Cutting insert for severing metal workpiece

Abstract

A dual cutting edge severing insert (100) includes a first cutting portion (100, 110), a second cutting portion (112), and an elongate body portion (114) connecting the first cutting portion and the second cutting portion. The elongate body portion (114) has a body width (BW) measurable parallel to the transverse axis and a body length (BL) measurable parallel to the elongate axis. The body width is smaller than the cutout widths of the cutting edges of both the first body portion and the second body portion, and the following conditions are satisfied: 0.55 mmlt; bWlt; BWlt; the thickness is 0.95 mm; the length of the body meets the following conditions: 2 mmlt; bLlt; the thickness is 14 mm.

Description

Technical Field

[0001] The subject matter of the present invention relates to a cemented carbide cutting insert for cutting off a metal workpiece (hereinafter referred to as "cut-off insert" or "insert(s)" for the sake of simplicity). Background Art

[0002] The present invention relates to an insert for cutting off a metal workpiece. It will be understood that an insert constructed for cutting off is also constructed for grooving, as both involve similar machining processes. That is, both operations involve only forward movement relative to the workpiece (in other words, there is no lateral or transverse movement component). The difference between the cutting off operation and the grooving operation lies solely in the extent to which the cutting edge of the insert that cuts or machines a slit-shaped cut (an example of a slit-shaped cut of the type discussed is shown in FIG. 7B of WO 2022 / 084992 and is labeled “S”; also referred to as a “slit” hereinafter) enters the workpiece. In the grooving operation, unlike the cutting off operation, the slit extends relatively little into the workpiece, i.e., less than about half of the rotating workpiece, and therefore does not “cut” the workpiece into two separate parts. In the cutting off operation, the slit-shaped cut extends far enough into the workpiece to cut through the workpiece (i.e., completely separate a piece from the workpiece).

[0003] To be clear, in the description and claims of the present application, the insert is referred to as a cut-off insert, but it should be understood that such a cut-off insert is also inherently configured to produce a groove for a slit of the type shown in WO 2022 / 084992.

[0004] To create the slit, the cutting edge of the insert extends along the entire transverse length of the insert (i.e., the transverse or lateral direction perpendicular to the forward direction). The transverse extent of the cutting edge including the corners is referred to as the kerf width (usually denoted "CW", as in US Pat. No. 11,278,968). Figure 2 C, although in this document it is referred to as "cutting width W C ”).

[0005] It is worth noting that the present invention includes so-called neutral inserts as well as right and left inserts, wherein in a plan view of the rake surface (such a plan view is in the US Pat. No. 11,278,968) Figure 2 C, although other names for such views are interchangeable as referred to in the document), the cutting edge may extend perpendicularly or obliquely to the forward direction. Figure 2 , Figure 3 and Figure 4 , which shows a plan view of the rake surface of inserts that are identical except that they are a neutral type insert, a left type insert, and a right type insert, respectively.

[0006] For details, refer to Figure 2 , showing the elongation axis A E Elongated insert 100. Elongation axis A E Define the forward (or cutting) direction D F and a backward direction D opposite to the forward (or cutting) direction R For purposes of this description only, the first cutting edge 102 is selected as the operative cutting edge and thus when the insert is moved in the forward direction D F When it is moved toward a workpiece (not shown), it is used to cut or groove the workpiece. At the end of the insert 100 opposite the first cutting edge 102, there is a second cutting edge 104, which only becomes operable after the insert is indexed in the tool pocket (not shown).

[0007] The transverse axis A extending through the forwardmost portion of the cutting edge 102 L Perpendicular to the elongation axis A E Extends and defines a first lateral direction D S1 and the first lateral direction D S1 The second opposite lateral direction D S2 .

[0008] For the sake of completeness, it is noted that the first central axis A C1 (Also called "vertical axis A C1 ”) extends through the center of the insert and is perpendicular to the elongation axis A E and transverse axis A L Both.

[0009] Also there Figure 5C and Figure 5D The second central axis A shown in C2 Extends through the center of the insert and is perpendicular to the axis of elongation A L and parallel to the transverse axis A L .

[0010] Since the illustrated insert 100 is centered about the first central axis A C1 (ie, vertical axis) 180° rotational symmetry, only the first cutting edge 102 will be discussed in detail.

[0011] The first cutting edge 102 includes: a frontmost cutting sub-edge 102A (ie, the first cutting edge 102 is in the forward direction D FThe first right sub-edge 102C extends from a second corner 102E connecting the forward cutting sub-edge 102A and the first right sub-edge 102C in a substantially rearward direction.

[0012] Figure 2 The first cutting edge 102 seen in FIG. 1 is a neutral cutting edge, which means that the frontmost cutting sub-edge 102A is aligned with the transverse axis A. L Basically parallel.

[0013] In contrast, Figure 3 2 shows a so-called "left" insert 200 which is identical in all respects except for the cutting edge, the forwardmost cutting sub-edge 202A being oriented relative to the transverse axis A. L More specifically, the frontmost cutting sub-edge 202A is inclined in the second lateral direction D S2 and backward direction D R Extends to the horizontal axis A L An acute angle 204 is formed.

[0014] Similarly, Figure 3 1 shows a so-called "right" insert 300 which is identical in all respects except for the cutting edge, the forwardmost cutting sub-edge 302A being oriented relative to the transverse axis A. L More specifically, the frontmost cutting sub-edge 302A is inclined in the first lateral direction D S1 and backward direction D R Extends to the horizontal axis A L An acute angle 304 is formed.

[0015] In summary, because different cutting edge shapes fall within the scope of the present invention, the lengths discussed and defined below associated with the forward-most cutting sub-edge 102A should be measured from its forward-most point.

[0016] Additional general issues associated with such inserts and common cut-off insert features will now be discussed.

[0017] The first key consideration for a cut-off insert is the kerf width CW. The kerf width CW of a cut-off insert is generally preferred to be as small as possible to reduce waste of the workpiece being machined. However, due to strength and machining force considerations, the operator has no choice but to select a relatively large kerf width to ensure that there is no breakage. In US 11,278,968, which describes the inventor's invention, there is a cut-off insert that is designed to counteract such machining forces to ensure that even a smaller insert than previously known will not break under relatively high-force machining conditions. Nevertheless, given the machining forces, the general preference is to select the smallest possible kerf width for a given machining operation.

[0018] Some common cut-off insert features will be described below with reference to the reference numerals designating the features in the drawings in US 1 1 ,278,968, all for the purpose of facilitating an understanding of typical design features.

[0019] At the cutting portion, the front and lateral surfaces (24, 78, 80) adjacent to the cutting edge (i.e., extending downwardly from the cutting edge) are typically relieved (i.e., "flank surfaces") so that they do not contact the slot in the workpiece formed by the cutting edge. In other words, they extend in both a downward and inward direction.

[0020] The cutting edge (54) is formed along the intersection of the so-called rake (also referred to as "upper surface") surface (22) of the insert with the front and lateral surfaces (24, 78, 80).

[0021] The rake surface (22) typically has a chip forming formation (56) which usually comprises one or more downwardly extending recesses, but may alternatively consist of or include upwardly extending projections, although this is less common.

[0022] Behind the cutting edge, in a plan view of the rake surface (22), similar to the front and lateral surfaces (24, 78, 80), at least a portion of the insert body immediately adjacent the rake surface is relieved from the cutting width defined by the cutting edge (see Figure 2 C). In other words, the portion is thinner than the cutting width (ie, extends in an inward lateral direction on both sides) so that the insert body does not contact the slot in the workpiece formed by the cutting edge.

[0023] Currently, the most popular material for inserts is cemented carbide. During production, cemented carbide is pressed and then sintered. During the sintering process, inserts (especially those with thin, elongated shapes, which are particularly desirable for small kerf widths) can become deformed. This is another important design consideration for cut-off inserts.

[0024] The above-described features are typical for the type of inserts to which the present invention relates, namely, cemented carbide inserts configured for parting operations.

[0025] A second key design consideration for a cut-off insert is the kerf depth (which will be denoted hereinafter as "DC"). A relatively large kerf depth is preferred because it allows the cutting tool to cut through both smaller diameter workpieces and relatively larger diameter workpieces (or relatively deep grooves, etc.). The kerf depth is limited by the insert or tool having a portion that is wider than the cutting edge that creates the slit. To explain, the cutting edge creates the slit and the insert at least partially enters the workpiece. In a plan view of the rake surface, when the enlarged portion of the insert or tool first reaches the workpiece, the insert cannot enter further without an undesirable impact because the enlarged portion (of the insert or tool) cannot enter the slit created by the cutting edge. Therefore, it is preferred that at least as much of the insert as possible is thinner than the cutting edge, i.e., "relieved," in a plan view of the rake surface so that it does not contact the walls of the slit being machined.

[0026] Therefore, the best solution is to allow unlimited cut depth (at least not limited by the insert) by designing the insert to be overall thin in a plan view of the rake surface, and thus the cut depth is limited only by the tool.

[0027] In a first example, this can be provided by an insert having a single cutting edge and the remainder of the cutting insert being thinner than the cutting edge in a plan view of the rake surface. Thus, the single cutting edge provides unlimited kerf depth capability, at least not limited by the insert itself, even though the tool holding the insert will limit the kerf depth to some extent. Hereinafter, this design will be referred to as a classic single cutting edge insert (or "single cutting edge insert").

[0028] The most commonly sold cut-off insert is probably a single cutting edge insert (an arbitrarily chosen example is shown in US 11,278,968). A single cutting edge insert comprises a cutting portion which in turn comprises a rake surface and a relief surface extending substantially downwardly and inwardly from the rake surface. Only a single cutting edge is formed at the intersection of the rake and relief surfaces. The insert also comprises a shank portion behind the cutting portion which is designed to be attached or retained to a tool (the "tool" may be a blade or insert holder having a square or round shank, etc.).

[0029] Thus, the third key design consideration for an insert is met by the popular single cutting edge insert, i.e., it can be made of the smallest possible amount of expensive carbide material and can be press-formed (i.e., no separate grinding is required, although in some cases separate grinding is performed for applications that require it). However, generally speaking, press-formed inserts do not have ground surfaces.

[0030] A fourth key design consideration for the insert is the number of cutting edges, wherein each additional cutting edge is preferred because the insert can be used for machining for an overall longer amount of time before being discarded (ie, increased "tool life").

[0031] Therefore, a second type of highly popular cut-off insert has two cutting edges, the additional cutting edge providing a significant benefit over single cutting edge inserts. Dual cutting edge inserts provide added economic value to the user by allowing the second cutting edge to be used after the first cutting edge wears.

[0032] In the most common configuration discussed here, each cutting edge is located at opposite ends of the same rake surface. Hereinafter, this design will be referred to as a classic double cutting edge insert. The rake surface includes a first sub-rake surface and a second sub-rake surface, which are visible in the same plan view of the rake surface. In the plan view of the rake surface, each sub-rake surface is separated by a relatively thin and elongated body portion. In other words, the insert includes two cutting portions and a body portion extending therebetween, and each cutting portion includes a corresponding one of the first sub-rake surface and the second sub-rake surface.

[0033] However, the depth of the cut that can be produced by such an insert is limited by the distance between the two cutting portions (ie the point at which the cutting insert widens again to where it contacts the slit being produced, which is also the second sub-rake surface).

[0034] Thus, the classic double-edge insert has one major advantage (the number of cutting edges) and one major disadvantage (the depth of the cut) compared to the single-edge insert.

[0035] The classical dual cutting edge insert design also suffers from a moderate disadvantage in that the kerf width CW cannot be made as small as a single cutting edge insert (e.g., the applicant offers a single cutting edge insert with a minimum kerf width of 0.6 mm and a dual cutting edge insert with a minimum kerf width of 1.4 mm). This difference is due to the elongated body portion of the classical dual cutting edge insert design deforming during the sintering process if made unacceptably thin.

[0036] Additionally, the classic dual cutting edge insert design has the minor disadvantage that it requires more material due to the need for the second cutting portion.

[0037] A known design developed to overcome the main drawback of the classic double cutting edge insert, namely the kerf depth limitation, is the so-called "twist-off insert". An example of a twist-off insert can be found in US 5,156,502. The twist-off insert differs from the classic double cutting edge insert in that the two cutting parts are not in parallel planes, but are twisted relative to each other so that the rake faces do not face exactly in the same direction. This adjusts the non-operating cutting edge so that in a plan view of the rake surface of the operating cutting edge, the rest of the insert is thinner than the kerf width CW.

[0038] The main advantage of a twist-type insert over a classic two-cutting edge insert design is that it allows for unlimited cut depth (at least relative to the insert and not the tool holding it).

[0039] The disadvantage of the twist-type insert when compared to a classic dual cutting edge insert is that it can only be manufactured with relatively large cut widths (especially when compared to the very small cut widths of smaller single cutting edge inserts), and some compromise is made in securing the insert to the pocket.

[0040] In summary, the three well-known and sold types of inserts described above include: single cutting edge inserts, which have the advantage of unlimited cut depth and are the cheapest inserts to manufacture; classic dual cutting edge inserts, which have the major advantage of another cutting edge, but are significantly limited in cut depth relative to single cutting edge inserts, and are slightly limited in cut width and manufacturing cost; and twisted dual cutting edge inserts, which have the advantages of unlimited cut depth and two cutting edges, but are even more limited in cut width than the other two.

[0041] Since each solution has advantages and disadvantages, the industry has long been in need of a better solution. Therefore, many different solutions have been conceived to provide even better cut-off inserts, some of which from the present applicant are mentioned below.

[0042] One solution developed is a double cutting edge insert with an enlarged central portion (sold by the applicant Iscar Inc. under the name DO-GRIP DGN 1002, hereinafter referred to as the "DGN insert"), which can produce a small cut width (1 mm), which is smaller than the cut width of the classic double cutting edge insert mentioned above, but not the cut width of the smallest single cutting edge insert, and of course has the benefit of two cutting edges, but due to the enlarged central portion, it is expensive to manufacture and the cut depth is extremely limited (3 mm).

[0043] Yet another solution disclosed in USP 10,363,722 B2 is a relatively large double-edged insert without an enlarged central portion. By providing such a large insert, a relatively large cut depth and a relatively small cut width (less than 1.5 mm specified in the patent) are achieved. However, the height of the insert is very large and therefore expensive due to the large amount of material and a rather unique insert pocket is required for this purpose.

[0044] An object of the present invention is to provide a new and improved cut-off insert.

[0045] Such an objective is not a simple task, as many solutions for improved cut-off inserts have been attempted, a small number of which are described in detail above. Summary of the invention

[0046] In search of an improved cut-off insert, given the known variables identified above, it was contemplated to provide a modified carbide dual cutting edge insert (hereinafter) having a superior (ie, smaller) kerf width that could compete with single cutting edge inserts in the minimum kerf width range.

[0047] It is believed that such inserts have not been produced to date due to known problems with thin elongated inserts deforming during the sintering process.

[0048] As will be appreciated, the straightness of a cut-off insert intended to enter a slot over a wide range of its length is critical to the cut-off process.

[0049] In detail, as mentioned above, a difficulty faced by such designs is the inherently problematic nature of producing extremely thin, elongated cemented carbide inserts which are susceptible to deformation.

[0050] The deformation can be counteracted by thickening the insert (which is undesirable here since the kerf width is preferably as small as possible), which would essentially result in a classic double-cutting edge insert with a known kerf width.

[0051] Alternatively, the deformation can be counteracted by shortening the insert (undesirable here because shortening the distance between thicker cutting portions results in relatively smaller cut depths and reduces the range of workpiece diameters that can be cut), which would essentially result in an insert having similar capabilities to a DGN insert.

[0052] Yet another difficulty is that, regardless of the length of the insert, it is never possible to obtain a kerf width as small as that achievable with a classic single cutting edge insert, since larger sized double cutting edge inserts always have a larger width to avoid deformation during sintering.

[0053] Therefore, in order to minimize the chance of deformation while still obtaining favorable kerf width and kerf depth having certain values, the present invention provides a slightly unfavorable kerf width, which is larger than the kerf width of a single cutting edge insert with a smaller kerf width (0.6 mm), but smaller than the kerf width of known classic double cutting edge inserts (1.4 mm), and is therefore favorable compared thereto.

[0054] In order to achieve said kerf width, yet another compromise is made, namely, in order to further minimize the risk of deformation, a second step is to provide a shorter length than a classic double cutting edge insert, thereby limiting the kerf depth, so as to further mitigate the expected deformation. Although this also reduces the suitability for use (i.e., only workpieces of smaller diameter can be cut off), it is believed that the overall benefit of the better kerf width of the classic double cutting edge insert than previously known, coupled with the advantage over the classic single cutting edge insert due to the presence of two cutting edges, provides a possible new and advantageous insert for at least a portion of the market segment.

[0055] During production of the prototypes, despite concerns, the dimensions described below were found to have small enough deformation to be within acceptable tolerances.

[0056] As explained above, many niche-type inserts have been tried, for example, the present invention has a comparable cut width to the DGN 1002 insert, but with a significantly greater cut depth.

[0057] Additionally, the present invention has a smaller cutout depth and a slightly smaller cutout width than the insert according to USP 10,363,722, but uses much cheaper materials during manufacture.

[0058] According to a first aspect of the present invention, a double-cutting-edge cutting insert is provided, comprising: a first cutting portion; a second cutting portion; an elongated body portion connecting the first cutting portion and the second cutting portion; a front cutting surface; a base surface, the base surface being positioned opposite to the front cutting surface; and a peripheral surface connecting the front cutting surface and the base surface; the peripheral surface comprising: a front sub-surface at the first cutting portion; a rear sub-surface, the rear sub-surface being located at the second cutting portion and being positioned opposite to the front sub-surface; a left sub-surface connecting the front sub-surface and the rear sub-surface and being located at one side of the cutting insert; and a right sub-surface connecting the front sub-surface and the rear sub-surface and being positioned opposite to the left sub-surface; the body portion is elongated along an elongation axis extending through the center of the body portion; the elongation axis (A E ) defines a forward direction (D) from the second cutting portion toward the first cutting portion F ) and the backward direction opposite to the forward direction (D R ); the cutting insert has a longitudinal axis (AE ) measured insert length (IL); cut insert perpendicular to the elongation axis (A E ) measured height (H); the first central axis (A C1 ) is defined as being perpendicular to the elongation axis and extending through the center of the cut-off insert and through the base surface and the rake surface, the first center axis (A C1 ) defines an upward direction (D) from the base surface toward the rake surface U ) and the downward direction opposite to the upward direction (D D ); the second central axis (A C2 ) is defined as perpendicular to the elongation axis (A E ) and the first central axis (A C1 ) and extending through the center of the cut insert, the second center axis (A C2 ) defines a first lateral direction (D S1 ) and a second lateral direction (D S2); the first cutting portion includes: a first sub-front blade surface at the front blade surface; a first front sub-rear blade surface at the front sub-surface; a first left sub-rear blade surface at the left sub-surface; a first right sub-rear blade surface at the right sub-surface; a first cutting edge, the first cutting edge is formed at the intersection of the first front sub-front blade surface and each of the first front sub-rear blade surface, the first left sub-rear blade surface and the first right sub-rear blade surface; the first cutting edge includes: a first frontmost cutting sub-edge, the first frontmost cutting sub-edge is along the first sub-front blade surface and the intersection of the first front sub-rear blade surface; a first left sub-edge, the first left sub-edge extending along the intersection of the first sub-front blade surface and the first left sub-rear blade surface; a first right sub-edge, the first right sub-edge extending along the intersection of the first sub-front blade surface and the first right sub-rear blade surface; a first left corner, the first left corner formed at the intersection of the first frontmost cutting sub-edge and the first left sub-edge; and a first right corner, the first right corner formed at the intersection of the first frontmost cutting sub-edge and the first right sub-edge; a second The cutting portion includes: a second front blade surface at the front blade surface; a second front sub-relief blade surface at the rear sub-surface; a second left sub-relief blade surface at the right sub-surface; a second right sub-relief blade surface at the left sub-surface; a second cutting edge formed at the intersection of the second front sub-front blade surface and each of the second front sub-relief blade surface, the second left sub-relief blade surface, and the second right sub-relief blade surface; the second cutting edge includes: a second frontmost cutting sub-edge, the second frontmost cutting sub-edge extending along the second sub-front blade surface and the second front sub-relief blade surface. The cutting edge of the second cutting blade is formed at the intersection of the second front cutting blade and the second left cutting blade; the second right cutting blade is formed at the intersection of the second front cutting blade and the second right cutting blade; the second left turning corner is formed at the intersection of the second front cutting blade and the second left cutting blade; and the second right turning corner is formed at the intersection of the second front cutting blade and the second right cutting blade; the transverse axis (A) L ) extends through the forwardmost portion of the first cutting edge, the transverse axis (A L ) is parallel to the second central axis (A C2 ) extends and defines a first lateral direction (DS1) and a first lateral direction (D S1 ) in the opposite second lateral direction (D S2); the first cutting edge has a first kerf width (CW1) that can be measured parallel to the transverse axis and from the first left corner to the first right corner; the second cutting edge has a second kerf width (CW2) that can be measured parallel to the transverse axis and from the second left corner to the second right corner; the slender body portion has a body width (BW) that can be measured parallel to the transverse axis and a body length (BL) that can be measured parallel to the elongation axis; wherein: the body width (BW): is smaller than both the first kerf width (CW1) and the second kerf width (CW2); and satisfies the following conditions: 0.55mm≤BW≤0.95mm; and the body length (BL): satisfies the following conditions: 2mm≤BL≤14mm.

[0059] In other words, according to a second aspect of the present invention, there is provided a double cutting edge cut-off insert comprising: a first cutting portion; a second cutting portion; a body portion connecting the first cutting portion and the second cutting portion; Rake surface; a base surface positioned opposite the rake surface; and an outer peripheral surface connecting the rake surface and the base surface; The first cutting portion includes a first sub-rake surface at the rake surface; The second cutting portion includes a second sub-rake surface at the rake surface; The body portion has a body width (BW) measurable parallel to the transverse axis and a body length (BL) measurable parallel to the elongation axis; Body width (BW): meets the following conditions: 0.55mm≤BW≤0.95mm; and Body length (BL): meets the following conditions: 2mm≤BL≤14mm.

[0060] It will be appreciated that according to each of the above aspects, it has been found that a body portion of a given size can be produced within an acceptable amount of deformation.

[0061] Preferably, the body width (BW): satisfies the following conditions: 0.65 mm ≤ BW, and more preferably 0.75 mm ≤ BW. It will be appreciated that increasing the body width reduces the amount of deformation. It is also preferred that BW ≤ 0.85 mm to allow for sufficient clearance with the cut width.

[0062] Although even a body length just greater than 2 mm is beneficial, since it is known from DGN inserts that there is a market demand for a cut depth DC of only 3 mm (remember that the cutting portion itself has a length), a longer body length (BL) is of course preferred. For example, it is preferred that the body length (BL) satisfies the following condition: 6 mm ≤ BL, more preferably 8 mm ≤ BL. It will be appreciated that even if increasing the body length increases deformation, it makes a greater number of machining operations feasible (e.g., cutting off relatively large workpieces). In addition, it provides another advantage over smaller single cutting edge inserts in that the overall length of the insert is longer and therefore easier to hold and move. Nevertheless, too large a body length is considered to risk increasing deformation to an unacceptable level, and therefore an upper limit of 14 mm is defined above to avoid increasing deformation to an unacceptable amount. Preferably, the condition BL ≤ 12 mm and more preferably BL ≤ 11 mm is satisfied.

[0063] Preferably, the first kerf width (CW1) and the second kerf width (CW2) satisfy the following conditions: 0.75 mm ≤ CW1, CW2 ≤ 1.1 mm, more preferably 0.9 mm ≤ CW1, CW2 ≤ 1.1 mm. It will be appreciated that, although this kerf width is less advantageous than the minimum kerf width of a smaller single cutting edge insert (~0.6 mm), it is still more advantageous than the smallest double cutting edge insert known to the applicant at this time. It should also be appreciated that a reduction in the kerf width means that the insert is less able to handle the cutting forces, and therefore in order to maintain the possibility of machining at reasonable feed rates, a minimum kerf width value of 0.8 mm is preferred, more preferably 0.9 mm. Similarly, in order to have an increased benefit over the kerf width of known classic double cutting edge inserts, a maximum kerf width value of 1.1 mm is preferred. One most preferred kerf width is equal to 1.0 mm ± 0.04 mm. Another most preferred kerf width is equal to 0.8 mm ± 0.04 mm.

[0064] Preferably, the cut-off insert has a first working length OL1, which can be measured parallel to the axis of elongation from the forwardmost point of the first cutting edge to the intersection of the body portion and the second cutting portion (i.e. where the insert starts to widen relative to the body portion), satisfying the following condition: 5mm≤OL1≤15mm. More preferably, the condition 9mm≤OL1≤13.5mm and most preferably 11mm≤OL1≤12.5mm is satisfied. As explained above, even if increasing the body length increases deformation, it makes a greater number of machining operations feasible and allows the insert to be held more easily. However, too large a length risks increasing deformation to an unacceptable level, and therefore an upper limit is preferred.

[0065] The cut-off insert may include a EMeasured insert length IL. Preferably, the insert length IL satisfies the condition of 4 mm ≤ IL ≤ 16 mm, more preferably 11 mm ≤ IL ≤ 15 mm and most preferably 13 mm ≤ IL ≤ 14 mm.

[0066] The first cutting portion 110 also includes a E Measure the length L of the first cutting portion C1 Preferably, the first cutting portion has a length L C1 Meet 1.25mm≤L C1 ≤1.5mm and most preferably 1.30mm≤L C1 ≤1.40mm. The same value is for the second cutting portion length L C2 It is also preferred.

[0067] Preferably, the cut-off inserts are press-formed (and thus not ground, and thus have no ground surfaces). Press-forming increases manufacturing advantages, for example, over larger types of inserts, such as DGN inserts and the inserts disclosed in USP 10,363,722. Notably, ground inserts are identifiable because they exhibit oriented lines. In detail, a technician can determine if an insert has been ground because even after very elaborate post-coating treatments, such as polishing, the post-treatment removes material and leaves a visible pattern of parallel lines, as opposed to an unground insert which has a more random marking.

[0068] Preferably, the cutting insert is arranged around the first central axis A. C1 180° rotational symmetry.

[0069] Preferably, the height H of the body portion satisfies the condition 3.5 mm ≤ H ≤ 4.5 mm, more preferably 4.0 mm ≤ H ≤ 4.3 mm. This corresponds to the height of a classic double cutting edge insert, and it is preferred not to reduce this dimension, as this would increase deformation without significant benefit.

[0070] However, it was found that the corners may preferably be manufactured with a radius R satisfying the condition 0.8 mm ≤ R ≤ 1.20 mm, which is an improvement over the 0.16 mm radius of the applicant's prior classic double cutting edge inserts.

[0071] Preferably, each of the first cutting portion and the second cutting portion comprises a chip former arrangement. More preferably, the chip former arrangement comprises a single recess.

[0072] The above inserts will now be compared using an arbitrary rating system of 1 to 5 (where "1" is the lowest score and "5" is the highest score) (relative values ​​are assigned after specifically looking at these inserts being compared to each other) and using the following criteria: (a) cut depth (where larger cut depths are preferred), (b) cut width (where smaller cut widths are preferred, the values ​​shown are minimums for applicant's products and patents and are approximate in the event that real-world products are not on the market), (c) material cost (where relatively small amounts of material are preferred; although not mentioned in the name "material cost", manufacturing complexity is also included in this category) and (d) two cutting edges (where two cutting edges are preferred over a single cutting edge).

[0073] While the values ​​shown below are subjective and are affected by many factors, they give an indication of the basic considerations that were taken into account when developing the inserts of the present application that were customized for smaller kerf width applications.

[0074] In general, the classic single cutting edge still compares favorably to the other double cutting edge types, at least at the smallest kerf width dimensions.

[0075] Nevertheless, at unique kerf width dimensions of about 0.8 mm and 1 mm (or more precisely 0.8 mm ± 0.1 mm and 1 mm ± 0.1 mm), it is believed that the introduction of a new dual cutting edge insert of the classical dual cutting edge insert type is beneficial.

[0076] After producing prototypes, it was found that at these dimensions, the deformation was at an acceptable level.

[0077] Some disclaimers about these values:

[0078] The kerf width values ​​assume that the application for which the selected smaller kerf width is desired. For heavy duty machining applications, smaller kerf widths may conversely be undesirable as their structural strength may be preferred over saving workpiece material.

[0079] While it is generally correct that two cutting edges are preferred over a single cutting edge, the indication that two cutting edges are far superior to a single cutting edge is inaccurate because in practice inserts often break, meaning that the operator loses the ability to utilize the second cutting edge of the same insert (which is typically more expensive than a single cutting edge insert).

[0080] In summary and according to the table above, the cut-off insert according to the present invention is: advantageous over a single-edge insert in that it has two cutting edges, but is significantly inferior to the single-edge insert in terms of cut depth and slightly inferior to the single-edge insert in terms of cut width; is slightly advantageous over a classic double-edge insert in that it has a slightly smaller cut width, but is inferior to the classic double-edge insert in terms of cut depth; is advantageous over a twisted double-edge insert in that it has a significantly smaller cut width, but is inferior to it in terms of cut depth; is advantageous over a DGN insert in that it has a larger cut depth and a smaller manufacturing cost; and is slightly advantageous over the insert disclosed in USP 10,363,722 in terms of cut width and a smaller manufacturing cost, but is inferior in terms of cut depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to better understand the subject matter of the invention and to show how the application can be implemented in practice, reference will now be made to the accompanying drawings derived from a scale model, in which: Figure 1 is a perspective view of a cut-off insert according to the present invention; Figure 2 yes Figure 1 A plan view of the rake surface of the insert in FIG. Figure 3 is a plan view of the rake surface of another insert according to the present invention, and the insert is Figure 1 The insert in is different only in that it is a "left" type insert; Figure 4 is a plan view of the rake surface of yet another insert according to the present invention, and the insert is Figure 1 and Figure 3 The insert in is different only in that it is a "right" type insert; Figure 5A yes Figure 1 A front view of the insert in FIG. Figure 5B yes Figure 5A A plan view of the rake surface of the insert in Figure 2 same view); Figure 5C yes Figure 5A Right side view of the insert in; Figure 5D yes Figure 5A a bottom view of the insert in; and Figure 5E yes Figure 1 Rear view of the insert in . DETAILED DESCRIPTION

[0082] Figure 1 , Figure 2 and FIG. 5A to FIG. 5EAn exemplary cut-off insert 100 according to the present invention is illustrated and will be described in additional detail below. Figure 3 and Figure 4 A cut-off insert according to the invention is also illustrated, but the differences from the cut-off insert 100 have already been described in sufficient detail above.

[0083] The cut-off insert 100 includes a first cutting portion 110, a second cutting portion 112, and an elongated body portion 114 connecting the first cutting portion and the second cutting portion.

[0084] The arrow labeled "116" shows the area (hereinafter referred to as "transition area 116") where the cutting portion (in this example, the second cutting portion 112) transitions to become the elongated body portion 114. While this is visible by the thinning of the cutting portion until it reaches the width of the elongated body portion, it should also be understood that the cutting portion is functionally associated with the cutting function (i.e., in contact with the workpiece (not shown) and chips machined therefrom), while the body portion is not configured to provide a cutting function.

[0085] The cut-off insert 100 also includes a rake surface 118 , a base surface 120 (also referred to as a “lower surface”; the base surface lacks a cutting edge), and a peripheral surface 122 .

[0086] refer to Figure 2 The body portion 114 is arranged along an elongated axis A extending through the center thereof. E Elongation. Elongation axis A E A forward direction D is defined from the second cutting portion 112 toward the first cutting portion 110. F and forward direction D F Opposite backward direction D R .

[0087] Referring also to the rest of the drawings, the first central axis A C1 The vertical axis is defined as being perpendicular to the axis of elongation A. E and extends through the center of the cut-off insert 100 and through the base surface 120 and the rake surface 118, and as Figure 5C The defined upward direction D shown in U and downward direction D D .

[0088] The second central axis A C2 is defined as perpendicular to the elongation axis A E and the first central axis A C1 and extending through the center of the cutting insert 100, the second center axis A C2 Define a first lateral direction D S1 , and the first lateral direction D S1The second opposite lateral direction D S2 .

[0089] The cutting insert 100 includes a E Measure the Insert length IL.

[0090] For the sake of brevity, some of the following descriptions may be directed to only a portion of the cutting insert 100 because it is centered around the first central axis A. C1 Rotationally symmetric, it will be appreciated that such a feature also exists at the opposite end of the cut-off insert 100 .

[0091] The outer peripheral surface 122 includes a front sub-surface 122A at the first cutting portion 110 , a rear sub-surface 122B located at the second cutting portion 112 , a left sub-surface 122C, and a right sub-surface 122D.

[0092] The first cutting portion 110 comprises a first sub-rake surface 110A at the rake surface 118. The first sub-rake surface 110A comprises a chip former arrangement 124 in the form of a single recess.

[0093] The first cutting portion 110 also includes a first front sub-relief surface 110B at the front sub-surface 122A, a first left sub-relief surface 110C at the left sub-surface 122C; and a first right sub-relief surface 110D at the right sub-surface 122D. It is worth noting that the illustrated preferred sub-relief surfaces (which are inclined inwardly) do not extend to the base surface 120, however, it is also feasible that they extend to the base surface 120. As shown in the preferred embodiment, the sub-relief surfaces extend less than one-third of the height H of the cutting insert 100.

[0094] The first cutting edge 102 is formed at an intersection of the first front sub-relief surface 110A and each of the first front sub-relief surface 110B, the first left sub-relief surface 110C, and the first right sub-relief surface 110D.

[0095] Reference above Figure 2 Various portions of the cutting edge 102 are depicted.

[0096] The first cutting portion 110 also includes a E Measure the length L of the first cutting portion C1 Similarly, the second cutting portion 112 may include a second cutting portion length L C2 .

[0097] Behind the cutting edge, in a plan view of the rake surface (22), similar to the front and lateral surfaces (24, 78, 80) of US 11,278,968, at least a portion of the insert body immediately adjacent the rake surface is relieved from the kerf width defined by the cutting edge (see Figure 2 C). In other words, the portion is thinner than the kerf width (ie, extends in an inward lateral direction on both sides) so that the insert body does not contact the slit in the workpiece formed by the cutting edge.

[0098] The first cutting edge 102 has a first kerf width CW1 , and the second cutting edge 104 has a second kerf width CW2 .

[0099] The elongated body portion 114 has a body width BW and a body length BL.

[0100] The insert length IL is equal to the body length BL plus the first cutting portion length L C1 and the second cutting portion length L C2 (IL=BL+L C1 +L C2 ).

[0101] Because when the first cutting portion 100 is the operating cutting portion (ie, the cutting insert 100 is in the forward direction D F The cutting insert 100 (moving relatively upward toward the workpiece) can only enter the slit until the width of the insert body becomes wider (considering that the body width BW is designed to be as wide as possible even at its thinnest part to avoid unnecessary weakening of the structure), the cut depth DC is effectively equal to the first working length OL1, which can be measured from the forwardmost point of the first cutting edge 102 to the transition area 116 between the slender body portion 114 and the second cutting portion 112.

[0102] After indexing the insert with respect to the second cutting portion 112, the cut-off insert 100 will have the same cut depth DC, ie, the second working length OL2.

[0103] The insert may have a first insert ratio R1, which is defined as the ratio of the kerf depth to the first cutting width (R1=DC / CW1). Thus, for an insert having a kerf depth DC=12 mm and a first cutting width CW1=1 mm, the first insert ratio is 12. Preferably, the first insert ratio R1 of the cutting insert according to the subject matter of the present application satisfies the following conditions: 6≤R1≤16, more preferably 10≤R1≤14, and most preferably 11≤R1≤13.

[0104] The insert may have a second insert ratio R2, which is defined as the ratio of the length IL of the insert to the height H of the insert (R2=IL / H). Thus, for an insert with a length IL=14 mm and a height H=4 mm, the second insert ratio is 3.5. Preferably, the second insert ratio R2 of the cutting insert according to the subject matter of the present application satisfies the following conditions: 1≤R2≤4.5, more preferably 2.5≤R2≤3.8, and most preferably 3≤R2≤3.6.

Claims

1. A double cutting edge cutting insert, comprising: a first cutting portion; a second cutting portion; an elongated body portion connecting the first cutting portion and the second cutting portion; Rake surface; a base surface, the base surface being positioned opposite to the rake surface; as well as an outer peripheral surface connecting the rake surface and the base surface; The peripheral surface comprises: a front sub-surface at the first cutting portion; a rear sub-surface located at the second cutting portion and positioned opposite the front sub-surface; a left sub-surface connecting the front sub-surface and the rear sub-surface and located at one side of the cutting insert; and a right sub-surface, the right sub-surface connecting the front sub-surface and the rear sub-surface and positioned opposite to the left sub-surface; the body portion is elongated along an axis of elongation extending through a center of the body portion; The elongation axis (A E ) defines a forward direction (D) from the second cutting portion toward the first cutting portion F ) and a backward direction opposite to the forward direction (D R ); The cutting insert has a longitudinal axis (A E ) measured insert length (IL); The cutting insert has a longitudinal axis perpendicular to the elongation axis (A E ) measured height (H); The first central axis (A C1 ) is defined as being perpendicular to the elongated axis and extending through the center of the cut-off insert and through the base surface and the rake surface, the first central axis (A C1 ) defines an upward direction (D) from the base surface toward the rake surface U ) and a downward direction opposite to the upward direction (D D ); The second central axis (A C2 ) is defined as perpendicular to the elongation axis (A E ) and the first central axis (A C1 ) and extending through the center of the cutting insert, the second center axis (A C2 ) defines a first lateral direction (D S2 ) and the first lateral direction (D S1 ) in the opposite second lateral direction (D S2 ); The first cutting portion comprises: a first sub-rake surface at the rake surface; a first front sub-flank surface at the front sub-surface; a first left sub-relief surface at the left sub-surface; a first right sub-relief surface at the right sub-surface; a first cutting edge formed at an intersection of the first front sub-relief surface and each of the first front sub-relief surface, the first left sub-relief surface, and the first right sub-relief surface; The first cutting edge comprises: a first forward-most cutting sub-edge, the first forward-most cutting sub-edge extending along the intersection of the first rake sub-edge surface and the first rake sub-edge surface; a first left sub-edge, the first left sub-edge extending along the intersection of the first left front sub-edge surface and the first left rear sub-edge surface; a first right sub-blade, the first right sub-blade extending along the intersection of the first front sub-blade surface and the first right rear sub-blade surface; a first left corner formed at an intersection of the first forwardmost cutting sub-edge and the first left sub-edge; and a first right corner formed at an intersection of the first frontmost cutting sub-edge and the first right sub-edge; The second cutting portion comprises: a second sub-rake surface at the rake surface; a second front sub-flank surface at the rear sub-surface; a second left sub-relief surface at the right sub-surface; a second right sub-flank surface at the left sub-surface; a second cutting edge formed at an intersection of the second front sub-relief surface and each of the second front sub-relief surface, the second left sub-relief surface, and the second right sub-relief surface; The second cutting edge comprises: a second forward-most cutting sub-edge, the second forward-most cutting sub-edge extending along the intersection of the second rake sub-edge surface and the second rake sub-edge surface; a second left sub-edge, the second left sub-edge extending along an intersection of the second left sub-front blade surface and the second left sub-rear blade surface; a second right sub-edge, the second right sub-edge extending along an intersection of the second right sub-front blade surface and the second right sub-rear blade surface; a second left corner formed at an intersection of the second forwardmost cutting sub-edge and the second left sub-edge; and a second right corner formed at an intersection of the second frontmost cutting sub-edge and the second right side sub-edge; Transverse axis (A L ) extends through the forwardmost portion of the first cutting edge, the transverse axis (A L ) is parallel to the second central axis (A C2 ) extends and defines a first lateral direction (DS1) and a first lateral direction (DS2) and a first lateral direction (DS3) S1 ) in the opposite second lateral direction (D S2 ); The first cutting edge has a first kerf width (CW1) that can be parallel to the transverse axis and measured from the first left corner to the first right corner; The second cutting edge has a second kerf width (CW2) that can be parallel to the transverse axis and measured from the second left corner to the second right corner; The elongated body portion has a body width (BW) measurable parallel to the transverse axis and a body length (BL) measurable parallel to the elongation axis; wherein: The body width (BW): smaller than both the first kerf width (CW1) and the second kerf width (CW2); and Meet the following conditions: 0.55mm≤BW≤0.95mm; and The body length (BL): Meet the following conditions: 2mm≤BL≤14mm.

2. The cutting insert according to claim 1, wherein: The body width (BW) satisfies the following condition: 0.65 mm ≤ BW ≤ 0.95 mm.

3. The cutting insert according to claim 2, wherein: The body width (BW) satisfies the following condition: 0.75 mm ≤ BW ≤ 0.95 mm.

4. The cutting insert according to claim 1, wherein: The body width (BW) satisfies the following condition: 0.55 mm ≤ BW ≤ 0.85 mm.

5. The cutting insert according to claim 1, wherein: The body length (BL) satisfies the following condition: 6mm≤BL≤14mm.

6. The cutting insert according to claim 5, wherein: The body length (BL) satisfies the following condition: 8mm≤BL≤14mm.

7. The cutting insert according to claim 1, wherein: The body length (BL) satisfies the following condition: 2mm≤BL≤12mm.

8. The cutting insert according to claim 7, wherein: The body length (BL) satisfies the following condition: 6mm≤BL≤11mm.

9. The cutting insert according to any one of claims 1 to 8, wherein The first kerf width (CW1) and the second kerf width (CW2) satisfy the following conditions: 0.75 mm ≤ CW1, CW2 ≤ 1.1 mm.

10. The cutting insert according to claim 9, wherein: The first kerf width (CW1) and the second kerf width (CW2) satisfy the following conditions: 0.76 mm ≤ CW1, CW2 ≤ 0.84 mm.

11. The cutting insert according to claim 9, wherein: The first kerf width (CW1) and the second kerf width (CW2) satisfy the following conditions: 0.9 mm ≤ CW1, CW2 ≤ 1.1 mm.

12. The cutting insert according to claim 11, wherein The first kerf width (CW1) and the second kerf width (CW2) satisfy the following conditions: 0.96 mm ≤ CW1, CW2 ≤ 1.04 mm.

13. A cutting insert according to any one of claims 1 to 12, wherein: The cutting insert has a first working length (OL1) which can be parallel to the elongation axis (A E ) measured from the frontmost point of the first cutting edge to the intersection of the main body portion and the second cutting portion, meets the following conditions: 5mm≤OL1≤15mm.

14. The cutting insert according to claim 13, wherein: The first working length (OL1) satisfies the following condition: 9mm≤OL1≤13.5mm.

15. The cutting insert according to claim 14, wherein The first working length (OL1) satisfies the following condition: 11 mm≤OL1≤12.5 mm.

16. A cutting insert according to any one of claims 1 to 15, wherein The cut-off insert has no ground surface.

17. A cutting insert according to any one of claims 1 to 16, wherein The height (H) of the main body portion satisfies the condition of 3.5 mm ≤ H ≤ 4.5 mm.

18. A cutting insert according to any one of claims 1 to 17, wherein The first cutting portion also includes a first cutting portion length (L C1 ), the first cutting portion length (L C1 ) can be parallel to the elongation axis A E Measure and meet 1.25mm≤L C1 Condition of ≤1.5mm.

19. A cutting insert according to any one of claims 1 to 18, wherein The first insert ratio (R1) is defined as a ratio of the cut depth (DC) to the first cutting width (CW1) (R1=DC / CW1), and satisfies the following condition: 6≤R1≤16.

20. A cutting insert according to any one of claims 1 to 19, wherein The second insert ratio (R2) is defined as a ratio of the insert length (IL) to the insert height (H) (R2=IL / H), and satisfies the following condition: 1≤R2≤4.5.

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