Abstract:
A molding device includes a device for displacing at least one molding tool ( 10, 10   a ), especially for the production of geometrics of plastic containers, by a linking motion ( 12 ) which brings the respective molding tool ( 10, 10   a ) into a closing position (I-I) for at least the closure of the mold. The linking position ( 12 ) can be operated by a drive ( 14 ). Based on the linking motion ( 12 ), a novel drive and displacement concept for the respective molding tool is provided, enabling the hydraulic means to be totally dispensed with a drive, preferably an electric drive, can be used, especially in the form of a stepping motor.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a molding device, particularly for forming plastic containers, having a molding tool coupled to a link motion control element for moving the molding tool between opening and closing positions. 
   BACKGROUND OF THE INVENTION 
   Processes and molding devices for producing containers are known in the prior art. For example, DE 199 26 329 A1 discloses a process and molding device in which a hose of plasticized plastic material is extruded into a molding mechanism. One end of the hose is closed by heat sealing. The closed end hose is expanded by generation of a pneumatic pressure gradient acting on the hose and applied to the molding wall of the molding mechanism having two opposite molding tools to form the container. The plastic container is then filled under sterile conditions into the molding mechanism by an appropriate charging mandrel. After the charging mandrel has been removed, the filled container is hermetically sealed with a specific head geometry being formed. For the purpose of forming the plastic container proper, in which fluid is later stored, two container molding jaws may be moved toward each other by hydraulic drive means to obtain a closing position and away from each other into one of their opening positions. 
   The head geometries to be generated by the two separately actuatable head jaws regularly also comprise the neck component of the plastic container, including one in the form of an ampule. The container is closed by a head piece connected at a separation point that may be opened for a fluid removal process as soon as the head piece is separated by the separation point from a toggle piece molded on it, and, in this way, removed from the plastic container proper. 
   Such processes have been disclosed in a plurality of embodiments and are widely used in packing systems for liquid or paste products, for example, in the disclosed “bottelpack7” system. 
   The hydraulic drive systems regularly employed in practical applications for the respective feed movement of the molding tool present problems. Any leakage may result in fouling with the fluid, something which results in problems especially when the molding machines are used for plastic containers in the pharmaceutical and food packaging spheres and in medical technology in general. The maintenance cost is also increased. The hydraulic drive systems do not reach the desired or high cycle frequencies for mass production for precise positioning of the molding tools for shaping of containers. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a molding device for moving at least one molding tool permitting application of modern drive concepts, such as ones in the form of electric or pneumatic drives. The maintenance cost of such drives is reduced. Especially high rates of output of goods can be produced, particularly plastic containers, along with high positioning accuracy for the molding tools. 
   The object is basically attained by a molding device according to the present invention provided with a link motion control element for moving at least one molding tool, especially one for generation of container geometries in plastic containers. This element moves the respective molding tool to a closing position at least for closing the mold, the link motion control element being actuatable by a drive. On the basis of the link motion control element, a novel drive and movement concept is presented for the respective molding tool, one which makes it possible to dispense with hydraulic drive means entirely, and by preference to employ an electric or pneumatic drive as the drive means. The link motion control element may, however, continue to be actuated conventionally by a hydraulic drive if the respective application appears to call for it and rigid requirements have not been set for sterile filling or clean room qualities. 
   The molding device of the present invention, with a drivable link motion control element for a closing movement of the molding tool, permits uniform, safe, and position-accurate driving of the respective molding tool and involves only a minor maintenance effort. The link motion control element may be employed to execute a plurality of opening and closing processes in rapid sequence. The molding device of the present invention results in high output of goods to be produced, in particular those in the form of blow-molded plastic containers filled under sterile conditions. 
   In one preferred embodiment of the molding device of the present invention, the link motion control element has a slot guide positioned on the exterior circumference of a body of rotation actuatable by a drive. Preferably, provision is also made such that an actuating member is engaged in the guide slot and operates in conjunction with a slide component. Also, during rotation of the slot guide from one of its end positions to its other end position and vice versa, the slide component with molding tool associated with it may be displaced with the molding tool by the actuating member moved longitudinally in this manner from a closing position to an opening position of the mold shaped by the respective molding tool and vice versa. Safe and precise positioning control is achieved as a result, along with clearly defined specific closing forces specified by the link motion control element. 
   In another especially preferred embodiment of the molding device of the present invention, the maximum closing force for the molding tool may be specified by central adjusting means on the slide component means, preferably in the form of an energy accumulator. Pressure spring elements, such as ones in the form of disk springs or the like, are suitable for use as energy accumulators. Independently of the closing force of the link motion control element which is applied, this force may be appreciably limited, and the reliability of shaping is thereby increased by the adjusting means. It has been found in configuration of the molding device to be especially cost-effective to mount the body of rotation together with the drive so as to be stationary on a machine frame in relation to which the slide component may move back and forth along its rail guide. A rigid machine configuration is achieved for the slide component and for the molding device as a whole. Obstacles in operation are reliably eliminated on the basis of the rail guide. 
   In another especially preferred embodiment of the molding device of the present invention, the molding tools mounted opposite each other may be moved by a single link motion control element synchronously by a common driving component. By preference, at least four link motion control elements are positioned in pairs, one opposite the other, and may be driven by gearing actuatable by the drive and the common drive component. As a result, a total of four molding tools with mold geometries mounted in sequence may be actuated in pairs operating together synchronously for shaping and mold opening processes to produce several container geometries. 
   In one preferred embodiment, as protection from collision, a monitoring assembly monitors the position of the link motion control element, at least with respect to the position of the molding tool in its closing position, but preferably also in its opening position. 
   It has also been found to be favorable for obstacle-free operation in one preferred embodiment of the molding device of the present invention for the path equation for the slot guide of the body of rotation to be executed as a Bestehorn sinoid. 
   Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
       FIG. 1  is a top plan view of the molding device as a whole and partially in section, according to an embodiment of the present invention; 
       FIG. 2  is a top plan view in section of an enlarged portion of the upper left segment of  FIG. 1 ; and 
       FIG. 3  is a view of the path geometry of a link motion control element mounted on a body of rotation and having slot guides, applied in the molding device shown in  FIGS. 1 and 2 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A part of the molding device as a whole for moving a molding tool  10  is described with reference to the upper left segment of the illustration in  FIG. 1  and  FIG. 2 . On its free front side, the molding tool  10  has trough-like recesses (not shown). The recesses form mold halves for generation of container geometries for plastic containers (not shown), including ones in the form of ampules. For the purpose of generating the respective container geometries, the molding tool  10  operates in conjunction with a corresponding molding tool  10   a  with correspondingly shaped recesses (not shown). The two molding tools  10 ,  10   a  are in the closed molding position in  FIG. 1 , in which position the free front surfaces of the molding tools  10 ,  10   a  meet along a closing separation line I-I. 
   For the purpose of moving the respective molding tool  10 ,  10   a , a link motion control element  12  may be driven by a centrally mounted drive  14 . For the sake of simplicity,  FIG. 1  only shows the spline shaft of the drive which may be coupled to the driven shaft of an electric motor, such as one in the form of an electric stepping motor, and permits driving of the link motion control element  12 . For this purpose, the spline shaft  14  is rotatably mounted by bearings  16  in a machine frame  18 , and has a drive gear  20  on its one free side facing the molding tool  10 . The drive gear  20  meshes with a driven gear  22  of the link motion control element  12 . The link motion control element  12  has a slot guide  24  positioned on the external circumference side on a body of rotation or rotation body  26 . The body of rotation may be powered by drive  14  and is essentially cylindrical in configuration. The respective slot guide  24  has two path or curve segments  28  resulting from development of the body of rotation  26  as show in  FIG. 3 . The respective path curve of a curve segment  28  obeys a path equation for a Bestehorn sinoid. The respective body of rotation  26  with its path curve segments  28  need not be configured to be identical for the molding tool  10   a  to the body of rotation  26  for the molding tool  10 . In this instance, slight adaptations may be necessary with respect to the control curve pattern. However, the bodies of rotation  26  of the two mold halves  10 ,  10   a  are in other respects essentially the same. 
   An actuating member  30  in the form of a cam follower engages the slot guide  24  with its two path curve segments  28 . The actuating member  30  is mounted rotatably on opposite sides of a slide component  32  so that, as the body of rotation  26  with its slot guide  24  rotates, uniform advance in the direction of closing of the molding tools  10 ,  10   a  is ensured, along with uniform resetting movement into a corresponding opening position, the respective rearward position being indicated by a broken-line circle at the top left in  FIG. 1  and in  FIG. 2 . When the slot guide  24  rotates from one of its end areas  34  to the other end area  36  of a path curve segment  28 , the slide component  32  may be displaced longitudinally in one direction of movement and in the other direction when the body of rotation rotates in the opposite direction. Consequently, the maximum path of travel which may be reached for the slide component  32  is determined by the longitudinal axial distance between the end areas  34 ,  36  opposite each other of two different path curve segments  28  of a slot guide  24  of a body of rotation  26 . 
   The slide component  32  has on its frontal side facing the molding tool  10  a guide component  38  on which the respective molding tool  20  may be mounted so as to be replaceable. The guide component  38  is mounted on the edge side so that it may be displaced axially in the longitudinal direction along two rail guides  40 . The ends of the rail guides  40  are appropriately mounted in the machine frame  18 . In addition, the guide component  38  is retained so that it may be displaced longitudinally in a displacement component  42  of the slide component in a direction in parallel with the rail guides  40 . The displacement component  42  rests on adjusting means  44  in the form of a disk spring package which functions as a compression spring. In this way the maximum closing force for the molding tool  10  may be determined by the adjusting means  44  so that a reliably operating shaping process is made possible. 
   In  FIG. 1 , a drive component  46  in the form of a drive shaft is mounted at the top in parallel with the upper rail guide  40 . At both ends of the drive shaft  46 , a crown gear  48 ,  48   a  is connected to this shaft. As the body of rotation  26  moves by the drive shaft  14 , the driven gear  22  meshes with the crown gear  48 , thereby driving the drive shaft  46 , which in turn transmits the driving power by the crown gear  48   a  on the opposite side to the following driven gear  22  of the body of rotation  26  following in the drive chain. Consequently, the molding tools  10 ,  10   a  mounted opposite each other may be actuated and moved in pairs by a single link motion control element  12  with drive  14 , by the common drive component  46 . Hence, molding tools  10 ,  10   a  move synchronously into their opening position and into their closing position along the closing separation line I-I. 
   As is also to be seen in the illustration in  FIG. 1 , four link motion control elements  12  positioned opposite each other in pairs may be actuated in the drive direction appropriate for back-and-forth movement of the slide components  32  of the molding device by the gears operated by the drive  14  including gears  20 ,  22  and  48 ,  48   a . The respective drive is very accurate and permits precise positioning of the respective molding tool  10 ,  10   a  for a molding process. In addition, the molding tools  10  opposite each other in one line may be connected to each other on one side, but may also be separated from each other. Such positioning may also apply correspondingly to molding tools  10   a  mounted opposite each other. 
   As is also to be seen in  FIG. 2 , a monitoring assembly  50  is provided. It is spring-loaded and may be displaced longitudinally from its locking position illustrated in  FIG. 2  into a release position, preferably from the exterior by an actuator, in particular one in the form of a pneumatic cylinder or the like. The body of rotation  26  accordingly has on the external circumference side a first recess  52  corresponding to the closing position of the molding tools  10 ,  10   a . If locking occurs in this locking position, that is, if parts of the monitoring assembly  50  are engaged in the associated recess  52  in the body of rotation  26 , it is made certain that a locking position has been assumed along the closing separation line I-I by the molding tools  10 ,  10   a  and that the machine control unit then recognizes that a reliable molding process is possible. If, as a result of an error, the proper closing position is not assumed, the monitoring assembly  50  ascertains this and the molding process could be halted without damage to the molding device. The reset opening position area for the molding tools  10 ,  10   a  may also be monitored synchronously by the monitoring assembly  50 , by a recess (not shown) positioned diametrically opposite recess  52 . In addition, the drive shaft  46  is mounted on the end side so as to be rotatable, by additional bearings  54  in the machine frame  18 . 
   The configuration of the described molding device makes it possible to reach very high cycle speeds in production of molded containers of a plastic material, along with very high machining accuracy, in view of the specifiable accuracy of positioning of the molding tools  10 ,  10   a , with respect both to their closing position and to movement apart into their opening position for the production mold. The molding device is very rigidly configured from the viewpoint of its structural design, so that precise actuation of the moving parts is ensured. Also, the molding device may be very cost-effectively produced and maintained because of the equivalent parts employed. 
   While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.