Cutting tool and replaceable cutting head having spiral driven surfaces therefor
A replaceable cutting head includes a forward cutting portion and a rearward mounting portion. The mounting portion includes a male coupling member that protrudes rearwardly from a base surface. The male coupling member includes three circumferentially spaced apart head fixation members, where each head fixation member has a head peripheral surface that spirals inwardly in a direction against the direction of rotation and diverges. A tool holder includes a female coupling member extends rearwardly from a holder forward surface. The female coupling member includes three circumferentially spaced apart holder fixation members, where each holder fixation member has a holder peripheral surface that diverges rearwardly. When a cutting tool, which includes said cutting head and tool holder, is in a locked position, the male coupling member of the replaceable cutting head is removably retained within the female coupling member of the tool holder by means of a self-lock mechanism.
1. A replaceable cutting head ( 22 ), for rotary cutting operations, having a head longitudinal axis (A) around which the replaceable cutting head ( 22 ) rotates in a direction of rotation (R), the head longitudinal axis (A) extending in a forward (D F ) to rearward direction (D R ), comprising:
a forward portion forming a cutting portion ( 26 ) and a rearward portion forming a mounting portion ( 28 );
the cutting portion ( 26 ) comprising:
a plurality of cutting members ( 30 ) extending radially with respect to the head longitudinal axis (A); and
the mounting portion ( 28 ) comprising a male coupling member ( 40 ) protruding rearwardly from a base surface ( 42 ), the base surface ( 42 ) extending transversely with respect to the head longitudinal axis (A), and defining a boundary between the cutting portion ( 26 ) and the mounting portion ( 28 ), the male coupling member ( 40 ) comprising:
three circumferentially spaced apart head fixation members ( 44 ), each head fixation member ( 44 ) comprising a head peripheral surface ( 46 ) diverging rearwardly with respect to the head longitudinal axis (A), wherein:
in each cross section of the male coupling member ( 40 ) taken in a plane through the head peripheral surface ( 46 ) and perpendicular to the head longitudinal axis (A), a first end point (PE 1 ) on any head peripheral surface ( 46 ) is closer to the head longitudinal axis (A) than a second end point (PE 2 ) on the same head peripheral surface ( 46 ), the second end point (PE 2 ) being circumferentially disposed further in the direction of rotation (R) relative to the first end point (PE 1 ).
2. The replaceable cutting head ( 22 ) according to claim 1 , wherein
a first angle α is formed between the head longitudinal axis (A) and a line (T) tangential to any point on each head peripheral surface ( 46 ), wherein the first angle α is in the range of 35°≦α≦55°.
3. The replaceable cutting head ( 22 ) according to claim 2 , wherein the first angle (α) is a 45° angle.
4. The replaceable cutting head ( 22 ) according to claim 1 , wherein
in each cross section of the male coupling member ( 40 ) taken in a plane through the head peripheral surface ( 46 ) and perpendicular to the head longitudinal axis (A), each head peripheral surface ( 46 ) lies on a spiral (S), having a spiral center (S C ), each head peripheral surface ( 46 ) forming a spiral portion (SP).
5. The replaceable cutting head ( 22 ) according to claim 4 , wherein
the two end points (PE 1 , PE 2 ) of each spiral portion (SP) subtend a peripheral surface angle β relative to the spiral center (S C ); wherein the peripheral surface angle β is in the range of 30°≦β≦60°.
6. The replaceable cutting head ( 22 ) according to claim 4 , wherein each spiral center (S C ) is coincident with the head longitudinal axis (A).
7. The replaceable cutting head ( 22 ) according to claim 4 , wherein each spiral (S) is an Archimedean spiral.
8. The replaceable cutting head ( 22 ) according to claim 7 , wherein the pitch angle (δ) of each spiral portion (SP) is less than 30°.
9. The replaceable cutting head ( 22 ) according to claim 1 , wherein
the head peripheral surfaces ( 46 ) serve as spiral driven surfaces applying torque transmission to the replaceable cutting head ( 22 ); and
the cutting portion ( 26 ) is devoid of a surface facing against the direction of rotation (R) that serves as a driven surface for applying torque transmission to the replaceable cutting head ( 22 ).
10. The replaceable cutting head ( 22 ) according to claim 1 , wherein
the head peripheral surfaces ( 46 ) serve as spiral driven surfaces applying torque transmission to the replaceable cutting head ( 22 ); and
the mounting portion ( 28 ) is devoid of a surface facing against the direction of rotation (R) that serves as a driven surface applying torque transmission to the replaceable cutting head ( 22 ).
11. The replaceable cutting head ( 22 ) according to claim 1 , wherein the male coupling member ( 40 ) is devoid of a resilience slit.
12. The replaceable cutting head ( 22 ) according to claim 1 , wherein the base surface ( 42 ) is perpendicular to the head longitudinal axis (A).
13. The replaceable cutting head ( 22 ) according to claim 1 , wherein
in an end view perpendicular to the head longitudinal axis (A), an imaginary cutting portion circle (C CP ) circumscribing the cutting portion ( 26 ) has a maximum cutting portion diameter (D CP ); and
the maximum cutting portion diameter (D CP ) is greater than or equal to 25 mm.
14. The replaceable cutting head ( 22 ) according to claim 1 , wherein
an imaginary base surface circle (C BS ) circumscribing a largest dimension of the base surface ( 42 ), taken perpendicular to the head longitudinal axis (A), has a maximum base surface diameter (D BS );
an imaginary male coupling member circle (C MCM ) circumscribing a largest dimension of the male coupling member ( 40 ), taken perpendicular to the head longitudinal axis (A), has a maximum male coupling member diameter (D MCM ); and
the maximum base surface diameter (D BS ) is at least one and a half times as large as the maximum male coupling member diameter (D MCM ).
15. The replaceable cutting head ( 22 ) according to claim 1 , wherein,
measured in the forward direction (D F ) along the head longitudinal axis (A) from the base surface ( 42 ), the cutting portion ( 26 ) has a maximum cutting portion length (L CP ),
measured in the rearward direction (D R ) along the head longitudinal axis (A) from the base surface ( 42 ), the mounting portion ( 28 ) has a maximum mounting portion length (L MP ); and
the maximum cutting portion length (L CP ) is at least two and a half times greater than the maximum mounting portion length (L MP ).
16. The replaceable cutting head ( 22 ) according to claim 1 , wherein,
measured in the rearward direction (D F ) along the head longitudinal axis (A) from the base surface ( 42 ), the mounting portion ( 28 ) has a maximum mounting portion length (L MP );
an imaginary base surface circle (C BS ) circumscribing a largest dimension of the base surface ( 42 ), taken perpendicular to the head longitudinal axis (A), has a maximum base surface diameter (D BS ); and
the maximum base surface diameter (D BS ) is at least three times greater than the maximum mounting portion length (L MP ).
17. The replaceable cutting head ( 22 ) according to claim 1 , wherein the male coupling member ( 40 ) exhibits 3-fold rotational symmetry about the head longitudinal axis (A).
18. The replaceable cutting head ( 22 ) according to claim 1 , comprising a unitary integral one-piece construction.
19. The replaceable cutting head ( 22 ) according to claim 1 , wherein each head peripheral surface ( 46 ) lies on a portion of the curved surface of an associated imaginary irregular cone, the cone having a spiral-shaped base surface.
20. The replaceable cutting head ( 22 ) according to claim 1 , wherein
the male coupling member ( 40 ) further comprises a rear surface ( 48 ), the rear surface ( 48 ) intersecting the rearmost portion of each head fixation member ( 44 ).
21. The replaceable cutting head ( 22 ) according to claim 20 , wherein the rear surface ( 48 ) is perpendicular with respect to the head longitudinal axis (A).
22. The replaceable cutting head ( 22 ) according to claim 20 , wherein
each head fixation member ( 44 ) further comprises a chamfered surface ( 50 ), extending between the rear surface ( 48 ) and each head peripheral surface ( 46 ), and converging rearwardly with respect to the head longitudinal axis (A).
23. The replaceable cutting head ( 22 ) according to claim 20 , wherein
each head fixation member ( 44 ) further comprises a concave surface ( 66 ), extending between the base surface ( 42 ) and each head peripheral surface ( 46 ).
24. A cutting tool ( 20 ) comprising:
a replaceable cutting head ( 22 ) in accordance with claim 1 ; and
a tool holder ( 24 ), having a holder longitudinal axis (C) extending in the forward (D F ) to rearward direction (D R ), comprising a female coupling member ( 52 ) extending rearwardly from a holder forward surface ( 54 ), the holder forward surface ( 54 ) extending transversely with respect to the holder longitudinal axis (C), the female coupling member ( 52 ) comprising:
three circumferentially spaced apart holder fixation members ( 56 ), each holder fixation member ( 56 ) comprising a recessed holder peripheral surface ( 58 ) diverging rearwardly with respect to the holder longitudinal axis (C); and
a holder rear surface ( 60 ) extending transversely with respect to the holder longitudinal axis (C) and intersecting each holder fixation member ( 56 ); wherein
the male coupling member ( 40 ) further comprises a rear surface ( 48 ), the rear surface ( 48 ) intersecting the rearmost portion of each head fixation member ( 44 ); and
the replaceable cutting head ( 22 ) is rotatable between a released position and a locked position, wherein in the locked position:
the male coupling member ( 40 ) is removably retained in the female coupling member ( 52 );
each of the head peripheral surfaces ( 46 ) abuts a corresponding holder peripheral surface ( 58 );
the base surface ( 42 ) abuts the holder forward surface ( 54 ); and
the rear surface ( 48 ) is spaced apart from the holder rear surface ( 60 ).
25. The cutting tool ( 20 ) according to claim 24 , wherein
the tool holder ( 24 ) further comprises a holder shank surface ( 62 ) extending rearwardly from the holder forward surface ( 54 );
the female coupling member ( 52 ) opens out to the holder shank surface ( 62 ) at three circumferentially spaced apart holder flute surfaces ( 64 ); and
the holder forward surface ( 54 ) comprises three spaced apart portions.
26. The cutting tool ( 20 ) according to claim 24 , wherein each holder peripheral surface ( 58 ) spirals inwardly in a direction against the direction of rotation (R).
27. The cutting tool ( 20 ) according to claim 24 , wherein the head longitudinal axis (A) is coaxial with the holder longitudinal axis (C).
28. The cutting tool ( 20 ) according to claim 24 , wherein the peripheral portion of the holder forward surface ( 54 ) comprises a raised surface ( 68 ).
29. A tool holder ( 24 ) having a longitudinal axis (C) extending in a forward (D F ) to a rearward direction (D R ) and a direction of rotation (R) about the longitudinal axis (C), the tool holder comprising:
a female coupling member ( 52 ) extending rearwardly from a holder forward surface ( 54 ), the holder forward surface ( 54 ) extending transversely with respect to the holder longitudinal axis (C), the female coupling member ( 52 ) comprising:
three circumferentially spaced apart holder fixation members ( 56 ), each holder fixation member ( 56 ) comprising a recessed holder peripheral surface ( 58 ) diverging rearwardly with respect to the holder longitudinal axis (C), wherein:
in each cross-section of the female coupling member ( 52 ) taken in a plane through the holder peripheral surfaces ( 58 ) and perpendicular to the holder longitudinal axis (C), a first female end point (FPE 1 ) on a given holder peripheral surface ( 58 ) is closer to the holder longitudinal axis (C) than a second female end point (FPE 2 ) on the same holder peripheral surface ( 58 ), the second female end point (FPE 2 ) being circumferentially disposed further in the direction of rotation (R) relative to the first female end point (FPE 1 ); and
each holder peripheral surface ( 58 ) is formed as an undercut of a corresponding holder fixation member ( 56 ) and hidden from view in a front view of the tool holder ( 24 ) along the longitudinal axis (C); and
a holder rear surface ( 60 ) extending transversely with respect to the holder longitudinal axis (C) and intersecting each holder fixation member ( 56 ).