Patent Application
20220072628
When removing material from a work piece, breaking the material into discrete chips improves the ability of the removed material to flow more easily out of the work piece area, and also reduces heat generation and the pressure exerted on the end mill. Rotary cutting tools, such as end mills, sometimes include chip breaker features that help break otherwise continuous chips of material into discrete chips of material. These cutting tools, also known as “chip breaker tools” or “chip breakers,” have been developed to facilitate chip removal by creating discrete chips, and include chip breaking features or notches that are cut transversely into the cutting blades at spaced intervals. As compared to a conventional cutting tool with cutting edges that do not include such chip breaking features or notches, the cutting edges of chip breakers are provided as interrupted cutting edges.
The chip breaker features may be provided in various configurations. Chip breaker tools configured for roughening operations may be provided with wavy notch patterns, also known as sinusoidal chip breakers, and such tools produce a rougher finish on the work piece. Other chip breaker tools include a series of notches that provide similar benefits as the sinusoidal design but are easier to manufacture and, because a portion of the original cutting edge is retained, they tend to produce a smoother surface finish on the work piece. Regardless of their configuration, chip breaker features produce smaller chips, and these smaller chips are more easily removed from conventional milling machines that often utilize auger type clean out systems.
Chip breaker tools have several drawbacks that decrease their tool life. First, because a portion of the cutting edge has been removed, the interrupted cutting edge will wear out faster, thereby decreasing overall tool life. Second, because the cutting edge is interrupted by a series of non-cutting gaps (i.e., the notches), some portions of the work piece are missed and removed by the subsequent cutting edge or edges. Here, the subsequent edges or edges are subjected to additional load when they remove the missed material and may be chipped. This chipping also decreases tool life.
In accordance with the present disclosure, a chip breaker geometry is provided. The chip breaker geometry may be utilized in a variety of rotary cutting tools having cutting blades. In some examples, the chip breaker geometry may include a plurality of notches formed into radial relief surfaces of the blades at an angle relative to a tool axis, wherein the angle is sufficient to define a secondary cutting edge in each of the notches. The notches may be uniformly distributed along each of the blades, or the notches may be randomly distributed along the blades, or the notches may be both uniformly distributed and randomly distributed.
Also provided herein is a cutting tool having cutting blades and at least one chip breaker arranged on each of the blades. The chip breakers may each define a gap, and at least one of the gaps may include a secondary cutting edge that overlaps at least a portion the gap defined in the preceding cutting blade.
Also provided herein is an uninterrupted cutting edge for a rotary cutting tool. In these examples, the uninterrupted cutting edge may include at least one first notch arranged at an intersection between a leading face of the first blade and a radial relief surface of the first blade, and at least one second notch arranged at an intersection between a leading face of the second blade and a radial relief surface of the second blade, wherein the at least one second notch at least partially overlaps the first notch upon rotation of the rotary cutting tool.
The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure.
The present disclosure is related to rotary cutting tools and, more particularly, to rotary cutting tools with chip breaker features.
The embodiments described herein provide rotary cutting tools, such as end mills, with chip breaker features that eliminate voids along a periphery of the rotary cutting tool such that there is no excess material for subsequent cutting edges to remove.
As illustrated, the cutting tool 100 generally includes a cylindrical body 102 that extends longitudinally along an axis A1 of the cylindrical body 102. Here, the cylindrical body 102 includes a shank portion 104 and a cutting portion 106 that generally defines the length of cut of the cutting tool 100, and the cutting portion 106 extends longitudinally along the axis A1 to an axial face or axial end 108 of the cutting tool 100. The cutting portion 106 is illustrated as having a generally cylindrical shaped periphery, but it may be configured with various other geometries without departing from the present disclosure, including but not limited to a frusto-conical shape or ball nose shape.
The cutting portion 106 includes a plurality of blades 110 that are separated by a plurality of flutes 112. Each of the blades 110 has a leading face surface 114, a trailing face surface 116, and a radial relief surface 118 that bridges the leading face surface 114 and trailing face surface 116. As to each of the blades 110, a cutting edge 120 is formed at the intersection between the leading face surface 114 and the radial relief surface 118. Here, the blades 110 and flutes 112 extend along the cutting portion 106, helically about the axis A1. The blades 110 may be oriented at various helix angles that are measured with respect to the axis A1, and in other non-illustrated embodiments, the blades 110 and the flutes 112 may even be oriented parallel to the axis A1. In operation, chips are removed from the work piece upward through the flutes 112 and towards the shank portion 104, and/or chips may be removed downward way from the shank portion 104 depending on cut direction of the cutting tool 100 (e.g., left-hand or right-hand helix).
The radial relief surface 118 may have various configurations. For example, the radial relief surface 118 may exhibit a generally cylindrical configuration, a generally planar configuration, a not-concave configuration, a faceted configuration, or an eccentric configuration when evaluated in cross section. Also, the radial relief surface 118 may include one or more relief surfaces that are oriented at one or more corresponding relief angles. For example, the radial relief surface 118 may include a primary relief surface disposed contiguous with the cutting edge 120 extending at a first relief angle relative to a tangential line drawn at the cutting edge 120. In other examples, the radial relief surface 118 may include a secondary relief surface that is disposed on a side of the primary relief surface opposite of the cutting edge 120 at a second relief angle relative to the previously mentioned tangential line, where the magnitude of the second relief angle is greater than the magnitude of the first relief angle. In even other examples, the radial relief surface 118 may include additional relief surfaces, such as a tertiary portion disposed on a side of the second relief surface that is opposite of the first relief surface. These relief surfaces may be provided linearly, or may extend arcuately to blend into each other and/or the trailing face surface 116.
The cutting tool 100 is configured as a chip breaker (i.e., a chip breaking end mill) and thus includes a plurality of chip breaking features 122 disposed along the cutting edges 120. Conventional cutting tools (i.e., without chip breaking features) have continuous cutting edges that remove long and continuous chips of material from work pieces. In contrast, the plurality of chip breaking features 122 arranged in the cutting edges 120 of the cutting tool 100 break each of those otherwise continuous chips of material into discrete chips of material. The chip breaking features 122 may be notches or recesses that are ground or otherwise formed into the radial relief surface 118.
The chip breaking features 122 are disposed in the radial relief surface 118, extending there-through along a notch axis N1, and open into the leading face surface 114 at the cutting edge 120. As illustrated, the chip breaking features 122 on the cutting edge 120 of one of the blades 110 are offset longitudinally along the axis A1 from the chip breaking features 122 on the other blades 110 (i.e., the notch axes N1 of the chip breaking features 122 on one of the cutting edges 120 do not align with the notch axes N1 of the chip breaking features 122 on another of the cutting edges 120). Thus, the chip breaking features 122 on any one of the blades 110 are not in alignment with the chip breaking features 122 of any other of the remaining blades 110 when the cutting tool 100 is rotated in direction R about the axis A1.
During operation, the chip breaking features 122 generate a reduction in cutting force experienced in the blades 110 in which they are disposed, and thereby enhance performance. The cutting edges 120 remove material from the workpiece (i.e., in the form of chips) and such material is pushed out through the flutes 112. However, the chip breaking features 122 each define a gap or void 124 in the cutting edge 120 where material is not removed from the work piece, resulting in the cutting edge 120 removing smaller discrete chips that are then pushed through the flutes 112. As discussed below, however, these portions of workpiece material that are not cut (i.e., removed from the work piece) as they pass through the gaps or voids 124 in the cutting edge are later cut (i.e., removed from the work piece) by the cutting edges 120 of one or more of the other blades 110 as the cutting tool 100 continues to rotate.
The chip breaking features 122 and the gaps or voids 124 defined thereby may have various geometries. In the illustrated example, all of the chip breaking features 122 (and, thus, the gaps or voids 124) have an arcuate shaped geometry. In other examples, the chip breaking features 122 (and the gaps or voids 124) may all be of a different geometry, for example, rectangular geometries, triangular geometries, and combinations of the same. In even other embodiments, the chip breaking features 122 (and the gaps or voids 124) of one of the blades 110 may have a different geometry from the chip breaking features 122 (and the gaps or voids 124) of the remaining of the blades 110. Moreover, in some example the chip breaking features 122 (and the gaps or voids 124) of one or more of the blades 110 have different geometries.
Various methods may be utilized to form the chip breaking features 122, regardless of their geometry. In one example, the chip breaking features 122 are ground into the radial relief surface 118.
The chip breaking features 122 (and the gaps or voids 124 that correspond therewith) may also have various orientations and pitches. In the example of
In these examples, the gaps or voids 124 in the cutting edges 120 leave excess material for subsequent cutting edges 120 to remove during a material removal operation. It is this excess material (i.e., the material that passed over by a first of the blades 110 and left to be removed by one or more subsequent blades 110) that causes the overload in the cutting edges 120. Thus, as the cutting tool 100 rotates in direction R about the axis A1, the cutting edge 120 of a first of the blades 110 engages the work piece such that the cutting edge 120 removes material except at the chip breaking features 122, where remaining material pass through the gap or void 124; and the ensuing cutting edges 120 of the subsequent blades 110 each experience greater loads as they clean up and remove portions of that remaining material that was left by the gaps or voids 124 in the cutting edges 120 of the preceding blades 110. Thus, the cutting edges 120 may experience increased loading at areas proximate to the chip breaking features 122, which may result in decreased tool life.
This increased loading (or overloading) of the cutting edges 120 at areas proximate the chip breaking features 122 is illustrated with respect to
Here, for example, the first interrupted cutting edge 1 removes material from the work piece, except that the chip breaking feature 122 thereof does not remove material from the work piece. This material that passes through the gap or void 124 and is not removed from the work piece is referred to as “left over material.” As the second interrupted cutting edge 2 rotates into engagement with the workpiece, the second interrupted cutting edge 2 removes material from the work piece, including a portion of the left over material that was left by the chip breaking feature 122 of the first interrupted cutting edge 1, but the second interrupted cutting edge 2 also does not remove material at the location of its chip breaking feature 122. The chip breaking feature 122 in the second interrupted cutting edge 2 are longitudinally offset from chip breaking feature 122 in the first interrupted cutting edge 1 so that the second interrupted cutting edge 2 removes its normal amount of material plus only a portion of the left over material. Thus, some portions of the second cutting edge 2 are removing twice the amount of material because these portions of the second cutting edge 2 are removing some of the left over material that was not removed via the gaps or voids 124 in the first interrupted cutting edge 1. As the third interrupted cutting edge 3 rotates into engagement with the workpiece, the third interrupted cutting edge 3 removes material from the work piece, including a portion of the left over material that was left by the gaps or voids 124 in the first interrupted cutting edge 1 and the second interrupted cutting edge 2, but the third interrupted cutting edge 3 also does not remove material at the location of its gaps or voids 124 so that a portion of the left over material is remains for one or more subsequent cutting edges (e.g., the fourth interrupted cutting edge 4) to engage and remove (clean up). As previously mentioned, the chip breaking features 122 in the third interrupted cutting edge 3 are longitudinally offset from the chip breaking features 122 in the first and second interrupted cutting edges 1,2 so that the third interrupted cutting edge 3 removes its normal amount of material plus only a portion of the left over material. Thus, some portions of the third interrupted cutting edge 3 are removing triple the amount of material, as the third interrupted cutting edge 3 is also removing some of the left over material that passed through the gaps or voids 124 in the first and second interrupted cutting edges 1,2 and was not removed by the first and second interrupted cutting edges 1,2. As the fourth interrupted cutting edge 4 rotates into engagement with the workpiece, the fourth interrupted cutting edge 4 removes material from the work piece, including a portion of the left over material that was left by the gaps or voids 124 in the first, second, and third interrupted cutting edges 1,2,3. However, the fourth interrupted cutting edge 4 does not remove material at the location of its gaps or voids 124, which are longitudinally offset from chip breaking feature 122 in the first, second, and third interrupted cutting edges 1,2,4, thereby resulting in the fourth interrupted cutting edge 4 removing its normal amount of material plus the remaining portion of the left over material that was not cleaned up by the second or third interrupted cutting edges 2,3. Thus, some portions of the fourth interrupted cutting edge 4 are removing quadruple the amount of material, as the fourth interrupted cutting edge 4 is also removing portions of the left over material that was not removed by the chip breaking feature 122 of the first, second, and third interrupted cutting edges 1,2,3. Accordingly, areas of the various interrupted cutting edges 1,2,3,4 may encounter elevated loads that may exceed the programmed feed rate.
According to embodiments of the present disclosure, chip breaking features may be arranged nearly parallel to the axis A1. In such embodiments, the chip breaking features each define a secondary cutting edge, and these secondary cutting edges eliminate any overlapping or alignment of the gaps or voids 124 between neighboring cutting edges 120 when the chip breaking features 122 are oriented approximately perpendicular to the axis A1 as described with reference to
The gapless chip breaker 400 illustrated and described herein is similar to the cutting tool 100 of
The cutting portion 406 includes a plurality of blades 410 that are separated by a plurality of flutes 412. Each of the blades 410 has a leading face surface 414, a trailing face surface 416, and a radial relief surface 418 that bridges the leading face surface 414 and trailing face surface 416. As to each of the blades 410, a cutting edge 420 is formed at the intersection between the leading face surface 414 and the radial relief surface 418. Here, the blades 410 and the flutes 412 extend along the cutting portion 406, helically about the axis A2. The blades 410 and the flutes 412 may be oriented at various helix angles that are measured with respect to the axis A2, and in other non-illustrated embodiments, the blades 410 and the flutes 412 may be oriented approximately parallel to the axis A2. Also, in some examples, the corner radius R and/or the axial end 408 may be configured to make cuts and, in such embodiments, may include either or both of a radius cutting edge and/or an axial cutting edge, respectively. Where utilized, the cutting edge 420 may smoothly transition into the radius cutting edge, which may in turn smoothly transition into the axial cutting edge.
The radial relief surface 418 may have various configurations. In the illustrated example, the radial relief surface 418 exhibits a generally cylindrical configuration when evaluated in cross section. In other embodiments, the radial relief surface 418 may exhibit a generally planar configuration, a not-concave configuration, a faceted configuration, or an eccentric configuration when evaluated in cross section. Also, the radial relief surface 418 may include one or more relief surfaces that are oriented at one or more corresponding relief angles, as described above with reference to
The gapless chip breaker 400 also includes a plurality of chip breaking features 422 arranged in each of the cutting edges 420. As described herein, the chip breaking features 422 interrupt the cutting edges 420 (i.e., such that the cutting edges 420 discontinuous), which results in smaller, discrete chips rather than long continuous chips that would be formed by an uninterrupted or continuous cutting edge. The chip breaking features 422 may be ground or otherwise formed in the radial relief surface 418. Here, the chip breaking features 422 are uniformly distributed in each of the cutting edges 420, and the chip breaking features 422 of each cutting edge 420 are off set (along the axis A2) relative to the chip breaking features 422 in the other cutting edges 420. Moreover, in embodiments where the cutting portion 406 includes either or both of the radius cutting edge and/or the axial cutting edge, the chip breaking features 422 may be similarly arranged within either or both of the radial cutting edge and/or the axial cutting edge.
The chip breaking features 422 may have various geometries. In the illustrated embodiment, the chip breaking features 422 are formed with an arcuately-shaped base. In other embodiments, however, the chip breaking features 422 may include a substantially rectangular geometry, a substantially triangular geometry, trapezoidal, etc. In addition, in some embodiments, the chip breaking features 422 in one or more cutting edges 420 may have various geometric configurations.
The chip breaking features 422 may also have various organizations or distributions in each of the cutting edges 420 and/or between two or more cutting edges 420. For example, the chip breaking features 422 may be non-uniformly distributed within each of the cutting edges 420, and/or may be non-uniformly distributed between adjacent cutting edges 420. Where utilized, the pattern of non-uniformly distributed chip-breaking features 422 may be such that the material being machined at any given position is not subject to a uniform pattern of chip breaking features 422 as the gapless chip breaker 400 rotates. As a result, the gapless chip breaker 400 is not subject to significant uniform periodic forces that may give rise to an undesirable harmonic response under acceptable operating conditions. The non-uniform organizations or distributions may be created by arrangements such as, but not limited to: 1) dissimilar spacing between the chip breaking features 422 within a particular cutting edge 420; 2) dissimilar spacing (of the chip breaking features 422) between adjacent cutting edges 420; 3) dissimilar types (of the chip breaking features 422) within a particular cutting edge 420; 4) dissimilar types (of the chip breaking features 422) in adjacent cutting edges 420; 5) dissimilar groupings of chip breaking features 422 within a particular cutting edge 420; 6) dissimilar groupings of chip breaking features 422 between adjacent chip breaking features 422; or combinations thereof, etc.
The chip breaking features 422 are notches that extend through the radial relief surface 418 along a notch axis N2, between the leading face surface 414 and the trailing face surface 416. Thus, the chip breaking features 422 are each oriented at a notch angle α, where the notch angle α is evaluated between the notch axis N2 and the axis A2. As further described below, a secondary cutting edge 424 may be defined in the chip breaking features 422 that are oriented with notch angles α that are less than 90°.
In the illustrated embodiment, all of the chip breaking features 422 are oriented at the same notch angle α. In other embodiments, however, the chip breaking features 422 need not all be oriented at the same notch angle α. For example, the chip breaking features 422 on one or more of the cutting edges 420 may be oriented at a different notch angle α than the chip breaking features 422 on one or more of the remaining cutting edges 420. In these or other examples, at least one of the chip breaking features 422 (or at least one group of chip breaking features 422) on one of the cutting edges 420 may have a different notch angle α than the other chip breaking features 422 (or other groups of chip breaking features 422) on that cutting edge 420.
By orienting the chip breaking features 422 with the notch angle α that defines the secondary cutting edge 424, the secondary cutting edge 424 on the radial relief 418 may eliminate any gap or void that may exist between the chip breaking features 422 in adjacent cutting edges 420. Thus, the secondary cutting edges 424 of one of the blades 410 may remove or clean up any left over material that was not removed by the cutting edge 420 (e.g., via the chip breaking features 422 thereof) of that same blade 410. This will lower the loading on the adjacent blades 410 as they will not need to remove and clean up as much material (for example, the adjacent blades 410 will clean up a remaining small amount of material that is equivalent to the radial relief), which in turn improves tool life and part finish.
The chip breaking features 424 may be oriented at various angles. As mentioned, the notch angle α of each of the chip breaking features 422 is sufficient for providing the secondary cutting edge 424. The notch angle α may be selected such that the secondary cutting edge 424 closes the gaps or voids in the cutting edge 420 that would otherwise permit left over material to remain for subsequent cutting edges 420 to clean up. Thus, as illustrated in
In some of these examples, the notch angle α is selected such that less than the entire length of the secondary cutting edge 424 closes the gaps or voids in the cutting edge 420 that would otherwise permit left over material to remain for subsequent cutting edges 420 to clean up (e.g., the portion 606 of the secondary cutting edge 424 as illustrated in
The chip breaking feature designs disclosed herein may various configurations depending on the tool upon which they are provided.
Thus, a certain end mill may be configured with a first set of chip breaking features to provide it with a “gapless” design or instead be configured with various other sets of chip breaking features that also provide it with a “gapless” design. In some examples, any combination of right-hand and left-hand helix and chip breaker width, and radial relief angle that eliminates the normally open area in the cutting edge would create a gapless chip breaker. In these examples, the primary radial relief may be eccentric or flat (e.g., not concave) and may be of enough width to cover the gap.
Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.
The use of directional terms such as above, below, upper, lower, upward, downward, left, right, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward or upper direction being toward the top of the corresponding figure and the downward or lower direction being toward the bottom of the corresponding figure.
As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C.
This application claims priority to and the benefit of pending U.S. Provisional Application No. 62/785,795 filed Dec. 28, 2018, which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/068577 | 12/26/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62785795 | Dec 2018 | US |
