Abstract:
A female latch member comprising an aperture having a central axis and an inside surface, and first and second portions extending radially from said inside surface. The first and second portions cooperate to form a channel, wherein the channel is configured to receive a pin of a male latch member and cause the female latch member to rotate relative to the male latch member, while the female latch member and the male latch member alternate between latched and unlatched configurations as the female latch member reciprocates along the central axis relative to the male latch member. The female latch member and the male latch member temporarily engage one another when latched.

Description:
TECHNICAL FIELD 
       [0001]    This application is directed, in general, to a coupling device or latch and, more specifically, to a rotating tension latch. 
       BACKGROUND 
       [0002]    Fasteners are ubiquitous. A quick trip to the hardware section of any home center will readily reveal the broad selection of fasteners. Screws, bolts, rivets, wall anchors, cotter pins, magnets, latches, etc., serve to enable one object to be fastened permanently or temporarily to another object. Seemingly, the choices are so broad that there is likely a specific fastener for every specific application. 
         [0003]    Many assembly line operations use fasteners, such as bolts or screws, to couple two separate parts together. However, in many automated assembly line operations it is desirable to grasp an assembly with a robotic arm and temporarily relocate the assembly to the next station where assembly continues. In some applications magnetic or vacuum forces are employed to grasp the assembly for transport. However, in some applications magnetic forces may be undesirable because of the nature of the assembly which may be adversely affected by magnetism. Similarly, other assemblies may be unsuitable for the use of vacuum force because of insufficient area to affect a secure grasp of the assembly, excessive weight of the workpiece, etc. Therefore, there is needed a simple and re-useable mechanical fastener that may be employed in these and other suitable applications. 
       SUMMARY 
       [0004]    One aspect provides a female latch member comprising an aperture having a central axis and an inside surface, and first and second portions extending radially from said inside surface. The first and second portions cooperate to form a channel, wherein the channel is configured to receive a pin of a male latch member and cause the female latch member to rotate relative to the male latch member while the female latch member and the male latch member alternate between latched and unlatched configurations as the female latch member reciprocates along the central axis relative to the male latch member. The female latch member and the male latch member intermittently engage one another when latched. 
         [0005]    Another aspect provides a male latch member comprising a core having a central axis and an outside surface, and first and second portions radially extending from the core that cooperate to form a channel around the core. The channel is configured to receive a pin of a female latch member and cause the male latch member to rotate relative to the female latch member. The channel is further configured to alternate between latched and unlatched configurations as the male latch member reciprocates along the central axis relative to the female latch member. The male latch member and the female latch member temporarily engage one another when latched. 
         [0006]    Another aspect provides a pick and place system comprising a first latch member having a central axis and a surface around the central axis, a second latch member, and first and second portions extending radially from the surface. The first and second portions cooperate to form a channel, wherein the channel is configured to receive a pin of the second latch member and cause the first latch member to rotate relative to the second latch member. Consequently, the first and second latch members alternate between latched and unlatched configurations as the first latch member reciprocates along the central axis relative to the second latch member. The first latch member and the second latch member intermittently engage one another when latched. 
       BRIEF DESCRIPTION 
       [0007]    Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         [0008]      FIG. 1  is an exploded isometric view of one embodiment of a rotating tension latch constructed according to the principles of the present disclosure; 
         [0009]      FIG. 2A-2M  are a series of elevation views of a periphery of a male latch member and sectional views of a corresponding female latch member in a progression from unlocked to locked in tension to unlocked. 
         [0010]      FIG. 3A  is a perspective view of one embodiment of a pick-and-place system constructed according to the principles of the present disclosure; 
         [0011]      FIG. 3B  is an elevation view of the pick-and-place device of  FIG. 3A ; and 
         [0012]      FIG. 3C  is a sectional view of the pick-and-place system of  FIG. 3A  along plane  3 C- 3 C. 
     
    
     DETAILED DESCRIPTION 
       [0013]    Referring initially to  FIG. 1 , illustrated is an exploded isometric view of one embodiment of a rotating tension latch  100  constructed according to the principles of the present disclosure. For the purposes of this discussion, the operating principles of a rotating tension latch  100  will be explained with respect to a female latch member  110  and a male latch member  120 . The female latch member  110  includes a central aperture  111  having an inner surface  111   a  and first and second pins  112 ,  113 , respectively. In the illustrated embodiment, the first and second pins  112 ,  113 , respectively, extend radially inward from the inner surface  111   a  into the central aperture  111  and are diametrically opposed. For balance, and to limit rotation between unlocked and tension locked positions, the present embodiment includes both first and second pins  112 ,  113 , respectively, spaced apart by 180° around the inner surface  111   a  of the female latch member  110 . In an alternative embodiment, the female latch member  110  may include only a single pin, for example the first pin  112 . In yet another embodiment, the female latch member  110  may include three or more pins. In such embodiments, it is advantageous that the pins be distributed evenly around the inner surface  111   a ; for example, three pins are evenly distributed with 120° between adjacent pins; four pins are evenly distributed with 90° between adjacent pins, etc. 
         [0014]    The male latch member  120 , in one embodiment, includes a core  121  having a first end  122 ; a second end  123 ; a central axis  124 ; first, second and third portions  125 - 127 , respectively; and a cone  128 . The cone  128  may be truncated as shown. The core  121 , in this embodiment, is substantially-cylindrical around the central axis  124  and comes to a blunt point or a truncated cone  128 . Such a truncated cone  128  form may also be referred to as chamfered. The first, second and third portions  125 - 127 , respectively, are solid masses contiguous to the core  121  that limit the vertical travel of the first pin  112  when the male latch member  120  is inserted into the female latch member  110 . Note that the initial angular (rotated) relationship of the female latch member  110  (and therefore also the first and second pins  112 ,  113 , respectively,) to the male latch member  120  is unimportant, as the male latch member  120  and the female latch member  110  will self-align with the aid of the chamfered/truncated cone  128 . 
         [0015]    For the purposes of this disclosure, vertical movement is defined as along the central axis  124  of the male latch member  120 . Of course, one of skill in the pertinent art will recognize that this “defined vertical” may vary from “absolute local vertical” of the location wherein the tension latch  100  is employed. 
         [0016]    In this embodiment, the first portion  125  is proximate the first end  122  and extends radially outward from the core  121 . The first portion  125  has a first irregular surface  131  proximate a midpoint  140  of the core  121 . The first irregular surface  131 , in the illustrated embodiment, is perpendicular to the central axis  124  and has an edge  129  that is sawtooth-like. The first irregular surface  131  defines a vertical limit as a bearing surface that the first pin  112  may travel along the core  121  while the male latch member  120  is inserted into the female latch member  110 . The first portion  125  is continuous around the core  121  so that the first and second pins  112 ,  113  may not pass vertically beyond the first irregular surface  131 . 
         [0017]    The second portion  126  is proximate the second end  123  and extends radially outward from the core  121 . The second portion  126  has a second irregular surface  132  proximate the midpoint  140  that, in this embodiment, is also perpendicular to the central axis  124 . The first and second irregular surfaces  131 ,  132 , respectively, form an irregular channel  133  therebetween that is configured to guide one of the first and second pins  112 ,  113 , respectively, around at least a portion of a periphery  130  of the core  121 . The channel  133  is “irregular” in that the width of the channel  133  between the first and second irregular surfaces  131 ,  132 , respectively, varies with the location around the periphery of the core  121 . The second portion  126  also has a third irregular surface  134  proximate the second end  123 . The third portion  127 , in this embodiment, is similar to, and positioned 180° around the core  121  from, the second portion  127 . The third portion  127  together with the first portion  125  forms a second channel (not visible) that is substantially identical to the first channel  133 . The second and third portions  126 ,  127 , respectively, are evenly distributed around the core  121 , and therefore the first channel  133  and the second channel are evenly distributed around the core  121 . Similarly, the first and second pins are evenly distributed around the inner surface  111   a  of the female latch member  110 . 
         [0018]    In one embodiment, the female latch member  110  may be fixed to or part of a workpiece  150  and the male latch member  120  may be rotatably coupled around the central axis  124  to a positioning arm  160 . The motion of the positioning arm  160  may be controlled by an automated machine (not shown). One of skill in the pertinent art is familiar with conventional methods to rotationally couple the male latch member  120  to the positioning arm  160  and how an automated machine may be made to place the male latch member  120  in a desired position relative to the female latch member  110 . 
         [0019]    For ease of illustration and understanding of the principles of the present device, the female latch member  110  will be considered fixedly coupled to a workpiece  150  and the male latch member  120  will be moveable vertically with respect to the female latch member  110  as well as capable of rotation with respect to the female latch member  110 . This vertical movement along the central axis  124  may be referred to as “reciprocation” as the rotating tension latch operates first in a downward motion and then an upward motion followed by a second downward motion. This combination of linear motions together with rotation of the male latch member  120  causes the tension latch  100  to move from unlatched, to a momentarily latched, to an unlatched condition. Of course, momentarily does not mean only for a very limited time, as the rotating tension latch  100  will maintain the latched condition so long as tension remains between the male and female latch members  120 ,  110 , respectively. 
         [0020]    Referring now to  FIG. 2A-2M , illustrated is a series of elevation views of the periphery of the male latch member  120  and a sectional view of the female latch member  110 . That is, the side surfaces (periphery) of the male latch member  120  show the first, second, and third portions  125 ,  126 ,  127 , respectively, flattened out to form a planar view of the outer surface of the male latch member  120 . This provides a more easily understood view showing the progress of the interaction of the first and second pins  112 ,  113 , respectively, with the contours of the male latch member  120 . In the series of elevation views,  FIG. 2A-2M , the female latch member  110  will be shown in a fixed vertical location until the tension latch  100  engages in  FIG. 2G  and the position of the male latch member  120  will be positioned vertically relative to the female latch member  110  as befits the interaction of the male and female latch members,  120 ,  110 , respectively, in  FIG. 2H . This demonstrates how the tension latch  100  may be used to move a workpiece having a female latch member embedded or applied thereto. Only the first pin  112  will be shown in subsequent FIGURES for simplicity. One of skill in the pertinent art will recognize that the second pin  113  interacts with the third portion  127  in the same manner as the first pin  112  interacts with the second portion  126 . One of skill in the pertinent art will further recognize the sawtooth-like profile of the first irregular surface  131  (having an edge  129 ) which has alternating short and long teeth  231 ,  232  respectively, as shown in  FIG. 2A . 
         [0021]    Continuing now with  FIG. 2A  with continuing reference to  FIG. 1 , an attachment  210  of the positioning arm  160  (not shown in these views) places the male latch member  120  vertically proximate the female latch member  110 . The first pin  112  is randomly positioned with respect to the workpiece  150  and the male latch member  120 , as would be the case in a manufacturing production line. In these figures, the first pin  112  is represented by its cross section as a small circle. The central axis  124  is approximately aligned with a center of the central aperture  111  ( FIG. 1 ). The male latch member  120  is aligned with, but not in contact with, the female latch member  110  at this point. The female latch member  110  is fixed with respect to the workpiece  150  in this example. A vertical downward force F M  is applied to the male latch member  120 . In one embodiment, this downward force F M  may be applied by the positioning arm  160  (not shown) through the attachment  210 . In this embodiment, the male latch member  120  is free to rotate as necessary around the central axis  124  even as the downward force F M  is applied. 
         [0022]    In an alternative embodiment, the male latch member  120  may be positioned by a flexible attachment  120  such as a cable (not shown). In that embodiment, gravity acting on the male latch member  120  may be used as a force to latch and unlatch the male latch member  120  to the female latch member  110 . Of course, one who is of skill in the art will realize that tool tolerances for a gravity-operated device must be carefully considered for reliable operation. 
         [0023]      FIG. 2B  shows the male latch member  120  advanced vertically downward toward the central aperture  111  with the chamfered end or truncated cone  128  assisting in correcting for non-alignment of the central aperture  111  and the central axis  124 . In the illustrated embodiment, the first pin  112  contacts a point  201  on the third irregular surface  134  and the male latch member  120  rotates counter-clockwise R cc  (when viewed from above) or left to right as in  FIG. 2B  as the male latch member  120  advances downward toward the female latch member  110 . As the male latch member  120  further advances toward the female latch member  110  and rotates, the first pin  112  moves toward a point  202  on the third irregular surface  134 . 
         [0024]      FIG. 2C  shows the male latch member  120  rotated and advanced so that the first pin  112  is at the point  202  on the third irregular surface  134 . The male latch member  120  continues to advance toward the female latch member  110 , but ceases rotation for a moment, as the first pin  112  moves toward a point  203  on the first irregular surface  131 . 
         [0025]      FIG. 2D  shows the male latch member  120  advanced so that the first pin  112  is at the point  203  on the first irregular surface  131 . The male latch member  120  continues to advance toward the female latch member  110 , but now rotates clockwise R cw  from above (right to left in the FIG.), and the first pin  112  moves toward a point  204  on the first irregular surface  131 . 
         [0026]      FIG. 2E  shows the male latch member  120  advanced so that the first pin  112  is at the point  204  on the first irregular surface  131 . The male latch member  120  is at its farthest advance toward the female latch member  110  until the two members lock in tension. The male latch member  110  force F M  now reverses to an upward vertical force so that the male latch member  120  moves upward relative to the female latch member  110  and the first pin  112  moves toward a point  205  on the second irregular surface  132 . 
         [0027]      FIG. 2F  shows the male latch member  120  withdrawn so that the first pin  112  is at the point  205  on the second irregular surface  132 . The male latch member  120  continues to withdraw from the female latch member  110 , but now rotates clockwise R cw  from above (right to left in the FIG.), and the first pin  112  moves toward a point  206  on the second irregular surface  132 . 
         [0028]      FIG. 2G  shows the male latch member  120  withdrawn so that the first pin  112  is captured at the point  206  on the second irregular surface  132 . Point  206  includes a concavity configured to capture the first pin  112  in tension between the female latch member  110  and the male latch member  120 . The male latch member  120  and the female latch member  110  are now locked in tension and will move vertically, or alternatively horizontally, as a single unit so long as there is continuous upward force F M . The latched condition may be termed temporary because the rotating tension latch  100  is intended for the limited amount of time necessary to reposition the workpiece. 
         [0029]      FIG. 2H  shows the male latch member  120  withdrawn vertically with the female latch member  110  coupled thereto as well as workpiece  150 . The first pin  112  remains captured in tension at point  206 . Therefore, workpiece  150  can be relocated as necessary to the next station on the assembly line. 
         [0030]      FIG. 2I  shows the male latch member  120  located so that the workpiece  150  is at the next station of the assembly line. The workpiece  150 , female latch member  110  and male latch member  120  are lowered until the workpiece  150  is in position. At that time, the female latch member  110  and the workpiece resist further movement, and a downward vertical force F M  may be applied to the male latch member  120  releasing tension on the first pin  112 . This force F M  causes vertical motion of the male latch member  120  relative to the female latch member  110  and places the first pin  112  at a point  207  on the first irregular surface  131 . Continued downward force F M  causes clockwise rotation R CW  of the male latch member  120  and movement of the first pin  112  toward a point  208  on the first irregular surface  131 . This, in one embodiment, unlocks the male latch member  120  from the female latch member  110 . 
         [0031]      FIG. 2J  shows the male latch member  120  advanced so that the first pin  112  is at the point  208  on the first irregular surface  131 . Reversing the vertical force F M  causes the male latch member  120  to move vertically relative to the female latch member  110  and the first pin  112  moves toward a point  209  on the second irregular surface  132 . 
         [0032]      FIG. 2K  shows the male latch member  120  withdrawn from the female latch member  110  so that the first pin  112  is at the point  209  on the second irregular surface  132 . Continued withdrawal of the male latch member  120  by upward force F M  causes the male latch member  120  to rotate clockwise R CW  as the first pin  112  proceeds toward a point  210  on the second irregular surface  132 . 
         [0033]      FIG. 2L  shows the male latch member  120  withdrawn sufficiently from the female latch member  110  that the first pin  112  is at the point  210  on the second irregular surface  132 . Continued withdrawal of the male latch member  120  causes the male latch member  120  to separate completely from the female latch member  110 . 
         [0034]      FIG. 2M  shows the male latch member  120  completely withdrawn from the female latch member  110 . 
         [0035]    One who is of skill in the art will recognize that the pins may also be located on a male member while the first, second and third portions may be located on a female member. Such a configuration will now be discussed. 
         [0036]    Referring now to  FIG. 3A  illustrated is a perspective view of one embodiment of a pick-and-place system  300  constructed according to the principles of the present disclosure. The pick-and-place system  300  comprises a first latch member  311  and a second latch member  312 . In this embodiment, the first latch member  311  is a female latch member  311  having a central axis  313 . The second latch member  312  is a male latch member  312  having a core  315  coincident with the central axis  313  and a base  316 .  FIG. 3B  is an elevation view of the pick-and-place device  300  of  FIG. 3A . 
         [0037]    Referring now to  FIG. 3C  with continuing reference to  FIG. 1 , illustrated is a sectional view of the pick-and-place system  300  along plane  3 C- 3 C. The female latch member  311  comprises a hollow cylinder  320  having an internal surface  314  parallel to the central axis  313  and upon which first, second and third portions  321 - 323  (third portion  323  not visible), respectively, are formed. The first, second and third portions  321 - 323 , respectively, are analogous to the first, second and third portions  125 - 127 , respectively of  FIG. 1 . The male latch member  312  further comprises first and second pins  341 ,  342 , respectively, coupled to an end of the core  315  and extending radially therefrom. While the core  315  is shown as relatively thin, an alternative embodiment is envisioned to have a core that substantially fills the lower cavity of the female latch member  311  with the first and second pins  341 ,  342 , respectively, extending radially therefrom. One who is of skill in the art will realize that the base  316  does not need to be a rectangular plate as shown, but can be any configuration that will readily couple to a workpiece. In the present embodiment, the female latch member  312  reciprocates vertically to temporarily latch with the male latch member  311 . Of course, the relative positions of the female and male members  311 ,  312  can be swapped so that the female member  311  is coupled to the workpiece and the male member  312  performs the latching/unlatching function. The operation of the pick-and-place system  300  is essentially the same as the rotating tension latch  100  of  FIG. 1 . 
         [0038]    One or both latch members could contain sensors to assist a control system or user in recognizing the pin or pins&#39; relative position within the channel. For example, in  FIG. 2E , when the pin  112  reaches the secure position  204 , it could signal the user or automated control system by completing a circuit, touching a contact switch, or otherwise. One skilled in the art will recognize that such a sensor can be placed to sense the position of the pin at any point in the channel. 
         [0039]    It should also be noted that one or both latch members could contain sensors to assist a control system or user in aligning the two parts concentrically before latching. For example, in  FIG. 1 , an optical sensor could be placed at the tip of the cone  128  to sense a mark or light emitter in the center of the female member. Similarly, in the embodiment shown in  FIG. 3A , the sensor could be placed within the female latching member  311  or it&#39;s actuator (not shown), and the target mark or light emitter could be placed on the male pins  312 . Strategically placed magnets could be used to sense or even assist alignment of the two members. 
         [0040]    Thus, a rotating tension latch and a pick-and-place system have been described wherein vertical motion of the one latch member relative to the complementary latch member latches and unlatches the two members. Clockwise or counterclockwise rotation of one latch member is automatically accomplished as the first latch member engages or disengages from the second latch member. One of skill in the pertinent art will readily understand that the roles of the male and female latch members as described may be reversed, i.e., the male latch member may be affixed to a workpiece or other apparatus, and the female latch member may be used to engage and disengage the male latch member. 
         [0041]    Tension in the present disclosure is defined as the resistance of one latch member, e.g., female latch member  110 , to motion when a vertical upward force is applied to the complementary latch member, e.g., male latch member  120 . The use of such terms as providing, forming, etc., as used herein includes: manufacturing, milling, casting, contracting, purchasing, etc. Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.