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EP-3129178-B1 - CUTTING TOOL AND CUTTING INSERT HAVING EXACTLY FOUR CUTTING PORTIONS THEREFOR

EP3129178B1EP 3129178 B1EP3129178 B1EP 3129178B1EP-3129178-B1

Inventors

  • HECHT, GIL

Dates

Publication Date
20260506
Application Date
20150312

Claims (15)

  1. An indexable cutting insert (20) comprising two opposing end surfaces (22) with a peripheral side surface (24) and a central axis (C) extending therebetween, and exactly four cutting portions (26), each of the four cutting portions (26) having a major cutting edge (28) formed by the intersection of a rake surface (30) and a relief surface (32), the peripheral side surface (24) having two pairs of opposing side surfaces (34, 36), a first pair of opposing side surfaces (34) including the four relief surfaces (32) and a second pair of opposing side surfaces (36) including the four rake surfaces (30), wherein in an end view: four cutting points (Nc) on the four major cutting edges (28) define the transitions between the first and second pairs of opposing side surfaces (34, 36), characterized in that , in the end view, a minimum first length dimension (L1) between the second pair of opposing side surfaces (36) is less than six-tenths of a minimum second length dimension (L2) between two of the four cutting points (Nc).
  2. The indexable cutting insert (20) according to claim 1, wherein each of the four cutting portions (26) has a radial plane (P R ) containing the central axis (C) and its respective cutting point (Nc), preferably wherein each radial plane (P R ) intersects the second pair of opposing side surfaces (36).
  3. The indexable cutting insert (20) according to claim 2, wherein each radial plane (P R ) is coplanar with another radial plane (P R ).
  4. The indexable cutting insert (20) according to claim 2 or 3, wherein the minimum first length dimension (L1) is measured along an imaginary first segment (S1) that does not intersect any of the four radial planes (P R ).
  5. The indexable cutting insert (20) according to any one of claims 2 to 4, wherein each radial plane (P R ) forms an acute relief angle (α1) with a straight imaginary relief line (L R ) coincident with or tangential to the relief surface (32) immediately adjacent its respective cutting point (Nc), and wherein the acute relief angle (α1) has a value equal to or greater than 75 degrees.
  6. The indexable cutting insert (20) according to any one of claims 2 to 5, wherein the four radial planes (P R ) define four imaginary insert regions (R1, R2, R3, R4), and wherein the four relief surfaces (32) are entirely located in non-adjacent first and third imaginary insert regions (R1, R3); preferably: wherein the second pair of opposing side surfaces (36) has four spaced apart abutment zones (38), and wherein each abutment zone (38) is entirely located in the first or third imaginary insert region (R1, R3).
  7. The indexable cutting insert (20) according to claim 6, wherein the two radial planes (P R ) defining the first imaginary insert region (R1) form an acute first region angle (β1), and the two radial planes (P R ) defining the third imaginary insert region (R3) form an acute third region angle (β3).
  8. The indexable cutting insert (20) according to any one of the preceding claims, wherein the four cutting points (Nc) define a first imaginary circle (C1) which circumscribes the peripheral side surface (24); preferably wherein in an end view: a first relief point (N P 1) on each relief surface (32) is located further from its respective cutting point (Nc) than a second relief point (N P 2) on the same relief surface (32), and the first relief point (N P 1) is located closer to the first imaginary circle (C1) than the second relief point (N P 2).
  9. The indexable cutting insert (20) according to any one of the preceding claims, wherein the minimum first length dimension (L1) is measured along an imaginary first segment (S1) that is parallel to an imaginary second segment (S2) along which the minimum second length dimension (L2) is measured.
  10. The indexable cutting insert (20) according to any one of the preceding claims, wherein the minimum first length dimension (L1) is measured along an imaginary first segment (S1) that is parallel to and offset from a vertical plane (Pv) containing the central axis (C); preferably wherein the cutting insert (20) exhibits mirror symmetry about the vertical plane (Pv).
  11. The indexable cutting insert (20) according to any one of the preceding claims, wherein each cutting portion (26) has two minor cutting edges (40), and wherein each minor cutting edge (40) extends away from its associated major cutting edge (28) in a direction towards a median plane (M) perpendicular to the central axis (C).
  12. A cutting tool (46) comprising an insert holder (48) and a cutting insert (20) in accordance with any one of the preceding claims retained therein, the insert holder (48) having a holding portion (52) extending along a longitudinal tool axis (L), the holding portion (52) having a seating surface (54) transverse to the longitudinal tool axis (L), and the cutting insert (20) removably securable to the insert holder (48) in any one of four index positions by a separate fastener (50), wherein exactly one cutting portion (26) is operative, and wherein one end surface (22) is in clamping contact with the seating surface (54).
  13. The cutting tool (46) according to claim 12, wherein the holding portion (52) has three reaction surfaces (60, 62, 64) adjacent the seating surface (54), wherein the second pair of opposing side surfaces (36) has exactly four spaced apart abutment zones (38), and wherein for each index position, three of the four abutment zones (38) are in clamping contact with the three reaction surfaces (60, 62, 64); preferably: wherein each of the four cutting portions (26) has a radial plane (P R ) containing the central axis (C) and its respective cutting point (Nc), wherein the four radial planes (P R ) define four imaginary insert regions (R1, R2, R3, R4), and the four relief surfaces (32) are entirely located in non-adjacent first and third imaginary insert regions (R1, R3), and wherein each abutment zone (38) is entirely located in the first or third imaginary insert region (R1, R3).
  14. The cutting tool (46) according to claim 13, wherein two spaced apart protuberances (58a, 58b) protrude from the seating surface (54), and wherein two of the three reaction surfaces (60, 62) are located on a first protuberance (58a) and the third reaction surface (64) is located on a second protuberance (58b).
  15. The cutting tool (46) according to any one of claims 12 to 14, wherein in an end view of the cutting tool (46), a second imaginary circle (C2) having a second diameter (D2) contains the cutting insert (20) and the entire holding portion (52), wherein the operative cutting portion (26) has a depth of insertion (D I ) perpendicular to the longitudinal tool axis (L), and wherein the depth of insertion (D I ) is equal to or greater than one-tenth of the second diameter (D2).

Description

FIELD OF THE INVENTION The present invention relates to metal cutting tools for use in groove turning and groove milling operations having an indexable cutting insert with a plurality of cutting portions. BACKGROUND OF THE INVENTION Within the field of metal cutting tools used in groove turning and groove milling operations, cutting inserts removably securable in an insert holder have long since provided a way of performing a cutting operation with a suitably hard material, i.e. cemented carbide, in the vicinity of the cutting edge, where the insert holder, manufactured from a less hard material, is reusable following the disposal of a worn or damaged cutting insert. This type of cutting tool has been further developed to utilize indexable cutting inserts with an increased number of cutting edges, giving economic benefits from providing an increased number of cutting operations per cutting insert. This type of cutting tool has also been developed to provide a more efficient means of securing the indexable insert to the insert holder. US 2012/0099935 discloses an indexable cutting insert having two opposing end surfaces, a peripheral side surface, and four cutting portions. The peripheral side surface has two pairs of opposing side surfaces, a first pair including four cutting portion relief surfaces, and a second pair including four cutting portion rake surfaces and four abutment zones. A minimum length dimension between the second pair of opposing side surfaces is coincident with a first plane about which the cutting insert exhibits mirror symmetry. For each index position of the cutting insert within an insert holder, three of the four abutment zones are in clamping contact with three reaction zones located on a sidewall surface of the insert holder. US 2014/0050542 discloses an indexable cutting insert having two opposing main surfaces, a peripheral side surface, and four cutting portions. The peripheral side surface has two pairs of opposing side surfaces, a first pair of short sides including four cutting portion relief surfaces and two positioning notches, and a second pair of long sides including four cutting portion rake surfaces and four locating surfaces. In a plan view of one of the main surfaces, it is clear that a radial plane containing any one of the four cutting edges does not intersect the second pair of long sides. For each index position of the cutting insert within an insert holder, one of the four locating surfaces is supported by a stop surface in an insert pocket of the holder, and one of the two positioning notches engages a positioning pin in the insert pocket. It is an object of the present invention to provide an improved indexable cutting insert having four cutting portions. It is also an object of the present invention to enable the cutting insert to be secured to a mating body with an efficient use of space. It is a further object of the present invention to provide robust support for the cutting insert's four cutting edges. It is yet a further object of the present invention to provide an improved cutting tool which can perform internal groove turning operations. It is still yet a further object of the present invention to provide a cutting tool configuration which enables undisturbed chip forming. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided an indexable cutting insert comprising two opposing end surfaces with a peripheral side surface and a central axis extending therebetween, and exactly four cutting portions, each of the four cutting portions having a major cutting edge formed by the intersection of a rake surface and a relief surface,the peripheral side surface having two pairs of opposing side surfaces, a first pair of opposing side surfaces including the four relief surfaces and a second pair of opposing side surfaces including the four rake surfaces,wherein in an end view: four cutting points on the four major cutting edges define the transitions between the first and second pairs of opposing side surfaces, and a minimum first length dimension between the second pair of opposing side surfaces is less than six-tenths of a minimum second length dimension between two of the four cutting points. Also in accordance with the present invention, there is provided a cutting tool comprising an insert holder and a cutting insert of the sort described above retained therein, the insert holder having a holding portion extending along a longitudinal tool axis, the holding portion having a seating surface transverse to the longitudinal tool axis, andthe cutting insert removably securable to the insert holder in any one of four index positions by a separate fastener,wherein exactly one cutting portion is operative, andwherein one end surface is in clamping contact with the seating surface. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding, the invention will now be described, by way of example only, with reference to the accompanying