Abstract:
A horizontal injection molding machine includes two platens, of which one can be a fixed or a moving platen and the other a moving platen, with the platens moving on horizontal columns, and a mold half carrier which is rotatably supported by a turntable and carries mold halves for injection molding tools. A yoke extends between the upper columns for movement along the upper columns. The mold half carrier has on its top side a pivot pin which engages in an opening of the yoke. This arrangement eliminates or at least reduces forces on the columns due to weight and torques.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a continuation of prior filed copending PCT International Application No. PCT/EP2006/060836, filed Mar. 17, 2006, which designated the United States and has been published but not in English as International Publication No. WO 2006/106035 and on which priority is claimed under 35 U.S.C. §120, and which claims the priority of German Patent Application, Serial No. 10 2005 016 240.1, filed Apr. 8, 2005. 
   This application is also a continuation of prior filed copending PCT International Application No. PCT/EP2006/060838, filed Mar. 17, 2006, which designated the United States and has been published but not in English as International Publication No. WO 2006/106036 and on which priority is claimed under 35 U.S.C. §120, and which claims the priority of German Patent Application, Serial No. 10 2005 016 239.8, filed Apr. 8, 2005, pursuant to 35 U.S.C. 119(a)-(d). 
   The contents of International Application Nos. PCT/EP2006/060836 and PCT/EP2006/060838 as well as German Patent Application, Serial Nos. 10 2005 016 240.1 and 10 2005 016 239.8 are incorporated herein by reference in their entirety as if fully set forth herein. 

   BACKGROUND OF THE INVENTION 
   The present invention is directed, in general, to an injection molding machine with a moving rotary device. 
   WO 01/010624 discloses a two-platen horizontal injection molding machine with a fixed platen and a moving platen, which moves along columns, as well as a rotary device which is provided for injection molding tools and arranged between the two platens, and which is displaceable parallel to the longitudinal machine axis and rotatable about a vertical axis. The rotary device includes a base plate which can be moved by a drive assembly in the longitudinal machine direction, a turntable which is arranged on the base plate and which can be rotated by second drive means about the vertical axis. For displacing the base plate, hydraulic actuators are provided which are attached, on one hand, on the base plate and, on the other hand, in the machine bed and/or on the fixed platen. This type of horizontal injection molding machine is applicable for smaller sized machines. However, when large-sized horizontal injection molding machines are involved which have correspondingly sized rotary device and heavy mold halves, tilting moments are encountered during acceleration and deceleration of the base plate due to their mass inertia which have to be compensated. The base plate is thus guided on linear guides which must be correspondingly dimensioned in cross-section, for example a dovetail cross-section. With increasing size of the horizontal injection molding machine, the tilting moments to be absorbed also increase; however, the required linear guides with a dovetail cross-section are relatively expensive and not available for very large horizontal injection molding machines. 
   WO 03/013824 A1 discloses a two-platen horizontal injection molding machine wherein a reversing plate adapted to receive mold halves of injection molding tools and operating as rotary device for the injection molding tools is stationarily supported for rotation about a vertical axis in two directions in a closed solid support frame or in a C-shaped support frame which is open to one side, with the platens being movable relative to the support frame. 
   The document JP 62060618A discloses a two-platen horizontal injection molding machine with a rotary device which is provided for injection molding tools and arranged between the two platens and which is displaceable parallel to the longitudinal machine axis and rotatable about a vertical axis. In this horizontal injection molding machine, the rotary device has upper and lower support blocks which are supported and guided on the columns. A mold half carrier with an upper and a lower pivot pin arranged on an axis is received for rotation between the support blocks. For moving the mold half carrier along the longitudinal machine axis, hydraulic actuators are provided between the fixed platen, on one hand, and, the upper and lower support blocks, on the other hand. In this horizontal injection molding machine, the columns are subjected to weight torque and torsion torque, in particular when using heavy mold half carriers. Because the moving platen is displaced via the columns, loading of the columns with weight and torsion torques has also an adverse affect on the movement mechanism and the travel for the moving platen. 
   DE 19733667 A1 discloses a three-platen horizontal injection molding machine with a moving platen which extends between a fixed platen and a support platen and which is longitudinally displaceable in the fixed upper and lower columns. A rotary device provided for mold halves of injection molding tools and displaceable parallel to the longitudinal machine axis, is provided between the platens. In this horizontal injection molding machine, the rotary device has upper and lower support blocks which are supported and guided on the columns. A mold half carrier is rotatably received between the support blocks by an upper and lower pivot pin arranged on an axis and in suitable bearings. For moving the mold half carrier along the longitudinal machine axis, hydraulic actuators are provided between the moving platen and the upper and lower support blocks. In this type of three-platen horizontal injection molding machine, the lower columns are under stress because they have to support the substantial weight of the mold half carriers. When heavy mold half carriers are involved, there is a need to prop up the lower support block with rollers and/or skids on the machine bed. 
   WO 99/28108 discloses a three-platen injection molding machine having two pivot pins provided with several channels or passageways for conducting media, such as gases, liquids or electric current, to the mold half carriers and onward to the mold halves. 
   It would be desirable and advantageous to provide an improved horizontal injection molding machine which obviates prior art shortcomings and yet is simple in structure and reliable in operation. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the invention, a horizontal injection molding machine includes two moving platens constructed for relative movement therebetween, a base plate disposed between the two moving platens and constructed for movement in parallel relationship to a longitudinal machine axis, a turntable supported on or in the base plate for rotation about a vertical axis, a mold half carrier attached to the turntable for carrying mold halves of injection molding tools, with the mold half carrier having a topside provided with a pivot pin, a plurality of upper and lower columns extending between the fixed and moving platens, and a yoke extending between the upper columns and movable relative to the upper columns, wherein the yoke has an opening for rotatably accepting the pivot pin of the mold half carrier. 
   According to another aspect of the invention, a horizontal injection molding machine includes a fixed platen, a moving platen constructed for movement in relation to the fixed platen, a base plate disposed between the fixed and moving platens and constructed for movement in parallel relationship to a longitudinal machine axis by a first drive assembly, a turntable supported on the base plate for rotation about a vertical axis, a mold half carrier attached to the turntable for carrying mold halves of injection molding tools, with the mold half carrier having a topside provided with a pivot pin, a plurality of upper and lower columns extending between the fixed and moving platens, a yoke extending between the upper columns and movable relative to the upper columns, with the yoke having an opening for rotatably accepting the pivot pin of the mold half carrier, and a second drive assembly arranged between the yoke and one of the fixed and moving platens, with the second drive assembly having a first drive positioned on one side of the pivot pin and a second drive positioned on another side of the pivot pin for moving the yoke relative to the one of the fixed and moving platens. 
   The present invention resolves prior art problems by providing a moving yoke between the upper columns, which is moving along the columns and engageable by a pivot pin of the center mold half carrier. The center mold carrier can be moved by a first drive assembly which engages the base plate from below as well as by the second drive assembly that operates on the yoke, so that the presence of tilting moments during acceleration and deceleration of the rotary device can be eliminated. The entire weight of the rotary device is thereby kept away from the columns. The lower columns are neither subject to weight moments nor torque. The upper columns need, at the most, to support the weight of the yoke only; the weight can also be kept away from the upper columns by supporting the weight of the yoke on the mold carrier element by suitable sliding or roller bearings. Any torque resulting from the friction between the pivot pin and the yoke can be neglected, in particular when using appropriate bearings. Weight and torsion torques can then be kept away from all four columns so that complex linear guides can be used even when a large horizontal injection molding machine is involved. 
   According to another feature of the present invention, the first and second drives may be constructed as hydraulic actuators arranged to the left and right, respectively, of the pivot pin. 
   According to another feature of the present invention, the yoke may be supported upon the mold half carrier through intervention of a bearing unit, e.g. a slide bearing or a roller bearing. 
   According to another feature of the present invention, the pivot pin is supported on the topside of the mold half carrier for rotation therewith and may constitute an inner part of a rotary distributor configured to supply media to at least one of the mold half carrier and mold halves, with the rotary distributor having a non-rotating outer part which is connected to the yoke. 
   According to another feature of the present invention, first linear guides can be mounted on the machine bed for guiding the movement of the moving platen, and second linear guides can be provided on or in the machine bed for guiding the movement of the base plate. 
   According to another feature of the present invention, the first drive assembly is disposed between the base plate and the fixed platen. Suitably, first drive assembly includes a hydraulic actuator. 
   According to another feature of the present invention, a trailing cable installation may be secured on the yoke for flexibly carrying along supply lines. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
       FIG. 1  shows schematically a side view of a first embodiment of a two-platen horizontal injection molding machine according to the invention; 
       FIG. 2  shows schematically a front view of the two-platen horizontal injection molding machine of  FIG. 1  taken along the line A-A; 
       FIG. 3  shows a perspective top view with a detail of the yoke with an upper rotary distributor and a rotary feedthrough of the two-platen horizontal injection molding machine of  FIG. 1 ; 
       FIG. 4  shows in cross-section a detail of the upper rotary distributor of  FIG. 3 ; 
       FIG. 5  shows a detail of a lower rotary distributor in cross-section; 
       FIG. 6  is an enlarged view of a cross roller bearing supporting the turntable on the baseplate; 
       FIG. 7  shows schematically a side view of a second embodiment of a two-platen horizontal injection molding machine according to the invention; 
       FIG. 8  shows schematically a front view of the two-platen horizontal injection molding machine of  FIG. 7  taken along the line B-B; 
       FIG. 9  shows a perspective top view with a detail of the yoke with an upper rotary distributor and a rotary feedthrough of the two-platen horizontal injection molding machine of  FIG. 7 ; 
       FIG. 10  shows schematically a side view of a two-platen horizontal injection molding machine of the invention; 
       FIG. 11  shows schematically a front view of the two-platen horizontal injection molding machine of  FIG. 1  taken along the line C-C; and 
       FIG. 12  shows a perspective top view with a detail of the yoke with a rotary distributor and a rotary feedthrough of the two-platen horizontal injection molding machine of  FIG. 10 ; 
       FIG. 13  shows schematically a side view of a fourth embodiment of a two-platen horizontal injection molding machine according to the invention; 
       FIG. 14  shows schematically a front view of the two-platen horizontal injection molding machine of  FIG. 13  taken along the line D-D; and 
       FIG. 15  shows a perspective top view with a detail of the yoke with an upper rotary distributor and a rotary feedthrough of the two-platen horizontal injection molding machine of  FIG. 13 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Throughout all the figures, same or corresponding elements are generally indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
   Turning now to the drawing, and in particular to  FIG. 1 , there is shown a first embodiment of a two-platen horizontal injection molding machine according to the invention with a fixed, centrally located rotary device. Two platens  5  and  6  are movably supported on massive slide shoes  3  on a machine bed  1  by way of two longitudinal support beams  2  and transverse struts  4 . The two platens  5  and  6  can be moved by diagonally opposed hydraulic actuators  7  (top) and  8  (bottom). The actuators are mounted, on one hand, (for example with the cylinders  7   a ,  8   a ) on support struts  9   a  and  9   b  connected to the machine bed and, on the other hand, (for example with piston rods  7   b ,  8   b ) to the platens. The platen  6  is composed of the actual platen  6   a  and a pressure plate  6   b , between which four pressure cushions are arranged for producing the clamping pressure, with only the rear pressure cushions  9  and  10  being visible in the Figure. Two columns  11   a,b  and  12   a,b , in parallel relationship and in a plane, are secured between the two platens  5  at the top and at the bottom, with only the rear columns  11   a  and  12   a  visible in the Figure. The columns extend through the left platen  5  in  FIG. 1  and have grooves  13  on their protruding end for engagement of hemispherical locking jaws  14  and  15 . In the position illustrated in  FIG. 1 , the locking jaws are closed and the clamping unit is locked. A turntable  21  is rotatably supported for rotation about a vertical axis on a base plate  18  attached on or in the machine bed  1  by way of a suitable bearing, in the present example a cross roller bearing  22 . A mold half carrier  23 , which in the present example is configured as a reversing plate, is affixed to the turntable  21  and carries mold halves  24   a  and  25   a  of two injection molds  24  and  25 . The corresponding mold halves  24   b  and  25   b  are disposed on the platens  5  and  6   a.    
   A yoke  16  is supported above the reversing plate  23  by way of a first slide bushing  17  disposed on the top side of the reversing plate  23  for rotation relative to the reversing plate  23 . The columns  11   a  and  11   b  extend through the yoke  16  through additional slide bushings  19  and  20  in matching bores. The first slide bushing  17  extends through a matching opening in the center of the yoke  16  and is used for passing a rotary distributor or a rotary feedthrough  26  for supply of media, such as water, auto, air, electric current and the like, to the reversing plate  23  and the mold halves  24   a ,  25   a  (for a detailed description of the upper rotary distributor  26 , see  FIG. 4 ). The inner part  26   a  is fixedly connected to the reversing plate  23  and includes channels  27  which terminate above the yoke  16  in annular grooves  28  and which can be used to supply the desired media to and discharge the media from the mold halves. The outer part  26   b  is secured on the yoke  16  and supported for rotation relative to the inner part  26   a  by way of upper and lower bearings  29 . Connecting channels  30  are provided in the outer part  26   b  which terminate in the annular grooves  28  of the inner part  26   a  and which can be connected to the lines for the respective media. 
   Another rotary distributor  26 ′ which is illustrated in more detail in  FIG. 5  is provided below the reversing plate  23 . This rotary distributor is of the same type as the upper rotary distributor  26  arranged above the reversing plate  23 . The inner part  26 ′ a  is fixedly connected to the turntable  21  or the reversing plate  23 , whereas the outer part  26 ′ b  is fixedly connected to the base plate  18  and supported by several bearings for rotation relative to the inner part. 
     FIG. 6  illustrates on an enlarged scale the support of the turntable  21  on the base plate  18  by a cross roller bearing  22 . Other suitable bearings can be used in lieu of the cross roller bearing. The rotary drive may be conventional and is therefore not illustrated or described in detail. For example, a gear ring can be provided on the outer circumference of the turntable, in which a gear wheel driven by an electric motor or a hydraulic motor engages. 
     FIGS. 7 to 9  show a second embodiment of a two-platen horizontal injection molding machine according to the invention with a stationary rotary device. Identical components are designated with identical reference symbols. Unlike the first embodiment depicted in  FIGS. 1 to 6 , the hydraulic actuators of the first embodiment located outside the region of the platen are replaced with hydraulic actuators located between the rotary device and the platens. As seen in  FIGS. 7 to 9 , a total of four hydraulic actuators  27 ,  28 ,  29  and  30  are arranged between the joke  16  and the two platens  5  and  6  on both sides of the yoke at a distance from the upper rotary distributor  26 . The actuators  27  and  28  are mounted between the yoke  16  and the left platen  5 , as viewed in  FIG. 7 , whereas the actuators  29  and  30  are mounted between the yoke  16  and the right platen  6 , as viewed in  FIG. 7 . The actuators  27  and  29  are aligned on an axis, as are the actuators  28  and  30 . In this way, the forces transferred to the yoke  16  compensate each other and the yoke  16  is not tilted relative to the columns  11   a  and  11   b . Likewise, four hydraulic actuators  31 ,  32 ,  33  and  34  are arranged below the reversing plate  23 , which are attached, on one hand, to brackets  31   a  to  34   a  which are connected to the base plate  18  and, on the other hand, to the platens. The actuators  31  and  33  and the actuators  32  and  34 , respectively, are each aligned on a respective axis. Due to the particular view, neither the brackets  33   a  and  34   a  nor the hydraulic actuators  34  are visible in the Figure (which would be located in the lower right corner of  FIG. 1  in front of the actuator  33 ). 
     FIGS. 10 to 12  illustrate a third embodiment of a horizontal injection molding machine according to the invention. Unlike the first and second embodiments, one of the platens, in the present example the left platen  50 , is here fixedly secured on a machine bed  1 , and a moving platen  60  which is movably supported on massive slide shoes  60  and matching linear guides  42 . The moving platen  60  can be moved by hydraulic actuators  70  and  80  which are arranged diagonally with respect to one another. These are secured, on one hand, (for example, with the cylinders  70   a ,  80   a ) on support struts  90   a  and  90   b , which are connected to the machine bed, and, on the other hand, on the moving platen  60  (for example with their piston rods  70   b ,  80   b ). The hydraulic actuators  70  and  80  can also be arranged between the fixed and the moving platens. The platen  60  is composed of the actual platen  60   a  and a pressure plate  60   b , between which four pressure cushions  10  are arranged for producing the clamping pressure, with only the rear pressure cushions  9  and  10  visible in  FIG. 10 . Secured to the moving platen  60  at the top and the bottom are two columns  110   a,b  and  120   a,b , respectively, in parallel relationship and in a plane, of which only the rear columns  110   a  and  120   a  are visible in  FIG. 10 . The columns extend through the fixed platen  50  and have grooves  13  on their protruding end, for engagement of locking jaws  14  and  15 . A base plate  18  can be moved on additional linear guides  40  and  41  by means of hydraulic actuators  43  and  44  in parallel relationship to the longitudinal machine axis. A turntable  21  is supported on the base plate  18  by a cross roller bearing  22  (see  FIG. 6 ) for rotation about a vertical axis. The construction of the rotary device itself is otherwise identical to the embodiments illustrated in  FIGS. 1 to 9 . 
   A yoke  16  is positioned above the reversing plate  23  and supported by a first slide bushing  17  disposed on the top side of the reversing plate  23  for rotation with respect thereto. The columns  110   a  and  110   b  are guided through the yoke  16  via additional slide bushings  19  and  20  in mating bores. The first slide bushing  17  extends through a mating opening in the center of the yoke  160 . A rotary distributor or a rotary feedthrough  26  passes through the slide bushing  17  and supplies media, such as water, oil, air, electric power and the like to the reversing plate  23  and the mold halves  24   a ,  25   a . The supply lines for the media (not shown) leading to the connections  30  in the rotary distributor can be implemented as a trailing cable installation  45  secured to the yoke  16  which can then flexibly follow the travel of the turntable. 
   Two hydraulic actuators  270  and  280  are arranged between the yoke  16  and the fixed platen  50  at a distance to the rotary distributor  26 . The entire turntable can be moved by the actuators  43  and  44  which operate below the reversing plate  23  on the base plate  18  without the risk of generating a tilting moment during acceleration and deceleration along the longitudinal machine axis. The linear guides  40  and  41  therefore do not need to be provided with a special cross-section, for example a dovetail cross-section, for absorbing the tilting moment. Instead, simple linear guides suffice as long as they provide lateral guiding, such as a U-shaped rail, in which a mating guide section disposed on the bottom side of the base plate can engage, or a rail with an inverted T-profile (see  FIG. 11 ), which engages with a mating groove on the bottom side of the base plate. 
     FIGS. 13 to 15  illustrate a fourth embodiment of a two-platen horizontal injection molding machine according to the invention. In this embodiment, the rotary device is moved only by way of the actuators  43  and  44  operating on the base plate, while no actuators are installed between the yoke  16  and the fixed platen  50 . Depending on the size of the machine, the linear guides  40  and  41  may here advantageously be provided with a dovetail cross-section and the like. Another difference to the previously described embodiments is that the travel of the moving platen  60  is attained by way of the two diagonally opposed hydraulic actuators  46  and  47 , which are attached, on one hand, to the fixed platen  50  and, on the other hand, to the moving platen  60  by way of brackets  49 . In all other aspects, the configuration and operation of this two-platen horizontal injection molding machine are identical to the third embodiment depicted in  FIGS. 10 to 12 . 
   While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.