Abstract:
A two-piece tool changing device is described. The changing device includes a base and a plate that nests with the base. The base includes a body along with guide brackets and a manifold attached to, or defined within, the base at a point along the peripheral edge of the base. The plate includes shoulders that reversible engage with the guide brackets. A standing section extends from the manifold toward the guide brackets, and defines a channel between the standing section and the body. A spring-biased plunger is optionally disposed within an aperture in the standing section, and the spring plunger is movable between a first position extending into the channel and a second position withdrawn from the channel. At least one conduit is optionally defined in the manifold and a corresponding conduit is defined in the plate, such that the conduit in the manifold and the conduit in the plate are in registration when the plate is nested in the base.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is hereby claimed to provisional application Ser. No. 60/887,466, filed Jan. 31, 2007, which is incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention is directed to a robotic tool changer that enables robotic tooling, especially tools mounted at the end of a robotic arm, to be changed quickly and without using additional hand tools to complete the change. 
       BACKGROUND 
       [0003]    Robotic tool changers are generally known. Several different mechanisms have been described. For example, actively-powered tool changers use pneumatic or electrical means to establish the connection between the robot arm and the desired tool. See, for example, U.S. Pat. No. 4,676,142. Mechanical or passive systems use the robot&#39;s own wrist motion to establish a mechanical link between the robot and the desired tool. See, for example, U.S. Pat. No. 4,512,709. A host of other mechanisms have been described. For example, U.S. Pat. No. 5,044,063 describes a passive robotic tool change mechanism designed to operate in zero-gravity environments. 
         [0004]    As noted in U.S. Pat. No. 4,660,274, in many robotic applications it is very desirable for the tool-changing apparatus to be devoid of switches, motors, or other “active” types of components. Not only are these “active” components expensive, they require rigorous routine maintenance, and are prone to failure absent diligent routine maintenance. 
         [0005]    A host of tool changers are automatic, meaning that the robot itself can make and break the wrist linkage between tools without human intervention. See, for example, any of U.S. Pat. Nos. 4,512,709; 4,604,787; 4,637,121; and 5,993,365. There are, however, a great many robotically-implemented processes that do not require the complexity of either an “active” type of linkage or an automatic mechanism for changing tools. In many industrial processes that use robots, a relatively small number of tools are attached to the robot. On one hand, the number of tool changes required in these situations is likewise relatively small. Thus the high cost of an automatic tool-changing system cannot be justified. On the other hand, the tool changes (while small in number) still must take place for the robot to accomplish its assigned tasks. Without an automatic tool changer, each tool change entails robot down-time and human manual input to detach the current tool and to attach another, different tool. Therefore, even in robotic processes that require only a small number of tool changes, and where those tool changes are accomplished manually, those tool changes need to take place as quickly as possible, yet with an absolute maximum level of safety and security. Industrial robots are extremely powerful machines. A tool that is improperly attached to the robot due to haste or inattention on the part of the human operator not only can destroy the work piece which the robot is manipulating, but seriously injure or kill the operator and others working near the robot. 
         [0006]    Thus there remains a long-felt need for a secure, passive, manually-operated, quick-change device for changing tools at the end of a robotic arm. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention is a tool-changing device for robotic arms. One version of the device comprises, in combination, a base and a nesting plate. The base comprises a body, guide brackets attached to or defined within the body, a manifold attached to, or defined within the body at a point along the peripheral edge of the body; and a standing section extending from the manifold toward the guide brackets, such that a channel is defined between the standing section and the body. The plate has a peripheral edge and is dimensioned and configured to nest in face-to-face orientation with the body of the base. The plate comprises at least two shoulders that are dimensioned, configured, and positioned to engage the guide brackets of the base. When the shoulders are engaged to the guide brackets, at least a portion of the plate is disposed within the channel defined between the standing section and the body. When the plate is nested within the base, a reversible linkage is established between the base and the plate. 
         [0008]    In other versions of the invention, an aperture is defined in the standing section and passing through the standing section. A corresponding aperture is defined in the plate. Thus, the aperture in the standing section and the aperture in the plate are in registration when the plate is nested in the base. A spring-biased plunger is optionally disposed within the aperture in the standing section. The spring plunger is movable between a first position extending into the channel defined between the standing section and the body, and a second position withdrawn from the channel. 
         [0009]    In the preferred version of the invention, at least one conduit is defined in the manifold. The conduit passes through the manifold. There is also a corresponding conduit defined in the plate. The conduit in the manifold and the conduit in the plate are in registration when the plate is nested in the base. In the preferred version, the conduit in the plate has a first open end and a second open end, and the first and second open ends are disposed in the peripheral edge of the plate. The tool changer may include eight (8) or more conduits defined in the manifold and passing therethrough, and a corresponding eight (8) or more conduits defined in the plate. As before, the conduits in the manifold and the conduits in the plate are in registration when the plate is nested in the base. 
         [0010]    The invention has several advantages, the foremost of which is that it provide a robust and secure linkage between a robotic arm and a tool, while at the same time the linkage is easily broken and reestablished by human intervention. The invention allows robotic arm-end tools to be changed quickly and without the need for additional hand tools. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a left perspective view of the preferred version of the invention showing the plate  12  engaged with the base  14 . 
           [0012]      FIG. 1B  is a right perspective view of the preferred version of the invention showing the plate  12  engaged with the base  14 . 
           [0013]      FIG. 2A  is a left perspective view as shown in  FIG. 1A , with the plate  12  disengaged from the base  14 . 
           [0014]      FIG. 2B  is a right perspective view as shown in  FIG. 1B , with the plate  12  disengaged from the base  14 . 
           [0015]      FIG. 2C  is a left, bottom perspective view of the invention, with the plate  12  disengaged from the base  14 , and illustrating the apertures passing through the air/vacuum manifold  22 . 
           [0016]      FIG. 3A  is a right elevation view of the preferred version of the invention with the plate  12  engaged with the base  14 . 
           [0017]      FIG. 3B  is a left elevation view of the preferred version of the invention with the plate  12  engaged with the base  14 . 
           [0018]      FIG. 4A  is a right elevation view as shown in  FIG. 3A , with the plate  12  disengaged from the base  14 . 
           [0019]      FIG. 4B  is a left elevation view as shown in  FIG. 3B , with the plate  12  disengaged from the base  14 . 
           [0020]      FIG. 5  is a front elevation view of the preferred version of the invention with the plate  12  engaged with the base  14 . 
           [0021]      FIG. 6  is a top plan view of the preferred version of the invention with the plate  12  engaged with the base  14 . 
           [0022]      FIG. 7  is a front perspective view of the assembled base  14   
           [0023]      FIG. 8  is an exploded front perspective view of the base  14 , illustrating how the guide brackets  18  and air/vacuum manifold  22  attach to the body  16 . 
           [0024]      FIG. 9  is a left perspective view of the plate  12  and interlocking bushing  28 , and showing the apertures  50 - 54 . 
           [0025]      FIG. 10  is a perspective view of the plate  12 , illustrating the shoulders  30  that interlock with the guide brackets  18  of the base  14 . 
           [0026]      FIG. 11  is a front elevation view of another version of the invention with the plate  12  engaged with an electrical adaptor  60 . 
           [0027]      FIG. 12  is a front elevation view of yet another version of the invention with the base  14  engaged with an electrical adaptor  60 ′. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The same reference numerals are used throughout all of the drawings to identify the same elements in each of the drawings. 
         [0029]    Referring now to  FIGS. 1A ,  1 B,  2 A,  2 B,  2 C,  3 A,  3 B,  4 A,  4 B,  5  and  6 , these figures depict a quick-change device  10  according to the present invention. The device  10  includes two major parts: a plate  12  and a complementary base  14 . The plate  12  is dimensioned and configured to securely engage the base  14 . Vice-versa, the base  14  is dimensioned and configured to securely engage the plate  12 .  FIGS. 1A ,  1 B,  3 A,  3 B,  5  and  6  depict the plate  12  engaged with the base  14 .  FIGS. 2A ,  2 B,  2 C,  4 A, and  4 B are exploded views depicting the plate  12  separated from the base  14 . 
         [0030]    Referring specifically to  FIG. 7 , the base  14  is comprised of several parts that are either machined from a single billet of material (i.e., the base can be monolithic) or which are formed from distinct parts that are then assembled to yield the base  14 . As shown in  FIG. 7 , the base  14  comprises a body  16  having attached to it or defined within it a pair of opposed guide brackets  18 . Preferably each guide bracket defines a channel  20 , and the two channels are co-linear, as shown in  FIG. 7 . The body  16  also has attached to it, or defined within it, an air/vacuum manifold  22  having a plurality of apertures  51 - 58  passing through the manifold. (See  FIG. 2C  for aperture  55 , which is hidden from view in  FIG. 7 .) A standing section  24 , extending from the manifold  22 , is provided such that a channel  40  (see  FIG. 4A ) is defined between the standing portion  24  and the body  16 . 
         [0031]      FIG. 8  depicts an exploded version of the base  14  as shown in  FIG. 7 . As noted in the prior paragraph, the various sub-elements of the base  14  can either be machined from a single billet, or, as shown in  FIG. 8 , fabricated separately and then brought together. As shown in  FIG. 8 , the various parts (described in full momentarily) are attached to a body  16  by fasteners  19  and  23 . (The fasteners can be of any design, without limitation, including screws, pins, rivets, etc.) Preferably, the various elements of the base are attached to the body  14 , rather than body and associated parts being milled from a single block of material. The plate  12  can then be engaged with the base  14 , and the fasteners  23  and  19  are adjusted to ensure a snug fit between the plate and the base. It is preferred that once a suitably snug fit of the plate into the base is attained, the various elements (guide brackets  18  and manifold  22 ) are then permanently welded to the body  16 , to insure the rigidity and robustness of the linkage between the base and the body. 
         [0032]    Shown in  FIG. 8  are the body  16  and two guide brackets  18 . The guide brackets are affixed to the body via fasteners  19  that pass through corresponding apertures  17  in each guide bracket  18  and into the body  16 . Similarly, the air/vacuum manifold  22  is affixed to the body via fasteners  23  that pass through corresponding apertures  21  in the manifold  22  and the body  16 . The standing section  24  includes an aperture  25  passing therethrough. The aperture  25  is dimensioned and configured to accept a spring plunger  26 . The spring plunger is biased to extend into and through aperture  25 . That is, the spring plunger is biased to extend all the way through the standing section  24 . This is best shown in  FIGS. 4A and 4B . The spring plunger can be withdrawn from aperture  25  by pulling on the ring, thus allowing the plate to be inserted into channel  40  as shown in  FIGS. 4A and 4B . The aperture  25  and spring plunger  26  may be threaded, or the spring plunger may be friction fit, glued, welded, or otherwise immobilized within the aperture  25 . 
         [0033]    Referring now to  FIGS. 2C and 7 , passing through the air/vacuum manifold  22  are a series of channels,  51 - 58 . The upper opening of these channels (that is, the openings depicted in  FIG. 7 ) are in registration with a corresponding series of channels defined within the plate  12 . This is best seen in  FIG. 2C . See also  FIG. 9  for a view of the corresponding channels in the plate  12 . For clarity, the channels in the plate are defined by corresponding numbers, and using prime symbols to designate each end of the channel. Thus,  51 ′ and  51 ″ define each end of a channel passing through the plate  12 . The same applies for  52 ′ and  52 “and so on, up to  58 ′ and  58 ″. Thus, when the plate  12  is engaged with the base  14 , channel  51  in the manifold is in registration with channel opening  51 ′ in the plate  12 ; channel  52  in the manifold is in registration with channel opening  52 ′ in the plate  12 ; and so on, up to channel  58  in the manifold, which is in registration with channel opening  58 ′ in the plate  12 . Thus, when the plate  12  is engaged with the base  14 , there are  8  conduits passing through the manifold  22  and the plate  12 . This conduits can be designated by their channel openings:  51  and  51 ″,  52  and  52 ″,  53  and  53 ″,  54  and  54 ″, and so on, as shown in  FIG. 2C . The channel openings  51 ″ through  58 ″ are best seen in  FIGS. 3A and 3B . These channels can be used for pneumatic, hydraulic or electrical control elements to pass through the device of the present invention to the tool affixed to the plate  12  of the device. 
         [0034]    Referring now to  FIGS. 9 and 10 , the plate  12  has an aperture  25 ′ passing therethrough, and a bushing  28  that is fit within the aperture  25 ′. The bushing is for wear resistance in the event the plate  12  is made of aluminum and the spring plunger  26  is made of a stronger metal, such as steel. In that instance, the plunger would cause wear on aperture  25 ′. Thus, the bushing  28  is preferably made of any suitably stiff, wear-resistant material, such as steel or other alloys. With the bushing  28  inside the aperture  25 ′, the aperture  25 ′ of the plate lines up in registration with aperture  25  and spring plunger  26  of the base  14  (see  FIGS. 8 ,  4 A, and  4 B). Additionally, the plate  12  includes shoulders  30  that are dimensioned and configured to engage with the guide brackets  18  of the base  14 . Thus, to engage the plate  12  with the base  14 , the spring plunger  26  is manually withdrawn through aperture  25 , thus providing clearance through channel  40 . The plate  12  is inserted into channel  40 , in face-to-face orientation with body  16 . (See  FIGS. 4A and 4B ). At the moment the plate  12  is inserted fully into channel  40 , and pushed into face-to-face contact with the body  16 , two things occur: (1) the shoulders  30  of plate  12  firmly engage within the channel  20  defined by guide brackets  18 ; and (2) the biased action of the spring plunger  26  forces the spring plunger back through aperture  25  of the base and into aperture  25 ′ of the plate. Thus, the plate  12  is firmly engaged or nested with the base  24 , as shown in  FIGS. 1A ,  1 B,  3 A, and  3 B. 
         [0035]    In operation, a plate  12  is affixed to the tool to be used (not shown) by any means now known in the art or developed in the future. Preferably this is done via fasteners (not shown) that pass through apertures  11  in the plate. Preferably, the plate is attached to the tool in a semi-permanent manner. In short, to make tool changes faster, each tool should have attached to it a plate  12 . The base  14  is affixed to a robot arm by any means now know to the art or developed in the future. To change tools, the user simply pulls on spring plunger  26  with one hand, and removes the tool (with its affixed plate  12 ) from the base  14 . A new tool (with its own affixed plate  12 ) is then engaged with the base  14  via the tool&#39;s affixed plate. 
         [0036]      FIGS. 11 and 12  show alternative versions of the invention wherein an electrical adapter,  62  in FIG.  11  and  62 ′ in  FIG. 12 , is attached to the plate  12  or to the base  14  (or both). Referring now to  FIG. 11 , the adaptor  60  is shown having apertures  61  passing therethrough. The apertures are in registration with corresponding apertures  63  in the plate  12 . Dowel pin holes  65  are provided to ensure that the adapter  62  is fixed to the plate  12  in proper registration. Dowels (not shown in  FIG. 11 ) are inserted into the pin holes  65  to align the adapter  62  with the plate. The adaptor is attached to the plate using any suitable type of fastener, as noted earlier. The adaptor includes a pocket  62  defined therein to house any type of electrical connector or jack, such as a 25-pin DIN connector (not shown). 
         [0037]    Similarly, as shown in  FIG. 12 , an electrical adaptor  60 ′ may also be attached to the body  16  of the base via apertures  17 . As shown in  FIG. 12 , the adaptor includes a pocket  62 ′ defined therein to house any type of electrical connector or jack, such as a 25-pin DIN connector (not shown). 
         [0038]    Providing the adaptors  60  and  60 ′ allows the device to provide instructions to or feedback from tools mounted to a robot via the quick-change device. 
         [0039]    In terms of preferred dimensions and material, the following information relates solely to the preferred embodiment of the invention. Other materials and other dimensions are explicitly within the scope of the invention. The plate  12  is preferably machined from 6061 aluminum. The eight apertures  51 ′ to  58 ′ in plate  12  are preferably 0.159″ diameter. The eight corresponding apertures  51 ″ to  58 ″ are also preferably 0.159″ diameter. The depths of these apertures are such that aperture  51 ′ intersects with aperture  51 ″, creating a conduit,  52 ′ with  52 ″, and so on, up to the conduit between aperture  58 ′ and aperture  58 ″. Thus, in the preferred embodiment, plate  12  has eight conduits passing through it. The invention includes versions having at least one conduit, and more than eight conduits passing through the plate  12  and base  14 . The apertures  11  are preferably drilled 0.201″ diameter and tapped 0.250″-20 through the plate thickness. Aperture  25 ′ is preferably drilled and reamed through the thickness of the plate and dimensioned and configured to accept a pressed in drill bushing (0.312 inch ID×0.500 inch OD×0.0375 thickness). 
         [0040]    As shown in  FIG. 8 , the base preferably comprises four pieces of low-carbon, flat-ground steel machined into the elements that comprise the base  14 . The body  16  preferably is machined from low-carbon, flat-ground steel stock. The apertures  21  for mounting the manifold  22  are preferably 0.106″ diameter. The apertures  17  for mounting the guide brackets  18  are also preferably 0.106″ diameter 
         [0041]    The air/vacuum manifold  22  is machined from low-carbon steel. The apertures  21  (to attach the manifold to the body  16 ) are preferably 0.136″ diameter and counter bored 0.288″ diameter×0.150 deep to provide for clearance for fasteners  23  (preferably #6-32×0.0500 long socket head cap screws). Channels  51 - 58  are preferably 0.0159″ diameter and counter bored. The aperture  25  in the standing section  24  is preferably 0.422″ diameter. The spring plunger  26  is of a complementary diameter to engage within the aperture  25 . 
         [0042]    The guide brackets  18  are machined from low-carbon, flat-ground steel. Each guide bracket  18  preferably has a 0.325″ wide×0.210″ deep groove  20  machined in the top surface, as shown in the figures. The apertures  17  in each Guide Bracket are preferably 0.136″ diameter and counter bored 0.228″ diameter×0.150″ deep, which is the appropriate clearance for fasteners  19  (#6-32 UNC socket head cap screws) that fasten the guide brackets  18  to the body  16 . 
         [0043]    It is important to insure that the plate  12  can easily be nested and removed from the base  14 . To ensure a optimized fit between the plate  12  and the base  14 , the guide brackets  18  and manifold  22  are first attached to body  16  of the base using fasteners  19  and  23  as shown in  FIG. 8 . The plate  12  is then engaged with the base  14 . With the plate nested within the base, all mating surfaces are then adjusted so that they are flush with each other. The fasteners  19  and  23  are then fully tightened and the fit again checked. The plate  12  should be able to be removed and nested within the base  14  without obstruction and by applying only a moderate amount of manual force. When seated within the base  14 , however, the plate  12  is rendered immobile relative to the base  14 . 
         [0044]    Once a snug and easily releasable fit is obtained, the manifold  22  and the guide brackets  18  are preferably welded to the body  18 , thus ensuring the dimensional stability of the base  14 .