Abstract:
An induction hardened processing shaft of a part-processing apparatus and method of manufacturing includes exposing a shaft to a partial induction hardening process. An induction hardening process may be applied to only the portion of the shaft that may be exposed to processing spray or shot peening material. The portion of the shaft exposed to induction hardening will include a harder surface material that can better withstand its composition and structure during impact, minimizing or reducing the amount of wear on the surface from exposure to processing material utilized in the part-processing apparatus. By limiting the induction hardening process to less than the full length of the shaft, the shaft is less likely to experience substantial deformation, and further permits screws and fasters to be driven into the shaft to secure the shaft at specific locations with the processing apparatus.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62/056,151, filed Sep. 26, 2014. The disclosure set forth in the referenced application is incorporated herein by reference in its entirety. 
     
    
     FIELD AND BACKGROUND 
       [0002]    The subject matter disclosed herein relates to an improved component for a part processing apparatus and method of making same, and more particularly to a method of making a shaft for use in retaining parts being processed in an automatic part processing apparatus. More particularly, the present invention relates to an induction hardening shaft of a spindle or other rotational assembly. The part processing apparatus may be similar to the device as shown in U.S. Pat. No. 5,272,897, which is hereby incorporated by reference. In illustrative embodiments, the shaft may be similar to the shaft as shown in U.S. Application No. 61/927,071, filed Jan. 14, 2014, which is hereby incorporated by reference. 
         [0003]    A shaft for a spindle assembly may be used in an automatic part processing apparatus for fully automated processing of a part by methods such as shot peening and the like. A processing apparatus as shown in U.S. Pat. No. 5,272,897 uses a shaft and spindle assembly to hold and rotate parts in the apparatus, the parts positioned on the upwardly extending shaft that is held in place by the spindle assembly coupled to the bottom of the processing apparatus. As the shaft is configured to rotate at continuous and high speeds, the shaft must be relatively straight in order to maintain the part located on the shaft is a fixed position as it rotates. As the parts rotate on the shaft, they are typically exposed to processing media. 
         [0004]    Further, as the shaft is configured to hold up various types of parts, the shaft may be required to be somewhat thick to withstand the pressure of parts or other components without deforming the shaft. A part-hold down assembly may be configured to apply pressure to the parts to maintain them in a fixed position on the shaft while processing occurs. As a result of the weight of the parts and/or the downward pressure from the part-hold down assembly, fasteners, screws or other mechanisms may be attached to or incorporated in the shaft to attach the shaft to a fixed structure in order to prevent the shaft from unintended downward movement through the spindle assembly. For instance, when significant and/or repeated pressure is applied to the shaft to hold the part down during processing, the shaft may tend to slip and the fasteners, screw or other mechanism may prevent such slipping. The material and composition of the shaft must be such as to allow a screw to be driven into the shaft in order to secure the shaft is a specific position. As an alternative, the shaft may be blocked from unintended downward movement by a stepped shaft design, as disclosed in U.S. Application No. 61/927,071, which includes a radial step that abuts against a fixed structure of the spindle assembly to prevent downward movement. With one or more of these features, for example, the part is maintained at a specific height that is predetermined for processing the part, and the part does not slide out of alignment with the processing apparatus. 
         [0005]    As the part is being processed, the shot peening or processing material may unintentionally contact an exposed portion of the shaft holding up the part being processed as well. During operation of the part processing apparatus, an unprocessed part is first placed on the shaft, and then processed, and finally the processed part is removed from the shaft. Another unprocessed part is then placed on the shaft again, and the process is repeated. As the shaft is secured to a turntable in the processing apparatus, it is a permanent fixture in the processing apparatus. As processing continues throughout many cycles of processing, the shafts are continuously blasted with shot peening or other processing material. Over time, the processing material can wear away at the exposed portions of the shaft that are unintentionally sprayed with the processing material, reducing the diameter of the shaft and shortening the useful lifespan of the shaft. Given the specific dimension and strain requirements for a shaft, it may be very difficult to recondition a worn out or used shaft for additional usage. Further, given the positioning of the shaft in a permanent position in the processing apparatus, it is disadvantageous to frequently replace the shaft. 
         [0006]    This background information is provided to provide some information believed by the applicant to be of possible relevance to the present disclosure. No admission is intended, nor should such admission be inferred or construed, that any of the preceding information constitutes prior art against the present disclosure. Other aims, objects, advantages and features of the disclosure will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings. 
       SUMMARY 
       [0007]    It is desirable for a shaft to be hard enough to withstand being continuously exposed to the peening or processing material without being worn away, but at the same time ensure the shaft is both straight and malleable enough to permit items such as screws and fasteners to be secured to the shaft at certain locations to maintain the shaft at the proper height. 
         [0008]    Various induction hardening techniques may be used to harden a work piece. In various applications, induction hardening may be considered a two-step process. First, a non-contact heat treatment process is applied to a surface of a work piece. A current may be generated and applied to the surface of a work piece in order to cause the temperature of the surface to increase. Second, once the surface of the work piece reaches a certain temperature to cause various properties of the material of the work piece to change, the work piece may be quickly cooled or quenched in order to create a harder surface material than the original work piece material. 
         [0009]    Application of a traditional induction hardening technique applied to a shaft of a processing apparatus may create drawbacks. In general, induction hardening of a work piece is known to produce substantial deformation in the work piece, to the point where sometimes the work piece must be further processed or straightened prior to use. Further, induction hardening, by definition, hardens the work piece and prevents or interferes with the ability to engage or insert various components, such as screws, bolts or other fasteners, into or against the surface of the work piece. In particular, a fastener may not engage or tighten properly with a very hard piece of metal because it does not receive the same frictional traction or scoring into a harder piece of material as opposed to a softer piece of material. 
         [0010]    In illustrative embodiments, a partial induction hardening process may be applied to a shaft of a processing apparatus. Specifically, an induction hardening process may be applied to only the portion of the shaft that may be exposed to processing spray or shot peening material. The portion of the shaft exposed to induction hardening will include a harder surface material that can better withstand its composition and structure during impact, minimizing or reducing the amount of wear on the surface from exposure to the peening material. By limiting the induction hardening process to less than the full length of the shaft, the shaft is less likely to experience substantial deformation, and further permits screws and fasters to be driven into the shaft to secure the shaft at specific locations with the processing apparatus. 
         [0011]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present disclosure will be described hereafter with reference to the attached drawings which are given as a non-limiting example only, in which: 
           [0013]      FIG. 1  is a front perspective view of an automatic part processing apparatus of a part by a method such as peening, with a portion broken away to reveal a turntable to which lower spindle assemblies are located, the lower spindle assemblies including rotating shafts that extend upward into a processing field above the turn-table to hold the part being processed; 
           [0014]      FIG. 2  is a partial cross-sectional view of a portion of the spindle assembly of  FIG. 1  above the turntable, showing by way of illustrative and not limitation a part hold-down assembly of the spindle assembly that is applying downward pressure to the part being processed on the rotating shaft, and further showing that the shaft extends from the spindle assembly to retain the part on a support portion of the shaft; 
           [0015]      FIG. 3A  is a side view of the shaft of the spindle assembly of  FIG. 1 , showing the shaft includes a top portion that is configured to extend into the processing field above the turntable and further includes a bottom portion that is configured to be retained outside of the processing field below the turntable; 
           [0016]      FIG. 3B  is a cross-sectional view of a portion of the spindle assembly of  FIG. 1 , showing the shaft extends above and below the turntable, showing the shaft is configured to extend through an aperture of the turntable and through one or more bearing housings and/or a pulley of the spindle assembly, the shaft being secured to the bearing housing via screws or other fasteners that extend into the shaft from the bearing housings and/or pulley at a position on the shaft under the turntable; 
           [0017]      FIG. 4  is a side perspective view of the automatic part processing apparatus showing the part retained on the shaft in a specific position relative to a processing nozzle, and further showing an exposed portion of the shaft in the processing field being in the spray area of the processing nozzle below the part; 
           [0018]      FIG. 5A  is diagrammatic view of the shaft of  FIG. 1  undergoing an illustrative example of a partial induction hardening process; and 
           [0019]      FIG. 5B  is a cross-sectional view of the shaft of  FIG. 5A  after it has undergone the partial induction hardening process of  FIG. 5A , illustrating the hardened surface of the shaft along a portion of the shaft. 
       
    
    
       [0020]    The exemplification set out herein illustrates embodiments of the disclosure that are not to be construed as limiting the scope of the disclosure in any manner. Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived. 
       DETAILED DESCRIPTION 
       [0021]    While the present disclosure may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, embodiments with the understanding that the present description is to be considered an exemplification of the principles of the disclosure. The disclosure is not limited in its application to the details of structure, function, construction, or the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of various phrases and terms is meant to encompass the items or functions identified and equivalents thereof as well as additional items or functions. Unless limited otherwise, various phrases, terms, and variations thereof herein are used broadly and encompass all variations of such phrases and terms. Furthermore, and as described in subsequent paragraphs, the specific configurations illustrated in the drawings are intended to exemplify embodiments of the disclosure. However, other alternative structures, functions, and configurations are possible which are considered to be within the teachings of the present disclosure. Furthermore, unless otherwise indicated, the term “or” is to be considered inclusive. 
         [0022]    As shown in  FIG. 1 , a processing assembly  10  of a larger parts-processing apparatus is shown. The overall parts processing apparatus is similar to that as shown and described in U.S. Pat. No. 5,272,897, incorporated by reference herein. While the basic operation of this parts processing assembly  10  will be described herein, the primary focus of the present application will be on the structures and functions associated with a spindle assembly  62  that supports a part being processed in the processing assembly  10 . 
         [0023]    In illustrative embodiments, the spindle assembly  62  is configured to be permit rotational movement of a part retained on the spindle assembly  62  as it is processed in the processing assembly  10 . In various embodiments, the spindle assembly  62  includes at least a shaft  40  to retain the part in a predetermined position as the part is being processed. During use of the processing assembly  10 , a part  22  can be fixtured on a support portion  24  of the shaft  40 , as illustrated in  FIG. 1 . In order to rotate the part  22  during processing, the spindle assembly  62  rotates the shaft  40 , and in particular the support portion  24 . The part  22  may be of varying forms, but may typically be a hollow component, at least for the present configuration of the apparatus, having a generally cylindrical cavity  26  extending therethrough. An example of such a part  22  might include an automotive gear component. A pin  28  may extend from the support portion  24  through the cavity  26  of the part  22  to help provide axial alignment of the components within the processing assembly  10 . 
         [0024]    While not described herein, reference is made to the incorporated patent, U.S. Pat. No. 5,272,897, with regard to the operation of the overall part processing apparatus. The processing assembly  10  receives a part  22  mounted on the support portion  24  of the shaft  40 , which is then processed in an automated manner. The processing may include automated fixturing of a part hold-down assembly  20  against the part  22 , rotation of the part  22  relative to processing nozzles  50  via rotation of the shaft  40 , and movement of the part  22  on a turntable  12  through a processing path  11 . For example, one type of process used with such processing assembly  10  may be peening. As shown in  FIG. 1 , a series of peening nozzles  50  may be directed in a predetermined vicinity and direction of the parts  22  carried on the support portion  24  of the shaft  40 . While the process itself is not the subject of the present application, the operation of the process is important because it highlights the fact that peening material is introduced and sprayed in a processing field  32  that surrounds the area where the part  22  is being processed. The processing field  32  may be defined at a lower boundary by the top of the turntable  12 , as illustrated n  FIGS. 1 and 4 , as the turntable  12  may block or prevent peening material from exiting the processing field  32 . 
         [0025]    When mounted on the support portion  24 , the part  22  is processed in the processing assembly  10  by movement of the part  22  along the processing path  11 , as shown in  FIG. 1 . The turntable  12  permits the part  22  to travel along the processing path  11  through the processing assembly  10 . Specifically, the processing assembly  10  is configured to carry the part  22  around the processing assembly  10  by rotation of the turntable  12 . Accordingly, a portion of the shaft  40  necessarily extends into the processing field  32 . Consequently, by spraying the part  22  with peening or other processing material, a portion of the shaft  40 , such as external circumferential surface  64  of the shaft  40 , and in particular the support portion  24 , is unintentionally sprayed with such material, as well. The support portion  24  of the shaft  40  holding the part  22  is further connected to one or more spindle assemblies  62  attached to the turntable  12  below the turntable  12 , as illustrated in  FIGS. 1 and 4 . Accordingly, a portion of the surface of the shaft  40  extends outside of the processing field  32  and is blocked from substantial exposure to processing material spray. 
         [0026]    In illustrative embodiments, in addition to the turntable  12  being rotatable to carry the part  22  around the processing assembly  10 , the shaft  40  is also rotatable relative to the turntable  12  in order to rotate the part  22  with respect to an individual nozzle  50 , as illustrated by arrow R in  FIG. 1 . More specifically, the shaft  40  of the processing assembly  10  is configured to extend through an aperture  48  in the turntable  12  and is rotatable with respect to the turntable  12  via the spindle assembly  62  that attaches the shaft  40  to a bottom surface  14  of the turntable  12 , as illustrated in  FIG. 3 . In this manner, the full circumference of the external surface  64  shaft  40  that is within the processing field  32  may be unintentionally sprayed with peening material from a nozzle  50  as a part  22  is being processed. A portion of the spindle assembly  62  is fixedly attached to the bottom surface  14  of the turntable  12  to secure the spindle assembly  62  and shaft  40  with respect to the turntable  12 . In various embodiments, a portion of the shaft  40  may be required to be fixedly attached to the spindle assembly  62  via fasteners or screws that are configured to screw into and past the surface of the shaft  40 , as described in more detail below. 
         [0027]    In this way, the part  22 , and the shaft  40  on which it rests, moves with the turning of the turntable  12  and travels around the processing assembly  10  to be exposed to multiple processing operations along the processing path  11 . In addition, the part  22  and shaft  40  are also movable in a rotational direction R during processing at each of the processing operations, the part being rotatable on the shaft  40  via the spindle assembly  62  which is fixedly secured to the turntable  12 . 
         [0028]    As shown in  FIG. 3 , in illustrative embodiments the shaft  40  is configured to be secured to the spindle assembly  62  in order to ensure the shaft  40  does not slip downward by any variety of known means. For example, the shaft  40  may be secured in an upper bearing  70  of the spindle assembly  62  by a pair of fasteners or set screws  76  extending through a race portion  80  of the upper bearing  70  and into an aperture  71  to abut against and/or insert into the surface of the shaft  40 . Similarly, the shaft  40  may be secured to a lower bearing  72  of the spindle assembly  62  by a pair of fasteners or set screws  78  extending through a race portion  82  of the lower bearing  72  and into an aperture  73  to abut against and extend into the surface  64  of the shaft  40 . The shaft  40  may be secured to the pulley assembly  74  by similar means. In illustrative embodiments, to facilitate maintenance and replacement of the spindle assembly  62  components and the shaft  40 , the fasteners or set screws  76 ,  78  may not be configured to extend through the shaft  40 , but merely screw partially into the outer surface  64  of the shaft  40  to create frictional engagement to hold the shaft  40  in fixed placement with respect to the rest of the spindle assembly  62  components. In other illustrative embodiments, a step  90  may be located around the outer surface  64  of the shaft to abut against the race portion  80  of the upper bearing  70 , further preventing the shaft  40  from slipping downward. 
         [0029]    In illustrative embodiments, the support portion  24  on which the part  22  is supported, or the shaft  40  itself, may be exposed to the peening material being sprayed at the part  22  from the nozzle  50  in the processing field  32 , as illustrated in  FIG. 4 . Specifically, an exposed portion  54  of the shaft  40  in the processing field  32  may be repeatedly subjected to a peening process as various parts are processed in processing assembly  10 . Conversely, a bottom portion  56  of the shaft  40  below the processing field  32  may be located adjacent to the spindle assembly  62  through which the shaft  40  rotates such that the fasteners or set screws  76 ,  78  extend through the surface  64  of the shaft  40  at the bottom portion  56 . 
         [0030]    In order to reduce the amount of wear and tear on the shaft  40  from peening adjacent to the part  22 , while still permitting proper engagement of the fasteners or set screws  76 ,  78  with the shaft  40 , an induction hardening technique  30  is proposed whereby the shaft  40  is only partially hardened at or near the exposed portion  54  of the shaft, while the bottom portion  56  is not exposed to induction hardening. In illustrative embodiments, the induction hardening technique  30  may be applied along a length L of the shaft  40  that is less than the full length of the shaft  40 . For example, the induction hardening technique  30  may be applied only in the areas of the exposed portion  54 , or it may be applied to extend from the exposed portion  54  to the top end  66  of the shaft  40 , before it is received within the processing assembly  10 . 
         [0031]    In an illustrative embodiment, as illustrated in  FIGS. 5A and 5B , the shaft  40  may be treated to an induction hardened technique  30  whereby a non-contact heat treatment process is applied to the length L between the exposed portion  54  and the top end  66  of the shaft  40 , leaving the bottom portion  56  of the shaft  40  to remain substantially the same temperature during the induction hardening technique  30 . The length L may be defined by the surface  64   a  exposed to the induction hardening technique  30  (e.g. the exposed portion  54  of the shaft  40 ). The surface  64   a  is substantially hardened through the induction process, while a surface  64   b  that is not exposed to the induction hardening technique  30  remains substantially the same. In illustrative embodiments, the surface  64   b  may be located along the bottom portion  56  of the shaft  40 . The bottom portion  56  of the shaft  40  may be configured to be located outside the processing field  32 . The surface  64   b  is thereby unhardened and permits fasteners or set screws  76 ,  78  to properly engage with the surface  64   b  of the bottom portion  56  of the shaft  40 . Moreover, as the bottom portion  56  of the shaft  40  is not subject to the induction hardening technique  30 , it will not warp or become deformed, thereby reducing any reprocessing or straightening of the bottom portion  56  of the shaft  40  prior to use. 
         [0032]    Various forms of an induction hardening technique  30  are known in the industry. The present disclosure is not limited in any way to a specific method or process of induction hardening. 
         [0033]    In illustrative embodiments, the shaft  40  may be made of various materials to promote hardening of surface  64   a  from the induction hardening technique  30  while still permitting fasteners or set screws  76 ,  78  to engage with surface  64   b.  In illustrative embodiments, such material may include 4140 alloy steel. 
         [0034]    In illustrative embodiments, the thickness T of the hardened material (e.g. case depth) on the surface  64   a  of the exposed portion  54  of the shaft  40  may be determined based on the desired wear and tear the shaft  40  may be exposed to. In various embodiments, the thickness T may be 1/16 inch or more around the circumferential surface  64   a  of the exposed portion  54 . The thickness T may alternatively be a few thousands of an inch. Other dimensions for thickness T are also envisioned and may be dependent on the specific diameter C 3  of the shaft  40 . 
         [0035]    The foregoing terms as well as other terms should be broadly interpreted throughout this application to include all known as well as all hereafter discovered versions, equivalents, variations and other forms of the abovementioned terms as well as other terms. The present disclosure is intended to be broadly interpreted and not limited. 
         [0036]    While the present disclosure describes various exemplary embodiments, the disclosure is not so limited. To the contrary, the disclosure is intended to cover various modifications, uses, adaptations, and equivalent arrangements based on the principles disclosed. Further, this disclosure is intended to cover such departures from the present disclosure as come within at least the known or customary practice within the art to which it pertains. It is envisioned that those skilled in the art may devise various modifications and equivalent structures and functions without departing from the spirit and scope of the disclosure.