An aspect relates to a rotary tool such as an end mill or a drill used in machining and to a method for manufacturing a machined product.
Drills such as a drill described in JP H09-277108 A (Patent Document 1) have been used for machining workpieces such as a metal member. The drill described in Patent Document 1 may include a helical groove through which the generated chips pass. The helical groove may include a leading end portion having a constant helix angle, an intermediate portion in which a helix angle gradually decreases from a leading end to a rear end, and a rear end portion having a constant helix angle that is less than the helix angle of the leading end portion. The length of the leading portion may be from 1 D to 2 D, the length of the intermediate portion may be from 1 D to 3 D, and the length of the rear end portion may be appropriately set depending on the depth of a hole to be machined.
In the drill described in Patent Document 1, in a case that the depth of the hole to be machined is deep, the length occupied by the rear end portion with respect to the entire length of a body may increase. In addition, a region where the helix angle is relatively small may be increased with respect to the entire length of the helical groove. As a result, chips may become stuck on the rear end side where the helix angle is relatively small.
A rotary tool according to a non-limiting aspect may include a body having a rod-like shape and extending along a rotation axis from a first end toward a second end. The body may include a cutting edge located at the first end, and a first groove extending in a spiral manner from the cutting edge toward the second end. The first flute may include a first region having a first helix angle, a second region located closer to the second end than the first region and having a second helix angle, a third region located closer to the second end than the second region and having a third helix angle, a fourth region located between the first region and the second region and having a fourth helix angle, and a fifth region located between the second region and the third region and having a fifth helix angle.
In a rotary tool according to a non-limiting aspect, the second helix angle may be less than the first helix angle and greater than the third helix angle. The fourth helix angle and the fifth helix angle may each decrease from a side of the first end toward the second end. A decreasing range of a value of the fourth helix angle may be less than a decreasing range of a value of the fifth helix angle. A length of the fourth region in a direction along the rotation axis may be greater than a length of the fifth region in a direction along the rotation axis.
The following describes in detail a cutting tool of various non-limiting embodiments using the drawings. However, for convenience of explanation, each of the drawings referenced below is simplified to illustrate only the main members of the constituent members of the various non-limiting embodiments. Accordingly, the cutting tool described below may be provided with any constituent member which is not illustrated in each of the referred drawings. Further, 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.
The cutting tool according to the various non-limiting embodiments below may be a drill. The drill represents a rotary tool. In addition to the drill, examples of the rotary tool may include an end mill and a reamer.
A rotary tool 1 (drill 1) of an example illustrated in
The body 3 of the example illustrated in
The body 3 of the example illustrated in
The cutting portion 11 may have, for example, a cylindrical shape that extends along the rotation axis X and may have a missing portion that defines the flute 7, as illustrated in
The drill 1 is not limited to a particular size. The outer diameter of the cutting portion 11 may be set to from 6 mm to 42.5 mm, for example. The drill 1 may also be set to satisfy L=from 8 D to 20 D, for example, where L may be the length of the axis line (length of the cutting portion 11), and D may be the outer diameter of the cutting portion 11.
Examples of the material of the body 3 may include a cemented carbide alloy that contains tungsten carbide (WC) and cobalt (Co) as a binder, an alloy that may include this cemented carbide alloy and an additive such as titanium carbide (TiC) or tantalum carbide (TaC) added thereto, or a metal such as stainless steel and titanium.
Next, a description will be given of the cutting edge 5. The cutting edge 5 may be located at the leading end of the body 3 and may be used as a portion for cutting the workpiece. The cutting edge 5 of an example illustrated in
The sub cutting edge 5b in the example illustrated in
The pair of main cutting edges 5a of the example illustrated in
The main cutting edge 5a in the example illustrated in
The pair of main cutting edges 5a in the example illustrated in
Next, a description will be given of the flutes 7. The pair of flutes 7 in the example illustrated in
In the example illustrated in
The pair of flutes 7 may be mainly intended to discharge chips generated by the pair of main cutting edges 5a and the sub cutting edge 5b to the outside. When machining, chips generated by one of the pair of main cutting edges 5a may be discharged to the rear end side of the body 3 through the flute 7 connected to the main cutting edge 5a, out of the pair of flutes 7. In addition, the chips generated by the remaining one (the other side) of the pair of main cutting edges 5a may be discharged to the rear end side of the body 3 through the flute 7 connected to the other main cutting edge 5a, out of the pair of flutes 7.
At this time, one of the pair of flutes 7 may be formed so as to overlap with the other of the pair of flutes 7 in a case that the other flute 7 is rotated by 180° around the rotation axis X. In this case, chips generated in each of the pair of main cutting edges 5a can be made to flow well through a corresponding flute 7.
The flute 7 in examples illustrated in
In one example illustrated in
In the example illustrated in
In an example illustrated in
The second helix angle θ2 may have only to be less than the first helix angle θ1, and the third helix angle θ3 may have only to be less than the second helix angle θ2. The first helix angle θ1 may be approximately from 26 to 30°, for example, the second helix angle θ2 may be set to approximately from 25 to 29°, for example, and the third helix angle θ3 may be set to approximately from 10 to 15°, for example.
In the example illustrated in
The constant helix angle does not mean that the helix angle is strictly constant from the leading end side toward the rear end side in a target region, but may also have variation of about 5% in helix angle in the target region.
In the example illustrated in
At this time, the decrease amount of the fourth helix angle θ4 may correspond to the difference between the first helix angle θ1 and the second helix angle θ2, and the decrease amount of the fifth helix angle θ5 may correspond to the difference between the second helix angle θ2 and the third helix angle θ3.
The decrease rate of the fourth helix angle θ4 in the fourth region 24 and the decease rate of the fifth helix angle θ5 in the fifth region 25 may be constant or gradually vary. In a case that the decrease rate of the fourth helix angle θ4 in the fourth region 24 and the decrease rate of the fifth helix angle θ5 in the fifth region 25 are each constant, chip discharge performance may be improved.
In a case that the flute 7 includes the first region 21, the second region 22, the third region 23, the fourth region 24, and the fifth region 25 that have the configuration described above, the flute 7 may have a configuration in which the closer to the leading end of the body 3, the greater is the helix angle. This provides a great force for pushing chips out, thereby improving chip discharge performance. Additionally, the closer to the rear end of the body 3 in the flute 7, the smaller is the helix angle, so the strength of the portion toward the rear end of the flute 7 may be great.
Further, in a case that the fourth region 24, which is longer in the direction along the rotation axis X than the fifth region 25, is located on the rear end side of the first region 21 having a relatively great helix angle, chips may easily pass from the first region 21 to the second region 22, thereby improving chip discharge performance. In particular, in a case that the first region 21 and the second region 22 are connected by the fourth region 24, chip discharge performance may be further improved.
In a case where the fifth region 25, which is shorter in length in the direction along the rotation axis X than the fourth region 24, is located on the leading end side of the third region 23 having a relatively less helix angle, chips can be transferred from the second region 22 to the third region 23 having the least helix angle at the shortest distance. As a result, the rigidity of the portion toward the rear end of the flute 7 can be improved. Since the body 3 has great rigidity, it is possible to not only use the rotary tool 1 in a process for forming a hole with a great depth, but also exhibit high chip discharge performance.
In the present disclosure, the helix angle may refer to an angle formed by the leading edge (leading edge of land) and an imaginary straight line parallel to the rotation axis X, as illustrated in
If it is difficult to perform evaluation by the leading edge, the line of intersection formed by the flute 7 and the land 13 (specifically, heel) located frontward from the flute 7 in the rotation direction Y of the rotation axis X may be identified, and the angle formed by the line of intersection and the imaginary straight line that passes parallel to the rotation axis X through one point on the line of intersection may be evaluated as the helix angle.
Furthermore, in the present disclosure, the length of each of the regions (the first region 21 to the fifth region 25) in the direction along the rotation axis X is the length of each of the regions in the direction parallel to the rotation axis X, and as illustrated in
In the drill 1 of the present disclosure, the length L4 of the fourth region 24 and the length L5 of the fifth region 25 with respect to the entire length of the flute 7 in a direction parallel to the rotation axis X may have only to satisfy the relationship described above. For example, the length L4 can be set to approximately from 0.9 D to 1.5 D, and the length L5 can be set to approximately from 0.7 D to 1.4 D. In addition, the length L1 of the first region 21, the length L2 of the second region 22, and the length L3 of the third region 23 can be set to, for example, approximately from 0.9 D to 1.5 D, approximately from 4 D to 8 D, and approximately from 1 D to 10 D, respectively, with respect to the entire length of the flute 7 in a direction parallel to the rotation axis X.
The flute 7 in the example illustrated in
As illustrated in
On the other hand, as illustrated in
As illustrated in the example illustrated in
In a case that the second region 22 is configured as described above, the second portion 22b, which is relatively wide in the second region 22, may be located away from the fourth region 24. The fourth helix angle θ4 changes in the fourth region 24. As a result, in the fourth region 24, the outflow direction of the chips tends to be unstable. However, the width of the first portion 22a located on the leading end side of the second region 22 may be relatively narrow. This makes the outflow direction of the chips stable in the first portion 22a even in a case where the chips pass through the fourth region 24 in a state in which the outflow direction is unstable.
In addition, in a case that the second region 22 may include the second portion 22b having a relatively large width, friction between the chips and the flute 7 can be reduced, and chips, whose outflow direction is stable, can be discharged more smoothly. In particular, in a case that machining is performed by use of a coolant, the space between the chips and the inner wall of the flute 7 may be more likely to be large in the second portion 22b, which is relatively wide. This makes it possible to pass the coolant easily and discharge chips more easily.
In a case that the second region 22 includes the first portion 22a and the second portion 22b, the lengths of the first portion 22a and the second portion 22b in the direction along the rotation axis X may not be particularly limited to specific lengths. However, in a case that the length of the second portion 22b in the direction along the rotation axis X is greater than the length of the first portion 22a in the direction along the rotation axis X, the chips may be more easily discharged.
Further, as illustrated in the cross-sectional view orthogonal to the rotation axis X of
In the case the second portion 22b has a shape in which the two second concave curved line portions (R2A, R2B) are connected as described above, the two second concave curved line portions (R2A, R2B) may form arcs having the same radius of curvature in a cross section orthogonal to the rotation axis X. According to such a configuration, chips may be less likely to be clogged, and the flow of chips can be made smoother. Also in manufacturing the drill 1, in the case that the two second concave curved line portions (R2A, R2B) form arcs having the same radius of curvature, the two second concave curved line portions (R2A, R2B) may be formed at the same processing conditions. Therefore, manufacturing of the drill 1 may be facilitated.
The same radius of curvature does not require that the radius of curvature is exactly the same. There may be some difference of approximately 5% in the radius of curvature between the two second concave portions (R2A, R2B).
As illustrated in an example illustrated in
The region of the flute 7 located closer to the rear end than the second region 22 may have two concave curved line portions in a cross section orthogonal to the rotation axis X, such as the second portion 22b. That is, the second portion 22b, the fifth region 25, and the third region 23 of the flute 7 may have two concave curved line portions in a cross section orthogonal to the rotation axis X. According to the example illustrated in
Here, the two concave curved line portions in the third region 23 may be referred to as a third concave curved line portion R3A and a third concave curved line portion R3B. In an example illustrated in
As illustrated in the example illustrated in
Also, as examples illustrated in
Here, “the maximum value of the groove depth V in each region is the same” does not mean that each of the regions has exactly the same maximum value of the groove depth, but may have variations of approximately 5% in the maximum value of the groove depth V.
The depths V1 to V5 of the first region 21 to fifth region 25 may be constant from the leading end side to the rear end side. Here, the constant depth V of each region does not mean that the depth is strictly constant from the leading end side to the rear end side, and the depth V of each region may vary by approximately 5%.
The depth V of the flute 7 may be set to, for example, approximately from 10 to 40% with respect to the outer diameter of the cutting portion 11. The depth V of the flute 7 refers to a value obtained by subtracting a distance between a bottom of the flute 7 and the rotation axis X from a radius of the body 3 in the cross section orthogonal to the rotation axis X as illustrated in
That is, a web thickness indicated by a diameter of an inscribed circle in the cross section orthogonal to the rotation axis X at the body 3 may be set to from 20 to 80%, for example, with respect to the outer diameter of the cutting portion 11. Specifically, for example, in a case where the outer diameter D of the cutting portion 11 may be 20 mm, the depth V of the flute 7 can be set to approximately from 2 to 8 mm.
The groove depth V1 in the first region 21 may be reduced on the leading end side of the body 3. That is, the groove depth V1 of the first region 21 may increase from the leading end side toward the rear end side. In this case, in the first region 21, chips generated by the cutting edge 5 can be curled on the leading end side where the groove depth is relatively shallow such that the diameter of the curls is small, and then the chips can be discharged through the inside of the flute 7 more smoothly toward the rear end of the body 3.
Furthermore, as illustrated in the example illustrated in
Next, a method for manufacturing a machined product according to a non-limiting embodiment will be described in detail using the drill 1 described above as an example. Below, a description will be given with reference to
The method for manufacturing a machined product of an example illustrated in
(1) A step of arranging the drill 1 above a prepared workpiece 101 (refer to
(2) A step of rotating the drill 1 in a direction of the arrow Y around the rotation axis X and bringing the drill 1 toward the workpiece 101 in a direction Z1 (refer to
(3) A step of bringing the drill 1 closer to the workpiece 101 and causing the drill 1 that is rotating to come into contact with a desire position on a surface of the workpiece 101 to form a machined hole 103 (through-hole) in the workpiece 101 (refer to
(4) A step of separating the drill 1 from the workpiece 101 in a Z2 direction (refer to
The step (2), for example, may be performed by fixing the workpiece 101 on a table of the machine tool having the drill 1 installed thereto and bringing the drill 1 close to the workpiece 101 while rotating the drill 1. In the step (1), the workpiece 101 and the drill 1 may be brought relatively close to each other, or the workpiece 101 may be brought close to the drill 1.
In the step (3), the entire cutting portion of the drill 1 may be inserted into the workpiece 101, or a portion of the cutting portion of the drill 1 on the rear end side does not need to be inserted into the machined hole 103. In a case where a portion of the cutting portion of the drill 1 on the rear end side is not inserted into the machined hole 103, a part of region of the cutting portion on the rear end side can function as a region for discharging chips. This makes it possible to provide excellent chip discharge performance with the part of region.
In the step (4) as well, similar to the step (2) above, the workpiece 101 and the drill 1 may be relatively separated from each other, or the workpiece 101 may be separated from the drill 1, for example.
Through such steps (1) to (4) as described above, the machined product including the machined hole 103 can be obtained.
Here, when machining the workpiece 101 as described above may be carried out a plurality of times, and, for example, a plurality of machined holes 103 are formed in one workpiece 101, the bringing the cutting edge of the drill 1 into contact with a different location of the workpiece 101 may be repeated with the drill 1 being rotated.
Various aspects of the drill 1 may be described above. However, the drill according to the present non-limiting embodiments is not limited thereto, and, needless to say, the drill may have any configuration without departing from the spirit of the present invention.
For example, the drill 1 is described as the cutting tool according to an example of a non-limiting embodiment, but it is possible to use an end mill or reamer to which the gist of the present invention may have been applied. Furthermore, the cutting portion 11 may have a configuration in which the portion including the leading end is detachable with respect to the portion on the rear end side, or the cutting portion 11 may be constituted only by one member.
Number | Date | Country | Kind |
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2016-222026 | Nov 2016 | JP | national |
This application is a national stage entry according to 35 U.S.C. 371 of PCT Application No. PCT/JP2017/040793 filed on Nov. 13, 2017, which claims priority to Japanese Application No. 2016-222026 filed on Nov. 15, 2016, which are entirely incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2017/040793 | 11/13/2017 | WO | 00 |