Cutting tool and cutting insert with a rearward resilience slit
A cutting insert has a head portion and a coupling portion protruding rearwards from the head portion, along a longitudinal insert axis. The head portion has a base surface at a rearward end thereof, defining a base plane, and two major surfaces. A coupling portion rear surface is longitudinally spaced apart from the base surface and a cylindrical coupling peripheral surface extends between the coupling portion rear surface and the base surface. A resilience slit has two opposite inner walls converging forwards towards a slit inner end terminating at a slit inner end plane. The slit inner end plane is parallel to the base plane and spaced apart therefrom by a longitudinal distance. The inner walls of the resilience slit form an acute slit angle therebetween.
1. A cutting insert ( 102 ), having a longitudinal insert axis (A) extending in a forward (D F ) to rearward direction (D R ), comprising:
a head portion ( 104 ) having two opposing major surfaces ( 106 ) and a head peripheral surface ( 108 ) extending therebetween, the head peripheral surface ( 108 ) including a base surface ( 110 ) at a rearward end ( 112 ) of the head portion ( 104 ), the base surface ( 110 ) defining a base plane (P 1 ) perpendicular to the insert axis (A); and
a coupling portion ( 116 ) protruding rearwards from the base surface ( 110 ) along the insert axis (A), the coupling portion ( 116 ) comprising:
a rear surface ( 118 ) spaced apart from the base surface ( 110 ) along the insert axis (A) and a cylindrical coupling peripheral surface ( 120 ) extending therebetween, the coupling peripheral surface ( 120 ) intersecting with the base surface ( 110 ) at a transition area ( 122 ); and
a resilience slit ( 124 ) extending from the rear surface ( 118 ) in the forward direction (D F ) and opening out to the coupling peripheral surface ( 120 ), the resilience slit ( 124 ) having two opposite inner walls ( 131 ) converging in the forward direction (D F ) towards a slit inner end ( 126 ) which terminates at a slit inner end plane (P 2 ) perpendicular to the insert axis (A),
wherein:
the slit inner end plane (P 2 ) is spaced apart from the base plane (P 1 ) by a longitudinal distance (D); and
the inner walls ( 131 ) of the resilience slit ( 124 ) form a first acute slit angle (α 1 ) therebetween.
2. The cutting insert ( 102 ) according to claim 1 , wherein the rear surface ( 118 ) defines an end plane (P 3 ) perpendicular to the insert axis (A) and the resilience slit ( 124 ) has a longitudinal slit length (H) between the end plane (P 3 ) and the slit inner end plane (P 2 ).
3. The cutting insert ( 102 ) according to claim 2 , wherein the longitudinal distance (D) is smaller than the longitudinal slit length (H).
4. The cutting insert ( 102 ) according to claim 1 , wherein a cross section of the coupling portion ( 116 ) taken perpendicular to the insert axis (A) between the slit inner end plane (P 2 ) and the base plane (P 1 ), is a full undivided cross section ( 128 ).
5. The cutting insert ( 102 ) according to claim 1 , wherein the coupling peripheral surface ( 120 ) includes two opposite indents ( 130 ) arranged symmetrically about the insert axis (A).
6. The cutting insert ( 102 ) according to claim 1 , wherein the transition area ( 122 ) has a substantially circular boundary ( 132 ), entirely surrounded by the base surface ( 110 ).
7. The cutting insert ( 102 ) of claim 1 , wherein in a side view of the coupling portion ( 116 ) taken along the insert axis (A), a coupling portion width (W) extends between the coupling peripheral surface ( 120 ), on either side of the resilience slit ( 124 ), and in a neutral position of the coupling portion ( 116 ) the coupling portion width (W) is substantially constant, along the coupling portion ( 116 ).
8. The cutting insert ( 102 ) according to claim 1 , wherein the head peripheral surface ( 108 ) further includes a forward surface ( 134 ) at a forward end ( 136 ) of the head portion ( 104 ), wherein a portion of the intersection of each of the major surfaces ( 106 ) with the forward surface ( 134 ) forms a respective major cutting edge ( 138 ).
9. The cutting insert ( 102 ) according to claim 1 , wherein each of the major surfaces ( 106 ) has an insert radial abutment surface ( 125 ) extending from the head peripheral surface ( 108 ) towards the insert axis (A) and the base surface ( 110 ), the insert radial abutment surfaces ( 125 ) defining first and second radial abutment planes (P A1 , P A2 ), parallel to one another and to the insert axis (A), and
the resilience slit ( 124 ) divides the coupling portion ( 116 ) into two coupling legs ( 117 ), and a resilience slit plane (P S ) passes substantially centrally between the coupling legs ( 117 ) and includes the insert axis (A), the resilience slit plane (P S ) being perpendicular to the first and second radial abutment planes (P A1 , P A2 ).
10. The cutting insert ( 102 ) according to claim 1 , wherein:
the coupling legs ( 117 ) are located on either side of a resilience slit plane (P S ) which passes between the coupling legs ( 117 ) and contains the insert axis (A);
each coupling leg ( 117 ) has a thickness (T) in a direction perpendicular to the resilience slit plane (P S ); and
the thickness (T) of each coupling leg ( 117 ) decreases in the direction toward the rear surface ( 118 ).
11. A cutting tool ( 100 ) having an axis of rotation (B) extending in a forward (D F ) to rearward direction (D R ), and around which the cutting tool ( 100 ) rotates in a direction of rotation (R), the cutting tool ( 100 ) comprising:
a tool shank ( 150 ) having a shank forward end ( 154 ) with a receiving portion ( 152 ), the receiving portion ( 152 ) comprising a receiving portion peripheral surface ( 156 ) extending circumferentially about the axis of rotation (B); and
a cutting insert ( 102 ) according to claim 1 ,
wherein:
in an assembled position of the cutting tool ( 100 ), the cutting insert ( 102 ) is resiliently secured to the tool shank ( 150 ) by an interference fit applied between the coupling peripheral surface ( 120 ) and the receiving portion peripheral surface ( 156 ).
12. The cutting tool ( 100 ) of claim 11 , wherein
the resilience slit ( 124 ) divides the coupling portion ( 116 ) into two coupling legs ( 117 ); and
the coupling legs ( 117 ) resiliently approach the insert axis (A), in the assembled position.
13. The cutting tool ( 100 ) of claim 11 , wherein the receiving portion peripheral surface ( 156 ) is substantially cylindrical.
14. The cutting tool ( 100 ) of claim 11 , wherein the receiving portion ( 152 ) includes a rearmost receiving portion base ( 158 ), and in the assembled position the rear surface ( 118 ) is spaced apart from the rearmost receiving portion base ( 158 ).
15. The cutting tool ( 100 ) of claim 11 , wherein:
each of the major surfaces ( 106 ) has an insert radial abutment surface ( 125 ) extending from the head peripheral surface ( 108 ) towards the insert axis (A) and the base surface ( 110 ),
the tool shank ( 150 ) further includes two shank radial abutment surfaces ( 160 ), located at the shank forward end ( 154 ), extending parallel to, and arranged symmetrically about the axis of rotation (B), and
in the assembled position each head radial abutment surface ( 125 ) abuts a respective shank radial abutment surface ( 160 ).
16. The cutting tool ( 100 ) of claim 11 , wherein:
the base portion ( 110 ) further includes two insert transverse abutment surfaces ( 123 ), extending perpendicular to, and symmetrically around the insert axis (A),
the tool shank ( 150 ) further includes two shank radial abutment surfaces ( 160 ), located at the shank forward end ( 154 ), extending parallel to, and arranged symmetrically about the axis of rotation (B),
the tool shank ( 150 ) further includes two shank transverse abutment surfaces ( 162 ), each extending from a respective one of the shank radial abutment surface ( 160 ), circumferentially and perpendicular to the axis of rotation (B), and
in the assembled position, each one of the head transverse abutment surfaces ( 123 ) abuts a respective one of the shank transverse abutment surfaces ( 162 ).
17. The cutting tool ( 100 ) of claim 11 , wherein:
the cutting insert ( 102 ) further includes two retaining ledges ( 133 ), each extending circumferentially from the rearward end of a respective insert radial abutment surfaces ( 125 ), along a portion of the respective insert transverse abutment surface ( 123 ), and
the tool shank ( 150 ) further includes two retaining undercuts ( 164 ), each extending circumferentially from a respective shank transverse abutment surface ( 162 ), for receiving the retaining ledges ( 133 ) therein, in the assembled position.
18. The cutting tool ( 100 ) of claim 11 , wherein:
the cutting insert ( 102 ) further includes two insert flute surfaces ( 107 ), each extending rearwards from a forward end ( 136 ) of the head portion ( 104 ), on the respective major surface ( 106 ),
the tool shank ( 150 ) further includes two shank flute portions ( 157 ), arranged symmetrically about the axis of rotation (B), and
in the assembled position, each of the shank flute portions ( 157 ) forms an extension of a respective insert flute surface ( 107 ).
19. The cutting tool ( 100 ) of claim 11 , wherein in the assembled position, the insert axis (A) coincides with the axis of rotation (B).
20. The cutting tool ( 100 ) of claim 11 , wherein in the assembled position, the coupling portion ( 116 ) of the cutting insert ( 102 ) is entirely confined within the receiving portion ( 152 ) of the tool shank ( 150 ).
21. The cutting tool ( 100 ) of claim 11 , wherein:
in the side view of the coupling portion ( 116 ) a coupling portion width (W) extends between the coupling peripheral surface ( 120 ), on either side of the resilience slit ( 124 ),
in a neutral position of the coupling portion ( 116 ) the coupling portion width (W) is substantially constant, along the coupling portion ( 116 ), and
in the assembled position, the coupling portion width (W) decreases when approaching the rear surface ( 118 ) from the slit inner end ( 126 ).
22. The cutting tool ( 100 ) of claim 11 , wherein in the assembled position, the inner walls ( 131 ) of the resilience slit ( 124 ) form a second slit angle (α 2 ) therebetween, the second slit angle (α 2 ) being smaller than the first acute slit angle (α 1 ).