Abstract:
A releasable adaptor is carried on the end of the pick-and-place vacuum nozzle which diffuses and restricts the air flow access of the nozzle to the top surface of an apertured fastener such as a nut while covering the fastener hole. The adaptor allows a standard nozzle to develop sufficient suction to lift the nut/adaptor combination and transport it to its desired target location such as a circuit board. There, the nut is released from the adaptor, which is then lifted by the nozzle and transported back to the supply location. This functionality is achieved by a unique adaptor air valve which the PNP equipment operates both mechanically and through its controlled application of negative air pressure applied to the adaptor by the nozzle.

Description:
RELATED APPLICATIONS 
       [0001]    This is a non-provisional patent application related to provisional application No. 62/094,243 entitled “Pick and Place Nozzle Adaptor” filed on Dec. 19, 2014, priority from which is hereby claimed. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to automated pick-and-place manufacturing assembly machines, which take individual parts from a supply location and place them into a designated position with other components of a greater assembly. More specifically, it relates to pick-and-place robotics used in the electronics industry for placing components onto a circuit board. 
       BACKGROUND OF THE INVENTION 
       [0003]    Pick-and-place machines (hereinafter “PNP”) for positioning components onto a circuit board have been used for many years. In one such system, a robotic transport arm has a vacuum line and a nozzle at the end that lifts components from a supply station and delivers them to a specific location on a circuit board. To achieve this step, the individual component must have a top surface that will form a vacuum seal with the nozzle tip. Components that have through holes (“apertured components”), such as internally threaded fasteners, present a problem since the hole in their top surface is not conducive to drawing a vacuum by a standard nozzle tip. Nozzle tips cannot be custom designed for each different part because many differently-shaped components must be delivered by the same nozzle to the same circuit board in sequence. 
         [0004]    To solve this problem, it is known to add a piece of adhesive tape to the top of the apertured component to seal off the hole. The tape creates a uniform planar surface with which the nozzle tip can sufficiently vacuum seal so that component can be lifted. However, this solution is not ideal since it requires an additional sacrificial element be applied to the apertured component and then later removed. Applying tape adds cost, slows production rates and creates used tape scrap. It is therefore desirable to provide the electronics industry an automated assembly means that can efficiently handle apertured components using standard PNP equipment. 
       SUMMARY OF THE INVENTION 
       [0005]    In one preferred embodiment, an adaptor is provided that can be used with apertured components, which avoids the need to first temporarily seal the aperture in the component. The adaptor is releasable and travels on the end of the PNP nozzle. The adaptor diffuses and restricts the air flow access of the nozzle to the top surface of the apertured component, such as a nut, while covering the central aperture. The adaptor enables a standard nozzle to develop sufficient suction to lift the nut/adaptor combination and transport it to its desired location such as a hole in a circuit board. At the target location, the component is released from the adaptor, which is then lifted by the nozzle and transported back to the supply location. The nozzle adaptor achieves this functionality using a unique air valve, which the PNP operates both mechanically and through its controlled application of air pressure applied to the adaptor by the PNP nozzle. 
         [0006]    In one preferred embodiment, the PNP nozzle adaptor has a body with a top, a bottom, and a central axial bore. The body has a manifold cavity, which is open at the bottom and has a larger diameter than the bore that accepts the apertured component. A plunger is closely fitted within an internal shoulder in the bore, which has a reduced diameter. The plunger reciprocates between upwardly retracted and downwardly extended positions. An O-ring at the bottom of the plunger captivates the plunger within the body and limits its upward movement. An enlarged head at the top of the plunger limits its downward movement. A recoil spring is positioned and operative between the underside of the plunger head and the shoulder in the body to normally bias the plunger in the retracted position. The plunger has a vacuum chamber that is open at the top of the plunger. An extension on the bottom end of the plunger is adapted to cover the hole in the nut when the plunger is extended downward. At least one air intake port extends from the vacuum chamber laterally (radially) through the sidewall of the plunger near its bottom end. The shoulder covers the ports when the plunger is upwardly retracted. When the plunger is downwardly extended, the ports lie beyond the shoulder and are open to the manifold cavity. In this construction, the plunger acts as a slide valve which opens and closes the intake ports. Thus, the plunger can function both as a slide valve and a cover for the hole in the apertured component. 
         [0007]    The spring-biased plunger is moved by the mechanical action of the nozzle against it. When the plunger is pushed downwardly to the extended position, the intake ports are open to the manifold cavity so that air can flow between the cavity and the chamber. In this position, the bottom of the plunger contacts the nut and seals off the hole. An annular step around the top of a recess at the bottom of the body also contacts and seals against the top surface of the apertured component. This construction enables a vacuum connection between the adaptor and the apertured component. When it is desired to release the component, the vacuum is stopped and the plunger is biased to the retracted position by the recoil spring as the nozzle is lifted a distance equal to the stroke of the plunger. In the retracted position, the intake ports are closed by the inner wall of the shoulder in the adaptor body. In this position, the vacuum chamber is only open to the PNP vacuum nozzle through the opening at the top of the plunger. In this position, suction can be re-applied to the adaptor, which can then be carried away by the nozzle with the apertured component left behind. 
         [0008]    The operation of one embodiment of the invention may be more specifically described as follows. At a supply location, with an adaptor already placed on a nut, the PNP nozzle pushes the plunger downwardly against the biasing force of the recoil spring. This movement continues until the plunger contacts and covers the upper surface of the apertured component. The plunger valve connects ambient air in fluid communication with the top surface of the apertured component. Suction is then applied and the component is thereby forcefully captured in the lower cavity of the adaptor body. The component is then transported with the adaptor by the PNP to the desired circuit board location. The nut is then released from the adaptor by stopping nozzle suction. Then, the nozzle is moved upward, which allows the recoil spring to bias the plunger upward to the retracted position to close the valve between the vacuum source and the apertured component. With the valve closed, a vacuum is again drawn on the adaptor which is then lifted away from the component and back to the supply location where it is placed on the next component in the supply reel. The next component can then be taken or the adaptor can be released from the nozzle by terminating the suction. The nozzle can then move away from the supply reel to transport any other part to the circuit board. 
         [0009]    The advantages of the nozzle adaptor of the present invention are provided by a simple, self-actuating device. The adaptors spring-actuated mechanism does not rely upon any motive force other than the mechanical force of the PNP nozzle and the negative air pressure it applies. Other advantages and differences will follow from the foregoing explanation and the following drawings and description of the invention. The preferred embodiment of the invention will provide one of skill in the art with a full understanding of what has been invented. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a top, front perspective of an adaptor in accordance with a preferred embodiment of the invention; 
           [0011]      FIGS. 2A and 2B  are side-by-side cross-sections showing the adaptor in the retracted and extended positions, respectively; 
           [0012]      FIGS. 3A and 3B  are sectional views of the nozzle adaptor interacting with a reel-supplied, apertured component before and after it is connected to vacuum pressure; 
           [0013]      FIG. 3C  is an enlarged fragmentary cross section; 
           [0014]      FIGS. 4A and 4B  are sectional views of the nozzle adaptor transporting and inserting an apertured component on a circuit board; and, 
           [0015]      FIGS. 5A and 5B  are sectional views of the nozzle adaptor releasing an apertured component on a circuit board and returning to a supply reel of additional apertured components. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    A nozzle adaptor in accordance with a preferred embodiment is illustrated in  FIGS. 1-5  and is designated generally by reference numeral  10 . The nozzle adaptor  10  generally comprises a main body/housing  11 , a plunger  13  and a recoil spring  15 . With reference to the orientation shown in  FIGS. 1 and 2 , the plunger  13  reciprocates upwardly and downwardly within the housing. The recoil spring  15  normally urges the plunger  13  to the retracted position shown in  FIG. 2A . The plunger  13  is shown in its extended position in  FIG. 2B . It should be understood that although the main elements of this preferred embodiment are cylindrical, other shapes and sizes may be utilized. 
         [0017]    In  FIG. 2A , the plunger is held retracted by the spring  15  and the air intake ports are closed by the shoulder  11   d.  In  FIG. 2B , the plunger  13  is in the extended position and the intake ports  20  are open to the manifold cavity  23  (described below). Thus motion of the plunger between up and down positions acts as a slide valve which opens and closes the intake ports  20 . 
         [0018]    The body  11  of the adaptor  10  has a generally-cylindrical shape with an upper portion  11   a  and an enlarged-diameter lower portion  11   b.  The upper  11   a  and lower  11   b  portions transition at an external shoulder  11   c  and a first internal shoulder  11   d.  The inner walls of the body  11  define an internal, axial-extending central bore  22  extending entirely through the body  11 . The central bore  22  has an upper portion  22   a,  a central portion  22   b  and a lower portion  22   c  defined by the interior walls of the upper portion  11   a,  first internal shoulder  11   d,  and lower portion  11   b  of the body  11 , respectively. The lower portion  22   c  acts as a manifold cavity and has an enlarged recess  28  formed at the axial end of the lower portion  11   b  of the body. The enlarged recess  28  is co-axial with the central bore and forms a second internal shoulder  11   e , which engages the top of the apertured component with which the nozzle is designed to be used. Preferably, the shape of the recess matches the shape of the apertured component so that the nozzle is centered on the apertured component. In one preferred embodiment, the recess  28  has a cylindrical shape that compliments the shape of the outer surface of a nut. 
         [0019]    The plunger  13  has a generally-cylindrical shape with an enlarged head  14   a  at one end, side walls  14   b,  and an end wall  14   c.  A central, axial vacuum chamber  17  extends from the head  14  to the end wall  14   c.  A plurality of radially-extending ports  20  are located proximate the end wall  14   c  and extend through the side walls  14   b.  In the preferred embodiment shown in  FIGS. 1-5 , the ports  20  are equally spaced at 90-degree intervals around the perimeter of the plunger  13 . An annular race  34  is formed in the outer surface of the side walls  14   b  proximate the end wall  14   c.  An O-ring  21  is seated in the race  34 . 
         [0020]    The spring  15  is captivated between the head  14   a  and the first internal shoulder  11   d.  The plunger  13  is captivated to the body  11  by the enlarged head  14   a  at the top and the O-ring seal  21  near the bottom, which abuts the bottom of the first internal shoulder  11   d.  The outer diameter of the side walls  14   b  is slightly smaller than but closely approximates the inner diameter of body  11  at the inner shoulder  11   d.  This close-fitting arrangement controls alignment of the plunger  13  within the body  11  as it reciprocates to open or close the ports  20 . Referring to  FIG. 2A , the ports  20  align with and are occluded by the central portion  11   b  of the side walls  14   b.  Referring to  FIG. 2B , as the plunger  13  moves to the extended position wherein the ports  20  move into axial alignment with the lower portion  11   c  of the side walls  11 . However, since the diameter of the sidewalls at this axial location is greater than the diameter of the plunger  13 , the ports are un-occluded and create a fluid passageway from the manifold cavity  22   c  into the central vacuum chamber  17 . 
         [0021]      FIGS. 3 a -3 d    show the interaction between the nozzle adapter  10  and an apertured component  24  on a reel strip  25  of components  24 . Referring now to  FIG. 3A , an apertured component  24  such as a nut  24  is delivered to a home position by an advancing reel strip  25  that holds a row of similar components. The PNP provides motion and vacuum control to a standard lifting nozzle  30 , such as shown in  FIG. 3B , to remove an apertured component  24  from the reel strip  25  and insert it in the hole  33  of a circuit board, such as shown in  FIG. 3B . 
         [0022]    The adaptor  10  is initially positioned on the first nut  24  on the reel  25 . In this first step, the plunger  13  is arranged in the retracted position as shown in greater detail in  FIG. 2A . Next, the PNP depresses the plunger  13  to the extended position shown in  FIGS. 2B, 3B and 3C  by pushing on the head  14   a  against the resistive force of the recoil spring  15 . Downward movement of the nozzle  30  is stopped when the apertured component  24  contacts the second internal shoulder  11   e  and the end wall  14   c  as seen in  FIGS. 3B and 3C . In this position, the top of the apertured component  24  around the hole is covered by the end of the plunger  13 . The manifold cavity  22   c  is also sealed off by engagement of top surface of the component nut  24  with the second internal shoulder  11   e . Vacuum pressure is then applied to the vacuum chamber, which also creates an effective vacuum in the manifold cavity  22   c  since the cavity  22   c  is connected in fluid communication with the vacuum chamber  17  through the ports  20  as shown by fluid flow lines in  FIG. 2B . The vacuum creates a releasable attachment between the component  24  and the adaptor  10 . The vacuum is sufficient to overcome the force of the recoil spring  15  and the weight of the component/adaptor combination so that the component and adaptor can now be lifted by the PNP. 
         [0023]    After the component  24  is removed from the reel strip  25 , it is carried, as seen in  FIG. 4A , and positioned in the receiving hole  33  of the circuit board  31 , as seen in  FIG. 4B . After the component  24  is placed on the circuit board  31 , the vacuum is halted and the PNP lifts the nozzle  30  a small amount, which allows the plunger  13  to return to the retracted position shown in  FIGS. 5 a    and  2 A. In the retracted position, the air intake ports  20  are closed and the vacuum applied to the nut is relieved by air flow through the unsealed hole in the apertured component  24 . Finally, the vacuum is re-applied to the vacuum chamber  17  so that the adaptor nozzle  10  can be lifted away from the component  24  and returned to the supply strip  25  as shown in  FIG. 5B . The PNP can then acquire the next component  27  on the reel  25  and repeat the installation process. 
         [0024]    In an alternative method of installing an apertured component, the nozzle adaptor  10  is left in place on the component  24  after it is placed in the receiving hole  33  on the circuit board  31 . In this embodiment, a vacuum is not re-applied to the plunger  13  after the plunger is returned to the retracted position. The PNP nozzle is then moved away from the component  24  to pick and place another type of component located elsewhere that does not require the adaptor nozzle  10 . 
         [0025]    From the foregoing, it should be appreciated that the adaptor  10  for a PNP nozzle eliminates the requirement that apertured parts have a sacrificial hole seal. The foregoing is to be considered illustrative only of the principles and possible embodiments of the invention. Further, since numerous modifications and changes will be readily apparent to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. Accordingly, suitable modifications and equivalents may be resorted to, all falling within the scope of the invention, which shall be determined only by the following claims and their legal equivalents.