Abstract:
A charge ring and fluid restriction arrangement for a paint spray tool. The paint spray tool has a charge ring that is moveable along the axis of the tool body. The paint spray tool also has interchangeable pre-orifices within the tool body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/666,241, filed Jun. 29, 2012. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a charge ring and a fluid restriction purge arrangement for a paint spray tool. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the field of painted automotive components, robotic arms having paint spray tools are used for applying paint to a part. At the end of a robotic arm a paint spray tool is mounted. Several designs of paint spray tools incorporate the use of a charge ring, near the spray outlet of the paint tool for applying an electrical charge to the paint particles in midair as the paint leaves the spray outlet, and is blown toward the surface of the part. The system uses electrostatic attraction to charge the paint spray particles and cause them to be attracted to the part in order to prevent the particles from becoming airborne, over spraying or reflecting off of the surface of the part. 
         [0004]    One particular problem with the use of a charge ring is that during a paint spraying operation, the probes of the charge ring can accidentally become covered with paint due to the close proximity of the paint spray tool and the part. When the probes of the charge ring become covered in paint, they lose their effectiveness to charge the paint particles coming off of the paint spray tool. It is therefore desirable to provide a paint spray tool arrangement that allows for adjustment of the charge ring for specific types of applications. 
         [0005]    Another aspect of paint spray tools is that they have paint supply inlets where pressurized paint is connected to the paint spray tool and flows through conduits in the paint spray tool to a spray outlet. Different types of paints having different types of viscosities are used sometimes alone or simultaneously with paint having a different type of viscosity or consistency in order to achieve a desired finish. During operation of the paint spray tool, it is desirable to purge the main paint supply conduits of any paint within the tool body. In order to effectively purge the paint, it is desirable to have a proper orifice size in the purge conduit that is suitable for the viscosity of the paint that is being purged. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a charge ring and fluid restriction arrangement for a paint spray tool. The paint spray tool has a mounting bracket for connection to a mechanical arm and a tool connected to the mounting bracket having two or more paint supply inlets and one or more conduits extending through the body which lead to one or more spray outlets. A bell cup is connected to the body and circumscribes the spray outlets. The bell cup directs the spray coming off of the spray outlets in a specific direction. 
         [0007]    In one embodiment of the present invention, a charge ring is slidably connected to and moveable along the longitudinal surface of the body. The charge ring has a lockable collar with one or more probes extending from the collar. The charge ring can move between a standard position and at least one secondary position. 
         [0008]    In another aspect of the invention, at least one purge supply line is connected to the one or more conduits of the body between the two or more paint supply inlets and the one or more spray outlets. At least one interchangeable pre-orifice is positioned in the at least one purge supply line and the pre-orifice is interchangeable with other pre-orifices having different orifice diameters. A valve and main orifice is positionable in the at least one purge supply line upstream of the at least one interchangeable pre-orifice. During a paint purging operation, paint is purged from the conduit of the tool part of the body, through the pre-orifice and past the main orifice and valve. The use of the pre-orifice allows for effective purging of the paint from the conduit since the pre-orifice has an orifice diameter that is ideal for the viscosity of paint being purged from the conduit. 
         [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a perspective side view of a paint spray tool in accordance with the present invention; 
           [0012]      FIG. 2A  is a perspective side view of a paint spray tool with the charge ring in a standard position; 
           [0013]      FIG. 2B  is a perspective side view of a paint spray tool with the charge ring in a secondary position and having a mounting bracket cover removed; 
           [0014]      FIG. 3  is an enlarged rear perspective view of the charge ring with the tool body removed showing a groove on the inside sliding diameter of the charge ring; 
           [0015]      FIG. 4  is a cross-sectional enlarged perspective end view of the charge ring showing the groove on the surface of the charge ring and a tab on the tool body shown in phantom inside of the groove with the external charge ring in the locked position; 
           [0016]      FIG. 5  is a cross-sectional plan side view of the charge ring and fluid restriction arrangement of the present invention; and 
           [0017]      FIG. 6  is a second cross-sectional side view of the charge ring and fluid restriction arrangement for a paint spray tool in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0019]    Referring now to all the  FIGS. 1-6  various views of a paint spray tool  10  are shown. The paint spray tool  10  has a mounting bracket  12  for connecting to a robotic arm  11 .  FIGS. 1 and 2A  show a cover  13  on the mounting bracket  12 , while  FIG. 2B  shows the cover  13  removed. A body  14  of the paint spray tool  10  is connected to the mounting bracket  12 . The body  14  has two paint supply inlets  16 ,  16 ′ (shown in  FIG. 2B ) and two conduits  18 ,  18 ′ (shown in  FIGS. 5 and 6 ). The conduits extend through the body  14  between the paint supply inlet  16 ,  16 ′ and spray outlets  20 ,  20 ′. The paint spray tool  10  has two paint supply inlets  16 ,  16 ′, conduits  18 ,  18 ′, and spray outlets  20 ,  20 ′, in order to accommodate two different types of paints or paint materials having different types of viscosity. For example, certain paint mixtures are aqueous or water based and therefore has a higher viscosity, while other solvent or organic based paint materials have a lower viscosity. Each type of paint material will travel separately through the paint spray tool  10  through independent paint supply inlets  16 ,  16 ′ and spray outlets  20 ,  20 ′. 
         [0020]    Connected to the conduits  18 ,  18 ′ are two purge lines  22 ,  22 ′, with one purge line connected to a respective conduit  18 ,  18 ′. The purge lines  22 ,  22 ′ each have an interchangeable pre-orifice  24 ,  24 ′ that is a cylindrical insert placed within the purge line  22 ,  22 ′, the insert has an orifice diameter for allowing the flow of paint from the conduits  18 ,  18 ′ through the purge line  22 ,  22 ′. The interchangeable pre-orifice  24 ,  24 ′ can be interchanged with other interchangeable pre-orifices that have different orifice diameters. The use of the interchangeable pre-orifice  24 ,  24 ′ in each purge line  22 ,  22 ′ allows the purge line to be calibrated in order to effectively purge the conduits  18 ,  18 ′ based on the type of paint or viscosity of the paint being used by the paint spray tool  10 . Upstream of each interchangeable pre-orifice  24 ,  24 ′ is a main orifice  26 ,  26 ′ which has a valve  28 ,  28 ′ that functions to open and close the main orifice  26 ,  26 ′ in order to control the purging of paint from the conduits  18 ,  18 ′, through the purge lines  22 ,  22 ′. Having an interchangeable pre-orifice  24 ,  24 ′ allows you to control the flow of paint through the purge lines  22 ,  22 ′ without having to completely remove and have multiple main orifices  26 ,  26 ′ and valves  28 ,  28 ′ in order to accommodate paints having various viscosities. The interchangeable pre-orifice  24 ,  24 ′ can be interchanged with an alternate orifice  25 ,  25 ′ having different dimensions and orifice diameters compared to interchangeable pre-orifice  24 ,  24 ′. 
         [0021]    The paint spray tool  10  also has a bell cup  30  connected to the body  14  and circumscribing the spray outlets  20 ,  20 ′. The bell cup  30  helps to prevent back spray of paint and control the spray direction of the paint leaving the spray outlets  20 ,  20 ′. 
         [0022]    In another aspect of the invention, the body  14  has a longitudinal surface  32  where a charge ring  34  is connected. The use of a charge ring in paint spray tools serves the purpose of electro-statically charging the paint particles as they exit the outlet of the paint spray tool, so that the paint particles will be attracted to the part being sprayed. The practice of using a charge ring to charge the paint particles helps to eliminate overspray and improve the consistency and evenness of paint applied to the part. 
         [0023]    The charge ring  34  shown in accordance with the present invention has one or more probes  36  connected to a lockable collar  38 . The probes  36  emit the electric charge that is applied to the paint particles leaving the spray outlets  20 ,  20 ′. During a paint spray operation, the paint spray tool  10  can move to close to the part or encounter overspray of paint which adheres to the probes, which causes the probes to become less effective in charging the paint particles. 
         [0024]    The present invention provides the lockable collar  38  which allows the charge ring  34  to be moved between a standard position (shown in  FIG. 2A ) and at least one secondary position (shown in  FIG. 2B ). The lockable charge ring  38  moves between positions using a protrusion  40  extending from an outside surface of the body, which locks into a locking groove  44  formed on an inside surface  42  of the lockable collar  38  (see  FIG. 4 ). It is within the scope of this invention for the protrusion  40  and locking groove  44  to be placed on opposite surfaces. During movement of the charge ring  34  between the standard position and the secondary position, the lockable collar  38  is rotated in order to disengage the protrusion  40  from the locking groove and then allow the lockable collar  38  to slide along the longitudinal surface  32  of the body  14 . It is within the scope of this invention for there to be several different secondary positions for the charge ring  34  depending upon the particular application. The use of the charge ring  34  in the present invention allows for the manual adjustment of the charge ring  34  if overspray onto the probes  36  is noticed or in spraying operations where it is known that the paint spray tool  10  will have to be in close proximity to the part being painted. 
         [0025]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.