Abstract:
A die apparatus for assembling a part carried by a part strip onto a carrier strip is disclosed. The die apparatus includes a die housing defining an assembly station, with a portion of the die housing including a punch generally aligned with the assembly station. A part strip conveyor is provided and is adapted to convey the part strip to a position adjacent the assembly station, while a carrier strip conveyor is also provided and is adapted to convey the carrier strip to a position aligned with the assembly station. Accordingly, upon operation of the punch a part is separated from the part strip and inserted into a part receiving aperture of the carrier strip during a single punch stroke.

Description:
STATEMENT REGARDING RELATED APPLICATIONS 
     This application is a Divisional of application Ser. No. 08/692,009, filed Aug. 2, 1996, now U.S. Pat. No. 5,938,038. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the supply of parts, and more particularly to a carrier strip for carrying parts and an apparatus for assembling parts therein. 
     BACKGROUND ART 
     Many machines for trimming workpieces from a supply of workpieces are known. These machines include conventional punch presses in which a reciprocating cutting punch or die sequentially contacts a supply feedstock to separate a workpiece therefrom. Other machines may include trimming machines which trim an individual part or workpiece from a connecting member interconnecting a plurality of such workpieces, such as a strip or other carrier item. In these machines, the supply feedstock may consist of a coil of sheet metal in which individual workpieces have been previously stamped and formed. Yet other machines, such as that described in U.S. Pat. No. 3,512,438, utilize a strip of feedstock which is fed into the punch press and acted upon thereby to form the feedstock into a predetermined configuration along the entire length thereof. Individual workpieces are subsequently trimmed from the feedstock as a further finishing step. 
     In the manufacture of a variety of electronic and other components, robotic loaders or other automated assembly devices are used more frequently to achieve better production line efficiencies. Such automated assembly devices pick up individual parts or workpieces from a predesignated location and insert the part into a portion of the component. Such automated assembly devices are commonly used in the construction of electronic circuit boards. These automated devices may include, for example, an arm which moves along a designated path to a predesignated location where the arm picks up an individual workpiece and inserts it in place onto a production line component, such as a circuit board, where it is subsequently soldered or otherwise attached thereto by another automated device. In order to maintain production line efficiencies, the robotic devices must have individual workpieces consistently presented to them in a predesignated orientation and at a predesignated location. Deviation from either the predesignated orientation or location may result in the automated device not engaging the workpiece and inserting it into the production line component. 
     Many of the workpieces or parts used in such automated production lines are delicate in nature because they are stamped and formed from thin sheet metal prior to being presented to an automated assembly device. The stamping and forming of the workpiece typically occurs away from the automated production line. Robotic assemblers utilize “carrier strips,” “carrier tapes” or trays to feed parts thereto. One such type of carrier tape is known as “debossed tape and reel” and consists of a plastic carrier tape with a plurality of recessed pockets or openings formed therein along the longitudinal extent of the tape. A part is placed in each of the pockets and a plastic sealing tape or bonding tape is adhesively applied to the carrier tape, thereby sealing the parts in respective pockets. The carrier tape is fed into a robotic assembler and the seal tape is peeled away and the part removed and installed. Both the seal tape and the carrier tape are then discharged to waste by the robot. Examples of such constructions are described in U.S. Pat. Nos. 4,712,675 and 4,781,953. However, human insertion of the parts into the pockets is often required and the two-part nature of the debossed tape is expensive. Additionally, a specific orientation of the parts in the pocket must also be maintained for pick-up by the robot loader. 
     Another type of carrier type is known by the tradename of “GPAX” and is described in U.S. Pat. Nos. 4,583,641 and 4,757,895. In a GPAX-type structure, a carrier tape is provided with a plurality of holes and intervening slots punched into it along the longitudinal extent thereof. The holes are adapted to engage legs or stubs of each electrical part to insure proper and secure positioning of the part on the tape. A plastic bonding tape overlays the carrier tape and parts and is pressed or stitched into the carrier tape between adjacent parts. This bonding tape offers protection to the parts and retains the parts in place on the carrier tape. This type of carrier tape construction shares certain disadvantages with the debossed tape and reel construction previously described. For example, the assembled tapes are composed of multiple pieces and thus increases the amount of waste generated by the process. 
     Ziberna U.S. Pat. No. 5,483,857 discloses a work piece finishing and presentation machine including means for mounting a supply of interconnected work pieces in the form of a continuous belt, means for engaging and feeding the continuous belt, means for trimming individual work pieces from the belt and means for receiving an individual work piece and for presenting same to a robotic loader or assembler. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a parts carrier comprises a flexible member which can be flattened into a planar strip and having a plurality of part-receiving apertures extending fully therethrough. Each aperture is defined by walls including a tab portion which is resiliently deflectable from an undeflected position while the flexible member is flattened to permit placement of a preformed part in a part-receiving aperture, and which thereafter returns to substantially the undeflected position to releasably engage a recess in the part. Preferably, the tab portions are coplanar and the walls defining each aperture may include four portions wherein each wall portion may include two tab portions. Still further in accordance with the preferred embodiment, each aperture may be rectangular. 
     Also, the flexible member may include a series of positioning holes. In accordance with a specific embodiment, first and second series of marginal positioning holes are disposed on first and second sides, respectively, of the apertures. In addition, each series of marginal positioning holes may include a first set of spaced holes each of a first size and a second set of spaced holes interspersed between the first set of spaced holes and each of a second size smaller than the first size. Also, the apertures and the positioning holes may be regularly spaced. In accordance with a further aspect of the present invention, a combination includes a flexible planar strip having a plurality of part-receiving apertures extending fully through the strip wherein each aperture is defined by walls including tab portions which are deflectable when the strip is flattened to releasably engage a recess in a part. The strip further includes a series of positioning holes adjacent the apertures. A plurality of parts are disposed in the plurality of apertures wherein each part has a recess which receives one of the tab portions. 
     In accordance with yet another aspect of the present invention, apparatus for assembling a part carried by a parts strip into a carrier strip includes first means for conveying the parts strip along a first path to deliver the part to an assembly station and second means for conveying the carrier strip along a second path transverse to the first path to position a part-receiving aperture in the carrier strip at the assembly station. A punch is operative when the part is aligned with the part-receiving aperture at the assembly station for separating the part from the parts strip and placing the part into the part-receiving aperture during a single punch stroke. 
     These and other features of the present invention will become apparent from a reading of the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the course of the following detailed description, reference will be made to the attached drawings wherein like reference numerals identify like parts and wherein: 
     FIG. 1 is a fragmentary, isometric and diagrammatic view of a die for assembling a part into a carrier strip according to the present invention; 
     FIG. 2 comprises a plan view of a lower portion of an assembly station of the die of FIG. 1; 
     FIG. 3 is a sectional view taken generally along the lines  3 — 3  of FIG. 2 when the die is fully open; 
     FIG. 4 is a view similar to FIG. 3 with the die fully closed; 
     FIG. 5 is a partial sectional view taken generally along the lines  5 — 5  of. FIG. 2 when the die is fully closed; and 
     FIG. 6 is a bottom elevational view of the top of the assembly station of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a die  10  forms parts in a metal strip  12  and assembles the parts into a parts carrier strip  14  fabricated of plastic or other suitable flexible material. The metal strip  12  is fed in the direction of an arrow  16  into a space between lower and intermediate die portions  18 ,  20 , respectively. The die  10  further includes an upper portion  22  which is slidably connected to the intermediate die portion  20 . The die portions,  18 ,  20  and  22  are interconnected by guides (not shown) which allow reciprocating movement of the intermediate die portion  20  and the upper die portion  22  relative to the lower die portion  18 . 
     Preferably, the carrier strip is fabricated of polypropylene or any other suitable plastic or other material and is two inches wide and 0.020 inches thick. The carrier strip  14  may be fed by any suitable means, and, in the preferred embodiment is fed into the die by an air-operated feeding device  24  which may comprise, for example, a model B4 feeder manufactured by Rapid Air Corporation of Rockford, Ill. 
     As seen in FIG. 2, the carrier strip  14  is generally planar and includes a plurality of part-receiving apertures  26 . Preferably, although not necessarily, each aperture  26  is generally rectangular and, more particularly, is generally square. In the illustrated embodiment, each aperture  26  includes four wall portions  28   a - 28   d  and each wall portion  28   a    28   d  includes two planar tab portions  30  which are spaced from one another near outer ends of the wall portions  28   a - 28   d . If necessary or desirable, the number and/or placement of tab portions  30  may be varied in dependence upon the size and shape of the part to be carried in the aperture  26 . 
     Each tab portion  30  is resiliently deflectable from an undeflected position while the carrier strip  14  is flattened. 
     First and second series of marginal positioning holes  32 ,  34  are located on either side of the apertures  26  inside of guide edges of the strip  14 . Preferably, the holes of each series  32 ,  34  are regularly spaced. Also preferably, each series of holes  32 ,  34 , for example, the series  32 , includes a first set of spaced holes  36  each of a first size and a second set of spaced holes  38  interspersed between the first set of spaced holes  36  wherein each hole of the second set is of a second size smaller than the first size. Each hole of the second set of holes  38  is precisely located with respect to the apertures  26  to permit accurate placement of the carrier strip  14  during insertion of a part therein. The second set of holes  36  are larger to permit pickoff apparatus (not shown) to accurately position each part during a subsequent assembly process. If a different methodology is to be used to accurately position the parts carried by the strip during the subsequent assembly process, then the use of differently sized holes  36  and  38  may be dispensed with. 
     Referring again to FIG. 1, the die  10  includes a series of forming stations (not shown) which sequentially stamp the metal strip  12  into parts  40 , three of which  40 - 1 .  40 - 2  and  40 - 3  are shown in FIG.  2 . The parts  40 - 1  and  40 - 2  are connected to the balance of the strip  12  by arms  42  which remain after punching of the metal strip  12 . As seen in FIG. 3, each part, for example the part  40 - 2 , includes four downwardly depending walls  44 , each of which includes a pair of recesses in the form of holes  46 . The spacing between the holes  46  is equal to the spacing between the tabs  30  of the wall portions  28   a - 28   d  defining the apertures  26 . The metal strip  12  may further include positioning holes  48 , if desired. 
     FIGS. 2 and 6 illustrate an assembly station  50  at which the metal strip  12  and the carrier strip  14  are fed along paths that extend transversely, and preferably perpendicularly, to each other. More particularly, with reference to FIGS. 2 and 3, the metal strip  12  is fed by a feeder (not shown) and is guided along a path by spring-loaded stock lifter guides  52  each of which, as seen in FIG. 3, includes a channel  54  therein. During operation of the die  10 , the metal strip  12  is moved to a position such that a part  40 , for example the part  40 - 2 , is moved to the position showing in FIG.  2 . Accurate placement of the part  40 - 2  at such location is assured by the placement of guides (not shown) into holes  48  upstream of the locations shown in FIG.  2 . The plastic carrier strip  40  is similarly moved by the feeding device  24  such that an aperture  26  is placed in the position shown in FIG.  2 . Accurate positioning of the carrier strip  14  is assured by pilots  56  which, as noted in greater detail below, lower into certain ones of the marginal positioning holes  32  and  34 . 
     FIG. 3 illustrates the various parts of the die  10 , the metal strip  12  and the carrier strip  14  during the time that the die  10  is open. As seen in FIG. 3, the upper die portion  22  includes a die set top  58  and a punch holder  60  which is screwed and dowelled to the die set top  58 . A punch  62  preferably having a cross-sectional shape and size substantially the same as each part  40  is carried by the punch holder  60 . 
     The intermediate die portion  20  includes a stripper  64  which carries a face plate  66 . The face place  66  is made of a relatively hard material to resist wear and is secured to the stripper  64  by any convenient means, such as by screws and dowels. With reference to FIGS. 5 and 6, four sub-liner pins  68  extend through the punch holder  60  and include ends which are press fitted into bores in the stripper  64 . The sub-liner pins further include enlarged heads  72  which are disposed within recesses  74 . A pair of springs  76  are disposed in spring recesses  78  and are placed in compression between threaded plugs  80  and the stripper  64 . 
     Once the metal strip  12  is moved to the position shown in FIG. 2, the part  40 - 2  is in alignment with a recess  82  formed in a die block  84  of the lower die portion  18 . The recess  82  has a shape and size which is slightly larger than the outline of each part  40 . Four guides or locators  86  are mounted by bolts  88  in side recesses  90  adjacent the recess  82 . Leading edges  92  of the locators  86  are shaped complementary to outer edges of each part  40  (in the illustrated example the surfaces  92  are planar) and the positions of the leading edges  92  are adjusted so that an opening is formed which is substantially the same size as the outer dimensions of the part  40 . 
     Once the metal strip  12  and the carrier strip  14  are precisely located at the positions shown in FIG. 2, the upper die portion  22  is lowered. Initially, the die set top, the punch holder  60  and punch  62  as well as the stripper  64  and the face plate  66  move downwardly together as a unit. Eventually, the face plate  66  contacts the stock lifter  52  and forces the guides  52  downwardly against the biasing of the spring loading thereof. Thus, the metal strip  12  is also moved downwardly, thereby causing the part  40 - 2  to enter the recess  82 . Just prior to or during such time, a piston and cylinder unit  94  is actuated to extend a support rod  96  (also seen in FIG. 4) into a position to support the carrier strip  14  during insertion of the part  40 - 2 . Still further, downward movement of the stripper  64  causes the pilots  56  to similarly move downward into marginal holes of the carrier strip  14 , thus assuring the aperture  26  is precisely aligned with the recess  82 . 
     Thereafter, continued downward movement of the upper die portion  22  causes the punch  62  to punch out the part  40 - 2  from the arms  42 , thereby separating the part  40 - 2  from the metal strip  12 . The part  40 - 2  then moves downwardly through the recess  82 , during which time the part  40 - 2  is guided by the guides  86  and is inserted into the aperture  26  whereupon the tabs  30  deflect to permit such insertion. Once the holes  46  align with the tabs  30 , the tabs  30  return to their original position owing to the resiliency of the plastic used to fabricate the carrier strip  14 , thereby inserting such tabs into the holes  46  and thus retaining the part  40 - 2  in the aperture  26 . At this point, the various components are in the position shown in FIGS. 4 and 5. 
     Following the foregoing sequence of steps, the upper die portion  22  is raised, thereby withdrawing the punch  62  from the recess  82 . Eventually, as seen in FIG. 5, the heads  72  of the sub-liner pins  68  contact lower walls  98  of the recesses  74 . Continued upper movement of the upper die portion  22  thereafter causes the stripper  64  and the face plate  66  to be moved upwardly as well away from the carrier strip  14 . Also during this lifting movement, the piston and cylinder unit  94  is operated to withdraw the support rod  96  from the space between the parts  40 - 2  and  40 - 3 . Eventually, the components assume the position shown in FIG. 3 whereupon the strips  12  and  14  can be again moved and the foregoing sequence of steps can be repeated to insert the part  40 - 1  in the next aperture  26  in the carrier strip  14 . 
     As should be evident from the foregoing, the carrier strip  14  will eventually be loaded with parts  40  in the apertures  26 . Thereafter, the carrier strip  14  can be rolled up onto reels and delivered to another location whereupon the parts  40  can be removed from the apertures  26 . During transport, the parts are securely held in the apertures  26  by the tabs  30 . Further, the parts are consistently presented in proper orientation to the assembly apparatus. Thereafter, if desired, the carrier strip can be reused, i.e., loaded with additional parts  40  and again delivered to the assembly location. This reusability is a highly important feature of the present invention and can significantly reduce manufacturing costs. This feature results from the ability of the tabs  30  to deflect and return to their original shape without permanent deformation. 
     In addition to the foregoing, no secondary labor is required to load parts onto the carrier strip or otherwise perform a finishing operation thereon. Labor costs are low and packaging costs are held to a minimum since no adhesive, cover strips, etc. . . . are used. 
     As noted above, dimensions of the strips  12  and/or  14  and the tape need not be fabricated of plastic, but instead could be made of any material which is sufficiently resilient to allow the tabs  30  to deflect when a part is inserted into the apertures  26  and so that the tabs subsequently return to an undeflected position and enter a recess in the part  40 . 
     Also as noted above, the dimensions of the strips  12  and/or  14  and the sizes and shapes of the apertures and parts can be varied as needed and still obtain the unique benefits afforded by the present invention. For example, the parts may be circular in cross-section, in which case the apertures  26  may be similarly circularly shaped and include at least one wall portion having at least one tab which is deflectable to engage a recess in the part. Any other cross-sectional part and aperture configuration could alternatively be used, even part and aperture sizes and/or configurations that do not match one another. 
     Still further, the marginal holes  36 ,  38  and  48  need not be utilized if some other positioning methodology can be used. 
     Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.