Abstract:
An apparatus for masking an article with masking material is disclosed. The apparatus generally includes a spray head connected to a primary channel which forms a passage for the masking material. This channel has two sections, the first of which terminates in a junction with the spray head and is angled from the second section. In addition, the apparatus has at least one secondary channel which forms an air passage and is attached to the primary angled channel

Description:
BACKGROUND 
       [0001]    This disclosure generally relates to an apparatus, a system, and a method for masking articles, and more particularly, to an apparatus, a system, and a method for masking articles of complex geometry not conducive to traditional spray masking. 
         [0002]    Generally, it is known to mask and coat articles in order to protect them from degradation and wear during operation. Existing apparatuses dedicated to this task are limited by the geometry of the parts which they attempt to mask, since they typically have a sprayer connected directly and immovably to a large, blunt spraying mechanism. For this reason, it is difficult to mask parts with complex geometries prior to the coating process. 
         [0003]    Specifically, high pressure compressor vanes are known to be exposed to extreme temperatures and pressures during the course of their operation. In order to reduce the amount of degradation and wear, the parts are typically coated with a protective material. The process of applying such a coating involves rapidly heating the material and accelerating the material at the part. This process can be damaging to the part and thus, masking with an ultraviolet (UV) curable material prior to coating is common practice. 
         [0004]    During the masking process, a masking material is sprayed out of a central channel and air is sprayed out of at least one secondary channel. Combining the jet of air with the jet of masking material causes the atomization of the masking material, which improves the adhesion of the masking material to the substrate. 
         [0005]    After the article has been masked, the coating material is heated and accelerated toward the partially-masked substrate. The masked surface is protected from the harsh effects of the coating process. 
       SUMMARY 
       [0006]    An apparatus for masking an article with masking material is disclosed. The apparatus generally includes a spray head connected to a primary channel which forms a passage for the masking material. This channel has two portions: a first portion terminates in a junction with the spray head, and a second portion other terminates with a rotatable connection to an existing spraying machine. The first portion is angled from the second portion. In addition, the apparatus has at least one secondary channel which forms an air passage. The air passage is attached to the primary angled channel and at least one point along the length of the primary angled channel. 
         [0007]    These and other features of the present disclosure can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a sectional view of an axial flow, turbo fan gas turbine engine. 
           [0009]      FIG. 2A  is a perspective view of the airfoils in application to the vanes of a gas turbine engine. 
           [0010]      FIG. 2B  is a perspective view of the interaction between a prior art sprayer and a traditional compressor vane assembly. 
           [0011]      FIG. 2C  is a side view of the interaction between an embodiment of the disclosure and a traditional compressor vane assembly. 
           [0012]      FIG. 2D  is a side view of the interaction between the embodiment in  FIG. 2C  and a traditional compressor vane assembly in an alternate position. 
           [0013]      FIG. 3A  is a side view of an embodiment of the apparatus. 
           [0014]      FIG. 3B  is a section view of the nozzle and air channels taken from section A. 
           [0015]      FIG. 4  is a pictorial illustration of the coating process following masking. 
           [0016]      FIG. 5  is a method chart outlining the masking and coating processes. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  illustrates a sectional view of an axial flow, turbo fan gas turbine engine  10  which comprises of a compressor section  14 , a combustion section  16 , a turbine section  18 , and a fan  30 . The turbine has rotating blades  22  which are fixed to rotors  28  which rotate about the centerline  12 . In addition the turbine  18  has vanes  20 , which remain fixed with respect to the blades  22 . Similarly, the compressor  14  has vanes  26 , and rotating blades  24  connected to a rotor  28  which rotates about the centerline  12 . 
         [0018]      FIG. 2A  shows a perspective view of vanes  26 . As shown, the vanes  26  are curved and nested within each other. Given such a closely-spaced orientation, it is difficult to apply a mask to the surfaces. 
         [0019]      FIG. 2B  shows the limitations of the prior art apparatus  32  for coating airfoils  62  such as the vanes  26  of a compressor  14 . The prior art apparatus  32  can only partially mask section  34  of two airfoils  62  of relatively complex geometry in series. The remainder of the airfoils  62  remain unmasked, as seen by sections  54  and  56 , since the prior art apparatus  32  cannot reach around the curved surfaces due to its existing geometry. 
         [0020]      FIG. 2C  shows the spray apparatus  36  of the disclosure which can fully mask  34  the complex geometry of the airfoils  62  in series. In contrast to  FIG. 2A , the entire surface of the airfoils  62  is masked due to the spray apparatus&#39;s ability to rotate and translate about the axis  64 . The spray apparatus may be configured to rotate and translate simultaneously, though the steps of rotating and translating the spray apparatus may be performed separately or in series. 
         [0021]      FIG. 2D  shows the spray apparatus  36  of the disclosure as in  FIG. 2C  in a secondary orientation. In this second orientation, the apparatus  36  has been rotated and translated about the vertical axis  64 . 
         [0022]      FIG. 3A  shows a side view of the spray apparatus  36  described in this disclosure. The apparatus  36  is rotatably attached to an existing spraying machine  70  and connected to the supply of masking material  72  and an air tank  74  by adapter  38 . The supply of masking material  72  and the air tank  74  may be associated with an actuator capable of propelling masking material  72  through the channel  40 , for example, while concurrently passing air through air channels  60 . Alternatively, the supply of masking material  72  and the air tank  74  may be provided with separate, individual actuators capable of such concurrent operation. 
         [0023]    The adapter  38  is connected to a longer second portion  42  of the apparatus, which is of length d 1 . The second portion  42  is connected to a first portion  44 , which is of length d 2 , and is at an angle  50  from the centerline of the apparatus  48 . In this embodiment, the angle  50  is approximately 45° and the ratio of d 1  to d 2  is substantially equal to 2:1. In other embodiments, the angle  50  can be between 35° and 145°, and the ratio of d 1  to d 2  can be approximately 2:1. The spray head  46  is secured to the termination of the first portion  44 . Additionally, the at least one channel  40  is secured and congruent to both the first portion  44  and second portion  42  of the apparatus  36 . 
         [0024]      FIG. 3B  shows a section view of the spray apparatus  36  taken from section A. The first portion  44  is surrounded by air channels  60 . In this example there are two air channels  60 , however in another embodiment there may be any number of air channels. 
         [0025]      FIG. 4  illustrates the coating process that follows the masking process. The airfoils  62  have been previously coated with the masking material  34  and is then sprayed with the coating material  76  which has been heated in a plasma flame and accelerated at the airfoils  62  at a high velocity. During this process, the masking material  34  protects the coating  78  from directly contacting the airfoils. 
         [0026]      FIG. 5  shows an outline of the process described in this application. First, the UV masking material is atomized at step  80 . Next, at step  82 , the atomized UV masking material is sprayed through the spray head, and then the airfoils (e.g., the articles or substrates) are covered with the atomized UV masking material at step  84 . At step  86  the coating material is heated in a plasma flame, and is subsequently accelerated onto, and deposited onto, the masked airfoils as represented at step  88 . Further, as represented at step  90 , the atomized UV masking material may be removed from the airfoils through a heat treating process without detrimental effect to the coating material deposited in step  88 . That is, the heat treating process removes the UV masking material without harming or removing the coating material. In one example, the temperatures associated with the heat treating process are no less than 600° F. 
         [0027]    Although an embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For this reason, the following claims should be studied to determine their true scope and content.