Abstract:
The present disclosure sets forth an automated apparatus and method for applying gas plasma coatings to aircraft engine parts. The process and apparatus employ a plurality of sensors which continually monitor various process parameters associated with the coating process. If any of the measured parameters fall out of tolerance, the coating process is interrupted to allow a user to fix the source of the problem, where upon the process is reengaged. Moreover, the process and apparatus employ a pause resume circuit which uses predetermined durations for pausing and resuming the coating process.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The present disclosure generally relates to aircraft engine parts, and more particularly relates to plasma coating of aircraft engine parts. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    In the manufacture of various aircraft engine parts, very complex plasma coating and heat treatment processes must be performed on the parts. For example, in the manufacture of turbines, airfoils, and other components of an aircraft, plasma coating must be performed to exacting standards. In so doing, multiple coating parameters, sometimes in excess of ten or more parameters, must be constantly monitored to ensure that the coating process is being performed within tolerance of the specific recipe required for the application. Any deviation from those tolerances will result in a part which does not meet specification and either must be scrapped or reworked. 
         [0003]    Currently, such monitoring of the various process parameters is performed manually. Sensors may be provided to measure the various coating parameters, but a human operator must continually monitor the outputs of those sensors to ensure they are within tolerance. If a fault is detected, i.e. if one of the parameters falls out of tolerance, the human operator must manually stop production, determine the source of the fault, fix the fault, and restart the process. This is accordingly very time consuming and if done repetitively over time, can become tedious and thus lead to human error. Moreover, as the parameters must be monitored constantly, a single human operator can only be responsible for a single coating bay or booth, thus increasing labor requirements of the overall assembly process. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    In accordance with one aspect of the disclosure, an apparatus for plasma coating aircraft engine parts is therefore disclosed which may include a spray unit, a plurality of sensors and a controller. The plurality of sensors sense a plurality of process parameters associated with the coating, and the controller includes a pause/resume circuit that is communicatively coupled to the plurality of sensors. 
         [0005]    In accordance with another aspect of the disclosure, a method for plasma coating aircraft engine parts is disclosed which may include the steps of providing an apparatus having a spray unit, a plurality of sensors and a controller wherein the plurality of sensors sense a plurality of coating process parameters and the controller includes a pause/resume circuit that is communicatively coupled to the plurality of sensors, pausing the coating once one of the plurality of process parameters falls out of tolerance, and resuming the coating once the plurality of process parameters are back within tolerance. 
         [0006]    In accordance with another aspect of the disclosure, an apparatus for plasma coating aircraft engine parts is disclosed which may comprise a plurality of sensors sensing a plurality of coating process parameters selected from that group consisting of current, voltage, power, process gas pressure, carrier gas pressure, part feed rate, air flow, vibration level, water temperature, and water conductivity; a robotic spray unit; and a controller including a pause/resume circuit that is communicatively coupled to the plurality of sensors and the robotic spray unit. The pause/resume circuit automatically pauses operation of the robotic spray unit when one of the coating process parameters is out of tolerance, and automatically resumes operation of the robotic spray unit when the coating process parameters are within tolerance. 
         [0007]    These and other aspects and features of the disclosure will become more apparent upon reading the following detailed description when taken in conjunction of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a block diagram of an apparatus for plasma coating aircraft engine parts constructed in accordance with the teachings of the disclosure; 
           [0009]      FIG. 2  is a perspective view of the exemplary embodiment of an apparatus for a plasma coating aircraft engine parts constructed in accordance with the teachings of the disclosure; and 
           [0010]      FIG. 3  is a flow chart depicting a sample sequence of steps which may be practiced in accordance with the teachings of the disclosure. 
       
    
    
       [0011]    While the following detailed description will be made with reference to certain exemplary embodiments, it is to be understood that the scope of the disclosure is not to be so limited. Rather, the scope of the disclosure is intended to include not only that specifically set forth in the following detailed description, but that which is fairly encompassed by equivalents thereof, and captured by the appended claims. 
       DETAILED DESCRIPTION 
       [0012]    Referring now to the drawings, with specific reference to  FIG. 1 , an apparatus  20  for plasma coating aircraft engine parts  22  is shown in schematic fashion. The part  22  can be any number in different components used on an aircraft such as, but not limited to, turbines, airfoils, fuselages and the like. In addition, while the following detailed description will be made with reference to gas plasma coating of such parts  22 , it should be understood that the teachings of the present disclosure, specifically that with respect to the pause/resume circuit, can be similarly employed with respect to various other coatings, heat treatments, or other processes applied to the parts  22 . 
         [0013]    Referring again to  FIG. 1 , the apparatus  20  is shown to include a robotic or otherwise automated spray unit  24  having a gun  26  adapted to apply a gas plasma treatment or other process on the part  22 . The robotic spray unit  24  is in fluid communication with various gases to effect the gas plasma coating including process gases  28  and carrier gases  30 . While the process gases  28  and carrier gases  30  are shown in a singular fashion in  FIG. 1 , it is to be understood that in actual practice, multiple types of process and carrier gases can be, and are likely, employed. For example, four different process gases and four different carrier gases may be used to create the specific recipe applied by the robotic spray unit  24 . Those gases may include, but not be limited to, argon, nitrogen and hydrogen. 
         [0014]    It order to ensure that the gas plasma or the other coating applied to the part  22  is applied correctly, the apparatus  20  may also include a plurality of sensors  32  adapted to sense various process parameters associated with the application of the coating  34  to the part  22 . Those sensors  32  can include, but are not limited to, current sensors  36 , vibration sensors  38 , voltage sensors  40 , power sensors  42 , process gas pressure sensors  44 , carrier gas pressure sensors  46 , part feed rate sensors  48 , air flow sensors  50 , water temperature sensors  52 , water conductivity sensors  54 , barometric pressure sensors  56  and pressure differential sensors  58 . Each of these sensors  32  continually monitors the various parameters associated therewith, and generates a signal  60  indicative of the measured parameter to a controller  62 . 
         [0015]    The controller  62  then compares the measured signal  60  to an acceptable tolerance range. “Acceptable tolerance range”, “within tolerance”, and “out of tolerance” are defined herein as predetermined values or ranges for the various sensed parameters suitable to result in the proper application of the coating. If the measured signal  60  is within the tolerance range, the controller  62  continues to enable the robotic spray unit  24  to apply the coating  34  to the part  22 . However, it is to be understood that this is a continual comparison of not just one signal, but each of the signals received from the various sensors  32  to each of the tolerance ranges associated with each parameter. Concurrent with allowing the robotic spray unit  24  to continue application of the coating  34 , output signals  66  are sent by the controller  62  to an operator interface panel  68  to allow for a user  70  to monitor the various sensed parameters as well. 
         [0016]    As will be described in further detail with respect to  FIG. 3 , if one of the sensed parameters as indicated by signal  60  is out of tolerance, the controller  62  engages a pause/resume circuit  72  to disengage the robotic spray unit  24  until the sensed parameter is back within tolerance range. More specifically, the pause/resume circuit  72  disengages operation of the robotic spray unit  24  for a predetermined duration as measured by an off-timer  76 . After completion of the predetermined range  74 , the controller  62  then again compares the measured parameter to the tolerance range. If the measured parameter is within tolerance, the controller  62  reengages the robotic spray unit  24  to allow the coating  34  to again be applied to the part  22 . In order to do so, the resume circuit  72  employs an on-timer  78 , which lasts for predetermined duration. After completion of the predetermined duration, the robotic spray unit  24  reengages. Again, this process is continual in that every time a sensed parameter is out of tolerance, the pause/resume circuit comes into play. 
         [0017]    As will be noted above, the apparatus  20  fully automates the process of applying gas plasma coatings to an aircraft engine part  22  by measuring various process parameters associated with the coating process, and if any are out of tolerance, disengaging the gas plasma spray unit. This is a significant departure compared to the prior art which requires a single user to manually monitor the sensed parameters, and if any are out of tolerance, to immediately and manually cause the coating process to discontinue. The user then has to fix whatever problem is causing the sensed parameter to be out of tolerance, and then measure the sensed parameter again. Assuming it is back within tolerance, the user then has to manually restart the coating application process. Given the number of sensors and process parameters associated with the gas plasma coating process, such a prior art monitoring system largely occupies the time of a user, thus resulting in significant labor costs and decreased production. Moreover, given the manual component of the monitoring process, the process might become tedious and thus cause human error. 
         [0018]    However,  FIG. 2  depicts one of the significant improvements afforded by the teachings of the present disclosure. As shown herein, a single user  70  can simultaneously monitor multiple spray booths  82 , each of which are continually applying gas plasma coatings  34  to parts  22 . The overall process is therefore greatly improved in terms of productivity, but also in terms of quality in that human error does not play nearly as significant a role in the coating process since much of the coating process is automated. Rather, a single user can simply and periodically monitor the operator panel  68  to ensure the process is being conducted as appropriate. Moreover, while four gas plasma spray booths  82  are depicted in  FIG. 2 , it is to be understood that given the teachings of the present disclosure, a greater or lesser number of the spray booths can of course be monitored by a single user  70 . 
         [0019]    Referring now to  FIG. 3 , sample sequence of steps which can be conducted in accordance with the teachings of the present disclosure are depicted. Starting with step  84 , the process begins by commencing application of the gas plasma coating  34  to the part  22 . Immediately the various process parameters associated with the process are monitored by the various sensors  32  as depicted in step  86 . If the process parameters as sensed are within tolerance as indicated by step  88 , the gas plasma coating process is continued as indicated by step  90 . 
         [0020]    However, if the process parameters are out of tolerance as indicated by step  92 , the pause/resume circuit  72  is initiated as indicated by step  94 . This involves the deactivation of the robotic spray unit  24  as indicated by step  96 . The predetermined duration of the pause cycle is then measured after which the controller  62  again compares the measured process parameters to the acceptable tolerance range as indicated by step  100 . 
         [0021]    If the measured processed parameters are then determined to be within tolerance as indicated by step  102 , the resume circuit  72  is initiated as indicated by step  104 . This entails measuring the predetermined duration of the resume circuit  72  after which the robotic spray unit  24  is reactivated as indicated by step  106 . After reactivation, the process restarts in that the various process parameters are continually measured to determine if they are continuing to stay within tolerance. 
         [0022]    However, if at any time the processed parameters are determined to be out of tolerance  100  as measured by step  108 , output signal  66  is sent to operator interface panel  68  as indicated by step  110 . This alerts the user  70  to fix or alleviate whatever problem is causing the process parameter to be out of tolerance as indicated by step  112 . After the problem is fixed, the process reverts back to the process of comparing the measured process parameters to determine if they were within the tolerance range associated with that parameter. 
         [0023]    While the predetermined durations for the pause circuit and resume circuit  72  will be variable and dependent upon the actual process or coating process being applied to a given part, in one particular embodiment, the predetermined duration of the pause circuit may be about 10 seconds and the predetermined duration of the resume circuit may be about 4 seconds. Of course, as indicated above, other times are certainly possible. 
       INDUSTRIAL APPLICABILITY 
       [0024]    In light of the foregoing, it can be seen that the teachings of the present disclosure can find industrial applicability in the application of various coatings to aircraft engine parts. Such parts can include but not be limited to turbine blades, airfoils, fuselages and the like. Such processes can be, but are not limited to, gas plasma coating and heat treatments. The apparatus and process provide a mechanism by which multiple process parameters associated with the coating process are continually and automatically measured and compared to predetermined tolerance ranges, and only if they are continually within those tolerance ranges, will the coating process continue. If at any time the measured process parameters fall out of tolerance, the coating process is interrupted until the process parameters are fixed and back within range. By automating the process, the time of the user is greatly alleviated and a single user can monitor multiple coating or spray booths as compared to the prior art which requires a single user to constantly monitor a single spray booth. The present disclosure not only improves productivity, but quality as well in that human error has historically played a part in malformed parts, which either cause rework or scrapping of parts or poor performances with respect to the resulting aircraft.