Abstract:
A sealing jaw for sealing a packaging material using ultrasound is provided. Said sealing jaw comprises energy directing means ( 28 ) which, for sealing purposes, can be brought in contact with an opposite surface ( 26 ) via the packaging material and which have a substantially grid-shaped or rhomboidal sealing profile ( 36 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention proceeds from a sealing jaw for sealing a packaging material using. Such a generic apparatus is known, for example, from US 2004/0011452 A1. This describes a transverse sealing device for bar packaging which consists of a rotating sonotrode and a rotating anvil. 
     SUMMARY OF THE INVENTION 
     The object underlying the invention is to provide a sealing jaw which improves the sealing quality. 
     In contrast, the advantage of the sealing jaw for sealing a packaging material using ultrasound is that, on account of the sealing profile selected, a lengthening of the contact time between the sealing tools is achieved, as a result of which the sealing quality is improved. The sealing jaw for sealing a packaging material using ultrasound includes energy directing means which can be moved into contact with a counter surface by means of the packaging material. The energy directing means have a substantially grid-shaped or rhomboidal sealing profile. 
     In an expedient further development, it is provided that the energy directing means are provided with a radius. As a result, the packaging material is protected. In addition, a high seal seam strength and tightness is able to be achieved. 
     In an expedient further development, it is provided that the side faces are inclined at an angle in relation to the surface of the sealing profile. As a result, in conjunction with the rounded design of the energy directing means, the fused mass is able to be optimized. 
     In an expedient further development, it is provided that the side faces merge rounded-off into the base faces. This contributes to a sealing process which protects the packaging material and counteracts any possible adhesion of product residue. 
     In an expedient further development, it is provided that the grid-shaped or rhomboidal sealing profile consists of several rectangles of substantially identical size. This achieves a particularly uniform force application, as a result of which a sealing seam with a constant high strength is achieved. 
     In an expedient further development, it is provided that in that the rectangles are arranged in such a manner with regard to a side edge of the sealing jaw that a zigzag-shaped development of the energy directing means is produced. In particular, this allows the contact area to be enlarged, as a result of which the energy input for the sealing is improved. 
     In an expedient further development, it is provided that that the rectangles are arranged such that a base face of the rectangles is arranged at an angle that differs from zero, preferably 45°, in relation to the side edge of the sealing jaw. This produces a substantially parallel development of the zigzag-shaped energy directing means parallel to the side edge such that a tight seal is produced. 
     In an expedient further development, it is provided that that the length of the diagonals of the rectangles is selected such that twice the length of the diagonals of the rectangles is less than or equal to a width of the sealing profile. As a result, a high degree of tightness is achieved as the transverse seam sealing is always obtained by two rectangles. 
     In an expedient further development, it is provided that the sealing profile has two part regions which are separated from each other by a gap. A cutting blade can be incorporated in said gap, whilst the two other part regions of the transverse seam sealing serve for two pouch packages which are to be separated from each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the apparatus for processing a packaging material using ultrasound are shown in the drawing and are described below, in which, in detail: 
         FIG. 1  shows a perspective front view of the apparatus for processing a packaging material, 
         FIG. 2  shows the top view on a sealing profile of the anvil, 
         FIG. 3  shows a sectioned representation of the sealing profile according to  FIG. 2 , 
         FIG. 4  shows a view of a detail of the sealing profile according to  FIG. 2 , 
         FIG. 5  shows a sectioned representation of a view of a detail of an energy directing means according to  FIG. 2 , 
         FIG. 6  shows a perspective representation of a first sealing profile, 
         FIG. 7  shows an enlarged view of a detail of the representation according to  FIG. 6  and 
         FIG. 8  shows a top view of a second sealing profile with flatter side walls. 
     
    
    
     DETAILED DESCRIPTION 
     In the case of the apparatus according to  FIG. 1 , a sonotrode  10  is guided rotatably mounted at both ends in each case by an end shield  14 . The two end shields  14  for the sonotrode  10  are connected together in a lateral manner at the top end of the apparatus  8  by an upper support means  22 , in this case, as an example, realized as a support bar. An anvil  12 , which is equally rotatingly mounted, interacts with the sonotrode  10 . The anvil  12  is mounted in two end shields  16 . The end shield  14  of the sonotrode  10  is connected to the end shield  16  of the anvil  12 , arranged in each case below said end shield of the sonotrode, by a coupling means  20 . The two end shields  16  of the anvil  12 , in their turn, are connected together in a lateral manner by way of a lower support means  24 , which is realized, as an example, as a support tube. Force means  18  are arranged in each case on the opposite side of the coupling means  20  with reference to the rotational axes of the sonotrode  10  or the anvil  12 , by means of which force means the necessary sealing force can be applied to the sealing face of the sonotrode  10  and of the anvil  12 . Adjusting means  30  are provided in each case above the force means  18 . As a result the sealing force or sealing gap can be adjusted. 
     The sonotrode  10  and the anvil  12  have in each case four sealing faces  24 ,  26 . The sealing face  26  of the sonotrode  10  has a smooth, plane surface. The sealing face  24  of the anvil  10  is described in more detail by way of the following figures. According to  FIG. 2 , the rectangular sealing face  24  of the anvil  10  consists of two rectangular part faces  31  which are separated from each other by an elongated gap  30 . The two part faces  31  are in each case provided with special sealing profiles  36 . The sealing profiles  36  are essentially realized in the shape of a rectangle or a rhomboid. The base sides of the individual rectangles  38  forming the rectangular sealing profile  36  are aligned inclined at approximately 45° in relation to the side edge  35 , as a result of which a lengthening of the length of the seal is achieved. 
     In the case of the sectional representation according to  FIG. 3 , it can be seen that energy directing means  28  protrude at a certain height  46  in relation to the base faces  42 . The energy directing means  28  are part of a sealing jaw  33 . Said energy directing means  28  act during the sealing process as counter faces for the sealing face  26  of the sonotrode  10 . It can be seen according to  FIG. 5  that the tip of the energy directing means  28  protruding in the direction of the sonotrode  10  is realized with a radius  29 . In addition, the energy directing means  28  is inclined by an angle  40  toward the base face  42 . The side faces  44  of the energy directing means  28 , inclined by the angle  40 , merge with a radius, not determined in any more detail, into the base faces  42 . The described geometry is shown in an enlarged representation according to  FIG. 4 . The part face  31  of the sealing profile  36  has a sealing width  32 , the gap  30  has a gap width  32 . 
     Perspective representations in  FIGS. 6 and 7  are shown for further clarification of the drawing according to  FIGS. 2 to 5 . In this connection, the side faces  44  are relatively strongly inclined, approximately by an angle  40  of approximately 60°. In the case of the exemplary embodiment according to  FIG. 8 , in contrast, the side faces  44  are inclined by an angle  40  of approximately 120°. 
     The apparatus  8  for processing a packaging material using ultrasound operates as follows. It includes, as the essential element, the sonotrode  10  which acts as an active welding tool against the anvil  12 . The system voltage is converted by an electric generator into a high-frequency electric voltage. An ultrasonic transducer (converter), which in its turn converts the electrical energy into high-frequency mechanical oscillations, is connected to the generator. By means of an amplitude matching section (booster), the amplitudes are strengthened or reduced and are transmitted by the converter to the sonotrode  10 . The anvil  12  is the passive workpiece. The workpiece to be welded, for example the packaging material, is clamped between the anvil  12  and the sonotrode  10  in order to enable the energy transfer between the sonotrode  10  and the packaging material in this way. The anvil  12  absorbs the ultrasound oscillations of the sonotrode  10 . Both the sonotrode  10  and the anvil  12  rotate in opposite directions and are realized quasi as sealing rollers. They have several sealing faces in which a cutting function can also be incorporated for separating off the packaging material. In dependence on the type of packaging material, a sealing gap has to be set with a high level of precision. 
     The apparatus  8  serves for sealing the transverse seam of a bag. The sealing of the preliminary transverse seam of the following bag is effected by means of the first part face  31 , two bags are separated from each other by means of a cutting blade arranged in the gap  30  and the final transverse seam of the preceding bag is sealed by means of the second part face  31 . 
     In the case of ultrasound sealing, energy can only be input during the contact period between the sonotrode  10 , the film to be sealed and the energy directing means  28  of the anvil  12 . Consequently, it is sensible to optimize the energy input in particular in the case of the described rotating sealing method. This is effected by the described sealing profile  36 . The described grid-like structure of the energy directing means  28  enlarges the contact area by running in a zigzag-shaped manner along the side edge  35  of the sealing profile  36  and consequently being realized longer than a parallel, straight-lined execution along the side edge  35  as in the prior art. A uniform distribution of the sealing force is additionally achieved by means of the grid-shaped, waffle-like structure shown. In order to obtain a tight seal, two rectangles  38  are always arranged along the sealing width  32  of a part face  31 . 
     The rounded-off surface with the radius  29  of the energy directing means  28  combined with the side faces  44  inclined by the angle  40  has proved particularly advantageous for the control of the fused mass. 
     In a preferred manner, the width  32  is in the order of magnitude of 6 mm. The gap width  34  of the gap  30 , in a preferred manner, is in the order of magnitude of 3 mm. Consequently, the entire width of the sealing jaw  33  is in the order of magnitude of 15 mm. The tip of the energy directing means  28  protrudes beyond the base face  42  of the rectangles  38  at the height  46  and is approximately in the order of magnitude of 0.5 mm. The radius  29  is approximately within the range of between 0.1 to 1 mm. The angle  40 , in a preferred manner, is within a range of between 20° and 120°. The sealing jaw  33  preferably consists of steel. The sealing jaw  33  has corresponding receiving means for fastening means such as bolts or screws, by way of which the sealing jaw  33  can be fastened to the anvil.