Rotary cutting head having cutting edges extending past key actuating portion
A replaceable milling head rotatable in a cutting direction about a longitudinal central axis, the central axis defining a forward direction and an opposite rearward direction, has a forward cutting portion and a rear threaded coupling portion for coupling to a shank. The cutting portion includes two or more key actuating portions which assist in mounting the milling head onto the shank. The cutting portion includes a plurality of helical chip flutes alternating with cutting edges. At least one or more of the cutting edges and flutes extend axially rearward of at least a portion of the key actuating portions.
1. A replaceable milling head ( 10 ) rotatable in a cutting direction (RD) about a longitudinal central axis (S) defining a forward direction (F) and an opposite rearward direction (R), the milling head ( 10 ) comprising:
a cutting portion ( 20 ), comprising:
an abutment surface ( 22 ), facing in the rearward direction (R) and extending annularly about the central axis (S);
a peripheral surface ( 24 ) extending forward (F) from the abutment surface ( 22 );
a plurality of chip removal flutes ( 26 ) extending along the peripheral surface ( 24 );
a plurality of cutting edges ( 28 ), each extending along a respective chip removal flute ( 26 ); and
a first and second key actuating portions ( 32 a , 32 c ) formed on radially opposite sides of the peripheral surface ( 24 ), each of the first and second key actuating portions ( 32 a , 32 c ) comprising:
a rearward-facing top shoulder ( 34 a , 34 c );
a forward-facing bottom shoulder ( 36 a , 36 c ) located rearward of the top shoulder ( 34 a , 34 c ); and
a bracing surface ( 38 a , 38 c ) extending between the top shoulder ( 34 a , 34 c ) to the bottom shoulder ( 36 a , 36 c ); and
a threaded coupling portion ( 40 ), extending rearward (R) of the abutment surface ( 22 );
wherein:
at least one cutting edge ( 28 ) has an active rear cutting edge portion ( 30 ) located axially rearward of at least one of the top shoulders ( 34 a , 34 c ); and
at least one of the chip removal flutes ( 26 ) intersects at least one of the bottom shoulders ( 36 a , 36 c ).
2. The replaceable milling head ( 10 ) according to claim 1 , wherein at least one of the chip removal flutes ( 26 ) intersects at least one of the top shoulders ( 34 a , 34 c ).
3. The replaceable milling head ( 10 ) according to claim 1 , wherein at least one of the chip removal flutes ( 26 ) intersects at least one of the bracing surfaces ( 38 a , 38 c ).
4. The replaceable milling head ( 10 ) according to claim 1 , wherein the at least one active rear cutting edge portion ( 30 ) intersects the abutment surface ( 22 ).
5. The replaceable milling head ( 10 ) according to claim 1 , wherein the at least one active rear cutting edge portion ( 30 ) extends axially rearward of at least one of the bottom shoulders ( 36 a , 36 c ).
6. The replaceable milling head ( 10 ) according to claim 1 , wherein
an actuating portion axial length (SL) extends parallel to the central axis S from one of the top shoulders ( 34 a , 34 c ) to a respective bottom shoulder ( 36 a , 36 c ), and
at least one active rear cutting edge portion ( 30 ) extends to at least 50% of the actuating portion axial length (SL) in the rearward direction (R).
7. The replaceable milling head ( 10 ) according to claim 1 , wherein the number of chip removal flutes ( 26 ) is four, and the number of cutting edges ( 28 ) is four.
8. The replaceable milling head ( 10 ) according to claim 7 , wherein exactly two of the chip removal flutes ( 26 a , 26 c ) intersect the top shoulders ( 34 a , 34 c ), the bottom shoulders ( 36 a , 36 c ) and the bracing surfaces ( 38 a , 38 c ).
9. The replaceable milling head ( 10 ) according to claim 7 , wherein all four chip removal flutes ( 26 ) intersect the abutment surface ( 22 ).
10. The replaceable milling head ( 10 ) according to claim 1 , wherein each bracing surface ( 38 a , 38 c ) is split into a leading surface ( 39 L) and a trailing surface ( 39 T) which straddle a portion of one of the chip removal flutes ( 26 ).
11. The replaceable milling head ( 10 ) according to claim 1 , wherein
an additional cutting extent (CL) extends parallel to the central axis (S) from one of the top shoulders ( 34 a , 34 c ) to an axially rearmost point ( 31 ) of the respective rear cutting edge portion ( 30 ),
an actuating portion axial length (SL) extends parallel to the central axis (S) from one of the top shoulders ( 34 a , 34 c ) to a respective bottom shoulders ( 36 a , 36 c ), and
the relation between the additional cutting extent (CL) and the actuating portion axial length (SL) fulfils the condition:
CL
SL
≥
0.3
.
12. The replaceable milling head ( 10 ) according to claim 11 , wherein the relation between the additional cutting extent (CL) and the actuating portion axial length (SL) fulfils the condition:
2
≥
CL
SL
≥
0.5
.
13. The replaceable milling head ( 10 ) according to claim 1 , wherein
a rear core diameter (Dr) is located rearward of at least one of the top shoulders ( 34 a , 34 c ) and measurable as the diameter of an inscribed circle (Ic) of the milling head ( 10 ) from a forward view, and
a forward core diameter (Df) is located forward of the top shoulders ( 34 a , 34 c ) and measurable as the diameter of the inscribed circle (Ic) of the milling head ( 10 ) from a rear view, and wherein
the rear core diameter (Dr) is equal to, or larger than, the forward core diameter (Df).
14. The replaceable milling head ( 10 ) according to claim 13 , wherein the rear core diameter (Dr) is between 5% and 15% larger than the forward core diameter (Df).
15. The replaceable milling head ( 10 ) according to claim 1 , wherein the chip removal flutes ( 26 ) extend helically along the peripheral surface ( 24 ).
16. A replaceable milling head ( 10 ) rotatable in a cutting direction (RD) about a longitudinal central axis (S) defining a forward direction (F) and an opposite rearward direction (R), the milling head ( 10 ) comprising:
a cutting portion ( 20 ), comprising:
an abutment surface ( 22 ), facing in the rearward direction (R) and extending annularly about the central axis (S);
a peripheral surface ( 24 ) extending forward (F) from the abutment surface ( 22 );
a plurality of chip removal flutes ( 26 ) extending along the peripheral surface ( 24 );
a plurality of cutting edges ( 28 ), each extending along a respective chip removal flute ( 26 ); and
a first and second key actuating portions ( 32 a , 32 c ) formed on radially opposite sides of the peripheral surface ( 24 ), each of the first and second key actuating portions ( 32 a , 32 c ) comprising:
a rearward-facing top shoulder ( 34 a , 34 c );
a forward-facing bottom shoulder ( 36 a , 36 c ) located rearward of the top shoulder ( 34 a , 34 c ); and
a bracing surface ( 38 a , 38 c ) extending between the top shoulder ( 34 a , 34 c ) to the bottom shoulder ( 36 a , 36 c ); and
a threaded coupling portion ( 40 ), extending rearward (R) of the abutment surface ( 22 );
wherein:
at least one cutting edge ( 28 ) has an active rear cutting edge portion ( 30 ) located axially rearward of at least one of the top shoulders ( 34 a , 34 c ); and
the at least one active rear cutting edge portion ( 30 ) extends axially rearward of at least one of the bottom shoulders ( 36 a , 36 c ).
17. The replaceable milling head ( 10 ) according to claim 16 , wherein
an actuating portion axial length (SL) extends parallel to the central axis S from one of the top shoulders ( 34 a , 34 c ) to a respective bottom shoulder ( 36 a , 36 c ), and
at least one of the chip removal flutes ( 26 ) extends to at least 50% of the actuating portion axial length (SL) in the rearward direction (R).
18. The replaceable milling head ( 10 ) according to claim 16 , wherein the at least one active rear cutting edge portion ( 30 ) intersects the abutment surface ( 22 ).
19. A replaceable milling head ( 10 ) rotatable in a cutting direction (RD) about a longitudinal central axis (S) defining a forward direction (F) and an opposite rearward direction (R), the milling head ( 10 ) comprising:
a cutting portion ( 20 ), comprising:
an abutment surface ( 22 ), facing in the rearward direction (R) and extending annularly about the central axis (S);
a peripheral surface ( 24 ) extending forward (F) from the abutment surface ( 22 );
a plurality of chip removal flutes ( 26 ) extending along the peripheral surface ( 24 );
a plurality of cutting edges ( 28 ), each extending along a respective chip removal flute ( 26 ); and
a first and second key actuating portions ( 32 a , 32 c ) formed on radially opposite sides of the peripheral surface ( 24 ), each of the first and second key actuating portions ( 32 a , 32 c ) comprising:
a rearward-facing top shoulder ( 34 a , 34 c );
a forward-facing bottom shoulder ( 36 a , 36 c ) located rearward of the top shoulder ( 34 a , 34 c ); and
a bracing surface ( 38 a , 38 c ) extending between the top shoulder ( 34 a , 34 c ) to the bottom shoulder ( 36 a , 36 c ); and
a threaded coupling portion ( 40 ), extending rearward (R) of the abutment surface ( 22 );
wherein:
at least one cutting edge ( 28 ) has an active rear cutting edge portion ( 30 ) located axially rearward of at least one of the top shoulders ( 34 a , 34 c );
the number of chip removal flutes ( 26 ) is four, and the number of cutting edges ( 28 ) is four; and
all four chip removal flutes ( 26 ) intersect the abutment surface ( 22 ).