial area, preferably at the end of the air conveyor, means are provided to apply air to the bottle bodies. These means are arranged such that the bottles are essentially oriented vertically, i.e. the openings of the bottles face upwards and the bottoms of the bottles face downwards. 
     The application of air to the bottle bodies is performed such that the oblique position of the bottles decreases and the bottles are oriented as vertically as possible. The deviation of the thus oriented bottles from the vertical is less than 10° and preferably less than 5°. 
     When air is being applied to the bottle bodies, the air is preferably blown against the bottle bodies from the side or diagonally from the side. However, embodiments of the disclosure are possible, where air is blown against the bottle bodies from behind, from the bottom or diagonally from the bottom. Possible airflow angles to the direction of movement or transport of the bottles can be of any values from 0° to 90°. 
     To apply air to the bottle bodies, guide plates are typically used which are provided with gills or nozzles. Gills are slits worked into a guide plate through which air flows out in a preferred direction. Guide plates with nozzles are more complicated to manufacture, but permit a very precise airflow. Embodiments with combinations of gills and nozzles are also conceivable. The gills or nozzles can be located at different levels at the guide plates. For example, the gills or nozzles can be arranged in diagonal rows on the guide plates, preferred angles to the longitudinal sides of the guide plates being in a range of 20° to 40°. The arrangement of the gills or nozzles at different levels or the diagonal arrangement of the gills or nozzles permits to transport and vertically orient bottles of different sizes and different oblique positions in one and the same air conveyor. In case of bottles with a lower or higher own weight, the blowing strength can be correspondingly decreased or increased. 
     For the air supply, usually blower fans, compressors or an external air supply are employed. The air supply to the bottle bodies is either the same air supply as for the bottle openings, or a separate air supply is used for applying air to the bottle bodies. 
     Furthermore, the air conveyor can comprise means for applying air to the bottle bodies, namely one or several detectors for detecting the oblique position of individual bottles, and a control of the air supply which can take into consideration the detected oblique position of the bottles. In this manner, bottles with a more oblique position can be blown at with a stronger flow than bottles with a less oblique position, so that, if possible, in the end area of the air conveyor all bottles are oriented vertically as precisely as possible after air has been applied to the bottle bodies. 
     Furthermore, the air conveyor can typically comprise one or several hooks in the end area by which arriving bottles can be abruptly slowed down or stopped. This procedure can become necessary if the bottle transport in the air conveyor has to be quickly interrupted. 
     The method of transporting plastic bottles with an air conveyor comprises applying air in the area of the bottle openings to drive the bottles. Additionally, in a partial area, for example at the end of the air conveyor, air is applied to the bottle bodies to orient the bottles towards the vertical. 
     When the bottles are being oriented, a completely vertical orientation is typically strived for, where deviations from the vertical should be less than 5°. 
     To orient the bottles vertically, air can be blown against the bottle bodies at an angle between the airflow direction and the transport direction of the bottles in a range of 0° to 90°. When the bottles are being oriented vertically, the speed of the bottles is not decreased (as, in addition to the total movement of the bottle, the bottle body moves forward, i.e. in the direction of movement of the bottle). 
     In a further embodiment of the disclosure, the method of transporting plastic bottles with an air conveyor comprises additional steps. To be able to orient the bottles in the end area of the air conveyor more precisely vertically, the oblique position of individual bottles is first detected, and then this information is used to adjust the application procedure in the end area of the air conveyor, so that the airflow against bottles with a more oblique position is stronger than against bottles with a less oblique position. This leads to bottles with different oblique positions being oriented as uniformly or as precisely vertically as possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further aspects of possible embodiments of the disclosure will become clear with reference to the Figures. In the drawings: 
         FIG. 1   a  shows a schematic view of a bottle in an air conveyor which is in an extremely oblique position; 
         FIG. 1   b  shows a schematic view of a bottle in an air conveyor which is in a less oblique position than the bottle in  FIG. 1   a;    
         FIG. 1   c  shows a schematic view of a bottle in an air conveyor which is oriented vertically; 
         FIG. 1   d  shows a schematic view of a bottle as transferred by an air conveyor to a further unit, such as a sawtooth or zigzag star. 
         FIG. 2  shows a schematic view of an air conveyor with guide plates; 
         FIG. 3   a  shows a schematic side view of a bottle in an air conveyor which is held with a hook; 
         FIG. 3   b  shows a schematic plan view of a bottle in an air conveyor which is held by a hook; and 
         FIG. 4  shows a process sequence for orienting bottles as vertically as possible. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates the vertical orientation of a bottle  101  in an air conveyor. The air conveyor comprises, among others, two guide rails  103  situated at the same level at opposite sides, in  FIG. 1  only one of them being shown. The guide rails  103  are arranged in pairs in parallel to each other. The distance between two guide rails  103  is selected such that the neck of a bottle just fits between the two guide rails  103  and the bottle  101  rests with the supporting ring of the bottle on the two guide rails  103 . In the indicated air conveyor, air is applied to the bottle opening  102 , so that the bottle  101  slides on the guide rails  103 . The total direction of movement of the bottle  101  is indicated by an arrow. In  FIG. 1   a , the bottle  101  is in an extreme oblique position as only in the area of the bottle opening  102 , air is applied to the bottle  101 , and as the aerodynamic drag caused by the progressive movement mainly acts on the bottle body. 
     In  FIG. 1   b , air is additionally applied to the bottle body  104  (wavy arrows), so that the bottle  101  starts to orient vertically. In  FIG. 1   c , the completely vertically oriented bottle  101  can be seen. The additional admission of air to the bottle body  104  permits to increase the capacity of an air conveyor in an exemplary embodiment from 30,000 bottles per hour up to 120,000 bottles per hour. 
       FIG. 2  shows a part of an air conveyor according to a possible embodiment of the disclosure. The main direction of movement of the bottles is indicated by an arrow. Two guide plates  201  are arranged in parallel to each other, both guide plates  201  being equipped with gills or nozzles  202  which are supplied with air by one or several air supplies  203 . The gills or nozzles  202  can be arranged, for example, in one or several rows on a guide plate  201 . Preferably, these rows extend diagonally, so that the gills or nozzles  202  are located at different levels at the guide plate  201 . 
     Optionally, one or several detectors  204  are attached to one or both guide plates  201  and can detect the oblique position of individual bottles  101 . The output signals of the detectors  204  can be forwarded to a control (not shown) and then be used to improve the vertical orientation of individual bottles  101  in that the control instructs, for example, the air supply to supply more or less air, corresponding to the oblique position of individual bottles  101 . It is also possible to actuate valves (e.g. solenoid valves) to control the airflow, so that individual bottles  101  can be oriented vertically by a directed airflow. The detectors  204  can be located at various points of a guide plate  201  or, depending on the construction, in front of or behind a guide plate  201 . The detector position is, for example, further in the front to first be able to detect the oblique position of a bottle and further in the back to be able to check, after air has been additionally applied to the bottle body  104 , whether the bottle  101  is oriented sufficiently vertically. 
     Another possible aspect of the disclosure is drawn in  FIG. 3 . To be able to stop bottles  101  as quickly as possible, a hook  301  grips at the neck of the bottle near the bottle opening  102 , so that a further movement of the bottle  101  (in this case from left to right) is prevented.  FIGS. 3   a  and  3   b  show the same scenario, in one case from the side and in the other case from above. 
     To prevent, in the end area of a bottle conveyor, quickly arriving bottles  101  from rising upwards (or from no longer resting on the guide rails  103 ), a hold-down disk  105  can be used which is located just above the bottle openings  102 . This can prevent bottles  101  from wedging or being damaged during the transfer to further units, such as e.g. a sawtooth or zigzag star  106 . 
       FIG. 4  shows an exemplary process sequence for orienting bottles vertically. In step  401 , first the oblique position of a bottle is detected to get an indication of how strong the airflow against the bottle has to be. This information is used in step  402  to control or adjust the airflow for blowing against bottles. In step  403 , air is applied to the bottle body, the oblique position of the bottle being taken into consideration by adjusting the airflow. If there are several detectors, there is the possibility of passing this cycle several times and of taking into consideration the current oblique position of a bottle in each case. Furthermore, there is the possibility of taking into consideration a residual oblique position of the bottles oriented in the direction of the vertical to be able to orient subsequent bottles even more precisely.