Abstract:
A chamber conveyor belt machine having a machine frame, a chamber cover with two or more columns and a lifting device for lifting the chamber cover. The lifting device may include a safety system that includes a latching rail that cooperates with a latching hook disposed on at least one of the two columns. The safety system may include one or more sensors for determining whether the lifting device is working correctly or is in a failure condition. The safety system may prevent the chamber conveyor belt machine from operating if a failure condition is sensed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to European Patent Application Number 16168027.7 filed May 3, 2016, to Maximilian Brunner, Rainer Häring, and Konrad Mössnang, currently pending, the entire disclosure of which is incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a packaging machine in the form of a chamber conveyor belt machine. 
       BACKGROUND OF THE INVENTION 
       [0003]    The German patent no. DE 102010013889 A1 shows a chamber conveyor belt machine having a unit for vertically moving a chamber cover. In this machine, the chamber cover is arranged at four columns, which are synchronously moved by means of a motor drive and a fluid cylinder as a supporting tool. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the invention to constructively simplify a chamber conveyor belt machine regarding the movement of the chamber cover. 
         [0005]    The chamber conveyor belt machine of the invention comprises a machine frame, a chamber cover with two columns, and a lifting device, wherein a safety system may be provided for the lifting device. The conveyor belt machine according to the invention is characterized in that the safety system may comprises a latching rail cooperating with a latching hook at one column in order to secure the chamber cover in a lifted position against lowering or falling down in the event that the lifting device shows a malfunction, for example, due to the fact that a failure of the pressurized air supply of the pneumatic cylinder for lifting the chamber cover, an inner leakage in the pneumatic cylinder, or a leakage in the supply lines may be provided. In this case, nevertheless, a secure hold of the chamber cover may be provided and any danger to the operating personnel is prevented. 
         [0006]    In a preferred embodiment, the latching rail may comprise a plurality of latching teeth, in order to generate a self-reinforcing holding effect of the chamber cover together with the latching hook of the column. 
         [0007]    Preferably, the latching rail at its first end may be arranged so as to be pivotable on the machine frame, and at its second end, an actuator may be provided in order to pivot the latching rail about the first end and to guide the latching rail to the column or the latching hook so that the latching hook engages one of the latching teeth and a lowering of the chamber cover is prevented. 
         [0008]    The actuator may be a pneumatic cylinder or a motorized linear drive in order to enable a simple performance of the construction. 
         [0009]    The safety system may have at least one first sensor in order to screen the holding position, in which the latching hook engages the latching rail in order to ensure the highest security against the risk of an unintentionally or unexpectedly lowering of the chamber cover. 
         [0010]    Thereby, the sensor preferably verifies the position of the latching rail or may alternatively be arranged on the actuator in order, for example, to check the position of a cylinder piston or a linear carriage. 
         [0011]    In a preferred embodiment, a second sensor may be provided in order to also verify the open position of the latching rail. Thus, the function of a positively-driven resetting from an open position into the holding position can also be checked, since both positions can be detected via the two sensors. 
         [0012]    The safety system preferably has a spring in order to move the latching rail into the holding position so that an automatic resetting of the latching rail into the holding position is provided in a constructively preferred manner. 
         [0013]    The spring may be preferably a resetting spring within a pneumatic cylinder. 
         [0014]    A method according to the invention for operating a chamber conveyor belt machine as described above is characterized in that a functional test may be carried out before a machine start, wherein the chamber cover is extended into its uppermost position, the safety system is in the open position, and wherein the first sensor verifies the open position. Thus, in conjunction with valves, pressure switches, and unlockable throttling back valves, for example, a performance level “d” according to technical standard EN ISO 13849-1 can be achieved. 
         [0015]    Thereby, in one embodiment, the first sensor preferably screens the position of the pneumatic cylinder by means of the piston position in order to determine the position of the latching rail. 
         [0016]    In the event of a failure, the chamber conveyor belt machine may preferably indicates an error message by means of a control system and the chamber belt machine does not enter into an operation mode, since the safety is no longer ensured. The failure has to be remedied before the chamber conveyor belt machine can be further operated. 
         [0017]    Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
     
    
     
       DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0018]    In the following, an advantageous embodiment of the present invention will be explained in more detail making reference to the following drawings, in which the individual figures show: 
           [0019]      FIG. 1  is a perspective view of one embodiment of a chamber conveyor belt machine in accordance with the teachings of the present invention; 
           [0020]      FIG. 2  is a schematic rear view of one embodiment of a chamber conveyor belt machine in accordance with the present invention with a safety system in the holding position; and 
           [0021]      FIG. 3  is a schematic rear view of one embodiment of a chamber conveyor belt machine in accordance with the present invention with a safety system in the open position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures. 
         [0023]    The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
         [0024]      FIG. 1  shows a schematic view of a chamber conveyor belt machine  1  according to the invention comprising a conveyor belt  2 , a machine frame  3 , a loading area  4 , and an evacuating and sealing device  5 . The evacuating and sealing device  5  has a vertically movable chamber cover  6 , which together with a lower part  7  forms a chamber that can be evacuated. The chamber cover  6  can be automatically closed and opened by means of a power-driven mechanism in order, for example, to collect bags  9  to be evacuated and sealed, which are automatically fed to the evacuating and sealing device  5  by the motor-driven conveyor belt in a production direction P. The bag  9  with its product is evacuated in the chamber and subsequently air-tightly sealed in the region of its bag opening so that a vacuum pack  90  is produced. 
         [0025]    The chamber conveyor belt machine  1  comprises a lifting device  11 , wherein the chamber cover  6  can be lifted and lowered vertically via two columns  10  by means of one pneumatic cylinder  12 , respectively. Via a control  100 , which is arranged in the loading area  4 , an operator can carry out settings and the machine start and receives display status reports, for example error messages. 
         [0026]      FIG. 2  shows a schematic rear view of the chamber conveyor belt machine  1  comprising a safety system  13  for the lifting device  11  in the holding position. The two columns  10  are guided via guides  14 , which are connected to the machine frame, and are each movable via a pneumatic cylinder  12 . The pneumatic cylinder  12  is connected to a lower end of the movable column  10  via a bar  15 . The pneumatic cylinders  12  themselves are supplied via at least one compressed air line  16 . In the event that, for example, a leakage occurs along the compressed air line  16 , a leakage in the interior of the pneumatic cylinder  12 , or a failure of the compressed air supply for the pneumatic cylinders  12 , a safety system  13  is provided in order to prevent the chamber cover  6  from being lowered unexpectedly for the machine operator. The safety system  13  comprises a latching rail  18 , which is rotatably or pivotably mounted via a support  19  to the machine frame  3  and cooperates with a latching hook  20 , which is mounted on the right-hand column  10  in the lower area shown in  FIG. 2 . 
         [0027]    On its side facing the column  10 , the latching rail  18  has a plurality of latching teeth  21 , between which the latching hook  20  can immerse, if the latching rail  18  is in its holding position, as shown in  FIG. 2 . The shape of the latching teeth  21  and the latching hook  20  is designed such that when brought into contact with one another, the weight of the chamber cover  6  even reinforces a latching of the latching hook  20  with the latching teeth  21 . 
         [0028]    The pivoting movement of the latching rail  18  occurs, for example, by means of an actuator  22 , shown here as a pneumatic adjust cylinder  22 , which on the one hand is connected to a lower end of the latching rail  18 , and on the other hand to the machine frame  3  via a further support  23 . A pressure spring  24 , which is supported on the machine frame  3  and pivots the latching rail  18  into the holding position so that the latching teeth approach the latching hook  20  and also come into contact, ensures a forced movement of the latching rail into the holding position, even in the event of a failure of the adjust cylinder  22 . Instead of the pressure spring  24 , also a spring-resetting pneumatic cylinder is conceivable as an actuator  22 . 
         [0029]      FIG. 3  shows a schematic rear view similar to  FIG. 2  of the chamber conveyor belt machine  1  with the safety system  13  in the open position, in which the latching rail  18  has been moved counterclockwise away from the latching hook  20 . This pivoting movement is effected by the actuator  22  in the direction of the arrow. Thereby, the illustrated pressure spring  24  or the resetting spring, which is not shown in more detail, is compressed and tensioned in the interior of the actuator  22  or of the pneumatic adjust cylinder. In this open position, namely the cleaning position, the chamber cover  6  can be moved by means of the lifting device  11  at least into an upper charging position or into a lower evacuating and sealing position, namely the working position. 
         [0030]    The operation of the chamber conveyor belt machine  1  provides a functional test of the safety system  13  and, in particular, of the pressure spring  24  before each start, after each switching on of the chamber conveyor belt machine  1  or in cyclic sections. The chamber cover  6  is lifted to its uppermost position via the control  100 , while the safety system  13  is in the open position. Subsequently, the safety system  13  is brought into the holding position. In order to be able to monitor one or both positions, a first sensor  25  is provided, which detects the open position. Optionally, a second sensor  26  can also be provided in order to also detect the holding position. Thus, both positions and also the change between both positions can be reliably detected by the control  100 . In an alternative embodiment, two sensors  25 ,  26  can also be arranged on the actuator  22  in order to detect both positions at the actuator  22 . 
         [0031]    If the control  100  determines an error in this function test or also during the operation of the chamber conveyor belt machine  1 , the chamber conveyor belt machine  1  is stopped and a corresponding message is issued, by means of which the machine operator can carry out an elimination of the problem. 
         [0032]    From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
         [0033]    The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.