Abstract:
The invention relates to an injection molding machine having a plurality of modular drive groups which are arranged on the injection molding side and on the mold closure side. According to the invention, at least one of the drive groups is connected to the injection molding machine via at least one multifunction element which, as an interface, makes it possible to optionally connect different types of drives, e.g., electromechanical drives, hydraulic drives, pneumatic drives, linear motors or electromagnetic drives as a drive group in an otherwise unmodified injection molding machine. Independent of the respective drive, space for the respectively used drive groups is provided on the injection molding machine in order to accommodate each type of drive. As a result, the structural requirements for an increased modularity are accomplished by using components which, to a great extent, are identical.

Description:
TECHNICAL FIELD 
     The invention relates to an injection molding machine for processing plastics materials and other plasticisable substances, such as ceramic or pulverulent substances, having a modular structure comprising a plurality of driving groups. 
     BACKGROUND OF THE INVENTION 
     Such modular structure is indeed not known in its entirety from prior art, but it is known from EP 0 576 925 A1, for example, to provide liquid-cooled electrical servomotors within individual driving groups of an injection molding machine, both on the side of the injection molding unit and on the mold-closing side. Indeed, such motors may therefore be optionally used for an injection molding machine, but it is necessary to change the actual connecting elements on the injection molding machine if other drive types are used. In consequence, numerous parts have to be provided, especially in the factory of the manufacturer, in order to construct machines totally in accordance with the wishes of the customers. In addition, this leads to longer delivery times. 
     SUMMARY OF THE INVENTION 
     On the basis of this prior art, the basic object of the present invention is to provide the structural prerequisites for increased modularity with an injection molding machine of the initially mentioned type, using largely identical component parts. 
     This object is achieved by an injection molding machine for processing plastics materials having a modular structure comprising a plurality of driving groups. The injection molding machine includes: 
     a machine base, 
     a mold closing unit having 
     a stationary mold carrier connected to the machine base, 
     a movable mold carrier, which provides a mold clamping chamber between itself and the stationary mold carrier 
     at least one injection mold, the mold parts of which can be accommodated in the mold clamping chamber on the stationary mold carrier and on the movable mold carrier, 
     a closing mechanism as a first driving group for moving the movable mold carrier towards the stationary mold carrier and away from said stationary mold carrier so as to close the injection mold, and 
     force transmitting means for transmitting substantially the closing force from the closing mechanism to the stationary mold carrier, 
     and an injection molding unit, having 
     a plasticizing unit, which comprises a plasticizing cylinder and a feeding means, which is accommodated in the plasticizing cylinder, as well as a nozzle mouth on the end face, which mouth lies in an injection axis, 
     a carrier block, which is disposed on the machine base so as to be displaceable along the injection axis, and on which block the plasticizing unit is detachably mounted, 
     an injection bridge, 
     a metering drive for the feeding means of the plasticizing unit as a third driving group, which is connectable to the injection bridge, 
     at least one nozzle moving drive, which is axis-parallel to the injection axis, as a fourth driving group for moving the nozzle mouth towards the injection mold and away from said mold, and 
     at least one injecting means, which is axis-parallel to the injection axis, as a fifth driving group for the movement of the feeding means relative to the plasticizing cylinder, 
     wherein at least one of first driving groups is connectable to the injection molding machine via at least one multifunctional element, which serves as an interface selectively for the connection of at least two different drive types selected from the group consisting of electromechanical drives, hydraulic drives, pneumatic drives, linear motors and electromagnetic drives as the driving group with an otherwise unchanged injection molding machine, whereby space is made available for the driving groups, independently of the particular drive, on the injection molding machine for accommodating each type of drive. 
     Because of additional structural outlay, possibilities for connection to the parts of the injection molding machine are already provided in the preliminary section, so that the remaining parts of the injection molding machine already satisfy the various requirements of the different drive types, either hydraulically, pneumatically, electromechanically, as a linear motor or electromagnetically. If this additional outlay is provided during construction, this later facilitates the manufacture and reduces the additional outlay for each machine since, without creating greater problems, compliance with the wishes of the individual customers can be achieved. In this respect, the more interfaces are provided for different drive types, the quicker the machine can be delivered. Furthermore, this modularity provides possibilities for the customer himself to optimize the injection molding machine depending on the injection molded product. Thus, for example, for two-color injecting or for a large throughput, it may be advantageous to operate the injection molding unit electrically, while it may be advantageous, because of the speed with a small throughput, to operate the injection molding unit hydraulically. Because of the given modularity, the customer himself can even make the adaptation required for this. 
     For example, a rotation transmitting element may be provided in the injection bridge, which element is provided so that a rotary motor is connected to the rear end, or a driving wheel can be secured at a different location, so that this element is actuatable via a transmission, In such case, sufficient space is made available for all of the drives on the injection molding machine. 
     Structural elements may be provided in the injection bridge, which elements are even passive depending on the drive type and are not needed at all, but, on the other hand, they create the possibility of changing the drive type without any problems. In such case, the space required for the different drive types can be achieved when these structural parts, which are required for the different drive typos, can be combined in a very small space. 
     The movable mold carrier may be provided on the mold closing side, so that both electromechanical drives and hydraulic or pneumatic drives can be connected to the same structural parts. It should not be underestimated here that the structural part has to be prepared in this respect for the various requirements, whereby the tightness for the hydraulics has to be ensured in the same way as the introduction of forces has to be ensured for the electromechanical drive. 
     Additional advantages are found in the sub-claims. 
    
    
     BRIEF DESCRIPTIONS OF THE FIGURES 
     FIG. 1 is a three-dimensional view of the injection molding unit taken in the direction of the injection bridge, all of the driving groups being hydraulically operated; 
     FIG. 2 is a cross-sectional view through the injection molding unit of FIG. 1; 
     FIG. 3 is a cross-sectional view according to FIG. 2, the metering drive being effected electrically via a high-torque motor; 
     FIG. 4 is a cross-sectional view according to FIG. 2, the feeding means being rotated by a servomotor via a transmission; 
     FIG. 5 is a cross-sectional view taken along the line  5 — 5  of FIG. 4; 
     FIG. 6 is a cross-sectional view through the injection molding unit in the region of the transmission taken along the line  6 — 6  of FIG. 5; 
     FIG. 7 is a three-dimensional view of the injection bridge and transmission; 
     FIG. 8 is a cross-sectional view according to FIG. 2 with a modified injection bridge and hydraulic injection; 
     FIG. 9 is a cross-sectional view according to FIG. 8 with an electromechanical injection unit; 
     FIG. 10 is a cross-sectional view according to FIG. 8, the nozzle moving drive being a linear motor; 
     FIG. 11 is a side elevational view, partially in cross-section, of a plasticizing cylinder, mounted on the carrier block, with an hydraulic drive for a closure nozzle; 
     FIG. 12 is a view according to FIG. 11 with an electromechanical drive for the closure nozzle; 
     FIG. 13 is a side elevational view, partially in cross-section, of an hydraulically operated mold closing unit; 
     FIG. 14 is a view according to FIG. 13, all of the drives being effected electromechanically; 
     FIG. 15 is a side elevational view of a mold closing unit having an electromechanical closing mechanism and a hydraulic means for applying the closing force; and 
     FIG. 16 is an isometric view of the injection molding machine provided with the driving groups. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention is now explained more detailed by way of example with reference to the accompanying drawings. However, the embodiments are only examples which should not limit the inventive concept to one specific actual arrangement 
     The injection molding machine is used, for example, as a plastic injection molding machine for processing plasticisable substances, such as plastics materials, pulverulent or ceramic substances, for example. According to FIG. 16, the injection molding machine has a modular structure provided with a plurality of driving groups, some of which are associated with the mold closing unit F and some of which are associated with the injection molding unit S. Mold closing unit F and injection molding unit are disposed on the machine base  35 . 
     The mold closing unit F has a stationary mold carrier  34  and a movable mold carrier  13 . A mold clamping chamber R is formed between the two mold carriers, and molding parts of an injection mold M on the stationary mold carrier  34  and on the movable mold carrier  13  are accommodated in said chamber. The mold closing unit has a closing mechanism C, which simultaneously represents the first driving group  100  for moving the movable mold carrier towards the stationary mold carrier  34  and away from said stationary mold carrier. A first supporting element  25  is provided to support the closing mechanism C, and an additional supporting element may also be provided for “serial closing”. The movable mold carrier is transferred for the mold closure via the first driving group  100  during this serial closing, while the closing force is applied by a separate driving group. The second driving group  200  serves as the device for applying the closing force and is used, more especially, when the first driving group  100  has transferred the movable mold carrier  13  for mold closure of the injection mold assembly M. If necessary, however, the first driving group  100  may be combined with the second driving group  200  by one and the same driving group, and such is possible, for example, more especially with an hydraulic solution. 
     Force transmitting means are provided in order to transmit forces, which are substantially produced during the application of the closing force, from the first supporting element  25  to the stationary mold carrier  34 . These force transmitting means are the bars  86 , which simultaneously serve as the guide means for the closing mechanism C and the movable mold carrier  13 . Other elements may also be provided as the force transmitting element, such as so-called “C-shaped clamps”, for example, which conduct the forces, which occur during closure and during injection molding, around the mold clamping chamber R from the stationary mold carrier  34  to the movable mold carrier  13 , as is known to the person skilled in the art. 
     According to FIG. 1, the injection molding unit S has a plasticizing unit P, which includes a plasticizing cylinder  11  and a feeding means  12 , which is accommodated in the plasticizing cylinder. At the end face, the injection molding unit terminates with a nozzle body  52 , which includes a nozzle mouth  52   a , which lies in an injection axis s—s (FIGS. 11,  12 ). The plasticizing unit P is detachably mounted on a carrier block  10 , which is displaceably disposed on the machine base  35  along the injection axis s—s. 
     Furthermore, the injection molding unit S includes an injection bridge  14  as well as a metering drive  41 ,  41 ′,  41 ″ for the feeding means  12  and the plasticizing unit P as the third driving group  300 , which is connectable to the injection bridge  14 . The metering drive is more especially used to rotate the feeding means, since this feeding means is mainly a feeding screw. If a feeding piston is provided here, the third driving group  300  coincides with the injecting means  43  of the fifth driving group  500 . 
     At least one drive, which is axis-parallel to the injection axis s—s, is provided as the injecting means—but a plurality of drives are provided mainly to achieve a symmetrical introduction of force—which drive serves as the fifth driving group  500  for the movement of the feeding means  12  relative to the plasticizing cylinder  11 . Because of this axial movement of the feeding means, the plasticized material situated in front of the feeding screw is injected into the mold cavity of the injection molding M. 
     Furthermore, in order to permit the injection molding unit S to be lifted from the stationary mold carrier  34 , or respectively to permit such to be deposited on said mold carrier, at least one nozzle moving drive  42 , which is axis-parallel to the injection axis s—s, is provided as the fourth driving group  400 . As in the embodiment, a plurality of drives may also be provided here. 
     If the plasticized material injected into the mold cavity is hardened, it is ejected as a molding via an ejector unit  24 , which is disposed at any desirable location within the injection molding machine, but mainly in the injection axis s—s on the mold closing side. However, the ejector unit  24  may also be configured as a core puller. The drive for ejector unit  24 , or respectively core puller, is effected via a sixth driving group  600 . 
     Finally, a seventh driving group  700  is provided, via which a nozzle needle  51  is actuatable via a rod assembly  50 , in order to close the nozzle mouth  52   a  if necessary in the case of a closure nozzle. 
     Multifunctional elements may be distributed over the injection molding machine. At least one of the driving groups  100 , 200 , 300 , 400 , 500 , 600 , 700  is connected to the injection molding machine via at least one of these multifunctional elements. In this respect, the multifunctional element serves as the interface for the connection of different drive types. It selectively permits the connection of at least two different drive types, such as, for example, electromechanical drives, hydraulic drives, pneumatic drives, linear motor drives or electromagnetic drives. By using these multifunctional elements, it is possible for the rest of the injection molding machine to remain unchanged as far as possible. The modularity can be completed thereby, so that compliance with the wishes of individual customers can be achieved more rapidly. At the same time, the customer himself can exchange drive types in a short time depending on the intended purpose of use and adapt such to the particular requirements. For such purpose, sufficient space on the injection molding machine is made available for the driving groups  100 , 200 , 300 , 400 , 500 , 600 , 700 , irrespective of the particular drive, to accommodate any drive type. Furthermore, the multifunctional elements are so dimensioned that they also satisfy the various loadings which the individual drive types bring with them. 
     This explained more detailed hereinafter with reference to various Examples. 
     FIG. 1 illustrates a purely hydraulic injection molding unit. This injection molding unit is also shown in FIG. 2 partially in enlarged cross-section. An injection cylinder  60 , with cylinder chambers  61  and  62 , serves as the injecting means as the fifth driving group  500 . This injecting cylinder is closed by cylinder covers  63  and  64 , which slide along the cylinder  27  of a nozzle moving unit of the fourth driving group  400 . By actuating the cylinder chambers  61 ,  62  with hydraulic medium or pneumatically, the injection bridge  14 ′ is moved along the injection axis s—s, whereby the feeding means  12  is axially moved in the plasticizing cylinder  11  during this movement. The plasticizing cylinder  11  is detachably mounted on the carrier block  10 , and the cylinder  27  is also secured to said block. The cylinder  27  is coaxially penetrated by bars  31 , which simultaneously carry the piston  30  for the fourth driving group  400  of the nozzle moving drives. In this respect, a known fully hydraulic embodiment is involved up to now, wherein the injecting cylinder and nozzle moving drive are disposed coaxially with each other. 
     The injection bridge  14 ′carries centrally a rotation transmitting element  46  which, together with the injection bridge  14 ′, is configured as the multifunctional element for the third driving group  300 . The rotation transmitting element  46  serves to transmit the rotation of a metering drive  41 , which serves to prepare the material which is to be processed and, in addition, rotates the feeding means, which is configured as a feeding screw. The rotation transmitting element  46  is situated in a recess  14   a ′ of the injection bridge  14 ′ and is rotatably mounted there via bearings  15  and also secured in the axial direction. 
     On its rear side, the rotation transmitting element  46  has a recess  46   a , in which the drive shaft  41   a  of the metering drive  41  engages for operative connection. In FIG. 2, the metering drive is an hydraulic rotary motor, but an electrically operated high-torque motor may also be used instead, as in FIG.  3 . In this respect, both motors engage with the same recess  46   a , which is clearly apparent in FIG.  1 . 
     While, in FIG. 4, the fifth driving group  500  and the fourth driving group  400  are hydraulically constructed, and the nozzle movement is effected by actuating the cylinder chambers  28  and  29 , a transmission housing  47  is now disposed on a portion  46   b  of the rotation transmitting element  46 . The recess  46   a  has no function here. The portion  46   b  protrudes forwardly from the injection bridge  14 ′, so that the transmission housing  47 , with the associated transmission, can be connected there. The drive is effected via a metering drive  41 ′. In such case, the portion  46   b  clearly shows the principle pursued here. From a constructive point of view, not only is the portion  46   b  provided for the connection of the transmission, but the space is also provided on the injection molding machine, so that the elements of the different drive types can be accommodated at any time. 
     The structure of transmission and metering motor  41 ′ of the third driving group  300  is found in FIGS. 5 to  7 . According to FIGS. 6 and 7, the metering motor  41 ′ drives the pinion  72  with a drive shaft  41   a′ . The pinion  72  is mounted in the transmission housing with the spindle  72   a  and has, on the same spindle, a smaller pinion  72   b , which meshes with the pinion  71 . According to FIG. 5, the pinion  71  is also mounted in the transmission housing  47  with its spindle  71   a . The pinion  71  meshes with the pinion  70 , which is connected to the rotation transmitting element  46  according to FIG.  5 . In order to effect the connection between the transmission and servomotor instead of the metering drives  41 , the metering motor  41  has to be removed from the recess  46   a  with its drive shaft  41   a . Then the locking mechanism  45 , which locks the rotation transmitting element  46  with the feeding means  12 , has to be removed so that the transmission can be flange-mounted, possibly together with the servomotor, in the portion  46   b.    
     FIGS. 8 to  10  illustrate an alternative embodiment of the metering drive and, above all, the injection means  43 . Here, the injection bridge  14  is provided as the multifunctional element for the fifth assembly  500  and includes an abutment face  14   a . According to FIG. 8, this abutment face may serve as an abutment for a pressure transmitting element, which is configured as the injecting means  43 . The pressure transmitting element is supported on a support  18 . According to FIG. 8, the support  18  is situated at one end of the cylinder  27 , while the carrier block is disposed at the other end of the cylinder  27 , so that a framework of forces is formed via the cylinder  27 , and the injecting means  43  is supported via said framework. 
     In FIG. 8, an hydraulic or a pneumatic piston  49  is provided as the injecting means  43 . This piston is guided in a cup-like recess  18   a  of the support  18 . If the hydraulic chamber  48  there is actuated, the piston  49  is pressed in the direction towards the carrier block, whereby it transmits its force, via the recess  14   a , to the injection bridge which transmits this force to the feeding means  12 . An electromotor is provided as the metering driver  41 ′ and drives, via a transmission, the additional driving element  20  which is mounted in the injection bridge via bearings  15 . A first driving element  19 , which has no function here, is provided in the injection bridge  14 . It is apparent that the cylinder  27  serves as a guide means only for the injection bridge  14  and the support  18 , without additional cylinders being interposed, as in FIGS. 1 to  7 . 
     FIG. 9 differs from FIG. 8 because of the fact that an electromechanical drive  16  is provided as the injecting means  43 , as known from the prior German Patent Application 197 31 883.9. The cup-like recess  18   a  of the support  18  supports a part of the electromechanical spindle drive. The rotatable part of this drive, co-operating with this non-rotatable part, is mounted on the injection bridge  14 . A threaded tube  16   b  comes to lie in the cup-like recess and co-operates with a spindle head  16   c , the spindle head  16   c  being disposed on the end of a linear moving means  16   a . This linear moving means  16   a  penetrates the pressure transmitting element, which is configured as pressure tube  26 , coaxially and is driven via the first driving element  19 , the drive being effected via an electromotor of the fifth driving group  500 . Planets  16   d  are disposed between spindle head  16   c  and threaded tube  16   b . The pressure tube  26 , which is mounted in the recess  14   a  of the injection bridge, immerses in the threaded tube  16   b  in any position so that the impression of a piston-and-cylinder unit is given externally. This contributes towards protecting the drive unit from contaminants and permits constant lubrication to be introduced. Threaded tube  16   b  and spindle head communicate with each other via planets  16   d . Pressure tube  26  and threaded tube  16   b  are indirectly connected via an axial bearing element  40 . The forces, which occur during injection, are therefore not transmitted to the driving element  19  via the linear moving means  16   a , but are transmitted from the threaded tube  16   b  to the spindle head  16   c  via the planets  16   d . The spindle head passes these forces to the axial bearing element  40 , so that the pressure tube becomes the pressure transmitting element. The flux of force passes to the additional driving element  20  and the feeding means  12  via injection bridge  14 , bearing element  17  and first driving element  19 , via the axial bearing element  21 . In consequence, the dimensions of the linear moving means  16   a  must be adapted only to the rotational forces and no longer to the transmission of pressure. 
     As explained in the prior patent application, the first driving element  19  and the additional driving element  20  are disposed coaxially with each other. If both driving elements are used according to FIG. 9, the axial bearing element  21  simultaneously serves as the force transmitting element and separating means between the two driving elements, which are driven at different times by their respective drives, metering motor  41 ″ or respectively electromotor of the fifth assembly  500 . With regard to advantage and further structure of the arrangement, reference is made to the prior German Patent Application 197 31 883.9, the disclosed content of which in this respect is also expressly made the subject-matter of the present application. 
     FIG. 10 differs from FIG. 9 because of the fact that the cylinder  27  is the primary element of a linear motor. A secondary element is disposed on the bar  31  as the nozzle moving drive  42 . By appropriately actuating the primary element, a movement of the primary element relative to the secondary element is effected, and so is the nozzle movement. A comparison between FIGS. 2,  9  and  10  shows that only the cylinder needs to be appropriately exchanged for different drive types, with the cylinder covers  32 ,  33  remaining identical. If the various volumes of the hydraulic chambers  61 ,  62  are omitted in FIG. 2, and if the cylinder were prepared therefor, possibly to be used as the primary element of a linear motor, the cylinder  27  no longer needs to be exchanged basically. Depending on the intended purpose of use, the cylinder  27  serves, like the cylinder covers  32 ,  33 , as the multifunctional element for the fourth assembly  400 , said multifunctional element serving either on the inside as the cylinder for an hydraulic annular piston  30  or as a wall for the secondary element  75  of the linear motor. On the outside, the cylinder may be configured as the multifunctional element for the fifth assembly  500 , and it serves as the guide means for the injection bridge  14 ,  14 ′, or it is possibly the piston rod of an hydraulic injecting means  43 . 
     FIGS. 11 and 12 illustrate different embodiments of a plasticizing unit with a closure nozzle. The plasticizing unit P has a plasticizing cylinder  11 , in which the feeding means  12  is accommodated. The plasticizing unit is detachably mounted on the carrier block  10 , the driving mechanism for the closure nozzle remaining on the plasticizing cylinder during separation. According to FIG. 11, the nozzle needle  51  is actuated via a rod assembly  50  and a pivotal lever  55 . The nozzle body  52  is connected to the plasticizing cylinder  11  via a connection sleeve  53 . A nozzle insert  54  is disposed in the nozzle body  52 . The nozzle mouth  52   a  lies in the injection axis s—s. In FIG. 11, the rod assembly  50  terminates at a connection point  50   a , whereby it is securable on an hydraulic piston-and-cylinder unit. However, a housing wall  80  is provided in FIG.  11  and is changed with the plasticizing cylinder  11 . The rod assembly  50  penetrates this housing wall  80 . In FIG. 12, this housing wall is used, for example, as the housing of a hollow-shaft motor, which actuates the rod assembly  50 ′ electromechanically via a rolling thread drive  84 . The rod assembly  50 ′ is replaced by rod assembly  50 . A comparison of the two illustration shows that all of the elements are provided for the connection of a hollow-shaft motor or another electrical motor, so that only rod assembly and driving group need to be exchanged in order, for example, to achieve a conversion to clean-room conditions for the customer. 
     The desired modularity can also be achieved on the mold closing side at the mold closing unit F. According to FIGS. 13 and 14, the movable mold carrier  13  is configured as the multifunctional element for the first and second driving groups  100 ,  200 . The mold closing unit is supported on the machine base  35  via bearing elements  88 . The closing mechanism C is connected to the stationary mold carrier  34  via the guide bars  86 . The closing mechanism C moves the movable mold carrier  13  which, in the embodiments, is connected to a first supporting element  25  either via a threaded tube  89  or via the cylinder  110  to form an elongate unit of movement in the form of a framework of forces. Hydraulic driving groups are controlled from an hydraulic block  87 . In the fully hydraulic embodiment according to FIG. 13, the movable mold carrier  13  has a recess  13   a . The piston rod  111  of the first assembly  100  is mounted at the base of this recess to move the movable mold carrier  13  for mold closure. In this case, the recess  13   a  is part of a pressure chamber within the cylinder  110 . The first driving group  100  is simultaneously the piston rod  111  of the arrangement for applying the closing force of the second driving group  200 . It carries the piston  90 , which has overflow channels which are closed by a valve piston  91 , the movement of which is limited by a boundary element  92 . 
     In FIG. 14, however, the driving groups are electromechanical. Nevertheless, the hydraulic block  87 , the additional supporting element  85 , the guide bars  86  and, above all, the movable mold carrier  13  are retained. Whereas, in FIG. 13, the cylinder  110  of the second assembly  200  is secured on the edge of the recess  13   a  to apply the closing force, the recess  13   a  with an abutment face  1   3   b  serves as the abutment for a threaded tube  89  in FIG.  14 . This threaded tube communicates with planets  96 , which are driven by a spindle head  95 . The drive is effected via a drive rod  94 , which rotates in a freely displaceable manner in a pressure tube  93 . Even during movement, the outward appearance is of a piston-and-cylinder unit. The closing force may be applied in a manner which is not illustrated in the drawing, e.g. by a short-stroke cylinder which co-operates with the additional supporting element  85 . 
     FIGS. 13 and 14 illustrate the sixth driving group  600  of the ejector unit  24 . In FIG. 13, two hydraulic piston-and-cylinder units are disposed around an equalizing cylinder  112  and actuate the ejector unit  24  which may also be configured as the core puller. It is precisely in this embodiment that either electromechanical spindle drives may be used instead of the hydraulic piston-and-cylinder units or, for example, the surface of the equalizing cylinder  112  may be simultaneously used as the primary element of a linear motor, a sleeve, which is connected to the ejector  24 , being able to be the secondary element in a manner which is not illustrated in the drawing. If the equalizing cylinder is eliminated with the hydraulic solution, the ejector unit  24  may also be disposed directly on the movable mold carrier  13  according to FIG.  14 . The ejector unit  24  is configured as an independent structural unit, as known from WO-A 97/12741, the disclosed content of which is hereby made expressly the subject-matter of the present application in this respect. In such case, the drive is a hollow-shaft motor which accommodates the actuating element therein, this ejector unit being usable as the unscrewing arrangement or as the core puller by appropriate rotation transmitting elements. Any other desirable ejector may also be used instead of such an ejector, provided that it is ensured that communication with the movable mold carrier  13  is possible. 
     FIG. 15 illustrates the use of an electromechanical drive unit as the first assembly  100  and the use of an hydraulic unit as the driving group  200 . The structure corresponds to the structure in the prior Patent Application 197 50 057.9. The closing mechanism C drives the drive rod  94  via a belt drive  81 . The drive rod  91  terminates at the spindle head  95 , which communicates with a threaded tube  89  via planets  96 . The end face of the threaded tube  89  is closed by a closure element  97 , so that the impression of a piston-and-cylinder unit is also given here since the threaded elements are invisible externally. The movable mold carrier is divided into the parts  13 ′ and  13 ″ in order to permit the belt drive  81  to be accommodated therebetween. The first driving group  100  brings the injection mold M for mold closure. By connecting the second driving group, the first driving group  100  comes to abut with its rotatable element  94  whilst reducing the spacing a. This may occur at any time during the movement as a result of the switching chamber  98  being actuated by pressure, so that the additional supporting element  85 , which is a piston here, presses the bearing sleeve  83  in FIG. 15 to the left. When the first driving group  100  is actuated, the movable mold carrier  13 ′,  13 ″ is moved to any desirable gap between the mold halves or to the mold closure, a force and, hence, a deformation being initiated at the latest when the two halves of the mold abut against each other, such deformation leading to an earlier or later reduction in the spacing a for the abutment of the pressure tube  93  against the spindle head  95  in dependence on the ratio of forces between the switching chamber  98  and the pressure chamber  98 . This abutment prevents further rotation. The pressure chamber  99  is mainly actively connected at any desirable location so that, irrespective of whether a mold closure has already been achieved or not, the switching chamber  98  is actively or passively unloaded. The pressure tube  93  is connected to the additional supporting element  85 , which is configured as the piston. The position of the pressure tube can be influenced by the pressure in the switching chamber  98 . With regard to the additional structure and the mode of operation of this arrangement, reference is made to the above-mentioned prior German patent application. 
     To summarize, therefore, the following variable driving systems may be provided on an injection molding machine, this list making no claim to being complete. 
     1. Side of the injection molding unit 
     a) Metering (rotation) 
     hydraulically with hydraulic motor (radially, axially, toothed wheel, torque) 
     electrically with a constant motor or closed-loop controlled motor and transmission 
     b) Injection (translation) 
     hydraulically with cylinder 
     electrically with conversion of rotation to translation 
     pneumatically with cylinder 
     electrically with linear motor 
     c) Move nozzle (translation) 
     hydraulically with cylinder 
     electrically with conversion of rotation to translation 
     pneumatically with cylinder 
     electrically with linear motor 
     d) Close nozzle (translation 
     hydraulically with cylinder 
     pneumatically with cylinder 
     electromagnet 
     electromotor rotation to translation 
     electrically via linear motor 
     2. Mold closing side. 
     a) Move mold (translation) 
     hydraulically with cylinder via toggle lever or directly 
     electrically with conversion of rotation to translation 
     linear motor 
     b) Closing force with high pressure (translation) 
     hydraulically with cylinder via toggle lever or directly 
     electrically with toggle lever or eccentric 
     c) Ejector (translation) 
     hydraulically with cylinder 
     pneumatically with cylinder 
     electrically with conversion of rotation to translation 
     electrical linear motor 
     3. General 
     a) Core pullers like ejectors 
     b) Protective door like ejector 
     It is self-evident that this description may be subjected to the most varied modifications, changes and adaptations, which range from equivalents to the dependent claims.