JP7574731B2 - Measuring Equipment - Google Patents

Description

The present invention relates to a measuring device.

Patent Document 1 describes a measuring device that measures the attachment position of cutting tools such as drills and end mills. The measuring device in Patent Document 1 includes a light-projecting unit and a light-receiving unit. The light-projecting unit irradiates a light beam toward the light-receiving unit. At this time, the tip of the tool is positioned between the light-projecting unit and the light-receiving unit. As a result, a shadow corresponding to the shape of the tip of the tool is projected onto the light-receiving unit. The measuring device in Patent Document 1 measures the attachment position of the tool relative to the spindle of the machine tool based on the position of the shadow projected onto the light-receiving unit.

JP 2007-185771 A

For example, as shown in FIG. 7, the drill 60 described in Patent Document 1 has two lands 70 and two grooves 80. Here, the direction in which the drill 60 rotates around the rotation axis 60A of the drill 60 during cutting processing is defined as a first rotation direction R1, and the opposite direction to the first rotation direction R1 is defined as a second rotation direction R2. The lands 70 and the grooves 80 are positioned alternately in the first rotation direction R1. Each land 70 extends in a spiral shape around the rotation axis 60A of the drill 60. The winding direction of each land 70 is the direction that proceeds in the second rotation direction R2 from the tip to the base end of the drill 60. The grooves 80 are the space between the lands 70.

As shown in FIG. 7, the land 70 has a cutting edge 71 and a clearance surface 72. The cutting edge 71 is an edge portion of the land 70 in the first rotation direction R1 when the tip of the drill 60 is viewed in a direction along the rotation axis 60A. Therefore, the cutting edge 71 extends outward from approximately the vicinity of the rotation axis 60A of the drill 60 so as to move away from the rotation axis 60A. The clearance surface 72 is a portion of the tip surface of the land 70 adjacent to the cutting edge 71. Therefore, the clearance surface 72 is adjacent to the cutting edge 71 in the second rotation direction R2. The inclination angle of the clearance surface 72 with respect to the rotation axis 60A of the drill 60 varies from place to place. Specifically, as shown in FIG. 8, the acute angle 75 formed by the clearance surface 72 and the rotation axis 60A of the drill 60 becomes smaller on the clearance surface 72 toward the second rotation direction R2. Although the above describes the drill 60, other cutting tools such as end mills also have flanks in a similar manner.

Now, for the tool described in Patent Document 1, for the purpose of inspection, etc., it is sometimes necessary to measure the magnitude of change in the acute angle 75 between the flank 72 and the rotation axis 60A, the so-called conical clearance angle EA, as shown in FIG. 8. Here, when the drill 60 is viewed from the side in a direction perpendicular to the direction in which the cutting edge 71 extends, a line perpendicular to the rotation axis 60A is defined as a virtual line K1. In addition, in the same side view, a tangent line drawn to the edge of the flank 72 at the intersection 73 between the base end side edge of the flank 72 and the cutting edge 71 is defined as a tangent line K2. For example, the conical clearance angle EA is expressed as an acute angle formed by the virtual line K1 and the tangent line K2. The measuring device in Patent Document 1 can only measure the mounting position of the tool relative to the spindle of the machine tool, but cannot measure the conical clearance angle EA.

The measuring device for solving the above problem is a measuring device for measuring the conical clearance angle of a cutting tool, and is equipped with a holder for rotatably holding the tool, a light-projecting unit for emitting a light beam, a light-receiving unit for receiving the light beam irradiated from the light-projecting unit, and a calculation unit for calculating the conical clearance angle. When the rotation axis of the holder is defined as a first axis, an axis perpendicular to the first axis is defined as a second axis, and an axis perpendicular to both the first axis and the second axis is defined as a third axis, the light-projecting unit irradiates a light beam in a direction along the third axis, and the light-receiving unit faces the light-projecting unit across the first axis. A first irradiation process in which the light-projecting unit irradiates a light beam to the light-receiving unit in a state in which the holder holds the tool so that the rotation axis of the tool coincides with the first axis, and a second irradiation process in which the holding state of the holder with respect to the tool is the same as that in the first irradiation process, are performed. The second irradiation process is performed in which the light projecting unit irradiates the light receiving unit with a light beam while the rotational position of the holder is the same as that of the first irradiation process, and is different from that of the first irradiation process; the first acquisition process is performed in which the calculation unit acquires, as a setback distance, a difference between a position in the direction along the first axis at a first specific point on the flank of the tool identified by the first irradiation process and a position in the direction along the first axis at a second specific point on the flank that is the same as that of the first specific point in the direction along the second axis, as identified by the second irradiation process; the second acquisition process is performed in which the calculation unit acquires, as a rotation angle, a difference between the rotational position of the holder during the first irradiation process and the rotational position of the holder during the second irradiation process; and the calculation unit calculates the conical clearance angle of the flank based on the setback distance and the rotational angle.

The conical clearance angle of the tool increases as the setback distance increases relative to the rotation angle. In other words, the conical clearance angle of the tool is uniquely determined by the setback distance and the rotation angle. Therefore, with the above configuration, the conical clearance angle of the tool can be calculated based on the acquired setback distance and rotation angle.

FIG. 4 is a flowchart showing a clearance angle measuring method. 5A to 5C are explanatory diagrams showing a pre-irradiation process and the like in the clearance angle measuring method. 5A to 5C are explanatory diagrams showing a first irradiation process and the like in the clearance angle measuring method. 5A to 5C are explanatory diagrams showing a rotation process and the like in the clearance angle measuring method. 11A to 11C are explanatory diagrams showing a second irradiation process and the like in the clearance angle measuring method. Front view of the drill. Side view of the drill.

<General configuration of measuring device>
An embodiment of the present invention will now be described with reference to Figures 1 to 6. First, a schematic configuration of a measuring device 10 will be described.

As shown in FIG. 1, the measuring device 10 includes a table 11, a tool rest 12, a support plate 13, and a holder 14. The shape of the table 11 is a substantially rectangular plate shape. In the following description, a specific axis along the main surface of the table 11 is defined as the X-axis XJ. The main surface is the outer surface of a plate-shaped member with the largest area. The axis along the main surface of the table 11 and perpendicular to the X-axis XJ is defined as the Y-axis YJ. Furthermore, the axis perpendicular to both the X-axis XJ and the Y-axis YJ is defined as the Z-axis ZJ. One of the two directions along the Z-axis ZJ is defined as the upward direction UD, and the opposite direction is defined as the downward direction DD. In this embodiment, the X-axis XJ corresponds to the first axis, the Y-axis YJ corresponds to the second axis, and the Z-axis ZJ corresponds to the third axis.

The tool rest 12 is located on the surface of the table 11 in the upward direction UD. The shape of the tool rest 12 is a substantially rectangular plate. The main surface of the tool rest 12 faces the main surface of the table 11. The tool rest 12 can move relative to the table 11 by a slider mechanism (not shown). The tool rest 12 can move relative to the table 11 in the direction along the X-axis XJ and the direction along the Y-axis YJ.

The support plate 13 is fixed to a surface of the tool rest 12 facing the upward direction UD. The shape of the support plate 13 is a substantially rectangular plate. The main surface of the support plate 13 faces in a direction along the X-axis line XJ. Therefore, the support plate 13 stands up from the tool rest 12.

The holder 14 is connected to the support plate 13. The holder 14 is substantially cylindrical. The holder 14 penetrates the support plate 13 in the direction along the X-axis XJ. Therefore, the rotation axis 14A of the holder 14 is parallel to the X-axis XJ. The holder 14 can rotate with respect to the support plate 13 around the rotation axis 14A of the holder 14. In the following description, the rotation axis 14A of the holder 14 is assumed to coincide with the X-axis XJ. In addition, one end of the holder 14 can hold a cutting tool. Therefore, the holder 14 rotatably holds a cutting tool. Examples of cutting tools include a drill 60 and an end mill. As described above, the tool rest 12 can move with respect to the table 11 in the direction along the X-axis XJ and the direction along the Y-axis YJ. Therefore, the holder 14, together with the tool rest 12 and the support plate 13, can move in the direction along the X-axis XJ and the direction along the Y-axis YJ.

The measuring device 10 includes a light-projecting unit 21, a light-receiving unit 22, and a first display 23. The light-projecting unit 21 is located on the downward direction DD side when viewed from the X-axis line XJ. The light-projecting unit 21 is also located directly below the end of the holder 14 that holds the tool. The light-projecting unit 21 emits a beam of light in the upward direction UD.

When viewed from the X-axis line XJ, the light receiving unit 22 is located on the opposite side to the light projecting unit 21, i.e., on the upward direction UD side. The light receiving unit 22 receives the light beam emitted from the light projecting unit 21. The light receiving unit 22 and the light projecting unit 21 face each other across the X-axis line XJ.

The first display 23 is connected to the light receiving unit 22. The first display 23 displays the shadow of the tool projected onto the light receiving unit 22. As shown in FIG. 3, the first display 23 displays a virtual line X1 along the X-axis line XJ, a virtual line Y1 along the Y-axis line YJ, and an origin 25 as the intersection of these virtual lines X1 and Y1. These virtual lines X1, Y1, and origin 25 serve as references for direction and position on the first display 23.

1, the measuring device 10 includes an X-axis detection sensor 31, a Y-axis detection sensor 32, a rotational position detection sensor 33, a calculation unit 41, an input device 42, and a second display 43. The X-axis detection sensor 31 is built into a slider mechanism for sliding the tool rest 12. The X-axis detection sensor 31 detects the position of the holder 14 relative to the table 11 in the direction along the X-axis line XJ as an X-axis value XV. The Y-axis detection sensor 32 is built into a slider mechanism for sliding the tool rest 12. The Y-axis detection sensor 32 detects the position of the holder 14 relative to the table 11 in the direction along the Y-axis line YJ as a Y-axis value YV. The rotational position detection sensor 33 is connected to the holder 14. The rotational position detection sensor 33 detects the rotational position RV of the holder 14 relative to the support plate 13. The rotational position RV changes within a range of 0 degrees to less than 360 degrees, with the reference rotational position being 0 degrees. In other words, when the holder 14 rotates once, the rotational position RV returns to its original value. An example of the rotational position detection sensor 33 is a rotary encoder.

The calculation unit 41 acquires a signal indicating the X-axis value XV from the X-axis detection sensor 31. The calculation unit 41 acquires a signal indicating the Y-axis value YV from the Y-axis detection sensor 32. The calculation unit 41 acquires a signal indicating the rotational position RV from the rotational position detection sensor 33.

The input device 42 is connected to the calculation unit 41. The input device 42 is a device for inputting commands, etc. from the worker who operates the input device 42 to the calculation unit 41. An example of the input device 42 is a keyboard. The second display 43 is connected to the calculation unit 41. The second display 43 is a device that displays various types of information.

The calculation unit 41 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The calculation unit 41 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that are configured to cause the CPU to execute the processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

<How to measure clearance angle>
Next, a clearance angle measuring method for measuring the conical clearance angle EA using the measuring device 10 will be described. The drill 60 to be measured includes a land 70 and a groove portion 80. The land 70 includes a cutting edge 71 and a clearance surface 72. The configuration of the drill 60 is the same as that of the conventional technology described above, and therefore a detailed description thereof will be omitted.

As shown in FIG. 2, the clearance angle measurement method includes a process of step S11. In step S11, the operator holds the drill 60. As a specific example, the operator inserts the drill 60 into the holder 14. At this time, the operator aligns the rotation axis 60A of the drill 60 with the rotation axis 14A of the holder 14, i.e., with the X-axis XJ. In addition, the operator rotates the holder 14 so that the cutting edge 71 of the drill 60 is perpendicular to the Z-axis ZJ when the drill 60 is viewed from a direction along the X-axis XJ. Then, the process proceeds to step S20.

As shown in FIG. 2, in step S20, the operator executes a pre-movement process. As a specific example, the operator slides the tool post 12. At this time, as shown in FIG. 3, the rotation axis 60A of the drill 60 is aligned with the origin 25 of the first display 23 in the direction along the Y-axis YJ. Then, the process proceeds to step S21.

As shown in FIG. 2, in step S21, the measuring device 10 executes a pre-irradiation process. Specifically, as shown in FIG. 3, with the rotation axis 60A of the drill 60 positioned between the light-projecting unit 21 and the light-receiving unit 22, the light-projecting unit 21 irradiates a light beam onto the light-receiving unit 22. Then, the process proceeds to step S22.

As shown in FIG. 2, in step S22, the operator executes a reset process for the Y-axis value YV. As a specific example, the operator operates the input device 42 to reset the value of the Y-axis value YV at the time of the process of step S22 to "0". After that, the process proceeds to step S30.

As shown in FIG. 2, in step S30, the operator executes a first movement process. As a specific example, the operator slides the tool post 12. At this time, as shown in FIG. 4, an arbitrary point on the flank surface 72 of the drill 60 is aligned with the origin 25 of the first display 23 in the direction along the X-axis line XJ and the direction along the Y-axis line YJ. The arbitrary point determined at this time is the first specific location T1. After that, the process proceeds to step S31.

As shown in FIG. 2, in step S31, the measuring device 10 executes a first irradiation process. Specifically, as shown in FIG. 4, with the flank 72 of the drill 60 positioned between the light projecting unit 21 and the light receiving unit 22, the light projecting unit 21 irradiates a light beam onto the light receiving unit 22. This first irradiation process identifies the position of the first specific point T1 on the flank 72 of the drill 60 in the direction along the X-axis XJ. Note that in the first irradiation process, the holder 14 holds the drill 60 so that the rotation axis 60A of the drill 60 coincides with the X-axis XJ. Then, the process proceeds to step S32.

As shown in FIG. 2, in step S32, the worker executes a reset process of the X-axis value XV. As a specific example, the worker operates the input device 42 to reset the value of the X-axis value XV at the time of the processing of step S32 to "0". Through the processing of step S32, the position in the direction along the X-axis line XJ at the first specific location T1 identified in the first irradiation processing of step S31 is defined as "0". After that, the processing proceeds to step S33.

In step S33, the operator executes a process of resetting the rotational position RV. As a specific example, the operator operates the input device 42 to reset the value of the rotational position RV at the time of the process of step S33 to "0." In other words, the rotational position RV of the holder 14 during the first irradiation process is defined as "0." Then, the process proceeds to step S41.

2, in step S41, the operator executes a rotation process of the holder 14. As a specific example, the operator grips the holder 14 and rotates the holder 14 in the first rotation direction R1 to change the rotation position RV of the holder 14. At this time, as shown by the dashed line in FIG. 5, the shadow angle 75B of the acute angle 75 formed by the flank 72 of the drill 60 and the rotation axis 60A of the drill 60 becomes smaller than the shadow angle 75A of the acute angle 75 before rotation shown by the solid line in FIG. 5. As a result, the flank 72 of the drill 60 is displaced from the origin 25 of the first display 23 in the direction along the X-axis XJ. An example of the angle by which the holder 14 is rotated in step S41 is about 10 degrees. Then, the process proceeds to step S50.

2, in step S50, the operator executes the second movement process. As a specific example, the operator slides the tool post 12 in the direction along the X-axis XJ. At this time, as shown in FIG. 6, the flank 72 of the drill 60 is aligned with the origin 25 of the first display 23 in the direction along the X-axis XJ. At this time, the operator does not slide the tool post 12 in the direction along the Y-axis YJ. The point on the flank 72 that is aligned with the origin 25 is the second specific point T2. As described above, in step S50, the tool post 12 is not slid in the direction along the Y-axis YJ. Therefore, the second specific point T2 is in the same position as the first specific point T1 in the direction along the Y-axis YJ. Then, the process proceeds to step S51.

2, in step S51, the measuring device 10 executes the second irradiation process. Specifically, as shown in FIG. 6, in a state in which the flank 72 of the drill 60 is positioned between the light projecting unit 21 and the light receiving unit 22, the light projecting unit 21 irradiates the light receiving unit 22 with a beam. At this time, the holding state of the holder 14 with respect to the drill 60 is the same as the holding state of the holder 14 with respect to the drill 60 at the time of processing in step S31. Also, the rotational position RV of the holder 14 is in a state different from the rotational position RV of the holder 14 at the time of processing in step S31. That is, in the second irradiation process, the holding state of the holder 14 with respect to the drill 60 is the same as in the first irradiation process, and the rotational position RV of the holder 14 is in a state different from the first irradiation process. This second irradiation process identifies the position in the direction along the X-axis XJ at the second specific point T2 on the flank 72 of the drill 60. Then, the process proceeds to step S61.

As shown in FIG. 2, in step S61, the measuring device 10 executes a first acquisition process. As a specific example, the calculation unit 41 acquires the value of the X-axis value XV at the time of processing in step S61 as the retreat distance D1. Here, the X-axis value XV at the time of processing in step S61 is a value indicating the amount of change since the value of the X-axis value XV was reset to "0" in step S32. Therefore, the X-axis value XV at the time of processing in step S61 can be treated as the difference between the position in the direction along the X-axis line XJ at the first specific location T1 and the position in the direction along the X-axis line XJ at the second specific location T2, that is, the retreat distance D1. Note that FIG. 5 illustrates an example of the retreat distance D1. Then, the process proceeds to step S62.

As shown in FIG. 2, in step S62, the measurement device 10 executes the second acquisition process. As a specific example, the calculation unit 41 acquires the value of the rotational position RV at the time of processing step S62 as the rotational angle D2. Here, the rotational position RV at the time of processing step S62 corresponds to the rotational position RV of the holder 14 at the time of the second irradiation process. Furthermore, the rotational position RV at the time of processing step S62 is a value indicating the amount of change since the value of the rotational position RV was reset to "0" in step S33. Therefore, the rotational position RV at the time of processing step S62 can be treated as the difference between the rotational position RV of the holder 14 at the time of the first irradiation process and the rotational position RV of the holder 14 at the time of the second irradiation process, that is, the rotational angle D2. Then, the process proceeds to step S63.

In step S63, the measuring device 10 executes an acquisition process to acquire the tool radius D3 of the drill 60. As a specific example, the calculation unit 41 acquires the value of the Y-axis value YV at the time of processing in step S63 as the tool radius D3 of the drill 60. In this embodiment, the Y-axis value YV at the time of processing in step S63 is a value indicating the amount of change since the value of the Y-axis value YV was reset to "0" in step S22. Therefore, the Y-axis value YV at the time of processing in step S63 can be treated as the tool radius D3 of the drill 60. Note that the tool radius D3 of the drill 60 is the same as the value of the Y-axis value YV of the first specific location T1 and the second specific location T2 described above. Also, FIG. 5 illustrates an example of the tool radius D3. Then, the process proceeds to step S64.

As shown in FIG. 2, in step S64, the measuring device 10 executes an acquisition process to acquire the travel distance D4. Here, FIG. 7 illustrates an example of the first specific location T1 and the second specific location T2. At this time, the travel distance D4 is the distance of an arc from the first specific location T1 to the second specific location T2, among the arcs centered on the rotation axis 60A that passes through the first specific location T1 and the second specific location T2, when the drill 60 is viewed from a direction along the X-axis line XJ, as shown in FIG. 7. The calculation unit 41 calculates the travel distance D4 based on the tool radius D3 and the rotation angle D2. For example, the calculation unit 41 calculates the travel distance D4 using the following formula.

Formula (1): D4=D3×tanD2
The moving distance D4 calculated from the above formula (1) is slightly different from the actual moving distance D4. However, when the rotation angle D2 is small, the error is extremely small, so the above formula (1) ) is used. Then, the process proceeds to step S65.

As shown in FIG. 2, in step S65, the measuring device 10 executes an acquisition process to acquire the conical clearance angle EA of the drill 60. Specifically, the calculation unit 41 calculates the conical clearance angle EA based on the retreat distance D1 and the movement distance D4. For example, the calculation unit 41 calculates the conical clearance angle EA using the following formula:

Formula (2): EA=arctan(D1/D4)
As described above, in the process of step S64, the moving distance D4 is calculated based on the rotation angle D2. Therefore, in the processes of steps S64 and S65, the cone relief angle EA is calculated based on the retraction distance D1 and the rotation angle D2. After that, the process proceeds to step S66.

In step S66, a display process is executed to display the conical clearance angle EA of the drill 60. As a specific example, the calculation unit 41 outputs a signal indicating the conical clearance angle EA calculated in the process of step S65 to the second display 43. Then, the second display 43 displays the conical clearance angle EA.

<Action of this embodiment>
When the moving distance D4 according to the rotation angle D2 is the same, the conical clearance angle EA increases as the setback distance D1 increases. Also, when the setback distance D1 is the same, the conical clearance angle EA increases as the moving distance D4 according to the rotation angle D2 decreases. In other words, the conical clearance angle EA increases as the setback distance D1 increases with respect to the rotation angle D2. In other words, the conical clearance angle EA is uniquely determined by the rotation angle D2 and the setback distance D1.

<Effects of this embodiment>
(1) In this embodiment, the calculation unit 41 acquires the setback distance D1 through a first acquisition process. The calculation unit 41 also acquires the rotation angle D2 through a second acquisition process. The calculation unit 41 then calculates the conical clearance angle EA based on the acquired setback distance D1 and rotation angle D2. Therefore, in this embodiment, the conical clearance angle EA can be calculated using the measurement device 10.

(2) In this embodiment, the shadow of the drill 60 projected onto the light receiving unit 22 is displayed on the first display 23. Therefore, even if the diameter of the drill 60 is small, for example, by enlarging and displaying the shadow of the drill 60 on the first display 23, it is easy to match any point on the clearance surface 72 of the drill 60 with the origin 25 of the first display 23 with high accuracy. This is expected to improve the measurement accuracy of the conical clearance angle EA.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

- In the above embodiment, the processing content of the clearance angle measurement method may be changed. For example, the processing of steps S20 to S22 may be omitted. As a specific example, when the conical clearance angle EA of multiple drills 60 is measured using the clearance angle measurement method, even if the type of drill 60 is changed, the rotation axis 60A of the drill 60 generally coincides with the rotation axis 14A of the holder 14. Therefore, if the processing of steps S20 to S22 is performed in the initial clearance angle measurement method, the processing of steps S20 to S22 may be omitted in subsequent clearance angle measurement methods.

- For example, the process of step S64 may be changed. Specifically, the above formula (1) used in step S64 is an example of a formula for calculating the travel distance D4, and the formula for calculating the travel distance D4 may be changed.

For example, the process of step S65 may be changed. Specifically, the calculation unit 41 may calculate the cone clearance angle EA using the following formula instead of the above formula (2).
Formula (3): EA=arctan(D1/(D3×tanD2))
That is, the above formula (2) is one example of a formula for calculating the conical clearance angle EA, and the formula for calculating the conical clearance angle EA may be changed as long as it is based on the setback distance D1 and the rotation angle D2. In this configuration, the process of step S64 can be omitted.

- In the above embodiment, the entity that executes the processes in the clearance angle measurement method may be changed. For example, the processes that were previously performed by an operator may be executed by the measuring device 10. As a specific example, if the measuring device 10 is equipped with an electric motor that rotates the holder 14, in step S41, the measuring device 10 may rotate the holder 14 using the electric motor.

-Also, for example, some of the processes performed by the measuring device 10 may be performed by an operator. As a specific example, when the measuring device 10 performs the first acquisition process, the operator calculates the setback distance D1 using a calculator or the like. The operator also inputs the calculated setback distance D1 by operating the input device 42. Then, in the first acquisition process, the measuring device 10 may acquire the setback distance D1 input by the operator. In other words, in the clearance angle measurement method, it is sufficient that the measuring device 10 is involved in some of the multiple processes.

D1...Retraction distance D2...Rotation angle D3...Tool radius D4...Travel distance EA...Cone clearance angle XJ...X-axis YJ...Y-axis ZJ...Z-axis 10...Measuring device 11...Table 12...Tool rest 13...Support plate 14...Holder 14A...Rotation axis 21...Light projecting unit 22...Light receiving unit 23...First display 25...Origin 31...X-axis detection sensor 32...Y-axis detection sensor 33...Rotation position detection sensor 41...Calculation unit 42...Input device 43...Second display 60...Drill 60A...Rotation axis 70...Land 71...Cutting edge 72...Relief surface 80...Groove portion

Claims (1)

A measuring device for measuring a conical clearance angle of a cutting tool, comprising:
A holder that rotatably holds the tool;
A light projecting unit that projects a light beam;
a light receiving unit that receives the light beam emitted from the light projecting unit;
A calculation unit that calculates the cone clearance angle,
When a rotation axis of the holder is defined as a first axis, an axis perpendicular to the first axis is defined as a second axis, and an axis perpendicular to both the first axis and the second axis is defined as a third axis,
The light projecting unit projects a light beam in a direction along the third axis,
The light receiving portion faces the light projecting portion across the first axis,
a first irradiation process in which the light projecting unit irradiates a light beam to the light receiving unit while the holder holds the tool such that a rotation axis of the tool coincides with the first axis;
a second irradiation process in which the light projecting unit irradiates the light receiving unit with a light beam while the holding state of the holder with respect to the tool is the same as that of the first irradiation process and while the rotational position of the holder is different from that of the first irradiation process;
a first acquisition process in which the calculation unit acquires, as a retraction distance, a difference between a position in a direction along the first axis at a first specific point on the flank of the tool, which is identified by the first irradiation process, and a position in a direction along the first axis at a second specific point on the flank that is located at the same position as the first specific point on the flank in the direction along the second axis, which is identified by the second irradiation process;
a second acquisition process in which the calculation unit acquires a difference between a rotational position of the holder during the first irradiation process and a rotational position of the holder during the second irradiation process as a rotation angle;
a calculation process in which the calculation unit calculates the conical relief angle of the relief face based on the setback distance and the rotation angle.