Patent Application
20230364684
The present disclosure relates to a cutting insert used in machining for a workpiece, a rotary tool, and a method for manufacturing a machined product.
As a rotary tool used when machining a workpiece made of metal or the like, a drill bit disclosed in Patent Document 1 is known, for example. The drill bit described in Patent Document 1 has a cutting edge, a rake face, and a helical flute (flute). When the rotating drill bit is brought into contact with the workpiece to perform drilling, chips produced by the cutting edge are curled in the rake face and discharged to the outside of the workpiece through the flute.
Patent Document 1: JP 2019-501787 T
A cutting insert as one non-limiting example includes a main body extending from a first end toward a second end along a rotational axis. The main body includes: a cutting edge positioned on a side of the first end; a rake face extending from the cutting edge toward the second end; and a flute extending from the rake face toward the second end. The rake face includes: a first surface region connected to the cutting edge and having a first rake angle; a second surface region positioned closer to the second end than the first surface region and having a second rake angle; and a third surface region positioned closer to the second end than the second surface region and having a third rake angle. The flute is positioned closer to the second end than the second surface region is. The third surface region is adjacent to the flute rearward in a rotational direction about the rotational axis and on a side of an outer peripheral of the main body. The second rake angle is smaller than the first rake angle, and the third rake angle is smaller than the second rake angle.
Detailed description will be given below of a cutting insert (hereinafter, also simply referred to as an insert), a rotary tool, and a method for manufacturing a machined product of a non-limiting embodiment of the present disclosure with reference to the diagrams. However, for convenience of explanation, each of the drawings referenced below is simplified to illustrate only the main members necessary to describe the embodiment. Accordingly, the insert and the rotary tool may be provided with any constituent member that is not illustrated in each of the drawings referenced in this specification. The dimensions of the members in the drawings do not faithfully represent the actual dimensions of the constituent members, the dimension ratios of the members, or the like.
First, an overview of an insert 1 of an embodiment is described with reference to
As illustrated in
The insert 1 has the cutting portion 10 formed on the first end 10A side of the main body 2. The cutting portion 10 is a portion that comes into contact with a workpiece T that is a process target (see
The insert 1 is rotatable about the rotational axis R1 when cutting the workpiece. An arrow R2 illustrated in
The shaft portion 3 extends along the rotational axis R1. The shaft portion 3 may be used as a portion held by a holder 102 described below, by being fitted and fixed in a pocket 111 provided to the holder 102, when the insert 1 is attached to the holder 102 (see
The size of the shaft portion 3 is not particularly limited, and the maximum width of the shaft portion 3 in a direction orthogonal to the rotational axis R1 may be set to, for example, about 3 to 10 mm The dimension of the shaft portion 3 in a direction along the rotational axis R1 (longitudinal direction) may be set from about 3 to 10 mm for example.
The size of the main body 2 is also not particularly limited. A diameter of a virtual circle drawn with the rotational axis R1 being the center point to be in contact with the outer edge of the main body 2 in a front view of the main body 2 from the first end 10A side in a direction parallel to the rotational axis R1 may be set to be about 10 to 40 mm for example. The dimension of the main body 2 in a direction along the rotational axis R1 from the first end 10A to a trailing end of the main body 2 (a connection portion between the main body 2 and the shaft portion 3) may be set to be about 5 to 20 mm for example.
The main body 2 and the shaft portion 3 in the insert 1 may be formed separately and joined together or may be formed integrally.
Note that, in the present specification, the description of “flat” or “flat surface” intends to mean that the surface is not a curved surface at a visible level or does not have unevenness at a visible level. Thus, for a surface referred to as being “flat” or “flat surface”, an unavoidable degree of unevenness may be allowed in the manufacture of insert 1. Specifically, unevenness with a surface roughness of about 50 μm may be allowed for example. The “rotational axis” can also be expressed as a straight line (center line, center axis) passing through (i) the first end 10A and (ii) the center or substantially the center of a surface of the second end 3A of the shaft portion 3.
The front view in
In the side view in
With known drill bits (see, for example, Patent Document 1), attempts have been made to control the chips into a desired shape in the rake face. Unfortunately, the attempt to control the chips into a desired shape may result in an unstable flow direction of the chips.
Specifically, the chips may fail to flow toward the flute and may instead flow in a direction toward the outer peripheral direction (direction toward the outer portion) of the drill bit, and thus may damage a process surface (inner wall of the hole drilled) of the workpiece.
The cutting insert according to an aspect of the present disclosure is configured to facilitate the flow of the chips toward the flute.
Details of the insert 1 will be described using
These lines V-V, VI-VI, and VII-VII in
As illustrated in
The cutting edge 11 may include a chisel edge 16 extending toward the outer peripheral of the cutting portion 10 from the position of the rotational axis R1 (that is, position of the first end 10A), a thinning edge 17 extending toward the outer peripheral from the chisel edge 16, and a main cutting edge 18 extending toward the outer peripheral from the thinning edge 17. The cutting portion 10 may have a thinning surface 70 extending from the thinning edge 17 toward the second end 3A (the second end 3A side).
The rake face 80 extends from the main cutting edge 18 toward the second end 3A, and curls chips produced by the cutting edge 11. The chips curled with the rake face 80 flow toward the flute 90. The rake face 80 may include a first surface region 81, a second surface region 82, a third surface region 83, and a fourth surface region 84.
As illustrated in
The second surface region 82 is connected to the first surface region 81, positioned closer to the second end 3A than the first surface region 81, and connected to the third surface region 83, the fourth surface region 84, and the flutes 90. The second surface region 82 is inclined with respect to the first surface region 81. A boundary 12 between the second surface region 82 and the first surface region 81 may extend and be inclined toward the second end 3A as getting closer to the outer peripheral of the main body 2 in side view.
The second surface region 82 may be a surface having a shape (concavely curved shape) slightly convexly curved downward in a cross-section orthogonal to the rotational axis RE The second surface region 82 may be a surface having a linear shape in a direction along the rotational axis R1, or may be a surface having a shape convexly curved downward.
The third surface region 83 is positioned closer to the second end 3A than the second surface region 82, and is adjacent to the flute 90 rearward in the rotational direction about the rotational axis R1 and on the side close to the outer peripheral of the main body 2. In other words, the third surface region 83 is a portion defined by the second surface region 82, the flute 90, and a ridge L1 positioned at the intersection between the rake face 80 and the outer peripheral surface of the main body 2.
The third surface region 83 is inclined with respect to the second surface region 82. In side view of the main body 2, a boundary 23 between the second surface region 82 and the third surface region 83 may extend to pass through an end portion of the flute 90 closest to the first end 10A, and to be orthogonal to the rotational axis RE The third surface region 83 may have a smaller rake angle than the second surface region 82 as will be described in detail below. Thus, an end portion of the chips produced by the cutting edge 11 in the width direction is likely to come into contact with the third surface region 83.
The fourth surface region 84 is positioned closer to the second end 3A than the second surface region 82, and is adjacent to the flute 90 frontward in the rotational direction about the rotational axis RE The fourth surface region 84 is inclined with respect to the second surface region 82. The fourth surface region 84 is connected to a contact surface 20 that comes into contact with a fix claw 105 (see
The flute 90 is positioned closer to the second end 3A than the second surface region 82. The boundary between the flute 90 and the rake face 80 is referred to as a boundary 98. The flute 90 may have a helical shape toward the rear in a rotational direction R2 as getting closer to the second end 3A. In this case, a ridge is formed at the boundary between the flute 90 and the rake face 80, and thus this ridge serves as the boundary 98. The flute 90 may have a concavely curved shape in a cross section orthogonal to the rotational axis R1 for the sake of smooth discharging of the chips, flowing from the rake face 80, toward the second end 3A side.
In the insert 1 of the present example, as illustrated in
The rake angles can be defined in cross sections (for example, cross sections taken along lines V-V, VI-VI, and VII-VII illustrated in
For example, when the slope of the line of the first surface region 81 is constant (the first rake angle θ1 is constant) in the cross section illustrated in
On the other hand, for example, the slope of the line of the first surface region 81 may not be constant in the cross section illustrated in
The values of the respective rake angles of the first surface region 81 to the third surface region 83 are compared in the same cross section. This is because, for example, the absolute value of the first rake angle θ1 may vary among the plurality of cross sections illustrated in
In the cross sections illustrated in
The definition of the rake angle and the rule for comparison between a plurality of rake angles similarly apply to the second rake angle θ2 and the third rake angle θ3.
In the insert 1 of the present example, the second rake angle θ2 is smaller than the first rake angle θ1, and the third rake angle θ3 is smaller than the second rake angle θ2. This expression “the third rake angle θ3 is smaller than the second rake angle θ2” includes a case where the second rake angle θ2 is a positive value and the third rake angle θ3 is a negative value.
A difference between the first rake angle θ1 and the second rake angle θ2 may be about 1°, or may be in a range from 0.3° to 10°, both inclusive, for example. A difference between the second rake angle θ2 and the third rake angle θ3 may be about 1°, or may be in a range from 0.3° to 10°, both inclusive, for example. About 1° means 1°±0.1°.
The insert 1 of the present example provides the following effects. Specifically, when the insert 1 comes into contact with the workpiece while rotating about the rotational axis R1, the workpiece is cut and processed by the cutting edge 11, thus forming chips of the workpiece along the cutting edge 11. As illustrated in
Furthermore, of the chips, those in the vicinity of the outer peripheral of the insert 1 advance to the first surface region 81, the second surface region 82, and the third surface region 83 in this order. With the rake angle varying to gradually decrease from the first surface region 81 to the third surface region 83 as illustrated in
In this case, a brake is applied to the chips advancing, thereby causing curling of the chips at the rake face 80. On the other hand, the chips are likely to advance more smoothly in the flute 90 than at the rake face 80, because the flute 90 has a helical shape toward the rear in the rotational direction R2 as getting closer to the second end 3A.
As described above, the third surface region 83 is adjacent to the flute 90 rearward in the rotational direction about the rotational axis R1 and on the side close to the outer peripheral of the main body 2. Thus, in the insert 1 of the present example, the chips are likely to be twisted in a portion around the outer peripheral of the insert 1. Thus, the chips are less likely to jump out from the insert 1, and are likely to flow toward the flute 90.
In particular, in the insert 1 of the present example, the second rake angle θ2 is smaller than the first rake angle θ1, and the third rake angle θ3 is smaller than the second rake angle θ2. Thus, a large angle is likely to be formed between the third surface region 83 and the flute 90, whereby the twisting of the chips in the portion around the outer peripheral of the insert 1 is further facilitated.
In other words, the insert 1 of the present example can be regarded having the following configuration.
The main body 2 includes the rake face 80 extending from the cutting edge 11 toward the second end 3A and the flute 90 extending from the rake face 80 toward the second end 3A. A region of the flute 90 on the side of the first end 10A has a shape convex toward the rake face 80. Thus, the boundary 98 between the rake face 80 and the flute 90 has a shape convex toward the first end 10A (side of the first end 10A).
The rake angle of the rake face 80 is smaller at a portion as separating from the cutting edge 11. A rake angle in a region (third surface region 83) of the rake face sandwiched between the flute 90 and the ridge L1 is smaller than a rake angle in a region (the first surface region 81 and the second surface region 82) closer to the first end 10A than the flute 90 in the rake face.
The main body 2 may further include the contact surface 20. The contact surface 20 may be positioned frontward in the rotational direction R2 with respect to the flute 90, and may come into contact with the holder 102 when the insert 1 is attached to the holder 102 described below. A rake angle in a region (fourth surface region 84) of the rake face between the flute 90 and the contact surface 20 may be smaller than a rake angle in a region (the first surface region 81 and the second surface region 82) closer to the first end 10A than the flute 90 is in the rake face.
The insert 1 may have a shape with the boundary 98 between the rake face 80 and the flute 90 protruding toward the first end 10A in side view. In other words, the boundary 98 may be convex toward the first end 10A (side of the first end 10A). Part of the flute 90 protruding toward the first end 10A side is referred to as a protruding groove part 91. With this configuration, the distance from the main cutting edge 18 to the flute 90 can be made short. Thus, the chips, flowing in a portion of the boundary 98 serving as the boundary between the second surface region 82 and the flute 90 (in other words, the chips flowing between the third surface region 83 and the fourth surface region 84), can easily flow toward the flute 90.
In the insert 1, in a cross section (cross section illustrated in
With this configuration, the dischargeability of the chips is improved. The chips flowing from the rake face 80 to the flute 90 are likely to flow in a biased manner rearward in the rotational direction R2 of the rake face 80 and the flute 90. Since the flute 90 is biased rearward in the rotational direction R2 of the rake face 80 and the flute 90, the chips thus flowing are likely to flow to the flute 90.
As illustrated in
In the insert 1, in a first cross section (the cross section illustrated in
This configuration facilitates reduction of the area of contact between the chips and the flute 90 when the chips flow from the rake face 80 to the flute 90. Specifically, when the chips flow from the rake face 80 to the flute 90, at least part of the chips is likely to flow while being separated from the flute 90. Thus, the dischargeability of the chips is improved, while reducing the chance of the flute 90 wearing.
In other words, the insert 1 of the present example can be regarded having the following configuration.
The main body 2 includes the rake face 80 extending from the cutting edge 11 toward the second end 3A and the flute 90 extending from the rake face 80 toward the second end 3A. A region of the flute 90 on the side of the first end 10A has a shape convex toward the rake face 80. Thus, the boundary 98 between the rake face 80 and the flute 90 has a shape convex toward the first end 10A.
The rake angle of the rake face 80 is smaller at a portion as separating from the cutting edge 11. A rake angle in a region (third surface region 83) of the rake face sandwiched between the flute 90 and the ridge L1 is smaller than a rake angle in a region (the first surface region 81 and the second surface region 82) closer to the first end 10A than the flute 90 in the rake face.
The main body 2 may further include the contact surface 20. The contact surface 20 may be positioned frontward in the rotational direction R2 with respect to the flute 90, and may come into contact with the holder 102 when the insert 1 is attached to the holder 102 described below. A rake angle in a region (fourth surface region 84) of the rake face between the flute 90 and the contact surface 20 may be smaller than a rake angle in a region (the first surface region 81 and the second surface region 82) closer to the first end 10A than the flute 90 in the rake face. [0060] 4. Surface Region of Rake Face
Whether the rake face 80 has the first surface region 81, the second surface region 82, and the third surface region 83 may be evaluated through the following procedure.
In the cross section described above, part of the rake face 80 that is positioned on the second end 3A side and is sandwiched between the flute 90 and the ridge L1 is defined as the third surface region 83. The rake angle at part of the third surface region 83 connected to the flute 90 is defined as the third rake angle θ3.
When a surface region is present between the first surface region 81 and the third surface region 83, with a rake angle smaller than the first rake angle θ1 and larger than the third rake angle θ3, this surface region may be regarded as the second surface region 82.
Whether the rake face 80 has the first surface region 81, the second surface region 82, and the fourth surface region 84 may be evaluated through the following procedure.
When a surface region is present between the first surface region 81 and the fourth surface region 84, with a smaller rake angle than the first rake angle θ1, this surface region may be regarded as the second surface region 82.
A rotary tool 100 of one non-limiting example of the present disclosure will be described with reference to
As illustrated in
While the rotary tool 100 of the present example is a single-chip type drill to which one insert 1 is attached, but the rotary tool including the insert 1 is not limited to the single-chip type drill. The rotary tool is not limited to a drill that performs drilling by moving in the direction of the rotational axis R1 relative to the workpiece, and may be a tool that can rotate and cut the workpiece by moving in any direction while rotating. Examples of the rotary tool including the insert 1 include an endmill, and a milling tool.
The holder 102 may include a shank 103 and a body 104 extending along the rotational axis R1. The shank 103 may have a rod shape extending along the rotational axis R1, and is a portion held by a machine tool for example.
The body 104 has a side surface provided with a flute 110 formed in a helical shape for discharging chips from a workpiece T.
The body 104 includes the pocket 111 opening on the leading end side. The shaft portion 3 of the insert 1 is attached to the pocket 111. The insert 1 is attached to the holder 102 (body 104), for example, using a screw (not illustrated).
The body 104 has the leading end, on the insert 1 side, provided with a fix claw 105 with which the insert 1 can be fixed. One of a plurality of surfaces of the fix claw 105 comes into contact with the contact surface 20 of the insert 1. The flute 110 is connected to the flute 90 of the insert 1.
Method for Manufacturing Machined Product
Description will be given of a method for manufacturing a machined product according to an example by using
The method for manufacturing the machined product U according to one embodiment of the present disclosure may include the following steps. Specifically, the steps may include:
More specifically, first of all, as indicated by the reference numeral 1301 in
As indicated by the reference numeral 1302 in
Then, as indicated by the reference numeral 1303 in
Variation
In the present disclosure, the invention has been described above based on the various drawings and examples. However, the invention according to the present disclosure is not limited to each embodiment described above. That is, the embodiments of the invention according to the present disclosure can be modified in various ways within the scope illustrated in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, note that a person skilled in the art can easily make various variations or modifications based on the present disclosure. Note that these variations or modifications are included within the scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-162137 | Sep 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/035635 | 9/28/2021 | WO |
