JPH033756A - Measuring device for notch depth of rotating cutting tool - Google Patents

Abstract

PURPOSE:To correctly measure an actual notch depth at cutting time by detecting the azimuth of a rotating cutting tool while in contact based on the contact signal of an outer peripheral edge and the material to be cut and providing a means for deciding the notch depth on the mateirlal to be cut based on this azimuth and the diameter dimension of the rotating cutting tool. CONSTITUTION:When the contact of the outer peripheral edge 30 of a rotating cutting tool 26 and the material 10 to be cut at cutting time is detected by contact detection means (52, 54), the azimuth of the rotating cutting tool 26 while the outer peripheral edge 30 is brought into contact with the material 60 to be cut is detected by azimuth detection means (50, 56) based on this contact signal. The notch depth on the material 10 to be cut is decided by a depth deciding means 58 based on this detected azimuth and the diameter dimension of the tool 26.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for measuring the depth of cut of a rotary cutting tool into a workpiece.

Conventional technology and its problems Rotary cutting tools, such as milling cutters, have been widely used in the past, where the peripheral cutting edge intermittently cuts into the surface of the workpiece by being rotatably driven by being attached to a spindle to perform TA cutting. . Conventionally, the depth of cut of such a rotary cutting tool into the workpiece is only set based on the relative positional relationship between the spindle and the workpiece using an NC table, etc.; No depth measurements were made. For this reason, for example, when the dimensions of the workpiece vary or the surface of the workpiece has gentle irregularities, there is a problem that machining cannot be performed to a desired depth of cut. In addition, since the actual depth of cut is unknown, there are also problems in that it is impossible to judge whether the machining is good or bad unless it is inspected after machining.

The present invention was made against the background of the following two circumstances, and its purpose is to provide a depth of cut measuring device that measures the actual depth of cut during cutting.

Means for Solving the Problems In order to achieve the object, the present invention provides a rotary cutting method in which a peripheral blade intermittently cuts into the surface of a workpiece by being attached to a main shaft and driven to rotate. A device for measuring the depth of cut into the work material in a tool, the device comprising: (a) contact detection means for detecting contact between the peripheral blade and the work material and outputting a contact signal representing the contact; , (b) a rotation angle detection means for detecting the rotation angle of the rotary cutting tool while the peripheral blade is in contact with the workpiece based on the contact signal; and (C) the rotation angle and the rotation. The method further includes a depth determining means for determining the depth of cut into the work material based on the diameter of the cutting tool.

Function: In such a depth of cut measuring device, when the rotary cutting tool is driven to rotate and cutting is performed on the workpiece, it is possible to determine whether or not the peripheral edge of the rotary cutting tool is in contact with the workpiece. The contact detection means detects the contact and outputs a contact signal representing the contact, and the rotation angle detection means determines the rotation angle of the rotary cutting tool while the peripheral blade is in contact with the workpiece based on the contact signal. Detected.

The contact between the peripheral blade and the work material means that the peripheral blade is cutting the work material,
When the rotary cutting tool is relatively moved in a direction approximately parallel to the surface of the workpiece and cutting is performed along that surface, the depth of cut is determined after the peripheral cutting edge contacts the surface of the workpiece. The contact period is the period until the rotation angle becomes the deepest, and the rotation angle detected by the rotation angle detection means is the angle θ during that period. Note that since the position where the peripheral blade has the deepest cutting depth into the work material can be detected from the positional relationship between the rotary cutting tool and the work material, the contact detection means detects the movement of the peripheral blade during cutting. If the direction and the direction of relative movement of the workpiece are the same, it is sufficient to detect at least the start of contact between the peripheral blade and the workpiece, and the direction of movement of the peripheral blade and the direction of relative movement of the workpiece during cutting are In the opposite case, it is sufficient to be able to detect at least the end of contact between the peripheral cutter and the workpiece.

Additionally, when the rotary cutting tool is moved relative to the surface of the workpiece in a direction perpendicular to it and the depth of cut into the workpiece gradually increases, the peripheral cutting edge cuts into the surface of the workpiece. The contact period is the period from when it is pulled out until it is pulled out, and the rotation angle detected by the rotation angle detection means is 2θ, which is twice the above-mentioned angle θ.

Then, the depth of cut into the workpiece is determined by the depth determining means based on the rotation angle θ or 2θ and the diameter dimension of the rotary cutting tool. When the radius of the cutting tool is R, the depth of cut d is calculated according to the following equation (1).

d=R(1-cos θ) −・−(])
Note that the cutting depth determining means does not necessarily need to perform such calculations to calculate the cutting depth d, but reads the cutting depth d corresponding to the rotation angles θ and 2θ from a pre-stored data map, etc. There is no harm in doing so.

In addition, if the peripheral edge is twisted, it is desirable to determine the cutting depth d by considering the helix angle and the width of the workpiece. It is also possible to determine the depth of cut in consideration of the conditions.

Effects of the Invention As described above, according to the depth of cut measuring device of the present invention, the actual depth of cut can be measured during cutting. Even if there are irregularities, it is possible to perform machining at the desired depth of cut by controlling the relative position between the rotary cutting tool and the workpiece based on the measured depth of cut. become able to. Furthermore, the depth of cut measuring device of the present invention can be used for various purposes, such as determining the quality of machining at the same time as cutting by monitoring the actual depth of cut using the depth of cut measuring device described above. obtain.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic configuration diagram of an automatic eaves removal device, and numeral 10 is a bar-shaped material having a circular cross section, such as a billet I-, which is an intermediate product obtained by rolling or the like on a steel material.

This rod-shaped material 10 corresponds to a work material, and as shown in FIG. 2, there are long surface flaws 14 mainly in the longitudinal direction caused by rolling rollers etc. on its surface.
During the process of being sent to the right in FIG. 1 by a moving device (not shown), the pressure detection means 18 is disposed along the feeding path.
Then, the surface flaws 14 are removed by the flaw removing means 20.

The pressure detection means 18 is composed of, for example, an eddy current flaw detector that is driven to rotate around the bar 10, and detects the surface flaw 14 existing on the bar 10, and determines the position of the flaw and the flaw in the circumferential direction. A flaw signal SK representing the depth is output to the flaw removing means 20. FIG. 3 is a diagram showing an example of such a flaw signal SK, where the flaw position in the circumferential direction is expressed by an angle α° from a predetermined reference position, and the magnitude of the signal intensity indicates the flaw depth. represents. In addition, such a flaw signal SK is periodically output for a certain period of time depending on the length of the surface flaw 14 in the axial direction in relation to the rotational speed of the pressure detection means 18 and the feeding speed of the rod-like material 10. .

The flaw removing means 20, as shown in FIG.
A rotating disk 24 is rotatably disposed on a fixed frame (not shown) and is rotationally driven by a rotation driving means 22 such as a motor, and a circular hole is formed at the center of rotation of the rotating disk 24. The rod-shaped member 10 is configured to be able to travel along its rotation center line in the longitudinal direction. A milling cutter 26 and a receiver roller 28 are disposed on the rotating disk 24 with the center of rotation thereof sandwiched therebetween. The milling cutter 26 constitutes the rotary cutting tool of this embodiment, and is equipped with four outer circumferential blades 30 composed of chips or the like, and is mounted on the main shaft 34 of the drive motor 32 to cut the rotating disk 24. It is designed to be rotated around an axis perpendicular to the rotation center line. The drive motor 32 is disposed on the slider 36, and the milling cutter 26 is moved from the rotating disk 2 by a milling cutter drive means 38 consisting of a drive cylinder or an electric motor, a feed screw, etc.
4, it is linearly reciprocated in the vertical direction of FIG. 4 so as to approach and separate from the rotation center of FIG. Further, the roller 28 of the bearing has a ■-shaped bearing surface 41 on the outer periphery, and the rotating disk 28
The rotating disk 24 is rotated by a roller driving means 42, which is rotatably disposed on the slider 40 about an axis perpendicular to the rotational center line and parallel to the main shaft 34, and is composed of a driving cylinder or an electric motor, a feed screw, etc. It is linearly reciprocated in the vertical direction in FIG. 4 so as to move toward and away from the center.

Said rotation drive means 22. The milling drive means 38 and the roller drive means 42 are each driven according to a drive signal DD DF DR supplied from a control device 44. The control device 44 is supplied with the flaw signal SK output from the pressure detecting means 18, and is configured to control the preset distance between the pressure detecting means 18 and the flaw removing means 20, and the flaw signal SK outputted from the pressure detecting means 18. Based on the feed rate of the rod-shaped material 10, the diameter of the rod-shaped material 10, the rotational speed of the pressure detection means 18, etc., which are measured by a measuring device that does not have the same or set in advance,
The driving signals DDDF and DR are outputted so that when a portion having a surface flaw 14 reaches the flaw removing means 20, the surface flaw 14 is cut away by the milling cutter 26.

Specifically, when the flaw signal SK is supplied from the pressure detection means 18 to the control device 44, the drive signal DD is first transmitted to the rotational drive means 22 based on the feeding speed of the rod-shaped material 10 and the flaw position represented by the flaw signal SK. The flaw signal SK is output to
A milling cutter 2 is placed at the flaw position in the circumferential direction of the rod-shaped material 10 represented by
The rotary disk 24 is rotated and positioned so that 6 is located. The rotary disk 24 can be rotated within a range of 180 degrees in both forward and reverse directions from a predetermined reference position corresponding to the reference position of the flaw signal SK. The angle α° of the flaw position represented is 180°
In the following cases, the rotating disk 24 is rotated about its center of rotation by an angle α°, and the rotating disk 24 is rotated to a rotational position where the milling chair 26 faces the surface flaw 14, as shown in FIG. is positioned. Also, if the angle α° is larger than 180°,
The rotary disk 24 is rotated by (360-α) degrees in the opposite direction and positioned.

Next, a drive signal DF is output to the milling cutter drive means 38 based on the feed rate and diameter of the bar 10, the flaw depth represented by the original signal SK, etc. Based on the drive signal DR, the roller drive means 4
2, and when the area where the surface i14 is present approaches the flaw removing means 20, the milling cutter 26 receives a target determined according to the flaw depth represented by the original signal SK, as shown in FIG. The bar 10 is advanced so that cutting is performed on the outer circumferential surface of the bar 10 at a depth of cut D, while the roller 28 is advanced to a position where the V-shaped receiver surface 41 contacts the outer circumferential surface of the bar 10. I am made to do so. The target cutting depth D is determined to be, for example, approximately 0°5 mm deeper than the flaw depth represented by the original signal SK, and is determined to be a dimension that completely removes the surface flaw 14, and is determined to be approximately 0.5 mm deeper than the flaw depth represented by the original signal SK, and the center line of rotation of the rotary disk 24 is The outer circumferential blade 30 of the milling cutter 26 intermittently cuts into the outer circumferential surface of the rod-shaped material 10 being fed, and cutting is performed at a target cutting depth D.

Further, the drive signals DF and DR are applied to the target depth of cut D by the cutting length determined based on the original signal SK which is periodically supplied according to the length of the surface flaw (4). The milling cutter driving means 380 is outputted to the driving means 42 so that cutting is performed on the outer circumferential surface of the bar-shaped material 10. The cutting length is determined to be longer in the axial direction of the bar-shaped material 10 by a certain amount than the flaw length of the surface flaw 14, and the milling cutter 26 and the receiving roller 28 approach the bar-shaped material 10. After the bar-shaped material 10 is fed in the axial direction by the cutting length and the cutting process is performed, the milling cutter 26 and the roller 28 are rotated by the rotation of the rotating disk 24. It is moved back in a direction away from the center, thereby completely cutting out the surface flaw 14 over its entire length. The milling cutter 26 is rotationally driven counterclockwise in FIG. 6 so that the moving direction of the outer peripheral blade 30 during cutting is 1 2 the same as the feeding direction of the bar-shaped material 10.

Here, since the rod-shaped material 10 is an intermediate product such as a billet obtained by rolling, etc., it is not necessarily straight, its diameter also varies, and its roundness accuracy is not necessarily high. . For this reason, the actual cutting depth d of the cutting process by the milling cutter 26 does not necessarily match the target cutting depth D, and in the conventional automatic eaves removal device, surface flaws 14 may remain.
In this embodiment, the actual cutting depth d is measured and the forward position of the second milling cutter 26 is feedback-controlled so that it matches the target cutting depth D. The configuration for performing this feedback control will be described below.

First, the drive motor 3 rotates the milling cutter 26.
An optical rotary encoder 50 is provided at 2, and outputs a rotation signal SR that generates pulses as the main shaft 34 rotates. Further, a ring sensor 5 having a ring-shaped excitation coil is arranged around the main shaft 34 of the drive motor 32.
2 is provided, and excitation current is supplied from the control amplifier 54. The control amplifier 54 operates when the outer circumferential cutter 30 of the milling cutter 26 comes into contact with the rod-shaped material 10 and the main shaft 34. Milling cutter 26. By forming an electrical closed circuit passing through the rod-shaped material 10 and the receiving roller 28, when a weak high-frequency current is excited in the closed circuit based on the excitation of the ring sensor 52, the peripheral blade 30 and the rod-shaped A contact signal ST is output without indicating contact with the material 10.

Here, since the peripheral blade 30 and the bar-shaped material 10 are brought into contact only while the peripheral blade 30 is cutting the bar-shaped material 10, in this embodiment, the peripheral blade 30 is connected to the bar-shaped material 10. The contact signal S'F is generated only during the period from when the cutting edge 30 contacts the outer circumferential surface until the cutting depth becomes the deepest, that is, while the outer circumferential cutter 30 is located within the range of angle θ in FIG. It will be output. An example of this contact signal ST and the rotation signal SR is shown in FIG. In this embodiment, the ring sensor 52 and the control 4 amplifier 54 constitute contact detection means.

The contact signal ST and rotation signal SR are then supplied to the rotation angle detector 56. This rotation angle detector 5
6 is for detecting the rotation angle of the milling cutter 26 while the peripheral cutter 30 and the bar-shaped material 10 are in contact with each other, that is, the angle θ, and includes, for example, an AND circuit and a counter; The rotation angle θ is determined by counting the number of pulses of the rotation signal SR supplied while the signal ST is in the ON state. Specifically, P is the number of pulses of the rotation signal SR supplied while the contact signal ST is in the ON state.
a. If the number of pulses per rotation of the milling cutter 26 is pb, then the rotation angle θ (°) can be obtained according to the following equation (2). The above pulse number P1] is set in advance. This rotation angle detector 56 is connected to the rotary encoder 50.
Together, they constitute rotation angle detection means.

θ-360xPa/pb (2) The rotation angle detector 56 outputs a rotation angle signal Sθ representing the rotation angle θ to the depth calculation circuit 58. Sθ does not represent the rotation angle θ,
The actual depth of cut d is calculated based on the preset radius R to the cutting edge of the peripheral cutter 30 according to the equation (1). Then, the depth calculation circuit 58 outputs a depth signal Sd representing the depth of cut d to the control device 44, and the control device 44 outputs the depth signal Sd indicating the depth of cut d to the target cut depth D. The milling cutter drive means 38 is controlled in a feed bank manner so as to match the above. The depth calculation circuit 58 corresponds to depth determining means.

Therefore, even if there are variations in the diameter of the rod-shaped material 10, the actual cutting depth d of the milling cutter 26 can be made to substantially match the target cutting depth D, and the surface flaws 14 can always be reliably removed.
It becomes possible to cut and remove the . Moreover, for this reason, it is possible to reduce the increase in the target cutting depth D with respect to the flaw depth of the surface flaw 14 represented by the flaw signal SK, and the thinning of the bar-shaped material 10 due to flaw removal processing can be reduced. I can do it.

5 6 Although such an automatic flaw removing device generally uses a grinder to remove surface flaws 14 by grinding, in this embodiment, a milling cutter 26 is used to remove the flaws. , it has the advantage of high machining efficiency, easy disposal of cutting waste, and maintaining a good working environment. Furthermore, since the milling cutter 26 is used in this way, it becomes possible to measure the depth of cut as described above, and various advantages can be obtained compared to the case where a grinder is used.

Next, another embodiment of the present invention will be described. In the following embodiments, parts common to those in the above embodiments are designated by the same reference numerals, and explanations thereof will be omitted.

In Figures 8 and 9, the cross section of the workpiece is 150 m.
This is a diagram showing a flaw removing means 62 for removing defects from a square piece 60 such as a billet having a square shape of about 150 mm in diameter. , it is rotated by a rotating device (not shown) so that the surface on which the surface flaw is present faces upward. The flaw removing means 62 is equipped with a milling cutter 66 as a rotary cutting tool which is rotatably driven by the drive motor 32, and the milling cutter 66 has 12 peripheral blades 6B formed of chips etc. on the outer peripheral surface at a 30° angle. are provided at intervals. The drive motor 32 is moved by a moving device (not shown) in the left and right directions in FIG. As a result, the peripheral blade 68 intermittently cuts into the parts of the square timber 60 where flaws exist to perform flaw removal processing. The peripheral blade 68 has a trapezoidal shape, and the width of its tip is set to about 15 mm to accommodate normal flaws. Surface flaws are removed by cutting shallow grooves on the surface of the square timber 60. do. The milling cutter 66 is rotationally driven counterclockwise in FIG. 9 so that the moving direction of the outer peripheral blade 68 during cutting is the same direction as the feeding direction of the square material 60.

The drive motor 32 is provided with the ring sensor 52 and a control amplifier 54 so as to output a contact signal ST, and generate pulses as the main shaft 34 rotates. An optical rotary encoder 70 that outputs a rotation signal SR is provided. This rotary encoder 70 also has the feature that when the main shaft 34 is rotated to a predetermined rotational position, each of the peripheral blades 68 of the milling cutter 66 is positioned directly below, and the depth of cut into the square material 60 is adjusted. The reset signal SS is output when the depth becomes the deepest. These contact signals ST' and rotation signals SR.

An example of the reset signal SS is shown in FIG.

The contact signal ST, rotation signal SR, and reset signal SS are supplied to the rotation angle detector 72. The rotation angle detector 72 is configured with a counter, etc., and counts the number of pulses Pc of the rotation signal SR after the reset signal SS is supplied until a new contact signal ST is supplied, for example. The rotation angle θ (°) of the milling cutter 66 while the peripheral cutter 68 is in contact with the square timber 60 is determined according to the following equation (3) from the number of pulses Pd of the rotation signal SR during the rotation of 30 degrees, and the rotation angle is A rotation angle signal Sθ representing θ is output. Note that the number of pulses of the rotation signal SR after the contact signal ST is supplied until the reset signal SS is supplied, that is, the pulse number Pa is counted,
The rotation angle θ can also be determined according to the above equation (2) or according to the following equation (4).

θ-30×(Pd-PC)/Pd...(3) θ-3
0×Pa/Pd (4) The rotation angle signal Sθ is supplied to the depth calculation circuit 58, and the actual depth of cut is calculated from the rotation angle θ represented by the rotation angle signal Sθ and the radius R to the cutting edge of the peripheral blade 68. Depth d is found. Then, so that this actual cutting depth d matches a target cutting depth determined based on the actual depth of the surface flaw existing in the square timber 60, or a predetermined constant target cutting depth, The movement device of the drive motor 32 is feedback-controlled.

Here, in the flaw removing means 62 of this embodiment,
The rotation angle θ is determined by using the reset signal SS that is generated when each peripheral cutter 68 of the milling cutter 66 reaches the bottom.
Therefore, due to the presence of chips, etc., the contact signal ST is not supplied until after the peripheral cutter 68 has passed directly below, as shown by the dashed line in FIG. 10, for example. However, there is an advantage in that the rotation angle θ and the cutting depth d can always be detected with high accuracy.

In this embodiment, the rotary encoder 70 and the rotation angle detector 72 constitute rotation angle detection means.

Although the embodiments of the present invention have been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the above embodiment, the depth of cut measuring device of the present invention is used for feedback control of the depth of cut in an automatic eaves removal device, but the present invention can also be used in various fields where cutting is performed using the peripheral edge of a rotary cutting tool. This device can be used in various ways, such as when the depth of cut is monitored and displayed or recorded.

Further, the contact detection means in the above embodiment is constituted by the ring sensor 52 and the control amplifier 54, but the outer peripheral blade 30.68 and the bar-shaped member 10. Directly detect electrical continuity due to contact with the square timber 60,
Various contact detection means can be employed, such as detecting contact between the two based on fluctuations in motor power of the drive motor 32 or fluctuations in shaft torque due to cutting resistance. In the second embodiment, it is only necessary to detect at least the start of contact, and it is sufficient to detect the end of contact when the rotating direction of the milling cutter 66 or the feeding direction of the square material 60 is reversed.

Further, the rotation angle detection means in the above embodiment is just an example, and for example, an optical rotary encoder 50
．． Regarding the use of a magnetic low reencoder instead of 70, and the reset signal SS in the second embodiment,
The milling cutter 66 may be configured in various other ways, such as by disposing a photoelectric switch or the like on the outer periphery of the milling cutter 66 and detecting each outer peripheral blade 68 to take out the cutter.

1 2 Also, the calculation contents of the depth calculation circuit 58 are determined as appropriate depending on the cutting form by the rotary cutting tool.

Further, in the above embodiment, the milling cutter 26 is used as a rotary cutting tool.
．． 66 is used, however, the number of peripheral cutting edges 30.68 and the shape of the cutting edge can be changed as appropriate, and the present invention can be similarly applied to rotary cutting tools other than milling cutters.

Further, in the embodiment described above, the rod-shaped material 10 and the square material 60 are fed in the longitudinal direction thereof, but the flaw detection means 18 and the flaw removal means 20.62 are moved in the longitudinal direction of the workpieces. There is no harm in doing so.

In addition, in the first embodiment, the amount of advance of the milling cutter 26 is controlled according to the depth of the surface flaw 14, but the cutting depth is always constant and predetermined regardless of the depth of the flaw. It is also possible to carry out the flaw removal process.

Further, in the first embodiment, the surface flaw 14 is detected by the flaw detection means 18, but a mark such as fluorescent paint is placed on the flaw position in advance, and the mark can be used to determine the flaw position and flaw depth. It is also possible to detect the

Further, in the first embodiment, the milling cutter 26 and the roller 28 are driven by separate driving means 38 and 42, but the milling cutter 26 and the roller 28 may be moved relative to each other in a floating manner by a single driving means. It is also possible to dispose the roller 28 immovably at a position where it substantially contacts the outer circumferential surface of the rod-shaped member 10 so that only the roller 28 is driven. In the case of a floating type, it is desirable that the roller 28 of the receiver contacts the bar-shaped member 10 first.

Further, in the first embodiment, the rotary disk 24 can be rotated within a range of 180 degrees in both forward and reverse directions from the reference position, but it can be rotated only in one direction within a range of 360 degrees. It is also possible to do so.

Further, in the second embodiment, the square timber 60 is rotated by a rotating device, but the flaw removal means 62 may be rotated instead of the square timber 60 as in the first embodiment, or It is also possible to arrange a total of four flaw removing means 62 facing each surface of the flaw removing means 60 .

Although other examples are not given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating the outline of an automatic flaw removing apparatus equipped with a cutting depth measuring device, which is an embodiment of the present invention. FIG. 2 is a diagram showing flaws existing on the surface of a rod-shaped material to be removed by the apparatus shown in FIG. FIG. 3 is a diagram showing an example of a flaw signal output from the flaw detection means of the apparatus shown in FIG. 1. FIG. 4 is a block diagram illustrating the main parts of the flaw removing means of the apparatus shown in FIG. 1. FIG. 5 is a diagram illustrating the rotational movement of the rotary disk in the flaw removing means of FIG. 4. FIG. 6 is a side view illustrating a state in which flaw removal is being performed by the flaw removal means shown in FIG. 4. FIG. FIG. 7 is a diagram showing an example of a contact signal and a rotation signal in the flaw removing means of FIG. 4. FIG. 8 is a configuration diagram illustrating a main part of another embodiment of the present invention. FIG. 9 is a side view of FIG. 8. FIG. 10 is a diagram showing an example of signals of each part in FIG. 8. 10: Rod-shaped material (work material) 26.66: Milling cutter (rotary cutting tool) 30.68: Peripheral cutting edge 34: Main shaft 58: Depth calculation circuit (depth determining means) 60: Square material (work material) ST: Contact signal θ: Rotation angle

Claims (1)

[Scope of Claims] In a rotary cutting tool that is attached to a main shaft and driven to rotate, the peripheral blade intermittently cuts into the surface of a workpiece to perform cutting, and the depth of cut into the workpiece is measured. The apparatus includes: a contact detection means for detecting contact between the peripheral blade and the work material and outputting a contact signal representing the contact, and a contact detection means for detecting contact between the peripheral blade and the work material, a rotation angle detection means for detecting a rotation angle of the rotary cutting tool while in contact; and a depth for determining a depth of cut into the workpiece based on the rotation angle and a diameter dimension of the rotary cutting tool. 1. A depth of cut measuring device for a rotary cutting tool, comprising determining means.