Abstract:
In various embodiments, devices, systems, and methods for blow molding plastics are provided. In particular, the present disclosure provides for devices, systems, and methods that are configured to create an internal cooling airflow, using conductive and convective cooling thermal properties, such that the cycle time for blow molding plastics is reduced. The decrease in cycle time provided for in accordance with the disclosed devices, systems, and methods are between, approximately 15 percent and 35 percent.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Application No. 61/135,448 filed on Jul. 19, 2008, and entitled “Molding cycle enhancer”. The entire contents of the foregoing application are hereby incorporated by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention generally relates to blow molding plastics, more particularly, to systems, methods, and devices for forming, curing, and cooling blow molded plastics. 
       BACKGROUND OF THE INVENTION 
       [0003]    Blow molding is a plastic manufacturing process where a molten plastic, also called a parison, is placed in a mold and contacted with a compressed fluid, such that the parison is forced and/or stretched to conform to the mold when it is subjected to a pressure from the compressed fluid. These systems may be used to make a wide variety of plastic products, such as, milk jugs, carbonated beverage bottles, water bottles, watering cans, plastic storage cases, and the like. Blow molded products generally have hollow cavities enclosed within plastic structures, making blow molding an efficient process to produce large volumes of low cost plastic products. Once a blow molding process and system have been designed and built, the ability to decrease the cycle time, that is the time it takes to make a part or lot of parts, makes the blow molding process more efficient and economical. 
         [0004]    Typical blow molding systems include a blow stem coupled to a fluid supply, where the fluid supply is usually compressed air at room temperature. The system also includes a melted plastic supply configured to supply a parison to a mold. The mold is generally configured to couple with the blow stem, such that, the fluid supply provided through the blow stem may be applied to the parison to force or stretch the parison to conform to the interior dimensions of the mold. 
         [0005]    Typical blow mold systems also include an external mold cooler, such as a bath that provides water to the exterior of the mold, or to internal plumbing that circulates water through the structure of the mold to provide cooling. Generally, after the parison has been stretched or forced to conform to the mold, the parison must cool and harden to retain the shape of the mold. Cooling and hardening of the parison requires that the blow mold system maintain a pressure within the cavity created in the parison by the compressed air, such that the parison continues to conform to the mold until it is sufficiently cool and hard to retain the physical structure of the mold. 
         [0006]    These systems present challenges to blow mold plastic manufactures. Specifically, the manufacture must wait for the plastic to cure before removing the formed plastic part from the mold and making another plastic part. Although cure time varies depending on the plastic product being formed, a typical blow mold system that manufactures milk jugs (a approximately one gallon container) can require between, approximately 6.5 seconds and 8.0 seconds to allow the formed parison to cool and harden sufficiently to be removed from the mold. A typical blow mold system that manufactures bleach bottles (an approximately one gallon container) can require between, approximately 14 seconds and 18 seconds to allow the formed parison to cool and harden sufficiently to be removed from the mold. This time spent waiting for cooling slows down the process and is inefficient. As such, there is a need to reduce the cooling time for solidifying blow molded products. 
       SUMMARY OF THE INVENTION 
       [0007]    The systems, methods, and devices discussed herein in exemplary embodiments of the present invention provide a circulating cooling fluid to the internal cavity of the formed parison such that the formed parison may cool and harden sufficiently to be removed from the tool, in a time that is shorter than the time for a comparable product made without the disclosure of this application. As such, the present invention provides advantages over prior art blow molding systems. 
         [0008]    In various embodiments, a device for facilitating internal cooling within a mold during blow molding operations comprises a blow stem and a supply port forming part of the blow stem. The supply port is configured to supply fluid to the mold. The device further comprises an exhaust port forming part of the blow stem. The exhaust port is configured to exhaust fluid from the mold. 
         [0009]    In various embodiments, a plastic molding system comprises a fluid supply, a fluid exhaust, and a bidirectional blow stem. The bidirectional blow stem is configured to receive a fluid from the fluid supply and supply fluid to a parison to inflate the parison. The bidirectional blow stem is also configured to exhaust fluid from the parison to the fluid exhaust during cooling of the parison. 
         [0010]    In various embodiments a method of making blow molded plastics, comprises the steps of supplying a parison to a mold, supplying a blow stem with pressurized air, and forcing the parison to conform to the mold. Once the parison has conformed to the mold, the parison is allowed to stabilize within the mold. Then a cooling airflow is created within the mold to cool and cure the parison and cool the mold. Once the parison is cured the cured parison (blow molded plastic part) is removed from the mold. 
         [0011]    One object of the present invention is to decrease cycle time for manufacturing blow molded plastic products. The systems, devices, and methods disclosed herein enable a decrease in cycle time of at least one second. The decrease in cycle time is provided by the introduction of a cooling air flow to the internal cavity of a blow molded parison. As those skilled in the art will appreciate, the volume of the internal cavity of the blow molded parison effects the decrease in cycle time of the devices, systems, and methods disclosed herein. In particular, the devices, systems and methods disclosed will provide decreased cycle times, between, approximately 10 percent and 35 percent. Various factors dictate the overall decrease in cycle time achieved by the disclosed devices, systems, and methods, including but not limited to, for example, the temperature of the parison, temperature of the supply air, wall thickness of the plastic part being formed, the geometry of the blow molded plastic part, the internal volume of the blow molded parison, the number, size, configuration, and shape of the blow stem(s), flow rate of the cooling fluid flow, the controls in use, the ambient conditions, and/or the like. In one embodiment, the cycle time for blow molding a thin walled one gallon plastic container is decreased by approximately 20 percent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar elements throughout the Figures, and: 
           [0013]      FIG. 1  illustrates an exemplary block diagram of a blow mold system in accordance with an exemplary embodiment; and; 
           [0014]      FIG. 2  illustrates a side-view cross section of an exemplary blow stem in accordance with another exemplary embodiment; 
           [0015]      FIG. 3  illustrates a top-view cross section of an exemplary blow stem in accordance with another exemplary embodiment; 
           [0016]      FIG. 4  illustrates an exemplary schematic of a blow mold system in accordance with another exemplary embodiment; 
           [0017]      FIG. 5  illustrates another exemplary schematic of a blow mold system in accordance with another exemplary embodiment; 
           [0018]      FIG. 6  illustrates yet another exemplary schematic of a blow mold system in accordance with another exemplary embodiment; and 
           [0019]      FIG. 7  illustrates a block diagram of an exemplary method of blow molding. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0020]    The following is a description of exemplary embodiments of the invention only, and is not intended to limit the scope or applicability of the invention in any way. Rather, the following description is intended to provide convenient illustrations for implementing various exemplary embodiments of the invention. As will become apparent, various changes may be made to methods, structures, topologies, and compositions described in these exemplary embodiments without departing from the spirit and scope of the invention. 
         [0021]    In general, systems, methods, and devices are suitably configured to facilitate the production of blow molded plastics. The production may provide for the rapid manufacture of plastic products with hollow internal cavities. Production of blow molded plastics may be facilitated, for example, through use of blow molding and/or blow forming, and in particular though extrusion blow molding, injection blow molding, stretch blow molding and/or the like, such that the production results in a finished plastic part. 
         [0022]    For example, the device and/or system may be configured to provide a supply of compressed fluid to a parison such that the parison is forced and/or stretched to conform to a mold. Further, the device and/or system may be configured to exhaust the pressurized fluid from the internal cavity of the parison, while supplying a cooling fluid flow, such that a sufficient internal pressure is maintained to retain the shape of the parison in the mold. The cooling fluid flow may provide convective cooling and/or conductive cooling. This “internal” cooling, in addition to any other cooling that may be used, facilitates faster production of plastic parts compared to processes that do not use internal cooling processes. Once the parison has been sufficiently cooled, the system is configured to expel the plastic part from the mold. Consequently, the production devices, systems, and methods described herein may provide for reduced costs in the manufacture of blow-molded plastics and/or provide for higher production yields of blow molded plastics parts. 
         [0023]    Although described herein in the context of blow molded plastics, it should be understood that the techniques described herein may work in other contexts and that the description herein related to blow molded plastics may be similarly applicable to any manufactured product and or system, wherein the product produced has internal cavity formed by contacting the raw material with a compressed fluid such that the raw material is forced and/or stretched to conform to a mold and cooled to cure, in order to retain the shape of the mold. 
         [0024]    Blow mold systems exist in various configurations, with a variety of components and performance factors. Nevertheless, an exemplary blow mold system is briefly described here. An exemplary blow mold system may comprise one or more blow stems coupled to a fluid chamber. The fluid chamber may be coupled to a fluid inlet and a fluid outlet. The fluid inlet may be coupled to a compressed fluid supply and a controller, such that the compressed fluid supply is capable of providing a supply of compressed fluid to the fluid chamber in accordance with instructions from the controller. The fluid outlet may be coupled to a control module. The control module may also be coupled to a controller, such that the controller is configured to modulate the fluid outlet. Finally, an exemplary blow mold system may comprise a mold operatively coupled to the blow stem and configured to receive a parison. 
         [0025]    Referring to  FIG. 1 , and in accordance with an exemplary embodiment, a blow molding system  100  may comprise a blow stem  110 . Blow molding system  100  may further comprise a mold  160 . Mold  160  may be in fluid communication with blow stem  110 . 
         [0026]    Blow stem  110  may be any structure comprising a supply port and an exhaust port. In various exemplary embodiments, blow stem  110  may be, for example, a blow pin, a blow stem, a blow needle, a stretch pin, and/or the like. In an exemplary embodiment, blow stem  110  is a bidirectional blow stem. As such, the bidirectional blow stem allows for airflow in at least two directions. Blow stem  110  may be a pair of pipes, tubes, and/or similar structures. Blow stem  110  may be configured to conduct a fluid from a fluid supply through a supply port to a mold. Further, blow stem  110  may be configured to exhaust a fluid from a mold through an exhaust port to a fluid outlet. 
         [0027]    Referring to  FIGS. 2 and 3 , and in one exemplary embodiment, blow stem  110  may comprise a flange  220 , one or more exhaust ports  210 , and one or more supply ports  200 . Flange  220  may be an annular structure coupled to supply port  200  and configured with one or more exhaust ports  210 . In one exemplary embodiment, flange  220  may be configured with any number of exhaust ports  210 , for example, one to twelve exhaust ports  210 . In one exemplary embodiment, flange  220  may comprise an attachment system, such as a thread, a set screw mechanism, a detent mechanism, a press fit configuration, a configuration suitable for applying a weld, braze, adhesive, and/or the like, and/or similar mechanical, electro-mechanical, and/or chemical attachment systems. The attachment system of flange  220  may be configured to allow blow stem  110  to be removably coupled to a fluid supply. Supply port  200  may be a nozzle, tube, and/or similar structure. Supply port  200  may be in fluid communication with a fluid supply and conduct the fluid supply to mold  160  containing a parison. Stated another way, supply port  200  may be configured to supply a fluid supply to inflate the parison with the mold. Exhaust port  210  may be a through hole, passage, channel, and/or the like. Exhaust port  220  may be configured to exhaust and conduct a fluid from mold  160  to a fluid outlet. 
         [0028]    Referring again to  FIG. 1 , and in accordance with various exemplary embodiments, mold  160  is any structure with an internal cavity having an internal geometry conforming to the exterior of a part to be manufactured. Mold  160  may be in fluid communication with blow stem  110  and configured to receive a parison. As such, compressed fluid supplied through blow stem  110  stretches and/or forces the parison to conform to the internal cavity of mold  160 . In an embodiment, mold  160  may have an internal cavity that defines the exterior shape of a plastic part to be blow molded. As such, the internal cavity may take the shape of any plastic part capable of being blow molded, such as, for example, a milk jug, a carbonated beverage bottle, a watering can, a storage container, and/or the like. In an embodiment, mold  160  may be in fluid communication with one or more blow stems  110 . Mold  160  may be configured with a cooling system. The cooling system may be a channel contained between the internal cavity and the exterior surface, such that the channel may be configured to transport cooling fluid through the mold. The cooling system may also be a fluid bath, such that the exterior surface of the mold is bathed in a cooling fluid to provide conductive and/or convective cooling. 
         [0029]    In accordance with various exemplary embodiments, blow molding system  100  may further comprise a fluid inlet  140 , and a fluid outlet  150 . Fluid inlet  140  may be any structure suitable for supplying a fluid. Fluid inlet  140  may be, for example, a pipe, a tube, a hose, a conduit, a coupling, a fitting, a valve, and/or the like. Fluid outlet  150  may be any structure suitable for exhausting a fluid. Fluid outlet  150  may be, for example, a pipe, a tube, a hose, a conduit, a coupling, a fitting, a valve, and/or the like. The fluid may be any gas and/or liquid suitable for use in a system for blow molding plastics, such as, for example, air, nitrogen, water, and/or the like. In an exemplary embodiment, the fluid supplied to fluid inlet  150  is air. Although described hereinafter as air, it should be understood that this description is also applicable to other gases and fluids. Fluid inlet  140  may be in fluid communication with blow stem  110  at supply port  200 . In one exemplary embodiment, fluid inlet  140  may be configured to supply air to supply port  200 , such that, the supply stretches and/or forces a parison to conform to mold  160 . In various embodiments, fluid inlet  140  may be configured to supply compressed air at a temperature of between, approximately  65  degrees Fahrenheit and  260  degrees Fahrenheit, where the temperature range provided, is the temperature range of the fluid prior to the air contacting the parison. Moreover, in various embodiments, the temperature of the air supplied to fluid inlet  140  may be any temperature suitable for cooling in parison. Fluid outlet  150  may be in fluid communication with blow stem  110  at exhaust port  210 . In one exemplary embodiment, fluid outlet  150  may be configured to exhaust air through exhaust port  210 , wherein, a cooling airflow is created within the parison, where the parison has conformed to mold  160 . 
         [0030]    Referring still to  FIG. 1 , and in accordance with an exemplary embodiment, blow molding system  100  may further comprise a fluid conduit  120 , a fluid control device  130 , and a controller  170 . Fluid conduit  120  may be operatively coupled to fluid inlet  140  and fluid outlet  150 . Further, fluid conduit  120  may be in fluid communication with blow stem  120 . Fluid control device  130  may be operatively coupled to fluid outlet  140  and controller  170 . 
         [0031]    Referring to  FIG. 4 , and in accordance with various exemplary embodiments, fluid conduit  120  may be any structure capable of conducting and exhausting air to and/or from blow stem  110 . In an embodiment, fluid conduit  120  comprises a supply channel  400  and an exhaust channel  410 . Supply channel  400  may be in fluid communication with fluid inlet  140  and blow stem  110 . In accordance with one exemplary embodiment, supply channel  400  may be configured such that it conducts an air supply from fluid inlet  140  to blow stem  110 . Fluid conduit  120  is configured such that air can be supplied to supply port  200  to maintain a pressure within mold  160  for a specified time. Thereafter, the air is exhausted through exhaust port  210 . As a result, the exhausted air creates a cooling airflow. The cooling airflow is conducted through exhaust port  210  to fluid outlet  150 . The cooling airflow may be managed and/or modulated by fluid control device  130  in conjunction with controller  170 . 
         [0032]    In accordance with various exemplary embodiments, fluid control device  130  may be any structure capable of directing and/or modulating fluid flow. In an exemplary embodiment, fluid control device  130  comprises a pressure vessel coupled to one or more valves  420 . Fluid control device  130  may be coupled to controller  170  and fluid outlet  150 . Valve  420  may be a pressure regulator, for example, a flow control valve, a dump valve, and/or the like. Fluid control device  130  may be configured, such that a fluid exhausted through exhaust port  210  and exhaust channel  410  is managed and/or modulated by valve  420 . Valve  420  is configured to control the air flow from fluid outlet  150  and exhaust channel  410 , such that, a specified pressure is maintained in the parison and sufficient cooling air flow is provided to the parison. 
         [0033]    Referring still to  FIG. 4 , and in accordance with various embodiments, controller  170  may be any structure or system configured to regulate, direct, control, command, organize, manage, and or the like, any variable or monitor-able component of a blow molding system. In one exemplary embodiment, controller  170  may be operatively coupled to fluid inlet  140 , fluid outlet  150 , fluid control device  130  and valve  420 . Controller  170  may be configured to monitor and/or modulate, at least one of fluid inlet  140 , fluid outlet  150 , and fluid control device  130 . Controller  170  may be, for example, a timer, a digital controller, an analog controller, a computer and/or the like. Selection of an appropriate controller will depend on many factors including the number of parameters to be managed and/or monitored, the configuration of variable components, and the outputs provide by monitor-able components, among other factors. In an exemplary embodiment, controller  170  is a JZ10-11-UN20 programmable logic controller and/or a JZ10-11-UA24 programmable logic controller provided by Unitronics, Inc., with an address at 1 Batterymarch Park, Quincy, Mass., 02169. 
         [0034]    In various embodiments, the blow molding system may comprise one or more sensors (not shown). The sensors may be any monitoring device suitable for measuring system parameters, such as, for example temperature, pressure, fluid flow rate, and/or the like. The sensor may be operatively coupled to controller  170 . Controller  170  may be configured to monitor and/or record data associated with the system parameters monitored by the sensor. As such, controller  170  is configured to control the system parameters by adjusting one or more variable components of blow mold system  100 , such as, for example, fluid inlet  140 , fluid outlet  150 , and/or fluid control device  130 . 
         [0035]    In accordance with various embodiments, mold  160  may comprise a cooling system  430 . In one exemplary embodiment, cooling system  430  may be a channel within mold  160 , located between the interior cavity and the exterior surface of mold  160 . Alternatively, cooling system  430  may be a water bath. Cooling system  430  may be configured to supply cooling fluid to mold  160 . Mold  160  may further comprise parison  440 . Parison  440  may be in fluid communication with supply port  200 . When fluid is supplied through supply port  220 , parison  440  is stretched and/or forced to conform to the surface defining the internal cavity of mold  160 . Similarly, exhaust port  210  may be in fluid communication with the internal cavity of mold  160  and fluid control device  130 . As such, the blow molding system may be configured to create a cooling airflow in the internal cavity of mold  160  through exhaust port  210  where valve  420  is modulated by controller  170 . 
         [0036]    Referring to  FIG. 5 , and in accordance with an exemplary embodiment, blow molding system  100  may further comprise a pressure gauge  500 . Pressure gauge  500  may be operatively coupled to fluid control device  130 . Alternatively, pressure gauge  500  may be couple to fluid outlet  150 . In either embodiment, pressure gauge  500  may also be coupled to controller  170 . Controller  170  may be configured to monitor the pressure measured by pressure gauge  500 . Blow molding system  100  may also comprise an exhaust handler  510 . Exhaust handler  510  may be operatively coupled to fluid control  420 . Exhaust handler  510  may be configured such that air exhausted through fluid control  420  is conditioned by exhaust handler  510 . In accordance with various embodiments, exhaust handler  510  may be a muffler, a pressure vessel, and/or the like. 
         [0037]    Referring to  FIG. 6 , and in accordance with an embodiment, blow molding system  100  may further comprise a fluid bypass  600 . Fluid bypass  600  may be coupled to fluid inlet  140  and fluid outlet  150 . Fluid bypass  600  may further comprise fluid control  610  coupled to fluid outlet  150 . Fluid control  610  may be a valve or other fluid control device. Fluid control  610  may be in fluid communication with fluid inlet  140  and fluid outlet  150  and operatively coupled to controller  170 . Fluid control  610  may be configured to manage and/or modulate a supply of fluid to exhaust channel  410  through fluid outlet  150  at a specified condition. As such, fluid control  610  is configured to provide supply air through fluid outlet  150  initially. Thereafter, fluid control  610  may be modulated to allow for exhaust flow through fluid outlet  150 . 
         [0038]    Referring to  FIG. 7 , and in accordance with an embodiment, blow molding method  700  may comprise supplying parison  440  to mold  160  (step  710 ). Thereafter, pressurized air is supplied to blow stem  110  (step  720 ). The pressurized air, forces parison  440  to conform to mold  160  (step  730 ). Parison  440  is then allowed to stabilize in the mold (step  740 ). For example, the parison is allowed to stabilize in the mold sufficiently that air circulation within the parison would not cause the parison to deform significantly. Significant deformation would be any deformation outside of acceptable tolerances for the end product. After parison  440  is stabilized, an airflow is created within the internal cavity of mold  160  to cool and cure parison  440  (step  750 ). Parison  440  can then be removed from mold  160  (step  760 ). As such, the blow molding method  700  provides for efficient manufacturing of blow molded plastic products. 
         [0039]    The present invention may be described herein in terms of functional block components, optional selections and/or various processing steps. It should be appreciated that such functional blocks may be realized by any number of hardware and/or software components suitably configured to perform the specified functions. For example, the present invention may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements, look-up tables, and/or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, the software elements of the present invention may be implemented with any programming or scripting language such as C, C++, Java, COBOL, assembler, PERL, Visual Basic, SQL Stored Procedures, extensible markup language (XML), with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Further, it should be noted that the present invention may employ any number of conventional techniques for data transmission, messaging, data processing, network control, and/or the like. 
         [0040]    For the sake of brevity, conventional data networking, application development and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections might be present in a practical blow molding system. 
         [0041]    The description of various embodiments herein makes reference to the accompanying drawing figures, which show the embodiments by way of illustration and not of limitation. While these embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the invention. Thus, the disclosure herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not limited to the order presented. Moreover, any of the functions or steps may be outsourced to or performed by one or more third parties. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component may include a singular embodiment. 
         [0042]    Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the invention. The scope of the invention is accordingly to be limited by nothing other than the claims that may be included in an application that claims the benefit of the present application, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, and C” may be used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Although certain embodiments may have been described as a method, it is contemplated that the method may be embodied as computer program instructions on a tangible computer-readable carrier and/or medium, such as a magnetic or optical memory or a magnetic or optical disk. All structural, chemical, and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are contemplated within the scope of this disclosure.