Abstract:
An apparatus and method for the production of plastic containers, in particular, plastic tanks, for example, fuel tanks for motor vehicles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority 35 U.S.C. §119 to European Patent Publication No. EP 13162273.0 (filed on Apr. 4, 2013) which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     Embodiments relate to an apparatus and method for the production of plastic containers, in particular of plastic tanks, for example, fuel tanks for motor vehicles. 
     BACKGROUND 
     For the production of plastic containers, in particular plastic tanks, it is known to employ the method of thermoforming and, correspondingly, thermoform pressing. Further, what may be referred to as double-ply thermoforming or double-mould thermoforming is known, in which plastic half-shells are simultaneously thermoformed in two moulds and are subsequently welded to one another in the hot and pasty state at their margins to form a hollow body. 
     A method for the double-ply thermoforming of plastic fuel tanks and an apparatus for the production of plastic fuel tanks are known from WO Patent Publication No. WO 2004/062889 A1, two heated plastic plies being moved independently of one another to a thermoforming station, the individual plastic plies being lowered into a first and a second shaping die, the first and the second die being arranged laterally next to one another, each plastic ply being thermoformed into a shell, and one of the shaping dies, together with the thermoformed shell, being overturned and arranged above the other die, and, finally, overlapping sealing regions of the shells being pressed together and being thermally fused. 
     European Patent Publication No. EP 1 314 528 A2 discloses a thermoforming press for the production of formed parts, comprising a mould supporting table, which is suspended on a frame beneath a forming-die subassembly, and a pair of moulds which are mounted side to side on the mould supporting table, means being provided for pivoting the said mould supporting table along an arcuate reciprocating path and for alternately aligning and registering one of the said moulds and then the other of the said moulds with the forming-die subassembly. 
     SUMMARY 
     Embodiments relate to an enhanced apparatus and method for the production of plastic containers, as a result of which, in particular, the throughput may be increased and at the same time it becomes possible for the apparatus to have a compact construction. 
     In accordance with embodiments, an apparatus for the production of plastic containers includes at least one of: a first press platen with a first mould half and a pivoting arm with a second mould half to accommodate heated and thermoformed plastic half-shells, a second press platen with a third mould half and the pivoting arm having a fourth mould half to accommodate heated and thermoformed plastic half-shells, wherein in a first position of the pivoting arm spatially above the first press platen, the first mould half and the second mould half open towards one another such that, by the first mould half being pressed onto the second mould half, the plastic half-shells accommodated therein may be welded to one another at overlapping margins, wherein in a second position of the pivoting arm spatially above the second press platen, the third and the fourth mould half being opened towards one another, so that, by the third mould half being pressed onto the fourth mould half, the plastic half-shells accommodated therein may be welded to one another at their overlapping margins. 
     In accordance with embodiments, a method for the production of plastic containers includes at least one of: introducing heated plastic plates in a first upwardly open mould half arranged on a first press platen and a second upwardly open mould half the second mould half arranged on a pivoting arm; thermoforming the heated plastic plates into first and second plastic half-shells; after thermoforming, manipulating the pivoting arm to a first position spatially above the first press platen such that the first mould half and the second mould half are open towards one another; pressing the first mould half onto the second mould half; welding the first and second plastic half-shells to one another at overlapping margins thereof; introducing heated plastic plates in a third upwardly open mould half arranged on a second press platen and a fourth upwardly open mould half arranged on the pivoting arm; thermoforming the heated plastic plates into third and fourth plastic half-shells; after thermoforming, manipulating the pivoting arm to a second position spatially above the second press platen such that the third mould half and the fourth mould half are open towards one another; pressing the third mould half onto the fourth mould half; and welding the third and fourth plastic half-shells to one another at overlapping margins thereof. 
     In accordance with embodiments, there is provision for using two press platens on which a mould half is arranged in each case. The two associated mould halves which complete the mould halves on the press platens are arranged on a common pivoting arm. Thus, by way of a single pivoting movement of the pivoting arm, a pair of moulds, for example, a first and a second mould half, may be moved spatially closer to one another and be brought into a position for welding, and at the same time a second pair of moulds, for example, the third and the fourth mould half, may be opened in order to extract the welded container. Thus, also, while one pair of moulds is closed and the welded container cools therein, heated plastic plates may be introduced simultaneously into the mould halves of the other pair of moulds and be thermoformed into plastic half-shells. 
     In accordance with embodiments, any combination of the first mould half, the second mould half, the third mould half and the fourth mould half comprises a thermoforming station, so that a heated plastic plate may be introduced into the respective mould half and the plastic half-shell is thermoformed out of the plastic plate in the respective mould half. 
     In accordance with embodiments, the thermoforming stations comprises vacuum thermoforming stations, so that the plastic plates are drawn into the respective mould halves by a vacuum. 
     In accordance with embodiments, the second mould half and the fourth mould half may be arranged on opposite sides of the pivoting arm, so that the orifices of the mould halves in each case point away from the pivoting arm. The pivoting arm may then be mounted approximately in the middle between the first press platen and the second press platen and may be pivoted vertically through about 180 degrees between the first position and the second position. 
     In accordance with embodiments, the pivoting arm may comprise, for example, a vertical immovable pivoting-arm pillar and a pivotable pivoting table which is mounted on and/or over the pivoting-arm pillar and which carries the second and the fourth mould half. In the context of embodiments, a pivoting movement of the pivoting arm may comprise a pivoting movement of the pivotable pivoting table of the pivoting arm. 
     In accordance with embodiments, the pivoting arm may be pivoted between the first position and the second position by way of a geared motor or by way of a hydraulic motor. 
     In accordance with embodiments, the pivoting movement of the pivoting arm may be assisted by a device which utilizes the weight of the pivoting arm for lifting the pivoting arm. This may, in particular, be a spring device or a hydraulic device which is pre-stressed in the lifting direction as a result of the lowering of the pivoting arm. 
     In accordance with embodiments, the press of the first press platen and/or of the second press platen may be operated mechanically, hydraulically and/or hydro-pneumatically. In particular, one or both presses may be operated at least in two stages, for example, in a first, high-speed phase with a higher closing speed and lower closing force, and in a second, force phase with a higher closing force. In this case, for example, the high-speed phase may be driven mechanically and the force phase hydraulically. 
     The method for the production of plastic containers in accordance with embodiments may include, drawing via a vacuum the plastic plates in at least one of the first mould half, the second mould half, the third mould half and the fourth mould half for thermoforming into the respective mould halves. 
     In accordance with embodiments, the plastic plates may be introduced into the first and the second mould half, and also thermoformed while plastic half-shells welded to one another cool in the third and the fourth mould half. Plastic plates may also be introduced into the third and the fourth mould half, and also thermoformed while plastic half-shells welded to one another cool in the first and the second mould half. Therefore, alternately, the plastic is prepared and thermoformed in one pair of moulds while a container cools in the other pair of moulds. 
     In accordance with embodiments, insert parts may be introduced into at least one of the first mould half, the second mould half, the third mould half and the fourth mould half after the thermoforming of the plastic half-shells and before the welding of the plastic half-shells in pairs. Insert parts may, for example, also be introduced into the plastic half-shells before thermoforming. 
     In accordance with embodiments, the pivoting arm or the pivotable pivoting table of the pivoting arm, which pivoting table carries the second and the fourth mould half, may be locked in its position before pressing, for example, mechanically, for example by way of a bolt which may be driven into a bore, by way of a paul or rotary latch, or else electrically, hydraulically or pneumatically, so that the locked pivoting arm may withstand the forces during pressing. 
     In accordance with embodiments, an apparatus for producing plastic containers may include at least one of: a first press platen including a pivoting arm, a first mould half and a second mould half arranged on the pivoting arm, the first mould half and the second mould half configured to accommodate heated and thermoformed plastic half-shells; and a second press platen including the pivoting arm, a third mould half and a fourth mould half arranged on the pivoting arm, the third mould half and the fourth mould half configured to accommodate heated and thermoformed plastic half-shells, wherein the pivoting arm is movable between a first position above the first press platen in which the first mould half and the second mould half are opened towards one another such that, by the first mould half being pressed onto the second mould half, the plastic half-shells may be connected to one another at overlapping margins thereof, and from the first position to a second position above the second press platen in which the third mould half and the fourth mould half are opened towards one another such that, by the third mould half being pressed onto the fourth mould half, the plastic half-shells may be welded to one another at overlapping margins thereof. 
     In accordance with embodiments, an apparatus for producing motor vehicle fuel tanks may include at least one of: a first press platen including a pivoting arm having a pivoting-arm pillar and a pivotable pivoting table, a first mould half and a second mould half arranged on the pivotable pivoting table, the first mould half and the second mould half configured to accommodate heated and thermoformed plastic half-shells; and a second press platen including the pivoting arm, a third mould half and a fourth mould half arranged on the pivotable pivoting table, the third mould half and the fourth mould half configured to accommodate heated and thermoformed plastic half-shells, wherein the pivoting arm is movable between a first position above the first press platen in which the first mould half and the second mould half are opened towards one another such that, by the first mould half being pressed onto the second mould half, the plastic half-shells may be connected to one another, and from the first position to a second position above the second press platen in which the third mould half and the fourth mould half are opened towards one another such that, by the third mould half being pressed onto the fourth mould half, the plastic half-shells may be welded to one another. 
     In accordance with embodiments, a method for producing plastic containers may include at least one of: providing a first press platen including a pivoting arm, a first mould half and a second mould half arranged on the pivoting arm, and a second press platen including the pivoting arm, a third mould half and a fourth mould half arranged on the pivoting arm; introducing first heated plastic plates in the first mould half and the second mould half by manipulating the pivoting arm to a first position above the first press platen in which the first mould half and the second mould half are opened towards one another; thermoforming the first heated plastic plates into first plastic half-shells; pressing the first mould half onto the second mould half; connecting the first plastic half-shells accommodated in the first and second mould halves to one another at overlapping margins thereof; introducing second heated plastic plates in the third mould half and the fourth mould half by manipulating the pivoting arm from the first position to a second position above the second press platen in which the third mould half and the fourth mould half are opened towards one another; thermoforming the second heated plastic plates into second plastic half-shells; pressing the first mould half onto the second mould half; connecting the second plastic half-shells accommodated in the third and fourth mould halves to one another at overlapping margins thereof. 
    
    
     
       DRAWINGS 
       Embodiments will be illustrated by way of example in the drawings and explained in the description below. 
         FIG. 1  illustrates a perspective view of an apparatus for the production of plastic containers, in accordance with embodiments. 
         FIG. 2  illustrates a diagrammatic view of an apparatus for the production of plastic containers, in accordance with embodiments. 
         FIGS. 3-8  illustrate a method for the production of plastic containers, in accordance with embodiments. 
         FIG. 9  illustrates a front view of an apparatus for the production of plastic containers, in accordance with embodiments. 
         FIG. 10  illustrates a back view of the apparatus of  FIG. 9 . 
         FIG. 11  illustrates a diagrammatic illustration of a spring assistance of an apparatus for the production of plastic containers, in accordance with embodiments. 
     
    
    
     DESCRIPTION 
     As illustrated in  FIGS. 1 and 2 , an apparatus for the production of plastic containers, in accordance with embodiments. The apparatus includes a first press platen  1 , a second press platen  5  and a pivoting arm  3  between the press platens  1 ,  5 . The pivoting arm  3  includes a pivoting-arm pillar  9  and a pivoting table  10  mounted pivotably on the pivoting-arm pillar  9 . The first press platen  1  is associated with a first press  13  and the second press platen  5  is associated with a second press  14 . 
     As illustrated in  FIG. 2 , on and/or over the first press platen  1 , a first mould half  2  may be arranged, which together with a second mould half  4  arranged on the pivoting arm  3  on a side of the pivoting table  10  which faces the first press platen  1 , forms a cooperating pair of moulds. Heated and thermoformed plastic half-shells may be accommodated in the first mould half  2  and the second mould half  4 . For this purpose, as further illustrated in  FIGS. 3-8 , plastic plates  8  held approximately level are laid onto the mould halves  2  and  4  and thermoformed in the mould halves  2 ,  4 . 
     The apparatus has a third mould half  6  on the second press platen  5 . The pivoting arm  3  has a fourth mould half  7 , heated and thermoformed plastic half-shells being accommodatable in the third mould half  6  and the fourth mould half  7 . 
       FIGS. 1 and 2  illustrate the pivoting arm  3  in each case in a second position of the pivoting arm  3  in which the third mould half  6  and the fourth mould half  7  are open towards one another, so that, by the third mould half  6  being pressed onto the fourth mould half  7 , the heated plastic half-shells accommodated therein may be welded to one another at their overlapping margins, in order to form a closed plastic container  20 . 
     As illustrated in  FIG. 1 , the pivoting arm  3  or its pivoting table  10  may be actuated primarily via a geared motor  11 . The pivoting movement of the pivoting arm  3  may in this case be assisted by a hydro-pneumatic spring device  12 , so that the geared motor  11  may have smaller dimensioning. The pivoting table  10  may be secured in a horizontal position by way of locks  15 , so that it withstands the forces when the mould halves are being pressed one onto the other. 
       FIGS. 3 to 8  illustrate a method for the production of plastic containers in accordance with embodiments. First, in  FIG. 3 , the pivoting arm  3  of the apparatus is still in the second position in which the orifices of the third and the fourth mould halves  6 ,  7  are opposite one another. The orifices of the first mould half  2  and the second mould half  4  point upwards, so that preheated plastic plates  8  may be arranged on them and sealed off at their margins with respect to the mould halves  2 ,  4  by way of suitable sealing frames. 
     As illustrated in  FIG. 4 , the plastic plates  8  are thermoformed in the mould halves  2 ,  4  by a vacuum, so that they are drawn into the mould halves  2 ,  4 . Thereupon, insert parts may be introduced into the formed plastic shells and fastened such as, for example, welded, thereto. 
     As illustrated in  FIG. 5 , next the pivoting arm  3  is pivoted through 180 degrees to the left in the figures, so that the pivoting arm  3  is manipulated to the first position in which the orifices of the first and the second mould half  2 ,  4  lie opposite one another. The first press platen  1  is manipulated upward and presses together the two plastic shells which are welded to one another at their margins by pressure and heat in order to form a plastic container  20 . 
     As illustrated in  FIG. 6 , next the preheated plastic plates  8  may be laid in turn onto the then upwardly open mould halves  6 ,  7  and sealed off at the margin with respect to the mould halves  6 ,  7 , by way of suitable sealing frames, while the plastic container  20  in the first and second mould half  2 ,  4  cools. 
     As illustrated in  FIG. 7 , next the plastic plates  8  on the third and fourth mould halves  6 ,  7  are vacuum-formed, and once again insert parts may be introduced into the plastic shells and welded thereto. Meanwhile, the plastic container  20  in the first and second mould half  2 ,  4  cools further. 
     As illustrated in  FIG. 8 , next the first press platen  1  may be lowered again and the finished plastic container  20  extracted, while the pivoting arm  3  is pivoted back to the second press platen  5  again and a further container is pressed on this second press platen  1 . 
     The method in accordance with embodiments, may then, of course, be repeated as often as desired or necessary. Whenever the pivoting arm  3  is pivoted, a further finished plastic container  20  may be released. The plastic containers  20  produced by way of the first press  13  may be identical to the plastic containers  20  produced on the second press  14 , and therefore, be produced with a higher output. Structurally different mould halves, however, may also be used on the press platens, so that two different products may be produced simultaneously. 
     As illustrated in  FIG. 9 , an apparatus for the production of plastic containers illustrated from the side on which the containers are extracted.  FIG. 10  is a back view of the apparatus of  FIG. 9 , for example, from the side on which the plastic plates are supplied. 
     As illustrated in  FIG. 11 , the apparatus in accordance with embodiments may include a spring assistance in which the pivoting movement of the pivoting arm  3  may be assisted by a hydro-pneumatic spring device  12 . The hydro-pneumatic spring device  12  may use a hydraulic cylinder  16 , by way of which the pivoting table  10  may be moved. For this purpose, a hydraulic fluid is stored in a pressure reservoir  17 . As a result of a downward movement of the pivoting table  10 , the hydraulic fluid is pressed into the pressure reservoir  17  via the hydraulic cylinder  16 , and thus, builds up a pressure which may be utilized for subsequently lifting the pivoting table  10 . The pressure of the hydraulic fluid may also be controlled actively, for example via a hydraulic pump  18 . In order to prevent resonant vibrations of the pivoting arm  3 , damping  19  of the spring device  12  may be provided. 
     Embodiments provide an enhanced apparatus and method for the production of plastic containers, as a result of which, in particular, results in an increase in output with an apparatus having a compact construction. 
     The term “coupled” or “connected” may be used herein to refer to any type of relationship, direct or indirect, between the components in question, and may apply to electrical, mechanical, fluid, optical, electromagnetic, electromechanical or other connections. In addition, the terms “first,” “second,” etc. are used herein only to facilitate discussion, and carry no particular temporal or chronological significance unless otherwise indicated. 
     Those skilled in the art will appreciate from the foregoing description that the broad techniques of the embodiments may be implemented in a variety of forms. Therefore, while the embodiments have been described in connection with particular examples thereof, the true scope of the embodiments should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims. 
     LIST OF REFERENCE SIGNS 
       1  first press platen 
       2  first mould half 
       3  pivoting arm 
       4  second mould half 
       5  second press platen 
       6  third mould half 
       7  fourth mould half 
       8  plastic plate 
       9  pivoting-arm pillar 
       10  pivoting table 
       11  geared motor 
       12  spring device 
       13  press 
       14  press 
       15  lock 
       16  hydraulic cylinder 
       17  pressure reservoir 
       18  pump 
       19  damping 
       20  plastic container