Cutting insert and toolholder for holding the same

A cutting insert for metalworking operations has an insert core with a pair of cutting portions having cutting tips extending therefrom such that a toolholder having a pocket to accept such a core is suitable to accept different cutting inserts having a common core plus different cutting portions. As a result, for example, an 80° diamond, a 55° diamond and a 35° diamond cutting insert may all be utilized within a common toolholder. The invention is also directed to a toolholder that will accept such a variety of cutting inserts.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to tooling for metalworking operations and, more particularly, directed to cutting inserts and the toolholder for holding such inserts during metalworking operations, such as turning.

2. Description of Related Art

In turning operations, one of the primary criteria for selecting an appropriate insert is the required nose angle. The nose angle is defined at the cutting point in a cutting portion of the insert made up of two straight lines meeting at that point. There are turning inserts referred to as 80° diamonds, 55° diamonds and 35° diamonds, whereby these numerical values define the angle the two sides form with the cutting point. Typically, these inserts are symmetric with two opposing cutting regions. These inserts may also be indexable.

In the past, each cutting insert having a different nose angle would require a dedicated toolholder having a pocket conforming to the shape of the unengaged cutting portion of that insert, thereby requiring a toolholder for every different insert shape.

U.S. Pat. No. 6,152,658 is directed to a modular cutting tool assembly whereby, as illustrated in FIG. 2, a plurality of different inserts may be accepted by the pocket of a single toolholder. However, the pocket of this toolholder is suitable to accept a variety of different inserts only because the pocket has been formed to accommodate each of the different shapes of these inserts. As a result, any one insert may not be supported optimally because portions of the toolholder pocket have been recessed and carved out to accommodate cutting inserts of other shapes.

Therefore, one object of the present invention is to provide a cutting insert having a standardized core with a desired cutting portion such that a variety of other cutting inserts having the same standardized core, but different cutting portions, may be utilized in a common toolholder, thereby minimizing the need to maintain in inventory a large number of different toolholders.

A further object is to provide a single toolholder that will accept these differently shaped inserts.

Additionally, during some metalworking operations, space is limited and the tip-to-tip length of a particular standard cutting insert used for tuning operations may be excessive. In particular, for small cutting tools, such as those cutting inserts having an IC (inscribed circle) of ¼ inch or less, space is limited and it is desired, if possible, to reduce the tip-to-tip length between cutting inserts while, at the same time, maintaining the strength and integrity of those inserts.

SUMMARY OF THE INVENTION

A cutting insert for metalworking operations is comprised of an insert body having a top surface and a bottom surface defining sides therebetween and a core having two pairs of core sides. Top edges are defined at the intersection of the top surface with the sides, and bottom edges are defined at the intersection of the bottom surface with the sides. Each pair of core sides has a first core side and a second core side, wherein the top edges of these core sides form a core angle with one another. When viewed in plan, the top edge of the first core side of one pair is parallel to the top edge of the first core side of the other pair and the top edge of the second core side of one pair is parallel to the top edge of the second core side of the other pair. A first cutting portion and a second cutting portion extend from the core. Each cutting portion is comprised of a pair of sides having top edges which converge at a tip angle to form a cutting tip and a bisector line bisecting the tip angle. When viewed in plan, the bisector line of the first cutting portion is offset from and parallel to the bisector line of the second cutting portion and the tip angle is less than the core angle.

Additionally, a toolholder for supporting a cutting insert has a core with four sides defining a quadrilateral shape and having diametrically opposing corners with a pair of cutting portions having cutting tips extending from two diametrically opposing corners. The toolholder is comprised of a body having a front end and a pocket with a floor and walls positioned rearwardly from the front end of the body, wherein the pocket has a core region adapted to conform to and provide support to the insert core. Two walls in the core region are adapted to conform to and provide support to two sides of the insert core and the floor in the core region is adapted to conform to and provide support to the insert core. The pocket further includes a recess extending rearwardly from the core region and of sufficient area to encompass one cutting tip of the insert when the insert is mounted within the pocket. The core region of the pocket terminates at the front end of the body such that when the insert is positioned within the pocket, one cutting tip extends beyond the front end of the toolholder while the other cutting tip is encompassed by the pocket recess.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates a perspective view of a cutting insert10mounted within a toolholder100in accordance with the subject invention.FIG. 2illustrates an exploded view of these same elements andFIGS. 1 and 2will be discussed simultaneously.

The unique shape of the cutting insert10makes possible the introduction into a common toolholder of mounting one of a plurality of similar cutting inserts which, as will be seen, have a common core, but different cutting portions.

The cutting insert10is further illustrated inFIGS. 3A and 3B. The cutting insert10may be utilized for metalworking operations and has an insert body12with a top surface14and a bottom surface16defining sides18a–18ftherebetween, comprised of tip sides and core sides.

Top edges20a–20fare defined at the intersection of the top surface14with the sides18a–18f. Bottom edges are defined at the intersection of the bottom surface16with the sides18a–18f. Bottom edges21aand21dare shown inFIG. 3B.

The insert core22is made up of two pairs A, B of core sides, wherein one pair A is defined by the intersection of a first core side18aand an extension of the second core side18cand another pair B has a first core side18dand a second core side18f. The top edges20a,20cand20d,20fof each pair A, B of core sides18a,18cand18d,18fform core angles, as illustrated by angles W and X inFIG. 3A.

When viewed in plan, which is looking at the insert directly down upon the top surface14, the top edge20aof the first core side18aof one pair A is parallel to the top edge20dof the first core side18dof the other pair B. Furthermore, when viewed in plan, the top edge20cof the second core side18cof one pair A is parallel to the top edge20fof the second core side18fof the other pair B.

The cutting insert10has a first cutting portion24and a second cutting portion26each extending from the core22.

Cutting portion24is comprised of a pair of sides18a,18bconverging at a first tip angle Y to form a cutting tip28. A bisector line30bisects the tip angle Y. The second cutting portion26has a pair of sides18d,18ewhose top edges20d,20econverge at a second tip angle Z to form a cutting tip34. A bisector line36bisects the second tip angle Z. The bisector line30of the first cutting portion24is offset by a distance d from and parallel to the bisector line36of the second cutting portion26. Furthermore, each of the tip angles Y, Z is less than the respective core angles X, W adjacent to these tips28,34.

As illustrated inFIG. 3A, one side of the cutting tip28is common with the second core side18a. Furthermore, as illustrated inFIG. 3A, the first tip angle Y is equal to the second tip angle Z. However, it should be noted that such a relationship is not necessary and it is entirely possible to have a first cutting portion24and a second cutting portion26, each having different tip angles of between 5° and 85°. It should be noted that the cutting insert10, illustrated inFIGS. 1–3, has a tip angle of 35°.

From inspection of the insert10, illustrated inFIG. 2, it should be apparent that the cutting tip34of the insert10may be positioned to extend beyond the toolholder100for machining or the insert10may be indexed such that cutting tip34may be recessed within the toolholder100.

As illustrated inFIGS. 1 and 2, the cutting insert10has a bore40extending between the ton surface14and the bottom surface16to accept a retention pin42for retaining the insert10within a pocket102of the toolholder100. The retention pin42may have threads43to interlock with mating threads45of a bore47within the toolholder pocket102. In the alternative, although not illustrated in the figures, it is easily envisioned by one skilled in the art to provide the top surface14and bottom surface16of the body12with surfaces to accept a clamp for holding the insert10within the pocket102of the toolholder100.

Throughout the remainder of this discussion, similar elements of the insert10illustrated inFIGS. 3A–3Bare identified by the same reference numbers, but incremented by multiples of 100, i.e., insert10indicated as insert110.

Directing attention toFIG. 4A, a cutting insert110, typically referred to as a 55° diamond, has a core22. The insert110has many features identical to that of cutting insert10illustrated inFIG. 3A. However, cutting insert110has a first cutting portion124comprised of a pair of sides118a,118bhaving top edges120a,120bthat converge at a tip angle Y1to form a cutting tip128. A bisector line130bisects the tip angle Y1. A second cutting portion126is comprised of a pair of sides118d,118ehaving top edges120d,120ethat converge at a tip angle Z1to form a cutting tip134. A bisector line136bisects the tip angle Z1. In a plan view, the bisector line130of the first cutting portion124is offset by an amount d1from and parallel to the bisector line136of the second cutting portion126. Furthermore, each tip angle Y1, Z1is less than the respective core angle X, W.

Directing attention toFIG. 5, a cutting insert210typically referred to as an 80° diamond, is illustrated. The insert210has a top surface214and a bottom surface216.

This is a standard insert design, however, it should be noted that the core22associated with insert10and110has the general profile of the 80° diamond cutting insert210illustrated inFIG. 5. It is this profile of the 80° diamond cutting insert210which defines the shape of the core22for cutting insert10and cutting insert110. The cutting insert210has four sides218a,218c,218dand218fwith the top edges220a,220c,220dand220fdefining core angles X and W. These core angles X and W are identical to the core angles associated with cutting inserts10and110previously defined. This is significant because it permits a toolholder having a pocket suitable to accept the 80° diamond cutting insert210, with minor modifications, to also accept, among others, the 35° diamond insert10, illustrated inFIG. 3Aand the 55° diamond cutting insert110illustrated inFIG. 4A.

The possibilities of a single toolholder100(FIG. 1) accepting a plurality of different cutting inserts having the same core22is illustrated in the exploded view ofFIG. 6. The unique combination of the common core22with each of these inserts coupled with the unique features of the toolholder100will now be described to highlight the use of a single toolholder to accommodate a variety of different inserts each sharing a common core shape.

Directing attention toFIG. 2, a toolholder100is illustrated for supporting the cutting insert10having a core22with four sides18a,18c,18d,18ehaving a top edges20a,20c,20dand20edefining a quadrilateral shape. The core22has diametrically opposed corners44,46with a pair of cutting portions24,26having cutting tips28,34extending from the two diametrically opposing corners44,46.

The toolholder100has a body104with a front end106and a pocket102. The pocket102has a floor108and walls112a,112b,112c, positioned rearwardly from the front end106of the body104. The pocket102has a core region113which conforms with and provides support to the insert core22. A shim300, also shown inFIG. 1, provides support to the cutting insert10. A shim300having a different thickness, may position the cutting insert10higher or lower in the pocket102. The shim300inFIG. 2is partially cut away to illustrate a shim bore302.

Two walls112a,112cof the core region113are adapted to conform and provide support to two sides18a,18cof the core22of the cutting insert10. The floor of pocket108in the core region113is adapted to conform to and provide support to the insert core22whether such support is provided through the shim300on the floor108or through the cutting insert10resting directly upon the floor108.

The pocket102further includes a recess114extending rearwardly from the core region113. The recess114is of a sufficient area to encompass one cutting tip28, for example, of the insert10when the insert10is mounted within the pocket102. With cutting tip34extending from the toolholder100. The recess114is generally intended to provide an area in which the unengaged cutting tip may rest and be afforded protection from the operating environment.

The core region113of the pocket102terminates at the front end106of the body104such tat when the insert10is positioned within the pocket102, one cutting tip34extends beyond the floor of pocket108of the toolholder100, while the other cutting tip28is encompassed by the pocket recess114. The bore47of the pocket102may include threads45extending therein to accommodate threads43on retention pin42to secure the cutting insert10within the pocket102.

The pocket recess114is of sufficient area to accommodate inserts having a tip angle less than 80° but greater or equal to 35°. In general, the pocket102is sized to fully support the largest insert for which the toolholder100is intended.

It is possible to provide a shim300and to conform the shape of the shim300to resemble the shape of the insert10it supports, thereby providing additional support to the tip34of the insert10that extends past the front end106of the toolholder100. The appearance and details of such a shim would be known to those skilled in the art of cutting tool design. Additionally, it may be possible to remove the shim300entirely so that the insert10rests directly in the pocket102. As an example,FIGS. 7A, B and C illustrate the toolholder100supporting a cutting insert10, which is a 35° diamond insert. The cutting tip34of the insert10, when mounted within the pocket102of the toolholder100, is unsupported. Under certain circumstances, where the load upon the cutting insert10is low, such a configuration may be entirely acceptable. However, in the event it is desired to provide additional support to what essentially is a cantilevered cutting insert10, it may be desirable to introduce the shim300within the pocket102of the toolholder100, thereby providing additional support to the cutting tip34of the insert10. It should be appreciated that while the shim300illustrated inFIG. 7extends only partially beyond the front end106of the toolholder100, it is entirely possible to include a shim48which extends further beyond the front end106of the toolholder100, thereby providing additional support to the cutting tip34of cutting insert10. In the alternative, when the cutting insert10will be subjected only to light loads, it may be entirely possible to position the insert10within the pocket102of the toolholder100without a shim or without any additional support beyond that already provided by the toolholder100.

While the toolholder herein discussed may be used for any of a variety of applications, the toolholders illustrated, for example, inFIGS. 1 and 8may have a back end125suitable for use with quick change tooling. In the alternative, it is entirely possible for the toolholder100to have a standard shank that is manually mounted within the toolholder100of a typical machine tool.

While the discussion so far has been directed to the cutting inserts10,110,210having a common core22which permits them to be mounted within a common toolholder100, there is an additional benefit provided by the inserts in accordance with the subject invention. By introducing a core22having a core angle which is greater than the tip angle of the respective inserts, the tip-to-tip length of a standard cutting insert having only four sides defined by the pair of sides associated with each cutting tip may be reduced. In particular, and directing attention again toFIG. 3A, the introduction of the core22and the offset bisector lines30,36, reduces the overall tip-to-tip length of this 35° diamond cutting insert10by approximately 28 percent from the tip-to-tip length of a conventional 35° diamond insert having the same IC. In certain machining environments, and especially those in which space is at a premium, this reduction in tip-to-tip length provides more versatility to the machine operator and permits machining in areas that may be inaccessible to the full tip-to-tip length of the standard insert. This furthermore permits the use of a toolholder having a smaller pocket thereby allowing the toolholder to be smaller.

Directing attention toFIG. 8, it is possible to reduce this tip-to-tip length even further. In particular, the cutting insert310is similar to cutting insert10previously discussed, however, an indentation315is now introduced such that the top edge320aof the side318aof the first cutting portion324intersects with the core22at a point P1recessed from a point P2defined by the intersection of an extension330of the top edge320cof the insert side318cwith the cutting portion324. By doing so, the core22is still in tact, however, the tip-to-tip length between first cutting tip328and second cutting tip334of the insert310is still further reduced from even the tip-to-tip reduction illustrated in the 35° diamond insert ofFIG. 3A.

It should be appreciated that the cutting inserts discussed so far have had flat top surfaces with a planar topography. The subject invention is directed to cutting inserts having both a planar topography and a non-planar topography. Directing attention toFIGS. 9,10A and10B, a cutting insert410has an insert body412with a top surface414and a bottom surface416defining sides418a–418ftherebetween.

Top edges420a–420fare defined at the intersection of the top surface414with the sides418a–418f. Bottom edges are defined at the intersection of the bottom surface416with the sides418a–418f. Bottom edges421aand421dare shown inFIG. 10B.

The insert core422is made up of two pairs A, B of core sides, wherein one pair A is defined by the intersection of a first core side418aand an extension of the second core side418cand another pair B has a first core side418dand a second core side418f. The top edges420a,420cand420d,420fof each pair A, B of core sides418a,418c,418dand418fform core angles, as illustrated by angles W and X inFIG. 10A.

When viewed in plan, which is looking at the insert410directly down upon the top surface414, the top edge420aof the first core side418aof one pair A of core sides is parallel to the top edge420dof the first core side418dof the other pair B of core sides. Furthermore, when viewed in plan, the top edge420cof the second core side418cof one pair A of core sides is parallel to the top edge420fof the second core side418fof the other pair B of core sides.

The cutting insert410has a first cutting portion424and a second cutting portion426each extending from the core422.

Cutting portion424is comprised of a pair of sides418a,418bconverging at a first tip angle Y to form a cutting tip428. A bisector line430bisects the tip angle Y. The second cutting portion426has a pair of sides418d,418ewhose top edges420d,420econverge at a second tip angle Z to form a cutting tip434. A bisector line436bisects the second tip angle Z. When viewed in plan, the bisector line430of the first cutting portion424is offset by a distance d from and parallel to the bisector line436of the second cutting portion426. Furthermore, each of the tip angles Y, Z is less than the respective core angles X, W adjacent to these tips428,434.

As illustrated inFIG. 10A, one side of the cutting tip428is common with the second core side418a. Furthermore, as illustrated inFIG. 10A, the first tip angle Y is equal to the second tip angle Z. However, it should be noted that such a relationship is not necessary and it is entirely possible to have a first cutting portion424and a second cutting portion426, each having different tip angles of between 5° and 85°. It should be noted that the cutting insert410, illustrated inFIGS. 9 and 10Ahas a tip angle of 55°. Additionally, insert410has a bore440extending therethrough to accept a retention pin or screw for mounting the insert410within the pocket of a toolholder.

Finally, it should be appreciated that inserts in accordance with the subject invention may also be invertible and that the discussion directed to the cutting edges at the intersection of the top surface and sides, along with their geometric relationship, would be applicable to cutting edges formed at the intersection of the bottom surface and the sides.

The documents, patents and patent applications referred to herein are hereby incorporated by reference.