Abstract:
A tool head using a scissor style pair of jaws is described. The jaws may be provided with cutting, pressing, crimping, or other functional surfaces. The tool head includes a linearly positionable member which is engaged with the jaws. Upon linear displacement of the member, the jaws are pivotally displaced.

Description:
FIELD 
     The present subject matter relates to a large angular displacement mechanism for press tools, and particularly for an assembly for cutting large diameter cables. 
     BACKGROUND 
     Tools having scissor jaws are well known. For example, scissor jaw tools for cutting, crimping, and other applications have been used for many years. Such tools typically include a pair of jaws which are pivotally attached to one another. Applying a force on handle ends attached to a pair of jaws to bring the handle ends together, results in a corresponding displacement at the other end, i.e. the working end, of the jaws. As will be appreciated, depending upon the relative location at which the jaws are pivotally attached to each other, significant force multiplication can be produced at the working end of the jaws. 
     Scissor jaws have also been used in conjunction with press tools. Press tools typically utilize a linearly displaceable member such as a hydraulic piston which when extended, engages a scissor jaw assembly. Although relatively large closure forces can be expressed at the working end of the jaws, certain known assemblies are significantly limited in the extent to which the jaws can be opened. For example, for many such assemblies, a maximum opening angle is about 20 degrees. This in turn limits the size of workpieces such as items to be cut or pressed, which can be placed between the jaws. 
     Therefore, in order to cut, press, or perform work upon a relatively large workpiece, an even larger tool head must be provided. Larger tool heads require heavier and more robust members, are heavier and bulkier, and may be too large to use in certain applications in which space is limited. 
     Accordingly, a need exists for a tool head using a scissor jaw and engagement assembly in which the jaws can be opened relatively wide to thereby accept large workpieces. 
     SUMMARY 
     The difficulties and drawbacks associated with previously known tools are overcome in the present tool and related methods. 
     In one aspect, the present subject matter provides a tool head comprising a pair of jaws pivotally attached to one another by a single pivot. Each jaw has a frontwardly directed nose, a generally oppositely directed rear face, and a rearwardly directed cam member. The jaws are positionable between (i) an open position in which the noses of each jaw are spaced apart and (ii) a closed position in which at least a portion of a lateral face region of one jaw is disposed immediately adjacent to and alongside at least a portion of a lateral face region of another jaw. The tool head also comprises a linearly displaceable member having a pair of forwardly directed cam surfaces in contact with the rearwardly directed cam members of the pair of jaws. Upon forward displacement of the member, camming engagement between the cam surfaces and the cam members results in pivotal displacement of the jaws. 
     In another aspect, the present subject matter provides a tool head comprising a first side plate defining a forwardly directed nose and an oppositely directed rear, and a pivot aperture. The tool head also comprises a second side plate spaced from and oriented generally parallel with the first side plate. The second side plate defines a forwardly directed nose and an oppositely directed rear, and a pivot aperture. The tool head also comprises a first jaw member disposed between the first side plate and the second side plate. The first jaw defines a forwardly directed nose, an oppositely directed cam member, a work surface, an inwardly directed lateral face region, and a pivot aperture. The tool head also comprises a second jaw member disposed between the first side plate and the second side plate. The second jaw defines a forwardly directed nose, an oppositely directed cam member, a work surface, an inwardly directed lateral face region, and a pivot aperture. The first side plate, the second side plate, the first jaw member, and the second jaw member are aligned such that the pivot aperture of the first side plate, the pivot aperture of the second side plate, the pivot aperture of the first jaw, and the pivot aperture of the second jaw are defined along a common center axis. The tool head additionally comprises a linearly displaceable member disposed between the first side plate and the second side plate, and rearward of the first jaw and the second jaw. The linearly displaceable member defines at least one forwardly directed cam surface in contact with at least one of the cam member of the first jaw and the cam member of the second jaw. 
     In still another aspect, the present subject matter provides a tool head comprising a linearly displaceable member defining a forwardly directed cam surface. The cam surface includes a first cam surface region defined within at least a portion of a left hand face of the cam surface and a second cam surface region defined within at least a portion of a right hand face of the cam surface. The tool head also comprises a first jaw member having a forwardly directed nose region and a rearwardly directed cam member. The tool head additionally comprises a second jaw member having a forwardly directed nose region and a rearwardly directed cam member. The second jaw is pivotally attached to the right side of the first jaw member. Upon forward displacement of the member, contact between at least one of (i) the rearwardly directed cam member of the first jaw and the first cam surface region, and (ii) the rearwardly directed cam member of the second jaw and the second cam surface region, results in pivotal displacement of at least one of the first jaw and the second jaw. 
     As will be realized, the subject matter described herein is capable of other and different embodiments and its several details are capable of modifications in various respects, all without departing from the claimed subject matter. Accordingly, the drawings and description are to be regarded as illustrative and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a tool head in accordance with the present subject matter. 
         FIG. 2  is a side elevational view of the tool head depicted in  FIG. 1 . 
         FIG. 3  is a top view of the tool head of  FIG. 1 . 
         FIG. 4  is a rear end view of the tool head of  FIG. 1 . 
         FIG. 5  is a front end view of the tool head of  FIG. 1 . 
         FIG. 6  is a front perspective view of the tool head of  FIG. 1  having a side member removed to reveal an interior region of the tool head. 
         FIG. 7  is a side elevational view of the tool head depicted in  FIG. 6 . 
         FIG. 8  is an exploded assembly view of the tool head of  FIG. 1 . 
         FIG. 9  is a graph of force measured at the jaws of a cutting tool in accordance with the present subject matter as a function of tool travel for various wire samples during cutting operations. 
         FIG. 10  is a graph of blade angle as a function of tool travel of a tool head in accordance with the present subject matter. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present subject matter provides a tool and in particular, a tool head assembly for releasable engagement with a press tool. The tool head assembly includes a pair of pivotally attached jaws which include rearwardly directed cam members. The tool head assembly also includes a linearly displaceable slidable member which defines a forwardly directed cam face. The cam face engages or contacts the cam members of the jaws. Thus, upon linear displacement of the slidable member, the jaws are pivotally displaced and typically closed. In certain embodiments of the present subject matter, the jaws are aligned alongside one another such that at least a portion of the first jaw is on the left or right side of the second jaw. This side-by-side orientation of the jaws is maintained during pivotal displacement of the jaws. In such embodiments, the cam face of the forwardly directed slidable member includes a first cam surface region defined within at least a portion of a left hand face of the cam face, and a second cam surface region defined within at least a portion of the right hand face of the cam face. The left hand face and the right hand face of the cam face are divided or separated by a plane bisecting a rearward face of the slidable member and extending along the longitudinal axis of the slidable member. These and other aspects of the present subject matter are described in greater detail herein. 
       FIGS. 1-8  illustrate a tool head  10  in accordance with the present subject matter. The tool head  10  generally comprises a pair of side plates spaced apart such as a first side member  20  and a second side member  30 . Each plate or member defines a frontwardly directed nose or nose regions and a rearwardly directed rear or rear regions. Specifically, the first side member  20  defines nose regions  22  and oppositely directed rear regions  24 . And, the second side member  30  defines nose regions  32  and rear regions  34 . Each side plate may also define an aperture for receiving a pivot pin associated with the jaws, described in greater detail herein. Thus, the first side member  20  defines a pivot aperture  23  and the second side member  30  defines a pivot aperture  33 . A work or access region is accessible along the front of the side plates at which work surfaces of the jaws can be accessed as described in greater detail herein. 
     Specifically, the first side member  20  defines a work region  26  between the nose regions  22 . And, the second side member  30  defines a work region  36  between the nose regions  32 . Each of the plates or side members typically define one or more engagement apertures that can be used when releasably engaging the tool head  10  with a press tool (not shown) as known in the art. Specifically, the first side member  20  defines an engagement aperture  21  and the second side member  30  defines an engagement aperture  31  (best shown in  FIG. 8 ). The side members  20  and  30  are affixed to one another as described in greater detail herein and spaced apart from one another to thereby define a tool head interior region between the side members. The side members  20  and  30  are also typically aligned with one another such that the engagement apertures  21  and  31  are defined along a common center axis. Moreover, it is also generally preferred that each of the side members  20  and  30  have the same or similar shape and size and are oriented such that their corresponding nose regions  22  and  32  are aligned, their rear regions  24  and  34  are aligned, and their work regions  26  and  36  are aligned. However, it will be appreciated that the present subject matter includes a wide array of configurations including nonsymmetrical side members and irregular orientations. 
     The tool head  10  also comprises a pair of jaw members. Specifically, the jaw members can be in the form of a first jaw  40  and a second jaw  50  movably disposed between the pair of side plates or members  20  and  30 . Typically, the jaw members  40  and  50  are pivotally attached to one another and also pivotally attached to the side members  20  and  30 . A pivot pin assembly  55  can be used and extends through the first side plate  20 , the first jaw  40 , the second jaw  50 , and the second side plate  30 , and specifically through corresponding and aligned pivot apertures defined in each of these members. Each jaw member  40 ,  50  typically includes a forwardly directed nose region  42 ,  52 , an oppositely directed cam member, a pivot aperture, and a work surface. In certain versions of the jaws, the jaws are configured such that during closing of the jaws at least a portion of a lateral face region of one jaw is disposed immediately adjacent to or contacts, at least a portion of a lateral face region of another jaw. Referring to  FIG. 5  for example, an inwardly directed lateral face region  46  of the first jaw  40  and an inwardly directed lateral face region  56  of the second jaw  50  are shown. These lateral face regions  46  and  56  are generally directed toward one another and may contact one another. These aspects are described in greater detail herein. 
     The tool head  10  also comprises a pair of guide members affixed to the side plates and a slidable cam member which is slidably received and/or engaged with the guide members. Specifically, a first guide member  60  is disposed between the side members  20  and  30 , and a second guide member  70  is disposed between the side members  20  and  30 . A slidable cam member  80  is positioned between the first and second guide members  60  and  70  and as described in greater detail herein, is linearly moveable along an axis generally extending between the front and the rear of the tool head  10 . As explained in greater detail herein, a forwardly directed cam surface  84  (best shown in  FIG. 6 ) defined along the cam member  80  is in contact and camming engagement with rearwardly directed cam members  44  and  54  (best shown in  FIGS. 6 and 7 ) associated with each of the jaws  40  and  50 , respectively. Thus, upon linear displacement of the cam member  80 ; the jaws  40 ,  50  are pivotally displaced relative to one another, as a result of their pivotal affixment to the side members  20 ,  30  and camming engagement with the cam member  80 . Generally, as the cam member  80  is linearly displaced toward the nose region(s) of the tool head, the jaws  40 ,  50  are pivotally displaced toward one another or “closed.” 
       FIGS. 6 and 7  are views of the tool head  10  having the first side member  20  removed to thereby further reveal the first jaw  40 , the second jaw  50 , the first guide member  60 , the second guide member  70 , the slidable cam member  80 , and other aspects and components as follows. As illustrated in  FIG. 6 , the slidable cam member  80  is disposed between the first and second guide members  60  and  70 . A forwardly directed cam surface  84  defined by the cam member  80  receives and is in contact with rearwardly extending cam members of the jaws such as a first cam member  44  extending from the first jaw  40  and a second cam member extending  54  from the second jaw  50 . Generally, the cam surface  84  of the slidable member  80  is in contact with both cam members  44  and  54  of the jaws  40 ,  50 . However, the present subject matter includes assemblies in which camming engagement occurs between only one of the cam members  44  and  54  and the cam surface  84 . 
     Each of the guide members may optionally include provisions for engaging a jaw member to preclude travel of the jaw member beyond a designated extent or angle. For example, the first guide member  60  includes a first stop assembly  90  which generally comprises a longitudinal member threadedly engaged within the first guide member  60  having a spring assembly directed toward a rear portion of the first jaw  40 . Upon pivotal opening of the jaw  40 , a rearwardly directed region of the jaw  40  eventually contacts the spring assembly of the first stop assembly  90  which thereby precludes further pivotal opening of the jaw  40 . Similarly, a second stop assembly  94  is provided in association with the second guide member  70 . The second stop assembly  94  generally comprises a longitudinal member threadedly engaged within the second guide member  70  having a spring assembly directed toward a rear portion of the second jaw  50 . Upon pivotal opening of the jaw  50 , a rearwardly directed region of the jaw  50  eventually contacts the spring assembly of the second stop assembly  94  which thereby precludes further pivotal opening of the jaw  50 . 
       FIG. 8  is an exploded assembly view of the tool head  10 .  FIG. 8  illustrates orientation and arrangement of the various components relative to one another. Additional aspects are as follows. The slidable member  80  may also include outwardly extending rollers or other low friction members which are slidably received in channels formed in the guide members  60 ,  70 . For example, the slidable member  80  includes a first member  81  which is slidably received in a channel  62  defined in the guide member  60 . Similarly, the slidable member also includes a second member  83  which is slidably received in a channel  72  defined in the guide member  70 . 
     The slidable member  80  also includes one or more cam surfaces for contacting cam members associated with the jaws. Thus, upon linear displacement such as forward displacement of the slidable member  80 , camming engagement between the cam surfaces and the jaw cam members results in pivotal displacement of the jaws. Specifically, the slidable member  80  defines the previously noted forwardly directed surface  84  which can include one or more cam surface regions. That member  80  includes a forwardly extending member  120  that defines an arcuate outer cam surface region  84   a  of the cam surface  84 . The member  120  is positioned along the face of the slidable member  80  so as to be generally aligned with the cam member  44  of the jaw  40 . And, the slidable member  80  also includes another forwardly extending member  130  that defines another arcuate outer cam surface region  84   b  of the cam surface  84 . The member  130  is positioned along the face of the slidable member  80  so as to be generally aligned with the cam member  54  of the jaw  50 . Typically, the forwardly extending members  120 ,  130  are spaced apart from one another and are symmetrically arranged on the slidable member  80  relative to a plane bisecting the member  80  along its longitudinal axis. The tool head  10  also includes springs  82  and  102 . 
     EXAMPLES 
     A collection of large cable samples having sizes of 250 mcm, 300 mcm, 350 mcm, 400 mcm, 500 mcm, 600 mcm, and 750 mcm were subjected to a cutting operation by a tool head having a pair of cutting jaws corresponding to the present subject matter. The tool head was engaged and operated by a hydraulic press tool. During each cutting operation of a sample, the tool force was measured as a function of tool travel. Tool force was determined by measuring the hydraulic pressure on the piston in the press tool by use of a pressure transducer and multiplying the measured pressure by the piston surface area. Tool travel was measured by using a linear variable differential transformer (LVDT) mechanically attached to the ram end of the press tool. 
       FIG. 9  graphically illustrates the measurements of tool force and travel for each of the cables cut. As shown, relatively large cutting forces are exhibited over each of the cutting operations. At the onset of each cutting operation, the jaws of the tool head were opened to receive the relatively large diameter cables. And, in all instances, the cables were completely cut and thus the jaws were closed, within a tool travel of between about 25 to about 27 mm. The jaws were able to pivotally open to a large dimensional opening to thereby accept and cut each of the noted cables. 
       FIG. 10  is a graph of a blade opening angle between the jaws of a tool head according to the present subject matter as a function of tool travel. As evident in the graph, a change of approximately 40 degrees can be realized by a linear tool travel of only about 20 mm, e.g. closing the jaws from an approximately 90 degree configuration to about 50 degrees required a linear tool travel of only about 20 mm. This demonstrates another unique and beneficial property of the present subject matter. 
     Many other benefits will no doubt become apparent from future application and development of this technology. 
     All patents, published applications, and articles noted herein are hereby incorporated by reference in their entirety. 
     As described hereinabove, the present subject matter overcomes many problems associated with previous strategies, systems and/or devices. However, it will be appreciated that various changes in the details, materials and arrangements of components, which have been herein described and illustrated in order to explain the nature of the present subject matter, may be made by those skilled in the art without departing from the principle and scope of the claimed subject matter, as expressed in the appended claims.