Abstract:
A polymer is plasticized in a plasticizing unit and is thereafter fed into a transfer device which is moved into alignment with a clamping press which is remotely located from the plasticizing unit. The polymer from the transfer device is deposited directly into a mold attached to the clamping press or is deposited on a carrier which moves into the mold. An impress preforming device allows the carrier deposited polymer to be shaped prior to entering the mold. Alternatively, the transfer device can be connected with a chamber which is capable of coating continuous or chopped fibers which are deposited on a carrier in a continuous or chopped manner. The carrier moves the fiber composite into the mold.

Description:
FIELD OF INVENTION 
     This invention relates to a polymer transfer and deposition device and method for depositing plasticized polymers or polymer composites on multiple sets of molds by collecting the material in transfer chambers from a central plasticizing unit, and then depositing the contents from the transfer chambers into molds which are remote from the central plasticizing unit via either a direct deposit or through an intermediate carrier which moves the polymer into the molds. Continuous or various fiber lengths can be incorporated into the polymer using an attachment connected to the transfer chamber. Polymer deposited on a carrier can be formed to a specific shape while located over the mold. 
     BACKGROUND OF THE INVENTION 
     Plastic injection molding is a well established method for producing a wide variety of plastic parts. A melt charge is built in the plasticizing section, then injected under high pressure into a closed mold held in a clamping station which must resist the pressure. After a suitable cooling time, the mold is opened to eject the finished part. To reduce the pressure created in the mold, a series of hot runner, sequential valves were developed to allow the melt to flow over shorter distances within the mold cavity to create a complete part. As cavity pressure build-up is related to the melt flow distance during fill, reducing this flow length with multiple valve gates, reduced the cavity pressure. The necessary software upgrade and valve sequence controls have become available for this lower cavity pressure injection molding process. 
     In order to further reduce the cavity pressure, various processes were developed where molten plastic was deposited into an open mold of a vertical acting clamping press. In one technique, molten plastic was injected through a series of valve gates into the bottom, stationary platen side of a down acting clamping station to form a series of puddles. The press closes on the still fluid material to fill out the mold cavity. Another version prepared a melt charge in the injection side of molding machine. When a sufficient molten charge was prepared, the entire injection unit moved forward into a open mold, attached to a vertical clamp press. As the injection section retracted out of the mold, the melt charge was deposited into the open mold in a controlled manner. This deposition of molten polymer into an open mold helped to reduce the cavity pressure based on third power affect of the cavity wall thickness on pressure generation during a typical closed mold filling process. However, like standard injection molding machines, these lower cavity pressure machines were designed to prepare and deposit a molten charge of plastic into a mold using a similar integrated, cycle driven process. Their main advantage is the ability to produce larger parts at lower clamping pressures or to capture decorative surface materials that would not resist the higher cavity pressures of a standard injection molding machine. 
     In reference to glass fiber reinforced thermoplastics processing, one method, described in U.S. Pat. No. 5,185,117, issued Feb. 9, 1993, utilized a vertical press and a two stage extrusion process where long glass fibers were introduced downstream into the plastic. The molten composite was discharged into an integrally attached accumulator in the form of a continuous log. As needed, a set length of molten plastic was cut from the log and loaded into the mold of a vertical acting clamping press, using a suitable transfer device such as a robot. 
     As described in U.S. Pat. No. 5,798,128, issued Aug. 25, 1998, another glass fiber reinforced thermoplastic process involved melting a plastic in a twin screw extruder, then introducing glass fibers into the melt stream within the extruder which exited into an accumulation chamber attached to the end of the extruder. A second syringe shaped accumulator is aligned with and connected to the first accumulator. A shutter opened and molten plastic was pushed into the second accumulator. At a predetermined fill level, the shutter closed and the syringe shaped accumulator was moved by a robot to either an open vertical press or connected to the fill port of a closed mold. Melt was pushed out of the same port opening used to fill the accumulator. 
     It is a feature of this invention to be able to produce polymer composites whereby collection devices carry polymer from a central plasticizing supply to clamping stations where the polymer can be directly deposited in the mold or transported via an intermediate carrier into the mold. This low pressure molding process allows inserts to be incorporated on the surface, as a core material or combined to form a finished product. 
     It is a further feature of the invention that the collection devices can transfer polymer into another chamber designed to accept and mix continuous fibers, chopped fibers or various combinations of chopped and continuous length fibers with the polymer using a continuous or discontinuous process. Surface materials and/or cores can be incorporated in the polymer composite. 
     Still another feature of the invention which allows the carrier deposited polymer or polymer composite to be shaped over the mold using compression dies that capture and form the polymer to produce a desired profile before placement in a mold. 
     SUMMARY OF THE INVENTION 
     A polymer is fed into a plasticizing machine such as an extruder for continuous mixing or a batch type processing machine for discontinuous mixing. Additives can be blended into the polymer during the mixing phase. The discharged polymer is deposited into a transfer device that is separate from and not integrally attached to the plasticizing machine. A swing clamp or other suitable device lifts and rotates a fill port located on top of the transfer device. Where a continuous stream of polymer is being discharged, a dual feed manifold or diverter device switches the polymer from a filled transfer chamber to another transfer device. The transfer devices are designed to move on guide tracks. The amount of polymer deposit can be regulated from chamber to chamber. For a discontinuous polymer discharge, a single feed manifold can be utilized to fill transfer chambers. 
     With the specified amount of polymer in the transfer chamber, the transfer device is moved on a linear guide transport system until it is aligned with the selected clamping station. A motor driven rack and pinion, pulley, conveyor drive or other suitable method can be used to provide linear motion. The clamping station holds one or more molds and provides the opening and closing sequence needed to produce and remove a finished part. Individual or multiple clamp stations can be aligned with the transfer device. To deposit the polymer, an exit port seal on the transfer device is partially or fully opened and pressure applied using a forward moving ram within the chamber. The shape of the exit port determines the shape of the exiting polymer. The ram is arranged to move in a horizontal direction to keep a low vertical profile on the transport device. 
     The polymer can be discharged into the mold of a vertical acting press by using one of several techniques or systems. A film, fabric, foil, scrim, felt or other suitable carrier transport passes in close proximity to the exiting polymer stream and carries the combined materials to the mold opening using supporting conveying attachments. Where two or more clamp stations are in series, two or more carriers move the combined materials to the correct mold location. Serial presses can produce a part that spans each clamp station. The press closes against the carrier and polymer to replicate the shape of the mold cavity and core. Alternately, the carrier can be supported by a second carrier which aids in transporting the materials into the press, then separated from the first carrier prior to the press close sequence. 
     The transport device moves into the clamping station to the opposite side of the mold. As the transport device retracts, polymer is deposited into the mold. The speed of retraction, chamber exit gap and length opening, and ram pressure control the rate of polymer deposit. 
     The transport device moves into the clamping station to the nearest side of the mold. As the transport device moves forward, polymer is deposited into the mold. Upon completion of the forward stroke, an insert can be placed on the deposited polymer. The transport device retracts, depositing additional polymer over the insert. The press closes after the transport device clears the mold to form an encapsulated composite structure. 
     The transport device moves into the clamping station to the opposite side of the mold. A film, fabric, foil, felt or other suitable insert is positioned below the transport device and over the mold opening. As the transport device retracts, polymer is deposited on the insert. The mold can be designed to create a seal prior to complete closure to evacuate trapped gases. 
     For each of the above discharge methods, an insert such as a film, foil, fabric or other shape, can be positioned above the melt stream in the mold to be laminated to the exposed melt side during the closing of the mold. 
     Because transport devices can travel along parallel paths, two can be aligned in series. In such an arrangement, a carrier passes under and collects deposited polymer from both units. As the carrier moves from one deposition point to the other, an insert can be placed or laminated to the exposed polymer side, then coated with the second deposition. Each transport device can deposit a different type of polymer or polymer composite. A second carrier can be positioned under the first carrier to provide additional support. The second carrier would separate from the first carrier prior to closing of the press. An insert such as a film, foil, fabric or other shape can be laminated to the exposed surface of the combined deposited polymers prior to or after entering the mold. 
     For a horizontal acting press, the carrier deposited polymer rotates from a horizontal to a vertical direction and positioned between the open horizontal acting clamp station. The clamp would close to form a part. 
     In another embodiment, the transport device connects to a second polymer collection chamber which is aligned with a clamping station. A controlled rate of polymer is transferred from the transport chamber to the collection chamber. The collection chamber has a retractable entrance designed to match the mating exit shape of the transport device. The chamber becomes progressively narrower going from the top to bottom. A spool, multiple spools or rolls of continuous fibers, woven fibers or other fiber combinations are drawn into the chamber. Chopped fibers can be fed into the chamber through the same opening. Pressure is applied to the polymer and fibers using one or more sets of rotating impellers or similar pumping methods that apply downward and penetrating forces on the polymer and fiber mix. Baffles can be attached to the walls to reduce back flow of polymer. Space is allowed within the chamber to allow polymer to fill around the fibers. Sprockets, rollers or other suitable mechanisms pull or push the coated fibers out the narrow end of the chamber. The size of the exit opening, fiber position and fiber spacing can be adjusted to control the polymer to fiber ratio and coating thickness on each side. Cut fibers can be realigned using flow disrupting devices such as stationary or reciprocating pins. Continuous fiber lengths can be blanked to the desired charge length. The width of the fiber composite can be adjusted by varying the chamber exit width. The coated fibers can be deposited on a film, fabric, foil, scrim or other suitable carrier that pass in close proximately to the polymer exit location and transported to the mold opening. The shape of the exit port determines the shape of deposited reinforced polymer., For example, a slot opening would produce a sheet or ribbon shape. Within the slot opening, selective wall thickness variations can be controlled by adjusting portions of the exit seal. The clamping station closes to form a finished part. 
     Where a thicker layer of deposited polymer is desirable, the carrier can collect additional polymer by reciprocating under the depositing polymer chamber, picking up polymer in both directions. An insert can be placed between layers of deposited polymer. 
     Alternately, the reinforced polymer can be fed directly into a horizontally positioned clamp station by locating the polymer exit just above the open mold. A controlled stream of reinforced polymer exits from the chamber, cut to the desired length and supported during movement between the open mold. The mold halves or sections then close on the polymer. 
     In a third embodiment, a low surface friction carrier, such as fluorocarbon coated fiberglass cloth or metal foil or other suitable carrier collects deposited polymer from the deposition device and moves into a vertical acting clamping press containing an open mold. Located outside the carrier conveyor, a set of shaping dies are attached to actuators positioned on each side of the carrier. As the dies move forward, they gather and shape the polymer over the mold. The carrier moves away from the dies, exposing the mold cavity. The shaping dies retract while separating the formed polymer deposition which drops into the lower mold section., The mold closes to form the finished part. The dies may be heated. 
     Where necessary, supplemental heat can be applied to any carrier deposited polymer or polymer composite prior to the mold closure sequence. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic top view of the components that make up the transfer deposition device. 
     FIG. 2 is a cross-sectional view of the polymer distribution manifold taken along line  2 A— 2 A of FIG.  1 . 
     FIG. 3 is a cross-sectional view of the transport device taken along line  3 B— 3 B of FIG.  1 . 
     FIG. 4 is a side view of a vertical acting clamping press. 
     FIG. 5 is a top view of the transport device including the driver mechanism. 
     FIG. 6 is an end view of the transport device and transport guide. 
     FIG. 7 is a view of the carrier guide and transport device depositing polymer on a carrier that feeds a vertical opening mold. 
     FIG. 8 is a view of the carrier guide and transport device depositing polymer on a carrier that feeds a horizontally opening mold. 
     FIG. 9 is a partial view of the transport device attached to a slide system within a clamping station. 
     FIG. 10 illustrates a polymer transfer and deposition device depositing polymer within a vertically active clamping station or press. 
     FIG. 11 is a cross-sectional view of inserts placed below and between deposited polymer. 
     FIG. 12 is a partial cross-sectional view of the transport device mated to the polymer collection chamber, a roll of fiber being drawn into the chamber and a carrier passing below the chamber. 
     FIG. 13 is a perspective view of the transport device depositing polymer between molds attached to a horizontally opening clamping station. 
     FIG. 14 illustrates a pair of polymer and deposition devices in series, with an insert placed between the deposits. 
     FIG. 15 is a view of two forming dies located at the clamping station. 
     FIG. 16 illustrates polymer placed on a low friction carrier which is supported by another carrier. 
     FIG. 17 is a cross-sectional view of an insert placed over deposited polymer within a clamping station. 
     FIG. 18 illustrates a clamping station with an insert being laminated to a polymer deposited on a carrier prior to entering a clamping station. 
     FIG. 19 illustrates a carrier provided with a two sided heat source, showing a cross-section of a polymer deposited on the carrier and passing between the two sided heat source. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, where the polymer transfer and deposition device is designated by the letter A. It includes plasticating machine or extruder  10  shown with remotely located combinations of multiple or a plurality of clamp stations  12  and a plurality of single site clamping stations  14 . A dual outlet polymer distribution manifold  16  with shut off controls  28  for each outlet  30  is attached to the plasticating machine  10  while depositing the plasticized polymer into the chamber of a transport device  18 . Additional transport devices  20  are positioned in front of the clamping stations  12  and  14  for returning to the manifold  16  polymer dispensing outlet. The transport device guide or conveyor  22  handles the outer transport movement while transport device guide or conveyor  24  controls the inner transport movement. 
     The arrangement or layout of the clamping stations  12  and  14  are for illustrations purposes. As shown in FIG. 4, each vertical acting clamping station  14  includes mold sections  15  which are attached to vertically spaced apart platens  13 . A fluid cylinder  25  is attached to the upper platen  13  for moving the platen  13  up and down on the guides  1   7 . The size and number of stations can be adjusted to meet a specific requirement. 
     The four illustrated transport devices  18  and  20  of FIG. 1 are shown with the inner, bottom transport device  20  serving clamping stations  12  and  14  on the bottom left side as illustrated. The top transport device  18  handles the upper left clamping station  14  as illustrated. The two outer transport devices  20  serve the outer top and bottom clamping stations  12  respectively as illustrated in FIG.  1 . One or more cylinders are attached to the transport devices  18 ,  20 , providing the pressure to move a ram  36  located within the transport chamber  34 , as shown in FIG.  3 . The number of cylinders on each transport device  18 ,  20  depends on the size of the chamber  34 . The overall dimensions of chamber  34  and the position of the ram  36  therein determine the available volume within the chamber  34 . When a molten polymer is deposited in the transport chamber  34 , the transport device  18 ,  20  is insulated and/or heated. Although not illustrated, necessary electrical, pneumatic and hydraulic components are attached to the transport device  18 ,  20 . 
     Referring now to FIG. 2, the polymer distribution manifold  16  has two outlet ports  30  for providing a continuous discharge of the polymer, with alternating on-off shut off devices  28  located at the outlet port  30 . When the outside transport chamber  34  is collecting discharging polymer, the mating shut off device  28  is in the open position and the inner shut off device  28  is in the closed position. The shut off devices  28  are reversed when the inside transport chamber  34  is collecting polymer. 
     To allow polymer discharge from the dual outlet manifold  16  into chamber  34  of the transport device  18 ,  20 , a fill port  38  is opened using a toggle lift and rotation clamp  37 . As link  39  is retracted, the toggle clamp  37  lifts the port  38  and rotates it away from the opening  38   a . In the close position, the toggle clamp  37  locks the fill port  38  in place in opening  38   a . To discharge the polymer from the transport chamber  34 , seal  40  is retracted using one or more cylinders  41 , and the ram  36  pushes against the polymer within transport chamber  34 , forcing the polymer out of the exit port  42 . 
     Each movable non-rotatable and hollow transport  18 ,  20  has a top wall  23 , a bottom wall  24  and a pair of end walls  32 . The entrance port or opening  38   a  is located in the top wall  23 . The exit port or opening  42  is located in the bottom wall  24 . 
     The transport device  20  of FIGS. 5 and 6 is provided with attached guide rolls or rollers  46  and  48 . Rollers  48  consist of inner sections that move in guide track  53  and connects to the outer pulley sections. Drive belt  50  is attached to the pulleys, not shown, located near each end of the transport device  20 . A drive motor  52  provides two directional motions for the transport device  20 . Linear encoders are positioned near the guide rails or tracks  53  to locate and control the motion of the transport device  20 . Rollers  46  move in the parallel guide tracks  53  as shown in FIG.  6 . 
     The preferred carrier  60  for either a horizontal clamping arrangement  56  and  58  (FIG. 8 and 13) or vertical clamping arrangement  13  and  15  (FIG. 7 and 10) is shown, with the carrier  60  secured on both sides by clamps  66  to a set of rotating guides  64 . The guides  64  are driven by a driver  62  moving at either a constant or at a variable speed. One or more carriers  60  pass under the transport device  20  where a layer  59  of polymer is deposited onto the carrier  60  and moved between the mold sections. The carrier  60  is in the horizontal position when passing under the transport device  20  where a polymer layer  59  is deposited on the carrier  60 . Guides  64  are positioned outside the space occupied by the mold half sections, not shown, in FIG.  10 . As the mold closes, the polymer coated carrier  60  is separated from the side clamps  66 . The guides  64  can be adjusted to allow the two mold sections to maintain close proximately to each other while feeding the coated carrier  60  between them. Where additional carrier support is required, a second carrier is positioned below the top carrier  60 , and separated from the deposited carrier  60  before closing the clamping press, not shown. 
     Referring now to FIG. 8, for a horizontally opening clamping press, the carrier  60  moves from the horizontal coating position to a vertical position prior to entering the open sides or sections  56 ,  58  of the mold. 
     In FIG. 10, the polymer transfer and deposit device  20  is depositing polymer  59  directly into the bottom half of mold  15  attached to platen  13 . Seal  40  is open during deposition. The transfer and deposit device can deposit polymer during the forward stroke, reversing stroke or in both stroke directions. An insert may be placed below the deposited polymer or between deposits or below and between deposits. FIG. 11 is a cross-section of an insert  55  below deposited polymer  59  and insert  57  captured between deposited polymer  59 . 
     For direct deposit of a layer of polymer into a vertical acting clamping press (FIG.  7 ), the transport device  20  is shuttled forward from the traversing transport device guides  22  or  24  while keeping the exit port  42  (FIG. 3) aligned with the clamping stations  12  or  14 . As shown in FIG. 9, one of the two outboard guide carriers  71  is shown. The guide carriers  71  support and direct the transport device  18 ,  20 , moving on linear guide tracks  68 , located outside the mold and polymer carrier guide space  64 . Guide attachment  54  is positioned in a locking clamp  51  mounted on carrier  71  that holds and maintains alignment of the transport device  18 ,  20  while the guide carriers are moving on the guide tracks  68 . One or both of the guide carriers  71  are attached to a drive cable  61  which drive and position the transport device  18 ,  20  within the clamping press. 
     In another embodiment, the polymer transfer and deposition device designated by the letter B of FIG. 12 shows the transport device  20  aligned with the top of a polymer collection device  72 . As the transport device  20  moves forward to combine with the collection device  72 , a hinge  78  is pushed to open a space  70  where polymer, located in chamber  34 , can be deposited into the collection chamber  72  at a controlled rate. A roll or spool of fiber  76  unwinds and moves through an opening  81  located near or on top of the polymer collection device  72 . 
     A set of drivers  80  pull the fibers  76  into the chamber  72  at a controlled rate. The drivers  80  can move the fiber  76  in a continuous or discontinuous manner. A set of rotating impellers  83  apply inward acting force to the polymer and fibers or fiber mix. Baffles  77  are laterally spaced apart from impellers  83 . Once the polymer transport device  20  has delivered a set amount of polymer, it retracts, allowing hinge  78  to close, and returns the transport device to the plasticating machine  10  where more polymer can be deposited into chamber  34 . The exit position  75  of the polymer coated fiber is adjustable to control the ratio of polymer to fiber. The exit position  75  opening is controlled by seal  40  attached to one or more pistons  41 . Seal  40  has a blade edge that can cut the existing polymer composite to any desired length. The existing polymer composite can be deposited on carrier  60  and moved into a clamping station. Cutters  85  chop fibers to any desirable length. The collection device  72  can be moved on a track system that is similar to the method used to guide the transport devices  18 ,  20  to the various clamp stations  1   2  and  14 . 
     FIG. 14 shows two polymer and deposition devices  20  in series and insert  65  placed over the first deposit  59  prior to entering the second deposition station  20 . A double carrier  60  is illustrated in FIG.  14 . Each carrier could align with separate clamping stations or mold cavities. Each device  20  could deposit the same or different polymers. 
     Another embodiment utilizes a low surface friction carrier such as described in FIG. 16, where the top surface of carrier  60  would have low friction characteristics or a low surface friction carrier  63  placed between the carrier  60  and the deposited polymer  59 . A layer of polymer is deposited on the carrier  60  and the combination indexed into a vertical clamping press and positioned over the bottom portion of an open mold. FIG. 15 shows two forming dies  82  and  84  attached to actuators  92  and  90  respectively. The forming dies  82  and  84  are aligned perpendicular to the movement direction of the carrier  60  and in line with the mold or die sections  86  and  88  which are attached to vertical acting clamps  87  and  89 . With the polymer aligned with the forming or shaping dies  82  and  84 , the dies are pushed forward by the actuators  90  and  92  where they capture and rearrange the shape of the polymer to conform to the desired shape represented in the die contact areas. The carrier  60  indexes away from the polymer captured in the die sections  86 ,  88 . The two forming dies  82  and  84  retract out of the mold area, forcing the shaped polymer to deposit within the mold section  88 . 
     For direct deposition of a polymer or polymer composite into a horizontal clamping station, FIG. 13 shows the transport device  20  positioned directly over an open mold  98  attached to horizontally opening clamping platens  56 ,  58 . The transport device  20  feeds a polymer stream  96  between the mold platens  56 ,  58 . Deposit  96  is blanked to the desired length and is supported during movement between the open clamping platens  56 ,  58  of the mold. Where polymer is deposited directly into horizontal opening clamping press, FIG. 13 shows a clamping device  101  that holds the exiting polymer  96  until the mold half&#39;s  15 , attached to platen  56 ,  58 , close on the polymer. The clamping device  101  moves down at the same rate as the existing polymer. 
     Independent of the method of deposing polymer within a clamping station, an insert  55  can be positioned above exposed polymer prior to closing the clamps. FIG. 17 shows a cross-section of an insert  55  positioned over deposited polymer  59  while the mold  15  and attached platens  13  are still in the open position. 
     Whenever a carrier  60  is utilized under a deposition device  20  or  72 , an insert can be laminated to an exposed side of the polymer using a laminating device such as a roller  67  as shown in FIG. 18 prior to entering a clamping station illustrated by clamps  13  and mold  15 . 
     For carrier deposited polymer within a clamping station, the polymer can be exposed to external heat prior to entering the clamping station. As shown in FIG. 19, heat source  103  provides heat to a polymer being transported to a clamping station. 
     The invention described above may be modified or have changes made to it within the scope of the invention as defined by the attached claims.