Tool holder having a tool body and top clamp for retaining a cutting insert

A cutting tool includes a cutting insert releasably retained therein. The cutting insert has top and bottom surfaces and a peripheral surface extending therebetween. The cutting insert does not include any clamping bore for receiving a clamping component therein. The cutting insert may having unitary, one-piece construction and be formed of a superabrasive material. The cutting insert may have a two-headed arrow shape, or similar shapes, such that the body of the cutting insert is small relative to the cutting regions thereof. The cutting tool includes a top clamp for clamping the cutting insert in an insert pocket. The top clamp has an asymmetrical shape and engages the cutting insert in one engagement region on the top surface, and in one engagement region on the peripheral surface. The cutting insert engages the insert pocket at the bottom surface, and in three spaced apart engagement regions on the peripheral surface.

FIELD OF THE INVENTION

The present invention relates to a cutting insert for performing metal cutting operations, and to a cutting tool therefor.

BACKGROUND OF THE INVENTION

Some metal cutting operations are performed using a cutting insert which has at least a cutting edge that is coated with, or made of, a superhard material, for example, a superabrasive material, e.g., Polycrystalline Diamond (PCD) or Cubic Boron Nitride (CBN). This kind of cutting insert may be used, for example, for machining very hard metals, superalloys, or the like, while providing the machined work-piece with appropriate surface quality, and/or obtaining other desired results.

In some instances, due to the high cost of superhard materials such as superabrasives, the cutting insert is assembled, for example, from two separate components: a cutting insert body and a cutting tip. The cutting insert body is formed, for example, of a material used for manufacturing ordinary cutting inserts, for example, cemented carbide such as Tungsten carbide, and the cutting tip, which is significantly smaller in size than the cutting insert body, is formed of a superabrasive material such as PCD or CBN. A pocket is formed in an end of the cutting insert body and the cutting tip is brazed to the pocket, or positioned therein using other methods.

However, the above-described manufacture of a cutting insert may be prolonged and expensive. Also, the assembling of a cutting insert from two separate components may result in manufacture imprecisions that reduce the cutting quality of the cutting insert. In addition, the cutting tip may undesirably become detached or torn from the cutting insert body, either partially or entirely, for example, due to extensive use of the cutting insert and/or due to a poor assembling thereof.

SUMMARY OF THE INVENTION

In some embodiments of the invention, a cutting tool includes a cutting tool holder and a cutting insert. The cutting tool holder has a cutting tool body and a cutting insert clamp, henceforth referred to as a “top clamp”, attached thereto using a securing member received in a through-bore formed in a central portion of the top clamp. The cutting tool body has an insert pocket formed at a front end thereof, having the cutting insert releasably retained therein. The top clamp secures the cutting insert in the insert pocket, for example, when the securing member is fastened.

In some embodiments, the cutting insert includes only imperforated surfaces, i.e., in some embodiments the cutting insert does not include any clamping bore for receiving therein clamping components such as a screw, a pin or a lever to clamp the cutting insert in the insert pocket. The cutting insert may have unitary, one-piece construction and be made of superhard material, for example, superabrasive material such as Cubic Boron Nitride (CBN) or Polycrystalline Diamond (PCD). The cutting insert may be machined out of a planar disc of superabrasive material, e.g., using electro-discharge machining methods.

In some embodiments, the cutting insert is an indexable, double-sided, double-ended cutting insert having a longitudinal axis defining an end-to-end direction of the cutting insert. The cutting insert may have a general shape of a double-headed arrow, e.g., as seen from a top view, and include two identical, opposing top and bottom surfaces, and a peripheral surface extending therebetween. The peripheral surface includes two central surfaces and four intermediate surfaces. Rake surfaces are formed at opposite cutting ends of both the top and bottom surfaces.

The cutting insert is mirror-symmetrical with respect to a first median plane thereof, the first median plane containing the longitudinal axis and extending through the top and bottom surfaces. The two central surfaces are located mirror-symmetrically with respect to the first median plane, and each intermediate surface extends from a respective end of the respective central surface, in a direction away from the first median plane. The central surfaces and the intermediate surfaces are generally perpendicular to the top and bottom surfaces.

In some embodiments, the cutting insert has a second median plane, the second median plane being perpendicular to the first median plane and extending through the top and bottom surfaces and also the two central surfaces. In these embodiments, the cutting insert is mirror-symmetrical also with respect to the second median plane.

In some embodiments, the peripheral surface additionally includes four end surfaces, e.g., four substantially planar end surfaces, each end surface extending from a respective intermediate surface in the direction of the first median plane, and forming respective cutting corners thereat. In other embodiments, the peripheral surface may alternatively include two end surfaces, e.g., two curved end surfaces, located mirror-symmetrically with respect to the second median plane, extending between two respective intermediate surfaces on the same side of the second median plane. In yet other embodiments, the peripheral surface may include other end surfaces, e.g., based on specific design and/or cutting requirements of the cutting insert.

In some embodiments, the top clamp may have a generally triangular shape, e.g., as seen from a top view. The top clamp includes a bottom surface, facing an upper surface of the cutting tool body. In some embodiments, the top clamp has a generally asymmetrical shape. A single sliding surface of the top clamp inclinedly protrudes down from a first rear corner of the top clamp, slidingly engaging a complementary shaped sloping surface of the cutting tool body. Thus, as the securing member is fastened, the sliding surface slides against the sloping surface in a direction away from the first median plane, downward and rearward.

In some embodiments, the top clamp includes two engagement surfaces, to respectively engage the cutting insert, e.g., exclusively, in two engagement regions. The top clamp includes, for example, a top engagement surface, formed at a front portion of the top clamp's bottom surface, to engage the cutting insert top surface in a top engagement region formed thereon. The top clamp additionally includes an insert-side engagement surface, extending generally perpendicularly downward from the front portion of the top clamp's bottom surface, to engage one of the intermediate surfaces in a side engagement region on the peripheral surface of the cutting insert.

In some embodiments, a supporting boss may project downward from a second rear corner of the top clamp's bottom surface, to solidly engage the upper surface of the tool body, e.g., when the securing member is fastened. The engagement between the supporting boss and the upper surface directs clamping forces applied by the top clamp toward the cutting insert, resulting in increased, solid securing of the cutting insert in the insert pocket. In a fastened position, the top clamp may exclusively engage the cutting tool body through the sliding surface and the supporting boss.

In addition, in a fastened position the cutting insert engages the insert pocket in three spaced apart engagement regions of three respective intermediate surfaces, to provide solid engagement between the cutting insert and the insert pocket, e.g., without over-constraining the position of the cutting insert in the insert pocket.

In some embodiments, an imaginary plane extends through the top clamp, passes through the top engagement surface and includes a central axis of the through-bore. Due to the asymmetric structure of the top clamp, the single sliding surface is entirely positioned on one side of the imaginary plane, and the supporting boss and the insert-side engagement surface are positioned entirely on the opposite side thereof.

In some embodiments, the geometry of the cutting insert beneficially results in that the body of the cutting insert is relatively small in volume with respect to the cutting regions or cutting tips of the cutting insert. Thus, a cutting insert according to the present invention can be formed, for example, to have unitary one-piece construction and made of superhard material, wherein material is not “wasted” on formation of the body of the cutting insert, e.g., which is not directly involved in the cutting operation. Therefore, the cutting insert is both relatively inexpensive to manufacture, and provided with desired cutting abilities, for example, for adequately performing extensive cutting operations such as cutting of hard metals or superalloys. In addition, the present invention provides an improved securing means for securing the cutting insert of the present invention in a cutting tool holder.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity, or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE INVENTION

Although some drawings herein show a turning tool, the present invention is not limited in this respect. For example, embodiments of the invention may refer to other cutting tools, e.g., to milling tools or to other metal cutting tools having one or more cutting inserts releasably retained therein.

Reference is made toFIGS. 1-13, showing a cutting tool10, and a plurality of portions, components and sections thereof, in accordance with a plurality of embodiments of the invention.

In some embodiments, the cutting tool10includes a cutting tool holder12, having a cutting tool body14and a cutting insert clamp16, henceforth referred to as “top clamp16”. The top clamp16is attached to the cutting tool body14using a securing member18, for example, a screw having two opposite threads at respective ends thereof, e.g., as shown inFIG. 2, or other appropriate securing means. The cutting tool10has a front end19and a rear end21. The cutting tool body14includes an insert pocket20formed at the front end19, the insert pocket20having a cutting insert22releasably retained therein. The top clamp16secures the cutting insert22in the insert pocket20, e.g., as described in detail below.

In some embodiments, e.g., as shown inFIG. 6, the cutting insert22is an indexable, double-sided double-ended cutting insert having a longitudinal axis L defining an end-to-end direction of the cutting insert. The cutting insert22has identical top and bottom surfaces,24′,24″, respectively. Each top and bottom surface comprises at least two spaced apart rake surfaces25formed at opposite cutting ends31of the insert22. The cutting insert22additionally includes a peripheral surface26extending between the top and bottom surfaces24′,24″. The top and bottom surfaces24′,24″ and the peripheral surface26are imperforated, i.e., the cutting insert22does not include any clamping bore for receiving therein a clamping component such as a screw, pin or lever, and thus is devoid of any such clamping bores.

In some embodiments, the cutting insert22has unitary, one-piece construction and is formed of superhard material, for example, a superabrasive material such as Cubic Boron Nitride (CBN) or Polycrystalline Diamond (PCD). The cutting insert22may be cut, or machined, out of a larger planar disc of superabrasive material, e.g., using electro-discharge machining methods or other methods.

The cutting insert22may have four cutting corners28, e.g., one cutting corner28associated with each rake surface25, respectively. Thus, the cutting insert22is 180 degrees indexable about a first axis T1, and 180 degrees indexable about a second axis T2, e.g., as shown inFIG. 6. The rake surfaces25may include one or more grooves30formed thereon, e.g., as shown inFIG. 7, each groove30associated with a respective cutting corner28. The grooves30may function as chip formers for regulating chip flow during a cutting operation.

In some embodiments, the cutting insert22is mirror-symmetrical with respect to a first median plane M1thereof, the first median plane M1extending longitudinally through the cutting insert22, containing the longitudinal axis L, extending through the top and bottom surfaces24′,24″ and passing through the cutting corners28. In some embodiments, the cutting insert22includes a second median plane M2that extends through the top and bottom surfaces24′,24″ and perpendicularly to the first median plane M1and includes the first and second axes T1and T2. In these embodiments, the cutting insert22is in addition mirror-symmetrical with respect to the second median plane M2, e.g., as shown inFIGS. 8-12.

In some embodiments, the peripheral surface26includes two central surfaces32, located mirror-symmetrically with respect to the first median plane M1and halved, for example, by the second median plane M2, which extends through the two central surfaces in addition to the top and bottom surfaces. The central surfaces32may either be planar, and thus parallel to each other, or assume other, appropriate shapes. The peripheral surface26additionally includes four intermediate surfaces34, wherein each intermediate surface34extends from a respective end of the respective central surface32in a direction away from the first median plane M1. In some embodiments, the intermediate surfaces34extend from the respective central surfaces32away also from the second median plane M2, e.g., as shown inFIGS. 8-10and inFIG. 12. In other embodiments, the intermediate surfaces34extend from the respective central surfaces32toward the second median plane M2, e.g., as shown inFIG. 11. The central surfaces32and the intermediate surfaces34may be generally perpendicular to the top and bottom surfaces24′,24″.

In some embodiments, the peripheral surface26additionally includes four end surfaces36, the end surfaces36extending from respective intermediate surfaces34toward the first median plane M1, forming respective cutting corners28thereat. In other embodiments, the peripheral surface26may alternatively include two end surfaces, e.g., two curved end surfaces36, located on opposite sides of the cutting insert22with respect to the second median plane M2, and extending between two respective intermediate surfaces34, e.g. as shown inFIG. 9. In yet other embodiments, the peripheral surface26may include other end surfaces.

In some embodiments, the top clamp16has a generally triangular shape, e.g., as seen from a top view. The top clamp16includes a bottom surface38, which may be planar, facing an upper surface40of the cutting tool body14. The top clamp16has a generally asymmetrical structure, such that in a secured position, for example, the top clamp16exclusively engages the cutting insert22in two engagement regions, as described in detail below.

The top clamp16includes an engagement member41located on the front portion75of the bottom surface38and protruding down therefrom, the engagement member41including a top engagement surface42, for engaging the cutting insert22in a top engagement region44thereof, which is formed on the top surface24′. The top engagement surface42is lower with respect to the bottom surface38, and may be generally planar, e.g., extending generally parallel to the bottom surface38, or assume other appropriate shapes for engaging the cutting insert's top surface24′.

The top clamp16additionally includes an insert-side engagement surface46, also extending generally perpendicularly downward from the front portion75of the bottom surface38, to engage the cutting insert22in a side engagement region48formed on a side intermediate surface34′ of the intermediate surfaces34, e.g., as shown inFIG. 2. The side intermediate surface34′ only engages the insert-side engagement surface46, and does not engage the insert pocket20, e.g., as shown inFIG. 13.

In some embodiments, the insert pocket20and the cutting insert22are at least partially complementarily shaped. The insert pocket20includes three spaced apart pocket walls50formed therein, for engaging the peripheral surface26of the cutting insert22. In a secured position, for example, three pocket intermediate surfaces34″ of the intermediate surfaces34respectively engage the three pocket walls50at three pocket engagement regions52of the three pocket intermediate surfaces34″, e.g., as shown inFIGS. 3,5and13. Thus, in a secured position, the peripheral surface26engages the insert pocket20at three spaced apart pocket engagement regions52, wherein in some embodiments, e.g., due to the geometry of the cutting insert22and insert pocket20, no two of the three pocket engagement regions52are coplanar. This provides solid securing of the cutting insert22in the insert pocket20.

The top, side, and pocket engagement regions,44,48and52, respectively, are shown in some drawings herein to have a generally elliptical shape. This shape has been chosen for illustrative purposes only, and the engagement regions44,48and52are not limited in this respect. For example, illustrations of the engagement regions44,48and52may not refer to any physical structure formed on surfaces of the cutting insert22, and are only be used to indicate the locations of respective regions of engagement between the surfaces associated therewith. In addition, the engagement regions44,48and52on the cutting insert22may each assume any convenient shape, e.g., based on the specific geometries of the respective associated engagement surfaces.

In some embodiments, the bottom surface24″ engages a supporting surface54of insert pocket20. The supporting surface54may include a central recess56that does not engage the bottom surface24″, thereby the bottom surface24″ engages only an outer surface58of the supporting surface54, e.g., in order to avoid over-constrained engagement between the cutting insert22and the insert pocket20.

The top clamp16additionally includes a through-bore60, for example, a threaded through-bore, formed in a generally central portion of the top clamp16, and opening out to the bottom surface38and to a clamp upper surface62of the top clamp16, to receive the securing member18therein. An imaginary plane P which extends through the top clamp passes through the top engagement surface42and includes a central axis A of the through-bore60.

In some embodiments, the top clamp16includes a single sliding surface64, which inclinedly extends from a first rear corner66of the bottom surface38in a direction D, i.e., in a direction away from the imaginary plane P, rearward and downward; the direction D shown, for example, inFIGS. 3,5and13. A sloping surface68of the cutting tool body, shaped complementarily to the sliding surface64, facing the sliding surface64and located substantially underneath thereto, slopes from the upper surface40, in the direction D. Thereby, fastening of the securing member18results in sliding of the sliding surface64against the sloping surface68, in the direction D. The sliding of the sliding surface64in this direction results in fastening of the top clamp16to the cutting insert22through the top and side engagement regions44and48, respectively, and thus in fastening of the cutting insert22to the insert pocket20through the pocket engagement regions52.

In some embodiments, the top clamp16includes a supporting boss70, projecting downward from a second rear corner72of the bottom surface38, to solidly engage the upper surface40of the cutting tool body14. Due to the asymmetric structure of the top clamp16, the single sliding surface64is entirely positioned on one side of the imaginary plane P, and the supporting boss70and insert-side engagement surface46are entirely positioned on the opposite side thereof.

When fastening the securing member18, for example, engagement between the supporting boss70and the upper surface40directs clamping forces, applied by the top clamp16, toward the front portion75of the top clamp's bottom surface38where the top engagement surface42abuts the top engagement region44of the cutting insert22. This is so, for example, since engagement between the supporting boss70and the upper surface40results in the upper surface40exerting an upward normal force on the top clamp16. Due to arrangement of the supporting boss70and the sliding surface64on opposite sides of the imaginary plane P and securing member18, the applied normal force results in the top clamp16increasedly forcing the cutting insert22in the direction D.

In some embodiments, the top clamp16may additionally include a shaft74, e.g., a cylindrical shaft, extending down from the bottom surface38and received into a corresponding bore76formed in the cutting tool body14. The shaft74may protrude downward from the bottom surface38, for example, more considerably than other components extending downward from the bottom surface38. The shaft74guides the top clamp16into position, e.g., in a specific direction and orientation with respect to the cutting tool body14, for example, after indexing or replacing the cutting insert22. The bore76has a larger diameter than diameter of the shaft74. Thereby, in a secured position, the shaft74is not involved in securing of the cutting insert22.