Abstract:
An apparatus and method to automate the process of measuring and verifying trace gas levels such as oxygen and dewpoint inside a retort used to coat or heat treat substrates are provided. The apparatus may include an integrated measuring system, and an operator interface. The method may include coupling the apparatus to the retort in which the substrate is coated or heat treated, activating the integrated measuring system to measure and verify atmospheric conditions within the retort, and providing operator access to process parameters and status through the operator interface. The measurement and verification system may be completely autonomous.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The present disclosure generally relates to systems and methods for coating or heat treating a substrate, and in particular to automated measurement and verification systems for assuring a retort used for such operations meets suitable dewpoint and oxygen levels prior to engaging in same. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    In manufacturing many industrial parts, coatings of a particular material to the parts need to be applied to exacting standards. In others, heat treatments of the parts has to be undertaken to precise standards as well. Any deviation away from those standards or thresholds can result in malfunctioning components. If those components are used, the overall machine in which they are employed may under-perform. Accordingly, they are often rigorously tested prior to installation. If they are not sufficient, the parts are either scrapped or remachined. Either way, the result is added cost and lessened efficiency. 
         [0003]    One example where this is currently problematic is in the manufacture of turbines and other components used in gas turbine engines and other aircraft components. With turbines, for example, aluminide or other coatings often need to be applied. Currently, prior to application of such coatings, the retort or chamber environment in which the component is coated needs to be purged with argon or another inert gas to establish proper coating conditions. An operator not only needs to manually do this, but then manually verify it with dewpoint and oxygen measurements. These measurements require the operators to manually connect a dewpoint and oxygen meter to the retort and follow a specific procedure to assure all process parameters are achieved before proceeding. If they are not adhered to, it may cause deficiencies in the processed parts as well as damage to the measuring equipment. 
         [0004]    Not only is this manual verification labor intensive, but prone to human error. For example, the repetition of the task throughout the day may lead to tedium and mistakes. Moreover, the manual purging and verification process occupies the operator, often precluding him or her from performing any other task, thus slowing production. Accordingly, it would be beneficial to have an automated measuring system to eliminate scrap/rework due to improper coating or heat treating environments, and to prolong the life of the process measuring equipment by avoiding human error in the manual operation. Moreover, it would be beneficial to allow for increased productivity and reduced costs by allowing the operator to monitor multiple stations and by minimizing human intervention in the manufacturing process. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    In accordance with one aspect of the disclosure, an apparatus for automating dewpoint and oxygen level verification within a retort for coating or heat treating substrates is disclosed, which may include an integrated measuring system being communicatively coupled to the retort and measuring dewpoint and oxygen conditions inside the retort, and an operator interface communicatively coupled to the integrated measuring system, the operator interface automatically communicating whether dewpoint and oxygen levels inside the retort are within an acceptable range. 
         [0006]    In accordance with another aspect of the disclosure, a method for automating dewpoint and oxygen level verification within a retort for coating or heat treating substrates is disclosed, which may include the steps of providing an integrated measuring system communicatively coupled to the retort and measuring dewpoint and oxygen conditions inside the retort, an operator interface communicatively coupled to the integrated measuring system for automatically communicating whether dewpoint and oxygen levels within the retort are within an acceptable range, purging the retort, activating the integrated measuring system, and verifying dewpoint and oxygen levels within the retort using the integrated measuring system. 
         [0007]    In accordance with yet another aspect of the disclosure, an apparatus for automating dewpoint and oxygen level verification within a retort for coating or heat treating substrates prior to coating is disclosed, which may include dewpoint and oxygen sensors, a processor receiving signals for the dewpoint and oxygen sensors indicative of dewpoint and oxygen levels, respectively, and an operator interface automatically communicating whether dewpoint and oxygen levels within the retort are with an acceptable range. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The disclosure itself, and advantages thereof, will best be understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a block diagram representation of the automated measurement and verification computer system, according to some embodiments of the disclosure; 
           [0010]      FIG. 2  is an exemplary operator interface display and operator interface that may be used to implement operator interactions for the verification and measurement processes of the apparatus and method, according to some embodiments of the disclosure; 
           [0011]      FIGS. 3A-3E  depict a flow chart illustrating PLC software control within the automated measurement and verification system and the display unit of the operator interface, according to some embodiments of the disclosure; and 
           [0012]      FIG. 4  is a perspective view of a retort, the control panel of the retort, and the automated measurement and verification system, according to some embodiments of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The disclosure and various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments of the disclosure. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments of the disclosure may be practiced and to further enable those of skill in the art to practice the embodiments of the disclosure. Accordingly, the examples should not be construed as limiting the scope of the disclosure. 
         [0014]    Referring now to the drawings, and with specific reference to  FIG. 1 , a block diagram of the automated measurement and verification system  100  according to some embodiments of the present disclosure is shown. The system  100  may generally include a central processing unit (CPU)  101 , an integrated measuring system  103 , and an operator interface  105 . Each of the foregoing components may be provided on a self-contained portable unit, such as a cart  107  as will be described in greater detail as disclosed herein. 
         [0015]    Breaking the foregoing parts down further and starting with the central processing unit  101 , it may be provided in many different forms including, but not limited to, that of a programmable logic controller (PLC)  108 . The CPU or PLC may include an internal or external memory  109 . The integrated measurement system  103  may include trace or process gas analyzers and sensors to measure and verify atmospheric conditions inside a retort  111 . For example, the integrated measurement system  103  may include an oxygen sensor  113  and a dewpoint sensor  115 . As will be described in further detail herein, the integrated measurement system  103  automates the process of measuring trace gases and atmospheric conditions such as dewpoint and moisture content within the retort. 
         [0016]    The operator interface  105  for either automated or semi-automated operation of the integrated measurement system  103  may be provided by any number of input/output (I/O) devices including, but not limited to, a touch screen display, tablet, mobile, or portable device that may physically attached or docked to the automated measurement and verification system  100 . 
         [0017]    The memory  109  may be part of the PLC, and may include separate high speed random access memory and non-volatile memory, such as one or more magnetic disk storage devices. The memory  109  may alternately include mass storage that is remotely located from the PLC, or may comprise a computer readable storage medium. Memory  109  may store software  117  run by the automated measurement and verification system  100 . 
         [0018]    The automated measurement and verification system  100  may be configured for semi-automated substrate processing allowing an operator to enter desired atmospheric conditions via the operator interface  105  and then enabling measurement and verification of atmospheric conditions inside the retort  111 . The operator is then notified through operator interface  105  that substrate processing under the desired atmospheric conditions can begin, or that such processing cannot begin due to atmospheric conditions having fallen outside operator defined values. 
         [0019]    The automated measurement and verification system of the present disclosure may be performed on a wide-range of retorts. A “retort” in the context of the present disclosure may be any type of chamber with at least one opening and a wall defining an interior space containing a gas atmosphere. If the retort has two or more openings, the openings may be of the same or different size. If there is more than one opening, one opening may be used for the gas inlet for a process method, (e.g. a deposition method such as PECVD), while the other openings are either capped or open. The system may be implemented on any retort equipped for any type of process method, including but not limited to, deposition, annealing, coating, heat treatment, and the like, and any combination thereof, used in the processing of a substrate. For example, such processing methods include without limitation: chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), high density plasma (HDP), pulsed nucleation layer (PNL), pulsed deposition layer (PDL), physical vapor deposition (PVD), annealing furnace, rapid thermal annealing (RTP) furnace, atmospheric pressure CVD (APCVD), sub-atmospheric chemical vapor deposition (SACVD), vapor phase aluminizing techniques (VPA), etching chambers, sintering chambers, spin on chambers, oxidation-resistant environmental coatings, thermally-sprayed bonding coating, pack cementation, slurry coatings, thermal barrier coating (TBC) (e.g. air plasma spraying (APS), vacuum plasma spraying (VPS), high velocity oxy-fuel (HVOF), etc.,), plating (including electroplating and electroless plating) chambers, evaporative coating chambers, the like, and combinations thereof. 
         [0020]    A “substrate” in the context of the present disclosure may, in particular, be, but not be limited to, an aircraft part or component. However, it may also be any other material such as, but not limited to, superconducting, non-conducting, or semiconducting material; intermetallic compound; metal; metal alloy, super alloy, plastic, wood, paper, glass, ceramic, organic, polymeric, or compound material. 
         [0021]    A “process gas” or “trace gas” as used herein may be a single gas or multiple gases such as an inert gas (e.g., He, Ar, or  N2 ), non-inert gas, other gaseous byproducts, and the like. 
         [0022]    A “cycle” or “process cycle” may be a retort measurement or verification step, for example, fine measurement cycle, coarse measurement cycle, or atmospheric conditions within the reaction chamber. Moreover, terms such as “process method”, “process cycle”, and the like, may be used interchangeable without deviating from the nature and scope of the disclosure. 
         [0023]    A “desired level” or “acceptable range” for processing may depend on various factors such as the substrate material processing method, and type of retort. However, for processing gas turbine engine parts, an acceptable range for dewpoint content may be between 0° F. and −40° F., and for oxygen or O 2  content may be 800 parts-per-million (ppm) or less, with other ranges certainly being possible. 
         [0024]    Referring to  FIG. 2 , the operator interface  105  is shown for the automated measurement and verification system  100 . In the depicted embodiment, the operator interface  105  provided in the form of a touch screen display  119 ; although other forms of input/output devices could be employed as mentioned above. A main screen  120  of the display  119  allows the operator to manually start and stop a measuring cycle using measuring cycle start button  122  and measuring cycle stop button  124 , respectively. Moreover, the operator can also view the status of the cycle process in the event log  126 . The operator can view from a cursory glance or, at a distance, where in general the cycle process is through status indicator lights  127 . Such lights  127  may include measuring light  128 , fault light  130 , and complete light  132 . The operator can also record measurements with print button  136 , and select measurement parameters with parameter button  138 . More specifically, the setup button  134  may allow the engineer to enter step times for the measurement and verification steps, for example, initial purge time, coarse measurement time, and fine measurement time, and number of retries for each process. Additionally, the operator may select a specific retort or process type and process parameters for automating substrate processing. The print button  136  allows the operator to select process parameters for printing. The Batch button  138  allows the operator to set the furnace and cycle type, batch number, and Furnace ID number, which are displayed on the main screen  120  as furnace ID number  140 , furnace/cycle type  142 , and batch number  144 . Finally, a countdown timer  145  is provided to show how much time is left in a given cycle being performed. 
         [0025]    Referring to  FIGS. 3A-3E , a flow chart depicting the sequence of steps within the PLC software which may be practiced by the automated measurement and verification system  100  is shown. As shown, operator interaction with the system  100  is through the display unit  119  of the operator interface  105 . The system  100  may process a retort environment in accordance with the following three stages: a purge stage to prepare the environment for processing; a coarse measurement stage to prepare dewpoint and oxygen levels; and a fine measurement stage to set dewpoint and oxygen levels at optimum levels for processing a substrate. Of course, other stages can be included as well and still be within the scope of the present disclosure. 
         [0026]    Starting with the purge stage, and referring specifically to  FIG. 3A , it begins by powering on the system  100  and then following with a predetermined delay, such as but not limited to 30 seconds, for example. After connecting the retort  111  to the system  100 , the operator is prompted to enter process information prior to beginning a cycle to purge the retort  111 . Process information may include, but not be limited to, selecting an equipment type and entering a batch number. Once the process information is confirmed by the operator, cycle start button  122  is enabled, allowing the operator to begin the process of purging the retort environment. Once the cycle start button  122  is pressed, the measuring light  128  turns yellow showing the purge has initiated, a measuring message is displayed on event log  126 , a purge time T 1  is initiated, and an initial purge message is displayed until the period for the purge is completed. Of course, the specific color used may vary, and not be one of the red, green, and yellow colors provided herein as examples. 
         [0027]    Referring to  FIG. 3B , following the purge stage, a coarse measurement stage is initiated for concurrently sampling oxygen and dewpoint levels in the retort  111 . The sampling process of coarse measurement stage may include, but not be limited to, turning on a sample pump, turning on trace gas sensor(s), for example, dewpoint sensor  115  and oxygen sensor  113 , initiating a sampling period time T 2 , and displaying a course measurement message to notify the operator that the sampling process for oxygen and dewpoint has begun. 
         [0028]    In the oxygen portion of the sampling process, oxygen threshold levels are tested for a coarse setpoint. If the coarse setpoint for oxygen has not been reached, the sampling process resumes testing for oxygen coarse setpoint until the sampling period time T 2  is reached. If oxygen coarse setpoint is reached within the sampling period time T 2 , the success of the process is posted to the operator interface  105 , and sampling process continues with the dewpoint portion of the coarse measurement stage described below. If after the sampling period time T 2  the oxygen coarse setpoint is not reached, the cycle is aborted, the measuring light  128  turns red showing the sampling process has failed, and the operator is notified that oxygen coarse setpoint had not been reached within the specified sampling period. The software increments the coarse retry counter and the sampling process is sent to an abort stage. 
         [0029]    In the dewpoint portion of the sampling process, and concurrent with the oxygen sampling process stated above, dewpoint threshold levels are tested for a coarse setpoint. If the coarse setpoint for dewpoint has not been reached, the sampling process resumes testing for dewpoint coarse setpoint until the sampling period time T 2  is reached. If dewpoint coarse setpoint is reached within the sampling period time T 2 , the success of the process is posted to the operator interface  105 , and sampling process continues with the oxygen portion of the coarse measurement stage described above. If after the sampling period time T 2  the dewpoint coarse setpoint is not reached, the cycle is aborted, the measuring light  128  turns red showing the sampling process has failed, and the operator is notified that dewpoint coarse setpoint had not been reached within the specified sampling period. The software increments the coarse retry counter and the sampling process is sent to an abort stage. Once dewpoint and oxygen coarse setpoint levels are reached within the sampling period time T 2  in the coarse measurement stage, the system begins the fine measurement stage. 
         [0030]    Referring to  FIG. 3C , following the coarse measurement stage, a sampling period time T 3  for fine measurement stage is initiated for concurrently sampling oxygen and dewpoint levels in the retort  111 , and a fine measurement message is displayed in event log  126  to indicate to the operator the fine measurement stage has begun. 
         [0031]    In the oxygen portion of the sampling process, oxygen threshold levels are tested for a fine setpoint. If the fine setpoint for oxygen has not been reached, the sampling process resumes testing for oxygen fine setpoint until the sampling period time T 3  is reached. If oxygen fine setpoint is reached within the sampling period time T 3 , the success of the process is posted to the operator interface  105 , and the sampling process continues with the dewpoint portion of the fine measurement system described below. If after the sampling period time T 3 , the oxygen fine setpoint is not reached, the cycle is aborted, the measuring light  128  turns red showing the sampling process has failed, and the operator is notified that oxygen fine setpoint had not been reached within the specified sampling period. The software increments the fine retry counter and the sampling process is sent to an abort stage. 
         [0032]    In the dewpoint portion of the sampling process, and concurrent with the oxygen sampling process stated above, dewpoint threshold levels may be tested for a fine setpoint. If the fine setpoint for dewpoint has not been reached, the sampling process resumes testing for dewpoint fine setpoint until the sampling period time T 3  is reached. If dewpoint fine setpoint is reached within the sampling period time T 3 , the success of the process is posted to the operator interface  105 , and sampling process continues with the oxygen portion of the fine measurement system described above. If after the sampling period time T 3  the dewpoint fine setpoint is not reached, the cycle is aborted, the measuring light  128  turns red showing the sampling process has failed, and the operator is notified that dewpoint fine setpoint had not been reached within the specified sampling period. The software increments the fine retry counter and the sampling process is sent to an abort stage. 
         [0033]    Referring to  FIG. 3D , once dewpoint and oxygen fine setpoint levels are reached within the sampling period time T 3  in the fine measurement stage, the measuring light  128  turns green showing the sampling process for the fine measurement stage has succeeded and a message showing dewpoint and oxygen have reached fine setpoint is displayed in event log  126 . The measuring light  128  is then turned off, and the measurement complete light  132  is turned on. A print message may then be displayed for the operator, and the cycle is ended once a printout request of process results is made. A “cycle complete” message can then be displayed on operator interface  105 . 
         [0034]    Referring to  FIG. 3E , in the event that in the coarse or fine measurement stage an abort request is made, the measuring light  128  turns red showing the sampling process has failed, the fault light  130  turns on, and “cycle failed” message is displayed. The operator is then given the option to abort the cycle or restart the cycle. Once the cycle start button  122  is pressed, the fault light  130  is turned off. In the event that the maximum number of retries for the cycle is not reached, the cycle in which an abort request was made is retried. However, if the maximum number of retries is reached, a message may be displayed to notify the operator that too many retries have been made in the cycle and the operator is requested to contact operations and manufacturing personnel. The cycle is then prevented from starting and the cycle ends. 
         [0035]    Referring to  FIG. 4 , one embodiment of a physical setup between the retort  111  and the automated measurement and verification system  100  is shown. As shown, the automated measurement and verification system  100  may be configured to connect to the retort  111  through a coupler  146 , and to process gases  147  by way of a coupler  148 . In this exemplary embodiment, the automated measurement and verification system  100  may be mounted on or attached to the portable cart  107  allowing the operator and cart  107  to move between substrate processing stations. 
         [0036]    As indicated above, the automated measurement and verification system  100  includes an integrated measurement system for measuring trace gases and atmospheric conditions such as dewpoint and oxygen within the retort  111 . When connected to the retort  111  via the coupler  146 , sensors  113  and  115  sense oxygen and dewpoint levels, respectively, and communicate their findings to an operator through the operator interface  105 . The automated measurement and verification system  100  may also includes a power switch  152  to allow an operator to terminate processing inside the retort  111 , and a stack light  154  mounted on the cart  107  to allow an operator to quickly view, at a distance, the cycle process status. In the exemplified embodiment, the automated measurement and verification system  100  may provide the operator interface  105  in the form of a touch screen panel  119  as indicated above, and may also include a printer  156  for printing process results. 
         [0037]    While the present disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular system, device or component thereof to the teachings of the disclosure without departing from the essential scope thereof. As will be further appreciated, the processes in embodiments of the present disclosure may be implemented using any combination of software, firmware, or hardware. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims. 
       INDUSTRIAL APPLICABILITY 
       [0038]    An example where an automated measurement and verification system can be implemented is in the manufacture of turbines and other components used on gas turbine engines and other aircraft components. For example, aluminide coating processes used in gas turbine engine parts requires the retort environment in which the component is coated or heat treated to be purged with argon or another inert gas to establish proper conditions. Following the purge, an operator typically, and manually, monitors all process parameters to ensure they are achieved and within a certain threshold to prevent causing deficiencies in the processed parts, as well as damage to the measuring equipment. The present disclosure automates the process of purging the retort, and monitoring and verifying retort conditions, thereby freeing up the operator to monitor multiple stations and minimizing human intervention in the manufacturing process. 
         [0039]    It should be understood that various changes and modifications to the present embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present disclosure and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.