Abstract:
A device for transforming plastics preforms into containers includes at least one blow mold for receiving the plastics preforms. The blow mold has two mold parts, which can be pivoted with respect to each other about a connecting axis, with at least one locking element, which is arranged on one of the mold parts and interacts with at least one counter element arranged on the other mold part, in order to lock the two mold parts with respect to each other. The counter element is arranged about an axis arranged substantially parallel to the connecting axis and can be turned between a locking position, and an unlocking position. The device has an actuating element for turning the counter element, having a drive element which interacts with the counter element to actuate it.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for moulding plastic preforms into plastic containers. Such apparatus have been known from the prior art for a long time and usually include a plurality of blow stations, with blow moulds being arranged at these blow stations, on the inside of which the plastic preforms are arranged so as to be expanded into plastic containers for example by means of pressurised air. 
     Blow moulds of this kind usually have two mould halves that can be opened and closed so as to receive the plastic containers on the inside thereof. 
     During the actual expansion process, these mould halves are locked against each other, so that they cannot come open during the actual moulding process. 
     From U.S. Pat. No. 7,384,261 B2, a blow moulding apparatus for producing thermal plastic containers is known. In this apparatus, a locking mechanism for locking two blow mould halves against each other is provided. This locking mechanism has here a locking member which can be pivoted about an axis. Further, a cam mechanism may be provided in order to activate this locking mechanism. 
     From DE 42 12 583 A1 an apparatus for blow moulding is known. This apparatus also has mould carriers as well as a locking unit for locking these two mould carriers. Here, an adjustment element is provided which is guided substantially in the direction of a centre line of the blow mould. 
     DE 692 04 407 T2 describes an apparatus for opening and closing a divided mould. Here again, two mould halves are provided which can be pivoted relative to each other. Further, this apparatus includes two actuating arms which are fixed to the two mould halves at one of their ends so that they can rotate freely. 
     EP 1 276 598 B1 also describes a blow mould and a blow moulding machine. In this blow moulding machine, a shaft for locking and unlocking the respective mould halves is provided, said shaft having an external contour such that the shaft rests in a locking position at least partially on a locking element and in an unlocking position releases said locking element. 
     The content of the above-mentioned EP 1 276 598 B1 is herewith enclosed in its entirety by reference in the subject matter of the present application. 
     SUMMARY OF THE INVENTION 
     The present invention is based on the task of simplifying the actuation of a corresponding locking mechanism and to enable in particular also a rapid, reliable and accurate locking and unlocking operation. 
     An apparatus according to the invention for moulding plastic preforms into containers includes at least one blow mould for receiving the plastic preforms. This blow mould includes here at least two mould parts which can be pivoted relative to each other about a connection axis as well as at least one locking element disposed on one of the mould parts, said locking element cooperating with at least one counter element disposed on the other mould part so as to lock the two mould parts against each other. The counter element is here a counter element that can be rotated about an axis arranged parallel to the connection axis, which counter element can be rotated between a locking position in which the blow mould is locked and an unlocking position in which the blow mould can be opened, said counter element being designed in such a way that the counter element rests in the locking position at least partially on the locking element and in the unlocking position releases the locking element. 
     According to the invention, the apparatus includes an actuating element for rotating the counter element, said actuating element including a drive element which cooperates with the counter element so as to actuate the latter. 
     The counter element is preferably a shaft and this shaft has an external contour such that the counter element rests in its locking position at least partially on the counter element and in the unlocking position releases the locking element. However, it would also be possible for the counter element to include a plurality of hooks which are pivoted by the rotation of the counter element and which engage in a locking area of the respectively other mould part so as to lock the mould parts against each other. The mould parts are preferably half-shells which in the assembled condition receive a preform or a plastic container. 
     Advantageously, a drivable element is disposed on the counter element, which has a guiding surface that cooperates with a guiding protrusion movable relative to the counter element in such a way that this relative movement of the guiding protrusion in relation to the guiding surface causes a rotation of the counter element. The guiding protrusion is here preferably arranged to be stationary and the counter element moves relative to this guiding protrusion. In this way, a movement of the entire blow mould can be translated into a rotary movement of the counter element. 
     This guiding surface is preferably curved at least in sections. In this connection, a radius of curvature of this guiding surface particularly preferably deviates from a radius of curvature of a movement path of the blow mould, so that in this way the counter element or the shaft can be swung in. 
     In a further advantageous embodiment, a bevel gear is arranged at least on the counter element or on the actuating element. The bevel gear is preferably provided here on the end of the counter element. 
     This bevel gear preferably cooperates with a further bevel gear arranged on the actuating element or on the counter element so as to rotate the counter element. Due to the use of bevel gears, a drive shaft can be inclined in relation to a longitudinal direction of the movement element or the rotary axis thereof, and in this way, as will be shown with reference to the figures, the movement can be translated in a particularly advantageous manner. 
     Preferably, the further bevel gear is arranged on a lever that can be pivoted about an axis of the further bevel gear. As a result of a pivoting action of this lever, the further bevel gear is thus rotated and thus also the first-mentioned bevel gear and thus also the movement element are rotated. Preferably, this lever can be pivoted here in a vertical plane. 
     In a further advantageous embodiment, the actuating element includes engagement means cooperating with a thread provided on the movement element so as to cause the rotation thereof. This thread is preferably a coarse thread, so that as a result of a longitudinal movement a rotation of the movement element is generated. Conversely, an engagement element could also be provided on the movement element, which engagement element cooperates with a thread of the actuating element. A thread could also be provided both on the movement element and on the actuating element. The engagement means mentioned could engage here in a winding of the thread of the respectively other element. 
     Preferably, the actuating element mentioned can be moved in the direction of the rotary axis of the actuating element. As a result of this longitudinal movement, as mentioned above, a rotation of the movement element is caused. 
     In a further advantageous embodiment, the thread is an external thread. This means that an external thread is provided on the movement element, which external thread is engaged by a protrusion of the actuating element. The movement element or the thread can be fed through an opening of the actuating element, on the inner surface of which the engagement means are disposed. In this connection, the engagement element can be formed as a tip. 
     In a further advantageous embodiment, the apparatus includes a guiding rod extending parallel to the movement element for guiding a movement of the actuating element. In this way, a reliable guidance of the actuating element can be achieved even in the case of the rapid movements involved. The actuating element is preferably moved by a guide curve which is arranged to be stationary. However, it would also be possible for a guide roller to be provided in order to simplify the movement. 
     In a further advantageous embodiment, the actuating element has a plate-shaped body that is arranged to be movable relative to the movement element and that has a recess, into which at least one section of the movement element protrudes. In this embodiment, a sliding guide is provided as the actuating mechanism, in which sliding guide the movement element is guided and is at the same time rotated in a defined manner. 
     This plate-shaped body can therefore preferably be pivoted about a pivot axis that is parallel to the rotary axis of the movement element, but which does not coincide with this rotary axis. 
     In a further advantageous embodiment, the drive element cooperates with an end-side driven element disposed in the counter element. 
     In a further embodiment, a first guiding body is disposed on the counter element, and a second guiding body is disposed on the actuating element, said first guiding body being displaceable relative to the second guiding body, and as a result of a displacement of the first guiding body relative to the second guiding body, a rotation of the counter element is achieved. Preferably, one of the two guiding bodies is a guiding groove, into which the other guiding body, which is preferably formed as a protrusion or a roller, engages. 
     As a result of a displacement of the protrusion relative to the groove, also a rotation of the counter element is achieved. Preferably, the groove is formed on the counter element and the protrusion is formed on the actuating element. Thus, it would be possible, for example, for the actuating element to be a lever that can be pivoted about a predefined axis, on which the protrusion or the roller engaging in the groove is formed. 
     The present invention further relates to a blow mould, in particular for an apparatus for moulding plastic preforms into plastic containers, said blow mould including two mould parts which can be pivoted relative to each other about a connection axis, and at least one locking element disposed on one of the mould parts, which locking element cooperates with at least one counter element disposed on the other mould part so as to lock the two mould parts against each other. The counter element is here a counter element that is disposed parallel to an axis arranged on the connection axis, and this counter element can be rotated between a locking position in which the blow mould is locked and an unlocking position in which the blow mould can be opened, said counter element being designed in such a way that the counter element in its locking position rests at least partially on the locking element and in its unlocking position releases the locking element. 
     According to the invention, an actuating element for rotating the counter element is provided, said actuating element including a drive element that cooperates with the counter element so as to actuate the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantageous embodiments will become evident from the attached drawings, wherein: 
         FIG. 1  shows a view of a blow mould; 
         FIG. 2  shows a schematic view for illustrating a locking mechanism according to the invention; 
         FIG. 3   a  shows a schematic view for illustrating a locking mechanism according to the invention in a first embodiment; 
         FIGS. 4   a - 4   g  show various views for illustrating a locking mechanism in a second embodiment; 
         FIGS. 5   a - 5   f  show views of an apparatus according to the invention in a third embodiment; 
         FIGS. 6   a - 6   h  show views of an apparatus according to the invention in a fourth embodiment; 
         FIGS. 7   a - 7   b  show views of an apparatus according to the invention in a fifth embodiment; and 
         FIGS. 8   a - 8   d  show views of an apparatus according to the invention in a sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a partial view of a blow mould. This blow mould  1  includes two mould halves  3 ,  4  that can be rotated about a connection axis  2  and that are used as mould carriers, more specifically a first mould half  3  and a second mould half  4 . These two mould halves  3 ,  4  are designed in such a way that they form an inner cavity  5  in their closed condition, in which a preform (not shown) can be blow moulded, which means contoured, by means of mould inserts (not shown) in a stretch blow moulding process. 
     In order to close the two mould halves  3 ,  4 , these are pivoted about the connection axis  2  in such a way that their lateral surfaces abut against each other.  FIG. 1  shows a closed locked condition of the two mould halves  3 ,  4 . Reference numeral  10   a  refers to a movement element that can be rotated so as to lock the two mould halves  3 ,  4  to each other. 
       FIG. 2  shows a top view onto a central area for illustrating the locking element. Here, too, the movement element  10   a  is provided which is implemented as a shaft which in turn has a recess  12 . Reference numeral  9  relates to a locking element which may be inserted along the arrow A between the movement element  10   a  and a further movement element  10   b  which is formed symmetrically in relation to the movement element  10 . The two movement elements  10   a ,  10   b  can be rotated here about the axes Y, Y′. 
     In order to lock the locking mechanism, the movement element  10   a , that is the shaft  10 , is rotated about a predefined angle, so that a contour  15  engages in a recess  13  of the locking element  9 . Correspondingly, also an area of the movement element  10   b  engages in the corresponding lower area or the recess  13  of the locking element  9 . 
     A rotary movement of the movement element  10   b  is preferably coupled with a rotary movement of the movement element  10   a . In this embodiment therefore two shafts  10   a ,  10   b  are attached to the mould part  4 , which two shafts can be rotated about a longitudinal axis extending therethrough between the locking position and the unlocking position. The locking element  9  may, in the unlocking position, be at least partially guided through between the shafts  10   a ,  10   b , and in the locking position, the contours  15  of the two movement elements or shafts  10   a ,  10   b  rest at least partially against the locking element  12  in such a way that the blow mould  1  is firmly locked. 
       FIG. 3   a  shows a first embodiment of an apparatus according to the invention. What can be seen here again is the movement element  10   a  which includes the recess  12  already mentioned in  FIG. 2 . This movement element  10   a , i.e. the shaft, can here be rotated about the arrow P 1  so as to cause the blow mould to be locked or unlocked. To this end, a drivable element  22  is fixedly disposed on the movement element  10   a , which drivable element  22  has a guiding surface  23  opposite of which a guiding protrusion moves. 
     More specifically, this is here not a guiding protrusion, but a rotatable guiding roller, so as to minimise any frictional losses in this way. During operation of the apparatus, the blow mould and thus also the actuating element  10   a  moves along a circular path which is usually determined by the pitch circle radius of a corresponding carrier on which a plurality of blow moulds is arranged. During this circular movement, the guiding surface  23  is lead past the protrusion  24 , and in this way the movement element  22  is rotated in a predefined manner along the arrow P 1 . This rotation again causes the blow mould to be locked or unlocked. In the terminal areas  28 , the drivable element respectively includes rounded surfaces, so that the locking or unlocking operation runs smoothly. 
     During a movement of the movement element relative to the guiding protrusion  24  in a specified direction, the blow mould is either locked or unlocked. The respectively inverse process, i.e. the unlocking or locking, is enabled by a further guiding surface on the rear side of the drivable element  22 . However, it would also be possible to cause a reverse rotation of the movement element  10   a  through other mechanisms such as for example spring mechanisms. Here, too, it would also be possible for a corresponding drivable element to be arranged on the second movement element  11  (cf.  FIG. 2 ), and this further drivable element would be provided for the respectively inverse process, that is the unlocking or locking. 
       FIG. 4   a  shows a further embodiment in an apparatus according to the invention. In this case, again a guiding unit  39  in the form of a guiding wheel is provided, and this guiding wheel actuates a lever  36  which in turn is arranged on a carrier  37  which is stationary relative to the blow mould  1 .  FIG. 4   b  shows a detailed view of the apparatus shown in  FIG. 4   a . In this case, a first bevel gear  32  is provided on the movement element  10 , which cooperates with a second bevel gear  34  arranged on the lever  36 . 
     Thus, by pivoting the lever  36  about the axis of the second bevel gear  34 , the movement element  10  is rotated in a predefined manner as a function of a pivot angle. At the bottom end, the lever  36  includes again a guiding surface  38  which cooperates with the above-mentioned guiding unit  39  or the wheel. By means of a movement element  10  opposite the wheel  39 , a pivoting action of the lever is achieved. Corresponding guide rollers, on which the wheel  39  is arranged, could however also be implemented in a manner different to the one illustrated. 
       FIGS. 4   c  to  4   e  show further views of the locking mechanism according to the invention. In particular, also the lever  36  is shown here in several perspective views. At the bottom end of the lever  36 , said guiding surface  38   a  as well as a further guiding surface  38   b  are arranged here. By means of these two different guiding surfaces, with the aid of correspondingly arranged guiding cams, both a pivoting of the lever towards the left in  FIG. 4   a  and a pivoting of the lever towards the right in  FIG. 4   e  may be achieved. However, it would also be possible for the lever  36  to be pivoted back due to its own weight. However, here too, a spring could be provided for returning the lever. This spring could be provided for example between the carrier  37  and the lever  36 , but also in an area of the movement element. 
       FIGS. 4   f  and  4   g  show a further modified embodiment of an apparatus according to the invention. Here, too, a pivotable lever  36  is provided, at the bottom end of which, however, a gear  35  is arranged which is movable relative to a guide curve  30 . As shown in  FIGS. 4   f  and  4   g , a movement of the movement element  10  along the arrow P can also cause a movement of the gear  35  along the arrow P relative to the guide curve  30 . 
     In this way, the lever  36  is pivoted in a clockwise direction, and as a result also the movement element  10  is rotated. To pivot the lever  36  back it is possible for the guide curve  30   a  to sink back again and thus also the lever  36  can swing back with a movement of the movement element  10  in a clockwise direction, and in this way the movement element  10  is again rotated in an exactly predefined manner. The angle of rotation, about which the movement element  10  is rotated, is thus determined by the height difference between the area  30   b  and  30   a  of the guide curve  30 . Preferably, however, a further guiding level (not shown) is provided, which is here provided above the gear  35  and which sinks down in the directions of movement of the lever. 
     The bevel gear  34  is here arranged in a take-up shaft (not shown), wherein also support means or intermediate shafts can be provided for guiding the lever  36 . The cam roller  35  is here also preferably supported in a rotatable manner. 
       FIGS. 5   a  to  5   f  show a further embodiment of an apparatus according to the invention. 
     In this embodiment, an actuating element  20  is provided which can be moved upwards and downwards in the direction of the axis Y, which means along the arrow P 2 . Here, a thread  42  of the movement element  10   a  is guided through this actuating element  20 , and during a movement of the actuating element  20 , a rotation of the movement element  10   a  is caused in this way. The thread  42  is preferably a coarse thread, so that a rotation as a result of a displacement of the actuating element  20  is facilitated. Similar to the embodiment shown in  FIGS. 4   e  to  4   f , here, too, a cam roller  45  is provided which is moved relative to a guide curve  40 , in order to lift the actuating element. A further guiding level (not shown) may be provided for lowering the cam roller. 
     Reference numeral  46  relates to a further rod which is here used as a twist protection or as a control lever. In this way it is prevented that the actuating element  20  rotates about the thread  42 , or the longitudinal direction along the arrow P 2  is secured by means of this rod  46 . It would be possible here for the rod  46  to be arranged rigidly on the blow mould  1  and to extend through a hole  47   a  of the actuating element  20 , and thus the actuating element  20  would be movable relative to the rod  46 . It would however be possible for the rod  46  to be arranged on the actuating element  20  in a fixed manner and to be arranged again on the blow mould  1  so as to be displaceable in the longitudinal direction. Reference numeral  48  relates to a housing or a receptacle that can be used, amongst other things, also for supporting the rod  46 . 
     Inside of the actuating element  20 , either an internal thread or a tapering body  49  may be provided here, which engages in the thread  42  and thus causes, in the case of a relative movement of the actuating element  20  along the arrow P 2 , a rotation of the movement element  10 . At the bottom end of the movement element, a stop  47  may be provided which delimits the relative movement of the actuating element relative to the movement element  10  towards the bottom. 
     In the situation shown in  FIG. 5   d , the actuating element  20  is largely lowered so that the thread area  42  extends above the actuating element. In the situation shown in  FIG. 5   a , the actuating element is lifted, so that the thread  42  protrudes out of the actuating element  20  towards the bottom. 
     In  FIG. 5   f , a further termination element  47  is provided which is arranged at the bottom end of the thread and which delimits a movement of the thread  42  relative to the actuating element, so that the actuating element  20  cannot fall off the thread. 
       FIGS. 6   a - 6   h  show a further embodiment of the present invention. In this case, the movement element  10   a  extends through the actuating element  20  or through an adjustment lever  62  of this actuating element  20 . To this end, the actuating lever  62  has an opening  64  which is here formed like a slot that accommodates the movement element  10   a . Below this adjustment lever  62 , a connection member  66  is provided, which is on the one hand formed in a manner to be rotationally fixed to the movement element  10   a  and on the other hand includes a pin  68  that protrudes through a further opening  69  into the adjustment lever  62 . This adjustment lever is here arranged to be pivotable about a rod  65  or the rotary axis thereof. Reference numeral  67  again identifies a guide curve of the adjustment lever  62 . 
     Reference numeral  63  relates to a guide roller that causes a pivoting of the adjustment lever  62 . Thus, as a result of a specific pivoting of the adjustment lever  62 , a likewise defined rotation of the movement element  10   a  can be achieved. 
       FIGS. 6   e - 6   h  illustrate a corresponding rotation of the movement element  10   a , which is caused by a pivoting of the adjustment lever  62 . It can be seen that the adjustment lever  62  can be pivoted about an angle δ 1 . However, a pivot action about this angle δ 1  causes on the other hand, due to the interplay of the two openings  64 ,  69 , a pivoting of the movement element  10  about the angle δ 2 , which is here larger than said angle δ 1 . As a result, a smaller adjustment angle is required in order to achieve a correspondingly higher rotatory movement of the movement element  10   a . The relationship between the two angles δ 1  and δ 2  can be adjusted via the radii R 1  and R 2  or the relationship between them as shown in  FIGS. 6   g  and  6   h  relative to one another. 
       FIGS. 7   a  and  7   b  show a further embodiment of the mechanism according to the invention. This embodiment is similar to the embodiment shown in  FIG. 3   a , but here the movement element  10   a  is designed in a different way. Here, the movement element  10   a  has three engagement elements  72  which in a locking condition engage in the locking body  9 . The actuation of the movement element  11  shown here, however, is carried out in the same way as illustrated with reference to  FIG. 3   a . A person skilled in the art will recognise that the other movement mechanisms which are also shown in the figures can be applied to the movement element  11 . 
       FIGS. 8   a - 8   d  show a further embodiment of a mechanism according to the invention. Here, again, a cam roller  85 , or more specifically a double cam roller  85 , is provided which extends along a curved path (not shown). A lever  86  is disposed on this cam roller, which is rotated as a result of a movement of the cam roller. An engagement element is fixedly disposed on this lever  86 , and this engagement element causes a pivoting action of the counter element  10   a  about the axis Y. 
     As a result of a pivoting action of the counter element  10   a , an engagement between the hook  82  and corresponding counter hooks  81  can be achieved or released.  FIG. 8   c  shows this engagement mechanism in more detail. The lever  86  is, as said above, pivotably arranged on a fixed support  84 . Further, an engagement body, or more specifically, a roller  89  disposed on a roller support  87 , is provided on the lever  86 , which roller  89  extends in a groove  88  that is formed on or in the counter element  10   a . This groove  88  is here a three-dimensional groove and a movement of the roller  89  within this groove leads to a pivoting action of the counter element  10   a  about the axis Y. It can be seen that the groove has a curved path and that the roller can roll in this groove  88  without tilting. Preferably, a groove width of the groove  88  will be slightly bigger than a diameter of the roller  89 . It would also be conceivable for the roller  89  to be implemented as a double roller in order to prevent a rotation of the roller  89  in two rotary directions, which may occur depending on the load situation, in order to reduce wear on the roller  89  and the groove  88 . 
     The other hook or the locking element  9  cannot be pivoted in the embodiment shown in  FIGS. 8   a - 8   d ; however, it would also be possible to pivot both hooks for opening or closing the blow mould. Thus, in this embodiment a cam for opening and closing the blow mould is directly integrated in the counter element. The cam for moving the roller  85  in turn is controlled by a cam which is fixed relative to the machine, when the blow stations pass this cam during their circular movement. It would further also be conceivable for a slide coupling to be integrated into the course of movement between the lever  86  and the support  84 , so that it would be possible to respond to any jamming of the hooks  82  and  81 . 
     In a further embodiment it would also be possible to provide a spur gear on the movement element  10  or  11 , which spur gear cooperates with a further spur gear acting as an actuating element, in order to achieve a rotation of the movement element. In this connection, another lever could be arranged in a further toothed gear or spur gear, which lever would be pivoted by a guide curve so as to achieve in this way a rotary movement of the movement element. 
     By means of corresponding size relationships between the two spur gears it can thus be established at which degree of pivoting of said lever, which rotary angles of the movement element can be achieved. 
     All of the features disclosed in the application documents are claimed as being essential to the invention in as far as they are novel over the prior art either individually or in combination.