Abstract:
Provided is an insert that has good positioning precision and sufficient rigidity. Said insert is rod-shaped and has: a shank part; cutting blades formed on both sides of the shank part; and raised surfaces that are positioned between the cutting blades and the shank part and bulge such that parts farther away from the cutting blades are progressively closer to the outer surface of the shank part. In a side view, the rake face of the cutting blade on one side and the raised surface on the other side are disposed in the same direction with respect to the axis of rotation of the shank part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a national phase of the International Patent Application PCT/JP2010/060659 filed on Jun. 23, 2010 that claims the priority from the Japanese patent applications 2009-154341 filed on Jun. 29, 2009 and 2009-177724 filed on Jul. 30, 2009. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to insert, holder and cutting tool using the same. 
     Conventionally, those manufactured by inserting, into a holder, a substantially rod-shaped insert (hereinafter simply referred to as an insert) that has a cutting edge on both ends thereof, and is clamped by tightening with a bolt, are known as a cutting tool used for grooving an inner diameter or threading. 
     Patent Document 1, for example, discloses a cutting tool manufactured by inserting, into a hole of a holder, one end of a substantially rod-shaped insert having a cutting edge on both ends thereof. Also, disclosed is that the position in the axial direction of the insert is determined by abutting contacting with a flank surface on one end of the insert against an adjustment member within the holder. 
     However, although the position in the axial direction is determined with relatively good accuracy, index accuracy regarding the center height of the insert is poor. That is, for determining the position of the center height, a plane (a plane portion on the upper surface side) perpendicular to the center height direction is provided on the outer peripheral surface of the upper side of the insert to press and, for example, clamp the plane portion on the upper surface side by screwing. Therefore, when pressed by screwing, sometimes the insert ends up rotating slightly; hence, experienced training is required to constantly maintain the center height when repeatedly securing the insert. As a result, variations in the accuracy of repetitive mounting become significant. Furthermore, because the plane portion on the upper surface side is provided, the cross-section area of the insert becomes small, resulting in a problem of deterioration in its rigidity.
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-71204   

     SUMMARY OF THE INVENTION 
     The objective of the present invention is to provide an insert with better accuracy for adjustment while having sufficient rigidity, a holder for the insert, and a cutting tool comprising the insert and the holder. 
     According to one aspect of the invention, the insert has a rod shape and comprises a shank part, a cutting edge formed respectively on both sides of the shank part, and a rising surface located between the cutting edge and the shank part protruding so as to approach the outer peripheral surface of the shank part as it moves away from the cutting edge, wherein, when viewed from a side surface, a rake surface of the cutting edge on one side and the rising surface on the other side thereof are arranged in the same direction with respect to the rotational axis of the shank part. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In an embodiment, a chip pocket is formed between the rising surface and the cutting edge provided on the same side when viewed from the shank part. 
     In an embodiment, the rising surface is flat in a cross-sectional view perpendicular to the longitudinal direction and the end part thereof connected to the chip pocket is concave-shaped when viewed from the side surface parallel to the longitudinal direction. 
     In an embodiment, in a cross-sectional view perpendicular to the longitudinal direction, a flat part is formed on the outer periphery of the shank part, on a side opposite to the position at which the rising surface is formed. 
     A holder of the present invention comprises an insertion hole at the tip end part for inserting and securing the insert, with an adjustment member in abutting contact with the rising surface of the insert provided in the insertion hole thereof. 
     In an embodiment, an adjustment member mounting-hole penetrating from the outer peripheral surface to the insertion hole is provided and a rod-shaped adjustment member is inserted into the adjustment member mounting-hole. 
     In an embodiment, a screw hole penetrating from the outer peripheral surface into the insertion hole is formed on the tip end side relative to the adjustment member, and a screw member is fit into the screw hole to press and clamp the outer peripheral surface of the shank part of the insert by the tip end of the screw member. 
     In an embodiment, after the screw member is fit into the screw hole, when the tip end of the screw member is in abutting contact with the outer peripheral surface of the shank part of the insert, the abutting contact part of the screw is provided off-set from a rotational axis of the pressing member so as to pull the insert into the inserting part following the rotation of the pressing member. 
     In an embodiment, a mounting support member located on the tip end side relative to the adjustment member and penetrating from the outer peripheral surface into the insertion hole is provided in the insertion hole, and prevents the cutting edge on the side inserted into the insertion hole from contacting the adjustment member when the insert is inserted into the insertion hole. 
     In an embodiment, a through-hole penetrating from the outer peripheral surface into the insertion hole is provided and the rod-shaped mounting support member is inserted into the through-hole. 
     In a cutting tool of the present invention, the above insert is inserted into an insertion hole that is formed at a tip end of a holder and clamps the rising surface in abutting contact with the adjustment member provided with the holder. 
     According to an insert of the present invention, in case of using a cutting edge on one side, a rising surface on the cutting edge side on the other side arranged in the same direction as the one cutting edge with respect to the rotational axis of the shank part functions as a surface for limiting the center height direction and the longitudinal direction and is capable of constraining rotations of the insert when securing the insert, while having good index precision in determining the position of the center height. Furthermore, the cross-sectional area may be largely kept, providing sufficient rigidity in comparison to conventional shapes in which a plane part is provided on the upper surface side of a shank part. 
     Because the rake surface of the cutting edge on one end and the rising surface of the other end are arranged so as to face substantially the same direction, even if the cutting edge is pressed by a work material during a cutting process and a force lifting up the other end of the insert is applied, the suppressing part of the rising surface on the other end constrains the insert from being lifted so as to be firmly clamped, allowing vibration of the insert during cutting to be constrained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view schematically illustrating a whole insert according to an embodiment of the present invention. 
         FIGS. 2  ( a ), ( b ) and ( c ) are an upper plan view, a side view, and an end surface view of the insert shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view taking from the M-M line shown in  FIG. 2  ( a ). 
         FIG. 4  is a perspective view schematically illustrating a whole cutting tool, with using the insert shown in  FIG. 1 , according to an embodiment of the present invention. 
         FIGS. 5(   a ), ( b ) and ( c ) are an upper plan view, a side view and an end surface view of the cutting tool shown in  FIG. 4 , respectively. 
         FIG. 6  is a cross-sectional view taking from the N-N line shown in  FIG. 5  ( a ). 
         FIG. 7  is a side view of the insert shown in  FIG. 2(   b ) according to another embodiment. 
         FIG. 8  is an enlarged view of the essential parts of the cutting tool, with using the insert shown in  FIG. 1 , according to another embodiment of the present invention. 
         FIG. 9  is an illustration showing a structure of a mounting support member to be attached to a cutting tool according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Hereinafter, using  FIGS. 1 to 6 , a cutting tool T for the machining of an inner diameter used by mounting, to a holder  10 , an insert which is an embodiment of the present invention, is described.  FIG. 1  is a schematic perspective view illustrating the insert  1 ,  FIG. 2  is (a) an upper plan view of the insert  1  shown in  FIG. 1  viewed from the X-direction (upper surface direction), (b) a side view viewed from the Y-direction (side surface direction), and (c) an end surface view viewed from the Z-direction (tip end direction), and  FIG. 3  is a cross-sectional view taking from an M-M cross-section shown in  FIG. 2  ( a ). Furthermore,  FIG. 4  is an a perspective view schematically illustrating a whole cutting tool cutting tool T with the insert  1  mounted on the holder  10 ,  FIG. 5  is a upper plan view looking at the cutting tool T of  FIG. 4  from (a) the X-direction (upper surface direction), (b) a side surface view viewed from the Y-direction (side surface direction), and (c) an end surface view viewed from the X-direction (tip end direction), and  FIG. 6  is a cross-sectional view taking from the N-N line shown in  FIG. 5  ( b ). 
     As shown in  FIG. 1 , the insert  1  is composed of a rod-shaped body and includes cutting edges  2  ( 2 A,  2 B) respectively located on both ends thereof and a shank part  3  located between these cutting edges  2 . The rod-shaped body indicates a shape that is substantially cylindrical, a substantially polygonal shape, or a shape combining these as a standard shape. In the present embodiment, the shank part  3  is substantially circular at the M-M cross-section longitudinally in the center part. 
     The insert  1  is an insert bar for which two corners can be used and two cutting edges are present. In the present embodiment, as shown in  FIG. 2(   a ), both cutting edges  2 A and  2 B are formed protruding toward the side with respect to a part (a chip pocket  8  as well as a rising surface  6  in  FIG. 2(   a )) capable of inserting into the inner diameter of a work material of the insert  1 . This function is also effective with a rod shaped-insert in the present invention that does not have a rising surface  6  but has a cutting edge on both ends thereof. 
     Between the cutting edge  2  and the shank part  3 , a rising surface  6  ( 1 A,  6 B) is formed respectively. The rising surface  6  protrudes so as to approach the outer peripheral surface  4   a  as it moves away from the cutting edge  2  toward the shank part  3 . In case of using the cutting edge  2 B at the tip end on the side opposite the rising surface  6   a , that is, in case of inserting the cutting edge  2 A into an insertion hole  11  of the holder  10 , the rising surface  6  functions as a restraining part to limit the center height direction, the longitudinal direction, and the rotating direction by being caused to abut against an adjustment member  12  formed in the insertion hole  11  of the holder  10 . The index precision in determining the center height position is also good. The cross-section area may be largely maintained, providing sufficient rigidity in comparison to conventional shapes in which a plane part is provided on the upper surface side of a shank part. 
     The shape of the rising surface  6  is not particularly limited. The cross-sectional view perpendicular to the longitudinal direction of the insert  1  is preferably flat, but the side-surface view parallel to the longitudinal direction may also be a flat surface, a concave surface (particularly, a concave-curved surface), or a combination of these surfaces. In terms of preventing the insert  1  from breaking due to stress applied during cutting, it is preferable to have a smooth connection without any bending points between the chip pocket  8  to be described later and the rising surface  6  when viewing a side surface of the insert parallel to the longitudinal direction of the rising surface. In view of this, the part of the rising surface  6  connected to the chip pocket  8  preferably has a concave surface. 
     In the present embodiment, as shown in  FIG. 2(   b ), the chip pocket  8  is formed between the rising surface  6  and the cutting edge  2  and temporarily retains chips generated by the cutting edge  2  at the chip pocket  8  so as to gradually discharge the chips from a space between the internal wall surface of a work material and the insert  1 , preventing the chips from clogging around the cutting edge  2  and hampering the cutting, even if a large amount of chips are momentarily generated. 
     According to the configuration of  FIG. 1 , the rake face  7  of one end of the cutting edge  2 A and the rising surface  6 B on the other end are arranged in the same direction to the rotational axis of the shank part  3 , and the rising surface  6 A as well as  6 B are also arranged in the same direction with respect to the rotational axis. According to such a configuration, even if a force is generated so as to lift the other end of the insert  1  when the cutting edge  2  is pressed by a work material during a cutting process, the other rising surface  6 B works so as to suppress the lifting of the insert and is capable of firmly securing the insert, allowing vibrations of the insert  1  to be constrained during cutting. Because a position of the insert is determined by forcing the rising surface  6 B directly be in abutting contact with the adjustment member  12 , the mounting accuracy of the cutting edge  2  is high and also screws do not become loose in comparison to a screwing method by providing a plane part on the side surface of a shank part and making the screw in abutting contact with the plane part against screwing members from the outer periphery of a holder. 
     As shown in  FIG. 3 , a flat part  5  is formed on the outer periphery of the shank part  3 , on the side opposite to the rising surface  6  in a cross-sectional view perpendicular to the longitudinal direction. The flat part  5  is formed as a notch to avoid a mounting support member  19  so that the insert  1  may be inserted into the insertion hole  11  of the holder  10  in case of forming the mounting support member  19  which is described later. This configuration has a function that makes it possible to reliably mount the insert  1  with confidence without accidentally damaging the cutting edge  2  of the insert  1  prior to a cutting process. Because the rising surfaces  6 A and the  6 B are facing substantially the same direction according to the configuration shown in  FIG. 2 , one flat part  5  can support the mounting of both cutting edges  2 A and  2 B, making it is possible, for that part, to keep the cross-sectional area of the shank part  3  largely such that the shank part  3  is sufficiently rigid. 
     On one hand, regarding the holder  10 , as shown in  FIG. 4 , an insertion hole  11  for inserting the insert  1  is provided at the tip end part of the holder  10  and an adjustment member  12  in abutting contact with the rising surface  6  of the insert  1  is provided within the insertion hole  11 . In  FIG. 4 , a large number of adjustment member mounting-holes  13  for inserting the rod-shaped adjustment member  12  are provided on the side surface of the holder  10 . The rod-shaped adjustment member  12  is inserted into one of mounting holes  13  of the adjustment member mounting-holes  13 . A large number of adjustment member mounting-holes  13  are provided such that this configuration becomes capable of appropriately adjusting the amount of protrusion of the insert  1 . 
     The adjustment member  12 , for example, is not particularly limited as long as it is in abutting contact with the rising surface  6  of the insert  1  such as pins or screws. If the adjustment member is a pin, it is easy to insert or pull out, making it possible to easily change the amount of protrusion of the insert; hence, a pin is used as adjustment member  12  in the present embodiment. Furthermore, the adjustment member  12  is provided such that the axis of the adjustment member  12  becomes perpendicular with respect to the longitudinal direction of the insertion hole  11 . 
     Regarding the securing method of the adjustment member  12 , the following may be used: a securing method by pinching both ends of a cylindrically-shaped pin with screws, a method by providing a thread for an end part on one side of a cylindrically-shaped pin and fitting the thread part to the thread part also provided for the holder  10 , a securing method by forming one end of a cylindrically-shaped pin into a tapered shape with an enlarged diameter and making the tapered part contact with a predetermined location of the adjustment member mounting-holes  13 , a method of securing a cylindrically-shaped pin with an adhesive, and a securing method by fastening a screw member from the side surface of a cylindrically-shaped pin. In  FIG. 9 , which is an embodiment to be described later, a method by fastening a screw member in from the side surface of a cylindrically-shaped pin is employed. 
     The position within the insertion hole of the adjustment member  12  may be appropriately adjusted according to the insertion angle of the rising surface of the insert  1 . The rising surface  6  of the insert  1  preferably comes into linear contact with the adjustment member  12 , and if the adjustment member  12  is a cylindrically-shaped pin, for example, it is preferably configured such that, in the event of mounting the insert  1  on the holder  10 , the direction perpendicular to the longitudinal direction of the rising surface  6  and the direction perpendicular to the longitudinal direction of the holder  10  on the outer peripheral surface of the adjustment member  12  is parallel. Accordingly, restraining can be made stable and strong. Each of the rising surfaces  6  ( 6 A,  6 B) may be a shape parallel to a direction perpendicular to the longitudinal direction (axial line L) of the insert  1 , or an inclining shape when viewed from the upper surface with respect to the direction perpendicular to the longitudinal direction as shown in  FIG. 7 , instead of the rising surface  6 ′ ( 6 A′,  6 B′) being parallel to the direction perpendicular to the longitudinal direction. 
     As shown in  FIGS. 4 and 5 , in addition to the adjustment member  21 , screw holes  14  penetrating from the outer peripheral surface of the holder  10  into the insertion hole  11  are formed on the tip end side of the holder relative to the adjustment member  12  so as to fit the screw member  15  into the screw hole  14  to press and clamp the outer peripheral surface of the shank part  3  of the insert  1  at the tip end of the screw member  15  in order to constrain the falling off or playing of the insert  1 . Then, a curved surface for the outer peripheral surface of the shank part  3  is preferably in abutting contact with the screw member  15 . That is, if the shank part  3  comes into a planar contact with the screw member  15  on a plane, due to the influence of manufacturing variations, the insert  1  may rotate and end up being mounted thereon; hence, the mounting position is shifted. 
     As shown in another embodiment in  FIG. 8 , regarding the positional relationship of the screw hole  14  and the screw member  15 , it is also possible to have a configuration in which the tip end of the screw member  15  is in abutting contact with the outer peripheral surface  4  of the shank part  3  of the insert  1  and in which a screw hole  14 ′ is formed so as to be arranged off-set from the rotational center axis O of the screw member  15  as if pulling the insert  1  into the rear side of the insertion hole  11  by an abutting contact part  18  following the rotation of the screw member  15 . It is indicated that a force ×1 pulling the insert  1  into the rear end direction of the holder  10  is generated at both points P and Q of  FIG. 8  ( b ). 
     Furthermore, as shown in  FIGS. 5(   c ) and  9 , in the event of inserting the insert  1 , for example, a mounting support member  19  is preferably provided within the insertion hole  11  for preventing the cutting edge  2 B from being damaged if the inserting direction of the insert  1  is incorrect (in case of inserting, for example, the insert by rotating 180° around an axis of the insert with respect to the inserting direction of the insert  1 ). According to the configuration, in case of inserting the insert  1  into the insertion hole  11  in a wrong direction, such a mounting support member  19  blocks the insertion of the insert  1  by causing other parts besides the cutting edge  2 B to contact the mounting support member  19  such that the cutting edge  2  of the insert  1  is prevented from being chipped by mistake when the insert is inserted in the holder  10 . 
     As a specific configuration of the mounting support member  19 , for example, a form of inserting the insert  1  into the insertion hole  11  is cited in which the flat part  5  formed at a location away from the cutting edge  2  of the insert  2  passes by the side of the mounting support member  19 . Although the mounting support member  19  protrudes towards the inside from the internal wall of the insertion hole  11  of the holder  11 , it is configured such that the mounting support member  19  is on the outside relative to the mounting position of the cutting edge  2  when the insertion hole  11  is viewed from the tip end side (the distance from the center of the insertion hole  11  to the cutting edge  2  is shorter than the distance from the center of the insertion hole  11  to the protruding part of the mounting support member)  19  in order to prevent collision of the cutting edge  2 . 
     Furthermore, as shown in  FIGS. 4 and 5(   c ), it may be configured that the mounting support member  19  is inserted, in a substantially cylindrically-shaped notch provided near the opening part of the insertion hole  11 , a cylindrically-shaped (rod shape) mounting support member  19  from the tip end side of the insertion hole  11  into a position where the side face thereof slightly protrudes into the insertion hole  11 , or to configure the mounting support member also by providing a through-hole  20  located on the tip end side of the holder  10  relative to the adjustment member  12  penetrating from the outer peripheral surface of the holder  10  to the insertion hole  11  such that a cylindrically-shaped (rod shape) mounting support member  19 ′ is inserted into the through-hole  20  as shown in  FIG. 9 . 
     As other methods for preventing a cutting edge from chipping due to a mounting mistake or an accident of the insert, as shown in  FIG. 5(   c ), a method may be considered for preventing the cutting edge  2  from colliding with the surroundings of the insertion hole  11  when the cutting edge  2  passes the opening part of the insertion hole  11  by providing a notch-groove  21  with an arch-shaped cross-section on an internal wall surface of the insertion hole  11  of the holder  10 . In addition, a method of covering and protecting the surface of the unused cutting edge  2 , which is inserted into the insertion hole  11 , with a protecting sheet, or a method of marking a position matching mark for a prescribed position on the outer peripheral surface of the shank part  3  and the vicinity of the opening part of the insertion hole  11  of the holder  10 , is also effective. 
     As a method for securing the adjustment member  12 , as shown in  FIG. 9 , a configuration has been employed by providing screw holes  22  communicating from a direction perpendicular with respect to the adjustment member mounting-holes  13  into which fit the cylindrically-shaped adjustment member  12  so as to fit a screw member  23  into the screw hole  22 . 
     The cutting tool T in the present invention for which the above insert  1  is mounted on the holder  10  clamps the adjustment member  12  provided inside the insertion hole  11  in a state of abutting the rising surface  6  thereto by inserting the insert  1  into the insertion hole  11  of the holder  10  as shown in  FIGS. 4 to 6 . According to such a configuration, favorable index precision may be obtained when determining the position in the longitudinal direction of the insert  1  and the center height direction, and the rotation of the insert may also be constrained during cutting. 
     REFERENCE NUMERALS 
     
         
           1  insert 
           2 ( 2 A,  2 B) cutting edges 
           3  shank part 
           4  outer peripheral surface 
           5  flat part 
           6 ( 6 A,  6 B) rising surface 
           7 ( 7 A,  7 B) rake surface 
           8 ( 8 A,  8 B) chip pocket 
           10  holder 
           11  insertion hole 
           12  adjustment member 
           13  adjustment member mounting-hole 
           14 ,  14 ′ screw hole screw member 
           18  abutting contact part 
           19 ,  19 ′ mounting support member 
           20  through-hole 
           21  notch-groove 
         T cutting tool