Patent Publication Number: US-2023145486-A1

Title: Method for producing a container product and device for implementing the method

Description:
The invention relates to a method for producing at least one molded, filled and sealed container product, such for example bottles or ampoules, and to a device for implementing the method. 
     WO 02/49821 A2 discloses a method for blow molding, filling and sealing containers, such as ampoules, in which at least one hose of plasticized plastic material is extruded into an open mold. Sealing the mold welds the hose at its leading end. In addition, a separating element is used to cut the hose above the mold to form a filling opening. The mold and the hose section inside is then moved to a filling position, where the container is filled after it has been formed in the mold by generating a pressure gradient acting on the hose and expanding it. After filling, the container is sealed while still in the mold. In addition, a corresponding device is disclosed. 
     The invention addresses the problem of further improving the known blow molding, filling and sealing process in terms of its efficiency. 
     A method for producing at least one molded, filled and sealed container product having the features of patent claim  1  in its entirety solves such a problem. 
     The method according to the invention is characterized by at least the method steps outlined below:
         extruding a hose by means of an extrusion device using supporting gas in the vertical extrusion direction in a preforming position,   sealing the hose at its lower end and cutting it off at its upper open end,   transporting such a parison cut to length using a gripper device in a linear transport direction transverse to the extrusion direction from the preforming position into an open molding tool,   transferring the parison into the opened molding tool using the gripper device in a main forming position,   sealing the molding tool for the purpose of further forming the parison using a pressure gradient,   filling and sealing the parison, and   returning the gripper device to the preforming position for a repeated sequence of the method steps listed above.       

     The hose is extruded in a heat-softened state, wherein the term “heat-softened” shall be defined to denote a plasticized state of a thermoplastic, in which forming by means of a pressure gradient and/or welding is possible without supplying additional heat. Heat-softened parisons typically have an average temperature of 150° C. to 210° C., depending on the plastic material. 
     Suitable plastics for the method according to the invention are semi-crystalline polyolefins, such as polyethylene (PE), in particular low-density polyethylene (PE-LD), high-density polyethylene (PE-HD) and polypropylene (PP). Advantageously, amorphous polyolefins such as cycloolefin polymers (COP) and cycloolefin copolymers (COC) can also be processed according to the invention. The method according to the invention can also be used to produce multilayer containers—as described in DE 10 347 908 A1. 
     Due to the features of claim  1 —in contrast to the method known from the prior art—based on the stationary arrangement of the molding tool, the molding tool does not have to be moved from the extrusion device to the molding-filling-sealing station, hereinafter also referred to as the sealing station, and vice versa during every process run. This not only eliminates the need to move the molding tool, which can be very heavy if several cavities are provided for the production of one container product each, but also facilitates the precise alignment of the mold halves of the stationary molding tool with each other for the production of the container product. In addition, owing to the stationary arrangement of the molding tool according to the invention, its ports, for instance in the form of a power supply, a cooling medium supply and/or a compressed air supply, do not have to be moved along during motions of the molding tool from the extrusion device to the sealing station and vice versa. This reduces the amount of energy required to perform the method, rendering it simple and inexpensive to perform. 
     Furthermore, due to the hose being sealed at its lower end by applying a closing force by means of the gripper device, which is separate from the molding tool, the closing force of the molding tool for welding in this area is lower than the closing force of the gripper device. 
     Because the heat-softened parison is not extruded directly into an open mold, but is held by the gripper device and moved from the preforming position to the main mold position, the parison is largely freely accessible for further additional method steps before it is transferred to the molding tool. In that way, already in the preforming position the outer diameter of the heat-softened hose can be limited by a shaping tool, such as a calibrating element, which is positioned around the heat-softened hose before it is cut off. The use of a calibration element has proved particularly useful for thin-walled parisons, i.e. parisons having an average wall thickness of less than approx. 0.2 cm. Furthermore, to improve the properties of the parison, in particular for a targeted modification of its surfaces, the inner and/or outer surface(s) of the parison can be treated using a fluid, for instance, to flush it with sterile air or an inert gas for medical purposes. Furthermore, the temperature of all or part of the parison can be controlled using cooling, heating, shielding and/or reflecting devices or based on motion time or speed controlled by a control device. In addition, a test of deviations from the predefinable target of an extruded parison, for instance with regard to dimensions, weight, temperature, transparency and/or particle inclusions, can be performed particularly easily and inexpensively, so that the extrusion process can be controlled just as easily and inexpensively based on a corresponding test. As a result, the method can be performed particularly efficiently. This is without parallel in the prior art. 
     Particularly in the case of parisons of low weight and/or low volume, during rapid motions one would expect deformations, spatial deflections and/or agglutinations when several parisons being transported simultaneously. Surprisingly, it turned out that even parisons weighing less than approximately 0.07 kg and/or having a volume of less than 500 ml can be moved without any problems using the gripper device when the heat-softened parison is held at two points. In this case, it has also surprisingly turned out that no significant inhomogeneous thickening or bead formation of the parison, which would actually be expected, occurs during transport if the transport time in the gripper device is less than approximately two to three seconds. 
     The invention also addresses a device for implementing a method described above, comprising at least the components listed below: extrusion device, gripper device and molding tool. 
     Further embodiments of the method and device according to the invention are subject of the dependent claims. 
    
    
     
       The method of producing at least one formed, filled and sealed container product, according to the invention by means of a device according to the invention for implementing such a method is explained in more detail below according to the drawing. In the figures, in general view, not to scale, 
         FIG.  1    shows a perspective view of the device according to the invention, wherein a hose extruded by means of an extrusion device is arranged in a preforming position between one open pair of gripper jaws each of two tongs of a gripper device; 
         FIG.  2    shows an, compared to  FIG.  1   , enlarged partial view of the device of  FIG.  1    in the area of the pairs of gripper jaws of the tongs, wherein an open calibration element is provided between the tongs; 
         FIG.  3    shows a perspective view of the open calibration element of  FIG.  2   ; 
         FIG.  4    shows a perspective view of the device of  FIG.  1   , wherein the pairs of gripper jaws of the tongs are closed and the upper pair of gripper jaws enclose the hose tightly; 
         FIG.  5    shows a perspective view of the device of  FIG.  2   , wherein the closed calibrating element and the upper pair of gripper jaws encompass the hose spaced apart; 
         FIG.  6    shows a perspective view of the calibration element of  FIG.  3    in a closed state; 
         FIG.  7    shows a perspective view of the device of  FIG.  5   , wherein the calibrating element and the upper pair of tongs enclose the hose tightly; 
         FIG.  8    shows a perspective view of the assembly of  FIG.  1   , wherein a parison is arranged between opened holding, head and forming jaws of a molding tool while being held in a main forming position by the gripper device; 
         FIG.  9    shows a perspective view of the device of  FIG.  8   , wherein the holding, head and forming jaws are closed; and 
         FIG.  10    shows individual steps of a blow-molding, filling and sealing process, partly in a longitudinal section, partly in view. 
     
    
    
       FIG.  1    shows a device according to the invention for implementing a method according to the invention for producing at least one blow-molded, filled and sealed container product  10 , in particular produced from at least one plastic material. The device has a stationary extrusion device  12  with a hose head  14 , a movable cutting device  16 , a stationary molding tool  18  that can be opened and closed and a movable gripper device  20  for transporting a parison  22  that has been extruded by means of the hose head  14  and cut to length by means of the cutting device  16 , from the extrusion device  12  to the molding tool  18 . 
     In addition, the device has a support gas supply (not shown in the figures) directed into the interior of the hose  32  , which support gas supply may be identical to the support gas supply disclosed in DE 102 45 318 A1. Optionally, the device may have a calibration element  51  for a sectionally calibration of the outer diameter of the heat-softened hose  32  in the preforming position. 
     The gripper device  20  has two tongs  24 ,  26 , which, each extending in a horizontal plane, are aligned in parallel to each other, so that they are arranged congruently and superposed. Both tongs  24 ,  26  have a pair of angled legs  28  matching each other. The legs  28  of all tongs  24 ,  26  are arranged side by side and articulated mirror-symmetrically at the free ends of a U-shaped connecting plate  30  extending vertically between the tongs  24 ,  26 . The connecting plate  30  keeps the tongs  24 ,  26  at such a distance from one another that the tongs  24 ,  26  can each hold a hose  32  extruded by means of the hose head  14  of the extrusion device  12  at its two end areas. For this purpose, all tongs  24 ,  26  have a pair of gripping jaws  34 ,  36  at their ends facing the molding tool  18 . 
     The gripping jaws  34  of the first tongs  24 , which are closest to the hose head  14 , each have a semicircular recess  38  on their opposite sides, such that the two closed gripping jaws  34  of the first tongs  24  in conjunction form a circular recess as a receiving opening, whose diameter is slightly larger than the diameter of the extruded hose  32 . One slot  40  is made in each of the gripping jaws  34  of the first tongs  24 , starting from their mutually opposite inner sides, which slot  40  is connected to a vacuum pump (not shown in the figures) via a channel extending through the respective leg  28 , for the purpose of generating a vacuum for holding the hose  32  circumferentially at its upper end area nearest the extrusion device  12  by suctioning the hose  32  using the two gripping jaws  34  of the first tongs  24 . The gripping jaws  36  of the second tongs  26  are formed without recesses, so that they lie flat against each other in the closed state, forming a clamping gap. As a result, the second tongs  26  can hermetically seal and hold the still heat-softened extruded hose  32  at its end area furthest from the extrusion device  12 . A drive  42 ,  44  each is arranged between the legs  28  of all tongs  24 ,  26  in their lower end area furthest from the molding tool  18 , which drive  42 ,  44  is hinged at the end to both legs  28  for the purpose of synchronous, simultaneous actuation of the respective tongs  24 ,  26 . 
     A temperature-control not shown in the figures may be provided, which has a cooling circuit that cools the gripper jaws  34 ,  36  of the respective tongs  24 ,  26  for the purpose of preventing unwanted sticking of the hose  32  or parison  22  to the gripper jaws  34 ,  36  of the respective tongs  24 ,  26 . For gripping several hoses  32  arranged side by side in a row, the respective tongs  24 ,  26  can be designed as angular grippers in the form of a parallel gripper (not shown) as an alternative to the present design. The first tongs  24  may also be multi-part in that their gripping jaws  34  are interchangeable for the purpose of adapting the receiving opening  38  of the first tongs  24  to a predetermined hose diameter. 
     On one side at its central area the U-shaped connecting plate  30  is firmly connected to a carriage  46 , which can be moved on a rail  50  by means of a linear drive  48 . The end areas of the rail  50  are supported on a rectangular base plate  56  of the device by means of respective foot parts  52 ,  54  and the rail  50  extends in parallel to the base plate  56  aligned in the longitudinal direction of the base plate  56  and the tongs  24 ,  26 , which are also aligned in parallel to the base plate  56 . Both foot parts  52 ,  54  are each formed as L-shaped angles and are firmly connected to the rail  50  at a distance from each other on the side facing away from the hose head  14 . A drive  58  of the linear actuator  48  engages with the end of the rail  50  facing away from the hose head  14  of the extrusion device  12  and simultaneously protrudes longitudinally along the base plate  56  beyond the base plate  56 , and extends vertically therefrom away from the rail  50  towards the base plate  56 . 
     Advantageously, a calibration by sections of the outer diameter of the heat-softened hose  32  can be performed in the preforming position. For this purpose, a calibration element  51  ( FIGS.  2  and  3   ), preferably stationary, is provided, which has a largely rectangular base part  49  and two calibration jaws  57 . The calibration element  51  can be used to delimit the outer diameter of that part of the hose, which is enclosed by the calibration jaws  57  of the closed calibration element  51 . The mount of the calibration element  51  is not shown in the figures. 
     One calibration jaw  57  each is articulated to the end areas of the two side surfaces of the base part  49  extending in the longitudinal direction of the base part, with one degree of freedom such that the calibration jaws  57  can be moved between an open position, in which they extend perpendicularly away from the side surfaces of the base part  49 , and a closed position, in which the calibration jaws  57  extend away from the free end face of the base part  49  and are in contact with each other. The base part  49  includes a drive  53  for moving the calibration jaws  57  from the open position to the closed position and vice versa. A semicircular recess  59  each is formed in the one side surfaces of the calibration jaws  57  facing each other in the closed position of the calibration jaws  57 , which semicircular recesses  59  in conjunction form a circular receiving opening  55  for the hose  32  in the closed position of the calibration jaws  57 . Preferably, the diameter of the receiving opening  55  is matched to the size of the neck of the container product  10  to be manufactured. 
     The other side surface, opposite from the one side surface with the recess  59 , of the respective calibration jaw  57  is flat and preferably has two ports  61  for a temperature control (not shown in the figures). The temperature control is used to cool the calibration jaws  57  to locally selectively cool the hose  32  and, if necessary, prevent undesirable sticking of the heat-softened hose  32  to the calibration jaws  57 . 
     The cutting device  16  is provided in the form of a cutting blade, which is aligned in parallel to the base plate  56  and the cutting edge  60  of which can be moved back and forth between the hose head  14  and the gripper device  20  transverse to the rail  50  and to the base plate  56  for separating the parison  22  from the hose  32  extruded by means of the hose head  14 , between the hose head  14  of the extrusion device  12  and, in particular the gripper jaws  34  of the first tongs  24 , of the gripper device  20 . The cutting blade can, for instance, have the form of a so-called hot knife or oscillate at an ultrasonic frequency. Such designs of the cutting blade  60  are known from the prior art, for which reason the respective design will not be discussed in more detail here. 
     Two stationary housing plates  62 , aligned in parallel to each other and aligned longitudinally with respect to the base plate  56  and extending away from the base plate  56  in the direction of the hose head  14 , are arranged at the end area, facing away from the drive  58  of the linear actuator  48 , of the base plate  56 . An extension  64  extending away from the base plate  56 , is provided at the edge area, facing away from the drive  58  of the linear actuator  48  and from the base plate  56 , of every housing plate  62 . In the area of the extension  64  of the housing plates  62  and in an edge area, facing the drive  58  of the linear actuator  48  and the base plate  56 , of the housing plates  62  a guide pin  66  extends between each of these housing plates  62  and is secured to each housing plate  62  at its two ends. 
     Two support plates  68 , through which the guide pins  66  pass and which are guided for motion along the guide pins  66 , are arranged between the housing plates  62  as tool carriers. The support plates  68  support the molding tool  18 , which has one pair of holding  70 , head  72  and forming jaws  74  each. Specifically, each support plate  68  bears a holding jaw  70 , a head jaw  72 , and a forming jaw  74  extending in pairs opposite from each other away from the facing sides  76  of the support plates  68  to each other. The respective holding jaw  70  is secured in the central area of the side  78 , facing away from the base plate  56 , of the support plates  68 . A part-circular recess  80  for holding the parison  22  is provided in each of the sides, facing each other, of the holding jaws  70 . First the head jaw  72  and then the forming jaw  74  adjoin the respective holding jaw  70  at the side  76  of every support plate  68  facing the other support plate  68 , in the direction of the base plate  56 . 
     In the edge area facing away from the base plate  56  and, viewed in the longitudinal direction, in the central area of the respective housing plate  62 , one support plate drive  84  each is secured at the sides  82  facing away from each other, of the housing plates  62 , which support plate drive  84  acts in a pressing or pulling manner on the support plate  68  adjacent to the respective housing plate  62 , such that the support plates  68  can be moved towards each other by means of the support plate drive  84  to close the molding tool  18  and away from one another to open the molding tool  18 . In an area of the support plates  68  projecting, with the exception of the extension  64 , beyond the housing plates  62  in a direction away from the base plate  56 , a respective head jaw drive  88  is secured at the sides  86 , facing away from each other, of the support plates  68 , which head jaw drive  88  acts in a pressing or pulling manner on the respective adjacent head jaw  72 , such that the head jaws  72  can be moved towards and away from each other independently of the holding  70  and forming jaws  74 . The direction of travel of the support plates  68  is aligned transversely to the direction of travel of the gripper device  20 . 
     The linear drive  48  can move the two tongs  24 ,  26  simultaneously from a preforming position, the position where the tongs  24 ,  26  take over the extruded hose  32 , to a transfer position, where the parison  22  is transferred into the opened molding tool  18 , and vice versa. 
     Cooling, heating, shielding and/or reflecting devices (not shown in the figures) may be provided along the travel path of the parison  22  for optionally controlling the temperature of all or part of the parison  22 , wherein a temperature sensor may be used to monitor the temperature of the hose  32  or parison  22 . The respective cooling device can be designed such that a cooling fluid, preferably gas, in particular air, is directed against the parison  22 . For cooling the parison  22 , the transport path of the parison  22  can be extended and/or the transport speed can be adjusted in accordance with the required cooling capacity, achieving natural cooling by radiation. The respective heating device can be designed as a radiation heating device, preferably based on infrared radiation. By heating different areas of the hose  32 , different wall thicknesses of the finished container product can be implemented. The shielding and reflecting devices (not shown) can each be formed as metal sheets. 
     Sensors, in particular optical sensors (not shown in the figures) can also be provided on the gripper device  20  or along the travel path of the parison  22  for checking the parison  22 , for instance with regard to its geometry, its dimensions, its transparency, its wall thickness distribution, its temperature (distribution), its degree of crystallinity, its weight, for impurities and/or for particle inclusions, wherein the measured values of the respective sensor can be incorporated into a corresponding control of the extrusion process. 
     protection devices (not shown in the figures) may be provided to protect the parison  22  during transport. For instance, a protection device to protect against contamination, in particular microbial and/or particulate contamination, can be designed in such a way that it directs a flow of clean, sterile air, i.e. low in particles and germs, and/or filtered air or inert gas towards the inner and/or outer surface(s)  90  of the parison  22  during the traversing motion of the parison  22 . 
     Treatment devices not shown in the figures, can be provided along the travel path of the parison  22  for improving its properties, in particular for the selective modification of its surfaces  90 , which treatment devices are used to treat the inside and/or outside surfaces  90  of the parison  22  using a fluid. The treatment device can be set up in such a way that it directs a flow of fluid towards the parison  22 . The use of a reactive fluid, such as a fluorine-containing gas, permits the selective modification of the inner and/or outer surfaces  90  of the parison  22 , resulting in an improvement in the barrier properties of the polymer used to produce the parison  22 . When surface  90  is treated with gas mixtures containing siloxane, such as hexamethyldisiloxane (HMDSO) or 1,1,1,3,3,3-hexamethyldisilazane (HMDS), inerting occurs and wetting properties are altered. Surface modifications have been shown to occur at parison  22  temperatures in the range of 150 to 250° C., depending on the polymer, without the need for additional measures typical of coatings, such as heating or plasma treatment. 
     The method according to the invention is explained in more detail below: 
     First, the hose head  14  of the usual extrusion device is used to extrude  12  the hose  32  in the vertical extrusion direction (z-direction), resulting in the former being arranged in a preforming position ( FIG.  1   ). At the same time, the tongs  24 ,  26  are open. 
     If possibly the stationary calibration element  51  ( FIGS.  2 ,  5   ) is provided for a calibration by sections of the outer diameter of the heat-softened hose  32  in the preforming position, the calibration element&#39;s calibration jaws  57 , which are also open, are first closed in a spaced-apart, encompassing manner around the hose  32  ( FIG.  7   ). The supporting gas pulse directed into the interior of the hose  32  causes the hose  32  to contact the two calibration jaws  57  of the calibration element  51  and thus determines the outer diameter of the heat-softened hose  32  in the contact area. 
     Thereafter or simultaneously, the respective tongs drive  42 ,  44  is used to close the tongs ( FIG.  4 ,  7   ). In this way, the lower tongs  26  seal the hose  32  and hold it at its lower end area, whereas the gripping jaws  34  of the closed upper tongs  24  only surround the heat-softened hose  32  at its upper end area in an encompassing manner, but do not touch it. The supporting gas pulse or a further supporting gas pulse now expands the hose  32  in the area of the upper tongs  24 , puts it against the gripper jaws  34  and holds it at the slots  40  by negative pressure. The vacuum is generated by a vacuum pump (not shown in the figures), which is connected by means of a channel (not shown) extending through the respective leg  28 . Surprisingly, this permits keeping even large openings  92  ( FIG.  10   ) with a diameter of up to about 6 cm open in a stable manner, allowing for a fast and thus cost-efficient filling using a correspondingly large filling mandrel  100  ( FIG.  10   ). 
     If the calibration element  51  is provided, the calibration jaws  57  of the calibration element  51  are opened by means of the pneumatic actuator  53  after the hose  32  is in contact with the gripping jaws  34  of the first tongs  24 . Thus, by means of the calibration element  51 , the forming operation is performed in two distinct, regarding time and location, steps: In a first step, the calibrating element  51  shapes the hose  32  in the preforming position before it is cut off and, in a second step, after the parison  22  has been introduced into the actual molding tool  18  in the transfer position. Furthermore, according to the invention, the calibration element  51  manages to cool the hose  32  in the contact area of the calibration jaws  57 , which are cooled by means of the temperature control and in this way to specifically stabilize the shape of the hose  32 . 
     Subsequently, the hose  32  is severed between the hose head  14  and the gripper device  20  to form an opening  92  at its upper end, thereby cutting the parison  22  off from the hose  32 . 
     Then, the gripper device  20 , which holds the parison  22  open on one side in a vertical orientation, transports the parison  22  by means of the linear drive  48  starting from the preforming position in a linear transport direction along the rail  50  of the linear drive  48  into the opened molding tool  18 , in which the parison  22  is arranged in a main molding position ( FIG.  8   ). 
     Optionally, this motion first is downwards in the vertical direction (z-direction) and then transversely to the stationary mold in the transfer position. 
     First, the lower tongs  26  are opened and the support plate drive  84  is used to close the support plates  68 , in particular the head jaws  72  are carried along by the support plates  68  and the holding  70  and forming jaws  74  are closed for the holding  70  and forming jaws  74  to hold the parison  22  therebetween ( FIG.  9   ). In this process, the forming jaws  74  weld the underside  94  of the parison  22  shut. Thereafter, opening of the upper tongs  24  completes the transfer of the parison  22  from the gripper device  20  to the molding tool  18 . The largely freely accessible arrangement of the parison  22  during the traversing motion makes it accessible for further method steps. 
     Subsequently, a usual blow molding, filling and sealing process is performed on the parison  22 . Thus, the forming jaws  72  are used to first blow mold the container body  96  of the container product  10  using a blow molding assembly  98  ( FIG.  10   —step  2 ). Subsequently, a filling device  100  ( FIG.  10   —step  3 ) fills the container body  96  with filling material via the opening  92  of the container body. Then, the respective head jaw drive  88  is used to close the head jaws  72  of the molding tool  18 , thereby forming a head part  102  of the filled container product  10 , namely the head part  102  is sealed towards the outside ( FIG.  10   —step  4 ). Because every head jaw  72  can be closed by means of a head jaw drive  88  in the form of a hydraulic cylinder and each mold jaw  74  can be closed by means of a support plate drive  84  in the form of a further hydraulic cylinder, the blow molding and filling process can be performed at a particularly high pressure. 
     Afterwards, the gripper device  20  is transported back along the rail  50  into the extrusion position and simultaneously opened for a renewed sequence of the preceding method steps. Finally, the forming  74 , head  72  and holding jaws  70  ( FIG.  10   —step  5 ) are retracted, thereby removing the finished container product  10  from the molding tool  18 ; this step can also be performed using an additional manipulator, such as a robotic arm. 
     Optionally, it is possible—as detailed in DE 10 2014 008 611 A1—to introduce an insert into the upper part of the container product  10  between filling ( FIG.  10   , step  3 ) and sealing of the container product  10  ( FIG.  10   , step  4 ). 
     Optionally and simplifying, it is further possible to make one of the forming jaws  74  stationary by securing it to the base plate  56  and moving only the other forming jaw  74 , thereby minimizing the number of support plate drives  84 . Such a one-sided closing motion requires that the parison is always located in the center between the two forming jaws  74 , which is made possible by a transverse motion of the gripper device  20  that is easy to implement. 
     Optionally, and in a considerably simplifying manner, the holding jaws  70  as part of the molding tool  18  can also be dispensed with, and the upper tongs  24  of the gripper device  20  can take over a holding function, wherein the parison  22 , even while it is already at least partially located in the molding tool  18 , is held by the upper tongs  24  of the gripper device  20  by a pressure gradient at least until the start of its further forming, which is easy to implement in terms of control technology. 
     Further advantageously, the container product  10  can be removed towards the top, which according to the invention is rendered possible by the space above the mold being empty, i.e., it is not occupied by the hose head  14  of the extrusion device  12 . 
     Advantageously, as already mentioned, the gripper device  20  and with it the parison  22  can initially be moved in the vertical direction (z-direction) after separation. This renders—while maintaining continuous extrusion of a hose  32 —dispensing with the technically complex tilting motion of the extruder, which is customary in the prior art and results in a vertical motion of the hose head  14  possible. For this purpose, the parison  22  is moved downwards in the extrusion direction (z-direction) with the aid of the gripping assembly  20  after the parison  22  has been separated from the hose  32  and before it is transported transverse thereto to the main forming position. 
     The gripper device  20  according to the invention having its two tongs  24 ,  26 , has proved to be very advantageous, particularly for transporting parisons of low weight. Whereas in the case of parisons  22  weighing more than approx. 0.1 kg during transport, holding them by only the upper tongs  24  is often sufficient for stable production processes resulting in low rejection numbers, in the case of lightweight parisons  22  for the production of lightweight containers weighing less than approx. 0.06 kg, and in the case of multiple hose heads using a plurality of tongs  24 ,  26  in accordance with the invention is advantageous for securing purposes. 
     The lightweight containers produced in this way—such as bottles or ampoules—can preferably be used for medical purposes, for instance for infusion solutions, inhalatives, ophthalmics, injectables or diagnostics and oral tonics.