Patent Publication Number: US-8967594-B2

Title: Apparatus and method for fitting wires with seals or other elastic wire elements

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to European Patent Application No. 10158413.4, filed Mar. 30, 2010, which is incorporated herein by reference. 
     FIELD 
     The present disclosure relates to an apparatus and a method for fitting wires with seals, i.e. it relates to applications in the field of wire processing. The apparatus and the method can also be used on other elastic wire elements. 
     BACKGROUND 
     Seals are sealing elements of silicon or similar material, which are generally used for sealing connector housings or, for example, electrical apparatuses. To effect such sealing, a stripped wire is first fitted with a seal and then crimped with a metal contact. The contact is embodied in such manner that it holds the seal tightly on the wire. 
     Seal-fitting devices may be fully automatic or semiautomatic. Fully automatic seal-fitting devices are used, for example, in wire-processing machines that automatically present the stripped wire to, and remove it from, the seal-fitting apparatus. Semiautomatic seal-fitting devices are typically used as bench top devices, wherein the wire must be inserted into a holding gripper of the seal-fitting apparatus by hand. 
     In the case of seal-fitting devices that operate on simple fitting principles, the wire is pushed directly into the seal. This carries the risk of the internal contour of the seal being damaged. Moreover, this operation cannot be performed with already stripped wires, since the strands of the wire would then be bent. Although stripping after seal-fitting would be possible, it would result in productivity losses and further disadvantages. 
     In more advanced seal-fitting devices, before the seal is fitted it is expanded by being pushed onto an expansion collar, which is embodied as a hollow cylinder. When the wire is being fitted, it is pushed into this expansion collar, and then the expansion collar is pulled out between the wire and the seal, which is held by a releaser. A seal-fitting device in which the seals are expanded before being pushed onto a wire is known, for example, from EP-B1-0 410 416. 
     Known from document US 2008/155816 A1 is a technical solution that allows a flexible seal to be pushed onto a wire. A seal-transfer device and a seal-holding device are used. A seal from a stock is fed into the seal-holding device. Fastened onto the seal-transfer device is a hollow cylindrical body, which is pushed into the seal. Hereinafter, this body is referred to as “hollow cylinder”. Before being pushed in, the seal is moved by the seal-holding device into a transfer position. A pressure-body is then deployed to exert counter pressure against the seal from one side while the hollow cylinder is pushed into the seal. During the pushing-in as described, a needle-shaped guide element sits inside the hollow cylinder in such manner that an end of the needle that tapers to a point projects from an opening of the hollow cylinder, the opening facing in the direction of the seal. The hollow cylinder, along with the needle sitting inside it, is pushed into the seal, while the pressure-body exerts counter pressure as stated. As a result of the needle tapering to a point, the joint pushing-in of the hollow cylinder and the needle proceeds gently. After the hollow cylinder has been pushed into the seal, the needle is retracted to create room inside the hollow cylinder to push-in a wire-end. After the wire-end has been pushed in, the hollow cylinder is retracted, and hence the seal is transferred from the hollow cylinder onto the wire. 
     The following describes characteristic features, as well as advantages and disadvantages, of the two most common fitting principles. A more easily maintainable and more rapidly operating seal-fitting device is disclosed in EP-B1-0 626 738. EP-B1-0 626 738 discloses a seal-fitting device in which a seal, on being removed individually from a feeder-rail, is mounted onto an arbor and, on the arbor, is pushed from a smaller to a larger diameter so as to expand the seal. After the arbor has been swiveled into the correct position, an expansion collar, which is embodied bipartitely, and a releaser, which is also embodied bipartitely, embrace the seal. By means of a relative movement of the releaser, the seal is pushed onto the expansion collar. The fitting operation per se is performed by the expansion collar, along with the seal and the releaser, moving over the wire. During the operation, the releaser remains stationary until the expansion collar has completed its movement, which causes the seal to be released onto the wire. 
     It is an advantage of this approach that the seal is expanded in gently progressive manner. Moreover, the seal cannot slip off the expansion collar, since the former is held by the releaser. Disadvantageous is that through the bipartite embodiment of the expansion collar, the latter has a relatively large external diameter, since the wall thickness cannot be reduced limitlessly. 
     EP-B1-1 022 821 discloses a further apparatus for seal-fitting. After the seal has been individually picked, it is mounted on a tubular monopartite expansion collar. While the seal is being swiveled into the horizontal fitting position, it is not additionally held. After the seal is embraced by a bipartite releaser, fitting takes place through movement over the wire, followed by retraction of the expansion collar. 
     This approach has the advantage that the monopartite expansion collar can be embodied very thin-walled, as a result of which the seal need be only slightly widened. Disadvantageous is that, with certain types of seal, it is difficult to push the seal onto the expansion collar without the seal subsequently slipping off again. The great elasticity of the seal hinders the pushing-on operation. 
     Both fitting principles have the disadvantage that, when the seal is being pushed onto the expansion collar and being released, the seal is not supported on the same shoulder, and hence is pressed together in two opposite directions. This can cause folding-back of the seal, and in series production generally results in a greater variation of the position of the seal. 
     SUMMARY 
     There is therefore a need for providing a remedy. The various embodiments of the technologies disclosed herein enable a simple, certain, and rapid fitting of wires with elastic wire elements, for example with seals. 
     Advantageous further developments of the invention are stated in the dependent patent claims. 
     The fitting principle disclosed herein can be used in both fully automatic and semiautomatic (seal-) fitting devices. The former are used in wire-processing machines that automatically feed the stripped wire to, and remove it from, the seal-fitting device. By contrast, semi-automatic seal-fitting devices are used as bench top devices, in which the wire must be inserted into a holding gripper by hand. 
     Depending on various requirements, however, wires are also fitted with other elastic wire elements, for example, a shrink-tube, or a ring-shaped element, through which the wire is passed. The various embodiments can be used not only for fitting wires with seals, but also for fitting wires with other elastic wire elements. 
     The embodiments of the device are particularly suitable for use in wire-processing machines. 
     Advantageously, the seal is not pushed onto a hollow cylinder but onto a needle, and transferred off the needle onto a wire. The transfer hence takes place preferably directly off the needle onto the wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various disclosed technologies will be explained in more detail symbolically and by way of example on the basis of the figures. The figures are described conjunctively and in general, wherein: 
         FIG. 1A  shows a diagrammatical representation of a first operation step; 
         FIG. 1B  shows a diagrammatical representation of a second operation step; 
         FIG. 1C  shows a diagrammatical representation of a third operation step; 
         FIG. 1D  shows a diagrammatical representation of a fourth operation step; 
         FIG. 1E  shows a diagrammatical representation of a fifth operation step; 
         FIG. 1F  shows a diagrammatical representation of a sixth operation step; 
         FIG. 1G  shows a diagrammatical representation of a seventh operation step; 
         FIG. 2  shows a three-dimensional diagrammatical representation of an apparatus; 
         FIG. 3  shows a three-dimensional diagrammatical representation of details of the apparatus shown in  FIG. 2 ; 
         FIG. 4  shows a diagrammatical cross-sectional representation of details of the apparatus shown in  FIG. 2 ; 
         FIG. 5  shows a further diagrammatical cross-sectional representation of details of the apparatus shown in  FIG. 2 ; 
         FIG. 6  shows a further diagrammatical cross-sectional representation of details of an apparatus; 
         FIG. 7  shows a diagrammatical cross-sectional representation of a needle that can be used, and a section of a wire that is to be fitted; 
         FIG. 8  shows a diagrammatical cross-sectional representation of a thin end of the needle that can be used, and a seal; and 
         FIG. 9  shows a three-dimensional diagrammatical representation of a fitting apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Central to the technologies disclosed herein is a novel fitting principle, which is diagrammatically represented in  FIGS. 1A to 1G  and described below. Shown above  FIGS. 1A to 1G  is an x-axis. By reference to this x-axis, various positions are defined to permit better description of the individual movements. It should be noted here that all movements are relative. These relative movements can also be realized differently than in the example represented in  FIGS. 1A to 1G . 
     An elastic seal  20 , or another elastic wire element, is pushed onto a needle  12 , as shown in  FIG. 1A . Before being pushed on, the seal  20  sits in a position x 1 . When the seal  20  is pushed on, it reaches the position x 2 , as shown in  FIG. 1B . 
     The needle  20  has two external diameters D 1  and D 2  (see also  FIG. 7 ) and, at a first end  14  with the larger external diameter D 2 , is provided with a blind bore  16 , which has an internal diameter D 1 , which is slightly larger than the external diameter of the wire  30  that is to be fitted. At the beginning, this first end  14  of the needle  12  is held by closed centering jaws  13  of a centering gripper, which, as shown in  FIG. 1A , stand in a position x 3 . The centering gripper is only indicated diagrammatically in  FIG. 9 . The second end  15  of the needle  12  stands at a position x 4  and has a smaller external diameter D 1 , which approximately corresponds to the internal diameter of a pass-through aperture  21  of the (unfitted) seal  20  (see  FIG. 8 ). The seal  20  is pushed over this end  15 , which at the beginning is freestanding, onto the needle  12 . This pushing-on movement P 1  is executed by a pusher-on  11 , which is provided with sprung jaws  44  (referred to as pushing-on jaws), which can adapt to the diameter of the needle  12 , which diameter varies along the longitudinal axis from D 1  to D 2 . In the example shown, the pushing-on movement P 1  travels a linear distance whose length is defined by a difference x 2 -x 1 . 
     Shown in  FIG. 1B  is a state after the seal  20  has been pushed onto the needle  12 . The seal  20 , along with the pusher-on  11 , now sits on the area of the needle  12  that has a larger external diameter than the end  15  of the needle  12 . The feathered jaws of the pusher-on  11  enable automatic adaptation of the gap between the jaws  44  (see  FIG. 3 ) to a changing external diameter of the needle  12 . 
     In this example, the centering jaws  13  of the fitting device, or of the fitting apparatus  100 , are embodied locationally fixed, and remain at the position x 3 . Here, the centering jaws  13  can only execute an opening or closing movement perpendicular to the x-axis. Under certain circumstances the centering jaws  13  can be manually displaced and fixed, to enable adaptations to be performed depending on the size and shape of the seal  20 . 
     In another (not shown) embodiment, the centering jaws  13  are executed to be movable, so that they can execute a feeding movement parallel to the x-axis in the direction of the wire  30 . In this case, no drive (drive A 4  in  FIG. 9 ) is required to move the wire  30 . 
     The wire  30  is now inserted through the closed centering jaws  13  into the blind bore  16  of the needle  12 . Instead of a blind bore  16 , another receptacle (e.g. a through hole, or a fastening lug) can be used to accept a wire-end. In this feed movement, the left end of the wire  30  travels a distance from a position x 5  to a position x 6 . To insert the wire  30 , the centering jaws  13  form a central orifice  17 , as may be seen in  FIGS. 1A to 1G . A state after insertion of the wire  30  into the blind bore  16  of the needle  12  is represented in  FIG. 1C . The direction of movement of the wire  12  is indicated by an arrow P 2 . Here, it should be noted that the wire  30  can be, for example, also inserted into the needle  12  before the seal  20  is pushed on from the left. The wire  30  can also remain in the position x 5  while the centering jaws  13 , along with the needle  12 , are moved towards the wire  30 . 
     When the pushing-on movement P 1  of the seal  20  is complete and the wire  30  has been inserted into the blind bore  16 , as shown in  FIG. 1C , the second end  15  of the needle  12  is held by a gripping element  10 . For this purpose, the gripping element  10  is moved from a position x 7  into a position x 8 . The centering jaws  13  of the centering gripper are then opened. This instant is shown in  FIG. 1D . The opening movement of the centering jaws  13  is indicated by the two arrows P 3 . 
     The fitting per se, i.e. the transfer of the seal  20  to the wire  30 , is executed by a backwards movement P 4  of the gripping element  10 , as shown in  FIG. 1D . In this backwards movement P 4 , the gripping element  10 , along with the needle  12 , executes a movement from the position x 8  to the position x 9 . Through this backwards movement P 4 , the needle  12  is pulled out between the seal  20  and the wire  30 . During the backwards movement, the seal  20  is held in its position x 2  by the stationary pusher-on  11 . The backwards movement P 4  is executed by the gripping element  10 , which holds the needle  12  and moves it to the left. 
     After the fitted wire  30  is then moved away to the right (from the position x 6  to, for example, the position x 5 ), as shown with an arrow P 5  (opposite in direction to the backwards movement P 4 ), the needle  12  is moved back into the starting position by a movement P 6  of the gripping element  10 . There, the gripping element  10 , along with the needle  12 , executes a movement from the position x 9  to the position x 8 . The left end of the needle  12  again reaches the position x 4 . Shown in  FIG. 1F  is a state in which the needle  12  has reached the starting position x 4 . 
     In the starting position x 4 , the needle  12  is now again gripped by the closing centering jaws  13 . The arrows P 7  indicate this closing movement of the centering jaws  13 . The state with gripped needle  12  is represented in  FIG. 1G . 
     The gripping element  10  can now release the needle  12  and the next seal  20  can be pushed onto the needle  12 , as described above. The gripping element  10  is, for example, returned into the position x 7 . 
     A preferred constructive embodiment of the fitting apparatus is presented below and described with reference to  FIGS. 2 to 6 . 
     The pusher-on  11  and the gripping element  10  are preferably integrated in a fitting-head  40 , which is part of a fitting device or of a fitting apparatus  100 . Assuming that the seals  20  are fed in a horizontal feeder-rail  42  in accordance with the state of the art described at the outset, the fitting-head  40  is embodied in such manner that it can execute a swiveling movement in the wire-axis A and the longitudinal movements P 1 , P 4 , P 6  in the direction of the wire-axis A. Here, the wire-axis A runs parallel to the x-axis of  FIGS. 1A to 1G . The corresponding swivel drive for executing the swiveling movement in the wire-axis A is not shown. 
     The fitting principle can also be used for alternative seal-feeds, for example, a horizontal feed of the seal  20  is possible. Shown in  FIG. 9  is a corresponding fitting apparatus  100  in which no swiveling movement of the seal-feed is provided. 
     In the embodiment shown in  FIGS. 2 to 6 , an individual-picking tool  41  is used that comprises an inner arbor  50  and a collar  51 . The individual-picking tool  41  serves the purpose of taking the seals  20  from the feeder-rail  42  to the fitting-head  40 . For this purpose, first the inner arbor  50  is pushed through the bore  20  of the seal, and then the seal  20 , through lowering of the collar  51 , is pressed out of the feeder-rail  42  into the fitting-head  40 . This operation is to be seen in  FIG. 4 , where a seal that is referenced with  20 . 1  is just being pushed downwards out of the feeder-rail  42  in the direction P 8 . 
     The drives A 1 -A 5  that are necessary for the movements of the fitting-head  40  and of the wire  30  are shown purely diagrammatically in  FIG. 9 . The swiveling movement in the direction of the wire-axis A can be motorized, or also be effected by means of a pneumatic swivel drive. Depending on the requirements, the various longitudinal movements can be effected pneumatically or by means of a programmable longitudinal axis. 
     The pusher-on  11  is preferably constructed as a replaceable unit and embodied in such manner that it can hold the seal  20  in the receptacle bore  43 , see  FIG. 3 . So that the seal  20  cannot fall out during the swiveling movement of the fitting-head  40 , the receptacle bore  43  is correspondingly embodied. Also possible would be to hold the seal  20  in the receptacle bore  43  by application of a vacuum. By means of a compression spring  46 , the two symmetrically arranged pushing-on jaws  44  of the pusher-on  11  are pressed into the cone  45  of the pusher-on  11  that is arranged behind the receptacle bore  43 . During pushing-on, the pushing-on jaws  44 , guided by the cone  45 , move radially apart, and thereby follow the contour (i.e. the increasing external circumference) of the needle  12 . This is necessary because, as described above, the needle  12  has a circumference that changes in the x-direction. 
     In the case of the fitting-head  40  shown, the gripping element  10  is embodied as a collet  47 . Such collets are used, for example, in similar form on lathes. The collet  47  is fastened to a pull-rod  49 , with which it can be pulled into a collar  48 , which causes the collet  47  to close and, hence, the needle  12  to be gripped. To close or open the collet  47 , the pull-rod  49  need only execute a short stroke, which can advantageously be realized with a not-shown pneumatic cylinder, which executes movements in the direction P 9 . 
     To be able to execute the necessary steps for the fitting principle, the collet  47  must be capable of movement inside the fitting-head  40  in the open and closed state. This relative movement is advantageously also executed pneumatically. 
     To open or close the centering jaws  13 , a commercially available pneumatic centering gripper  60  (see, for example,  FIG. 9 ) can be used. The centering jaws  13  are designed in such manner that, in their closed state, the needle  12  is securely gripped, and access through an orifice  17  to the blind bore  16  is possible. To prevent bending of the strands  31  of the wire  30 , the bore diameter of the orifice  17  of the centering jaws  13  of the centering gripper  60  is embodied slightly smaller than the diameter Di of the blind bore  16  in the needle  12 . 
     Since the seals  20  to be processed vary greatly in their dimensions, the dimensions of the needle  12 , of the centering jaws  13 , of the pusher-on  11 , and of the collet  47 , i.e. the dimensions of the gripping element  10 , are also variable. These parts should be as easy as possible to replace. The lengths, or distances, respectively, of the longitudinal movements P 1 , P 4 , P 5 , P 6  that are indicated by the arrows can, however, remain unchanged, and be adapted to the dimensions of the longest of the seals  20  that is to be processed. 
       FIG. 7  shows a diagrammatical cross-sectional representation of a needle  12 . The needle  12  that is shown has a blind bore  16  which runs coaxially with the longitudinal axis B of the needle. In all embodiments, the needle  12  is embodied monopartite. The external diameter of the needle  12  is smaller at a first end  15  than at a second end  14 . In the example shown, the first external diameter D 1  in the area  15 , and the second external diameter D 2  in the area  14 , are constant. Situated between these areas  15  and  14  is a transitional area  18 , where the diameter gradually changes from D 1  to the diameter D 2 . 
     Also possible is that in the area  15  the diameter slowly increases, thereafter to attain the maximum diameter D 2  in the end area (in  FIG. 7 , at the right). 
     The blind bore  16  preferably extends from the right end of the needle  12  in the direction of the second end  15 . In all embodiments, the blind bore  16  ends already before the transition zone  18 . The diameters D 1 , D 2 , the length of the needle  12 , and the depth of the blind bore  16  depend on the constructional shape and size of the seal  20 , as well as on the position at which the seal  20  should sit on the wire  30 . The internal diameter Di of the blind bore  16  is slightly greater than the external diameter of the wire  30  including insulation. 
     A section of the wire  30  that is to be fitted is shown to the right of the needle  12 , so as to illustrate the dimensions in this diagrammatical representation. 
       FIG. 8  shows a diagrammatical cross-sectional representation of the end-piece  15  of a monopartite needle  12 . Shown immediately adjacent to the needle  12  is an exemplary seal  20  with a central pass-through aperture  21 . In the finished state, the wire  30  runs through this pass-through aperture  21 . Due to the elasticity of the seal  20 , the latter sits tightly on the wire  30 . 
       FIG. 5  shows in a cross-sectional representation further details of the embodiment that was already described. Shown is an instant before transfer of the seal  20  onto the wire  30 . The representation in  FIG. 5  corresponds approximately to the situation shown  FIG. 1C . Transfer takes place through the backwards movement (arrow P 4 ) of the gripping element along with the needle  12 , as described. 
     Through a changed movement pattern, the various embodiments allow the required free wire-overhang K to be reduced, as indicated in  FIG. 6 . For this purpose, before release of the seal  20  from the needle  12 , the position shown in  FIG. 6  is traveled to. In the travel, after opening of the centering jaws  13 , the needle  12  is slightly retracted, and the fitting-head  40  is then moved in the x-direction between the opened centering jaws  13  to the wire  30 . It should be noted that, in this case, the gripping element  10  must travel to three different positions. 
     Particularly in the case of so-called “sheathed wires”, a short wire-overhang K is advantageous. Here, a plurality of wires is surrounded by a sheath. Before processing takes place, this sheath must be removed. In many cases, the so-called unsheathed length should be kept as small as possible, and depends on the required wire-overhang K. 
     Shown in  FIG. 9  is an exemplary fitting apparatus  100  which has a common machine bed  61 . The centering gripper  60  includes the two centering jaws  13  and sits on a first carriage  62 , which here can be moved linearly along the x-axis. The first carriage  62  can contain a corresponding first linear drive, spindle drive, or pneumatic drive A 1 . This drive A 1  is integrated into the carriage  62 , or built onto this carriage  62 . At the instant shown, the centering jaws  13  are holding the needle  12 . The wire  30  has already been pushed through the orifice  17  of the centering jaws  13  into the blind bore  16  of the needle  12 . For this purpose, a second carriage  63  is provided, which here can be moved linearly along the x-axis. The second carriage  63  can contain a corresponding second linear drive, spindle, or pneumatic drive A 2 . This drive A 2  is integrated into the carriage  63 , or built onto this carriage  63 . The wire  30  can be held by, for example, two jaws  64 ,  65 . One of these jaws  64 , (here the back jaw), can be movable, while the other jaw  65 , (here the front jaw), is immovable. Here, the fitting-head  40  is embodied non-swiveling, i.e. it is always aligned in the x-direction, can, however, execute the feeding movements and withdrawal movements parallel to the x-axis, as described at the outset. 
     The internal structure of the fitting-head  40  can be embodied according to  FIG. 5  or  FIG. 6 . Provided on the fitting-head  40  can be a third carriage  66 , which here can be moved linearly along the x-axis. The third carriage  66  can contain a corresponding third linear drive, spindle drive, or pneumatic drive A 3 . This drive A 3  is integrated into the carriage  66 , or built onto this carriage  66 . Provided in, or on, the fitting-head  40 , and indicated in outline, are two drives A 4 , A 5 , which are designed to move the gripping element  10  and the pull-rod  49 . The various gripper movements and/or other movements are preferably executed pneumatically. 
     The fitting apparatus  100  shown in  FIG. 9  can execute a movement of the centering gripper  60  in the direction of the wire. In principle, this is not necessary for execution of the fitting method described herein, can, however, be used for the (not shown) transfer of the seal  20 . This movement of the centering gripper  60  in the direction of the wire is hence optional. 
     It should be noted that all of the movements can be relative movements. These relative movements are preferably the result of a combination of movements, which are generated by the various drives A 1 -A 5  (which, for example, sit in, or on, the carriages  62 ,  63 ,  66 ). They may, however, also be individual movements caused by only one drive. 
     Advantageously, the seals  20 , or other elastic wire elements, must not be expanded as much as in the state of the art. The treatment and handling of the seals  20 , and of other elastic wire elements, is more gentle. Moreover, the risk of damage is reduced. Furthermore, a greater accuracy of the position of the seal on the wire  30  results, and a shorter wire-overhang K is required. 
     Having illustrated and described the principles of the disclosed technologies, it will be apparent to those skilled in the art that the disclosed embodiments can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of the disclosed technologies can be applied, it should be recognized that the illustrated embodiments are only examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims and their equivalents. We therefore claim as our invention all that comes within the scope and spirit of these claims.