CUTTING EDGE MACHINING APPARATUS AND CUTTING APPARATUS

A first optical member including a reflection mirror and a lens forms a first optical path of laser light. A second optical member including a reflection mirror, a lens, and a reflection mirror forms a second optical path of laser light. A motion mechanism moves a cutting edge of a cutting part relative to the first optical path and the second optical path. A controller causes the motion mechanism to move the cutting edge relative to the first optical path to machine a flank face of the cutting edge with laser light passing through the first optical path. The controller further causes the motion mechanism to move the cutting edge relative to the second optical path to machine a rake face of the cutting edge with laser light passing through the second optical path.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a technique of machining a cutting part of a cutting tool with laser light.

2. Description of the Related Art

As a machining method using laser light, pulse laser grinding (PLG) is known in which surface machining is performed by concentrating pulse laser light and scanning a cylindrical irradiation region including a focused spot over a surface of a premachined object. JP 2016-159318 A discloses a method of overlapping an irradiation region of pulse laser light that extends in a cylindrical shape and has energy enough to make machining with a surface-side portion of a premachined object and scanning the irradiation region at a speed that allows machining to remove a surface region of the premachined object. Non Patent Literature 1, Hiroshi Saito, Hongjin Jung, Eiji Shamoto, Shinya Suganuma, and Fumihiro Itoigawa; “Mirror Surface Machining of Steel by  Elliptical Vibration Cutting with Diamond-Coated Tools Sharpened by Pulse Laser Grinding”, International Journal of Automation Technology, Vol. 12, No. 4, pp.573-581 (2018), discloses a technique of machining a flank face of a tool base material in two directions by pulse laser grinding to form a V-shaped cutting edge.

SUMMARY

FIGS. 1A and 1Bare diagrams for describing a method of sharpening a cutting edge of a diamond-coated tool by pulse laser grinding disclosed in Non Patent Literature 1.FIG. 1Ashows a state where a rake face is subjected to pulse laser grinding, andFIG. 1Bshows a state where a flank face is subjected to pulse laser grinding in two directions. As disclosed in Non Patent Literature 1, the cutting edge is sharpened by causing laser light to slightly cut into the tool cutting edge and applying a feed motion along the cutting edge ridgeline between the laser light and the tool.

As shown inFIGS. 1A and 1B, in order to machine the rake face and flank face of the tool cutting edge using a single ray of laser light, it is necessary to change the orientation of the tool relative to the laser light. As disclosed in Non Patent Literature 1, a five-axis machine tool having three translation axes of XYZ and two rotation axes including A-axis and C-axis is used to change the tool orientation by a cutting-part angle (an angle between the  rake face and the flank face after being machined). In order to machine the rake face and flank face of the tool cutting edge with a machining apparatus that uses a single ray of laser light as described above, a rotation control axis for changing the tool orientation is required.

The present disclosure has been made in view of such circumstances, and it is therefore one object of the present disclosure to provide a cutting edge machining technique that allows a reduction in the number of control axes. Further, another object of the present disclosure is to provide a cutting apparatus excellent in practicality.

In order to solve the above-described problem, a cutting edge machining apparatus according to one aspect of the present disclosure is structured to laser-machine a cutting part of a cutting tool and includes a first optical member structured to form a first optical path of laser light, a second optical member structured to form a second optical path of laser light, a motion mechanism structured to move a cutting edge of the cutting part relative to the first optical path and the second optical path, and a controller structured to control relative movement made by the motion mechanism. The controller causes the motion mechanism to move the cutting edge relative to the first optical path to machine a flank face of the cutting edge with laser light passing through the first optical path. The controller further causes the motion mechanism to move the cutting edge  relative to the second optical path to machine a rake face of the cutting edge with laser light passing through the second optical path.

Another aspect of the present disclosure is a cutting apparatus. This apparatus includes a motion mechanism structured to move a cutting edge of a cutting tool relative to a workpiece, and a controller structured to control movement, made by the motion mechanism, of the cutting edge of the cutting tool relative to the workpiece. The cutting apparatus further includes a laser light source structured to emit laser light for use in laser-machining the cutting edge of the cutting tool, and an optical member structured to form an optical path of laser light. The controller causes the motion mechanism to move the cutting edge relative to the optical path to laser-machine the cutting edge.

DETAILED DESCRIPTION

The disclosure will now be described by reference to the preferred embodiments. This does not intend to limit the scope of the present disclosure, but to exemplify the disclosure.

FIG. 2is a diagram for describing pulse laser grinding. As disclosed in JP 2016-159318 A and Non Patent Literature 1, the pulse laser grinding is a machining method of overlapping a cylindrical irradiation region extending in an optical axis direction of laser light2and having energy enough to make machining with a surface of a premachined  object20and scanning the cylindrical irradiation region in a direction intersecting the optical axis to remove a surface region of the premachined object20where the cylindrical irradiation region has passed. In the pulse laser grinding, a plane parallel to the optical axis direction and scanning direction is formed on the surface of the premachined object20.

Structure of Cutting Edge Machining Apparatus

FIG. 3shows a cutting edge machining apparatus10that laser-machines a cutting part of a cutting tool. The cutting edge machining apparatus10includes a laser-machining part11and a controller17. The controller17may be a numerical control (NC) control device that controls the laser-machining part11in accordance with an NC program. In the cutting edge machining apparatus10, the laser-machining part11and the controller17may be separately provided and be connected to each other by a cable or the like, or alternatively, may be integrated into a single device.

The laser-machining part11includes a bed12serving as a base, and a first table13and a second table14movably supported on the bed12. The first table13is supported movable in an X-axis direction by a rail provided on the bed12, and the second table14is supported movable in a Z-axis direction by a rail provided on the first table13. A tool holder15to which a premachined object is attached is provided on an upper surface of the second table14, and according to the embodiment, attached to the tool holder15is a cutting tool21having a cutting part22to be laser-machined. The cutting part22has a cutting edge22awith a flank face and a rake face for use in cutting a workpiece.

A laser unit16is capable of irradiating the cutting edge22aof the cutting part22with two rays of laser light to sharpen the cutting edge22a. The laser unit16according to the embodiment is a pulse laser grinder that overlaps a cylindrical irradiation region including a focused spot of laser light with the flank face of the cutting edge22aand the rake face of the cutting edge22aat the same timing or at different timings and scans the cylindrical irradiation region in a direction intersecting an optical axis of the laser light to remove a surface region through which the cylindrical irradiation region has passed, or alternatively, may be a laser machine tool that uses a different irradiation method.

The first table13and the second table14serve as a motion mechanism that moves the cutting edge22aof the cutting part22relative to a laser optical path in the laser unit16. Although not shown, the first table13and the second table14are each driven by an actuator such as a motor. Note that, according to the embodiment, the first table13and the second table14move the cutting tool21attached to the tool holder15in the X-axis direction and  the Z-axis direction, but the cutting tool21only needs to be moved relative to the laser optical path in the laser unit16. That is, the motion mechanism may move the laser optical path in the laser unit16relative to the cutting tool21. As described above, it does not matter which of the cutting tool21and the laser optical path is moved as long as the relative movement in a movement direction is made.

During laser-machining, the controller17controls the movements of the first table13and the second table14in accordance with the NC program to regulate the relative movement between the cutting tool21and the laser optical path made by the motion mechanism. Further, during laser-machining process, the controller17regulates the irradiation of laser light in the laser unit16. Note that the controller17may be capable of adjusting a position and orientation of an optical member in the laser unit16to make the laser optical path variable.

FIG. 4shows a state where the cutting part22of the cutting tool21has entered the laser unit16. Before laser-machining process, the controller17moves the second table14in a Z-axis positive direction to put at least a tip side of the cutting tool21into the laser unit16through an opening of the laser unit16. Then, the controller17drives a laser light source in the laser unit16to emit laser light for use in machining the flank face of the cutting edge22aand laser light for use in machining the rake face of the  cutting edge22a. Since the cutting edge machining apparatus10according to the embodiment machines the flank face of the cutting edge22aand the rake face of the cutting edge22aby using the two rays of laser light traveling in different directions, the cutting edge machining apparatus10has an advantage in that the orientation of the cutting tool21need not be changed between the machining of the flank face and the machining of the rake face, and no rotation control axis that changes the orientation of the tool is required.

FIG. 5shows an internal structure of the laser unit16. The laser unit16includes a protective housing30having an opening31, and a laser light source32and a plurality of optical members forming two laser optical paths are provided in the protective housing30. The protective housing30prevents the laser light emitted by the laser light source32from leaking to the outside and prevents foreign matter from entering the laser unit16. Note that, in order to prevent the leakage of light and the entrance of foreign matter more reliably, a mechanism that closes the opening31when laser-machining process is not under execution may be provided.

The laser light source32includes a laser oscillator that generates laser light, an attenuator that adjusts output of the laser light, a beam expander that adjusts a diameter of the laser light, and the like, and emits the laser light thus adjusted. The laser oscillator  may generate, for example, Nd:YAG pulse laser light. A beam splitter33splits the laser light emitted from the laser light source32into two optical paths. As shown inFIG. 5, the laser light emitted from the laser light source32is split into two rays of light by the beam splitter33, and the two rays of laser light are directed to the cutting edge22athrough different optical paths. The beam splitter33may be a half mirror.

A reflection mirror34and a lens35are optical members that form a first optical path25of laser light and direct light transmitting through the beam splitter33to a flank face23of the cutting edge22a. A reflection mirror36, a lens37, and a reflection mirror38are optical members that form a second optical path26of laser light and direct light reflected off the beam splitter33to a rake face24of the cutting edge22a. The lens35and the lens37each concentrate a corresponding ray of incident light to position the cylindrical irradiation region including the focused spot of the laser light at the cutting edge22a. The lens35and the lens37may be lens systems each including a plurality of lenses. When viewed in the X-axis direction, an angle between the first optical path25and the second optical path26near the cutting edge22ais set equal to an angle of the cutting part after being machined (an angle between the rake face and the flank face after being machined).

The controller17causes the motion mechanism to  move the cutting edge22aof the cutting tool21relative to the first optical path25and/or the second optical path26to machine the cutting edge22a. In the example shown inFIG. 5, a cutting edge ridgeline of the cutting edge22aextends in the X-axis direction, and, with the laser light passing through the first optical path25and/or the laser light passing through the second optical path26impinging on (applied to) the cutting edge22a, moving the cutting edge22ain the X-axis direction sharpens a tip of the cutting edge22a.

Specifically, the controller17moves, with the laser light passing through the first optical path25that is approximately parallel to the flank face23of the cutting edge22aapplied to the flank face23, the cutting edge22ain the X-axis direction relative to the first optical path25to machine the flank face23of the tool cutting edge with the laser light passing through the first optical path25. Further, the controller17moves, with the laser light passing through the second optical path26that is approximately parallel to the rake face24of the cutting edge22aapplied to the rake face24, the cutting edge22ain the X-axis direction relative to the second optical path26to machine the rake face24of the tool cutting edge with the laser light passing through the second optical path26. As described above, the laser unit16according to the embodiment is capable of machining the flank face23and the  rake face24with the rays of laser light passing through the two laser optical paths without changing the orientation of the cutting tool21.

The controller17may cause the motion mechanism to simultaneously move the cutting edge22arelative to the first optical path25and the second optical path26to simultaneously machine the flank face23and the rake face24. Simultaneously machining the flank face23and the rake face24using the two rays of laser light brings about an advantage that the sharpening time can be shortened.

Note that the flank face23and the rake face24may be machined at different timings. It is known that the finishing accuracy of cutting using the cutting tool21provided with the cutting edge22adepends on the surface roughness of the flank face23rather than the surface roughness of the rake face24. Therefore, the rake face24may be machined first, and then the flank face23may be machined such that the flank face23is finished last.

In this case, first, the controller17causes the motion mechanism to move the cutting edge22arelative to the second optical path26to machine the rake face24. Since the laser light passing through the first optical path25is not used at this time, the controller17may block the laser light passing through the first optical path25with a light-shielding plate (not shown). Note that it is preferable that the light-shielding plate be provided between the beam  splitter33and the lens35to block beam light before being concentrated. As described above, the rake face24of the tool cutting edge is machined first.

After the rake face24is machined, the controller17causes the motion mechanism to move the cutting edge22arelative to the first optical path25to machine the flank face23. Since the laser light passing through the second optical path26is not used at this time, the controller17may block the laser light passing through the second optical path26with a light-shielding plate (not shown). Note that it is preferable that the light-shielding plate be provided between the beam splitter33and the lens37to block the beam light before being concentrated. As described above, the flank face23of the tool cutting edge is machined, and the cutting edge machining is then completed.

As shown inFIG. 5, the rays of laser light passing through the first optical path25and the second optical path26each travel in a direction from a root side of the cutting part22toward a tip side of the cutting part22. Results of performing pulse laser grinding under various conditions show that the laser light applied from the root side of the cutting part22toward the tip side of the cutting part22brings about a flat surface with high accuracy as compared with the laser light applied from the tip side of the cutting part22toward the root side of the cutting part22. Therefore, it is preferable that the  traveling directions of the rays of laser light passing through the first optical path25and the second optical path26be each set to the direction from the root side of the cutting part22toward the tip side of the cutting part22.

Note that, in order to direct the laser light from the root side of the cutting part22toward the tip side of the cutting part22, it is necessary to avoid interference between the laser light and a part of the cutting tool21other than the cutting edge22a, a jig part, and the like. When it is difficult to set the traveling directions of the rays of laser light passing through both the first optical path25and the second optical path26to the directions from the root side of the cutting part22toward the tip side of the cutting part22due to spatial restrictions, the traveling direction of one of the rays of laser light may be set to an opposite direction. When the traveling direction of one of the rays of laser light is set to the opposite direction, the controller17first machines the cutting edge using the laser light traveling from the tip side of the cutting part22toward the root side of the cutting part22, and then machines the cutting edge using the laser light traveling from the root side of the cutting part22to the tip side of the cutting part22. As a result, a blunt (slightly less sharp) portion formed due to the previous cutting edge machining can be removed by the following cutting edge machining to form a sharp cutting edge22a.

The first optical path25and the second optical path26may change in direction of laser incident on the cutting edge22aby changing mirror angles. In the example shown inFIG. 5, the direction of laser incident on the cutting edge22acan be adjusted by changing arrangement angles of the reflection mirrors34,38. Further, in the above-described example, the laser light emitted from the single laser light source32is split into two rays of laser light by the beam splitter33, but laser light sources may be individually provided for the first optical path25and the second optical path26.

Cutting Apparatus Including Laser Unit16

The cutting edge machining apparatus10is equipped with the laser unit16that performs the cutting edge machining using the two rays of laser light, thereby eliminating the need for a rotation control axis for use in changing the tool orientation and allowing a simple structure. Proposed below is a structure where the laser unit16is built into a cutting apparatus that performs cutting process on a workpiece. Since the cutting apparatus is provided with the laser unit16, when the cutting edge22aof the cutting part22of the cutting tool21is worn, the cutting part22is moved to the laser unit16for laser-machining process without detaching the cutting tool21from the cutting apparatus, so that the cutting edge22acan be resharpened.

FIG. 6shows a cutting apparatus100that is  integrated with the laser unit16that laser-machines a cutting part of a cutting tool. The cutting apparatus100shown inFIG. 6is a machining apparatus that causes the cutting edge22aof the cutting tool21to cut into a workpiece104to turn the workpiece104. The cutting apparatus100includes an integrated part111and a controller117, and the controller117may be a numerical control (NC) control device that controls the integrated part111in accordance with an NC program. In the cutting apparatus100, the integrated part111and the controller117may be separately provided and be connected to each other by a cable or the like, or alternatively, may be integrated into a single device.

FIG. 7shows a top view of the integrated part111. The integrated part111includes a bed112serving as a base, and a first table113and a second table114are movably supported on the bed112. The first table113is supported movable in the X-axis direction by a rail provided on the bed112, and the second table114is supported movable in the Z-axis direction by a rail provided on the first table113. A tool post115to which the cutting tool21is attached is provided on an upper surface of the second table114. The cutting part22is fixed to the cutting tool21, and the cutting part22has the cutting edge22aprovided at a tip of the cutting part22, the cutting edge22ahaving the flank face and the rake face for use in cutting the workpiece.

Provided above the bed112are a spindle103to which the workpiece104is attached and a headstock102that supports the spindle103rotatable. Provided in the headstock102is a rotation mechanism105that rotates the spindle103. In order to cut the workpiece104, the controller117drives the rotation mechanism105to rotate the spindle103.

The first table113and the second table114serve as a motion mechanism that moves the cutting edge22aof the cutting tool21relative to the workpiece104. Although not shown, the first table113and the second table114are each driven by an actuator such as a motor. Note that, according to the embodiment, the first table113and the second table114move the cutting tool21attached to the tool post115in the X-axis direction and the Z-axis direction, but the cutting tool21only needs to be moved relative to the workpiece104. That is, the motion mechanism may move the workpiece104relative to the cutting tool21. As described above, it does not matter which of the cutting tool21and the workpiece104is moved as long as the relative movement in the movement direction is made.

FIGS. 8 and 9show a state where the cutting edge22aof the cutting tool21cuts into the workpiece104to cut the workpiece104. At the start of cutting process, the controller17rotates the rotation mechanism105and moves the second table114in the Z-axis positive direction to  cause the cutting edge22aof the cutting part22to cut into the workpiece104. The controller117controls the movements of the first table113and the second table114in accordance with the NC program for cutting process to regulate the relative movement between the cutting tool21and the workpiece104made by the motion mechanism to cut the workpiece104.

When cutting process with the cutting tool21is repeatedly performed in the cutting apparatus100, the cutting edge22ais sure to wear. Once the worn cutting tool21is detached from the cutting apparatus100and the cutting edge22ais resharpened with a dedicated machine tool, it is necessary to measure and correct, for position calibration, an attachment error, and the like when the cutting tool21is attached again to the cutting apparatus100.

Therefore, the integrated part111according to the embodiment includes, on the bed112, the laser unit16capable of irradiating the cutting edge22aof the cutting part22with two lays of laser light to sharpen the cutting edge22a. The laser unit16may be a pulse laser grinder that overlaps a cylindrical irradiation region including a focused spot of laser light with the flank face of the cutting edge22aand/or the rake face of the cutting edge22aand scans the cylindrical irradiation region in a direction intersecting an optical axis of the laser light to remove a surface region through which the cylindrical irradiation  region has passed, or alternatively, may be a laser machine tool that uses a different irradiation method. The controller117may estimate the degree of wear in the cutting edge22aby measuring the cutting time and the like and determine to resharpen (perform sharpening process on) the cutting edge22awhen the degree of wear exceeds a predetermined threshold.

FIGS. 10 and 11show a state where the cutting part22of the cutting tool21has entered the laser unit16. At the end of cutting process, the first table113is located at the position in the X-axis direction shown inFIG. 7. When determining to sharpen the cutting edge22a, the controller117moves the first table113in the X-axis negative direction to cause the cutting part22to face the opening31of the protective housing30(seeFIG. 5). Subsequently, the controller117moves the second table114in the Z-axis positive direction to put at least the tip side of the cutting tool21into the laser unit16through the opening31of the laser unit16. Then, the controller117drives the laser light source32in the laser unit16to cause the laser light source32to emit the laser light for use in machining the flank face of the cutting edge22aand the laser light for use in machining the rake face of the cutting edge22a. The sharpening process on the cutting edge22ais as described with reference toFIG. 5.

In the cutting apparatus100, the controller117causes the motion mechanism to put the tip side of the cutting tool21into the laser unit16while maintaining the cutting orientation of the cutting tool21and move the cutting tool21relative to the laser optical path to laser-machine the cutting edge22a. In the cutting apparatus100according to the embodiment, the laser unit16is capable of irradiating the cutting edge22awith two rays of laser light to sharpen the cutting edge22a, which eliminates the need for changing the orientation of the cutting tool21during sharpening process and allows laser-machining process using the translation control axis used for cutting process.

For example, in spherical/aspherical turning, a round cutting tool with an arc-shaped cutting edge22aare often used. During sharpening process on such a round cutting tool, referring toFIG. 5, the controller117may synchronously control the X-axis and Z-axis of the motion mechanism to move the cutting edge22arelative to the laser optical path along the arc-shaped cutting edge ridgeline.

Note that when the cutting apparatus100includes a rotation control axis corresponding to the B-axis, it is desirable that laser-machining process be performed by rotating, after irradiating the cutting edge22awith the laser light, the cutting edge22arelative to the laser optical path about the center of the arc of the cutting edge22aby B-axis control. Such machining allows, even when the intensity distribution of the laser light is not completely  axisymmetric, the entire area of the cutting edge22ato be machined at the same location in the circumferential direction of the laser light.

Although the case where the cutting apparatus100equipped with the laser unit16is a turning apparatus has been described above, the cutting apparatus100may be a different type of machining apparatus. A free-form surface machining apparatus creates a free-form surface on the workpiece attached to a work table, and the laser unit16may be provided side by side with the workpiece on the same work table. Note that it is also possible to fix the laser unit16to the bed12and separate the laser unit16from the work table. This is because the number of control axes for use in cutting process and the number of control axes for use in laser-machining process on the tool cutting edge need not necessarily be equal to each other.

Further, the cutting apparatus100may be an ultrasonic elliptical vibration cutting apparatus as disclosed in JP 2008-221427 A. Ultrasonic elliptical vibration cutting is a cutting method that enables ultra-precision fine cutting of high-hardness metals such as die steel.

FIG. 12shows a structure of an ultrasonic elliptical vibration cutting tool used in the ultrasonic elliptical vibration cutting apparatus. Since, in the cutting apparatus100, the laser unit16machines the cutting  edge22awith the laser light traveling from the root side of the cutting part22toward the tip side of the cutting part22without changing the cutting tool orientation, it is necessary to avoid interference between the laser light and a part of the cutting tool21other than the cutting edge22a, a jig part, and the like.

In the conventional ultrasonic elliptical vibration cutting tool, an ultrasonic vibrator is disposed on the extension line of the rake face, and when this ultrasonic elliptical vibration cutting tool is put into the laser unit16, the ultrasonic vibrator interferes with the laser light traveling from the root side of the cutting part22toward the tip side of the cutting part22. Therefore, for the ultrasonic elliptical vibration cutting tool mounted on the cutting apparatus100, an ultrasonic vibrator40is disposed in a region defined between the extension line of the rake face of the cutting edge22aand the extension line of the flank face of the cutting edge22a.

Note that the ultrasonic elliptical vibration cutting apparatus that uses the ultrasonic elliptical vibration cutting tool shown inFIG. 12requires a new control method for maintaining a vibration amplitude in a depth-of-cut direction constant, which is important for ultra-precision machining. This is because neither of the ultrasonic vibrations in two directions for use in generating elliptical vibrations coincides with the depth-of-cut  direction. Therefore, the controller117performs the control of automatically tracking a resonance frequency of one vibration or a frequency between resonance frequencies in the two directions (weighted average) and calculating at least the amplitude in the depth-of-cut direction to maintain the amplitude in the depth-of-cut direction constant, thereby suppressing changes in amount of depth-of-cut to achieve high machining accuracy.

The present disclosure has been described on the basis of the examples. It is to be understood by those skilled in the art that the examples are illustrative and that various modifications are possible for a combination of components or processes, and that such modifications are also within the scope of the present disclosure. According to the embodiment, the laser unit16in the cutting edge machining apparatus10emits two rays of laser light, but may emit three or more rays of laser light. On the other hand, when the finishing accuracy required for cutting is not high in the integrated part111of the cutting edge machining apparatus10, the laser unit16may use a single ray of laser light to machine, for example, only the flank face that highly affects the finishing accuracy of cutting process.

An outline of aspects of the present disclosure is as follows. A cutting edge machining apparatus according to one aspect of the present disclosure is structured to laser-machine a cutting part of a cutting tool and includes a  first optical member structured to form a first optical path of laser light, a second optical member structured to form a second optical path of laser light, a motion mechanism structured to move a cutting edge of the cutting part relative to the first optical path and the second optical path, and a controller structured to control relative movement made by the motion mechanism. The controller causes the motion mechanism to move the cutting edge relative to the first optical path to machine a flank face of the cutting edge with laser light passing through the first optical path. The controller further causes the motion mechanism to move the cutting edge relative to the second optical path to machine a rake face of the cutting edge with laser light passing through the second optical path.

Using the laser light that passes through two different optical paths to machine the flank face of the cutting edge and the rake face of the cutting edge brings about an advantage of eliminating the need for a mechanism that changes the tool orientation.

The controller may cause the motion mechanism to simultaneously move the cutting edge relative to the first optical path and the second optical path to simultaneously machine the flank face of the cutting edge and the rake face of the cutting edge. This makes it possible to shorten the laser-machining time. It is preferable that at least one of the rays of laser light passing through the first optical  path and the second optical path travel in a direction from a root side of the cutting part toward a tip side of the cutting part. In particular, in pulse laser grinding, high-precision machining can be achieved by causing the laser light to travel in the direction from the root side of the cutting part to the tip side of the cutting part. Note that it is preferable that both the rays of laser light passing through the first optical path and the second optical path each travel in the direction from the root side of the cutting part to the tip side of the cutting part.

Another aspect of the present disclosure is a cutting apparatus. This apparatus includes a motion mechanism structured to move a cutting edge of a cutting tool relative to a workpiece, and a controller structured to control movement, made by the motion mechanism, of the cutting edge of the cutting tool relative to the workpiece. The cutting apparatus further includes a laser light source structured to emit laser light for use in laser-machining the cutting edge of the cutting tool, and an optical member structured to form an optical path of laser light. The controller causes the motion mechanism to move the cutting edge relative to the optical path to laser-machine the cutting edge.

When the cutting apparatus has a laser-machining capability of sharpening a cutting part, it is possible to sharpen, when the cutting edge is worn, the cutting edge  without detaching the cutting tool from the cutting apparatus. It is preferable that the laser-machining capability allow the flank face of the cutting edge and the rake face of the cutting edge to be machined by using the laser light passing through two different optical paths. It is preferable that the controller cause the motion mechanism to move the cutting edge relative to the optical path while maintaining the cutting orientation of the cutting tool to laser-machine the cutting edge.