Abstract:
A production coater for coating a material with a solution or a suspension. The production coater including a cabinet with an integrated exhaust plenum providing an exhaust flow path from a coating drum to an output of the production coater. The production coater and the integrated exhaust path provides a system for coating materials with a solution that includes a reduced number of parts, simplified cleaning, service and maintenance, and does not require the lifting of heavy parts as is required of previously known production coaters.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This Application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/148,602, filed on 16 Apr. 2015. The co-pending U.S. Provisional Patent Application is hereby incorporated by reference herein in its entirety and is made a part hereof, including but not limited to those portions which specifically appear hereinafter. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to an exhaust plenum and cabinet assembly for a production coater for coating a material to be coated with a solution or a suspension. This invention includes an exhaust plenum integrated with a cabinet to provide an air flow path for exhaust from a drum in the production coater. 
         [0004]    2. Discussion of Related Art 
         [0005]    Fully-perforated side-vented coating pans and coaters have been in use since the early 70&#39;s. In the past, such coaters for coating pharmaceuticals and other substrates were expensive, complex, difficult to clean and included a multiplicity of parts. The apparatus of the prior art are inherently expensive, inflexible, difficult to operate properly, difficult to clean and sized to a specific application. Traditional coaters include a separate exhaust plenum that can be inserted into a production coater, providing an exhaust path.  FIG. 1  shows an example of such a known exhaust plenum. Known exhaust plenums are also described in the production coater described U.S. patent application Ser. No. 14/198,703 and the production coater with exchangeable drums described in U.S. patent application Ser. No. 12/493,710. U.S. patent application Ser. Nos. 14/198,703 and 12/493,710 are hereby incorporated by reference in their entirety. These known exhaust plenums generally require a large number of parts, can be difficult to service, maintain and clean. As such, there is a need for an exhaust plenum with: fewer parts; simple servicing, maintenance and cleaning; and does not require an operator to lift heavy parts. 
       SUMMARY OF THE INVENTION 
       [0006]    A production coater of this invention is a machine for coating a material with a solution or suspension. The production coater preferably includes a cabinet housing an internal coating drum that is rotated by a motor to coat cores or other materials with the solution or suspension, for example, but not limited to, coating pills or tablets. The production coater of this invention preferably includes an integrated exhaust plenum formed by a plurality of plenum walls and a surface of the cabinet housing. The plenum walls and the cabinet housing provide an exhaust path from the drum to an outlet of the cabinet housing. This integrated design of exhaust plenum reduces the number of parts, simplifies service and maintenance, does not require the lifting of heavy parts, and is easily cleanable when compared to known production coaters. 
         [0007]    In an embodiment of this invention, the production coater includes the cabinet forming an outer housing for the production coater. The cabinet encloses the coating drum positioned within the cabinet. The drum is preferably releaseably connectable to a motor that rotates the drum. The coating drum also preferably includes a baffle and/or a divider in an interior of the coating drum to improve the design of the drum to agitate cores, solutions and/or suspensions within the drum to ensure adequate coverage of the cores. 
         [0008]    In a preferred embodiment of this invention, the production coater includes an exhaust plenum with a plurality of walls. The exhaust plenum is integrally formed with an interior surface of the cabinet to form an enclosed pathway with an inlet and an outlet. The inlet opening of the exhaust plenum is in air-flow communication with an opening in the coating drum. The enclosed pathway allows air and exhaust to be vented from an interior of the drum and exhausted from the production coater through the outlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the following generalized and simplified drawings, wherein: 
           [0010]      FIG. 1  is a perspective view of a prior art exhaust plenum assembly for use with a separate coater cabinet. 
           [0011]      FIG. 2  shows a production coater according to an embodiment of this invention. 
           [0012]      FIG. 3  show the production coater of  FIG. 2  with an access door open to show an interior of the production coater. 
           [0013]      FIG. 4  is a cross-sectional view of the production coater of  FIG. 2  showing an air-flow path through the production coater. 
           [0014]      FIG. 5  is a perspective view of the production coater of  FIG. 2  with a cabinet housing removed to show an exhaust plenum and a drum of an embodiment of this invention. 
           [0015]      FIG. 6  is a pair of assembly drawings of a rear plate installation for the exhaust plenum shown in  FIG. 5 . 
           [0016]      FIG. 7  is a pair of assembly drawings of a front plate installation for the exhaust plenum shown in  FIG. 5 . 
           [0017]      FIG. 8  is a set of drawings showing rotation of a lower flap of the exhaust plenum shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]      FIGS. 2-8  show a production coater  10  with an integrated exhaust plenum according to one embodiment of this invention. The production coater  10  is a machine for coating pharmaceutical tablets and similar applications, preferably with a solution or a suspension. The production coater  10  is preferably a production scale coater capable of production in the range of approximately 30 liters to approximately 1,200 liters of material per batch. However, the production coater  10  of this invention should not be limited to this range and may be designed to handle any volume. 
         [0019]    The production coater  10  of this invention preferably includes a cabinet  12  housing a drum  14  and a motor, not shown, capable of rotating the drum  14 . The drum  14  is preferably a production sized coating drum, creating a generally cylindrical or frusto-conical coating vessel. The drum  14  is preferably rotated by the motor to create an internal mixing chamber within the drum  14 . 
         [0020]    The cabinet  12  provides a sealed, sanitary enclosure for the mixing and coating operation. The production coater  10  of this invention is preferably constructed of stainless steel, such as HASTELLOY™, or another suitable material compatible with compounds and/or coating solutions used in coating operations. 
         [0021]    According to a preferred embodiment of this invention, the production coater  10  may include access to an interior of the cabinet  12  through access door  16  and/or process port  18  positioned within access door  16 . In such a manner, the front of coater  10  preferably opens to provide full access to the drum  14  for extraction, insertion, inspection, baffles access, cleaning, maintenance and cleaning validation. 
         [0022]      FIG. 4  shows the production coater  10  with the cabinet  12  removed to show the drum  12  and an exhaust plenum  20  of this invention. In this embodiment, the exhaust plenum  20  and cabinet  12  form an air flow path  22  from the drum  14  and out of the cabinet  12 . In this embodiment, the exhaust plenum  20  includes a pair of side walls  24 , a center wall  26 , and a top wall  30 . At least one of the side walls  24 , the center wall  26  and the top wall  30  connect to a portion of an interior surface of the cabinet  12  to form an enclosed air flow path  22  with an inlet and an outlet to allow air and exhaust to expelled from an interior of the drum  14  to outside of the production coater  10 . In a preferred embodiment, the interior surface of the cabinet  12  provides a rear wall and/or a bottom wall for the exhaust plenum  20 . In alternative embodiment, the exhaust plenum  20  may include additional walls, such as a wall at the bottom or rear of the exhaust plenum, to enclose the exhaust plenum and prevent air or exhaust from leaking into other internal part of the production coater  10 . 
         [0023]    In the embodiment of  FIG. 2 , the drum comprises a cylinder and frusto-conical shape. Each of the pair of side walls  24  of the exhaust plenum  20  are positioned in proximity to a transition in the drum  14  from the cylinder to the conical shape, extending at approximately at a right angle to the cylinder. The side walls  24  each further include a curved edge that corresponds to surface of the cylinder of the drum and minimize a gap between the curved edge and the drum  14 . The center wall  26  is shaped similar to the side walls  24  and positioned near the center of the cylinder. Each of the side walls  24  and the center wall  26  extend from the drum to an interior surface of the cabinet  12 , where the side walls  24 , center wall  26  and the interior surface of the cabinet  12  define at least a portion of the air flow path  22  and provide an enclosed exhaust path for the drum  14 . In this embodiment, the rear wall and bottom wall of the integral exhaust plenum  20  is preferably provided by the interior surface of the cabinet  12 . Alternatively, the rear wall or the bottom wall may comprise a separate wall to enclose the rear and the bottom of the integral exhaust plenum  20 . In the embodiment of  FIG. 5 , the exhaust plenum  20  also includes a top wall  30 ,  32  and a pair of exhaust stacks  34 ,  36  forming openings in the top wall  30 ,  32 . In the embodiment of  FIG. 5 , the top wall is angled however, the top wall  30 ,  32  may not be angled and may be flat or curved. In this embodiment, there are two exhaust stacks  34 ,  36  however it should be understood that alternative embodiments may include one or more than two exhaust stacks. 
         [0024]    As best shown in  FIGS. 5 and 6 , the pair of side walls  24 ,  26  may each further include a rib  38 ,  40  and a plate  42 ,  44  to at least partially seal and/or enclose an edge of an inlet to the exhaust plenum  20 , when the drum  14  is positioned next to the exhaust plenum  20 . In a preferred embodiment, the exhaust plenum  10  may further include one or more upper seals and lower seals  36  positioned between each the pair of side walls  24  and the center wall  26  to further enclose the inlet to the exhaust plenum between the exhaust plenum  20  and the drum  14 . In a preferred embodiment, one or more of the seals may be moveable to simplify cleaning, draining or other maintenance of the production coater. For example, as best shown in  FIG. 7 , the lower seal  36  is a rotating lower seal to ensure proper water drainage during a washing cycle. 
         [0025]    As best shown in  FIG. 4 , the production coater  10  of this invention includes an air flow path  22  that takes air into an interior of the drum  14  via an intake  54  and expels the air and other exhaust out of the drum  14 , through the integral exhaust plenum  20  and out of the production coater  10  via an outlet  56 . In a preferred embodiment, the drum  14  includes a vented or perforated surface and a plurality of baffles. The vented surface provides a path for air to enter the interior of the drum and path for exhaust to be expelled from the interior of the drum  14  to the exhaust plenum  12  without the cores being able to escape the drum. The baffles mix the cores to ensure proper coverage of the cores with the solution or suspension. The baffles are preferably removable and replaceable or adjustable depending on the desired configuration or application. The baffles assist in the coating process by evenly distributing the coating solution or suspension over the material to be coated. The drums of this invention may further include various levels of polishing, multiple perforation patterns, various perforation sizes and shapes and/or various types of mixing baffles and anti-slide bars. Such multiple configuration enable replaceable drums to match perforation size and shape to various substrates, processes and wash requirements; match perforation pattern to various structural requirements; and permit the processing of tablets, granules, beads, very small tablets and/or other objects. Drums may further include meshed perforations. 
         [0026]    As shown in  FIGS. 5, 6, and 8 , the exhaust plenum  20  includes a reduction baffle  48  to reduce the inlet to the exhaust plenum  20  to prevent air bypass leakage when smaller volumes of tablets (multiple sizes are provided to adjust for varying bed depths). The reduction baffle  48  is preferably operable to allow the drum  14  to be sealed during coating of the cores with solution or suspension and operable to open the air flow path  22  through the exhaust plenum  20  when evacuating the drum  14 . 
         [0027]    As best shown in  FIG. 2 , the production coater  10  of this invention preferably further includes an inspection door  50  in the cabinet  12  that allows for access to the interior of the exhaust plenum  20  to facilitate cleaning, either horizontally or vertically, and/or to facilitate inspection of the exhaust plenum  20  and cabinet assembly  12  and/or the drum  14 . 
         [0028]    The production coater  10  of this invention preferably further includes spray bar  52  extending into a mixing chamber of drum  14 . The spray bar  52  is preferably externally adjustable from outside cabinet  12 , such as through adjustment device. The spray bar  52  disperses a desired coating solution over the material to be coated and may be positioned in a desirable manner to facilitate a desired coating. 
         [0029]    The various components of the production coater  10  are preferably accessible and viewable from the access door  16  and/or the process port  18  positioned within access door  16 . The process port  18  is preferably connected within access door  16  and permits direct and/or indirect access to the mixing chamber of drum  14 . Each of access door  16  and process port  18  are preferably independently openable for access to a coating chamber within the coater  10 , the coating drum  14  and/or the batch of material within and/or other components within the coater  10 , such as the spray bar  52 . 
         [0030]    While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.