JPH0466286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus and a measuring method for measuring the dimensions, shape accuracy, etc. of rotary tools such as ball end mills and drills.

[Conventional technology]

For example, when machining the surface of a mold three-dimensionally, a ball end mill is used as the tool. As illustrated in FIGS. 8 and 9, this type of tool 1 has blades on the outer periphery and tip of the straight portion 2, and the rotating surface of the tip has a hemispherical shape. To perform machining using the tool 1, for example, you can machine the workpiece so that it has the same shape as the model while tracing the model with a stylus, or you can machine the workpiece so that it has the same shape as the model, or when using CAD/CAM. There is also an established method for directly machining workpieces using numerical control without the use of .

In order to perform high-precision machining, it goes without saying that the shape and dimensional accuracy of tools such as ball end mills are important, but in the case of copy machining using a stylus and model, the precision of the tool is more important than the precision of the tool. Rather, shape errors in the model itself and mechanical errors caused by scanning sensitivity had a greater effect on the transfer accuracy of the workpiece shape. For this reason, in the case of copying machining, the accuracy of the cutting edge of the tool has not been much of an issue.

However, when the three-dimensional shape of a workpiece is directly machined with a tool using numerical data, the error factors are significantly reduced compared to the copying process mentioned above, so it is important to improve the shape of the tool's cutting edge ( In particular, maintaining high accuracy in the roundness and radius of the spherical tip is an extremely important requirement. Particularly when re-polishing and reusing a worn tool, it is extremely important to know whether the tip of the tool has the proper shape and dimensions in order to maintain the finishing accuracy of the workpiece. be.

As illustrated in FIGS. 8 and 9, in a normal ball end mill tool 1, the cutting edge lead extends to the top of the spherical part 3 at the tip, so the radius R of the spherical part 3 is measured. This has become extremely difficult. Note that the cutting edge radius is the radius of the outermost cutting edge rotating surface created by the rotation of the tool.

Currently, there are methods to measure this radius indirectly using a magnifying projector, estimating the radius of the spherical part of the cutting edge by measuring the diameter of the straight part of the tool, and measuring the radius in 3D while rotating the tool. A method of measuring using a measuring device is known.

[Problem that the invention seeks to solve]

Among the above-mentioned methods, the method using a magnifying projector requires projecting the shadow of the tool on the magnifying projector while rotating the tool, plotting its outline, and calculating the radius using a gauge or numerical calculation. Because of this, measurements not only take a considerable amount of time, but also require experience and skill.

Further, in the method (2), the straight portion 2 is measured directly using a caliper or a micrometer, so the measurement time is short, but not only does it require considerable experience and skill, but the measurement accuracy is low. Moreover, although this method is a simple method in which the radius R can be determined when the boundary between the tip spherical portion 3 and the straight portion 2 is ideal, it has a fatal drawback of large measurement errors. Further, this method cannot be applied to a tool in which the straight portion 2 has a tapered shape.

Although the method using a three-dimensional measuring device can determine the radius value extremely accurately, it takes a long time to measure and requires a considerable amount of labor and skill.

[Means for solving problems]

The measuring device for a rotary tool according to the present invention includes a tool rotating unit rotated by a motor, a tool moving means, a measuring head, a measuring head driving means, a control/calculating section, etc. . The tool rotation unit chucks a tool and is capable of accurately rotating the tool around an axis by a predetermined angle using a motor. Further, the tool moving means has a function of reciprocating the tool rotation unit in the axial direction of the tool. The measuring head is equipped with a line sensor consisting of a light emitter and a light receiver that are arranged opposite to each other in a direction perpendicular to the axis of the tool. Further, the measuring head driving means accurately rotates the measuring head by a predetermined angle around a horizontal axis in a direction perpendicular to the axis of the tool, with the reference point at one end side of the measurement area by the line sensor as the rotation center. It is possible. For example, a microcomputer is used as the control/calculation section, and is capable of controlling the movements of the tool rotation unit, the tool moving means, the measuring head driving means, etc., and also takes in the measured values from the line sensor and processes the measurements. Process values according to purpose.

In order to actually measure the radius of the spherical part of the tool tip (the radius of the circle formed by the rotating surface of the cutting edge), the reference point of the measurement area of the line sensor, that is, the center of rotation of the line sensor, and the center of the circle at the tool tip must approximately align. need to be on. Therefore, the control/arithmetic unit of the present invention has a control content for performing preliminary measurement (centering) before starting the main measurement (actual measurement of the radius).

That is, in the preliminary measurement, the control/calculation unit of the present invention rotates the line sensor around this reference point with the reference point of the line sensor located inside the tool tip, and measures at least three different angles. At the same time, the tool is rotated by the tool rotation unit at each angle.
After rotating the tool and calculating the approximate center position of the circle created by the rotating surface of the cutting edge at the tip of the tool based on the light shielding position of the measurement area at each angle, the tool moving means is rotated so that the center of this circle is located at the reference point. Then move the tool in the axial direction. In the subsequent main measurement, the line sensor is rotated around the reference point and set at multiple angles, and the tool is rotated once by the tool rotation unit at each angle, and the tool is rotated once at each angle. It has control content that calculates the radius of the circle created by the rotating surface of the cutting edge at the tip of the tool based on the shaded position of the measurement area detected by the line sensor.

[Effect]

In the preliminary measurement (centering process), the measurement head driving means is configured to set the line sensor at at least three different angles with the reference point of the measurement area of the line sensor located inside the tip of the tool. The measuring head is rotated around the horizontal axis with the reference point as the center, and the tool is rotated once at each angle by the tool rotation unit, and the measurement head is rotated once based on the shaded position of the measurement area at each angle. After calculating the approximate center position of a circle formed by the rotating surface of the cutting edge at the tip of the tool, the tool is moved in the axial direction by the tool moving means so that the center of the circle is located at the reference point.

In the subsequent main measurement, the line sensor is rotated around the horizontal axis around the reference point and set at multiple angles,
The tool is rotated once by the tool rotation unit at each angle, and the radius of the circle created by the rotating surface of the cutting edge at the tip of the tool is calculated based on the shaded position of the measurement area detected by the line sensor for each angle. do.

〔Example〕

First, the measuring device will be explained.

As shown in FIG. 1, the measuring device 10 includes a tool rotation unit 11, a tool moving means 12, a measuring head 13, a measuring head driving means 14, a control/calculating section 15, etc. There is.

The tool rotation unit 11 includes a chuck (not shown) for gripping the tool 1 and a motor 1.
8 allows the tool 1 to be accurately rotated by a predetermined angle around the axis. Therefore, as the motor 18, for example, a pulse motor is used so that the rotational position can be controlled. 1
9 is a driving side rotating body, and this driving side rotating body 19
The rotational force is transmitted to the driven rotating body 21 by the transmission body 20.
is transmitted to.

The tool moving means 12 is for reciprocating the tool rotation unit 11 in the axial direction of the tool 1. That is, this tool moving means 12 is connected to the tool rotating unit 1 by means of the guide rail 22.
1 is movably supported, and a pulse motor 24
By rotating a lead screw 25 attached to the tool 1, the tool rotation unit 11 can be moved along the guide rail 22 to a desired position together with the tool 1. The tool moving means 12 and the tool rotation unit 11 are provided with a position sensor (not shown) for electrically detecting the position of the tool 1 and providing feedback to the control/calculation section 15.

The measuring head 13 is equipped with a line sensor 27. This line sensor 27 is configured to include a light projecting section 28 and a light receiving section 29 that are arranged to face each other in a direction orthogonal to the axis of the tool 1. As shown in FIG. 3, the line sensor 27 detects the length r of the light shielding part 30a (the hatched area in the figure) in the measurement area 30, thereby knowing the position of the end face of the measured location. It's becoming like that. The measuring head 13 is rotatably supported by a fixed frame 32 by a horizontal shaft 31 extending perpendicularly to the axis of the tool 1. The center o'- of this horizontal axis 31
o' (see FIG. 2) corresponds to the position of one end 30b as an example of the reference point of the measurement area 30,
Moreover, the height of the frame 32 or the relative height of the tool rotation unit 11 is designed so that the height of one end 30b of the measurement area 30 and the height of the axis o-o of the tool 1 exactly match each other. There is.

The measuring head drive means 14 are equipped with a motor 35. This motor 35 rotates the measurement head 13 by a predetermined angle around the horizontal axis 31 in a direction perpendicular to the axis of the tool 1, centering on one end 30b of the measurement area mentioned above. For example, a pulse motor is used for control. The measuring head driving means 14 is provided with a sensor (not shown) for detecting the position of the measuring head 13 and providing feedback to the control/calculating section 15.

The control/calculation unit 15 uses a microcomputer, for example, and includes a keyboard unit 37 for inputting various data and a display unit 38.
It is equipped with This control/calculation section 15 is capable of controlling the movements of the motor 18 of the tool rotation unit 11, the motor 24 of the tool moving means 12, and the motor 35 of the measuring head driving means 14, and also receives measured values from the line sensor 27. In addition to incorporating
Through pre-programmed processing procedures,
These measured values can be processed by calculation.

Next, the tool 1 is measured using the measuring device 10 configured as described above.
We will explain how to measure the shape of the tip, etc.

First, the tool 1 to be measured is accurately held by the chuck of the tool rotation unit 11 so as not to move. This is done manually. Next, the motor 24 of the tool moving means 12 is driven to move the tool 1 forward together with the tool rotation unit 11, and as shown in FIG.
One end 30b, which is the center of rotation of the tool 1, is stopped at a position several mm inside from the top of the tip of the tool 1.

The measuring head 13 is then moved at at least three different angles, for example θ ₁ , θ ₂ , θ ₃ , as shown in FIG.
The spherical tip portion 3 is measured by sequentially setting the angle to θ ₄ . That is, the tool 1 is rotated once each time the line sensor 27 is successively set at the above-mentioned angles with one end 30b of the measurement area as the center. Then, every time the tool 1 rotates once, the line sensor 2
7 performs transmission measurement, extracts the maximum value of the length r of the light shielding part 30a, and inputs it into the control/calculation part 15. In this way _, the _measured values _{r 1 , r 2} ,
Obtain r ₃ and r ₄ . Then, (r ₁ ~ r ₄ , θ ₁ ~ _{θ 4} ) is converted into xy coordinate values (x ₁ ~ x ₄ , y ₁ ~ y ₄ ), and (x ₁ ~ x ₄ , y ₁ to _{y 4} ), the center position (x ₀ , y ₀ ) of a circle passing through these four points is determined. Here, since the point x=0, y=0 is the rotation center 30b of the line sensor 27, by moving the tool 1 by _x0 in its axial direction (x direction), as shown in FIG. One end 30b of the measurement area 30 is located at the radial center position C of the spherical tip of the tool 1.
match. In other words, alignment is performed.
The above series of steps is preliminary measurement (alignment). Note that the height of one end 30b of the measurement area, which is the center of rotation of the line sensor 27, and the tool axis o-o
Since the heights of are made to match, the above y ₀ is 0 in terms of design. However, the tool rotation unit 1
If the structure is such that 1 can also move in the y direction (in the vertical direction in the figure), more accurate centering can be achieved.

Next, the main measurement begins. To explain one example, the line sensor 27 is stopped at a lower position of θ=-90°, as shown by the solid line in FIG.
Then, by operating the motor 18, the tool 1 is rotated once around its axis, and the line sensor 27 measures the light-shielding portion during the rotation. This measurement is performed at, for example, 200 locations during one rotation of the tool 1, and the maximum value is extracted and input to the control/calculation section 15. Next, the measurement area is rotated by an arbitrary angle around one end 30b of the measurement area and measured multiple times over a total range of 180° up to +90°. For example, the sensor is rotated 15 degrees around the horizontal axis 31 and the same measurement as above is performed at θ ₁ =-75 degrees. Similarly, the measurement is repeated over a total range of 180° by increasing the angle by 15° such as θ ₂ = −60° and θ ₃ = −45° until +90°, and the values are sent to the control/calculation unit 15. input. The input data is converted from polar coordinate values (r ₀ to r _o , θ ₀ to _{θ o} ) to orthogonal coordinate values (x ₀ to x _o , y ₀ to y _o ). Next, the radius value R and the center position (X, Y) are calculated from the data of ( _x0 to _xo , _y0 to _yo ) by the least square method of circles.
Further, the variation in the radius of curvature of each point between θ ₀ and θ _o is determined using the following formula Z _i =R−√( _i −) ² +( _i −) ² . By displaying the various calculation results obtained in this way on the display unit 38 and printing them out as necessary, it is possible to grasp the accuracy, dimensional accuracy, etc. of the tip shape of the tool 1, and to confirm that these satisfy the specified values. You can easily determine whether or not there are any. The flow of the above series of processes is shown in FIG.

According to the measuring device 10 and the measuring method described above, the tool 1
Since the radius of the tip spherical part 3 can be directly measured without contact, there is no influence of contact pressure or elastic deformation, etc.
Can be measured accurately. Since the method directly measures the radius, etc., errors are less likely to occur. Furthermore, since it is non-contact, there are no wear points, and the device itself is almost maintenance-free. The measurement can be completed in a short time (several minutes), and the quality of the tool can be automatically determined without being affected by the operator's level of skill or skill, and the location of the defect can also be clearly indicated.

Furthermore, according to the above-mentioned device 10, the measured values of each part of the tool can be registered as they are in a machine tool control computer, and the data required during machining can be used online.

In the above embodiment, a case has been described in which a ball end mill tool 1 having a hemispherical tip is measured as an example of a rotary tool, but the present invention can also be applied to an end mill having a tip other than hemispherical.

For example, in the rotary tool 1' shown in FIGS. 6 and 7, the length L and diameter D of the tool can be measured using the measuring device 10 described above. In this case, after rotating the measuring head 13 so that the measuring area 30 of the line sensor becomes horizontal as shown in FIG. 6, the tool rotating unit 11 is moved forward. Overall length specific to the device
Accurately measure _L1 and unit length _L2 in advance.
Then, the moving distance L ₃ is determined based on the position of the tip end surface of the tool 1' at the moment when it is sensed by the line sensor 27 and the drive pulse to the motor 24. The length L of the tool 1' is obtained by _L1 - ( _L2 + _L3 ).

Furthermore, in order to measure the diameter D, one end 30b, which is the center of rotation of the line sensor 27, must be positioned, for example, by 55 mm, which is the center of rotation of the line sensor 27, as shown by the solid line in FIG.
Stop about ~10mm inside. Then, the radius a1 is determined by measuring with the line sensor 27 while rotating the tool ₁ ' once. In principle, the diameter D can be obtained by doubling a ₁ , but in order to further improve measurement accuracy, the line sensor 27 is placed at one end 30a of the measurement area.
Rotate 180° around , and find the upper radius measurement value a ₂ . Then, the diameter D can be determined accurately from a ₁ +a ₂ .

〔Effect of the invention〕

According to the present invention, the following effects can be achieved.

(a) Because it is a non-contact measurement, there is no influence of contact pressure or elastic deformation, allowing for accurate measurement. Furthermore, since the method directly measures the radius, etc., errors are less likely to occur.

(b) Since it is a non-contact measurement, there are no wear points, and the device itself is almost maintenance-free.

(c) Measurements can be made in a short time and with high precision, regardless of the skill level or skill of the worker.

(d) Fully automatic measurement using a computer is possible, and the work required for measurement is simple because the operator only needs to attach and detach tools. In addition, it is possible to automatically determine whether the tool is good or bad, and also to clearly indicate the location of the defect.

(e) The measured values of each part of the tool can be registered directly into the machine tool control computer, and the data necessary for machining can be used online.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the device of the present invention;
FIG. 2 is an enlarged view of a part of the apparatus shown in FIG.
Fig. 3 is a side view showing the movement of the line sensor in Fig. 1 during preliminary measurement, Fig. 4 is a side view showing the movement of the line sensor during main measurement, and Fig. 5 is an embodiment of the method of the present invention. FIG. 6 is a schematic side view illustrating the case of measuring the length of a tool using the device of the present invention, and FIG. 7 illustrates the case of measuring the diameter of a tool using the device of the present invention. FIG. 8 is a side view showing the tip of the tool, and FIG. 9 is a front view of the tip of the tool. DESCRIPTION OF SYMBOLS 1, 1'...Tool, 3...Top spherical part, 10...Measuring device, 11...Tool rotation unit, 12...Tool moving means, 13...Measuring head, 14...Measuring head driving means, 15...Control/calculation section, 27...Line sensor, 28...Light emitter, 29...Light receiver, 30...Measurement area, 30b...One end of the measurement area, 31...Horizontal axis.

Claims (1)

[Claims] 1. A tool rotation unit capable of chucking a rotary tool and rotating the tool by a predetermined angle around an axis, and reciprocating the tool rotation unit in the axial direction of the tool. A measuring head equipped with a tool moving means, a line sensor consisting of a light emitting part and a light receiving part arranged opposite to each other in a direction perpendicular to the axis of the tool, and this measuring head being used as a reference at one end of the measurement area by the line sensor. A measuring head driving means that can be rotated by a predetermined angle around a horizontal axis in a direction perpendicular to the tool axis around a point, and controlling the tool rotation unit, tool moving means, and measuring head driving means. and a control/calculation unit capable of taking measured values from the line sensor and processing the measured values; With the line sensor positioned inside the tip of the tool, rotate the line sensor around the above reference point to set the line sensor at at least three different angles, and rotate the tool once at each angle using the tool rotation unit. After calculating the approximate center position of the circle formed by the cutting edge rotation surface of the tool tip based on the light shielding position of the measurement area at each angle, the tool moving means is moved so that the center of this circle is located at the reference point. Therefore, the tool is moved in the axial direction, and in the subsequent main measurement, the line sensor is rotated around the reference point and set at multiple angles, and at each angle, the tool is rotated by the tool rotation unit. A rotary tool, characterized in that the rotary tool has a control function of calculating the radius of a circle formed by the rotating surface of the cutting edge at the tip of the tool based on the shaded position of the measurement area detected by the line sensor for each angle. measuring device. 2. A method of measuring the radius of a spherical part at the tip of a tool using a measuring head equipped with a line sensor consisting of a light emitting part and a light receiving part arranged facing each other in a direction perpendicular to the axis of the tool, which is carried out first. In the preliminary measurement, with the reference point at one end of the measurement area of the line sensor positioned inside the tip of the tool, the measurement head drive means is used to set the line sensor at at least three different angles. Then, the measuring head is rotated about the horizontal axis in the direction orthogonal to the tool axis around the reference point, and the tool is rotated once at each angle by the tool rotation unit to measure the measurement area at each angle. After calculating the approximate center position of the circle formed by the rotating surface of the cutting edge at the tip of the tool based on the light shielding position, move the tool in the axial direction using the tool moving means so that the center of this circle is located at the above reference point, and then In this measurement, the line sensor is rotated around the horizontal axis around the reference point and set at multiple angles, and the tool is rotated once by the tool rotation unit at each angle. A method for measuring a rotary tool, characterized in that the radius of a circle formed by the rotating surface of the cutting edge at the tip of the tool is calculated based on the light shielding position of the measurement area detected by the line sensor for each angle.