Replaceable Face-Milling Head With Integrally Formed Threaded Shank-Connector

Abstract

A replaceable face-milling head configured for rotating about a central rotation axis A.sub.R. The head includes a cutting portion and an integrally formed threaded shank-connector portion, the latter of which being configured for connecting to a shank. A length-diameter ratio LDR, defined as a cutting portion length L.sub.C divided by a cutting portion diameter D.sub.E, fulfills the condition: LDR≦1.00.

Claims

1. A replaceable face-milling head configured for rotating about a central rotation axis A.sub.R defining opposite axially forward and rearward directions D.sub.F, D.sub.R and opposite rotational preceding and succeeding directions D.sub.P, D.sub.S, the preceding direction D.sub.P being the cutting direction, the face-milling head comprising: a head rear face, a head front face and a head peripheral surface extending from the head rear face to the head front face; a shank-connector portion formed with external threading and extending forward from the head rear face; a cutting portion integrally formed with the shank-connector portion and extending forward from the shank-connector portion to the head front face; a cutting portion length L.sub.C measurable parallel to the central rotation axis A.sub.R; and a perpendicular plane P.sub.P adjacent the front face and extending perpendicular to the central rotation axis A.sub.R, the cutting portion comprising: a plurality of integrally formed teeth, each of the teeth comprising a primary cutting edge at the head front face; a plurality of flutes alternating with the plurality of teeth; and a cutting portion diameter D.sub.E; characterized in that a length-diameter ratio LDR defined as the cutting portion length L.sub.C divided by the cutting portion diameter D.sub.E fulfills the condition: 0.3≦LDR≦1.00.

2. The face-milling head according to claim 1, wherein the length-diameter ratio LDR fulfills the condition: LDR≦0.90.

3. The face-milling head according to claim 2, wherein the length-diameter ratio LDR fulfills the condition: LDR≧0.40.

4. The face-milling head according to claim 1, wherein the length-diameter ratio LDR fulfills the condition: LDR=0.50±0.05

5. The face-milling head according to claim 1, wherein the center of gravity of the head is located in the cutting portion.

6. The face-milling head according to claim 1, wherein each tooth of the plurality of teeth is positioned front-of-center.

7. The face-milling head according to claim 1, wherein a coolant hole opens out at a center of the head front face.

8. The face-milling head according to claim 1, wherein each tooth of the plurality of teeth further comprises: a relief edge extending along the peripheral surface; a convexly curved outer corner connected to the relief edge and comprising a radial extremity point of the cutting portion; said primary cutting edge connected to, and extending in a forward-inward direction from, the outer corner; a convexly curved inner corner connected to the primary cutting edge; and a ramping cutting edge connected to, and extending in a rearward-inward direction from, the inner corner.

9. The face-milling head according to claim 8, wherein in a rearward view along the central rotation axis A.sub.R, each tooth of the plurality of teeth is convexly curved, at least from the inner corner to the outer corner.

10. The face-milling head according to claim 8, wherein: the primary cutting edge is convexly curved and has a cutting edge radius; the outer corner has an outer corner radius; and the cutting edge radius is greater than the outer corner radius.

11. The face-milling head according to claim 10, wherein the cutting edge radius is at least eight times greater that the outer corner radius.

12. The face-milling head according to claim 8, wherein the outer corner radius is smaller than or equal to 2 mm.

13. The face-milling head according to claim 8, wherein the relief edge extends in a rearward-inward direction from the outer corner.

14. The face-milling head according to claim 8, wherein: a first connection point is defined where the primary cutting edge and the inner corner connect; a second connection point is defined where the primary cutting edge and the outer corner connect; and an imaginary straight line is defined between the first and second connection points and together with the perpendicular plane subtends a cutting angle a fulfilling the condition: 10°≦α≦25°.

15. The face-milling head according to claim 8, wherein a lead-in-angle θ subtended by the perpendicular plane P.sub.P and the central rotation axis A.sub.R fulfills the condition: 10°≦θ≦30°.

16. The face-milling head according to claim 1, wherein a fastening construction is formed at the cutting portion along a head peripheral surface thereof and the length-diameter ratio LDR fulfills the condition: 0.50≦LDR≦1.00.

17. The face-milling head according to claim 1, wherein the cutting portion comprises a rearwardly facing cutting portion annular surface surrounding the shank-connector.

18. The face-milling head according to claim 1, wherein the plurality of teeth is 5 to 7 teeth.

19. The face-milling head according to claim 18, wherein the plurality of teeth is exactly 6 teeth.

20. A face-milling assembly comprising: a face-milling head according to claim 1; and a shank comprising: a shank rear face; a shank front face; and a shank peripheral surface extending from the shank rear face to the shank front face; the shank front face being formed with an opening configured to receive the shank-connector portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] For a better understanding of the subject matter of the present application, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:

[0063] FIG. 1 is an exploded side view of a milling head and shank according to the subject matter of the present application;

[0064] FIG. 2 is a front end view of a milling head in FIG. 1;

[0065] FIG. 3 is an enlarged side view of the milling head in FIG. 1;

[0066] FIG. 4 is a side view of a part of a cutting portion of the milling head in FIGS. 1 to 3;

[0067] FIG. 5 is a side view of the same part of the cutting portion in FIG. 3, rotated to match the orientation shown in FIGS. 1 and 3; and

[0068] FIG. 6 is a schematic profile view of the lowermost tooth shown in FIG. 5.

DETAILED DESCRIPTION

[0069] Referring to FIG. 1, typical features of a face-milling assembly 10 will first be described. The face-milling assembly 10 comprises a shank 12 and a head 14.

[0070] The shank 12 comprises a shank rear face 16, a shank front face 18 and a shank peripheral surface 20.

[0071] The shank front face 18 can be formed with an opening 22. The opening 22 can be centrally located. The opening 22 can be formed with an internal threading 24.

[0072] The shank front face 18 can further comprise a forwardly facing shank annular surface 26. The shank annular surface 26 can surround the opening 22.

[0073] The shank can have shank axis A.sub.S, along which a shank length L.sub.SH can be measured. The shank length L.sub.SH can be configured with a standard length for being held by a collet (not shown).

[0074] The head 14 can comprise a head rear face 28, a head front face 30 and a head peripheral surface 32 extending from the head rear face 28 to the head front face 30.

[0075] The head 14 further comprises a shank-connector portion 34 and a cutting portion 36.

[0076] The shank-connector portion 34 can extend from the rear face 28 to an intersection 38 of the shank-connector portion 34 and cutting portion 36.

[0077] The shank-connector portion 34 can be formed with external threading 40. More precisely the shank-connector portion 34 can comprise a lower connector section 42 and an upper connector section 44. The upper connector section 44 can connect the lower connector section 42 and the cutting portion 36. The external threading 40 can be formed on the lower connector section 42. The upper connector section 44 can preferably be frustoconical.

[0078] The cutting portion 36 can comprise a cutting portion annular surface 46 surrounding the shank-connector 34.

[0079] The head 14 can be secured to the shank 12 via the internal and external threading 24, 40, typically with the shank annular surface 26 abutting the cutting portion annular surface 46.

[0080] Referring now to FIGS. 2 and 3, features more specifically relating to the subject matter of the present application will be described.

[0081] A central rotation axis A.sub.R extends longitudinally through the center of the head 14, defining opposite axially forward and rearward directions D.sub.F, D.sub.R and opposite rotational preceding and succeeding directions D.sub.P, D.sub.S, the preceding direction D.sub.P being the cutting direction. An example inward direction D.sub.I is shown for understanding, but it will be understood that the term “inward direction” means generally directed toward the central rotation axis A.sub.R. Similarly, an outward direction D.sub.O is also exemplified, and should be understood as generally directed away from the central rotation axis A.sub.R. Hereinafter combined directions such as “forward-inward direction” and “rearward-inward direction” are used, which define a single direction resulting from a combination of components of both of the mentioned directions, although not necessarily an exact bisector between the two mentioned directions.

[0082] A perpendicular plane P.sub.P is located adjacent to the head front face 30 (i.e. extending at a intersecting a front point thereof, which in this case is constituted by the inner corners 60) and extends perpendicular to the central rotation axis A.sub.R.

[0083] A cutting portion length L.sub.C is measurable parallel to the central rotation axis A.sub.R. More precisely, the cutting portion length L.sub.C can be defined as extending from an intersection 38 of the shank-connector portion 34 and the cutting portion 36 to the head front face 30 (or, stated differently, to the perpendicular plane P.sub.P).

[0084] A shank-connector length L.sub.S is measurable parallel to the central rotation axis A.sub.R. More precisely, the shank-connector length L.sub.S can be defined as extending from the rear face 28 to the intersection 38.

[0085] A shank-connector diameter D.sub.SC (i.e. a maximum shank-connector diameter) can be smaller than a cutting portion diameter D.sub.E measurable perpendicular to the central rotation axis A.sub.R. Preferably the shank-connector diameter D.sub.SC can be smaller than a smallest outer diameter D.sub.M of the cutting portion 36.

[0086] A total length L.sub.T can be defined from the head rear face 28 to the perpendicular plane P.sub.P.

[0087] The cutting portion 36 comprises a plurality of integrally formed teeth 50 (e.g. first, second, third, fourth, fifth, and sixth teeth 50A, 50B, 50C, 50D, 50E, 50F) and a plurality of flutes 52 (e.g. first, second, third, fourth, fifth, and sixth flutes 52A, 52B, 52C, 52D, 52E, 52F) alternating with the plurality of teeth 50.

[0088] Referring also to FIGS. 4 to 6, the teeth 50 and flutes 52 can be identical as shown, therefore a description below relating to any tooth or flute should be considered as relating to all.

[0089] The first tooth 50A can comprise a relief edge 54A, a convexly curved outer corner 56A, a primary cutting edge 58A, a convexly curved inner corner 60A, and a ramping cutting edge 62A.

[0090] The relief edge 54A can extend along the peripheral surface 32. The relief edge 54A can extend in a rearward-inward direction D.sub.R, D.sub.I from the outer corner 56A.

[0091] The outer corner 56A can be connected to the relief edge 54A and comprises a radial extremity point 57A of the cutting portion 36. An outer corner radius R.sub.OC can have a preferred yet exemplary value of 0.6 mm.

[0092] The primary cutting edge 58A can be connected to the outer corner 56A and can extend in a forward-inward direction D.sub.F, D.sub.I from the outer corner 56A. In cases where the cutting edge 58A is curved to a measurable extent, a preferred yet exemplary value of a cutting edge radius R.sub.CE thereof can be 10 mm.

[0093] The inner corner 60A can be connected to the primary cutting edge 58A.

[0094] The ramping cutting edge 62A can be connected to inner corner 60A and can extend in a rearward-inward direction D.sub.F, D.sub.I from the inner corner 60A.

[0095] More precisely, a first connection point 64A can be defined where the primary cutting edge 58A and the inner corner 60A connect, a second connection point 64B can be defined where the primary cutting edge 58A and the outer corner 56A connect.

[0096] An imaginary straight line L.sub.I can be defined between the first and second connection points 64A, 64B and together with the perpendicular plane P.sub.P can subtend a cutting angle α. In the present example, the cutting edge radius R.sub.CE is so large that the primary cutting edge 58A essentially overlaps with the imaginary straight line L.sub.I.

[0097] An effective cutting length L.sub.E can be defined from the second connection point 64B to the perpendicular plane P.sub.P.

[0098] Each tooth 50 can be positioned front-of-center as shown. To elaborate, with reference to FIG. 2, a head 14 can be rotated until a radial line L.sub.R intersects an intersection point P.sub.I of a primary cutting edge 58A, as is shown in this case for the first tooth 50A. The intersection point P.sub.I coincides with the start of the intended main cutting edge, i.e. the second connection point 64B. Notably, at points along the primary cutting edge 58A closer to the central rotation axis A.sub.R than the intersection point P.sub.I, the primary cutting edge 58A is in front of the radial line L.sub.R in the preceding direction D.sub.P (i.e. the cutting direction). Accordingly, as a chip (not shown) contacts the primary cutting edge 58A it is ejected away from the head 14, the basic direction being schematically shown by the arrow designated 66 (which is directed more towards the outward direction D.sub.O than the inward direction D.sub.I).

[0099] In FIG. 6 a lead-in-angle θ is shown.

[0100] A coolant hole 68 can open out to the front face 30.

[0101] Using the first flute 52A as an example, during a facing application, coolant exiting the coolant hole 68 (not shown) flows through adjacent teeth (e.g. in the direction shown by arrow 69) which can further assist ejection of chips (not shown) already propelled in the direction shown by arrow 66.

[0102] In FIG. 4 a helix angle H is shown. While the helix angle values for this type of head are not limited, a preferential range would fulfil the condition 10°≦H≦30°. With values closer to 20° being considered more preferred.

[0103] Reverting to FIG. 3, it is noted that the head 14 is configured with a fastening construction 70 along the peripheral surface 32. The exemplary fastening construction 70 comprises two identical flat recesses 72 on opposite sides of the head 14 (only one of which being shown) which are configured for engagement with a spanner (not shown).

[0104] Since a fastening construction 70 along the head peripheral surface 32 can require some of the cutting portion's length (i.e. the fastening construction 70 shown requires a fastening construction length L.sub.F), the head 14 can be lengthened to a greater cutting portion length L.sub.C than would strictly speaking be required for heat or machining purposes (i.e. such elongation being instead for ease of mounting the head 14 to the shank 12).

[0105] In the example shown the cutting portion length L.sub.C and cutting portion diameter D.sub.E are equal and hence LDR=1.00.