Abstract:
The present invention relates to stack mold carriers in an injection molding machine with a rotating turret. Services to the rotating turret are provided by a rotary union attached to the translating mold carrier at the turret&#39;s axis of rotation. Hence, services such as oil, water, air and electrical power are provided to the rotating turret thereby allowing the turret to rotate in either direction. The rotating turret is attached to linkages which open and closed the molds through connection to a moving and a stationary platen which interface with the rotating turret to form molded articles therein.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved injection molding machine with a stack mold carrier. More particularly, the present invention relates to a stack mold carrier for an injection molding machine wherein the services to a rotating turret is provided by a rotary union at the pivot of the stack mold. 
     2. Related Prior Art 
     Stack mold systems for molding articles are well known in the prior art. Early stack mold carriers were attachments to the mold center section that supported it in the molding machine and allowed the center section to slide along the machine&#39;s tiebars. U.S. Pat. No. 4,408,981 to Brown shows a carrier riding on the lower tie bars. Removal of the mold required the removal of the carrier as they were not attached to the machine. 
     Another such stack mold is shown in U.S. Pat. No. 5,707,666 to DiSimone et al. The &#39;666 Patent stack mold system has a unique linkage arrangement whereby a center section and a movable end platen is displaced from the stationary platen at different rates, thereby opening and closing the stack mold during the injection molding process. In this patent, the center section does not rotate, but only translates away from the fixed platen. 
     Turret style molding machines are also well know in the prior art. A turret style molding machine includes a center or end platen that rotates following an injection cycle to either align with a post-molding operation (ie, cooling, forming, etc.) or with another injector in a multi-material application. U.S. Pat. No. 4,427,359 to Fukuoka discloses an injection stretch blow molding machine. The machine incorporates a four sided turret block positioned on a vertical axis wherein preforms are injection molded in a first position of the four sided turret block. Preforms are temperature conditioned inside a second conditioning mold at a second position of the block. The preforms are blow molded at a third position and ejected at a fourth. 
     U.S. Pat. No. 4,243,362 to Rees discloses a composite molding apparatus for molding articles from two materials. The apparatus includes a four sided turret block rotatable between two opposed faces about a horizontal axis. The block is mounted slidably between a fixed and a moving platen of a horizontal injection molding machine. Two material molding is achieved by injecting different materials from separate injectors when the block is in each of the two positions. 
     U.S. Pat. No. 5,728,409 to Schad et al., teaches a turret style injection molding machine having a rotating and longitudinally movable turret block with a plurality of mold halves rotatable and movable into engagement with a non-rotatable mold half and at least one additional molding related operation. Services to the rotating turret block are provided by a rotary union located at the axis of rotation of the turret block. 
     U.S. Pat. No. 4,734,023 to Nesch et al. discloses a turret style injection molding machine in a stack mold configuration. The turret rotates in 90° intervals to align with a first and second injector. This apparatus uses two fixed platens and a movable platen in communication with the rotating turret. The movable platen is connected to the fixed platens via a plurality of tiebars which also support and guide the platens. The movable platen and turret are operated by an inline hydraulic cylinder. 
     There exists a need for an improved stack mold injection molding machine that provides a rotating turret where services are provided to the rotating turret through a rotary union. In addition, it is desirable to incorporate features in conjunction with a rotary turret whereby the mold may be removed without the removal of the tiebars. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide an improved stack mold injection molding machine with a rotating turret. 
     Another object of the invention is to provide a means for providing services like water, hydraulic oil, pressurized air, electrical power, etc. to the rotating turret of a stack mold injection molding machine. 
     A further object of the present invention is to provide a stack mold injection molding machine with a drive means for selectably rotating a turret. 
     Yet another object of the present invention is to provide a stack mold injection molding machine with a rotating turret whereby turret rotation is independent of the clamp motion. 
     Still yet another object of the present invention is to provide a stack mold injection machine that reduces the mold open time and allows for part removal from the top or the bottom of the rotating turret. 
     Yet another object of the present invention is to provide a rotating turret in a stack mold injection machine that eliminates swinging hoses and electrical cables by the use of a rotary union. 
     The foregoing objects are achieved by the present invention which comprises a pair of mold supports to which the rotating turret can be attached. Each mold support is movable along a linear rail attached to the base of a molding machine and has at least one block containing a linear bearing mounted thereto for engaging the linear rail. Each mold support further includes a linkage assembly for connecting the mold support to other platens to synchronize movement of each mold support with movement of at least one other platen. Rotatably attached between a pair of mold supports is a turret which comprises at least one mold cavity for interface with at least one platen. Attached to at least one mold support is an actuator like an electric servomotor and in communication with the turret for rotation about a central axis. Provided to the rotating turret through the central axis of rotation is a rotary union for the communication of various services like oil, water, air, electrical power, etc. 
     Other details of the present invention, as well as other objects and advantages attendant thereto are set forth in the following detailed description and the accompanying figures, in which like reference numerals depict like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a machine base and platen assembly with stack mold linkages and rotary union in accordance with the present invention; 
     FIG. 2 is an isometric view of the mold supports with the rotating turret and rotary union; 
     FIG. 3 is a plan side view of the stack mold linkage of the present invention; 
     FIG. 4 is a plan top view of the stack mold linkage of the present invention; 
     FIG. 5 is a cross sectional view of the rotating turret with the rotary union of the present invention; 
     FIG. 6 is a side plan view of the linkage in accordance with the present invention with mold halves installed on the platens. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, FIG. 1 illustrates a molding machine  10  with the stack mold carrier assembly  12  of the present invention. The molding machine  10  has a clamp base  14  which includes two lateral support structures  16  and  18 . The molding machine  10  further has two platens  20  and  22  to which molds (not shown) are attached. Platen  20  is a fixed or stationary platen, while platen  22  is a movable platen which rides on linear bearings  24  that engage fixed linear rails  26  fastened to the support structures  16  and  18 . The molding machine  10  also includes means (not shown) for moving the platen  22  between mold closed and mold open positions. The means for moving the platen  22  may be accomplished using a hydraulic piston or other similar means operatively attached to the platen  22 , or in the alternative may be operatively attached to the linkage of the present invention. Tiebars  28  are provided to add structural support to the machine and extend from the stationary platen  20  to a mold clamping unit (not shown) or other support (not shown). In the molding machine  10 , the tiebars  28  are not used to align or support the moving platen  22  or the stack mold carrier assembly  12 . 
     As shown in the drawings, the stack mold carrier assembly  12  for supporting a rotating turret  56  comprises two mold supports or pillar castings  30  positioned on the support structures  16  and  18 . The rotational axis of the turret  56  can be either horizontal or vertical. Referring now to FIG. 2, each pillar casting  30  has a vertical post portion  32  that contains through holes  36  for acceptance of mounting bolts. The bolts are used to align and fasten each pillar casting  30  to a respective side of the rotating turret  56  of the stack mold in a known fashion. Any suitable connection means known in the art may be used to rotatably mount the turret  56  to the pillar castings  30 . Each pillar casting  30  has a base support  38  to which is fastened one or more blocks  40  containing linear bearings that engage and run a respective linear rail  26  mounted to one of the side supports  16 ,  18 . The linear rail  26  may be the same rail used to guide the moving platen  22  or may be a second rail mounted parallel to the linear rail used to guide the moving platen  22  and offset outboard to provide a dedicated alignment means for the stack mold carrier assembly pillar casting  30 . 
     Each pillar casting  30  has a third portion, a boss  42 , to which carrier linkage assembly  44  is rotatably mounted. Any suitable connection means known in the art may be used to rotatably mount the linkage assembly  44  to the boss  42 . The linkage assembly  44 , as shown in FIGS. 3-5, has a propeller  46  rotatably mounted to the boss  42 . The propeller  46  has links  48  and  50  rotatably mounted to its ends. Link  48  is rotatably mounted to stationary platen  20 , while link  50  is rotatably mounted to the moving platen  22 . The motion of the moving platen  22  between mold closed and mold open position causes the linkage assembly  44  to move each pillar casting  30  along a respective rails  26  and maintain each pillar casting  30 , and hence the turret  56 , midway between the platens  20  and  22  for the entire platen stroke. This is a conventional and well known method of mold carrier movement. 
     Alternatively, each pillar casting  30  and the moving platen  22  could be moved along a plurality of tie bars (not shown). The tie bars would support and guide the moving pillar casting  30  and platen  22 . The tie bars would obviate the need for the linear rails  26  and the blocks  40  which contain the linear bearings. This type of structure is also well known in the injection molding art. 
     Also mounted to at least one pillar casting  30  is an actuator  60  that is in mechanical communication with the rotating turret  56  through a transmission  62 . In the preferred embodiment the transmission  62  can be belts, gears, linkages or the like. The actuator  60  is used to selectably rotate in either direction the turret  56  when the mold is in the mold open position. Also mounted to at least one pillar casting  30  is a rotary union  64  which communicates the flow of services for example cooling water  66  and electrical power  68  to the rotating turret  56 . The rotary union  64  allows the turret  56  to rotate in either direction (clockwise/counterclockwise) through any angular displacement while maintaining the flow of services to the turret  56 . In the preferred embodiment, and by way of example only, the services can include hydraulic oil, water, pressurized air, electrical power or the like. For using these services, turret  56  also includes the required circuitry and control valves on board and movable with the turret. 
     In the event the turret  56  of the stack mold assembly is removed from the machine  10  and from the stack mold carrier assembly  12 , the carrier assembly  12  remains attached to the machine  10  and will not fall inward or outward. 
     Referring to FIG. 6, a first mold half  21  is mounted to the fixed platen  22  in alignment with mold cavities that are in the turret  56 . A second mold half  19  is mounted to the movable platen  20  in alignment with another set of mold cavities that are in the turret  56 . In a preferred embodiment, the turret  56  is selectably rotated by the actuator  60  to align the mold cavities in the turret  56  with a set of corresponding mold cavities on mold halves  19 ,  21 . Once aligned, the carrier assembly  12  is actuated to the mold closed position, whereby an injection molded article may be fabricated in each mold cavity. 
     Within this configuration, one could easily envision myriad pre and post processing operations during an injection molding cycle. For example, based on a four station turret, one station could injection mold a preform, a second station could temperature condition the preform, a third station could blow mold the preform into a full size plastic container, and the fourth station could eject the part on a conveyor for further processing/packaging. To transfer the article from one station to the next, the carrier assembly  12  is opened, the actuator  60  rotates the turret  56  through an arcuate sector to align the turret with a respective station and the carrier assembly  12  is closed. 
     Thus, the reader can see an improved stack mold injection molding machine with a rotary turret is provided. The use of the rotary union  64  allows for the rotation of the turret in any direction without restriction. The rotary union  64  provides a common interface to the rotating turret  56  which eliminates swinging hoses and clamps. The rotary union  64  also reduces the work required to disassembly and maintain the stack mold machine. 
     It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.