Patent Publication Number: US-2015079288-A1

Title: Plug assembly for masking threaded holes

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to manufacturing of a metallic component. More specifically, the present disclosure relates to a plug assembly for masking the threaded holes while manufacturing the metallic component. 
     BACKGROUND 
     Engines commonly include various metallic components, such as engine blocks, which undergo wear and tear during prolonged and continuous operations. These metallic components are required to be manufactured for reuse. “Manufacturing” herein refers to reforming of the metallic component to correct dimensions by coating the metallic component with the same or the different material as that of the metallic component. Various manufacturing processes, such as a thermal spray process, may be used to manufacture a metallic component. In the thermal spray process, the metallic component is coated with a coating material to correct the dimensions of the metallic component. Further, the metallic component commonly includes threaded holes that require protection from the coating material during the thermal spray process. Therefore, a plug assembly may be required to protect the threaded hole during the thermal spray process. 
     Conventionally, a cylindrical mask plug made of rubber material were used to mask the threaded hole. The mask plug would be inserted in the threaded hole before coating the metallic component. The mask plug of completely cylindrical shape may be insufficient to mask the threaded hole, and some coating material may still flow through the threaded hole. This results result in poor quality of the threaded hole after completion of manufacturing of the metallic component. Moreover, once the thermal spray process is completed, the mask plug needs to be removed from the metallic component using various machining processes known in the art. These machining processes may be laborious and cumbersome to perform and are also likely to damage the threaded hole during operation. This results in poor quality of threaded hole after completion of the manufacturing process. 
     U.S. Pat. No. 7,147,899 discloses a method of masking cooling holes of a gas turbine component. The method includes applying mask material to the cooling holes, thickening the mask material, coating the gas turbine component, and removing the remaining mask material from the cooling hole. Although this reference provides the method of masking the cylindrical cooling hole of the gas turbine component with a mask material and removing the remaining mask material by use of various machining processes, no solution is provided for masking the threaded hole of the metallic component that can be removed without use of such machining processes. 
     SUMMARY OF THE INVENTION 
     One aspect of the present disclosure is directed to plug assembly for masking internal threads of a base component. The plug assembly including a plug member having peripheral margin portions engagable with the internal threads of the base component. The plug member consists of a water-soluble material and is structured and arranged to dissolve in a water based liquid. 
     Another aspect of the present disclosure is directed to a method of manufacturing a metallic component. The metallic component having at least one threaded hole. The at least one threaded hole having internal threads. The method includes masking the at least one threaded hole using a plug member. The plug member consisting of a water soluble material. Masking the at least one threaded holes includes inserting the plug member in the at least one threaded hole, coating the external surface, and de-masking the at least one threaded hole. Insertion of the plug member in the at least one threaded hole of the metallic component facilitates covering of the internal threads of the at least one threaded hole. Thereafter, the external surface of the metallic component is coated with a coating material. After coating the at least one threaded hole is de-masked by causing the plug member to dissolve by exposing the plug member to a water-based liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a portion of an engine having at least one threaded hole, in accordance with the concepts of the present disclosure; 
         FIG. 2  is a cross-sectional view of a plug assembly that protects internal threads within the at least one threaded hole of a metallic component of  FIG. 1 , in accordance with the concepts of the present disclosure; 
         FIG. 3   a  is a cross-sectional view of an assembly of the metallic component and a first embodiment of the plug assembly, describing insertion of the plug assembly in the at least one threaded hole; 
         FIG. 3   b  is a cross-sectional view of the assembly of the metallic component and a second embodiment of the plug assembly, describing insertion of the plug assembly in the at least one threaded hole; 
         FIG. 4  is a cross-sectional view of the assembly of the metallic component and the plug assembly, describing coating of the metallic component by thermal spray process; 
         FIG. 5  is a cross-sectional view of the assembly of the metallic component and the plug assembly, describing de-masking of the at least one threaded hole, in accordance with the concepts of the present disclosure; 
         FIG. 6  is cross-sectional view of a portion of the metallic component after completion of the manufacturing process; and 
         FIG. 7  is a flow chart that depicts an exemplary method of manufacturing the metallic component by use of the thermal spraying process. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , there is shown a portion of an engine  100  having a base component. The base component of the engine  100  may be a metallic component  102  that needs to be manufactured to its correct dimensions. The engine  100  may embody a petrol engine, a diesel engine, a dual-fuel engine, and/or such similar engines. Although, the concepts of the present disclosure are directed towards the metallic component  102  of the engine  100 , it may be contemplated that the concepts of the disclosure may be applied to the metallic components of various other machines such as a generator, a turbine, and/or such similar machines. Concepts of the present disclosure may also be employed to applications that include non-metallic components. 
     In the current embodiment of the disclosure, the metallic component  102  is an engine block, that includes an external surface  104 , holes  105  and at least one threaded hole  106  in the metallic component  102 . As is customarily known, the threaded hole  106  of the metallic component  102  includes internal threads  108  (as shown in  FIGS. 3-6 ) that facilitate mounting of various other components of the engine  100  to the metallic component  102 . Furthermore, the metallic component  102  may occasionally require to be manufactured. In a manufacturing process, the dimensions of the metallic component  102  may be corrected so that it can be used for different process requirements. The manufacturing process of metallic components  102 , may involve operations such as, boring, honing, grinding, micro-polishing, resurfacing, surface coating, re-aligning, etc. In the current embodiment of manufacturing process, a thermal spray process is performed to add the external surface  104  over the metallic component  102  with a coating material  304  (as shown in  FIGS. 4-6 ). It may be noted that during the manufacturing process, the threaded hole  106  needs to be masked. Masking of the metallic component  102  includes inserting a plug assembly  202  (as shown in  FIG. 2 ) in to the threaded hole  106 , coating the external surface  104  of the metallic component  102 , and then de-masking the plug assembly  202  (as shown in  FIG. 2 ) to obtain a manufactured metallic component  102 . 
     Referring to  FIG. 2 , there is shown the plug assembly  202  that masks the threaded hole  106 , during manufacturing process. The plug assembly  202  includes a plug member  204  made up of a water-soluble material and is structured and arranged to dissolve in a water based liquid  504  (as shown in  FIG. 5 ). It may be envisioned that the plug member  204  may be made of any water-soluble material, such as but not limited to, Monopol C100, ISOBAM, cellulose, and/or similar polymer compounds. The plug member  204  may be a cylindrical member having peripheral margin portions  206  engagable with internal threads  108  of the metallic component  102 . In a first embodiment, the peripheral margin portions  206  of the plug member  204  includes external threads  208  that are made conjugate to the internal threads  108  of the threaded hole  106 , as best seen in  FIG. 3   a.  The external threads  208  may be manufactured by any of the known thread-cutting techniques known in the art, such as but not limited to, the thread milling method, taps and dies method, and the like. 
     Referring to  FIG. 3   a - 6 , there is shown the step-wise illustration of masking process of the metallic component  102 . It may be envisioned that before initiating the masking process, the external surface  104  and the internal threads  108  of the metallic component  102  may be cleansed by any of the known methods, such as but not limited to, grinding, shaping, oil treating. 
     Referring to  FIG. 3   a,  there is shown an assembly of the metallic component  102  and the first embodiment of the plug assembly  202 , describing insertion of the plug member  204 . The masking process initiates with insertion of the plug member  204  in to the threaded hole  106  of the metallic component  102  to protect the internal threads  108 . Preferably, the plug member  204  may be inserted in to the threaded hole  106  by screwing or fastening the plug member  204  to the threaded hole  106 . When the plug member  204  is fastened with the threaded hole  106 , the external threads  208  of the plug member  204  meshes with the internal threads  108  of the threaded hole  106 . This facilitates an air tight sealing of the threaded hole  106 . Moreover, during assembly of the plug member  204  with the metallic component  102 , there may be a possibility of a certain portion of the plug member  204  that protrudes outside the external surface  104 . The portion of plug member  204  that protrudes outside of the external surface  104  may be machined flush to the external surface  104  by various known techniques in the art, such as, but not limited to, milling, shaping, planning, and other similar techniques. 
     Referring to  FIG. 3   b,  there is shown an assembly of the metallic component  102  and a second embodiment of the plug assembly  202 ′, describing insertion of the second embodiment of the plug assembly  202 ′. The plug assembly  202 ′ in the second embodiment includes a cup-shaped plug member  204 ′. The plug member  204 ′ defines a peripheral margin portions  206 ′ and a flange portion  210 . The plug member  204 ′ is inserted in to the threaded hole  106  so that the peripheral margin portions  206 ′ makes a tight fit with the internal threads  108  of the metallic component  102 . In that position, the flange portion  210  of the plug member  204 ′ may rest on the external surface  104  of the metallic component  102 . Subsequently, the flange portion  210  may be machined flush to the external surface  104  to obtain a planar external surface  104 . It may be noted that the forthcoming FIGS. may describe further steps of masking process in accordance with the first embodiment of the plug assembly  202 , however use of second embodiment of the plug assembly  202 ′ may also be envisioned. 
     Referring to  FIG. 4 , there is shown the assembly of the metallic component  102  and the first embodiment of the plug member  204 , describing coating of the metallic component  102  using thermal spray process. In the thermal spray process, a thermal spray torch  302  is used to spray hot molten coating material  304  on top of the external surface  104  of the metallic component  102 . The thermal spray torch  302  may work on the principle of plasma spraying, detonation spraying, wire arc spraying, and/or similar operating principles. The molten coating material  304  forms a uniform coating and adheres to the external surface  104  when cooled. It may be contemplated that the coating material  304  may be of same material as that of the metallic component  102  and/or an alloy of the material of the metallic component  102 . 
     Referring to  FIG. 5 , there is shown the assembly of the metallic component  102  and the plug member  204  being dipped in a hot-water bath  502 , describing de-masking of the metallic component  102 . After coating, a core of the plug member  204  may be drilled out and the assembly of the metallic component  102  and the plug member  204  may be introduced to a hot-water bath  502  to perform de-masking. The hot-water bath  502  may contain the water based liquid  504 , such as hot-water maintained at a pre-determined range of temperature. As the plug member  204  is made of water soluble material, the plug member  204  may dissolve in the water based liquid  504 , when introduced to the hot-water bath  502 . However, the present disclosure contemplates drilling of the core of the plug member  204  before being introduced to the hot-water bath  502 , it may be envisioned that drilling the core of the plug member  204  does not limit the scope of the present disclosure. 
     Referring to  FIG. 6 , there is shown the cross-sectional view of the metallic component  102  after completion of the masking process. In the final state, the coating material  304  is coated on the external surface  104  of the metallic component  102  and without any damage to the threaded hole  106 . Thereafter, the metallic component  102  may be installed and used in the engine  100  ( FIG. 1 ) after performing certain finishing operations, such as but not limited to, grinding, filing, shaving, polishing, and the like. 
     Referring to  FIG. 7 , there is shown a flow chart that depicts the method  700  of the manufacturing process that has been performed on the metallic component  102 . The method  700  initiates at step  702 . 
     At step  702 , the threaded hole  106  of the metallic component  102  is masked. Masking of the metallic component  102  refers to protection of the threaded hole  106 . Masking includes insertion of the plug member  204  in the threaded hole  106 , coating the external surface  104 , and de-masking the threaded hole  106 . It may be noted that various steps of masking process may be explained in the forthcoming steps of the method  700 . 
     At step  704 , the plug member  204  is inserted in to the threaded hole  106  of the metallic component  102 . The plug member  204  may be inserted by screwing the plug member  204  with the threaded hole  106 . The screwing of the plug member  204  with the threaded hole  106  facilitates sealing of the threaded hole  106 . Thereafter, the method  700  proceeds to step  706 . 
     At step  706 , the coating material  304  is sprayed on the external surface  104  of the metallic component  102  to coat the external surface  104 . This enables the coating of the external surface  104 . Once the coating is performed on the external surface  104 , the method  700  proceeds to step  708 . 
     At step  708 , the plug member  204  is de-masked from the metallic component  102 . The assembly of the metallic component  102  and the plug member  204 , after being coated, is introduced to the hot-water bath  502 , thereby causing the plug member  204  to be removed from the metallic component  102 . 
     Industrial Applicability 
     In operation, the metallic component  102  of the engine  100  may require to be manufactured. While manufacturing the metallic component  102 , the threaded hole  106  may require to be masked. Moreover, during masking of the threaded hole  106 , the metallic component  102  broadly undergoes insertion, coating, and de-masking. Initially, the plug member  204 ,  204 ′ of the plug assembly  202 ,  202 ′ is inserted in to the threaded hole  106  of the metallic component  102 . This facilitates engaging the threaded hole  106  with the plug member  204 ,  204 ′. 
     Once the threaded hole  106  is inserted, the metallic component  102  is exposed to the coating process. In the coating process, the thermal spray torch  302  sprays hot molten coating material  304  on the external surface  104  of the metallic component  102 . Since, the plug member  204 ,  204 ′ is already inserted in in the threaded hole  106 , there is no flow of coating material  304  in to the threaded hole  106  during the coating process. This facilitates coating of the external surface  104 , while protecting the threaded hole  106  from the coating material  304 . After the coating process, the metallic component  102  is cooled and then undergoes the de-masking process. 
     In the de-masking process, the assembly of the metallic component  102  fitted with the plug member  204 ,  204 ′ is submersed in a hot-water bath  502 . The plug member  204 ,  204 ′ being made of water-soluble material, dissolves in the hot-water bath  502 . Therefore, the plug member  204 ,  204 ′ is removed from the threaded hole  106  when introduced to the hot-water bath  502 . As the plug member  204 ,  204 ′ is removed by feeding in to the hot-water bath  502 , it avoids any additional labor and effort associated with removing thermal coating from threads of the threaded hole  106  which is cumbersome and time consuming Also, the removal of the plug member  204 ,  204 ′ by dissolving the same in the hot-water bath  502  better protects the internal threads  108  of the threaded hole  106  which may be otherwise damaged or unclean if the thermal coating was allowed to attach to and diminish the integrity of the threads of the threaded hole  106  of the metallic component  102 . 
     It should be understood that the above description is intended for illustrative purposes only and is not intended to limit the scope of the present disclosure in any way. Those skilled in the art will appreciate that other aspects of the disclosure may be obtained from a study of the drawings, the disclosure, and the appended claim.