Patent Document

BACKGROUND 
     Chucks, which removably secure articles, such as tools or work-pieces, to machine tools, are well known in the art. Such chucks may employ flexible collets, which may expand or contract radially, to releasably grip the article in the chuck. 
     It has been known that occasionally, the gripped article may slide axially relative to the chuck, especially when relatively large axial cutting forces act on the article. Such axial sliding is undesirable, and may adversely affect the quality of the work-piece, the life of the tool, or both. 
     It is an object of the present disclosure to present an improved chuck. This object is attained with the subject matter in accordance with the claims. 
     SUMMARY 
     The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other advantages or improvements. 
     Also provided is an apparatus comprising a chuck and an article having a common longitudinal axis L, the apparatus further comprising a longitudinally extending through-hole formed in the chuck, designed to accommodate the article; one of the article or the through-hole being formed with a crest, and the other of the article or the through-hole being formed with a trough; the chuck being transferable between chuck releasing and chuck securing positions; wherein in the releasing position, the article is slidable relative to the through-hole of the chuck; and in the securing position, the crest is accommodated in the trough, preventing the article from sliding relative to the chuck. The chuck can further comprise a collet with the through-hole formed in the collet. Optionally a nut may be threadingly secured to a forward end of the chuck, while the nut being in abutment with the collet. 
     There is also provided a method for securing an article in a chuck, comprising the steps of: 
     (i) providing the article with a peripheral envelope, providing the chuck with a through-hole extending therethrough, the through-hole having a through-hole envelope formed therein; providing one of the article or the chuck with a crest formed on either the through-hole or the peripheral envelopes, respectively; and, providing the other of the article or the chuck with a trough formed on either the through-hole or the peripheral envelopes, respectively, with the chuck being transferable between a releasing position and a securing position; 
     (ii) transferring the chuck to the releasing position, whereby the article may slide into and relative to the through-hole; 
     (iii) inserting the article at least partially into the through-hole, so that the crest is positioned opposite the trough; and 
     (iv) transferring the chuck to the securing position, whereby the crest is at least partially accommodated in the trough. 
     Optionally, inserting the article at least partially into the through-hole comprises inserting the article into a through-hole of a collet within the chuck. 
     If desired, transferring the chuck to the securing position can comprise tightening the nut over a forward end of the chuck. Typically, tightening the nut urges the collet rearwardly into a tapered bore of the chuck, thereby contracting the collet in a radially inward direction. 
     In another aspect, the present invention is directed to a cutting tool assembly having a longitudinal axis L defining a front-to-rear direction. The assembly comprises a collet and a shank. The collet has a through-bore extending along said longitudinal axis, an inner surface of the collet comprising a peripheral inner slot and a crest, the crest comprising a collet front, an axially rearwardly facing first slot face, and a front inner surface extending between the collet front and the first slot face, at least a portion of the front inner surface being radially inward of the peripheral inner slot. The shank extends along the longitudinal axis and is releasably secured in said through-bore, the shank comprising a shank peripheral envelope having a peripheral shank slot formed therein, the shank slot defining a trough comprising an axially rearwardly facing first slot side, an opposing axially forwardly facing second slot side, and a slot base extending therebetween. The collet is transferable between a releasing position in which the tool shank is accommodated in, and slidable through, the collet through-bore, with the crest positioned outside of the trough; and a securing position in which the crest is at least partially accommodated in the trough. Optionally, the cutting tool assembly comprises: a chuck with a receiver, which has a bore, and a nut; the collet that is accommodated in the bore of the receiver, whereas the nut is threadingly engaged to the receiver and abuts the collet. If desired, the nut comprises a nut forcing cone which abuts the collet. Typically, the shank peripheral envelope has a plurality of peripheral shank slots formed: therein. Optionally, the plurality of peripheral shank slots are evenly spaced apart along an axial portion of the shank. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the accompanying illustrative figures and drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Exemplary embodiments are demonstrated in the accompanying illustrative figures and drawings. It is intended that the exemplary embodiments and illustrative figures disclosed herein are considered illustrative rather than restrictive. 
       In the accompanying illustrative figures: 
         FIG. 1  is a perspective view of an assembly comprising a chuck and an article secured therein in accordance with an exemplar embodiment; 
         FIG. 2  is a cross-section taken in a plane of a longitudinal axis L of the assembly shown in  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of the assembly shown in  FIG. 1 ; 
         FIG. 4  is a partial section perspective view of a collet of the chuck shown in  FIG. 1 ; 
         FIG. 5  is a partial section perspective view of a nut of the chuck shown in  FIG. 1 . 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements. 
     DETAILED DESCRIPTION 
     Attention is drawn to an assembly  10  and its components, seen in  FIGS. 1 to 5 . A chuck  30  releasably grips an article  32 , which may be, for example, a shank  32  of a rotary cutting tool, such as an end mill  34 . The chuck  30  has a longitudinal axis L defining a front-to-rear direction, and accommodates a collet  36  secured therein by a nut  38  in a front receiver  40  thereof The receiver  40  has a generally cylindrical receiver outer envelope  42  with a receiver male thread  44  formed thereon. The receiver outer envelope  42  extends rearwardly from a receiver front  46  to a flange  48  having a forwardly-facing flange front face  50 . The flange front face  50  extends outwardly away from the receiver outer envelope  42  to a flange peripheral envelope  52 . The flange peripheral envelope  52  extends rearwardly from the flange front face  50  to a rearwardly facing flange rear face  54 . The flange rear face  54  extends inwardly away from the flange peripheral envelope  52  to a mount front  56  of a rear mount  58 . The mount  58  has a mount envelope  60  which extends rearwardly from the mount front  56  coaxially with the longitudinal axis L while tapering inwardly to a mount rear  62 . Thus, the mount  58  is of a generally frustoconical shape, and is adapted to be releasably mountable in a rotary machine tool, such as, for example, a milling machine (not shown). The shape and function of the mount  58  and the flange  48  are not critical and therefore they will not be further discussed herein below. 
     The receiver  40  has a tapered bore  64  having a frustoconical bore surface  65  formed therein. The bore surface  65  extends rearwardly from the front  46  coaxially with the longitudinal axis L while converging inwardly to terminate at a bore rear end  66 , to define a bore cone angle β with the longitudinal axis L. 
     The collet  36  has an inner clamping through-hole  68  defined by a through-hole envelope  70 , as well as an outer collet envelope  72 . Both the through-hole envelope  70  and the collet envelope  72  extend rearwardly from a collet front  74  to a collet rear  76 . The collet  36  has a plurality of alternating first slots  78  and second slots  80  extending radially between, and opening to, the through-hole envelope  70  and the collet envelope  72 . The first slots  78  open to the collet front  74  and extend rearwardly therefrom towards the collet rear  76 . The second slots  80  open to the collet rear  76  and extend forwardly therefrom towards the collet front  74 . The first and second slots  78 ,  80  facilitate radial expansion and contraction of the collet  36 , so that an inner diameter of the through-hole  68  may change to grip a variety of articles having differing diameters. The first slots  78  define a plurality of first fingers  81  therebetween. Each of the first fingers  81  extends rearwardly from the collet front  74  to merge with adjacent first fingers  81  at the collet rear  76 . Similar collets are known, for example, from GB551720, GB565164, GB802769, GB808787, GB827169, GB1048458, GB1379700, GB1080771, GB1394328, GB729051, EP0013645, EP0263982, EP0618030, EP1049555, EP1616647, U.S. Pat. Nos. 5,324,050, 6,746,023, 6,886,835, and JP2004025349, which are incorporated herewith by reference. 
     The collet envelope  72  has a peripheral outer slot  82  formed therein, defining a front outer surface  84  and a rear outer surface  86 . The front outer surface  84  extends rearwardly from the collet front  74  while tapering radially outwardly to a rearwardly facing first slot wall  88 . The front outer surface  84  forms a generally frustoconical shape defining an acute front cone angle γ F  with the longitudinal axis L. The first slot wall  88  extends radially inwardly from the front outer surface  84  to a radially outwardly facing outer slot bottom  90 . The outer slot bottom  90  extends axially rearwardly from the first slot wall  88  to a forwardly facing second slot wall  92 . The second slot wall  92  extends radially outwardly from the outer slot bottom  90  to the rear outer surface  86 . The rear outer surface  86  extends rearwardly from the second slot wall  92  while tapering radially inwardly to the collet rear  76 . The rear outer surface  86  forms a generally frustoconical shape defining an acute rear cone angle γ R  with the longitudinal axis L. Generally, the rear cone angle γ R  is smaller than the front cone angle γ F  (γ R &lt;γ F ). In accordance with an exemplar embodiment, the rear cone angle γ R  is equal to the bore cone angle β. 
     A peripheral inner slot  94  is formed in the through-hole envelope  70 , defining a front inner surface  96  and a rear inner surface  98 . At least a portion of the front inner surface  96  is radially inward of the peripheral inner slot  94 , relative to the longitudinal axis L. The front inner surface  96  extends across the plurality of front fingers  81  and axially rearwardly from the collet front  74  to an axially rearwardly facing first slot face  100 . The first slot face  100  extends radially outwardly from the front inner surface  96  to a radially inwardly facing slot floor  102 . The slot floor  102  extends axially rearwardly from the first slot face  100  to an axially forwardly facing second slot face  104 . The second slot face  104  extends radially inwardly from the slot floor  102  to the rear inner surface  98 . The first slot face  100 , the front inner surface  96 , the collet front  74 , and two adjacent first slots  78  define an inner collet crest  106  on each of the first fingers  81 . 
     The nut  38  has a nut outer envelope  108  extending rearwardly from an axially forwardly facing nut front  110  to an axially rearwardly facing nut rear  112 . A nut inner envelope  114  extends forwardly from the nut rear  112  to the nut front  110 . The nut inner envelope  114  has a female thread  116  formed therein, extending forwardly from the nut rear  112 , to terminate adjacent a nut forcing cone  118 . The nut forcing cone  118  extends forwardly from the female thread  116  to the nut front  110  while tapering inwardly, to form a generally frustoconical shape defining an acute nut cone angle ν with the longitudinal axis L. In accordance with the exemplar embodiment, the nut cone angle ν is equal to the front cone angle γ F . 
     The shank  32  has a shank peripheral envelope  120 , which extends peripherally thereabout, generally parallel to the longitudinal axis L. In the exemplar embodiment, a plurality, and in this instance three, peripheral shank slots  122  are formed in the shank peripheral envelope  120  and may be evenly spaced apart along an axial portion of the shank  32 . However, any number of shank slots  122  may be formed in the shank peripheral envelope  120 . Each shank slot  122  has a rearwardly facing first slot side  124  extending inwardly from the shank peripheral envelope  120  to a slot base  126 . The slot base  126  extends from the first slot side  124  rearwardly to an axially forwardly facing second slot side  128 . The second slot side  128  extends outwardly from the slot base  126  to the shank peripheral envelope  120 . The first slot side  124 , the slot base  126 , and the second slot side  128  define a shank trough  130 . 
     The chuck  30  is assembled by placing the collet  36  with the collet rear  76  adjacent the bore rear end  66 , with the rear outer surface  86  of the collet  36  abutting the bore surface  65 , and with the outer slot  82  and the front outer surface  84  of the collet  36  extending forwardly relative to the receiver front  46 . The nut  38  is placed on the receiver  40  with the female thread  116  of the nut  38  engaging the male thread  44  of the receiver  40 , and is threadingly tightened thereon, until the nut forcing cone  118  abuts the front outer surface  84  of the collet  36 , so that the chuck  30  is brought to a releasing position. In the releasing position, the crest  106  is located outside of the trough  130  so that the shank  32  may be inserted and slid relative to the through-hole  68 . 
     To clamp the article  32  in the chuck  30 , the shank  32  is inserted into the through-hole  68  of the collet  36 , so that the shank peripheral envelope  120  faces the through-hole envelope  70 , and the trough  130  of the shank  32  is set opposite the crest  106  of the collet  36 . The article is clamped in the chuck  30  by bringing the chuck  30  to a clamping position, by further tightening of the nut  38  relative to the releasing position. Since the bore cone angle β of the bore envelope  65 , and the corresponding rear cone angle γ R  of the rear outer surface  86  are smaller than the nut cone angle ν of the forcing cone  118 , and the corresponding front cone angle γ F  of the front outer surface  86 , such further tightening of the nut  38  urges the collet  36  rearwardly in the bore  64 . As the collet  36  is urged rearwardly in the bore  64 , it is wedged by the rearwardly inwardly converging bore envelope  65 . However, the collet  36  is resilient, by virtue of the alternating first and second slots  78 ,  80  thereof. Therefore, as the collet  36  is wedged by the bore envelope  65 , it contracts in a radially inward direction, until the rear inner surface  98  of the through-hole  68  abuts the shank peripheral envelope  120 , bringing the chuck  30  to the clamping position, whereby the shank  32  is clamped in the chuck  30 . 
     To secure the article in the chuck  30 , the chuck  30  is brought to a securing position, by continuing to tighten the nut  38  to the receiver  40 . However, the collet  36  can not be further urged rearwardly in the bore  64  and therefore bends, so that the crests  106  of each of the first fingers  81  are urged into the trough  130  of the shank  32  until the front inner surface  96  abuts the slot base  126 . When the article is secured in the chuck  30 , a force acting axially forwardly thereon will cause the shank  32  to slide axially forwardly relative to the collet  36  to a very small extent, until the second slot side  128  of the shank slot  122  abuts the first slot face  100  of the inner slot  94  of the collet  36 , thereby preventing further forward sliding of the article relative to the shaft. 
     Although the present disclosure has described and illustrated an exemplar embodiment to a certain degree of particularity, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present disclosure is to be limited only by the terms of the appended claims, and alterations and modifications to the exemplar embodiment may possibly be made without departing from the scope of the disclosure as hereinafter claimed. 
     For example, while in the exemplar embodiment, the shank peropheral envelope is cylindrical, it may take on different shapes, such as oval or polygonal, so long as the inner surface of the collet is correspondingly formed. In addition, an article should not be construed as limited to a shank of a cutting tool; the angles β, ν, γ F  and γ R  may be modified to suit other geometrical configurations; the collet does not necessarily have a converging frustoconical rear portion; urging the crests of the collet into the trough of the article is not necessarily accomplished by tightening of a nut or by a conical portion formed thereon; and, a trough may be formed on the collet, while a crest may be formed on the article. Moreover, the crest must not be construed as necessarily being an integral part of the article or the collet. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as included therein.

Technology Category: b