RU2779739C2 - Unilateral three-way indexable cutting plate for milling, having large ratio of void volume to material volume, and milling cutter containing plate for it - Google Patents

Abstract

FIELD: material processing.

SUBSTANCE: group of inventions relates to material processing by cutting; it can be used in milling operations with high supply. A unilateral three-way indexable cutting plate contains the main form with a positive front angle, a front surface, a peripheral surface containing side stop surfaces, the main bearing surface, and a hole for a screw connecting front and main bearing surfaces. The plate has a cutting edge containing three main sub-edges and three additional sub-edges. Material volume VF of the cutting plate and void volume VS of the plate satisfy the condition VS/VF ≥ 0.30, and a circumscribed diameter of the edge DE satisfies the condition DE < 6 mm.

EFFECT: structural strength of a milling tool of a small diameter is provided.

22 cl, 9 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to milling cutters containing inserts and one-sided three-way indexable cutting inserts for milling (hereinafter also referred to as insert(s)) therefor. In particular, the invention relates to relatively small such inserts and tool holders capable of performing high feed milling operations.

BACKGROUND OF THE INVENTION

For the purposes of the present invention, end mills can theoretically be divided into two general groups, namely insert cutters and solid end mills.

Insert-containing milling cutters are milling tools that include tool holders with pockets and indexable inserts, usually indexable, adapted to fit into these pockets. The advantage of milling cutters containing inserts is that the inserts, which are made of a relatively expensive and harder material, constitute a relatively small part of this milling tool. Tool holders contain a shank that is held firmly by a collet or chuck during milling.

Unlike insert cutters, which require small inserts to be replaced regularly and also require tool holder replacement less regularly, solid end mills contain integral teeth, whereby the entire solid end mill is replaced after wear. Solid end mills also include a one-piece shank that is held firmly by a collet or chuck during milling. Accordingly, solid end mills use a comparatively much more expensive material than cutters containing inserts. Despite the comparatively higher cost, one of the advantages of solid end mills over insert-containing cutters is that the single integral body of the solid end mill can be made in a relatively smaller diameter (typically less than 20 mm, with smaller diameters being more popular, such as a diameter of about 12 mm or less) allowing milling at relatively smaller locations than is possible, or practiced with cutters containing an insert.

Accordingly, the present invention relates to inserts and insert-containing cutters that have a number of design features that make them functionally and economically competitive with solid endmills at tool cutting diameters (also referred to as cutting diameter(s)) of 20 mm or less, in in particular, in the range from 9 to 16 mm. In particular, in the range from 9 to 12 mm.

Publication EP 3050655 of interest discloses one-sided, two-way indexable inserts for small diameter tool holders. An object of the present invention is to provide an improved three-way indexable cutting insert for milling and an insert-containing milling cutter therefor.

DISCLOSURE OF THE INVENTION

The present invention provides a single-sided, three-way indexable insert for high feed milling operations and for small diameter tool holders. Three index positions are generally preferred over the two index positions disclosed in EP 3050655, and the design chosen in EP 3050655 was deliberately chosen to have only two index positions, presumably because it was the optimal design for small tool holders. diameter represented by these inventors.

Notably, three-pass indexable inserts are in many ways disadvantageous compared to two-pass indexable inserts. Firstly, due to the fact that manufacturing errors have a greater effect on eccentricity (due to the sharp angle formed by the stop surfaces of the tool), which leads to greater instability during machining. Secondly, due to the fact that the large size of the insert creates a greater moment when applying cutting forces to the cutting edge, which also leads to greater instability during machining. Thirdly, and perhaps most significantly, since three-way indexable inserts are wider, they are more problematic to design for small diameter tools, as will be further explained below.

However, the present invention proposes that even for very small diameter cutters containing inserts (i.e., having a diameter of 9 to 12 mm, or in particular about 10 mm), a three-way indexable insert, for example, with a generally triangular shape (at least least in relation to the main cutting edges) may provide an overall advantage over the prior art.

As mentioned above, three-way indexing inserts for high feed milling operations are comparatively wider than, for example, two-way indexing inserts of the type shown in EP 3050655 (also US 2018015554 A1). In other words, they have a relatively large radial dimension (ie dimension in a direction perpendicular to the axis of rotation when mounted in a tool holder), limiting them to conventional use with relatively large diameter tools. The reason for this is that in order to provide a main cutting edge of sufficient size (the main cutting edge for an insert containing high feed milling cutter is the edge that enables this operation) and three-sided symmetry, the radial size of the insert depends on the length of this cutting edge. This is not the case for the side bearing surface of an elongated insert of the type shown in EP 3050655, which has a radial dimension independent of the length of the main cutting edge and can be minimally reduced to match the minimum wall strength required near its screw hole. Because a three-way indexable insert cannot have a radial size reduced to a minimum in this way, a tool capable of holding such inserts has a reduced amount of material in its core. This reduction is less significant for drills that have mainly axial forces or larger diameters that still have significant core dimensions, but is very important for the present invention relating to small diameter milling tools with significant radial cutting forces. Let's pay attention to Fig. 13 in EP 3050655 where it can be seen that the core diameter approximates the width of each of the inserts shown. It should be understood that there is a problem in that a reduction in core diameter can lead to unacceptable bending of the tool holder. While relatively small diameter drills are known, it should be understood that insert-containing cutters are subject to greater radial forces than drills due to the nature of the milling operation involving off-axis movement of the tool holder.

Therefore, the present invention provides an insert-containing cutter for cutting tool diameters ranging from 9 mm to 12 mm, and in particular, a cutting tool diameter of approximately 10 mm, which is significantly more difficult to design than insert-containing cutters with larger cutting tool diameters, especially when providing three-way indexable inserts.

Therefore, a number of advantageous features have been combined, each of which has been designed to be economically manufactured in order to make the insert-containing small diameter cutter competitive with solid endmills, which will be discussed below.

According to a first aspect of the present invention, there is provided a one-sided three-way indexable insert having a positive rake base shape and a volume ratio VS/VF of void volume VS and material volume VF given by the amount of insert material, satisfying the following condition: VS/VF ≥ 0 ,thirty.

According to a second aspect of the present invention, there is provided a one-sided three-way indexable insert having a positive rake base shape and comprising: a volume (VF) of material given by an amount of insert material, a rake face; a main bearing surface opposite the front surface; an axis (AI) of the plate passing perpendicular to the main bearing surface and through the center of said plate, wherein the plate axis defines: an upward direction extending from the main bearing surface to the front surface, a downward direction opposite to the upward direction, and an outward direction perpendicular to the upward and down and passing from the axis of the plate; insert height (HI) measured parallel to the insert axis and extending from the main bearing surface to the highest point of the rake surface; a peripheral surface connecting the front surface and the main bearing surface; a cutting edge formed at the intersection of the peripheral surface and the rake surface, wherein in a view parallel to the axis (AI) of the insert, the cutting edge defines an imaginary circumscribed circle (CE) of the edge having a circumscribed diameter (DE) of the edge; and a screw hole opening toward the front and main bearing surfaces, wherein the screw hole comprises: a lower part of the screw hole located at an intersection with the main bearing surface; the top of the screw hole located at the intersection with the front surface; void volume (VS) calculated as the void volume extending from the bottom of the screw hole to the top of the screw hole, and the circumference (CS) of the hole, in a view parallel to the axis (AI) of the plate, given at the intersection of the rake face and the hole for a screw, wherein the circumference (CS) of the hole has a diameter (DS) of the hole; in a bottom view parallel to the axis (AI) of the plate, the main bearing surface defines an imaginary main circumscribed circle (CB) having a main diameter (DB); peripheral surface contains: first, second, third, fourth, fifth and sixth side thrust surfaces; in a plan view parallel to the axis (AI) of the insert, the cutting edge defines an inscribed circle (CM) of the edge having an inscribed diameter (DM) of the edge, while the cutting edge contains: exactly three main sub-edges and exactly three additional sub-edges, while the main sub-edges alternate with additional hemlines, and at each intersection between the main and additional hemlines there is a corner hemline; moreover: the main circumscribed diameter (DB) is less than the circumscribed diameter (DE) of the edge; and the volume ratio of the volume (VS) of voids to the volume (VF) of the material satisfies the following condition: VS/VF≥0.30.

Having a main shape with a positive rake angle allows the main bearing surface of the insert to be released (i.e., spaced away from the cutting tool diameter as shown in FIG. 9A), which is important to the present invention relating to insert-containing ultra-small diameter cutters.

In addition, allowing the compaction process to be carried out with the least possible machining, as disclosed in EP 3050655 B1 (paragraph [0034]), also contributes to the economic advantage of the present design. It should be noted that the term "basic shape with a positive rake angle" specifically means that the cross-sectional areas near the main bearing surface of the plate are smaller than the cross-sectional areas away from it, but does not require all peripheral surfaces to be continuously inclined. For example, some portions of these plate surfaces may extend parallel to the axis of the plate. One way to determine the main shape with a positive rake angle is that the main circumscribed diameter DB is smaller than the circumscribed edge diameter DE.

The amount of material of the plate itself can be reduced to a minimum. It was found that the above volume ratio VS/VF was successfully achieved. It should be understood that the size of the plate must be minimized, while a minimum amount of material is needed for structural strength. In addition, minimizing the amount of material and providing three indexable positions can provide an economic advantage.

According to a third aspect of the present invention, there is provided a single-sided three-pass indexable insert, wherein the ratio DS/DM of insert thickness diameters for hole diameter DS and inscribed edge diameter DM satisfies the following condition: DS/DM>0.60.

This aspect is similar to the above aspects in that it specifies the minimum amount of material required for structural strength, albeit in a different way. Based on the drawings, it should be noted that the weakest structural part of the plate is the material located approximately between the hole diameter DS and the inscribed edge diameter DM. Accordingly, the ratio DS/DM of the plate thickness diameters according to the above value is successfully performed.

According to a fourth aspect of the present invention, there is provided a single-sided three-way indexable cutting insert with major undercuts; in which the ratio LM/LS of the edge lengths for the main edge length LM and the additional edge length LS, each containing half of the adjacent corner sub-edges, satisfies the following condition: LM/LS>0.80.

Typically, high feed rate inserts have a significantly larger edge length ratio LM/LS than specified above. The reason for this is that most high-feed operations are performed with the main undercut, and thus need to be longer and reduce machining time. In one non-limiting but preferred embodiment, the length of the major edge is reduced to provide a faster feed rate.

According to a fifth aspect of the present invention, there is provided a single-sided three-way indexable cutting insert with major under-edges, wherein the described edge diameter DE satisfies the following condition: DE<6 mm.

It should be understood that reducing the size of the insert also reduces the size of chips that such an insert can remove, making it less efficient. However, to accommodate two inserts in a small cutting diameter tool holder, a particularly small insert is required. This is despite the fact that a similarly sized two-way indexable insert would be much easier to place.

Because the cutting insert according to the present invention is small, it has been found that the deformation caused by the sintering process is within acceptable tolerances, and circumferential grinding of the insert can be dispensed with. Thus, the plate can be provided with an unpolished lower subsurface. As is known in the art, sanded surfaces can be identified by sanding strokes and break lines where the flat sanded surface ends and the rough surface begins.

Although each of the main design features mentioned above (namely volume ratio, plate thickness diameter ratio, edge length ratio and small circumscribed edge diameter DE) is contemplated individually to be advantageous, it is to be understood that the present invention contemplates that any combination of any such features on a basic shape with a positive rake angle will make a single-sided, three-way indexable insert even more advantageous.

Likewise, any of the optional features below can be applied to each aspect above.

It should be understood that a larger VS/VF volume ratio uses less material. Therefore, it is preferable that the volume ratio satisfies the following condition: VS/VF>0.35, or even VS/VF>0.40. Theoretically, it is assumed that the approximated maximum volumetric ratio for acceptable modern cutting conditions satisfies the following condition: VS/VF<0.50. In this case, the largest ratio having an acceptable margin of safety will be VS/VF<0.45.

Likewise, a larger ratio DS/DM of plate thickness diameters uses less material. Therefore, it is preferable that the volume ratio satisfies the following condition: DS/DM>0.65. Theoretically, it is assumed that the approximate maximum ratio of plate thickness diameters for acceptable modern cutting conditions satisfies the following condition: DS/DM<0.80. In this case, the largest ratio having an acceptable margin of safety will be DS/DM<0.75.

The larger LM/LS lip length ratio provides acceptable cutting width while reducing the base lip length for high feed. Therefore, in some embodiments, the edge length ratio LM/LS satisfies the following condition: LM/LS>0.80, more preferably LM/LS>1.0. Theoretically, it is assumed that the approximated maximum ratio of plate thickness diameters for economical machining satisfies the following condition: LM/LS<1.2.

The additional edge length LS is the length of the additional edge containing half of the corner sub-edges adjacent to it, and the effective beveled edge length LR is the length of the additional edge measured in the vicinity of the released portion of the peripheral surface. In accordance with some embodiments, the effective beveled edge length LR satisfies the following condition: 0.4LS>LR>0.8LS.

It should be understood that although the given edge diameter DE described above allows for an unground lower subsurface, even smaller dimensions will more easily fit into the tool holder. Therefore, it is preferable that the described edge diameter DE satisfies the following condition: DE<5.5 mm.

Theoretically, it is assumed that the approximate maximum feasible size for such a three-way indexing insert, designed to provide acceptable modern cutting conditions, satisfies the following condition: DE>4 mm. In this case, the largest circumscribed edge diameter DE, which has an acceptable margin of safety, will be DE>4.5 mm.

Preferably, a positive rake angle is formed over the entire cutting edge.

Preferably, in a plan view parallel to the plate axis AI, all internal angles λ formed between the main and additional under-edges are obtuse. However, it should be understood that only alternating interior angles can have identical values.

The peripheral surface of the plate may include a lower subsurface and an upper subsurface; wherein the lower subsurface extends upward or upward and outward from the main bearing surface and comprises first, second, third, fourth, fifth and sixth side abutment surfaces; the upper subsurface connects the lower subsurface and the front surface, with the upper subsurface beginning in an upward direction at a minimum height HU of the upper surface above the main bearing surface.

Preferably, the lower subsurface only extends upwards (ie, perpendicular to the main bearing surface). This is expected to provide a stable mounting position as well as simplify milling of the tool holder seat (allowing for simple orthogonal milling).

Preferably, the upper subsurface extends more outward than the lower subsurface.

It should be understood that a larger minimum upper subsurface height HU provides for a larger lower subsurface height. The lower subsurface provides a load-bearing function and therefore maximizing its height provides more stability to the plate when installed in the socket. On the contrary, a sufficient size of the upper subsurface is necessary for the cutting function. Therefore, it is preferable that the minimum height HU of the upper subsurface satisfies the following condition: 0.35HI ≤ HU ≤ 0.85HI, and more preferably 0.40HI ≤HU ≤ 0.60HI.

The upper subsurface may comprise at least one overhang, preferably extending around the entire periphery of the plate.

Preferably, with the exception of a portion of the peripheral surface near each additional edge, the remainder of the peripheral surface near the cutting edge is parallel to the insert axis.

Preferably, under a portion of each additional sub-edge, a recess is formed.

In the bottom view, parallel to the AI axis, the first, second, third, fourth, fifth and sixth side thrust surfaces of the inserts are located at an unequal distance from adjacent parts of the cutting edge. The greatest distance of the thrust surface from the adjacent part of the cutting edge can be located near the main sub-edge. The smallest distance of the thrust surface from the adjacent part of the cutting edge can be located near the additional under-edge.

Preferably, the cutting insert may have 120° rotational symmetry around the insert axis. In other words, the cutting insert can have three identical sides.

The cutting insert may comprise three main undercuts of the same size and three additional undercuts of the same size.

According to one preferred example, each base hem has an edge length LM that satisfies the following condition: 1.8 mm<LM<2.8 mm.

Most preferably, the main bearing surface is sanded. In an embodiment of the invention, only the main bearing surface of the cutting insert is ground. This is the most economical plate production. It should be understood that in all cases it is advantageous when the lower subsurface is rough.

In that embodiment of the invention, in which it is necessary to carry out an additional grinding operation of the front surface, the main bearing surface and the entire cutting edge are ground. In other words, the grinding operation is not carried out on the entire peripheral surface, but only along the top of the plate, and therefore the entire edge is contained within the plane (that is, lies on it). It should be understood that such top grinding of the insert allows a plurality of inserts to be ground in a single pass.

It is also possible to produce a cutting edge that lies on a plane parallel to the main bearing surface, i.e. it is flat in the side view of the insert. As will be known to those skilled in the art, it is more economical to grind a flat cutting edge than one that is three-dimensional and non-flat.

To ensure proper performance, the width WL of the contact area of the cutting edge, measured perpendicular to the axis of the insert and taken at any position along the cutting edge, satisfies the following condition: WL≤0.14mm. Preferably, the contact area width WL satisfies the following condition: 0.02mm≤WL≤0.14mm, or even more preferably 0.03mm≤WL≤0.11mm, and most preferably 0.04mm≤WL≤0.08mm.

According to a sixth aspect of the present invention, there is provided a one-sided three-way indexable insert having a positive rake base shape and comprising: a front surface; a main bearing surface opposite the front surface; a screw hole opening to the front and main bearing surfaces, with the screw hole extending along the axis (AI) of the plate, which runs perpendicular to the main bearing surface and through the center of the plate, with the axis of the plate giving an upward direction passing from the main bearing surface to a front surface, a downward direction opposite to the upward direction, and an outward direction perpendicular to the up and down directions and extending from the axis of the plate; a peripheral surface connecting the front surface and the main bearing surface, while the peripheral surface includes: an upper subsurface located near the front surface and containing an overhanging part; and a lower subsurface located between the upper subsurface and the main bearing surface, the lower subsurface having six side abutment surfaces; and a cutting edge formed at the intersection of the peripheral surface and the rake surface, wherein the cutting edge comprises three main sub-edges alternating with three additional sub-edges, and a corner sub-edge located at each main and additional sub-edges and forming an obtuse internal corner; wherein: each additional hem includes a first edge portion adjacent to one corner hem and a second edge portion extending from the first edge portion in the direction of the adjacent corner hem; the overhanging part of the upper subsurface contains an unreleased surface located below the first edge part, and a drain recess located below the second edge part; and the withdrawal recess has a stepped shape in the direction along said each additional hem.

The cutting insert may contain six identical side thrust surfaces.

The main load-bearing surface may form an internal right angle (β1) with each of the six side abutment surfaces forming the lower subsurface.

The entire upper cutting edge may lie flat.

The cutting insert may further be defined as follows: a material volume (VF) given by the amount of material of the cutting insert; insert height (HI), measured parallel to the insert axis and extending from the base bearing surface to the highest point of the rake face; the cutting edge in a plan view parallel to the axis (AI) of the insert defines an inscribed circle (CM) of the edge having an inscribed diameter (DM) of the edge and an imaginary circumscribed circle (CE) of the edge having an inscribed diameter (DE) of the edge; and each base hem has a base hem length (LM) that contains half the lengths of the corner edges adjacent thereto; each additional hem has a length (LS) of the additional hem, which contains half the lengths of the corner edges adjacent to it; the main bearing surface in the bottom view, parallel to the axis (AI) of the plate, defines an imaginary main circumscribed circle (CB) having a main diameter (DB); the screw hole contains: the bottom part of the screw hole, located at the intersection with the main bearing surface; the top of the screw hole located at the intersection with the front surface; void volume (VS) calculated as the void volume extending from the bottom of the screw hole to the top of the screw hole; and a hole circle (CS), in a view parallel to the plate axis (AI), defined at the intersection of the rake face and the screw hole, the hole circle (CS) having a hole diameter (DS); the main circumscribed diameter (DB) is less than the circumscribed diameter (DE) of the edge; and the volume ratio of the volume (VS) of voids to the volume (VF) of the material satisfies the following condition: VS/VF≥0.30.

According to a seventh aspect of the present invention, there is provided a tool holder comprising two pockets comprising a seating abutment surface, a threaded hole of the seat opening towards the seating abutment surface; first, second and third transverse abutments that are straight and oriented perpendicular to the seat abutment; each first transverse stop surface is located near the periphery of the tool and extends outward and forward; each second transverse abutment surface is closer to the axis of rotation than the first transverse abutment surface, and is separated from the first transverse abutment surface by the first outlet recess, while the second transverse abutment surface extends inward and forward; each third transverse abutment surface is closer to the axis of rotation, and also located more forward than the second transverse abutment surface, and is separated from the second transverse abutment surface by a second outlet recess, while the third transverse abutment surface extends inward and forward; and the tool diameter DT satisfies the following condition: DT<11 mm.

The cutting insert may further be defined as follows: a material volume (VF) given by the amount of material of the cutting insert; insert height (HI), measured parallel to the insert axis and extending from the base bearing surface to the highest point of the rake face; the cutting edge in a plan view parallel to the axis (AI) of the insert defines an inscribed circle (CM) of the edge having an inscribed diameter (DM) of the edge and an imaginary circumscribed circle (CE) of the edge having an inscribed diameter (DE) of the edge; and each base hem has a base hem length (LM) that contains half the lengths of the corner edges adjacent thereto; each additional hem has a length (LS) of the additional hem, which contains half the lengths of the corner edges adjacent to it; the main bearing surface in the bottom view, parallel to the axis (AI) of the plate, defines an imaginary main circumscribed circle (CB) having a main diameter (DB); the screw hole contains: the bottom part of the screw hole, located at the intersection with the main bearing surface; the top of the screw hole located at the intersection with the front surface; void volume (VS) calculated as the void volume extending from the bottom of the screw hole to the top of the screw hole; and a hole circle (CS), in a view parallel to the plate axis (AI), defined at the intersection of the rake face and the screw hole, the hole circle (CS) having a hole diameter (DS); the main circumscribed diameter (DB) is less than the circumscribed diameter (DE) of the edge; and the volume ratio of the volume (VS) of voids to the volume (VF) of the material satisfies the following condition: VS/VF≥0.30.

According to a seventh aspect of the present invention, there is provided a tool holder comprising two pockets comprising a seating abutment surface, a threaded hole of the seat opening towards the seating abutment surface; first, second and third transverse abutments that are straight and oriented perpendicular to the seat abutment; each first transverse stop surface is located near the periphery of the tool and extends outward and forward; each second transverse abutment surface is closer to the axis of rotation than the first transverse abutment surface, and is separated from the first transverse abutment surface by the first outlet recess, while the second transverse abutment surface extends inward and forward; each third transverse abutment surface is closer to the axis of rotation, and also located more forward than the second transverse abutment surface, and is separated from the second transverse abutment surface by a second outlet recess, while the third transverse abutment surface extends inward and forward; and the tool diameter DT satisfies the following condition: DT<11 mm.

According to an eighth aspect of the present invention, there is provided a tool holder, comprising: a rear end, a front end, a tool periphery extending from a rear end to a front end; an axis of rotation passing through the center of the tool holder, wherein the axis of rotation defines a forward direction extending from the rear end to the front end, a backward direction opposite to the forward direction, an outward direction perpendicular to the rotation axis and directed from the rotation axis to the periphery of the tool, an inward direction, opposite to the outward direction; part of the shank extending forward from the rear end; and a cutting portion extending forward from the shank portion to the front end, wherein the cutting portion has a tool diameter (DT) at the front end and exactly two circumferentially spaced recesses extending rearward from the intersection of the front end and the periphery of the tool; wherein each of these recesses contains a socket formed at the intersection of the front end and the periphery of the tool; each of the two sockets contains: a landing thrust surface, a threaded hole of the socket opening to the landing thrust surface; and first, second, and third transverse abutments that are transverse to the seat abutment; each first transverse stop surface is located near the periphery of the tool and extends in outward and forward directions; each second transverse abutment surface is closer to the axis of rotation than the first transverse abutment surface and is separated from the first transverse abutment surface by a first retractable recess, with each second transverse abutment surface extending inward and forward directions; each third transverse abutment surface is closer to the axis of rotation, and also located more forward than the second transverse abutment surface, and is separated from the second transverse abutment surface by a second outlet recess, with each third transverse abutment surface extending inward and forward directions; and the diameter (DT) of the tool satisfies the following condition: DT<11 mm.

It is not believed that tool holders of such small diameters (with two pockets opening partially in the radial direction, increasing the instability of the front end of this tool holder during milling operation and made to accommodate a relatively wide three-way indexing insert) are not expected to be made.

Furthermore, it should be understood that the tool holders of the present invention refer only to the sockets at the front end of the tool holder.

Preferably, in a plan view of the seating abutment surface, the second and third transverse abutment surfaces are not parallel to each other.

Preferably, each recess contains only one socket.

Preferably, the tool holder includes a support bridge extending between the two sockets to a forwardmost point that is recessed from the front end of the tool holder.

It should be understood that for such small diameter tool holders, each element that adds structural strength is significant. Given the close spacing of the plates, a support bridge cannot be added between them without risk of damage. A compromise was reached in the form of a limited size support web that does not extend all the way to the front end of the tool.

Preferably, the support bridge has a thin, elongated shape.

Preferably, the central portion of the frontmost surface of the support web is flat.

Preferably, in a side view of the tool holder, the frontmost surface of the support web has a concave shape.

Preferably, the third transverse abutment surface is at least partially formed on the support web.

Preferably, the DT tool diameter is as small as possible in order to compete with solid end mills. With the features described above, a tool diameter DT satisfying the condition DT<10 mm was successfully tested. It should be understood that the diameter of the tool, which is measured at the front end of the tool holder, is slightly smaller than the diameter DC of the cutting tool. Theoretically, it is assumed that the approximate minimum tool diameter satisfies the condition DT> 9 mm.

Another measure taken to accommodate two plates in such a small diameter is to adjust their position relative to each other.

While it is generally preferred for both inserts that their rake surfaces be generally aligned, this is not possible with a small diameter tool holder (eg because the inserts will touch). The preferred solution according to the present invention is to align the plates such that a portion of the peripheral surface of each plate is adjacent to the other plate. With regard to this feature, it can also be described, for example, in relation to the sockets of the tool holder as follows.

In a front end view that is parallel to the axis of rotation AR: a first imaginary extension line extending from the front edge of one of the seating abutments may be parallel to a second imaginary extension line extending from the leading edge of the other seating abutment surface; the center plane PC of the tool is set parallel to the axis of rotation AR and is located between the first and second extension lines so that each landing abutment surface faces the center plane PC of the tool; the first seating distance DS1 is defined from the first extension line to the tool center plane PC; the second seating distance DS2 is set from the second extension line to the center plane PC of the tool; wherein the total distance DS3, which is the sum of the first landing distance DS1 and the second landing distance DS2, satisfies the following condition: DS3<0.35DT. Preferably, the total distance DS3 satisfies the following condition: DS3<0.30DT. Preferably, the minimum dimension is DS3>0.20DT.

Preferably, each socket is formed and oriented identically in the tool holder.

Preferably, the socket opening can likewise be comparatively larger in cross section compared to the distance to the transverse abutment surfaces. This can be seen from the diameter of the socket opening and the distances to the transverse surfaces and can be understood in terms of dimensions in accordance with the present invention.

Preferably, the axis of the screw may be offset from the center of the seating surface, i.e., may be slightly closer to where the first and second transverse abutments are closest to each other, such that the screw holding the insert in the seat will move this cutting insert towards the first and second transverse thrust surfaces.

According to a ninth aspect of the present invention, there is provided a tool holder, comprising: a rear end, a front end, a tool periphery extending from a rear end to a front end; an axis of rotation passing through the center of the tool holder and specifying a forward direction extending from the rear end to the front end, a backward direction opposite to the forward direction, and an outward direction perpendicular to the axis of rotation and directed from the axis of rotation to the periphery of the tool, a portion of the shank extending forward from the rear end; and a cutting portion extending forward from the shank portion to the front end, the cutting portion having a tool diameter DT at the front end and exactly two circumferentially spaced recesses extending rearward from the intersection of the front end and the periphery of the tool; wherein each of these recesses contains one socket formed at the intersection of the front end and the periphery of the tool; moreover, the support bridge extends between said sockets to the most forward point, which is recessed from the front end of the tool holder.

According to a tenth aspect of the present invention, there is provided an insert cutter comprising a tool holder according to one of the seventh to ninth aspects and at least one insert according to any one of the first to sixth aspects mounted thereon.

According to an eleventh aspect of the present invention, there is provided an insert-bearing cutter comprising: a tool holder according to any of the above aspects; and a cutting insert according to any of the above aspects, in which the cutting insert is installed in one of the pockets of the tool holder; exactly one of the insert's main under-edges extends forward from the tool holder; exactly one of the insert's additional hems extends forward from the tool holder; and exactly one of the additional insert edges extends outward from the tool periphery.

According to a twelfth aspect of the present invention, there is provided an insert cutter comprising: two cutting inserts and a tool holder, the tool holder comprising: a rear end, a front end, a tool periphery extending from a rear end to a front end; a rotation axis passing through the center of the tool holder and defining a forward direction extending from the rear end to the front end, a backward direction opposite to the forward direction, and an outward direction perpendicular to the rotation axis and directed from the rotation axis to the tool periphery; part of the shank extending forward from the rear end; and a cutting portion extending forward from the shank portion to the front end, the cutting portion having a tool diameter DT at the front end and exactly two circumferentially spaced recesses extending rearward from the intersection of the front end and the periphery of the tool; wherein each of these recesses contains one socket formed at the intersection of the front end and the periphery of the tool; each seat has a cutting insert installed therein, each seat opens in an outward direction so that the main under-edge of each cutting insert extends in a forward direction beyond the front end of the tool holder, the extension of the cutting insert in the outward direction further defines the diameter DC of the cutting tool; wherein each of the cutting inserts contains an identical cutting edge formed along the intersection of the peripheral surface with its front surface; each cutting edge in a view parallel to the insert axis AI defines an imaginary circumscribed circle CE of the edge having a circumscribed circle diameter DE of the edge; wherein the RIM ratio of the insert-containing cutter, defined as (DE+DE)/DC, satisfies the following condition: RIM>0.9.

Preferably, the RIM ratio of the insert-containing cutter satisfies the following condition: RIM>1.0. Preferably, the maximum size is DS3<1.4, preferably DS3<1.2.

Preferably, in a front end view that is parallel to the axis of rotation AR, the peripheral surface of each plate is adjacent to a part of the peripheral part of the other plate.

Preferably, the total distance DS3 is greater than the insert height HI.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present application, and also in order to show how the subject matter may be carried out in practice, reference will now be made to the accompanying drawings obtained from the scale model, in which:

in fig. 1A is a side view of an insert-containing cutter containing a tool holder and inserts in accordance with the present invention, rotated to show a side view of one of said inserts;

in fig. 1B is a side view of the insert containing cutter of FIG. 1A rotated to show a front view of one of said plates;

in fig. 1C is a front end view of the insert containing cutter of FIG. 1B;

in fig. 2 is a perspective view of one of the plates of FIG. 1A;

In FIG. 3 is a plan view of the plate of FIG. 2;

in fig. 4A is a sectional view taken along line IVA shown in FIG. 3;

in fig. 4B is a sectional view taken along the line IVB shown in FIG. 3;

in fig. 4C is a sectional view taken along the IVC line shown in FIG. 3;

in fig. 5A is a side view of the plate of FIG. 2;

in fig. 5B is a plan view of the plate of FIG. 5A;

in fig. 5C is a bottom view of the plate of FIG. 5A;

in fig. 6 is a sectional view taken along line VI-VI of FIG. 5B;

in fig. 7A is a side view of the tool holder containing the cutter insert of FIG. 1A rotated to show a side view of one of the sockets;

in fig. 7B is a side view of the tool holder of FIG. 7A rotated to show a front side view of one of the sockets;

in fig. 7C is a front end view of the tool holder of FIG. 7A;

in fig. 7D is a perspective view of a portion of the tool holder of FIG. 7A;

in fig. 8A is a perspective view of the tool holder seat of FIG. 7A;

in fig. 8B is a side view of the socket of FIG. 8A;

in fig. 8C is a plan view (ie, axial view) of the socket of FIG. 8A, which is also a plan view of the landing abutment of said socket;

in fig. 9A is a view of the plates shown in FIG. 1C, without tool holder and screws, schematically depicting a tool describing a cutting diameter circle;

in fig. 9B is a side view of the plates shown in FIG. 9A, also corresponding to the orientation of the plates as shown in FIG. 1B; and

in fig. 9C is a side view of the plates shown in FIG. 9B and screws for mounting them in a tool holder rotated to match the orientation of the inserts as shown in FIG. 1A.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1A-1C illustrate an insert-containing cutter 10 configured to perform high feed milling operations.

The insert-containing cutter 10 includes a tool holder 12, cutting inserts 14, and screws 16 for fixing the cutting inserts 14 in the tool holder 12.

The insert-containing cutter 10 is rotatable about a rotation axis AR that extends longitudinally through its center.

The axis of rotation AR defines the axially opposite forward direction DF and the backward direction DR, as well as the opposite cutting and non-cutting directions DK, DN.

The tool holder 12 includes a rear end 13A, a front end 13B, and a tool periphery 13C extending therebetween.

The tool holder 12 further comprises a shank portion 18 and a cutting portion 20 extending in front of it.

The cutting portion 20 includes exactly two recesses 21. Each recess 21 contains a socket 22 (see FIG. 8A) formed at the intersection of the front end 13B and the periphery 13C of the tool.

In these examples, the inserts 14, screws 16 and sockets 22 are identical, hence the features described in relation to one are considered to apply to all.

The cutting insert 14 will now be described with reference to FIG. 2-6.

The insert 14 is a single-sided, three-way indexable insert having a positive rake basic shape. It comprises a front surface 24, a main bearing surface 26, a peripheral surface 28, a screw hole 30, and a cutting edge 32.

The insert axis AI (FIG. 6) extends perpendicular to the main bearing surface 26 and through the center of the insert 14. The insert axis AI is provided to help define the directions and features of the cutting insert 14. In general, although it is most preferred that the screw hole in according to the present invention was located in the center of the plate and perpendicular to the main bearing surface, which causes the axis of the plate to also pass through the center of the screw hole, it should be understood that it is possible that the screw hole may be inclined or not perfectly centered relative to the cutting of the plate, resulting in the axis of the screw hole (not shown) being not coaxial with the axis AI of the plate (even though they are coaxial in the present preferred example). However, given that the present invention seeks to minimize the use of material, the perpendicular and centered screw hole shown in the example is clearly preferred for structural strength purposes. Therefore, in this example, the plate axis AI also passes through the center of the screw hole 30 .

With reference to FIG. 6, the screw hole 30 may include a bottom screw hole part 31 and an upper screw hole part 33.

In FIG. 5B shows the hole circle CS defining the hole diameter DS.

The plate axis AI defines opposite directions DU, DD up and down, and as shown in the example of FIG. 5C, opposite directions DI, DO in and out. The outward direction DO is not meant to define one particular direction, but it defines all possible outward directions 360° from the plate axis AI, four such directions are shown in the example. This is also true in the opposite direction, with respect to the inward direction of the DI, although only one such example is shown. This is also true for the inward and outward directions DI, DO shown with respect to the insert containing cutter 10 shown in FIG. 1C.

As shown, for example, in FIG. 4A-4C and 6, preferably, the rake face 24 may slope inward and downward from the cutting edge 32 to form a sharp internal angle α for the purposes of chip formation. The acute internal angle α formed between the front surface 24 and the peripheral surface 28 is also referred to as a positive rake angle. Such a positive angle compensates for the orientation of the seating surfaces, which in this non-limiting but preferred example run obliquely to the axis of rotation AR and do not by themselves provide a positive cutting angle.

As shown, main bearing surface 26 is generally flat, but it should be understood that this definition does not exclude the possibility of including small, rounded transitional edges between peripheral surface 28 and main bearing surface 26, as shown, for example, in FIG. 7 in EP 3050655. In the embodiment shown, a chamfer 27 is provided (FIGS. 5A and 5C). For the purposes of this specification and claims, main bearing surface 26 is considered to be the lowest surface, ie not containing any beveled or rounded areas. Thus, in FIG. 5C, the main bearing surface 26, in a view parallel to the plate axis AI, defines an imaginary main circumscribed circle CB having a main diameter DB.

With reference to FIG. 5C, the positive rake base shape of the insert 14 means that the base bearing surface 26 has a smaller base diameter DB than the described diameter DE of the cutting edges 32 (FIG. 5B).

With reference to FIG. 2, 5C and 6, the peripheral surface 28 includes a bottom subsurface 34 and an upper subsurface 36. The bottom subsurface 34 is rough and extends upward from the main bearing surface 26 and also includes first, second, third, fourth, fifth, and sixth side abutment surfaces 38A. , 38B, 38C, 38D, 38E, 38F (hereinafter, these identical side abutments will be identified generically as "side abutment(s) 38"). Radially rounded portions 39 (FIG. 2) extend between the side stop surfaces 38, but in the example shown they have no stop function.

It should be noted that the abutment surfaces 38 of the plate serve as bearing surfaces which form an internal right angle β1 with the main bearing surface 26, as best seen in FIG. 6.

Each of the side abutments 38 is generally flat. To be specific, in Fig. 3 shows an exaggerated schematic bulge 40. The bulge 40 typically results from the sintering process. Because the plates of the present invention are small, the deformation resulting in such a bulge 40 is tolerably small so that they do not require grinding. In general, such bulges and concavities (not shown, which for the purposes of this specification may be considered inward "bulges") are measured as the maximum distance from the plane connecting adjacent corners of the plate to such a bulge.

Thus, the plate is said to have an unpolished lower subsurface. Although, for example, in FIG. 2, for example, a fracture line 42 is shown on the unpolished lower subsurface, this is only a consequence of this particular drawing showing a line of curvature. The actual product, which has not been sanded, has no discernible line and smoothly transitions from the generally flat part to the radiused part 39.

Upper subsurface 36 comprises an overhang 44, in this example extending around the entire plate 14 (examples are shown in FIGS. 4A-4C).

With reference to FIG. 2, the insert 14 may include six corner edges 46A, 46B, 46C, 46D, 46E, 46F (hereinafter collectively referred to as "corner edge(s) 46"), three identical main under edges 48A, 48B, 48C (hereinafter herein collectively referred to as “main hem(s) 48”) and three identical additional hem(s) 47A, 47B, 47C (hereinafter collectively referred to as “additional hem(s) 47”).

With reference to FIG. 5B, in connection with the cutting edge 32, an imaginary circumscribed edge CE having an inscribed edge diameter DE and an imaginary inscribed circle CM having an inscribed edge diameter DM are shown. The circumscribed circle CE of the edge is the smallest diameter circle that surrounds all parts of the circumferential cutting edge 32, while the inscribed circle CM of the edge is the largest diameter that fits entirely within the circumferential cutting edge 32.

The dimensions of the various features are shown as follows: each corner hem 46 may have a radius R (FIG. 5C); and each base hem 48 may have a base hem length LM measured from the center of the adjacent corner hem 46, with the base hem length LM being the actual size applicable during high feed operations. In addition, each additional hem 47 (measured from the center of the adjacent corner hem 46) may have an additional edge length LS; each chamfered portion 43 of the additional under-edge 47, that is to say, that portion of it which has under it the released portion of the peripheral surface, that is, the withdrawal recess 53, may have an effective beveled edge length LR; and the width WL of the contact portion of the cutting edge is shown in FIG. 4b.

With reference to FIG. 6, the void volume VS of the cutting insert 14 is defined by the boundaries of the screw hole 30. In particular, the height HS of the screw hole is given from the main bearing surface 26 to the upper edge 49 of the screw hole 30 (also indicated in FIG. 4). In other words, the void volume VS is calculated as the void volume extending from the bottom of the screw hole 30 defined on the bottom plane PL perpendicular to the plate axis AI to the top of the screw hole 30 defined on the top plane PT perpendicular to the intersection of the hole 30 for the screw and the front surface 24, that is, at the height of the top edge 49. More specifically, the top edge 49 is at the intersection of the curved corner 51 and the front surface 24.

The material volume VF is the volume of the actual material from which the cutting insert 14 is made.

Preferably, each side abutment surface 38 extends upward from the main bearing surface 26 at a right angle β1 shown in FIG. 6.

The insert height HI extends from the main bearing surface 26 to the highest point of the rake surface 24 (noting that the cutting edge is part of the rake surface 24).

The overhang 44 has its lowest point 60 (FIG. 6) at the minimum height HU of the upper subsurface above the main bearing surface 26.

The top subsurface 36 (FIG. 6A) starts in the upward direction at the minimum top subsurface height HU above the main bearing surface 26, with the minimum top subsurface height HU being measured parallel to the plate axis AI.

As can be seen from FIG. 2, the additional hem 47A has a first edge portion 54 adjacent to one corner hem 46B and a second edge portion 56 that extends from the first edge portion 54 towards the adjacent corner hem 46A.

With reference to FIG. 2, 4A and 4B, a run-out recess 53 is formed under the second edge portion 56 of each additional under-edge 47. The run-out recess 53 is as short as possible in the direction along (below) the additional under-edge 47 in order to provide the desired capability of the slope processing function. surfaces without weakening adjacent parts of the cutting edge. For example, under the first part 54 of the additional under-hem 47A, there is no retraction at the overhang 44, as shown in FIG. 2 and 4A. This results in the vertical passage of a flat, unreleased surface 55 which extends below and along the first edge portion 54. In contrast, below the second edge portion 56 of the sub-hem 47A, the overhang 44 is inclined inwardly towards the main bearing surface 26, thereby forming a recess 53 below and along the second edge portion 56, as shown in FIG. 2 and 4B. In other words, the withdrawal recess 53 can be described as having a stepped shape in the direction along the additional under-edge 47.

This stepped shape provides strength to the rest of the cutting edge. Alternatively, a gradually decreasing shape in the direction along the additional under-hem 47 can be used.

In FIG. 4 shows the retraction angle ε. In particular, other surfaces adjacent to the rake face 24, in sectional views 4A-4C, are perpendicular thereto, thereby providing a preferred, stronger support for the cutting edge.

With reference to FIG. 5C, the longest distance 57 of the abutment face from the adjacent part of the cutting edge is shown near the main under-edge 48. The smallest distance 59 is shown near the additional under-edge 47. In particular, near the run-off recess 53.

Now with reference to FIG. 7A-8C, which show a socket 22 comprising a seating shoulder 62, a threaded socket hole 64 opening to the seating shoulder 62 and defining a minimum inscribed circle IP of the socket hole and an associated minimum socket hole diameter DP, first, second and third transverse thrusts. surfaces 66A, 66B, 66C (collectively referred to as "transverse abutment surfaces 66") perpendicular to seat abutment surface 62.

Between the transverse abutment surfaces 66 are first and second transverse recesses 67A, 67B (collectively referred to as "transverse recesses 67"). The use of transverse recesses 67 aids in defining the contact points of plate 14 and seat 22. Note that these contact points are shown in FIG. 8A with dashed lines.

Likewise, the socket opening 64 may be relatively large in cross section compared to the distance to the transverse abutments. This can be seen from the socket hole diameter DP and the distances from the socket hole 64 to the transverse thrust planes 66.

The first, second and third transverse thrust surfaces 66A, 66B, 66C are preferably oriented at the same orthogonal internal angle β1 as the thrust surfaces 38 of the insert.

Preferably, the screw axis AS may be offset from the center of the seating surface 62, i.e., may be slightly closer to where the transverse thrust surfaces 66 are closest to each other (i.e., the area indicated generally by 68), thus that the screw holding the cutting insert in seat 22 will move this cutting insert towards these transverse surfaces.

As shown in FIG. 7A, the seat is preferably inclined in the forward direction DF and cutting direction DC with respect to the rotation axis AR, as shown by the seat inclination angle μ. Preferably, the inclination angle μ of the socket can satisfy the condition 2°≤μ≤9°, and more preferably 5°≤μ≤8°.

With reference to FIG. 7C, a first imaginary extension line L1 extending from the leading edge 72 of one of the seating surfaces 62 may be parallel to a second imaginary extension line L2 extending from the leading edge 74 of the other seating abutment surface 62. The tool center plane PC contains a rotation axis AR, is located between and parallel to the first and second extension lines L1, L2 such that each seating abutment surface 62 faces the tool center plane PC. The first seating distance DS1 is defined from the first extension line L1 to the tool center plane PC. The second seating distance DS2 is set from the second extension line L2 to the tool center plane PC. The total distance DS3 is the sum of the first landing distance DS1 and the second landing distance DS2.

Alternatively, the total distance DS3 may be given relative to the plate. With reference to FIG. 1C, the total distance DS3 is greater than the insert height HI (only shown in FIG. 6 because the inserts are tilted in FIG. 1C). It should be understood that the space is limited to given dimensions. It should also be understood that if the plates are arranged such that their peripheral surfaces are spaced apart, instead of the present arrangement (that is, if the plate on the right side of Fig. 7C were moved to the bottom of the page and the plate on the left side to the top of the page ), then the structural strength of the tool holder for pocket 22 will be weakened (because there is less material to support the insert). On the contrary, if the inserts 14 are moved in the opposite direction, there may not be enough space in the recesses to remove the chips. Accordingly, in the most preferred arrangement, the peripheral surfaces are adjacent to each other.

With reference to FIG. 9A and 9B, the last of which shows the relative positions of the seated inserts, as shown in the front end view of this tool, the inserts have only a small gap between each other. To facilitate this, positive rake basic shapes have been provided and positioned as shown in FIG. 9A (that is, the cutting edges are not adjacent, and the peripheral surface of each insert is located near a portion of the peripheral portion of the other insert). The use of such features is one way of fitting relatively large inserts (relative to the diameter of the tool holder) into a relatively small circumscribed circle CC of the cutting diameter. The relationship for these features is described above.

With reference to FIG. 7A and 7D, due to the proximity of the plates 14, a support web 70 of limited length is provided.

The support bridge 70 extends to the most forward point 71A (at its center, also coinciding with the axis of rotation AR), which is recessed rearward from the front end 13B of the tool holder 12. It should be noted that the circle shape 71B shown is only indicative of a flat surface. As shown in FIG. 7A, the frontmost surface 71C has a concave shape.

When installed, the screw 16 secures the cutting insert 14 in such a way that the main bearing surface 26 rests against the landing abutment surface 62, and three of the insert abutment surfaces 38 abut against the three transverse abutment surfaces 66 of the socket. It should be understood that the cutting insert 14 can be repositioned in the seat 22 three times, and that it is not important to indicate exactly which abutment surfaces are in contact at any given time.

Note, for example, based on FIG. 1A that the top subsurface 36 is not in contact with the tool holder 12 and therefore inserts with slightly different cutting edges can be mounted in the same tool holder 12.

In FIG. 1B for high feed operations, the main cutting edge 48 is in contact with the workpiece (not shown). The depth of cut AP is relatively small compared to other types of milling operations.

It should be noted that in this non-limiting example, the main cutting edge 48 is located at a large distance from the axis of rotation AR (shown by distance F in the example). As a rule, this is a disadvantage, but provides a very small diameter cutter containing inserts with an allowable cutting width AE. For sloping operations, only the beveled portion 43 is in contact with the workpiece (the rest of the additional undercut 47 is not used).

Claims (62)

1. A single-sided, three-way indexable cutting insert having a basic shape with a positive rake angle and comprising: volume (VF) of material given by the amount of material of the cutting insert; front surface; a main bearing surface opposite the front surface; an axis (AI) of a plate extending perpendicular to the main bearing surface and through the center of said plate, wherein the plate axis defines an upward direction extending from the main bearing surface to the front surface, a downward direction opposite to the upward direction, and an outward direction perpendicular to the up and down directions and passing from the axis of the plate; insert height (HI) measured parallel to the insert axis and extending from the main bearing surface to the highest point of the rake surface; a peripheral surface connecting the front surface and the main bearing surface; a cutting edge formed at the intersection of the peripheral surface and the rake surface, wherein in a view parallel to the axis (AI) of the insert, the cutting edge defines an imaginary circumscribed circle (CE) of the edge having a circumscribed diameter (DE) of the edge; and screw hole opening to the front and main bearing surfaces, while the screw hole contains: the lower part of the screw hole, located at the intersection with the main bearing surface; the top of the screw hole located at the intersection with the front surface; void volume (VS) calculated as the void volume extending from the bottom of the screw hole to the top of the screw hole, and a hole circle (CS) given, in a view parallel to the plate axis (AI), at the intersection of the front surface and the screw hole, the hole circle (CS) having a hole diameter (DS); at the same time, in the bottom view parallel to the axis (AI) of the plate, the main bearing surface defines an imaginary main circumscribed circle (CB) having a main diameter (DB); the peripheral surface contains the first, second, third, fourth, fifth and sixth side thrust surfaces; in a top view parallel to the axis (AI) of the insert, the cutting edge defines an inscribed circle (CM) of the edge having an inscribed diameter (DM) of the edge, the cutting edge comprising: exactly three main hemlines and exactly three additional hemlines, with the main hemlines alternating with additional hemlines, and at each intersection between the main and additional hemlines there is a corner hemline; and the main circumscribed diameter (DB) is less than the circumscribed diameter (DE) of the edge; and the volume ratio of the volume (VS) of voids to the volume (VF) of the material satisfies the following condition: VS/VF≥0.30, and the circumscribed diameter (DE) of the edge satisfies the following condition: DE<6 mm. 2. The cutting insert according to claim 1, wherein the volume ratio satisfies the following condition: VS/VF≥0.35. 3. The cutting insert according to claim 1, wherein the volume ratio satisfies the following condition: 0.5>VS/VF. 4. The cutting insert according to claim 1, wherein the ratio of the insert thickness diameters for the hole diameter (DS) and the inscribed diameter (DM) of the edge satisfies the following condition: DS/DM>0.60. 5. A cutting insert according to claim 4, wherein the insert thickness diameter ratio satisfies the following condition: 0.80>DS/DM. 6. The cutting insert according to claim 1, wherein the ratio of the edge lengths for the length (LM) of the main trough and the length (LS) of the additional trough, each of which contains half of adjacent corner troughs, satisfies the following condition: LM/LS>0.80. 7. The cutting insert according to claim 6, wherein the edge length ratio satisfies the following condition: LM/LS>1.0. 8. The cutting insert of claim. 1, in which the length (LS) of the additional edge is the length of the additional edge, containing half of the corner sub-edges adjacent to it, and the effective length (LR) of the beveled edge is the length of the additional under-edge, measured near the released part of the peripheral surface, and satisfies the following condition: 0.4LS>LR>0.8LS. 9. The cutting insert of claim. 1, in which, with the exception of a portion of the peripheral surface near each additional under-edge, the remainder of the peripheral surface near the cutting edge is parallel to the axis of the insert. 10. The cutting insert according to claim 1, wherein in a top view parallel to the axis (AI) of the insert, all internal angles formed between the main and additional undercuts are obtuse. 11. An insert according to claim 1, wherein the described edge diameter (DE) satisfies the following condition: DE>4 mm. 12. The cutting insert of claim. 1, in which the main bearing surface is a single ground surface of the specified cutting insert. 13. The cutting insert according to claim 1, in which the six side thrust surfaces are perpendicular to the main bearing surface. 14. The cutting insert of claim. 1, in which the outlet recess is formed under part of each additional hem. 15. An insert according to claim 1, in which, in a bottom view parallel to the insert axis (AI), the greatest distance between the abutment surface and the adjacent part of the cutting edge is located near the main sub-edge. 16. An insert according to claim 15, wherein in a bottom view parallel to the axis (AI) of the insert, the shortest distance between the abutment surface and the adjacent part of the cutting edge is located near the additional under-edge. 17. Tool holder, containing: back end; front end; a tool periphery extending from a rear end to a front end; a rotation axis passing through the center of the tool holder, wherein the rotation axis defines a forward direction extending from the rear end to the front end, a backward direction opposite to the forward direction, an outward direction perpendicular to the rotation axis and directed from the rotation axis to the periphery of the tool, and a direction inward, opposite to the outward direction; part of the shank extending forward from the rear end; and a cutting portion extending forward from the shank portion to a front end, the cutting portion having a tool holder diameter (DT) at the front end and exactly two circumferentially spaced recesses extending rearward from the intersection of the front end and the periphery of the tool; wherein each of these recesses contains a socket formed at the intersection of the front end and the periphery of the tool; with each of the two sockets containing: landing thrust surface; a threaded hole of the nest opening to the landing thrust surface; and first, second, and third transverse abutments that are transverse to the seat abutment; and: each first transverse stop surface is located near the periphery of the tool and extends in outward and forward directions; each second transverse abutment surface is closer to the axis of rotation than the first transverse abutment surface and is separated from the first transverse abutment surface by a first retractable recess, with each second transverse abutment surface extending inward and forward directions; each third transverse abutment surface is closer to the axis of rotation, and also located more forward than the second transverse abutment surface, and is separated from the second transverse abutment surface by a second outlet recess, with each third transverse abutment surface extending inward and forward directions; and diameter (DT) of the tool holder satisfies the following condition: DT<11mm, in the top view of the landing thrust surface, the second and third transverse thrust surfaces are not parallel to each other. 18. The tool holder of claim 17, wherein a support web extends between the two sockets to a forwardmost point that is recessed from the front end of the tool holder. 19. The tool holder of claim 18, wherein the support web has a thin, elongated shape. 20. Tool holder according to claim 18, in which: (a) the central part of the frontmost surface of the support web is flat; or (b) in a side view of the tool holder, the frontmost surface of the support web has a concave shape, or (c) both are made. 21. The tool holder of claim 18, wherein the third transverse abutment surface is at least partially formed on the support web. 22. Insert-containing cutter containing tool holder according to any one of paragraphs. 17-21 and cutting plate according to any one of paragraphs. 1-16 installed in one of the sockets of the tool holder; moreover, exactly one of the main insert edges extends forward from the tool holder; exactly one of the insert's additional hems extends forward from the tool holder; and exactly one of the additional insert edges extends outward from the tool periphery.

Images