Title of Invention	METAL CUTTING TOOL
Abstract	A metal cutting tool (10) having an indexable cutting insert (12) retained in an insert pocket (16) of an insert holder (14). The cutting insert has two opposing side surfaces (24) with a peripheral edge surface (26) extending therebetween and a plurality of cutting portions (32). The peripheral edge surface (26) has a plurality of abutment sections (28), each abutment section (28) lying on a portion of a sidewall of an imaginary regular polygon. A plurality of cutting portions (32) extend outwardly from the imaginary polygon and are equal in number to the number of side walls thereof. Each abutment section (28) is located between two cutting portions (32). The insert holder (14) has an insert pocket (16) in which the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28) by two support walls (20) of the insert pocket (16), the support walls (20) being fixed and integral parts of the insert holder(14). (

Title of Invention

METAL CUTTING TOOL

Abstract

A metal cutting tool (10) having an indexable cutting insert (12) retained in an insert pocket (16) of an insert holder (14). The cutting insert has two opposing side surfaces (24) with a peripheral edge surface (26) extending therebetween and a plurality of cutting portions (32). The peripheral edge surface (26) has a plurality of abutment sections (28), each abutment section (28) lying on a portion of a sidewall of an imaginary regular polygon. A plurality of cutting portions (32) extend outwardly from the imaginary polygon and are equal in number to the number of side walls thereof. Each abutment section (28) is located between two cutting portions (32). The insert holder (14) has an insert pocket (16) in which the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28) by two support walls (20) of the insert pocket (16), the support walls (20) being fixed and integral parts of the insert holder(14). (

Full Text	FIELD OF THE INVENTION The present invention relates to metal cutting tools for use in turning, grooving, parting, and threading operations having an indexable insert with a plurality of cutting edges. BACKGROUND OF THE INVENTION Metal cutting tools of this type are well known in the art. US Patent No. 4,320,996 discloses a cutoff tool that enables narrow grooves to be produced. The tool consists of a holder having a recess in one side face in which a cutting insert is located and clamped by means of a center screw threadably engageable with the holder. The insert is triangular and is provided with a protruding triangular central portion, which is received in the recess, whereas the remainder of the insert extends laterally from the holder for cutoff purposes. Since the insert has a protruding central portion, it is one-handed, that is, if the insert has been designed for a right-handed tool, as shown in US 4,320,996, then it can only be used with a right-handed tool. US Patent No. 4,169,690 discloses an indexable insert for heavy- duty capabilities. The cutting insert has a plurality of cutting edge portions extending outwardly from a central body portion. The insert is held in a pocket of a holder by a clamp arm either from the side or from the top. The existence of the clamp arm somewhat complicates the structure of the holder. US Patent No. 5,308,197 discloses a machining apparatus, comprising a holder bar with a pocket member that mounts on the bar that holds an insert. The insert has a mount portion and a plurality of arms. The mount portion locating sides bear against a pair of positioning sides of the pocket member. The pocket member complicates the production and use of the apparatus. Other disadvantages include a clamping system limiting the depth of cut. US Patent No. 3,613,197 discloses an indexable and reversible, threading or grooving insert. It includes an insert support that engages the insert at the lower cutting edge. The insert support screws to the tool body and engages the cutting arm in use, limiting depth of cut. US Patent Application Publication No. 2001/0022123 A1, describes in one embodiment (see Fig. 2) a holding element in which a cutting bit with four cutting edges sits on the holding element at three spaced apart locations 10", 10", and 10"". It is pointed out that the cutting bit can, in principle, also touch the holding element at a fourth location 10"" and that during use for the intended purpose a force is exerted on the cutting bit so that the bit would possibly no longer rest on the holding element at the location 10"". This means that in principle the cutting bit is not stably seated. The cutting bit would be in one position with 4 points of contact before use and then would move to another position with three points of contact during use. This is clearly disadvantageous because it means that the location of the cutting edge changes and is therefore not well defined. US patent No. US 4602897 discloses a cutting insert and, in one embodiment, a grooving cutter, is formed so that multiple cutting edges are disposed in the cutting path. Rectangular cutting inserts and radial cutting inserts are contemplated. The rectangular shape is most suited for small tools and equally so for internal applications. Multiple radial cutting inserts can be mounted equally radially disposed, but differently angularly disposed from each other, for providing a grooving cutter. The cutting inserts and tool assemblies thereof may be used for OD grooving, threading, relieving, trepanning, face grooving, slotting and milling. It is an object of the present invention to provide a new metal cutting tool, primarily for grooving, parting and turning operations, comprising an indexable cutting insert having a plurality of cutting edges, wherein the cutting insert can be used for either right or left handed cutting operations and wherein the above-referred-to difficulties and disadvantages are significantly reduced. It is another object of the present invention to provide the metal cutting tool, wherein the cutting insert is positively secured in a well-defined position without necessitating the use of an external clamp. SUMMARY OF THE INVENTION In accordance with the present invention there is provided a metal cutting tool comprising: an indexable cutting insert, comprising two opposing side surfaces, and a peripheral edge surface extending therebetween and having an insert axis of rotational symmetry passing through the side surfaces; the peripheral edge surface having a plurality of abutment sections, each abutment section lying on a portion of a side wall of an imaginary regular polygon having a plurality of side walls, a plurality of cutting portions extending outwardly from the imaginary polygon, the plurality of cutting portions being equal in number to the number of side walls of the imaginary polygon, each cutting portion having a cutting edge, each abutment section being located between two cutting portions; and an insert holder comprising an insert pocket in which the cutting insert is retained with the peripheral edge surface being abutted at two abutment sections only, the insert pocket comprising a lower support wall abutting a first abutment section, and an upper support wall abutting a second abutment section; the lower support wall and the upper support wall each being fixed and integral parts of the insert holder. In accordance with the present invention, the upper support wall and the lower support wall define an acute angle a between them. In accordance with a specific application, the acute angle a is 36°. In accordance with a preferred embodiment of the present invention, the cutting portions are generally triangular in a side view of the cutting insert. In a preferred application of the present invention, the cutting tool is for grooving, parting and turning. In accordance with a preferred embodiment of the present invention, the cutting insert has a varying width dimension, taken in a direction parallel to the insert axis. Preferably, the cutting insert has three width dimensions, a first width dimension, D1, at the cutting portions, a second width dimension, D2, at a generally centrally located region of the cutting insert and a third width dimension D3, at all other regions of the cutting insert. Further preferably, the second width dimension D2 is greater than the first width dimension D1, and the first width dimension Dl is greater than the third width dimension D3. Still further preferably, the generally centrally located region of the cutting insert having the second width dimension is polygonal in form, from a side view of the cutting insert, thereby forming a protruding polygon from each side surface. Typically, the imaginary polygon has a polygon axis that is coincident with the insert axis. If desired the protruding polygon is angularly offset from the imaginary polygon with respect to the insert axis. In accordance with a preferred embodiment present invention, the regular imaginary polygon is a regular imaginary pentagon; the cutting insert having five abutment sections, each abutment section lying on a portion of a side wall of the imaginary regular pentagon; five cutting portions spaced at regular intervals one from the other; and the protruding polygons are protruding pentagons, each protruding pentagon having an area smaller than a surface area of the imaginary pentagon and each protruding pentagon is angularly offset with respect to the imaginary pentagon. In accordance with the present invention, the insert pocket comprises a base surface from which the lower and upper support walls generally uprightly extend, the base surface being abutted by a given protruding polygon of the cutting insert. In accordance with the present invention, the cutting tool further comprises a screw, for securing the insert in the insert pocket, the screw extending through an insert through bore and threadingly engaged with a threaded receiving bore in the base surface; the insert through bore extending between the two opposing side surfaces. Tn accordance with the present invention, the insert through bore extends between the protruding polygons. In accordance with the preferred embodiment present invention, the operative first and second abutment sections divide the cutting insert into two sections. Further in accordance with the preferred embodiment present invention, a first section contains an operative cutting portion and two cutting portions on either side of the operative cutting portion and a second section contains two adjacent cutting portions. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS For a better understanding, the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is an perspective view of a metal cutting tool in accordance with the present invention; Fig. 2 is an perspective view of an insert holder in accordance with the present invention; Fig. 3 is a side view of the metal cutting tool shown in Fig. 1; and Fig. 4 is an edge-on view of the cutting insert shown in Fig 1. DETAILED DESCRIPTION OF THE INVENTION Attention is first drawn to Figs. 1-3, showing a metal cutting tool 10 in accordance with the present invention. The metal cutting tool 10 comprises a cutting insert 12, having an insert axis A, and an insert holder 14 with the cutting insert 12 retained in an insert pocket 16 (16", 16") of the insert holder 14. The cutting insert 12 is produced by form pressing and sintering a hard metal body made from a carbide powder such as Tungsten Carbide. However, the cutting insert 12 can also be produced by injection molding. The insert holder 14 is formed of machined steel or other hard materials. The insert holder 14, shown in Fig. 2, has two insert pockets 16, one 16" for right-handed cutting operations and the other 16" for left-handed cutting operations. The cutting insert 12, which will be described in detail below, can be used for both right-handed and left- handed cutting operations and as such can be retained in either of the insert pockets 16", 16". The insert axis A is an axis of rotational symmetry about which the cutting insert 12 has five-fold rotational symmetry. The insert pocket 16 comprises a base surface 18, a lower support wall 20 extending generally uprightly from the base surface 18, and an upper support 22 wall also extending generally uprightly from the base surface 18. The upper support wall 22 and lower support wall 20 form an acute angle a between them. In accordance with a specific application, the acute angle a is 36°, within manufacturing tolerances. The lower and upper support walls 20, 22 are integrally formed with the base surface 18. Attention is now additionally drawn to Fig. 4. The cutting insert 12 comprises two identical opposing side surfaces 24 and a peripheral edge surface 26 extending therebetween. Since the side surfaces 24 are identical, only one will be described, it being understood that the other side surface has identical structure. The peripheral edge surface 26 has five abutment sections 28 and five equally spaced apart cutting portions 32. Each of the five abutment sections 28 lies on a portion of a side wall 34 of an imaginary regular pentagon 36 (shown by a dashed line in Fig. 3) and are separated from one another by a given cutting portion 32. Each cutting portion 32 of the cutting insert 12 is triangular shaped and extends outwardly from the imaginary regular pentagon 36 of the cutting insert 12. At a radially outermost portion of each cutting portion 32 a cutting edge 38 is formed at the intersection of a rake surface 40, on a leading side 41 of the cutting portion 32, and a relief surface 42, a trailing side 43 of the cutting portion 32. The leading and trailing sides 41, 43 of the cutting portion 32 are not radially directed. As can be seen, the cutting edges 38 are radially more distant from the insert axis A than the abutment sections 28. The rake and relief surfaces 40 and 42 being located on the peripheral edge surface 26. An operative cutting portion 32" projects from an end surface 44 (in Fig. 3 shown by a line of short dashes) of the insert holder 14 to cut a workpiece (not shown). An operative first abutment section 28" abuts the lower support wall 20, and an operative second abutment section 28" abuts the upper support wall 22. Clearly, the operative first and second abutment sections 28", 28" form an angle between them substantially equal to the angle a. Apart from the operative first and second abutment sections 28", 28" no other portion of the peripheral edge surface 26 comes into contact with the insert holder 14. The operative first and second abutment sections 28", 28" divide the cutting insert 12 into two sections. A first section contains the operative cutting portion 32" and two cutting portions 32 on either side of the operative cutting portion 32". The second section contains two adjacent cutting portions 32. As can be seen, each side surface 24 has a centrally located outwardly protruding portion in the form of a protruding pentagon 46 having a flat surface 50. The flat surfaces 50 of each protruding pentagon 46 are parallel to each other. The flat surface 50 of the protruding pentagon 46 is smaller in surface area than the imaginary pentagon 36. The surface 50 of the protruding pentagon 46 abuts the base surface 18 of the insert pocket 16. The protruding pentagon 46 is also angularly offset with respect to the imaginary pentagon about the insert axis A, such that a given side wall 52 of the protruding pentagon 46 is coplanar with the end surface 44 of the insert holder 14. This offset maximizes the contact area between the insert 12 and the insert holder 14 without reducing the depth of cut. The cutting insert 12 has three width dimensions. A first width dimension D1, being the width of the cutting portion 32. A generally centrally located region of the cutting insert 12 has a second width dimension D2 between the flat surfaces 50 of the two protruding pentagons 46. A third width dimension D3, is defined by all other regions of the cutting insert 12 not included in the first and second width dimensions D1, D2. The second width dimension D2 is greater than the first width dimension D1, which ensures the cutting edge 38 does not abut the base surface 18 of the insert pocket 16. It will be appreciated that the cutting portion 32 slightly tapers inwardly from the cutting edge 38. That is, the first width dimension D1 is slightly variable, having a maximum value at the cutting edge 38 and decreasing in magnitude inwardly towards the insert axis A. This arrangement assures that the sides 24 of the cutting portions 32 are relieved from a workpiece during cutting operations. An insert through bore 56 extends between the flat surface 50 of the protruding pentagon 46 and has a bore axis that is coincident with the insert axis A. The insert through bore 56 is countersunk on both sides. A screw 54 extends through the insert through bore 56 and threadingly engages a threaded receiving bore 57 in the base surface 18 of the insert pocket 16. The lower support wall 20, the upper support wall 22, and the base surface 18 of the insert holder 14 and the screw 54 positively lock the cutting insert 12 in the insert pocket 16. The relative positioning of the lower support wall 20 and the upper support wall 22 are such that cutting forces exerted on the operative cutting portion 32" during cutting operations are exerted primarily on the lower support wall 20 and on the upper support wall 22 and only minimally on the screw 54. This removes the need for additional structure, such as a clamp, to positively lock the cutting insert 12 and limits the possibility of failure by the screw 54. Although the present invention has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the spirit or scope of the invention as hereinafter claimed. For example, a cutting insert could have four or six or more cutting portions instead of five. The width dimensions D1, D2, and D3 can be changed to suit various applications. Furthermore, it will be appreciated that the present invention can also be applied to threading operations. The angle a may be modified to suit other geometrical configurations. A lever or pin mechanism could be used in place of the screw. WE CLAIM 1. A metal cutting tool (10) comprising : an indexable cutting insert (12), comprising two opposing side surfaces (24), and a peripheral edge surface (26) extending therebetween and having an insert axis (A) of rotational symmetry passing through the side surfaces (24); the peripheral edge surface (26) having a plurality of abutment sections (28, 28", 28") lying on a portion of a side wall (34) of an imaginary regular polygon (36) having a plurality of side walls (34), a plurality of cutting portions (32) extending outwardly from the imaginary polygon (36), the plurality of cutting portions (32) being equal in number to the number of side walls (34) of the imaginary polygon (36), each cutting portion (32) having a cutting edge (38), each abutment section (28, 28", 28") being located between two cutting portions (32); and an insert holder (14) comprising an insert pocket (16, 16", 16") in which the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28", 28") only, the insert pocket (16, 16", 16") comprising a lower support wall (20) abutting a first abutment section (280 and an upper support wall (22) abutting a second abutment section (28"); the lower support wall (20) and the upper support wall (22) each being fixed and integral parts of the insert holder (14), and the upper support wall (22) each being fixed and integral parts of the insert holder (14), and upper support wall (22) and the lower support wall (20) define an acute angle (a) between them. 2. The metal cutting tool (10) as claimed in claim 1, wherein the acute angle (a) is 36°. 3. The metal cutting tool (10) as claimed in claim 1, wherein the cutting portions (32) are generally triangular in a view of the cutting insert (12). 4. The metal cutting tool (10) as claimed in claim 1, wherein the cutting tool (10) is for grooving, parting and turning. 5. The metal cutting tool (10) as claimed in claim 1, wherein the cutting insert (12) has a varying dimension (Dl, D2, D3) taken in a direction parallel to the insert axis (A). 6. The metal cutting tool (10) as claimed in claim 5, wherein the cutting insert (12) has three width dimensions, a first width dimension (Dl) at the cutting portions (32), a second width dimension (D2) at a generally centrally located region of the cutting insert (12) and a third width dimension (D3) at all other regions of the cutting insert (12). 7. The metal cutting tool (10) as claimed in claim 6, wherein the second width dimension (D2) is greater than the first width dimension (D1), and the first width dimension (D1) is greater than the third width dimension (D3). 8. The metal cutting tool (10) as claimed in claim 7, wherein the generally centrally located region of the cutting insert (12) having the second width dimension (d2) is polygonal in form from a side view of the cutting insert (12), thereby forming a protruding polygon (46) from each side surface (24). 9. The metal cutting tool (10) as claimed in claim 8, wherein the imaginary polygon (36) has a polygon axis coincident with the insert axis (A). 10.The metal cutting tool (10) as claimed in claim 9, wherein the protruding polygon (46) is angularly offset from the imaginary polygon (36) with respect to the insert axis (A). 11.The metal cutting tool (10) as claimed in claim 10, wherein the regular imaginary polygon (36) is a regular imaginary pentagon (36); the cutting insert (12) has five abutment sections (28, 28", 28"), each abutment section (28, 28", 28") lying on a portion of a side wall (34) of the imaginary regular pentagon (36); five cutting portions (32) spaced at regular intervals one from other; and the protruding polygons (46) are protruding pentagons (46), each protruding pentagon (46) having an area smaller than a surface area of the imaginary pentagon (36) and each protruding pentagon (46) is angularly offset with respect to the imaginary pentagon (36). 12.The metal cutting tool (10) as claimed in claim 8, wherein the insert pocket (16, 16" 16") comprises a base surface (18) from which the lower and upper support walls (20, 22) generally uprightly extend, the base surface (18) being abutted by a given protruding polygon (46) of the cutting insert (12). 13.The metal cutting tool (10) as claimed in claim 12, wherein the cutting tool (10) further comprises a screw (54), for securing the cutting insert (12) in the insert pocket (16, 16", 16") the screw (54) extending through an insert through bore (546) and threadingly engaging a threaded receiving bore (57) in the base surface (18); the insert through bore (56) extending between the two opposing side surfaces (24). 14.The metal cutting tool (10) as claimed in claim 13, wherein the insert through bore (56) extends between the protruding polygons (46). 15.The metal cutting tool (10) as claimed in claim 11, wherein the first and second abutment sections (28) divide the cutting insert (12) into two sections. 16.The metal cutting tool (10) as claimed in claim 15, wherein a first section contains an operative cutting portion (32") and two portions (32) on either side of the operative cutting portion (32") and a second contains two adjacent cutting portions (32). This invention relates to a metal cutting tool (10) comprising an indexable cutting insert (12), comprising two opposing side surfaces (24), and a peripheral edge surface (26) extending therebetween and having an insert axis (A) of rotational symmetry passing through the side surfaces (24); the peripheral edge surface (26) having a plurality of abutment sections (28, 28", 28") lying on a portion of a side wall (34) of an imaginary regular polygon (36) having a plurality of side walls (34), a plurality of cutting portions (32) extending outwardly from the imaginary polygon (36), the plurality of cutting portions (32) being equal in number to the number of side walls (34) of the imaginary polygon (36), each cutting portion (32) having a cutting edge (38), each abutment section (28, 28", 28") being located between two cutting portions (32); and an insert holder (14) comprising an insert pocket (16, 16", 16") in which the cutting insert (12) is retained with the peripheral edge surface (26) being abutted at two abutment sections (28", 28") only, the insert pocket (16, 16", 16") comprising a lower support wall (20) abutting a first abutment section (28") and an upper support wall (22) abutting a second abutment section (28"); the lower support wall (20) and the upper support wall (22) each being fixed and integral parts of the insert holder (14), and upper support wall (22) and the lower support wall (20) define an acute angle (a) between them.

Full Text

FIELD OF THE INVENTION
The present invention relates to metal cutting tools for use in turning,
grooving, parting, and threading operations having an indexable insert with a
plurality of cutting edges.
BACKGROUND OF THE INVENTION
Metal cutting tools of this type are well known in the art. US
Patent No. 4,320,996 discloses a cutoff tool that enables narrow grooves to be
produced. The tool consists of a holder having a recess in one side face in which
a cutting insert is located and clamped by means of a center screw threadably
engageable with the holder. The insert is triangular and is provided with a
protruding triangular central portion, which is received in the recess, whereas the
remainder of the insert extends laterally from the holder for cutoff purposes.
Since the insert has a protruding central portion, it is one-handed, that is, if the
insert has been designed for a right-handed tool, as shown in US 4,320,996, then
it can only be used with a right-handed tool.
US Patent No. 4,169,690 discloses an indexable insert for heavy-
duty capabilities. The cutting insert has a plurality of cutting edge portions
extending outwardly from a central body portion. The insert is held in a pocket of
a holder by a clamp arm either from the side or from the top. The existence of
the clamp arm somewhat complicates the structure of the holder.
US Patent No. 5,308,197 discloses a machining apparatus, comprising a holder
bar with a pocket member that mounts on the bar that holds an insert. The
insert has a mount portion and a plurality of arms. The mount portion locating
sides bear against a pair of positioning sides of the pocket member. The pocket
member complicates the production and use of the apparatus. Other
disadvantages include a clamping system limiting the depth of cut.
US Patent No. 3,613,197 discloses an indexable and reversible, threading or
grooving insert. It includes an insert support that engages the insert at the lower
cutting edge. The insert support screws to the tool body and engages the cutting
arm in use, limiting depth of cut.
US Patent Application Publication No. 2001/0022123 A1, describes in one
embodiment (see Fig. 2) a holding element in which a cutting bit with four
cutting edges sits on the holding element at three spaced apart locations 10",
10", and 10"". It is pointed out that the cutting bit can, in principle, also touch
the holding element at a fourth location 10"" and that during use for the
intended purpose a force is exerted on the cutting bit so that the bit would
possibly no longer rest on the holding element at the location 10"". This means
that in principle the cutting bit is not stably seated. The cutting bit would be in
one position with 4 points of contact before use and then would move to another
position with three points of contact during use. This is clearly disadvantageous
because it means that the location of the cutting edge changes and is therefore
not well defined.
US patent No. US 4602897 discloses a cutting insert and, in one embodiment, a
grooving cutter, is formed so that multiple cutting edges are disposed in the
cutting path. Rectangular cutting inserts and radial cutting inserts are
contemplated. The rectangular shape is most suited for small tools and equally
so for internal applications. Multiple radial cutting inserts can be mounted equally
radially disposed, but differently angularly disposed from each other, for
providing a grooving cutter. The cutting inserts and tool assemblies thereof may
be used for OD grooving, threading, relieving, trepanning, face grooving, slotting
and milling.
It is an object of the present invention to provide a new metal cutting tool,
primarily for grooving, parting and turning operations, comprising an indexable
cutting insert having a plurality of cutting edges, wherein the cutting
insert can be used for either right or left handed cutting operations and wherein the
above-referred-to difficulties and disadvantages are significantly reduced.
It is another object of the present invention to provide the metal
cutting tool, wherein the cutting insert is positively secured in a well-defined
position without necessitating the use of an external clamp.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a metal
cutting tool comprising:
an indexable cutting insert, comprising two opposing side surfaces, and a
peripheral edge surface extending therebetween and having an insert axis of
rotational symmetry passing through the side surfaces; the peripheral edge
surface having a plurality of abutment sections, each abutment section lying on a
portion of a side wall of an imaginary regular polygon having a plurality of side
walls, a plurality of cutting portions extending outwardly from the imaginary
polygon, the plurality of cutting portions being equal in number to the number of
side walls of the imaginary polygon, each cutting portion having a cutting edge,
each abutment section being located between two cutting portions; and
an insert holder comprising an insert pocket in which the cutting insert is
retained with the peripheral edge surface being abutted at two abutment sections
only, the insert pocket comprising a lower support wall abutting a first abutment
section, and an upper support wall abutting a second abutment section; the lower
support wall and the upper support wall each being fixed and integral parts of the
insert holder.
In accordance with the present invention, the upper support wall
and the lower support wall define an acute angle a between them.
In accordance with a specific application, the acute angle a is 36°.
In accordance with a preferred embodiment of the present
invention, the cutting portions are generally triangular in a side view of the
cutting insert.
In a preferred application of the present invention, the cutting tool
is for grooving, parting and turning.
In accordance with a preferred embodiment of the present
invention, the cutting insert has a varying width dimension, taken in a direction
parallel to the insert axis.
Preferably, the cutting insert has three width dimensions, a first
width dimension, D1, at the cutting portions, a second width dimension, D2, at a
generally centrally located region of the cutting insert and a third width
dimension D3, at all other regions of the cutting insert.
Further preferably, the second width dimension D2 is greater than
the first width dimension D1, and the first width dimension Dl is greater than the
third width dimension D3.
Still further preferably, the generally centrally located region of the
cutting insert having the second width dimension is polygonal in form, from a
side view of the cutting insert, thereby forming a protruding polygon from each
side surface.
Typically, the imaginary polygon has a polygon axis that is
coincident with the insert axis.
If desired the protruding polygon is angularly offset from the
imaginary polygon with respect to the insert axis.
In accordance with a preferred embodiment present invention, the
regular imaginary polygon is a regular imaginary pentagon; the cutting insert
having five abutment sections, each abutment section lying on a portion of a side
wall of the imaginary regular pentagon; five cutting portions spaced at regular
intervals one from the other; and the protruding polygons are protruding
pentagons, each protruding pentagon having an area smaller than a surface area
of the imaginary pentagon and each protruding pentagon is angularly offset with
respect to the imaginary pentagon.
In accordance with the present invention, the insert pocket
comprises a base surface from which the lower and upper support walls generally
uprightly extend, the base surface being abutted by a given protruding polygon of
the cutting insert.
In accordance with the present invention, the cutting tool further
comprises a screw, for securing the insert in the insert pocket, the screw
extending through an insert through bore and threadingly engaged with a
threaded receiving bore in the base surface; the insert through bore extending
between the two opposing side surfaces.
Tn accordance with the present invention, the insert through bore
extends between the protruding polygons.
In accordance with the preferred embodiment present invention, the
operative first and second abutment sections divide the cutting insert into two
sections.
Further in accordance with the preferred embodiment present
invention, a first section contains an operative cutting portion and two cutting
portions on either side of the operative cutting portion and a second section
contains two adjacent cutting portions.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
For a better understanding, the invention will now be described, by
way of example only, with reference to the accompanying drawings in which:
Fig. 1 is an perspective view of a metal cutting tool in accordance with the
present invention;
Fig. 2 is an perspective view of an insert holder in accordance with the
present invention;
Fig. 3 is a side view of the metal cutting tool shown in Fig. 1; and
Fig. 4 is an edge-on view of the cutting insert shown in Fig 1.
DETAILED DESCRIPTION OF THE INVENTION
Attention is first drawn to Figs. 1-3, showing a metal cutting tool
10 in accordance with the present invention. The metal cutting tool 10 comprises
a cutting insert 12, having an insert axis A, and an insert holder 14 with the
cutting insert 12 retained in an insert pocket 16 (16", 16") of the insert holder 14.
The cutting insert 12 is produced by form pressing and sintering a hard metal
body made from a carbide powder such as Tungsten Carbide. However, the
cutting insert 12 can also be produced by injection molding. The insert holder 14
is formed of machined steel or other hard materials. The insert holder 14, shown
in Fig. 2, has two insert pockets 16, one 16" for right-handed cutting operations
and the other 16" for left-handed cutting operations. The cutting insert 12, which
will be described in detail below, can be used for both right-handed and left-
handed cutting operations and as such can be retained in either of the insert
pockets 16", 16". The insert axis A is an axis of rotational symmetry about
which the cutting insert 12 has five-fold rotational symmetry.
The insert pocket 16 comprises a base surface 18, a lower support
wall 20 extending generally uprightly from the base surface 18, and an upper
support 22 wall also extending generally uprightly from the base surface 18. The
upper support wall 22 and lower support wall 20 form an acute angle a between
them. In accordance with a specific application, the acute angle a is 36°, within
manufacturing tolerances. The lower and upper support walls 20, 22 are
integrally formed with the base surface 18.
Attention is now additionally drawn to Fig. 4. The cutting insert 12
comprises two identical opposing side surfaces 24 and a peripheral edge surface
26 extending therebetween. Since the side surfaces 24 are identical, only one
will be described, it being understood that the other side surface has identical
structure. The peripheral edge surface 26 has five abutment sections 28 and five
equally spaced apart cutting portions 32. Each of the five abutment sections 28
lies on a portion of a side wall 34 of an imaginary regular pentagon 36 (shown by
a dashed line in Fig. 3) and are separated from one another by a given cutting
portion 32.
Each cutting portion 32 of the cutting insert 12 is triangular shaped
and extends outwardly from the imaginary regular pentagon 36 of the cutting
insert 12. At a radially outermost portion of each cutting portion 32 a cutting
edge 38 is formed at the intersection of a rake surface 40, on a leading side 41 of
the cutting portion 32, and a relief surface 42, a trailing side 43 of the cutting
portion 32. The leading and trailing sides 41, 43 of the cutting portion 32 are not
radially directed. As can be seen, the cutting edges 38 are radially more distant
from the insert axis A than the abutment sections 28. The rake and relief
surfaces 40 and 42 being located on the peripheral edge surface 26. An operative
cutting portion 32" projects from an end surface 44 (in Fig. 3 shown by a line of
short dashes) of the insert holder 14 to cut a workpiece (not shown). An
operative first abutment section 28" abuts the lower support wall 20, and an
operative second abutment section 28" abuts the upper support wall 22. Clearly,
the operative first and second abutment sections 28", 28" form an angle between
them substantially equal to the angle a. Apart from the operative first and second
abutment sections 28", 28" no other portion of the peripheral edge surface 26
comes into contact with the insert holder 14. The operative first and second
abutment sections 28", 28" divide the cutting insert 12 into two sections. A first
section contains the operative cutting portion 32" and two cutting portions 32 on
either side of the operative cutting portion 32". The second section contains two
adjacent cutting portions 32.
As can be seen, each side surface 24 has a centrally located
outwardly protruding portion in the form of a protruding pentagon 46 having a
flat surface 50. The flat surfaces 50 of each protruding pentagon 46 are parallel
to each other. The flat surface 50 of the protruding pentagon 46 is smaller in
surface area than the imaginary pentagon 36. The surface 50 of the protruding
pentagon 46 abuts the base surface 18 of the insert pocket 16. The protruding
pentagon 46 is also angularly offset with respect to the imaginary pentagon about
the insert axis A, such that a given side wall 52 of the protruding pentagon 46 is
coplanar with the end surface 44 of the insert holder 14. This offset maximizes
the contact area between the insert 12 and the insert holder 14 without reducing
the depth of cut.
The cutting insert 12 has three width dimensions. A first width
dimension D1, being the width of the cutting portion 32. A generally centrally
located region of the cutting insert 12 has a second width dimension D2 between
the flat surfaces 50 of the two protruding pentagons 46. A third width dimension
D3, is defined by all other regions of the cutting insert 12 not included in the first
and second width dimensions D1, D2. The second width dimension D2 is greater
than the first width dimension D1, which ensures the cutting edge 38 does not
abut the base surface 18 of the insert pocket 16. It will be appreciated that the
cutting portion 32 slightly tapers inwardly from the cutting edge 38. That is, the
first width dimension D1 is slightly variable, having a maximum value at the
cutting edge 38 and decreasing in magnitude inwardly towards the insert axis A.
This arrangement assures that the sides 24 of the cutting portions 32 are relieved
from a workpiece during cutting operations.
An insert through bore 56 extends between the flat surface 50 of
the protruding pentagon 46 and has a bore axis that is coincident with the insert
axis A. The insert through bore 56 is countersunk on both sides. A screw 54
extends through the insert through bore 56 and threadingly engages a threaded
receiving bore 57 in the base surface 18 of the insert pocket 16.
The lower support wall 20, the upper support wall 22, and the base
surface 18 of the insert holder 14 and the screw 54 positively lock the cutting
insert 12 in the insert pocket 16. The relative positioning of the lower support
wall 20 and the upper support wall 22 are such that cutting forces exerted on the
operative cutting portion 32" during cutting operations are exerted primarily on
the lower support wall 20 and on the upper support wall 22 and only minimally
on the screw 54. This removes the need for additional structure, such as a clamp,
to positively lock the cutting insert 12 and limits the possibility of failure by the
screw 54.
Although the present invention has been described to a certain
degree of particularity, it should be understood that various alterations and
modifications could be made without departing from the spirit or scope of the
invention as hereinafter claimed. For example, a cutting insert could have four or
six or more cutting portions instead of five. The width dimensions D1, D2, and
D3 can be changed to suit various applications. Furthermore, it will be
appreciated that the present invention can also be applied to threading operations.
The angle a may be modified to suit other geometrical configurations. A lever or
pin mechanism could be used in place of the screw.
WE CLAIM
1. A metal cutting tool (10) comprising :
an indexable cutting insert (12), comprising two opposing side surfaces
(24), and a peripheral edge surface (26) extending therebetween and
having an insert axis (A) of rotational symmetry passing through the side
surfaces (24); the peripheral edge surface (26) having a plurality of
abutment sections (28, 28", 28") lying on a portion of a side wall (34) of
an imaginary regular polygon (36) having a plurality of side walls (34), a
plurality of cutting portions (32) extending outwardly from the imaginary
polygon (36), the plurality of cutting portions (32) being equal in number
to the number of side walls (34) of the imaginary polygon (36), each
cutting portion (32) having a cutting edge (38), each abutment section
(28, 28", 28") being located between two cutting portions (32); and
an insert holder (14) comprising an insert pocket (16, 16", 16") in which
the cutting insert (12) is retained with the peripheral edge surface (26)
being abutted at two abutment sections (28", 28") only, the insert pocket
(16, 16", 16") comprising a lower support wall (20) abutting a first
abutment section (280 and an upper support wall (22) abutting a second
abutment section (28"); the lower support wall (20) and the upper
support wall (22) each being fixed and integral parts of the insert holder
(14), and
the upper support wall (22) each being fixed and integral parts of the
insert holder (14), and upper support wall (22) and the lower support wall
(20) define an acute angle (a) between them.
2. The metal cutting tool (10) as claimed in claim 1, wherein the acute angle
(a) is 36°.
3. The metal cutting tool (10) as claimed in claim 1, wherein the cutting
portions (32) are generally triangular in a view of the cutting insert (12).
4. The metal cutting tool (10) as claimed in claim 1, wherein the cutting tool
(10) is for grooving, parting and turning.
5. The metal cutting tool (10) as claimed in claim 1, wherein the cutting
insert (12) has a varying dimension (Dl, D2, D3) taken in a direction
parallel to the insert axis (A).
6. The metal cutting tool (10) as claimed in claim 5, wherein the cutting
insert (12) has three width dimensions, a first width dimension (Dl) at the
cutting portions (32), a second width dimension (D2) at a generally
centrally located region of the cutting insert (12) and a third width
dimension (D3) at all other regions of the cutting insert (12).
7. The metal cutting tool (10) as claimed in claim 6, wherein the second
width dimension (D2) is greater than the first width dimension (D1), and
the first width dimension (D1) is greater than the third width dimension
(D3).
8. The metal cutting tool (10) as claimed in claim 7, wherein the generally
centrally located region of the cutting insert (12) having the second width
dimension (d2) is polygonal in form from a side view of the cutting insert
(12), thereby forming a protruding polygon (46) from each side surface
(24).
9. The metal cutting tool (10) as claimed in claim 8, wherein the imaginary
polygon (36) has a polygon axis coincident with the insert axis (A).
10.The metal cutting tool (10) as claimed in claim 9, wherein the protruding
polygon (46) is angularly offset from the imaginary polygon (36) with
respect to the insert axis (A).
11.The metal cutting tool (10) as claimed in claim 10, wherein the regular
imaginary polygon (36) is a regular imaginary pentagon (36);
the cutting insert (12) has five abutment sections (28, 28", 28"), each
abutment section (28, 28", 28") lying on a portion of a side wall (34) of
the imaginary regular pentagon (36); five cutting portions (32) spaced at
regular intervals one from other; and the protruding polygons (46) are
protruding pentagons (46), each protruding pentagon (46) having an area
smaller than a surface area of the imaginary pentagon (36) and each
protruding pentagon (46) is angularly offset with respect to the imaginary
pentagon (36).
12.The metal cutting tool (10) as claimed in claim 8, wherein the insert
pocket (16, 16" 16") comprises a base surface (18) from which the lower
and upper support walls (20, 22) generally uprightly extend, the base
surface (18) being abutted by a given protruding polygon (46) of the
cutting insert (12).
13.The metal cutting tool (10) as claimed in claim 12, wherein the cutting
tool (10) further comprises a screw (54), for securing the cutting insert
(12) in the insert pocket (16, 16", 16") the screw (54) extending through
an insert through bore (546) and threadingly engaging a threaded
receiving bore (57) in the base surface (18); the insert through bore (56)
extending between the two opposing side surfaces (24).
14.The metal cutting tool (10) as claimed in claim 13, wherein the insert
through bore (56) extends between the protruding polygons (46).
15.The metal cutting tool (10) as claimed in claim 11, wherein the first and
second abutment sections (28) divide the cutting insert (12) into two
sections.
16.The metal cutting tool (10) as claimed in claim 15, wherein a first section
contains an operative cutting portion (32") and two portions (32) on either
side of the operative cutting portion (32") and a second contains two
adjacent cutting portions (32).
This invention relates to a metal cutting tool (10) comprising an indexable
cutting insert (12), comprising two opposing side surfaces (24), and a peripheral
edge surface (26) extending therebetween and having an insert axis (A) of
rotational symmetry passing through the side surfaces (24); the peripheral edge
surface (26) having a plurality of abutment sections (28, 28", 28") lying on a
portion of a side wall (34) of an imaginary regular polygon (36) having a plurality
of side walls (34), a plurality of cutting portions (32) extending outwardly from
the imaginary polygon (36), the plurality of cutting portions (32) being equal in
number to the number of side walls (34) of the imaginary polygon (36), each
cutting portion (32) having a cutting edge (38), each abutment section (28, 28",
28") being located between two cutting portions (32); and an insert holder (14)
comprising an insert pocket (16, 16", 16") in which the cutting insert (12) is
retained with the peripheral edge surface (26) being abutted at two abutment
sections (28", 28") only, the insert pocket (16, 16", 16") comprising a lower
support wall (20) abutting a first abutment section (28") and an upper support
wall (22) abutting a second abutment section (28"); the lower support wall (20)
and the upper support wall (22) each being fixed and integral parts of the insert
holder (14), and upper support wall (22) and the lower support wall (20) define
an acute angle (a) between them.

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Patent Number

212690

Indian Patent Application Number

01151/KOLNP/2004

PG Journal Number

50/2007

Publication Date

14-Dec-2007

Grant Date

12-Dec-2007

Date of Filing

10-Aug-2004

Name of Patentee

ISCAR LTD.

Applicant Address

P.O-BOX. 24959 ISRAELI

Inventors:

#	Inventor's Name	Inventor's Address
1	FRIEDMAN JACOB	EREZ STREET 5, 25147 KFAR VRADIM.
2	THORNTON JAY E	56 LINCOLN STREET, WATEROWN, MA 02472, UNITED STATES OF AMERICA.

PCT International Classification Number

B23B 27/08

PCT International Application Number

PCT/IL03/00051

PCT International Filing date

2003-01-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10/147,198	2002-05-16	Israel
2	148228	2002-02-19	Israel