Abstract:
A gripping apparatus is disclosed. The gripping apparatus includes a first finger including a plurality of first sawteeth along a first longitudinal end and a receiving area being located between adjacent sawteeth and a second finger including a plurality of complementary sawteeth juxtaposed from the first sawteeth. One of the first and second fingers is movable relative toward the other of the first and second fingers such that an object to be gripped is positioned in the receiving area by one of the plurality of complementary sawteeth. The object is releasably retained against the receiving area by the second finger. A method of gripping an object is also disclosed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to grippers which are used to correct alignment of and to load electrical terminals into precise tooling, as well as a method used to precisely grip an object. 
     BACKGROUND OF THE INVENTION 
     Currently, many insert-molding applications involve the placement of multiple electrical terminals into a mold cavity with precise insertion into a core slide. This core slide usually forms a portion of molded plug geometry around the electrical terminals. With today&#39;s modem electrical connectors, smaller watertight and even airtight designs are quickly becoming the standard in the automotive and computer industries. The designs, therefore, require tighter tolerances and more precise part-to-part tolerances than before. Current automated assembly and molding processes are not successful in ensuring absolute quality and yield. 
     It would be beneficial to provide a tool which can grasp and locate electrical terminals in a desired location during precision manufacturing, and improving the quality and yield of a manufactured product. 
     BRIEF SUMMARY OF THE INVENTION 
     A gripping apparatus is provided. The gripping apparatus comprises a first finger including a plurality of first sawteeth along a first longitudinal end and a receiving area being located between adjacent sawteeth and a second finger including a plurality of complementary sawteeth juxtaposed from the first sawteeth. One of the first and second fingers being movable relative toward the other of the first and second fingers such that an object to be gripped is positioned in the receiving area by one of the plurality of complementary sawteeth. The object is releasably retained against the receiving area by the second finger. 
     A method of gripping an object is also provided. The method comprises locating the object between first and second fingers, the first finger including a plurality of first sawteeth along a first longitudinal side, a receiving area being located between adjacent sawteeth and the second finger including a plurality of complementary sawteeth juxtaposed from the first sawteeth; and moving one of the first and second fingers relative toward the other of the first and second fingers, the first and second fingers maneuvering the object between the receiving area and the second finger, the second finger releasably retaining the object against the receiving area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein, and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings: 
     FIG. 1 is a perspective view of a preferred tool which employs a gripper according to a preferred embodiment of the present invention in an open position; 
     FIG. 2 is a perspective view of the preferred tool which employs a gripper according to a preferred embodiment of the present invention gripping two electrical terminal blades; 
     FIG. 3 is an enlarged side view of a lower portion of a first embodiment of a pair of gripper fingers in an open position with objects to be gripped therebetween; 
     FIG. 4 is an enlarged side view of the lower portion of the first embodiment of the pair of gripper fingers in a closed position gripping the objects; 
     FIG. 5 is an enlarged side view of a lower portion of a second embodiment of a pair of gripper fingers in an open position with objects to be gripped therebetween; 
     FIG. 6 is an enlarged side view of the lower portion of the second embodiment of the pair of gripper fingers in a closed position gripping the objects; 
     FIG. 7 is an enlarged side view of a lower portion of a third embodiment of a pair of gripper fingers in an open position with objects to be gripped therebetween; and 
     FIG. 8 is an enlarged side view of the lower portion of the third embodiment of the pair of gripper fingers in a closed position gripping the objects. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of a gripping apparatus  2  used to grip terminal blades  300 ,  310  during assembly of a fuel injector is shown in FIGS. 1 and 2. The gripping apparatus  2  is preferably part of an automated assembly line which manufactures fuel injectors, although those skilled in the art will recognize that the present invention can be used on other types of precision manufactures as well, such as circuit boards. A fuel injector having terminal blades which can be inserted into the fuel injector assembly using the apparatus and method of the present invention is disclosed in U.S. Pat. No. 6,047,907, which is incorporated by reference herein. 
     During the preferred assembly of fuel injectors, the terminal blades  300 ,  310  are gripped by a first finger  100  and a second finger  200  on the gripping apparatus  2  and inserted into a mold cavity (not shown). The first finger  100  and the second finger  200  comprise a pair of gripper fingers  10 . The fingers  10  align the terminal blades  300 ,  310  in a predetermined location for precise assembly into the fuel injector (not shown), as will be described in more detail herein. 
     A first embodiment of the invention is shown in FIGS. 3 and 4. The gripper fingers  10  include a generally longitudinal axis  12  which extends between the fingers  100 ,  200  when the fingers  100 ,  200  are in an open position. The first finger  100  includes an upper end  102 , a lower end  104 , an outside longitudinal end  106  and an inside longitudinal end  108 . Preferably, the outside longitudinal end  106  is generally straight and parallel to the longitudinal axis  12 . The inside longitudinal end  108  includes a plurality of sawteeth formed by adjacent sides as now described. 
     As seen in FIG. 3, a first side  110  extends obliquely downward and away from the longitudinal axis  12 . A second side  112 , adjacent to the downstream end of the first side  110 , extends downward generally parallel to the longitudinal axis  12 . As used herein, the term “downward” means toward the bottom of the referenced figure. A third side  114 , adjacent to the downstream end of the second side  112 , extends obliquely downward and toward the longitudinal axis  12 . A receiving area  115  is formed in a space partially bounded by first side  110 , second side  112 , and third side  114 . A fourth side  116 , adjacent to the downstream end of the third side  114 , extends downward generally parallel to the longitudinal axis  12 . 
     A fifth side  118  extends obliquely downward and away from the longitudinal axis  12 . A sixth side  120 , adjacent to the downstream end of the fifth side  118 , extends downward generally parallel to the longitudinal axis  12 . A seventh side  122 , adjacent to the downstream end of the sixth side  120 , extends obliquely downward and toward the longitudinal axis  12 . A receiving area  121  is formed is a space partially bounded by fifth side  118 , sixth side  120 , and seventh side  122 . An eighth side  124 , adjacent to the downstream end of the seventh side  122 , extends downward generally parallel to the longitudinal axis  12 . 
     The second finger  200  includes a like number of complementary sawteeth and sides as the first finger  100  and juxtaposed from the sawteeth and sides on the first finger  100 . A first side  210  extends obliquely downward and toward the longitudinal axis  12 . A second side  212 , adjacent to the downstream end of the first side  210 , extends downward generally parallel to the longitudinal axis  12 . A third side  214 , adjacent to the downstream end of the second side  212 , extends obliquely downward and away from the longitudinal axis  12 . A fourth side  216 , adjacent to the downstream end of the third side  214 , extends downward generally parallel to the longitudinal axis  12 . 
     A fifth side  218  extends obliquely downward and toward the longitudinal axis  12 . A sixth side  220 , adjacent to the downstream end of the fifth side  218 , extends downward generally parallel to the longitudinal axis  12 . A seventh side  222 , adjacent to the downstream end of the sixth side  220 , extends obliquely downward and away from the longitudinal axis  12 . An eighth side  224 , adjacent to the downstream end of the seventh side  222 , extends downward generally parallel to the longitudinal axis  12 . 
     Those skilled in the art will recognize that the above-described pattern of sawteeth can continue either below the eighth sides  124 ,  224  of the first and second fingers  100 ,  200 , respectively or above the first sides  110 ,  210 , of the first and second fingers  100 ,  200 , respectively, and as many receiving areas as desired can be formed in the sawteeth. Additionally, the plurality of sides  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124 ,  210 ,  212 ,  214 ,  216 ,  218 ,  220 ,  222 ,  224  are preferably flat, although those skilled in the art will recognize that the sides  110 ,  112 ,  114 ,  116 ,  118 ,  120 ,  122 ,  124 ,  210 ,  212 ,  214 ,  216 ,  218 ,  220 ,  222 ,  224  can be other shapes as well. 
     The oblique alignment of the first, third, fifth, and seventh sides  110 ,  114 ,  118 ,  122 ,  210 ,  214 ,  218 ,  222 , of the first and second fingers  100 ,  200 , respectfully, provides a lead-in angle for misaligned terminal blades to be guided into a predetermined position as the fingers  100 ,  200  close together, as described below. 
     Initially, the fingers  100 ,  200  are separated and distal from the longitudinal axis  12 , as shown in FIG.  3 . During operation, either the first finger  100  can move to the right as shown in FIG. 3, the second finger  200  can move to the left, or both the first and second fingers  100 ,  200  can move toward each other in order to grip the terminal blades  300 ,  310 . 
     An object to be gripped, such as a terminal blade  300  or a terminal blade  310 , are generally located between the first and second fingers  100 ,  200 . Although it is preferred that the terminal blades  300 ,  310  are initially properly aligned in predetermined positions, either or both of the first and second terminal blades  300 ,  310  may be at least slightly misaligned from the predetermined positions. 
     An optimal location of the terminal blade is at the intersection of a horizontal axis H and a vertical axis V prior to gripping by the finger pair  10 . As seen in FIG. 3, the terminal blade  300  is displaced from the horizontal axis H by a distance D 1 , and from the vertical axis V by a distance D 2 . The distances D 1 , D 2  represent displacements from the optimal location for the terminal blade  300  to be gripped by the pair of fingers  10 . As the fingers  100 ,  200  move toward each other, the terminal blade  300  first engages the first finger  100 , due to the horizontal distance D 2  that the terminal blade  300  is offset from the optimal location. A top left corner of the terminal blade  300  engages the first side  110  due to the vertical distance D 1  that the terminal blade  300  is offset from the optimal location. As the first finger  100  continues to move toward the right, the oblique angle of the first side  110  forces the terminal blade  300  to slide downward toward the receiving area  115 , translating the terminal blade  300  along both an “X” axis and a “Y” axis which define the plane of the paper of FIG.  3 . Also, by this time, the second side  212  of the second finger  200  has engaged the right side  304  of the terminal blade  300 , assisting in forcing the terminal blade  300  downward toward the receiving area  115 . 
     When the terminal blade  300  reaches the receiving area  115 , the terminal blade  300  is stopped by the second side  112  of the first finger  100  and the left side  302  of the terminal blade  300  aligns itself between the second side  112 ,  212  of the first and second fingers  100 ,  200 , respectively, and between the first and third sides  110 ,  114 . The final location of the terminal blade  300  with respect to the first finger  100  is shown in dashed lines in FIG.  3 . The terminal blade  300  is now gripped by the finger pair  10 , and is in the optimal location for inserting the terminal blade  300  into the mold (not shown), as seen in FIG.  4 . As can be seen in FIG. 4, a space exists between the first and second fingers  100 ,  200  which corresponds to the width of the terminal blade  300 . 
     Also, as seen in FIG. 3, the terminal blade  310  is axially rotated about an axis “Z” which extends from the plane of the paper. The terminal blade  310  is rotated an angle “R” from an optimal orientation. As the first and second fingers  100 ,  200  come together to grip the terminal blade  310 , the top left corner of the terminal blade  310  is engaged by the fifth side  118  of the first finger  100  and the bottom right corner of the terminal blade  310  is engaged by the fifth side  218  of the second finger  200  due to the rotation of the terminal blade  310  with respect to the optimal orientation. As the two fingers  100 ,  200  come together, the fingers  100 ,  200  rotate the terminal blade  310  about the Z axis clockwise from the orientation shown in FIG.  3 . 
     Any vertical or horizontal misalignment of the terminal blade  310  from the optimal location is corrected by the fingers  100 ,  200 , as described above with regard to the alignment of the terminal blade  300 . The final location of the terminal blade  310  with respect to the first finger  100  is in the receiving area  121  as shown in dashed lines in FIG.  3 . Those skilled in the art will recognize that the alignment of the terminal blade  310  can be performed simultaneously with the alignment of the terminal blade  300 . 
     As shown in FIG. 4, once the fingers  100 ,  200  grip the terminal blades  300 ,  310 , the terminal blades  300 ,  310  are located in a precisely aligned location with respect to the fingers  100 ,  200  and with each other, allowing for proper precision assembly into the mold cavity. After the terminal blades  300 ,  310  are moved by the fingers  100 ,  200  to a desired location, such as the mold cavity, the fingers  100 ,  200  separate, releasing the terminal blades  300 ,  310 , and repeating the process for the next terminal blades  300 ,  310 . 
     A second embodiment  20  of the preferred invention is shown in FIGS. 5 and 6. The second embodiment  20  is similar to the first embodiment  10  with the exception of recessed pockets  126  located between faces  110 ,  114  and  118 ,  122 . The recessed pockets  126  allow the first and second fingers  100 ,  200  to mate, with complementary sides  110 / 210 ,  114 / 214 ,  116 / 216 ,  118 / 218 ,  122 / 222 , and  124 / 224  of the first and second fingers  100 ,  200 , respectively, as shown in FIG.  6 . The second embodiment also provides a more precise alignment and allowing free movement of the terminal blades  300 ,  310  within each respective recessed pocket  126 . Operation of the second embodiment  20  is the same as the operation of the first embodiment  10  as described above, but with each terminal blade  300 ,  310  being located in a respective recessed pocket  126  once the fingers  100 ,  200  have come together. 
     A third embodiment  30  of the present invention is shown in FIGS. 7 and 8. The third embodiment  30  is similar to the second embodiment with the exception that the side  128 ,  130  on a first finger  500  is curved. The curved sides  128 ,  130  form curved or rounded recessed pockets  129 ,  131  which conform to the contours of terminal blades  700 ,  710 , which have generally circular cross-sectional areas. The second finger  600  has corresponding flat sides  228 ,  230  which force the terminal blades  700 ,  710 , respectively, into the pockets  129 ,  131  during gripping. 
     Operation of the third embodiment  30  is similar to the operation of the second embodiment  20 , with the terminal blades  700 ,  710  being grasped within the recessed pockets  129 ,  131  of the fingers  500 ,  600 . 
     Those skilled in the art will recognize that blades with cross-sectional geometries other than rectangular or circular can be used, so long as the receiving areas or pockets are configured with the same geometry as the cross-section of the terminal blade being used. If a terminal blade with a different cross-section is desired, the first and second fingers  100 ,  200  are simply removed from the apparatus  2  and other fingers with matching geometries, such as the fingers of the third embodiment, shown in FIGS. 7 and 8, are installed in the apparatus  2 . 
     The preferred embodiments of the present invention, as disclosed above, are used to realize faster processing times, eliminate steps in the manufacturing process, and improve the overall quality of the terminal blade  300 ,  310  loading process. Additionally, the terminal blades  300 ,  310  can be held by the fingers  100 ,  200  with a high force, enabling the apparatus  2  to move at high speeds and allowing stable loading of the terminal blades  300 ,  310  into the mold cavity. Additionally, the present invention allows for more tolerance in material handling equipment such as transport systems, feeding systems, and workpiece carriers, as, any errors will be corrected when the fingers  100 ,  200  grip the terminal blades  300 ,  310 . 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined in the appended claims.