MODULAR CUTTING TOOL BODY AND METHOD FOR MANUFACTURING THE SAME

Abstract

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

Claims

1. A method for manufacturing a cutting tool body comprising the steps of: manufacturing a first member, a second member, and a transition member, wherein the step of manufacturing the transition member comprises an additive manufacturing method, and wherein the first member and the second member both have a substantially cylindrical shape, and wherein the first member has a tool characteristic of a first magnitude, and the second member has a tool characteristic of a second magnitude, which is different from the first magnitude, and wherein the tool characteristic in the transition member is of the first magnitude at a first end thereof, and of the second magnitude at a second end thereof, and wherein the transition member includes a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude; connecting the first end of the transition member to the first member; and connecting the second end of the transition member to the second member to create a cutting tool body having a tool body central axis that coincides with a central axis of each of the first and the second members.

2. The method according to claim 1, further comprising the step of forming at least one flute and/or one or more cutting edges in the cutting tool body.

3. The method according claim 1, wherein the step of manufacturing the members includes manufacturing the members of cemented carbide.

4. The method according to claim 1, wherein the step of connecting the members comprises sinter fusing.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0047] FIGS. 1A-1C show a first member, a second member and a transition member, respectively.

[0048] FIG. 1D shows a cutting tool body made from the members in FIGS. 1A-1C.

[0049] FIG. 2A shows a cutting tool body in the form of a tool blank with multiple transition members.

[0050] FIG. 2B shows a cutting tool body in the form of a cutting tool, manufactured from the tool blank in FIG. 2A.

[0051] FIG. 2C is a cross-sectional view along the central axis of the cutting tool in FIG. 2B.

[0052] FIGS. 3A-3B show examples of transition members.

[0053] FIG. 4A shows a cutting tool body in the form of a tool blank.

[0054] FIG. 4B shows a cutting tool body in the form of a cutting tool, manufactured from the tool blank in FIG. 4A.

[0055] FIG. 5 is a flowchart illustrating a method for producing a cutting tool.

DETAILED DESCRIPTION

[0056] FIG. 1A shows a cylindrical first member 101 having a central axis L.sub.1. The first member has two helical internal coolant channels 104, 105, each of which has a radial distance d.sub.1 from its center to the tool body central axis, a helix angle ?1 and a cross-sectional area A.sub.1. FIG. 1B shows a cylindrical second member having a central axis L.sub.2. The second member 102 has two helical internal coolant channels 104, 105, each of which has a radial distance d.sub.2 from its center to the tool body central axis, a helix angle ?.sub.2 and a cross-sectional area A.sub.2. FIG. 1C shows a transition member having at a first end 106 two helical internal coolant channels each of which has a radial distance d.sub.1 from its center to the tool body central axis, a helix angle ?.sub.1 and a cross-sectional area A.sub.1, and at a second end 107 two helical internal coolant channels, each of which has a radial distance d.sub.2 from its center to the tool body central axis, helix angle ?.sub.2 and a cross-sectional area A.sub.2. Hence, the distance d.sub.1, helix angle ?.sub.1 and area A.sub.1 transform continuously and uniformly to distance d.sub.2, helix angle ?.sub.2 and area A.sub.2, respectively, when moving from the first end 106 to the second end 107 of the transition member. That is, the geometry of the coolant channels in the transition member corresponds to the geometry of the coolant channels 104, 105 in the first member 101 at the first end 106, and to the geometry of the coolant channels 104, 105 in the second member 102 at the second end 107.

[0057] The transition member 103 includes a transition region 108. The axial length of the transition region 108 corresponds to the axial length of the transition member 103. In other words, the transition region 108 extends over the whole length of the transition member. FIG. 1D shows a cutting tool body 109 in the form of a tool blank comprising the members shown in FIGS. 1A-1C, connected to each other. The first end 106 of the transition member 103 is connected to the first member 101 and the second end 107 of the transition member 103 is connected to the second tool blank member 102 such that a tool body central axis T of the cutting tool body 109 coincides with the central axes L.sub.1, L.sub.2 of the first and second members 101, 102 (and consequently also with a central axis of the transition member 103). For illustrative purposes, the interfaces between the members are clearly shown in the drawings. However, for a real tool, these interfaces may not be visible.

[0058] The tool characteristic transformed by the transition member is a combination of the distance between the tool body central axis and the center of each coolant channel, the helix angle, and the cross-sectional area of the coolant channels. This tool characteristic has a first magnitude in the first member defined by the distance d.sub.1, the angle ?.sub.1, the area A.sub.1, and a second magnitude in the second member defined by the distance d.sub.2, the angle ?.sub.2, the area A.sub.2. The tool blank members shown in FIGS. 1A-1C are preferably made of cemented carbide and sintered before being connected. The members may be connected by sinter fusing or brazing, for example.

[0059] A cutting tool (not shown), for example a twist drill, may be manufactured from the tool blank in FIG. 1D, where such manufacturing may involve, for example, grinding of flutes and forming of cutting edges in the tool blank. Such cutting tool body would have a first member, a second member, and a transition member corresponding to the respective members 101, 102, 103 of the tool blank 109 in FIG. 1D. The flutes of such cutting tool would preferably have helix angles corresponding to the helix angles of the internal coolant channels. The transformation of the distance d.sub.1, angle ?.sub.1 and area A.sub.1 to distance d.sub.2, angle ?.sub.2 and area A.sub.2 in the cutting tool is uniform and continuous. Thus, since the transformation is smooth and with no sudden changes, any adverse effects on the coolant flow, caused by the change, is minimized.

[0060] FIGS. 2A-2C shows another example of a cutting tool body, in the form of a tool blank 201 in FIG. 2A, and in the form of a step drill 202 in FIGS. 2B and 2C. In FIG. 2A, internal coolant channels 212, 212a, 212b are indicated with dashed lines. The interfaces between the different members 203, 204, 205, 206 and transition members 207, 208, 209 of the tool blank 201 are shown with solid lines. However, for a real tool these interfaces are not necessarily visible.

[0061] FIG. 2B is a side view of a cutting tool 202 made from the tool blank shown in FIG. 2A. The cutting tool 202 is a multi-step drill. The step drill 202 has two straight flutes 213 (of which one is shown in the drawing) and six cutting edges 214 (two at the front and two at each step).

[0062] As best seen in FIG. 2C, the step drill 202 has a first, a second, a third and a fourth member 203, 204, 205, 206 and a first, a second and a third transition member 207, 208, 209 for transforming a respective tool characteristic. In this example, the tool characteristics transformed are the same as for the corresponding members 203, 204, 205, 206 and transition members 207, 208, 209 of the tool blank in FIG. 2A. The first member 203, which in this example is the shank of the drill, is characterized by a tool body diameter D.sub.1 and one coolant channel 210 with cross-sectional area A.sub.1, located with a radial distance d.sub.1 from its center to the tool body central axis T (d.sub.1=0 since the coolant channel is centrally arranged). The second member 204 is characterized by a tool body diameter D.sub.2 and two coolant channels (210a, 210b) each having a cross-sectional area A.sub.2 and located with a radial distance d.sub.2 from its center to the tool body central axis T. The third member 205 is characterized by a tool body diameter D.sub.3 and two coolant channels each having a cross-sectional area A.sub.3 and located with a radial distance d.sub.3 from its center to the tool body central axis T. The fourth member 206 is characterized by a tool body diameter D.sub.4 and two coolant channels each having a cross-sectional area A.sub.4 and located with a radial distance d.sub.4 from its center to the tool body central axis T.

[0063] The first transition member 207 provides a transformation of a tool characteristic defined by a combination of the number of channels, a cross-sectional area of the channel, and a radial distance between a coolant channel center and the tool body central axis, i.e. a transformation from a first magnitude defined by the distance d.sub.1, area Aland a first number of coolant channels (one) to a second magnitude defined by the distance d.sub.2, area A.sub.2 and a second number of coolant channels (two). However, the tool body diameter changes instantly and is not part of the tool characteristic being transformed by the first transition member 207. The axial length of the transition region corresponds to the axial length of the transition member 207. In other words, the transition region extends over the whole length of the transition member. The transformation of the distance d.sub.1 and area A.sub.1 to distance d.sub.2 and area A.sub.2 is uniform and continuous.

[0064] The second transition member 208 provides a transformation of a tool characteristic defined by a combination of a tool body diameter, a cross-sectional area of the coolant channels, and a radial distance between a coolant channel center and the tool body central axis, i.e., a transformation from a first magnitude defined by the diameter D.sub.2, distance d.sub.2, and area A.sub.2 to a second magnitude defined by the diameter D.sub.3, distance d.sub.3, and area A.sub.3. The distance d.sub.2 and area A.sub.2 transform into distance d.sub.3 and area A.sub.3, respectively, within a first section of the transition region, whereas the diameter D.sub.2 transforms into diameter D.sub.3 within a second section, partly overlapping the first section of the transition region. Hence, in the second transition member 208, all aspects of the tool characteristic are not transformed continuously over the whole length of the transition region.

[0065] The third transition member 209 provides a transformation of a tool characteristic defined by a combination of a tool body diameter, a cross-sectional area of the coolant channels, and a radial distance between a coolant channel center and the tool body central axis, i.e., a transformation from a first magnitude defined by the diameter D.sub.3, distance d.sub.3, and area A.sub.3 to a second magnitude defined by the diameter D.sub.4, distance d.sub.4, and area A.sub.4. The third transition member is comprised of two separate transition member parts 211, 212. The first part 211 transforms the distance d.sub.3 and area A.sub.3 into distance d.sub.4 and area A.sub.4, respectively. The second part 212 transforms the diameter D.sub.3 into diameter D.sub.4. The parts of the transition member are preferably connected to each other during the process when also all the other members are connected. Thus, the transition member does not have to be assembled prior to connecting all the other members of the cutting tool body.

[0066] FIG. 3A illustrates an example of a transition member 301 for transforming a single, centrally arranged, coolant channel into four separate coolant channelstwo with a first cross-sectional diameter and distance from the central axis, and two with a second, different, cross-sectional diameter and distance from the central axis. The axial length of a transition region 302 is smaller than the axial length of the transition member 301. Accordingly, there is a region 303 at each respective end of the transition member 301 where the geometry of the coolant channel(s) is non-changing.

[0067] FIG. 3B illustrates an example of a transition member 304 for transforming two coolant channels into a single central coolant channel and also transforming (reducing) the cutting tool body diameter.

[0068] Transition members as those shown in FIGS. 3A and 3B may be combined such as to form a single transition member. In such arrangements, the transition members 301 and 304 would be considered as parts of the transition member. A benefit of the temporary transformation to a single coolant channel in the junction between the parts 301 and 304 is that such configuration makes it easier to combine different parts with different output- and input geometries. Thus, since parts would be combinable to a greater extent, many different transformations are obtainable using a relatively small set of different transition member parts.

[0069] FIG. 4A shows another embodiment of a cutting tool body 401 in the form of a tool blank, having a transition member 402. This transition member transforms a single straight coolant channel into two helical coolant channels and also transforms the tool body diameter. Furthermore, the transition member includes two additional coolant channels 403 branching off from the internal coolant channels to provide coolant to the exterior of the cutting tool body.

[0070] FIG. 4B shows a cutting tool 404 (a step drill) made from the tool blank in FIG. 4A. The additional coolant channels 403 opens in the exterior of a transition member 402 (which corresponds to the transition member 402 of the tool blank in FIG. 4A). The coolant channels 403 (of which one is visible in the FIG. 4B) opens in the region of the diameter transition, i.e., near the cutting edges of the drill's step. Hence, coolant will be efficiently delivered to the region where it is needed. A similar configuration might be advantageous also for other kinds of tools, for example for end mills, where it is beneficial to convey coolant to the peripheral cutting edges, with or without also changing the diameter of the tool body.

[0071] FIG. 5 is a flowchart illustrating a method for producing a cutting tool body according to the invention. In step 501, members of a cutting tool body are manufactured, comprising a first member, a second member and a transition member. Preferably, the first member and the second member are made using conventional manufacturing methods, for example machining (turning) a cemented carbide rod into a specific diameter, drilling coolant holes, etc., followed by sintering. The transition member is preferably manufactured using alternative manufacturing methods, such as additive manufacturing, better suited for creating complex geometries.

[0072] In step 502, a first end of the transition member is connected to the first member and a second end of the transition member is connected to the second member. If the transition member comprises two or more parts, these are also connected. The connection of all members and part of members may be made using sinter fusing or brazing, or any other suitable method for joining parts.

[0073] In the optional step 503, the tool body is machined to form the final shape of a cutting tool. Such machining may involve forming chip flutes and cutting edges, for example by grinding.

[0074] Although the present embodiment(s) has been described in relation to particular aspects thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred therefore, that the present embodiment(s) be limited not by the specific disclosure herein, but only by the appended claims.