JP3252248B2 - Non-contact diameter measuring device using speckle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a cylindrical or disc-shaped object by utilizing a speckle pattern generated when light having good coherence such as laser light is scattered on a rough surface of the object. The present invention relates to a device for measuring a diameter in a non-contact manner.

[0002]

2. Description of the Related Art Conventionally, an object to be measured is irradiated with a laser beam emitted from a semiconductor laser, and the speckle caused by minute irregularities on the surface is changed with the rotation of the object to be measured. There is known a technique for measuring the diameter of an object to be measured in a non-contact manner based on the amount of displacement of the object.

FIG. 8 shows the measurement principle of a conventional apparatus. When the cylindrical or disc-shaped DUT 1 rotates by an angle θ, the speckle is imaged by the CCD camera 12 in a state of being inclined by an angle 2θ. The speckle displacement X at this time is represented by the following equation. X = ΔS ′ + (L + Δ) tan2θ (1) where L is the distance between the DUT 1 and the CCD camera 12,
Δ is the amount of increase in the distance from the CCD camera 12 due to the rotation of the device 1, and ΔS ′ is the amount of movement in the direction parallel to the light receiving surface of the CCD camera 12 as the device 1 rotates. Also,
The moving distance ΔS of the point A irradiated with the laser light when the DUT 1 is rotated by the angle θ is as follows. ΔS = πD · θ / 360 (2) where D is the diameter of the DUT 1. Furthermore, if the angle θ is small, it can be approximated as in the following equation. ΔS ′ = ΔS (Equation 3) (L + Δ) tan2θ = 2π (L + Δ) · 2θ / 360 (Equation 4) Further, since L >> Δ, it can be approximated as the following equation. L + Δ = L (Equation 5) Accordingly, Equation 1 is expressed as follows from Equations 2, 3, 4, and 5 above. X = (D + 4L) π · θ / 360 (Formula 6) From the above Formula 6, the diameter D of the DUT 1 can be derived by the following formula. D = ((360 · X) / (π · θ))-4L (Equation 7)

[0004]

Since the measurement principle described above calculates the diameter D of the DUT 1 using the above equation (7), the distance L between the DUT 1 and the CCD camera 12 is calculated at this time. Need to be measured. However, when the workpiece 1 is a workpiece for machine tool processing, the distance L always fluctuates due to a change in the diameter D of the workpiece during the processing, so that the diameter D of the workpiece cannot be measured in-process by some conventional apparatuses. There was a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the need to measure the distance between an object to be measured and an image pickup means such as a CCD camera. It is an object of the present invention to provide a speckle-based non-contact diameter measuring device capable of measuring the diameter of a workpiece for machining with high accuracy in-process.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for measuring a diameter of an object to be measured in a non-contact manner using speckles such as a laser beam. The apparatus includes a light source that generates speckles by irradiating a laser beam or the like to a circumferential surface of the device under test, a single imaging unit that receives the generated speckles, and an image capturing unit that performs imaging with respect to the device under test. Means for relative movement, means for measuring the position of the imaging means, means for detecting the rotation angle of the object to be measured, and output of the imaging means when the imaging means is moved to a plurality of positions to rotate the object to be measured Means for calculating the amount of displacement of speckle based on the above and calculating the diameter of the object to be measured.

A non-contact diameter measuring apparatus utilizing speckles according to the second aspect of the present invention includes a light source for generating speckles by irradiating a laser beam or the like to a circumferential surface of an object to be measured, and a speckle-emitting device for generating speckles. A plurality of imaging means for receiving light at different positions from the measurement object, a means for measuring the position of each imaging means, a means for detecting a rotation angle of the measurement object, and a method for rotating the measurement object Means for calculating the speckle displacement amount based on the output of the imaging means and calculating the diameter of the object to be measured.

[0008]

According to the first aspect of the present invention, a plurality of speckle displacement amounts are calculated by moving a single imaging means to a plurality of positions and rotating the object at each position. Since these calculated values accurately specify the distance between the object to be measured and the imaging means, unlike the related art, the diameter of the object to be measured is accurately obtained without depending on the measured value of the distance. In-process measurement of diameter is also possible.

According to the second aspect of the present invention, a plurality of speckle displacements are calculated by a single measurement by rotating a device under measurement with a plurality of imaging means arranged at different positions. Is calculated in a short time based on the calculated value of

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an in-process measuring apparatus for a workpiece diameter in an NC lathe will be described with reference to the drawings. FIG. 1 shows N equipped with the measuring device of the present invention.
It is the schematic which shows the whole structure of C lathe. The measuring device 5 is mounted on a turret 6 of a tool rest 7, driven by a motor 9 via a ball screw 8, and its position is measured by an encoder 10 as position measuring means. In this position measurement, the measuring device 5 can be fixed to a known fixed point by a dog or the like. On the other hand, the workpiece 1 or the work is held by the chuck 2 and rotated by the built-in motor 3, and the rotation angle is detected by the encoder 4 as rotation angle detecting means. In this rotation angle detection, the DUT 1 can be rotated by a known angle using a dog or the like. In the figure, 11
Is an NC device for controlling each part of the NC lathe.

FIG. 2 is an explanatory diagram showing the principle of measurement by the measuring device 5 of the first embodiment. In the figure, reference numeral 12 denotes a CCD camera as an image pickup means, which is stored in the measuring device 5. When measuring the diameter of the DUT 1, first, the DUT 1 is rotated by an angle θ1 at a position 1 where the distance between the DUT 1 and the CCD camera 12 is L, and the CCD camera at that time is rotated. Then, the speckle displacement amount X1 is calculated based on the output of T12. Subsequently, the CCD camera 12 is moved to the position 1 by the ball screw 8 and the motor 9 as relative moving means.
Is moved to a position 2 which is more arbitrarily distanced than above, and the speckle displacement X2 is calculated in the same manner. Then, the distance L between the DUT 1 and the CCD camera 12 is calculated.
Can be expressed by the following equation. L = X1 · / (X2−X1) (Equation 8) Accordingly, from the above Equation 8, the above Equation 7 is as follows. D = ((360 · X1) / (π · θ)) − ((4 ·· X1) / (X2−X1)) (Equation 9) where θ = θ1 = θ2. Since the equation 9 does not include the distance L between the DUT 1 and the CCD camera 12 unlike the equation 7, the diameter D of the DUT 1 is calculated regardless of the measured value of the distance L. can do. The circuit configuration for executing this series of arithmetic processing will be described later.

FIG. 3 is a schematic diagram showing the configuration of the measuring apparatus 5 of the first embodiment. In a position where the distance between the DUT 1 and the CCD camera 12 is L, the light is emitted from a semiconductor laser 13 as a light source. The emitted laser beam passes through the luminous intensity adjustment filter 14 and strikes the half mirror 15 to irradiate the DUT 1 in a different direction. The speckles generated by scattering on the rough surface of the surface of the DUT 1 are received by the CCD camera 12 through the half mirror 15 and the laser wavelength transmission filter 16. Then, the device under test 1 is rotated by the built-in motor 3, and the rotation angle θ1 is detected by the encoder 4,
The speckle displacement X1 at this time is calculated. continue,
The measuring device 5 is moved by a motor 9 via a ball screw 8 by an arbitrary distance, and the device under test 1 is again rotated by the built-in motor 3, and the rotation angle θ2 is detected by the encoder 4, and the speckle displacement at this time is detected. The quantity X2 is calculated, and the diameter D of the DUT 1 is calculated using equation (9).

FIG. 4 is a schematic diagram showing the configuration of the measuring device 5 of the second embodiment. In this case, two CCDs are used as image pickup means.
The cameras 12, 19 are installed at different positions with the light receiving axes orthogonal to each other. The speckles generated in the same manner as in the first embodiment are divided into those that change directions by the half mirror 17 for a long optical path and those that go straight. The speckle which goes straight is CC which is a distance L1 away from the half mirror 17 for long optical path.
The speckles which are received by the D camera 12 and whose direction is changed are received by the long optical path CCD camera 19 which is separated from the long optical path half mirror 17 by an arbitrary distance longer than L1 by a distance L2. Then, the device under test 1 is rotated by the built-in motor 3, the rotation angle θ is detected by the encoder 4, and the speckle displacement amount is calculated based on the outputs of the CCD cameras 12 and 19 at this time. In this way, two speckle displacements X1 and X2 whose optical paths differ only by one measurement can be calculated by one measurement, and the diameter D of the DUT 1 can be calculated in a short time by using the same nine equations as in the first embodiment. be able to. In addition, the measuring device 5 of the first embodiment and the second embodiment calculates the number of processed workpieces,
It can be selected according to the allowable measurement time, cost, and the like.

FIG. 5 is a block diagram showing the configuration of the calculating means in the measuring device 5 of each of the above embodiments. The measuring device 5 incorporates a CCD camera 12 and a first-stage amplifier 21,
The NC device 11 is equipped with a sample-and-hold circuit 22, a gain control amplifier 23, a binarization circuit 24, a correlator 25, and a microcomputer 26 mounted on a common processing board 27.

FIG. 6 is an explanatory view showing an in-process measuring method of the NC lathe. In measuring the diameter of the work, the NC apparatus 11 first inputs the number of processing, the allowable dimension range and the number of measuring operation insertions, and performs the processing. Start. When the number of processing reaches the number of measurement operation insertions, the processing is stopped, and N
A measurement command is output from the C device 11, the turret 6 is turned, and a tool pot with a measuring device to which the measuring device 5 is attached is determined. Next, the semiconductor laser 13 emits laser light, and speckles generated by scattering on the device under test 1 are received by the CCD camera 12.

The CCD camera 12 is connected to a sample-and-hold circuit 22 via a first-stage amplifier 21. Here, a specific noise contained in an output signal of the CCD camera 12 is removed. The output of the sample hold circuit 22 is sent to a binarization circuit 24 via a gain control amplifier 23,
Here, the speckle image signal is binarized, and the binarized signal is sent to the correlator 25, and the cross-correlation between before and after the movement of the speckle accompanying the rotation of the DUT 1 is calculated. The calculation result is sent to the microcomputer 26. The microcomputer 26 calculates the amount of displacement of the speckle from the peak position of the cross-correlation function, and calculates the diameter D of the DUT 1 using the above-mentioned equation.

The calculated diameter D is calculated by the NC unit 11
Is displayed on the NC panel 28, and it is determined whether or not the calculated value is outside the allowable dimension range previously input. If the calculated value is not out of the allowable dimension range, the machining is resumed as it is. If the calculated value is out of the allowable dimension range, the microcomputer 26 calculates the correction value and inputs it to the tool offset in the NC device 11, and then resumes the machining. . Then, when the number of processed pieces reaches the previously input number, the processing is terminated.

The method of measuring the diameter, which does not depend on the measured value of the distance between the object to be measured and the imaging means, is not limited to the disclosed technology of each of the above embodiments, but employs the measuring principle shown in FIG. Is also possible. According to this measurement principle, the center of the DUT 1 (center of the main axis) and the CCD camera 12
The measuring device 5 is set so that the distance from the measuring device 5 is LL. Then, the distance L between the DUT 1 and the CCD camera 12 is calculated.
Can be expressed as: L = LL−D / 2 (Equation 10) Therefore, from the above equation 8, equation 7 is as follows. D = ((360 · X) / (π · θ)) − 4 (LL−D / 2) (Equation 11) In this equation, the distance L between the DUT 1 and the CCD camera 12 is calculated. Since it is not included, the diameter D of the DUT 1 can be obtained without depending on the measured value of the distance L.
The diameter D of the DUT 1 can be measured by one measurement using the same optical system as the first embodiment shown in FIG. However, since the distance LL between the center of the DUT 1 and the CCD camera 12 may change due to thermal displacement of the spindle or the like during processing, when this measurement principle is adopted, the diameter D of the DUT 1 is changed. Before measuring, there is a trouble that a work serving as a reference is measured in advance, and the measured value is corrected with the reference value.

[0019]

As described above in detail, according to the first aspect of the present invention, a plurality of speckles can be obtained by moving a single imaging means to a plurality of positions and rotating the object to be measured at each position. Calculate the amount of displacement, accurately specify the distance between the object to be measured and the imaging means with these calculated values, and can accurately measure the diameter of the object to be measured, regardless of the measured value of the distance. It has an excellent effect that it can be applied to in-process measurement of the workpiece diameter.

According to the second aspect of the present invention, by arranging a plurality of imaging means at different positions and rotating the object to be measured,
There is an effect that a plurality of speckle displacement amounts are calculated by one measurement, and the diameter of the measured object can be measured in a short time based on the calculated values.

[Brief description of the drawings]

FIG. 1 is a schematic view of an NC lathe equipped with a measuring device of the present invention.

FIG. 2 is an explanatory diagram showing a measurement principle of the measurement device of the first embodiment.

FIG. 3 is a schematic diagram showing a configuration of a measuring device of the first embodiment.

FIG. 4 is a schematic diagram illustrating a configuration of a measuring apparatus according to a second embodiment.

FIG. 5 is a block diagram showing a calculating means in the measuring apparatus of the first and second embodiments.

FIG. 6 is an explanatory view showing an in-process measuring method of a workpiece diameter in an NC lathe.

FIG. 7 is an explanatory diagram showing a measurement principle according to the related art of the present invention.

FIG. 8 is an explanatory diagram showing a conventional measurement principle.

[Explanation of symbols]

1 ‥ DUT, 2 ‥ chuck, 3 ‥ built-in motor,
4 ‥ rotation angle detection encoder, 5 ‥ measuring device, 6 ‥ turret, 7 ‥ turret, 8 ‥ ball screw, 9 ‥ motor, 1
0 ° position measuring encoder, 11 ° NC device, 12 ° C
CD camera, 13 ‥ semiconductor laser, 14 ‥ luminosity adjustment filter, 15 ‥ half mirror, 16 ‥ laser wavelength transmission filter, 17 ‥ long optical path half mirror, 18 ‥ long optical path laser wavelength transmission filter, 19 ‥ long optical path CCD camera, 21 ‥ first stage amplifier, 22 ‥ sample hold circuit,
23 ‥ gain control amplifier, 24 ‥ binarization circuit, 25 ‥ correlator, 26 ‥ microcomputer, 27 ‥ processing board, 28 ‥ NC panel.

Claims (2)

(57) [Claims] 1. An apparatus for measuring the diameter of an object to be measured in a non-contact manner using speckles generated by a laser beam or the like, and generating speckles by irradiating a laser beam or the like to a circumferential surface of the object to be measured. A light source to be emitted, a single imaging unit for receiving the generated speckles, a unit for moving the imaging unit relative to the object to be measured, a unit for measuring the position of the imaging unit, and detecting a rotation angle of the object to be measured. Means for calculating the speckle displacement based on the output of the imaging means when the imaging means is rotated by moving the imaging means to a plurality of positions and calculating the diameter of the measurement object. Use non-contact diameter measuring device. 2. An apparatus for measuring the diameter of an object to be measured in a non-contact manner using speckles generated by a laser beam or the like, and generating a speckle by irradiating a laser beam or the like to a circumferential surface of the object to be measured. A light source to be emitted, a plurality of imaging means for receiving the generated speckles at different positions from the object to be measured, a means for measuring the position of each imaging means, and a means for detecting the rotation angle of the object to be measured, A speckle-using non-contact diameter measuring apparatus, comprising: a unit for calculating a speckle displacement amount based on an output of each imaging unit when the device to be measured is rotated and calculating a diameter of the device to be measured.