Abstract:
A fastener dispensing apparatus includes a body that defines a punch path and at least partially surrounds a punch that includes forward and rearward portions. The punch reciprocates between retracted and advanced positions in which the tip of the forward portion extends from an end of the punch path to drive a fastener towards the workpiece. A fastener feed path extends transverse to the punch path and is defined by a surface of the body, the fastener feed path receives an elongate carrier of fasteners. A fastener feeding device sequentially feeds fasteners along the fastener feed path and into alignment with the end of the punch path. An actuator is drivable by the reciprocal movement of the rearward portion of the punch. An engagement member engages the carrier and is moveable relative to the body.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase application of PCT Application No. PCT/GB2010/001957, filed Oct. 22, 2010 which claims priority to U.S. Patent Application No. 61/260,151, filed Nov. 11, 2009, the entire contents of which are hereby incorporated by reference therein. 
    
    
     BACKGROUND 
     The present invention relates to fastener dispensing apparatus having a fastener feeding device for feeding fasteners into the path of a punch of the apparatus, the punch being drivable to dispense a fastener and optionally insert it into a workpiece. 
     The term “fastener” is used here to include, for example, rivets, screws, slugs and other types of fasteners. The term “punch” is used here to include any appropriate component of a fastener insertion apparatus which inserts such fasteners into a workpiece. 
     SUMMARY 
     A fastener insertion apparatus, such as a punch riveter, is commonly used in the construction of a wide variety of workpieces, such as white goods and automobiles. The fastener insertion apparatus includes a reciprocally translating punch and a feeding device which feeds fasteners into the path of the punch. Such fastener insertion apparatus are often used in large scale continuous production lines over long periods of time. It is therefore desirable that the fastener insertion apparatus is equipped with a feeding device capable of reliably providing a large supply of fasteners into the path of the punch. 
     It is desirable that a feeding device functions reliably so as to avoid errors, such as a fastener not being supplied to the fastener insertion apparatus when expected or a fastener being incorrectly fed into the path of the punch. Such errors can result in a halt in production, in the fastener insertion apparatus incorrectly fastening workpieces together, or in damage to either the workpieces or the fastener itself. 
     A halt in production is a costly delay in itself. However, damage to the feeding device or the fastener insertion apparatus can be a particularly problematic cause of delays because the machines must be taken offline so as to be repaired. In the case of a production line this requires shutting down production for a time, at a significant cost. The feeding device and fastener insertion apparatus should therefore function reliably and robustly in order to reduce the likelihood of delays due to the need to repair or replace them. 
     Fasteners are often fed into fastener insertion apparatus supported in an elongate flexible carrier such as a tape. The tape comprises a number of spaced apart holes along its length, into which fasteners are inserted and is fed into the path of the punch so that, the punch sequentially drives each fastener from the tape and inserts it into a workpiece. 
     In such a tape-fed fastener insertion apparatus, the feeding device feeds the tape through the fastener insertion apparatus so that each fastener in the tape becomes aligned with the path of the punch and is inserted by the punch into a workpiece which is being fastened. A common solution to the problem of timing movement of the tape during a fastener insertion cycle is to use the reciprocal movement of the punch to drive the feeding device. 
     In one such example, a punch-driven rivet insertion apparatus described in a PCT patent application published as WO 93/09918 incorporates a guide bush, within which a punch travels, a punch-driven index wheel which feeds a tape of rivets through the apparatus, and a nose piece which is pressed against a workpiece into which a rivet is to be inserted. During a rivet insertion cycle, the punch emerges from an end of the guide bush and travels through a cavity defined through the centre of the index wheel. After the punch passes through the cavity, it drives a rivet from the tape, through the nose piece and into the workpiece. As the punch drives the rivet into the workpiece, a rearward portion of the punch engages the index wheel, causing the index wheel to rotate. Rotation of the index wheel by the punch causes the wheel to index along the tape. The index wheel is biased by a torsion spring so that, when the punch retracts, the index wheel rotates back to its original position. The return motion of the wheel feeds the tape further through the apparatus, feeding the next rivet on the tape into the path of the punch. In some commercial embodiments the function of the torsion spring is fulfilled by a stripper spring, which is primarily used in the apparatus to bias the nose piece away from the punch as the punch is retracted at the end of a rivet insertion cycle. This double function of the stripper spring is achieved by providing a push rod between the stripper spring and the index wheel. 
     One problem with the above described apparatus is that the punch is unsupported as it travels through the cavity defined in the index wheel. As a result, should the punch drive an incorrectly aligned rivet against the nose piece, shear stresses may be imparted to the punch that can potentially cause damage. 
     A further problem is that, as the punch retracts, it can catch the next rivet on the tape “lifting” the rivet from the tape sufficiently to dislodge it. Thus, when that rivet is fed into the path of the punch, and subsequently punched, it is misaligned and causes a jam, or even damage to the apparatus. This is particularly a problem with short rivets as they can be lifted out of the tape carrier completely. 
     It is an object of the present invention to obviate or mitigate at least some of the problems outlined above. An alternative object is to provide for improved or alternative fastener insertion apparatus 
     According to a first aspect of the present invention there is provided fastener dispensing apparatus for dispensing fasteners comprising: a body in which a punch path is defined; a punch at least partially within the punch path, the punch being reciprocally moveable between a retracted position and an advanced position in which it extends from an end of the punch path in order to drive a fastener towards a dispensed position; a fastener feed path extending transverse to the punch path, the fastener feed path being arranged for receipt of an elongate carrier of fasteners; and a fastener feeding device for feeding the elongate carrier along the fastener feed path such that fasteners are sequentially brought into alignment with the end of the punch path, the fastener feeding device comprising an actuator moveable relative to the body by the reciprocal movement of the punch and at least one engagement member for engaging the elongate carrier or a fastener in the carrier, the at least one engagement member being moveable relative to the body in response to movement of the actuator. 
     The movement of the punch, which is typically in a rectilinear direction, between the retracted and advanced positions thus effects feeding of the elongate carrier so as to bring the next fastener into line with the punch path. The movement of the at least one engagement member relative to the body in which the punch path is defined provides for apparatus that is reliable and compact. 
     The actuator may be provided within the body and may be moveable by contact with a part of the punch at an appropriate point in its reciprocation in the punch path. The actuator may be coupled directly or indirectly to the at least one engagement member. The actuator may extend at least partially into the punch path. 
     The fastener feed path may be defined at least in part by a surface of the body. This is advantageous in that the surface of the body limits the movement of fasteners in the elongate carrier relative to the apparatus and relative to the elongate carrier. This ensures that fasteners in the carrier are fed into the path of the punch in a reliable fashion. For example, the surface substantially prevents lifting or hooking of the fasteners by the punch during retraction, thus improving reliability of performance of the fastener insertion apparatus. The fastener feed path may extend through the body or may extend at one end. 
     In one embodiment, the at least one engagement member is reciprocally moveable between a retracted position in which it is disengaged from the carrier or fastener and an advanced position in which the carrier is advanced so as to bring a fastener into alignment with the end of the punch path. The movement of the engagement member back and forth between the retracted and advanced positions in response to the movement of the punch provides for reliable indexing of the fasteners in the carrier. It enables the carrier to be advanced along an arcuate feed path that has a sufficiently large radius to prevent kinking or unwanted bending of the carrier whilst allowing for a compact arrangement of the dispensing apparatus. In particular, a reciprocating engagement member can be arranged to occupy a much smaller spatial envelope in comparison to a rotating sprocket wheel. If the engagement member is arranged to engage the carrier rather than the fastener this has the advantage that it can be used with short fasteners that do not protrude significantly from the carrier. The idea of a reciprocating engagement member of this kind may be used independently of whether measures are taken to prevent lifting of the rivet or to support the punch during its passage through the body. 
     In operation the punch moves in a first direction along the punch path towards the workpiece. When it reaches the advanced position it extends into the fastener feed path so as to drive a fastener from the elongate carrier. 
     A nose may be provided for engagement with the workpiece. The nose may have a fastener delivery passage therethrough for delivery of a fastener to the workpiece after it has been removed from the elongate carrier and the fastener feed path by the punch. The fastener feed path may be defined at least in part by a clearance between the nose and the body. The nose is preferably fixed relative to the body. The nose may have an end surface for contact with the workpiece. 
     The actuator may be provided within the body so as to be engageable by the punch within the punch path, providing a compact solution to the problem of driving the feeding device. 
     The actuator may be engaged by a part of the punch in order to effect movement in the fastener feeding device. The engagement of the punch with the actuator may cause translational movement of the actuator substantially parallel to the punch path. 
     The actuator may be biased towards an initial position, to which it returns after engagement of the punch with the actuator ends. This return of the actuator means that the actuator need only be driven in one direction, which provides a simpler construction than one in which the actuator must be driven in both directions. 
     The bias may be provided by a resiliently compressible biasing member such as, for example, a spring. Translational movement of the actuator parallel to the punch path under engagement from the punch may cause compression of the biasing member. 
     The biasing member may be provided on substantially the opposite side of the punch path to the actuator. 
     Providing the biasing member separate from the actuator provides greater freedom in the design of the biasing member itself. It also allows a design of feeding mechanism in which the biasing member can be serviced and replaced without the need to remove or reposition the actuator, making the biasing member more easily accessible. 
     The punch may have a first portion at least a part of which extends from the punch path in the advanced position and a second portion, the actuator being moveable by the second portion of the punch. The actuator may be engageable by the second portion. The first portion may be a punch rod and the second portion may be a punch head or boss. 
     The actuator may be mechanically coupled to the at least one engagement member. The at least one engagement member may pivot about a pivot axis which intersects the body and/or which intersects the punch path. The at least one engagement member may have a first end that is coupled to the actuator and a second end for engagement with the carrier and/or the fastener. The pivot axis is preferably disposed between the first and second ends. The actuator may be biased by the biasing member, with the actuator being offset from the pivot axis on one side and the biasing member being offset from the pivot axis on an opposite side. 
     The body may have a bore that defines the punch path. The punch path or the bore may be defined by a support surface of the body and the punch may be supported along its length by the support surface as it reciprocates in the bore along the punch path. The support surface thus provides support to the punch throughout its insertion cycle such that in the event of a misfeed where the punch encounters a misaligned fastener and potentially damaging resistance forces are imparted to the punch the support surface prevents or restricts damage to the punch. 
     The punch path preferably defines a punch path axis along which the punch reciprocates and from which the punch extends to intersect the fastener feed path. The at least one engagement member is preferably moveable relative to punch axis. 
     The at least one engagement member may be external to the body or may be mounted within the body. The at least one engagement member comprises a first portion which extends alongside the body and a second portion which occupies the fastener feed path. 
     The at least one engagement member may engage the carrier or the fastener. In the case of the former the engagement member may comprise a main element and an engagement element moveable relative to the main element. The main element may be operated by the actuator and the engagement element may be moveably mounted on the main element. The engagement member may comprise a further biasing member, the further biasing member configured, in use, to bias the engagement element towards engagement with the carrier. The engagement element may be in the form of a tooth for engagement in an aperture or recess in the carrier. 
     The engagement element may be rotatably mounted on the main body. Such an arrangement is advantageous in that it allows more complex movement of the formation on the engagement member with respect to the carrier. The whole engagement member need not move in order to move the formation into (or out of) a driving position relative to the carrier. 
     The at least one engagement member may engage a fastener supported in the carrier. It may comprise an abutment surface such that, in use, the abutment surface abuts at least one of the fasteners supported in the elongate carrier so as to sequentially feed the fasteners into alignment with the end of the bore. The engagement member may have a tapered surface such that, in use, abutment of the tapered surface against at least one further fastener deflects the at least one engagement member around the fastener. 
     An advantage of engaging the carrier, rather than engaging a fastener in the carrier, is that the carrier can be reliably indexed through the apparatus even in the case when a fastener is missing from the carrier. Moreover, a wider variety of fasteners can be carried by the carrier since they do not need to be any particular shape in order to be indexed through the apparatus. 
     The body may comprise a guide bush for supporting the punch or it may be detachably connected to a guide bush that receives an upper part of the punch. The guide bush may be connectable to a driving actuator such as a hydraulic actuator. 
     A locking member may be provided that is engageable with the carrier such that, in use, the locking member prevents reverse movement of the carrier along the fastener feed path when a fastener is in the path of the punch. The locking member may be disposed in a downstream portion of the feed path. 
     The body may define an abutment surface in the fastener feed path, the abutment surface serving, in use, to prevent fasteners from being fed past the punch path and thus misaligned. The abutment surface may be an extension of the punch path. 
     The components of the fastener feeder device allow it to be packaged in a relatively slender unit in the direction of the tape. This allows the apparatus to be used in areas that have limited access. This is in contrast to existing insertion apparatus where the drive for the carrier tape is often disposed alongside the tape. 
     The fastener feed path may be defined by at least one carrier support for supporting the carrier in its movement along the feed path. A first carrier support may be defined on an opposite side of the fastener feed path to the body. The first carrier support may be defined upstream and/or downstream of the punch path. A second carrier support may be defined on the same side of the feed path and the punch path. At least part of the second carrier support may be defined by the fastener feed device and in particular by the at least one engagement member. At least part of the second carrier support may be defined upstream of the punch path. The at least one engagement member may be disposed so as to urge the elongate carrier into contact with the second carrier support. The second carrier support may define a recess to accommodate deflection of the carrier by the at least one engagement member. 
     According to a second aspect of the present invention there is provided fastener dispensing apparatus for dispensing fasteners into a workpiece, comprising: a body through which a punch path is defined; a punch at least partially within the punch path, the punch being reciprocally moveable between a retracted position and an advanced position in which the punch extends from an end of the punch path in order to drive a fastener towards a dispensing, the body defining a support surface that extends alongside the punch path and supports the punch during its movement along the punch path from the retracted to the advanced position; a fastener feed path extending transverse to the punch path, the fastener feed path being arranged for receipt of an elongate carrier of fasteners, the punch intersecting the fastener feed path in the advanced position; and a fastener feeding device for feeding the elongate carrier along the fastener feed path such that fasteners are sequentially brought into alignment with the end of the punch path, the fastener feeding device comprising an actuator moveable relative to the body by the reciprocal movement of the punch and at least one engagement member for engaging the elongate carrier or a fastener in the carrier, the at least one engagement member being moveable relative to the support surface. 
     The support surface may be defined by the part of the body that defines the punch path, which may be in the form of a bore. The body may also define a portion of the fastener feed path, more particularly an end of the body may define a surface that bounds the fastener feed path. 
     The apparatus in any of the aspects of the invention may be designed to insert a fastener into a workpiece after or at the same time as it is dispensed. 
     It will generally be appreciated that the features of the first aspect of the present invention as set out above may readily be taken in combination with the features of the second aspect of the present invention, either individually and in combinations. 
     According to a third aspect of the invention there is provided a method for dispensing a fastener comprising: providing an elongate carrier of fasteners in a fastener feed path; reciprocating a punch along a punch path in a body between a retracted position and an advanced position and into contact with a fastener disposed in the elongate carrier of fasteners, the fastener feed path extending transverse to the reciprocating direction of the punch, thereby driving a fastener out of the carrier towards a dispensed position; and using an actuator to feed the elongate carrier along the fastener feed path such that fasteners are sequentially brought into alignment with the end of the punch path; the reciprocal movement of the punch effecting movement of the actuator relative to the body; engaging the elongate carrier or at least one fastener in the elongate carrier with at least one engagement member and moving the at least one engagement member relative to the body in response to movement of the actuator; supporting a fastener adjacent to the punch path with a surface of the body, the surface defining at least part of the fastener feed path. 
     According to a fourth aspect of the present invention there is provided a method for dispensing a fastener comprising: providing an elongate carrier of fasteners in a fastener feed; reciprocating a punch along a punch path in a body between a retracted position and an advanced position and into contact with a fastener disposed in the elongate carrier of fasteners, the fastener feed path extending transverse to the reciprocating direction of the punch, thereby driving a fastener out of the carrier towards a dispensed position; supporting the punch with a support surface that extends alongside the punch path and supports the punch during its movement along the punch path from the retracted to the advanced position; using an actuator to feed the elongate carrier along the fastener feed path such that fasteners are sequentially brought into alignment with the end of the punch path; the reciprocal movement of the punch effecting movement of the actuator relative to the body; engaging the elongate carrier or at least one fastener in the elongate carrier with at least one engagement member and moving the at least one engagement member relative to the body in response to movement of the actuator. 
     In each of the method aspect of the invention the fastener may be inserted into a workpiece after or at the same time as being dispensed. 
     It will be appreciated that the inventive aspects outlined above may be applied to the dispensing, placing or insertion of components other than fasteners using the same feeding device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Specific embodiments of the invention are now described, by way of example only, with reference to the accompanying figures, in which: 
         FIG. 1  is a cross-sectional side view (along line A-A of  FIG. 4 ) of an embodiment of a fastener insertion apparatus in accordance with aspects of the present invention including a punch and shown loaded with a carrier tape of rivets; 
         FIG. 2  is an exploded perspective view of the fastener insertion apparatus of  FIG. 1 , shown without the carrier tape of rivets; 
         FIG. 3  is a partially assembled perspective view of part of the apparatus of  FIG. 2 ; 
         FIG. 4  is an orthogonal projection of the fastener insertion apparatus of  FIG. 1  in the direction of arrow B, shown without the carrier tape of rivets; 
         FIG. 5  is an end view of the fastener insertion apparatus of  FIG. 1  in the direction of arrow C, shown without the carrier tape of rivets; 
         FIGS. 6A to 6E  show cross-sectional side views of the fastener insertion apparatus of  FIG. 1  including the punch and shown loaded with a carrier tape of rivets, the views showing a chronological sequence of the feeding process during a single fastener insertion cycle; 
         FIG. 7  shows a cross-sectional side view of the fastener insertion apparatus of  FIGS. 6A to 6E  but depicting a rivet jam; 
         FIG. 8  shows a cross-sectional side view of the fastener insertion apparatus of  FIGS. 6A to 6E  but depicting a rivet being lifted during retraction of the punch; 
         FIG. 9  is a perspective view of a second embodiment of a fastener insertion apparatus in accordance with the present invention, mounted on a C-frame and loaded with a tape of rivets; 
         FIG. 10  is a perspective view of a lower part of the fastener insertion apparatus of  FIG. 9 ; 
         FIG. 11  shows the same part of the fastener insertion apparatus shown in  FIG. 10  but a body of the fastener feeding device removed for clarity; 
         FIG. 12  is a side cross section of the part of the fastener insertion apparatus shown in  FIG. 10 , along line D-D of  FIG. 13 ; 
         FIG. 13  is a side cross section of the part of the fastener insertion apparatus of  FIG. 10 , along line E-E of  FIG. 12 ; 
         FIG. 14  is a part-sectioned side view of the part of the fastener insertion apparatus of  FIG. 10 , along line F-F of  FIG. 13  and with a fastener feeding device being in a first position; 
         FIG. 15  is a part-sectioned side view of the part of the fastener insertion apparatus shown in  FIG. 14 , the feeding device being in a rotated position and the body having been removed to expose the feeding device; 
         FIG. 16  is a perspective view of the fastener insertion apparatus shown in  FIG. 15 , but with a nose of the apparatus additionally depicted; 
         FIG. 17  is a sectioned side view of a third embodiment of part of a fastener insertion apparatus in accordance with the present invention, the body not being shown for clarity; 
         FIG. 18  is a sectioned side view of a fourth embodiment of a fastener insertion apparatus in accordance with the present invention, the body not being shown to expose the feeding device; 
         FIG. 19  shows the fastener insertion apparatus of  FIG. 18  wherein the feeding device is in a partially rotated state; and 
         FIG. 20  shows the fastener insertion apparatus of  FIG. 18  wherein the feeding device is in a fully rotated state. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1 to 5 , a fastener insertion apparatus  1  comprises a generally cylindrical guide bush  2 , which defines a bore  3  along its central longitudinal axis between upper  4  and lower  5  openings defined at opposite ends. A punch  6  travels reciprocally within the bore  3 , the punch  6  being driven by a suitable actuator (not shown) that is connected to the guide bush  2  at the upper opening  4 . It will be appreciated that the actuator may be any appropriate type including, for example, hydraulic, pneumatic or electrical. A lower end of the guide bush  2  has a pair of depending lateral walls  5 A which define between them a channel that forms part of a path P for the passage of rivets into axial alignment with the bore  3 , the walls  5 A merging at one end of the channel to form an arcuate abutment surface  5 B that closes the channel. The abutment surface  5 B effectively provides a small extension to part of the surface that defines the bore  3 . 
     A generally frustoconical nose  7  is provided beneath the lower end of the guide bush  2 , the nose  7  being spaced from the guide bush  2  so as to provide a clearance between the nose  7  and the guide bush  2  for the feed path P. The nose  7  defines a longitudinal passage  8  in axial alignment with the bore  3  of the guide bush  2 . At the lower end of the passage  8 , the nose  7  defines a generally annular face  9  for contacting a workpiece (not shown) to be fastened. 
     In use, a tape  10  defining holes  10 A for carrying rivets  11  is fed laterally along the path P beneath the guide bush  2  between the walls  5 A by a fastener feeding mechanism that ensures that each rivet  11  in turn is axially aligned with the bore  3  and thereby the path of the punch  6  as will be described in more detail below. 
     The structure of the fastener insertion apparatus  1  is now described in greater detail. The bore  3  is divided into a wide diameter section  12  adjacent to the upper opening  4  and a narrow diameter section  13  adjacent to the lower opening  5 . The guide bush  2  thus defines an internal annular shoulder  14  at the junction between the wide and narrow sections  12 ,  13  of the bore  3 . 
     A cavity  15  running substantially parallel to the bore  3 , extends between the lower end of the guide bush  2  and the wide diameter section  12  of the bore  3 , merging at its upper end with the wide diameter section  12  at an internal aperture  16  which is partially defined by a portion of the shoulder  14  and partially defined by a portion of the wall of the wide section  12 . The cavity  15  is sufficiently radially offset from the bore  3  that the wall of the wide diameter section  12  defines an abutment surface  17  within the cavity  15  adjacent to the internal aperture  16 . A cylindrical actuator  18  is slidably disposed within the cavity  15 . An end cap  19  (held by a pin  19 A depicted in  FIG. 2 ) blocks the lower end of the cavity  15 , and a compressible spring  20  resides within the cavity  15  between the actuator  18  and the end cap  19  so as to bias the actuator  18  against the abutment surface  17 . A portion of the actuator  18  therefore projects into the wide diameter section  12  of the bore  3  through the aperture  16 . The actuator  18  is slidable within the cavity  14  against the bias of the spring  20  to a position in which the actuator  18  no longer projects into the wide diameter section  12  of the bore  3 . 
     Two elongate slots  21  in the guide bush  2  extend along a portion of the length of the cavity  15 , exposing the cavity  15  to the exterior of the guide bush  2 . A hole  22  extends laterally through the actuator  18  so as to receive an actuating pin  23 , the ends of which extend through the slots  21  to the exterior of the guide bush  2 . Therefore, as the actuator  18  reciprocates within the cavity  15 , the ends of the actuating pin  23  slide in the slots  21 . Each end of the actuating pin  23  is mechanically engaged with a respective catcher  24  mounted on the exterior of the guide bush  2 . The catchers  24 , described in detail below, engage the rivets  10  so as to feed them into the path of the punch  8 . The catchers  24  themselves are prevented from passing into the path of the punch by a guard pin  24 A which projects from either side of the guide bush  2  adjacent to the lower end of the bore  3 . 
     The two catchers  24  are in the form of generally longitudinally extending arms with laterally extending tips  25 . The catchers  24  are mounted via pivot pins  26  on radially opposite sides of the exterior surface of the guide bush  2  such that the axis of rotation of the catchers  24  intersects the principal axis of the bore  3 . The end of each catcher  24  remote from the laterally extending tips  25  is located adjacent to one of the elongate slots  21  and defines a slot  27  for mechanical engagement with an end of the actuating pin  23  protruding from the elongate slot  21 . At the opposite end of each catcher  24 , the laterally extending tip  25  extends across the lower end of the guide bush  2  such that the laterally extending tips  25  of the two catchers  24  meet one another in the path P between the guide bush  2  and the nose  7 . The guard pin  24 A extends through the guide bush  2  adjacent to the lower end such that its opposite ends protrude from the radial exterior surface of the guide bush  2 . The catchers  24  rest against these opposite ends of the guard pin  24 A so as to prevent the laterally extending tips  25  from moving into the path of the punch  6 . 
     The fastener feeding mechanism thus comprises the actuator  18 , spring  20 , the actuating pins  23 , the catchers  24  and the pivot pins  26 . The actuator reciprocates within the cavity  15 , carrying the actuating pin  23 , which forces the catchers  24  to pivot about the pivot pins  26  such that the laterally extending tips  25  first sweep (in a first direction) away from the guard pin  24 A before returning back (in an opposite second direction) to their original position against the guard pin  24 A. 
     Each laterally extending tip  25  has a leading edge  28 , which leads when the laterally extending tips  25  move in the first direction, and an opposite trailing edge  29 . The leading edge  28  tapers so as to present an oblique angle to the first direction of movement of the tips  25 . The catchers  24  are sufficiently flexible and resilient that they deflect outwardly from one another under stress so as to create a gap between the tips  25 . When not under stress, the catchers  24  resiliently return to their original shape and the tips  25  once again meet between the guide bush  2  and the nose  7 . It will be appreciated therefore that if the tapered leading edges  28  of the tips  25  abut an obstacle during movement in the first direction, the tips  25  (and thereby the catchers  24 ) will be deflected outwardly so as to pass the obstacle. However, if the trailing edges  29  of the tips  25  abut an obstacle during movement in the second direction, the lack of a taper on these edges  29  means that no such deflection will occur. 
     The holes  10 A in the carrier tape  10  are evenly spaced along its length. Each rivet  11  comprises a shank  30 , which is slightly larger than the holes  10 A in the tape  10  so that the shank is a friction fit with the tape, and a head  31 , which has greater cross-sectional dimensions than the holes  10 A. Thus, each rivet  11  sits in the tape  10  such that the shank  30  passes through a hole  10 A in the tape and the rivet head  31  abuts the tape to prevent the rivet  11  falling out of the tape  10 . 
     In use, as shown in  FIG. 1 , the tape  10  is fed through the fastener insertion apparatus  1  by the feeding mechanism so as to pass along the path P between the lower end of the guide bush  2  and the nose  7 . The head  31  of each rivet passes through the channel portion of the path P defined between the walls  5 A. The catchers  24  are disposed on each side of the tape  10  such that the tips  25  occupy the path P and pass under the tape  10 . However, the dimensions of the rivets  11  in the tape  10  are such that the tips  25  cannot pass under the shanks  30  of the rivets  11 . Rather, the tips  25  extend between successive rivet shanks  30  and may only travel past a rivet  11  when the tips  25  are deflected outwardly by the shanks  30  as described above. Therefore, the rivets  11  may pass the tips  25  in one direction, by abutting the tapered leading edge  28  and deflecting the catchers  24  outwardly, but not the other. This provides a convenient indexing function between the catchers  24  and the tape  10  of rivets  11 . 
     The punch  6  comprises a piston head  32 , which is drivable through the upper opening  4  of the guide bush  2  by an appropriate driving actuator, and punch rod  33 , which extends from the piston head  32 . The arrangement is such that during reciprocation of the punch (in a rivet insertion cycle) the lower end of the punch rod  33  emerges from the lower opening  5  in the guide bush  2  so as to engage a rivet  11  and insert it into a workpiece. The diameter of the piston head  32  corresponds closely to that of the wide section  12  of the bore  3  and the diameter of the punch rod  33  corresponds closely to that of the narrow section  13 . Accordingly, the piston head  32  is guided and supported by the wide section  12  of the guide bush  2 , and while the punch rod  33  is travelling within the narrow section  13 , it is also guided and supported by the guide bush  2 . The extent of possible translation of the punch  6  within the bore  3  is restricted in that the piston head  32  cannot move into the narrow section  13  of the bore  3 . It will be apparent that as the punch  6  is advanced within the bore  3 , the piston head  32  abuts the actuator  18  forcing it to slide against the spring  20  further into the cavity  15 . 
     In operation, as shown in  FIG. 6A , a rivet  11 A is disposed at the end of the bore  3  in the path of the punch  6 . The punch rod  33  advances in the bore  3  and emerges from the lower opening  5  into path P. The punch rod  33  passes through the tape  10 , driving the rivet  11 A out of the hole  10 A in the tape  10  and through the passage  8  in the nose  7 , as shown in  FIG. 6B . As the punch rod  33  drives the rivet  11 A out of the end of the passage  8  and into a workpiece (not shown but against which the annular face  9  of the nose  7  has been positioned), as shown in  FIG. 6C , the piston head  32  engages the actuator  18  and forces it further into the cavity  15 . This causes the catchers  24  to pivot about the pivot pins  26 , sweeping the laterally extending tips  25  of the catchers  24  away from the bore  3  in the first direction as described above. The tape  10  is held fast by the engagement of the punch rod  33  through the hole  10 A in the tape  10 . The tapered leading edges  28  of the tips  25  therefore abut the next-but-one rivet  11 C in the tape  11 , causing the catchers  24  to be deflected outwardly as described above. Once past the next-but-one rivet  11 C, the catchers  24  resiliently return to their original shape, snapping back behind the next-but-one rivet  11 C such that the trailing edges  29  abut the shank  30  of the rivet  11 C. After insertion of the rivet  11 A into the workpiece, as shown in  FIG. 6D , the punch  6  retracts and the piston head  32  releases the actuator  18 . The tape  10  initially remains held in place by virtue of the punch rod  33  occupying the hole  10 A in the carrier tape  10 . In this position, the laterally extending tips  25  cannot pass the next-but-one rivet in a return direction, as described above. The catchers  24  are therefore held away from the bore  3  by the rivet  11 C in the tape  10 . The catchers  24  in turn hold the actuator  18  in place within the cavity  15  against the resilience of the spring  20 . As indicated in  FIG. 6E , the punch rod  33  subsequently retracts sufficiently to release the tape  10 , so that the catchers  24  can pivot back to their original position under the influence of the spring  19  and the actuator  18  which moves back to a position in which it protrudes into the wide section  12  of the bore  3 . The laterally extending tips  25  of the catchers  24  thereby sweep back (in the second direction described above) to their original position pushing the next-but-one rivet  11 C and feeding the tape  10  past the bore  3  until the next rivet  11 B contacts the abutment surface  5 B and is aligned with the bore  3  in the path of the punch  6 . 
     The feeding mechanism is advantageous in that the reciprocation of the punch  6  during each rivet insertion cycle causes the next rivet  11  to be fed into the path of the punch  6 . This is a simple and elegant solution to the problems of powering and timing the feeding of the rivets  11  into the path of the punch  6 . The catchers  24 , actuator  18 , guard pin  24 A and tape  10  are configured such that when the catchers sweep back to their original position the next rivet  11 B is correctly aligned with the path of the punch  6 . It will, however, be appreciated that in the event that the relationship between these components is altered, for example if there is a defect in the tape  10 , the abutment surface  5 B prevents overfeeding of the rivet  11 B past the bore  3 , maintaining the rivet  11 B in the path of the punch  6 . 
     The provision of catchers  24  that move around the guide bush  2  ensures that the punch  6  can be supported during its advance. In particular, the guide bush  2  provides a bore  3  that extends close to the point at which rivets  11  are driven out of the tape  10 . This is advantageous in that the punch  6  is less likely to be damaged in use if it is supported as it extends. Furthermore, rivets  11  which are being fed into the path of the punch  6  are close to the lower end of the guide bush  2 , which more tightly controls the movement of the rivets  11  than if the tape  10  was moving through an open space. 
     Two examples illustrating the advantages of this embodiment of the present invention are described below with reference to  FIGS. 7 and 8 . 
     In operation, two malfunctions that can occur in rivet insertion apparatus are partial feeding, in which a rivet is not fully aligned with the path of the punch, and rivet “lifting”, in which the return motion of the punch causes the punch to “lift” the next rivet dislodging it from its seated position in the tape. 
       FIG. 7  illustrates what happens when a misaligned rivet  11  is driven by the punch  6 . Upon contact of the punch  6  with the rivet  11 , the rivet  11  is forced against the nose  7  at the upper edge of the passage  8  such that it jams. The force applied by the punch  8  against the jammed rivet  11  induces shear stresses in the punch rod  33 . The guidance and support provided by the guide bush along the length of the punch reduces the likelihood that the shear stresses on the punch rod  33  will result in the punch rod  33  bending or breaking under those stresses. Instead, the rivet  11  will simply be sheared by the punch  6 . 
       FIG. 8  shows a rivet  11  being lifted by the punch rod  33  during retraction of the punch  6 . The guide bush  2  provides a bore  3  that extends close to the point at which rivets  11  are driven out of the tape  10 , which means that a surface  34  of the guide bush  2  around the lower opening  5  defines a portion of the path P of the tape  10 . Thus when the punch  6  lifts the rivet  11 , the rivet  11  abuts the surface  34  at the bottom of the channel between walls  5 B adjacent to the lower opening  5  before it has moved sufficiently to be dislodged from its seated position within the tape  10 . This prevents the rivet  11  from being dislodged from the tape  10  and reduces jams and misaligned rivets. 
     Further embodiments of fastener insertion apparatus which engage with the tape rather than the rivets so as to move the tape through the apparatus are now described with reference to  FIGS. 9 to 20 . Features of each further embodiment which correspond to features of the first embodiment have had their reference numbers increased in increments of 100. Features of the embodiments will only be described so as to highlight differences from previous embodiments of the invention. 
       FIG. 9  shows a fastener insertion apparatus  101  in an assembled state and mounted on the upper arm of a C-frame  135  opposite the lower arm of the frame  135 . The lower arm of the frame  135  supports a die  136  over which a workpiece is placed. The apparatus comprises a hydraulic cylinder actuator  138 . In operation, the actuator drives nose  107  of the apparatus in descent towards the die until it comes into contact with the workpiece and may clamp the workpiece with any appropriate clamping force profile. The actuator  138  then drives the punch (hidden in  FIG. 9 ) such that it performs a rivet insertion cycle to insert a rivet  111  into the workpiece. 
     The fastener insertion apparatus  101  comprises a longitudinal guide bush  102 A, beneath which is provided a fastener feed assembly  102 B comprising a body B that supports a number of feed assembly components. The nose  107  is mounted beneath the fastener feed assembly  102 B and defines a passage  108  (see  FIG. 12 ) which is axially aligned with a bore  103  in the feed assembly body B. Referring now to  FIGS. 9 to 16 , a fastener feed path P is defined through the feed assembly  102 B below an inclined bottom edge of internal side wall  105 A of the body B and an internal arcuate abutment surface  105 B is defined below the bore  103  as in the previous embodiment. In this particular embodiment the rivets are fed into the fastener feed assembly  102 B rather than between the guide bush  2  and the nose piece  7 , as in the first embodiment. It will be noted that the body B is relatively slender and only slightly wider than the carrier tape itself. This enables the insertion apparatus to be used in confined areas where access is limited. 
     In use, a carrier tape  110  of rivets  111  (other fasteners may be used) is fed along the feed path P. Two substantially vertical tubes  137  (shown only in  FIG. 9 ) are mounted on the upper arm of the support  135 , one on each side of the fastener insertion apparatus  101 , so as to receive opposite ends of the tape  110 . Thus, in operation, carrier tape  110  with rivets present  111  is drawn through one of the tubes  137  to the apparatus  101 , where it passes laterally along the fastener feed path P. Used tape  110 , from which the rivets have been punched, leaves the fastener feed path P on the other side of the fastener insertion apparatus  101  and passes into the other tube  137 . 
     Whereas in the first embodiment of the invention the fastener feed mechanism  18 ,  20 ,  23 ,  24 ,  26  is arranged in and around the guide bush  2 , in this second embodiment there is provided a separate feed assembly  102 B that is disposed below the guide bush  102 A. An advantage of providing the guide bush and feed assembly as separable components is that servicing and maintenance of the feed assembly may be performed more easily. Moreover, different size feed assemblies may be connected to the guide bush  102 A. It will be appreciated that in many respects the fastener feed assembly  102 B functions in the same way as the fastener feed mechanism of the first embodiment. 
     In particular, it will be appreciated that both the guide bush  102 A and the feed assembly  102 B support and guide the punch  106  as it reciprocates during rivet insertion. The punch  106  reciprocates within a bore  103  defined partly by the guide bush  102 A and partly by the feed assembly  102 B. The guide bush  102 A defines a wide section (not shown) of the bore  103  and the fastener feed assembly  102 B defines a narrower section of the bore, analogous to the upper and lower sections  12 ,  13  of the bore  3  of the first embodiment. The guide bush  102 A is only shown in  FIG. 9 . 
     Referring to  FIGS. 10 to 16 , the punch  106  comprises a piston head  132  and a punch rod  133 , as in the first embodiment. The piston head  132  and punch rod  133  have diameters which respectively correspond to the diameters of the wide section and the narrow section  113  of the bore  103 . Thus, only the punch rod  133  may enter the narrow section  113  of the bore  103  because the piston head  132  is too wide. The rod  133  is thus supported throughout its descent by the part of the body B that defines the narrow section  113  of the bore  103 . The guide bush  102 A is essentially a tubular member which acts as a piston cylinder within which the piston head  132  moves. 
     The fastener feed assembly body B houses a feed mechanism which is engaged by the punch  106  so as to feed rivets  111  into the path P. The body B has a cylindrical upper end defining an annular upper surface  114 , having at its centre the upper opening of the narrow section  113  of the bore  103 . At the exterior edge of the annular surface  114 , a circumferential exterior rim  139  is defined for engagement with the guide bush  102 A. A pair of screws  140  which project upwardly out of opposite sides of the annular surface  114  are used to secure the guide bush  102 A to the feed assembly  102 B. 
     A pair of indexing arms  141  is rotatably mounted to the body B on pivot pins  126  that are received in respective apertures  142  defined in the arms  141 . The indexing arms  141  are mounted in a similar way to the catchers  24  of the first embodiment and move in a similar way, so as to perform a similar function. In contrast with the catchers  24 , however, the indexing arms  141  are mounted inside the body B of the feeder assembly  102 B. Each indexing arm  141  comprises a curved edge  141 A which, in use, is adjacent to an upper edge of the tape  110 . Each curved edge  141 A defines a single tooth  143  having an oblique upstream edge (with respect to the feed path P) and an upright downstream edge. Each tooth  143  is configured to engage a corresponding series of regularly spaced indexing holes  144  defined towards the edge of the tape  110 . When one of the teeth  143  is in an indexing hole  144 , the upright edge of the tooth  143  is engageable with the edge of the indexing hole  144  such that rotation of the indexing arm  141  so as to move the tooth  143  in a downstream direction drives the tape  110  downstream with the tooth  143 . When the indexing arms  141  rotate so as to move the teeth  143  in an upstream direction, however, the oblique upstream edge of the tooth  143  bears against the edge of the indexing hole  144  and lifts the tooth  143  out of the hole  144 , allowing the tooth  143  to slide along an upper surface of the tape  110  to the next hole  144 . Subsequent downstream movement of the tooth  143  (as described above) then causes the tooth  143  to engage with the edge of this next hole  144  and drive the tape  110  in the downstream direction. In this way the indexing arms  141  may be rotated back and forth so as to reliably index the tape  110  through the apparatus  101 . The mechanism by which the indexing arms  141  are actuated is now described. 
     A pair of elongate actuators  145  are slidably mounted side by side above the fastener feed path P. The actuators  145  are connected together at their lower ends by a transverse first load spreading bar  146 . In a retracted position the upper ends of the actuators  145  extend above the annular surface  114  towards the piston head  132 . The first load spreading bar  146  abuts downstream portions of the indexing arms  141  such that, when the actuators  145  are pushed downwards to an extended position, the first load spreading bar  146  forces the indexing arms  141  to rotate about pins  126  such that the teeth  143  move in an upstream direction. A pair of compression springs  147  is provided within a cavity  148  on the upstream side of the feed assembly  102 B. The compression springs  147  are retained within the cavity  148  by a spring retainer  147 A fixed in the upper surface of the fastener feed assembly  102 B. The compression springs  147  are joined together at their lower ends by a second load spreading bar  149  parallel to the first load spreading bar  147 , and which engages upstream portions of the indexing arms  141  when the arms  141  rotate in an upstream direction. Thus, downward movement of the actuators  145  rotates the indexing arms  141  so as to compress the compression springs  147  between the indexing arms  141  and the end cap  147 A. When the indexing arms  141  are no longer being held against the resilience of the compression springs  147 , the springs  147  bias the indexing arms  141  back towards their initial position so that the actuators  145  are pushed back up to their retracted position. The end cap  147 A serves for easy access to the compression springs  147  for servicing and replacement. The actuators  145  are extended and retracted as the punch descends and retracts during a rivet insertion cycle, and this rotates the indexing arms  141  as described above, thus indexing the tape  110  through the apparatus  101 . Adjacent to the actuators  145  on the downstream side of the guide bush  102 , a static stop member  150  is provided in the rotational path of the indexing arms  141  so as to prevent over-rotation of the indexing arms  141  past their initial position upon their return (forward) movement. 
     So as to improve the reliability with which the punch  106  drives rivets  111  from the tape  110 , rotatable tape retainers  151  flank the arms  141  and are supported on the same pivot pins  126  so as to rotate with the indexing arms  141 . The tape retainers  151  have substantially the same profile as the indexing arms  141 , having edges adjacent the edges  141 A which run along edge portions of the upper surface of the tape  110 , but do not define teeth for engagement with the tape  110 . A pair of walls  156  flank the rivet path P on each side and are disposed below the retainers  151  with a small clearance for receipt of the carrier tape  110 . The upper surface of the walls  156  serve to guide the underside of the tape along the path P whilst the tape retainers hold the tape against walls  156 . A lower portion of each wall has a shoulder  153  that serves to support the tape under the retainers  151  and on the downstream side, the tape having ridges  154  at its edges which run against a top edge of the wall  156  so as to maintain the tape in alignment in the fastener feed path P. 
     On the upstream side in order to ensure that the tape  110  is fed into the apparatus  101  at an appropriate angle, the upper surface of the walls  156  are inclined at an appropriate angle. The upper surfaces of the walls  156  each define a recess  156 A (best seen in  FIGS. 14 and 15 ) so as to allow deflection of the tape  110  from its path P upstream of the passage  108  and bore  103 . This allows the tooth  143  of each indexing arm  141  to deflect the tape  110  into the recess  156 A as the indexing arm  141  rotates, allowing the tooth  143  to slide upstream over an upper surface of the tape  110  from one indexing hole  144  to another. Further upstream above the tape a pair of spaced triangular plates  155  may be disposed such that the longest edge of each plate is in contact with a portion of the edge of the tape  110 . The walls  156  are disposed with the body B of the feed assembly  102 B. 
     It will be appreciated that several modifications may be made to the walls  156  so as to improve the reliability of support and/or ease of construction, including the addition of a biasing member (e.g. a resilient pad) within the recess  156 A, which biases the tape  110  towards the indexing arm  141 . Alternatively, the recess  156 A may be omitted and the upstream portion of the wall  156  configured to be moveable relative to the body B in a lateral direction away from the punch axis, such that force applied by the indexing arms  141  and tooth  143  on the carrier tape  110  moves the wall  156  in the lateral direction. 
     As shown in  FIGS. 14 and 15 , the pivot apertures  142  in the indexing arms  141  and rotatable tape retainers  151  may be slightly elongated so as to afford a small clearance relative to the pivot pins  126  that allowing the indexing arms  141  move slightly laterally of the pin as well as to rotate. This feature of the apertures  142  provides a dual advantage. Firstly, when the indexing arms  141  are rotated upstream by the actuators  145  the engagement of the teeth  143  and indexing holes  144  pushes the indexing arms  141 , shifting them away from the tape  110  so as to help the teeth  143  clear the holes  144  in the tape  110 . Secondly, when loading (or unloading) the tape  110  into (or out of) the apparatus  101 , the indexing arm can be manually lifted clear of the feed path P so as to allow more easy insertion (or removal) of the tape  110 . 
     So as to improve the reliability of insertion of rivets  111  by the apparatus  101 , the nose  107  is provided with a plurality of bearings  157  which defined the passage  108 . The bearings  157  are biased inwardly by one or more elastomeric members  158  such that a rivet  111  passing through the passage  108  is prevented from tumbling and is thus correctly inserted into the workpiece. 
     In operation, the fastener insertion apparatus  101  of the second embodiment functions according to the following sequence. A carrier tape  110  of rivets  111  is loaded such that a first rivet  111  is in position in the path of the punch  106  under the bore  103 . A workpiece is positioned over the die  136  in the path of the punch  106  and the nose  107  brought into contact with the workpiece so as to retain it in place and optionally apply a desired clamping force at any stage before, during or after rivet insertion. The punch  106  translates axially downwards and the punch rod  133  strikes the rivet  111 A, driving it out of the tape  110 , down the passage  108  and into the workpiece. The punch rod  133  occupying the hole  110 A in the tape  110  prevents further movement of the tape until the punch  106  retracts and is withdrawn from the tape  110  later in the cycle. 
     During descent of the punch rod  133  to drive the rivet  111 A from the tape  110 , the piston head  132  strikes the actuators  145 , pushing the actuators  145  downwardly. The actuators  145  push the indexing arms  141 , causing them to rotate and move the teeth  143  in an upstream direction, thereby compressing the compression springs  147  as described above. The teeth  143  leave the indexing holes  144  and proceed upstream beyond the next set of holes  144 . At this point, the apparatus  101  is as shown in  FIG. 15  (workpiece and die  136  not shown). The punch  106  then retracts. Although the piston head  132  has withdrawn away from the actuators  145 , the indexing arms  141  and the compression springs  147  are held under tension until the punch rod  133  has released the tape  110 . Once the punch rod  133  is withdrawn from the tape  110 , the mechanism is returned to its original position by the extension of the compression springs  147 . The return movement of the arms  141  causes the teeth  143  to travel downstream and towards the tape  110  engaging the edges of the next holes  144  and driving the tape in a downstream direction. The return movement of the indexing arms  141  is limited by the stop member  150  (as shown in  FIG. 14 ), which is positioned such that, at the point at which the indexing arm  141  stops, the tape  110  has been fed downstream to the point that the next rivet  111 B is in position in the path of the punch  106 . The insertion sequence is then repeated so as to insert this next rivet  111 B into the workpiece. It will be appreciated that, in the event that there is a problem such as an irregularity in the tape  110 , the abutment surface  105 B prevents overfeeding of the rivet  111  past alignment with the punch  106 . 
     In a third embodiment, shown in  FIG. 17 , the fastener insertion apparatus  201  has all of the features of the fastener insertion apparatus of the second embodiment but has a sensor  259  provided adjacent to the position of a rivet  211  in the path of the punch  206 . This sensor detects the presence or absence (or, more generally, the position) of the next rivet  211  on the tape  210 . The sensor  259  is connected to a control system (not shown) such that, in the event that a rivet  211  is not correctly aligned with the punch  206  or is missing, the sensor  259  detects this and the control system stops the apparatus  201 . This helps to prevent damage to the apparatus  201  but most importantly prevents the apparatus  201  from performing a rivet insertion cycle when there is no rivet  211  in the path of the punch  206 , which greatly increases the likelihood that every fastening action of the apparatus  201  results in a rivet  211  being inserted in the expected place into the workpiece. This is advantageous in that there is a greater certainty that individual workpieces have been fastened correctly. 
     A fourth embodiment of a fastener insertion apparatus  301  in accordance with the present invention is shown in  FIGS. 18 to 20 . The principal difference of the fourth embodiment from the second embodiment is that, the indexing arms  341  are smaller, and are rotatably mounted on the rotatable tape guides  351  rather then being directly mounted on to the body B of the feeder assembly  302 B via a pivot pin  26 , 126 , 226  as in previous embodiments. The rotatable tape guides  351  are mounted on primary pivot pins  326  and interact with the actuators  345  and compression springs  147  in functionally the same way that the indexing arms  141  of the second embodiment interact with the actuators  145  and compression springs  147 . Each indexing arm  341  is mounted on one of the rotatable tape guides  351  via a secondary pivot pin  360  defined on the interior surface of the rotatable tape retainer  351  at a location upstream of the pivot pin  326 . For clarity and ease of understanding only one of each of the indexing arms  341  and the tape guides  351  are shown. More specifically, an indexing arm  141  in the foreground is depicted and obscures its counterpart which is immediately behind in the background, whereas only the tape retainer  351  in the background is shown, the foreground retainer  351  being removed so that the indexing arm  141  can be seen. Each indexing arm  341  is rotatably mounted at its first end, and at its opposite end comprises a lower edge (remote from the primary pivot pins  326 ) which defines a tooth  343  and an upper edge opposite the lower edge which defines a bearing surface  361  for contact with a plunger  362  biased by a spring  362 A (only the foreground pair are shown) which is compressed between the plunger and the rotatable tape guide  351 . The tooth  343  defined on each indexing arm  341  is thus biased into the hole  344  in the tape  310  when the rotatable tape guide  351  has not been moved by the actuators  345 . Accordingly, in use, as shown in  FIG. 18 , at an initial position the teeth  343  of the two indexing arms  341  are biased into the indexing holes  344  in the tape in generally the same way that the teeth  143  engage with the holes  144  as described in relation to the second embodiment above. When the punch  332 , 333  descends the head  332  acts on the actuators  345 , as before. However, the actuators  345 , in turn, act on the rotatable guides  351  instead of directly on the indexing arms  341  and the guides  351  are rotated about primary pins  326  as illustrated in  FIG. 19 . This movement serves to lift the secondary pins  230  and indexing arms  341  such that the teeth  343  lift clear of the holes  344 . Further movement of the guides  351  cause the indexing arms  341  to move to the position shown in  FIG. 20  where the teeth  333  are clear of the upper surface of the tape  310 , the springs  362 A force the plunger  362  against the bearing surface  361 , pushing the indexing arms  341  (and thus the teeth  343 ) to return to a retracted position ready for engagement with the next indexing holes  344 . Retraction of the punch releases the guides  351  and allows the teeth  343  to engage in the next set of indexing holes  344  i.e. back to the position shown in  FIG. 18 , but with the tape having indexed forward along the path P. The arrangement is such that each tooth  343  is able to slide over the surface of the carrier tape until it is in register with a hole  344  whereupon it drops in. Moreover, the tooth is fully engaged in the hole  344  when the punch is retracted from the tape 
     It will be appreciated that the indexing arm  341  could take any suitable form. In one alternative embodiment it may take the form of a flat torsional spring with an integral tooth. 
     A further difference in the fourth embodiment is that the elongate tape guide  352  is provided with a rotatably mounted locking member  363  downstream of the path of the punch  306 , beneath the tape  310  and aligned with the indexing holes  344  in one side of the tape  310 . The locking member  363  is biased upwardly against the tape by a compression spring  364 A mounted on a support  365  projecting from the nose  307 . The spring is covered by a cap  364  that bears against the locking member  363 . The locking member  363  defines a tooth  366  on its upper edge for engagement with tape indexing holes  244 . The tooth  366  has an oblique edge on its upstream side and an upstanding edge on its downstream side, such that movement of the tape  310  in the downstream direction pushes the locking member  363  downwards, compressing the spring  364 A. Thus, the indexing holes  344  in the tape  310  index past the locking member  363  as the tape  310  moves downstream. The holes  344  in the tape  310  and the position of the locking member  363  are such that, when a rivet  311  in the tape  310  is in the path of the punch  106 , the tooth  366  of the locking member  363  sits in an indexing hole  344  in the tape  310  and prevents reverse, upstream, movement of the tape  310  by engagement between the upstanding edge of the tooth  366  and the edge of the hole  344 . This is advantageous in that during a punching action, even when the punch rod  333  is not pinning the tape  310  in position, the tape  310  cannot be pulled backwards through the apparatus  301  (for example, by the upstream movement of the indexing arm  341 ). It will be appreciated that the feature of a locking member  363  may advantageously be added to any of the other embodiments. 
     The embodiments of  FIGS. 9 to 20  all have a feed assembly that engages the tape in order to index it along the feed path P. This is beneficial in applications where very short rivets are present in the carrier tape since such rivets do not lend themselves to engagement by elements such as the catcher of the first embodiment. Moreover, the arrangement allows the very last rivet in the tape to be indexed into position automatically. 
     The indexing is performed by an indexing mechanism that disengages and re-engages with the tape or the fasteners as compared to conventional sprocket drives in which the drive is permanently engaged. 
     It will be appreciated that numerous modifications to the described embodiment may be made without departing from the scope of the invention as defined by the appended claims. In particular, it will be apparent that the fastener feed assembly or mechanism comprising a spring biased actuator and a pair of catchers or indexing arms may be replaced by any desirable mechanism provided that actuation occurs as a result of the movement of the punch relative to the guide bush and/or feed assembly. The actuator is provided within the guide bush or feed assembly so as to allow the guide bush or feed assembly to guide and support more of the range of movement of the punch. It will be appreciated that many of the features described in relation to different embodiments might be incorporated, individually or in combination, into a single embodiment of a fastener insertion apparatus in accordance with the present invention. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.