JPH06201351A - Shape measurement for rotary tool - Google Patents

Abstract

PURPOSE:To provide a shape measurement method of a rotary tool capable of finding a radius of an edge point of the rotary tool comparatively easily and accurately. CONSTITUTION:A device with a means 4 to hold a rotary tool 6 free to rotate, a measuring head 3 of an LSM (laser scan micrometer) type arranged with a light sending part 31 and a light receiving part 33 against the direction orthogonal with a shaft of the rotary tool 6, a rotary table 2 to hold this measuring head 3 and to rotatively drive it and a control part to take up output of the measuring head 3, to memorize and arithmetically process it is used. A radius value of a master ball the radius value of which is already known is taken up as an offset value, the rotary tool 6 is installed and its edge point center which must exist is positioned on the rotational center of the rotary table 2, finite difference of the edge point head end and the offset value is measured by rotating the rotary table 2 intermittently, and by averaging its data, diameter of the blade edge is computed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring method for measuring the shape of a cutting edge of a rotary tool such as a ball end mill.

[0002]

2. Description of the Related Art A ball end mill is used as a rotary tool for machining the surface of a mold or the like. The ball end mill has a blade with a hemispherical surface of revolution at the tip of the straight shank. In order to perform high-precision machining using this ball end mill, it is necessary that the shape of the cutting edge, that is, the roundness and radius of the spherical tip portion is maintained with high precision. Since the tip of the ball end mill extends to the top of the tip spherical portion, it is very difficult to measure the radius of the tip spherical portion. Here, the radius of the cutting edge means the radius of the outermost peripheral surface formed when the tool rotates.

[0003]

Conventionally, in order to measure the radius of this ball end mill, a method of indirectly obtaining the radius by performing enlarged projection and a method of measuring the diameter of a straight shank and estimating the radius of the cutting edge are known. Etc., various methods are used. However, it is difficult to measure the blade edge shape with high accuracy by any of the methods. The method of measuring with a three-dimensional shape measuring machine while rotating the tool can accurately know the radius, but this has a drawback that it takes a lot of time and labor for measurement.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for measuring the shape of a rotary tool which can relatively easily and accurately determine the radius of the cutting edge of the rotary tool.

[0005]

According to the present invention, a holding means for holding a rotary tool rotatably around its axis, a moving means for reciprocating the holding means in the axial direction of the rotary tool, and a holding means for holding the holding means. Measuring means for dimensional measurement by a light receiving signal pattern obtained by linearly scanning a laser light beam, in which a light transmitting portion and a light receiving portion are arranged so as to face each other in a direction orthogonal to the axis of the rotating tool. A rotary tool using a shape measuring device having means for holding and rotating and driving the means in a plane orthogonal to the laser light beam, and control means for fetching output data of the measuring means and storing and processing the data. A method for measuring the shape of
(A) A step of holding a master ball having a known radius in the holding means and aligning the center of the master ball so that its center coincides with the center of rotation of the rotary table; and (b) a rotary tool to be measured, the holding means. And (c) aligning the center of the cutting edge of the rotary tool with the center of rotation of the rotary table based on the difference between the radius value of the master ball and the nominal value of the diameter of the cutting edge of the rotary tool. Measuring the distance from the center of the rotary table at each angular position to the tip of the cutting edge of the rotary tool by the measuring means while intermittently rotating the rotary table at every predetermined angle,
(D) A step of averaging the distance data measured at the respective angular positions by the control means to calculate the diameter of the cutting edge of the rotary tool.

[0006]

According to the present invention, the shape of the cutting edge of a rotary tool such as a ball end mill is used by using a shape measuring device of a so-called laser scanning micrometer (LSM) system for scanning a laser light beam to measure dimensions in contact. Can be easily measured. Particularly, in the present invention, center alignment and radius value presetting of a master ball whose radius is known in advance are performed, and with this as a reference, a rotary tool to be measured is set and a plurality of angular positions are set along the circumference of the cutting edge. By obtaining the polar coordinates of the cutting edge as a difference from the above-mentioned offset value and performing arithmetic processing to average this, it is possible to perform very accurate diameter measurement.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an LS used in an embodiment of the present invention.
1 is a schematic configuration of a non-contact type shape measuring device using M. A turntable 2 (arrow A is the direction of rotation) is provided on a base 1, and an LSM type measurement head 3 is provided on the turntable 2.
Is attached. The measurement head 3 has a light transmitting unit 31 that emits a laser light beam 32 in the upper portion, and a light receiving unit 33 that receives the laser light beam in the lower portion. The light transmitting section 31 can linearly scan the laser light beam 32 as shown in the figure by a polygon mirror or the like, and the light receiving section 33 collects and detects the laser light beam thus scanned.

The measuring principle of the measuring head 3 is as follows. The object to be measured is placed in the scanning area of the laser light beam 32. Then, when the laser light beam is scanned, the laser light beam 32 is blocked at the portion of the object to be measured. Therefore, the shape of the object to be measured can be measured by data-processing the on / off received light signal pattern obtained by the light receiving portion 33. In this embodiment, the light transmitting section 3 of the measuring head 3 is
A reference pin 34 serving as a reference for distance measurement is provided at an intermediate position between 1 and the light receiving unit 33.

The rotary table 2 on which the measuring head 3 is mounted
Adjacent to the above, holding means 4 is arranged to hold the rotary tool 6 to be measured such that its axis is orthogonal to the axis of the laser light beam 32 and is rotatable about its axis by a hydraulic chuck or the like. . The arrow B in the figure indicates the rotation direction of the rotary tool 6. The holding means 4 includes an X, Y drive table 5a,
It is arranged on the moving means 5 composed of 5b, and can be moved arbitrarily in the directions of arrows C and D. With this moving means 5, the tip end of the rotary tool 6 held by the holding means 4 to be measured can be set in the scanning region of the laser light beam 32.

The angle between the axis of the rotary tool 6 to be measured and the scanning surface of the laser light beam 32 is set by setting the angle of the rotary table 2 in the direction of rotation of the rotary table 2. Further, by setting the angle of the rotating tool 6 in the rotation direction indicated by the arrow B, the cross section of the rotating tool 6 that blocks the laser light beam 32 is determined. In this embodiment, the rotary table 2 rotationally drives the measuring head 3 in a plane orthogonal to the laser light beam 32. In other words, this is formed by the scanning plane of the laser light beam 32 and the axis of the rotary tool 6. It determines the corner. Therefore, the rotary table 2 may be provided not on the measuring head 3 side but on the tool holding means 4 side.

In FIG. 1, a motor or the like which is a drive source of each part is omitted. As control means for controlling the rotary table 2, the measuring head 3, the holding means 4, the moving means 5 and the like to perform automatic measurement, for example, as shown in FIG. 2, a keyboard 71, a storage / calculation / control section 72, a display section 73. PC 7 consisting of
Are connected. The personal computer 7 is also used to store and process the measurement data obtained from the measuring head 3. Actually, each part is also provided with a manual operation part,
This is also omitted in FIG.

A method for specifically measuring the shape of the cutting edge of a straight shank ball end mill using the shape measuring device thus configured will be described below. The blade tip of the straight shank ball end mill has a complicated shape as shown in FIG. 3, and in this embodiment, the diameter of the blade tip can be accurately measured without contact. The principle of diameter measurement by the measuring head 3 will be described with reference to FIG. As shown in the figure, it is assumed that two works W1 and W2 are arranged so as to cross the scanning region of the laser light beam. At this time, the light receiving part
Since the light and dark patterns are projected by the works W1 and W2, the work W can be processed by processing the received light signal.
The diameters of 1 and W2 can be directly obtained, and the distance between them can be obtained. In this embodiment, the principle of distance measurement between one of the two works W1 and W2 shown in FIG. 4 is used as a reference pin. That is, the distance between the center position of the master ball and the reference pin is measured using a master ball whose reference diameter is known, and this distance data is stored as an offset reference value corresponding to the radius value of the master ball. Next, regarding the end mill to be measured, the polar coordinates of the cutting edge are obtained at a plurality of angular positions along the circumference of the cutting edge as a difference from the above-mentioned offset value. If these differences are averaged, the value shows the deviation of the radius of the end mill from the nominal value, and the radius of the end mill is obtained by this.

A measuring method of a concrete example will be described below. First, the master ball 11 having a known radius R as shown in FIG. 5 is used to preset the shape measuring apparatus. That is, the master ball 11 is attached to the holding means 4, the center of the master ball 11 is set substantially at the rotation center position of the rotary table 2, and the distance a between the master ball 11 and the reference pin 34 is measured by the measuring head 3. . Further, the rotary table 2 is rotated by 90 °, and the same distance measurement is performed again. Although it is shown in FIG. 5 that the master ball 11 is rotated, this is the rotary table 2
This is because rotating the ball relatively rotates the master ball 11. At this time, the moving distance of the master ball 11 in the support axis direction is adjusted by the moving means 5, and the position of the master ball 11 is set so that the distances a measured at the two rotational positions become equal. As described above, the center of the master ball 11 is aligned with the center of rotation of the turntable 2. Further, the distance value a measured in the above steps is taken in and stored in the personal computer 6 as a radius offset value corresponding to the radius of the master ball 11.

Next, the ball end mill 12 to be measured
(Nominal value r of radius) is attached to the holding means 4, and the position in the axial direction is adjusted while measuring the distance b between the holding means 4 and the reference pin 34, and b−a = Positioning is performed electrically so as to satisfy R−r = Δr. As a result, the center of curvature of the cutting edge of the ball end mill 12 is set to the center of rotation of the rotary table 2. This alignment does not mean that the actual center of the ball end mill is aligned with the center of rotation of the rotary table 2, but based on the nominal value of the radius of the ball end mill 12, the center of rotation should be the original center when there is no wear or the like. Is to be aligned with.

Next, the rotary table 2 is rotated by 90 ° so that the ball end mill 12 is relatively rotated by 90 ° as shown in FIG. In this state, the ball end mill 12 is rotated about its axis as indicated by arrow E in the figure, and the distance c between the ball end mill 12 and the reference pin 34 is measured, and the ball end mill 12 is stopped at a position where this distance c is minimized. This alignment is for making the cross section with the maximum diameter of the cutting edge orthogonal to the laser beam and measuring the diameter of the cutting edge at that cross section.

After the above positioning is completed, the personal computer 7
The rotation table 2 is moved from 5 ° to 1 by the measurement start command from
It is intermittently rotated at an appropriate interval of about 5 °, and the cutting edge of the ball end mill 12 and the reference pin 34 are rotated at each rotational position.
Measure the distance between them. At this time, when measuring the distance at each angular position, the ball end mill 12 is moved about 4 times around its axis.
Rotate slowly in the range of about 0 ° compared to the laser scanning cycle, and use the smallest distance value (which corresponds to the diameter at the largest blade edge cross section) of the distance values obtained in that range as measurement data. adopt. By rotating the blade edge during this measurement, the diameter of the blade cross section to be measured can be measured. The ball end mill in FIG. 3 has two blades, but the blade tip rotation range at the time of this measurement changes depending on whether the ball end mill has three blades or four blades.

FIG. 8 shows the distance measurement data d1, d2, d obtained intermittently in this way in the rotation range of 180 °.
3, ..., d13, radius offset value R and rotation center O1
To the actual tip of the blade edge (amount of error from the radius offset value). That is, each of the distance data d1, d2, d3, ..., D13 can be said to be the distance from the center O1 of the rotary table at each angular position to the tip of the cutting edge of the tool as a difference from the radius offset value.

The center O1 of the rotary table 2 and the actual center O2 of the cutting edge of the ball end mill are as described above.
Although the alignment is performed on the basis of the nominal value of the ball end mill in the step of FIG. 6, there is actually a deviation as shown in FIG. Including the influence of this shift, the measured distance data d1, d2, d3, ..., D13 have variations as shown.

The distance measurement data d thus obtained
1, d2, d3, ..., D13 are taken into the personal computer 7 and data processed, and the diameter of the cutting edge of the ball end mill 12 is obtained. That is, the measurement data d1, d2, d shown in FIG.
By averaging 3, ..., d13 by the method of least squares, the difference between the radius r1 of the actual cutting edge of the ball end mill 12 and the radius offset value R can be obtained without the influence of the deviation of the centers O1 and O2. Therefore, by obtaining the difference between this difference and the radius offset value R, the actual radius r1 of the ball end mill 12 is obtained.

The above measurement results are graphically displayed on the display section of the personal computer 7 and can be printed out. In addition to the above-mentioned error amount (plus direction and minus direction), fluctuation range (plus direction maximum error amount + minus direction maximum error amount), standard deviation calculation, print output, etc. It is more preferable to know the situation.

[0021]

As described above, according to the present invention, L
Using the SM type shape measuring device, preset the radius offset value with a master ball of known radius,
Set the rotary tool to be measured, determine the polar coordinates of the cutting edge at a plurality of angular positions along the circumference of the cutting edge as the difference from the above-mentioned offset value, and perform arithmetic processing to average this to obtain accuracy Higher diameter measurement is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a measuring apparatus used in an embodiment of the present invention.

FIG. 2 is a diagram showing a personal computer connection state of the embodiment apparatus.

FIG. 3 is a view showing a cutting edge of a straight shank ball mill.

FIG. 4 is a diagram for explaining the principle of LSM.

FIG. 5 is a diagram showing an offset value setting step of the embodiment.

FIG. 6 is a diagram showing a step of setting a ball end mill according to the embodiment.

FIG. 7 is a diagram showing steps of setting a ball end mill according to the embodiment.

FIG. 8 is a diagram showing a distribution of distance measurement data according to an example.

[Explanation of symbols]

1 ... Base, 2 ... Rotating table, 3 ... Measuring head, 31 ...
Light transmitting section, 32 ... Laser light beam, 33 ... Light receiving section, 34 ...
Reference pins, 4 ... Holding means, 5 ... Moving means, 6 ...
Rotating tool, 7 ... PC, 11 ... Master ball, 12
… Ball end mill.

Claims (2)

[Claims] 1. A holding means for holding a rotary tool rotatably around its axis, a moving means for reciprocating the holding means in the axial direction of the rotary tool, and an axis orthogonal to the axis of the rotary tool held by the holding means. A light-transmitting section and a light-receiving section are arranged to face each other in the direction of measurement, and the dimension is measured by a light-receiving signal pattern obtained by linearly scanning a laser light beam; A method for measuring the shape of a rotary tool using a shape measuring device having a rotary table that is rotationally driven in a plane orthogonal to a laser light beam, and a control means that captures output data of the measuring means and stores and processes the data. And (a) a step of holding a master ball having a known radius in the holding means and aligning the center of the master ball so that the center of the master ball coincides with the center of rotation of the turntable. Holding the rotary tool to be fixed to the holding means, based on the difference between the radius value of the master ball and the nominal value of the diameter of the cutting edge of the rotary tool, the center of the cutting edge of the rotary tool should be the rotation center of the rotary table. Aligning, and (c) measuring the distance from the center of the rotary table at each angular position to the tip of the cutting edge of the rotary tool by the measuring means while intermittently rotating the rotary table at each predetermined angle. And (d) averaging the distance data measured at each of the angular positions by the control means to calculate the diameter of the cutting edge of the rotary tool. . 2. A holding means for holding the rotary tool rotatably around its axis, a moving means for reciprocating the holding means in the axial direction of the rotary tool, and an axis orthogonal to the axis of the rotary tool held by the holding means. A light-transmitting section and a light-receiving section are arranged to face each other in the direction of measurement, and the dimension is measured by a light-receiving signal pattern obtained by linearly scanning a laser light beam; A method for measuring the shape of a rotary tool using a shape measuring device having a rotary table that is rotationally driven in a plane orthogonal to a laser light beam, and a control means that captures output data of the measuring means and stores and processes the data. (A) A master ball having a known radius is held by the holding means, the center of the master ball is aligned with the center of rotation of the rotary table, and the radius value is turned off. Storing in the control means as a set value, (b) holding the rotary tool to be measured in the holding means, and based on the difference between the radius value of the master ball and the nominal value of the diameter of the cutting edge of the rotary tool. Aligning the center of the cutting edge of the rotary tool with the center of rotation of the rotary table; (c) aligning the axis of the rotary tool held by the holding means with the laser beam scanning direction of the measuring means, and Rotating around and measuring the diameter by the measuring means, and setting it to a position where the diameter to be measured becomes the maximum; (d) rotating the rotary table intermittently at every predetermined angle while Measuring the distance from the center of the rotary table to the tip of the cutting edge of the rotary tool by (e) averaging the distance data at each of the angular positions by the control means. Shape measuring method of the rotary tool, characterized in that it comprises a step of calculating the diameter of the cutting edge of the rotary tool to sense, the.