Abstract:
The disclosure provides a cutting tool which may utilize the manner in which a cutting insert is supported therein to better retain the cutting insert. The disclosure also provides a method of assembling the cutting insert in the cutting tool in a manner which may increase the cutting accuracy of the cutting tool.

Description:
BACKGROUND 
   The present disclosure relates to cutting tools having cutting inserts, which are detachably secured in an insert holder. 
   In such cutting tools a cutting insert may abut the insert holder at several abutment regions. These abutment regions apply reaction forces to the cutting insert during a cutting operation. These reaction forces may be utilized to better secure the cutting insert in the insert holder. 
   SUMMARY 
   The following embodiment 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 one aspect, the present invention is directed to a cutting insert having an insert axis (B) with five-fold rotational symmetry. The cutting insert has two identical opposing end surfaces, a cylindrical through bore extending axially along the insert axis (B) and connecting the two identical opposing end surfaces, and a peripheral side surface located between the end surfaces and being divided into five identical segments. Each segment extends between the end surfaces and is located between a pair of adjacent segments; each segment has a cutting section located between a leading wall located on a leading surface and a trailing wall located on a trailing surface; the trailing surface of one segment and the adjacent leading surface of an adjacent segment meet at a corner which forms a radially innermost portion of the peripheral side surface; and the trailing surface of one segment and the adjacent leading surface of an adjacent segment diverge outwardly from the corner in a direction away from the insert axis (B). 
   In another aspect, the present invention is directed to a cutting tool comprising a cutting insert of the sort described above retained in an insert holder. The insert holder has a forward securing portion and a rear body portion. The forward securing portion comprises a base and securing surface, the securing surface including a first support, a second support and a third support which all extend transversely to the base. At least a portion of the first support abuts at least a portion of a trailing wall of a first segment of the cutting insert; at least a portion of the second support abuts at least a portion of a leading wall of a second segment of the cutting insert, the second segment being adjacent to the first segment; at least a portion of the third support abuts at least a portion of trailing wall of a third segment of the cutting insert, the third segment being adjacent to the second segment; and the trailing wall of the third segment of the cutting insert generally faces upwardly. 
   In yet another aspect, there is provided a cutting tool comprising a cutting insert and an insert holder; the cutting insert comprises a first wall, a second wall, a third wall and at least one cutting section; the at least one cutting section comprises a cutting edge located between a rake face and a relief face; the rake face extends rearwardly from the cutting edge and the relief face extends downwardly from the cutting edge and away from the rake face. Therefore, cutting forces acting on the at least one cutting section during a cutting operation are mainly directed towards the rake face in a generally downward direction. 
   The insert holder comprises a forward securing portion and a rear body portion; the securing portion comprises a first support, a second support and a third support; at least a portion of the first support abuts at least a portion of the first wall along a first abutment region, at least a portion of the second support abuts at least a portion of the second wall along a second abutment region and at least a portion of the third support abuts at least a portion of the third wall along a third abutment region, wherein the first and the second abutment regions diverge downwardly and the second and the third abutment regions diverge rearwardly. 
   The first, second and third supports of the insert holder react to the cutting force acting on the at least one cutting section by applying reacting forces to the cutting insert in directions perpendicular to the first, second and third abutment regions respectively. The rearwardly diverging second and third abutment regions therefore apply rearwardly converging reacting forces towards the body portion and away from the at least one cutting section which assist to retain the cutting insert in the insert holder. 
   The above embodiment provides also the advantage that the securing portion is a rigid and non-resilient body which generally does not deform when subjected to forces and, therefore, may provide large reaction forces to the cutting insert at the first second and third abutment regions. 
   In addition to the exemplary aspects and embodiment described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative, rather than restrictive. The disclosure, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which: 
       FIG. 1  shows a perspective view of a cutting tool in accordance with the present disclosure showing a cutting insert secured in an insert holder; 
       FIG. 2  shows a perspective view of a cutting insert; 
       FIG. 3  shows a side view of a cutting insert; 
       FIG. 4  shows a perspective view of an insert holder; 
       FIG. 5  shows a side view of an insert holder; 
       FIG. 6  shows a side view of a cutting tool showing the cutting insert located in the insert holder; and 
       FIG. 7  shows a side view of a cutting tool showing a cutting insert secured in an insert holder. 
   

   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 first drawn to  FIG. 1  showing a right hand cutting tool  10  having a longitudinal tool axis A that defines a forward to rear direction. The cutting tool  10  which may be used in grooving, parting or turning operations has a cutting insert  12  that is located at a forward end of an insert holder  14 . The same cutting insert  12  can be used for both right-handed and left-handed cutting operations, and as such, can be part of the right hand cutting tool  10  ( FIG. 1 ) or a left hand cutting tool (not shown). The description herein will refer to the right hand cutting tool  10  and to the cutting insert  12  and the insert holder  14  as they appear in the right hand cutting tool  10 , but may also relate to a left-handed cutting tool. 
   The cutting insert  12  may be produced by form pressing and/or sintering a hard body which may be made from a carbide powder such as Tungsten Carbide or any other appropriate material such as ceramic materials and the like, as described in the World Directory and Handbook of Hardmetals, Fifth Edition, published by International Carbide Data, which is incorporated by reference herein. However, the cutting insert  12  may also be produced by injection molding. The insert holder  14  may be formed of machined steel or other hard materials. The present disclosure will be described herein with reference to a non-rotary cutting tool; however, it will be clear to the skilled person in the art that it may be applied also to rotary cutting tools in which the cutting insert is detachably secured. It should be noted that directional terms appearing throughout the specification and claims, such as “forward”, “rear”, “up”, “down” and the like, (and derivatives thereof) are for illustrative purposes only, and are not intended to limit the scope of the appended claims. In addition, it is noted that the directional terms “down”, “below” and “lower” (and derivatives thereof) define identical directions. 
   Attention is now drawn to  FIG. 2 . The cutting insert  12  has an insert axis B, two identical opposing end surfaces  16  (only one is seen in  FIG. 2 ) and a peripheral side surface  18 , which is located between the end surfaces  16 . Each end surface  16  has a flat abutment surface  20 , (one is seen in  FIG. 2 ) which is perpendicular to the insert axis B and protrudes axially above the end surface  16 . A cylindrical bore  22  of the cutting insert  12  extends axially along the insert axis B and opens out to each abutment surface  20 . A five-fold rotational symmetry exists in the cutting insert  12  about the insert axis B, and the insert axis B has a positive direction P and an opposing negative direction N which are defined thereabout. 
   Attention is now additionally drawn to  FIG. 3 , which shows a side view of a cutting insert. The side surface  18  is divided into five identical segments  24 ( a - e ). Each segment  24  extends between the end surfaces  16  and is located between a pair of adjacent segments  24  which meet at rounded corners  33  forming the radially inwardmost portions of the peripheral side surface  18 . For example, segment  24   a  is located between segments  24   b  and  24   e . Each segment  24 ( a - e ) has a cutting section  26 ( a - e ) respectively, which is located between a flat leading wall  28 ( a - e ) respectively, and a flat trailing wall  30 ( a - e  respectively). Each leading wall  28 ( a - e ) faces the positive direction P and is located adjacent a positive end of the segment  24 ( a - e ). Each trailing wall  30 ( a - e ) faces the negative direction N and is located adjacent to a negative end of the segment  24 . Each cutting section  26  (see for example,  FIG. 2 ) has a cutting edge  32 , which is located between a rake face  34  and a relief face  36 . Each cutting edge  32  extends between the end surfaces  16 , and the rake face  34  generally faces the positive direction P. Each trailing wall  30  is located on an imaginary trailing surface  31 , and each leading wall  28  is located on an imaginary leading surface  29  (only one imaginary trailing surface  31  and one imaginary leading surface  29  are marked). The leading surface  29  of one segment and the trailing surface  31  of an adjacent segment meet at one of the corners  33 ( a - e ) which are the radially inwardmost portion of the cutting insert&#39;s peripheral surface  18 . From the corner  33 ( a - e ), the trailing and leading surfaces  31 ,  29  of adjacent segments  24  diverge outwardly in a direction away from the insert axis B. 
   Attention is now drawn to  FIGS. 4 and 5  which show a perspective view and a slide view of an insert holder, respectively. The insert holder  14  has a forward holder face  38  and a pair of opposing parallel first and second flank faces  40 ,  42  (only the first flank face  40  can be seen). The first and second flank faces  40 ,  42  extend along the tool axis A, and the holder face  38  is located at a forward end of the insert holder  14 . The insert holder  14  is also divided into a forward securing portion  44  and a rear body portion  46 . The securing portion  44  has a base  48 , a threaded hole  50  and a securing surface  52 . The base  48  is parallel to the first flank faces  40  and  42 , and the hole  50 , which is formed in the securing portion  44 , extends along a holder axis H and opens out to the base  48 . The holder axis H is perpendicular to the tool axis A, and the securing surface  52  extends uprightly from the base  48  along the holder axis H to the first flank face  40 . 
   The base  48  and the securing surface  52  define an insert pocket  54  which opens out to a forward end of the tool holder  14  at the holder face  38  and to the first flank face  40 . The securing portion  44  has a lower bulge  56  and an upper bulge  58 . The lower bulge  56  has a root  60  from which it projects mainly upwardly and slightly forwardly and rearwardly into the insert pocket  54  along a lower support portion  62  of the securing surface  52 . A bulge axis G having an axis direction X, which is defined thereabout, is located in the vicinity of the root  60  of the lower bulge  56 . The bulge axis G is parallel to the holder axis H and located generally below the holder axis H. The upper bulge  58  projects forwardly into the insert pocket  54  along an upper support portion  64  of the securing surface  52 . 
   The securing surface  52  has a forward first support  66  and a rear second support  68  on its lower support portion  62 . The axis direction X of the bulge axis G generally follows a path from the second support  68  along the lower support portion  62  to the first support  66 . A generally downwardly facing third support  70  of the securing surface  52  is located on the upper support portion  64 . The first support  66  is located on an imaginary first surface  67  ( FIG. 5 ), the second support  68  is located on an imaginary second surface  69  ( FIG. 5 ) and the third support  70  is located on an imaginary third surface  71  ( FIG. 5 ). The imaginary first and second surfaces  67 ,  69  diverge downwardly in a direction away from the third support  70 , and the imaginary second and third surfaces  69 ,  71  diverge rearwardly. 
   Attention is now drawn to  FIG. 6  to show an initial assembly position of the cutting tool  10 . The cutting insert  12  is placed in the insert pocket  54  in a way that one of its abutment surfaces  20  (not shown) generally faces the base  48  (which can be seen in  FIGS. 4 and 5 ) of the insert holder  14 , and one of its segments  24  (as seen in  FIG. 3 ) is an operative segment  25  which has an operative cutting section  27  that is located at a forward end of the cutting tool  10 . In the operative cutting section  27  the rake face  34  faces upwardly and extends rearwardly from the cutting edge  32 , and the relief face  36  extends downwardly from the cutting edge  32  and away from the rake face  34 . 
   In the cutting tool  10 , the segment adjacent the operative segment  25  in the positive direction P will be referred to herein as segment S 1 , and the remaining three consecutive segments that follow in the positive direction P will be respectively referred to herein as segments S 2 , S 3  and S 4 . The trailing wall  30  of segment S 2 , the leading wall  28  of segment S 3  and the trailing wall  30  of segment S 4  will be respectively referred to herein as a third wall  76 , a second wall  74  and first wall  72 . 
   The first, second and third walls  72 ,  74 ,  76  of the cutting insert  12 , respectively, face the first, second and third supports  66 ,  68 ,  70  of the insert holder  14  in the initial assembly position of the cutting tool  10 . The first and second supports  66 ,  68  diverge downwardly, and the second and third supports  68 ,  70  diverge rearwardly. In addition, in the initial assembly position of the cutting tool  10 , the hole  50  (not shown) of the insert holder  14  is eccentric in relation to the bore  22  of the cutting insert  12 . The eccentricity is such that the holder axis H is located forwardly and downwardly in relation to the insert axis B. An imaginary axis plane I which includes the holder and the insert axes H, B passes the bulge axis G from a forward direction. That is to say that a portion of the axis plane I is located forwardly in relation to the bulge axis G. 
   Attention is now additionally drawn to  FIG. 7  showing a final assembled position of the cutting tool  10 . To secure the cutting insert  12  in the insert holder  14 , a fastener  78  of the cutting tool  10  is placed through the bore  22  and screwed into the hole  50  (which can be seen in  FIGS. 4 and 5 ). Due to the eccentricity of the bore  22  and the hole  50 , the screwing of the fastener  78  into the hole  50  applies a biasing force F B  to the cutting insert  12  in a direction from the insert axis B through the holder axis H along the axis plane I. The biasing force F B  first urges the cutting insert  12  to an intermediate assembly position in which the cutting insert respectively bears against the first and the second supports of the lower support portion  62  with the first wall  72  and the second wall  74 . Further screwing of the fastener  78  into the hole  50  applies an additional biasing force F B  which further urges the cutting insert forwardly and downwardly and thereby forms a loading moment, which urges the cutting insert  12  to rotate about the bulge axis G in the axis direction X until the third wall  76  of the cutting insert  12  bears against the upper support portion  64 . 
   In the final assembled position of the cutting tool  10 , a portion of the first wall  72  abuts and bears against a portion of the first support  66  along a first abutment region  80 , a portion of the second wall  74  abuts and bears against a portion of the second support  68  along a second abutment region  82 , and a portion of the third wall  76  abuts and bears against a portion of the third support  70  along a third abutment region  84 . The first  66 , second  68  and third  70  supports constitute the only abutment surfaces between the securing surface  52  of the forward securing portion  44  and the peripheral side surface  18  of the cutting insert  12 . 
   Consequently, the insert holder  14  applies to the cutting insert  12  a first reaction force R 1  in a direction perpendicular to the first abutment region  80 , a second reaction force R 2  in a direction perpendicular to the second abutment region  82 , and a third reaction force R 3  in a direction perpendicular to the third abutment region  84 . The second and the third reaction forces R 2 , R 3  converge to a point rear of the insert axis B in a direction towards the body portion  46  and, therefore, assist to retain the cutting insert  12  in the securing portion  44 . 
   It is noted that in the final assembled position of the cutting tool  10 , a gap  59  is formed between the cutting insert  12  and a forward portion of the upper bulge  58 , which is located at a forward end thereof and faces forwardly. 
   During a cutting operation, the operative cutting section  27  is exposed, for example, to a generally downwardly directed cutting force F C  which is included in an imaginary operative plane O, which preferably passes the bulge axis G from a forward direction. That is to say that a portion of the operative plane O is located forwardly in relation to the bulge axis G. Therefore, the cutting force F B  preferably urges the cutting insert  12  to additionally bear against the lower support portion  62  and forms the loading moment, which urges the cutting insert  12  to rotate about the bulge axis G in the axis direction X, and thereby additionally bear against the upper support portion  64 . The cutting force F C  therefore preferably increases, for example, the second and the third reaction forces R 2 , R 3 , which assist to retain the cutting insert  12  in the securing portion  44  during the cutting operation. 
   The biasing force F B  and preferably also the cutting force F C  both contribute to the formation of the first, second and third abutment regions  80 ,  82 ,  84 . In other words, the biasing force F B  biases the cutting insert  12  towards its position in the cutting tool  10  during a cutting operation. Therefore, the biasing force F B  may be referred to as a pre-loading force which stabilizes the position of the operative cutting section  27  in the cutting tool  10  during a cutting operation. This, in turn, increases the cutting accuracy of the cutting tool  10 . 
   In order to resist the cutting force F C  acting of the cutting insert  12  during a cutting operation and provide the first, second and third reaction forces R 1 , R 2 , R 3 , the securing portion  44  may have unitary one-piece construction, which is rigid and non-resilient. This means that the upper bulge  58  and the lower bulge  56  may be an integral and non-resilient part of the securing portion  44 . 
   Although the present embodiment has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the disclosure as hereinafter claimed.