Abstract:
An expansion assembly includes a connecting plug, a deformable sealing sleeve, and an expansion sleeve. The connecting plug defines a through hole configured for air flow to pass therethrough. The deformable sealing sleeve is sleeved on the connecting plug. The expansion sleeve houses the deformable sealing sleeve and is sleeved on the connecting plug. The expansion sleeve comprises a number of resilient arms separated from each other. When airflow is introduced into the deformable sealing sleeve via the connecting plug, the deformable sealing sleeve is expanded, causing the number of resilient arms of the expansion sleeve to expand outward. A positioning mechanism employing the expansion assembly is also disclosed.

Description:
FIELD 
       [0001]    The present disclosure generally relates to a positioning mechanism and an expansion assembly thereof. 
       BACKGROUND 
       [0002]    A positioning mechanism is usually employed to position a workpiece on a worktable for machining or inspecting the workpiece. The positioning mechanism can be a pin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0003]    The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0004]      FIG. 1  is an assembled, isometric view of an embodiment of a positioning mechanism, the positioning mechanism including an expansion assembly. 
           [0005]      FIG. 2  is an exploded, isometric view of the positioning mechanism of  FIG. 1 . 
           [0006]      FIG. 3  is a cross-sectional view of the positioning mechanism of  FIG. 1 , taken along line III-III. 
           [0007]      FIG. 4  is a cross-sectional view of the positioning mechanism of  FIG. 1 , taken along line IV-IV. 
           [0008]      FIG. 5  is a sectional view of the expansion assembly of  FIG. 1  in use. 
           [0009]      FIG. 6  is an enlarged view of circled portion VI of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one.” The references “a plurality of” and “a number of” mean “at least two.” The term “coupled” is defined as coupled, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently coupled or releasably coupled. 
         [0011]      FIG. 1  illustrates an embodiment of a positioning mechanism  100  to position a workpiece (not shown) defining a positioning hole. The positioning mechanism  100  can include a base seat  10 , an expansion assembly  30  mounted to the base seat  10 , and a covering plate  50  sleeved on the expansion assembly  30  and secured to the base seat  10 . An outer air source/hydraulic source can be adopted to provide power for the positioning mechanism  100 . In the embodiment, the positioning mechanism  100  can adopt the outer air source to provide the power. 
         [0012]    Referring to  FIGS. 2 through 4  the base seat  10  can define a substantially L-shaped fluid conduit  11  therein. The fluid conduit  11  can include an entrance line  112  oriented along a longitudinal direction of the base seat  10 , and a connecting line  113  substantially perpendicularly coupled to the entrance line  112 . The connecting line  113  can open through a top of the base seat  10 . A governor joint  115  can be coupled to the entrance line  112  and coupled to the outer air source to introduce airflow into the fluid conduit  11 . The base seat  10  can further define an annular positioning groove  117 , which can surround a periphery of an end of the connecting line  113 . 
         [0013]    The expansion assembly  30  can include a connecting plug  31 , a deformable sealing sleeve  33 , an expansion sleeve  35 , and a protection block  37 . The connecting plug  31  can be stepped-columnar shaped and coupled to the connecting line  113  of the base seat  10 . The connecting plug  31  can include a resisting portion  312 , a sleeving portion  313  coaxially protruding from one side of the resisting portion  312 , and a sealing portion  315  coaxially protruding from a distal end of the sleeving portion  313 . A diameter of the sleeving portion  313  is less than a diameter of the resisting portion  312 , but greater than a diameter of the sealing portion  315 . The connecting plug  31  can axially define a through hole  3121 . The through hole  3121  is cooperatively defined by the resisting portion  312 , the sleeving portion  313 , and the sealing portion  315 . The through hole  3121  can be aligned to an opening of the connecting line  113 . 
         [0014]    The deformable sealing sleeve  33  can be a substantially hollow cylinder and can define a sealing hole  331  in one end thereof. The deformable sealing sleeve  33  can be sleeved onto the sealing portion  315  of the connecting plug  31  via the sealing hole  331  to hermetically seal the deformable sealing sleeve  33 . In the embodiment, the deformable sealing sleeve  33  can be made of soft materials, such as rubber. When the airflow from the fluid conduit  11  flows into the deformable sealing sleeve  33 , the deformable sealing sleeve  33  can be expanded. 
         [0015]    The expansion sleeve  35  can house the deformable sealing sleeve  33  and be sleeved on the sleeving portion  313  of the connecting plug  31 . An outer periphery of the deformable sealing sleeve  33  can resist against an inner periphery of the expansion sleeve  35 . The expansion sleeve  35  can include an expansion portion  351 , and a fixing portion  353  protruding from an end of the expansion portion  351 . The expansion portion  351  can be a substantially hollow cylinder and be sleeved on the deformable sealing sleeve  33  and the sleeving portion  313 . The expansion portion  351  can define an opening  3512  in an end thereof away from the fixing portion  353 , and a restricting hole  3513  in a periphery thereof. The restricting hole  3513  can be defined adjacent to the opening  3512 . The expansion sleeve  35  can be sleeved on the sleeving portion  313  via the opening  3512 . The periphery of the expansion portion  351  can define a plurality of slits (not labeled) oriented along a longitudinal direction of the expansion sleeve  35 , thereby forming a plurality of resilient arms  3515 . Each resilient arm  3515  is formed between two adjacent slits. Each resilient arm  3515  can expand radially outward from the expansion sleeve  35 . In an embodiment, the expansion sleeve  35  can be made of metallic materials having high elasticity, such as spring steel. When the workpiece is sleeved on the expansion sleeve  35 , the plurality of resilient arms  3515  can be expanded radially outward by expansion of the deformable sealing sleeve  33  received in the expansion sleeve  35 , causing the plurality of resilient arms  3515  to resist against an inner periphery of the positioning hole of the workpiece. The fixing portion  353  can have a diameter less than a diameter of the expansion portion  351 . The protection block  37  can be sleeved on the fixing portion  353  and resist an end portion of the expansion portion  351 , to prevent the expansion sleeve  35  from damaging the workpiece when the expansion sleeve  35  expands. In the embodiment, the protection block  37  can be made of rubber. 
         [0016]    The covering plate  50  can be sleeved on the expansion sleeve  35  and be secured to the base seat  10 . The covering plate  50  can define a fixing hole  51  corresponding to the connecting line  113 . The fixing hole  51  can be a stepped hole, which includes a receiving portion  512  and a latching portion  513 . The expansion sleeve  35  can be partially received in the fixing hole  51  and partially extend out of the covering plate  50 . The latching portion  513  can be adjacent to the connecting line  113  of the base seat  10 . The resisting portion  312  of the connecting plug  31  can be received in the latching portion  513 . The sleeving portion  313  and the sealing portion  315  of the connecting plug  31  can be received in the receiving portion  512 . The covering plate  50  can further define an inserting hole  53  in a side thereof. The inserting hole  53  can extend to the fixing hole  51 . The inserting hole  53  can be aligned to the restricting hole  3513  of the expansion sleeve  35 . 
         [0017]    In the embodiment, the positioning mechanism  100  can further include a jack screw  70  for positioning the expansion sleeve  35 , and a sealing ring  90 . An end of the jack screw  70  can be latched within the restricting hole  3513  of the expansion sleeve  35 , and another end of the jack screw  70  can be received in the inserting hole  53  to prevent the jack screw  70  from detaching from the covering plate  50 . The sealing ring  90  can be received in the positioning groove  117  to hermetically seal the covering plate  50  and the base seat  10 . 
         [0018]    In assembly, the sealing ring  90  can be received in the positioning groove  117  of the base seat  10 . The connecting plug  31  can be received in the fixing hole  51 , such that the resisting portion  312  is received in the latching portion  513 , and the sleeving portion  313  and the sealing portion  315  are received in the receiving portion  512 . The deformable sealing sleeve  33  can be sleeved on the sealing portion  315  of the connecting plug  31  via the sealing hole  331 . The expansion sleeve  35  can be sleeved on the sleeving portion  313  of the connecting plug  31  via the opening  3512 , and the inner periphery of the expansion sleeve  35  can contact the outer periphery of the deformable sealing sleeve  33  in an unexpanded state. The covering plate  50  can be secured to the base seat  10 , and the expansion sleeve  35  can extend through the fixing hole  51  of the covering plate  50 . The jack screw  70  can be received in the inserting hole  53  of the covering plate  50  and latch in the restricting hole  3513  of the expansion sleeve  35 . The governor joint  115  can be coupled to the entrance line  112  of the base seat  10  and to the outer air source. 
         [0019]    In use, the workpiece can be sleeved on the expansion sleeve  35  via the positioning hole. The airflow can be introduced into the fluid conduit  11  via the governor joint  115 , and enter into the deformable sealing sleeve  33  via the through hole  3121 . The deformable sealing sleeve  33  can be expanded by the airflow, thereby causing the plurality of resilient arms  3515  to expand outward to tightly resist the inner side of the positioning hole of the workpiece. 
         [0020]      FIGS. 5 and 6  show the expansion assembly  30  used to position a first workpiece  201  and a second workpiece  203  together. The through hole  3121  of the connecting plug  31  can fluidly couple to the outer air source. In use, the expansion assembly  30  can extend through a positioning hole  2012  of the first workpiece  201  and the second workpiece  203 . Airflow can flow into the deformable sealing sleeve  33 . The deformable sealing sleeve  33  can be expanded by the airflow, thereby causing the plurality of resilient arms  3515  to expand outward to tightly resist the inner side of the positioning hole  2012  of the first workpiece  201  and the second workpiece  203 . Thus, the first workpiece  201  and the second workpiece  203  are positioned together. 
         [0021]    In other embodiments, the protection block  37  can be omitted. When the resisting portion  312  of the connecting plug  31  hermetically seals the base seat  10  and the covering plate  50 , the sealing ring  90  can be omitted. When the expansion sleeve  35  is securely received in the covering plate  50 , the jack screw  70  can be omitted. 
         [0022]    While the present disclosure has been described with reference to particular embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Therefore, those of ordinary skill in the art can make various modifications to the embodiments without departing from the true spirit and scope of the disclosure, as defined by the appended claims.