Abstract:
A spray system for a molding process applies mold release agent to a surface of a mold to assist in release of a molded article from the mold. The spray system includes a spray head attached to a frame member. The spray head is vertically movable with respect to the frame member. The spray head includes a plurality of nozzles for outputting mold release agent. A mold release agent source provides mold release agent to a mold release dosing device. The dosing device provides select quantities of mold release agent through a conduit to a manifold mounted on the spray head. The manifold includes a plurality of valves leading to a plurality of nozzles. Then the dosing device outputs a predetermined amount of mold release agent to the manifold through the conduit. In operation, the spray system provides an air input to the dosing device to remove any mold release agent therefrom and to flush mold release agent from the conduit and manifold outwardly through the nozzles. Thus, a precise quantity of mold release agent is obtained in the dosing device and provided to a surface of a mold.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/199 980, filed Nov. 22, 2008, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is related generally to a spray system including a dosing device for applying a predetermined amount of release agent to predetermined regions of a mold in order to provide a more uniform amount of release agent on a mold surface. 
       BACKGROUND OF THE INVENTION 
       [0003]    The molding of parts, such as for use in automobiles is well known. One example of molding includes the steps of opening a mold, applying a release agent thereto, and closing the mold while providing a molding material, such as a heated stream including magnesium inside the mold. 
         [0004]    One known spray system for applying a release agent within a mold includes a guide shaft unit having a guide shaft vertically movable so that a lower end thereof can be introduced within a mold that is in an open position. The lower end of the guide shaft includes a spray head with nozzles for applying a release agent combined with an air pressure flow onto surfaces of a mold. The spray head has a separate set of air blow nozzles for applying air to spread the release agent on the mold surfaces. 
         [0005]    Such known spray systems further include an up pressure valve, a down pressure valve and a pressure adjustment mechanism for applying pneumatic air to move the guide shaft upwardly or downwardly. The spray system also receives pneumatic air pressure from a compressor that is utilized to provide pressure to an up pressure valve or a down pressure valve for moving the spray unit upwardly or downwardly. The valve arrangement can control the speed and amount of movement upwardly or downwardly for the guide shaft. 
         [0006]    Further, the guide shaft unit includes a spray situation adjustment screw for controlling the amount of spray applied by the spray system. 
         [0007]    The spray system includes a spray unit that receives release agent from a container or other source via a conduit that includes a spray adjustment screw. The spray unit includes a master valve for introducing air into the spray unit. Release agent simply passes through a liquid valve to a manifold or a spray head that receives both release agent via the liquid valve and air traveling through the master valve to apply the release agent to a user. 
         [0008]    The pneumatic pressure is supplied to the spray unit and advanced to the manifold, along with a release agent for providing a mold release. The release agent and air combine in the manifold and are output by spray nozzles of the spray head onto a mold. The pressurized air exiting the nozzle has a vacuum effect on the mold release agent in a conduit providing the mold release agent to the manifold. Thus there is a delay in the output of mold release agent from the nozzles of the spray unit. 
         [0009]    Finally, pneumatic air is provided to an air blow valve for selectively applying air through additional air blow nozzles to a previously applied release agent disposed at a lower end of the movable spray unit to apply air to spread the release agent throughout the mold. 
         [0010]    Due to a number of factors, accuracy for the quantity of release agent applied to a mold is difficult to obtain, much less predict. One factor is a significant distance between the liquid valve for the release agent and the location of the spray head nozzle. A large quantity of release agent is provided in the connecting line between the valve and spray head. The amount of the release agent that remains in the line or is output through the spray nozzles by a Venturi effect is not predictable. Thus, the amount of release agent applied to a mold can differ significantly and is unpredictable. 
         [0011]    Another factor affecting accuracy of the release agent, when multiple spray units are provided sharing the same pneumatic air source. Depending on the predetermined operating times for the multiple spray units, the pressure output values from a compressor air source can vary and thus vary the pressure applied to force a mold release agent. His factor may result in improper quantities out a spray nozzle. 
         [0012]    In this known arrangement, the amount of pressure of the mold release agent and the time that the liquid valve is open, along with the pressure valve of the air provided by the air blow valve, result in variation of the quantity of release agent applied from the spray head. 
         [0013]    As to other factors, fluid pump pressure of the mold release agent, air pump pressure of a compressor, the opening and closing times of valves for air, for control and for operation of a valve for a mold release, and even adjustable nozzle flow settings are all inexact factors that may lead to inaccuracy in the amount of mold release agent applied to a mold. 
         [0014]    An object of the invention is to provide a spray system wherein an exact dosage of release agent is applied to a mold at each application cycle. 
         [0015]    Another object of the invention is to reduce the sticking of parts formed within the mold due to a lack of mold release agent thereon. Further, the proper amount of mold release enables better flow of casting material within the die and results in a more constant temperature or temperature range within the die to more uniformly provide a predetermined cooling effect for the die that prevents overcooling or overheating, which wears a die or mold prematurely. 
         [0016]    Another object of the invention is to minimize energy use, such as by generally not requiring a separate blow off process utilizing the separate blow off nozzle. Further, the amount of noise is reduced by Applicant&#39;s claimed invention. 
         [0017]    Another object of the invention that is obtained by sharing the same nozzles for applying release agent and air is that the air is sprayed exactly where the mold was applied to improve the spreading of the mold onto the mold surfaces. Besides magnesium, zinc and aluminum, there are other metals that can be used in die cast molding embodiments. 
         [0018]    Another object of the invention is to ensure that the mold release pump pressure and mold release timing for applying release agent from a nozzle are not critical to the amount or dose of release agent applied therefrom. 
         [0019]    In one embodiment, a dosing device is mounted to the movable spray unit to minimize the length of a connecting line between the dosing unit and the spray head thereof. 
         [0020]    In another embodiment of the invention, air is provided through the mold release agent connecting line to remove essentially all release agent from the conduit and to apply same onto the mold. 
         [0021]    In another embodiment of the invention, the speed/cycle time for operation of the spray unit and molding device is improved. 
         [0022]    Another embodiment of the invention provides the proper amount of mold release to the inner surface of a mold so that, for example, in the instance of a die cast material including magnesium, little fluid is left over in the mold, which prevents magnesium from exploding due to the over saturation of the die with a mold release. 
         [0023]    The embodiments that include flushing or removing release agent from the fluid line connected to the spray heads lead to improved accuracy, and better conditioning of the flow line, as air is blown through the same nozzles that apply the release agent. 
         [0024]    Some of the embodiments utilize reaction injection molding (RIM), but the claimed invention may be utilized to apply a release agent to cooking molds used in commercial bakeries or to other areas that require application of an even amount release agent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a perspective view showing one embodiment of a spray system including vertically movable spray head having a dosing device. 
           [0026]      FIG. 2  is a perspective view showing a view of a mold release spray system provided in a position above a die cast machine. 
           [0027]      FIG. 3  shows a pneumatic diagram of the spray system including a dosing device, along with a spray manifold and a blow off manifold. 
           [0028]      FIG. 4  is a block diagram of an electronic control circuit of the invention. 
           [0029]      FIG. 5  is a flow chart showing an operation of the spray system. 
           [0030]      FIG. 6  is a flow chart describing a release agent spray subroutine for the dosing device that is illustrated in  FIG. 3 . 
           [0031]      FIG. 7  is a cross-sectional view of a dosing quantity meter device. 
       
    
    
       [0032]    Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement, and designated parts thereof. Said terminology includes the word specifically mentioned, derivatives thereof, and words of similar input. 
       DETAILED DESCRIPTION 
       [0033]      FIGS. 1 and 2  depict a spray system  10  of the invention. Spray system  10  is designed to provide a precise coating of a release agent to inner surfaces of molds to enable release of a molded object therefrom after completion of a molding process. 
         [0034]    The spray system  10  includes a support structure for securing the system onto a floor. The support structure of the spray system  10  includes a fixed mount  12  and a pivoting base  14  disposed thereon that is rotatable relative to the mount  12  about an upwardly oriented axis. The support structure further includes a plate  16  that is pivotable along with the base  14 . The plate  16  has mounted thereon a vertically oriented support  18  and has an angled support  20  secured thereto. 
         [0035]    As shown in  FIG. 2 , the support structure of the spray system  10  includes a horizontal support  22  joined between an end of the angled support  20  and a midsection of the support  18 . A front vertically oriented support element  24  extends upwardly from the distal end of the angled support  20 . An upper horizontal support member  26  joins the top end of front support  24  to an upper end of support  18 . Lower horizontal support bushings  28   a,    28   b  are provided horizontally spaced and opening in alignment with each other. A lower horizontal travel guide shaft  30  extends through the pair of bushings. Upper horizontally spaced travel support bushings  32   a,    32   b  receive an upper horizontal guide shaft  34 . A horizontally oriented driving shaft  36  is disposed in parallel with and between the lower and upper horizontal guide shafts  30 ,  34 . Proximal ends of the guide shafts  30 ,  34  and the driving shaft  36  are affixed to frame member  38 . A horizontal linear actuator  40  coacts with the driving shaft  36  for horizontally extending and retracting the driving shaft along the length thereof. Thus the driving shaft  36  moves the fixed frame member  38  horizontally relative to the mounting structure, including the mount  12  and pivotable base  14 . 
         [0036]    The frame member  38  receives a vertically movable frame  42  that is supported thereon. As shown in  FIG. 1 , the vertically movable frame  42  includes a spray head  43  mounted at a bottom edge thereof. A vertical linear actuator  44  moves the vertically movable frame  42  and thus the spray head  43  upwardly and downwardly. 
         [0037]    As shown in  FIG. 1 , a pair of vertically oriented legs  46 ,  48  joined at lower ends thereof by a cross piece  50  and joined at an upper end by upper horizontal cross piece  52  and, in combination, form the spray head  43  having a rectangular shape. A quick release mechanism  54  secures an upper part of the spray head  43  to the bottom of the movable frame  42 . 
         [0038]    Electrical power cables provide power to the linear actuators  40 ,  44 , a dosing device  60  and other powered devices of the spray system  10 . 
         [0039]    The dosing device  60  is mounted to the upper horizontal crosspiece  52  of the spray head  43 . Hoses  62 ,  64  provide mold release agent such as air. Hose  66  provides gas to the spray system  10 . A cat track  70  illustrated in  FIG. 2  carries air hoses, mold release hoses and power lines. 
         [0040]    Turning to  FIG. 1 , the spray head includes a spray manifold  72  that receives a plurality of variable length spray nozzle elements  74   a - 74   g.  Each of the spray nozzle elements  74   a - 74   g  has a spray nozzle  76   a - 76   g  oriented horizontally at the respective lower ends thereof. A plurality of dial elements  80 , shown in  FIG. 1 , provides manual adjustment of the respective spray valves  82   a - 82   f  illustrated in  FIG. 3 . 
         [0041]    Spray manifolds  72   a,    72   b  mounted horizontally at the top of the spray head  43  provide release agent to respective nozzle elements. Spray manifold  72   a  provides release agent to nozzles  76   a - 76   d  oriented in a first substantially horizontal direction. Spray manifold  72   b  provides release agent to nozzles  76   e,    76   f  oriented in an opposing horizontal direction with respect to nozzles  76   a - 76   d.    
         [0042]    While  FIG. 1  shows four nozzles  76   a - 76   d  oriented in a first horizontal direction and two nozzles  76   e,    76   f  oriented in a second opposing substantially horizontal direction, the invention contemplates the use of any number of nozzles oriented in either direction. 
         [0043]    Cross piece  50  at the lower end of spray head  42  contains a blow-off manifold  84  thereon. In some embodiments, the blow-off manifold  84  shown in  FIG. 3  replaces the lower cross piece  50  and acts as a support element for the spray head  43 . The blow-off manifold  84  includes blow-off nozzles  86   a,    86   b  oriented horizontally outwardly therefrom as shown in  FIG. 1  and blow-off nozzle  86   c  oriented in an opposing horizontal direction as shown in  FIG. 2 . In different embodiments, any number of blow-off nozzles  86  are provided and aligned in either substantially horizontal direction. 
         [0044]      FIG. 2  illustrates molding machine  90  including a pair of mold elements  92 ,  94  in an open position. 
         [0045]      FIG. 3  shows a valve arrangement and structure of dosing device  60  for providing release agent followed by air from the spray manifold  72   a,    72   b  and providing air from the blow-off manifold  84 . 
         [0046]    Pneumatic air compressor  100  in  FIG. 3  provides pressurized air through air conduit  102  to a high pressure two output air valve  104 . The two output air valve  104  is capable of selectively providing pressurized air to a high pressure blow-off manifold conduit  106  or to a high pressure spray manifold output conduit  108 . The high pressure blow-off manifold conduit  106  connects to the blow-off manifold  84 . The high pressure spray manifold output conduit  108  connects to the release agent spray manifolds  72   a,    72   b  as shown in  FIG. 3 . 
         [0047]    Dosing device  60  is illustrated in  FIG. 3  by a dosing device air and release agent circuit  109  shown in broken line. The dosing device circuit  109  includes a dosing device air conduit  110  that connects to a dosing device air feed valve  112 . The air feed valve  112  includes a bleed valve  113 . An air feed conduit  114  connects to a dosing quantity control unit  116  of the dosing device  60 . 
         [0048]    The dosing quantity control unit  116  includes a cylinder  118  having a piston defined by a piston head  120  and a piston shaft  122 . The piston head  120  has an O-ring positioned radially outwardly about the circumference thereof to provide a seal within the chamber formed within the cylinder  118 . A first end of the piston shaft  122  is secured to the piston head  120  and a second end of the piston shaft projects outwardly from a rear opening of cylinder  118 . A radially outwardly extending piston stop  124  is disposed at the end of the piston shaft  122  that projects from the cylinder  118 . A sealing element  126  provides a seal that isolates a chamber in the cylinder at the piston stop side of the cylinder  118  from outside areas during linear movement of piston shaft  122 . 
         [0049]    The dosing quantity control unit  116  further includes a mold release volume adjustment  128 . The mold release volume adjustment  128  includes a rotatable adjustment element  130  for moving a mold release full switch  132  linearly toward or away from the piston stop  124  of the quantity control unit  116 . In some embodiments, the piston stop  124  includes a magnet or other means thereon for magnetically actuating mold release full switch  132  or mold release dispensed switch  134 . In some embodiments, the mold release full switch  132  and mold release dispensed switch  134  optically sense the position of the piston stop  124  as the stop moves linearly with the piston shaft  122 . 
         [0050]    The dosing device circuit  109  further includes a dosing branch air flow conduit  136  that branches from the air feed conduit  114  and opens into a pressure regulator  138  including a pressure setting element  140 . Further, a pressure gauge  142  measures the air pressure thereat. An output side of the pressure regulator  138  connects to a check valve  144  that provides a flow path to a dosing side  146  of the piston head  120  within the cylinder  118 . The check valve  144  prevents a flow of release agent from the chamber at the dosing side  146  to the pressure regulator  138 . 
         [0051]    A mold release source or container  150  shown in  FIG. 3  provides a mold release agent driven by mold release pump  152  through mold release conduit  154 . The mold release conduit connects to an input port of a mold release 3-way valve  156 . 
         [0052]    The mold release 3-way valve  156  includes an output conduit  160  that provides a fluid connection to the dosing side  146  of the dosing quantity control unit  116 . The mold release 3-way valve  156  also switches and closes the port to the mold release conduit  154  and opens a separate connection to a spray head conduit  164 . The spray head conduit  164  connects to the release agent spray manifolds  72   a,    72   b  through a manifold arrangement  168  that essentially parallels the flow paths of the high pressure spray manifold output conduit  108  that connects to the spray manifolds  72   a,    72   b.    
       Electronic Control System  
       [0053]    The block diagram of  FIG. 4  shows the electronic control circuit  170  of the spray system  10 . The electronic control circuit  170  includes a dosing unit controller  174 , such as a programmable logic controller (PLC). The dosing unit controller  174  receives a plurality of inputs and provides a plurality of outputs to control the spray system  10 . 
         [0054]    Mold release agent full switch  132  and mold release agent dispensed switch  134  of the dosing quantity control unit  116  each provide an input  176 ,  178  to the dosing unit controller  174 . Further, a programmer input device  180 , such as a touchscreen or keyboard, provides an information or data input  182  to the controller  174  that includes parameters for the particular molds being utilized, parameters for the particular positions required for the spray head, parameters for the amount of spray for each of the spray nozzles, and information regarding cycle time for the spray system  10 . 
         [0055]    The dosing unit controller  174  receives an input  192  from frame member horizontal position sensor  190  and an input  195  from spray head vertical position sensor  194 . 
         [0056]    Dosing unit controller  174  communicates over signal path  184  with a molding machine controller  186 . The molding machine controller  186  controls the molding machine  90  to close the mold, inject molding material into the mold, determine completion of a molding process and open the mold. The molding machine controller  186  operates the molding machine  90  in an essentially known manner. 
         [0057]    The molding machine controller  186  and the dosing unit controller  174  communicate with each other to determine when spray system operations occur and when molding operations occur. Thus the controllers  174 ,  186  ensure essentially error free, fast operation of the respective machine  90  and spray system  10  for each molding cycle. 
         [0058]    The dosing unit controller  174  provides outputs  196 ,  198  to the horizontal linear actuator  40  and the vertical linear actuator  44 , respectively. 
         [0059]    The dosing unit controller  174  provides a control signal output  200  to the dosing device air feed valve  112  and provides a signal output  202  to the high pressure spray head multi-path air feed valve  104 . Further, the PLC  174  provides a control signal output  204  to the 3-way mold release valve  156 . 
         [0060]    As illustrated in  FIG. 4 , the dosing unit controller  174  receives inputs from the dosing unit switches  132 ,  134 , from molding machine controller  186 , from spray head horizontal position sensor  190 , and from spray head vertical position sensor  194 . 
         [0061]    In response to the input signals, the dosing unit controller  174  then provides outputs to control the spray system  10 . The dosing unit controller  174  provides control signals  196 ,  198  to the horizontal and linear actuators  40 ,  44  of the spray system  10  to move the spray head  43 , along with other moveable elements fixed thereto, upwardly and/or downwardly, as well as moving the fixed frame member  38  horizontally, if necessary, in order to position the spray head  43  inside an open mold. Further, the base  14  of the support structure pivots, if necessary, for alignment of the spray head  43  with a mold. 
         [0062]    In some embodiments, the horizontal and linear actuators  40 ,  44  are servomotors, such as step motors, to increase the speed and the overall position accuracy of the spray head  43  of the spray system  10 . Such an arrangement increases the number of operations or shots per minute of a molding machine  90  forming molded articles. 
       Spray System Operation  
       [0063]    Spray system  10  is controlled by dosing unit controller  174  as follows. At step  210  in  FIG. 5 , the spray head  43  of the spray system  10  is in the retracted, raised position when a manufacturing cycle for obtaining a molded article begins. At step  212 , dosing unit controller  174  operates the horizontal linear actuator  40  to move the frame member  38  horizontally, if necessary. Then the dosing unit controller  174  controls the vertical linear actuator  40  to move the spray head  43  downwardly to a deployed operating position. 
         [0064]    At step  214 , a spray subroutine executes to provide an exact quantity of release agent to the surface of inner walls of the mold elements  90 ,  92  as will be discussed below. 
         [0065]    At step  216 , air is output through blow-off nozzles  86   a,    86   b,    86   c  as the spray head  43  is raised to the retracted or stowed position shown in  FIG. 2  by vertical linear actuator  44 . The air provided through the blow-off nozzles  86   a,    86   b  typically is stopped by the dosing unit controller  174  before the spray head  43  exits the region of the open mold elements  92 ,  94 . 
         [0066]    At step  218 , the mold elements  92 ,  94  of the molding machine  90  close and the mold is filled with molding material. After a predetermined time, at step  222  the mold elements  92 ,  94  are opened by the mold operating controller  186 . Then at step  224  the molded article is removed. 
         [0067]    At step  226 , a molded article process cycle is finished and the process returns to step  210  to repeat the cycle and form additional molded articles. 
       Spray Subroutine 
       [0068]      FIG. 6  shows a release agent spray subroutine of the invention. At step  250 , the spray subroutine starts with the spray head in a downward deployed position between or within the mold elements. 
         [0069]    At step  250 , the dosing quantity control unit  116  is in the release agent loaded position. The piston head  120  is retracted so that the piston stop  124  is in alignment with the mold release full switch  132 . The dosing side  146  of the piston head  120  is filled with mold release agent. At step  250 , dosing device air feed valve  112 , the high pressure two output air valve  104  and the mold release 3-way valve  156  are in closed positions. 
         [0070]    At step  252  mold release agent is sprayed. The dosing device circuit  119  is controlled by the dosing unit controller  174  to open mold release 3-way valve  156  to provide a flow path from the dosing side  146  of the piston, through fluid output  160  and along spray head conduit  164  to the release agent spray manifold  72   a,    72   b.  Thus, the release agent at the dosing side  146  has an open path to the spray manifold  72   a,    72   b.  Then dosing device air feed valve  112  opens to provide high pressure air along air feed conduit  114  and into the side of the piston head  120  including the piston shaft  122 . The air applied into the cylinder  118  forces the piston head  120  to move rightwardly to the position shown in  FIG. 3 , which forces the mold release agent from the dosing side  146  of the piston head  120  into the fluid output  160  and through the 3-way valve  156  along spray head conduit  164  to the mold release agent spray manifold  72   a,    72   b.  The release agent then passes through the appropriate valves  82   a - 82   f.  At essentially the same time, high pressure two output valve  104  provides air through pressure spray manifold output  108  to the spray manifolds  72   a,    72   b.  The air or gas combines with the mold release agent to form a mist that is output by the nozzles  76   a - 76   f.    
         [0071]    At decision step  253 , the dosing unit controller  174  determines if the end of the piston shaft  122  is adjacent the dispensed switch  134  so that the switch is on, which indicates complete piston travel. If not, the spray subroutine  214  returns to step  252 . When the dosing unit controller  174  senses that the dispensed switch is on, the spray subroutine  214  advances to step  254 . 
         [0072]    At mold release agent flushing step  254 , the piston head  120  is in the closed position illustrated in  FIG. 3 . The air that closed the piston now provides a force or pressure through dosing branch air flow conduit  136  to the pressure regulator  138 . The pressure regulator  138  is adjusted so that, after movement of the piston to the closed position, a flow of air passes through check valve  144  and into the dosing side  146  of the piston. This air flushes any remaining release agent within the dosing side of the piston head  120 , and any release agent within the fluid output conduit  160  and the spray head conduit  164 , outwardly through nozzles  76   a - 76   f  of the release agent spray manifolds  72   a,    72   b.  The dosing unit controller  174  typically flushes the spray head conduit  164  for a predetermined time. While the spray head conduit  164  is being flushed, the high pressure two output valve  104  continues to provide air through spray manifold output  108  to the release agent spray manifolds  72   a,    72   b.    
         [0073]    After the mold agent flushing step  254 , the spray subroutine  214  advances to step  256 . At step  256 , the dosing device  60  sprays air through blow-off nozzles  86   a - 86   d  by switching the dosing device air feed valve  112  to provide air through high pressure blow-off line  106  to the blow-off nozzles. Blow-off continues for a predetermined time. 
         [0074]    Meanwhile during step  256 , or afterward at step  258 , the unit controller  174  switches the mold release 3-way valve  156  to close the path to spray head conduit  164  while opening the path from mold release conduit  154  to fluid output  160 . 
         [0075]    At release agent load recovery step  258 , the path from the mold release storage container  150  is open to the dosing side  146  of the release agent as set forth above. At the same time, dosing device air feed valve  112  is closed. The air feed valve  112 , however, includes a bleed valve  113  that enables air in the cylinder  118  on the driving side of the piston head to evacuate from the air feed conduit  114 . As the mold release agent enters the dosing side  146  of the piston, the piston head  120  and the piston shaft  122  move leftwardly from the position shown in  FIG. 3  toward a loaded position. 
         [0076]    At step  260 , the dosing unit controller  174  senses if the mold release full switch  132  is on. If not, the dosing unit controller  174  returns to step  258 . When the piston stop  124  is alignment with the mold release full switch  132  at decision step  260 , the dosing unit controller  174  advances to step  262 . 
         [0077]    At step  262 , at least the mold release 3-way valve closes to maintain the mold release agent in the dosing side  146  of the dosing quantity control unit  116 . 
         [0078]    The above spray subroutine  214  enables an exact quantity of release agent to be loaded on the dosing side  146  of the piston head  120 . Further, by flushing the fluid output and spray head conduit line  164  with air, all of the release agent provided in the dosing side  146  of the cylinder is applied to mold surfaces of mold elements  92 ,  94  through the nozzles  76   a - 76   f.    
         [0079]    The immediate application of force by the piston to the dose at the beginning of a mold release spray cycle results in essentially immediate output of a large quantity of the dose of mold release agent. As compared to the known system discussed above, the immediate output results in a shorter time period for the application of a predetermined amount of mold release agent. 
         [0080]    Moreover, a force applied to output the dose from the dose quantity control unit to begin spraying, generally has a force greater than the force of the pressurized air being provided to spray manifolds  72   a,    72   b  at least for a portion of the time period that the mold release agent is applied to a mold. 
         [0081]    Further, the application of force to the dose results in a more uniform application of the mold release agent. Thus no output or less output of air by the blow-off nozzles  86   a,    86   d  is necessary. 
       Spray System Set-up 
       [0082]    Before operating the spray system  10 , mold release volume adjustment  128  is moved by rotating adjustment element  130  to vary the length of the stroke of the piston by limiting movement of the piston shaft  122 . Mold release full switch  132  typically moves in correspondence with the mold release volume adjustment  128  so that the position of the piston shaft  122  is detected when the dosing side  140  of the cylinder  118  is completely filled with mold release agent. 
         [0083]    Dials  80  are provided to adjust the valves  82   a - 82   f  to control the quantity of mold release agent from each nozzle  76   a - 76   f.    
       Alternatives 
       [0084]    While  FIG. 3  shows the dosing quantity control unit  116  as a piston arrangement, other precision dosing quantity embodiments are contemplated. 
         [0085]    In one embodiment, a rotating dosing quantity metering device  300  shown in the cross-sectional view of  FIG. 7  includes a cylinder including a cylindrical wall  302 . Within the cylinder is a removable rotating mold release quantifying element  306 . The quantifying element  306  includes a plurality of symmetrically spaced dosing compartments  308 A- 308 D that open radially outwardly toward the cylindrical wall. 
         [0086]    The quantity metering device  300  includes a mold release agent air drive aperture  312  illustrated at dosing compartment  308 C for forcing release agent out of the dosing compartment  308 C and into a mold release output line  316 . 
         [0087]    A bleed value is disposed within the cylinder adjacent an opening in the wall connected to a mold release input line  314 . The bleed valve permits air removal from the dosing compartment  308 A when mold release agent is forced into the compartment from the mold release input line  314 . Drive shaft  310  is provided for rotating the mold release quantifying element  306 . 
         [0088]    In operation, the mold release quantifying element  306  rotates to a position whereat empty dosing compartment  308 A is filled with mold release agent while mold release agent is being removed from compartment  308 C by air provided from aperture  312 . The mold release agent travels through mold release output line  316  to spray manifolds. 
         [0089]    In one embodiment a drive device, such as a servomotor, is provided to move the piston head  122  of the dosing quantity control unit  116 . In such an embodiment, the dosing unit controller  174  maintains the position of the piston head  122 , and full switch and dispensed switch  132 ,  134  are not necessary. Further adjustment of the predetermined amount of release agent for each dose is accomplished by the dosing unit controller  174  controlling the servomotor. 
         [0090]    In another embodiment, the shaft  310  of the quantity metering device  300  in  FIG. 7  is driven by a drive device, such as a servomotor. 
         [0091]    Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.