JP3748866B2 - Tool measuring apparatus and method - Google Patents

Description

但し、ａ、ｂ、ｃは定数である。
【００２０】
このとき、残差の二乗和ｕは以下の式（２）にて表される。
【数２】

但し、ｉは複数の位相角度位置の各々における測定を表す整数である。
【００２１】
残差の二乗和ｕが最小になるように各係数ａ、ｂ、ｃを求めるために、ｕをａ、ｂ、ｃで偏微分した式を=0とした連立方程式（３）〜（５）を解く。
【数３】

【００２２】
このとき、最大外径を与える位相角度位置ｘは以下の式（６）で表される。
【数４】

【００２３】
また、図４に示すように、Ｕ軸方向に所定距離Δｕを置いた２点ｕ₁、ｕ₂において同様に最大外径を与える位相角度位置ｘ₁、ｘ₂を求めることにより、ねじれ角θは以下の式（７）にて求めることができる。
【数５】

【００２４】
本発明は直径１ｍｍ以下の小径の回転切削工具を測定するのに特に適しているが、直径１ｍｍ以上の回転切削工具を測定するために用いても良い。
【図面の簡単な説明】
【図１】本発明の好ましい実施形態による工具測定装置の略示図である。
【図２】回転切削工具と光学センサの位置関係を示す略示図である。
【図３】最大外径を与える位相角度位置を求めるための方法を説明するためのグラフである。
【図４】回転切削工具のねじれ角を測定する方法を示す略示図である。
【符号の説明】
１０…工具測定装置
１２…主軸頭１２
１４…主軸
１６…工具ホルダ
１８…ロータリーエンコーダ
２０…旋回台
２２…Ｕ軸案内レール
２３…スライダ
２４…投光部（光学センサ）
２５…受光部（光学センサ）
２６…数値制御装置
２８…パーソナルコンピュータ
Ｔ…回転切削工具[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tool measuring apparatus and a tool measuring method for measuring a phase angle position that gives a maximum outer diameter of a rotary cutting tool.
[0002]
[Prior art]
When a rotary cutting tool such as an end mill is automatically regrinded, automatic positioning on an NC tool grinder is required. In order to position the rotary cutting tool, a sensor using a touch probe is generally used. However, when the rotary cutting tool to be measured is a small diameter tool having a diameter of 1 mm or less, for example, φ0.1 to φ0.3 mm, the rigidity of the tool itself is so low that the tool rotates before the touch probe of the sensor operates. In many cases, the cutting tool cannot be measured due to bending or breaking.
[0003]
On the other hand, when measuring in a non-contact manner using an optical sensor, the light diffraction phenomenon becomes more prominent as the diameter of the rotary cutting tool becomes smaller, and the grinding start point of the rotary cutting tool having a twisted cutting edge, that is, rotation It becomes difficult to accurately obtain the origin of the rotation angle around the central axis of the cutting tool (the origin of the phase angle position).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 06-109440
[Problems to be solved by the invention]
Therefore, the present invention has a technical problem to solve such problems of the prior art, and a tool measuring apparatus and a tool measuring method capable of accurately measuring the phase angle of the cutting edge tip that gives the maximum outer diameter of the rotary cutting tool. The purpose is to provide.
[0006]
[Means for Solving the Problems]
The invention described in claim 1 is a tool measuring device for measuring a phase angle position that gives a maximum outer diameter of a rotary cutting tool, a tool support means for supporting the rotary cutting tool so as to be rotatable about its central axis, Based on a signal from a rotating means for rotating the rotary cutting tool about its central axis, a phase angle detecting means for detecting a phase angle of the rotary cutting tool around the central axis, and a signal from the phase angle detecting means, A tool rotation positioning means for positioning the rotary cutting tool at a plurality of phase angle positions around the central axis, and a tool outside that outputs a signal corresponding to the outer diameter of each of the rotary cutting tools positioned at the plurality of phase angle positions. and diameter measuring means, based on the signal from the signal and the tool outer diameter measuring means from the phase angle detecting means, after obtaining the phase angle reference position of approximately giving the maximum outer diameter, the phase angle A predetermined phase angle measurement range centered on a reference position is determined, and the outer diameter of the rotary cutting tool is measured by the tool outer diameter measurement means at a number of phase angles within the phase angle measurement range. A new phase angle reference position that gives the maximum outer diameter of the rotary cutting tool is calculated from the quadratic curve by approximating the relationship with the outer diameter by a quadratic curve by the least square method, and the phase is calculated after the calculation. the outer diameter under conditions narrowed angular measurement range is measured, and the maximum outer径位phase angular position calculation means for a similar operation to calculate a more accurate phase angle reference position, a tool measuring device comprising the gist And
[0007]
According to another feature of the invention, in the tool measurement method for measuring the phase angle position that gives the maximum outer diameter of the rotary cutting tool,
(A) supporting the rotary cutting tool rotatably about its central axis;
(B) positioning the rotary cutting tool at a phase angle position around the central axis;
(C) measuring an outer diameter of the rotary cutting tool positioned at the plurality of phase angle positions;
(D) repeating the steps (b) and (c) a predetermined number of times;
(E) After obtaining the approximate phase angle reference position giving the maximum outer diameter in the step (d), a predetermined phase angle measurement range centered on the phase angle reference position is determined, and the phase angle measurement range numerous approximated by a quadratic curve by the least squares method the relationship between the outer diameter of the phase angle positions, as well as calculating a new phase angle reference position from the secondary curve gives the maximum outer diameter of the rotary cutting tool Providing a tool measuring method comprising: performing the same calculation for measuring the outer diameter under the condition that the phase angle measurement range is narrowed after the calculation and calculating a more accurate phase angle reference position. Is done.
[0008]
The method is performed during steps (a) and (b); (f) positioning the rotary cutting tool at a point along the central axis; and
(G) performing the steps (b) to (e);
(H) positioning the rotary cutting tool at another point along the central axis;
(I) performing the steps (b) to (e);
(J) At two points along the central axis, the phase angle position that gives the maximum outer diameter of the rotary cutting tool is calculated, and based on the phase angle difference that is the difference between the two and the distance between the two points And calculating a twist angle of the cutting edge of the rotary cutting tool.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
The tool measuring apparatus 10 according to the present embodiment includes a spindle head 12 as a tool support means. The spindle head 12 includes a spindle 14 on which a rotary cutting tool T such as a ball end mill is mounted via a tool holder 16 at the tip, and a housing that rotatably supports the spindle 14 around a horizontal A axis. The main shaft 14 is connected to a servo motor (not shown) as rotating means for rotating the main shaft 14 and the rotary cutting tool T about the A axis as the central axis of the rotary cutting tool T. The servo motor may be a built-in motor disposed in the housing of the spindle head 12.
[0011]
A rotary encoder 18 is attached to the rear end of the main shaft 14 as phase angle detection means for detecting the rotational position of the main shaft 14 around the A axis. The rotary encoder 18 is connected to a numerical controller 26 that controls the operation of the tool measuring apparatus 10. The numerical controller 26 is also connected with a servo motor as the rotating means, and the operation of the servo motor is also controlled by the numerical controller 26. On the other hand, the numerical control device 26 is connected to a personal computer 28 forming the maximum outer diameter phase angle position calculating means and the torsion angle calculating means through communication means such as bus connection.
[0012]
The spindle head 12 is attached to the upper surface of a swivel base 20 provided so as to be rotatable around a vertical W axis. More specifically, a U-axis guide rail 22 extending parallel to the A-axis is disposed on the upper surface of the swivel base 20, and the spindle head 12 is horizontal along the U-axis guide rail 22 by a slider 23. It can freely reciprocate in the U-axis direction, which is a straight line direction. The swivel base 20 is provided with a U-axis feeding device (not shown) for linearly reciprocating the spindle head 12 in the U-axis direction. The U-axis feed device includes, for example, a feed screw (not shown) extending in the U-axis direction, a nut (not shown) fixed to the spindle head 12 and engaged with the feed screw, and the feed screw A servo motor (not shown) connected to one end and controlled by the numerical controller 26 can be provided. Further, a U-axis scale (not shown) connected to the numerical controller 26 is provided as an axis position detecting means for detecting the position of the spindle head 12 along the U axis.
[0013]
The swivel base 20 is provided with an optical sensor including a light projecting unit 24 and a light receiving unit 25 as a tool outer diameter measuring unit. The optical sensors 24 and 25 are preferably disposed so as to irradiate light in a direction perpendicular to the A axis. The optical sensors 24 and 25 irradiate light from a light emitting diode 24a disposed in the light projecting unit 24, and irradiate the light receiving unit 25 as uniform parallel light through the light diffusion unit 24b and the collimator lens 24c. It is like that. The light receiving unit 25 is configured to measure the outer diameter of the rotary cutting tool T by connecting only the parallel light of the received light to a CCD (charge coupled device) 25a and detecting the bright and dark edge position Ed. . The measurement result is digitized by an A / D converter (not shown) disposed in the light receiving unit 25 and transmitted to the personal computer 28 via communication means such as serial connection. The engineering sensors 24 and 25 may use laser light.
[0014]
In addition, although the tool measuring apparatus 10 already described can be configured as an independent tool measuring apparatus, by incorporating the tool measuring apparatus 10 as a part of the NC grinder, a tool which will be described later as a part of the tool grinding process. It is possible to carry out the measurement process, which is very advantageous.
[0015]
Hereinafter, the operation of the present embodiment will be described.
First, the rotary cutting tool T is attached to the tip of the main shaft 14. As described above, when the tool measuring device 10 is incorporated as a part of the NC grinder, the rotary cutting tool T is already attached to the tip of the spindle 14 as part of the cutting edge grinding process. It will be. Next, light is emitted from the light projecting unit 24.
[0016]
Next, the spindle head 12 is moved along the U-axis guide rail 22 with the rotary cutting tool T mounted on the spindle 14 by the U-axis feeding device. The axis position along the U axis of the moving spindle head 12 is measured by the U axis scale and read into the numerical controller 26. In this way, the spindle head 12 is positioned along the U axis so that the desired position along the central axis (A axis) of the rotary cutting tool T crosses the light from the light projecting unit 24. In this process, for example, the spindle head 12 is advanced from a position where the rotary cutting tool T does not cross the light irradiated from the light projecting unit 24, and the tip of the rotary cutting tool T crosses the light from the light projecting unit 24. At the moment of shut-off, a skip signal is sent from the light receiving unit 25 to the numerical control device 26, and the spindle head 12 is further advanced by a desired distance from the origin as the U-axis origin of the U-axis scale at that time. Can be performed.
[0017]
Next, while irradiating light from the light projecting unit 24 and measuring the outer diameter of the rotary cutting tool T, the main shaft 14 is rotated around the A axis by a predetermined angle, and the phase angle position that gives the maximum outer diameter is stored. At this time, the radius of the rotary cutting tool T is obtained by referring to the height of the A axis (coordinate position along the W axis) that is the rotation center of the rotary cutting tool T as the outer diameter of the rotary cutting tool T. Is preferred. As a result, even when the rotary cutting tool T has an odd number of cutting blades or an even number of cutting blades, the two cutting blades at the positions sandwiching the diameter are accurately 180. Even when not arranged with a phase difference of °, it is possible to measure the phase angle position that gives the maximum outer diameter of the rotary cutting tool T.
[0018]
Next, the outer diameter of the rotary cutting tool T is measured at a predetermined angle, for example, every 1 °, within a predetermined phase angle range, for example, ± 5 °, around the phase angle position that gives the maximum outer diameter. Then, the phase angle position giving the maximum outer diameter is obtained. Next, the outer diameter of the rotary cutting tool T is set at a predetermined angle, for example, every 0.1 ° within a predetermined phase angle range, for example, ± 1 ° around the phase angle position that gives the maximum outer diameter. taking measurement.
[0019]
According to the present invention, the relationship between the phase angle and the outer diameter is expressed using the least square method from the measurement result, and the phase angle position that gives the maximum outer diameter is obtained. Here, referring to FIG. 3, a graph showing the relationship of the outer diameter y to the phase angle position x is shown. Since the tip of the cutting edge of the rotary cutting tool T circulates in a circular orbit about the A axis, theoretically, y = αcosβx (α and β are constants). However, if the phase angle range Δx to be measured is sufficiently small, it can be approximated by a quadratic curve represented by the following equation (1).
[Expression 1]

However, a, b, and c are constants.
[0020]
At this time, the residual sum of squares u is expressed by the following equation (2).
[Expression 2]

Here, i is an integer representing a measurement at each of a plurality of phase angle positions.
[0021]
In order to obtain the coefficients a, b, and c so that the square sum u of the residuals is minimized, simultaneous equations (3) to (5) where 0 is a partial differential of u with a, b, and c. Solve.
[Equation 3]

[0022]
At this time, the phase angle position x giving the maximum outer diameter is expressed by the following equation (6).
[Expression 4]

[0023]
In addition, as shown in FIG. 4, the twist angle θ is obtained by obtaining the phase angle positions x ₁ and x ₂ that similarly give the maximum outer diameter at two points u ₁ and u ₂ that are spaced by a predetermined distance Δu in the U-axis direction. Can be obtained by the following equation (7).
[Equation 5]

[0024]
The present invention is particularly suitable for measuring a rotary cutting tool having a small diameter of 1 mm or less, but may be used for measuring a rotary cutting tool having a diameter of 1 mm or more.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a tool measuring device according to a preferred embodiment of the present invention.
FIG. 2 is a schematic diagram showing a positional relationship between a rotary cutting tool and an optical sensor.
FIG. 3 is a graph for explaining a method for obtaining a phase angle position that gives a maximum outer diameter;
FIG. 4 is a schematic diagram showing a method for measuring a torsion angle of a rotary cutting tool.
[Explanation of symbols]
10 ... Tool measuring device 12 ... Spindle head 12
DESCRIPTION OF SYMBOLS 14 ... Main axis | shaft 16 ... Tool holder 18 ... Rotary encoder 20 ... Turning table 22 ... U-axis guide rail 23 ... Slider 24 ... Light projection part (optical sensor)
25. Light receiving part (optical sensor)
26 ... Numerical control device 28 ... Personal computer T ... Rotary cutting tool

Claims (10)

In a tool measuring device for measuring a phase angle position that gives the maximum outer diameter of a rotary cutting tool,
Tool support means for rotatably supporting the rotary cutting tool around its central axis,
Rotating means for rotating the rotary cutting tool around its central axis,
Phase angle detection means for detecting a phase angle around the central axis of the rotary cutting tool;
Tool rotation positioning means for positioning the rotary cutting tool at a plurality of phase angle positions around the central axis based on a signal from the phase angle detection means;
Tool outer diameter measuring means for outputting a signal corresponding to the outer diameter of each of the rotary cutting tools positioned at the plurality of phase angle positions;
Based on the signal from the phase angle detecting means and the signal from the tool outer diameter measuring means, after obtaining an approximate phase angle reference position giving the maximum outer diameter, a predetermined phase centered on the phase angle reference position An angle measurement range is defined, the outer diameter of the rotary cutting tool is measured by the tool outer diameter measurement means at a number of phase angles within the phase angle measurement range, and the relationship between the phase angle and the outer diameter is determined by a least square method. And calculating a new phase angle reference position that gives a maximum outer diameter of the rotary cutting tool from the quadratic curve by approximation with a quadratic curve , and after the calculation, the phase angle measurement range is narrowed under the conditions measuring the outer diameter, a tool measuring device comprising a maximum outer径位phase angular position calculation means, a for a similar operation to calculate a more accurate phase angle reference position. The tool outer diameter measuring means includes a light projecting unit and a light receiving unit, irradiates light across the central axis of the rotary cutting tool from the light projecting unit toward the light receiving unit, and the light receiving unit The tool measuring device according to claim 1, further comprising an optical sensor that outputs a signal corresponding to light brightness and darkness received by. The tool measuring device according to claim 1, wherein the tool support means includes a spindle head including a spindle extending along the central axis and a housing that rotatably supports the spindle. The tool measuring apparatus according to claim 3, wherein the phase angle detection unit includes a rotary encoder that detects a rotation angle of the spindle. The tool measuring apparatus according to claim 3 or 4, wherein the rotating means includes a servo motor that rotates the spindle, and the tool rotation positioning means includes a numerical controller that controls the servo motor. The tool measuring device according to any one of claims 2 to 5, wherein the spindle head is disposed so as to be linearly movable in an axial direction parallel to the central axis. The tool measuring device comprises:
An axis feeding means for moving the spindle head along the axis;
Shaft position detecting means for detecting a position along an axis parallel to the central axis of the spindle head;
The phase angle position that gives the maximum outer diameter of the rotary cutting tool is calculated at two points along the axis, and the rotary cutting tool is calculated based on the phase angle difference that is the difference between the two and the distance between the two points. The tool measuring device according to claim 6, further comprising a torsion angle calculating means for calculating a torsion angle of the cutting edge. In a tool measuring device for measuring a phase angle position that gives the maximum outer diameter of a rotary cutting tool,
A spindle head that rotatably supports the rotary cutting tool;
A servo motor for rotating the rotary cutting tool;
A rotary encoder that detects a phase angle around a central axis of the rotary cutting tool;
An optical sensor that outputs a signal corresponding to the outer diameter of each of the rotary cutting tools,
Based on the signal from the rotary encoder and the signal from the optical sensor, after obtaining an approximate phase angle reference position that gives the maximum outer diameter, a predetermined phase angle measurement range centered on the phase angle reference position is determined. The outer diameter of the rotary cutting tool is measured by the tool outer diameter measuring means at a number of phase angles within the phase angle measurement range, and the relationship between the phase angle and the outer diameter is expressed by a quadratic curve by the least square method. Calculate a new phase angle reference position that gives the maximum outer diameter of the rotary cutting tool from the quadratic curve , and measure the outer diameter under the condition that the phase angle measurement range is narrowed after the calculation. The tool measuring device which performs the same calculation for calculating a more accurate phase angle reference position . In the tool measurement method for measuring the phase angle position that gives the maximum outer diameter of the rotary cutting tool,
(A) supporting the rotary cutting tool rotatably about its central axis;
(B) positioning the rotary cutting tool at a phase angle position around the central axis;
(C) measuring an outer diameter of the rotary cutting tool positioned at the plurality of phase angle positions;
(D) repeating the steps (b) and (c) a predetermined number of times;
(E) After obtaining the approximate phase angle reference position giving the maximum outer diameter in the step (d), a predetermined phase angle measurement range centered on the phase angle reference position is determined, and the phase angle measurement range numerous approximated by a quadratic curve by the least squares method the relationship between the outer diameter of the phase angle positions, as well as calculating a new phase angle reference position from the secondary curve gives the maximum outer diameter of the rotary cutting tool A tool measuring method comprising: performing the same calculation for calculating the more accurate phase angle reference position by measuring the outer diameter under the condition that the phase angle measurement range is narrowed after the calculation . (F) positioning the rotary cutting tool at one point along the central axis;
(G) performing the steps (b) to (e);
(H) positioning the rotary cutting tool at another point along the central axis;
(I) performing the steps (b) to (e);
(J) At two points along the central axis, the phase angle position that gives the maximum outer diameter of the rotary cutting tool is calculated, and based on the phase angle difference that is the difference between the two and the distance between the two points The tool measuring method according to claim 8, further comprising calculating a twist angle of a cutting edge of the rotary cutting tool.

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