Abstract:
A deep-drawing packaging machine that includes a sealing station and a method for changing the sealing frame together with the sealing plate at the sealing station. The sealing station includes a sealing plate and a sealing frame. The sealing plate may be releasably coupled to an upper sealing tool part, and the sealing frame may be slidably removable at a lower sealing tool part. The sealing frame may be slidable on rails. The sealing frame may include one or more centering aids for aligning the sealing plate with respect to said sealing frame during removal thereof. The centering aids may be displaceable underneath a film web by the upper sealing tool part during the clamping of the film web between the sealing frame and the upper sealing tool part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European Application Number 13156424.7 filed Feb. 22, 2013, to Christian Geble entitled “Deep-Drawing Packaging Machine with Sealing Station and Method,” currently pending, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a deep-drawing packaging machine having a sealing station comprising a sealing frame and a sealing plate, and a method of changing the sealing frame and the sealing plate at the sealing station of the deep-drawing packaging machine. 
     BACKGROUND OF THE INVENTION 
     DE 10 2004 051 923 A1 discloses a deep-drawing packaging machine with a sealing station which is designed to allow a sealing plate to rest on a lower sealing tool part together with a base plate comprising heating elements, a cover plate, a pressure plate and a further base plate as a common assembly. This common assembly is releasably attached to a housing of an upper sealing tool part. This configuration permits the accessibility for changing or servicing the tools is permitted. To be able to remove the sealing plate from the assembly and to also change parts of the lower sealing tool part which are designed depending on format, the assembly is withdrawn from the machine as a unit, and the sealing plate may be screwed off from the base plate outside the deep-drawing packaging machine. 
     EP 0 467 069 A1 shows a deep-drawing packaging machine with a forming station and a sealing station each comprising lower tool parts that may be laterally pulled out of the deep-drawing packaging machine on rails in order to be able to change format-depending insets or dividers at the lower tool part without having to remove a film web above the lower tool parts. 
     Deep-drawing packaging machines are known in which the sealing plate is releasably connected to the upper sealing tool part with threaded joints which are accessible by an operator at the upper side of an upper sealing tool part. Before the sealing plate is released, however, film webs which are guided through the sealing station must be removed or cut out such that, after having loosened the threaded joints, the operator can reach under the still heated sealing plate with one hand, which is protected by a heat-resistant safety glove, to grip the sealing plate with his/her hand and remove it from the sealing station. Such handling is on the one hand dangerous as often a still very hot tool must be gripped with one hand, and on the other hand, relatively large and therefore heavy sealing plates can no longer be handled ergonomically with one hand in this manner. The assembly or insertion of the sealing plate into the upper sealing tool part is difficult, especially because usually only a small gap between the outer contour of the sealing plate and the matching inner contour of the upper sealing tool part is provided. The sealing plate must be held at the upper sealing tool part manually until it is sufficiently, or at least partially, fastened. 
     Thus, there is a need in the art for an improved sealing plate and sealing frame configuration for a sealing station of a packaging machine and a method for removing or replacing such sealing plate and sealing frame that makes it easier and safer to remove and/or change the sealing plate and sealing frame. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to facilitate the operation of changing a sealing frame and a sealing plate of a sealing station of a deep-drawing packaging machine and to make the operation of changing the sealing frame and the sealing plate safer. 
     The deep-drawing packaging machine according to the invention may comprise a sealing station that may include a lifting device, a sealing plate, and a sealing frame. The sealing plate may be releasably disposed at an upper sealing tool part, and the sealing frame is releasably disposed at a lower sealing tool part. The deep-drawing packaging machine may be characterized in that the sealing frame includes centering aids for centering the sealing plate on the sealing frame. The centering aids may be designed such that they may be displaced by the upper sealing tool part underneath the film web when a film web is clamped between the sealing frame and the upper sealing tool part. Thus, this configuration allows a film web to be clamped between the sealing frame and the upper sealing tool part around its entire periphery and create a chamber in which the package may be evacuated and/or treated with gas before being sealed with a lid film. In this process, the centering aid only exerts forces that do not damage the film web and do not lead to the formation of folds of the film web within the sealing station. 
     The centering aids do not have to be removed from the sealing frame manually after the sealing plate has been replaced, resulting in an automatic centering of the sealing plate on the sealing frame. The sealing plate may be placed onto the sealing frame between or onto the centering aids manually; and during the movement of the sealing plate and the sealing frame using the lifting device in the direction of the upper sealing tool part, the sealing plate remains in a position fixed by the centering aids to be able to travel into the upper sealing tool part in an accurate position and without collision or further adjustment to align the sealing plate with respect to the fasteners. 
     Preferably, the sealing plate may be received by the sealing frame. For example, the sealing frame is located in an upper position in which it is in contact with the sealing plate. The fastening of the sealing plate at the upper sealing tool part is released and the sealing plate is lying with its weight on the sealing frame. In this embodiment, an access to the heated sealing plate by an operator is not intended or required. 
     In an advantageous embodiment, the lower sealing tool part may be laterally moved out of the deep-drawing packaging machine together with the sealing frame and the sealing plate to change the sealing frame and the sealing plate. In this lateral changing position, the sealing plate and the sealing frame are ergonomically easily accessible by the operator, and the heated sealing plate may thus be changed by using the sealing frame that is not heated, thereby reducing the risk to the technician. 
     Preferably, the sealing plate may be fixed to the upper sealing tool part using threaded joints, and the fasteners (threaded fasteners) are accessible to a technician from outside the upper sealing tool part. As an alternative, the sealing plate may be automatically fixed to the upper sealing tool part using at least one actuator. The advantage of both designs resides in that, in case of a change of the format division of the packages, only the sealing plate as a component cooperating with the packages must be changed and not the complete upper sealing tool part, optionally with its heating elements, its cooling water circuit and operating elements for generating a sealing pressure, for example the use of a membrane to generate sealing pressure as known in the art. This reduces efforts and time for retooling the deep-drawing packaging machine and also reduces the risk of injuries by a still very hot sealing plate. 
     Preferably, the sealing frame may include centering aids located at two or more corners (more preferably at four corners) for orienting the corners of the sealing plate. A reduction of the clearance of the sealing plate with respect to the sealing frame allows the sealing plate and the sealing frame to exist with very small lateral clearances of the sealing plate within the upper sealing tool part, where the upper sealing tool part may comprise a congruent recess at the inner surface for receiving the sealing plate. 
     Preferably, a centering aid comprises one or several pins that may be spring-loaded. The spring-loaded pins may be preferably lowered or retracted into the sealing frame in a moving direction of the lifting device such that the film web is not damaged. This embodiment permits a structurally simple and thus also inexpensive construction. 
     A pneumatic actuation of the pins, where the spring-loading of the pins could be eliminated, is also conceivable. 
     The method according to the invention for changing the sealing frame and the sealing plate together at a sealing station of a deep-drawing packaging machine includes: lifting the sealing frame upwards to an upper sealing tool part using a lifting device after film webs have been removed from in-between the upper sealing tool part and the sealing frame, releasing the sealing plate from the upper sealing tool part to deposit the sealing plate on the sealing frame, and lowering the sealing frame and the sealing plate using the lifting device, wherein centering aids provided at the sealing frame cooperate to align the sealing plate with the sealing frame. The alignment with the sealing frame also aligns the sealing plate with the upper sealing tool part so that when re-inserted into the sealing station, the sealing plate aligns with the fasteners which couple the sealing plate to the upper sealing tool part. 
     The centering aids do not have to be removed from the sealing frame manually after the sealing plate has been replaced, resulting in an automatically acting centering of the sealing plate on the sealing frame. 
     Preferably, the sealing frame and the sealing plate may be laterally moved out of the deep-drawing packaging machine in a lower changing position of the lifting device to grant access to the sealing frame and the sealing plate for replacement or servicing purposes. It is thus possible for an operator to ergonomically carry out retooling at the sealing station. 
     In an advantageous embodiment, the sealing frame lifts the sealing plate upwards to the upper sealing tool part using the lifting device to fix the sealing plate at the upper sealing tool part. 
     Preferably, the centering aids are displaced in the sealing frame as soon as the sealing plate has been fixed in the upper sealing tool part and the sealing frame is in contact with the upper sealing tool part. 
     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 
       The accompanying drawings form a part of the specification and are to be read in conjunction therewith, in which like reference numerals are employed to indicate like or similar parts in the various views. 
         FIG. 1  is a schematic side view of a deep-drawing packaging machine in accordance with the teachings of the present invention; 
         FIG. 2  is a front perspective view of a sealing station in accordance with the teachings of the present invention shown in an opened position; 
         FIG. 3  is a front perspective view of the sealing station of  FIG. 2  shown in a lower changing position after the sealing plate has been received by the sealing frame; 
         FIG. 4  is a front perspective view of the sealing station of  FIG. 2  shown with the sealing frame and the sealing plate located at a lateral changing position; 
         FIG. 5  is a top plan view of a the sealing frame in accordance with the teachings of the present invention; 
         FIG. 6  is a sectional view of a centering aid of the sealing frame of  FIG. 5  cut along the line  6 - 6 ; and 
         FIG. 7  is a sectional view of the sealing station of  FIG. 2  cut along the line  7 - 7  wherein the sealing station is in a closed position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description of the present invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the present 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 spirit and scope of the present invention. The present invention is defined by the appended claims and, therefore, the description is not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
       FIG. 1  shows a deep-drawing packaging machine  1  according to the invention in a schematic view. The deep-drawing packaging machine  1  comprises a forming station  2 , a sealing station  3 , a transverse cutting unit  4 , and a longitudinal cutting unit  5  which are disposed at a machine frame  6  in this sequence in a production direction R. At the entry side, a feed roller  7  is located at the machine frame  6  from which a film web  8  is unwound. In the region of the sealing station  3 , a material storage  9  is provided from which a lid film  10  is unwound. At the exit side, a discharge apparatus  13  in the form of a conveying belt is provided at the deep-drawing packaging machine using which finished, singled packages are carried away. Furthermore, the deep-drawing packaging machine  1  comprises a feeder which grips the film web  8  and transports it further in the production direction R in each main cycle. The feeder may include, for example, clamps  34  attached to advancement chains (not shown) which are disposed on either side of the film as shown in  FIG. 7 . 
     In the shown embodiment, the forming station  2  is embodied as a deep-drawing station in which cavities  14  are formed into the film web  8  by deep-drawing. The forming station  2  may be designed such that several cavities are formed next to each other in the direction perpendicular to the production direction R. In the production direction R downstream of the forming station  2 , an insertion section  15  is provided in which the cavities  14  formed in the film web  8  are filled with products  16 . 
     The sealing station  3  has a lifting device  21  and a sealable chamber  17  in which the atmosphere in the cavities  14  may be replaced by a replacement gas or a gas mixture before sealing, for example by evacuation or gas flushing. 
     The transverse cutting unit  4  is embodied as a punching machine which cuts through the film web  8  and the lid film  10  between adjacent cavities  14  in a direction transverse to the production direction R. In this process, the transverse cutting unit  4  operates such that the film web  8  is not cut through across its total width, as the film may not be cut at least in an edge region. This permits a further transport by the feeder that is also controlled. 
     In the shown embodiment, the longitudinal cutting unit  5  is embodied as a knife arrangement with several rotating revolving knives by which the film web  8  and the lid film  10  are cut through between adjacent cavities  14  and at the lateral edge of the film web  8 , so that there are singled packages downstream of the longitudinal cutting unit  5 . 
     The deep-drawing packaging machine  1  furthermore comprises a control unit  18 . The latter has the task of controlling and monitoring the processes running in the deep-drawing packaging machine  1 . A display device  19  with operational controls  20  serves to visualize or influence the process operations in the packaging machine  1  for or by an operator. 
     The general working manner of the packaging machine  1  will be briefly described below. The film  8  is reeled off from the feed roller  7  and transported into the forming station  2  by the feeder. In the forming station  2 , cavities  14  are formed in the film web  8  by deep-drawing. In a main cycle, the cavities  14  are transported further, together with the surrounding area of the film web  8 , to the insertion section  15  where they are filled with products  16 . 
     In the main cycle, the filled cavities  14  are subsequently transported further to the sealing station  3 , together with the surrounding area of the film  8 , by the feeder. The lid film  10  is transported further with the feed motion of the film web  8  after an operation of sealing it to the film web  8 . In the process, the lid film  10  is reeled off from the material storage  9 . By sealing the lid film  10  onto the cavities  14 , closed packages are formed which are singled in the subsequent cutting operations  4  and  5  and transported out of the deep-drawing packaging machine  1  using the discharge apparatus  13 . 
     A group of cavities  14  which are formed into the film web  8  in the forming station  2  during one cycle and which are then intermittently transported in the production direction R, is defined as a format. One format may comprise several packages or cavities  14  both in the production direction R and transverse to it, for example 4×4 cavities. In case of a format change from 4×4 to 3×3 cavities, for example, parts of the forming station as well as parts of the sealing station  3 , especially a sealing frame and a sealing plate, must be changed. 
       FIG. 2  shows a sealing station  3  in an opened position. The lifting device  21  may move up and down a lower sealing tool part  22  with the format-dependent sealing frame  23  located on it. The sealing station  3  comprises an upper sealing tool part  24  at the top in which a sealing plate  25  is disposed. The sealing plate  25  is releasably fixed in the upper sealing tool part  24  using a fastener  26   a , each fastener  26   a  may be covered by covers  26  such that an operator may access the threaded fasteners from outside the upper sealing too part  24  of the sealing station. In this example, six threaded fasteners  26   a  are provided as the fastener. However, other fastening methods, such as clamps, actuators, bolts, or any other method is within the scope of the present invention. At the sealing station  3 , arms  27  may be provided transversely to and laterally of the production direction R to be able to laterally pull out the lower sealing tool part  22  on the arms  27 . 
       FIG. 3  shows the sealing station  3  in a lower changing position after the lifting device  21  has lifted the sealing frame  23  upwards to the upper sealing tool part  24  to receive the sealing plate  25  on the sealing frame  23  after the sealing plate  25  has been released from the upper sealing tool part  24  by releasing the threaded fasteners  26   a . During a downward movement of the lifting device  21  (see arrows), the sealing plate  25  is resting on the sealing frame  23  and centered by pins  28  as centering aids. This is also the case during an upward movement of the lifting device  21 , and it is all the more important for the sealing plate  25  to be able to enter into the upper sealing tool part  24  in an accurate position and without collision. 
     In  FIG. 4 , the lateral changing position (see arrow) for the sealing frame  23  and the sealing plate  25  is shown, where both are resting on the lower sealing tool part  22 . All three components  22 ,  23 ,  25  are laterally slidable and have been laterally pulled out of the sealing station  3  on the rail-like arms  27 . While these parts  22 ,  23 ,  25  are located on the arms  27 , an operator may ergonomically advantageously change the sealing plate  25  and the sealing frame  23  to retool the sealing station  3  to a new format or to just clean the sealing frame  23  and/or the sealing plate  25 . 
       FIG. 5  shows in a plan view the sealing frame  23  with a format for 4×3 cavities  14 . At all four corners of the sealing frame  23 , two pins  28 ,  28   a  each are provided as centering aids via which the sealing plate  25  or the corners E of the sealing plate  25  are aligned on the sealing frame  23 . Corners E are indicated by dashed lines, are centered on the outer wall of sealing frame  23 . Furthermore, sealing frame  23  may also include pins  29   a  for facilitating gas treatment and evacuation bores  29   b  for allowing for the removal gas or air from the packages during the sealing step. 
     In the upper right part of the representation of  FIG. 5 , a section  6 - 6  through the pin  28   a  is shown, which is shown enlarged in  FIG. 6 . The pin  28   a  is mounted in the sealing frame  23  via a pressure spring  30  and a screwed bolt  31  such that the pin  28   a  may be moved downwards and compresses the pressure spring  30  in the process. A sealing gasket  32 , which may be manufactured from silicone, is provided on the sealing frame  23  and received in a groove  33  of the sealing frame  23  to at least help secure gasket  32  to sealing frame  23 . 
     The functioning of the pins  28 ,  28   a  will be illustrated in more detail with reference to  FIG. 7 .  FIG. 7  shows a partial detail as a sectional view through a pin  28   a  in the production direction R. The assembly of the lower sealing tool part  22 , the sealing frame  23  disposed above it and the sealing gasket  32  clamps the film web  8  and the lid film  10  against the upper sealing tool part  24 , so that a surrounding hermetical sealing along the outer dimension of the sealing gasket  32  and the sealing frame  23  to form a chamber  17  (see  FIG. 1 ) for the evacuation and/or gas treatment of the interior of the package or the cavity  14  (see  FIG. 1 ) is formed at least in film  8 . The seal may be formed in both film  8  and  10 . During the upward movement of the sealing frame  23  to the upper sealing tool part  24 , just before the working position is reached, the pin  28   a  and all further pins  28  come into contact with their upper sides with the film web  8  which is resting against the bottom side of the upper sealing tool part  24 , and they are pressed or lowered downwards, or retract, into the sealing frame  23  (see downward arrow), that means they are displaced underneath the film web  8 . The pressure spring  30  is configured such that the spring force is only large enough for the pin  28   a  to automatically project again out of the sealing frame  23  in a downward movement using the lifting device  21  to center the sealing plate  25 , and the pin  28   a  does not damage the film web  8  in the working position. This applies to all pins  28 . 
     It is conceivable to provide, instead of the pins  28 , molded parts as centering aids which cooperate, for example, each with a corner E of the sealing plate  25  on two sides to align the sealing plate  25  with respect to the sealing frame  23 . The molded parts could have an L-shape, four molded parts being preferably provided. The molded parts may cooperate with one or several springs corresponding to the invention. The larger surface at the upper side of a molded part, compared to the pin  28 , results in a lower surface pressure at the film web  8 , and thus in a reduction of the load on the film web  8 . 
     As is evident from the foregoing description, certain aspects of the present invention are not limited to the particular details of the examples illustrated herein. It is therefore contemplated that other modifications and applications using other similar or related features or techniques will occur to those skilled in the art. It is accordingly intended that all such modifications, variations, and other uses and applications which do not depart from the spirit and scope of the present invention are deemed to be covered by the present invention. 
     Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosures, and the appended claims.