Abstract:
A device for filling and compacting pourable products is proposed, comprising: —at least one product feed ( 16 ) for feeding a pourable product to a container ( 12 ) that is to be filled, —at least one ram ( 14 ) for compacting the product supplied to the container ( 10 ), characterized by means for applying a predetermined force to the ram ( 14 ) and for detecting the force acting on the ram.

Description:
This patent application is a U.S. National Phase of International Patent Application No. PCT/EP09/64493, filed 3 Nov., 2009, which claims priority to German Patent Application No. 10 2008 054 922.3, filed 18 Dec., 2008, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     The invention proceeds from a device for filling and compacting pourable products. DE 10 2006 010 092 A1 has already made known a device for filling with a fine-grained product. In this case a metering device, a guiding device for supplying the product from the metering device into a packaging unit and a suction device for sucking in swirled up, fine-grained product are provided with a suction housing, the guiding device being guided through the suction housing and the guiding device and the suction housing being located above the packaging unit. 
     SUMMARY OF THE INVENTION 
     The object underlying the invention is to improve the filling operation further. 
     The advantage of the device as claimed in the invention for filling and compacting pourable products in contrast is that the filling operation is improved further by providing a force-regulated filling and compacting of pourable products. In particular in the case of certain products such as, for example, coffee powder, force-controlled pressing is particularly advantageous in order to obtain a certain taste. In addition, the device is distinguished by a particularly space-saving arrangement, as it is possible to effect filling and pressing in just one operating station. 
     In an expedient further development, it is provided that a linear drive and/or a pneumatic cylinder are/is provided as means for applying a force to the plunger. The former is distinguished by simple controllability. For applying a pressing force, it is additionally possible for an application of force by the linear drive to overlie the pneumatic cylinder. This means, in particular, that small linear drives can be used which then take over the force-controlled or force-regulated impingement of the plunger. A minimum contact force is preferably applied to the plunger by means of the pneumatic cylinder. 
     In an expedient further development, it is provided that the linear drive acts on the plunger by way of a lever mechanism. This arrangement is distinguished, on the one hand, by a particularly small installation space requirement. In addition, a corresponding leverage allows for the use of relatively small linear motors for controlling or regulating the force of the contact force of the plunger. 
     In an expedient further development, detecting means are provided for detecting the force acting on the plunger. Load cells are particularly suitable for this on account of their sturdy design. The measuring data of the detecting means can be used for controlling the required value of the linear motor. This means that the achieving of the pre-selected pressing force is ensured in a particularly simple manner. 
     In an expedient further development, the detecting means is located directly above the plunger. This means that friction losses in the guides and lever mechanisms located above the detecting means are not important. This means that the products of the force-controlling or force-regulating process are improved further. 
     In an expedient further development, it is provided that stripping means are provided that prevent the product to be compacted from sticking to the underside of the plunger. Mechanisms that force the plunger to move rotationally about the longitudinal axis, or also ultrasound devices that can cause the plunger to vibrate, are particularly suitable in this case. This means that the sticking of the product to be filled is avoided, thereby presenting a constantly high quality of the force-controlled pressing or compacting of the product. 
     In an expedient further development, it is provided that at least two plungers are located so as to be displaceable together with the means for applying a force, in relation to a filling unit, above which the product to be filled is supplied to the receptacle to be filled. This means that it can be achieved in a particularly preferred manner that a plurality of plungers can also be moved to compact the filled product by way of only one movement mechanism, whilst, on the other hand, it can be ensured that each plunger can be displaced individually in a force-regulated or force-controlled manner. This contributes additionally to the minimizing of the space required for the overall arrangement with constantly high filling quality on account of the plungers that can be separately force-controlled or force-regulated. 
     Additional expedient further developments are produced from the description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the device according to the invention for filling and compacting pourable products is represented in the drawing and is described below in more detail, in which: 
         FIG. 1  shows a partial longitudinal sectional view of the device and 
         FIG. 2  shows a schematic view of a displaceable plunger unit. 
     
    
    
     DETAILED DESCRIPTION 
     As an example, two receptacles  12  are filled in this case with a pourable product via a fill block  10 . The pourable product passes into the receptacle  12  via a product feed  16 , which is located in an inclined manner opposite a longitudinal axis of a plunger  14 . Between the mouth of the product feed  16  and of the receptacle  12  there is located an opening of an ejector  44  that is preferably realized as an annular suction means in order to minimize possible product losses. A plunger unit  28  is located so as to be moveable in relation to the fill block  10 , which is what the double arrow at the side is to represent. To this end, the displaceable plunger unit  28  includes a plurality of guide bushes  52  which ensure a displaceability of the plunger unit  28  in relation to fixed guide rods  50 . The plunger unit  28  includes at its bottom end, shown as an example, two plungers  14  that are each connected to a pressure detecting means  42  via corresponding sleeves  43 . Plunger  14 , sleeve  43  and load cell  42  are rotatably mounted via a bearing arrangement  41  and can be rotated about the central axis of the plunger by a rotating device  40  located within the bearing region. An output signal of the pressure detecting means  42  is supplied to a drive device  26 , which in turn generates a drive signal for a linear motor  30 . The linear motor  30  is a structural component of the plunger unit  28 . A movement of the linear motor  30  acts on a lever arm  31  that is rotatably mounted by means of a bearing point  34  of a bearing block  33 . A corresponding movement of the linear drive  30 , where applicable amplified by a pneumatic cylinder  32  also acting on the lever arm  31 , pushes in a pressure rod  36  that is arranged coaxially to the plunger  14 . The movement of the pressure rod  36  and consequently of the plunger  14  is defined by a stop member  35 . A guide  38  transmits the movement of the pressure rod  36  to the plunger  14 . 
     The displaceability of the plunger unit  28  in relation to the fill block  10  is achieved in that parallel to the direction of displacement of the plungers  14 , guide rods  50  are connected to a machine frame  54 . The fill block  10  also rests on the machine frame  54 . The guide rods  50  can be interconnected at the top via a frame on which a motor  56  rests. The latter activates a spindle  58 , via which the plunger unit  28  with associated plungers  14  can be displaced along the guide rods  50 , mounted in the guide bushes  52 . 
     High-quality products demand force-controlled pressing to obtain, for example in the case of coffee powder, a certain taste. In order to achieve as high an output as possible in the case of corresponding filling systems, it is necessary to construct in a small space. A cost-efficient way in which to produce receptacles  12  is the thermoforming of plastic films. To generate as little waste as possible, attempts are also made with these systems to arrange the receptacles  12  as close to each other as possible. The device for filling and compacting pourable products can be used, for example, on a thermoforming machine in order to achieve, once the receptacle  12  has been filled, in the smallest space a force-controlled or force-regulated pressing of the product in one station or in one single operation. 
     To this end, the receptacle  12  is raised to the mouth of the fill block  10 . The product is metered into the receptacle  12  through the product feed  16 , which is realized as a bore. The metering amount, in this case, can exceed the receptacle volume as the receptacle  12  abuts closely against the mouth of the fill block  10 . Once the metering has been completed, the plunger  14  is moved downward to compress the product located in the receptacle  12 . 
     During or after the pressing operation, the plunger  14  is rotated by means of the rotating device  40  to avoid the product sticking to the plunger  14 . The rotating device  40  is preferably designed as a rack and pinion drive. It would also be possible to use other techniques for this, for example causing the plunger  14  to vibrate. This could be effected by means of ultrasound. 
     In order to move the plunger  14  in relation to the receptacle  12  for pressing, the entire plunger unit  28  is displaced in relation to the fixed fill block  10 . To this end, the plunger unit  28  is displaced by the motor  56  downward or upward along the guide rods  50  via the spindle  58 . The plunger unit  28  is mounted by means of guide bushes  52  in relation to the guide rods  50 . The guide rods  52  can be components of the machine frame  54 . 
     The plunger  14  is guided in the plunger unit  28  itself in an axially torque-secured manner. This task is taken over by the guide  38  that is preferably realized as a torque bushing. This ensures that the rotation of the plunger  14  does not go further upwards beyond the guide  38 . 
     The actual pressing force is introduced by the lever  31  which has its fulcrum  34  in the bearing block  33 . To this end, a linear motor  30  and a pneumatic cylinder  32  press on the lever  31 , which exerts a force via a roller onto a pressure rod  36  and the guide  38 . The stop member  35  prevents a more extensive movement. If the plunger  14  then contacts the product, presses it and exceeds the force preselected in the linear motor  30 , the plunger  14  quasi spring deflects in its guide. At the same time the linear motor  30  regulates the force presented and consequently ensures the selected pressing force. In order to generate a relatively high pressing force, on the one hand the lever arm  31  is used. In addition, the pneumatic cylinder  32  also supports the application of a force. By selecting a corresponding pressure beforehand and through corresponding leverage, relatively small linear motors  30  can also be used. Types of drive other than linear motors  30  are also suitable for this. They just have to displace the lever arm  31  such that the desired pressing force is presented to the plunger  14 . 
     The pressure detecting means  42  is used to monitor the pressing force. Said means detects the pressing force applied to the plunger  14  and provides a corresponding output signal to the drive device  26 . Measuring data of the pressure detecting means  42  can be used to control the required value of the linear motor  30 . This means that achieving the preselected pressing force is ensured. A pressure force sensor  42  that is designed, for example, as a load cell is preferably used as pressure detecting means. The direct arrangement above the plunger  14  means that friction losses in the guides  38  and in corresponding force transmission mechanisms  31 ,  33 ,  34 ,  36  are not important. The measuring results are, consequently, not falsified. 
     Possible product losses through gaps between receptacle  12  and mouth of the product feed  16  are sucked out through an annular suction of the ejector  44 . 
     The plunger unit  28  includes in a particularly preferred manner at least two plungers  14 . For the pressing process, the at least two plungers  14  can be displaced by just one movement device  56 ,  58 . On the other hand, it is ensured that a separate drive device  30  for controlling the pressing force or for regulating the pressing force is associated with each plunger  14 . Consequently, it is possible to adapt the pressing force of each plunger  14  individually. Over and above this, to obtain a particularly space-saving design of the plunger unit  28 , the respective lever arms  31  for the respective plungers  14  are located one behind another and interlock.