Abstract:
An expendable jaw combination for use in connection with a chuck for a lathe, milling machine, or the like to hold work stock. A receiver member is attached to the chuck, and an engagement member is provided in an elongated recess in the receiver member for engaging the stock. The receiver member is preferably constructed of tool material, such as tool steel, while the engagement member may be made of a lower cost material which is easier to work, such as mild steel. After the engagement member is used one or more times, it may be reworked or expended. Locking means are provided for securing the engagement member to the receiver member during use.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to an expendable jaw system for use in connection with lathes, milling machines and other machines which rotatably work stock or work pieces through cutting or other machining operations. 
     In machining operations, lathes, milling machines, or the like are used to cut, grind, or otherwise shape stock or work pieces. These machines generally use a chuck in order to hold the work piece during the machining operations. 
     Chucks typically include three or four jaws which move radially inwardly and outwardly with respect to a central, axial passage provided in the chuck for receiving the raw stock or work piece. Movement of the jaws, sometimes referred to as “master jaws,” may be performed dependently or independently with respect to one another, and the jaws are ordinarily attached to mechanical or hydraulic means and move within channels provided in the chuck. In many instances, these channels have an inverted T-shape for receiving and securing jaw nuts to which top jaws, also referred to as “soft jaws,” are attached. 
     The top jaws may be attached to the master jaws in a variety of ways, but perhaps the most common means is through use of serrated rails or tracks, which are provided on the master jaws and which mate with corresponding serrations on the bottom of the top jaws. The top jaws are positioned radially inwardly or outwardly at the desired location on the master jaw, and are then bolted into place using bolts which engage the jaw nuts to securely hold the top jaw in place. 
     The top, or soft, jaws are positioned on the master jaw such that as the master jaws move inwardly, the extreme ends of the top jaws on the chuck approach one another and are configured to grip the work piece therebetween. Because the ends of the top jaws may themselves require boring or other machining to accommodate and hold the work piece, the top jaws may find limited, or even one-time use for clamping a particular work piece for a production run of such work pieces. Thereafter, the top jaws may no longer be practical for use and are thus subsequently discarded. 
     Because of the provision of serrations on the bottom of such top jaws, their cost of manufacture is significant, and it would be desirable to have top jaws which could be re-used more frequently and/or which are less costly to manufacture. Moreover, it would be desirable to provide a top jaw design which could be readily made from conventional bar stock or other material generally found on-hand in machine shops. 
     Numerous jaw configurations have been patented. For example, U.S. Pat. No. 4,772,034, issued to Brown, discloses a soft jaw system having a lock ring with studs and nuts for adjusting the soft jaws. U.S. Pat. No. 5,236,207, issued to Ramunas, et al, discloses a segmented adjustable top jaw having a slot for allowing variable gripping forces. 
     U.S. Pat. No. 5,735,534, issued to Edwards, discloses a top jaw having a recessed slot for receiving a locking ridge of a mounting base, the mounting base including tracks received by rails of the top jaw. 
     U.S. Pat. No. 4,706,973, issued to Covarrubias, et al, and U.S. Pat. No. 5,542,686, issued to Revuelta, also disclose other chuck-gripping arrangements. Further, U.S. Pat. No. 5,842,704, issued to Gilliam, discloses quick-change jaw inserts for use in connection with a chuck. 
     Apparently, some form of reusable top jaws with expendable soft jaw inserts are offered for sale by H&amp;S Machine Works of Kent, Wash. 
     While the foregoing designs are known, there still exists a need for an expendable jaw system which is versatile in its application and allows for use of readily available, standard materials for manufacture of expendable components. 
     SUMMARY OF THE INVENTION 
     It is, therefore, the principal object of this invention to provide a jaw system having expendable jaw members. 
     It is another object of the present invention to provide a jaw system having a receiver, or pocket, member for attachment to a jaw of a chuck and a jaw insert for receipt in the pocket member. 
     A further object of the present invention is to provide an expendable jaw member which is relatively simple to manufacture from readily available stock materials. 
     Another object of the present invention is to provide jaw members of a variety of configurations for use in gripping work pieces of various shapes. 
     Yet another object of the present invention is to provide a pocket member and jaw insert member, wherein the pocket member can be configured for use on a variety of different chuck configurations. 
     A still further object of the present invention is to provide multiple jaw insert members for use in connection with the pocket member in order to maximize the life and/or length of the jaw insert. 
     A still further object of the present invention is to provide adjustment means for precise adjustment of a jaw insert with respect to the pocket member. 
     A further object of the present invention is to provide a method of gripping a work piece in a chuck system. 
     Generally, the present invention includes a jaw system for use in connection with a chuck for a lathe, milling machine, or the like used to hold stock being worked, and includes a receiver, or pocket, member for attachment to the chuck and an engagement member for engaging the stock. The engagement member is attached to the receiver member, and the receiver member defines a longitudinally-extending recess for receipt of the engagement member. A locking means is provided for selectively locking the engagement member to the receiver member. 
     More specifically, the receiver member is attached to a master jaw of the chuck and, in one preferred embodiment, includes an elongated slot which allows some flexibility in the positioning of the receiver member with respect to the master jaw. The engagement member, or jaw insert, is received within the recess, or pocket, of the pocket member. The jaw insert member is preferably constructed of mild steel and is bar stock of the dimensions of conventional, readily available raw bar stock. The jaw insert member is designed to be sacrificial and expendable. However, because of its relative simplicity and low cost, the benefits are of more expensive, soft jaws are obtained, without the additional cost. 
     The pocket member is preferably constructed of durable material, such as tool steel, and, since the pocket member does not actually grip the work piece during machining, allows for continued reuse. As compared to the jaw insert, the pocket member is of more complex manufacture and cost, but may only require a single purchase, with the expendable portion of the jaw system, namely, the jaw insert, being replaceable at low cost and of relatively simple manufacture. 
     The jaw system of the present invention also allows for precise adjustment, or extension, of the jaw insert from the pocket member through use of unique adjustment screws. An adjustment screw can be provided in the pocket member for adjusting the position of the jaw insert with respect to the pocket member, or, alternately, the adjustment screw could be provided in the insert itself for achieving such adjustment. Additionally, a spacer member is disclosed which can be used in conjunction with an adjustment screw to gain further extension of a jaw insert from a pocket member, for perhaps reaching parts of small diameters, and for prolonging the usable life of the jaw insert. 
     The present invention also discloses a method of holding stock or a work piece during machining using an expendable jaw system as set forth herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing, as well as other objects of the present invention, will be further apparent from the following detailed description of the preferred embodiment of the invention, when taken together with the accompanying specification and the drawings, in which: 
     FIG. 1 is a perspective view of a chuck such as used in a lathe having the expendable jaw system of the present invention installed thereon; 
     FIG. 2 is an exploded view of an expendable jaw system constructed in accordance with the present invention; 
     FIGS. 3A through 3E illustrate various embodiments of a jaw insert, or engagement, member constructed in accordance with the present invention; 
     FIG. 4 illustrates an exploded view of an alternate embodiment of an expendable jaw system constructed in accordance with the present invention; 
     FIG. 5 is and exploded view of another alternate embodiment of an expendable jaw system constructed in accordance with the present invention having a spacer member; 
     FIG. 6 is an exploded view of an expendable jaw system constructed in accordance with the present invention having means for adjusting movement a jaw insert member; 
     FIG. 7 is a sectional view of use of the adjustment means shown in FIG. 6; 
     FIG. 8 is perspective view, with parts cut away, of a further variation of adjustment means for moving the jaw insert member with respect to the pocket member; 
     FIG. 9 is and exploded view of another alternate embodiment of an expendable jaw system constructed in accordance with the present invention having further adjustment means for moving the jaw insert member with respect to the pocket member; and 
     FIG. 10 is an exploded view of a further alternate embodiment of an expendable jaw system constructed in accordance with the present invention showing a pocket member-chuck interface of a differing type. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The accompanying drawings and the description which follows set forth this invention in its preferred embodiment. However, it is contemplated that persons generally familiar with machinery will be able to apply the novel characteristics of the structures illustrated and described herein in other contexts by modification of certain details. Accordingly, the drawings and description are not to be taken as restrictive on the scope of this invention, but are to be understood as broad and general teachings. 
     Referring now to the drawings in detail, wherein like reference characters represent like elements or features throughout the various views, the expendable jaw system of the present invention is indicated generally in the figures by reference character  10 . 
     Turning to FIG. 1, the expendable jaw system  10  of the present invention is illustrated as installed on a conventional chuck, generally C. Chuck C includes an axial passage  12  for receipt of work piece or stock, generally S. Chuck C includes master jaws, generally  18 , which are moved radially inwardly or outwardly with respect to passage  12 , hydraulically, pneumatically, manually or through some other means, in conventional manner. Three master jaws  18  are shown on chuck C and are equi-distantly and radially spaced from one other at approximately 120 degree separations. Master jaws  18  also include conventional serrated tracks  20  to which conventional top jaws are attached. 
     In one preferred embodiment, jaw system  10  includes a receiver, or pocket, member, generally P which is positioned on serrated tracks  20  of master jaws  18 . Pocket members P include base portions, generally  22 , having serrations  24  defined thereon. Also defined in base portion  22  is a longitudinally extending channel  28 , which, as shown in FIG. 2, receives the ridge  30  of a jaw nut, generally J carried within a channel  32  provided in master jaw  18 . Jaw nut J is of a generally inverted T-shaped cross section, having flange portions  34  for receipt in channel  32 . 
     Jaw nut J also includes two threaded bores  38 ,  40  for receipt of bolts  42 ,  44  which are used to lock jaw system  10  in place on a master jaw  18 . 
     Pocket member P includes a recess, or pocket,  48  for receipt of an engagement, or jaw insert, member, generally I. Pocket  48  includes a floor  50  on which insert I rests during use, insert I being fixed within pocket  48  by bolts  42 ,  44  engaging jaw nut J. Side walls  52 ,  54  and end wall  56  of pocket member P form the boundaries of pocket  48 , and floor  50  of pocket  48  generally extends outwardly beyond side walls  52 ,  54 . Note, as shown in FIG. 2, side walls  52 ,  54  include notches  58 , which provide clearance for continued gripping stock S, and in particular small diameter stock S, or stock S having multiple, different diameters or peripheral profiles without such stock contacting pocket member P during use, but instead is gripped by insert I. 
     It should be noted that although only one pocket member P, insert I, and jaw nut combination are being discussed for simplicity purposes, two other such combinations are also provided on the chuck as shown in FIG. 1, one for each master jaw of the chuck. Should a chuck have additional master jaws, then an additional combination would be provided for each master jaw of the chuck. 
     Pocket member P includes an elongated slot  60  defined within recess floor  50  for receipt of bolts  42 ,  44 . The slot  60  allows for jaw insert I to be moved longitudinally within pocket  48  without requiring pocket member P to be moved with respect to a master jaw  18 . Thus, as jaw insert I is used, and becomes shortened during such use, insert I can be moved forward with respect to pocket member P, once pocket member P has been advanced as close to central passage  12  as is allowable, to therefore gain the most use of insert I as practical. 
     Insert I includes countersunk bores,  62 ,  64  for receipt of bolts  42 ,  44 , respectively, and also includes an engagement end, generally  68 , for actually engaging stock S, and a rearward end  70 . It is noted that rearward end  70  includes chamfered portions  72  and that engagement end is “pointed,” or tapered-in, in the embodiments of jaw insert I shown in FIGS. 1,  2 ,  3 C  5 ,  6 , and  8 - 10 . It is to be understood, however, that the engagement end of an insert I can take on a variety of different sizes, shapes, and configurations. FIG. 3A illustrates an insert I having a squared off engagement end  74 . Also in FIG. 3A, the reduction in length of insert I during use is illustrated in phantom lines, with the initial end of insert I being represented by reference number  74 , and the squared off end by reference numeral  76 , which results after use or cutting of insert I to length. 
     Paragraph  3 B illustrates an insert I having a concave engagement end  78 , such concave end having been formed in order to accommodate stock of a certain diameter. 
     FIG. 3C illustrates the pointed, or tapered-in end  79 , and FIG. 3D illustrates an engagement end  68 , which is wider than pocket  48  and has a pointed end  80  to accommodate certain work stock peripheries. FIG. 3E illustrates an insert having an enlarged, outwardly flared engagement end  82 . 
     FIG. 4 illustrates a pocket member P′ having a tongue T for engagement within a different style of master jaw, wherein serrations are not used at the interface between master jaw  18 ′ and pocket member P′. Instead, tongue T extends downwardly through a channel  32 ′ within master jaw  18 ′. Note bores  88  provided in jaws  18 ′ for receipt of bolts  42 ,  44 . 
     FIG. 5 includes an alternate embodiment pocket member  90  having taller side walls  52 ′,  54 ′ and end wall  56 ′ as compared to pocket member P discussed above. Also provided is a spacer member  92  for receipt in pocket  48  of pocket member  90 . Note spacer  92  includes chamfers  94  for receipt within the radiused corners of recess  48  at the juncture of side walls  52 ′,  54 ′ and end wall  56 ′. Instead of a slot  60 , pocket member  90  includes three holes  98  for receipt of bolts  42 ,  44 . Spacer member  92  is held in place by virtue of a flange  100  provided on a base portion  102  thereof which is received by a corresponding notch  104  in insert I. Thus, once spacer member  92  is installed, and insert I bolted into place, spacer  92  is securely retained within pocket member  90 . Although the spacer member  92  could be a variety of different lengths, in one preferred embodiment, the length of spacer member  92  is approximately the length between the center lines of holes  98 , therefore allowing a step increase in the effective length of insert I in a manner to allow bolts  42 ,  48  and corresponding bores  62 ,  64  of insert I to properly align. 
     FIG. 6 illustrates pocket member P having a threaded bore  108  for receipt of an adjustment screw on  10 . Note adjustment screw  110  includes an enlarged portion  112  having an internal drive profile  114  which may be hexagonal in shape for receipt of Allen wrench, or it could be variety of other drive profiles, such as a slot, Phillips head, Torx profile, or the like. At the other end of adjustment screw  110 , such end  116  being threaded, another internal drive profile  118  is provided which, as with drive profile  114 , is shown as being a hexagonal shape, but could be a variety of other drive profiles. 
     FIGS. 7 and 8 show uses of adjustment screw  110 . As shown in FIG. 7, adjustment screw is threadingly engaged with bore  108  of pocket member P such that the enlarged head,  112  bears against the rearward end  70  of insert I. By using a tool to engage a profile  118  of adjustment screw  110 , insert I can be advanced outwardly through turning of adjustment screw  110 . This, of course, assumes that bolts  42 ,  44  have not yet been tightened down. Once insert I has been properly positioned, using adjustment screw  110 , bolts  42 ,  44  can then be tightened to lock insert I into place. Accordingly, use of adjustment screw  110  allows for fine adjustment of insert I. 
     In FIG. 8, adjustment screw  110  is illustrated as bearing upon spacer member  92 , instead of directly upon insert I. As discussed above, through use of spacer member  92 , the effective length of insert I can be increased, and use of adjustment screw  110  allows for fine adjustment of insert I. 
     FIG. 9 illustrates use of a spacer, or adjustment, block  92 ′ having a threaded bore  120  for receipt of an adjustment screw  110 ′. FIG. 9 also illustrates an adjustment screw  110 , either of which could be used to urge spacer block  92  and, in turn, insert I outwardly. However, ordinarily, only adjustment screw  110 ′ would be used at a given time. Assuming adjustment screw  110 ′ is being used, a tool such as an Allen wrench, would be inserted in bore  108  of pocket member P in order to engage with drive profile  114  of the head portion  112  of adjustment screw  110 ′. Note adjustment block  92 ′ is shorter in length than spacer member  92 , thereby allowing for adjustment of insert I by an increment smaller than the length of spacer  92  and, accordingly, an increased range of adjustment of insert I through use of adjustment screws  110  or  110 ′. Use of adjustment member  92 ′ and adjustment screw  110 ′ allows for the length of adjustment screw  110 ′ to be minimized while allowing maximum use of length of screw  110 ′ in moving insert I outwardly. 
     FIG. 10 illustrates pocket member P having on its base portion transversely-extending lips  124  for receipt in transverse slots  126  of master jaw  18 ″. Bores  128 ,  130  are threaded for receipt of bolts  42 ,  44 , respectively. Master jaw  18 ″ also includes a tongue  132  for receipt within channel  28  of pocket member P, with bolts  42 ,  48  being used to lock insert I and pocket member P to master jaw  18 ″. 
     In use of jaw system  10  for a typical situation of machining stock or a work piece, pocket members P are placed on master jaws  18  of a chuck C, with inserts being carried within the pocket  48  of each pocket member P. Inserts I are moved towards one another to engage the work piece or for being bored or otherwise shaped themselves for engaging a work piece of a particular diameter or profile. Once the inserts I are properly positioned for engaging the work piece, either manually or through use of spacer members  92  and adjustment screw  110 , the inserts I and pocket members P are locked into position with bolts  42 ,  44  onto jaws  18 . Inserts I are then used to grip the work piece as the work piece is machined. After such machining, the inserts I can potentially be re-used, with any necessary reshaping of the inserts I being made, or simply discarded if no longer practical to reuse. 
     Although chuck C has been shown in use with stock S carried within its central passage  12 , there are occasions where a work piece would be gripped from the inside of the work piece, such as would be the case for gears having flanges. During machining of such parts, it may be necessary to grip the inside portions of the flanges such that the part can be rotated in a lathe for truing the outside of the flanges. The jaw system  10  of the present invention can also be used in those situations, with the pocket members simply being rotating 180° from what is shown in the drawings and reattached to the jaws of the chuck. In this manner, the inserts I would be adjusted to extend radially outwardly as necessary for gripping the work piece. 
     Spacer members  92 ,  92 ′ allow for increased versatility of gripping a work piece with a chuck. For example, in machining a cam, which has eccentric, i.e., spaced apart centers of revolution, the jaw system  10  could be used to bore an insert I on a first center, and then a spacer member  92  or  92 ′ could be used as necessary to reach the eccentric position in order to bore the insert I of the jaw system  10  on the second center. 
     Another advantage of the jaw system  10  of the present invention is that it allows for independent boring of jaw inserts on one machine for use on another machine or another portion of the same machine. For example, system  10  allows for boring or sizing of jaws on one machine, such as on a lathe, and then allows for subsequent removal of the jaws and moving of the jaws to another machine, or another portion of the same lathe machine with any needed adjustment being made using adjustment screws  110  or  110 ′ and/or spacer blocks  92  or  92 ′, as necessary. 
     Further, jaw system  10  should allow for a reduction in machining costs. Because inserts  10  are less expensive than conventional jaws, they can be more realistically sacrificed for use on smaller diameter stock or stock having unique peripheral profiles. 
     While preferred embodiments of the invention have been described using specific terms, such description is for present illustrative purposes only, and it is to be understood that changes and variations to such embodiments, including but not limited to the substitution of equivalent features or parts, and the reversal of various features thereof, may be practiced by those of ordinary skill in the art without departing from the spirit or scope of the following claims.