Abstract:
Improvements in a rotary screen printer that operates with a stepper motor for indexing the screen printer. The stepper motor provides a positive rotation and locating of the printing arms. The stepper motor can also have a controlled acceleration and deceleration speed while it indexes. The stepper motor further drives a spur gear to improve the drive ratio from the stepper motor to the indexing arms. The rotary screen printer uses pneumatic cylinders to operate the screening arms. Pneumatic cylinders are controllable for the downward force by adjusting pressure regulator(s) and the stroke by adjusting either limit switches or mechanical stops. Each station is interchangeable to accommodate the printing requirements of each job. Each station can be operated as a screen printing station, a drying station, a pad printer, and the number of stations can be changed by reprogramming the number of steps between each station stop.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of applicant&#39;s co-pending application Ser. No. 62/106,141 filed Jan. 21, 2015, and is a continuation-in-part of applicant&#39;s co-pending application Ser. No. 14/022,406 filed Sep. 10, 2013 the entire contents of which is hereby expressly incorporated by reference herein. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates to improvements in a rotary screen printer. More particularly, the rotary screen printer is a mechanized screen printing machine where an operator installs a product and the product is precisely rotated around to various printing stations for application of colors, textures, coatings or drying. 
         [0007]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
         [0008]    Over the years screen printing has evolved from an operator manually positioning a single such as a shirt on a platen, lowering a patterned silk screen and screening a single color or color blend. The applied color(s) then typically air dried and application of additional color(s) were applied in the same manner. This traditional silk screen printing of textiles and other supports has well-known limitations of resolution and rendering. One of the problems is with the use of a reasonable maximum number of silk-screen printing stencils needed for the sequential application of as many silk-screen printing inks or pastes, each application needing a drying step. 
         [0009]    With more modern printing methods need to be developed. Some solutions such as digital print by a common inkjet plotter color graphical compositions on dark or black supports. Another limitation of digital printing is the impossibility of forming features in relief or of introducing special effects such as for example: glitters, glues, expanded materials, in order to obtain peculiar esthetical effects in the drawing or graphical image to be reproduced on the printable support. 
         [0010]    Traditional silk-screen printing technique permits the use of special inks or pigmented pastes and therefore the printing may be done on any surface even black without any problem. Silk screen printing technique have trouble with the presence on the printing area of reliefs and/or depressions as may be produced by the presence of sewing lines, hems, pockets and the like in the printing area. With these challenges, registration of the textile is critical to ensure that each color is placed in the required location as the textile progresses through the printing process. 
         [0011]    A number of patents and or publications have been made to address these issues. Exemplary examples of patents and or publication that try to address this/these problem(s) are identified and discussed below. 
         [0012]    U.S. Pat. No. 3,427,964 that issued on Feb. 18, 1969 to M. Vasilantone discloses a stencil printing machine. This machine has a stretcher assembly which is pivotal vertically and a horizontally rotatable platen assembly having a plurality of baseboards where the stretcher assembly is indexed for multi-colored printing. This patent requires manual indexing of the stretcher assembly and either requires the operator to move between each of the colors or for four operators to print a single shirt. 
         [0013]    U.S. Pat. No. 7,231,873 that issued on Jun. 19, 2007 to Luigi Macchi discloses a print carousel for double technology silk-screen and digital color printing. This machine has a plurality of print stations that are rotary indexed with a pneumatic or similar indexing system and then the silk-screen in brought down and the ink applied. While this system uses a rotary indexing printer the drive mechanism is not a stepper motor that can both ramp to indexing rate and provide a positive position lock. 
         [0014]    U.S. Publication Number 2006/0249039 that issued on Nov. 9, 2006 to Alon Feldman et al., discloses a combined stencil and digital printing system. This system also uses a pneumatic actuator to index the table and a position lock to prevent undesirable movement of the table position while the object is being printed with either an ink jet or a silk screen printing stencil. While this publication discloses a rotary printing table, the table is indexed with a pneumatic actuator and requires a lock to hold the table in a ridged position. 
         [0015]    What is needed is a rotary screen printing machine where the indexing of the table is performed with a stepper motor drive to provide reliable acceleration and deceleration of the rotating platen(s) and further provides a ridged lock without the arms being compliant. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    It is an object of the rotary screen printer to operate with a stepper motor for indexing the screen printer. The use of a stepper motor provides a positive rotation and locating of the printing arms. The stepper motor can also have a controlled acceleration and deceleration speed while it indexes. The stepper motor further eliminates the need for a locating pin to stop the printer in an exact location and prevent compliance movement while the printing operation is in process. The stepper motor further drives a spur gear to improve the drive ratio from the stepper motor to the indexing arms. 
         [0017]    It is an object of the rotary screen printer to use pneumatic cylinders to operate the screening arms. The use of pneumatic cylinders provides a smooth stroke to the printing screens and squeegees that is comparable to the force and motion that would be applied by a person. The pneumatic cylinders are controllable for the downward force by adjusting pressure regulator(s) and the stroke by adjusting either limit switches or mechanical stops. 
         [0018]    It is an object of the rotary screen printer for the printer to be self-contained and free standing to allow multiple rotary screen printers to be placed or re-positioned within a facility. This allows greater flexibility for a printing operation as the company expands. 
         [0019]    It is another object rotary screen printer for each of the stations to be interchangeable to accommodate the printing requirements of each job. Each station can be operated as a screen printing station, a drying station, a pad printer. The use of a stepper motor to index the printer further allows for changes to the number of printing stations by simply reprogramming the number of steps between each station stop. 
         [0020]    It is another object of the rotary screen printer to utilize curing stations at some stations. The curing stations can be thermal air or UV light to set the ink, dies or other media that is being applied. Because the stations can be quickly interchanged, multiple curing stations can also be plated between printing stations to ensure a more complete curing before another color is applied. 
         [0021]    It is another object of the rotary screen printer to print drink koozie on one or multiple sides. When printing is required on multiple sides the platen is automatically flipped to print on the opposing sides. The flipping operation is performed with a pneumatic piston that turns the platen over. Locking arms at each station keep the platen from rotating when the koozie is being printed. 
         [0022]    It is another object of the rotary screen printer to print on the surface of baseball type caps. The printing platen has alignment arms that position and retain the baseball cap in proper orientation to ensure that multiple passes on the cap are properly registered. The locating arms move with the printing platen as the printing platens index between printing and drying positions. 
         [0023]    Various objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0024]      FIG. 1  shows a perspective view of the rotary screen printer. 
           [0025]      FIG. 2  shows a top perspective view of the switch stop mechanism. 
           [0026]      FIG. 3  shows a top perspective view of the index and drive mechanism. 
           [0027]      FIG. 4  shows a top perspective view of the base unit. 
           [0028]      FIG. 5  shows perspective detail views of the dryer units. 
           [0029]      FIG. 6  shows the indexing hub with an arm removed. 
           [0030]      FIG. 7  shows a front perspective view of the printing units. 
           [0031]      FIG. 8  shows a top perspective view of a koozie rotary printer. 
           [0032]      FIG. 9  shows a top perspective view of the rotary table with the koozie platens. 
           [0033]      FIG. 10  shows a perspective view of a koozie platen being rotated. 
           [0034]      FIG. 11  shows a perspective view of the koozie platen with the holding plate. 
           [0035]      FIG. 12  shows a perspective view of a cap pallet for printing baseball caps. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]      FIG. 1  shows a perspective view of the rotary screen printer  10 . The rotary screen printer  10  is constructed in and upright orientation with a base  24  configured with a plurality of support feet  21 . The feet  21  are adjustable to accommodate uneven flooring. An upright frame support  20 . An air pressure regulator  22  is shown mounted near the base  24  of the rotary screen printer  10 . The air pressure regulator controls the incoming air pressure to the unit. The regulator may also include a water trap and an air oiling mechanism. The regulator  22  is connected within the support frame to a variety of control units (not shown) to control movement of pneumatic devices such as the pneumatic piston cylinder and rod  80 . A raised frame area  23  covers the pneumatic control switches that can be accessed by a cover plate. 
         [0037]    The top portion of the rotary screen printer  10  shows a plurality of stations. In this preferred embodiment six stations are shown. Because the rotary screen printer  10  utilizes a stepper motor drive to rotate and lock the printing arms in position the printer can be configured with a variety of print stations. The preferred embodiment of six arms allows for four colors of printing with one loading and one unloading station. It is also contemplated that a drying or flash cure unit is installed at the last station or between stations to dry the ink or die prior to removal of the item being printed or to dry one material or color before applying another. 
         [0038]    At the top of the rotary screen printer a control box  19  with a stop or step button  25  is located. The control box is located upon a raised track  70  where a printing squeegee  27  is located that is moved with the pneumatic cylinder  80 . The Printing squeegee  27  is raised and lowered onto the print surface to apply ink or die. A frame  71  bridges over the top of the printing station  63 . The top of the frame  71  has locking and or adjustment handles to position the location of the printing/screening area. 
         [0039]    In this embodiment two drying stations  60  and  61  are shown. The drying station can be from heat, or in this preferred embodiment from UV light. The drying stations are shown and described in more detail in  FIG. 5 . A back plate  69  along with the side plates reduces exposure of the UV light. 
         [0040]      FIG. 2  shows a top perspective view of the switch stop mechanism,  FIG. 3  shows a top perspective view of the index and drive mechanism. From  FIG. 3  the stepper motor  47  is shown below the motor mount plate  44 . A spur gear  41  is connected to the stepper motor  47  and drives gear  42  that is connected to the arms or platens. A frame  43  surrounds the gear drive mechanism for protection of the drive from contamination and from harm to operators. The use of a stepper motor is superior to other motors that are used to turn objects. Other rotary printers use pneumatic cylinders that require a locking mechanism to hold the rotary table in a fixed location. Servo motors require encoders and are fairly compliant thereby allowing movement of the position. 
         [0041]    The stepper motor  47  uses magnetic forces to rigidly hold the rotary table is the exact location without the need to use locking mechanisms. The use of a stepper motor  47  also allows for adjustment in the acceleration and deceleration of movement of the rotary table. The number of steps between stations can also be reprogrammed to increase or decrease the number of stations. In this preferred embodiment the spur gear  41  with the larger driven gear  42  increases the driving and holding force from the stepper motor  47 . 
         [0042]    The drive system is supported by a top plate on the upright frame  20 . On the side of the upright frame the switch stop mechanism is located. The switch stop mechanism is one or more an optical, mechanical  53  or inductive sensor  55  mounted on adjustable hardware  50  and  51  that allows for position adjustment. The mechanical switch sensor  53  has an armed switch with a roller  54  that is tripped as the platen(s) index. 
         [0043]    The central post  40  can be fixed to gear  42  or can be held in a fixed position as shown here thereby allowing the arms or platen(s)  30 - 35  as shown in  FIG. 4  to move under any printing or curing mechanism. 
         [0044]      FIG. 4  shows a top perspective view of the base unit with six arms of platens extending from a support plate  52  that is mounted to the drive gear  42  from  FIGS. 2 and 3 . The six platen arms  30 - 35  are drive around the upright frame  20  by the previously described stepper motor drive system where they are individually indexed into position for loading, printing, drying and unloading. 
         [0045]      FIG. 5  shows perspective detail views of the dryer units. From  FIG. 1 , the dryer units are located with the covers  60  and  61 . The back cover  69  from the unit covered by item  61  is shown in both  FIGS. 1 and 5  to provide and orientation reference. The dryers include UV or similar light or heating tubes or elements  64  and  65 . In the left sub assembly the elements  64  and  65  are visible, while in the right sub assembly the elements are covered with a reflecting shroud  62  that is secured with hardware  67  to support arm  66 . While two elements are shown, more or less quantity of elements is contemplated as few as one to more than two can be utilized. Insulating conductors  68  both suspend the UV elements and provide electrical connection to the UV elements  64  and  65 . The dryers are supported on arm(s)  66  that are directly or indirectly secured to the central post as shown in  FIG. 6 . 
         [0046]      FIG. 6  shows the indexing hub with an arm removed and  FIG. 7  shows a front perspective view of the printing units. From both of these views the arms or platens  30 - 32  etc. . . . are shown extending around on the support plate  52  and above the upright frame based  20 .  FIG. 6  shows support arm  66  connecting with hardware  67  to UV cover  61 . Below the platens the stop switch mechanism along with the mounting hardware  50 ,  51  is shown.  FIG. 7  shows a profile view of a printing station where the control box  19  is mounted on top of the central post  40  with stop/start/step button  25 . Portions of the UV arm covers  60  and  61  can be seen in  FIG. 7 . The track or guide  70  connects the center post  40  to the screen printing mechanism or station  63  where a frame bridge  71  connects to a frame  72  that supports the screening pieces and the squeegee  27 . Movement of the squeegee is from pneumatic cylinder/piston  80 . 
         [0047]      FIG. 8  shows a top perspective view of a koozie rotary printer. This rotary screen printer  110  is constructed in and upright orientation with a base configured with a plurality of support feet  21 . The feet  21  are adjustable to accommodate uneven flooring. An upright frame support  120 . An air pressure regulator  122  is shown mounted on the control head  119 . The air pressure regulator  122  controls the incoming air pressure to the unit. The regulator may also include a water trap and an air oiling mechanism. The regulator  122  is connected to a variety of control units (not shown) to control movement of pneumatic devices such as the pneumatic piston cylinders and rods. 
         [0048]    The top portion of the rotary screen koozie printer  110  shows a plurality of stations. In this preferred embodiment eight stations are shown. Because the rotary screen printer  110  utilizes a stepper motor drive to rotate and lock the printing arms in position the printer can be configured with a variety of print stations. The preferred embodiment of eight arms or platens  130  allow for printing on each side of a koozie, with a loading station, a flipping station, printing and drying stations  160 . It is also contemplated that a drying or flash cure unit  160  is installed at the last station or between stations to dry the ink or die prior to removal of the item being printed or to dry one material or color before applying another. 
         [0049]    At the top of the rotary screen printer a control box  119  with a stop or step button  25  is located. The control box  119  is located upon a raised track  170  where a printing squeegee is located that is moved with the pneumatic cylinder. The Printing squeegee is raised and lowered onto the print surface to apply ink or die. A frame bridges over the top of the printing station. The top of the frame has locking and or adjustment handles to position the location of the printing/screening area. To show the operation of the koozie flipping platens, the printing, the drying and the control is shown removed in later figures in this disclosure. 
         [0050]      FIG. 9  shows a top perspective view of the rotary table with the koozie platens  130 - 137 . All eight platens  130 - 137  are shown in this figure. Platent  133  is shown in the process of being flipped. The platens are at least partially supported on ring segment(s)  152 . 
         [0051]      FIG. 10  shows a perspective view of a koozie platen  134  being rotated. In this figure, the platen  134  is shown pivotably connected through pivot rod  144  through supporting brace  145  that allows the koozie platen  134  to flip 180 degrees. While only one platen  134  is shown in this figure, it should be understood that each platen will rotate (or flip) when the piston or actuator  160  pushes piston rod  161  up. The support ring  152  has corner stops  171  that maintain the edges  170  of the platens in a horizontal orientation. It is further contemplated that the platen can have detents or over-center devices that essentially hold the platen in one of two 180 degree opposed orientations. While two 180 degree opposed orientations are shown and described, the orientations can be 120 degree, 90 degree or other orientations. The platens are rotated with a mechanical piston, actuator or pneumatic cylinders. A koozie  112  is shown over the platen  134 . The platen only needs to make a single 180 degree rotation for each full rotation around the printing table. 
         [0052]      FIG. 11  shows a perspective view of the koozie platen with the holding plate  120 . The holding plate  120  maintains the platen  131  in a flat orientation and further provides support under the platen to counteract downward printing forces. The sides of the holding plate  120  has side positioning tabs  121  and  122  that maintain the rotational position of the platen  131  in the printer. A koozie  112  is shown with a logo  114  imprinted on one side of the koozie  112 . The platen  131  is further supported through rotating rod  141  that is supported by supporting brace  145 . The support ring  152  supports the bottom of the platens as they rotate between stations and at each printing station. 
         [0053]      FIG. 12  shows a perspective view of a cap pallet  210  for printing baseball caps. The cap pallet  210  secures with a pallet attachment arm  219  with a plurality of holes  218  for securing the arm to a printing machine or screen. The pallet attachment arm  219  connects to U-brackets  240  and  245  and also to stretcher brackets  250  and  255 . The U-brackets  240  and  245  are connected to separate dash keepers  230  and  235  that are brought over the bill  211  of the cap to maintain the position of the cap when printing the cap  211 . The U-brackets  240  and  245  connect to a cap pallet or platen  220  where the printing in placed onto the front of the cap  211 . When the cap  211  is installed onto the cap pallet  210  the back portion of the cap is secured under a stretcher bar  260  to keep the cap  211  under tension. A spring  261  pulls down on the stretcher  260  to prevent movement of the cap  211  while the cap moves between printing and or drying stations. 
         [0054]    Thus, specific embodiments of a rotary screen printer have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.