End mill with independent rake surfaces

A cutting tool includes: a body extending along a longitudinal axis between a leading and trailing ends, the body having a clamping region disposed at or about the trailing end and a cutting region which extends toward the clamping region from the leading end of the body; a plurality of flutes defined in the body, each extending from the leading end toward the coupling portion; a plurality of peripheral cutting edges, each extending from the leading end toward the coupling portion along a corresponding flute of the plurality of flutes; and a plurality of end cutting edges disposed at the leading end, each end cutting edge extending from at or near the longitudinal axis outward along a corresponding flute. At least one end cutting edge is defined, in-part, by a plurality of rake faces which each extend from a corresponding portion of the one cutting edge into the corresponding flute.

RELATED APPLICATION DATA

The present application claims priority pursuant to 35 U.S.C. § 119(a) to Israeli Patent Application Number 264757 filed Feb. 10, 2019 which is incorporated herein by reference in its entirety.

FIELD

The disclosed concept relates rotary cutting tools and, more particularly to end mills having a plurality of rake surfaces along a given cutting edge.

BACKGROUND

End mills are commonly used in machining operations performed on a metal workpieces. As with any cutting tools used in machining operations, improvements in such mills are constantly being sought which improve tool life, improve surface finish, reduce cutting forces, and generally increase cutting capabilities of the tool (e.g., for end mills, improve drilling and/or ramping capabilities).

Tool life of an end mill is highly dependent on the ability of the cutting corner(s) to stay intact and functional. In most end mill applications, a cutting corners are under complex stresses derived from chip formation, particular tool path and reduced amount of coolant supply (as compared to other areas of the mill).

SUMMARY

End mills in accordance with embodiments of the disclosed concept improve upon conventional designs in several ways. Examples of such improvements include (without limitation): improved chip formation at the cutter's corner section (could be a radius, a chamfer or a sharp corner, improved tool life under complex stresses as for example in ramp down applications, and improved end mill manufacturing processes.

As one aspect of the disclosed concept a cutting tool comprises: a body of generally cylindrical shape extending along a longitudinal axis between a leading end and an opposite trailing end, the body having a clamping region disposed at or about the trailing end of the body and a cutting region extending toward the clamping region from the leading end of the body; a plurality of flutes defined in the body, each of the flutes extending in the cutting region from the leading end of the body toward the coupling portion; a plurality of peripheral cutting edges, each peripheral cutting edge extending from the leading end toward the coupling portion along a corresponding flute of the plurality of flutes; and a plurality of end cutting edges disposed at the leading end of the body, each end cutting edge extending from at or near the longitudinal axis outward along a corresponding flute of the plurality of flutes, wherein at least one end cutting edge of the plurality of end cutting edges is defined, in-part, by a plurality of rake faces which each extend from a corresponding portion of the one cutting edge into the corresponding flute.

The cutting tool may comprise an end mill.

The plurality of rake faces may comprise a first rake face disposed at a first axial rake angle and a second rake face disposed at a second axial rake angle different than the first axial rake angle.

The first rake face may be disposed closer to the longitudinal axis than the second rake face; and the first axial rake angle may be less than the second axial rake angle.

The portion of the one cutting edge corresponding to the first rake face is disposed at a first radial angle; and wherein the portion of the one cutting edge corresponding to the second rake face is disposed at a second radial angle different than the first radial angle.

The portion of the one cutting edge corresponding to the first rake surface may be closer to the longitudinal axis than the portion of the one cutting edge corresponding to the second rake surface and the first radial angle may be less than the second radial angle.

The one cutting edge may extend from a first end at or about the longitudinal axis to an opposite second end, wherein the portion of the one cutting edge corresponding to the first rake face is disposed at the first end of the one cutting edge, and wherein the first radial angle is neutral or positive.

The portion of the one cutting edge corresponding to the second rake face may be disposed at the second end of the one cutting edge, and the second radial angle may be greater than the first radial angle.

The plurality of rake faces may further comprise a third rake face disposed at a third axial rake angle.

The first rake face may be disposed closer to the longitudinal axis than the second rake face; the second rake face may be disposed closer to the longitudinal axis than the third rake face; the first axial rake angle may be less than the second axial rake angle; and the second axial rake angle may be less than the third axial rake angle.

The portion of the one cutting edge corresponding to the first rake face may be disposed at a first radial angle; the portion of the one cutting edge corresponding to the second rake face may be disposed at a second radial angle different than the first radial angle; and the portion of the one cutting edge corresponding to the third face may be disposed at a third axial rake angle.

The one cutting edge may extend from a first end at or about the longitudinal axis to an opposite second end, wherein the portion of the one cutting edge corresponding to the first rake face is disposed at the first end of the one cutting edge, and the first radial angle may be neutral or positive.

The portion of the one cutting edge corresponding to the third rake face may be disposed at the second end of the one cutting edge; the third radial angle may be greater than the first radial angle; and the second radial angle may be different than both the first and the second radial angles.

At least a second cutting edge of the plurality of cutting edges may be defined, in-part, by a second plurality of rake faces which each extend from a corresponding portion of the second cutting edge into the corresponding flute.

The plurality of cutting edges may comprise at least three cutting edges and at least a third cutting edge of the plurality of cutting edges may be defined, in-part, by a third plurality of rake faces which each extend from a corresponding portion of the third cutting edge into the corresponding flute.

The plurality of rake faces may comprise at least four rake faces.

The at least one cutting edge may be disposed in a plane which is perpendicular to the longitudinal axis.

The plurality of end cutting edges may comprise at least three cutting edges, the one cutting edge may extends from a first end at or about the longitudinal axis to an opposite second end, the portion of the one cutting edge corresponding to the first rake face may be disposed at the first end of the one cutting edge, the first radial angle may be neutral or negative.

It is to be understood that for a given example set forth herein, such example may include at least a portion of the subject matter of one or more of any other examples also set forth herein.

These and other examples are described in greater detail in the detailed description which follows.

DETAILED DESCRIPTION

It is to be understood that certain descriptions of the concepts disclosed herein have been simplified to illustrate only those elements and limitations that are relevant to a clear understanding of the concepts, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art, upon considering the present description, will recognize that other elements and/or limitations may be desirable in order to implement the disclosed concepts. However, because such other elements and/or limitations may be readily ascertained by one of ordinary skill upon considering the present description, and are not necessary for a complete understanding of the disclosed concepts, a discussion of such elements and limitations is not provided herein. For example, as discussed herein, embodiments of the end mills in accordance with the disclosed concepts may be produced in the form of entire solid carbide or a solid carbide head comprising a cutting portion and attached to a steel bar by fusion or other manufacturing mechanical methods. The methods by which the end mills are manufactured are generally understood by those of ordinary skill in the art and, accordingly, are not described in detail herein. In addition, all the geometric shapes should be considered to be modified by the term “substantially” wherein the term “substantially” means that the shape is formed within typical design and manufacturing tolerances for cutting tools.

The concepts described herein can be understood more readily by reference to the following detailed description and examples and their previous and following descriptions. Elements, apparatus and methods described herein, however, are not limited to the specific implementations presented in the detailed description and examples. It should be recognized that these implementations are merely illustrative of the principles of the present disclosure. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the spirit and scope of the present disclosure.

Whenever the term “about” or “approximately” is used herein or in the appended claims to modify the dimensions of a feature of an implementation of the present disclosure, it is to be construed as referring to the parameters related to the relevant feature. Whenever a range is used herein or in the appended claims to describe dimensions, temperatures, times, amounts, or the like relating to a feature of an aspect of the present disclosure, the range is to be construed as including the stated end points of the range and every point therebetween.

As used herein, the term “number” shall be used to refer to any non-zero quantity. As used herein, the term “plurality” shall be used to refer to any quantity greater than one, i.e., two or more.

The illustrated embodiments of the disclosed concept will be best understood by reference to the figures. The following description is intended only by way of example and simply illustrates certain selected exemplary embodiments of the concepts as claimed herein. To facilitate easier reference, in advancing fromFIG. 1Ato and throughFIG. 7, a reference numeral is advanced by a multiple of 100 in indicating a substantially similar or analogous component or element with respect to at least one component or element found in one or more earlier figures amongFIGS. 1A-7.

Referring to first toFIG. 1A, a perspective view of an end mill10in accordance with an example embodiment of the disclosed concept is shown. In the illustrated example ofFIG. 1A, end mill10is a solid carbide end mill, however, it is to be appreciated that end mill10may be in the form of various other types of end mills and related cutting inserts without varying from the scope of the disclosed concept. End mill10includes a body12of generally cylindrical shape which extends along a central longitudinal axis14between a leading end16and a trailing end18which is disposed opposite leading end16. Body10includes a clamping region20disposed at or about trailing end18and a cutting region22which extends from leading end16toward clamping region20. In the illustrated example ofFIG. 1A, clamping region20is generally cylindrical in shape and is structured to be secured (via any suitable mechanism) in a tool chuck (not shown) of a machine tool (e.g., without limitation, a CNC machine) for rotating end mill10about central longitudinal axis14thereof (in a direction such as shown by arrow R). It is to be appreciated that clamping region20may be of any other suitable shape or form without varying from the scope of the disclosed concept.

Continuing to refer toFIG. 1A, end mill10further includes a plurality of flutes24(two are shown in the example) formed/defined in cutting region22, each flute24extending from leading end16of end mill10rearward toward clamping region20, as well as a corresponding plurality of peripheral cutting edges26and end cutting edges28which are generally separated by cutting corners30. More particularly, each peripheral cutting edge26extends from a respective cutting corner30rearward toward clamping region20in a helical manner along a trailing (with respect to rotation R about axis14) portion of, and is defined in-in part by, a respective one of flutes24. Each end cutting edge28extends generally radially outward from a first end (not numbered) that is located generally at or about longitudinal axis14to a respective cutting corner30that is positioned at an outer periphery of leading end16. Peripheral cutting edges26, end cutting edges28, and cutting corners30are designed to cooperate with a workpiece being machined during rotation (in direction R) of end mill10around axis14. It is to be appreciated that although the example end mill10illustrated inFIG. 1Aincludes only two flutes24, and thus only two corresponding: peripheral cutting edges26, end cutting edges28, and cutting corners30, the number of flutes24and corresponding structures26,28,30may be varied without varying from the scope of the disclosed concept.

Continuing to refer toFIG. 1A, each end cutting edge28is defined, in-part, by a plurality of independent rake faces32, each of which extend from a corresponding portion of end cutting edge28into the flute24which corresponds to the particular end cutting edge28. Referring to the detail view ofFIG. 1B, each end cutting edge28of end mill10is defined by three rakes faces32: an inner rake face32A disposed adjacent longitudinal axis14which extends from an inner cutting edge portion28A of end cutting edge28; a central rake face32B disposed adjacent inner rake face32A which extends from a central cutting edge portion28B of end cutting edge28; and an outer rake face32C disposed adjacent central rake face32B opposite inner rake face32A and adjacent cutting corner30that extends from an outer cutting edge portion28C of end cutting edge28. Each of rake faces32are disposed at different axial rake angles. More particularly, inner rake face32A may be disposed generally at a negative, neutral or slightly positive axial rake angle, central rake face32B is disposed at an axial rake angle slightly more positive (i.e., slightly greater) than inner rake face32A, and outer rake face32C is disposed at an axial rake angle greater than that of central rake face32B but less than the helix angle (not labeled) of flutes24. Additionally, as shown inFIG. 1C, each of cutting edge portions28A-28C are disposed at different radial angles. More particularly, inner cutting edge portion28A is disposed at a neutral or slightly positive radial angle; central cutting edge portion28B is disposed at a radial angle which may be similar to, or slightly greater (e.g., up to a degree more, about 2-5 degrees more) than inner cutting edge portion28A; and outer cutting edge portion28C is disposed at a radial angle greater than both inner cutting edge portion28A and central cutting edge portion28B. Depending on the particular application, outer cutting edge portion28C is preferably disposed at a radial angle in the range of from about 2 degrees to 20 degrees. For example, in embodiments employed in aluminum cutting operations, outer cutting edge portions28C disposed at radial angles in the range of 5 to 20 degrees have been employed. As another example, in embodiments employed in steel and titanium cutting operations, outer cutting edge portions28C disposed at radial angles in the range of 2 to 7 degrees have been employed.

Another example end mill210in accordance with the disclosed concept having another arrangement including a cutting edge228having three portions cutting edge portions228A,228B, and228C and corresponding rake faces232A,232B and232C arranged similarly as end mill10ofFIGS. 1A-1Cis illustrated inFIG. 2.

Referring now toFIGS. 3A and 3B, an example end mill310in accordance with another example embodiment of the disclosed concept which includes only two rake faces332A and332C is illustrated. More particularly, end mill310includes an inner rake face332A which extends from an inner cutting edge portion328A of end cutting edge328and an outer rake face332C which extends from an outer cutting edge portion328C of end cutting edge328between inner rake face332A and cutting corner330. Inner rake face332A may be disposed at an axial rake angle which is negative, neutral, or slightly positive, while outer rake face332C is disposed at an axial rake angle which is greater than inner rake face332A but less than the helix angle (not labeled) of flutes324. As can be appreciated fromFIG. 3B, inner cutting edge portion328A may be disposed at a neutral or slightly positive radial angle while outer cutting edge portion328C is disposed at a positive radial angle greater than inner cutting edge portion328A.

Referring now toFIGS. 4A and 4B, an example end mill410in accordance with another example embodiment of the disclosed concept which includes only two rake faces432A and432C is illustrated. More particularly, end mill410includes an inner rake face432A which extends from an inner cutting edge portion428A of end cutting edge428and an outer rake face432C which extends from an outer cutting edge portion428C of end cutting edge428between inner rake face432A and cutting corner430. Inner rake face432A may be disposed at a negative, neutral, or slightly positive axial rake angle while outer rake face432C is disposed at an axial rake angle which is greater than inner rake face432A but less than the helix angle (not labeled) of flutes424. As can be appreciated fromFIG. 4B, inner cutting edge portion428A may be disposed at a neutral or positive radial angle while outer cutting edge portion428C is disposed at a positive radial angle which is greater than inner cutting edge portion428A.

Referring now toFIGS. 5A and 5B, an example end mill510in accordance with another example embodiment of the disclosed concept which includes three cutting edges528is illustrated. In general, the three cutting edge designs utilize the same concepts as the two cutting edge designs with the only difference being that the first, inner, portion has a radial angle which is 0 degrees or negative.

As shown inFIG. 5A, cutting edge528includes two rake faces532. More particularly, end mill510includes an inner rake face532A which extends from an inner cutting edge portion528A of end cutting edge528and an outer rake face532C which extends from an outer cutting edge portion528C of end cutting edge528between inner rake face532A and cutting corner530. Inner rake face532A may be disposed generally at a negative, neutral, or slightly positive axial rake angle while outer rake face532C is disposed at an axial rake angle which is greater than inner rake face532A but less than the helix angle (not labeled) of flutes524. As can be appreciated fromFIG. 5B, inner cutting edge portion528A may be disposed at a slightly negative or neutral radial angle while outer cutting edge portion428C is disposed at a positive radial angle which is greater than inner cutting edge portion528A.

Referring now toFIG. 6, an example end mill610in accordance with another example embodiment of the disclosed concept which includes three cutting edges is illustrated. Cutting edge628includes three rake faces632. More particularly, end mill610includes an inner rake face632A which extends from an inner cutting edge portion628A of end cutting edge628, a central rake face632B which extends from a central cutting edge portion628B, and an outer rake face632C which extends from an outer cutting edge portion628C of end cutting edge628between central rake face632B and cutting corner630. Inner rake face632A may be disposed generally at a negative, neutral, or slightly positive axial rake angle, central rake face632B is disposed at an axial rake angle slightly more positive than inner rake face632A, and outer rake face632C is disposed at an axial rake angle greater than central rake face632B but less than the helix angle (not labeled) of flutes624. Inner cutting edge portion628A may be disposed at a slightly negative or neutral radial angle, central cutting edge portion628B is disposed at a similar or more positive radial angle than inner cutting edge portion628A, and outer cutting edge portion628C is disposed at a radial angle greater than both inner cutting edge portion628A and central cutting edge portion628B.

Yet another example end mill710in accordance with another example embodiment of the disclosed concept which includes three cutting edges arranged similarly as end mill610is illustrated inFIG. 7.

From the foregoing examples it is thus to be appreciated that one or more of: the quantity of cutting edges, the quantity of independent rake faces, the axial rake angles of each of the independent rake faces, and/or the radial angles of the portions of the cutting edges associated with each rake face may be varied without varying from the scope of the disclosed concept.

Various implementations of the present disclosure have been described in fulfillment of the various objectives of the present disclosure. It should be recognized that these implementations are merely illustrative of the principles of the present disclosure. Moreover, although the foregoing descriptions and the associated drawings illustrate examples in the context of certain example combinations of elements and/or functions, numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present disclosure.

The description of the embodiment or embodiments is believed, at the time of the filing of this patent application, to adequately describe the embodiment or embodiments of this patent application. However, portions of the description of the embodiment or embodiments may not be completely applicable to the claims as originally filed in this patent application, as amended during prosecution of this patent application, and as ultimately allowed in any patent issuing from this patent application. Therefore, any statements made relating to the embodiment or embodiments are not intended to limit the claims in any manner and should not be interpreted as limiting the claims in any manner.