JP7023263B2 - Rotary cutting tool - Google Patents

Description

The present invention relates to a rotary cutting tool in which a tip made of an ultra-hard material is fixed to the tip of a shaft-shaped shank.

Conventionally, a rotary cutting tool in which a tip made of an ultra-hard material is fixed to the tip of a shaft-shaped shank has been known. When the workpiece is machined using such a rotary cutting tool, the chips cut by the cutting edge curl and extend in the direction away from the rake face. However, if the chips extend for a long time, the chips may get entangled with the rotary cutting tool, or the chips may get caught in the cutting edge and the machined surface may be roughened. Therefore, miniaturization of chips is required. In particular, when processing an aluminum alloy workpiece, miniaturization of chips is strongly required. Therefore, Patent Document 1 describes a rotary cutting tool in which the cutting edge is rounded. In this rotary cutting tool, the chips generated at the cutting edge portion are broken as soon as they are generated, that is, in a very short time, due to the action of the rounded portion. As a result, the chips are made finer.

Japanese Unexamined Patent Publication No. 2006-281411

The rotary cutting tool described in Patent Document 1 can make chips finer, but has a problem that the shape of the cutting edge is changed by rounding the cutting edge and the sharpness is deteriorated. This causes a problem that the processing speed is lowered and the processing accuracy is lowered.

Therefore, an object of the present invention is to provide a rotary cutting tool capable of miniaturizing chips without changing the shape of the cutting edge and maintaining cutting performance and machining accuracy.

As a result of diligent studies on the above problems, the present inventors have found that the chips are miniaturized by forming a rough surface region in the vicinity of the cutting edge on the rake surface. The present invention has been made based on such findings.

That is, the rotary cutting tool according to the present invention is a rotary cutting tool in which a tip is fixed to the tip of a shaft-shaped shank, and the tip has a cutting edge and a rake surface extending from the cutting edge, and is a rake. A roughened rough surface region is formed in the vicinity of the cutting edge on the surface.

In this rotary cutting tool, when the workpiece is rotated and cut, the chips cut by the cutting edge are pressed into the rough surface region while curling in the direction away from the rake surface. At this time, a large frictional resistance is generated between the chips and the rough surface region, causing a difference between the chip generation speed and the chip speed flowing on the rough surface region, and the chips are distorted. By generating it, the chips are broken and made finer. As a result, chips can be miniaturized without changing the shape of the cutting edge, and cutting performance and machining accuracy can be maintained. Moreover, when the chips are pressed against the rough surface region, a part of the chips is welded to the rough surface region, so that the frictional resistance generated between the chips and the rough surface region increases. This further promotes the miniaturization of chips.

The arithmetic mean height Sa of the rough surface region may be 0.1 μm or more and 5 μm or less. In this rotary cutting tool, the arithmetic mean height Sa of the rough surface region is 0.1 μm or more and 5 μm or less, so that sufficient frictional resistance can be generated between the chips and the rough surface region and cutting. It is possible to suppress the frictional resistance generated between the powder and the rough surface region and the excessive deposition of chips welded to the rough surface region.

The distance from the cutting edge to the tip of the rough surface region on the cutting edge side may be 10 μm or more and 100 μm or less. In this rotary cutting tool, the distance from the cutting edge to the tip of the rough surface region on the cutting edge side is 10 μm or more and 100 μm or less, so that the rough surface region does not affect the shape of the cutting edge while cutting appropriately. The powder can be pressed against the rough surface region.

The rough surface region may extend in a direction parallel to the cutting edge. In this rotary cutting tool, since the rough surface region extends in the direction parallel to the cutting edge, the rough surface region can be easily formed and chips can be appropriately pressed against the rough surface region. ..

The rough surface area does not have to extend to the edge of the rake face. In this rotary cutting tool, the rough surface region does not extend to the edge of the rake face, so the rough surface region directly contacts the workpiece, for example, when a land is formed on the edge of the rake face. It is possible to suppress the deterioration of the processing accuracy by suppressing the processing.

A plurality of rough surface regions may be formed on the rake surface in a direction perpendicular to the cutting edge. In this rotary cutting tool, since a plurality of rough surface regions are formed on the rake surface in the direction perpendicular to the cutting edge, the chips can be divided into a plurality of times and pressed against the rough surface region. This makes it possible to generate sufficient frictional resistance between the chips and the rough surface region while suppressing the local increase in the welded material of the chips.

The distance between the plurality of rough surface regions may be 8 μm or more and 100 μm or less. In this rotary cutting tool, since the distance between the plurality of rough surface regions is 8 μm or more and 100 μm or less, the frictional resistance generated between the chips and the rough surface regions is suppressed from becoming excessive, and the chips are removed. , It is possible to press-contact not only one rough surface region but also a plurality of rough surface regions.

The width of the rough surface region in the direction perpendicular to the cutting edge may be 10 μm or more and 200 μm or less. In this rotary cutting tool, the width in the direction perpendicular to the cutting edge of the rough surface region is 10 μm or more and 200 μm or less, so that sufficient frictional resistance can be generated between the chips and the rough surface region. It is possible to suppress the frictional resistance generated between the chips and the rough surface region and the excessive amount of the welded material of the chips welded to the rough surface region.

The rough surface region may be formed by a groove formed in the rake surface. In this rotary cutting tool, since the rough surface region is formed by the grooves formed on the rake surface, the rough surface region can be easily formed. Moreover, by accumulating the welded chips of chips in the grooves, sufficient frictional resistance can be generated between the chips and the rough surface region.

The depth of the groove may be 1 μm or more and 20 μm or less. In this rotary cutting tool, since the groove depth is 1 μm or more and 20 μm or less, sufficient frictional resistance can be generated between the chips and the rough surface region, and the chips and the rough surface region can be generated. It is possible to suppress the frictional resistance generated between them and the excessive amount of welded chips of chips welded to the rough surface region.

According to the present invention, chips can be miniaturized without changing the shape of the cutting edge, and cutting performance and machining accuracy can be maintained.

It is a front view which shows an example of the rotary cutting tool which concerns on this embodiment. It is a perspective view which shows an example of a chip. It is a front view which shows a part of the chip shown in FIG. It is an enlarged view which magnified a part of the chip shown in FIG. It is a front view which shows a part of the chip of the modification. It is a front view which shows a part of the chip of the modification. It is a front view which shows a part of the chip of the modification. It is sectional drawing of an example in the line VIII-VIII shown in FIG. It is a perspective view which shows an example of a cutting tool. It is a table which shows the measurement result of Example 1 and Comparative Example 1. It is a photograph of chips when the feed amount f is 0.05 [mm / rev] in Example 1. It is a photograph of chips when the feed amount f is 0.1 [mm / rev] in Example 1. It is a photograph of chips when the feed amount f is 0.2 [mm / rev] in Example 1. It is a photograph of chips when the feed amount f is 0.4 [mm / rev] in Example 1. It is a photograph of chips when the feed amount f is 0.05 [mm / rev] in Comparative Example 1. It is a photograph of chips when the feed amount f is 0.1 [mm / rev] in Comparative Example 1. It is a photograph of chips when the feed amount f is 0.2 [mm / rev] in Comparative Example 1. It is a photograph of chips when the feed amount f is 0.4 [mm / rev] in Comparative Example 1.

Hereinafter, the rotary cutting tool according to the embodiment will be described with reference to the drawings. In each figure, the same or corresponding elements are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 1, the rotary cutting tool 1 according to the present embodiment is a cutting tool such as a reamer, a drill, an end mill, etc. for drilling or milling a workpiece by being rotationally driven. In the following, as an example, the rotary cutting tool 1 will be described as being a reamer.

The rotary cutting tool 1 includes a shaft-shaped shank 2 and one or a plurality of tips 3 fixed to the tip of the shank 2.

The shank 2 is a flat-headed shank with a flat tip. The shank 2 is formed with one or a plurality of chip discharge grooves 4 extending in the axis A direction of the shank 2. The drawing shows a case where two chip discharge grooves 4 are formed in the shank 2.

As shown in FIGS. 1 to 3, the chip 3 includes a diamond sintered body (PCD: Polycrystalline Diamond), a single crystal diamond (for example, natural diamond, synthetic diamond), and a cubic boron nitride sintered body (PCBN: Polycrystalline Cubic). It is made of ultra-hard material such as Boron Nitride), which has extremely high strength and wear resistance. The tip 3 is fixed to the chip discharge groove 4 so as to protrude from the tip of the shank 2. When a plurality of chip discharge grooves 4 are formed, the tip 3 is fixed to each of the plurality of chip discharge grooves 4.

The insert 3 has a cutting edge 31 for cutting a workpiece, a rake surface 32 extending from the cutting edge 31, and a land 33 extending from the cutting edge 31 along the outer peripheral surface of the shank 2 in the axis A direction of the shank 2. And have. The cutting edge 31 is formed on the tip edge of the tip 3. In the present embodiment, the cutting edge 31 extends to the outer portion of the tip of the tip 3 in the radial direction of the shank 2 in a direction inclined with respect to the axis A of the shank 2.

By the way, as a result of diligent studies on the miniaturization of chips, the present inventors have found that the chips are miniaturized by forming a rough surface region in the vicinity of the cutting edge on the rake face. The reason is not clear, but the present inventors infer as follows.

That is, when the tip of the rotary cutting tool that had been drilled was observed with a microscope, a part of the chips was welded to the rake face of the tip, and the welded material of this chips was near the cutting edge on the rake surface. I was concentrating on. This means that the chips are once pressed against the rake face in the vicinity of the cutting edge and then move away from the rake face. Therefore, the present inventors increase the frictional resistance in the vicinity of the cutting edge to which the chips are pressure-welded to cause a difference between the chip generation rate and the chip flow rate on the rake face. I thought that the chips might be broken and made finer by causing the strain. Based on this idea, when the vicinity of the cutting edge on the rake face was roughened and drilled, the chips cut by the cutting edge were finely broken and made finer. After that, when the chip was further observed with a microscope, the amount of welded chips was increased as compared with the case where the rake face was not roughened. From these results, roughening the vicinity of the cutting edge on the rake surface promotes the welding of chips and further increases the frictional resistance, which also promotes the miniaturization of chips. I thought it might be.

Based on such findings, in the present embodiment, a roughened rough surface region 34 is formed in the vicinity of the cutting edge 31 on the rake face 32. The rough surface region 34 is a region where the rake surface 32 is roughened, and the surface roughness of the rake surface 32 is coarser than that of the region other than the rough surface region 34. The vicinity of the cutting edge 31 on the rake face 32 is a region that does not include the cutting edge 31. That is, the rough surface region 34 is not formed on the cutting edge 31.

The arithmetic mean height Sa, which is the surface roughness of the rough surface region 34, is, for example, 0.1 μm or more and 5 μm or less. The arithmetic mean height Sa of the region other than the rough surface region 34 on the rake face 32 is, for example, 0.02 μm or more and less than 0.1 μm. When the arithmetic mean height Sa of the rough surface region 34 is 0.1 μm or more, sufficient frictional resistance can be generated between the chips and the rough surface region 34. On the other hand, when the arithmetic mean height Sa of the rough surface region 34 is 5 μm or less, it is possible to suppress the frictional resistance generated between the chips and the rough surface region 34 from becoming excessive, and it is possible to suppress the excessive frictional resistance. It is possible to prevent the welded material of the chips welded to the region 34 from becoming excessive. Since the rough surface region 34 is formed in the vicinity of the cutting edge 31, if the welded material becomes excessive, the welded material may extend to the cutting edge 31 and reduce the sharpness of the cutting edge 31. Therefore, it is preferable that the chips are welded to the rough surface region 34, but it is also preferable that the welded material is not excessive.

As shown in FIGS. 2 to 4, the rough surface region 34 is formed in the vicinity of the cutting edge 31 on the rake face 32. For example, the tip of the rough surface region 34 on the cutting edge 31 side is from the cutting edge 31. It means that it is in a position up to 100 μm. In this case, the distance B from the cutting edge 31 to the tip of the rough surface region 34 on the cutting edge 31 side can be, for example, 10 μm or more and 100 μm or less. When the distance B from the cutting edge 31 to the tip of the rough surface region 34 on the cutting edge 31 side is 10 μm or more, it is possible to suppress the rough surface region 34 from affecting the shape of the cutting edge 31. On the other hand, when the distance B from the cutting edge 31 to the tip of the rough surface region 34 on the cutting edge 31 side is 100 μm or less, the chips can be appropriately pressed against the rough surface region 34.

The rough surface region 34 extends in a direction parallel to the cutting edge 31. That is, the rough surface region 34 extends linearly in the direction parallel to the cutting edge 31. Since the rough surface region 34 extends in the direction parallel to the cutting edge, the rough surface region 34 can be easily formed and chips can be appropriately pressed against the rough surface region 34. However, the rough surface region 34 does not have to extend linearly, and may extend in a direction inclined with respect to the cutting edge 31. The length F in the direction parallel to the cutting edge 31 of the rough surface region 34 is not particularly limited, but may be substantially the same as the length G of the cutting edge 31, for example, and the length of the cutting edge 31. It may be shorter than G. Substantially the same means not only when they are exactly the same, but also tolerate a difference of about 3%.

The rough surface region 34 does not extend to the edge of the rake surface 32. That is, the rough surface region 34 does not extend to the land 33. Since the rough surface region 34 does not extend to the edge of the rake surface 32, the rough surface region 34 is not formed on the land 33, so that it is possible to suppress a decrease in the processing accuracy of the workpiece. However, as in the chip 3A shown in FIG. 5, the rough surface region 34 may extend to the edge of the rake surface 32. The chip 3A shown in FIG. 5 is the same as the chip 3 except that the rough surface region 34 extends to the edge of the rake surface 32.

As shown in FIGS. 2 to 4, two rough surface regions 34 are formed on the rake surface 32 in the direction perpendicular to the cutting edge 31. However, one rough surface region 34 may be formed on the rake face 32 in the direction perpendicular to the cutting edge 31, or two or more rough surface regions 34 may be formed. FIG. 6 shows a tip 3B in which one rough surface region 34 is formed on the rake face 32 in a direction perpendicular to the cutting edge 31, and FIG. 7 shows a direction perpendicular to the cutting edge 31 on the rake surface 32. The chip 3C in which four rough surface regions 34 are formed is shown. The chip 3B shown in FIG. 6 and the chip 3C shown in FIG. 7 are the same as the chip 3 except that the number of rough surface regions 34 is different. When one rough surface region 34 is formed on the rake face 32 in the direction perpendicular to the cutting edge 31, the rough surface region 34 can be easily formed. On the other hand, when a plurality of rough surface regions 34 are formed on the rake surface 32 in the direction perpendicular to the cutting edge 31, chips can be pressed into the rough surface region 34 in a plurality of times. As a result, sufficient frictional resistance can be generated between the chips and the rough surface region 34 while suppressing the local increase in the welded material of the chips.

As shown in FIGS. 2 to 4, when a plurality of rough surface regions 34 are formed on the rake surface 32 in the direction perpendicular to the cutting edge 31, the distance C between the plurality of rough surface regions 34 is, for example, 8 μm. It can be 100 μm or less. When the distance between the plurality of rough surface regions is 8 μm or more, it is possible to prevent the frictional resistance generated between the chips and the rough surface regions from becoming excessive. On the other hand, when the distance between the plurality of rough surface regions is 100 μm or less, the chips can be pressed into not only one rough surface region but also a plurality of rough surface regions.

The width D of the rough surface region 34 in the direction perpendicular to the cutting edge 31 can be, for example, 10 μm or more and 200 μm or less. When a plurality of rough surface regions 34 are formed on the rake face 32 in a direction perpendicular to the cutting edge 31, this width D is a width in a direction perpendicular to the cutting edge 31 of one rough surface region 34. When the width D in the direction perpendicular to the cutting edge 31 of the rough surface region 34 is 10 μm or more, sufficient frictional resistance can be generated between the chips and the rough surface region. On the other hand, when the width D in the direction perpendicular to the cutting edge 31 of the rough surface region 34 is 200 μm or less, it is possible to suppress the frictional resistance generated between the chips and the rough surface region 34 from becoming excessive. At the same time, it is possible to prevent the welded material of the chips welded to the rough surface region 34 from becoming excessive.

As shown in FIG. 8, the rough surface region 34 is formed by, for example, a groove formed in the rake surface 32. Such a groove can be formed by, for example, electric discharge machining, laser machining, or the like. However, the rough surface region 34 is not limited to that formed by such grooves, and may be formed by, for example, roughening treatment such as sandblasting.

When the rough surface region 34 is formed by grooves, the depth E of the grooves can be, for example, 1 μm or more and 20 μm or less. When the groove depth E is 1 μm or more, sufficient frictional resistance can be generated between the chips and the rough surface region 34. On the other hand, when the groove depth E is 20 μm or less, it is possible to suppress the frictional resistance generated between the chips and the rough surface region 34 from becoming excessive, and welding to the rough surface region 34. It is possible to prevent the welded material of chips from becoming excessive.

As described above, in the rotary cutting tool 1 according to the present embodiment, when the rotary cutting tool 1 is rotated to cut the workpiece, the chips cut by the cutting edge 31 move away from the rake face 32. While curling, it is pressed against the rough surface region 34. At this time, a large frictional resistance is generated between the chips and the rough surface region 34, causing a difference between the chip generation speed and the speed of the chips flowing on the rough surface region 34, resulting in the chips. By causing the strain, the chips are broken and made finer. As a result, chips can be miniaturized without changing the shape of the cutting edge, and cutting performance and machining accuracy can be maintained. Moreover, when the chips are pressed against the rough surface region 34, a part of the chips is welded to the rough surface region 34, so that the frictional resistance generated between the chips and the rough surface region 34 increases. .. This further promotes the miniaturization of chips.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the tip of the shank is described as a flat flat head type, but the tip of the shank may be a pointed type. Further, in the above embodiment, the chip discharge groove has been described as extending in the axial direction of the shank, but the chip discharge groove may extend spirally along the axial direction of the shank.

The above-mentioned technique is not applied only to rotary cutting tools, but can also be applied to general cutting tools such as cutting tools and throw-away inserts as shown in FIG. The bite 110 shown in FIG. 9 has a cutting edge portion 130 fixed to the tip of the shank 120, and the cutting edge portion 130 has a cutting edge 131 and a rake face 132 extending from the cutting edge 131. Then, a roughened rough surface region 134 is formed in the vicinity of the cutting edge 131 on the rake face 132. The cutting edge portion 130, the cutting edge 131, the rake surface 132, and the rough surface region 134 correspond to the tip 3, the cutting blade 31, the rake surface, and the rough surface region 34 of the above embodiment, and the shape of the rough surface region 134 and the like, etc. The positional relationship of the rough surface region 134 with respect to the cutting edge 131 is the same as that of the above embodiment.

Next, Examples and Comparative Examples of the present invention will be described. The present invention is not limited to the following examples.

(Example 1)
As Example 1, a reamer in which two chips were fixed to the tip of a shank was produced. In Example 1, two rough surface regions extending linearly in the direction parallel to the cutting edge were formed on the rake face of each chip in the direction perpendicular to the cutting edge. Then, the reamer of Example 1 was rotated to drill a hole in the object to be machined of the aluminum alloy. In the drilling process, the feed amount f of the reamer was set to 0.05 [mm / rev], 0.1 [mm / rev], 0.2 [mm / rev], and 0.4 [mm / rev]. Then, the length of the chips generated by the drilling process at each feed amount f was measured. The measurement results are shown in FIG. Further, a photograph of chips generated by drilling with a feed amount f of 0.05 [mm / rev] is shown in FIG. 11, and the chips are generated by drilling with a feed amount f of 0.1 [mm / rev]. A photograph of chips is shown in FIG. 12, a photograph of chips produced by drilling with a feed amount f of 0.2 [mm / rev] is shown in FIG. 13, and a feed amount of 0.4 [mm / rev] is shown. A photograph of the chips generated by the drilling process in f is shown in FIG.

(Comparative Example 1)
As Comparative Example 1, the same reamer as in Example 1 was produced except that a rough surface region was not formed on the rake face of each chip. Then, the reamer of Comparative Example 1 was rotated to drill a hole in the object to be machined of the aluminum alloy. In the drilling process, the feed amount f of the reamer was set to 0.05 [mm / rev], 0.1 [mm / rev], 0.2 [mm / rev], and 0.4 [mm / rev]. Then, the length of the chips generated by the drilling process at each feed amount f was measured. The measurement results are shown in FIG. Further, a photograph of chips generated by drilling with a feed amount f of 0.05 [mm / rev] is shown in FIG. 15, and the chips were generated by drilling with a feed amount f of 0.1 [mm / rev]. A photograph of chips is shown in FIG. 16, and a photograph of chips generated by drilling with a feed amount f of 0.2 [mm / rev] is shown in FIG. 17, and a feed amount of 0.4 [mm / rev] is shown. A photograph of the chips generated by the drilling process in f is shown in FIG.

(evaluation)
As shown in FIGS. 10 to 18, in Comparative Example 1, the chips extended to 6 mm or more regardless of the feed amount f, but in Example 1, regardless of the feed amount f. , Chips were miniaturized to less than 6 mm. From these results, it was found that the chips can be miniaturized by forming a rough surface region on the rake face of the chip.

1 ... rotary cutting tool, 2 ... shank, 3 ... tip, 3A ... tip, 3B ... tip, 3C ... tip, 4 ... chip discharge groove, 31 ... cutting edge, 32 ... rake surface, 33 ... land, 34 ... coarse Surface area, 110 ... bite, 120 ... shank, 130 ... cutting edge, 131 ... cutting edge, 132 ... rake surface, 134 ... rough surface area.

Claims (8)

A rotary cutting tool in which a tip made of ultra-hard material is fixed to the tip of a shaft-shaped shank.
The tip has a cutting edge and a rake face extending from the cutting edge.
A plurality of roughened rough surface regions are formed in the vicinity of the cutting edge on the rake face in the direction perpendicular to the cutting edge.
The rough surface region extends in a direction parallel to the cutting edge and is formed by a groove formed in the rake surface.
The arithmetic mean height Sa of the rough surface region is 0.1 μm or more and 5 μm or less.
The plurality of rough surface regions are separated from each other.
Rotary cutting tool. The distance from the cutting edge to the tip of the rough surface region on the cutting edge side is 10 μm or more and 100 μm or less.
The rotary cutting tool according to claim 1. The tip has a land extending from the cutting edge along the outer peripheral surface of the shank along the axial direction of the shank.
The rotary cutting tool according to claim 1 or 2. The rough surface area does not extend to the land ,
The rotary cutting tool according to claim 3 . The distance between the plurality of rough surface regions is 8 μm or more and 100 μm or less.
The rotary cutting tool according to any one of claims 1 to 4 . The width of the rough surface region in the direction perpendicular to the cutting edge is 10 μm or more and 200 μm or less.
The rotary cutting tool according to any one of claims 1 to 5 . The depth of the groove is 1 μm or more and 20 μm or less.
The rotary cutting tool according to any one of claims 1 to 6 . The cemented carbide material is a diamond sintered body, a single crystal diamond, or a cubic boron nitride sintered body.
The rotary cutting tool according to any one of claims 1 to 7.

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