JP6635501B2 - Tool for rotary cutting of brittle material and rotary cutting method - Google Patents

Description

  The present invention relates to a rotary cutting tool for brittle material and a rotary cutting method using the same.

  Generally, when a brittle material such as an optical glass or ceramics is cut or ground, brittle damage occurs. Therefore, in order to secure the function of the product, it is removed by a post-process such as polishing. The polishing process is based on the "pressure transfer principle", in which the pressing pressure of the abrasive grains on the material is transferred as the processing shape. In addition to the mechanical removal by the abrasive grains, it also applies to the chemical action between the abrasive grains and the workpiece surface. Because of the influence, it is difficult to clearly predict the resulting shape. For this reason, the securing of the shape accuracy by the above-mentioned polishing process still depends greatly on the skill of a skilled worker even at present.

  On the other hand, in the case of cutting / grinding, both of the machining methods follow the “motion transfer principle” in which the relative motion between the tool and the workpiece is transferred as the finished surface, so that the finished surface can be generated without causing brittle damage. If so, the amount of material removed by machining and the shape to be generated can be relatively easily predicted, and machining accuracy can be compensated for by a simpler work process regardless of the skill of the operator.

  Therefore, an object of the present invention is to provide a rotary cutting tool capable of producing a smooth finished surface or a finished surface having an arbitrary surface property without causing brittle damage in the rotary cutting of a brittle material, and a rotary cutting using the same. It is to provide a method.

  The generation of brittle damage during cutting depends on the cutting of the cutting edge of the rotary cutting tool into the work material, and is suppressed when the cutting depth is smaller than a certain cutting amount. Cutting performed in this state is called ductile mode cutting. The present inventor, by arranging a plurality of microstructures on the micro-nanometer scale having a specific shape regularly on the cutting edge ridge, the cutting amount of the work material by each microstructure, the ductile mode It has been found that the cutting depth can be suppressed below the limit at which cutting can be achieved, and as a result, it is possible to produce a smooth finished surface or a finished surface having any surface texture without causing brittle damage (for example, cracking). I found it. The present invention is based on such findings.

The present invention
[1] A rotary cutting tool in which a plurality of microstructures on a micro-nanometer scale are regularly arranged on a cutting edge ridge line,
The tool, wherein the shape of the microstructure is a shape in which a tip makes a point-like contact with a processing surface of a workpiece;
[2] A rotary cutting tool in which a plurality of microstructures of the same shape and the same size on a micro-nanometer scale are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
The tool, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval;
[3] A rotary cutting tool in which a plurality of micro-nanometer-scale microstructures having the same shape and the same dimensions are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
Each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval,
The tool, wherein a tool movement amount per one rotation of the spindle is equal to or less than a condition of ductile mode cutting of the work material;
[4] A rotary cutting tool in which a plurality of micro- and nanometer-scale microstructures having the same shape and the same dimensions are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
Each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval,
The tool, wherein a tool movement amount per rotation of the spindle is an integral multiple of a basic period of the microstructure;
[5] A rotary cutting tool in which a plurality of microstructures on a micro-nanometer scale whose shape and / or size changes stepwise on a cutting edge ridge line are regularly arranged,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
The tool, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval;
[6] A rotary cutting tool in which a plurality of microstructures on a micro-nanometer scale whose shape and / or size changes stepwise on a cutting edge ridge line are regularly arranged,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
Each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval,
The tool, wherein a tool movement amount per one rotation of the spindle is equal to or less than a condition of ductile mode cutting of the work material;
[7] A rotary cutting tool in which a plurality of microstructures on a micro-nanometer scale whose shape and / or size changes stepwise are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
Each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval,
The tool, wherein a tool movement amount per rotation of the spindle is an integral multiple of a basic period of the microstructure;
[8] A rotary cutting method using the tool according to any one of [1] to [7].
About.

  ADVANTAGE OF THE INVENTION According to this invention, in the rotary cutting of a brittle material, a smooth finished surface or a finished surface having any surface properties can be generated without causing brittle damage.

FIG. 2 is a plan view and a side view schematically showing one embodiment of the present invention in which the present invention is applied to an R bite, and a partially enlarged view schematically showing a microstructure and a cutting edge ridge line around the microstructure in the one embodiment. 1 is a partial front view schematically showing one embodiment of the present invention in which the present invention is applied to a ball end mill. 1 is a partial front view schematically showing one embodiment of the present invention in which the present invention is applied to a drill. FIG. 3 is a partial front view schematically showing one embodiment of the present invention in which the present invention is applied to a grindstone, and a partially enlarged view schematically showing a microstructure in the one embodiment. It is explanatory drawing which shows typically the various shapes of the fine structure which can be used by this invention. It is explanatory drawing which shows typically the various shapes of another fine structure which can be used by this invention. FIG. 3 is a partial cross-sectional view schematically showing one embodiment of the present invention together with a work material, in which a plurality of microstructures have the same shape and the same dimension and the interval between adjacent microstructures is constant. FIG. 3 is a partial cross-sectional view schematically showing one embodiment of the present invention together with a work material, in which a plurality of microstructures have the same shape and the same dimension, and an interval between adjacent microstructures is not equal. FIG. 4 is a partial cross-sectional view schematically showing one embodiment of the present invention together with a work material, in which shapes and / or sizes of a plurality of microstructures change stepwise. In one embodiment of the present invention in which the shapes and / or sizes of a plurality of microstructures change stepwise, only each of the microstructures (1 to 4) is taken out and their shapes are adjusted so that their tips and central axes coincide. It is explanatory drawing which shows the mode that it overlapped typically. In another aspect of the present invention in which the shape and / or size of a plurality of microstructures changes stepwise, only each microstructure (1 to 9) is taken out, and the tip and the central axis thereof are aligned. It is explanatory drawing which shows the mode that the shape of this was overlapped typically. With respect to an embodiment of the tool of the present invention in which the tool (A-1) is applied to a ball end mill, in ball end mill cutting, a state in which a microstructure provided on a cutting edge ridge line cuts into a machined surface of a work material is schematically shown. FIG. With respect to one embodiment of the tool of the present invention in which the tool (A-2) is applied to a ball end mill, a schematic diagram showing a time series of a process in which a microstructure provided on a cutting edge ridge line generates a finished surface in ball end mill cutting. FIG. FIG. 14 is a schematic explanatory view showing a process of generating a finished surface, paying attention to the second fine structure region at the top of FIG. 13. Regarding an aspect of the tool of the present invention in which the tool (B-2) is applied to a ball end mill, in a ball end mill cutting, a state where a microstructure provided on a cutting edge ridge is cut into a machined surface of a work material. It is explanatory drawing which shows typically. FIG. 16 is a schematic explanatory view showing a process of generating a finished surface, paying attention to the region of the first fine structure in FIG. 15. FIG. 3 is a schematic explanatory view for explaining one of the causes of brittle damage in rotary cutting. It is a schematic explanatory view for explaining the mechanism of action of the present invention. 5 is a scanning electron micrograph showing the microstructure of one embodiment of the tool of the present invention used in the test. FIG. 19A is a scanning electron micrograph showing the shape of the tip of the ball end mill, and FIG. 19B is a partially enlarged photograph of a region surrounded by a circle in FIG. (c) is a partially enlarged photograph showing the shape of the fine structure further enlarged.

The rotary cutting tool of the present invention (hereinafter, sometimes simply referred to as the tool of the present invention) is characterized in that a plurality of microstructures on a micro-nanometer scale are regularly arranged on a cutting edge ridge line. And
The tool to which the present invention can be applied is not particularly limited as long as it is a tool that can be used for rotary cutting of a brittle material (for example, optical glass, ceramics, and the like). , Face milling) (Figure 1), milling tools (especially end mills; Figure 2) used in milling machines, drills (Figure 3) used in drilling machines, and multi-edged tools with a periodic structure (Figure 4) And the like.

  The microstructure provided in the tool of the present invention is not particularly limited as long as it has a shape and dimensions capable of achieving ductile mode cutting. The microstructure on the micro / nanometer scale in which the vicinity of the tip of each fine structure is in point-like contact.

  For example, as shown in FIG. 5, a triangular wave (see FIG. 5a) seen from the rake face side of the tool as shown in FIG. , B, d), a sine wave (FIG. 5c), a polygonal wave (FIG. 5e), a sawtooth wave (FIG. 5f), and the like, and a three-dimensional solid structure as shown in FIG. You can also.

  As used herein, the term “micro / nanometer scale” refers to a size that can be expressed in units of micrometer (μm) or nanometer (nm) and a range in the vicinity thereof, and specifically 1 nm to 1000 nm, And 1 μm (1000 nm) to 1000 μm. In the case of each of the shapes shown in FIGS. 5A to 5F, each dimension applies an appropriate dimension / geometric relationship to the work material and the processing conditions to be applied. For example, in the case of each shape shown in FIGS. 5a to 5f, the amplitude (the shortest distance between the reference line and the tip; z shown in FIG. 5) can be, for example, 0.1 μm to 20 μm, preferably 0.1 μm to 10 μm. The period (the interval between adjacent microstructures; x shown in FIG. 5) can be, for example, 0.1 μm to 20 μm, and preferably 0.1 μm to 10 μm. Further, if soda lime glass is cut by a single-blade ball end mill having a triangular wave-shaped fine structure formed under a condition of an inclination angle of 45 degrees, the period is desirably 2 μm for an amplitude of 1 μm.

  The tool of the present invention is characterized in that a plurality of microstructures are provided on the cutting edge ridge line, and a fine structure can be provided over the entire cutting edge ridge line. It is preferable to provide a microstructure in a region substantially involved in cutting and a peripheral region thereof. This area is determined by the radius of curvature of the tool nose, the cutting depth, and the tool inclination angle with respect to the normal direction of the finished surface. For example, if the radius of curvature of the tool nose is 500 μm, the cutting depth is 20 μm, and the tool inclination angle is 45 degrees, the forming length (on the ridgeline) 20 is within ± 50 μm around the cutting edge height of 150 μm, that is, within the range of cutting edge height of 100 to 200 μm. The fine structure can be provided in a region of from 40 μm to 40 μm, preferably from 40 to 120 μm.

  In the tool of the present invention, the plurality of microstructures are regularly arranged on the cutting edge line. In this specification, "arrange a plurality of microstructures regularly" means that the shape and / or size of the microstructures are regular and / or the interval between adjacent microstructures is regular. Means that.

  The case where the “shape and / or size of the microstructure is regular” is, for example, when the plurality of microstructures have the same shape and the same size (FIGS. 7 and 8). And / or a case where the size changes stepwise (FIG. 9). In the present invention, only a plurality of microstructures having the same shape and the same size, or only a plurality of microstructures having a shape and / or a size that changes stepwise can be provided. It is also possible to continuously provide a group of microstructures having the same shape and the same dimension and a group of microstructures whose shape and / or size are changed stepwise.

  FIGS. 10 and 11 show a case where the shapes and / or sizes of a plurality of microstructures change stepwise, take out only each microstructure, and superimpose the shapes so that the tip and the central axis coincide. FIG. The numbers 1 to 4 shown in FIG. 10 correspond to the numbers in parentheses of the numbers [for example, 4 (1)] representing the fine structure shown in FIG. 9 and therefore represent the order of cutting into the work material. . The same applies to the numerals 1 to 9 shown in FIG.

FIG. 10 shows a mode in which the shape of each microstructure is the same (here, a triangular wave is assumed as an example), and the size increases stepwise according to the cutting order in the work material. In the following description, it is assumed that the tool movement amount per one rotation of the spindle is the same as the period of the microstructure (that is, one time of the same period). After the microstructure 1 is first cut into a triangular shape, the microstructure 2 that has reached the next cut has a slightly larger cut area than the microstructure 1, so the cut is made by the area difference. At this time, if the area difference of the cut area is set so as not to exceed the ductile mode cutting condition, the occurrence of brittle damage (for example, crack) can be avoided. Similarly, each time the microstructure 3 and the microstructure 4 sequentially reach the same cut, the cut is made by the area difference between the adjacent microstructures, and finally, the surface texture corresponding to the triangular wave of the fine structure 4 is finished. Generated on the surface.
For example, when the ball end mill having the above-described microstructure is moved linearly, a plurality of curved streaks (grooves) extending along the traveling direction of the tool, and a cross section in a direction perpendicular to the traveling direction. Are formed on the finished surface. In the case of face cutting, a streak (groove) extending continuously in a spiral shape and having a triangular cross section is generated on the finished surface. In the case of a drill, a streak (groove) extending in a female screw shape and having a triangular cross section is generated on the finished surface.

FIG. 11 shows a mode in which the shape of each fine structure changes from a triangular wave (fine structure 1) to a polygonal wave (fine structures 2 to 9), and the size gradually increases. First, the microstructure 1 cuts in a triangular shape, and then the microstructure 2 that has reached the cut has a slightly larger cut area than the microstructure 1. Changes from a triangular shape to a polygonal shape. Subsequently, each time the microstructure 3 and the microstructure 4 sequentially reach the same cut, the cut is performed by the area difference between the adjacent fine structures while maintaining the polygonal shape. A surface property corresponding to a square wave is generated on the finished surface. In the present invention, since the area difference of the cut area is set so as not to exceed the ductile mode cutting condition, it is possible to avoid the occurrence of brittle damage (for example, crack) on the finished surface at each cut.
If a microstructure having an apex angle close to 180 degrees is further arranged after the microstructure 9, a substantially smooth finished surface can be generated.

The case where “the interval between adjacent microstructures is regular” is, for example, a case where each interval (period) between adjacent microstructures is an integral multiple of the minimum value of the interval (hereinafter, referred to as a basic period). Can be mentioned. In the present invention, as will be described later, by arranging the microstructures regularly, it is possible to suppress the occurrence of an unexpectedly large amount of cut, and as a result, the entire material removal region (however, (Excluding the initial stage of the above), it is possible to make the cut depth equal to or less than the ductile mode cutting condition.
The “integer multiple” is a positive integer of 1 or more, and can be set for each interval. In the tool of the present invention, the intervals between adjacent microstructures can be all the same (ie, equal intervals), or can be the same and / or different at each interval.

The tool of the present invention includes various specific embodiments according to, for example, the shape and size of the microstructure, and further, according to the relationship between the tool movement amount per rotation of the spindle and the basic period of the microstructure.
Specifically, the tool of the present invention includes, for example,
(A) A rotary cutting tool in which a plurality of microstructures of the same shape and the same size on a micro-nanometer scale are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
The tool, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval;
(B) A rotary cutting tool in which a plurality of micro-nanometer-scale microstructures whose shape and / or size change stepwise are regularly arranged on a cutting edge ridge line,
The shape of the microstructure is a shape in which the tip is in point contact with the processing surface of the work material,
The tool, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval;
Is included.

The tool (A) further includes, for example,
(A-1) The tool (A), which can be used under the condition that a tool movement amount per one rotation of a spindle is equal to or less than a condition of ductile mode cutting of a work material;
(A-2) The tool (A), which can be used under the condition that the amount of tool movement per revolution of the spindle is an integral multiple of the basic period of the microstructure;
Is included. The tool (A-1) can be used to generate a smooth finished surface, and the tool (A-2) can be used to generate a finished surface having any surface texture. it can.

The tool (B) further includes, for example,
(B-1) The tool (B), which can be used under the condition that the tool movement amount per one rotation of the spindle is equal to or less than the condition of the ductile mode cutting of the work material;
(B-2) the tool (B), which can be used under the condition that the tool movement amount per one rotation of the spindle is an integral multiple of the basic period of the microstructure;
Is included. The tool (B-1) can be used to generate a smooth finished surface, and the tool (B-2) can be used to generate a finished surface having any surface texture. it can.

Hereinafter, the present invention will be further described based on various specific embodiments of the present invention.
FIG. 12 shows an embodiment of the tool of the present invention in which the tool (A-1) is applied to a ball end mill. In the ball end mill cutting, a microstructure provided on a cutting edge ridge line cuts a work surface of a work material. It is explanatory drawing which shows the state which fits in typically.

  As shown in FIG. 12, a plurality of microstructures 4 (1) to 4 (7) having the same shape and the same size on the micro nanometer scale are provided on the cutting edge 2 of the tool 1 along the ridge line. Have been. The tool moves from left to right in the drawing (in the direction indicated by the arrow). Further, the tool is inclined so as to retract with respect to the traveling direction, and rotates clockwise with respect to the tool axis, that is, from the back of the drawing toward the near side. In the following description, the amount of tool movement in the direction indicated by the arrow per one rotation of the main spindle is equal to or less than the condition for ductile mode cutting of a work material.

  As shown in FIG. 12, when the microstructure 4 (7) reaches the lowest point of the cutting edge 2, the preceding microstructures 4 (1) to 4 (6) are processed surfaces of the work material 9, respectively. However, since the ridgeline (the ridgeline before providing the fine structure) of the cutting edge is circular, the cut position changes, and the finished surface 91 becomes lower as the subsequent fine structure is obtained. Here, for example, focusing on the microstructure 4 (5), the tool makes 20 rotations while moving to the position of the microstructure 4 (4). The finished surface 91 (4) sandwiched between 4 (5) and 4 (4) is cut only near the apex of the microstructure 4 (4). In the present invention, in order to set the shape and dimensions of the microstructure and the cutting conditions so as to be equal to or less than the limit depth of cut that can achieve ductile mode cutting, in the embodiment shown in FIG. When each of the cut depths is equal to or less than the limit cut depth, a smooth finished surface can be generated without causing brittle damage (for example, cracks).

  FIG. 13 is a view showing a state in which a microstructure provided on a cutting edge line forms a finished surface in ball end mill cutting in one embodiment of the tool of the present invention in which the tool (A-2) is applied to a ball end mill. It is a schematic explanatory view shown in a series. In FIG. 13, a thin line is shown as a cutting edge ridge line and a fine structure, and a thick line is shown as a finished surface, and the tool advances from left to right in the drawing. Further, the tool is inclined so as to retract with respect to the traveling direction, and rotates clockwise with respect to the tool axis, that is, from the back of the drawing toward the near side. In FIG. 13, numbers 1 to 13 are assigned from the fine structure in front of the feed.

  FIG. 14 is a schematic explanatory view showing the process of generating a finished surface, focusing on the area of the second fine structure at the top of FIG. In the tool (A-2), the tool movement amount per one rotation of the spindle is set to be equal to an integral multiple of the basic period of the microstructure. In the following description, it is assumed that the tool movement amount per one rotation of the spindle is the same as the period of the microstructure (that is, one time the same period). In this case, the second fine structure passes through the finished surface generated by the first fine structure after one rotation of the spindle. Thereafter, for each rotation, the subsequent microstructure passes through the finished surface in the same region in numerical order (3 → 4 → 5...). In the case of ball end mill cutting, the cutting edge (vertical line in the drawing) of each microstructure is circular because the ridgeline of the cutting edge (the ridgeline before the microstructure is provided) changes. Lower. That is, until the 7th microstructure, which is the lowest point of the circular cutting edge, passes through the finished surface, the subsequent microstructure cuts in the axial direction with respect to the finished surface generated by the preceding microstructure. Will be. After No. 7 has passed through the finishing surface, even if subsequent microstructures after No. 8 pass through the finishing surface, the cuts in the axial direction will not be made because the position will be higher, and the passing will continue as it is. The surface remains in shape. In the present invention, in order to set the shape and size of the microstructure and the cutting conditions so as to be equal to or less than the limit depth of cut that can achieve ductile mode cutting, in the embodiment shown in FIG. However, when each of them is equal to or less than the above-mentioned critical depth of cut, it is possible to generate a finished surface having a surface property of a microstructure without causing brittle damage (for example, cracking).

  In the embodiment shown in FIG. 13, when the tool movement amount per one rotation of the spindle is an integral multiple of the period of the microstructure, for example, twice, focusing on the region of the first microstructure at the top of FIG. After the first microstructure has passed, it passes through the finished surface in the same region in the order of No. 3, No. 5, and No. 7 every one revolution of the spindle. Similarly, paying attention to the region of the second fine structure at the top of FIG. 13, after the second fine structure passes, finishing of the same region in the order of the fourth, sixth, and eighth every one rotation of the spindle. Passing through the plane. Therefore, even when the amount of tool movement per spindle rotation is an integral multiple of the period of the microstructure, if the depth of cut of each microstructure does not exceed the condition of ductile mode cutting, respectively, brittle damage (for example, It is possible to produce a finished surface having a microstructured surface property without causing cracks.

FIG. 15 shows an embodiment of the tool of the present invention in which the tool (B-2) is applied to a ball end mill. In the ball end mill cutting, a microstructure provided on a cutting edge ridge line is cut on a machined surface of a work material. It is explanatory drawing which shows the state in which it was inserted typically. The tool travels from left to right in the drawing. Further, the tool is inclined so as to retract with respect to the traveling direction, and rotates clockwise with respect to the tool axis, that is, from the back of the drawing toward the near side. In FIG. 15, numbers 1 to 6 are assigned from the fine structure in front of the feed.
FIG. 16 is a schematic explanatory view showing the process of generating a finished surface, focusing on the region of the first microstructure in FIG.

  In the tool (B-2), the shape and / or size of the microstructure changes stepwise. The tool movement amount per one rotation of the spindle is an integral multiple of the basic period of the microstructure. In the following description, it is assumed that the tool movement amount per one rotation of the spindle is the same as the period of the microstructure (that is, one time the same period). In the mode shown in FIG. 15, the apex angle of the triangular-wave-shaped fine structure is enlarged in numerical order from the top. Each microstructure passes through the finished surface every rotation, and the final (No. 6) shape remains as the finished surface property. As the apex angle of each microstructure changes, the depth of cut in each step changes. However, if the depth of cut in each step does not exceed the condition of ductile mode cutting, brittle damage (eg, crack) , It is possible to generate a finished surface according to the surface properties of the final microstructure.

  In the embodiment shown in FIG. 15, by changing the tool movement amount per one rotation of the spindle from “an integral multiple of the basic period of the microstructure” to “not more than the condition of the ductile mode cutting of the work material”, The embodiment shown can be used as the tool (B-1).

As described above, in the present invention, on the cutting edge ridge of the rotary cutting tool, by regularly arranging a plurality of microstructures on the micro-nanometer scale, the cutting amount of each microstructure, Because it can be set to be equal to or less than the limit depth of cut that can achieve ductile mode cutting, without causing brittle fracture on the finished surface of the work material, a smooth finished surface, or any surface texture A finished surface can be created.
The critical depth of cut that can achieve ductile mode cutting includes, for example, the type of machine tool and rotary cutting tool used, the material to be machined and the material of the rotary cutting tool, and the various conditions of rotary cutting (for example, tool or workpiece Rotation speed of the material, the feed rate of the tool or the work material, the cutting amount of the tool cutting edge into the work material, the inclination angle of the tool or the work material, the cutting fluid, etc.). As shown in, under the conditions scheduled to perform rotary cutting, preliminary experiments are performed, for example, the presence or absence of brittle fracture and the state of the processed surface are used as evaluation indexes, and the shape and size of the microstructure, and the arrangement method are determined. be able to.
Alternatively, the present invention is determined by determining the shape and size of the microstructure and the arrangement method in advance, and in a preliminary experiment, changing the various conditions of the rotary cutting while changing the preferred execution conditions based on the evaluation index. Can be implemented.

  Even if a brittle material other than optical glass is selected as a work material and a rotary cutting tool other than a ball end mill is selected as a tool, the respective normal processing conditions are well known to those skilled in the art, In the same manner as described above, a microstructure and processing conditions that can generate a desired finished surface can be determined.

(Operation of the present invention)
The present invention is not limited to the following mechanism for the reason that the present invention can produce a smooth finished surface or a finished surface having an arbitrary surface property without causing brittle damage. Consider the following mechanism of action.
One of the causes of brittle damage due to a change in the shape of the cutting edge ridge line (so-called unevenness) in rotary cutting is as shown in FIG. 17, each position on the ridge line until the cutting edge 2 or the work material 9 makes one rotation. It is conceivable that the cutting amount of the cutting edge locally changes and brittle damage occurs from a portion where the cutting becomes excessive. This phenomenon is caused by brittle damage even if a cutting edge having a ridge line without unevenness (for example, a comparative example in the later-described example) is used, as shown in a comparative example in the later-described example. It is presumed that an irregular change in the shape of the cutting edge ridge occurs inside, and as a result, the state is the same as that in FIG.
However, as shown in FIG. 18, when a plurality of microstructures 4 having a specific shape are regularly arranged on the ridge line of the cutting edge 2, the generation of an unexpectedly large cutting amount is suppressed, so that the cutting is performed. It is possible to reduce the depth of cut to less than the ductile mode cutting conditions. As a result, local increase in depth of cut and change in stress state do not occur, and the entire material removal area (however, the initial stage of rotary It is considered that ductile mode cutting can be performed without causing brittle damage.

  Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the scope of the present invention.

<< Example 1 >>
In the cutting test in the present embodiment, a single-crystal diamond ball end mill having a tool nose radius of 0.5 mm and a number of blades formed of a triangular-wave microstructure having a period of 2 μm and an amplitude of 1.0 μm on a cutting edge ridge line was used. Groove cutting was performed on the soda-lime glass substrate, and the effect on brittle damage was evaluated by observing the finished surface properties (smooth surface).

  FIG. 19 shows the microstructure of the tool used for the test. FIG. 19A is a scanning electron micrograph showing the shape of the tip of the ball end mill, and FIG. 19B is a partially enlarged photograph of a region surrounded by a circle in FIG. (c) is a partially enlarged photograph showing the shape of the fine structure further enlarged. Using a focused ion beam processing machine (FIB), a period of 2 μm and an amplitude of 1 in a region (cutting edge height: 144 to 178 μm, forming length (on the ridge line): 48 μm) contributing to generation of a finished surface during cutting on the ridge. A microstructure of 0 μm was produced. The apex angle of the top of the triangular wave is 90 °.

  The processing machine on which the tool is mounted is composed of a total of three axes, a XY 2-axis linear stage (resolution 0.1 μm) and a Z-axis stepping motor stage (resolution 0.01 μm), and each axis can be controlled simultaneously by a motion controller. . A brushless motor spindle having a maximum rotation speed of 60,000 rpm is installed on a side surface of the Z-axis stage through a jig while being inclined at a specific angle with respect to the workpiece, and groove cutting can be performed while inclining the tool. The work material can be set on a gonio stage installed on a piezoelectric dynamometer, and cutting can be performed while tilting the work material with respect to the tool feed. The groove was cut at a tool inclination angle of 45 degrees with respect to the tool feed direction and an axial cut of 20 μm (constant). The tool inclination angle is 0 degree in the direction perpendicular to the upper surface of the work material, and the direction in which the tool is retracted with respect to the feed is positive. Distilled water was used as the cutting fluid. Table 1 shows the main processing conditions.

  Table 2 shows the results of the roughness measurement of the finished surface of the groove bottom cut under the above conditions. In any of the evaluation indices Ra and Rz, the tool of the present invention provided with a microstructure having a period of 2 μm and an amplitude of 1.0 μm can generate a smoother finished surface as compared with a comparative example having no microstructure. confirmed. Also, in observation of the finished surface, in the comparative example, fine peeling was observed on the entire finished surface, but in the example, fine peeling was also suppressed.

  INDUSTRIAL APPLICABILITY The present invention can be used in the field of rotary cutting of brittle materials such as optical glass and ceramics.

DESCRIPTION OF SYMBOLS 1 ... Tool; 2 ... Cutting edge; 3 ... Ridge line; 4 ... Microstructure;
9: Work material; 91: Finished surface.

Claims (8)

A rotary cutting tool in which a plurality of microstructures on a micro-nanometer scale are regularly arranged on the cutting edge ridge,
The tool, wherein all of the microstructures have a shape in which a tip makes a point-like contact with a processing surface of a work material. The plurality of microstructures are micro-nanometer-scale microstructures having the same shape and the same dimensions,
The tool according to claim 1, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval.   3. The tool according to claim 2, wherein a tool movement amount per rotation of the spindle is equal to or less than a condition of ductile mode cutting of a work material.   3. The tool according to claim 2, wherein a tool movement amount per one rotation of the spindle is an integral multiple of a basic period of the microstructure. The plurality of microstructures are micro-nanometer-scale microstructures in which the shape and / or size are changed stepwise,
The tool according to claim 1, wherein each interval between adjacent microstructures is an integral multiple of a minimum value (basic period) of the interval.   The tool according to claim 5, wherein a tool movement amount per one rotation of the spindle is equal to or less than a condition for ductile mode cutting of a work material.   The tool according to claim 5, wherein a tool movement amount per one rotation of the spindle is an integral multiple of a basic period of the microstructure.   A rotary cutting method using the tool according to any one of claims 1 to 7.