Abstract:
A cutting tool retention mechanism, for example, typically used to retain a tool holder in a tool pocket of a tool changer magazine. A horizontal machine tool apparatus typically contains a plurality of tool pockets attached to a movable tool changer magazine and the mechanism of the present inventions provides an affirmative mechanism for retaining tool holders so that they do not separate from their respective tool pockets unless removal is desired. More particularly, a pair of opposed pivotal fingers each include a latch which can engage with or disengage from the internal groove of a tool holder to perform this function. Spring bias can be provided to encourage this affirmative engagement of the latches with the internal groove.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates to a tool retention mechanism, for example, typically used to retain a cutting tool holder in a tool pocket of a tool changer magazine. A horizontal machine tool apparatus typically contains a plurality of tool pockets attached to a movable tool changer magazine and the mechanism of the present inventions provides an affirmative mechanism for retaining tool holders so that they do not separate from their respective tool pockets unless removal is desired. More particularly, a pair of opposed pivotal fingers each include a latch which can engage with or disengage from the internal groove of a tool holder to perform this function. A biasing force can be provided, for example, by one or more springs, to encourage this affirmative engagement of the latches with the internal groove. 
     2. Brief Description of the Related Art 
     The present invention relates to a cutting tool retention mechanism. This mechanism is designed to be received in a tool pocket and to interface with and retain within the tool pocket a tool holder having an internal groove, such as, for example, a “hohlschaftkegel” (or “HSK”) tool holder. An HSK tool holder is a special form of tool holder configured according to a “DIN” (German engineering) standard and designates short, hollow, tapered tool shanks, wherein the tool shank includes a conical surface and a face formed on an integral tool changer gripping flange thereof, and wherein a machine tool spindle is adapted to grip both the conical surface and the face of the tool holder for positive rotation thereof. Unlike well-known ANSI (American National Standards Institute) standard solid tool holders, which are pulled into a spindle seat by way of a retention stud extending from the generally cylindrical shank thereof, an HSK tool shank has an internal relief, or retaining groove, so that, once inside a machine spindle, internal gripping fingers of the spindle assembly direct outward and rearward forces against the tool shank, to retain it securely. 
     Low-force analogues of spindle gripping arrangements are known for retaining hollow shank tools within tool storage pockets, for example, the employment of spring loaded balls which engage the tool retaining groove. Typically, an external actuating means is employed to release the tool from its tool storage receptacle. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a cutting tool retention mechanism, for example, typically used to retain a tool holder in a tool pocket of a tool changer magazine. A tool changer magazine of a horizontal machining center contains a plurality of tool pockets, each of these tool pockets being adapted to store one tool such that, by the tool changer magazine, a plurality of tools are accessible to the machining center for performing a variety of machining operations, for example, utilizing a rotating spindle. In operation, when the machining center needs to utilize any specific tool for a specific machining operation, the tool changer magazine is moved such that the desired tool in its tool pocket is positioned in an index location where the desired tool can be removed from the pocket and mounted to the spindle. Typically, a machining center will retrieve (and replace) between 5 and 25 cutting tools during a complete machining cycle of a typical workpiece. With each tool change, the entire magazine, and as such, each of the tools held in the pockets thereof, moves. Therefore, because of the frequent, and sometimes jerky, movement of the magazine, it is desirable to provide for affirmative retention of the various tool holders in their respective tool pockets until such time as a specific tool is needed is desirable, and the current invention provides for this retention. 
     All of the embodiments disclosed herein have similar function. In function, a fulcrum supports at least a pair of opposed fingers which function as levers. Springs are used to provide a biasing force such that the bias portions of the opposed fingers are urged toward each other to a physical limit controlled, in one embodiment hereof, by a pair of channels provided in a spring plate. The finger bias portions are on one side of the fulcrum and the finger latch portions are on an opposite side of the fulcrum, such that, in this configuration, opposed latches toward the end of the finger latch portions are spaced a furthest distance from each other. In this configuration, the latches are spaced to engage an internal groove in an HSK tool holder to retain that tool holder in its respective tool pocket. 
     A tool holder can be forced on and off the latches. For example, when pushing a tool holder into the receiving portion of the tool pocket body, the holder will engage the opposed latches. As these latches are spaced a distance apart greater than the smallest diameter of the holder, a force will be applied to the latches overcoming the biasing force, provided by the springs, which is applied toward the opposite end of the fingers on the other side of the fulcrum. When the holder is pushed into the receiving portion a sufficient distance for engagement of the latches with the HSK tool holder internal groove, the springs will force the latches away from each other to affirmatively hold the tool holder. Alternatively, the finger bias portions can have a force applied thereto to overcome the force of the springs to push the finger bias portions away from each other, as permitted by the geometry of the spring plate channel. The separation of the finger bias portions causes the opposed latches on the finger latch portions on the opposite side to the fulcrum to move toward each other. This action can be initiated for insertion or removal of a tool holder and would cause less parts “wear and tear”, but requires additional components to implement. 
     The preferred embodiment of the present invention employs a unitary tool retention mechanism constructed of plastic. In another embodiment, a unitary plastic tool retention mechanism employs a wear-resistant surface in the form of, in one embodiment hereon, shields attached to the finger latch portions. The shields can be of metal or other material with high wear resistance to prolong the life of the mechanism. Alternatively, the mechanism, itself, can be constructed of a wear-resistant material, in which case, the shields are unnecessary. In yet another embodiment, a plurality of components are employed to permit the fingers to be made of a wear-resistant metallic material, such as steel, with the inclusion of the lever pivot by insertion of pins through bores in a retention support and each finger. 
     In still another embodiment hereof, a plurality of pairs of opposed fingers, or an odd number of individual fingers, are spaced equidistantly around the support. In an even further embodiment hereof, the pair of opposed fingers is replaced with a single finger, in which case, the latch distance and the bias distance are defined as the distance of the latch and the bias portion, respectively, to a reference, such as, for example, the central axis of the support. 
     More particularly, in the preferred embodiment hereof, the present invention comprises a retention mechanism having a pair of opposed fingers, each of the fingers extending from a support, each of the fingers having a latch spaced from the support, the support permitting each of the fingers to be pivoted to vary a latch distance between the latches. 
     Further, where each of the fingers has a latch portion including the latch and a bias portion, and where, when at least one of the fingers is pivoted to vary the latch distance, a bias distance between the bias portions varies oppositely thereto, as permitted by the support. That is, where at least one of the fingers is pivoted to decrease the latch distance, the bias distance will increase, although not necessarily inversely thereto. Additionally, each bias portion may have a spring to exert a biasing force on the bias portion, thereby urging the bias portion in a direction toward the bias portion of the other finger. 
     As the retention mechanism is designed to permit the latches to engage an internal groove of a tool holder, the latches preferably have an orientation away from each other, although the latches may have any configuration suitable to engage the internal groove of the tool holder. 
     These and additional objects, features and advantages of the present invention will become apparent to those reasonably skilled in the art from the description which follows, and may be realized by means of the instrumentalities and combinations particularly pointed out therein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings in which like numerals refer to like parts, and wherein: 
     FIG. 1 shows a perspective view of a typical machining center, having a tool storage matrix with a plurality of tool pockets; 
     FIG. 2 shows an exploded perspective view of a tool pocket according to a preferred embodiment of the present invention; 
     FIG. 3 shows a front view of the tool pocket of FIG. 2; 
     FIG. 4 shows a rear view of the tool pocket of FIG. 2; 
     FIG. 5 shows a cross-section view of the tool pocket of FIG. 2, shown along section line  5 — 5  of FIG. 3; 
     FIG. 6 shows a perspective view of a tool retention mechanism of the tool pocket of FIG. 2; 
     FIG. 7 shows a side view of the tool retention mechanism of FIG. 6; 
     FIG. 8 shows an end view of the tool retention mechanism of FIG. 6; 
     FIG. 9 shows a cross-section view of the tool retention mechanism of FIG. 6, shown along section line  9 — 9  of FIG. 8; 
     FIG. 10 shows a cross-section view of the retention mechanism of FIG. 6, shown along section line  10 — 10  of FIG. 8; 
     FIG. 11 shows a perspective view of a tool cage bushing according to the tool pocket of FIG. 2; 
     FIG. 12 shows a side view of the tool cage bushing of FIG. 11; 
     FIG. 13 shows an end view of the tool cage bushing of FIG. 11; 
     FIG. 14 shows a perspective view of a cage spring plate according to the tool pocket of FIG. 2; 
     FIG. 15 is a rendering generally demonstrating how a latch of the tool retention mechanism of FIG. 6 engages an internal retaining groove of an HSK tool holder so that the tool pocket retains the tool holder; 
     FIG. 16 is a rendering generally demonstrating how a latch of the tool retention mechanism of FIG. 6 is pivoted so that an HSK tool holder can be removed from the tool pocket of FIG. 2; 
     FIG. 17 shows an exploded perspective view of a tool pocket according to an alternative embodiment of the present invention; 
     FIG. 18 shows a perspective view of a tool retention mechanism of the tool pocket of FIG. 17; 
     FIG. 19 shows a perspective view of a latch shield for the tool retention mechanism of the tool pocket of FIG. 17; 
     FIG. 20 shows an exploded perspective view of a tool pocket according to another alternative embodiment of the present invention; 
     FIG. 21 shows a perspective view of one finger of the tool retention mechanism of the tool pocket of FIG. 17; 
     FIG. 22 shows a perspective view of a retainer support of the tool pocket of FIG. 17; 
     FIG. 23 shows a perspective view of a tool retention mechanism according to yet another alternative embodiment of the present invention; 
     FIG. 24 shows a perspective view of a tool retention mechanism according to yet another alternative embodiment of the present invention; and, 
     FIG. 25 shows a perspective view of a cage spring plate according to another alternative embodiment of the present invention 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the Figures and, in particular, to FIG. 1 thereof, a machine  10  includes a tool spindle  11  for supporting and driving a variety of tools  12  for performing a variety of machining operations on a workpiece  15 . The tool spindle  15  is adapted to grip for positive rotary motion thereof a tool holder  16 , which itself, securely grips the cutting tool  12  according to known and conventional techniques, such as, by press-fitting a shank portion  12   a  of the cutting tool  12  into a shank opening  16   a  of the tool holder  16 . Because each cutting tool  12  can perform but one type of specific machining operation (e.g., milling, boring, etc.), and because a typical machining cycle of the workpiece  15  requires a number of different machining operations, the machine  10  is equipped with a tool storage matrix or magazine comprising a movable chain  13 , along which are positioned a plurality of tool storage modules or tool pockets  14 , especially adapted for supporting a hollow shank tool holder, such as an HSK tool holder. The present invention is directed to the tool pocket  14  and, more specifically, its capability to affirmatively retain an HSK tool holder  16  therein. 
     Reference numerals are used in the figures for identification, as follows:  2 —portion of tool holder;  4 —internal groove in tool holder;  10 —machine;  11 —tool spindle;  12 —cutting tool;  12   a —tool shank;  13 —movable chain or magazine;  14 —tool pocket;  15 —workpiece;  16 —tool holder;  16   a —tool holder shank opening;  20 —HSK tool pocket body;  22 —front of body;  24 —rear of body;  26 —tool holder receiving portion;  28 —latch opening;  30 —retainer/cage receiving opening;  32 —alignment member channel;  34 —bore;  40 —tool retention mechanism (first embodiment);  42 —center support;  44 —alignment member;  45 —latch;  46 —finger;  48 —latch portion;  50 —latch;  52 —bias portion;  54 —spring support tip;  60 —tool cage bushing;  62 —center support engaging end;  64 —plate engaging end;  66 —base;  68 —opposed curved sides;  70 —channel;  72 —elongated opening;  74 —bore;  76 —spring channel;  80 —cage spring plate;  82 —center opening;  84 —side spring receiving channel;  86 —spring support tip;  88 —bore;  90 —threaded screw or bolt;  92 —washer;  94 —nut;  96 —compression spring;  140 —tool retention mechanism (second embodiment);  146 —finger;  148 —latch portion;  150 —latch;  156 —opening;  157 —“V”-shaped shield;  158 —lips;  240 —metal retainer (third embodiment);  241 —near center bore;  243 —washer;  245 —pin;  246 —finger;  248 —latch portion;  250 —latch;  252 —bias portion;  253 —bore;  254 —pin;  260 —tool cage bushing retainer support;  268 —opposed sides;  269 —bore; and,  270 —channel. 
     With reference to FIGS. 2-16, a tool pocket  20  according to the preferred embodiment hereof is shown. In FIG. 2, the tool pocket body  20  is shown having a front  22  and a rear  24 . With additional reference to FIGS. 3-5, tool pocket body  20  includes a tool holder receiving portion  26 , opposed latch openings  28 , a retainer/cage opening  30 , opposed alignment member channels  32 ; and a pair of throughbores  34 . From the rear  24 , a tool retention mechanism  40  is inserted into opening  30  so that alignment members  44  engage channels  32  and latches  50  are received in latch openings  28 . A tool cage bushing  60 , a cage spring plate  80 , and springs  96  are also inserted from the rear  24 . Then, threaded bolts  90  are inserted through respective bores  34  of body  20 , bores  74  of bushing  60  (FIG.  11 ), and bores  88  of plate  80  (FIG.  14 ), and washers  92  and nuts  94  are inserted onto the ends of bolts  90 , the nuts  94  being tightened to secure the mechanism  40 , bushing  60 , and plate  80  within the tool pocket body  20 . 
     With particular reference to FIGS. 6-10, the preferred tool retention mechanism  40  is shown. Mechanism  40  is preferably made from a molded plastic, although other materials, such as sufficiently flexible metal or composite materials including shape memory and superelastic metal alloys, could be used. FIG. 2 shows the proper orientation of mechanism  40  for insertion into opening  30  in the rear  24  of pocket body  20 . Mechanism  40  includes a center support  42 , to which a pair of opposed fingers  46  and a pair of opposed alignment members  44  are attached or are integrally-formed therewith. From the view of FIG. 8, it is seen that opposed fingers  46  are at the top and bottom, such as at the twelve o-clock and six o-clock positions, respectively, and opposed alignment members  44  are at the left and right, such as at the three o-clock and nine o&#39;clock positions, respectively. In this orientation, fingers  46  and alignment members  44  are spaced equidistantly around the support  42  and alternate with one another. 
     FIG. 10 shows that opposed alignment members  44  can each include a latch  45 . As is best seen in FIG. 5, when tool retention mechanism  40  is inserted into body  20 , latches  45  of opposed alignment members  44  each engage in one of the alignment member channels  32  of body  20  to retain mechanism  40  so that latches  50  are properly positioned, relative to the latch openings  28 . 
     Fingers  46  include a latch portion  48 , shown positioned to the right side of center support  42  in FIG. 7, and a bias portion  52 , shown positioned to the left side of center support  42  in FIG.  7 . Latch  50  is seen toward an end of the latch portion  48  of each finger  46 , distant from center support  42 . Spring support tip  54  is shown positioned toward an end of bias portion  52  of each finger  46 , distant from center support  42 . 
     Center support  42  functions as a fulcrum for the fingers  46 , which work like a pair of opposed levers. As will be explained in greater detail below, with particular reference to FIG. 7, it will be apparent to one of ordinary skill in the art upon reading the within description, that if opposed bias portions  52  are forced toward one another, for example by exerting inwardly-directed biasing forces at spring support tips  54 , the center support  42  will function as a fulcrum for the pivoting of both fingers  46  such that, the opposed latches  50 , in response, will be forced away from each other. In contrast, if opposed bias portions  52  are forced away from one another, with center support  42  providing the fulcrum for the pivoting of both fingers  46 , the opposed latches  50 , in response, will be forced toward one another. 
     With particular reference to FIGS. 11-13, the preferred tool cage bushing  60  is shown. Bushing  60  is preferably made from aluminum, although other materials could be used, for example, any sufficiently rigid plastic, hard rubber or composite material. FIG. 2 shows the proper orientation of bushing  60  for insertion into opening  30  in the rear  24  of pocket body  20 . Bushing  60  includes a center support engaging end  62 , which abuts the center support  42  of the mechanism  40 , and a plate engaging end  64 . A pair of opposed curved sides  68  with channel  70  therebetween extend from base  66 , a distal end defining support engaging end  62 . Base  66  contains an elongated opening  72  therethrough which is sized such that the end portions of the bias portion  52  of fingers  46  can pass therethrough and be operable to and from each other without interference from opening  72 . From the plate engaging end  64  of base  66 , a spring receiving channel  76  extends across the base  66  and is in alignment with opening  72 . Base  66  also contains a pair of throughbores  74 , spaced from the spring receiving channel  76 , which are sized to receive bolts  90  therethrough. 
     With particular reference to FIGS. 14 and 2, the preferred cage spring plate  80  is shown. Plate  80  includes a center opening  82  and a pair of outwardly extending side spring receiving channels  84 , the inner edge of each of which serving as an inner limit or stop for movement of respective bias portions  52 . The outer edges of both channels  84  each include an inwardly extending spring support tip  86 . Plate  80  also contains a pair of throughbores  88  which are sized to receive bolts  90  therethrough. Plate  80  will abut the plate engaging end  64  of bushing  60 . 
     As seen best in FIGS. 2,  4 , and  5 , with the mechanism  40 , bushing  60 , and plate  80  inserted into opening  30  in the rear  24  of pocket body  20 , throughbores  34  (in pocket body  20 ),  74  (in tool cage bushing  60 ), and  88  (in plate  80 ) are in axial alignment with one another and receive bolts  90  from the front  22  of the pocket body  20 , with bolts  90  extending beyond plate  80  toward the rear  24  of the pocket body  20 , and receive washers  92  and nuts  94  from the rear  24  of the pocket body to engage rearwardmost ends of the bolts  90 , thereby securing mechanism  40 , bushing  60 , and plate  80  within the pocket body  20 . The bias portions  52  of each finger  46  extend through elongated opening  72  through one of channels  84  in the plate  80 . With plate  80  abutting end  64 , channels  84  and channel  76  are in alignment with the spring support tip  54  of each finger  46  and also in facing alignment with an opposed spring support tip  86  in the plate  80 . Two compression springs  96  are employed to bias the bias portions  52  of the fingers  46  toward one another, as permitted by the plate channels  84 . The open ends of each spiral spring  96  are received by a pair of cooperating tips  54 ,  86 , the springs  96  being partway received in respective cooperating channels  84 ,  76 . 
     Therefore, springs  96  urge opposed bias portions  52  of fingers  46  toward one another to the inner limit permitted by the inner edges of channels  84  or by the stiffness of the fingers  46  or of the finger  46 -support  42  connection. Channels  84  permit movement of portions  52  away from each other if the force of the springs  96  is opposed. A representation of this is shown in FIGS. 15 and 16. In FIG. 15, bias portion  52  is spaced a distance “d 1 ” from a reference surface, such as, a portion of pocket body  20 , for example, an inner surface of the opening  30 . When the bias portion  52  is in the position shown in FIG. 15, latch  50  of latch portion  48  is received by the internal groove  4  of a portion of an HSK tool holder  2 . Internal groove  4  preferably is a continuous circular groove and, while not shown in this rendering, both of the latches  50  will be received in the groove  4 . The latches  50  are shaped such that, when received by the groove  4 , the tool holder  20  is retained in the tool holder receiving portion  26  of tool pocket body  20 . 
     As shown in FIG. 16, spring  96  may be compressed more than spring  96  of FIG. 15, such as, by applying a release force “F” directed against the biasing force of the spring  96 . As such, when the release force “F” exceeds the biasing force, the bias portion  52  will move to a position whereat the bias portion  52  is spaced a distance “d 2 ” from the inner surface of the opening  30 , the distance d 2  being a distance less than the distance d 1 . In response, the latch  50  will move inwardly as the bias portion  52  and latch portion  48  each pivot about the center support  42 . When the mechanism  40  is in the position whereat the latch  50  no longer engages the groove  4  of the tool holder  2 , the tool holder  2  can be removed from, or inserted into, from the tool holder receiving portion  26  of the tool pocket body  20 . 
     With reference to FIGS. 17-19, one alternative embodiment of the present invention is shown. Tool pocket body  20 , bushing  60 , plate  80 , bolts  90 , washers  92 , nuts  94 , and springs  96  are identical to those employed with the preferred embodiment hereof, and like reference numerals are intended to represent like components. However, in the present embodiment, the tool retention mechanism  140  has been modified. The main portion of mechanism  140  is again preferably made of plastic, as was mechanism  40 . However, to provide for longer wear of the latches  150 , each finger  146  includes a wear-resistant surface, for example, a V-shaped shield  157  which is sized and shaped to cover the wear surfaces of the latch  150 . The shields  157  are made of a metallic or other wear-resistant material, and each shield  157  includes one or more lips  158  which are used to securely each grip the latch  150  of latch portion  148  of one of the fingers  146 . One or more openings  156  may be provided on each latch portion  148  to receive lips  158  to attach the shield  157 . As shield  157  engages groove  4  of tool holder  2 , better component life is provided. Although the wear-resistant surfaces have been described as separate shields  157  which can be affixed to the latches  150  (and removed therefrom for replacement, if necessary, the same effect of which can be provided by constructing the mechanism  140 , or any portion thereof, out of a wear-resistant material, in which case, shields  157  are not necessary. 
     With reference to FIGS. 20-22, another alternative embodiment of the present invention is shown. Tool pocket body  20 , plate  80 , bolts  90 , washers  92 , nuts  94 , and springs  96  are identical to those employed with the preferred embodiment thereof and like reference numerals are intended to represent like parts, however, in the present embodiment, the fingers  246  are constructed of metal or other wear-resistant material. Because steel is the preferred material for the mechanism  240  according to the present embodiment, and because the stiffness of steel is significantly higher than the stiffness of most plastic materials, the entire tool retention mechanism can not be a unitary metal piece for the lever/fulcrum to function as described herein. Therefore, the metal retainers  240  comprise a pair of individual fingers  246 . Each finger  246  includes a throughbore  241  near the finger  246  center. Each finger  246  will pivot about its bore  241 . Each finger  246  includes a latch portion  248  to one side of bore  241  and a bias portion  252  to the opposed side of bore  241 . Toward the end of latch portion  248  away from bore  241  is a latch  250 . Toward the end of bias portion  252  away from bore  241  is a bore  253  which receives a pin  254 . While pin  254  could be formed as a unitary part of finger  246 , the manufacture is easier if pin  254  is a separate element. 
     Each latch  250  will function as latches  50 ,  150  of the previous embodiments and each pin  254  will function as spring support tip  54  of the previous embodiments. To support this function, tool cage bushing  60  is modified to be a retainer support  260  and provide the fulcrum or pivot point for both fingers  246 . Opposed curved sides  268 , with a channel  270  therebetween, include a pair of aligned bores  269 , each pair of bores  269  going through both sides  268 . Fingers  246  are connected to support  260  using washers  243  and pins  245 . A pin  245  passes through one bore  269  in one side  268 , through a washer  243 , through bore  241 , through a washer  243 , and through the aligned bore  269  in the opposed side  268 . This provides for operation as explained with the prior embodiments, springs  96  being contained between pins  254  and respective tips  84 . Fingers  246  can pivot about pins  245  as fingers  46 , 146  pivot about center support  42 , as described in the prior embodiments. 
     With reference to FIG. 23, a tool retention mechanism  340  according to yet another alternative embodiment of the present invention includes many components in common with the tool retention mechanism  40  (FIG. 6) of the preferred embodiment hereof, and like reference numerals are intended to represent like components. However, the tool retention mechanism  340  according to the present embodiment includes more than one pair of opposing fingers  346 , for example, two pair of opposing fingers  346  providing four such fingers  346  spaced equidistantly around the support  342  with alignment members  44  being positioned between first and second pairs of fingers  346 . Of course, tool pocket body  20 , plate  80 , bushing  60 , and the components thereof, must all be modified to receive the mechanism  340  of the present embodiment, however, such modifications will be apparent to one of ordinary skill in the art upon reading the within description. 
     With reference to FIG. 24, a tool retention mechanism according to still another alternative embodiment of the present invention includes many components in common with the tool retention mechanism  40  (FIG. 6) of the preferred embodiment hereof, and like reference numerals are intended to represent like components. However, the tool retention mechanism  340  according to the present embodiment includes only one finger  446 , preferably spaced between the alignment members  44 . Although not depicted in the drawings, any number of fingers, including any odd number of fingers, can be provided spaced around the support, either equidistantly or otherwise, without departing from either the spirit or the scope of the present invention. In any such case, it will be apparent to one of ordinary skill in the art, upon reading the within description, how to modify the tool pocket body  20 , and its associated components, for the purpose of receiving the mechanism. 
     With reference to FIG. 25, a spring plate  580  according to one alternative embodiment of the present invention includes many components in common with the spring plate  80  (FIG. 14) according to the preferred embodiment hereof and like reference numerals are intended to represent like components. However, the spring plate  580  according to the present embodiment includes a continuous channel  584  extending across the plate  580  such that outermost ends thereof are disposed, relative to the outer periphery of the plate  580 , much like respective outermost ends of the channels  84  (FIG. 14) of the plate  80  (FIG. 14) according to the preferred embodiment hereof. However, the spring plate  580  of the present embodiment differs from the spring plate  80  (FIG. 14) of the preferred embodiment integrally-formed stops have been removed therefrom. Inward travel of the bias portions  52  (FIG. 5) would be limited either by a separate component (not shown) known to those of ordinary skill in the art) or by the material properties (i.e., stiffness) of the fingers  46 . 
     While the invention has been illustrated with reference to one or more preferred embodiments hereof, and such preferred embodiments have been described in considerable detail with reference to the drawings, it is not the intention of applicants that the invention be restricted to such detail.