Abstract:
The present invention generally relates to a locating pin assembly for use in precision applications that locate a manufactured part such as gauging or machining. The interchangeable locating pin assembly has: a locating pin housing having a body with an interior portion, and a flange; a locating pin having a tapered head for engaging the manufactured part at a single contact point, and a shank complementary in shape to the interior portion of the housing body; means for axially moving the locating pin relative to the housing between a first extended position, a second partially retracted position, and a third fully retracted position; and means for preventing movement of the pin relative to the housing. The assembly eliminates the need to custom-make a locating pin tailored to each part. The assembly can be made using standard commercial locating pins for use in many manufactured part precision locating applications.

Description:
TECHNICAL FIELD 
     The present invention relates to a locating pin assembly for use in precision applications, more particularly for use in applications that locate a manufactured part such as gauging or machining. 
     BACKGROUND OF THE INVENTION 
     Certain applications require precision location of manufactured parts such as applications that use gauges, holding fixtures, workholding fixture dies, assembly fixtures, and test equipment. The manufactured parts may be made by conventional means well known in the manufacturing or machining arts such as, but not limited to, stamping, casting, molding, and extrusions. In a machining process, it is desirable to use a static locating pin assembly to locate holes in manufactured parts. In such a process, a static pin having a chamfered head and a shaft is permanently attached to a static pin housing. The housing has a flange that is then either press fit or lock-screwed into a mounting block for locating holes in a machining process. There is not a standard width flange used for dimensionally holding the manufactured part in such a process, therefore, a rest pad having a predefined width and a locating surface must be used in combination with the static pin to precisely locate the part. The static pin then operates to locate holes disposed within a manufactured part relative to one another. The manufactured part engages the static pin to locate the holes disposed within the manufactured part. The chamfered head is used to guide the manufactured part towards the shaft of the static pin. The tolerance of the holes capable of encircling the shaft is very narrow using such a static pin. The diameter of the hole on the part being checked must be larger than the diameter of the static pin to provide clearance between the hole and to allow the static pin to properly locate the hole. During manufacturing of the manufactured part, the clearance varies over time between the pin and each hole, thus, making it more difficult for the static pin to properly locate each hole. 
     Another application requiring precision location of manufactured parts is in the gauging process. In the gauging process, a tapered pin assembly is used to locate holes in manufactured parts. Each assembly is typically custom-made for a specific part to be gauged. The custom process involves boring a hole in a tapered pin assembly mounting block, permanently mounting a custom made tapered pin disposed within a custom-made housing to the hole in the tapered pin assembly mounting block, and providing a compression spring between the bottom of the housing and the tapered pin. The surfaces of the assembly must be ground and hardened to provide for an accurate and a durable locating device. The custom-made assembly must be remade each time because an interchangeable pin assembly that is interchangeable with standard commercial locating pins is not readily available. 
     It is desirable to provide a ground locating surface located at a standard height above the mounting block for dimensionally holding the manufactured part. 
     It is desirable to eliminate the need for a rest pad to be used in combination with a locating pin housing as a locating surface. 
     It is desirable to provide a locating pin assembly that may use standard commercial locating pins to be easily and removably mounted into a mounting block. 
     It is desirable to provide a locating pin assembly that may easily locate holes in manufactured parts regardless of the holes&#39; sizes. 
     SUMMARY OF THE INVENTION 
     The devices and assemblies of the present invention are premised upon the discovery of a unique locating pin assembly for locating manufactured parts used in a precision locating process. 
     In general, the interchangeable locating pin assembly has: 
     a) a locating pin housing having a body, the body having an interior portion, and a flange for locating the manufactured part; 
     b) a locating pin having a tapered head for engaging the manufactured part at a single contact point, and a shank complementary in shape to the interior portion of the housing body for slidably engaging the interior portion of the housing body, the shank disposed in axial alignment with the tapered head extending axially downwardly from the tapered head; 
     c) means for axially moving the locating pin relative to the housing between a first extended position, a second partially retracted position, and a third fully retracted position; and 
     d) means for preventing movement of the pin relative to the housing. 
     The present invention thereby meets the needs identified above by providing an improved locating pin assembly for locating manufactured parts. The assembly eliminates the need to custom-make a locating pin tailored to each part. Instead the assembly can be made using standard commercial locating pins that are complementary in shape to standard commercial locating pin housings for use in many manufactured part precision locating applications. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective drawing of one preferred embodiment of an interchangeable locating pin assembly. 
     FIG. 2 is a partial exploded view of an interchangeable locating pin assembly of a preferred embodiment. 
     FIG. 3 is a cross sectional view (taken through FIG. 1) of an interchangeable locating pin assembly according to the present invention. 
     FIG. 4 is a partial perspective view of a preferred embodiment of an interior side of an interchangeable locating pin assembly. 
     FIG. 5 is a top view of a preferred embodiment of an interchangeable locating pin assembly. 
     FIG. 6 is a cross-sectional view of a preferred embodiment of an interchangeable locating pin assembly taken through FIG.  5 . 
     FIG. 7 is a side exploded view of a preferred embodiment of an interchangeable locating pin assembly. 
     FIG. 8 is a partial side view of a preferred embodiment of the interchangeable locating pin assembly positioned in an intermediary partially retracted position. 
     FIG. 9 is a partial perspective view of another preferred embodiment in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1-9, there is generally disclosed an interchangeable locating pin assembly  10  for locating a manufactured part having a locating pin housing  14  and a locating pin  50 . The interchangeable locating pin assembly  10  operates to engage a manufactured part at a single contact point to locate the center axis of a hole disposed within the manufactured part. The assembly  10  further operates to locate the hole of the manufactured part, regardless of the hole size, relative to another location. 
     The locating pin housing  14  and the locating pin  50  are preferably formed from hardened steel, however, the housing  14  and the locating pin  50  may be formed from any suitable solid material that is durable, such as plastic, thus preventing wear during repeated use. Also, preferably, the locating pin housing  14  and the locating pin  50  are coated with a corrosion resistant material such as black oxide, however any corrosion resistant may be used as a coating. 
     The locating pin housing  14  has a body  16  having a hollow interior portion  18  for slidably receiving the locating pin  50 , and a flange  40 . The hollow interior portion  18  is complementary in shape to the locating pin  50 . The body  16  is preferably, cylindrical in shape and has an upper open end  20  integrally formed with the flange  40 , and a lower end  22 . Other tubular geometries are possible, however, in the embodiments shown, the body  16  is cylindrical. Preferably, the lower end  22  is substantially closed having a bottom plug  32  for supporting a spring as discussed further below. The bottom plug  32  preferably, has an opening  30  disposed therethrough to allow for venting of air when the housing  14  receives the locating pin  50 . Optionally, the lower end bottom plug  32  may be manufactured from the same material as the body  16  or may be separately constructed, as shown in the embodiment shown in FIG. 3, the bottom plug  32  is separately constructed from the body  16  and then is integrally formed with the lower end  22  by conventional means such as welding. Optionally, as shown in FIGS. 1-4, and  6 - 9 , the lower end  22  may be chamfered to allow for easy insertion into a mounting block recess. 
     The body  16  further has a wall  24  having a uniform thickness disposed between the upper open end  20  and the lower end  22 . The wall  24  has an inner portion  28 , and an outer portion  26 . The inner portion  28  further defines the hollow interior portion  18  for slidably receiving and engaging the locating pin  50 . Optionally, the wall  24  has an undercut portion  38  disposed within the outer portion  26  of the wall  24  and beneath the flange  40  to allow for machining ground surfaces. 
     In a preferred embodiment, as shown in FIGS. 1-8, the body  16 , preferably, further has an anti-rotate stop pin  36  for slidably engaging a slot disposed within the locating pin  50 . The anti-rotate stop pin  36  is preferably, fixedly attached to the locating pin housing  14  at a distance below the flange  40  equal to a distance less than an axial length of a tapered head of the locating pin  50 . Preferably, when the body  16  is cylindrical, the anti-rotate stop pin  36  protrudes radially inwardly from the inner portion  28  of the wall  24  towards the hollow interior portion  18  of the housing  14 . The anti-rotate stop pin  36  may be removably attached to the inner portion  28  of the wall  24  to allow for removal of the anti-rotate stop pin and for replacement of parts of the locating assembly. However, in an alternative embodiment, the anti-rotate stop pin  36  may be nonremovably attached to the inner portion  28 . The anti-rotate stop pin  36  is preferably used in combination with a diamond head tapered locating pin to prevent rotation of the pin relative to the housing. However, if a round tapered head is used, the anti-rotate stop pin  36  may not be necessary. 
     The flange  40  has a uniform thickness and projects upwardly and outwardly from the upper open end  20  of the body  16 . The flange  40  has an upper planar locating surface  44  for locating and engaging a manufactured part. The upper planar locating surface  44  is preferably ground to provide a smooth surface for engaging and supporting the manufactured part and to provide a thick tolerance for dimensionally holding the part. Additionally, the part is preferably hardened to prevent any abrasions from forming on the manufactured part when the part engages the locating surface  44 . Optionally, as shown in FIGS. 1-9, the flange has a recess  46  disposed therethrough for receiving a locking-screw when the flange  40  is mounted to a mounting block by a locking-screw. Alternatively, the flange  40  may be pressure fit to a mounting block as is well-known in the mechanical and machining arts, though, the flange  40  as shown in the present embodiment incorporates the recess  46 . 
     The locating pin  50  has a tapered head  52  and a shank  66  integrally formed therewith. The tapered head  52  may be integrally formed with the shank  66  as described further below. The tapered head  52  is preferably round or tapered but could be any geometry complementary to a hole disposed within a manufactured part. 
     The tapered head  52  has a top planar surface  54  having a first peripheral edge  56  defining a perimeter of the top planar surface  54 . The tapered head  52  has a base portion  60  having a second peripheral edge  58  defining a perimeter of the base portion  60 . The first peripheral edge perimeter is less than the second peripheral edge perimeter. The tapered head  52  further has a tapered peripheral wall  62  extending outwardly and sloping downwardly at an angle from the top planar surface  54  to the shank  66 . The tapered peripheral wall  62  is further disposed between the first peripheral edge  56  and the second peripheral edge  58  such that the wall is narrower near the first peripheral edge  56  and is wider near the second peripheral edge  58 . 
     Optionally, the tapered head  52  further may have an axial bore  64  for is partially disposed therein for grinding centers and to allow for easy positioning of the locating pin  50  in relation to a grinding machine for grinding surfaces as is well known in the machining arts. 
     The shank  66  is complementary in geometry to the hollow interior portion  18  of the housing  14 . Preferably, as shown in FIGS. 1-9, the shank  66  is cylindrical. The shank  66  has uniform dimensions, and thus has a uniform transverse cross section. The shank  66  is integrally formed with the tapered head  52 . The shank  66  has a uniform cross section, an upper planar end  68 , and a lower planar end  70 . 
     The upper planar end  68  is juxtaposed beneath the base portion  60  of the tapered head  52  wherein the second peripheral edge  58  of the tapered head  52  further defines a perimeter of the upper planar end  68 . The shank  66  further has a uniform peripheral wall  72  extending between the upper planar end  68  and the lower planar end  70 . 
     In a preferred embodiment, as shown in FIGS. 2-4, and  6 - 8 , the shank  66  further has a longitudinal slot  74  disposed through the peripheral wall  72  for allowing travel of the locating pin  50  relative to the housing  14 . Preferably, the length of the slot  74  has a length greater than the axial distance between the top planar surface  54  and the base portion  60  of the tapered head  52 . The slot  74  having a top shelf  76  disposed below the upper planar end  68  of the shank  66 , and a bottom shelf  78  extending downwardly from the top shelf  76  a distance greater than a longitudinal length along a center axis  80  of the locating pin  50  of the tapered head  52  between the top planar surface  54  and the base portion  60 . The top shelf  76  defines a first stop member for preventing downward longitudinal movement along the locating pin center axis  80  beyond a fully retracted position of the locating pin  50  relative to the housing  14  when the housing anti-rotate stop pin  36  engages the top shelf  76 . The bottom shelf  78  defines a second stop member for preventing upward longitudinal movement along the locating pin center axis  80  beyond a fully extended position of the locating pin  50  relative to the housing  14  when the housing anti-rotate stop pin  36  engages the bottom shelf  78 . 
     The interchangeable locating pin assembly  10  further has means for preventing movement between the locating pin  50  relative to the housing  14 . The means for preventing movement has a compression spring  82  disposed between the lower end bottom plug  32  and the locating pin  50 . In one embodiment, as shown in FIGS. 3, and  6 - 8  the spring  82  engages the upper end bottom plug  32  and the lower planar end  70  of the shank  66 . However, alternatively, the spring  82  may engage the lower end upper plug  32  and an interior portion within the shank  66 . As shown in one embodiment, the spring  82  cooperates with the anti-rotate stop pin  36  and the slot  74  to prevent axial movement of the shank  66  relative to the housing  14 . 
     The longitudinal slot  74  and the anti-rotate stop pin  36  cooperate to define means for axially moving the locating pin relative to the housing between a first extended position, a second partially retracted intermediary position, and a third fully retracted position. 
     In an alternative embodiment, as shown in FIG. 9, an optional slot  84  for controlling travel of the locating pin  50  relative to the housing  14  is formed through the inner portion of the wall  24  of the body  16 . A recess  86  is disposed within the peripheral wall  72  of the shank. Preferably, the recess  86  is threaded for receiving a removable set-screw  88 . The set-screw  88  cooperates with the slot  84  in the housing  14  to control travel of the locating pin  50  relative to the housing  14 . 
     In general, the locating pin assembly  10  can be used in many applications for locating holes such as in gauging or machining applications. The locating pin assembly  10  may be used in a gauge checking device. The gauge checking device may have a mounting block having two recesses for receiving two interchangeable locating pin assemblies  10 , a clamping assembly for clamping a manufactured part to the mounting block, and a check pin for checking the location of a first hole disposed within the manufactured part relative to a second and a third hole, disposed within the manufactured part. Advantageously, the clamping assembly may have a clamp arm, a clamp fastening assembly, and a clamp mounting block. 
     In operation, before engaging the manufactured part, the locating pin is biased in the first fully extended position. Then, the hole of the manufactured part engages the locating pin at a single contact point on the tapered head  52 . Center axis of the second and third holes are located upon the manufactured part engaging the locating pins  10 , at respective single contact points. The clamp arm engages the manufactured part and securely clamps the manufactured part with respect to the clamp mounting block thereby preventing movement of the manufactured part relative to the mounting block  94 . 
     When the manufactured part engages the tapered heads  52  at the single contact point, the anti-rotate stop pin  36  slidably engages the slots  74  in a position between the top shelf and the bottom shelf thereby compressing the spring and moving the locating pin from the first extended position to either the second partially retracted position or the third fully retracted position within the housing. 
     Alternatively, when the manufactured part engages the tapered head  52  at the single contact point, the set screw  88  slidably engages the housing slot  84  thereby compressing the spring and moving the locating pin  50  from the first extended position respectively to either the second partially retracted position or the third fully retracted position. 
     The clamping process moves the locating pin  50  to the second partially retracted position if the diameter of the second hole is greater than the first peripheral edge  56  perimeter of the tapered head  52  but is less than the second peripheral edge  58  perimeter of the tapered head  52 ; or to a fully retracted position if the diameter of the second hole is equal to or less than the first peripheral edge  56  perimeter of the tapered head  52 . The movement of the locating pin  50  relative to the housing  14  stops when the manufactured part engages the upper planar locating surface  44  of the flange  40 . The first hole position is then checked by the check pin to determine if the first hole is properly located relative to the second and third hole respectively. Thus, the locating pin assemblies  10 , operates to locate holes on the manufactured part. 
     It will be appreciated from the above that the needs in the art are met by the devices and assemblies of the present invention. 
     While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.