CUTTING TOOL

Abstract

A cutting tool comprises a tool body having a first end and a second end, and a longitudinal axis extending between the first end and the second end. The first end comprises two or more cutting portions, with each of the cutting portions comprising a cutting edge and a flank surface.

Each cutting edge extends radially outwardly from a centre region of the first end to a perimetral edge of the first end, with the cutting edge being angled relative to the longitudinal axis. Each flank surface extends circumferentially from the cutting edge.

Each of at least two of the two or more flank surfaces comprises an abrasive portion extending over at least a part of the respective flank surface and each abrasive portion comprises a plurality of abrasive features.

Claims

1. A cutting tool comprising: a tool body having a first end and a second end, the tool body having a longitudinal axis extending between the first end and the second end, the first end comprising two or more cutting portions, wherein each of the cutting portions comprises: a cutting edge extending radially outwardly from a centre region of the first end to a perimetral edge of the first end, the cutting edge being angled relative to the longitudinal axis; and a flank surface extending circumferentially from the cutting edge, characterised in that each of at least two of the two or more flank surfaces comprises an abrasive portion extending over at least a part of the respective flank surface, and each abrasive portion comprises a plurality of abrasive features.

2. The cutting tool as claimed in claim 1, wherein the abrasive features have a circular profile.

3. The cutting tool as claimed in claim 1, wherein the abrasive features extend from the flank surface as conical frusta.

4. The cutting tool as claimed in claim 1, wherein the abrasive features are arranged in two adjacent rows across the flank surface, each row extending radially across the flank surface, the first row positioned adjacent to a circumferentially trailing edge of the flank surface, the second row being radially offset from the first row.

5. The cutting tool as claimed in claim 1, wherein each abrasive feature extends from the flank surface by a feature height, the feature height increasing with radially distal feature position.

6. The cutting tool as claimed in claim 5, wherein the feature height of each abrasive feature is equal to the corresponding depth of the cut along the cutting edge.

7. The cutting tool as claimed in claim 1, wherein each cutting edge extends linearly from the centre region of the first end to a perimetral edge of the first end, each cutting edge subtending a first angle with the longitudinal axis.

8. The cutting tool as claimed in claim 1, further comprising two or more flutes extending along at least a part of the tool body, and wherein each of the two or more cutting edges corresponds to a respective one of the two or more flutes.

9. The cutting tool as claimed in claim 1, wherein the cutting tool is integrally formed from a material selected from the group consisting of diamond materials and cubic boron nitride materials.

10. The cutting tool as claimed in claim 1, wherein the cutting tool is formed from a base material selected from the group consisting of steel, titanium, and carbide materials, and the base material is provided with a coating layer selected from the group consisting of diamond materials and cubic boron nitride materials.

11. A method of forming a cutting tool, the method comprising the steps of: providing a tool body having a first end, a second end, and a longitudinal axis extending from the first end to the second end; forming two or more cutting portions at the first end, each cutting portion comprising a cutting edge and a flank surface, each cutting edge extending radially outwardly from a centre region of the first end to a perimetral edge of the first end, the cutting edge being angled relative to the longitudinal axis, and each flank surface extending circumferentially from the cutting edge; characterised in that the method comprises the further step of: forming an abrasive portion over at least a part of each of at least two of the two or more of the flank surfaces, with each abrasive portion comprising a plurality of abrasive features.

12. The method as claimed in claim 11, wherein the step of forming two or more cutting portions at the first end, comprises the additional step of: forming two or more flutes along the tool body, each twisted flute corresponding to a respective one of the cutting portions, each flute extending from the perimetral edge of the first end along at least a part of the tool body.

13. The method as claimed in claim 11, wherein the tool body is formed from a diamond material, and the step of forming an abrasive portion over at least a part of each of at least two of the two or more of the flank surfaces, comprises the step of: selectively creating (i.e. by laser ablating, electro-discharge machining, electroplating or brazing) a part of the flank surface on at least two of the two or more of the flank surfaces to generate a plurality of abrasive features extending from the flank surface.

14. The method as claimed in claim 11, wherein each abrasive feature extends from the flank surface by a feature height, the feature height increasing with radially distal feature position.

15. The cutting tool as claimed in claim 14, wherein the feature height of each abrasive feature is equal to the corresponding depth of the cut along the cutting edge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] There now follows a description of an embodiment of the disclosure, by way of non-limiting example, with reference being made to the accompanying drawings in which:

[0069] FIG. 1 shows a schematic sectional view of a ceramic matrix composite material;

[0070] FIGS. 2A to 2C show respectively schematic elevational, partial perspective, and end views of a cutting tool according to an embodiment of the disclosure; and

[0071] FIG. 3 shows a schematic enlarged partial perspective view of a flank surface of the cutting tool of FIGS. 2A to 2C;

[0072] FIG. 4A shows a schematic representation of the action of the cutting edge of a conventional cutting tool; and

[0073] FIG. 4B shows a schematic representation of the action of the cutting edge and corresponding abrasive portion of the cutting tool of FIGS. 2A to 2C.

[0074] It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION

[0075] Referring to FIGS. 2 and 3, a cutting tool according to an embodiment of the disclosure is designated generally by the reference numeral 100.

[0076] The cutting tool 100 comprises a tool body 110 having a first end 112 and an opposite second end 114. In the present embodiment, the tool body 110 has a generally cylindrical geometry. In other embodiments, the tool body 110 may have an alternative elongate geometry. The tool body 110 has a longitudinal axis 120.

[0077] In the present embodiment the second end 114 corresponds to a shank or holding portion (not shown) which would be used to hold the cutting tool 100 in a machine tool (not shown).

[0078] The first end 112 of the tool body 110 has a centre region 114 and a perimetral edge 116. The centre region 114 of the first end 112 corresponds to the intersection of the longitudinal axis 120 with the first end 112. The perimetral edge 116 of the first end 112 corresponds to the circumferential edge of the first end 112 of the first end 110.

[0079] The first end 112 comprises two cutting portions 130. In other embodiments the first end 112 may comprise more than two cutting portions 130.

[0080] Each of the cutting portions 130 comprises a cutting edge 132 and a corresponding flank surface 140. Each flank surface 140 extends circumferentially (direction 138) away from the respective cutting edge 132.

[0081] Each cutting edge 132 extends radially outwardly from the centre region 114 of the first end 112 to the perimetral edge 116 of the first end 112. Each cutting edge 132 is oriented at an angle 134 relative to the longitudinal axis 120. In the present embodiment, each cutting edge 132 extends linearly from the centre region 114 of the first end 112 to the perimetral edge 116 of the first end 112, with each cutting edge 132 subtending a first angle 136 with the longitudinal axis.

[0082] Each of the cutting edges 132 extends from the perimetral edge 116 of the first end 112 towards the second end 118 along at least a part of the tool body 110 as a twisted flute 162.

[0083] At least two of the two or more flank surfaces 140 comprise an abrasive portion 142 that extends over at least a part of the respective flank surface 140. In the case where the first end 112 comprises two cutting edges 132 (as in the present embodiment) then each one of the two corresponding flank surfaces 140 comprises an abrasive portion 142. In an alternative embodiment where the first end 112 comprises four cutting edges then either two, or all four, of the corresponding flank surfaces 140 may comprise an abrasive portion 142.

[0084] Each of the abrasive portions 142 comprises a plurality of abrasive features 144. The abrasive features 144 are arranged in two rows 150 across the flank surface 140. Each of the two rows 150 of abrasive features 144 extends radially across the flank surface 140. A first row 152 of abrasive features 144 is positioned at a circumferentially trailing edge 141 of the flank surface 140.

[0085] The second row 154 of abrasive features 144 is circumferentially (direction 138) offset from the first row 152. The abrasive features 144 forming the second row 154 are also offset radially from the abrasive features 144 forming the first row 152. This radial offset 156 is arranged such that each abrasive feature 144 in the second row 154 corresponds to the gaps between adjacent ones of the abrasive features 144 in the first row 152.

[0086] Each of the abrasive features 144 has a circular plan section 146 and each abrasive feature 144 extends from the flank surface 140 as a conical frustum 148.

[0087] Each abrasive feature 144 extends from the corresponding flank surface 140 by a feature height 158. The feature height 158 of each abrasive feature 144 increases with radially distal feature position. In other words each abrasive feature 144 has a feature height 158 that is greater than its radially proximal neighbour.

[0088] In the present embodiment the cutting tool 100 is integrally formed from polycrystalline diamond. The process of forming the cutting edges 132, flank surfaces 140 and longitudinal flutes 162 is known and is not described further herein.

[0089] The abrasive features 144 are formed integrally with the flank surface 140 by selectively ablating a part of each of the flank surfaces 140. This selective ablation leaves the frustoconical abrasive features 144 standing proud of the flank surface 140. The selective ablation process may be carried out by any suitable means such as, for example, a gas laser.

[0090] The abrasive features 144 may alternatively be formed by selectively modifying the flank surfaces 140 using electro-discharge machining. A further alternative arrangement may involve electroplating or brazing the abrasive features 144 to the flank surfaces 140.

[0091] In an alternative embodiment where the cutting tool 100 is formed from, say, a carbide material with a polycrystalline diamond coating being subsequently applied, the selective ablation process may be applied to the coating layer in the same manner as outlined above to produce the array of abrasive features 144.

[0092] In use, the abrasive portion 142 provides a supplementary cutting action and so reduces the cutting forces experienced by the cutting edge 132. This reduction in cutting force leads to a consequent reduction in the wear rate of the cutting edge 132.

[0093] FIG. 4A illustrates schematically the cutting action of a cutting tool 30 (in this case a twist drill) according to the prior art. The cutting tool 30 comprises two cutting edges 32 and two flank surfaces 40. Each flank surface 40 extends circumferentially away from a respective one of the cutting edges 32.

[0094] As the cutting tool 30 meets a material 60 each cutting edge 32 removes a portion of the material 60. This removed material has a depth h.sub.D that is referred to as the uncut chip thickness (or colloquially as the depth of cut). In the cutting tool 30 of the prior art the removal of material is performed entirely by the cutting edges 32.

[0095] In contrast, FIG. 4B shows a schematic illustration of the cutting action of the cutting tool 100 of the present disclosure. As shown in FIG. 4B, and as described above, the removal of material is effected by both the cutting edges 132 and the abrasive features 144.

[0096] Each of the abrasive features 144 removes a portion of material having a depth h.sup.grid.sub.D, and each cutting edge removes a portion of material having a depth h.sup.edge.sub.D. Each of the cutting edges 132 acts as a conventional cutting edge 32 of the prior art, and cuts along its entire linear length. Each of the abrasive features 144 removes material by a ploughing action as illustrated by the enlarged perspective view in FIG. 4B of one such abrasive feature. In this way each of the cutting edges 132 performs less work then a cutting edge 32 of the prior art and hence experiences a lower cutting force and a lower wear rate.

[0097] In one arrangement, each of the abrasive features 144 has a feature height 158 that is equal to the depth of cut h.sup.edge.sub.D of the corresponding cutting edge. In other words, in this arrangement, the abrasive feature has a depth of cut h.sup.grid.sub.D that is equal to the corresponding depth of cut h.sup.edge.sub.D of the corresponding cutting edge.

[0098] Although the aforementioned embodiments relate to the machining of CMC materials, it is to be understood that the positioning of abrasive features on the flank surfaces of a cutting tool may equally be applied to other cutting tool geometries and materials (i.e. coated and uncoated cemented carbide tools), and also to other machining processes (i.e. to turning inserts, or ball end milling cutters) commonly used for machining aerospace materials such as, for example, nickel and titanium alloy steels.

[0099] Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

[0100] The foregoing description of various aspects of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person of skill in the art are included within the scope of the disclosure as defined by the accompanying claims.